苯并（a）芘致人支气管上皮细胞DNA损伤及与组蛋白H2A单泛素化水平的关系

[目的]通过体外细胞培养途径,探讨苯并（a）芘（benzo[a]pyrene,B[a]P）作用下人支气管上皮细胞（16HBE）DNA损伤与组蛋白H2A单泛素化表达水平的关系。[方法]取对数生长期16HBE细胞,采用2μmol/L B[a]P染毒不同时间（0、1、2、4、8、12、24、48h）进行实验,用碱性单细胞凝胶电泳实验检测细胞DNA损伤水平,并以Olive尾矩值（olivetail moments,OTM）评价DNA损伤程度;用Western-blot法检测组蛋白H2A单泛素化水平。[结果]单细胞凝胶电泳结果显示：2μmol/L B[a]P染毒不同时间时,随着染毒时间的延长,各染毒组细胞DNA损伤程度均明显增高,与对照组相比,差异均有统计学意义（P〈0.01）;Western-blot结果显示：2μmol/L B[a]P染毒不同时间时,与对照组相比,组蛋白H2A的单泛素化水平增高,且在染毒2h后,差异有统计学意义（P〈0.01）;回归分析显示,单泛素化H2A的表达水平与DNA损伤程度存在高度相关,决定系数（R2）为0.910,P〈0.01。[结论]B[a]P染毒致16HBE细胞DNA损伤与组蛋白H2A单泛素化水平之间存在密切关系。

Correlation between DNA Damage and Expression of Mono-ubiquitinated Histone H2A in 16HBE Cells Exposed to Benzo[a]pyrene

[Objective] To investigate the association between DNA damage and expression of mono-ubiquitinated histone H2A in human bronchial epithelial cells（16HBE） exposed to benzo[a]pyrene（B[a]P）.[Methods] The 16HBE cells collected at the logarithmic phase of growth were exposed to B[a]P at the concentration of 2 μmol/L for 0,1,2,4,8,12,24 and 48 h respectively.DNA damage was determined by comet assay and expressed as olive tail moments（OTM）.Protein expression was detected by Western-blot.[Results] The results of comet assay showed that the OTM values increased with exposure time and a significant increment was found as compared with the control group（P 0.01）.After exposed to 2 μmol/L B[a]P for 2 h,the mono-ubiquitination levels of histone H2A increased significantly when compared with the control group（P 0.01）.The regression analysis showed a significant correlation between OTM and the levels of mono-ubiquitinated histone H2A,and the determination coefficient was 0.910（P 0.01）.[Conclusion] The findings suggest a close correlation between DNA damage and the levels of mono-ubiquitinated histone H2A in 16HBE cells exposed to B[a]P.