Abstract

Hepatocelluar carcinoma severely affects patients because of high incidence of cancer-mediated deaths. Wnt and hedgehog signaling pathways have been known to be associated with hepatocelluar carcinoma cell proliferation and migration; however, molecular connections between the two pathways are largely unknown. In this investigation the expression levels of key Wnt signaling genes (Wnt3, TCF7, and FZD8) and hedgehog signaling genes (Smo, Gli1, Gli2, and Gli3) were identified to be higher in hepatocelluar carcinoma cell lines (HepG2 and SMMC-7721) than in normal liver cell line (LO2). Western blot results indicated that β-catenin, Smo, and Gli1 levels were all higher in hepatocelluar carcinoma cells than in normal liver cells. In addition, overexpression of β-catenin activated Smo and Gli1 as well as accelerated HepG2 cell migration and proliferation. Further, immunoprecipitation assay showed that β-catenin/TCF4 complex directly bound to Smo and Gli1 promoters. Suppression of β-catenin or Gli1 inhibited HepG2 cell migration and proliferation, and Gli1 silencing inhibited β-catenin overexpression effects on cell migration and proliferation, and silencing of β-catenin inhibited Wnt3a-meidated induction of hedgehog signalling gene expressions, suggesting that β-catenin acts at the upstream of Smo and Gli1. Taken together, these results provided information for direct connection between Wnt and hedgehog signalling via β-catenin/TCF4 complex that broaden the regulatory mechanism for Wnt and hedgehog signalling pathways.