Identification of an epigenetically silenced gene, RFX1, in human glioma cells using restriction landmark genomic scanning
Identification of an epigenetically silenced gene, RFX1, in human glioma cells using restriction landmark genomic scanning
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DOI：
10.1038/sj.onc.1208058
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发表时间：
2004-10-14
期刊：
影响因子：
8
通讯作者：
Toda, M
中科院分区：
文献类型：
--
作者：
Ohashi, Y;Ueda, M;Toda, M
为了鉴定人脑胶质瘤中甲基化差异的CpG岛，我们用CpG甲基化敏感酶进行限制性标志基因组扫描。我们发现12个点，其强度完全丢失或降低，在两个人脑胶质瘤组织检查相比，在匹配的正常淋巴细胞，表明这些CpG岛在胶质瘤中的异常甲基化。RFX 1是与甲基化CpG岛相关的基因之一，其表达在人脑胶质瘤细胞系和组织中经常降低。我们还表明，位于RFX 1基因的第七内含子中的孤立的CpG岛具有增强子活性，并且在所有分析的胶质瘤组织和细胞系中被高甲基化，但在正常脑或淋巴细胞中没有。用去甲基化剂5-氮胞苷处理胶质瘤细胞，导致RFX 1的表达，表明RFX 1基因的沉默可能归因于其甲基化。RFX 1与原癌基因c-myc的转录下调有关。通过RFX 1基因的表达，胶质瘤细胞的细胞增殖活性被抑制。综上所述，这些结果表明，RFX 1基因可能是表观遗传沉默在人类胶质瘤和参与胶质瘤肿瘤的发生。
To identify the CpG islands differentially methylated in human glioma, we performed restriction landmark genomic scanning with a CpG methylation-sensitive enzyme. We found 12 spots, the intensity of which was entirely lost or decreased in both the human glioma tissues examined as compared with that in matched normal lymphocytes, indicating aberrant methylation of these CpG islands in gliomas. The expression of RFX1, one of the genes associated with the methylated CpG islands, was frequently decreased in human glioma cell lines and tissues. We also demonstrated that the isolated CpG island located in the seventh intron of the RFX1 gene had enhancer activity and was hypermethylated in all of the glioma tissues and cell lines analysed, but not in normal brains or lymphocytes. Treatment of glioma cells with a demethylating agent, 5-azacytidine, resulted in the expression of RFX1, indicating that the silencing of the RFX1 gene may be attributable to its methylation. RFX1 has been implicated in transcriptional downregulation of the proto-oncogene c-myc. By expression of the RFX1 gene, the cellular proliferative activity of glioma cells was suppressed. Taken together, these results suggest that the RFX1 gene may be epigenetically silenced in human gliomas and involved in glioma tumorigenesis.