Akt-mediated transforming growth factor-β1-induced epithelial-mesenchymal transition in cultured human esophageal squamous cancer cells

Epithelial-mesenchymal transition (EMT) has a crucial role during embryonic development and has also come under intense scrutiny as a mechanism through which esophageal squamous cell cancer (ESCC) progresses to become metastatic. Transforming growth factor beta (TGF-beta)-mediated EMT has been observed in a variety of cell types and has been identified as the main inducer of EMT in many types of cancer. Akt activity is involved in TGF-beta-mediated EMT; however, its precise relationship and role in EMT in ESCC has not been well explained to date. Our data demonstrated that in human ESCC tissues Akt and its activated form, phosphorylated-Akt (p-Akt), were overexpressed; in addition, Akt and p-Akt were negatively correlated with epithelial cadherin (E-cadherin). In EC-9706 cells, exogenous TGF-beta 1 could induce EMT and at the same time could increase the EC-9706 cell invasive and metastatic ability. Moreover, Akt knockdown by small-interfering RNA could attenuate the EMT induced by TGF-beta 1 by increasing the epithelial marker E-cadherin and decreasing the mesenchymal marker Vimentin. Silencing Akt expression could decrease the migration ability of EC-9706 cells efficiently. In short, Akt is likely to have a more important role in the EMT induced by TGF-beta 1 in EC-9706 and may contribute to the invasive and metastatic ability of EC-9706. Akt may be an effective therapeutic in advanced and metastatic ESCC.