Résumé
Objective To investigate the effect of PM2.5 airborne particulate matter with a mean diameter of less than 2.5μm exposure on autophagy and explore the links between autophagy and apoptosis in human lung cancer cells(A549). Methods A549 cells were exposed to 100μg/mL PM2.5 with or without 3-MA(autophagy inhibitor)for various periods of 0、2、4、12 or 24 hrs. Autophagy in A549 cells was assessed by determining the lev-el of LC3(a known autophagy marker)using confocal microscopy. The level of microtubule-associated protein 1 light chain 3(LC3) Ⅱ conversion and Bax (a pro-apoptotic protein) was detected by western blotting. Results The expression of LC3 and the ratio of LC3-II/LC3-I in A549 cells was significantly increased and Bax was signifi-cantly decreased following exposure to PM2.5100 μg/mL for 24 h in a time-dependent manner(P < 0.05). After treated with 100 μg/mL PM2.5,the formation of LC3 in A549 cells as evidenced by the intensity of intracellular fluorescence was significantly increased ,and autophageosomes were observed around nucleus in A549 cells. Fur-thermore blockage of autophagy by 3-MA led to a significant increase in the pro-apoptotic protein Bax. Conclu-sion PM2.5 exposure induces autophagy which may protect against apoptosis induced by PM2.5 in A549 cells.