Polypeptide inhibitor for treating triple negative breast cancer as well as preparation method and application of polypeptide inhibitor

The invention discloses a polypeptide inhibitor, and the sequence of the polypeptide inhibitor is D-W-Cyclo (isoD-AP-Dap)-E-E-W-G-N-W-V-D-E or Cyclo (isoD-RR-Dap)-D-W-N-A-P-E-E-W-G-N-W-V-D-E. The invention further discloses a preparation method of the polypeptide inhibitor. The invention also provides a preparation method of the polypeptide inhibitor and application of the polypeptide inhibitor in preparation of drugs for interfering MTDH/SND1 compound formation and treating triple negative breast cancer. According to the polypeptide inhibitor disclosed by the invention, a stable polypeptide ring closing method induced by terminal aspartic acid nucleation is introduced, so that a proper binding conformation can be maintained when the polypeptide is bound with a target spot. Experiments prove that the compound has good cell penetrability and serum stability, and shows good anti-tumor activity and extremely low non-specific cytotoxicity in triple negative breast cancer cells. 本发明公开了一种多肽抑制剂，其序列为：D-W-Cyclo(isoD-A