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A3816 - FGF2 Augments EMT Gene Expression in Airway Epithelial Cells Exposed to TGFβ1
Author Block: L. El-Baz1, N. Shoukry2, M. Salem3, H. Hafez2, R. Guzy4; 1Medicine, University of Chicago, Chicago, IL, United States, 2Zoology, Suez University, Suez, Egypt, 3Zoology and Biotechnology, Tanta University, Tanta, Egypt, 4Medicine/Pulmonary, The University of Chicago, Chicago, IL, United States.
Rationale: Epithelial-mesenchymal transition (EMT) is a process by which differentiated epithelial cells lose their epithelial characteristics and acquire a migratory mesenchymal phenotype. EMT is considered a critical event in wound healing and tissue repair following epithelial injury, and has been implicated in the pathogenesis of pulmonary fibrosis. Transforming growth factor beta 1 (TGF-β1) plays an important role in inducing EMT in lung epithelial cells in vitro and in vivo. In a separate study, we found that fibroblast growth factor (FGF2) reversed TGFβ1-induced collagen and alpha smooth muscle actin expression in primary mouse and human lung fibroblasts. The goal of this study was to determine the effect of FGF2 on TGFβ1-induced gene expression in lung epithelial cells. Methods: BEAS-2B and A549 cells were grown near-confluence in complete growth media and treated with recombinant FGF2 (2 nM) with or without TGFβ1 (2 ng/ml) for up to 4 days. Gene expression was assessed by quantitative real-time PCR. Smad2, AKT and ERK1/2 phosphorylation was assayed by western blot. Cell migration was quantified by creating a 1mm circular wound to pretreated cells or immediately prior to treatment and measuring wound area after 3 days. Results: Treatment of BEAS-2B or A549 cells with TGFβ1 significantly reduced the expression level of the epithelial adherence junction protein E-cadherin (CDH-1) and markedly induced expression of mesenchymal proteins such as collagen I (COL1A1), SNAIL-1, tenascin C (TNC), fibronectin (FN), α-smooth muscle actin (ACTA2) and N-cadherin (CDH-2). The process of mesenchymal transition was accompanied by a morphological change from cobblestone-like shape towards a more spindle fibroblast-like shape with significant increase in cell migration and motility. FGF2 by itself caused a non-significant decrease in CDH-1 and increase in ACTA2. FGF2 enhanced TGFβ1 induced suppression of CDH-1 and upregulation of ACTA2, as well as migration of TGFβ1-treated cells, maintaining their spindle-like shape. FGF2 suppressed TGFβ1 induced expression of COL1A1 and SNAIL-1. FGF2 did not alter TGFβ1 induced Smad2 phosphorylation. By itself, FGF2 increased AKT, but not ERK1/2, phosphorylation in cultured epithelial cells. Conclusions: This study shows that FGF2 does not significantly affect BEAS-2B and A549 cells on its own, but inhibits TGFβ1 induced COL1A1 expression and augments TGFβ1 induced EMT gene expression. This study suggests a synergistic effect between TGFβ1 and FGF2 that may play an important role in wound healing and tissue repair after injury, and provide an insight into potential uses of FGF2 following lung injury and in pulmonary fibrosis.