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Cigarette smoke-induced EGFR activation promotes epithelial mesenchymal migration of human retinal pigment epithelial cells through regulation of the FAK-mediated Syk/Src pathway

Epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is inevitable change of age-related macular degeneration (AMD). Smoking is a major risk factor for the development of EMT in several diseases, including lung cancer. Cigarette smoke-induced stress promotes the producti...

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Detalles Bibliográficos
Autores principales: Park, Ga Bin, Kim, Daejin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: D.A. Spandidos 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5802154/
https://www.ncbi.nlm.nih.gov/pubmed/29286114
http://dx.doi.org/10.3892/mmr.2017.8355
Descripción
Sumario:Epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is inevitable change of age-related macular degeneration (AMD). Smoking is a major risk factor for the development of EMT in several diseases, including lung cancer. Cigarette smoke-induced stress promotes the production of epidermal growth factor (EGF) in RPE cells. However, the underlying signaling pathways induced by aberrant EGF receptor (EGFR) expression in cigarette smoke-exposed RPE cells remain largely unknown. In the present study, the morphological transformation and production of EMT-associated cytokines were investigated to analyze the effect of smoking on the retina. Furthermore, EGF-treated or cigarette smoke-exposed RPE cells, as well as the downstream targets of EGFR, were investigated to identify the key molecules involved in EMT of cigarette smoke-stimulated RPE cells via immunoblotting. Exposure of RPE cells to cigarette smoke extract (CSE) induced secretion of VEGF and TGF-β1, and increased the expression of EMT markers. CSE-mediated focal adhesion kinase (FAK) activation resulted in the phosphorylation and activation of spleen associated tyrosine kinase (Syk)/Src proto-oncogene, non-receptor tyrosine kinase (Src), leading to migration and invasion of RPE cells. Knockdown of FAK or pharmacological inhibition of Syk/Src abrogated CSE-mediated VEGF and TGF-β1 production and blocked the phosphorylation of Smad2/3 in CSE-stimulated RPE cells. Erlotinib (an EGFR inhibitor) suppressed EGF and CSE-mediated switch from an epithelial to mesenchymal phenotype. Baicalein, an inhibitor of 12/15-lipooxygenase, also efficiently suppressed CSE-induced EMT processes by inhibiting EGFR-associated downstream signaling transduction. The results identified a novel signaling pathway mediated by EGFR in CSE-activated RPE cells, and suggest baicalein as a potential new therapeutic drug for CSE-associated retinopathy.