Global Alterations of DNA Methylation in Cholangiocarcinoma Target the Wnt Signaling Pathway
Global Alterations of DNA Methylation in Cholangiocarcinoma Target the Wnt Signaling Pathway
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DOI：
10.1002/hep.26721
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发表时间：
2014-02-01
期刊：
影响因子：
13.5
通讯作者：
Weichenhan, Dieter
中科院分区：
文献类型：
--
作者：
Goeppert, Benjamin;Konermann, Carolin;Weichenhan, Dieter
胆管癌（CC）发生的分子机制知之甚少。表观遗传学变化，如异常甲基化和随后的非典型基因表达是大多数人类癌症的特征。在CC中，迄今为止缺乏关于全球甲基化变化的数据。我们对人类CC中异常启动子甲基化进行了全基因组分析。我们分析了10个肝内和8个肝外CC相比，非肿瘤性胆道组织标本，使用甲基CpG免疫沉淀（MCIP）结合全基因组CpG岛阵列。通过定量质谱分析证实了DNA甲基化，并在使用5-氮杂-2脱氧胞苷（DAC）处理的两个CC细胞系的去甲基化实验中显示了启动子高甲基化的功能相关性。应用免疫组织化学染色技术对223例胆道癌组织芯片进行蛋白质水平的候选基因表达分析。差异甲基化的启动子相关区域是非随机分布的，并富集了参与癌症相关途径的基因，包括Wnt、转化生长因子β（TGF-β）和PI 3 K信号通路。在CC细胞系中，DAC给药后，参与Wnt信号传导的基因（如SOX 17、WNT 3A、DKK 2、SFRP 1、SFRP 2和SFRP 4）的沉默被逆转。与正常组织相比，候选蛋白SFRP 2在所有BTC亚型的肿瘤组织中显著下调。在BTC患者中，SFRP 2蛋白表达与pT状态呈显著负相关。结论：我们提供了一个全面的分析，以确定人类CC的全基因组甲基化景观。癌症相关信号通路的几个候选基因被鉴定，并且对所选择的Wnt通路基因的进一步分析证实了该通路在CC中的相关性。所提出的全球甲基化数据是未来研究胆管癌发生中表观遗传变化的基础。（肝病学2014;59：544-554）
The molecular mechanisms underlying the genesis of cholangiocarcinomas (CCs) are poorly understood. Epigenetic changes such as aberrant hypermethylation and subsequent atypical gene expression are characteristic features of most human cancers. In CC, data regarding global methylation changes are lacking so far. We performed a genome-wide analysis for aberrant promoter methylation in human CCs. We profiled 10 intrahepatic and 8 extrahepatic CCs in comparison to non-neoplastic biliary tissue specimens, using methyl-CpG immunoprecipitation (MCIp) combined with whole-genome CpG island arrays. DNA methylation was confirmed by quantitative mass spectrometric analysis and functional relevance of promoter hypermethylation was shown in demethylation experiments of two CC cell lines using 5-aza-2deoxycytidine (DAC) treatment. Immunohistochemical staining of tissue microarrays (TMAs) from 223 biliary tract cancers (BTCs) was used to analyze candidate gene expression at the protein level. Differentially methylated, promoter-associated regions were nonrandomly distributed and enriched for genes involved in cancer-related pathways including Wnt, transforming growth factor beta (TGF-), and PI3K signaling pathways. In CC cell lines, silencing of genes involved in Wnt signaling, such as SOX17, WNT3A, DKK2, SFRP1, SFRP2, and SFRP4 was reversed after DAC administration. Candidate protein SFRP2 was substantially down-regulated in neoplastic tissues of all BTC subtypes as compared to normal tissues. A significant inverse correlation of SFRP2 protein expression and pT status was found in BTC patients. Conclusion: We provide a comprehensive analysis to define the genome-wide methylation landscape of human CC. Several candidate genes of cancer-relevant signaling pathways were identified, and closer analysis of selected Wnt pathway genes confirmed the relevance of this pathway in CC. The presented global methylation data are the basis for future studies on epigenetic changes in cholangiocarcinogenesis. (Hepatology 2014;59:544-554)