肺癌细胞A549和H460对137Cs γ射线辐射敏感性差异的研究

Difference of radiosensitivity for 137Cs γ-radiation between A549 and H460 lung cancer cell lines

目的 研究肺癌细胞A549和H460对137Cs γ射线的辐射敏感性差异及核因子E2相关因子2（Nrf2）蛋白含量的差异。方法 使用2、4、6 Gy 137Cs γ射线照射A549和H460细胞；1、2、4、6 Gy 137Cs γ射线照射H460细胞，用克隆形成法检测细胞增殖能力，单细胞凝胶电泳检测细胞DNA损伤修复情况，casp_1.2.3b1彗星分析软件分析olive尾距值和尾部DNA含量，蛋白质印迹法检测Nrf2蛋白表达量。克隆形成率、olive尾距值和尾部DNA含量采用独立样本t检验进行比较。结果 经2、4、6 Gy 137Cs γ射线照射后，肺癌A549细胞的克隆形成率分别为（73.78±14.69）%、（42.26±3.19）%、（17.50±2.18）%；H460细胞的克隆形成率分别为（56.38±6.28）%、（23.82±8.25）%、（4.66±0.87）%，肺癌A549细胞克隆形成率高于H460细胞，且差异均有统计学意义（t=7.99，P=0.015；t=6.75，P=0.019；t=12.03，P=0.005）。4 Gy照射后2 h，肺癌H460细胞的olive尾距值（1.27±0.05）和尾部DNA含量（4.51±0.19）%明显高于A549细胞[0.68±0.04、（2.12±0.14）%]，且差异均有统计学意义（t=8.69、10.30，均P〈0.05）。蛋白质印迹实验结果显示，肺癌A549比H460细胞系的Nrf2蛋白丰度高，照射后两种细胞中的Nrf2蛋白水平均升高，但肺癌A549细胞明显高于H460细胞。结论 肺癌A549细胞系对137Cs γ射线的辐射抗性强于H460细胞系，这种辐射抗性差异可能与两种细胞系内Nrf2蛋白的含量相关。

Objective This study aims to compare radiosensitivity to γ ray between A549 and H460 cells and explore the relationship between different radiosensitivities and Nrf2 expression. Methods A549 and H460 cells were exposed to 2, 4, and 6 Gy 137Cs γ ray, and H460 cells were exposed to 1, 2, 4, and 6 Gy 137Cs γ ray. Cell proliferation was assessed by clone formation assay. DNA damage was evaluated using comet assay. Nrf2 protein level was measured by Western blot analysis. Results Clone formation assay indicated that the clone formation rates of A549 cells were （73.78±14.69）%, （42.26±3.19）%, and （17.5±2.18）%, and those of H460 cells were （56.38±6.28）%, （23.82±8.25）%, and （4.66±0.87）% after exposure to 2, 4, and 6 Gy, respectively （t=7.99, P=0.015; t=6.75, P=0.019; t=12.03, P=0.005）. Lung cancer H460 cells possessed higher olive tail moments （1.27±0.05）, and tail DNA（4.51±0.19）% than A549 cells[0.68±0.04, （2.12±0.14）%] in the comet assay conducted 2 h after 4 Gy irradiation（t=8.69, 10.30, both P〈0.05）. The Western blot assay indicated that the Nrf2 protein level was higher in A549 cells than in H460 cells. Radiation might induce the increase in the Nrf2 protein level in A549 and H460 cells. Moreover, the Nrf2 protein level was higher in radioresistant H460R cells than in radiosensitive H460 cells. Conclusion A549 cells are more resistant to 137Cs γ ray than H460 cells, and different radiosensitivities may be related to Nrf2 protein level.