Epithelial To Mesenchymal Transition Induced By HBx Protein In Hepatocellular Carcinoma And Its Molecular Mechanism

Purpose: Hepatocellular carcinoma(HCC) is one of the most frequent malignant neoplasms in China. Over 80% of the HCC are associated with chronic hepatitis B virus(HBV) infection. One of the protein products encoded by the HBV genome, the hepatitis B virus X protein(HBx), is closely related to the development of HCC. HBx is a trans-activation protein. Some of the signaling pathways, such as Src, Raf and so on, triggered by HBx are known to be involved in the acquisition of metastatic properties of HCC. In addition, previous studied have implicated that c-Src is a key regulator of epithelial to mesenchymal transition(EMT). Then we hypothesized that HBx may induce EMT of liver cancer cell by activation of c-Src.Originally EMT was defined by the formation of mesenchymal cells from epithelia in different embryonic territories. Recently, increasing evidences suggested that EMT was involved in cancer invasion and metastasis.Previous studies have shown that transforming growth factor-β1(TGF-β1) and raf-1 could induce EMT of HCC cell. Furthermore, HBx is reported to promote TGF-β1 activity and induce adherens junction disruption in a src-dependent manner. Therefore, we hypothesize that HBx induces EMT of HCC cell by activation of c-Src. The experiments outlined in this work were designed to test this hypothesis.Experimental Design: In the first part of the experiment, we immunohistochemically examined the expression of epithelial markers, E-cadherin,β-catenin andα-catenin, mesenchymal markers, N-cadherin, vimentin and fibronectin, HBx and activated c-Src, and to assess their correlation and clinicopathological significance. In the second part of the experiment, we constructed a recombinant adenovirus vector containing HBx gene. Then the HBx gene was introduced into SMMC-7721 cell via recombinant adenovirus. In the third part, we investigated the effect of HBx on SMMC-7721 cell 7 days after adenovirus...