背景与目的 已有的研究证明低氧可诱导肿瘤细胞自噬发生,自噬水平与肿瘤放疗敏感性相关,因而调控自噬信号通路是增强放疗敏感性极具潜力的治疗策略.本研究旨在探讨联合应用自噬抑制剂3-甲基腺嘌呤(3-methyladenine,3-MA)下调低氧环境中人肺腺癌A549细胞的自噬水平后对其放疗敏感性的影响.方法 实验设低氧对照组及低氧+3-MA(自噬抑制剂)组,分别采用电镜检测自噬体变化,Western blot检测自噬标记蛋白-微管相关蛋白1轻链3(microtubule-associated protein 1 light chain 3,LC3)蛋白表达,分析LC3Ⅱ/LC3Ⅰ比值变化随后每组再给予直线加速器(0Gy、2Gy、4Gy、6Gy、8Gy、10 Gy)照射后采用MTT法检测细胞增殖活性.结果 与低氧对照组相比,低氧+3-MA组自噬体数量、LC3Ⅱ/LC3Ⅰ比值均下降.给予照射后,与低氧对照组比较,低氧+3-MA组细胞增殖活性下降.结论 在低氧环境中,A549细胞保护性自噬增加,抑制自噬可增强A549细胞的放疗敏感性.%Background and objective It has been proven that cancer cell autophagy can be induced by hypoxia. In addition, autophagy was correlated with radiosensitivity. Thus, regulating the autophagy signaling pathway is a potential treatment strategy. The aim of this study is to investigate the effects of combined autophagy inhibitor 3-methyladenine (3-MA) on the radiosensitivity of human adenocarcinoma A549 cells in hypoxia condition. Methods A549 cells were cultured in hypoxia condition, and then divided into two groups: hypoxia group and 3-MA plus hypoxia group. Electronic microscopy was used to detect autophagosome levels at different time points. The expression of LC3 was examined by Western blot. The proliferation activity of A549 cells after radiotherapy (0 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy, and 10 Gy) was determined with an MTT assay. Results Autophagosome formation and the LC3II/LC3I ratio increased under hypoxic conditions. After treatment with the autophagy inhibitor 3-MA, the quantity of autophagosomes and the LC3II/LC3I ratio decreased. The proliferative activity of the cells in the 3-MA plus hypoxia group was remarkably lower than that in the hypoxia group after treatment with radiotherapy. Conclusion The level of protective autophagy of A549 cells increased in hypoxia condition; thus, inhibiting autophagy improves the radiosensitivity of A549 cells.
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