OSTP as a novel peptide specifically targeting human ovarian cancer

Ovarian cancer is a disease that seriously threatens the health of women and results in a high mortality rate. The present study aimed to investigate the novel peptide OSTP (peptide for specifically targeting ovarian cancer) to provide new methods for the effective diagnosis and treatment of ovarian cancer. The nude mouse ovarian cancer model was established. With the use of phage peptide display in vivo, a novel 7-amino peptide for specific binding to ovarian cancer was screened from the FliTrx bacterial peptide display system. OSTP was compounded and labeled with fluorescent pigment 5-FAM. The specificity and affinity of OSTP were tested in the ovarian cancer cell line A2780 in vitro. The tumor-targeting assays of OSTP were performed in vivo by injecting 5-FAM-OSTP into tumor-bearing mice. Clinical tissue specimens were tested by fluorescence staining following the addition of 5-FAM-OSTP. We found that the peptide specifically bound to ovarian cancer A2780 cells. Cell fluorescence staining showed that 5-FAM-OSTP obviously and specifically bound to ovarian cancer A2780 cells, particularly to the cell membrane. One hour after i.v. peptide injection, 5-FAM-OSTP specifically targeted the tumor tissues in the tumor-bearing mice. In the human pathological sections, 5-FAM-OSTP exhibited strong specific binding to ovarian cancer tissues. The cell membrane and cytoplasm of the cells exhibited a fluorescent signal. This signal was more evident on the cell membrane. The present results suggest that OSTP is a potential strategy for the development of new diagnostic strategies and drug-targeted therapies for ovarian cancer.