title: Rapamycin regulates connective tissue growth factor expression of lung epithelial cells via phosphoinositide 3-kinase.
abstract: The pathogenesis of idiopathic pulmonary fibrosis (IPF) remains largely unknown. It is believed that IPF is mainly driven by activated alveolar epithelial cells that have a compromised migration capacity, and that also produce substances (such as connective tissue growth factor, CTGF) that contribute to fibroblast activation and matrix protein accumulation. Because the mechanisms regulating these processes are unclear, the aim of this study was to determine the role of rapamycin in regulating epithelial cell migration and CTGF expression. Transformed epithelial cell line A549 and normal human pulmonary alveolar or bronchial epithelial cells were cultured in regular medium or medium containing rapamycin. Real time reverse transcriptase polymerase chain reaction was employed to determine CTGF mRNA expression. Western blotting and an enzyme-linked immunosorbent assay were used for detecting CTGF protein. Wound healing and migration assays were used to determine the cell migration potential. Transforming growth factor (TGF)-β type I receptor (TβRI) inhibitor, SB431542 and phosphoinositide 3-kinase (PI3K) inhibitor, LY294002 were used to determine rapamycin's mechanism of action. It was found that treatment of A549 and normal human alveolar or bronchial epithelial cells with rapamycin significantly promoted basal or TGF-β1 induced CTGF expression. LY294002, not SB431542 attenuated the promotional effect of rapamycin on CTGF expression. Cell mobility was not affected by rapamycin in wound healing and migration assays. These data suggest rapamycin has a profibrotic effect in vitro and underscore the potential of combined therapeutic approach with PI3K and mammalian target of rapamycin inhibitors for the treatment of animal or human lung fibrosis.
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Xu
authors.forename: Xuan
authors.initials: X
authors.lastname: Wan
authors.forename: Jing
authors.initials: J
authors.lastname: Geng
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.forename: Huaping
authors.initials: H
authors.lastname: Dai
mesh_terms: D002461:Cell Line, Transformed; D002465:Cell Movement / Q000187:drug effects*; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D051785:Smad Proteins / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D012333:RNA, Messenger; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D020123:Sirolimus
keywords: Connective tissue growth factor; epithelial cell; idiopathic pulmonary fibrosis; migration; rapamycin