Overexpression of connective tissue growth factor gene induces apoptosis in human aortic smooth muscle cells

Background-Connective tissue growth factor (CTGF) is expressed at very high levels particularly in the shoulder of human atherosclerotic lesions but n ot in normal blood vessels. Thus, CTGF may be important in the regulation o f vascular smooth muscle cell function in atherosclerosis, but its precise role remains elusive. Methods and Results-Full-length CTGF cDNA driven by a cytomegalovirus promo ter was transiently transfected into cultured human aortic smooth muscle ce lls (HASCs), Northern and Western analysis demonstrated that CTGF was overe xpressed in these cells 48 hours after transfection. The effects of CTGF ov erexpression on cell proliferation were evaluated by [H-3]thymidine uptake and cell count in quiescent HASCs or those stimulated with platelet-derived growth factor (PDGF). Although mock transfection showed no effect, CTGF ov erexpression significantly inhibited cell proliferation in cells stimulated by PDGF, Moreover, CTGF overexpression, but not mock transfection, signifi cantly increased apoptosis as assessed by DNA fragmentation associated with histone, TdT-mediated dUTP biotin nick end-labeling, and appearance of hyp odiploid cells by flow cytometry. Conclusions-Our results for the first time demonstrate that CTGF can also a ct as a growth inhibitor in human aortic smooth muscle cells at least in pa rt by inducing apoptosis. This may be important for the formation and compo sition of lesions and plaque stability in atherosclerosis.