TIG2基因在肺癌细胞中表达及启动子区甲基化的研究

Expression and promoter methylation of TIG2 gene in lung cancer cells

目的探讨TIG2基因在原发性非小细胞肺癌中的表达及意义。方法应用RT-PCR法检测TIG2基因在肺癌和正常肺细胞中表达变化,用CpG岛预测软件分析TIG2基因启动子和第一外显子区域CpG岛分布,用甲基化特异PCR法(MSP)检测TIG2基因甲基化。用RT-PCR法检测去甲基化试剂作用后TIG2基因的表达。结果正常肺细胞和癌旁正常组织中TIG2mRNA呈高表达,而肺癌细胞系和组织中低表达或沉默。TIG2基因的启动子和(或)第一外显子区域存在典型的CpG岛。在肺癌细胞系均发生TIG2甲基化,肺癌组织中常发生甲基化,而肺癌旁组织中未见甲基化。去甲基化试剂作用后TIG2基因恢复表达。5-氮-2′-脱氧胞苷浓度越高,TIG2mRNA表达的强度越大。结论甲基化是导致TIG2基因转录沉默的重要机制,TIG2可能是一种新的肺癌肿瘤抑制基因。

Objective To investigate the expression and promoter methylation of TIG2 genes in non - small cell lung cancer. Methods RT- PCR was used to examine the different expressions of TIC2 genes in lung cancer lines and normal lung cells, then different primers cound be designed using Methprime software. The effect of demethylating agent on TIG2 expression in lung cancer cells was assessed and the semi - quantitative RT - PCR method was used to assess the expression of TIG2 genes in three lung cell lines and clinical specimens. Results TIG2 gene was expressed in normal lung cells, but silenced in lung cancer cell lines and clinical specimens. Typical CpG islands were discoveried within promoter and first extron region of TIG2 gene. The promoter methylation status of TIG2 gene was examined , TIG2 gene was both unmethylated in normal lung cells and normal lung tissues,but was frequently methylated in lung cancer cells and lung cancer tissues. The TIG2 gene expression was restored in lung cancer cells by treatment with demethylating agent. Conclusions Methylation may be responsible for the decline of transcription of TIG2 gene and TIG2 gene might be a new gene of tumor suppressor.