5-Aza-2'-deoxycytidine induces p21WAF expression by demethylation of p73 leading to p53-independent apoptosis in myeloid leukemia
5-Aza-2'-deoxycytidine induces p21WAF expression by demethylation of p73 leading to p53-independent apoptosis in myeloid leukemia
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DOI：
10.1002/ijc.20797
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发表时间：
2005-05-01
影响因子：
6.4
通讯作者：
Tamm, I
中科院分区：
文献类型：
--
作者：
Schmelz, K;Wagner, M;Tamm, I
DNA甲基化抑制剂5-氮杂-2 ′-脱氧胞苷（5-Aza-CdR）对骨髓增生异常综合征（MDS）、急性髓细胞白血病（AML）和慢性髓细胞白血病（CML）的治疗具有重要价值。5-Aza-CdR的脱甲基作用已被很好地表征。相反，对甲基化抑制下游的分子事件知之甚少。在这里，5-Aza-CdR诱导AML细胞（p53突变体和野生型）的凋亡，但不是在上皮或正常的PBMC。细胞死亡伴随着线粒体凋亡途径的激活，如细胞色素c和AIF的释放以及线粒体膜电位（Deltapsim）的丧失所示。使用蛋白质印迹分析和半胱天冬酶酶活性的测量可检测到半胱天冬酶-3（而非-6和-8）的活化。5-Aza-CdR处理导致p21的诱导，这与AML细胞在G1细胞周期期的停滞相关。诱导p21的表达是独立的启动子甲基化状态，但介导的5-氮杂-CdR诱导的肿瘤抑制基因p73，一个已知的上游调节p21的再表达。p73启动子在AML细胞系和原代AML细胞中高甲基化，但在对5-Aza-CdR耐药的上皮细胞中没有。因此，5-Aza-CdR介导的髓系细胞特异性杀伤可能依赖于其逆转p73启动子甲基化和重新表达p73 mRNA的能力。此外，外源性表达p73使上皮细胞对5-Aza-CdR或其他细胞生长抑制药物诱导的凋亡敏感。因此，我们得出结论，p73是AML细胞中5-Aza-CdR甲基化依赖性功效的相关靶点。(C)2004 Wiley-Liss，Inc.
The DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR) has significant therapeutic value for the treatment of patients with myelodysplastic syndrome (MDS), acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). The demethylating effect of 5-Aza-CdR has been well characterized. In contrast, less is known about the molecular events downstream of the methylation inhibition. Here, 5-Aza-CdR induced apoptosis in AML cells (both p53 mutant and wild-type) but not in epithelial or normal PBMCs. Cell death was accompanied by activation of the mitochondrial apoptosis pathway, as shown by release of cytochrome c and AIF and loss of mitochondrial membrane potential (Deltapsim). Activation of caspase-3 (but not -6 and -8) was detectable using Western blot analysis and measurement of caspase enzymatic activity. 5-Aza-CdR treatment resulted in the induction of p21, which correlated with the arrest of AML cells in the G, cell cycle phase. Induction of p21 expression was independent of its promoter methylation status but mediated by 5-Aza-CdR-induced reexpression of the tumor-suppressor p73, a known upstream regulator of p21. The p73 promoter was hypermethylated in AML cell lines and in primary AML cells but not in epithelial cells, which were resistant toward 5-Aza-CdR. Therefore, 5-Aza-CdR-mediated specific killing of myeloid cells might be dependent on its ability to revert p73 promoter methylation and to reexpress p73 mRNA. In addition, exogenous expression of p73 rendered epithelial cells sensitive to apoptosis induced by 5-Aza-CdR or other cytostatic drugs. We therefore conclude that p73 is a relevant target for methylation-dependent efficacy of 5-Aza-CdR in AML cells. (C) 2004 Wiley-Liss, Inc.