EXTL3 promoter methylation down-regulates EXTL3 and heparan sulphate expression in mucinous colorectal cancers
EXTL3 promoter methylation down-regulates EXTL3 and heparan sulphate expression in mucinous colorectal cancers
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DOI：
10.1002/path.2377
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发表时间：
2008-09-01
影响因子：
7.3
通讯作者：
Fujimori, T.
中科院分区：
文献类型：
--
作者：
Karibe, T.;Fukui, H.;Fujimori, T.
Exostoses like-3(EXTL3)是一种可能的肿瘤抑制基因，但其与结直肠癌的关系尚不清楚。我们研究了EXTL3启动子甲基化作为EXTL3调控机制的作用，并验证了EXTL3表达缺失与结直肠癌细胞黏液分化和糖蛋白表达改变有关的假说。用亚硫酸氢盐修饰后的甲基化特异性聚合酶链式反应分析大肠癌细胞系、原发癌组织及其相应的癌旁正常大肠黏膜组织中EXTL3基因启动子的甲基化状态。在11例粘液性癌中有7例(63.6%)检测到EXTL3启动子甲基化，而在26例非粘液性癌中均未检测到EXTL3启动子甲基化。EXTL3启动子甲基化也在3例粘液性结直肠癌患者的正常结肠黏膜中检测到，而在任何一例非粘液性结直肠癌患者的正常结肠黏膜中均未检测到。在粘液性结直肠癌病变中，EXTL3甲基化的存在与HS表达的部分缺失显著相关。粘液性结直肠癌细胞株Colo201和Colo205存在EXTL3启动子甲基化和EXTL3mRNA表达缺失。然而，5-氮杂-2‘-脱氧胞苷处理使EXTL3基因启动子去甲基化，并恢复其mRNA表达。此外，EXTL3-siRNA可抑制大肠癌细胞HS的基础表达。我们认为EXTL3启动子甲基化及其相关的EXTL3表达缺失与粘液性癌HS表达缺失有关。版权所有(C)2008年大不列颠和爱尔兰病理学会。作者：John Wiley&Sons，Ltd.
Exostoses like-3 (EXTL3) is a putative tumour suppressor gene but its involvement in colorectal cancer (CRC) is unclear. We have investigated the role of methylation of the EXTL3 promoter as a mechanism for EXTL3 regulation and tested the hypothesis that loss of EXTL3 expression is associated with mucinous differentiation and alteration of glycoprotein expression in CRC cells. The methylation status of the EXTL3 gene promoter was analysed by methylation-specific PCR following bisulphite modification in CRC cell lines and microdissected primary CRC tissues and their corresponding adjacent normal colorectal mucosa. EXTL3 promoter methylation was detected in seven of 11 mucinous CRCs (63.6%) but in none of 26 non-mucinous CRCs examined. EXTL3 promoter methylation was also detected in the normal colonic mucosa of three patients with mucinous CRC but not in the normal colonic mucosa of any patients with non-mucinous CRC. The presence of EXTL3 methylation was significantly associated with the partial loss of HS expression in mucinous CRC lesions. The mucinous CRC cell lines, Colo201 and Colo205, showed EXTL3 promoter methylation and loss of EXTL3 mRNA expression. However 5-aza-2'-deoxycytidine treatment demethylated the EXTL3 gene promoter and restored its mRNA expression. Furthermore, the basal expression of HS in CRC cells was abolished by treatment with EXTL3-siRNA. We conclude that EXTL3 promoter methylation and its related loss of EXTL3 expression are involved in the loss of HS expression in mucinous CRCs. Copyright (C) 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.