Inhibition of the Wnt/β-catenin signaling pathway improves the anti-tumor effects of sorafenib against hepatocellular carcinoma.

Sorafenib, a multikinase inhibitor, is currently the only approved drug for advanced hepatocellular carcinoma (HCC). The current study tested the hypothesis whether inhibition of the Wnt/β-catenin signaling pathway could improve the anti-tumor effects of sorafenib in HCC. ICG-001, a small molecule which blocks the interaction of β-catenin with its transcriptional coactivator CBP, dose-dependently enhanced the growth-suppressive and apoptosis-induction effects of sorafenib in multiple HCC cell lines. Downregulation of β-catenin by RNA interference increased sorafenib sensitivity, whereas overexpression of β-catenin reduced sorafenib sensitivity in Huh7 cells. The sorafenib-sensitization effect of short hairpin RNA (shRNA)-mediated β-catenin downregulation in Huh7 cells was attenuated by β-catenin overexpression. Mechanistically, sorafenib combined with ICG-001 or shRNA-mediated β-catenin downregulation augmented the induction of apoptosis, and resulted in a significant downregulation of Mcl-1 in HCC cells. In Huh7 cell mouse xenograft model, the combination of ICG-001 and sorafenib showed a more significant growth-retarding effect than single agent treatment of sorafenib or ICG-001. Our data indicate that inhibition of the Wnt/β-catenin signaling pathway improves the antitumor effects of sorafenib against HCC in vitro and in vivo.