Enhancer of zeste homologue 2 (EZH2) down-regulates RUNX3 by increasing histone H3 methylation.
Enhancer of zeste homologue 2 (EZH2) down-regulates RUNX3 by increasing histone H3 methylation.
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DOI：
10.1074/jbc.m800224200
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发表时间：
2008-06-20
期刊：
影响因子：
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通讯作者：
Ochiai A
中科院分区：
文献类型：
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作者：
Fujii S;Ito K;Ito Y;Ochiai A
zeste增强子同源物2（EZH 2）的过表达发生在各种恶性肿瘤中，并且与不良预后相关，特别是因为癌细胞增殖增加。在这项研究中，我们发现EZH 2和RUNX 3基因表达在五种癌细胞系，即胃癌，乳腺癌，前列腺癌，结肠癌和胰腺癌细胞系中呈负相关。染色质免疫沉淀分析显示，在癌细胞中，与RUNX 3基因启动子结合的EZH 2与赖氨酸27处的三甲基化组蛋白H3和与RUNX 3基因启动子结合的HDAC 1（组蛋白去乙酰化酶1）之间存在关联。RNA干扰介导的EZH 2敲低导致H3 K27三甲基化和未结合HDAC 1的减少以及RUNX 3基因表达的增加。RUNX 3表达的恢复与RUNX 3启动子区DNA甲基化状态的任何变化无关。RUNX 3被组蛋白去乙酰化和启动子区CpG岛的高甲基化所抑制，并被抑制素A或/和5-氮杂-2 ′-脱氧胞苷所恢复。免疫荧光染色证实了敲低EZH 2后RUNX 3蛋白表达的恢复，并且其恢复导致细胞增殖降低。在体内，在RUNX 3启动子区域没有DNA甲基化的情况下，在胃癌患者的个体细胞水平上观察到EZH 2和RUNX 3蛋白表达之间的反比关系。结果表明，RUNX 3是EZH 2抑制的靶标，并表明EZH 2过表达对癌细胞增殖的功能作用的潜在机制。
Overexpression of enhancer of zeste homologue 2 (EZH2) occurs in various malignancies and is associated with a poor prognosis, especially because of increased cancer cell proliferation. In this study we found an inverse correlation between EZH2 and RUNX3 gene expression in five cancer cell lines, i.e. gastric, breast, prostate, colon, and pancreatic cancer cell lines. Chromatin immunoprecipitation assay showed an association between EZH2 bound to the RUNX3 gene promoter, and trimethylated histone H3 at lysine 27, and HDAC1 (histone deacetylase 1) bound to the RUNX3 gene promoter in cancer cells. RNA interference-mediated knockdown of EZH2 resulted in a decrease in H3K27 trimethylation and unbound HDAC1 and an increase in expression of the RUNX3 gene. Restoration of RUNX3 expression was not associated with any change in DNA methylation status in the RUNX3 promoter region. RUNX3 was repressed by histone deacetylation and hypermethylation of a CpG island in the promoter region and restored by trichostatin A or/and 5-aza-2′-deoxycytidine. Immunofluorescence staining confirmed restoration of expression of the RUNX3 protein after knockdown of EZH2 and its restoration resulted in decreased cell proliferation. In vivo, an inverse relationship between expression of the EZH2 and RUNX3 proteins was observed at the individual cell level in gastric cancer patients in the absence of DNA methylation in the RUNX3 promoter region. The results showed that RUNX3 is a target for repression by EZH2 and indicated an underlying mechanism of the functional role of EZH2 overexpression on cancer cell proliferation.