miR-۲۶b enhances radiosensitivity of hepatocellular carcinoma cells by targeting EphA۲

Objective(s): Although low-dose radiotherapy (RT) that involves low collateral damage is more suitable for hepatocellular carcinoma (HCC) than traditional high-dose RT, but to achieve satisfactory therapeutic effect with low-dose RT, it is necessary to sensitize HCC cells to irradiation. This study was aimed to determine whether radiosensitivity of HCC cells can be enhanced using miR-۲۶b by targeting erythropoietin producing human hepatocelluar A۲ (EphA۲). Materials and Methods: The levels of miR-۲۶b and EphA۲ expression in multiple HCC cell lines were assessed by qPCR and western blotting, respectively, and compared with those in a hepatic cell line. HCC ۹۷H cells were transfected with miR-۲۶b mimics, EphA۲-ShRNA or EphA۲ over-expression vector before exposure to low-dose irradiation. Results:Different degrees of miR-۲۶b down-regulation and EphA۲ up-regulation were observed in all HCC cell lines, among which the HCC ۹۷H cell line expressed the lowest level of miR-۲۶b and highest level of EphA۲. EphA۲ was verified as the target of miR-۲۶b by dual luciferase reporter assay. HCC ۹۷H cells transfected with miR-۲۶b mimics or EphA۲-ShRNA reduced the expression of EphA۲ protein, with significantly lower cell proliferation rate and cell invasion ability and higher apoptosis rate in response to low-dose irradiation than those in the non-transfected cells. These results were reversed after EphA۲ was overexpressed by transfection with the EphA۲ overexpression vector. Co-transfection with miR-۲۶b mimics and EphA۲ overexpression vector barely altered EphA۲ expression level and cell response to low-dose irradiation. Conclusion: These data suggest that miR-۲۶b enhances radiosensitivity of HCC ۹۷H cells by targeting EphA۲ protein.

Keywords:

EphA۲ , HCC ۹۷H cells , Hepatocellular carcinoma , miR-۲۶ , Radiosensitivity