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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 the effects of low doses of ~ (125) Ⅰ seeds on the apoptosis of human lung cancer cells and the expression of DNA-PK (DNA-PK). Methods: Two human lung cancer cell lines with different radiosensitivity of A549 and NCI-H446 were selected and irradiated continuously with a planar irradiation device consisting of 9 seeds to 125 I seeds, and the absorbed dose was 2Gy. The changes of apoptosis and cell cycle were detected by flow cytometry. The expression of DNA-PKcs protein was detected by immunohistochemistry. Results: The apoptosis rates of A549 and NCI-H446 cells were (11.14 ± 1.11)% and (25.27 ± 5.65)%, respectively, which were 5 times and 8 times that of the control group , And the apoptosis rate of NCI-H446 cells was significantly higher than that of A549 cells (P <0.05), which showed NCI-H446 cells were more sensitive. The cell cycle of both cells showed obvious G 2 / M arrest (P <0.05). A549 cell self-protein expression was significantly higher than NCI-H446 cells (P <0.05). CONCLUSION: The effect of continuous irradiation with ~ (125) Ⅰ seed at low dose on the apoptosis of lung cancer cells is closely related to the status of DNA-PK repair gene and the changes after irradiation.