LyGDI在非小细胞肺癌细胞A549中的辐射抗性机制研究

Mechanism of the radioresistant effect of LyGDI on NSCLC A549 cells

目的 探讨LyGDI的表达在非小细胞肺癌细胞A549中的辐射抗性机制.方法 A549和作为对照的H460细胞分别受到0、2、4和6 GyX射线照射后,克隆形成试验分析辐射抗性差异,Western blot分析LyGDI和辐射敏感性关键基因环氧合酶COX-2的表达.实时荧光定量PCR分析miR-34a以及miR-34b/c在A549和H460细胞中的表达.A549细胞中转染50 nmol/L的miR-34c成熟序列,观察其对A549细胞辐射抗性以及LyGDI和COX-2基因表达的影响.结果 LyGDI和COX-2在辐射抗性的A549细胞中的表达水平高于H460细胞,miR-34a以及miR-34b/c在两种非小细胞肺癌中低表达.转染miR-34c可抑制LyGDI、COX-2和Bcl-2以及激活p21的表达,增强A549细胞细胞的辐射敏感性（t=3.85、5.89、5.12,P＜0.05）.结论 LyGDI诱导的COX-2的上调表达以及电离辐射效应miR-34家族的下调表达,是A549细胞辐射抗性的一个主要原因.

Objective To elucidate the mechanism of radiation resistant effect of LyGDI on NSCLC A549 cells.Methods A549 and H460 cells were irradiated with X-rays of 0,2,4 and 6 Gy.The clone-forming assay was used to detect cell survival and radiosensitivity.The expressions of LyGDI and COX-2 （Cyclooxygenase-2）,a key radiosensitivity-related protein,were detected using Western blot.The miR-34 families were analyzed with RT-PCR.50 nmol/L mature miR-34c was transfected into A549 cells.Results The expression levels of LyGDI and COX-2 were much higher in radioresistive A549 cells than that in H460 cells.While the expression of miR-34a was quite low and miR-34b/c was hardly found in both NSCLC cells.Transfection of miR-34c into A549 cells strongly enhanced X-ray induced apoptosis by inhibiting the activations of LyGDI,COX-2,Bcl-2 and p21.Conclusions Up-regulation of LyGDI could induce COX-2 expression.The low expression of miR-34 family might be responsible for the radiation resistance of NSCLC cells.