PURPOSE: Cigarette smoke has been demonstrated to induce pulmonary vascular remodeling, which is characteristic of increased medial thickening of the pulmonary arteries mainly resulting from the abnormal proliferation of pulmonary artery smooth muscle cells(PASMCs). Connective tissue growth factor (CTGF) is involved in diverse biological precesses such as cell proliferation, adhesion, angiogenesis. Previous studies have documented that CTGF is involved in systemic vascular remodeling. The potential role of CTGF, however, in pulmonary vascular remodeling is unclear. The aim of the present study was to examine the influence of cigarette smoke on the expression of CTGF in rPASMCs and investigate whether CTGF regulates rPASMCs proliferation by cyclin D1 upregulation in vitro.
METHODS: In this study, primary cultured rPASMCs were exposed to cigarette smoke extract(CSE). CTGFsiRNA or cyclin D1siRNA were transfected to rPASMCs. Cell proliferation was determined by cell counting and BrdU incorporation assay. Real time RT-PCR was employed to examine relative expression levels of mRNA. Protein expression was analysed by western blotting and immunofluorescence staining. Cell cycle distribution was measured using flow cytometry(FCM).
RESULTS: The expression of CTGF was significantly increased in rPASMCs at both mRNA and protein levels when rPASMCs were treated with 2% CSE, which then promoted the proliferation of rPASMCs. CTGFsiRNA could inhibited the proliferation induced by CSE. Furthermore, CTGFsiRNA could markedly suppress the mRNA and protein expression of cyclin D1 in rPASMCs and led to the cell cycle arrest in G0/G1 phase and thus reduced the rPASMCs proliferation.
CONCLUSION: Collectively, the findings of current study strongly indicated that cigarette smoke extract increased CTGF expression in rPASMCs and suggested that upregulation of CTGF could promote rPASMCs cell proliferation and G1/S transition at least in part through regulating cyclin D1, which might play an important role in pulmonary vascular remodeling induced by cigarette smoke. Our results support the idea of the usage of CTGF or cyclin D1 blockers as a novel therapy for pulmonary vascular diseases.
CLINICAL IMPLICATIONS: CTGF is a important factor in pulmonary vascular remodeling in smokers.
DISCLOSURE: Ran Wang, No Financial Disclosure Information; No Product/Research Disclosure Information