Circular RNA Cdr1as Upregulates SCAI to Suppress Cisplatin Resistance in Ovarian Cancer via miR-1270 Suppression.

The aim of this study is to explore the roles of circular RNA (circRNA) Cdr1as on cisplatin resistance in ovarian cancer and explore the underlying mechanisms. We investigated the expression of circRNAs in five paired cisplatin-sensitive and cisplatin-resistant tissues of ovarian cancer by microarray analysis. The quantitative real-time PCR analysis was to investigate the expression pattern of Cdr1as in cisplatin-resistant ovarian cancer patient tissues and cell lines. Then, the effects of Cdr1as on cisplatin resistance, cell proliferation, and apoptosis were assessed in ovarian cancer cells. In this study, Cdr1as was observed to be downregulated in cisplatin-resistant patient tissues and cell lines. Overexpression of Cdr1as inhibited cell proliferation and promoted the cisplatin-induced cell apoptosis in ovarian cancer cells. Then we demonstrated that repressed Cdr1as promoted the miR-1270 expression, and miR-1270 could bind to the predicted binding site of Cdr1as. Furthermore, we found that miR-1270 displayed its role via modulating the Suppressor of Cancer Cell Invasion (SCAI) expression. Importantly, we demonstrated that Cdr1as was downregulated in serum exosomes from cisplatin-resistant patients. In summary, our study demonstrated that Cdr1as sensitizes ovarian cancer to cisplatin by regulating the miR-1270/SCAI signaling pathway.