Ogunwobi et al. cleverly use a novel cell line, “LH86”, derived from a well-differentiated HCC (not associated with hepatitis B or C cirrhosis) to demonstrate EMT. This is significant, as both hepatitis B and C viruses can induce EMT innately as a consequence of the expression of the HBV X gene6 or hepatitis C core protein7 in cultured liver cells. EMT would seem a logical mechanism for the migration and invasion of HCC. If so, its presence in HCC should be associated with advanced, metastatic, and recurrent
disease (type 3 EMT). So is there previous work supporting a role for EMT in HCC? Xu et al.8 first promoted EMT in a human HCC cell line (SMMC7721) using TGFβ-1, the mesenchymal phenotype being confirmed by a change to spindle morphology, FK506 loss of E-cadherin, and the nuclear translocation of β-catenin. As discussed before, Snail1 and Twist are major inducers of EMT, through the downregulation of E-cadherin. It is therefore interesting that Snail1 and Twist co-expression is associated with a significant reduction in cancer-free interval and overall survival.9 Furthermore, tumor recurrence after RFA is associated with the induction of EMT10 in treated HCC. Thus, EMT in HCC, regardless of the specific factors responsible, demonstrates
more vascular invasion, metastasis, and poorer survival.11 Of course, if we are to reverse the process of EMT in HCC, we must have a better molecular understanding of the mechanism. It is therefore LY294002 price medchemexpress of interest that Ogunwobi et al. demonstrate that TGFβ-1, EGF, HGF, and bFGF produce a significant increase in cyclooxygenase-2 (COX-2) mRNA and Akt-1 mRNA, which are possible intracellular signaling molecules.2 They also demonstrated the reversal of TGFβ-1 induced vimentin mRNA expression and E-cadherin protein loss using inhibitors of both COX-2 and Akt pathways. The role of EMT in hepatology appears
to not be confined to HCC. For example, it is well studied in relation to the progression of liver fibrosis, with variable conclusions being reached thus far (type 2 EMT). Hepatic fibrosis is due to the deposition of the extracellular matrix by stellate cells and portal fibroblasts. EMT might contribute to liver fibrosis through the conversion of cholangiocytes and hepatocytes to myofibroblasts. However, it remains possible that myofibroblasts are derived directly from hepatic stellate cells and bone marrow stem cells,12,13 and that EMT of hepatocytes and cholangiocytes is not involved. Nonetheless, TGFβ-1 might again be critical to this process,14 as it induces EMT in mouse hepatocytes, which lose their epithelial phenotype through the loss of E-cadherin; a major component of the adherens junction. Furthermore, in a mouse model of acute liver fibrosis, it has been demonstrated that hepatocytes upregulate Snail1, an endogenous transcription factor of EMT.