^(125)Ⅰ籽源持续照射对人肺癌细胞凋亡及DNA-PK蛋白表达的影响

Influence of ^(125)I Continuous Low Dose-rate Irradiation to Apoptosis and DNA-PK Expression of Human Lung Carcinoma Cell Lines

目的:探讨^(125)Ⅰ籽源低剂量率持续照射诱导人肺癌细胞凋亡以及对DNA依赖蛋白激酶复合物(DNA-PK)表达的影响。方法:选择A549和NCI-H446两种辐射敏感性不同的人肺癌细胞株,采用9粒^(125)I籽源组成的平面照射装置进行持续照射,吸收剂量为2Gy。应用流式细胞术检测细胞凋亡和细胞周期的变化,免疫组化方法检测DNA-PKcs蛋白表达。结果:^(125)Ⅰ籽源照射2Gy后,A549和NCI-H446细胞的凋亡率分别为(11.14±1.11)%和(25.27±5.65)%,分别是对照组的5倍和8倍左右,其中NCI-H446细胞的凋亡率较A549细胞显著升高(P<0.05),显示NCI-H446细胞更敏感。两种细胞的细胞周期均出现明显的G_2/M期阻滞(P<0.05)。A549细胞自身蛋白表达显著高于NCI-H446细胞(P<0.05)。结论:^(125)Ⅰ籽源低剂量率持续照射诱导肺癌细胞凋亡的效果与DNA-PK修复基因的状态和受照射后的变化密切相关。

Objective.. To investigate effect of ^125I continue low dose-rate irradiation in inducing apoptosis in human lung carcinoma and its influence on DNA dependent protein kinase complex. Methods：Two human lung carcinoma cell lines with different radiosensitivity （A549 and NCI H446） ware used in research. In a radiation device designed by ourselves, nine ^125I seeds were used to carry out low dose-rate irradiation. The final absorbed dose of cell plane was 2Gy. Immunocytochemistry was used to detect protein expression of DNA PKcs. FCM was used to detect apoptosis and cell cycle change. Results： After 2Gy low doserate irradiation, apoptosis rate of A549 and NCI- H446 was （11.14 ± 1.12）% and （25.27 ±5.65）%respectively, which was 5 times and 8 times higher than control group. Apoptosis rate of NCI-H446 is significantly higher than A549 （P〈0.05）, showing higher radiosensitivity of NCI-H446. G2/M phase block appear in both of the two cell lines. （P〈0.05）. Conclusion： Background expression of DNA-PKcs protein were significantly higher in A549 than in NCI-H446 cell line （P〈0.05）. The expression of DNA-PKcs before and after irradiation in both cell lines didn＇t change significantly.