Objective To study the methylation status of the promoter region of GPC5 and its significance in lung adenocarcino-ma. Methods The CpG island distribution of GPC5 promoter region was predicted online and the primers of methylation-specific polymer-ase chain reaction ( MSP ) were synthesized. The methyltransferase inhibitor 5-aza-2-deoxycytidine( 5-AZA ) induced the expression of GPC5 in lung adenocarcinoma cell line A549, SPC-A1 and immortalized bronchial epithelial ( HBE ) cells. The expression changes of GPC5 before and after 5-AZA induction were tested as well. Additionally, in 32 lung adenocarcinomas, the methylation status of promoter region of GPC5 was studied by MSP and mRNA expression levels were determined by reverse transcription polymerase chain reaction( RT-PCR ) assay. Results GPC5 did not express in normal bronchial epithelium while expressed significantly in lung adenocarcinoma cell lines. After 5-AZA induction, the expression levels were increased in both A549 and SPC-A1, suggesting the promoter region methylation of CpG island was involved in the regulation of GPC5 gene expression. But, the CpG island of GPC5 promoter region showed hypomethyla-tion in lung adenocarcinoma tissues, suggesting the hypomethylation may associate with the up regulation of GPC5 expression in lung adenocarcinoma. Conclusion The promoter methylation of GPC5 played a role in its expression regulation, which may be an important factor leading the upregulation of GPC5 expression in lung adenocarcinoma.%目的 研究启动子区域CpG岛的甲基化对肺腺癌细胞GPC5表达的调节作用.方法 在线预测GPC5启动子区域CpG岛的分布,合成甲基化特异性聚合酶链反应(Methylation specific polymerase chain reaction,MSP)引物,甲基化酶特异性抑制剂5-氮杂-2'-脱氧胞嘧啶核苷(5-AZA)处理肺腺癌细胞系A549、SPC-A1及永生化支气管上皮细胞HBE,检测处理前后GPC5表达的变化.同时用MSP方法检测肺腺癌组织标本中GPC5基因启动子区域CpG岛甲基化情况,以探讨其可能的临床意义.结果 GPC5在正常的支气管上皮中不表达,而在肺腺癌细胞系中均有明显表达.5-AZA处理后,GPC5在A549及SPC-A1中的表达均上调,提示启动子区域CpG岛的甲基化参与了GPC5基因表达的调节.但肺腺癌组织标本中GPC5基因启动子区域CpG岛呈现低甲基化状态,提示这种低甲基化状态参与了肺腺癌细胞中GPC5表达的上调.结论 GPC5基因启动子区域的甲基化参与了其表达的调控,可能是导致肺腺癌中GPC5上调的一个重要因素.
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