NR4A2基因及其选择性剪接异构体与胃癌发生及转移的关系

NR4A2 and its splicing variants contribute to tumorigenesis and metastasis of gastric cancer

目的:检测胃癌中NR4A2(又称Nurr1)基因的表达,从NR4A2调控机制出发寻找相关选择性剪接异构体,探讨其与胃癌发生和转移的关系。方法:通过选择性剪接数据库(ASD)预测NR4A2基因可能存在的选择性剪接异构体,半定量PCR检测NR4A2及异构体的表达,基因测序技术鉴定新的剪接异构体;实时定量PCR检测41例样本中NR4A2及剪接异构体的表达水平;免疫组织化学方法检测28例样本中NR4A2蛋白表达。结果:NR4A2基因在胃癌原位、癌旁、转移组织中均有表达,确定了2种剪接异构体NR4A2-Ⅰ和NR4A2-Ⅱ。实时定量PCR检测41例样本中NR4A2及2种异构体在癌旁组织表达水平高于原位癌(P=0.017,P=0.007,P=0.004);在肝转移灶中表达水平低于原位癌(P=0.001,P=0.018,P=0.016),差异有统计学意义。免疫组化检测发现癌旁组织中NR4A2表达阳性率高于原位癌及转移灶,但差异无统计学意义(P=0.672)。结论:胃癌原位、癌旁和转移组织中至少存在NR4A2基因的2种剪接模式;NR4A2及异构体的表达变化与胃癌发生和转移相关。

Objective：To investigate the expression of NR4A2（Nurr1） and its splicing variants in gastric cancer,and to evaluate their potential association with the pathogenesis and metastasis of gastric carcinoma.Methods：Alternative Splicing Database（ASD） was used to predict the possible splicing variants of NR4A2;they were identified by gene sequencing technique and their expression was detected by semi-quantitative PCR.The mRNA expression of NR4A2 and its splicing variants in tumor and their expression was detected by semi quantitative PCR. The mRNA expression of NR4A2 and its splicing variants in tumor and the corresponding adjacent-tumor tissues （n= 41） were determined by real-time PCR. Meanwhile,immunohistoehemisty was employed to examine the protein levels of NR4A2 in the tumor tissues （n=28）. Results： The expression of NR4A2 mRNA was observed in the primary tumor tissues, adjacent tumor tissues, and metastatic tissues. Two splicing variants of NR4A2 were discovered：NR4A2-I and NR4A2-H. The mRNA expression of NR4A2, NR4A2-I , and NR4A2-H in the adjacent-tumor tissue was significantly higher than that in the primary tumor tissue （P = 0. 017, P = 0. 007, and P = 0. 004）, and that in the hepatic metastatic tissue was significantly lower than that in the primary tumor tissue （P= 0. 001,P=0. 018,P= 0. 016）. Meanwhile,immunohistochemistry showed that the positive rate of NR4A2 protein was higher in adjacent-tumor tissue than that in both tumor tissues and metastatic tissues, but with no significant differences. Conclusion： At least there are 2 splicing variants of NR4A2 in the gastric tumor, adjacent-tumor, and metastatic tissues; NR4A2 and the novel splicing variants may contribute to the pathogenesis and metastasis of gastric malignancy.