Silent information regulator 1 regulates the human alveolar epithelial A549 cell apoptosis induced by cigarette smoke extract / 中华老年医学杂志

ABSTRACT

Objective To investigate the effect of silent information regulator 1 (SIRT1)on cigarette smoke extract (CSE)-induced apoptosis of human alveolar epithelial cell (AECs).Methods The expression levels of SIRT1 protein were examined by Western Blotting in A549 cells that were treated with CSE at different concentrations.The impairment models of A549 cells induced by CSE were established.The concentration of CSE was 20.0％ and the treatment time of CSE was 24 hours.A549 cells were pretreated with 20 μmol/L resveratrol(Res)or 5 mmol/L nicotinamide (NAM) for 2 h before CSE treatment.The protein levels of SIRT1,Bax and Bcl2 were further explored by Western blotting.The proportion of apoptotic A549 cells was measured using MTT.Results The expression of SIRT1 was reduced after treatment with CSE in a dose-dependent manner(P＜0.05).Compared with the control group,the group of CSE treatment with 2.5％,5.0％,10.0％,20.0％and 40.0％ CSE for 24h showed that the expression of SIRT1 in A549 cells was decreased by 25.6％(P＜0.05),35.2％(P＜0.05),38.7％ (P＜0.05),57.9％ (P＜0.05)and 64.0％(all P＜0.05)separately; that A549 cell viability was decreased in a dose-dependent manner; and that A549 cell viability was decreased by 10.2％(t=2.035,P＜0.05),18.4％(t=4.269,P＜0.05),27.7％ (t=5.963,P＜0.05),59.0％(t=21.140,P＜0.05)and 88.1％(t=58.827,P＜0.05)separately.CSE plus 20 μmol/L Res pretreatment reversed the expression levels of SIRT1,Bax and Bcl2 in A549 cells (all P＜0.05)and reduced the apoptosis of A549 cells.The effects of CSE on inhibiting SIRT1 pathways were aggravated by NAM (an inhibitor of SIRT1) in the A549 cells (P＜ 0.05).Conclusions SIRT1 plays important role in regulating the apoptosis of human alveolar epithelial A549cell induced by CSE.SIRT1 may inhibit apoptosis by up-regulating Bcl2 expression and downregulating Bax expression,which has a protective effect on A549 cells apoptosis induced by CSE.