Downregulation of miR-363 increases drug resistance in cisplatin-treated HepG2 by dysregulating Mcl-1.

Systemic therapy with cytotoxic agents provides marginal benefit in hepatocellular carcinoma (HCC) treatment especially for patients with advanced HCC. Cisplatin is one of the most active cytotoxic agents for HCC treatment. However, acquisition of cisplatin resistance is common, and one important underlying mechanism of such resistance is apoptosis-resistance. In this study, we found that miR-363 levels were significantly decreased in HCC patients treated with cisplatin-based chemotherapy. MiR-363 levels were also lower in cisplatin-resistant HepG2 (HepG2-R) cells than in HepG2 cells. Exogenous miR-363 significantly overcame cisplatin resistance in HepG2-R cells, whereas miR-363 knockdown increased the cell viability during cisplatin treatment. We further demonstrated that miR-363 directly targeted to Mcl-1 3'-UTR (3'-Untranslated Regions). Downregulation of miR-363 resulted in upregulation of Mcl-1 which is a key member of anti-apoptotic Bcl-2 family and increased drug resistance. We finally demonstrated that miR-363 decreased cisplatin resistance of HCC cell, partly by targeting Mcl-1. These data suggest that the combination of miR-363 and cisplatin may represent a novel approach in treatment for HCC, thus offering a new target for chemotherapy of HCC.