Complete inactivation of DNMT1 leads to mitotic catastrophe in human cancer cells
Complete inactivation of DNMT1 leads to mitotic catastrophe in human cancer cells
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DOI：
10.1038/ng1982
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发表时间：
2007-03-01
期刊：
影响因子：
30.8
通讯作者：
Li, En
中科院分区：
文献类型：
--
作者：
Chen, Taiping;Hevi, Sarah;Li, En
研究表明，DNA(胞嘧啶-5-)-甲基转移酶1(DNMT1)是维持CpG甲基化的主要酶，是小鼠胚胎发育和体细胞存活所必需的(1-3)。然而，DNMT1在人类癌细胞中的作用仍然存在很大争议(4-7)。利用同源重组，我们在人结直肠癌细胞系HCT116中产生了一个DNMT1条件等位基因，其中编码催化结构域的几个外显子两侧都有loxP位点。Cre重组酶介导的该等位基因的破坏导致基因组中类似于20%的CpG-CpG二联体的半甲基化，并激活了G2/M检查点，导致细胞周期的G2期停滞。尽管细胞逐渐摆脱这种停滞，但它们表现出严重的有丝分裂缺陷，并在有丝分裂期间或在四倍体G1状态停滞后经历细胞死亡。因此，我们的结果表明，DNMT1是维持人类癌细胞DNA甲基化模式所必需的，对癌细胞的增殖和生存是必不可少的。
Studies have shown that DNA (cytosine-5-)-methyltransferase 1 (DNMT1) is the principal enzyme responsible for maintaining CpG methylation and is required for embryonic development and survival of somatic cells in mice(1-3). The role of DNMT1 in human cancer cells, however, remains highly controversial(4-7). Using homologous recombination, here we have generated a DNMT1 conditional allele in the human colorectal carcinoma cell line HCT116 in which several exons encoding the catalytic domain are flanked by loxP sites. Cre recombinase-mediated disruption of this allele results in hemimethylation of similar to 20% of CpG-CpG dyads in the genome, coupled with activation of the G2/M checkpoint, leading to arrest in the G2 phase of the cell cycle. Although cells gradually escape from this arrest, they show severe mitotic defects and undergo cell death either during mitosis or after arresting in a tetraploid G1 state. Our results thus show that DNMT1 is required for faithfully maintaining DNA methylation patterns in human cancer cells and is essential for their proliferation and survival.