MiR-375 attenuates sorafenib resistance of hepatocellular carcinoma cells by inhibiting cell autophagy.

Abstract

Sorafenib is the first-line treatment for hepatocellular carcinoma (HCC), but its efficacy is limited by the drug resistance of HCC cells. MiR-375 has been shown to be an inhibitor of autophagy that contributes to sorafenib resistance of HCC cells. In this context, this study probed into the unaddressed molecular target of miR-375 in inhibiting the autophagy of HCC cells under sorafenib treatment. Western blotting and qRT-PCR (quantitative reverse transcription-polymerase chain reaction) have been applied to measure the expressions of miR-375 and SIRT5 in parental HCC cells (HepG2 and Huh7) and sorafenib-resistant HCC cells (HepG2/so and Huh7/so). HepG2/so cells were accordingly transfected with miR-375 mimic, miR-375 inhibitor, sh-SIRT5, pcDNA3.1-SIRT5 or negative control. Expressions of p62, LC3I and LC3II in HCC cells have been measured by Western blotting. Viability and apoptosis of HCC cells have been assessed by CCK-8 (cell counting kit 8) and flow cytometry respectively. Bioinformatics techniques and dual-luciferase reporter assay have been used to predict and verify the targeting relationship between miR-375 and SIRT5. MiR-375 was under-expressed and SIRT5 was over-expressed in HCC cells. An autophagy inhibitor impaired the survival of HepG2/so cells transfected with miR-375 inhibitor. An autophagy activator enhanced the drug resistance of HepG2/so cells transfected with miR-375 mimic. MiR-375 suppressed the drug resistance of HepG2/so cells by inhibiting autophagy. SIRT5 enhanced the drug resistance of HepG2/so cells by promoting autophagy and it could be targeted by miR-375. MiR-375 suppresses autophagy to attenuate the sorafenib resistance of HCC cells by regulating SIRT5. The findings of this study may provide new therapeutic targets for treating HCC.