Molecular genetic and epigenetic analysis of NCX2/SLC8A2 at 19q13.3 in human gliomas
Molecular genetic and epigenetic analysis of NCX2/SLC8A2 at 19q13.3 in human gliomas
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DOI：
10.1111/j.1365-2990.2010.01070.x
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发表时间：
2010-04-01
影响因子：
5
通讯作者：
Nister, M.
中科院分区：
文献类型：
--
作者：
Qu, M.;Jiao, H.;Nister, M.
目的：19q13.3杂合性缺失是人类神经胶质瘤中常见的遗传变化，表明该染色体区域存在未知的神经胶质特异性肿瘤抑制基因。位于染色体19q13.32上的NCX 2/SLC 8A 2编码Na+/Ca 2+交换蛋白，其有助于细胞内Ca 2+稳态。它的表达仅限于脑，在其他正常组织和胶质瘤中均不存在任何显著水平。本研究的目的是探讨NCX 2是否可能是一个参与胶质瘤的肿瘤抑制基因。研究方法：我们对42例人脑胶质瘤中NCX 2基因进行了系统分析，使用微卫星分析评估19 q杂合性丢失，DNA测序和DNA甲基化分析。结果如下：除了三个已知的基因内单核苷酸多态性，rs 12459087，rs7259674和rs 8104926，没有NCX 2序列变异中检测到的任何肿瘤样本。此外，NCX 2的5'启动子区域中的CpG岛未甲基化。有趣的是，位于外显子2、内含子2-3和外显子3的三个基因体CpG岛的CpG位点以及与NCX 2的所谓CpG岛海岸相关的5'CpG富集区的CpG位点在所有8个胶质瘤样品和所测试的3个已建立的胶质瘤细胞系中被甲基化。令人惊讶的是，通过向其中NCX 2完全沉默的神经胶质瘤细胞系中加入DNA甲基化抑制剂5-氮杂-2 '-脱氧胞苷，NCX 2可以被激活。结论：DNA甲基化可能在NCX 2基因转录沉默中起重要作用。
Aim: Loss of heterozygosity at 19q13.3 is a common genetic change in human gliomas, indicating yet unknown glial-specific tumour suppressor genes in this chromosome region. NCX2/SLC8A2 located on chromosome 19q13.32 encodes a Na+/Ca2+ exchanger, which contributes to intracellular Ca2+ homeostasis. Its expression is restricted to brain, and it is present neither in other normal tissues nor in gliomas at any significant level. The aim of this study was to investigate if NCX2 might be a tumour suppressor gene involved in glioma. Methods: We performed a systematic analysis of NCX2 in 42 human gliomas using microsatellite analysis for evaluation of loss of heterozygosity at 19q, DNA sequencing and DNA methylation analysis. Results: Except for three known intragenic single nucleotide polymorphisms, rs12459087, rs7259674 and rs8104926, no NCX2 sequence variations were detected in any of the tumour samples. Furthermore, a CpG island in the 5' promoter region of NCX2 was unmethylated. Interestingly, the CpG sites of three gene-body CpG islands located in exon 2, intron 2-3 and exon 3 and of a 5' CpG-rich area relevant to so-called CpG island shore of NCX2 were methylated in all eight glioma samples and in three established glioma cell lines tested. Surprisingly, NCX2 could be activated by addition of the DNA methylation inhibitor 5-aza-2'-deoxycytidine to glioma cell lines in which NCX2 was completely silent. Conclusion: Results indicate that DNA methylation may play a key role in the transcriptional silencing of NCX2.