Degradation agent targeting c-Myc protein, and preparation method and application of polypeptide drug coupled with nano-selenium

Abstract

The invention provides a c-Myc protein targeting degradation agent and a preparation method and application of a nano-selenium coupled polypeptide drug, and belongs to the technical field of biological medicines. The amino acid sequence of the degradation agent is shown as SEQ ID NO: 1, the binding constant of the degradation agent and c-Myc protein is 40.18 nM, and it is indicated that the degradation agent has high binding capacity with the c-Myc protein. The degradation agent or the polypeptide drug coupled with the nano-selenium is delivered into tumor cells, c-Myc protein can be effectively degraded, and the capability of remarkably inhibiting tumor growth and inducing tumor cell apoptosis is shown. Therefore, the preparation method of the degradation agent or the polypeptide drug coupled with nano-selenium can be applied to preparation of drugs for preventing and / or treating c-Myc protein disorder related diseases such as tumors or preparation of reagents for degrading c-Myc protein, and has very wide application value and patent medicine prospect.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine technology, and in particular relates to a preparation method and application of a degradation agent targeting c-Myc protein and a polypeptide drug coupled with nano-selenium. Background Art

[0002] c-Myc is one of the important members of the Myc family. As a transcription factor, c-Myc is widely expressed in various cells and plays an important role in cell proliferation and differentiation, cell cycle, metabolism and apoptosis. It is a key protein that regulates cell fate. A large number of studies have shown that c-Myc is highly expressed in a variety of tumors, including prostate cancer, breast cancer, lymphoma, leukemia, etc. c-Myc can induce rapid proliferation of tumor cells, inhibit cell differentiation and apoptosis, and thus promote tumor development. In addition to tumors, dysregulated expression of c-Myc is also closely related to the occurrence and development of other diseases such as diabetes and atherosclerosis. c-Myc protein has become one of the most attractive potential therapeutic targets for a variety of diseases. In recent years, researchers have tried to directly or indirectly inhibit the function of c-Myc at multiple levels. There are currently two new strategies for targeting c-Myc for treatment: targeting c-Myc protein expression or targeting c-Myc / Max interaction. However, these strategies have limitations, including off-target effects and the development of drug resistance. Because the important functional domains of c-Myc are inherently disordered and lack enzyme active sites, it is difficult to design drugs based on their structure. In addition, the high affinity and interaction between c-Myc and its obligate partner MAX, as well as its nuclear localization, pose a persistent obstacle to the design of effective c-Myc inhibitors. Therefore, the development of degraders that can specifically degrade c-Myc protein has very broad application value and drug development prospects. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a degradation agent targeting c-Myc protein, a preparation method and application of a polypeptide drug coupled with nano-selenium. The degradation agent has a high binding ability with c-Myc protein and can efficiently target and degrade c-Myc, and can be used to prepare drugs for preventing and treating diseases related to c-Myc protein disorder such as tumors.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a degradation agent targeting c-Myc protein, wherein the amino acid sequence of the degradation agent is shown as SEQ ID NO: 1.

[0006] Preferably, the binding constant between the degradation agent and the c-Myc protein is 40.18 nM.

[0007] The present invention also provides a drug for preventing and treating cancer, which comprises a drug carrier and the above-mentioned degradation agent.

[0008] Preferably, the drug carrier comprises one of nanogold, liposome or nanoselenium.

[0009] The present invention also provides a method for preparing a nano-selenium-coupled polypeptide drug, comprising the following steps:

[0010] After mixing the above-mentioned degradation agent targeting degradation of c-Myc with water, chitosan, sodium selenite and vitamin C are added to carry out heating reaction. After the reaction is completed, the residual reagents are removed by dialysis to obtain a nano-selenium-coupled polypeptide drug.

[0011] Preferably, the mass volume ratio of the polypeptide targeting degradation of c-Myc to water is 1 mg: 0.5-2 mL; the concentration of the chitosan is 4%-6%; the molar concentration of the sodium selenite is 45-55 mM; the molar concentration of the vitamin C is 45-55 mM; the volume ratio of the chitosan, sodium selenite, vitamin C and water is (0.5-0.7): (0.1-0.3): (1.5-2): (0.5-1.5).

[0012] Preferably, the temperature of the heating reaction is 45 to 55° C.; the time of the heating reaction is 15 to 25 minutes.

[0013] The present invention also provides an application of the above-mentioned degradation agent, medicine or preparation method in preparing a product for degrading c-Myc protein.

[0014] The present invention also provides an application of the above-mentioned degradation agent, medicine or preparation method in the preparation of medicine for preventing and treating cancer.

[0015] Preferably, the cancer comprises prostate cancer.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a method for preparing a degradation agent targeting c-Myc protein and a polypeptide drug coupled with nano-selenium, and the application thereof. The binding constant between the degradation agent and the c-Myc protein is 40.18 nM, indicating that the degradation agent has a strong binding ability with the c-Myc protein. The degradation agent or the polypeptide drug coupled with nano-selenium is delivered to tumor cells, which can effectively degrade the c-Myc protein and show the ability to significantly inhibit tumor growth and induce tumor cell apoptosis. It can be seen that the preparation method of the degradation agent or the polypeptide drug coupled with nano-selenium can be applied to the preparation of drugs for preventing and / or treating diseases related to c-Myc protein disorder such as tumors or the preparation of reagents for degrading c-Myc protein, and has a very wide range of application value and drug development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The identification result of the polypeptide targeting c-Myc provided by the present invention, wherein A is the spatial structure of the polypeptide; B is the detection of the binding ability of the polypeptide to c-Myc;

[0019] Figure 2 Characterization and evaluation of MYC-LYSO, wherein A is a transmission electron microscopy image of MYC-LYSO, B is the hydrodynamic diameter distribution of MYC-LYSO, and C is the surface Zeta potential of MYC-LYSO;

[0020] Figure 3 For the evaluation of MYC-LYSO cellular uptake capacity, confocal micrographs of DU145 cells cultured with 100 nM MYC-LYSO labeled with FITC (green) at 0 and 12 h, in which the cell nuclei were stained with Hoechst 33342 (blue);

[0021] Figure 4 Figure 1 is the result of in vitro inhibition of prostate cancer cell proliferation activity by MYC-LYSO at different concentrations, where A is the result of detecting the ability of MYC-LYSO to inhibit DU-145 cell proliferation, B is the result of detecting the ability of MYC-LYSO to inhibit C4-2 cell proliferation, C is the result of detecting the ability of MYC-LYSO to inhibit CWR22Rv1 cell proliferation, and D to F are the results of Western blotting to detect the degradation of c-Myc protein in DU-145, C4-2 and CWR22Rv1 cells by MYC-LYSO and the half-maximal degradation concentration (DC 50 ).

[0022] Figure 5 The results of the in vitro apoptosis detection of prostate cancer cells induced by MYC-LYSO drugs, A is the in vitro apoptosis detection result of DU-145 cells induced by MYC-LYSO drugs, B is the in vitro apoptosis detection result of CWR22Rv1 cells induced by MYC-LYSO drugs;

[0023] Figure 6 Figure 1 is a statistical analysis of the results of the in vitro apoptosis detection of prostate cancer cells induced by MYC-LYSO drugs. Figure 2 is a statistical analysis of the in vitro apoptosis detection of DU-145 cells induced by MYC-LYSO drugs. Figure 3 is a statistical analysis of the in vitro apoptosis detection of CWR22Rv1 cells induced by MYC-LYSO drugs. Data are expressed as mean ± SD (n = 3). Statistical analysis was performed using t-test. **** P<0.0001. DETAILED DESCRIPTION

[0024] The present invention provides a degradation agent targeting c-Myc protein, wherein the amino acid sequence of the degradation agent is shown as SEQ ID NO: 1.

[0025] In the present invention, the degradation agent is a polypeptide, and the amino acid sequence is GMKLRRIELLGGSGGKFERQ. The binding constant of the degradation agent to the c-Myc protein is 40.18nM, and the binding ability of the degradation agent to the c-Myc protein is high. In an embodiment of the present invention, the polypeptide is synthesized using a polypeptide solid phase synthesis method. The present invention has no special restrictions on the polypeptide solid phase synthesis method, and a polypeptide synthesis method known in the art can be used, such as Fmoc polypeptide synthesis. Fmoc protected amino acids were purchased from Jier Biochemical, and HBTU and HIBT condensing agents were from Suzhou Haofan Bio. The preparation method of the polypeptide of the present invention comprises:

[0026] (1) Deprotection: Fmoc-protected columns and monomers must be treated with an alkaline solvent (piperidine) to remove the amino protecting group.

[0027] (2) Activation and cross-linking: The carboxyl group of the next amino acid is activated by an activator. The activated monomer reacts with the free amino group to cross-link and form a peptide bond. In this step, a large amount of superconcentrated reagents is used to drive the reaction to completion. Cycle: These two steps are repeated until the synthesis is complete.

[0028] (3) Elution and deprotection: The polypeptide is eluted from the column and its protecting groups are eluted and deprotected by a deprotecting agent (TFA) to obtain a crude product.

[0029] The polypeptide targeted for degradation of c-Myc of the present invention has a strong ability to bind to c-Myc. The present invention has no special restrictions on the source of the polypeptide targeted for degradation of c-Myc, and the polypeptide source well known in the art can be used. In an embodiment of the present invention, the polypeptide is synthesized using a polypeptide solid phase synthesis method. The present invention has no special restrictions on the polypeptide solid phase synthesis method, and the polypeptide synthesis method well known in the art can be used, such as Fmoc polypeptide synthesis. Fmoc protected amino acids were purchased from Gill Biochemical, and benzotriazole-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU) and 1-hydroxybenzotriazole (HOBT) condensation agents were from Suzhou Haofan Biotechnology.

[0030] The present invention also provides a drug for preventing and treating cancer, which comprises a drug carrier and the above-mentioned degradation agent.

[0031] In the present invention, the drug carrier comprises one of nano-gold, liposome or nano-selenium.

[0032] As a preferred embodiment, using nano-selenium as a delivery system, the present invention also provides a method for preparing a nano-selenium-coupled polypeptide drug, comprising the following steps:

[0033] After the above-mentioned polypeptide targeting degradation of c-Myc is mixed with water, chitosan, sodium selenite and vitamin C are added to carry out heating reaction. After the reaction is completed, the residual reagents are removed by dialysis to obtain a polypeptide drug coupled with nano-selenium.

[0034] In the present invention, the above-mentioned polypeptide targeting degradation of c-Myc is mixed with water. The mass volume ratio of the polypeptide targeting degradation of c-Myc to water is 1 mg: 0.5-2 mL, more preferably 1 mg: 0.6-1.5 mL, and more preferably 1 mg: 1 mL.

[0035] After the polypeptide targeting the degradation of c-Myc is mixed with water, chitosan, sodium selenite and vitamin C are added for heating reaction. The concentration of the chitosan is preferably 4% to 6%, more preferably 4.5% to 5.5%, and more preferably 5%, wherein the concentration of the chitosan is a mass volume percentage. Taking 5% chitosan as an example, the preparation method of the 5% chitosan is to weigh 0.5g chitosan and dissolve it in 10mL pure water. The molar concentration of the sodium selenite is preferably 45 to 55mM, more preferably 46 to 54mM, and more preferably 50mM; the molar concentration of the vitamin C is preferably 45 to 55mM, more preferably 47 to 53mM, and more preferably 50mM; the volume ratio of the chitosan, sodium selenite, vitamin C and water is preferably (0.5 to 0.7): (0.1 to 0.3): (1.5 to 2): (0.5 to 1.5), and more preferably 0.6: 0.2: 1.6: 1. The temperature of the heating reaction is preferably 45 to 55° C., more preferably 46 to 54° C., and more preferably 50° C.; the time of the heating reaction is preferably 15 to 25 min, more preferably 16 to 23 min, and more preferably 20 min.

[0036] After heating reaction, cooling to room temperature, the nano-selenium-coupled polypeptide is obtained.

[0037] The nano-selenium-coupled polypeptide prepared by the preparation method is GMKLRRIELLGGSGGKFERQ (SEQ ID NO: 1), with a particle size of 41.68±5.6nm and a Zeta potential of 25.3±6.3mv. The nano-selenium-coupled polypeptide drug is experimentally confirmed to be non-toxic at the cellular level and has high safety.

[0038] In view of the function of the degrading agent to degrade intracellular c-Myc protein, the present invention also provides an application of the above-mentioned degrading agent, drug or preparation method in the preparation of a product for degrading c-Myc protein.

[0039] The present invention also provides an application of the above-mentioned degradation agent, medicine or preparation method in the preparation of medicine for preventing and treating cancer.

[0040] In the present invention, the cancer preferably includes prostate cancer. The cell types of the prostate cancer preferably include one or more of DU-145, C4-2 and CWR22RV1. The degrading agent is delivered to prostate cancer cells and is found to significantly inhibit cancer cell proliferation. The IC of the polypeptide drug on DU-145 cells is 50 The IC value for C4-2 cells is 140.1 nM. 50 The IC value for CWR22Rv1 cells is 222 nM. 50 The concentration of 552.7 nM is 552.7 nM. Therefore, the degradation agent or the polypeptide drug has a significant anti-cancer effect.

[0041] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0042] Description of experimental materials: In the following examples, Fmoc amino acids were purchased from Shanghai Jier Biochemical, DIEA (N,N-diisopropylethylamine), HOBT (1-hydroxybenzotriazole), and HBTU (O-benzotriazole-hexafluorophosphate) were purchased from Suzhou Haofan Biological. Chitosan, sodium selenite, and vitamin C were purchased from Sigma.

[0043] Glossary:

[0044] MYC-LYSO represents a c-Myc-targeted peptide drug coupled with nano-selenium;

[0045] Nano-Se represents the nanoselenium delivery system for unconjugated peptide drugs;

[0046] c-Myc represents the target protein c-Myc protein;

[0047] Vinculin represents vinculin and was used as a loading control in western blotting.

[0048] Example 1

[0049] The amino acid sequence of the degradation agent targeting c-Myc protein of the present invention is GMKLRRIELLGGSGGKFERQ (SEQ ID NO: 1).

[0050] The spatial structure of the polypeptide targeting c-Myc of the present invention is shown in Figure 1 A in.

[0051] The peptide targeting c-Myc labeled with rhodamine was co-incubated with c-Myc protein for 30 minutes, followed by fluorescence polarization detection. The specific steps are as follows: First, the peptide drug targeting c-Myc was labeled with rhodamine and added to a 384-well plate at a concentration of 10nM per well. Then, the P300 protein expressed and purified by E. coli was diluted to 10nM~10μM and co-incubated with the above-mentioned rhodamine-labeled peptide drug. After 30 minutes, the fluorescence polarization value was detected using a Tecan M1000 microplate reader.

[0052] The results are as follows Figure 1 In B, the binding constant between the peptide drug and c-Myc protein is 40.18 nM.

[0053] Example 2

[0054] The preparation method of the nano-selenium-coupled peptide (abbreviated as MYC-LYSO) drug is as follows:

[0055] 1 mg of the c-Myc-targeting polypeptide of Example 1 was dissolved in 1 mL of pure water, followed by the addition of 0.6 mL of 5% chitosan (5% chitosan was prepared by weighing 0.5 g of chitosan and dissolving it in 10 mL of pure water and mixing it), 0.2 mL of 50 mM sodium selenite and 1.6 mL of 50 mM vitamin C. The reaction was heated at 50° C. for 20 min and cooled to room temperature to obtain the nano-selenium-coupled polypeptide drug MYC-LYSO.

[0056] The morphology, Zeta potential and particle size of the peptide drug coupled with nano-selenium were determined by transmission electron microscopy (TEM), Zeta potential analyzer and DLS dynamic light scattering, respectively.

[0057] Depend on Figure 2 The results show that the nano-selenium-coupled polypeptide drug prepared by the present invention is spherical, with a particle size of 41.68±5.6nm and a Zeta potential of 25.3±6.3mv.

[0058] Example 3

[0059] Example 2 Cell level experiment of MYC-LYSO drug prepared

[0060] 1. Cell culture method: The culture conditions of prostate cancer cell lines DU-145, C4-2 and CWR22Rv1 were 1640 medium, 10% fetal bovine serum, 5% CO 2 The cells were cultured at 37°C with a saturated humidity of 100 μg / cm2 and a maximum cell density of 90% confluence.

[0061] 2. MYC-LYSO drug uptake experiment

[0062] Before analyzing the uptake of MYC-LYSO using confocal microscopy, MYC-LYSO was initially labeled with fluorescein FITC. This labeling process involves the reaction of FITC esterified with NHS with the amino group of the peptide drug. In order to perform drug uptake experiments, 2×10 5 DU-145 cells were seeded into glass-bottomed culture dishes. After 24 hours of culture, 100 nM MYC-LYSO drug was added or not added to the culture dishes for further incubation for 12 hours. After collecting the samples, the cells were washed twice with PBS, then fixed with 4% paraformaldehyde for 15 minutes, and then stained with Hoechst 33342. Observation and photography were performed under a NiKon A1R-si confocal microscope. All images were obtained with the same excitation wavelength and detector gain setting (scale bar: 100 μm).

[0063] Figure 3 The results showed that after 12 hours, most of the MYC-LYSO drug had been successfully taken up by DU-145 cells and entered the cell nucleus.

[0064] 3. Experiment on the ability of MYC-LYSO drugs to inhibit cancer cell proliferation

[0065] The Cell Counting Kit-8 detection method is used to analyze the ability of drugs to inhibit the proliferation of cancer cells.

[0066] Cell Counting Kit-8, referred to as CCK-8 kit, is a rapid and highly sensitive detection kit based on WST-8 that is widely used for cell proliferation and cytotoxicity. WST-8 is a compound similar to MTT. In the presence of an electron coupling agent, it can be reduced by some dehydrogenases in mitochondria to generate an orange-yellow compound. The more and faster the cell proliferation, the darker the color; the greater the cytotoxicity, the lighter the color. For the same cells, the depth of the color is linearly related to the number of cells.

[0067] In the experiment of detecting cell activity, DU-145, C4-2 and CWR22Rv1 cells were cultured at 5×10 4cells / mL, and seeded into 96-well plates treated with TC (Tissue Culture treated), and 100 μL of cell solution was added to each well. After 24 hours of cell adhesion culture, different concentrations of MYC-LYSO drugs (0, 16, 31.25, 62.5, 125, 250, 500, 1000 nM) were added to the cells as the drug-adding group, and naked selenium nanoparticles (Nano Se) with the same concentration gradient as the drug-adding group were set as the component control (the identity of the drug-adding group was substituted into the formula during calculation), and a complete control group (only cells and culture medium, no other components were added), a blank group (only culture medium without cells) and a background group (only culture medium without cells, with corresponding concentrations of MYC-LYSO or naked selenium nanoparticles) were set at the same time. After 48 hours of treatment, 10 μL of CCK8 reagent was added to each well and incubated in a 37°C incubator for 2 hours. After color development is completed, use a spectrophotometer to measure the absorbance of each well at 450nm and 690nm. After measurement, calibrate the absorbance of each well according to formula I. Finally, calculate cell viability according to formula II.

[0068] A=OD 450 -OD 690 Formula I

[0069] Cell viability (%) = [A (drug addition) - A (background)] / [A (complete control) - A (blank)] × 100% Formula II

[0070] After treatment with MYC-LYSO drugs, the detection and calculation obtained represent the inhibitory proliferation effect of MYC-LYSO drugs on prostate cancer cells.

[0071] Results Figure 4 A, B, and C in Figure 1 show that compared with naked selenium nanoparticles, MYC-LYSO showed a dose-dependent growth inhibitory effect in DU-145, C4-2, and CWR22RV1 cells. However, naked selenium nanoparticles (Nano Se) had no effect on cell viability. The half-maximal inhibitory concentration (IC 50 ) values ​​were 140.1nM, 222nM and 552.7nM respectively.

[0072] 4. In order to study the degradation ability of MYC-LYSO drug on c-Myc, immunoblotting (WB) experiment analysis was performed. The specific experimental process is as follows:

[0073] (1) DU-145, C4-2, and CWR22Rv1 cells were cultured at 3×10 5The cells were seeded at a density of cells / mL in a 6-well plate treated with TC (Tissue Culture treated), and 2 mL of cell solution was added to each well. After the cells were cultured for 24 hours, different concentrations of MYC-LYSO drugs (0nM, 250nM, 500nM, 1000nM, 2000nM, 4000nM) were added to the 6-well plate for treatment. After 24 hours of treatment, the culture medium was aspirated and washed once with PBS. 100 μL of RIPA lysis buffer containing protease inhibitors was added to each well to scrape and collect the cell lysate for protein extraction.

[0074] (2) The total protein content in each group of samples was quantified using a BCA quantitative kit, and the protein concentration in each group of samples was made consistent by adjusting the sample volume. After the protein concentration was adjusted, a corresponding volume of protein loading buffer was added and placed in a 100°C metal bath for 10 minutes to completely denature the protein.

[0075] (3) Separate the samples of different groups by SDS-PAGE. Prepare 10% polyacrylamide separation gel containing SDS and 5% polyacrylamide concentration gel. Then add the prepared samples and the same volume of pre-stained protein samples into the loading wells for electrophoresis separation experiment. The electrophoresis conditions are: the voltage is set to 80V, and the separation is about 30min until bromophenol blue reaches the separation gel. Then adjust the voltage to 120V, separate for about 60min until bromophenol blue reaches about 1cm from the end of the separation gel, and stop the electrophoresis.

[0076] (4) Transfer the protein sample to a membrane. All Western Blot experiments in the present invention use PVDF membranes, which are arranged in the following order on a membrane transfer apparatus: three layers of filter paper, glue, PVDF membrane, and three layers of filter paper. The transfer current is set to 350 mA, and the transfer time is 2 h.

[0077] (5) Blocking: The transferred PVDF membrane was immersed in a blocking solution containing 5% BSA and incubated at room temperature for 1 hour to remove the influence of non-specific adsorption.

[0078] (6) Primary antibody incubation. Prepare different antibody dilutions as required, and then incubate at 4 degrees overnight to achieve the purpose of antibody recognition of specific antigens.

[0079] (7) Secondary antibody incubation. Prepare species-specific HRP-labeled secondary antibodies (anti-mouse or anti-rabbit) according to the source species of the primary antibody and dilute them at 1:2000. Then incubate at room temperature for 1 h.

[0080] (8) Color development. Prepare color development solution, soak the PVDF membrane that has been fully incubated with the secondary antibody, and use a chemiluminescence analyzer for color development analysis.

[0081] Figure 4 The results of D to F in the figure show that MYC-LYSO degrades c-Myc protein in a dose-dependent manner. The half-maximal degradation concentration of MYC-LYSO on c-Myc protein in DU-145, C4-2, and CWR22Rv1 cells is DC 50 They are 441nM, 663.6nM and 557.4nM respectively.

[0082] 5.MYC-LYSO drug induces tumor cell apoptosis in vitro

[0083] The ability of MYC-LYSO to promote apoptosis of prostate cancer cells was evaluated by flow cytometry using the FITC-Annexin V / PI detection kit (Biolegend). DU-145 and CWR22Rv1 cells were cultured at 3 × 10 5 The cells were inoculated into 6-well plates at a density of 10 cells / mL. After 24 hours of cell attachment culture, different concentrations (0.5μM, 1μM) of MYC-LYSO were added for treatment, and the negative control was set to add 1μM naked selenium nanoparticles (Nano-Se). The blank group (Control) was set to add only cell culture medium to the cells. After 24 hours of culture, the cells were collected and analyzed by flow cytometry, and each group was tested three times in parallel.

[0084] Figure 5 The results in A and B showed that MYC-LYSO drug induced apoptosis of DU-145 and CWR22Rv1 cells in a dose-dependent manner.

[0085] Figure 6 The results showed that 0.5μM MYC-LYSO could directly induce significant apoptosis in prostate cancer cells, 1μM MYC-LYSO could cause about 70% DU-145 and 40% CWR22Rv1 cell apoptosis, while the same concentration of Nano-Se treatment would not cause cell apoptosis.

[0086] Combined with the above experimental results, it is shown that MYC-LYSO can effectively degrade c-myc protein in prostate cancer cells and kill prostate cancer cells by inducing cell apoptosis.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A degradation agent targeting c-Myc protein, characterized in that: The amino acid sequence of the degradation agent is shown in SEQ ID NO:

1.

2. The degradation agent according to claim 1, characterized in that The binding constant between the degradation agent and the c-Myc protein is 40.18 nM.

3. A drug for preventing and treating tumors, characterized in that: The drug comprises a drug carrier and the degradation agent according to claim 1 or 2.

4. The drug according to claim 3, characterized in that The drug carrier comprises one of nano-gold, liposome and nano-selenium.

5. A method for preparing a polypeptide drug coupled with nano-selenium, characterized in that: The following steps are involved: After mixing the c-Myc targeting degradation agent of claim 1 or 2 with water, chitosan, sodium selenite and vitamin C are added for heating reaction. After the reaction is completed, the residual reagents are removed by dialysis to obtain a nano-selenium-coupled polypeptide drug.

6. The preparation method according to claim 5, characterized in that: The mass volume ratio of the polypeptide for targeted degradation of c-Myc to water is 1 mg: 0.5-2 mL; the concentration of the chitosan is 4%-6%; the molar concentration of the sodium selenite is 45-55 mM; the molar concentration of the vitamin C is 45-55 mM; the volume ratio of the chitosan, sodium selenite, vitamin C and water is (0.5-0.7): (0.1-0.3): (1.5-2): (0.5-1.5).

7. The preparation method according to claim 5, characterized in that: The temperature of the heating reaction is 45-55° C.; the heating reaction time is 15-25 min.

8. Use of the degradation agent according to claim 1 or 2, the drug according to claim 3 or 4, or the preparation method according to any one of claims 5 to 7 in the preparation of a product for degrading c-Myc protein.

9. Use of the degradation agent according to claim 1 or 2, the drug according to claim 3 or 4, or the preparation method according to any one of claims 5 to 7 in the preparation of drugs for preventing and treating cancer.

10. The use according to claim 9, characterized in that: The cancer includes prostate cancer.

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