[Effects of CTGF gene silencing on the proliferation and myofibroblast differentiation of human lung fibroblasts].

Connective tissue growth factor (CTGF) is involved in the differentiation of lung fibroblast into myofibroblast and is considered as an important mediator in the pathogenesis of pulmonary fibrosis. In the present study, a CTGF small interference RNA (siRNA) expressing plasmid (CTGF-siRNA) was constructed and stably transfected into human lung fibroblast cell line, MRC-5. Stable clones with CTGF gene silencing (CTGF-siRNA/MRC-5) were successfully established by G418 screening and further confirmed by real-time quantitative PCR and Western blot. Cell proliferation was investigated by growth curve analysis, and cell doubling time of the CTGF-siRNA/MRC-5 cells was markedly longer than that of the control cells (P < 0.05). Compared with control cells, the expression of alpha-smooth muscle actin (alpha-SMA), the marker of myofibroblast differentiation, was decreased in CTGF-siRNA/MRC-5 cells. Moreover, the deposition of extracellular matrix (ECM) proteins (such as collagen type I and fibronectin) in CTGF-siRNA/MRC-5 cells was also declined. Our data suggest that CTGF may play an important role in the differentiation of lung fibroblast into myofibroblast, and that siRNA targeting CTGF gene might provide a new strategy for gene therapy of pulmonary fibrosis.