Lee Hwan Seok, Kim Baek-Hee, Cho Nam-Yun, Yoo Eun Joo, Choi Minhee, Shin So-Hyun, Jang Ja-June, Suh Kyung-Suk, Kim Yong Sung, Kang Gyeong Hoon
Department of Pathology, Seoul National University College of Medicine, Seoul, Republic of Korea.
Clin Cancer Res. 2009 Feb 1;15(3):812-20. doi: 10.1158/1078-0432.CCR-08-0266.
This study aims to determine the relationship between CpG island DNA hypermethylation and global genomic DNA hypomethylation and their prognostic implications in hepatocellular carcinoma. The association of DNA methylation changes with clinicopathologic factors and the chronological ordering of DNA methylation changes along multistep hepatocarcinogenesis were also assessed.
Hepatocellular carcinoma (n = 20) and nonneoplastic liver samples (n = 72) were analyzed for their methylation status at 41 CpG island loci and 3 repetitive DNA elements (LINE-1, ALU, and SAT2) using MethyLight or combined bisulfite restriction analysis. After selection of 19 CpG island loci showing cancer-specific DNA methylation, another set of 99 hepatocellular carcinoma samples was analyzed for these loci.
The number of methylated genes in hepatocellular carcinoma was significantly higher in hepatocellular carcinoma patients with a cirrhotic liver than in hepatocellular carcinoma patients with a noncirrhotic liver (9.9 versus 7.0, P = 0.001). Hepatocellular carcinoma from female patients showed a higher number of methylated genes than hepatocellular carcinoma from male patients (11.2 versus 8.4, P = 0.006). The genes CRABP1 and SYK showed significant association between CpG island hypermethylation and patients' poor survival. SAT2 hypomethylation occurred earlier than LINE-1 or ALU hypomethylation along the multistep hepatocarcinogenesis. Depending on the type of CpG island locus, a direct, inverse, or no relationship between CpG island hypermethylation and repetitive DNA hypomethylation was observed in hepatocellular carcinomas.
The varying relationships between the hypermethylation of individual CpG island loci and the hypomethylation of repetitive elements suggests that they are not mechanically linked. SYK and CRABP1 hypermethylation may serve as useful tumor markers for prognostication of hepatocellular carcinoma patients.
本研究旨在确定CpG岛DNA高甲基化与全基因组DNA低甲基化之间的关系及其在肝细胞癌中的预后意义。还评估了DNA甲基化变化与临床病理因素的关联以及DNA甲基化变化在多步骤肝癌发生过程中的时间顺序。
使用甲基化荧光定量法或联合亚硫酸氢盐限制性分析，对20例肝细胞癌和72例非肿瘤性肝样本在41个CpG岛位点和3个重复DNA元件（LINE-1、ALU和SAT2）的甲基化状态进行分析。在选择出19个显示癌症特异性DNA甲基化的CpG岛位点后，对另外99例肝细胞癌样本进行这些位点的分析。
肝硬化肝细胞癌患者中甲基化基因的数量显著高于非肝硬化肝细胞癌患者（9.9对7.0，P = 0.001）。女性患者的肝细胞癌中甲基化基因数量高于男性患者的肝细胞癌（11.2对8.4，P = 0.006）。CRABP1和SYK基因显示CpG岛高甲基化与患者不良生存之间存在显著关联。在多步骤肝癌发生过程中，SAT2低甲基化比LINE-1或ALU低甲基化出现得更早。根据CpG岛位点的类型，在肝细胞癌中观察到CpG岛高甲基化与重复DNA低甲基化之间存在直接、反向或无关联。
单个CpG岛位点的高甲基化与重复元件的低甲基化之间的不同关系表明它们并非机械地联系在一起。SYK和CRABP1高甲基化可能作为肝细胞癌患者预后的有用肿瘤标志物。
