人脑胶质瘤CXCL12基因的甲基化分析研究

目的 检测胶质瘤CXCL12基因启动子区的甲基化状态及其mRNA表达水平,以及受体CXCR4、DNA甲基转移酶等基因的mRNA表达情况,分析甲基化在CXCL12/CXCR4生物轴参与胶质瘤恶性进展中的调控机制.方法 半定量RT-PCR和实时定量PCR检测CXCL12、CXCR4、DNMT1、DNMT3A和DNMT3B基闪在76例胶质瘤及10例正常脑组织中的表达情况;甲基化PCR检测CXCL12基因启动子区的甲基化状态.结果 (1)CXCR4 mRNA随胶质瘤恶性程度的增高而表达增加;(2)CXCL12基因在胶质瘤中的甲基化率为34.2%,甲基化率随胶质瘤恶性程度的增高而降低;(3)CXCL12基因的甲基化主要发生在低度恶性胶质瘤中,其甲基化状态与mRNA表达密切相关;(4)DNMT1、DNMT3A和DNMT3B在CXCL12基因甲基化胶质瘤中的表达明显高于未发生甲基化的胶质瘤.结论 CXCR4基因有望成为胶质瘤恶性程度的生物学标志;CXCL12基因启动子区的甲基化主要发生在低度恶性胶质瘤中,其CXCL12基因甲基化下调mRNA的表达;DNMT1、DNMT3A和DNMT3B的过表达可能参与CXCL12基因甲基化的调控.

The methylation analysis of CXCL12 gene in human glioma

Objective To detect the methylation status of CXCL12 gene and the mRNA expression of CXCL12, CXCR4 and DNA methyhransferases (DNMTs) in glioma, and to analyze the methylation regulation and mechanism of CXCL12/CXCR4 signaling axis in the malignant progress of glioma. Methods The mRNA expression of CXCL12, CXCR4, DNMT1, DNMT3A and DNMT3B was detected by the semi - quantitative RT - PCR and real - time PCR in 76 gliomas and 10 normal brain tissues. The methylation status of CXCL12 in glioma was also studied by the methylation specific PCR. Results ( 1 ) The mRNA expression of CXCR4 in glioma increased with WHO grades. (2) Methylation of CXCL12 was detected in 34. 2% ( 26/76 ) of gliomas, but the methylation rate decreased with WHO grades. ( 3 ) Epigenetic inactivation of CXCL12 mainly happened in low- grade gliomas, and the CXCL12 mRNA levels were closely related to its methylation status. (4) The expression levels of these three DNMT genes were significantly higher in the CXCL12 - methylated gliomas than in the CXCL12 - unmethylated ones. Conclusion The CXCR4 gene may be a marker of aggressive biological behavior of glioma. The CXCL12 promoter hypermethylation is detected mainly in low - grade gliomas. And the methylaiton of CXCL12 gene cause the down - regulation of its mRNA levels in low - grade gliomas. The high expressions of DNMT1、DNMT3A and DNMT3B may be the potential mechanism of CXCL12 methylation.