Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
J Korean Med Sci. 2012 Jun;27(6):594-604. doi: 10.3346/jkms.2012.27.6.594. Epub 2012 May 26.
DNA methylation is one of the main epigenetic mechanisms and hypermethylation of CpG islands at tumor suppressor genes switches off these genes. To find novel DNA methylation markers in hepatocellular carcinoma (HCC), we performed pharmacological unmasking (treatment with 5-aza-2'-deoxycytidine or trichostatin A) followed by microarray analysis in HCC cell lines. Of the 239 promoter CpG island loci hypermethylated in HCC cell lines (as revealed by methylation-specific PCR), 221 loci were found to be hypermethylated in HCC or nonneoplastic liver tissues. Thirty-three loci showed a 20% higher methylation frequency in tumors than in adjacent nonneoplastic tissues. Correlation of individual cancer-related methylation markers with clinicopathological features of HCC patients (n = 95) revealed that the number of hypermethylated genes in HCC tumors was higher in older than in younger patients. Univariate and multivariate survival analysis revealed that the HIST1H2AE methylation status is closely correlated with the patient's overall survival (P = 0.022 and P = 0.010, respectively). In conclusion, we identified 221 novel DNA methylation markers for HCC. One promising prognostic marker, HIST1H2AE, should be further validated in the prognostication of HCC patients.
DNA 甲基化是主要的表观遗传机制之一，肿瘤抑制基因的 CpG 岛过度甲基化会导致这些基因失活。为了在肝细胞癌 (HCC) 中寻找新的 DNA 甲基化标志物，我们在 HCC 细胞系中进行了药物去甲基化（用 5-氮杂-2'-脱氧胞苷或曲古抑菌素 A 处理），然后进行微阵列分析。在 HCC 细胞系中（通过甲基化特异性 PCR 揭示），有 239 个启动子 CpG 岛位点呈高甲基化，其中 221 个在 HCC 或非肿瘤性肝组织中呈高甲基化。33 个位点在肿瘤中的甲基化频率比相邻非肿瘤组织高 20%。对 95 例 HCC 患者的临床病理特征与个别癌症相关的甲基化标志物的相关性分析表明，HCC 肿瘤中高甲基化基因的数量在老年患者中高于年轻患者。单因素和多因素生存分析表明，HIST1H2AE 的甲基化状态与患者的总生存率密切相关（P = 0.022 和 P = 0.010）。总之，我们鉴定了 221 个 HCC 的新型 DNA 甲基化标志物。一个有前途的预后标志物 HIST1H2AE 应该在 HCC 患者的预后判断中进一步验证。
