Epigenetic profiling in chronic lymphocytic leukemia reveals novel methylation targets
Epigenetic profiling in chronic lymphocytic leukemia reveals novel methylation targets
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DOI：
10.1158/0008-5472.can-03-2870
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发表时间：
2004-04-01
期刊：
影响因子：
11.2
通讯作者：
Plass, C
中科院分区：
文献类型：
--
作者：
Rush, LJ;Raval, A;Plass, C
CpG岛甲基化是一种表观遗传学改变，通过基因的转录失活促进肿瘤发生。慢性淋巴细胞白血病（CLL）中CpG岛甲基化的总体水平知之甚少。为了提供总体异常甲基化的基线估计并鉴定用于额外研究的靶序列，我们对10个CLL样品进行了限制性标志基因组扫描。使用了两种甲基化敏感的标志性酶（NotI和AscI），允许评估每个样品中超过3000个CpG岛。将肿瘤来源的限制性标志基因组扫描图谱与来自正常志愿者的CD 19选择的B细胞和来自4名CLL患者的匹配的正常中性粒细胞的图谱进行比较。结果发现，CLL患者中2.5-8.1%（平均4.8%）的CpG岛发生了异常甲基化，且甲基化呈非随机分布（P < 0.0001）。此外，我们还鉴定了193个异常甲基化序列，其中93%具有CpG岛特征，90%与基因或表达序列具有同源性。一个这样的基因，G蛋白偶联代谢型谷氨酸受体7（GRM 7），可能抑制环AMP信号在诱导细胞凋亡。GRM 7的亚硫酸氢盐测序证实了广泛的CpG岛甲基化，并且用5-氮杂-2 '-脱氧胞苷（地西他滨）处理导致体外几种基因的表达上调，同时细胞消耗DNMT 1蛋白。我们的双酶全局甲基化研究表明，CLL的特征是与其他肿瘤相似的广泛的非随机CpG岛甲基化，并提供了一组新的甲基化靶点，可用于更大规模的研究，旨在评估对疾病进展和生存的影响。
CpG island methylation is an epigenetic alteration that contributes to tumorigenesis by transcriptional inactivation of genes. Little is known about the overall levels of CpG island methylation in chronic lymphocytic leukemia (CLL). To provide a baseline estimate of global aberrant methylation and identify target sequences for additional investigation, we performed Restriction Landmark Genomic Scanning on 10 CLL samples. Two methylation-sensitive landmark enzymes were used (NotI and AscI), allowing assessment of over 3000 CpG islands in each sample. Tumor-derived Restriction Landmark Genomic Scanning profiles were compared with profiles from CD19-selected B cells from normal volunteers and matched normal neutrophils from 4 CLL patients. We found 2.5-8.1% (mean 4.8%) of the CpG islands in CLL samples were aberrantly methylated compared with controls, and the methylation events had a nonrandom distribution (P < 0.0001). Furthermore, we identified 193 aberrantly methylated sequences, of which 93% have CpG island characteristics and 90% have homology to genes or expressed sequences. One such gene, the G protein-coupled metabotropic glutamate receptor 7 (GRM7), possibly inhibits cyclic AMP signaling in the induction of apoptosis. Bisulfite sequencing of GRM7 confirmed extensive CpG island methylation, and treatment with 5-aza-2'-deoxycytidine (decitabine) resulted in up-regulated expression of several genes in vitro with concurrent cellular depletion of DNMT1 protein. Our dual-enzyme global methylation study shows that CLL is characterized by widespread nonrandom CpG island methylation similar to other tumors and provides a panel of novel methylation targets that can be used in larger studies designed to assess impact on disease progression and survival.