Compounds targeting tpm1.8 and / or tpm1.9 isoforms for preventing and / or treating cancer

Abstract

The present invention solves the problem of providing novel and improved therapeutic compounds for preventing and / or treating cancer, such as ovarian cancer. The present invention provides compounds targeting TPM1 alternative splicing variants Tpm1.8 and / or Tpm1.9. The compounds or a pharmaceutical composition comprising at least one compound according to the present invention counteracts chemoresistance, such as chemoresistance to taxane- and / or platinum-based chemotherapeutic agents. Further, the present inventions includes a method for identifying compounds targeting Tpm1.8 and / or Tpm1.9 isoforms which have a therapeutic effect in inhibiting, suppressing, preventing and / or treating cancer.

Description

[0001]P135452PC00 Title: COMPOUNDS TARGETING TPM1.8 AND / OR TPM1.9 ISOFORMS FOR PREVENTING AND / OR TREATING CANCER FIELD OF THE INVENTION The present invention relates to the use of compounds targeting the alternative splicing isoforms TPM1.8 and / or TPM1.9 of Tropomyosin 1 (TPM1) in a method of preventing and / or treating cancer. Further, the present invention relates to a method for identifying further compounds which target TPM1.8 and / or TPM1.9 isoforms and are for use in a method of preventing and / or treating cancer. BACKGROUND OF THE INVENTION Phenotypic plasticity, defined as the ability of individual cells with stable genotypes to exert different phenotypes upon exposure to specific environmental cues, represent the quintessential hallmark of the cancer cell en route from the primary lesion to distant organ sites where metastatic colonization will occur. Phenotypic plasticity is driven by a broad spectrum of epigenetic mechanisms that allow for the reversibility of epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions (EMT / MET). Epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial transitions (MET) are thought to underlie local dissemination and distant metastasis in the majority of epithelial malignancies, including ovarian cancer where the absence of a physical barrier between primary and metastatic sites would suggest alternative shedding mechanisms. EMT / MET are regulated by a broad spectrum of epigenetic mechanisms involving chromatin remodeling due to histone methylation / acetylation, non-coding RNAs, promoter DNA methylation, and post-transcriptional mechanisms such as alternative splicing (AS). Metastasis is responsible for the greatest number of cancer deaths. Metastatic disease, or the movement of cancer cells from one site to another, is a complex process requiring dramatic remodelling of the cell cytoskeleton. The various components of the cytoskeleton, actin (microfilaments), microtubules (MTs) and intermediate filaments, are highly integrated and their functions are well orchestrated in normal cells. Ovarian cancer is the most lethal gynecological cancer but early stages of ovarian cancer do not show any noteworthy symptoms. Most ovarian cancer patients present with disseminated disease at the time of their diagnosis, and a majority of patients will be treated for metastatic disease, which is one of the main reasons for the poor prognosis of ovarian cancer. There is a need for better insight in the process of cancer metastasis. As an actin-binding proteins, tropomyosins play an important role in metastatic disease and are commonly downregulated upon cell transformation and dedifferentiation in cancer development. Of the various epigenetic mechanisms, AS of tropomyosins may play a role in regulating EMT / MET in cancer metastasis. The tropomyosin 1 (TPM1) gene encodes various AS isoforms. The present inventors set out to investigate if alternative splicing isoforms of TPM1 could be therapeutic targets for the treatment of cancer. The present invention solves the problem of providing novel compounds for use in preventing and / or treating cancer, such as ovarian cancer. SUMMARY OF THE INVENTION Unexpectedly, the inventors of the present invention have discovered that the two isoforms Tpm1.8 and Tpm1.9 of the Tropomyosin 1 gene (TPM1) provide a novel and promising target for preventing and / or treating cancer, such as ovarian cancer. Without wishing to be bound by theory, it is believed that Tpm1.8 and / or Tpm1.9 represent specific isoforms which are involved in EMT activation through multiple signaling pathways including Wnt, TGF-β, Hedgehog, and Notch. Further, because of their localization to the lamellipodia and functional role in cell motility, the Tpm1.8 / 9 isoforms are likely to facilitate dissemination from the primary tumor to the intra-abdominal cavity. The Examples and Figures herein below show, inter alia, that the Tpm1.8 / 9 isoforms are a promising target for preventing and / or treating cancer, such as ovarian cancer. Further, it is shown that the compounds of the present invention targeting Tpm1.8 and / or Tpm1.9 isoforms are for use in preventing and / or treating cancer, such as ovarian cancer. The inventors further found up- and downregulation of RBM4 and ESRP1, respectively, in CD44hiEpCAMlocells in immortalized high-grade serous ovarian cancer (HGSOC) cell lines OV90, SKOV3, COV504, and CAOV3 by FACS with CD44 and EpCAM antibodies. Such CD44hiEpCAMlocells showed a mesenchymal-like morphology, in contrast with the epithelial appearances of their CD44hiEpCAMhicounterparts, whereby CD44hiEpCAMlocells showed increased migration and invasion capacity. Moreover, the TPM1 alternative slicing (AS)-pattern observed in ovarian cancer involved exons 1a / 2a, which earmark the Tpm1.6 / 7 isoforms upregulated in CD44hiEpCAMhicells, and exon 1b, featuring the Tpm1.8 / 9 isoforms upregulated in CD44hiEpCAMlocells as validated both by RT-qPCR and western blot analysis. As a further validation of these results, HGSOC cell lines exclusively encompassing CD44hiEpCAMhicells solely expressed the Tpm1.6 / 7 isoforms, whereas CD44hiEpCAMlocells solely expressed the Tpm1.8 / 9 isoforms. Further analysis showed that alternative splicing driven by RBM24 and ESRP1 up- and down-regulation, respectively, is a main regulator of EMT in ovarian cancer cells. The compounds of the present invention target the N-terminus of Tpm1.8 and / or Tpm1.9 at residues 4 – 16. The compounds of the present invention targeting Tpm1.8 and / or Tpm1.9 isoforms may counteract chemoresistance, preferably chemoresistance against taxane- and / or platinum-based chemotherapy. Further, the compounds of the present invention targeting Tpm1.8 and / or Tpm1.9 isoforms has an activity in a low micromolar range, preferably wherein the compound has an activity in a range of from 5 – 50 µM, more preferably wherein the compound has an activity in a range of from 5 – 20 µM. The compounds of the present invention targeting Tpm1.8 and / or Tpm1.9 isoforms may prevent Tpm1.8 and / or Tpm1.9 isoform enrichment in the lamellipodium. Therefore, the present invention provides in a first aspect a compound that is an inhibitor of Tropomyosin 1 alternative splicing isoforms Tpm1.8 and / or Tpm1.9, wherein the compound is selected from - a small molecule inhibitor selected from 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468), and pharmaceutically acceptable salts, hydrates, derivates, solvates or prodrugs thereof; - an antisense polynucleotide which decreases the expression of Tropomyosin 1 isoform 1.8 and / or 1.9 (Tpm1.8 or 1.9), and - an antibody which decreases Tpm1.8 and / or 1.9 polypeptide levels and / or Tpm1.8 or 1.9 polypeptide activity. In a further aspect, the present invention provides the compound according to the invention as indicated above for use in a method of preventing and / or treating cancer. In a preferred embodiment of the invention the cancer expresses TPM1 alternative splicing isoforms, more preferably the cancer expresses TPM1 alternative splicing isoforms of TPM1 Exon 1b. Optionally, the cancer is selected from acute myeloid leukemia (AML), adrenocortical carcinoma, bladder urothelial carcinoma, brain lower grade carcinoma, breast invasive carcinoma, cervical squamous cell carcinoma and endocervical adenocarcinoma, cholangiocarcinoma, colon adenocarcinoma, esophageal carcinoma, glioblastoma multiforme, head and neck squamous cell carcinoma, kidney chromophobe, kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, lung squamous cell carcinoma, lymphoid neoplasm diffuse large B-cell lymphoma, mesothelioma, ovarian cancer in particular ovarian serous cancer, pancreatic adenocarcinoma, rectum adenocarcinoma, sarcoma, skin cutaneous melanoma, stomach adenocarcinoma, testicular germ cell tumors, thymoma, thyroid carcinoma, uterine carcinosarcoma, uterine corpus endometrial carcinoma, uveal melanoma, or combinations thereof. The cancer which is treated by the use of the compounds of the invention is ovarian cancer, preferably epithelial ovarian cancer (EOC), more preferably wherein the cancer is high-grade serous ovarian cancer. In another embodiment of the present invention, the compound is administered in combination with an additional anti-cancer therapeutic agent. In another embodiment of the present invention, the compound is administered in combination with an additional anti-cancer therapy. Preferably the additional anti- cancer therapy is selected from a group consisting of chemotherapy, targeted therapy such as immunotherapy, stem cell therapy, hormone therapy, radiation therapy and surgery, and a combination thereof. More preferably, the additional anti-cancer therapy is a chemotherapy, for example a taxane- and / or platinum-based chemotherapy, such as a chemotherapy comprises cisplatin- and / or paclitaxel. In embodiments of the present invention, the administration of said compound to a subject may occur at a dose of between 0.1 and 100 mg / kg. The embodiments directed to the compounds of the present invention and its medical use in treating cancer also apply to a pharmaceutical composition comprising the compound. In a preferred embodiment, the pharmaceutical composition comprises a pharmaceutically acceptable carrier. Further, the embodiments directed to the use of compounds and the pharmaceutical compositions also apply to methods of inhibiting, suppressing, preventing and / or treating cancer, comprising administering to a subject in need thereof a therapeutically effective amount of said compound or said pharmaceutical composition. In another aspect, the present invention provides a method of identifying a compound targeting Tpm1.8 and / or Tpm1.9 isoforms for inhibiting, suppressing, preventing and / or treating proliferation, motility, invasion, migration, metastasis and / or chemo-resistance of a cancer, comprising: a) contacting a cancer cell that expresses Tpm1.8 and / or Tpm1.9 isoforms with a test compound, and b) measuring in said cancer cell the inhibition of Tpm1.8 and / or Tpm1.9 expression and / or activity, wherein the finding of an inhibitory effect identifies the test compound as a compound for use in a method of inhibiting, suppressing, preventing and / or treating cancer. In another aspect, the present invention provides an antisense polynucleotide which decreases the expression of Tropomyosin1 isoform 1.8 or 1.9 (Tpm1.8 or 1.9) or an antibody which decreases Tpm1.8 or 1.9 polypeptide levels and / or Tpm1.8 or 1.9 polypeptide activity, for use in a method of inhibiting, suppressing, preventing or treating proliferation, motility, invasion, migration, metastasis or chemo-resistance of a cancer. In a further aspect, the present invention provides a method of inhibiting, suppressing, preventing or treating proliferation, motility, invasiveness, dissemination, migration, metastasis or chemo-resistance of a cancer, comprising administering to a subject in need thereof a therapeutically effective amount of an antisense polynucleotide which decreases the expression of Tropomyosin 1 isoform 1.8 or 1.9 (Tpm1.8 or 1.9) or an antibody which decreases Tpm1.8 or 1.9 polypeptide levels and / or TPM1.8 or 1.9 polypeptide activity. In another aspect, the present invention provides a method for determining the presence of epithelial-to-mesenchymal transition (EMT) in cancer cells, comprising determining Tpm1.8 and or Tpm1.9 expression in said cells, whereby an increased expression relative to a control expression indicates EMT in said cells. The invention also provides a use of a compound targeting Tpm1.8 and / or Tpm1.9 isoforms for the manufacture of a medicament for preventing and / or treating cancer in a subject. The invention further provides use of RBM24 and / or ESRP1 and / or Tpm1.8 / 9 as markers for determining cancer development, in particular for determining if and / or indicating that a cancer cell, preferably an ovarian cancer cell, is in epithelial-to- mesenchymal transition, is a metastatic cell, is (capable of) causing metastases, or is metastasizing, or is resistant against taxane- and / or platinum-based therapies. DESCRIPTION OF THE DRAWINGS Figure 1: The RBPs ESRP1 and RBM24 synergistically regulate TPM1 alternative splicing. (A) RT-qPCR (histogram panels) and western (lower panel) analysis of ESRP1, RBM24, and TPM1 isoform expression in RBM24-OE (overexpressing) and shESRP1-KD (knockdown) OV90 and COV504 ovarian cancer cell line (Means±SEM, n=3). β-actin was used as loading control for western blots. (B) RT-qPCR (histogram panels) and western (lower panel) analysis of ESRP1, RBM24, and TPM1 isoform expression in ESRP1-OE (overexpressing) and shRBM24-KD (knockdown) OV90 and COV504 ovarian cancer cell line (Means±SEM, n=3). β-actin was used as loading control for western blots. Figure 2: Ectopic expression of Tpm1.6 / 7 and Tpm1.8 / 9 isoforms results in increased migration and invasion and decreased cell proliferation. (A) RT-qPCR analysis of OV90, COV504, PEA1, and PEA2 ovarian cancer cell lines transduced to ectopically express the Tpm1.6 / 7-OE and Tpm1.8 / 9-OE isoforms (Means±SEM, n=3). P values are relative to the comparison with the parental cell lines. (B) Western analysis of OV90, COV504, PEA1, and PEA2 ovarian cancer cell lines transduced to ectopically express the Tpm1.6 / 7-OE and Tpm1.8 / 9-OE isoforms. β-actin was employed as loading control. (C) Proliferation assays of OV90, COV504, PEA1, and PEA2 ovarian cancer cell lines transduced to ectopically express the Tpm1.6 / 7-OE and Tpm1.8 / 9-OE isoforms. O.D. values are shown from day 1 to 6 (Means±SEM, 697 n=3). P values are relative to the comparison with the parental cell lines. (D) Transwell migration assay of OV90, COV504, PEA1, and PEA2 ovarian cancer cell lines transduced to ectopically express the Tpm1.6 / 7-OE and Tpm1.8 / 9-OE isoforms.5×104cells were plated on TC-coated membranes and left O / N. The number of cells that migrated to the lower side of the membrane were counted and plotted (Means±SEM, n=3). P values are relative to the comparison with the parental cell lines. (E) Confocal images of OV90 and COV504 parental and Tpm1.6 / 7 / 8 / 9-OE cells seeded on collagen layers and incubated for 6 days. As indicated by the arrows, Tpm1.8 / 9-OE cells appear to invade the collagen layer collectively as narrow linear strands with “leader” and “follower” cells. Scale bar: 250 μm. The number of cells invading the collagen was quantified and plotted (Means±SEM, n=3). P values are relative to the comparison with the parental cell lines. Plots relative to the PEA1 and PEA2 ovarian cancer cell lines were also calculated (bottom). (F) Immunofluorescence analysis of OV90, COV504, PEA1 and PEA2 parental cells with antibodies directed against ARP2, Tpm1.6 / 7 and Tpm1.8 / 9. Nuclei were visualized by DAPI staining of DNA. Scale bar: 5 μm. Figure 3: RNAseq analysis revealed TPM1 isoforms function in Wnt pathway and contribute to metastasis in vivo. (A) Hallmarks pathways based on the Gene Set Enrichment Analysis (GSEA) of parental and Tpm1.6 / 7 / 8 / 9-OE OV90 cells. The heatmap only includes significantly altered pathways, with NES >1, and P value <0.05. (B) Volcano plots showing differentially expressed genes between Tpm1.6 / 7-OE (left, green) and Tpm1.8 / 9-OE (pink, right) OV90 cells (abs LFC >1.5, P value <0.01). (C) TOP-Flash luciferase reporter analysis of Wnt signaling activity in Tpm1.6 / 7 / 8 / 9-OE (upper histogram) and upon knockdown by siRNA of Tpm1.6 / 7 and Tpm1.8 / 9 in OV90 cells. P values are relative to the comparison with the parental cell lines (Means±SEM, n=3). Figure 4: Tpm1.8 / 9 isoforms are enriched in malignant ascites from ovarian cancer cells and confer resistance to platinum- and taxane-based therapies. (A) Examples of IHC (left panels) and ISH (BaseScope; right panels) analyses of patient- derived ovarian cancers with antibodies (IHC) and oligonucleotides probes (ISH) specific for the Tpm1.6 / 7 and Tpm1.8 / 9 isoforms. Ovarian cancer tissues were obtained from a primary tumor and a metastasis (without chemotherapy). Scale bar: 100 μm and 15 μm (inlets) for IHC; 20 μm and 5 μm (inlets) for ISH. (B) RT-qPCR analysis of Tpm1.6 / 7 and Tpm1.8 / 9 expression in OV90 cells exposed to cisplatin and paclitaxel cells (Means±SEM, n=3). (C) Dose-response curves relative to Tpm1.6 / 7 / 8 / 9-OE cells grown in the presence of different concentrations of paclitaxel and cisplatin (log scale and cell viability on the x and y axis, respectively). IC50 values were calculated from technical triplicates for each experiment (Means±SEM, n=3). (D) RT-qPCR (left histogram panels) and western (right) analysis of TPM1 isoform expression in siTpm1.6 / 7 and siTpm1.8 / 9 knockdown OV90 cells (Means±SEM, n=3). β-actin was employed as loading control for the western blots. (E) Dose-response curves of siTpm1.6 / 7 and siTpm1.8 / 9 knockdown OV90 cells cultured in the presence of different concentrations of paclitaxel (left) and cisplatin (right) concentrations (log scale and cell viability on the x and y axis, respectively). IC50 values were calculated from technical triplicates for each experiment (Means±SEM, n=3). Figure 5: Small molecule inhibitors directed against Tpm1.8 / 9 isoforms antagonize their effects on EMT, Wnt signaling, and resistance to chemotherapy. (A) Upper panels: RT-qPCR analysis of TPM1 isoforms and EMT-related gene expression in OV90 parental cells cultured for 24 h in the presence of 3-(2-Methyl-indol-1-yl)- propylamine (PubChem CID 6494468) (indicated as Cp-1) and 1-Phenylmethyl-1h- indole-2-methanol (PubChem CID 18973468) (indicated as Cp-3) at 0, 2, 5, and 10 μM. The values were calculated by normalizing with the untreated cells. P values < 0.05 are shown by red bars while grey bars indicate lower values (Means±SEM, n=3). Lower panels: western analysis of TPM1 isoform expression in OV90 parental cells cultured for 24 h in the presence of 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) (indicated as Cp-1) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468) (indicated as Cp-3) at 0, 2, 5, and 10 μM. β-actin was used as loading control for western blots. (B) RT-qPCR analysis of TPM1 isoforms and EMT-related gene expression in OV90 EpCAMlocells cultured for 24 h in the presence of 3-(2-Methyl-indol-1-yl)- propylamine (PubChem CID 6494468) (indicated as Cp-1) and 1-Phenylmethyl-1h- indole-2-methanol (PubChem CID 18973468) (indicated as Cp-3) at 0, 2, 5, and 10 μM. The values were calculated by normalizing with the untreated cells. P values < 0.05 are shown by red bars while grey bars indicate lower values (Means±SEM, n=3). Lower panels: western analysis of TPM1 isoform expression in OV90 EpCAMlocells cultured for 24 h in the presence of 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) (indicated as Cp-1) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468) (indicated as Cp-3) at 0, 2, 5, and 10 μM. β-actin was used as loading control for western blots. (C) Dose-response curves of parental OV90 cells treated with 3-(2-Methyl-indol-1- yl)-propylamine (PubChem CID 6494468) (indicated as Cp-1) and 1-Phenylmethyl-1h- indole-2-methanol (PubChem CID 18973468) (indicated as Cp-3) in the presence of different paclitaxel and cisplatin concentrations. IC50 values were calculated from technical triplicates for each experiment (Means±SEM, n=3). (D) Dose-response curves of OV90 EpCAMlocells treated with 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) (indicated as Cp-1) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468) (indicated as Cp-3) in the presence of different paclitaxel and cisplatin concentrations. IC50 values were calculated from technical triplicates for each experiment (Means±SEM, n=3). (E) TOP-Flash luciferase reporter analysis of Wnt signaling activity in OV90 parental (left panel) and EpCAMlo(right panel) cells treated with 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) (indicated as compound-1) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468) (indicated as compound-3) (Means±SEM, n=3). Figure 6: Small molecule inhibitor directed against Tpm1.8 / 9 isoforms antagonize resistance to chemotherapy in a breast cancer cell line. (A) Dose-response curves of MCF-7 breast cancer cells treated with 1-Phenylmethyl-1h- indole-2-methanol (PubChem CID 18973468) (indicated as 189-3) in the presence of different paclitaxel concentrations. Compound 189-3 was added at a concentration of 5 uM and 10uM. (B) Combined dose-response curves of all three conditions shown in (A). IC50 values were calculated from technical triplicates for each experiment. Addition of compound 189-3 resulted in an increased sensitivity of MCF-7 cells to Paclitaxel.DETAILED DESCRIPTION OF THE INVENTION Definitions The term “TPM1”, as used herein, is a gene (geneID:7168 in humans) that is a member of the tropomyosin family of highly conserved, widely distributed actin-binding proteins involved in the contractile system of striated and smooth muscles and the cytoskeleton of non-muscle cells. Tropomyosin is composed of two alpha-helical chains arranged as a coiled-coil. It is polymerized end to end along the two grooves of actin filaments and provides stability to the filaments. The encoded protein is one type of alpha helical chain that forms the predominant tropomyosin of striated muscle, where it also functions in association with the troponin complex to regulate the calcium- dependent interaction of actin and myosin during muscle contraction. In smooth muscle and non-muscle cells, alternatively spliced transcript variants encoding a range of isoforms have been described. TPM1 is known to have 39 transcripts (splice variants). Variants Tpm1.8 (formerly known as Tm5a) and Tpm1.9 (formerly known as Tm5b) contain alternate in-frame exons in the 5' and 3' coding region compared to variant Tpm1.1. For a schematic representation of the intron / exon organization of the mammalian TMP1 gene, reference is made to Schevzov et al. 2011 (Bioarchitecture 1(4): 135–164), which is herein incorporated by reference, and in particular to Figure 1 as shown therein. These variants encode (protein) isoforms Tpm1.8cy and Tpm1.9cy, respectively, which have distinct N- and C-termini and are shorter than isoform Tpm1.1st. Variants Tpm1.8 (Human: NP_001288218.1, Mouse: NP_001157724.1, Rat: NP_001029245.1) and Tpm1.9 (Human: NP_001317273.1, Mouse: NP_001157725.1, Rat: NP_001029246.1) encode TPM1 isoforms that are of the same length (248 aa), but have distinct protein sequences (Geeves, et al., 2015 J Muscle Res Cell Motil 36, 147-153). The accession numbers are from July 2023 and for full-length human, mouse, and rat sequences that have been documented at the nucleic acid level. Table 1. Protein and mRNA sequences of Tpm1.8 and Tpm1.9 Tropomyosin alpha-1 chain isoform Tpm1.8cy [Homo sapiens] Protein MAGSSSLEAVRRKIRSLQEQADAAEERAGTLQRELDHERKLRETAEADVASLNRR IQLVEEELDRAQERLATALQKLEEAEKAADESERGMKVIESRAQKDEEKMEIQEI (NP_001288218.1) QLKEAKHIAEDADRKYEEVARKLVIIESDLERAEERAELSEGKCAELEEELKTVT NNLKSLEAQAEKYSQKEDRYEEEIKVLSDKLKEAETRAEFAERSVTKLEKSIDDL EEKVAHAKEENLSMHQMLDQTLLELNNM mRNA 1 agccaggaca gccgcggcag ccgggtccgc agggcagcag ccggcctctc ccactgcagc (NM_001301289.2) 61 cctcccgccc gcctaccgtc cggcgcgatg gcggggagta gctcgctgga ggcggtgcgc 121 aggaagatcc ggagcctgca ggagcaggcg gacgccgctg aggagcgcgc gggcaccctg 181 cagcgcgagc tggaccacga gaggaagctg agggagaccg ctgaagccga cgtagcttct 241 ctgaacagac gcatccagct ggttgaggaa gagttggatc gtgcccagga gcgtctggca 301 acagctttgc agaagctgga ggaagctgag aaggcagcag atgagagtga gagaggcatg 361 aaagtcattg agagtcgagc ccaaaaagat gaagaaaaaa tggaaattca ggagatccaa 421 ctgaaagagg ccaagcacat tgctgaagat gccgaccgca aatatgaaga ggtggcccgt 481 aagctggtca tcattgagag cgacctggaa cgtgcagagg agcgggctga gctctcagaa 541 ggcaaatgtg ccgagcttga agaagaattg aaaactgtga cgaacaactt gaagtcactg 601 gaggctcagg ctgagaagta ctcgcagaag gaagacagat atgaggaaga gatcaaggtc 661 ctttccgaca agctgaagga ggctgagact cgggctgagt ttgcggagag gtcagtaact 721 aaattggaga aaagcattga tgacttagaa gagaaagtgg ctcatgccaa agaagaaaac 781 cttagtatgc atcagatgct ggatcagact ttactggagt taaacaacat gtgaaaacct 841 ccttagctgc gaccacattc tttcgttttg ttttgttttg tttttaaaca cctgcttacc 901 ccttaaatgc aatttattta cttttaccac tgtcacagaa acatccacaa gataccagct 961 aggtcagggg gtggggaaaa cacatacaaa aaggcaagcc catgtcaggg cgatcctggt 1021 tcaaatgtgc catttcccgg gttgatgctg ccacactttg tagagagttt agcaacacag 1081 tgtgcttagt cagcgtagga atcctcacta aagcagaaga agttccattc aaagtgccaa 1141 tgatagagtc aacaggaagg ttaatgttgg aaacacaatc aggtgtggat tggtgctact 1201 ttgaacaaaa ggtccccctg tggtcttttg ttcaacattg tacaatgtag aactctgtcc 1261 aacactaatt tattttgtct tgagttttac tacaagatga gactatggat cccgcatgcc 1321 tgaattcact aaagccaagg gtctgtaagc cacgctgctc ttccgagact tccattcctt 1381 tctgattggc acacgtgcag ctcatgacaa tctgtaggat aacaatcagt gtggatttcc 1441 actcttttca gtccttcatg ttaaagattt agacaccaca tacaactggt aaaggacgtt 1501 ttcttgagag ttttaactat atgtaaacat tgtataatga tatggaataa aatgcacatt 1561 gtaggacatt ttctaaa / / Tropomyosin alpha-1 chain isoform Tpm1.9cy [Homo sapiens] Protein MAGSSSLEAVRRKIRSLQEQADAAEERAGTLQRELDHERKLRETAEADVASLNRR IQLVEEELDRAQERLATALQKLEEAEKAADESERGMKVIESRAQKDEEKMEIQEI (NP_001317273.1) QLKEAKHIAEDADRKYEEVARKLVIIESDLERAEERAELSEGQVRQLEEQLRIMD QTLKALMAAEDKYSQKEDRYEEEIKVLSDKLKEAETRAEFAERSVTKLEKSIDDL EEKVAHAKEENLSMHQMLDQTLLELNNM mRNA 1 agccaggaca gccgcggcag ccgggtccgc agggcagcag ccggcctctc ccactgcagc (NM_001330344.2) 61 cctcccgccc gcctaccgtc cggcgcgatg gcggggagta gctcgctgga ggcggtgcgc 121 aggaagatcc ggagcctgca ggagcaggcg gacgccgctg aggagcgcgc gggcaccctg 181 cagcgcgagc tggaccacga gaggaagctg agggagaccg ctgaagccga cgtagcttct 241 ctgaacagac gcatccagct ggttgaggaa gagttggatc gtgcccagga gcgtctggca 301 acagctttgc agaagctgga ggaagctgag aaggcagcag atgagagtga gagaggcatg 361 aaagtcattg agagtcgagc ccaaaaagat gaagaaaaaa tggaaattca ggagatccaa 421 ctgaaagagg ccaagcacat tgctgaagat gccgaccgca aatatgaaga ggtggcccgt 481 aagctggtca tcattgagag cgacctggaa cgtgcagagg agcgggctga gctctcagaa 541 ggccaagtcc gacagctgga agaacaatta agaataatgg atcagacctt gaaagcatta 601 atggctgcag aggataagta ctcgcagaag gaagacagat atgaggaaga gatcaaggtc 661 ctttccgaca agctgaagga ggctgagact cgggctgagt ttgcggagag gtcagtaact 721 aaattggaga aaagcattga tgacttagaa gagaaagtgg ctcatgccaa agaagaaaac 781 cttagtatgc atcagatgct ggatcagact ttactggagt taaacaacat gtgaaaacct 841 ccttagctgc gaccacattc tttcgttttg ttttgttttg tttttaaaca cctgcttacc 901 ccttaaatgc aatttattta cttttaccac tgtcacagaa acatccacaa gataccagct 961 aggtcagggg gtggggaaaa cacatacaaa aaggcaagcc catgtcaggg cgatcctggt 1021 tcaaatgtgc catttcccgg gttgatgctg ccacactttg tagagagttt agcaacacag 1081 tgtgcttagt cagcgtagga atcctcacta aagcagaaga agttccattc aaagtgccaa 1141 tgatagagtc aacaggaagg ttaatgttgg aaacacaatc aggtgtggat tggtgctact 1201 ttgaacaaaa ggtccccctg tggtcttttg ttcaacattg tacaatgtag aactctgtcc 1261 aacactaatt tattttgtct tgagttttac tacaagatga gactatggat cccgcatgcc 1321 tgaattcact aaagccaagg gtctgtaagc cacgctgctc ttccgagact tccattcctt 1381 tctgattggc acacgtgcag ctcatgacaa tctgtaggat aacaatcagt gtggatttcc 1441 actcttttca gtccttcatg ttaaagattt agacaccaca tacaactggt aaaggacgtt 1501 ttcttgagag ttttaactat atgtaaacat tgtataatga tatggaataa aatgcacatt 1561 gtaggacatt ttctaaa / / The terms “Tpm1.8 and / or Tpm1.9 isoforms” and “Tpm1.8 / 9 isoforms”, as used interchangeably herein, refer to alternative splicing products of the TPM1 gene, and may refer to either nucleic acid transcripts ((m)RNA) or polypeptide (protein) translation products thereof. The term “inhibitor” as used herein, refers to a compound targeting Tpm1.8 and / or Tpm1.9 isoforms, wherein the Tpm1.8 and / or Tpm1.9 isoforms may either be in the form of DNA, mRNA or protein, and whereby the inhibitor decreases the transcriptional expression of Tropomyosin 1 isoforms Tpm1.8 and / or Tpm1.9 and / or decreases Tpm1.8 and / or Tpm1.9 polypeptide levels and / or Tpm1.8 and / or Tpm1.9 polypeptide activity. An inhibitor that decreases Tpm1.8 and / or Tpm1.9 polypeptide activity may for example be a small molecule inhibitor, preferably a small molecule inhibitor as disclosed herein. Another exemplary inhibitor that decreases Tpm1.8 and / or Tpm1.9 polypeptide activity may be a Tpm1.8 and / or Tpm1.9 antibody. An inhibitor that decreases Tpm1.8 and / or Tpm1.9 mRNA or polypeptide levels may for example be an antisense polynucleotide. Suitable antisense polynucleotides include synthesized single- stranded nucleic acids (20 to 30 nucleotides in length, e.g. oligonucleotides) in the form of antisense oligonucleotides (ASO), or small interfering RNA (siRNA) as the cleavage product of double-stranded RNA (dsRNA). An exemplary siRNA target sequence for human Tpm1.8 / 9 is 5’-CGAGAGGAAGCTGAGGGAGAC-3’ (codons 38-44 of Tpm1.8 / 9 in exon 1b). It is within the competence of one of skill in the art to produce such antisense polynucleotides for post-transcriptional gene silencing. The term “tumor”, as used herein, includes reference to an abnormal growth of tissue that may be benign, pre-cancerous, malignant, or metastatic. The tumor is preferably malignant, i.e., a cancer. The term "cancer" as used herein refers to any malignant neoplasm resulting from the undesired growth, the invasion, and under certain conditions metastasis of impaired cells in an organism. Examples of cancers include, but are not limited to, breast cancer, prostate cancer, ovarian cancer, such as ovarian epithelial cancer, cervical cancer, skin cancer, pancreatic cancer, spleen cancer, colorectal cancer, renal cancer, liver cancer, brain cancer, lymphoma, leukemia such as acute myeloid leukemia (AML), Hodgkin lymphoma, non-Hodgkin lymphoma, lymph nodes cancer, bone marrow cancer, lung cancer, stomach cancer, eye cancer and the like. The terms “treatment” and “treating”, as used herein, include reference to the application of a form of therapy to a subject, with the object of e.g. curing the patient from a disease such as cancer, halting or slowing down the development of a disease such as cancer, prolonging the life of a subject, or relieving pain in a subject suffering from a disease, such as cancer. Prophylactic treatment, therapy with the aim of preventing induction or onset of a disease, such as cancer, is also to be understood to be part of the term “treatment”. The terms “prevention” and “preventing”, as used herein, includes reference to the application of a form of therapy to a subject, with the object to hinder the outbreak of a disease, such as cancer. The terms refer to the application of a form of therapy to a subject to prevent and / or reduce the likelihood of an occurrence of a disease, such as cancer. The terms include proactive and prophylactic treatment and / or application of an active component in order to hinder outbreak of a disease, such as cancer and / or to immunize the subject. The terms “compound”, “active compound” and “active component”, as used herein, refer to an ingredient, drug, and / or molecule, such as a small molecule, which is able to trigger, exert and / or facilitate a therapeutic effect in a subject. The term “subject”, as used herein, refers to a human or animal suffering from and / or susceptible to cancer. The term “subject”, as used herein, includes reference to a recipient of a compound or a pharmaceutical composition targeting Tpm1.8 and / or Tpm1.9 as described herein, i.e. a subject that is suffering, or suspected of suffering, from cancer, such as ovarian cancer. For example, “subject” includes subjects in which a cancer is prevented. For example, the subject is a mammal, more preferably a human. The terms “patient” and “subject” can be used interchangeably herein. The subject is for example a human, i.e., a human having cancer and / or at risk getting cancer. The subject is for example older or younger than 50 years old. For example the subject is older than 50 years old. For example, the subject is human suffering from cancer. For example the subject is male or female. For example, the subject is a female human suffering from ovarian cancer such as epithelial ovarian cancer. For example, the subject is a human suffering from breast cancer. The term “resistance”, as used herein, includes reference to the ability of cancer cells to at least partially withstand one or more anti-cancer therapies, particularly one or more chemotherapies. In other words, resistance refers inter alia to a reduced efficacy of an anti-cancer therapeutic agent to treat a subject having a cancer. When the anti- cancer therapeutic agent is a chemotherapeutic agent, the resistance is referred to as “chemoresistance”. When reference to a resistance of a cancer is made, it preferably refers to a resistance of cancer cells of said cancer to said anti-cancer therapeutic agent. For example, chemoresistance against cisplatin- and / or paclitaxel. As an alternative to using the term “resistance” such as in “chemoresistance” and counteracting it in the medical use / methods of the invention, one could instead refer to restoring sensitivity to therapy, such as restoring chemosensitivity. Hence, the phrase “counteracting a (chemo)resistance can be used interchangeably with the phrase “restoring (chemo)sensitivity”. The term “restoring”, as used herein in relation to restoring chemosensitivity, includes reference to at least partial, such as complete, restoration of chemosensitivity of cancer to an anti-cancer therapeutic agent it was previously at least partially insensitive to. The term “therapeutically effective amount”, as used herein, means that the amount of active ingredients administered is of sufficient quantity to achieve the intended purpose, such as, in this case, to prevent and / or treat cancer, such as ovarina cancer. This means for example to prevent proliferation, motility, invasion, migration, metastasis or chemo-resistance. The term “administration”, as used herein, includes reference to the application of a substance, compound, and / or pharmaceutical composition to a subject. Main routes of administration are parenteral administration, enteral or gastrointestinal administration and topical administration. The term “parenteral”, as used herein, includes reference to any form of administration that is not via the application onto the skin or via the gastrointestinal tract. Non-limiting examples of parenteral administration include epidural, intracerebral, intracerebroventricular, epicutaneous, sublingual, extra- amniotic, nasal, intra-arterial, intra-articular, intracardiac, intracavernous, intradermal, intralesional, intramuscular, intraocular, intraosseous, intraperitoneal, intrathecal, intrauterine, intravaginal, intravenous, intravesical, intravitreal, subcutaneous, transdermal, perivascular, transmucosal, rectal or intratumoral administration. The term “intravenous”, as used herein, includes reference to a parenteral route of administration wherein a substance or composition is injected into the vein of a subject, for example using a hollow needle. The substance or composition that is administered intravenously will directly reach the blood stream of the subject. The term “intratumoral”, as used herein, includes reference to administration of a substance or composition directly into a tumor, for example using a hollow needle. The tumor wherein intratumoral administration takes place may be treated prior to administration, for example in order to improve visibility of the tumor. Intratumoral administration may for example be used for the administration of anti-cancer therapeutic agents. The term “chemotherapeutic agent”, as used herein, includes reference to an anti- cancer drug that is used as part of a chemotherapy, which is a type of cancer treatment. A chemotherapeutic agent has for example a cytotoxic effect and / or a cytostatic effect, and it is for example used to cure a subject from cancer, to reduce symptoms in a subject, or to prolong the life of a subject. Non-limiting examples of a chemotherapeutic agent include Cyclophosphamide, Mechlorethamine, Chlorambucil, Melphalan, Dacarbazine, Nitrosoureas, Temozolomide, Daunorubicin, Doxorubicin, Epirubicin, Idarubicin, Mitoxantrone, Valrubicin, Cabazitaxel, Larotaxel, Ortataxel, Tesetaxel, Paclitaxel, Docetaxel, Abraxane, Taxotere, Epothilone A, Epothilone B, Epothilone C, Epothilone D, Epothilone E, Epothilone F, Vorinostat, Romidepsin, Irinotecan, Topotecan, Etoposide, Teniposide, Tafluposide, Bortezomib, Erlotinib, Gefitinib, Imatinib, Vemurafenib, Vismodegib, Azacitidine, Azathioprine, Capecitabine, Cytarabine, Doxifluridine, Fluorouracil, Gemcitabine, Hydroxyurea, Mercaptopurine, Methotrexate, Tioguanine, Bleomycin, Actinomycin, Carboplatin, Cisplatin, Oxaliplatin, Nedaplatin, Triplatin Tetranitrate, Phenanthriplatin, Picoplatin, Satraplatin, Tretinoin, Alitretinoin, Bexarotene, Vinblastine, Vincristine, Vindesine, Vinflunine, Vinorelbine, Aminopterin, Pemetrexed, Pralatrexate, Raltitrexed, Pentostatin, Cladribine, Clofarabine, Fludarabine, Nelarabine, Carmofur, Floxuridine, Tegafur, Cytarabine, Gemcitabine, Decitabine, Hydroxycarbamide, Belotecan, Camptothecin, Cositecan, Etirinotecan pegol, Exatecan, Gimatecan, , Lurtotecan, Rubitecan, Silatecan, Aclarubicin, Amrubicin, Pirarubicin, Valrubicin, Zorubicin, Mitoxantrone, Losoxantrone, Pixantrone, Bendamustine, Chlormethine, Ifosfamide, Trofosfamide, Prednimustine, Uramustine, Carmustine, Fotemustine, Lomustine Semustine, Nimustine, Ranimustine, Streptozocin, Mannosulfan, Treosulfan, Carboquone, Thiotepa, Triaziquone, Triethylenemelamine, Altretamine, Procarbazine, Mitobronitol, Pipobroman, Dacarbazine, Temozolomide, Dactinomycin, Bleomycin, Mitomycins, Plicamycin, Aminolevulinic acid, Efaproxiral, Methyl aminolevulinate, Padeliporfin, Porfimer sodium, Talaporfin, Temoporfin, Verteporfin, Tipifarnib, Abemaciclib, Alvocidib, Palbociclib, Ribociclib, Seliciclib, Bortezomib, Carfilzomib, Oprozomib, Ixazomib, Anagrelide, Tiazofurin, Masoprocol, Niraparib, Olaparib, Rucaparib, Belinostat, Entinostat, Panobinostat, Romidepsin, Vorinostat, Pi3K, Alpelisib, Copanlisib, Duvelisib, Idelalisib, Umbralisib, Atrasentan, Bexarotene, Testolactone, Amsacrine, Arsenic trioxide, Asparaginase, Pegaspargase, Belzutifan, Celecoxib, Demecolcine, Elesclomol, Elsamitrucin, Eribulin, Estramustine phosphate, Etoglucid, Lonidamine, Lucanthone, Mitoguazone, Mitotane, Oblimersen, Omacetaxine mepesuccinate, Trabectedin, Alitretinoin, Bexarotene, Tretinoin, Veliparib and Venetoclax. Combinations of chemotherapeutic agents are for example used for the treatment of cancer. Combinations may be established or improvised by the treating physician. Established combinations are known as regimens, wherein in some cases also dose and administration interval are included. The chemotherapeutic agent as disclosed herein is for example an (i) alkylating agent (such as Altretamine, Bendamustine, Busulfan, Carboplatin, Carmustine, Chlorambucil, Cisplatin, Cyclophosphamide, Dacarbazine, Ifosfamide, Lomustine, Mechlorethamine, Melphalan, Oxaliplatin, Temozolomide, Thiotepa or Trabectedin), (ii) an nitrosoureas (such as Carmustine, Lomustine or Streptozocin), (iii) an antimetabolite (Azacitidine, 5-fluorouracil (5-FU), 6-mercaptopurine (6-MP), Capecitabine (Xeloda), Cladribine, Clofarabine, Cytarabine (Ara-C), Decitabine, Floxuridine, Fludarabine, Gemcitabine (Gemzar), Hydroxyurea, Methotrexate, Nelarabine, Pemetrexed (Alimta), Pentostatin, Pralatrexate, Thioguanine or Trifluridine / tipiracil combination, (iv) an anthracycline (such as Daunorubicin, Doxorubicin (Adriamycin), Doxorubicin liposomal, Epirubicin, Idarubicin or Valrubicin), (v) an topoisomerase I or II inhibitor (such as Irinotecan, Irinotecan liposomal, Topotecan, Etoposide (VP-16), Mitoxantrone or Teniposide), (vi) a taxane (Cabazitaxel, Docetaxel, Nab-paclitaxel or Paclitaxel), (vii) a vinca alkaloid (such as Vinblastine, Vincristine, Vincristine liposomal or Vinorelbine), (viii) a corticosteroid (such as Prednisone, Methylprednisolone or Dexamethasone), or (ix) All-trans-retinoic acid, Arsenic trioxide, Asparaginase, Eribulin, Hydroxyurea, Ixabepilone, Mitotane, Omacetaxine, Pegaspargase, Procarbazine, Romidepsin or Vorinostat. The term “combination” or “combination therapy”, as used herein, includes reference to using a compound targeting Tpm1.8 and / or Tpm1.9 as disclosed herein and an anti-cancer therapeutic agent as disclosed herein in the same medical treatment. The compound targeting Tpm1.8 and / or Tpm1.9 and the anti-cancer therapeutic agent as disclosed herein are for example administered together at the same time (such as in the form of a single pharmaceutical composition), separately of each other at the same time (for instance in the form of separate pharmaceutical compositions) or separately of each other staggered in time. Simultaneous, separate and sequential administration of a compound targeting Tpm1.8 and / or Tpm1.9 and an anti-cancer therapeutic agent as disclosed herein in the same treatment schedule are expressly envisaged. As an example, the time between administration of the compound targeting Tpm1.8 and / or Tpm1.9 and the anti-cancer therapeutic agent is for example at least one minute, at least fifteen minutes, at least sixty minutes, at least four hours, at least one day, at least one week or at least one month or at least one year, or anywhere in between such as between one minute and one year. Preferably, the compound targeting Tpm1.8 and / or Tpm1.9 is administered prior to administration of said anti-cancer therapeutic agent. Alternatively, the anti-cancer therapeutic agent is administered together with, or after, administration of the compound targeting Tpm1.8 and / or Tpm1.9. The anti-cancer therapeutic agent which is combined with the compound targeting Tpm1.8 and / or Tpm1.9 is for example a chemotherapy. The chemotherapy which is combined with the compound targeting Tpm1.8 and / or Tpm1.9 is for example taxane- and platinum-based chemotherapy. The compound targeting Tpm1.8 and / or Tpm1.9 is for example combined with cisplatin- and / or paclitaxel. The term “pharmaceutical combination”, as used herein, includes reference to e.g. a kit of parts containing multiple containers that hold the different active ingredients. Throughout this specification and the claims, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated member, integer or step or group of members, integers or steps but not the exclusion of any other member, integer or step or group of members, integers or steps. The terms “a” and “an” and “the” and similar reference used in the context of describing the invention (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”, “for example”), provided herein is intended merely to better illustrate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention. All documents cited or referenced herein (“herein cited documents”), and all documents cited or referenced in herein cited documents, together with any manufacturer's instructions, descriptions, product specifications, and product sheets for any products mentioned herein or in any document incorporated by reference herein, are hereby incorporated herein by reference, and may be employed in the practice of the invention. More specifically, all referenced documents are incorporated by reference to the same extent as if each individual document was specifically and individually indicated to be incorporated by reference. In the following, the features of the present invention will be described in more detail. It should be understood that embodiments may be combined in any manner and in any number to create additional embodiments. The variously described examples and embodiments should not be construed to limit the present invention to only the explicitly described embodiments. This description should be understood to support and encompass embodiments which combine the explicitly described embodiments with any number of the disclosed features. Furthermore, any permutations and combinations of all described features in this application should be considered disclosed by the description of the present application unless the context indicates otherwise. Compounds The compounds according to the present invention target Tpm1.8 and / or Tpm1.9 isoforms. For example, the compounds of the present invention target the N-terminal sequences of exon 1b of TPM1 (see Figures 1 and 6 of Schevzov et al.2011. Bioarchitecture 1(4): 135–164 to which reference is made for intron / exon organization of the TPM1 gene, and which is incorporated by reference herein). For example, the compounds targeting Tpm1.8 and / or Tpm1.9 isoforms target the N-terminus of Tpm1.8 and / or Tpm1.9 at residues 4 – 16. For example, the compound is a small molecule that perturbs the activity of Tpm1.8 and / or Tpm1.9 isoforms in a dose dependent manner. The compounds targeting Tpm1.8 and / or Tpm1.9 isoforms preferably inhibit Tpm1.8 and / Tpm1.9 activity in a concentration of 5 – 50 µM, 15 – 30 µM, or 10 – 20 µM. For example, the compound targeting Tpm1.8 and / or Tpm1.9 isoforms is selected from 3-(2- Methyl-indol-1-yl)-propylamine (PubChem CID 6494468), 1-Phenylmethyl-1h-indole-2- methanol (PubChem CID 18973468), or a combination thereof. PubChem CID 6494468 targets both Tpm1.8 / 9 and Tpm4.2, PubChem CID: 18973468 only targets Tpm1.8 / 9. In some embodiments of aspects of this invention PubChem CID 6494468 is a preferred compound. In some embodiments of aspects of this invention PubChem CID 18973468 is a preferred compound. Further, a compound targeting Tpm1.8 and / or Tpm1.9 isoforms includes for example pharmaceutical acceptable salts, hydrates, derivates and / or solvates of 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) and / or 1- Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468). Formula I: 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) Formula II: 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468) Further, compounds targeting Tpm1.8 and / or Tpm1.9 isoforms according to the present invention include any compound which is identified by the method of identifying compounds targeting Tpm1.8 and / or Tpm1.9 as disclosed herein. Compounds targeting Tpm1.8 and / or Tpm1.9 isoforms according to the present invention also include hydrates and solvates. Solvates are complexes formed by association of molecules of a solvent with a compound of the present invention. The compound targeting Tpm1.8 and / or Tpm1.9 isoforms of the present invention is for example in the form of pharmaceutically acceptable salts. The compound targeting Tpm1.8 and / or Tpm1.9 isoforms of the present invention also extends to include all derivatives with physiologically cleavable leaving groups that can be cleaved in vivo. Compounds of the present invention further include antisense polynucleotides which decreases the expression of Tpm1.8 and / or Tpm1.9 isoforms in cancer cells. Compounds of the present invention further include antibodies which decreases Tpm1.8 and / or 1.9 polypeptide levels and / or Tpm1.8 or 1.9 polypeptide activity. Antisense polynucleotides and antibodies of the invention may be used in a method of inhibiting, suppressing, preventing or treating proliferation, motility, invasion, migration, metastasis or chemo-resistance of a cancer. Pharmaceutical compositions A compound targeting Tpm1.8 and / or Tpm1.9 isoforms, or other compounds of the invention as disclosed herein, may be used as sole active ingredient of a pharmaceutical composition of the invention, or it may be combined with other compounds targeting the same or different targets. For example, a first compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein may be combined with a second compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein. A compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein is preferably in a pharmaceutical composition that may further comprise a pharmaceutically acceptable excipient (or carrier). As used herein, pharmaceutically acceptable excipient or carrier includes reference to any and all solvents, dispersion media, coatings, surfactants, antioxidants, preservatives (e.g., antibacterial agents, antifungal agents), isotonic agents, absorption delaying agents, salts, preservatives, drugs, drug stabilizers, gels, binders, excipients, disintegration agents, lubricants, sweetening agents, flavoring agents, dyes, such like materials and combinations thereof, as would be known to one of ordinary skill in the art. Except insofar as any conventional carrier is incompatible with the compound targeting Tpm1.8 and / or Tpm1.9 isoforms, its use in the pharmaceutical compositions is contemplated. Acceptable excipients, carriers or diluents for therapeutic use are well known in the pharmaceutical art, and are described, for example, in standard textbook references such as Remington's Pharmaceutical Sciences (e.g. Mack Publishing Co., A.R. Gennaro edit., 1985). Pharmaceutical compositions suitable for parenteral administration (e.g., by intramuscular, intraperitoneal, subcutaneous or injection directly into a target organ) include aqueous and non-aqueous, isotonic sterile injection solutions, which can contain antioxidants, buffers, bacteriostats, and solutes that render the formulation isotonic with the blood of the intended recipient, and aqueous and non-aqueous sterile suspensions that can include suspending agents, solubilizers, thickening agents, stabilizers, and preservatives. Pharmaceutical compositions can be presented in unit-dose or multi-dose sealed containers, such as ampoules and vials. Injection solutions and suspensions can be prepared from sterile powders, granules, and tablets. Pharmaceutical compositions suitable for oral administration can consist of (a) liquid solutions, such as an effective amount of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms suspended in diluents, such as water or saline; (b) capsules, sachets or tablets, each containing a predetermined amount of the active ingredient, as liquids, solids, granules or gelatin; (c) suspensions in an appropriate liquid; and (d) suitable emulsions. Tablet forms can include one or more of lactose, sucrose, mannitol, sorbitol, calcium phosphates, corn starch, potato starch, tragacanth, microcrystalline cellulose, acacia, gelatin, colloidal silicon dioxide, croscarmellose sodium, talc, magnesium stearate, stearic acid, and other excipients, colorants, fillers, binders, diluents, buffering agents, moistening agents, preservatives, flavoring agents, dyes, disintegrating agents, and pharmaceutically compatible carriers. Lozenge forms can comprise the active ingredient in a flavor, usually sucrose and acacia or tragacanth, as well as pastilles comprising the active ingredient in an inert base, such as gelatin and glycerin or sucrose and acacia emulsions, gels, and the like containing, in addition to the compound targeting Tpm1.8 and / or Tpm1.9 isoforms, carriers known in the art. Pharmaceutical compositions can be encapsulated, e.g., in liposomes, or in a formulation that provides for slow release of the active ingredient. Thus, in a specific embodiment, the pharmaceutical composition comprising a compound targeting Tpm1.8 and / or Tpm1.9 isoforms can be administered via liposomes, microparticles, or microcapsules. In various embodiments of the present invention, it may be useful to use such a composition to achieve sustained release of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms. In a specific embodiment, the present invention provides an agent pack or kit comprising one or more containers filled with one or more compounds, compositions or medicaments of the invention. Optionally, information indicating approval for manufacture, use, or sale for administration to a human by a government agency regulating the manufacture, use, or sale of medicaments or biological products can be appended to such a container in a stipulated form. The formulation procedure for the compound targeting Tpm1.8 and / or Tpm1.9 isoforms as a medicament or the like is known in the art. The procedure is described, for example, in the Japanese Pharmacopoeia, the United States Pharmacopeia, pharmacopeia of other countries, or the like. Thus, those skilled in the art can determine the embodiment such as the amount to be used without undue experimentation from the descriptions herein. Administration and treatment methods The present invention relates to a compound targeting Tpm1.8 and / or Tpm1.9 isoforms for use in a method of preventing and / or treating cancer in a subject. The administration of at least one compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein is for example through administration of a pharmaceutical composition comprising a compound targeting Tpm1.8 and / or Tpm1.9 isoforms. The pharmaceutical compositions can be administered in any suitable way, such as enterally, parenterally, topically, by inhalation and the like. Parenteral administration is for example epidural, intracerebral, intracerebroventricular, epicutaneous, sublingual, extra-amniotic, nasal, intra-arterial, intra-articular, intracardiac, intracavernous, intradermal, intralesional, intramuscular, intraocular, intraosseous, intraperitoneal, intrathecal, intrauterine, intravaginal, intravenous, intravesical, intravitreal, subcutaneous, transdermal, perivascular, transmucosal, intratumoral or a combination thereof. Administration is for example enterally, such as orally or rectally. A second and optionally a further compound targeting Tpm1.8 and / or Tpm1.9 isoforms can be employed in an aspect of the invention. For example, the second compound targeting Tpm1.8 and / or Tpm1.9 isoforms is administered together with the first compound targeting Tpm1.8 and / or Tpm1.9 isoforms, e.g. together at the same time (such as in the form of a single pharmaceutical composition), separately of each other at the same time (for instance in the form of separate pharmaceutical compositions) or separately of each other staggered in time. Simultaneous, separate and sequential administration of compounds targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein in the same treatment schedule are expressly envisaged. The second compound targeting Tpm1.8 and / or Tpm1.9 isoforms is for example administered parenterally or enterally. The parenteral administration is for example epidural, intracerebral, intracerebroventricular, epicutaneous, sublingual, extra-amniotic, nasal, intra-arterial, intra-articular, intracardiac, intracavernous, intradermal, intralesional, intramuscular, intraocular, intraosseous, intraperitoneal, intrathecal, intrauterine, intravaginal, intravenous, intravesical, intravitreal, subcutaneous, transdermal, perivascular, transmucosal, rectal, intratumoral administration or a combination thereof. The administration is for example intravenous or intratumoral administration, or is orally or rectally. A third, fourth, fifth or further compound targeting Tpm1.8 and / or Tpm1.9 isoforms is for example used in aspects of the invention. The third, fourth, fifth or further compound targeting Tpm1.8 and / or Tpm1.9 isoforms is for example administered together with the first and second compound targeting Tpm1.8 and / or Tpm1.9 isoforms as described above. The present invention further comprises co-administering an anti-cancer therapeutic agent as described herein in combination with a compound targeting Tpm1.8 and / or Tpm1.9 isoforms. A compound targeting Tpm1.8 and / or Tpm1.9 isoforms, and optionally a second, third, fourth, fifth and / or further compound targeting Tpm1.8 and / or Tpm1.9 isoforms is administered together with one or more anti-cancer therapeutic agents as described herein. Administration of said anti-cancer therapeutic agent is for example performed parenterally. Parenteral administration is for example epidural, intracerebral, intracerebroventricular, epicutaneous, sublingual, extra-amniotic, nasal, intra-arterial, intra-articular, intracardiac, intracavernous, intradermal, intralesional, intramuscular, intraocular, intraosseous, intraperitoneal, intrathecal, intrauterine, intravaginal, intravenous, intravesical, intravitreal, subcutaneous, transdermal, perivascular, transmucosal, intratumoral administration or a combination thereof. For example, the administration is intravenous or intratumoral administration. The same route of administration is for example selected for a compound targeting Tpm1.8 and / or Tpm1.9 isoforms, and optionally a second, third, fourth, fifth and / or further compound targeting Tpm1.8 and / or Tpm1.9 isoforms, and one or more anti-cancer therapeutic agents as described herein. However, it is also possible that the compound targeting Tpm1.8 and / or Tpm1.9 isoforms and the anti-cancer therapeutic agent are administered through different routes of administration. As an example, the anti-cancer therapeutic agent can be administered parenterally, and the compound targeting Tpm1.8 and / or Tpm1.9 isoforms orally. Further, as an example, the (first) compound targeting Tpm1.8 and / or Tpm1.9 isoforms is administered orally, and the second, or further, compound targeting Tpm1.8 and / or Tpm1.9 isoforms is administered parenterally. In aspects of this invention, the compound targeting Tpm1.8 and / or Tpm1.9 isoforms is administered to a subject at least once, at least twice, at least three times, at least four times, at least five times, at least six times, at least seven times, at least eight times, at least nine times, at least ten times, at least twelve times, at least fourteen times, at least sixteen times, at least eighteen times, at least twenty times, at least twenty-five times, at least thirty times, at least thirty-five times, at least forty times, at least fifty times, at least sixty times, at least seventy times, at least eighty times, at least ninety times or at least one hundred times. A compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein is for example employed in a treatment regimen that involves daily, weekly or monthly administration of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms. Treatment is for example maintained for at least three days, at least a week, at least a month, and more preferably at least 6 months or at least a year such as 2-5 years. A compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein and / or an anti-cancer therapeutic agent is for example employed in a treatment regimen that involves administration in cycles where each cycle comprises repetitive administration, for example daily administration, of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms for several days, for example for at least one day, at least three days, at least a week, at least two weeks or at least three weeks. The administration of a compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein and / or an anti-cancer therapeutic agent in cycles is for example repeated every two weeks, every three weeks, every four weeks, every five weeks, every six weeks, every seven weeks, every eight weeks. The administration of a compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein and / or an anti-cancer therapeutic agent in cycles is for example repeated after 3 – 5 weeks, for example after three weeks or after five weeks. For example, the administration of a compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein and / or an anti-cancer therapeutic agent is repeated at no fixed interval, but according to the patient’s need. For example, the administration of a chelating agent as disclosed herein and / or an anti-cancer therapeutic agent in cycles is repeated at least one time, at least two times, at least thee three times, at least four times, at least five times, at least six times, at least seven times, at least eight times, or at least 10 times. For example, treatment is maintained for at least three days, at least a week, at least a month, and more preferably at least six months or at least a year, such as 2-5 years. Administration of a compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein and / or an anti-cancer therapeutic agent as disclosed herein to a subject for example follow general protocols for the administration of such compounds, taking into account the toxicity, if any, of the agents. Therefore, in some embodiments there is a step of monitoring toxicity that is attributable to combination therapy. A compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein can be administered in any acceptable pharmaceutical dosage form, for example as an aqueous medium such as a solution, suspension, emulsification. A chelating agent can also be administered orally as a pill, tablet, capsule, etc. In aspects of the invention, the subject can be identified as eligible for therapy if he or she has a cancer with cancer cells, such as ovarian cancer. The cancer cells for example exhibit a resistance such as a chemoresistance. For example the cancer cells exhibit a chemoresistance against a taxane- and / or platinum-based chemotherapy. For example the cancer cells exhibit a chemoresistance against cisplatin- and / or paclitaxel. A suitable dosing of the compounds of the present invention in methods of treatment may include a dose in the range of 0.1- 100 mg / kg, preferably about 0.5-20 mg / kg, even more preferably about 1-10 mg / kg. Methods of treatment according to this invention include methods of inhibiting, suppressing, preventing and / or treating cancer, comprising administering to a subject in need thereof a therapeutically effective amount of a compound according to the present invention or of a pharmaceutical composition comprising a compound according to the present invention. In embodiments of such methods, the compound is for example a compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein, such as a small molecule inhibitor as disclosed herein, or an antisense polynucleotide or antibody which decrease Tpm1.8 or 1.9 polypeptide levels and / or Tpm1.8 or 1.9 polypeptide activity. Cancer In aspects of the present invention, the cancer is for example selected from non- small cell lung cancer; renal cancer; renal cell carcinoma; clear cell renal cell carcinoma; lymphoma; blastoma; sarcoma; carcinoma, undifferentiated; meningioma; brain cancer; oropharyngeal cancer; nasopharyngeal cancer; biliary cancer; pheochromocytoma; pancreatic islet cell cancer; Li-Fraumeni tumor; thyroid cancer; parathyroid cancer; pituitary tumor; adrenal gland tumor; osteogenic sarcoma tumor; neuroendocrine tumor; breast cancer; lung cancer; head and neck cancer; prostate cancer; esophageal cancer; tracheal cancer; liver cancer; bladder cancer; stomach cancer; pancreatic cancer; ovarian cancer; uterine cancer; cervical cancer; testicular cancer; colon cancer; rectal cancer; skin cancer; giant and spindle cell carcinoma; small cell carcinoma; small cell lung cancer; papillary carcinoma; oral cancer; oropharyngeal cancer; nasopharyngeal cancer; respiratory cancer; urogenital cancer; squamous cell carcinoma; lymphoepithelial carcinoma; basal cell carcinoma; pilomatrix carcinoma; transitional cell carcinoma; papillary transitional cell carcinoma; adenocarcinoma; gastrointestinal cancer; gastrinoma, malignant; cholangiocarcinoma; hepatocellular carcinoma; combined hepatocellular carcinoma and cholangiocarcinoma; trabecular adenocarcinoma; adenoid cystic carcinoma; adenocarcinoma in adenomatous polyp; adenocarcinoma, familial polyposis coli; solid carcinoma; carcinoid tumor, malignant; branchiolo-alveolar adenocarcinoma; papillary adenocarcinoma; chromophobe carcinoma; acidophil carcinoma; oxyphilic adenocarcinoma; basophil carcinoma; clear cell adenocarcinoma; granular cell carcinoma; follicular adenocarcinoma; papillary and follicular adenocarcinoma; nonencapsulating sclerosing carcinoma; adrenal cortical carcinoma; endometroid carcinoma; skin appendage carcinoma; apocrine adenocarcinoma; sebaceous adenocarcinoma; ceruminous adenocarcinoma; mucoepidermoid carcinoma; cystadenocarcinoma; papillary cystadenocarcinoma; papillary serous cystadenocarcinoma; mucinous cystadenocarcinoma; mucinous adenocarcinoma; signet ring cell carcinoma; infiltrating duct carcinoma; medullary carcinoma; lobular carcinoma; inflammatory carcinoma; Paget's disease, mammary; acinar cell carcinoma; adenosquamous carcinoma; adenocarcinoma with squamous metaplasia; thymoma, malignant; ovarian stromal tumor, malignant; thecoma, malignant; granulosa cell tumor, malignant; androblastoma, malignant; Sertoli cell carcinoma; Leydig cell tumor, malignant; lipid cell tumor, malignant; paraganglioma, malignant; extra-mammary paraganglioma, malignant; pheochromocytoma; glomangiosarcoma; malignant melanoma; amelanotic melanoma; superficial spreading melanoma; malignant melanoma in giant pigmented nevus; lentigo maligna melanoma; acral lentiginous melanoma; nodular melanoma; epithelioid cell melanoma; blue nevus, malignant; sarcoma; fibrosarcoma; fibrous histiocytoma, malignant; myxosarcoma; liposarcoma; leiomyosarcoma; rhabdomyosarcoma; embryonal rhabdomyosarcoma; alveolar rhabdomyosarcoma; stromal sarcoma; mixed tumor, malignant; Mullerian mixed tumor; nephroblastoma; hepatoblastoma; carcinosarcoma; mesenchymoma, malignant; Brenner tumor, malignant; phyllodes tumor, malignant; synovial sarcoma; mesothelioma, malignant; dysgerminoma; embryonal carcinoma; teratoma, malignant; struma ovarii, malignant; choriocarcinoma; mesonephroma, malignant; hemangiosarcoma; hemangioendothelioma, malignant; Kaposi' s sarcoma; hemangiopericytoma, malignant; lymphangiosarcoma; osteosarcoma; juxtacortical osteosarcoma; chondrosarcoma; chondroblastoma, malignant; mesenchymal chondrosarcoma; giant cell tumor of bone; Ewing's sarcoma; odontogenic tumor, malignant; ameloblastic odontosarcoma; ameloblastoma, malignant; ameloblastic fibrosarcoma; an endocrine or neuroendocrine cancer or hematopoietic cancer; pinealoma, malignant; chordoma; central or peripheral nervous system tissue cancer; glioma, malignant; ependymoma; astrocytoma; protoplasmic astrocytoma; fibrillary astrocytoma; astroblastoma; glioblastoma; oligodendroglioma; oligodendroblastoma; primitive neuroectodermal; cerebellar sarcoma; ganglioneuroblastoma; neuroblastoma; retinoblastoma; olfactory neurogenic tumor; meningioma, malignant; neurofibrosarcoma; neurilemmoma, malignant; granular cell tumor, malignant; B-cell lymphoma; malignant lymphoma; Hodgkin's disease; Hodgkin's; low grade / follicular non-Hodgkin's lymphoma; paragranuloma; malignant lymphoma, small lymphocytic; malignant lymphoma, large cell, diffuse; malignant lymphoma, follicular; mycosis fungoides; mantle cell lymphoma; Waldenstrom's macroglobulinemia; other specified non-Hodgkin's lymphomas; malignant histiocytosis; multiple myeloma; mast cell sarcoma; immunoproliferative small intestinal disease; leukemia; Preferably, leukemia is lymphoid leukemia; plasma cell leukemia; erythroleukemia; lymphosarcoma cell leukemia; myeloid leukemia; acute myeloid leukemia (AML), chronic myeloid leukemia (CML); basophilic leukemia; eosinophilic leukemia; monocytic leukemia; mast cell leukemia; megakaryoblastic leukemia; myeloid sarcoma; chronic lymphocytic leukemia (CLL); acute lymphoblastic leukemia (ALL); hairy cell leukemia; chronic myeloblastic leukemia; acute lymphoblastic leukemia (ALL), adrenocortical carcinoma, bladder urothelial carcinoma, brain lower grade carcinoma, breast invasive carcinoma, cervical squamous cell carcinoma and endocervical adenocarcinoma, cholangiocarcinoma, colon adenocarcinoma, esophageal carcinoma, glioblastoma multiforme, head and neck squamous cell carcinoma, kidney chromophobe, kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, lung squamous cell carcinoma, lymphoid neoplasm diffuse large B-cell lymphoma, mesothelioma, ovarian cancer, in particular ovarian serous cancer, pancreatic adenocarcinoma, rectum adenocarcinoma, sarcoma, skin cutaneous melanoma, stomach adenocarcinoma, testicular germ cell tumors, thymoma, thyroid carcinoma, uterine carcinosarcoma, uterine corpus endometrial carcinoma, uveal melanoma and combinations thereof. In some embodiments, said cancer is a solid tumor. In some embodiments, said cancer is a liquid tumor. Preferably, in aspects of the present invention the cancer is a carcinoma. Carcinoma is a malignancy that develops from epithelial cells. Preferably, in aspects of the present invention the cancer is a cancer that expresses TPM1 alternative splicing isoforms. For example, the cancer is a cancer that expresses TPM1 alternative splicing isoforms comprising Exon 1b of TPM1. For example, the cancer is a cancer that exhibits alternative splicing in that it expresses Tpm1.8 and / or Tpm1.9 isoforms. Tpm1.8 and or Tpm1.9 expression may for instance be determined at the level of RNA or protein. At the RNA level. Tpm1.8 and or Tpm1.9 expression may for example be determined by RT-PCR (reverse-transcription polymerase chase reaction) or by RNA-sequencing, and, at the protein level, by antibody detection (e.g. western blot, immunofluorescence, or immunohistochemistry) or mass spectrometry. The presence of alternative splicing (expression of Tpm1.8 and / or Tpm1.9 isoforms) may be indicated when the difference of an appropriate expression-level parameter (e.g. mean PSI (Δpsi; differential Percentage Spliced In) as in the examples below) between the tested cancer (cell) and an appropriate control (cell) is >10%. It was found by the present inventors that in ovarian cancer the Tpm1.8 and / or Tpm1.9 isoforms are not expressed in the primary tumors, but are expressed in a rather small time-window during the systemic dissemination of the cells in the abdominal cavity when they undergo epithelial-mesenchymal transition (EMT), a complex developmental program that enables carcinoma cells to suppress their epithelial features changing to mesenchymal ones, i.e. whereby cells acquire quasi-mesenchymal and chemo-resistant features in combination with mobility and invasiveness. Aspects of this invention therefore pertain to cancers that express the TPM1 gene and in particular TPM1 RNA molecules that comprise exon 1b (from which the Tpm1.8 and / or Tpm1.9 isoforms originate). There are numerous cancers that express TPM1 RNA molecules that comprise exon 1b. From a database search (TGCA database, world wide web address www.cancer.gov / ccg / research / genome-sequencing / tcga) it was determined that gene expression at the RNA level of the complete TPM1 gene including the expression of TPM1 RNA molecules that comprise exon 1b occurs in acute myeloid leukemia (AML), adrenocortical carcinoma, bladder urothelial carcinoma, brain lower grade carcinoma, breast invasive carcinoma, cervical squamous cell carcinoma and endocervical adenocarcinoma, cholangiocarcinoma, colon adenocarcinoma, esophageal carcinoma, glioblastoma multiforme, head and neck squamous cell carcinoma, kidney chromophobe, kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, lung squamous cell carcinoma, lymphoid neoplasm diffuse large B-cell lymphoma, mesothelioma, ovarian cancer, pancreatic adenocarcinoma, rectum adenocarcinoma, sarcoma, skin cutaneous melanoma, stomach adenocarcinoma, testicular germ cell tumors, thymoma, thyroid carcinoma, uterine carcinosarcoma, uterine corpus endometrial carcinoma, uveal melanoma. Hence, aspects of the invention find utility on treating such cancers. For example, the cancer is an ovarian cancer, such as epithelial ovarian cancer. For example, the cancer is a high-grade serous ovarian cancer. Epithelial ovarian cancer (EOC) is the leading cause of death amongst gynecologic malignancies due to its high case-to-fatality ratio. EOC generally becomes manifest at advanced disease stages, i.e. when metastases have already spread to pelvic organs (stage II), the abdomen (stage III), or beyond the peritoneal cavity (stage IV). Based on the underlying genetic defects, two main EOC subtypes have been recognized. Type I tumors are slow growing, mostly restricted to the ovary, and thought to arise from well- differentiated precursor lesions called “borderline” tumors. They are further subdivided into low-grade serous, mucinous, clear cell, and endometrioid subtypes. Mutations in KRAS, BRAF, PTEN, and CTNNB1 (β-catenin) earmarks type I EOCs, often together with a relatively stable karyotype. High-grade serous (HGSOC) and undifferentiated carcinomas are type II EOCs and are frequently characterized by TP53 mutations and by aneuploidy. HGSOC represents the most malignant and common ovarian cancer type accounting for up to 70% of all cases with poor prognosis and survival. Of note, EOC is the only cancer type where no physical barrier exists between primary lesion and the main metastatic site, i.e. the intraperitoneal cavity. The dissemination of ovarian cancer cells results in their adhesion to intra-abdominal organs and the peritoneum eventually leading to ascites accumulation due to the obstruction of lymphatic vessels. For example the cancer is an epithelial ovarian cancer of EOC Type I and / or a EPO Type II. For example, the epithelial ovarian cancer is selected from the group consisting of a EOC Type I, EOC Type II, high grade serous ovarian cancer (HGSOC), low-grad serous ovarian cancer (LGSOC), fallopian tube cancer, primary peritoneal cancer and combinations thereof. Anti-cancer therapeutic agent The present invention relates to a compound targeting Tpm1.8 and / or Tpm1.9 isoforms for use in a method of treating cancer in a subject. Optionally, at least one compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein is administered in combination with an additional anti-cancer therapeutic agent. An anti-cancer therapeutic agent may be any anti-cancer therapeutic agent. The anti-cancer therapeutic agent as described herein is for example an anti-cancer therapeutic agent used in a treatment type selected from the group of chemotherapy, targeted therapy such as immunotherapy, stem cell therapy, hormone therapy, radiation therapy and surgery, or a combination thereof; preferably, said treatment type is chemotherapy. The anti-cancer therapeutic agent is for example selected from the group comprising Cyclophosphamide, Mechlorethamine, Chlorambucil, Melphalan, Dacarbazine, Nitrosoureas, Temozolomide, Daunorubicin, Doxorubicin, Epirubicin, Idarubicin, Mitoxantrone, Valrubicin, Cabazitaxel, Larotaxel, Ortataxel, Tesetaxel, Paclitaxel, Docetaxel, Abraxane, Taxotere, Epothilone A, Epothilone B, Epothilone C, Epothilone D, Epothilone E, Epothilone F, Vorinostat, Romidepsin, Irinotecan, Topotecan, Etoposide, Teniposide, Tafluposide, Bortezomib, Erlotinib, Gefitinib, Imatinib, Vemurafenib, Vismodegib, Azacitidine, Azathioprine, Capecitabine, Cytarabine, Doxifluridine, Fluorouracil, Gemcitabine, Hydroxyurea, Mercaptopurine, Methotrexate, Tioguanine, Bleomycin, Actinomycin, Carboplatin, Cisplatin, Oxaliplatin, Nedaplatin, Triplatin Tetranitrate, Phenanthriplatin, Picoplatin, Satraplatin, Tretinoin, Alitretinoin, Bexarotene, Vinblastine, Vincristine, Vindesine, Vinflunine, Vinorelbine, Aminopterin, Pemetrexed, Pralatrexate, Raltitrexed, Pentostatin, Cladribine, Clofarabine, Fludarabine, Nelarabine, Carmofur, Floxuridine, Tegafur, Cytarabine, Gemcitabine, Decitabine, Hydroxycarbamide, Belotecan, Camptothecin, Cositecan, Etirinotecan pegol, Exatecan, Gimatecan, , Lurtotecan, Rubitecan, Silatecan, Aclarubicin, Amrubicin, Pirarubicin, Valrubicin, Zorubicin, Mitoxantrone, Losoxantrone, Pixantrone, Bendamustine, Chlormethine, Ifosfamide, Trofosfamide, Prednimustine, Uramustine, Carmustine, Fotemustine, Lomustine Semustine, Nimustine, Ranimustine, Streptozocin, Mannosulfan, Treosulfan, Carboquone, Thiotepa, Triaziquone, Triethylenemelamine, Altretamine, Procarbazine, Mitobronitol, Pipobroman, Dacarbazine, Temozolomide, Dactinomycin, Bleomycin, Mitomycins, Plicamycin, Aminolevulinic acid, Efaproxiral, Methyl aminolevulinate, Padeliporfin, Porfimer sodium, Talaporfin, Temoporfin, Verteporfin, Tipifarnib, Abemaciclib, Alvocidib, Palbociclib, Ribociclib, Seliciclib, Bortezomib, Carfilzomib, Oprozomib, Ixazomib, Anagrelide, Tiazofurin, Masoprocol, Niraparib, Olaparib, Rucaparib, Belinostat, Entinostat, Panobinostat, Romidepsin, Vorinostat, Pi3K, Alpelisib, Copanlisib, Duvelisib, Idelalisib, Umbralisib, Atrasentan, Bexarotene, Testolactone, Amsacrine, Arsenic trioxide, Asparaginase, Pegaspargase, Belzutifan, Celecoxib, Demecolcine, Elesclomol, Elsamitrucin, Eribulin, Estramustine phosphate, Etoglucid, Lonidamine, Lucanthone, Mitoguazone, Mitotane, Oblimersen, Omacetaxine mepesuccinate, Trabectedin, Alitretinoin, Bexarotene, Tretinoin, Veliparib and Venetoclax, or a combination thereof. For example, a combination of anti-cancer therapeutic agents is a known chemotherapy regimen, such as CMF (Cyclophosphamide, Methotrexate, 5- fluorouracil, vinorelbine), AC (doxorubicin, cyclophosphamide), DA (cytarabine, an anthracycline antibiotic, daunorubicin), IA (cytarabine, an anthracycline antibiotic, idarubicin), DAT (daunorubicin, cytarabine, tioguanine), FLAMSA (fludarabine, cytarabine, amsacrine), FLAMSA-BU (fludarabine, cytarabine, amsacrine, busulfan), FLAMSA-MEL (fludarabine, cytarabine, amsacrine, melphalan), TAD (tioguanine, cytarabine, daunorubicin), CAF (cyclophosphamide, doxorubicin, fluorouracil), CLIA (cladribine, idarubicin, and cytarabine), CLIA-M (mylotarg, cladribine, idarubicin, and cytarabine) and ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine). An anthracycline such as a doxorubicin, an antimetabolite, such as 5-fluorouracil (5-FU), and / or a taxane, such as Nab-paclitaxel and / or Paclitaxel is for example selected as the anti-cancer therapeutic agent. The anti-cancer therapeutic agent as disclosed herein can be administered by any acceptable delivery mode, such as e.g. by liposomal delivery. For example, the at least one compound targeting Tpm1.8 and / or Tpm1.9 isoforms as disclosed herein is administered in combination with a taxane- and / or platinum-based chemotherapy, such as a chemotherapy comprising cisplatin- and / or paclitaxel. Chemoresistance In aspects of the invention, the compounds targeting Tpm1.8 and / or Tpm1.9 isoforms for preventing and / or treating of cancer counteracts chemoresistance. For example, the compounds targeting Tpm1.8 and / or Tpm1.9 are for use in reversing a chemoresistance of a resistant cancer, e.g. a resistant ovarian cancer. For example, the chemoresistance is a native chemoresistance and / or an acquired chemoresistance. For example, the chemoresistance is acquired by one or more previous performed chemotherapies. For example, the chemoresistance which is counteracted by a compound targeting Tpm1.8 and / or Tpm1.9 according to the present invention is a chemoresistance to any chemotherapeutic agent in the art. For example, the chemoresistance which is counteracted by a compound targeting Tpm1.8 and / or Tpm1.9 according to the present invention is a chemoresistance against taxane- and / or platinum-based chemotherapy. For example, the chemoresistance which is counteracted by a compound targeting Tpm1.8 and / or Tpm1.9 according to the present invention is a chemoresistance against cisplatin- and / or paclitaxel. For example, the compound targeting Tpm1.8 and / or Tpm1.9 isoforms is used to restore chemosensitivity for any chemotherapy in the art. For example, the compound targeting Tpm1.8 and / or Tpm1.9 isoforms is used to restore chemosensitivity for taxane- and / or platinum-based chemotherapy. For example, the compound targeting Tpm1.8 and / or Tpm1.9 isoforms is used to restore chemosensitivity for cisplatin- and / or paclitaxel. For example, the compound targeting Tpm1.8 and / or Tpm1.9 isoforms according to the present invention counteracts chemoresistance and / or restores chemosensitivity at least partially, such as complete restoration of chemosensitivity of cancer to an anti-cancer therapeutic agent it was previously at least partially insensitive to. For example, the compound targeting Tpm1.8 and / or Tpm1.9 according to the present invention reduces a chemotherapeutic agent’s specific IC50 level by 10 – 100%, 20 – 95%, 25 – 90%, 30 – 85%, 35 – 80%, 40 – 75%, 45 – 70%, 50 – 65% or 55 – 60 % compared to the chemotherapeutic agent’s specific IC50 in an untreated control and / or compared to the chemotherapeutic agent’s specific IC50 before the use of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms. For example, the compound targeting Tpm1.8 and / or Tpm1.9 according to the present invention reduces a chemotherapeutic agent’s specific IC50 level by at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98 or 100% compared to an untreated control and / or compared to the chemotherapeutic agent’s specific IC50 before the use of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms. For example, the chemotherapeutic agent to which the cancer is resistant to is a taxane- and / or platinum-based chemotherapeutic agent, such as cisplatin- and / or paclitaxel. Screening methods The present invention further includes a method for identifying a compound targeting Tpm1.8 and / or Tpm1.9 isoforms for inhibiting, suppressing, preventing and / or treating proliferation, motility, invasion, migration, metastasis and / or chemo-resistance of a cancer. For example, the method comprises constructing a model of the N-terminus of Tpm1.8 and / or Tpm1.9, preferably of human Tpm1.8 and / or Tpm1.9, which contains the region of greatest diversity between the four TPM genes. For example, the model comprises the N-terminus at residues 4-16. Further, the method for identifying for example comprises performing a virtual in silico docking screen for identifying compounds that potentially bind Tpm1.8 and / or Tpm1.9, preferably in the N-terminus of Tpm1.8 and / or Tpm1.9, more preferably in the N-terminus of Tpm1.8 and / or Tpm1.9 at residues 4 – 16. For example, a virtual in silico docking screen of the ZINC database of database of purchasable compounds (Irwin et al. J. Chem. Inf. Model. 2020, 60, 12, 6065–6073), or other chemical database for lead compound discovery, is performed, using online available docking programs such as AutoDock, GOLD, Deep Docking, Glide, or POSIT. Candidate compounds can be purchased from vendors and tested in vitro or in vivo for their activity. For example, the method comprises contacting human fibroblasts with a test compound. The contacting is for example performed for at least 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 36, 48, 52 hours. Following the contacting, the human fibroblasts are for example fixed and stained. Staining is for example performed using Tpm1.8 and / or Tpm1.9 specific antibodies. Moreover, the method of identifying compounds according to the present invention for example comprises analyzing enrichment of Tpm1.8 and / or Tpm1.9 isoforms in the lamellipodium of the fibroblasts, wherein a fibroblast contacted with a test compound identified as compound targeting Tpm1.8 and / or Tpm1.9 isoforms according to the present invention shows reduced of enrichment of Tpm1.8 and / or Tpm1.9 isoforms in the lamellipodium compared to a control fibroblast. The compound facilitating a reduced enrichment of Tpm1.8 and / or Tpm1.9 isoforms in the lamellipodium compared to a control fibroblast is for example identified as a compound for use in a method of inhibiting, suppressing, preventing and / or treating cancer. The method of identifying compounds targeting Tpm1.8 and / or Tpm1.9 isoforms further comprises for example contacting a cancer cell that expresses Tpm1.8 and / or Tpm1.9 isoforms with a test compound. The cancer cell is for example an ovarian cancer cell. For example, the cancer cell, such as ovarian cancer cell, is contacted with a test compound in a concentration in the range of 5 – 50 µM, 15 – 30 µM, or 10 – 20 µM. Further, the method for identifying comprises measuring in the cancer cell the inhibition of Tpm1.8 and / or Tpm1.9 expression and / or activity, wherein the finding of an inhibitory effect (e.g. less than 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% or 10% of an appropriate (non-treated) control) identifies the test compound as a compound for use in a method of inhibiting, suppressing, preventing and / or treating cancer. For example, the compound identified by the method for identifying inhibits Tpm1.8 and / or Tpm1.9 expression and / or activity in a range of 10 – 100%, 20 – 95%, 25 – 90%, 30 – 85%, 35 – 80%, 40 – 75%, 45 – 70%, 50 – 65% or 55 – 60 % compared to an untreated cancer cell and / or compared to the cancer cell before the use of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms. For example, the compound identified by the method for identifying inhibits Tpm1.8 and / or Tpm1.9 expression and / or activity by at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 98 or 100% compared to an untreated cancer cell and / or compared to the cancer cell before the use of the compound targeting Tpm1.8 and / or Tpm1.9 isoforms. The present invention further provides a method for determining the presence of epithelial-to-mesenchymal transition (EMT) in cancer cells, comprising determining Tpm1.8 and or Tpm1.9 expression in said cells, whereby an increased expression relative to a control expression indicates EMT in said cells. A control expression may for instance be an expression of a household gene such as GAPDH. The expression is preferably determined by measuring the level of (m)RNA, but also protein may be measured as described elsewhere herein. The present invention further provides a method for determining the presence of epithelial-to-mesenchymal transition (EMT) in cancer cells, comprising determining RBM24 and / or ESRP1 expression in said cells, whereby an ESRP1 downregulation (or decreased expression relative to a control expression) and RBM24 upregulation (or increased expression relative to a control expression) indicates EMT in said cells. The invention further provides use of RBM24 and / or ESRP1 and / or Tpm1.8 / 9 as markers for determining cancer development, in particular for indicating that a cancer cell is in EMT, preferably an ovarian cancer cell. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the disclosure includes embodiments having combinations of all or some of the features described. The invention will now be exemplified by the flowing Example, which is for illustrative purpose only. EXAMPLES Example 1 Alternative splicing at a broad spectrum of target genes underlie epithelial to mesenchymal plasticity, metastatic dissemination, and resistance to chemotherapy in high-grade serous ovarian cancer. Material & Methods Cell cultures The human ovarian cancer cell line OV90, obtained from the American Type Culture Collection (ATCC), was cultured in a 1:1 mixture of MCDB 105 medium (M6395; Sigma Aldrich containing 1.5 g / L sodium bicarbonate) and Medium 199 (31150022; Thermo Fisher Scientific containing 2.2 g / L sodium bicarbonate) supplemented with 15% heat inactivated fetal bovine serum (FBS; #16140071, Thermo Fisher Scientific) and 1% Penicillin / Streptomycin (Pen / Strep; penicillin: 100 U / mL, streptomycin: 100 μg / mL; 15140122 Thermo Fisher Scientific). CAOV3 (ATCC), SKOV3 [European Collection of Authenticated Cell Cultures (ECACC) via Sigma], COV504 (ECACC), HEK293T (ATCC) cell lines were cultured in DMEM medium (11965092, Thermo Fisher Scientific) supplemented with 10% heat inactivated FBS, 2 mM L-glutamine (200 mM; 25030081; Thermo Fisher Scientific), and 1% Pen / Strep. PEA1 (ECACC) and PEA2 (ECACC) cell lines were cultured in RPMI 1640 medium (61870036, Thermo Fisher Scientific) with 10% FBS, 1% Pen / Strep, and 2 mM L-glutamine. The identity of each cell line was confirmed by DNA fingerprinting with microsatellite markers (Amelogenin, CSF1PO, D13S317, D16S539, D5S818, D7S820, THO1, TPOX, vWA, D8S1179, FGA, Penta E, Penta D, D18S51, D3S1358, D21S11) and compared with the analogous data provided by ATCC, EACC, and https: / / web.expasy.org / cellosaurus / (data not shown). Plasmid transfection and lentiviral transduction cDNAs encoding Tpms 1.6, 1.7, 1.8 and 1.9 were excised from the bacterial expression vectors pGEX or pET [from P.W.G. Schevzov et al., Tropomyosin isoforms and reagents, Bioarchitecture, 2011;1(4):135-64] and cloned into the mammalian expression vector pcDNA3.1(+). Stable transfections of ESRP1 (Sino Biological plasmid # HG13708- UT) and Tpm1.6 / 7 / 8 / 9 expression vectors were performed with the FuGENE HD transfection reagent (Promega, E2311) according to the manufacturer’s protocol, and selected with Geneticin (#10131035, Thermo Fisher Scientific). The inducible pSLIK-RBM24 vector was constructed using pDONR 233-RBM24 as entry plasmid (Horizon, #OHS6084) following Gateway Cloning instructions (11791- 020, Thermo Fisher Scientific). The inducible shZEB1 lentiviral vector was obtained as described in our previous study (18). For all of the above inducible vectors, ESRP1 (Horizon, V3THS_335722), shRBM24 (Horizon, V3SH11240-225117283) lentiviral constructs were packaged by psPAX2 (Addgene # 12260) and pMD2.G (Addgene # 12259) into HEK293T cells. The virus-containing supernatant was collected 24 h after transfection, filtered, and used to infect the OV90 and COV504 cell lines. Selection was applied with 750 ng / mL puromycin (#ant-pr-1, InvivoGen) or 800 μg / mL Geneticin for 1- 2 wk. Validation of ectopic expression and knockdown of target genes was conducted 72 h after transfection by qPCR and western blot. siRNA transfection siRNA target sequence for human Tpm1.6 / 7 was 5’- AAGCTGGAGCTGGCAGAGAAA-3’(codons 70-76 of TPM1.6 / 7 in exon 2b) and for human Tpm1.8 / 9 was 5’-CGAGAGGAAGCTGAGGGAGAC-3’(codons 38-44 of Tpm1.8 / 9 in exon 1b). Tpm siRNAs (Horizon Discovery, Waterbeach UK) and control siRNA (#4390843, Thermo Fisher Scientific) were transfected by Lipofectamine RNAiMAX (#13778150, Invitrogen) according to the manufacturer’s instructions. Seventy-two hrs. following siRNA transfection, cells were collected for RNA and protein analysis. To evaluate the effect of gene knockdown on drug resistance, cells were seeded 24 hrs. after siRNA transfection at a density of 5,000 cells / well, followed by 3 days of incubation in the presence of cisplatin (#PHR1624, Sigma-Aldrich) or paclitaxel (#S1150, Selleck Chemicals). RT-qPCT and PCR analyses Total RNA was isolated using the TRIzol reagent (Thermo Fisher Scientific, 15596018) followed by reverse transcription using high-capacity cDNA reverse transcription kit (Life Technologies, 4368814), according to the manufacturer's instructions. RT-qPCR was performed using the Fast SYBR Green Master Mix (#4368708, Thermo Fisher Scientific) on an Applied Biosystems StepOne Plus Real-Time Thermal Cycling Research device, with three replicates for each analysis. Relative gene expression was determined by normalizing the expression of each target gene to that of GAPDH. Results were analyzed using the 2-(ΔΔCt) method. RT-qPCR primers are listed in Supplementary Table 4. Western analysis Cells were lysed in 2X Laemmli buffer (4% SDS, 48% Tris 0.5M pH6.8, 20% glycerol, 18% H2O, bromophenol blue and 10% 1M DTT), and subjected to SDS-PAGE, followed by transfer onto polyvinylidene fluoride (PVDF) membranes (Bio-Rad). After blocking with 5% milk in TBS-Tween, the membranes were incubated with primary antibodies directed against ESRP1 (1:1000, # PA5-25833, Thermo Fisher Scientific), RBM24 (1:100, #18178-1-417 AP, Proteintech), TPM1 (1:1000, #MBS127505, MyBioSource) and β-actin (1:2000, #4970, Cell Signaling). The secondary Ab was a goat anti-rabbit immunoglobulins / HRP (1:10000, #P0161, DAKO)(1:10000, #P0448, DAKO). Detection was by the Pierce ECT western blotting substrate (#34578, Thermo Fisher Scientific) using the Amersham AI600 imager (GE Healthcare). Flow cytometry analysis and sorting Single-cell suspensions in PBS supplemented with 1% FBS were incubated with anti-EpCAM-FITC (1:20, #GTX30708, Genetex), and anti-CD44-APC (1:20, #559250, BD Pharmingen) antibodies for 30 min on ice and analyzed on a FACSAria III Cell Sorter (BD Biosciences). CD44hiEpCAMhiand CD44hiEpCAMloOV90 and CAOV3 cells were sorted and incubated in a humidified atmosphere at 37ºC with 5% CO2 for 3-5 days before RNA or protein were collected as described above. Patient-derived ascites were first washed 1-2 times with 1×RBC lysis buffer [150 mM NH4Cl (#7173-51-5, Sigma Aldrich), 10 mM KHCO3 (#298-14-6, Sigma Aldrich), 100 µM EDTA (#60-00-4, Sigma Aldrich)] to remove erythrocytes. The cell pellets were then labeled with anti-CD90.1 (Brilliant ^ ^Violet 421; 1:20, #328122, Clone:5E10, BioLegend), anti-CD45-APC (1:20, #304037, Clone: HI30, BioLegend), and SYTOXTMRed (1:1000, #S34859, Thermo Fisher Scientific) antibodies, and sorted by FACS. RNA from CD45- CD90- and CD45- CD90+ cells was isolated directly after FACS sorting. Cell proliferation assays To analyze cell proliferation rates, 2×103ovarian cancer parental cells and Tpm1.6 / 7 / 8 / 9-OE cells were plated into 96-well plates and incubated at 37°C, 5% CO2. After 24 hrs. (day 1), cells were incubated at 37ºC, 5% CO2 for 3 hrs. in culture medium supplemented with 0.45 mg / mL MTT [(3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide; Sigma-Aldrich]. The 96-well plates were then centrifuged at 1,000 rpm for 5 min and the culture medium removed. O.D. reading was performed at 595 nm with a microplate reader (Model 550, Bio-Rad). Background measurements were subtracted from each data point. Experiments were performed in triplicate for each individual cell line. Cell migration and invasion assays Migration assays were conducted using 8 μm pore PET Transwell inserts (#353097, BD Falcon™) and TC-treated multi-well cell culture plates (#353047, BD Falcon™).5×104443 cells were seeded in the upper chamber with 100 μL of serum-free culture medium. Culture medium supplemented with 10% FBS was used as a chemoattractant in the lower chamber. After 24 h, cells that migrated to the lower chamber were fixed with 4464% PFA (#9713.9010, VWR Chemicals), stained with 0.1% Trypan Blue solution (#15250061, Thermo Fisher Scientific) and counted using a microscope. The invasion assays were conducted as described here above with the only addition of 200 μL Matrigel mixed with 10-20 µl of a 0.01 M Tris (pH 8.0) / 0.7% NaCl solution on top of the Transwell-Clear insert and incubated at 37°C for 2 h. After having removed the excess liquid, 5×104450 cells were added to the well in 150 μL serum-free medium. Next, 0.5 mL of culture medium supplemented with 10% FCS was added. After 24 h, the cells that invaded the lower chamber were fixed with 4% PFA and stained with 0.1% Trypan Blue solution. Cells were counted using a microscope. 200 μL collagen mix [7.5% 10 × PBS, 57% collagen, 0.1% 1M NaOH, 9.5% H2O and 25% culture medium] were plated into scaffolds and incubated at 37°C for 1h. 5×104 455 cells were added on top of the solid collagen and incubated at 37°C. After 1 week, the entire scaffold with cells and collagen was fixed with 4% PFA and embedded in paraffin. 4 μm sections were mounted and counterstained with Hematoxylin. Slides were dehydrated and mounted in Pertex (#00811, Histolab). Immunohistochemistry – cultured cells 0.5-1×104cells were plated into 24-well plates containing glass cover slips coated with 0.2% gelatin. After 6-24 h, culture medium was removed, ice-cold methanol added to each well and plates incubated for 20 min at 40 °C. Cells were washed twice with PBS, and incubated in 0.2% Triton for 20 min with rotation. Cells were blocked in 2% FBS in PBS for 1 h. Primary antibodies for Tpm1.6 / 7 (1:200, from P.W.G.), Tpm1.8 / 9 (1:200, from P.W.G.), Arp2 (1:200, #ab47654, Abcam) were added and incubated O / N at 40 °C. Cells were washed twice with PBS, and secondary antibodies [goat anti-rat Alexa Fluor 488 conjugate (1:250, #A10528, Life Technologies); goat anti-rabbit Alexa Fluor 546 conjugate (1:250, #A11035, Life Technologies); goat anti-mouse Alexa Fluor 647 conjugate (1:250, #A32728, Life Technologies)] and DAPI (#D1306, Thermo Fisher Scientific) added. Slides were mounted using VECTASHIELD® (#H100010, VECTOR laboratories) and cells imaged using a LSM-700 (Zeiss) with 20×, 40×, 63× lenses. Images were analyzed using ImageJ. Immunochemistry – patient samples Formalin-fixed, paraffin embedded (FFPE) ovarian cancer patient tissue blocks were obtained from the Department of Pathology, Erasmus Medical Center, Rotterdam. The average fixation time was 1-2 yr. 4 μm sections were mounted on slides, dewaxed with Xylene (#28979.294, VWR Chemicals) and hydrated. Antigen25 retrieval was performed in Tris-EDTA buffer (pH 9.0) using a pressure cooker procedure. Slides were incubated in 3% hydrogen peroxidase (#95321, Sigma Aldrich) at RT for 10 min and blocked with 5% milk (#115363, Millipore) in PBS-Tween (#P1379, Sigma Aldrich) for 30 min. Immunohistochemistry was performed using antibodies directed against Tpm1.6 / 7 (1:100), Tpm1.8 / 9 (1:100) and mitochondria (1:100, #MAB1273, Sigma Aldrich) followed by the EnVision Plus-HRP system (Dako). Slides were incubated with primary antibodies O / N at 4°C, washed twice with PBS-Tween and incubated with Rat EnVision+ System-HRP (#P0405, Dako) or Mouse EnVision+ System-HRP (#K4007, Dako) for 30 min. Slides were counterstained with Hematoxylin (#MHS16, Sigma Aldrich). In vivo study Mouse experiments were performed according to the Code of Practice - Animal Experiments in Cancer Research, Netherlands Inspectorate for Health Protection, Commodities and Veterinary Public Health, and the Animal Experiment Committee (DEC). 6-8-week-old NOD.Cg-Prkdcscid Il2rgtm1Wjl 485 / SzJ (NSG) female mice were used. 50 μl PBS containing 1x105486 OV90 cells overexpressing Tpm1.6 / 7 / 8 / 9 isoforms was injected IP into each mouse.150 mg / kg D-luciferin (#L2916, Invitrogen) was injected IP for bioluminescence signal. After 10 min of isoflurane-induced anesthesia (#B506, Zoetis), the bioluminescence of the mouse was measured using the IVIS Spectrum imaging system (Caliper Life Science, Hopkinton, MA) and bioluminescence analyzed using LIVINGIMAGE 4.4 software (Caliper Life Science). Ascites was obtained by syringe, and tumoroids collected and washed with RBC lysis buffer. Mice were sacrificed and tissue fixed in 4% PFA for further analysis. Mouse tumoroid culture Mouse ascites with tumoroids were collected. Tumoroids were washed with RBC lysis buffer 1-2 times, then plated in 24-well ultra-low attachment surface plates (#33019010, Corning). Tumoroids were cultured in a 1:1 mixture of OV90 medium and advanced DMEM / F12 medium (#2322978; Thermo Fisher Scientific) containing 4% B27 (#A1895601, Life Technologies), 2% N-2 supplement (#11520536, Thermo Fisher Scientific) and 0.04% EGF (#PMG8045, Invitrogen). BaseScope Assay BaseScope assays were performed following the guidelines from ACD (Advanced Cell Diagnostics, Newark, CA). 4 μm sections were cut onto Superfrost plus slides (#10149870, Thermo Fisher Scientific) and stored O / N at RT. Sections were baked for 1 h at 60°C before deparaffinizing in xylene and 100% ethanol. Sections were dried for 5 min at 60°C , incubated in hydrogen peroxide at RT for 10 min, underwent target retrieval for 15 min at 100°C, and protease treatment for 30 min at 40°C. BaseScope probes were added and slides incubated in an oven for 2 h at 40°C before adding reagents AMP1 (30 min at 40°C), AMP2 (30 min at 40°C), AMP3 (15 min at 40°C), AMP4 (30 min at 40°C), AMP5 (30 min at 40°C), AMP6 (15 min at RT), AMP7 (30 min at RT) and AMP8 (15 min at RT). Fast Red A and B was added to slides and incubated for 10 min at RT, then counterstained with Gill’s hematoxylin. Slides were dried for 15 min at 60°C, then mounted in VectaMount permanent mounting medium (H5000, Vector labs). Images were taken using an LSM-700 with 40× lens. Chemoresistance and IC50 measurement Cells were seeded in 96-well plates at 5000 cells / well and left O / N to adhere. Three technical replicates were plated per tested condition. Both cisplatin (#PHR1624, Sigma-Aldrich) and paclitaxel (#S1150, Selleck Chemicals) were dissolved in DMSO (#D2650, Sigma Aldrich). Cells were incubated for 3 days with cisplatin and paclitaxel. After removal of the chemotherapeutic drug, cells were washed with PBS and left to re- grow in standard culture medium for 1 day. Cell viability was assessed using the MTT as described previously (Sacchetti et al. eLife. 2021;10). Absolute viability values were converted to percentage viability versus DMSO control treatment, then non-linear fit of log(inhibitor) versus response was performed in GraphPad Prism v7.0 to obtain an IC50 values. TOP-Flash reporter assay For the β-catenin / TCF reporter assay (TOP-Flash reporter assay), cells were plated on 48-well dishes. After 48 h, when 70% confluence was reached, cells were transfected by Fugene HD with 125 ng of the TOP-Flash or FOP-Flash reporter constructs together with 25 ng of the Renilla luciferase vector for normalization purposes. Luciferase activity was measured using the Dual-Luciferase Reporter Assay System (#E1910, Promega) 24 h post-transfection. Luminescence was measured using a GloMax Luminometer (#9100-102, Promega). Identification of compounds targeting TPM1.8 / 1.9 A model of the N-terminus of human Tpm1.8 (identical for Tpm1.9) containing the region of greatest diversity between the four TPM genes (residues 4-16) was constructed. A virtual in silico docking screen of the ZINC database was performed and 6 compounds with the best docking scores were purchased from suppliers. Human fibroblasts were exposed to each of the six compounds or vehicle alone for 24 hr, fixed and stained for Tpm1.8 / 9 using isoform specific antibodies (Brayford et al, 2016. Current biology: CB. 26(10):1312-8). Control cells show strong enrichment of Tpm1.8 / 9 in the lamellipodium (Brayford et al, 2016). Two of the compounds, Tpm1.8 / 9-1 and -3, prevented enrichment in the lamellipodium at 10 and 20 μM. They were selected for further studies. Alternative splicing analysis EpCAMhi / lo RNASeq data was obtained from the ovarian cancer cell lines OV90 and CAOV3 and the sequencing reads mapped to GRCh37.p13. genome by STAR55 (https: / / www.gencodegenes.org / human / release_19.html). MISO56 was used to quantify AS events with annotation from https: / / miso.readthedocs.io / en / fastmiso / index.html#iso- centric. The MISO uses the alternative exon reads and adjacent conservative reads to measure the percentage of transcript isoform with specific exon included, termed Percentage Spliced In (PSI or Ψ). The PSI ranges from 0 (i.e. no isoform includes a specific alternative exon) to 1 (i.e. all of the isoforms detected comprise the alternative exon). We removed alternative events with low expression of related transcript isoforms if less than 3 samples in a dataset had more than 10 informative reads to calculate the PSI. Next, we compared the PSI between EpCAMhiand EpCAMlogroups in the OV90 and CAOV3 ovarian cancer cell lines. AS events were defined as differentially spliced events when the difference of mean PSI between two groups (Δpsi; differential Percentage Spliced In) was >10%. RNA seq analysis of subpopulations in OV90 and CAOV3 RNA was isolated from sorted populations with Trizol reagent. Libraries were prepared with the TruSeq RNA sample prep kit v2 (Erasmus MC, Biomics). Samples were sequenced with Illumina HiSeq 2000 and adapter sequences were removed with Trimmomatic (v.0.33). Subsequently, the reads were mapped in a two-pass procedure to the human reference genome build hg38 with the RNA-seq aligner STAR (v2.4.2a) (Dobin et al. Bioinformatics. 2013;29(1):15-21) using the Homo sapiens GENCODE v23 annotations. Raw counts were imported in DESeq2 (v1.36.0) and normalized with a variance stabilizing transformation (VST)(Love et al. Genome Biol. 2014;15(12):550). Differential expressed genes were identified by comparing Epcamlow versus Epcamhigh / bulk samples using absLogFC > 1.5 and padj < 0.05, and visualized with the ComplexHeatmap package (v2.12.1) after a z-score scaling. Pathways activity was evaluated using gene set enrichment analysis (fgsea v1.22.0) on the hallmark gene sets from the Molecular Signature data base (Korotkevich et al. 2021. bioRxiv www.doi.org / 10.1101 / 060012). RNA seq analysis of TPM1 OE in OV90 Paired end mRNA sequencing was performed with the DNA Nanoball sequencing (DNBseq) technology till a depth of 25M reads per sample (BGI Genomics, Shen Zhen). Adapter trimming and quality filtering was performed using the SOAPnuke pipeline (BGI Genomics). Clean fastq files were aligned to the GRCh37 reference genome with RSEM (v1.3.3)( Li et al. BMC Bioinformatics.2011;12:323) using the STAR aligner (v2.7.9a) (Dobin et al. Bioinformatics. 2013;29(1):15-21). Gene level data was imported with tximport (v1.24.0) and downstream analysis was performed using DESeq2 (v1.36.0)(Love et al. Genome Biol. 2014;15(12):550). Counts were normalized with a variance stabilizing transformation (VST). Gene set activity was evaluated with a gene set variation analysis (GSVA, v1.44.5)(Hanzelmann et al. BMC Bioinformatics. 2013;14:7) using the Hallmark gene set from the Molecular Signature database and visualized with the ComplexHeatmap package (v2.12.1). Principal component analysis was computed using the top 500 genes with highest row variance. Differential expression analysis was performed by comparing the TPM1.6 / 7 samples with the TPM1.8 / 9 samples and results were displayed with a volcano plot using EnhancedVolcano (v1.14.0). scRNAseq analysis of ovarium cancer cells Publicly available data from Vázquez-García et al. were retrieved from CellxGene portal (Vazquez-Garcia et al. Nature. 2022;612(7941):778-86). Downstream analysis was performed in Seurat (v4.3.0) (Hao et al. Cell. 2021;184(13):3573-87 e29). An Epcamlow signature was evaluated with AddModuleScore based on the previously identified upregulated gene list (N = 38). A threshold (>0.1) was used to annotate cells with the highest association to the Epcamlow signature (“low-like cells”, 4% of cancer cells). Next, low-like cells were visualized on the integrated UMAP embedding from Vázquez-García et al. (supra) and pathway activity of clusters encompassing low-like cells were visualized with ComplexHeatmap. After approval of a data transfer agreement, FASTQ files from Izar et al. (Nat Med.2020;26(8):1271-9) were downloaded from the TerraBio repository and processed with RSEM using the STAR aligner to the hg19 human reference genome with isoform annotation from UCSC (Love et al. Genome Biol. 2014;15(12):550; Li et al. BMC Bioinformatics.2011;12:323). Files were imported with tximport (v1.24.0) and cells were selected that contained at least 500 different genes (nFeature_RNA > 500). Cells were clustered (kmeans, k = 4) according to the percentage of their respective TPM1 isoform expression and subsequent analysis was performed in Seurat (v4.3.0), where TPM1.7 expressing cells were compared to TPM1.9 with FindMarkers. A gene set enrichment analysis was performed using the Hallmark gene set and pathways were filtered according to similar activity in the OV90 cell line and patient data. Survival analysis of TPM1 in TCGA OVCA RSEM processed data from the TCGA cohort was downloaded from the tsvDB (Sun et al. BMC Genomics. 2018;19(1):405). Data was log2 transformed and survival analysis was performed with the survival package. Survival curves were generated with the survminer package for the whole TPM1 gene, TPM1.7 (isoform_uc002alk) and TPM1.9 (isoform_uc002alt) based on clinical data on overall survival (Therneau & Grambsch. Modeling Survival Data: Extending the Cox Model. Springer-Verlag New York 2000). Data availability RNA sequencing data has been deposited to the Gene Expression Omnibus (GEO) and can be accessed using the following identifiers: GSE192920 (subpopulations in OV90 and CAOV3), GSE231560 (TPM1 OE in OV90). Other single cell RNA sequencing data used in this study are publicly available and can be accessed from GEO for the SmartSeq2 data [GSE146026 (Izar et al., supra)] and from Synapse for the 10X Genomics data [syn25569736 (Vázquez-García et al., supra)]. Statistical analysis For statistical comparison, we performed unpaired t test. Statistical analyses were performed using Prism 7 software (GraphPad). Data with statistical significance are as indicated. Information on replicates, independent experiments and statistical test can be found in the description of the drawings. Results A subpopulation of quasi-mesenchymal cells co-exists with epithelial cells in high-grade serous ovarian cancer. Following the experimental strategy previously adopted to identify subpopulations of quasi-mesenchymal cells in immortalized colon cancer cell lines, we analyzed the HGSOC cell lines OV90, SKOV3, COV504, and CAOV3 by FACS with CD44 and EpCAM antibodies. Distinct distributions of CD44hi EpCAMhiand CD44hi EpCAMlocells (from here on referred to as EpCAMhiand EpCAMlo, respectively) earmarked each line albeit in different percentages. Upon sorting and short-term culturing, EpCAMlocells showed a mesenchymal-like morphology, in contrast with the epithelial appearances of their EpCAMhicounterparts. Accordingly, EpCAMlocells showed increased migration and invasion capacity in trans-well assays. In order to elucidate the global gene expression profiles of the two distinct subpopulations of ovarian cancer cells, RNAseq analysis was carried out on the EpCAMhi / locells sorted by FACS from the OV90 and CAOV3 lines. Principal component analysis (PCA) by multidimensional scaling (MDS) revealed a clear separation of the quasi-mesenchymal EpCAMlocells from their epithelial counterpart in the second dimension. Unsupervised clustering of the RNAseq data highlighted differentially expressed genes between the EpCAMloand EpCAMhisubpopulations from the two cell lines. Among these genes, different EMT transcription factors (EMT-TFs; ZEB1 / 2, RUNX2, SNAI2), EMT target genes (CDH1, VIM), and EMT- related RBPs (ESRP1, RBM24) earmarked EpCAMlocells in both OV90 and CAOV3. Accordingly, pathway analysis (PA) of the genes whose expression earmarks the quasi- mesenchymal ovarian cancer cells revealed significant associations with EMT, KRAS signaling, and several TNF- and interferon-related inflammatory pathways. To confirm the central role played by EMT in the establishment of the EpCAMloidentity as indicated by the PA analysis, ZEB1 expression was downregulated by shRNA in the OV90, SKOV3, and COV504 cell lines. As expected, FACS analysis of these cells shows that knockdown of this the differentially expressed EMT-TF results in a substantial reduction of the EpCAMlosubpopulation. To demonstrate the clinical relevance of the above data obtained from immortalized cancer cell lines, publicly available single-cell RNAseq data from 42 patient-derived ovarian cancers were employed to search for quasi- mesenchymal cells reminiscent of the EpCAMlosubpopulation. To this aim, we took advantage of the EpCAMlosignature derived from the above RNAseq analysis of the OV90 and CAOV3 cell lines. After classifying patient-derived cancer cells according to the EpCAMlosignature, approx.60% were found to cluster into one of the three subpopulations of HGS ovarian cancer cells defined in the original study by Vazquez- Garcia et al. Ovarian cancer mutational processes drive site-specific immune invasion, Nature, 2022;612(7941:778-86) as EMT-like (labeled as #2, #4, and #6). Of note, a substantial fraction of the EpCAMlo-like cells fell outside the three clusters indicative of large heterogeneity of cellular identities reminiscent of the quasi-mesenchymal state in the cell lines. Cells from within the EpCAMlo-like clusters were more represented in metastases and ascites (i.e. non-adnexa including omentum, peritoneum, etc.) when compared with primary tumors. We then evaluated module scores from the Hallmark gene sets across the EpCAMlo-like clusters in primary ovarian cancers (adnexa), ascites, and metastases (non-adnexa). EMT and inflammatory signaling pathways (TNFα, IL6 / Jak / Stat3, IFN, and TGFβ) were significantly upregulated in EpCAMlo-like clusters, in particular in cluster #2 in ascites and metastatic lesions. Collectively, these results indicate that, HGSOC cell lines encompass subpopulations of quasi-mesenchymal cells endowed with increased motility and invasive capacity, and characterized by EMT-TFs the expression of which is central to their cellular identity. Similar subpopulations of ovarian cancer cells are found in patient-derived primary and metastatic lesions, and in malignant ascites. Differential expression of RNA-binding proteins underlies alternative splicing of a subset of target genes in quasi-mesenchymal ovarian cancer cells. Several RNA-binding proteins (RBPs) known to be involved in alternative splicing are differentially expressed between EpCAMlo and EpCAMhicells in colon cancer cell lines and play significant functional roles in controlling E-to-M and M-to-E transitions and phenotypic plasticity during local dissemination and distant metastasis. Several differentially expressed RBPs likely to play an active role in EMT-related alternative splicing between epithelial- and mesenchymal-like subpopulations of ovarian cancer cells. ESRP1 and RBM24 were respectively down- and upregulated in EpCAMlocells in both cell lines. Moreover, other RBPs (i.e. ESRP2, RBM47, RBMS3, and QKI) were differentially expressed in one of the cell lines examined. The EpCAMlo-specific up- and downregulation of RBM4 and ESRP1, respectively, was validated by RTqPCR and western analysis of the subpopulations sorted from the OV90 and COV504 cell lines. Differentially spliced genes were analyzed by MISO (Mixture of Isoforms) and the results were filtered by selecting ΔPSI (differential Percentage Spliced In) values >10% and by comparing them with the corresponding lists of AS targets previously found in colon cancer cell lines. The large majority of ovarian cancer AS targets was not found in colon cancer. Among the ovarian-specific AS targets with a known function in EMT (n=39), diverse cellular components, e.g. extracellular matrix, focal adhesion, and the actin cytoskeleton, and cellular processes, e.g. ECM organization,integrin- and TGF-β- mediated signaling, and cell migration were represented (Figure 3). In particular, the presence of Tropomyosin 1 (TPM1), a member of a broad family of actin-binding proteins, was noteworthy both because of the high ΔPSI values in OV90 and CAOV3 cells and because of its known cellular function, i.e. in the cytoskeleton of non-muscle cells and in the contractile system of striated and smooth muscles. Although a direct causative role between TPM1 and EMT has not been reported yet, previous studies have shown that TGF-β signaling increases expression of high-molecular weight tropomyosins together with the formation of actin stress fibers thus affecting cell motility and invasion. Notably, the TPM1 AS-pattern observed in ovarian cancer involved exons 1a / 2a, which earmark the Tpm1.6 / 7 isoforms upregulated in EpCAMhicells, and exon 1b, featuring the Tpm1.8 / 9 isoforms upregulated in EpCAMlo, as validated both by RT-qPCR and western blot analysis. Of note, the western results relative to Tpm1.8 / 9 clearly match the RNA-based analysis, whereas the same is less evident for Tpm1.6 / 7 that, at the protein level, seem to undergo more subtle variations. As a further validation of these results, HGS ovarian cancer cell lines exclusively encompassing EpCAMhi(PEA2) or EpCAMlo(PEA1) cells, solely expressed the TPM1.6 / 7 and TPM1.8 / 9 isoforms, respectively. In order to establish a cause-effect relationship between the differential expression of ESRP1 and RBM24 in EpCAMloovarian cancer cells and the observed downstream AS targets using TPM1 as a model, RBP knockdown and overexpression assays were performed in OV90 and COV504 cell lines. First, as predicted by their unique EpCAMhi / lodistribution, the PEA1 and PEA2 cell lines exclusively express RBM24 and ESRP1, respectively. Accordingly, both ESRP1 knockdown and RBM24 ectopic expression in the OV90 and COV504 cell lines resulted in the up- and downregulation of the Tpm1.8 / 9 and Tpm1.6 / 7 isoforms, respectively, both at the RNA and protein levels. Vice versa, RBM24 knockdown and ESRP1 ectopic expression resulted in the up- and downregulation of the Tpm1.6 / 7 and Tpm1.8 / 9 isoforms, respectively (Figure 1A-B). Of note, the observed changes in RBP expression were also accompanied by a pronounced increase of the EpCAMlosubpopulation as validated by FACS analysis. Concurrent RBM24 overexpression and ESRP1 knockdown had significant effects not only on the TPM1 isoform shift but, more importantly, on the relative percentages of the EpCAMhi / losubpopulations when compared with the single RBP gain- and loss-of-function assays. The latter indicate that alternative splicing driven by RBM24 and ESRP1 up- and down-regulation is a main regulator of EMT in ovarian cancer cells. Overall, these results showed that epithelial and quasi-mesenchymal subpopulations of HGS ovarian cancer cells are earmarked by the differential expression of specific RBPs known to be involved in alternative splicing. Accordingly, differential AS patterns of a subset of EMT-related target genes characterize the EpCAMlocells. While some AS target genes are shared with those previously identified in colon cancer, the majority appear to be specific for ovarian cancer. Among these, TPM1 is of interest in view of both its function as an actin-binding cytoskeletal protein in various cell types and of its previously reported role as a tumor suppressor in breast cancer. Transcriptional and functional consequences of TPM1 isoforms on quasi-mesenchymal ovarian cancer cells. To assess the functional relevance of the specific TPM1 isoforms, their ectopic expression was induced and validated by RT-qPCR and western blot analysis in multiple ovarian cancer cell lines (OV90, COV504, PEA1 and PEA2)(Figure 2A-B). Cell viability and proliferation assays indicated that Tpm1.6 / 7 and Tpm1.8 / 9 expression was significantly associated with increased and decreased rates of cell division, respectively (Figure 2C). Of note, ectopic expression of Tpm1.8 / 9 in OV90 and COV504 cells resulted in a complete growth arrest within 6 days. Moreover, trans-well assays clearly showed that Tpm1.8 / 9 overexpression resulted in significantly increased migratory and invasive features when compared with Tpm1.6 / 7 (Figure 2D). Tpm1.8 / 9-overexpressing (OE) ovarian cancer cells appeared to invade the collagen layer collectively, as narrow linear strands with “leader”and “follower”cells (Figure 2E). The latter observation is of interest since in non-muscle cells Tpm1.8 / 9 are specifically expressed in lamellipodia, i.e. the membrane protrusions found at the leading edge driven by branched as well as unbranched filaments composed of actin and Tpm1.8 / 9 that promote cell motility. IF analysis with TPM1 isoform-specific antibodies confirmed the co-localization of Tpm1.8 / 9 and ARP2, a specific marker for lamellipodia, at the edge of ovarian cancer cells; instead, Tpm1.6 / 7 were mainly localized in the cytoplasm (Figure 2F). In order to carry out a more comprehensive study of the transcriptional and functional consequences of the ectopic expression of the specific TPM1 isoforms, RNAseq analysis was carried out on the OV90 overexpressing cells. Unsupervised hierarchical clustering and principal component analyses confirmed the distinct transcriptional identity of the OV90 parental, Tpm1.6 / 7-OE, and Tpm1.8 / 1.9-OE cells. Gene set enrichment analysis (GSEA) was then performed to allow the identification of specific signaling pathways and gene ontology functions characteristic of each of the above sample groups. As shown in the heatmap of Figure 3A, TPM1.8 / 9 overexpression resulted in the pronounced activation of Hedgehog, Wnt / β-catenin, TGF-β, and Notch signaling, i.e. pathways known to be involved in the induction and regulation of EMT. Accordingly, EMT was also found to earmark these cells, as also shown by the distinct expression patterns of several EMT-related genes between Tpm1.6 / 7- and Tpm1.8 / 9-OE samples (Figure 3B). To functionally validate the activation of the canonical Wnt / β-catenin signaling pathway, TopFLASH reporter assays was implemented. As shown in Figure 3C, a ~10- fold increase in luciferase activity was observed upon ectopic expression of the individual Tpm1.8 and 1.9 isoforms. Likewise, Wnt signaling activity was significantly reduced upon Tpm1.8 / 9 siRNA-driven knockdown. Overall, these results show that the TPM1 isoforms confer specific functional features on ovarian cancer cells. In particular Tpm1.8 / 9 isoforms are strongly associated with EMT-inducing and inflammatory signaling pathways likely to underlie ‘transcoelomic’ dissemination of ovarian cancer cells and the formation of ascites. However, their ectopic overexpression is also a potential source of artifacts as EMT is equally essential as is MET in the formation of intra-abdominal metastases. Tpm1.8 / 9 isoforms confer resistance to taxane- and platinum-based chemotherapy and are expressed in ovarian cancer patients-derived ascites. To investigate the role played by TPM1 alternative splicing in women suffering from ovarian cancer, patient-derived tumor tissues were examined by immunohistochemistry (IHC) and in situ hybridization (ISH) analyses with isoform- specific antibodies and oligonucleotide probes. Among the high- and low-grade serous tumors analyzed (n=13), Tpm1.6 / 7 appeared to be consistently expressed in primary and metastatic lesions (Figure 4A). In contrast, Tpm1.8 / 9 expression was virtually undetectable above background levels, with few cases showing patchy and enhanced staining. Although based on an admittedly limited number of tumors, these observations seem to suggest that, while the Tpm1.6 / 7 isoforms are mainly expressed in the bulk of epithelial tumor cells, their Tpm1.8 / 9 counterparts are only rarely observed possibly in association with late and chemo-resistant stages of the disease. The formation of intra- abdominal ascites predominantly occurs in stage III and IV ovarian cancer patients due to the spreading of tumor cells to the peritoneum and the obstruction of lymphatic vessels. As such, ascites-derived tumor cells may encompass quasi-mesenchymal and chemo-resistant cell types en route to the metastatic colonization of abdominal organs. Hence, we evaluated whether the Tpm1.8 / 9 isoforms are transiently expressed in ovarian cancer patient-derived ascites when compared with Tpm1.6 / 7. Ascites samples from n=13 patients were collected and the cellular content was sorted by FACS according to the [CD45(Lin)- / CD90+ 233 ] and [CD45(Lin)- / CD90-] gates, encompassing immune / stromal and cancer cells, respectively. Total RNA was then extracted from the sorted cells for RTqPCR analysis of TPM1 isoform expression. Increased Tpm1.8 / 9 expression was observed in the ascites-derived cancer cells (CD90-) when compared with Tpm1.6 / 7. Among the immune / stromal cells (CD90+ 237 ), Tpm1.6 / 7 expression levels were increased when compared with Tpm1.8 / 9. Last, expression profiles from the Cancer Genome Atlas (TCGA) project were employed and the TCGA Splicing Variants Database (TSVdb; http: / / www.tsvdb.com / ) and integrated the clinical follow-up data with the expression of TPM1 (whole gene) and its isoforms. Kaplan-Meier analysis was borderline significant for the TPM1 gene and its Tpm1.6 / 7 isoforms, whereas the p values for Tpm1.8 / 9 were both >0.05. The latter is not surprising in view of the very low expression level of these low-molecular weight isoforms in primary ovarian cancer from which the TGCA data are derived. In view of these results pointing at the specific Tpm1.8 / 9 upregulation in ovarian cancer ascites, i.e. at late and recurrent disease stages often in association with chemo- resistance and poor prognosis, we asked whether the same TPM1 isoforms may confer resistance to the platinum- and taxane-based therapies commonly employed in the clinical management of ovarian cancer. Therefore, the OV90 parental cell line was cultured in the presence of two distinct chemotherapeutic agents, namely cisplatin and paclitaxel, and then analyzed TPM1 isoform expression in cells surviving the treatment. RTqPCR analysis revealed a dramatic downregulation of Tpm1.6 / 7 expression with both agents when compared with the untreated parental cells. In contrast, Tpm1.8 / 9 expression appeared to increase in cells surviving both the cisplatin- and paclitaxel-treatment (Figure 4B). Dose-response curves with OV90 cells ectopically expressing the individual isoforms confirmed that Tpm1.8 / 9-OE cells displayed a 40-fold higher resistance (IC50=3.266 / 3.414 µM) than Tpm1.6 / 7 OE cells (IC50=0.078 / 0.043 µM) upon cisplatin treatment (Figure 4C). The same was also observed with paclitaxel (IC50=1.28 / 1.66 µM for Tpm1.8 / 9-OE; IC50=0.017 / 0.015 µM for Tpm1.6 / 7-OE cells). To validate this observation, siRNA assays were developed to selectively downregulate the Tpm1.6 / 7 and Tpm1.8 / 9 isoforms in parental OV90 cells and assess their chemo-resistance. As shown in Figure 4D-E, the specific downregulation of the Tpm1.8 / 9 isoforms, validated both at the RNA and protein levels, reduced the cisplatin- and paclitaxel-specific IC50, while the opposite was true for the siRNA-driven knockdown of Tpm1.6 / 7. Tpm1.8 / 9-specific small molecule inhibitors for ovarian cancer therapy Given the newly uncovered role played by the Tpm1.8 / 9 isoforms in ovarian cancer and the broad spectrum of consequences at the cellular and molecular level that their specific inhibition may exert on cell motility and proliferation, EMT / MET, several oncogenic signalling pathways including Wnt, and therapy resistance, the development of small molecule antagonists may provide novel tools in the clinical management of late- stage ovarian cancer. Differences in the N-and C-termini between tropomyosin isoforms provide an opportunity to develop compounds that preferentially target specific isoforms. Compounds that target the C-terminus of Tpm3.1 have been shown to inhibit the function of this isoform both in vitro and in vivo by incorporating into the overlap junction between adjacent dimers in actin / Tpm3.1 co-polymers. Compounds targeting the N-terminus show similar activity. Based on the differences in the N-terminal sequences of exon 1b in the TPM1, TPM3, and TPM4 genes, compounds were developed that target Tpm4.2 and Tpm1.8 / 9. In silico docking of compound libraries with the models was used to identify compounds with high docking scores. Tpm1.8 / 9 docking identified 6 candidate compounds that were tested for biological activity in fibroblasts based on their ability to disperse the target Tpm1.8 / 9 away from actin-containing structures in the lamellipodium. The two compounds, 3-(2-Methyl-indol-1-yl)- propylamine (PubChem CID 6494468) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468), showed activity in the low micro molar range. In order to functionally validate the two compounds, their most effective concentration was determined in the 0 to 10 μM (≤ 10 μM) range both on the OV90 parental cell line and on its sorted EpCAMlosubpopulation. RTqPCR and western analysis showed that these two compounds do not affect Tpm1.6 / 7 or Tpm1.8 / 9 expression at either the RNA or protein level (Figure 5A-B). This is not unexpected since displacement of Tpm1.8 / 9 from actin filaments to the soluble pool in cells does not result in Tpm1.8 / 9 turnover. However, the expression of EMT-related genes was affected by both compounds: ZEB1 and VIM expression was suppressed, whereas, EpCAM was increased, also in agreement with the expected MET-inducing effects of Tpm1.8 / 9 antagonists (Figure 5A-B). Furthermore, the treated OV90 bulk and EpCAMlocells showed a 2-5-fold reduction of the cisplatin- and paclitaxel-specific IC50 values when compared with untreated cells (Figure 5C-D). Last, compounds 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) and 1- Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468) dramatically reduced Wnt / β-catenin signaling as shown by TopFLASH reporter assays. As expected, the Wnt- inhibiting effects of the compounds are more clearly illustrated by the EpCAMlocells because of their Wnt- and EMT-hi transcriptional profiles when compared with the parental OV90 cell line where a majority of EpCAMhi(Wnt-lo) and EpCAMlocells coexist. Overall, these in vitro results suggest the potential for the future development of novel therapeutic strategies for high-grade serous ovarian cancer centered around the Tpm1.8 / 9 isoforms. Discussion It is generally accepted that epithelial-mesenchymal plasticity (EMP), i.e. the transient and reversible identity conferred to cancer cells by EMT / MET processes, underlies tumor progression, local invasion, distant metastases, therapy resistance, and immune evasion. EMT is a highly variable process with a very broad spectrum of upstream signals from the TME, intracellular regulatory mechanisms, and downstream effectors, the identity of which largely depends on the tumor type and its micro- and macro-environment. The same is true when it comes to the nature of the epigenetic mechanisms that underlie EMP. It was recently shown that the differential expression of RNA-binding proteins between the epithelial tumor bulk and subpopulations of quasi- mesenchymal colon cancer cells underlies alterative splicing at a variety of target genes known to play functional roles in EMT, metastasis, and resistance to chemotherapy. Here, a similar strategy toward the identification and functional characterization of genes whose splicing is altered during EMT / MET in ovarian cancer was applied. Comparison of the genes alternatively spliced between epithelial and quasi- mesenchymal colon and ovarian cancer cells revealed a minority of common targets with a vast majority of ovarian-specific genes, possibly in reflection of the distinct modalities of local dissemination and metastatic colonization characteristic of these types of carcinoma. Whereas most colon cancer metastases follow a hematogenous route, unique for ovarian cancer is the ‘transcoelomic’ dissemination of tumor cells and the formation of ascites fluid in the abdominal and pelvic cavity which provide a favorable tumor microenvironment (TME) for the disseminated cancer cells. Nonetheless, previous studies have indicated that EMT does contribute to ovarian cancer progression and to chemotherapy resistance. Hence, even though through distinct cellular and molecular mechanisms, EMT does play a key role in ovarian cancer metastasis and chemo- resistance. Gene ontology analysis of the ovarian cancer specific AS targets revealed an extremely broad spectrum of biological processes, molecular functions, and cellular components likely to collectively contribute to the transition to quasi-mesenchymal ovarian cancer cells capable of local invasion and distant metastatic colonization. Previously, AS targets likely to contribute to ovarian cancer progression have been reported such as BCL2L12 and ECM1. Here, among the EMT-related AS targets, TPM1 was selected because of its function in the regulation of cell motility through cytoskeletal modifications, and its alleged role as a tumor suppressor and even oncogene in multiple cancer types. TPM1 alternative spliced isoforms are found in multiple tissues. The present results establish a direct causative relation between the Tpm1.8 / 9 isoforms, arising due to the differential expression of several RBPs between epithelial and quasi-mesenchymal ovarian cancer cells, and EMT activation through multiple signaling pathways including Wnt, TGF-β, Hedgehog, and Notch. Of note, the respective up- and down-regulation of the RBM24 and ESRP1 RNA-binding proteins earmark the epithelial-to-mesenchymal transitions in the ovarian cancer cell lines here examined. Because of their localization to the lamellipodia and functional role in cell motility, the Tpm1.8 / 9 isoforms are likely to facilitate dissemination from the primary tumor to the intra-abdominal cavity, as also shown by their enrichment in patient-derived ascites. Allegedly as a consequence of their EMT-inducing capacity, ectopic expression of the low- molecular weight TPM1 isoforms confers resistance to taxane- and platinum-based chemotherapy. Accordingly, Tpm1.8 / 9 are also found to be expressed at very low levels, if any, in primary ovarian cancers and their metastases albeit increased in malignant ascites. Notwithstanding the above, our attempts to provide in vivo evidence for the metastatic capacity of ovarian cancer cells overexpressing the Tpm1.8 / 9 isoforms failed to show any increase when compared with Tpm1.6 / 7. This apparently contradictory result can be explained by the transient and reversible nature of EMT along the multistep events that underlie dissemination and metastasis. While the acquisition of quasi-mesenchymal characteristics is required for local invasion and systemic dissemination, METs are equally essential for the colonization of distant organs. In the OV90 cells overexpressing the EMT-inducing Tpm1.8 / 9 isoforms, MET is inhibited thus negatively affecting their metastatic potential. The presence of tumor cells with a strongly compromised colony formation capacity in the malignant ascites from recipient mice transplanted IP with Tpm1.8 / 9-OE cells supports the hypothesis according to which MET suppression in these cells negatively affects their metastatic potential. Another indication of the potential off-target artifacts caused by the non-physiological expression levels of TPM1 isoforms in these cells became apparent in the analysis of their RNAseq profiles. While several inflammation pathways were upregulated together with Tpm1.8 / 9 in the EpCAMloovarian cancer cells when compared with their epithelial counterpart, ectopic Tpm1.6 / 7 expression resulted in the activation of similar inflammation-related pathways, e.g. IL6 / Jak / Stat3, IFN, and TNF, when compared with Tpm1.8 / 9 OE cells. Because of the apparent multifunctional role of TPM1 alternative splicing in ovarian cancer malignancy and resistance to therapy, Tpm1.8 / 9 form a relevant therapeutic target. As shown here, the development of small molecule inhibitors prevents EMT and reduce cell motility, and simultaneously inhibit the activation of key signal transduction pathways such as Wnt, known to play a central role in ovarian cancer stemness, EMT, and chemoresistance. Last, combined treatment with conventional taxane- and platinum-based chemotherapies may increase their therapeutic efficacy by antagonizing chemoresistance. Example 2 Materials and Methods Breast cancer MCF-7 cells growing in DMEM with 10 % FBS were washed in PBS, trypsinised for 3 minutes and resuspended in complete media. MCF-7 cells were counted and seeded at a density of 2x10E3 per well in a volume of 100 µL with complete media onto a 96 well plate. Cells were incubated for 24 hours prior to adding drug compounds. Paclitaxel was serially diluted from 50 nM to 0.39 nM final concentration in complete media. For the combination treatments Paclitaxel was also serially diluted from 50 nM to 0.39 nM final concentration in complete media with the addition of 189-3 compound (1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468)) at 5 µM or 10 µM constant. Serial dilutions of either the Paclitaxel alone or with the 189-3 compound were added in triplicate on the 96 well plate. After 72 hours incubation, a 20 µL volume of MTS reagent (Cell Titer 96 Aqueous One Solution Cell Proliferation Assay – Promega G3581) was added per well and the plate was incubated for a further 2 hours. The plates were read at 490 nm on a Fluostar Plate reader. Data was collected in Excel file format and the percentage of cell proliferation relative to the control for each treatment was calculated (Figure 6). The percentage of control versus treated cells was normalised to the media only control set at 100 % of the cell number. The average values for each experiment replicate were entered into GraphPad Prism 8 to generate the IC50 curves. Results Exposure of the MCF-7 breast cancer cell line to Paclitaxel resulted in a decrease in cell proliferation with an IC50 of 8.5nM Paclitaxel. Addition of 189-3 at 5uM and 10uM resulted in an increase in sensitivity of MCF-7 cells to Paclitaxel. The two doses of 189-3 were equally effective with 5uM and 10uM reducing the IC50 of Paclitaxel to 4.5nM and 4.7nM respectively (Figure 6 B). We conclude that Compound 189-3 increases the sensitivity of MCF-7 cells to Paclitaxel by 2-fold.

Claims

CLAIMS 1. A compound that is an inhibitor of Tropomyosin 1 alternative splicing isoforms Tpm1.8 and / or Tpm1.9, wherein the compound is selected from - a small molecule inhibitor selected from 3-(2-Methyl-indol-1-yl)-propylamine (PubChem CID 6494468) and 1-Phenylmethyl-1h-indole-2-methanol (PubChem CID 18973468), and pharmaceutically acceptable salts, hydrates, derivates, solvates or prodrugs thereof; - an antisense polynucleotide which decreases the expression of Tropomyosin 1 isoform 1.8 and / or 1.9 (Tpm1.8 or 1.9), and - an antibody which decreases Tpm1.8 and / or 1.9 polypeptide levels and / or Tpm1.8 or 1.9 polypeptide activity.

2. The compound according to claim 1, for use in a method of preventing and / or treating cancer.

3. The compound for use according to claim 2, wherein the cancer expresses TPM1 alternative splicing isoforms, preferably wherein the cancer expresses TPM1 alternative splicing isoforms of TPM1 Exon 1b, more preferably alternative splicing isoforms Tpm1.8 and / or Tpm1.

9.

4. The compound according to any one of the preceding claims, wherein the cancer is selected from acute myeloid leukemia (AML), adrenocortical carcinoma, bladder urothelial carcinoma, brain lower grade carcinoma, breast invasive carcinoma, cervical squamous cell carcinoma and endocervical adenocarcinoma, cholangiocarcinoma, colon adenocarcinoma, esophageal carcinoma, glioblastoma multiforme, head and neck squamous cell carcinoma, kidney chromophobe, kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, liver hepatocellular carcinoma, lung adenocarcinoma, lung squamous cell carcinoma, lymphoid neoplasm diffuse large B-cell lymphoma, mesothelioma, ovarian cancer in particular ovarian serous cancer, pancreatic adenocarcinoma, rectum adenocarcinoma, sarcoma, skin cutaneous melanoma, stomach adenocarcinoma, testicular germ cell tumors, thymoma, thyroid carcinoma, uterine carcinosarcoma, uterine corpus endometrial carcinoma, uveal melanoma, and combinations thereof.

5. The compound according to any one of the preceding claims, wherein the cancer is ovarian cancer, more preferably high-grade serous ovarian cancer.

6. The compound for use according to any one of claims 2-5, wherein the compound is administered in combination with an additional anti-cancer therapy, preferably selected from chemotherapy, targeted therapy such as immunotherapy, stem cell therapy, hormone therapy, radiation therapy and surgery, and combinations thereof, more preferably taxane- and / or platinum-based chemotherapy.

7. The compound for use according to any one of claims 2-6, wherein said use comprises the administration of said compound to a subject at a dose of between 0.1 and 100 mg / kg.

8. A pharmaceutical composition comprising the compound according to claim 1, preferably said composition further comprising a pharmaceutically acceptable carrier.

9. A method inhibiting, suppressing, preventing or treating proliferation, motility, invasiveness, dissemination, migration, metastasis or chemo-resistance of a cancer, comprising administering to a subject in need thereof a therapeutically effective amount of a compound according to claim 1 or a pharmaceutical composition according to claim 8.

10. The method according to claim 9, wherein the cancer expresses TPM1 alternative splicing isoforms, preferably wherein the cancer expresses TPM1 alternative splicing isoforms of TPM1 Exon 1b, more preferably alternative splicing isoforms Tpm1.8 and / or Tpm1.

9.

11. The method according to claim 9, wherein the cancer is selected from acute myeloid leukemia (AML), adrenocortical carcinoma, bladder urothelial carcinoma, brain lower grade carcinoma, breast invasive carcinoma, cervical squamous cell carcinoma and endocervical adenocarcinoma, cholangiocarcinoma, colon adenocarcinoma, esophageal carcinoma, glioblastoma multiforme, head and neck squamous cell carcinoma, kidney chromophobe, kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, liver heptacellular carcinoma, lung adenocarcinoma, lung squamous cell carcinoma, lymphoid neoplasm diffuse large B-cell lymphoma, mesothelioma, ovarian cancer inparticular ovarian serous cancer, pancreatic adenocarcinoma, rectum adenocarcinoma, sarcoma, skin cutaneous melanoma, stomach adenocarcinoma, testicular germ cell tumors, thymoma, thyroid carcinoma, uterine carcinosarcoma, uterine corpus endometrial carcinoma, uveal melanoma, and combinations thereof, preferably wherein the cancer is ovarian cancer, more preferably high-grade serous ovarian cancer.

12. The method of claim 10 or 11, wherein said therapeutically effective amount comprises a dose of between 0.1 and 100 mg / kg.

13. A method of identifying a compound targeting Tpm1.8 and / or Tpm1.9 isoforms for inhibiting, suppressing, preventing and / or treating proliferation, motility, invasion, migration, metastasis and / or chemo-resistance of a cancer, comprising: a) contacting a cancer cell that expresses Tpm1.8 and / or Tpm1.9 isoforms with a test compound, and b) measuring in said cancer cell the inhibition of Tpm1.8 and / or Tpm1.9 expression and / or activity, wherein the finding of an inhibitory effect identifies the test compound as a compound for use in a method of inhibiting, suppressing, preventing and / or treating cancer.

14. The compound of claim 1, for use in a method of inhibiting, suppressing, preventing or treating motility, invasiveness, dissemination, migration, metastasis or chemo-resistance of a cancer.

15. A method for determining the presence of epithelial-to-mesenchymal transition (EMT) in cancer cells, comprising determining Tpm1.8 and or Tpm1.9 expression in said cells, whereby an increased expression relative to a control expression indicates EMT in said cells.

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