Synergistic effect of toosendanin and regorafenib against cell proliferation and migration by regulating WWOX signaling pathway in hepatocellular carcinoma

Regorafenib (RGF), a second-line multi-kinase inhibitor in the treatment of HCC (hepatocellular carcinoma) after sorafenib failure, exposes to the risk of drug resistance and subsequent progression of HCC patients. Toosendanin (TSN), a triterpenoid has presented excellent inhibition on several tumors. The purpose of this study is to investigate the inhibitory effect of the combination of TSN and RGF on HCC cells. We identified that TSN and RGF combination (TRC) synergistically inhibited the proliferation and migration of MHCC-97L cells. The upregulation of WWOX (WW-domain containing oxidoreductase) played a vital role in the HCC cell growth treated with TRC. TRC suppressed the phosphorylation of Stat3 and expression of DVL2, negatively regulated the activity of β-catenin by promoting the phosphorylation of GSK3β. In addition, the intranuclear proteins, including MMP2, MMP9, and C-MYC were significantly inhibited by TRC. The in vivo xenograft models confirmed that TRC effectually prevented the tumor growth through upregulating WWOX. Therefore, the treatment of TRC may be a potential solution of RGF resistance and promising therapeutic method in malignant HCC.