PM2.5对支气管上皮细胞DNA损伤作用研究

目的：探讨大气细颗粒物（PM_2.5）染毒对人支气管上皮细胞（HBE） DNA损伤的作用。方法：分别用8、20、50 μg/mL的PM_2.5水溶液染毒HBE细胞24 h后，单细胞凝胶电泳实验（SCGE）检测DNA损伤情况。10和50 μg/L的PM_2.5水溶液染毒HBE细胞，以未染毒细胞作为阴性对照组，10 μmol/L的Cr⁶⁺水溶液为阳性对照组，实时荧光定量PCR （qPCR）检测DNA损伤修复基因hOGG1、hMTH1的mRNA表达水平的变化，Western blot检测hOGG1、hMTH1蛋白表达变化。结果：单细胞凝胶电泳检测8、20和50 μg/mL PM_2.5水溶液染毒组HBE细胞的尾部DNA含量、尾长、尾距较阴性对照组明显增加（P < 0.05或P < 0.01）。qPCR结果显示，与阴性对照组比较，HBE细胞hOGG1 mRNA表达水平在10和50 μg/mL PM_2.5水溶液染毒以及阳性对照Cr⁶⁺水溶液染毒后分别升高75.0%、132.0%、214.0%；hMTH1 mRNA分别升高61.0%、144.0%、75.0%。Western blot结果显示，与阴性对照组比较，HBE细胞hOGG1蛋白表达水平在10和50 μg/mL PM_2.5水溶液染毒以及Cr⁶⁺水溶液染毒后分别升高47.6%、64.0%、47.0%；hMTH1蛋白分别升高20.5%、49.8%、20.9%。结论：PM_2.5水溶液染毒对HBE细胞DNA具有明显的损伤作用，并引起HBE细胞DNA损伤修复基因hOGG1、hMTH1表达水平升高。

PM2.5 on DNA damage in human bronchial epithelial cells

OBJECTIVE: To investigate the effect of PM_2.5 on DNA damage in human bronchial epithelial cells (HBE). METHODS: HBE cells were exposed to PM_2.5 (0,8,20,50 μg/mL) for 24 h and DNA damage was detected using the single cell gel electrophoresis (SCGE) assay. For another investigation,cells were treated with 10 and 50 μg/mL,untreated cells were used as negative controland cells treated with 10 μmol/L Cr⁶⁺ were used as positive control. mRNA expressions of DNA damage repair genes,including hOGG1 and hMTH1,were detected using real-time quantitative PCR (qPCR) and protein expressions using Western blot. RESULTS: SCGE data show that the tail DNA content,tail length,tail distance significantly increased in the treated groups compared with the control group (P < 0.05 or P < 0.01). The qPCR data show that,compared with the control group,expression of hOGG1 mRNA increased by 75.0%,132.0%,214.0% after exposure to PM_2.5 at 10,50 μg/mL and positive control Cr⁶⁺,respectively. Expression of hMTH1 mRNA increased by 61.0%,144.0% and 75.0%,respectively. The Western blot data show that,compared with the control group,expression of hOGG1 protein increased by 47.6%,64.0%,47.0% after exposure to PM_2.5 at 10,50 μg/mL and positive control Cr⁶⁺,respectively. Expression of hMTH1 protein increased by 20.5%,49.8%,20.9%,respectively. CONCLUSION: Our investigation shows that PM_2.5 induced DNA strand breaks which caused dose-dependent increase of expression in DNA damage repair genes.