MiR-30a-5p Enhances Cisplatin Sensitivity by Downregulating RIF1 in Ovarian Cancer.

Ovarian cancer (OC) is a common malignant tumor in females with high recurrence and poor prognosis. Cisplatin is commonly used for OC clinical treatment, but its efficacy is usually challenged by the chemotherapy resistance of cancer cells. MicroRNAs (miRNAs), including miR-30a-5p, were identified to modulate drug resistance in numerous tumors. However, molecular mechanisms of miR-30a-5p in OC chemoresistance need more illumination.MiR-30a-5p and Rap1 interacting factor 1 (RIF1) expression in OC tissues and cells were measured by qRT-PCR. The IC50 of cisplatin-resistant and cisplatin-sensitive OC cells was assessed by MTT assays. OC cell proliferation, apoptosis and migration were measured by EdU assays, TUNEL staining, and wound healing assays, respectively. The protein levels of EMT markers and RIF1 in OC cells were examined by western blotting. The binding capacity between miR-30a-5p and RIF1 was validated by luciferase reporter assays.Our study disclosed miR-30a-5p as a remarkably lowly-expressed miRNA in OC tissues in comparison to matched noncancerous tissues. Compared to parental cell lines, miR-30a-5p was also greatly downregulated in cisplatin-resistant OC cell lines. Additionally, functional assays indicated that miR-30a-5p suppressed malignant behaviors and cisplatin resistance of OC cells. Further, miR-30a-5p was revealed to target and negatively regulate RIF1 expression in OC. Moreover, it was validated that overexpressing RIF1 reverses the inhibitory influence of miR-30a-5p overexpression on malignant behaviors and cisplatin resistance of OC cells.MiR-30a-5p reduced cisplatin resistance in OC through downregulation of RIF1, which may be meaningful for targeting drug-resistant tumors.