Expression of miR-224-5p is associated with the original cisplatin resistance of ovarian papillary serous carcinoma.

Chemoresistance is a major challenge to successful chemotherapy of ovarian cancer, which represents the leading cause of mortality from gynecologic malignancies. We demonstrated that overexpression of miR-224-5p in ovarian cancer patients is associated with platinum-based chemoresistance using miRNA microarray analysis and quantitative real-time polymerase chain reaction (qRT-PCR) validation in vivo, as well as in 4 human ovarian cancer cell lines (C13/OV2008; A2780CP/A2780S) in vitro. In the present study, we aimed to clarify the role of miR-224-5p in regulating the chemoresistance of ovarian cancer. By using the sensitive miRNA transient transfection, we demonstrated expression and bioactivity of miR-224-5p in ovarian cancer cell lines. It is of note that enforced expression of miR-224-5p enhanced chemoresistance to cisplatin in ovarian cancer cells through apoptosis reversion. We predicted and identified the PRKCD gene as one of the targets of miR-224-5p in mediating the primary chemoresistance of ovarian cancer patients. We showed reciprocal expression of miR-224-5p and PRKCD by quantitative analysis in complete response and incomplete response patients in vivo, and 2 pairs of cisplatin resistance and sensitive cell lines in vitro, after either miR-224-5p overexpression or knockdown transfection. Additionally, miR-224-5p and PRKCD can serve as novel predictors and prognostic biomarkers for ovarian papillary serous carcinoma (OPSC) patient response to overall disease-specific survival. Our findings suggest that miR-224-5p may function as an oncogene and induce platinum resistance in OPSC at least in part by downregulating PRKCD, thereby providing a biomarker for predicting chemosensitivity to cisplatin in patients with ovarian cancer.