Abstract: 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.

Key words: PM_2.5, human bronchial epithelial cells, DNA damage, single cell gel electrophoresis