苯并芘作用下人支气管上皮细胞切除修复交叉互补蛋白Ⅰ表达的变化

Dynamic changes of nucleotide excision repair proteins expression and their correlations with levels of DNA damage in human bronchial epithelia cells exposed to benzo(a)pyrene

目的探讨苯并芘（BaP）作用下的人支气管上皮细胞（16HBE）核苷酸切除修复蛋白（Nucleotide excisionrepair proteins,NER proteins）表达和DNA损伤的时间效应特征,并分析二者之间可能存在的关联性。方法用8μmol/LBaP染毒16HBE细胞0、1、2、4、8、12、24和48 h,以彗星实验检测细胞DNA损伤并以Olive尾矩值（Olive Tail Moments,OTM）评价DNA损伤程度。以Western-blot检测核苷酸切除修复蛋白XPA、XPC、XPF、XPG和ERCC1的表达水平。结果染毒1~2 h时OTM值变化率最大,与正常细胞相比,除染毒1h组外其余各组OTM值均显著性增高（P〈0.01）。各蛋白的表达于染毒8h或12 h升高至峰值而后逐渐下降,其中切除修复交叉互补蛋白1（ERCC1）在峰值时蛋白表达量增高4.2倍,等级相关分析显示OTM与ERCC1表达的变化率呈显著正相关（r=0.892,P〈0.001）。结论ERCC1可能是核苷酸切除修复途径中的限速因子,其具体机制有待于进一步研究。

Objective To investigate the dynamic changes in levels of DNA damage and their correlations with levels of NER proteins in cells exposed to BaP. Methods The human bronchial epithelial cells were exposed to 8μmol/L BaP for 0, 1, 1, 2, 4, 8, 12, 24 and 48 hours. The levels of DNA damage were evaluated by the Olive Tail Moments （OTM）. The levels of protein expressions were detected by Western-blot. Results The OTM dramatically increased from 1 to 2 h, and then located platform period at durations ranging from 2 to 8 h. The extent of DNA damage gently increased from 8 to 48 h. The levels of these NER proteins significantly increased and peaked at 8^th or 12^th hours in cells exposed to 8 μmol/L RaP. ERCC1 expression increased by 4.2-fold for exposure group at 12^th hours, compared with control group. In addition, there was a significant positive correlation between Olive tail moments and relative ratios of ERCC1 in cells exposed to BaP（ r = 0.892, P 〈 0.001）. Conclusion Our results suggested ERCC1 may be an important limiting factor for NER, but the mechanism underlying this observation needs further investigation.