Activator protein-2alpha inhibits activation of Caspase 3 and cell apoptosis induced by cigarette smoke extract in vascular endothelial cells.]

To investigate the effect of activator protein-2alpha (AP-2alpha) on activation of cysteine proteases with aspartate specificity 3 (Caspase 3) and the apoptosis of vascular endothelial cells (ECV304) induced by cigarette smoke extract (CSE).ECV304 were cultured in vitro, and those at the exponential growth phase were studied in experiments. The cells were cultured with 0.0%, 2.5%, 5.0%, 10.0%, 15.0%, and 20.0%CSE respectively for 24 h, and in another experiment, the cells were exposed to 5.0%CSE for 0, 6, 12, 18, 24, 36, and 48 h respectively. Then the cells were infected with different virus vectors or treated by 5%CSE alone for 24 h. Cell apoptosis, and proliferation were tested by Hoechst staining and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) respectively, while the expression of cleaved Caspase 3 and AP-2alpha induced by CSE were tested by Western blot. The effects of over-expression of AP-2alpha on ECV304 apoptosis and the expression of cleaved Caspase 3 were investigated by transfection, Hoechst staining and Western blot.Compared with the blank control group (0.630 +/- 0.086), the proliferation was significantly increased in 2.5% CSE group (0.754 +/- 0.109), while that was decreased in the 5.0%, 10.0%, 15.0% and 20.0% CSE groups in a concentration-dependent manner. The cell apoptosis rate induced by 5.0%CSE was increased in a time-dependent manner [from (5.0 +/- 1.0)% to (72.6 +/- 12.1)%], and the differences among the groups was significant (chi(2) = 1773.0, P < 0.01). The expressions of AP-2alpha (0.882 +/- 0.014) in 24 h CSE-treatment group was higher than that of the control group (0.635 +/- 0.005, t = 5.21, P < 0.01). Over-expression of AP-2alpha inhibited the cell apoptosis [the apoptosis rate was (0.9 +/- 0.4)%, (7.5 +/- 0.9)% respectively] and the expression of cleaved Caspase 3 (the ratio were 0.300 +/- 0.020, 0.484 +/- 0.025) induced by CSE (t = 6.96, 8.75, all P < 0.01).AP-2alpha was shown to inhibit the activation of Caspase 3 and the apoptosis of ECV304 induced by CSE.