Cyclooxygenase-2 and Akt mediate multiple growth-factor-induced epithelial-mesenchymal transition in human hepatocellular carcinoma.

Abstract

Cancer invasion and metastasis are characterized by epithelial-mesenchymal transition (EMT). Hepatocellular carcinoma (HCC) causes metastasis and significant mortality. Elucidating factors promoting EMT in HCC are necessary to develop effective therapeutic strategies. The LH86 cell line was developed in our laboratory from well-differentiated HCC without associated hepatitis or cirrhosis and used as a model to study EMT in HCC. Effects of transforming growth factor β-1, epidermal growth factor, hepatocyte growth factor and basic fibroblast growth factor (bFGF) were examined using morphology, molecular markers, effects on migration and tumorigenicity. The involvement of cyclooxygenase-2 (COX-2) and Akt were examined. LH86 cells display epithelial morphology. Transforming-growth-factor-β-1-, epidermal-growth-factor-, hepatocyte-growth-factor- and basic-fibroblast-growth-factor-induced mesenchymal changes in them were associated with loss of E-cadherin, albumin, α-1 anti-trypsin expression and increased expression of vimentin, collagen I and fibronectin. There was associated increased migration, tumorigenicity and increased expression of COX-2, prostaglandin E2 (PGE2), Akt and phosphorylated Akt. Inhibition of COX-2 and Akt pathways led to inhibition of characteristics of EMT. Multiple growth factors induce EMT in HCC. COX-2 and Akt may mediate EMT-associated development and progression of HCC and molecular targeting of COX-2 and Akt may be an effective therapeutic or chemopreventive strategy in advanced and metastatic HCC.