微小RNA-422a在胃癌组织中的表达及参与多柔比星耐药的机制研究

Expression of MicroRNA-422a in Gastric Cancer and Its Role in Doxorubicin Resistance

目的:研究微小RNA-422a(miR-422a)在胃癌组织中的表达及参与多柔比星耐药的机制研究。方法:检测46例胃癌及癌旁组织中miR-422a的表达水平,分析其与胃癌临床特征和预后的相关性。将miR-422a转染到SGC-7901/多柔比星细胞中,检测不同浓度多柔比星对SGC-7901细胞增殖的影响,计算耐药指数(RI),同时检测miR-422a和肌细胞增强因子2D(MEF2D)的表达以及细胞凋亡情况。结果:miR-422a在胃癌组织的表达水平显著低于癌旁组织(P<0.05);根据miR-422a的表达水平将患者分为高表达组和低表达组,发现miR-422a的表达水平在分化程度、淋巴结转移和TNM分期有显著差异(P<0.05或P<0.01);与预后良好组患者相比,预后不良组患者miR-422a表达显著降低(P<0.05);SGC-7901的半抑制浓度(IC50)为0.33μg·ml-1,SGC-7901/多柔比星的IC50为12.08μg·ml-1,RI为36.61;miR-422a mimic组的IC50为4.01μg·ml-1,RI为2.74;通过转染miR-422a mimic,miR-422a显著上调,同时抑制MEF2D,SGC-790/多柔比星细胞在多柔比星诱导的情况下细胞凋亡率显著升高(P<0.01)。结论:miR-422a在胃癌组织中低表达,并与胃癌患者预后不良密切相关,上调miR-422a水平可以增加SGC-7901对多柔比星的敏感性,这一发现可能为逆转肿瘤耐药性提供新的治疗靶点。

Objective: To investigate the expression of microRNA-422 a( miR-422 a) in gastric cancer and its role in doxorubicin resistance. Methods: The expression levels of miR-422 a in gastric cancer tissues and adjacent tissues of 46 patients were detected,and its correlation with clinical features and prognosis of gastric cancer was analyzed. And then miR-422 a was transfected into SGC-7901/doxorubicin cells,and the effects of doxorubicin at different concentrations on the proliferation of SGC-7901 cells were detected,meanwhile,the drug resistance index( RI),and the expressions of mir-422 a and MEF2 D,as well as the cell apoptosis were detected.Results: The relative median expression level of microRNA-422 a in gastric cancer tissues was significantly lower than that in the adjacent tissues( P < 0. 05). According to the expression level of microRNA-422 a,the patients were divided into high-expression group and low-expression group,and the expression of microRNA-422 a was significantly various in the differentiation degree,lymph node metastasis and TNM stage( P < 0. 05 or P < 0. 01). Compared with the patients with good prognosis,the expression of miR-422 a in the patients with poor prognosis was significantly lower( P < 0. 05). The IC50 of SGC-7901 was 0. 33 μg·ml-1,the IC50 of SGC-7901/doxorubicin was 12. 08 μg·ml-1 and RI was 36. 61;the IC50 of miR-422 a mimic group was 4. 01 μg·ml-1 and RI was 2. 74. After the transfection of miR-422 a mimic,miR-422 a in the miR-422 a mimic group was significantly up-regulated,MEF2 D was inhibited,and the apoptosis rate of SGC-790/doxorubicin cells induced by doxorubicin was significantly increased( P < 0. 01). Conclusion: The low expression of microRNA-422 a in gastric cancer tissues is closely related to the poor prognosis of gastric cancer patients. Up-regulation of microRNA-422 a level can increase the sensitivity of SGC-7901 to doxorubicin,which may provide a new therapeutic target for reversing drug resistance of gastric cancer.