SYNCHRONIZATION OF CULTURED VASCULAR SMOOTH-MUSCLE CELLS FOLLOWING REVERSAL OF QUIESCENCE INDUCED BY TREATMENT WITH THE ANTIOXIDANT N-ACETYLCYSTEINE

Smooth muscle cell (SMC) proliferation plays an important role in the pathogenesis of vascular diseases such as atherosclerosis and postangi oplasty restenosis. Recently we demonstrated the thiol antioxidant N-a cetylcysteine (NAC) inhibits constitutive NF-kappa B/Rel activity and growth of vascular SMCs. Here we show that treatment of human and bovi ne aortic SMC with the thiol antioxidant NAC causes cells to exit the cell cycle and remain quiescent as determined by a greatly reduced inc orporation of [H-3]thymidine and G(0)/G(1) DNA content. Removal of NAC from the culture medium stimulates SMCs to synchronously reenter the cell cycle as judged by induction of cyclin D1 and B-myb gene expressi on during mid and late G(1) phase, respectively, and induction of hist one gene expression and [H-3]thymidine incorporation during S phase. T he time course of cyclin D1, B-myb, and histone gene expression after NAC removal was similar to that of serum-deprived cells induced to res ume cell cycle progression by the addition of fetal bovine serum to th e culture medium. Taken together, these results indicate that NAC trea tment causes SMCs to enter a reversible G(0) quiescent, growth-arreste d state. Thus, NAC provides an important new method for synchronizing SMCs in culture. (C) 1998 Academic Press.