PSP94 contributes to chemoresistance and its peptide derivative PCK3145 represses tumor growth in ovarian cancer.

Tumor drug resistance remains a major challenge in the treatment of cancer. Here, we show that Prostatic secretory protein 94 (PSP94) levels are reduced in ovarian cancer patients with high levels of excision repair cross-complementing 1 (ERCC1), a marker for chemoresistance. We find that PSP94 is decreased in an ovarian cancer drug-resistant cell line, and plays an important role in the development of drug resistance in vitro. Our studies indicate that PSP94 can partially reverse drug resistance in mouse tumor models in vivo and that a PSP94 peptide derivative PCK3145 suppresses chemoresistant cancer cell and tumor growth in vitro and in vivo. Our investigation of the involved molecular mechanisms suggests that PSP94 may confer drug resistance by modulating the Lin28b/Let-7 signaling pathway. We introduce PSP94 and its peptide derivative PCK3145 as potential target to reverse chemoresistance in ovarian cancer and have begun to identify their relevant molecular targets in specific signaling pathways.