PM2.5暴露对肺癌细胞A549自噬和凋亡的影响

摘要

目的 研究PM2.5暴露对人肺癌细胞A549的自噬影响探讨自噬与凋亡的关联效应.方法 100μg/mL PM2.5分别处理A549细胞0、2、4、12、24 h,采用免疫荧光观察处理PM2.524 h对细胞自噬的影响,免疫印迹法检测PM2.5对肺癌细胞自噬和凋亡重要基因的表达的影响,运用自噬抑制剂3-甲基腺嘌呤(3-MA)处理细胞进一步明确自噬通路对细胞凋亡的作用.结果 细胞自噬标志物LC3-II蛋白表达均明显著增强,LC3-II/LC3-I比值升高,而凋亡蛋白Bax逐渐下调(均P<0.05);免疫荧光显示,PM2.5组细胞的绿色荧光增强;但运用细胞自噬抑制剂(3-MA)会抑制LC3II/LC3I的转化,促进Bax的表达.结论PM2.5可诱导肺癌细胞保护性自噬的发生,抑制自噬能够促进PM2.5对肺癌细胞的凋亡诱导.%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.