A siRNA for inhibiting MCM7, a composition thereof and its application

Abstract

This invention discloses an siRNA for inhibiting MCM7, a composition thereof, and its application. The siRNA designed and verified by this invention can efficiently inhibit MCM7 gene expression, thereby inhibiting DNA synthesis, cell proliferation, and cell clone generation in cancer cells, achieving the purpose of preventing and treating tumors. This invention provides a new target and candidate compound for cancer prevention or treatment.

Description

Technical Field

[0001] This invention belongs to the field of biomedicine, and specifically relates to an siRNA that inhibits MCM7, a composition thereof, and its application. Background Technology

[0002] The MCM complex, composed of MCM2–MCM7 subunits, possesses helicase activity within the cell, opening the DNA double helix before DNA replication and participating in DNA replication initiation (Bik Tye, Annual Review of Biochemistry, 1999). Furthermore, the MCM complex plays a crucial regulatory role in cell proliferation, DNA damage repair, and the cell cycle.

[0003] Small interfering RNA (siRNA) is a double-stranded RNA of 20–25 nucleotides in length. It was first discovered in post-transcriptional gene silencing in plants, and has been reported to silence specific genes in mammalian cells using artificially synthesized siRNA (Thomas Tuschl et al., Nature, 2001; Thomas Tuschl et al., Science, 2001; Thomas Tuschl et al., Cell, 2002). Because siRNA can target and interfere at the gene level without relying on the crystal structure of point proteins, scientists have investigated a series of methods using RNA interference (RNAi) to inhibit the expression of target genes, thereby enabling gene function research and gene therapy.

[0004] Because different sites on a target gene have different sequences, resulting in different secondary structures (binary outcomes) and different thermodynamic properties, the likelihood and extent to which siRNA can interfere with different sites can vary greatly. Furthermore, the activity of the same siRNA may differ in different cell types. Therefore, the design, testing, and acquisition of highly active siRNAs for any target gene in any cell is an exploratory and inventive process.

[0005] Currently, there are no reports on siRNAs of the MCM7 gene used to suppress cancer cells such as liver cancer, stomach cancer, and prostate cancer. Summary of the Invention

[0006] The primary objective of this invention is to provide a siRNA that inhibits MCM7.

[0007] Another object of the present invention is to provide applications of the above-mentioned siRNA.

[0008] Another object of the present invention is to provide a method for treating cancer by specifically targeting the MCM7 protein with siRNA.

[0009] The inventors designed and tested numerous RNA interference fragments targeting the MCM7 gene, but most siRNAs exhibited low interference efficiency, hindering their effectiveness in later-stage tumor treatment research. Through creative exploration and research, the inventors developed several highly efficient siRNA sequences for interfering with the MCM7 gene. This is crucial for the application of RNA interference, as the effectiveness of siRNAs at different sites on the target gene varies significantly, potentially due to factors such as the siRNA's secondary (metaneous) structure, thermodynamic properties, and base distribution.

[0010] The inventors initially designed interference fragments targeting the MCM7 gene, but the interference was low, which seriously affected subsequent gene and protein experiments and made it impossible to effectively conduct later tumor research. Therefore, they devoted themselves to finding effective siRNA sequences to interfere with the MCM7 gene. Moreover, this is crucial for the application of RNA interference, that is, the effect of siRNA at different sites of the target gene varies greatly, which may be related to factors such as the size of the free energy at both ends of the siRNA and the base distribution.

[0011] The inventors further discovered that by altering one or more bases of the sense strand of the siRNA, the sense and antisense strands form an incomplete complementary pair, thereby changing the thermodynamic properties of the entire double-stranded RNA, increasing the efficiency of the antisense strand entering the RNA interference complex protein, and thus improving the efficiency of siRNA-1 in inhibiting the target MCM7 gene.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] The inventors designed siRNA targeting the MCM7 protein. This siRNA inhibits the expression of the human MCM7 gene, thereby suppressing the synthesis of the MCM7 protein and disrupting the formation of the entire MCM complex (MCM2-MCM7). This inhibits DNA replication and cell proliferation, thus achieving the purpose of cancer prevention or treatment.

[0014] Inhibiting the expression of any subunit of the MCM complex by siRNA can suppress the formation of the complex, thereby inhibiting cell proliferation and producing an anti-tumor effect.

[0015] In one aspect, the present invention provides an siRNA that can inhibit MCM7 gene expression, comprising a sense strand and an antisense strand.

[0016] The siRNA is selected from:

[0017] siRNA-1: positive strand: 5'-GUGGAGAAUUGACCUUAGA-3';

[0018] Antonym chain: 5'-UCUAAGGUCAGUUCUCCAC-3';

[0019] It may have 80% or more, or better, 90% or more, homology with the sense or antisense strand sequence defined by the siRNA-1, or its bases may be modified to form a nucleic acid derivative and have the same function.

[0020] Furthermore, the 3' ends of the sense and antisense strands of the siRNA-1 need to have two deoxyribonucleotides, dT or dN, added in a single-stranded hanging structure.

[0021] Furthermore, the siRNA prevents or treats tumors / cancer by inhibiting the expression of the MCM7 gene.

[0022] Furthermore, the tumor / cancer is selected from liver cancer, stomach cancer, prostate cancer, breast cancer, lung cancer, pancreatic cancer, cervical cancer, endometrial cancer, colorectal cancer, lung cancer, nasopharyngeal carcinoma, ovarian cancer, skin cancer, esophageal cancer, or brain tumor.

[0023] Furthermore, the tumor may slow down or stop growing, shrink, or disappear due to the suppression of MCM7 gene expression.

[0024] Furthermore, the MCM7 gene is selected from the human MCM7 gene.

[0025] Furthermore, the siRNA sequence can be locally modified at certain sites, as long as it does not affect its binding to and inhibition of the target.

[0026] Furthermore, the siRNA sequence and its locally modified sequences can be modified to become nucleic acid derivatives, as long as it does not affect their binding to and inhibition of the target.

[0027] In another aspect of the invention, the use of siRNA in the preparation of drugs or compositions for the prevention or treatment of tumors / cancer is proposed.

[0028] Furthermore, the tumor / cancer is selected from liver cancer, stomach cancer, prostate cancer, breast cancer, lung cancer, pancreatic cancer, cervical cancer, endometrial cancer, colorectal cancer, lung cancer, nasopharyngeal carcinoma, ovarian cancer, skin cancer, esophageal cancer, or brain tumor.

[0029] Furthermore, the tumor / cancer may slow down or stop growing, shrink, or disappear due to the suppression of MCM7 gene expression.

[0030] Furthermore, the concentration of siRNA is 5–150 nM, preferably 10–100 nM, more preferably 15–60 nM, and most preferably 20–40 nM.

[0031] It may also have the following additional technical features:

[0032] The siRNA can inhibit MCM7 protein expression and consists of a sense strand and an antisense strand.

[0033] The siRNA is selected from:

[0034] siRNA-1: positive strand: 5'-GUGGAGAAUUGACCUUAGA-3';

[0035] Antonym chain: 5'-UCUAAGGUCAGUUCUCCAC-3';

[0036] It may have 80% or more, or better, 90% or more, homology with the sense or antisense strand sequence of the siRNA-1, or its bases may be modified to form a nucleic acid derivative and have the same function.

[0037] Furthermore, the siRNA needs to have two deoxyribonucleotides, dT or dN, added to its 3' end in a single-stranded suspension structure.

[0038] Furthermore, the MCM7 gene is selected from the human MCM7 gene.

[0039] Furthermore, siRNA can be locally modified at certain sites, as long as it does not affect its binding to and inhibition of the target.

[0040] Furthermore, the bases of siRNA sequences and their locally modified sequences can be modified to become nucleic acid derivatives, as long as it does not affect their binding to and inhibition of the target.

[0041] In another aspect of the invention, a medicament or composition for the prevention or treatment of tumors / cancer is provided, said medicament or composition comprising:

[0042] Any of the siRNAs described above;

[0043] Or an expression system that can express any of the siRNAs described above;

[0044] Furthermore, the tumor / cancer is selected from liver cancer, stomach cancer, prostate cancer, breast cancer, lung cancer, pancreatic cancer, cervical cancer, endometrial cancer, colorectal cancer, lung cancer, nasopharyngeal carcinoma, ovarian cancer, skin cancer, esophageal cancer, or brain tumor.

[0045] Furthermore, the tumor may slow down or stop growing, shrink, or disappear due to the inhibition of MCM7 gene expression.

[0046] Furthermore, the concentration of siRNA is 5–150 nM, preferably 10–100 nM, more preferably 15–60 nM, and most preferably 20–40 nM.

[0047] Furthermore, the above-mentioned drugs or compositions also include

[0048] Pharmaceutically acceptable carriers;

[0049] Other active ingredients for the prevention or treatment of tumors.

[0050] Furthermore, pharmaceutically acceptable carriers and / or excipients include, but are not limited to, buffers, emulsifiers, suspending agents, stabilizers, preservatives, saline, excipients, fillers, coagulants and blending agents, surfactants, dispersants, and defoamers.

[0051] Furthermore, other active ingredients for preventing or treating tumors include: chemotherapeutic agents, radiotherapy agents, or antibody drugs.

[0052] Furthermore, the form of the drug or composition is suitable for: direct naked RNA injection, liposome-encapsulated RNA direct injection, protein or peptide-encapsulated RNA direct injection, gold-coated RNA gene gun bombardment, bacterial plasmid-carrying RNA expression, or viral RNA expression.

[0053] Furthermore, the form of the siRNA drug or its composition is not particularly limited and can be selected from any form such as solid, liquid, gel, semi-liquid, or aerosol.

[0054] Furthermore, the MCM7 gene is selected from the human MCM7 gene.

[0055] siRNA can effectively inhibit the expression of the MCM7 gene and the synthesis of its protein, thereby achieving the purpose of treating tumors.

[0056] The beneficial effects of this invention are:

[0057] This invention modifies the 9th base from the 5' end of the siRNA-1 sense strand, causing the sense and antisense strands to form an incomplete complementary pair. This alters the thermodynamic properties of the entire double-stranded RNA, increasing the efficiency of the antisense strand entering the RNA interference complex protein, thereby improving the efficiency of siRNA-1 in inhibiting the target MCM7 gene.

[0058] This invention provides an siRNA targeting the MCM7 gene. Compared with conventional gene knockout technology, this invention is simple to operate and has a short experimental cycle. The siRNA has an inhibition effect of over 90% at both the mRNA and protein levels, with extremely high inhibition efficiency and good specificity. At the same time, it can effectively inhibit the DNA replication, proliferation, and clone formation ability of cancer cells. This is of great significance for the development of new anti-cancer gene drugs and the improvement of cancer treatment effects, and has significant clinical application prospects and economic value. Attached Figure Description

[0059] Figure 1 The silencing effect of MCM7-specific siRNA-1 on MCM7 mRNA levels in HepG2 and Hep3B liver cancer cells.

[0060] Figure 2 Figures A and B show the silencing effect of MCM7-specific siRNA-1 on the MCM7 protein level in HepG2 and Hep3B liver cancer cells, with β-actin serving as an internal reference protein.

[0061] Figure 3 This is a fluorescence micrograph of EdU-positive cells showing siRNA-1 inhibition of DNA replication in HepG2 liver cancer cells. Figure 3 A, C, and E are respectively overlay images of EdU-positive cells (NC cells) transfected with HepG2 liver cancer cells, and images of Hochst-stained nuclear DNA. Figure 3 B, D, and F are respectively superimposed images of EdU-positive cells, Hochst-stained nuclear DNA, EdU-positive cells, and Hochst-stained nuclear DNA after siRNA-1 transfection into HepG2 liver cancer cells.

[0062] Figure 4 A statistical chart showing the proportion of HepG2 cells that showed positive results after EdU incorporation.

[0063] Figure 5 A through E are growth curves showing the inhibition of HepG2 liver cancer cells, Hep3B liver cancer cells, SGC-7907 gastric cancer cells, PC3 prostate cancer cells, and MCF7 breast cancer cells by siRNA-1, respectively.

[0064] Figure 6 The results of siRNA-1 inhibiting the clonal generation of various cancer cells are shown in Figures A through E, which are the control figures for the number of cancer cell clones generated after transfecting HepG2 liver cancer cells, Hep3B liver cancer cells, SGC-7907 gastric cancer cells, PC3 prostate cancer cells, and MCF7 breast cancer cells with siRNA-1 or the negative control NC.

[0065] Figure 7 To demonstrate the ability of siRNA-1 to inhibit the clonal generation of various cancer cells, Figures A through E show the proportion of the total clonal area of ​​cancer cells to the total area of ​​the wells after transfecting HepG2 liver cancer cells, Hep3B liver cancer cells, SGC-7907 gastric cancer cells, PC3 prostate cancer cells, and MCF7 breast cancer cells with siRNA-1 or the negative control NC. Detailed Implementation

[0066] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments, but are not limited thereto.

[0067] Example 1: siRNA Design

[0068] Based on the fundamental principles of siRNA target sequences, a 21-nucleotide siRNA sequence (one strand) expressing the human MCM7 gene transcript (NM_001278595.1) was designed and synthesized. This sequence comprises the sense and antisense strands of the siRNA, and its base sequence is as follows:

[0069] siRNA-1 positive strand: 5'-GUGGAGAAUUGACCUUAGA dTdT-3' (SEQ ID NO.1),

[0070] siRNA-1 antisense strand: 5'-UCUAAGGUCAGUUCUCCAC dTdT-3' (SEQ ID NO.2).

[0071] The base sequence of the negative control RNA (NC) is as follows:

[0072] Chain of Justice: 5'-CUCUUAGCCAAUAUUCGCU dTdT-3'(SEQ ID NO.3);

[0073] Antonym: 5′-AGCGAAUAUUGGCUAAGAGdTdT-3′(SEQ ID NO.4).

[0074] The siRNA sequence and control RNA of this invention have two single-stranded suspended deoxyribonucleotides (dT or dN) added to the 3' ends of the sense and antisense strands to enhance the stability of the siRNA in vivo and in vitro and prevent it from being degraded by nucleases.

[0075] The siRNA sequence of this invention can be locally modified at certain sites, as long as it does not affect its binding to and inhibition of the target.

[0076] The siRNA sequence and its locally modified sequence of this invention can be modified to become nucleic acid derivatives, as long as it does not affect its binding and inhibition of the target.

[0077] Example 2: siRNA transfection in cells

[0078] Lipofectamine RNAiMax was used as the transfection reagent, and the procedure was performed according to the operating procedures of Thermo Fisher Scientific. The cell lines used were HepG2 and Hep3B liver cancer cells, SGC-7907 gastric cancer cells, PC3 prostate cancer cells, and MCF7 breast cancer cells.

[0079] Experimental methods not specified in this invention are generally performed under conventional conditions, such as those described in Sambrook et al., Molecular Cloning: A Laboratory Guide (New York: Cold Spring Harbor Laboratory Press, 1989), or as recommended by the manufacturer.

[0080] The transfection procedure was as follows: Different cancer cell lines were seeded into 12-well plates and cultured overnight at 37°C with 5% CO2 until the cell density reached 40-50%. Following the Lipofectamine RNAiMax (Thermo Fisher Scientific) protocol, the siRNA prepared in this invention and the negative control RNA (NC) were transfected into different cells. Cells were collected after transfection, and the interference effect of siRNA-1 was further detected using qRT-PCR and Western blotting.

[0081] Example 3: Detection of siRNA Inhibition of MCM7 mRNA Expression

[0082] Methods: Cells were collected after transfection, RNA was extracted, reverse transcribed, and real-time quantitative PCR was performed to detect the expression level of MCM7 mRNA in cancer cells after siRNA-1 treatment.

[0083] The siRNA-1 and negative control RNA (NC) prepared in this invention were transfected into the HepG2 liver cancer cell line, and the same method was used to transfect the Hep3B liver cancer cell line. Twenty-four hours after transfection, cells were collected, and an appropriate amount of cells were reseeded into 6-well plates. Total RNA was extracted from the cells after 72 hours. Reverse transcription was performed, and MCM7 mRNA was detected by real-time quantitative PCR.

[0084] 1. Total RNA extraction

[0085] (1) Collect tumor cells into centrifuge tubes, centrifuge at 800 rpm for 3 min, discard the supernatant, wash once with PBS and transfer to EP tubes;

[0086] (2) Centrifuge again at 800 rpm for 3 min, discard the supernatant, add 0.5 ml TRIzol, repeatedly pipette to dissolve the tumor cells, and let stand at room temperature for 5-10 min;

[0087] (3) Add 0.2 ml chloroform / ml TRIzol, shake vigorously to mix for 15 seconds, and let stand at room temperature for 10 minutes;

[0088] (4) Centrifuge at 12000 rpm and 4℃ for 15 min;

[0089] (5) After centrifugation, the liquid is divided into three layers, from bottom to top: phenol / chloroform layer, intermediate protein layer, and upper colorless aqueous phase. RNA is stored in the upper aqueous phase.

[0090] (6) Transfer the upper aqueous phase to a new EP tube, taking care to avoid aspirating the intermediate protein;

[0091] (7) Add 0.5 ml / ml of pre-cooled isopropanol TRIzol, mix by inversion, and let stand at room temperature for 10 min;

[0092] (8) Centrifuge at 12000 rpm and 4℃ for 10 min;

[0093] (9) Discard the supernatant and wash the RNA precipitate with 75% ethanol (750 μl anhydrous ethanol and 250 μl freshly prepared DEPC water). Centrifuge at 12,000 rpm and 4°C for 5 min.

[0094] (10) Discard the supernatant and dry it in a clean bench for about 3 minutes until the RNA becomes translucent.

[0095] (11) Add 15-20 μl of 1‰ DEPC water to dissolve the RNA precipitate, measure the concentration and OD value with a UV spectrophotometer, store at -70℃ or use directly for reverse transcription reaction.

[0096] 2. Reverse transcription into cDNA

[0097] Pre-deformed at high temperature for 5 minutes, then rapidly frozen on ice. Reverse transcription reaction system:

[0098]

[0099] Reaction conditions: 37℃ for 15 min, 50℃ for 5 min, 98℃ for 5 min, and then maintained at 4℃. The synthesized cDNA can be used immediately for downstream experiments or stored at -20℃.

[0100] 3. Real-time Quantitative PCR

[0101] After diluting the reverse-transcribed cDNA sample at an appropriate ratio, the following PCR reaction system was prepared using THUNDERBRID SYBR qPCR Mix:

[0102]

[0103] in:

[0104] The upstream primer sequence is 5'-GTGAAGGATCCTGCGACACA-3' (SEQ ID NO.5);

[0105] The downstream primer sequence is 5'-ACACGCGTTCTTTTGTTCCG-3' (SEQ ID NO.6);

[0106] The upstream primer sequence for the internal control is 5'-AGAAGAGCTACGAGCTGCCTGACG-3' (SEQ ID NO.7);

[0107] The downstream primer sequence for the internal control is 5'-GGACTCCATGCCCAGGAAGGAA-3' (SEQ ID NO.8).

[0108] result: Figure 1 A and B indicate that, compared to the control group NC, siRNA-1 transfection of cancer cells effectively inhibited the expression of MCM7 mRNA in HepG2 and Hep3B liver cancer cells, with a silencing effect of over 90%.

[0109] Example 4: Detection of siRNA inhibition of MCM7 protein expression

[0110] Methods: The siRNA-1 and negative control RNA (NC) prepared in this invention were transfected into the hepatocellular carcinoma cell line HepG2, and the same method was used to transfect the hepatocellular carcinoma cell line Hep3B. After 24 hours of transfection, the cells were collected, and an appropriate amount of cells were re-seeded into 12-well plates. After 72 hours, the cells were collected for Western blotting experiments.

[0111] 1. Remove the culture medium, add an appropriate amount of 2×laemmli buffer, gently shake the 12-well plate to lyse the cells, collect them into PE tubes, rub the DNA against the wells of the PE tube rack to break up the DNA, and boil at 95℃ for 2 minutes.

[0112] 2. The boiled and denatured samples were subjected to polyacrylamide gel electrophoresis and Western blotting, and then the PVDF membrane was blocked with 5% skim milk at room temperature for 0.5 hours.

[0113] 3. Select a suitable primary antibody (mouse anti-human MCM7 monoclonal antibody, Santa Cruz Biotechnology), dilute it appropriately, and incubate it with a PVDF membrane overnight at 4°C.

[0114] 4. The next day, wash with TBST 3 times, 10 minutes each time;

[0115] 5. Select an HRP-labeled anti-mouse IgG secondary antibody corresponding to the host species of the primary antibody, dilute it appropriately, and incubate it with a PVDF membrane at room temperature for 1 hour.

[0116] 6. Wash with TBST 3 times, 10 minutes each time;

[0117] 7. ECL solution was used for imaging to detect the expression of MCM7 protein in tumor cells.

[0118] result: Figure 2 Figures A and B show that, compared to the control group NC, siRNA-1 transfection of cancer cells can effectively inhibit the expression of MCM7 protein in HepG2 and Hep3B cells, with an inhibition rate of over 90%.

[0119] Example 5: siRNA inhibits DNA replication in cancer cells

[0120] Methods: The siRNA-1 and negative control RNA (NC) prepared in this invention were transfected into the HepG2 liver cancer cell line, and the same method was used to transfect the Hep3B liver cancer cell line. Twenty-four hours after transfection, cells were collected, and an appropriate amount of cells were reseeded into 96-well plates. Twelve hours later, mimosine reagent was added to the cells and incubated for 24 hours to synchronize the cells at the G1 and S phase boundary.

[0121] Cells were washed three times with fresh culture medium, each time with a three-minute interval, to release them from mimosine inhibition. Cells were cultured in fresh culture medium for 3.5 hours, followed by 0.5 hours of culture with 50 mmol / L EdU (5-Ethynyl-2'-deoxyuridine, a thymidine analog). Cells were fixed and stained, and the proportion of cells showing EdU incorporation was observed and counted under a fluorescence microscope.

[0122] result: Figure 3 and Figure 4 The results showed that after siRNA-1 transfection of cancer cells, the proportion of EdU incorporation into positive cells was significantly reduced compared with the negative control, indicating that siRNA-1 significantly inhibited DNA replication in cancer cells.

[0123] The fresh culture medium used was Gibco RPMI 1640.

[0124] Example 6: MCM7 siRNA inhibits cancer cell proliferation

[0125] Methods: The siRNA-1 and negative control RNA (NC) prepared in this invention were transfected into different cancer cell lines, and cells were collected 24 hours after transfection. An appropriate amount of cells was divided into five equal parts and re-seeded in 12-well plates. Cells were counted continuously for five days, with one well selected for cell counting each day. Cell growth curves after transfection were plotted.

[0126] Result: As Figure 5The results showed that siRNA-1 could effectively inhibit the proliferation of HepG2 liver cancer cells, Hep3B liver cancer cells, SGC-7907 gastric cancer cells, PC3 prostate cancer cells, and MCF7 breast cancer cells.

[0127] Example 7: MCM7 siRNA inhibits cancer cell clone generation

[0128] Methods: The siRNA-1 prepared in this invention and the negative control RNA (NC) were transfected into the different cancer cell lines described above, respectively. Cells were collected 24 hours after transfection. Cells were seeded into 6-well plates at a cell density of 0.4 × 10⁻⁶ cells / well. 3 Cells / well. After 14 days of culture, fix with methanol and stain with crystal violet.

[0129] Result: As Figure 6 and Figure 7 show, Figure 6 As shown in A to E, after siRNA-1 transfection of cancer cells, the number of cancer cell clones was significantly reduced compared with the negative control NC. Figure 7 As shown in A to E, after siRNA-1 transfected cancer cells, the proportion of the total clonal area to the total well area decreased compared with the negative control NC. This indicates that siRNA can effectively inhibit the clonal generation ability of HepG2 liver cancer cells, Hep3B liver cancer cells, SGC-7907 gastric cancer cells, PC3 prostate cancer cells, and MCF7 breast cancer cells.

[0130] Example 8: Application of MCM7 siRNA

[0131] The present invention relates to the application of MCM7 siRNA in the preparation of compounds for the prevention or treatment of tumors, wherein the tumors / cancers are selected from liver cancer, gastric cancer, prostate cancer, breast cancer, lung cancer, pancreatic cancer, cervical cancer, endometrial cancer, colorectal cancer, lung cancer, nasopharyngeal carcinoma, ovarian cancer, skin cancer, esophageal cancer, or brain tumors.

[0132] In summary, the siRNA of this invention effectively inhibits the expression of the MCM7 gene, thereby reducing the synthesis of the MCM7 protein. The inhibitory effect of siRNA is as high as 90% or more, with extremely high inhibition efficiency and good specificity. At the same time, it can effectively inhibit the DNA replication, proliferation and clone formation ability of cancer cells. It is of great significance for the development of new anti-cancer gene compounds and the improvement of cancer treatment effects, and has significant clinical application prospects and economic value.

[0133] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention. SEQUENCE LISTING <110> Enzhi (Guangzhou) Pharmaceutical Technology Co., Ltd. Enkang Pharmaceutical Technology (Guangzhou) Co., Ltd. Foshan Interpharm Technology Co., Ltd. and Guangzhou Intergene Technology Co., Ltd. <120> A siRNA for inhibiting MCM7, a composition thereof, and its application <130> <160> 8 <170> PatentIn version 3.5 <210> 1 <211> twenty one <212> DNA <213> Artificial primers <400> 1 guggagaauu gaccuuagat t 21 <210> 2 <211> twenty one <212> DNA <213> Artificial primers <400> 2 ucuaagguca guucuccact t 21 <210> 3 <211> twenty one <212> DNA <213> Artificial primers <400> 3 cucuuagcca auauucgcut t 21 <210> 4 <211> twenty one <212> DNA <213> Artificial primers <400> 4 agcgaauauu ggcuaagagt t 21 <210> 5 <211> 20 <212> DNA <213> Artificial primers <400> 5 gtgaaggatc ctgcgacaca 20 <210> 6 <211> 20 <212> DNA <213> Artificial primers <400> 6 acacgcgttc ttttgttccg 20 <210> 7 <211> twenty four <212> DNA <213> Artificial primers <400> 7 agaagagcta cgagctgcct gacg 24 <210> 8 <211> twenty two <212> DNA <213> Artificial primers <400> 8 ggactccatg cccaggaagg aa 22

Claims

1. A siRNA, characterized in that, The siRNA can inhibit the expression of MCM7 gene, and is composed of a sense strand and an antisense strand, The siRNA is: siRNA-1: sense strand: 5'-GUGGAGAAUUGACCUUAGA-3'; antisense strand: 5'-UCUAAGGUCAGUUCUCCAC-3'.

2. The siRNA of claim 1, wherein Two deoxyribonucleotides dT or dN in single-stranded overhanging structure are added to the 3' end of the siRNA-1 sense strand and antisense strand.

3. Use of the siRNA according to claim 1 or 2 in the preparation of a medicament for preventing or treating cancer, wherein the cancer is selected from liver cancer, gastric cancer, prostate cancer or breast cancer.

4. A medicament for preventing or treating cancer, characterized by comprising the compound or salt according to claim 1. The medicament comprises: the siRNA according to claim 1 or 2; or an expression system capable of expressing the siRNA according to claim 1 or 2.

5. The medicament according to claim 4, characterized in that, The cancer is selected from liver cancer, gastric cancer, prostate cancer or breast cancer.

6. The medicament according to claim 4, characterized in that, Further comprising: a pharmaceutically acceptable carrier; other active ingredients for preventing or treating tumors.

7. The medicament according to claim 6, characterized in that, The pharmaceutically acceptable carrier comprises buffers, emulsifiers, suspending agents, stabilizers, preservatives, physiological saline, excipients, fillers, coagulants and harmonizing agents, surfactants, diffusing agents, antifoaming agents.

8. The medicament according to claim 6, characterized in that, The other active ingredients for preventing or treating tumors comprise chemotherapeutic agents, radiotherapeutic agents or antibody drugs.

9. The medicament according to any one of claims 4 to 8, characterized in that, The medicament is selected from any of solid, liquid, gel, semi-liquid, aerosol forms.

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