miR-145 regulates chemoresistance in hepatocellular carcinoma via epithelial mesenchymal transition.

Resistance to chemotherapeutic drugs is a major obstacle in hepatocellular carcinoma (HCC) therapy. MicroRNA—145 (miR—145) has been shown to be down—regulated in several cancers and may be involved in the process of carcinogenesis. The present study aimed to evaluate the effects of miR—145 in adriamycin (ADM)—resistant human HCC cells. We found that miR—145 was significantly reduced in HepG2/ADM and HuH7/ADM cells compared with the chemosensitive parental cells. Up—regulation of miR—145 increased the ADM cytotoxicity in chemoresistant tumor cells. In addition, Smad3 was identified as the target of miR—145 and miR—145 overexpression inhibited Smad3 expression both at the mRNA and protein levels. The luciferase reporter assay confirmed that Smad3 was a direct target of miR—145. Moreover, up—regulation of miR—145 suppressed Smad3 related EMT features as shown by increased expression of E—cadherin and reduced vimentin level in HepG2/ADM and HuH7/ADM cells. Our study demonstrated that miR—145 modulated both chemoresistance and EMT in HCC cells, and up—regulation of miR—145 might be a potential therapeutic strategy for treatment of chemoresistant HCC.