Epigenetic regulation of X-linked cancer/germline antigen genes by DNMT1 and DNMT3b
Epigenetic regulation of X-linked cancer/germline antigen genes by DNMT1 and DNMT3b
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DOI：
10.1038/sj.onc.1209678
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发表时间：
2006-11-01
期刊：
影响因子：
8
通讯作者：
Karpf, A. R.
中科院分区：
文献类型：
--
作者：
James, S. R.;Link, P. A.;Karpf, A. R.
我们以MAGE-A1、NY-ESO-1和XAGE-1为模型，研究了DNA甲基转移酶(DNMT)两种关键酶在X连锁肿瘤/生殖系(CG-X)抗原基因表观遗传调控中的作用。在HCT116细胞中，DNMT1基因敲除导致CG-X基因适度激活，Dnmt3b基因敲除影响很小，两种酶的双重敲除都能引起强烈的基因诱导。同样，双重DNMT基因敲除导致MAGE-A1和NY-ESO-1启动子显著的低甲基化，DNMT1基因敲除显示中度低甲基化，而Dnmt3b基因敲除仅引起轻微的甲基化变化。相反，单基因敲除细胞和双基因敲除细胞都显示出XAGE-1启动子的显著低甲基化。在HCT116细胞中靶向DNMT1的RNA干扰(RNAi)验证了使用基因敲除细胞所看到的结果；然而，在不同的结直肠癌细胞系中靶向DNMT1的RNAi显示DNMT1在其他类型的细胞中介导CG-X基因抑制和启动子甲基化方面具有更大的独立作用。值得注意的是，组蛋白H3莫迪。DNMT基因敲除后，CG-X启动子的阳离子模式发生了改变。DNMT1或Dnmt3b基因敲除降低了二甲基化赖氨酸-9(DME-H3K9)的水平，但对二甲基化赖氨酸-4(DME-H3K4)或乙酰化赖氨酸-9(Ac-H3-K9)的水平没有显著影响。相反，双重DNMT1/3b基因敲除降低了DIME-H3K9的水平，显著增加了CG-X基因座上的DIME-H3K4和Ac-H3K9的水平。综上所述，DNMT1和DNMT3b在人类癌细胞中对CG-X抗原基因的表观遗传调控中既具有冗余功能又具有独立功能。
We examined the function of two key DNA methyltransferase (DNMT) enzymes in epigenetic regulation of X-linked cancer/germline (CG-X) antigen genes in human cancer cells, using MAGE-A1, NY-ESO-1, and XAGE-1 as models. In HCT116 cells, genetic knockout of DNMT1 caused moderate activation of CG-X genes, DNMT3b knockout had a negligible effect, and double knockout of both enzymes caused robust gene induction. Similarly, dual DNMT knockout caused dramatic hypomethylation of the MAGE-A1 and NY-ESO-1 promoters, DNMT1 knockout showed moderate hypomethylation, and DNMT3b knockout elicited only slight methylation changes. In contrast, both single and double knockout cells showed significant hypomethylation of the XAGE-1 promoter. RNA interference (RNAi) targeting of DNMT1 in HCT116 cells validated the results seen using genetic knockout cells; however, RNAi targeting of DNMT1 in a different colorectal cancer cell line revealed a greater independent role for DNMT1 in mediating CG-X gene repression and promoter methylation in other cell types. Notably, the histone H3 modi. cation pattern at CG-X promoters was altered following DNMT knockout. DNMT1 or DNMT3b knockout reduced dimethylated lysine-9 (diMe-H3K9) levels, but did not significantly affect dimethylated lysine-4 (diMe-H3K4) or acetylated lysine-9 (Ac-H3-K9) levels. In contrast, dual DNMT1/3b knockout reduced the level of diMe-H3K9 and dramatically increased the levels of diMe-H3K4 and Ac-H3K9 at CG-X gene loci. In summary, DNMT1 and DNMT3b were found to perform both redundant and independent functions in epigenetic regulation of CG-X antigen genes in human cancer cells.