中文摘要：

目的：研究α粒子诱发永生化人支气管上皮细胞BEP2D恶性转化过程中细胞内主要抗氧化蛋白的表达和活性氧（ROS）水平以及DNA双链断裂水平的变化。方法：选择BEP2D细胞、RH22细胞和BERP35T-1细胞,采用Western blot检测细胞内抗氧化蛋白过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPXs）以及铜锌超氧化物歧化酶（Cu/Zn-SOD）和锰-SOD（Mn-SOD）的表达;采用SOD测定试剂盒检测细胞内总SOD（T-SOD）、Cu/Zn-SOD和Mn-SOD酶活力;荧光探针标记结合流式细胞仪检测细胞内基础H_2O_2和O_2~（？）水平;中性彗星电泳法检测细胞内DNA双链断裂水平。结果：与BEP2D细胞相比,RH22和BERP35T-1细胞内抗氧化蛋白CAT和GPX1表达下调（P〈0.05或P〈0.01）,GPX3、Cu/Zn-SOD和Mn-SOD表达增强（P〈0.05或P〈0.01）;且T-SOD、Cu/Zn-SOD和Mn-SOD活力均显著升高（P〈0.05或P〈0.01）。RH22和BERP35T-1细胞内基础O_2~（？）水平低于BEP2D细胞,基础H_2O_2和DNA双链断裂水平则高于BEP2D细胞（P〈0.05）。结论：细胞内氧化/抗氧化失衡形成氧化压力,促进DNA氧化损伤和基因组不稳定性,可能是α粒子诱发BEP2D细胞恶性转化的机制之一。

英文摘要：

OBJECTIVE：To study the variation of the levels of antioxidant proteins,active oxygen radicals and DNA double-strand breaks in the malignantly transformed human bronchial epithelial cell line BEP2D induced byα-particles. METHODS：Western blot was applied for the detection of the protein expressions of catalase （CAT）,glutathione peroxidase（GPXs）,Cu/Zn superoxide dismutase（Cu/Zn-SOD） and Mn superoxide dismutase（Mn-SOD） in BEP2D,RH22,and BERP35T-1 cells.SOD assay kit was employed to measure total SOD（T-SOD）,Cu/Zn-SOD and Mn-SOD enzyme activities in BEP2D,RH22 and BERP35T-1 cells.Using 2＇,7＇-dichlorofluorescein diacetate（DCHF-DA） and dihydroethidium（DHE）,the generation of H_2O_2 and superoxide anion（O2~-） in BEP2D,RH22 and BERP35T-1 cells was monitored by flow cytometry.Neutral single cell gel electrophoresis（SCGE） was used to compare the differences of the levels of DNA double-strand breaks in BEP2D,RH22 and BERP35T-1 cells. RESULTS：Compared to BEP2D cells,CAT and GPX1 were down-regulated,but GPX3,Cu/Zn-SOD and Mn-SOD were up-regulated at protein level in RH22 and BERP35T-1 cells（P〈0.05 or P〈0.01）.Corresponding to their protein expression levels,RH22 and BERP35T-1 showed increased T-SOD,Cu/Zn-SOD and Mn-SOD enzyme activities （P〈0.05 or P〈0.01）.Decreased basal level of O_2~-and increased basal levels of H2O2 and DNA double-strand breaks were observed in RH22 and BERP35T-1 cells compared to BEP2D cells（P〈0.05）.CONCLUSION： Oxidant/antioxidant imbalance promoting oxidative DNA damage which may result in genomic instability could contribute to the acceleration of cellular malignant transforming process in human bronchial epithelial cell line BEP2D induced byα-particles.