胃癌中microRNA-218调控BMI1基因表达的作用及机制

目的  探讨胃癌中microRNA-218（miR-218）调控BMI1基因表达的作用及机制。方法  应用实时定量聚合酶链反应（real-time PCR）检测胃癌及癌旁组织中miR-218及BMI1基因的表达。将miR-218的前体（miR-218 precursor）转染胃癌BGC823细胞，Western blot检测BMI1蛋白的表达。应用荧光素酶实验分析miR-218是否与BMI1基因3’非翻译区（3’-UTR）结合。结果  RT-PCR结果显示，相对癌旁组织，胃癌组织中miR-218的表达下调显著，而BMI1在胃癌组织中的表达则呈现明显的上调，miR-218与BMI1在胃癌及癌旁组织中的表达均为明显的负相关。在转染miR-218 precursor的胃癌BGC823细胞中，BMI1的蛋白表达显著下调。荧光素酶实验结果证实miR-218能够特异性地结合BMI1基因的3’-UTR，并与其表达呈负相关。结论  miR-218与BMI1基因的表达异常与胃癌的发生相关，BMI1基因是miR-218的靶基因，miR-218在胃癌细胞中能够靶向沉默BMI1基因。

Effect and mechanism of microRNA-218 in regulation of BMI1 gene in gastric cancer

Objective To explore the mechanism of microRNA-218 (miR-218) in regulation of BMI1 gene in gastric cancer. Methods Quantitative real-time PCR was used to detect the expression of miR-218 and BMI1 mRNA in gastric cancer and adjacent tissues. Western blot was used to investigate BMI1 protein level and luciferase assay was used to verify the ability of miR-218 binding to BMI1 after miR-218 precursor transfected into gastric cancer BGC823 cells. Results Quantitative real-time PCR results showed that miR-218 was down-regulated and BMI1 was up-regulated in gastric cancer tissues compared to the adjacent tissues; in both tissues miR-218 and BMI1 expressions were negatively correlated. Western blot and luciferase assay revealed that miR-218 could negatively regulate BMI1 protein expression by binding to the 3''-UTR of BMI1 gene. Conclusions The abnormal expressions of miR-218 and BMI1 are involved in gastric carcinogenesis; and miR-218 could target and silence BMI1 gene expression in gastric cells.