TGF-β1 pathway affects the protein expression of many signaling pathways, markers of liver cancer stem cells, cytokeratins, and TERT in liver cancer HepG₂ cells

Liver cancer is one of the most common human malignancies, and transforming growth factor-beta (TGF-β) pathway plays a key role in its pathogenesis. To study the relationship between TGF-β pathway and the related protein expression of many signaling pathway, markers of stem cells, CK family, and others, liver cancer HepG₂ cells were transfected with siRNA directed against TGF-β1 or were treated with exogenous TGF-β1. Then, these protein levels were measured by Western blotting. After siRNA transfection, TGF-β1 protein level was decreased, indicating that the siRNA against it was effective. In exogenous TGF-β1 group, the expression of smad4, smad2/3, and β-catenin proteins was increased, whereas that of p-smad2/3, CD133, cleaved Notch1, and epithelial cell adhesion molecule (EpCAM) proteins at 48 h was decreased. The expression of CK8 and CK18 proteins was increased at 24 h and was decreased at 48 and 96 h. In TGF-β1-silenced group, the expression of smad2/3, β-catenin, cleaved-notch1, and CK18 proteins was decreased, while that of smad4, p-smad2/3, CD133, EpCAM, and CK8 proteins was increased. TERT protein expression was slightly increased in exogenous TGF-β1 group at 48 h and in TGF-β1-silenced group at 96 h. TGF-β1 did not affect the protein expression of CK19 and HIF-1. Thus, TGF-β1 pathway plays an important role in cell regulation of liver cancer through the modulation of these proteins. These data will contribute to the understanding of the pathogenesis of liver cancer and the role of TGF-β pathway in this process.