hOGG1核酶介导的肺癌细胞对^60Co γ射线放射敏感性的研究  

Study on the radiosensitivity of lung cancer cells mediated by hOGG1 ribozyme

作　　者：刘芳[1] 吴媚[1] 张遵真[1] 

机构地区：[1]四川大学华西公共卫生学院环境卫生教研室,610041

出　　处：《中华放射医学与防护杂志》2010年第2期133-137,共5页Chinese Journal of Radiological Medicine and Protection

基　　金：国家自然科学基金（30571535,30872079）

摘　　要：目的观察^60Co γ射线对核酶诱导的hOGG1基因低表达的人肺腺癌A549细胞的损伤效应，探讨hOGGl低表达在增加肿瘤细胞放疗敏感性中的作用机制。方法以A549细胞、转染空质粒的A549-P细胞和转染hOGG1特异性锤头状核酶真核表达载体pcDNA3．1（＋）-RZ的A549-R细胞为研究对象，测定射线照射后3种细胞活性氧含量、细胞存活率、细胞染色体损伤及DNA损伤和修复的差异。结果A549、A549-P和A549-R3种细胞的存活率随^60Co γ射线照射剂量的增加而下降，存在较好的剂量一反应关系（r=-0．984、-0．978、-0．975，P〈0．05）。A549-R细胞的IC50（9．37±0．24）显著低于A549细胞（12．98±0．44），差异有统计学意义（t=-12．48，P〈0．05）。^60Co γ射线照射下细胞活性氧含量、微核形成率及DNA损伤均增加，在相同剂量下，A549-R细胞中活性氧含量和微核形成率均高于A549和A549-P细胞。此外，在相同照射剂量下，hOGG1缺陷的A549-R细胞的DNA损伤较A549和A549-P细胞严重，且损伤后更加不易修复。结论 ^60Co γ射线可以诱导A549、A549-P和A549-R3种试验细胞的活性氧增加，从而导致DNA和染色体损伤，最终使细胞存活率降低，且以hOGG1低表达的A549-R细胞更为明显，提示hOGG1基因的低表达可能增加肿瘤细胞对射线的敏感性。Objective To study the mechanism of hOGG1 clown-regulation mediated by hOGG1 ribozyme on increasing the radiosensitivity to tumor cells by observing the damage effects induced by ^60Co γ-rays on human lung cancer cell line. Methods Human lung adenocarcinoma A549 cells,A549-P cells transfected with empty pcDNA3.1 plasmid and A549-R cells transfected with pcDNA3. 1-RZ plasmid in which hOGG1 ribozyme was constructed previously were utilized as a model system. The three kinds of ceils were exposed to different doses of ^60Co γ-rays. The level of cellular reactive oxygen species （ROS） , the cell viability, the chromosome damage as well as DNA damage and repair were examined respectively. Results The cell viability decreased significantly among A549, A549-P and A549-R cells after exposure to ^60Co γ-rays with a dose-response relationship（r = - 0. 984, - 0. 978, - 0. 975, P 〈 0. 05） , and the IC50 in A549-R ceils （9.37 ± 0.24） was statistically lower than that in A549 cells（ 12.98 ± 0.44, t = -12.48, P 〈 0.05）. The ROS level, the rate of micronucleus formation and DNA damage in all three kinds of cells were enhanced after exposure to ^60Co γ- rays, in which A549-R cells presented the most remarkable effect compared with A549 and A549-P cells. Similarly, DNA damage in A549-R cells was also more severe and more difficult to be repaired than that in A549 and A549-P cells at the same dose. Conclusions ^60Co γ-rays can induce DNA and chromosome damage in A549 cells through the ROS accumulation, leading to the reduction of the cell viability. However, all effects detected were more remarkable in A549-R cells in which hOGG1 was down-regulated mediated by ribozyme, suggesting that the deficiency in hOGG1 might increase the radiosensivity in tumor cells. [ Key words ]

关 键 词：hOGG1基因 放射敏感性 辐射 核酶 

分 类 号：R734.2[医药卫生—肿瘤]