hOGG1基因低表达对氢醌的细胞毒性及遗传毒性的影响

目的 探讨hOGG1基因低表达对氢醌(HQ)的细胞毒性及遗传毒性的影响.方法 0、5、10、20、40、80μmol/L浓度的(HQ)染毒A549细胞和hOGG1基因低表达的A549-R细胞,噻唑蓝比色法检测2种细胞存活率,荧光法测定2种细胞内活性氧(ROS)含量,微核试验分析2种细胞染色体损伤,彗星试验观察细胞的DNA损伤和修复.结果 随着HQ染毒浓度的增加,2种细胞的存活率均下降,A549-R细胞和A549细胞IC50分别为160.49和228.42 μmol/L,且差异有统计学意义(P＜0.05).0、5、10、20、40、80 μmol/L HQ染毒组A549-R细胞ROS含量、微核率均明显高于A549细胞,差异有统计学意义(P＜0.05);各浓度HQ染毒组A549-R细胞拖尾率和Olive尾距(OTM)值均明显大于A549细胞,并有剂量-反应关系,差异有统计学意义(P＜0.05).hOGG1基因低表达的A549-R细胞比A549细胞对HQ引起的DNA损伤修复更慢,修复2.0 h后才出现拖尾率和OTM值的明显降低,3.0 h后仍未完全修复.结论 氧化损伤可能是HQ毒作用的机制之一,hOGG1基因低表达可增加A549-R细胞对HQ的敏感性.

Effect of down-regulated hOGG1 gene expression on cytotoxicity and genotoxicity of hydroquinone

Objective To explore the effects of down-regulated hOGG1 gene expression on cytotoxicity and genotoxicity of hydroquinone.Methods A549 cells and A549-R cells with down-regulated hOGG1 gene were treated with different concentrations of hydroquinone (0,5,10,20,40 and 80 μmol/L).The cellular sensitivity and contents of ROS were measured by MTT assay and fluorescence method,respectively.The chromosome damage was measured by micronucleus test.The DNA damage and repair were examined using comet assay in both cells.Results The cell viability decreased with increasing concentration of hydroquinone.The IC50 of hydroquinone was 160.49 and 228.42 μmol/L in hOGG1 deficient A549-R cell and in A549 cell respectively (P＜0.05).When the dose of hydroquinone reached 5 μmol/L and above,the contents of ROS and the rate of micronucleated ceils in A549-R cells were significantly higher than in A549(P＜0.05 ) cells.At the same time,the comet rate and OTM in A549-R cells were significantly higher compared with A549 cells at 5 μmol/L and above in a dose-response way(P＜0.05 ).Furthermore,in DNA repair assay,A549-R cells with down-regulated hOGG1 gene were more difficult to repair than A549 cells.In A549-R cells,the comet rate and OTM reduced significantly until after 2 h repair time and even after 3 h the DNA damage was not repaired completely.Conclusion Oxidative damage may be one of the toxicological mechanisms of hydroquinone,and hOGG1 deficiency could increase sensitivity of A549- R cells to hydroquinone.