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目的观察miR-18a对A549肺腺癌细胞放射敏感性的影响。方法 qRT-PCR检测2 Gy X线照射A549细胞后miR-18a的变化;将人工合成的miR-18a模拟物(mimics)转染A549细胞,测定不同剂量照射后A549细胞的克隆形成能力,描记细胞存活曲线,测算2 Gy时存活分数(SF2)等指标,判断miR-18a对A549细胞放射敏感性的影响;同时检测过表达miR-18a的A549细胞中共济失调-毛细血管扩张症突变基因(ataxia-telangiectasia mutated,ATM)蛋白,探讨miR-18a对A549细胞放射敏感性影响的分子机制。结果与照射前(1.00±0.04)相比,2 Gy剂量照射后A549细胞miR-18a水平[(0.18±0.04)～(0.31±0.09)]显著降低(P<0.05)。miR-18a过表达后A549细胞放射敏感性增强,miR-18a过表达组、空白对照组SF2分别为0.34,0.48;同时miR-18a过表达的A549细胞中ATM、磷酸化ATM(ATM phospho S1981)水平下降。结论 miR-18a上调A549细胞放疗敏感性,可能与miR-18a下调ATM有关。
Objective To observe the effect of miR-18a on radiosensitivity of A549 lung adenocarcinoma cells. Methods qRT-PCR was used to detect the changes of miR-18a after 2 Gy X-ray irradiation on A549 cells. A549 cells were transfected with synthetic mimics of miR-18a. The clonogenic capacity of A549 cells was measured after irradiation with different doses. Survival curve and the survival score (SF2) at 2 Gy were measured to determine the effect of miR-18a on the radiosensitivity of A549 cells. At the same time, the gene mutation of ataxia-telangiectasia in A549 cells overexpressing miR-18a ataxia-telangiectasia mutated (ATM) protein, to explore the molecular mechanism of miR-18a on the radiosensitivity of A549 cells. Results The level of miR-18a in A549 cells was significantly decreased compared with that before irradiation (1.00 ± 0.04) ([0.18 ± 0.04] -0.31 ± 0.09] (P <0.05). miR-18a overexpression A549 cells increased radiosensitivity, miR-18a overexpression group, the blank control group SF2 were 0.34,0.48; at the same time miR-18a overexpression of A549 cells ATM, phosphorylated ATM (ATM phospho S1981) Level down. Conclusion miR-18a up-regulates the radiosensitivity of A549 cells, which may be related to the down-regulation of ATM by miR-18a.