PTEN再表达对细胞内抗氧化蛋白表达和DNA氧化损伤的影响

Effect of Reexpression of PTEN on Intracellular Expression of Antioxidant Defense Proteins and Oxidative DNA Damage

目的研究10号染色体缺失磷酸酶及张力蛋白同源体(Phosphatase and tensin homolog deleted on chromosome ten,PTEN)再表达对细胞内抗氧化蛋白Prdx1,2,5,6和Cu/Zn SOD的表达、活性氧(ROS)和DNA氧化损伤水平及细胞抗氧化能力的影响。方法采用Western blot法比较Pten-/-MEFs细胞(对照细胞)与PTEN再表达的Pten-/-MEFs细胞内抗氧化蛋白Prdx1,2,5,6和Cu/Zn SOD的表达差异;采用化学/荧光发光法分析对照细胞与PTEN再表达细胞内基础ROS水平差异;采用中性单细胞凝胶电泳比较不同浓度(0、0.01、0.05、0.10mmol/L)H2O2处理后,对照细胞与PTEN再表达细胞内DNA双链断裂(DSBs)的变化。结果与对照细胞相比,PTEN再表达细胞中Prdx1,2,5,6和Cu/Zn SOD蛋白的表达水平增高,细胞内基础ROS水平降低,DSBs减少,细胞抵抗外源性H2O2的能力增强。结论 PTEN可能通过对Prdx1,2,5,6和Cu/Zn SOD等抗氧化蛋白的表达调控,增强细胞抗氧化能力,清除细胞内过量的ROS,从而保护细胞免受氧化压力导致的DNA氧化损伤,维持基因组稳定性。

Objective To investigate the effect of reexpression of phosphatase and tensin homolog deleted on chromosome ten（PTEN）on the intracellular expression of antioxidant defense proteins Prdx1,2,5,6 and Cu/Zn SOD,the levels of reactive oxygen species（ROS）and oxidative DNA damage as well as cellular antioxidative ability.Methods The expression levels of Prdx1,2,5,6 and Cu/Zn SOD in the Pten-/-MEFs as control and the Pten-/-MEFs in which PTEN was re-expressed were compared by Western blot,while the basic ROS levels by fluorescence activated cell sorter（FACS）.The changes of double-strand breaks（DSBs）of DNAs in control cells and the Pten-/-MEFs in which PTEN was re-expressed,after treatment with hydrogen peroxide at various concentrations（0,0.01,0.05 and 0.10 mmol/L）,were compared by neutral single cell gel electrophoresis（SCGE）.Results Compared with those in Pten-/-MEFs as control,the expression levels of Prdx1,2,5,6 and Cu/Zn SOD in the Pten-/-MEFs in which PTEN was re-expressed increased,while the basic ROS level and DSBs decreased,however,the resistance to exogenous hydrogen peroxide increased.Conclusions PTEN might enhance the antioxidant ability of cells and remove the excessive ROS by regulating the expressions of antioxidant defense proteins such as Prdx1,2,5,6 and Cu/Zn SOD,thereby prevent the cells from the oxidative DNA damage caused by oxidizing pressure and maintain the stability of genome.