Inhibition of autophagy significantly enhances combination therapy with sorafenib and HDAC inhibitors for human hepatoma cells

AIM: To clarify whether histone deacetylase inhibitors histone deacetylase inhibitors (HDACIs) can sensitize hepatocellular carcinoma (HCC) cells to sorafenib treatment. METHODS: Bax, Bcl-2, ATG5-ATG12, p21, and p27 protein levels in Hep3B, HepG2, and PLC/PRF/5 cells were examined by Western blot. CCK8 and a fluoro-metric caspase-3 assay were used to examine cellular viability and apoptosis levels. The effect of Beclin-1 on sensitization of HCC cells to sorafenib was examined by transfecting Beclin-1 siRNA into Hep3B, HepG2, and PLC/PRF/5 cells. RESULTS: Autophagy inhibition enhances the inhibitory effects of vorinostat and sorafenib alone or in combination on HCC cell growth. Vorinostat and sorafenib synergistically induced apoptosis and cell cycle alterations. Western blot data indicated that HDACIs and Beclin- 1 knockdown increased the p53 acetylation level. The knockdown of Beclin-1 enhanced the synergistic effect of the combination of vorinostat with sorafenib. CONCLUSION: HDACIs can sensitize HCC cells to sorafenib treatment by regulating the acetylation level of Beclin-1. (C) 2014 Baishideng Publishing Group Co., Limited. All rights reserved.