Yu Guolong, Zhang Xiangzhong, Wang Huaqiao, Rui Derong, Yin Aihua, Qiu Geng, He Yunshao
Department of Anatomy and Brain Research, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, P.R. China.
Oncol Rep. 2008 Nov;20(5):1061-7.
The epithelial cell adhesion molecule (EpCAM) gene has been found to be highly expressed in carcinomas of various origins; however, the molecular mechanisms underlying the transcriptional regulation of EpCAM remain poorly understood. The purpose of this experiment was to study the relationship between EpCAM gene overexpression and CpG island methylation status in the promoter region in cell cultures and normal colon epithelial and colorectal cancer tissues. Real-time quantitative PCR and bisulfite sequencing PCR were employed to detect EpCAM gene expression and to analyze the methylation status of the CpG islands. In addition, EpCAM gene expression and methylation status of CpG islands were studied in promoter methylation cell lines treated with a DNA methyltransferase inhibitor. It was found that most CpG dinucleotides were unmethylated in cell lines and cancer tissues where the EpCAM gene was highly expressed whereas most CpG dinucleotides were methylated in EpCAM gene unexpressed cell lines and normal colon tissues. When cells were treated with demethylating agent, CpG islands were demethylated, although EpCAM gene expression did not increase suggesting that unmethylation of the EpCAM promoter region was not responsible for EpCAM overexpression. The results of the study described herein suggest that unmethylation of the EpCAM promoter region was associated with EpCAM overexpression; however, it was not responsible for EpCAM overexpression by itself. Further research is required to determine which factors are responsible for EpCAM gene expression.
上皮细胞粘附分子（EpCAM）基因已被发现在各种起源的癌症中高表达；然而，EpCAM转录调控的分子机制仍知之甚少。本实验的目的是研究细胞培养物、正常结肠上皮组织和结直肠癌组织中EpCAM基因过表达与启动子区域CpG岛甲基化状态之间的关系。采用实时定量PCR和亚硫酸氢盐测序PCR检测EpCAM基因表达并分析CpG岛的甲基化状态。此外，还研究了用DNA甲基转移酶抑制剂处理的启动子甲基化细胞系中EpCAM基因表达和CpG岛甲基化状态。结果发现，在EpCAM基因高表达的细胞系和癌组织中，大多数CpG二核苷酸未甲基化，而在EpCAM基因未表达的细胞系和正常结肠组织中，大多数CpG二核苷酸甲基化。当细胞用去甲基化剂处理时，CpG岛去甲基化，尽管EpCAM基因表达并未增加，这表明EpCAM启动子区域的去甲基化与EpCAM过表达无关。本文所述研究结果表明，EpCAM启动子区域的去甲基化与EpCAM过表达有关；然而，其本身并非EpCAM过表达的原因。需要进一步研究以确定哪些因素负责EpCAM基因表达。
