FGF-1 reverts epithelial-mesenchymal transition induced by TGF-{beta}1 through MAPK/ERK kinase pathway.
Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal lung disease characterized by the expansion of the fibroblast/myofibroblast population and aberrant remodeling. However, the origin of mesenchymal cells in this disorder is still under debate. Recent evidence indicates that epithelial-mesenchymal transition (EMT) induced primarily by TGF-beta1 plays an important role; however, studies regarding the opposite process, mesenchymal-epithelial transition, are scanty. We have previously shown that fibroblast growth factor-1 (FGF-1) inhibits several profibrogenic effects of TGF-beta1. In this study, we examined the effects of FGF-1 on TGF-beta1-induced EMT. A549 and RLE-6TN (human and rat) alveolar epithelial-like cell lines were stimulated with TGF-beta1 for 72 h, and then, in the presence of TGF-beta1, were cultured with FGF-1 plus heparin for an additional 48 h. After TGF-beta1 treatment, epithelial cells acquired a spindle-like mesenchymal phenotype with a substantial reduction of E-cadherin and cytokeratins and concurrent induction of alpha-smooth muscle actin measured by real-time PCR, Western blotting, and immunocytochemistry. FGF-1 plus heparin reversed these morphological changes and returned the epithelial and mesenchymal markers to control levels. Signaling pathways analyzed by selective pharmacological inhibitors showed that TGF-beta1 induces EMT through Smad pathway, while reversion by FGF-1 occurs through MAPK/ERK kinase pathway, resulting in ERK-1 phosphorylation and Smad2 dephosphorylation. These findings indicate that TGF-beta1-induced EMT is reversed by FGF-1 and suggest therapeutic approaches to target this process in IPF.
Ramos
Carlos
C
Instituto Nacional de Enfermedades Respiratorias, Universidad Nacional Autónoma de México, México City, México.
Becerril
Carina
C
Montaño
Martha
M
García-De-Alba
Carolina
C
Ramírez
Remedios
R
Checa
Marco
M
Pardo
Annie
A
Selman
Moisés
M
D000818:Animals; D054338:Cell Transdifferentiation / Q000187:drug effects*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D016220:Fibroblast Growth Factor 1 / Q000494:pharmacology*; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000209:etiology / Q000473:pathology; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D008648:Mesoderm / Q000187:drug effects / Q000502:physiology*; D008856:Microscopy, Fluorescence; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology; D010766:Phosphorylation; D051381:Rats; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*
C497782:SMAD2 protein, human; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D016220:Fibroblast Growth Factor 1; D020929:Mitogen-Activated Protein Kinase Kinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9