Inhibition of DNA methyltransferase and induction of Friend erythroleukemia cell differentiation by 5-azacytidine and 5-aza-2'-deoxycytidine.
Inhibition of DNA methyltransferase and induction of Friend erythroleukemia cell differentiation by 5-azacytidine and 5-aza-2'-deoxycytidine.
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DOI：
10.1016/s0021-9258(19)68144-5
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发表时间：
1982-02
期刊：
影响因子：
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通讯作者：
F. Creusot;G. Acs;J. Christman
中科院分区：
文献类型：
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作者：
F. Creusot;G. Acs;J. Christman
用抗白血病药物5-氮杂胞苷和5-氮杂-2 '-脱氧胞苷处理Friend红白血病细胞，导致DNA甲基转移酶活性迅速、时间依赖性和剂量依赖性降低，并合成明显甲基化不足的DNA。由于该DNA在体内至少部分甲基化，并作为体外甲基化的优良底物，类似物处理的细胞中DNA的低甲基化似乎是由于DNA甲基转移酶的丢失，而不是由于5-氮杂胞嘧啶取代的DNA固有地不能作为甲基受体。DNA合成的抑制剂阻断DNA甲基转移酶活性的丧失，而RNA合成的抑制剂则不能，这表明类似物必须掺入DNA中以介导它们对酶的作用，并且DNA中胞嘧啶的5-氮杂胞嘧啶的微小取代（约0.3%）足以使细胞中超过95%的酶失活。一些证据表明DNA修饰模式的变化与分化有关。在这方面，重要的是5-氮杂胞苷和5-氮杂-2 '-脱氧胞苷在它们影响DNA甲基转移酶活性的相同浓度范围内作为Friend红白血病细胞的红系分化的弱诱导剂。为了进行分化，必须将细胞从药物中清洗出来。不到24小时后，DNA甲基转移酶活性恢复正常水平，48小时内，从细胞中分离的DNA未检测到甲基化不足。这可能部分解释了为什么5-氮杂胞苷和5-氮杂-2 '-脱氧胞苷在不到15%的人群中诱导分化，尽管它们最初对DNA甲基化有深远的影响。
Treatment of Friend erythroleukemia cells with the antileukemic drugs 5-azacytidine and 5-aza-2'-deoxycytidine leads to rapid, time-dependent, and dose-dependent decrease of DNA methyltransferase activity and synthesis of markedly undermethylated DNA. Since this DNA is at least partially methylated in vivo and serves as an excellent substrate for methylation in vitro, hypomethylation of DNA in analog-treated cells appears to result from the loss of DNA methyltransferase, rather than from an inherent inability of 5-azacytosine- substituted DNA to serve as a methyl acceptor. Inhibition of DNA synthesis blocks the loss of DNA methyltransferase activity while inhibitors of RNA synthesis do not, suggesting that the analogs must be incorporated into DNA to mediate their effect on the enzyme, and that minor substitution of 5-azacytosine for cytosine in DNA (approximately 0.3%) suffices to inactivate more than 95% of the enzyme in the cell. Several lines of evidence link changes in the pattern of DNA modification with differentiation. In this regard, it is significant that 5-azacytidine and 5-aza-2'-deoxycytidine act as weak inducers of erythroid differentiation of Friend erythroleukemia cells in the same concentration range where they affect DNA methyltransferase activity. For differentiation to proceed, the cells must be washed free of the drugs. Less than 24 h later, normal levels of DNA methyltransferase activity are restored and within 48 h, DNA isolated from the cells is not detectably undermethylated. This may in part explain why 5-azacytidine and 5-aza-2'-deoxycytidine induce differentiation in less than 15% of the population despite their initial profound effect on DNA methylation.