苯作业工人淋巴细胞p53相关基因mRNA表达水平分析

mRNA expression levels of p53 and DNA damage and repair genes in peripheral blood iymphocytes of benzene-exposed workers

目的了解苯环境作业工人外周血淋巴细胞中，经p53介导的DNA损伤修复路径相关基因表达水平。方法选择某喷涂厂直接接苯工人46人（直接接苯组）、间接接苯工人26人（间接接苯组）和无苯及其他毒物接触工人29人（对照组），应用SYBR GreenⅠ嵌合荧光法实时RT-PCR分析技术，检测外周血淋巴细胞p53及相关基因mRNA表达水平，比较对照组与作业组间P53及相关基因mRNA表达倍数差异。结果直接接苯组和间接接苯组p53、Ku80、Ape1和Mdm-2 mRNA表达水平与对照组比较，差异无统计学意义（P〉0．05）；p21有增高趋势，但差异无统计学意义（P〉0．05）。直接接苯组的Rad51、Bcl-2、Bax、Xpa和XpcmRNA表达水平下调、间接接苯组Rad51 mRNA表达下调，与对照组比较，差异有统计学意义（P〈0．05或P〈0．01）。直接接苯组的白细胞、血红蛋白和血小板分别为（4．93±1．27）×10^9／L、（123．97±11．80）g／L和（124．02±41．22）×10^9／L，间接接苯组血小板为（135．80±39．44）×10^9／L，均低于对照组，差异均有统计学意义（P〈0．05或P〈0．01）。结论长期慢性的低浓度苯接触可使工人淋巴细胞中p53介导的部分DNA损伤修复相关基因mRNA表达水平发生改变，直接接苯工人的外周血白细胞、血红蛋白、血小板减低以及Bcl-2、Bax、Xpa和XpcmRNA表达水平改变明显。

Objective To investigate the relationship between the mRNA expression levels of p53- mediating DNA damage and repair genes in the peripheral blood lymphocytes of workers and their exposures to benzene in their working environment. Methods The mRNA expression levels of p53 and related genes were determined by SYBR Green I chimeric fluorescence quantitative real-time RT-PCR analysis in peripheral blood lymphocytes of 72 workers, who were classified into group A （46 direct exposure to benzene） and group B （26 indirect exposure to benzene） based on their positions, and 29 controls. The differences of gene expression levels were analyzed by software REST 2005. Meanwhile,the peripheral blood leukocytes,hemoglobin and platelet of workers and controls were counted. Benzene content was measured in the samples of toluene, used as raw material,and spraying agents and benzene, toluene and xylene concentrations in the air of workplaces were monitored. Results There were no significant differences in the mRNA expression levels of p53, Ku80,Apel and Mdm-2 between group A or group B and control group （P〉0.05）. The expression uptrend of p21 mRNA was found,but without significant difference （P〉0.05）. However,the mRNA expression levels of Rad51, Bcl-2, Bax, Xpa and Xpc in group A and Rad51 in group B were downregulated significantly （P〈0.05 or P〈0.01 ）. Moreover, both the counts of white blood cell, hemoglobin and platelet in group A were （4.93 ± 1.27）×10^9/L, （ 123.97±11.80）g/L and （ 124.02±41.22）×10^9/L respectively and platelet in group B （ 135.80± 39.44）×10^9/L were significantly lower than in control group（P〈0.05 or P〈0.01 ）. Conclusion The mRNA expression levels of some p53-mediating DNA damage and repair genes are downregulated in the workers chronically exposed to low benzene concentration. The working environment impacts on health of group A workers are greater than the ones of group B.