Transforming growth factor beta1 induces epithelial-to-mesenchymal transition of A549 cells.
Idiopathic pulmonary fibrosis (IPF) comprises an aggregate of mesenchymal cells. However, the cellular origin of these mesenchymal phenotypes remains unclear. Transforming growth factor beta1 (TGF-beta1) has been known as the main cytokine involved in the pathogenesis of IPF. We examined whether the potent fibrogenic cytokine TGF-beta1 could induce the epithelial-to-mesenchymal transition (EMT) in the human alveolar epithelial cell line, A549, and determined whether snail expression is associated with the phenotypic changes observed in the A549 cells. EMT was investigated with cells morphology changes under phase-contrast microscopy, western blotting, and indirect immunofluorescence stains. E-cadherin and transcription factor, snail, were also evaluated by measuring mRNA levels using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The data showed that TGF-beta1 induced A549 cells with epithelial cell characteristics to undergo EMT in a concentration-dependent manner. Following TGF-beta1 treatment, A549 cells induced EMT characterized by cells morphological changes, loss of epithelial markers Ecaherin and cytokeratin, increased stress fiber reorganization by F-actin, and cytokeratin replacement by vimentin. Although IL-1beta failed to induce A549 cells to undergo EMT, the combination of TGF-beta1 and IL-1beta showed synergy effects in cells morphology changes and the expression of mesenchymal markers. The snail expression study using RT-PCR analysis provided that loss of E-cadherin expression was associated with snail expression. Stimulation of A54 cells with TGF-beta1 plus IL-1beta revealed a higher level of snail expression. Our data showed that EMT of A549 cells might be closely associated with snail expression.
Kim
Ju Hee
JH
Department of Internal Medicine, Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Anyang, Korea.
Jang
Young Sook
YS
Eom
Kwang-Seok
KS
Hwang
Young Il
YI
Kang
Hae Raen
HR
Jang
Seung Hun
SH
Kim
Cheol Hong
CH
Park
Young Bum
YB
Lee
Myung Goo
MG
Hyun
In Gyu
IG
Jung
Ki-Suck
KS
Kim
Dong-Gyu
DG
D000199:Actins / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007633:Keratins / Q000378:metabolism; D008648:Mesoderm / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000502:physiology*; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D015820:Cadherins; D053773:Transforming Growth Factor beta1; D014746:Vimentin; D007633:Keratins