Frequent epigenetic inactivation of the SLIT2 gene in gliomas
Frequent epigenetic inactivation of the SLIT2 gene in gliomas
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DOI：
10.1038/sj.onc.1206687
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发表时间：
2003-07-17
期刊：
影响因子：
8
通讯作者：
Latif, F
中科院分区：
文献类型：
--
作者：
Dallol, A;Krex, D;Latif, F
SLIT基因家族由大的细胞外基质分泌和膜相关糖蛋白组成。狭缝（Slit1-3）是排斥性引导受体（roho基因家族）的配体。在神经发育过程中，裂隙-机器人相互作用介导轴突和生长锥上的排斥信号。在最近的一份报告中，我们在体外实验中证明了人类SLIT2的启动子区CpG岛在肺、乳腺和结直肠肿瘤中经常被高甲基化，并且沉默的基因转录物抑制了恶性表型。在本报告中，我们在大量胶质瘤和胶质瘤细胞系中进行了SLIT2基因的表观遗传学、遗传学和表达分析。SLIT2的启动子区CpG岛在71%（5/7）的胶质瘤细胞系中被甲基化，在5个正常脑组织DNA样本中未被甲基化。胶质瘤细胞系中SLIT2启动子区域的高甲基化与表达缺失和去甲基化剂5-aza-2'-脱氧胞苷重新激活SLIT2基因表达相关。在原发性胶质瘤中，59%（37/63）的肿瘤发生了SLIT2甲基化。此外，定量实时RT-PCR证实，相对于未甲基化的肿瘤样本，甲基化胶质瘤中的SLIT2表达下调。杂合缺失分析显示，SLIT2甲基化胶质瘤在4p15.2位点保留了SLIT2基因100 kb内的微卫星标记的两个等位基因。SLIT2在胶质瘤细胞中大量甲基化的外源性表达减少了体外集落的形成。我们的数据表明，SLIT2在胶质瘤中经常因启动子区CpG岛超甲基化而失活，并且可能是位于4p15.2的胶质瘤肿瘤抑制基因（TSG）的良好候选者。此外，我们的数据表明，需要对癌症基因组和表观基因组进行详细分析，以确定参与胶质瘤发展的关键tsg。
The SLIT family of genes consists of large extracellular matrix-secreted and membrane-associated glycoproteins. The Slits (Slit1-3) are ligands for the repulsive guidance receptors, the roho gene family. The Slit-Robo interactions mediate the repulsive cues on axons and growth cones during neural development. In a recent report, we demonstrated that promoter region CpG island of human SLIT2 was frequently hypermethylated in lung, breast and colorectal tumours and the silenced gene transcript suppressed the malignant phenotype in in vitro assays. In this report we undertook epigenetic, genetic and expression analysis of SLIT2 gene in a large series of gliomas and glioma cell lines. Promoter region CpG island of SLIT2 was found to be methylated in 71% (5/7) of glioma cell lines and was unmethylated in five DNA samples from normal brain tissues. The hypermethylation of the SLIT2 promoter region in glioma cell lines correlated with loss of expression and treatment with the demethylating agent 5-aza-2'-deoxycytidine reactivated SLIT2 gene expression. In primary gliomas, SLIT2 was methylated in 59% (37/63) of tumours analysed. In addition, SLIT2 expression was downregulated in methylated gliomas relative to unmethylated tumour samples, as demonstrated by quantitative real-time RT-PCR. Loss of heterozygosity analysis revealed that SLIT2 methylated gliomas retained both alleles of a microsatellite marker within 100 kb of the SLIT2 gene at 4p15.2. Exogenous expression of SLIT2 in a glioma cell tine that was heavily methylated for SLIT2 decreased in vitro colony formation. Our data indicate that SLIT2 is frequently inactivated by promoter region CpG island hypermethylation in gliomas and may be a good candidate for a glioma tumour suppressor gene (TSG) located at 4p15.2. Furthermore, our data suggest that a detailed analysis of both the cancer genome and epigenome will be required to identify key TSGs involved in glioma development.