Frequent hypermethylation of CpG islands and loss of expression of the 14-3-3 σ gene in human hepatocellular carcinoma
Frequent hypermethylation of CpG islands and loss of expression of the 14-3-3 σ gene in human hepatocellular carcinoma
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DOI：
10.1038/sj.onc.1203898
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发表时间：
2000-11-02
期刊：
影响因子：
8
通讯作者：
Imai, K
中科院分区：
文献类型：
--
作者：
Iwata, N;Yamamoto, H;Imai, K
14-3-3sigma基因参与了P53对G2/M期细胞周期的抑制作用，最近在乳腺癌中发现CpG岛高甲基化导致14-3-3sigma基因频繁失活。为检测肝细胞癌组织中14-3-3sigma基因CpG岛的甲基化状态，采用亚硫酸氢钠修饰和荧光聚合酶链式反应-SSCP相结合的方法，用免疫组织化学方法检测了4例正常肝组织和19例癌旁肝组织中14-3-3sigma基因的甲基化状态。%(17/19)的肝细胞癌组织中检测到14-3-3sigma基因CpG岛高甲基化，而4例正常肝组织中均未检测到甲基化。免疫组织化学分析14例甲基化阳性的肝细胞癌标本均显示14-3-3 sigma表达缺失，而甲基化阴性的肝细胞癌标本均保留表达，且甲基化与表达缺失之间存在显著相关性。癌旁肝组织中甲基化水平较低(6/16在肝硬变组织中，1/3在慢性肝炎组织中)，但14-3-3sigma在所有组织中均有表达。在甲基化阳性的肝癌细胞系中，HLE，5-氮杂-2‘-脱氧胞苷(5-aza-2’-deoxcytidine，5-aza-DC)诱导的CpG岛去甲基化导致了14-3-3sigma基因的失活，高甲基化导致14-3-3sigma基因失活，导致14-3-3sigma基因的表达缺失，这是迄今为止报道的最常见的肝癌异常之一，提示它们在肝癌的发生和/或进展中起着至关重要的作用。
The 14-3-3 sigma gene has been implicated in G2/M cell cycle arrest by p53, Frequent inactivation of the 14-3-3 sigma gene by hypermethylation of CpG islands has recently been reported in human breast carcinoma. The aim of this study was to examine the methylation status of CpG islands of the 14-3-3 sigma gene in hepatocellular carcinoma (HCC), The methylation status of the 14-3-3 sigma gene was evaluated in four normal liver tissues and 19 paired specimens of carcinoma and adjacent non-tumorous liver tissues using bisulfite-single strand conformation polymorphism (bisulfite-SSCP), a combination of sodium bisulfite modification and fluorescence-based polymerase chain reaction (PCR)-SSCP, The 14-3-3 sigma protein expression was examined by immunohistochemical staining. Hypermethylation of CpG islands of the 14-3-3 sigma gene was detected in 89% (17/19) of the HCC tissues but not in any of the four normal liver tissues. All of the 14 methylation-positive HCC samples analysed by immunohistochemistry showed loss of 14-3-3 sigma expression, while both of the methylation-negative HCC samples retained the expression, and a significant correlation was found between methylation and loss of expression. Lower levels of methylation were detected in adjacent non-tumorous liver tissues (6/16 in cirrhotic tissues and 1/3 in chronic hepatitis tissues), but the 14-3-3 sigma expression was retained in all of these tissues. In a methylation-positive HCC cell line, HLE, 5-aza-2'-deoxycytidine (5-aza-dC)-induced demethylation of CpG islands led to reactivation of gene expression, indicating that hypermethylation plays a causal role in inactivation of the 14-3-3 sigma gene in HCC, Hypermethylation and the resulting loss of expression of the 14-3-3 sigma gene corresponds to one of the most common abnormalities reported to date in HCC, suggesting their crucial role in the development and/or progression of HCC.