Polypeptides targeting fibroblast activation protein and uses thereof

Abstract

This invention belongs to the field of biomedical technology, specifically relating to peptides targeting fibroblast activation proteins and their applications. Specifically, the amino acid sequence of the peptides targeting fibroblast activation proteins described in this invention is shown in any one of SEQ ID No. 1 to SEQ ID No. 6. Experimental results demonstrate that the peptides targeting fibroblast activation proteins of this invention possess superior binding specificity and affinity, and exhibit good endocytosis activity against cells highly expressing FAP. They can serve as candidate targeting molecules for anti-tumor drugs, used for the treatment or diagnosis of cancers related to abnormal activation of fibroblast activation proteins.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology, specifically relating to polypeptides that target fibroblast activation proteins and their applications. Background Technology

[0002] Fibroblast activating protein (FAP, also known as fibroblast activating protein α, FAPα) is highly overexpressed in cancer-associated fibroblasts (CAFs) in solid tumors, but is generally not expressed in normal tissues and benign tumors. Tumor stromal CAFs can promote the growth and invasion of tumor cells and have become important targets for tumor intervention. Overexpression of the tumor biomarker FAP is a significant characteristic of CAFs, and FAP is a potential target for CAF targeting in tumor diagnosis and treatment.

[0003] FAP, a type II transmembrane serine protease belonging to the dipeptidyl peptidase 4 (DPP4) family, possesses both dipeptidyl peptidase (DPPs) and proline endopeptidase (PREPs) activities. Its role involves involvement in extracellular matrix (ECM) remodeling and fibrosis. CAF surface-specific FAP can promote tumor progression by enhancing tumor cell-mediated invasion along fibrous pathways through promoting matrix remodeling, participating in VEGF / AKT / ERK signal transduction pathways, and participating in tumor angiogenesis to form a tumor biobarrier and inhibit effector T cell function. The inducible high expression of FAP in the tumor stroma also depends on malignant transformation of the tumor tissue. High FAP expression is positively correlated with poor tumor prognosis. Therefore, FAP has become a marker of viable fibroblasts in tumors, granulation tissues, and fibrotic lesions.

[0004] Currently, the clinical success rate of FAP-targeted therapy is not high, but the overexpression of FAP in many diseases suggests it is a potential molecular diagnostic biomarker. Although FAP inhibitor molecules have poor direct inhibitory effects on tumors, some of them exhibit good specificity and affinity for FAP, and these molecules can be used as structural frameworks for novel drugs. Furthermore, peptide-based FAP-targeted inhibitors that have undergone structural modification and optimized screening have significant advantages and development value for cancer diagnosis and treatment. Summary of the Invention

[0005] The purpose of this invention is to provide a polypeptide that targets fibroblast activation protein and its application. This polypeptide targets and binds to the overexpressed fibroblast activation protein in tumor cells, and has important application value in tumor molecular diagnosis and targeted therapy.

[0006] To achieve the above objectives, the present invention provides, in one aspect, a polypeptide targeting a fibroblast activation protein or a pharmaceutically acceptable salt thereof, characterized in that the amino acid sequence of the polypeptide is one of the optional amino acid sequences shown in SEQ ID No. 1 to SEQ ID No. 6, GCFRQCQTAWPAWDCFHHCG (SEQ ID No. 1),

[0007] GCVERCTTDFPQGAAACQAWCAG(SEQ ID No.2)、

[0008] GCHSLCVKYYQEAFCHSHCG(SEQ ID No.3)、

[0009] GCYRKCRANFNDLWCYKHCG(SEQ ID No.4)、

[0010] GCYRRCVTQYAAKWCLAHCG(SEQ ID No.5)、

[0011] GCYHSCSREWHPDTCRGWCG (SEQ ID No. 6).

[0012] In a second aspect, the present invention provides a polypeptide derivative, wherein the polypeptide derivative is a modified product of the polypeptide described in the first aspect or a variant obtained by adding and / or replacing one or more amino acids.

[0013] Preferably, the polypeptide derivative is a variant obtained by adding and / or replacing one, two, or three amino acids of any of the polypeptides shown in SEQ ID No. 1 to SEQ ID No. 6.

[0014] More preferably, the polypeptide derivative is a variant of the polypeptide shown in SEQ ID No. 1, SEQ ID No. 2, SEQ ID No. 3 or SEQ ID No. 4 obtained by adding and / or replacing one amino acid.

[0015] Preferably, the polypeptide derivative is an N-terminal or C-terminal modified product of the polypeptide shown in SEQ ID No. 1, SEQ ID No. 2, SEQ ID No. 3 or SEQ ID No. 4, and the modifying group is selected from one or more of acetyl, amino, alkyl, aromatic, fatty acid, glycosyl, phosphate, sulfate, polyethylene glycol (PEG) group or peptide linking group.

[0016] More preferably, the modification is selected from: C-terminal amidation blocking and / or N-terminal modification with acetyl groups.

[0017] In another aspect, the present invention provides a polynucleotide that encodes any of the above-described FAP-targeting polypeptides or polypeptide derivatives.

[0018] In another aspect, the present invention provides a pharmaceutical formulation, characterized in that the pharmaceutical formulation comprises, as an active ingredient, the above-mentioned FAP-targeting polypeptide or its pharmaceutically acceptable salt or polypeptide derivative or polynucleotide and a drug carrier.

[0019] In another aspect, the present invention provides the use of the aforementioned FAP-targeting polypeptide or a pharmaceutically acceptable salt, polypeptide derivative, polynucleotide, or pharmaceutical preparation thereof in the preparation of a medicament for the prevention, diagnosis, and / or treatment of cancers associated with abnormal FAP activation.

[0020] Preferably, the cancer is selected from the group consisting of: prostate cancer, breast cancer, pancreatic cancer, liver cancer, lung cancer, sarcoma, colorectal cancer, cholangiocarcinoma, chordoma, small bowel cancer, pheochromocytoma, gastric cancer, kidney cancer, ovarian cancer, bladder cancer, esophageal cancer, head and neck cancer, thymic cancer, cervical cancer, endometrial cancer, neuroendocrine tumors, thyroid cancer, intestinal cancer, and solid tumors such as bone metastases. Further, the cancer is selected from pancreatic cancer, thyroid cancer, and liver cancer.

[0021] Beneficial effects:

[0022] 1. This invention develops a series of novel high-affinity peptides for fibroblast activation proteins, which can be used to target fibroblast activation proteins. Utilizing the high expression of the FAP receptor in tumors, these peptides can be used for the prevention, diagnosis, and / or treatment of FAP-overexpressing tumors.

[0023] 2. These peptides are all low molecular weight peptides, which are inexpensive to synthesize, and these peptides exhibit significant endocytosis in HEK293-FAP cells.

[0024] As used herein, “amino acid” refers to both natural and non-natural amino acids. The stereoconfiguration of an amino acid is indicated by a three-letter code containing the prefix “L-” or “D-” (except for achiral glycine). For example, L-type amino acids include: alanine (“L-Ala” or “A”), arginine (“L-Arg” or “R”), asparagine (“L-Asn” or “N”), aspartic acid (“L-Asp” or “D”), cysteine ​​(“L-Cys” or “C”), glutamine (“L-Gln” or “Q”), glutamic acid (“L-Glu” or “E”), glycine (“Gly” or “G”), histidine (“L-…”), and so on. L-Leucine (“His” or “H”), L-Ile (“L” or “I”), L-Leu (“L” or “L”), L-Lys (“L” or “K”), L-Met (“L” or “M”), L-Phe (“L” or “F”), L-Pro (“L” or “P”), L-Serine (“L” or “S”), L-Thr (“L” or “T”), L-Trp (“L” or “W”), L-Tyr (“L” or “Y”), and L-Val (“L” or “V”). L-leucine and L-valine can be represented as (NLeu) and (NVal), respectively. Nineteen naturally occurring chiral amino acids have corresponding D-isomers, identified by three-letter codes prefixed with "D-": alanine ("D-Ala" or "a"), arginine ("D-Arg" or "r"), asparagine ("D-Asn" or "a"), aspartic acid ("D-Asp" or "d"), cysteine ​​("D-Cys" or "c"), glutamine ("D-Gln" or "q"), glutamic acid ("D-Glu" or "e"), histidine ("D-His" or "h"), and isoleucine. The following amino acids are listed: leucine (“D-Ile” or “i”), lysine (“D-Lys” or “k”), methionine (“D-Met” or “m”), phenylalanine (“D-Phe” or “f”), proline (“D-Pro” or “p”), serine (“D-Ser” or “s”), threonine (“D-Thr” or “t”), tryptophan (“D-Trp” or “w”), tyrosine (“D-Tyr” or “y”), and valine (“D-Val” or “v”).

[0025] "Non-natural amino acids" refers to any derivative of natural amino acids, including α- and β-amino acid derivatives. It should be noted that some amino acids classified as non-natural amino acids in this invention (e.g., hydroxyproline) may also exist in certain biological tissues or specific proteins in nature. Amino acids with many different protecting groups suitable for direct application in solid-phase peptide synthesis are readily available. In addition to the twenty most common natural amino acids, the following exemplary non-natural amino acids and amino acid derivatives (common abbreviations in parentheses) may be used according to this invention: 2-aminohexanoic acid (Aad), 3-aminohexanoic acid (β-Aad), 2-aminobutyric acid (2-Abu), α,β-dehydro-2-aminobutyric acid (8-AU), 1-aminocyclopropane-1-carboxylic acid (ACPC), aminoisobutyric acid (Aib), 3-aminoisobutyric acid (β-Aib), 2-amino-thiazoline-4- Carboxylic acids, 5-aminovaleric acid (5-Ava), 6-aminohexanoic acid (6-Ahx), 2-aminoheptanoic acid (Ahe), 8-aminooctanoic acid (8-Aoc), 11-aminoundecanoic acid (11-Aun), 12-aminododecanoic acid (12-Ado), 2-aminobenzoic acid (2-Abz), 3-aminobenzoic acid (3-Abz), 4-aminobenzoic acid (4-Abz), 4-amino-3-hydroxy-6-methylheptanoic acid (sta), aminooxyacetic acid (Aoa), 2-aminotetrahydronaphthalene-2-carboxylic acid (ATC), 4-amino-5-cyclohexyl-3-hydroxyvalerate (ACHPA), p-aminophenylalanine (4-NH2-Phe), 2-aminopimelic acid (Apm), biphenylalanine (Bip), p-bromophenylalanine (4-Br-Phe), o-chlorophenylalanine (2-Cl-Phe), m-chlorophenylalanine (3-Cl-Phe), p-chlorophenylalanine (4-Cl-Phe), m-chlorotyrosine (3-C l-Tyr), p-benzoylphenylalanine (Bpa), tert-butylglycine (TLG), cyclohexylalanine (Cha), cyclohexylglycine (Chg), desmodium (Des), 2,2-diaminopimelic acid (Dpm), 2,3-diaminopropionic acid (Dpr), 2,4-diaminobutyric acid (Dbu), 3,4-dichlorophenylalanine (3,4-Cl2-Phe), 3,4-difluorophenylalanine (3,4-F2-Phe), 3,5-diiodotyrosine (3,5-I2-Tyr), N-ethylglycine (EtGly), N-ethylasparagine (EtAsn), o-fluorophenylalanine (2-F-Phe), m-fluorophenylalanine (3-F-Phe), p-fluorophenylalanine (4-F-Phe), m-fluorotyrosine (3-F-Tyr), homoserine (Hse), homophenylalanine (Hfe), homotyrosine (Htyr), hydroxylysine (Hyl) Isohydroxylysine (aHyl), 5-hydroxytryptophan (5-OH-Trp), 3- or 4-hydroxyproline (3- or 4-Hyp), p-iodophenylalanine (4-I-Phe), 3-iodotyrosine (3-I-Tyr), dihydroindole-2-carboxylic acid (Idc), iso-iduxin (Ide), isoleucine (α-Ile), isoperidinic acid (Inp), N-methylisoleucine (Melle), N-Methyllysine (MeLys), m-methyltyrosine (3-Me-Tyr), N-methylvaline (MeVal), 1-naphthylalanine (1-Nal), 2-naphthylalanine (2-Nal), p-nitrophenylalanine (4-NO2-Phe), 3-nitrotyrosine (3-NO2-Tyr), leucine (Nle), valine (Nva), ornithine (Orn), 1-phosphotyrosine (H2PO3-Tyr), octahydroindole-2-carboxylic acid (Oic), penicillamine (Pen), pentafluorophenylalanine (F5-Phe), phenylglycine (Phg), piperidine acid (Pip), propargylglycine (Pra), pyroglutamic acid (PGLU), sarcosine (Sar), tetrahydroisoquinoline-3-carboxylic acid (Tic), thienylalanine, and thiazolidin-4-carboxylic acid (thioproline, Th). ,

[0026] As used herein, the meaning of "peptide" or "polypeptide" is well known to those skilled in the art. Typically, a peptide or polypeptide is two or more amino acids linked by an amide bond, which is formed by the amino group of one amino acid and the carboxyl group of an adjacent amino acid. Polypeptides described herein may contain naturally occurring or non-naturally occurring amino acids. They can be modified into analogs, derivatives, functional mimics, pseudopeptides, and other compounds containing at least two amino acids.

[0027] As used herein, "pharmaceutically acceptable salt" or "medicinal salt" means a salt of the compounds described herein or a salt of a drug conjugate that is safe and effective when used in mammals. Non-limiting examples of pharmaceutically acceptable salts include: hydrochloride, hydrobromide, hydroiodide, sulfate, hydrogen sulfate, citrate, acetate, succinate, ascorbate, oxalate, nitrate, sorbate, hydrogen phosphate, dihydrogen phosphate, salicylate, hydrogen citrate, tartrate, maleate, fumarate, formate, benzoate, methanesulfonate, ethanesulfonate, benzenesulfonate, and p-toluenesulfonate. Attached Figure Description

[0028] Figure 1 This is a diagram of polypeptide endocytosis shown in SEQ ID No. 1;

[0029] Figure 2 This is a diagram of polypeptide endocytosis shown in SEQ ID No. 2;

[0030] Figure 3 This is a diagram of polypeptide endocytosis shown in SEQ ID No. 3;

[0031] Figure 4 This is a diagram of polypeptide endocytosis shown in SEQ ID No. 4;

[0032] Figure 5 This is a diagram of polypeptide endocytosis shown in SEQ ID No. 5;

[0033] Figure 6 This is a diagram of polypeptide endocytosis shown in SEQ ID No. 6. Specific Implementation

[0034] The present invention will now be described in further detail with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

[0035] The polypeptides of the present invention can be prepared using methods well known to those skilled in the art, including well-known chemical synthesis methods. The polypeptides can be expressed in organisms and purified using known purification techniques.

[0036] Example 1: Solid-phase synthesis of polypeptides

[0037] The present invention discloses a method for synthesizing linear precursors of polypeptide compounds and their derivatives using solid-phase synthesis, with intramolecular disulfide bonds formed by DMSO oxidation. The synthesis support is Fmoc-Gly-Wang Resin resin. During the synthesis process, the Fmoc-Gly-Wang Resin resin is first fully swollen in N,N-dimethylformamide (DMF). Then, the solid support is repeatedly subjected to condensation → washing → deprotection of Fmoc → washing → the next round of amino acid condensation to achieve the desired polypeptide chain length. Finally, the polypeptide is cleaved from the solid support by reacting the resin with a mixed solution of trifluoroacetic acid:water:triisopropylsilane:aniline sulfide (90:2.5:2.5:5, v:v:v:v). After precipitation with frozen methyl tert-butyl ether, a solid crude linear precursor is obtained. The cleaved crude linear precursor is then subjected to disulfide bond oxidation in a weakly alkaline solution to obtain the target crude polypeptide. The crude polypeptide was purified and separated by a C-18 reversed-phase preparative chromatography column in a system of 0.1% trifluoroacetic acid in acetonitrile / water to obtain pure polypeptides and their derivatives.

[0038] Experimental reagents

[0039]

[0040]

[0041] (1) Solid-phase synthesis of the polypeptide shown in SEQ ID No. 1

[0042] SEQ ID No.1: GCFRQCQTAWPAWDCFHHCG

[0043] Step 1: Couple the first amino acid Fmoc-Gly-OH

[0044] 0.2 mmol of 2-Chlorotrityl chloride resin was fully swollen in DCM for 1 h. Fmoc-Gly-OH (0.16 mmol) and diisopropylethylamine (DIEA, 0.64 mmol) were dissolved in 8 mL of DCM and added to the resin. The reaction was carried out at room temperature for 2 h. After the reaction was complete, blocking buffer (10 mL) of DCM:methanol:DIEA (85:10:5, v:v:v) was added, and the mixture was blocked at room temperature for 10 min. The blocked resin was then washed 5 times with DCM and 5 times with DMF.

[0045] Step 2: Synthesis of linear peptide chains

[0046] The resin obtained in step 1 was fully swollen in DMF for 1 hour. Then, the linear precursor was synthesized sequentially from the second amino acid at the carboxyl terminus to the amino terminus, following the given sequence. Each coupling cycle was performed as follows:

[0047] • Perform Fmoc-deprotection twice with 20% piperidine / DMF (20% v / v, 10 mL), 8 min each time.

[0048] Rinse the resin with DMF 6-8 times until neutral pH is reached.

[0049] • Dissolve 0.5 mmol of Fmoc-AA, 0.5 mmol of 6-chlorobenzotriazole-1,1,3,3-tetramethylurea hexafluorophosphate (HCTU), and 1 mmol of 4-methylmorpholine (NMM) in DMF, add to resin, and react at room temperature for 1 h.

[0050] Rinse the resin with DMF 4-6 times before coupling the next amino acid.

[0051] After synthesis of the linear peptides, the resin was washed five times with DMF and five times with DCM. The resin was then dried under vacuum.

[0052] Step 3: Cleavage of the linear precursor peptide chain

[0053] Add 10 mL of freshly prepared cut cocktail (trifluoroacetic acid:water:triisopropylsilane:aniline sulfide) (90:2.5:2.5:5, v:v:v:v) to the resin obtained in step 1, and react with shaking at room temperature for 2 hours. After the reaction is complete, filter the reaction solution, wash the resin with trifluoroacetic acid, combine the washings with the reaction solution, and precipitate with 4 times the volume of cold MTBE to obtain the crude product. Wash the crude product three times with MTBE and dry it under vacuum.

[0054] Step 4: Preparation of Peptides

[0055] After filtration through a 0.45 μm membrane, the product was separated using a reversed-phase high-performance liquid chromatography (RP-HPLC) system with buffers A (0.1 wt% trifluoroacetic acid, aqueous solution) and B (0.1 wt% trifluoroacetic acid, acetonitrile). The relevant fractions were collected, and after HPLC purity assessment, fractions with a purity >95% were combined, lyophilized, and the resulting pure peptide was obtained.

[0056] (2) Solid-phase synthesis of the polypeptide shown in SEQ ID No. 3

[0057] SEQ ID No.3: GCHSLCVKYYQEAFCHSHCG

[0058] Step 1: Couple the first amino acid Fmoc-Gly-OH

[0059] 0.2 mmol of 2-Chlorotrityl chloride resin was fully swollen in DCM for 1 h. Fmoc-Gly-OH (0.16 mmol) and diisopropylethylamine (DIEA, 0.64 mmol) were dissolved in 8 mL of DCM and added to the resin. The reaction was carried out at room temperature for 2 h. After the reaction was complete, blocking buffer (10 mL) of DCM:methanol:DIEA (85:10:5, v:v:v) was added, and the mixture was blocked at room temperature for 10 min. The blocked resin was then washed 5 times with DCM and 5 times with DMF.

[0060] Step 2: Synthesis of linear peptide chains

[0061] The resin obtained in step 1 was fully swollen in DMF for 1 hour. Then, the linear precursor was synthesized sequentially from the second amino acid at the carboxyl terminus to the amino terminus, following the given sequence. Each coupling cycle was performed as follows:

[0062] • Perform Fmoc-deprotection twice with 20% piperidine / DMF (20% v / v, 10 mL), 8 min each time.

[0063] Rinse the resin with DMF 6-8 times until neutral pH is reached.

[0064] • Dissolve 0.5 mmol Fmoc-AA, 0.5 mmol 6-chlorobenzotriazole-1,1,3,3-tetramethylurea hexafluorophosphate (HCTU) and 1 mmol 4-methylmorpholine (NMM) in DMF, add to resin and react at room temperature for 1 h.

[0065] Rinse the resin with DMF 4-6 times before coupling the next amino acid.

[0066] After synthesis of the linear peptides, the resin was washed five times with DMF and five times with DCM. The resin was then dried under vacuum.

[0067] Step 3: Cleavage of the linear precursor peptide chain

[0068] Add 10 mL of freshly prepared cut cocktail (trifluoroacetic acid:water:triisopropylsilane:aniline sulfide) (90:2.5:2.5:5, v:v:v:v) to the resin obtained in step 1, and react with shaking at room temperature for 2 hours. After the reaction is complete, filter the reaction solution, wash the resin with trifluoroacetic acid, combine the washings with the reaction solution, and precipitate with 4 times the volume of cold MTBE to obtain the crude product. Wash the crude product three times with MTBE and dry it under vacuum.

[0069] Step 4: Preparation of Peptides

[0070] After filtration through a 0.45 μm membrane, the product was separated using a reversed-phase high-performance liquid chromatography (RP-HPLC) system with buffers A (0.1 wt% trifluoroacetic acid, aqueous solution) and B (0.1 wt% trifluoroacetic acid, acetonitrile). The relevant fractions were collected, and after HPLC purity assessment, fractions with a purity >95% were combined, lyophilized, and the resulting pure peptide was obtained.

[0071] The other polypeptides of this invention can be prepared by referring to the Fmoc solid-phase synthesis method described above.

[0072] Example 2: Affinity of peptide sample to FAP protein

[0073] 1. Experimental materials:

[0074]

[0075] 2. Experimental steps:

[0076] The affinity of peptides for FAP was tested using a Biacore T200 microarray. Approximately 2000 RU of FAP protein was captured at 25°C using a ProteinA chip. A 1×HBS buffer at pH 7.4 was used as the running buffer. Binding experiments were performed at 25°C. The peptide analysis flow rate was 30 μL / min, with association for 120 s and dissociation for 600 s. Single-cycle or multi-concentration cycling (Kinetics / Affinity) was selected to detect the binding of peptide samples to proteins. Gly-HCl at pH 1.5 was used at a flow rate of 30 μL / min for 30 s for chip regeneration. Data were fitted using a 1:1 binding model.

[0077] 3. Experimental Results

[0078] Table 1. Affinity results of peptide samples and FAP protein

[0079]

[0080]

[0081] The results showed that the peptide described in this invention had an affinity for FAP protein at the nm level. Example 3: Cell endocytosis experiment.

[0082] Experimental materials:

[0083] Cells: Positive cells: HEK293-FAP; Negative cells: HEK293.

[0084] (1) Main reagents

[0085] FBS Excell FSP500 Puromycin Invivogen ant-pr-1 4% paraformaldehyde fixative Beyotime P0099 DAPI solution (10ug / ml, ready to use) Solarbio C0065 Streptavidin-Cy5 (SA-Cy5) ApexBio K1080 Streptomycin sulfate Aladdin S105491 Penicillin G Sodium Aladdin P105489)

[0086] (2) Main consumables

[0087] 96WellTC-TreatedBlackMicroplates Agilent 204626-100 RT

[0088] (3) Cell lines

[0089] HEK293 (negative cells) F12K+10% FBS HEK293-FAP (positive cells) F12K+10%FBS+1%P / S+4μg / mlpuromycin

[0090] Experimental steps:

[0091] 1. Prepare SA-Cy5 dilution solution: dilution ratio 1:50, dilution solution: cell growth medium.

[0092] 2. Sample preparation: Dilute directly from the stock solution to the required concentration (0.1-1 μM). Diluent: The SA-Cy5 diluent prepared in step 1 above. Premix at room temperature in the dark for 1 hour.

[0093] 3. Sample addition: Remove the culture medium from the well and replace it with the corresponding concentration of sample (0.1-1 μM). Incubate at 37°C for 2 hours.

[0094] 4. Fixation: Wash cells 3 times with DPBS, add 60 μL / well fixative, and incubate at 4°C in the dark for 30 min.

[0095] 5. Nuclear staining: Wash cells 3 times with DPBS, add 40-50 μL / well of DAPI staining solution, and incubate at 37°C in the dark for 20 min.

[0096] 6. Experimental results.

[0097] Experimental results are as follows Figures 1-5 As shown, the polypeptides of the present invention can enter HEK293 (HEK293-FAP) cells that highly express FAP through endocytosis. All polypeptides corresponding to the sequences have endocytosis at 0.3 μM.

[0098] In summary, the above results demonstrate that the polypeptide of the present invention has the targeting ability to target FAP, and at the same time has good penetration ability of cells expressing high levels of FAP, enabling high-sensitivity in vivo imaging of small tumors. Therefore, in practical applications, the polypeptide of the present invention can be used as a homing peptide, combined with anticancer drugs or imaging agents, for targeted therapy and imaging of tumors.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polypeptide or a pharmaceutically acceptable salt thereof that targets a fibroblast activation protein, characterized in that, The amino acid sequence of the polypeptide is shown below. GCFRQCQTAWPAWDCFHHCG (SEQ ID No. 1).

2. A polynucleotide, characterized in that, The polynucleotide encodes the polypeptide of claim 1.

3. A pharmaceutical preparation, characterized in that, The pharmaceutical preparation comprises, as an active ingredient, the polypeptide of claim 1 or a pharmaceutically acceptable salt thereof, or the polynucleotide of claim 2.

4. Use of the polypeptide of claim 1 or a pharmaceutically acceptable salt thereof, or the polynucleotide of claim 2, or the pharmaceutical formulation of claim 3, in the preparation of a medicament for the diagnosis and / or treatment of cancers associated with abnormal FAP activation; wherein the cancer is selected from at least one of pancreatic cancer, liver cancer, and thyroid cancer.

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