Hepatitis B virus X protein stimulates the Hedgehog-Gli activation through protein stabilization and nuclear localization of Gli1 in liver cancer cells

Chronic hepatitis B virus (HBV) infection is a major cause of chronic liver diseases, which frequently results in hepatits, cirrhosis, fibrosis, and ultimately hepatocellular carcinoma (HCC). Recent studies have shown the activation of Hedgehog signaling in HCC. Here, we provide evidences that HBV induces Gli-directed gene transactivation. HBx increases the protein stability of Gli proteins, which are key transcription factors of the Hedgehog signaling pathway, and nucleus translocation of Gli1 through direct protein interaction of HBx and Gli1. This functional synergism of Gli1 protein by HBx increases the Hedgehog activation-directed gene expression. Taken together, these results suggest that HBV infection might induce hepatocellular carcinoma by modulating post-translational activation of the hedgehog signaling components. (C) 2011 Elsevier Ireland Ltd. All rights reserved.