MicroRNA-126通过靶向抑制EZH2增加胃癌SGC-7901细胞的放射敏感性

MicroRNA-126 enhances radiosensitivity of SGC-7901 cells via targeting inhibition of EZH2

目的:探讨微小RNA-126(miR-126)增强胃癌细胞放射敏感性的分子生物学机制。方法:体外培养胃癌SGC-7901细胞,通过转染miR-126模拟序列上调细胞内的miR-126水平,使用RT-q PCR及Western blot检测miR-126上调后zeste基因增强子同源物2(EZH2)的mRNA及蛋白水平的变化。双萤光素酶报告基因实验确认miR-126与EZH2的靶向结合关系。在上调miR-126水平的同时,通过共转染pc DNA3.1-EZH2真核表达质粒提高细胞内的EZH2表达,CCK-8法及流式细胞术分析照射后胃癌细胞的活力及凋亡率的变化,从而评估EZH2过表达对miR-126放射增敏作用的影响。结果:上调胃癌SGC-7901细胞中的miR-126水平可以显著抑制EZH2的mRNA及蛋白水平(P<0.05)。双萤光素酶报告基因实验提示miR-126与EZH2的mRNA间存在直接靶向关系。与仅上调miR-126的细胞相比,上调miR-126水平的同时过表达EZH2水平,将导致照射后SGC-7901细胞的活力增加,凋亡率减少(P<0.05)。结论:对EZH2靶向抑制是miR-126增强胃癌SGC-7901细胞放射敏感性的机制之一。

AIM： To investigate the molecular biological mechanisms by which microRNA-126（ miR-126） enhances the radiosensitivity of gastric cancer cells. METHODS： SGC-7901 cells were cultured in vitro. In order to over-express miR-126 in SGC-7901 cells,miR-126 mimic was transfected. The mRNA and protein levels of enhancer of zeste homolog 2（ EZH2） were detected by RT-q PCR and Western blot,respectively. The targeting relationship between miR-126 and EZH2 was determined by dual-luciferase reporter assay. To estimate the effect of EZH2 on miR-126-enhanced radiosensitivity of the SGC-7901 cells,the pc DNA3. 1-EZH2 vector was also co-transfected with miR-126 mimic,and then CCK-8 assay and flow cytometry were used to detect the viability and apoptotic rate of the cells after radiation. RESULTS： Overexpression of miR-126 significantly inhibited the expression of EZH2 in SGC-7901 cells both at protein and mRNA levels（ P〈0. 05）. A direct targeting relationship between miR-126 and EZH2 was confirmed by dual-luciferase reporter assay.Compared with the cells only transfected with miR-126 mimic,co-transfection of pc DNA3. 1-EZH2 with miR-126 mimic increased the viability but reduced the apoptosis of the cells treated by radiation（ P〈0. 05）. CONCLUSION： Targeting inhibition of EZH2 may be one of the mechanisms by which miR-126 enhances the radiosensitivity of gastric cancer cells.