Col1A1 Production and Apoptotic Resistance in TGF-β1-Induced Epithelial-to-Mesenchymal Transition-Like Phenotype of 603B Cells

Recent studies have suggested that proliferating cholangiocytes have an important role in the induction of fibrosis, either directly via epithelial-to-mesenchymal transition (EMT), or indirectly via activation of other liver cell types. Transforming growth factor beta 1 (TGF-beta 1), a critical fibrotic cytokine for hepatic fibrosis, is a potent EMT inducer. This study aimed to clarify the potential contributions of TGF-beta 1-induced EMT-like cholangiocyte phenotype to collagen production and cell survival of cholangiocytes in vitro. Mouse cholangiocytes (603B cells) were treated with TGF-beta 1 and EMT-like phenotype alterations were monitored by morphological changes and expression of EMT-associated genes. Alterations in Col1A1 gene, Col1A1-associated miR-29s, and pro-apoptotic genes were measured in TGF-beta 1-treated 603B cells. Snail1 knockdown was achieved using shRNA to evaluate the contribution of EMT-associated changes to Col1A1 production and cell survival. We found TGF-beta 1 treatment induced partial EMT-like phenotype transition in 603B cells in a Snail1-dependent manner. TGF-beta 1 also stimulated collagen alpha 1(I) expression in 603B cells. However, this induction was not parallel to the EMT-like alterations and independent of Snail1 or miR-29 expression. Cells undergoing EMT-like changes showed a modest down-regulation of multiple pro-apoptotic genes and displayed resistance to TNF-alpha-induced apoptosis. TGF-beta 1-induced apoptosis resistance was attenuated in Snail1 knockdown 603B cells. TGF-beta 1-induced Col1A1 production seems to be independent of EMT-like transition and miR-29 expression. Nevertheless, TGF-beta 1-induced EMT may contribute to the increased survival capacity of cholangiocytes via modulating the expression of pro-apoptotic genes. Citation: Liu J, Eischeid AN, Chen X-M (2012) Col1A1 Production and Apoptotic Resistance in TGF-beta 1-Induced Epithelial-to-Mesenchymal Transition-Like Phenotype of 603B Cells. PLoS ONE 7(12): e51371. doi: 10.1371/journal.pone.0051371