Reversal of p15/INK4b hypermethylation in AML1/ETO-positive and -negative myeloid leukemia cell lines
Reversal of p15/INK4b hypermethylation in AML1/ETO-positive and -negative myeloid leukemia cell lines
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DOI：
10.1016/j.leukres.2006.08.008
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发表时间：
2007-04-01
影响因子：
2.7
通讯作者：
Luebbert, Michael
中科院分区：
文献类型：
--
作者：
Berg, Tobias;Guo, Yalin;Luebbert, Michael
在体外和体内，髓系白血病和白血病前期细胞对低浓度DNA甲基转移酶(DNMT)抑制剂诱导的抗增殖和促凋亡作用表现出不同的敏感性。白血病细胞对5-氮杂胞苷和5-氮杂-2‘-脱氧胞苷(DAC)等氮杂核苷的不同敏感性的分子机制可能涉及AML1/ETO等特定融合蛋白的修饰作用。细胞周期蛋白依赖的激酶抑制剂p15/INK4b是AML和MDS中DNA去甲基化活性的一个潜在靶点，在这些疾病中，它经常被高甲基化沉默。为了研究髓系白血病细胞对DAC的敏感性，我们选择了p15/INK4b基因高度甲基化的髓系细胞系Kasumi-1(表达AML1/ETO)、KG-I和KG-1a(AML1/ETO阴性)。DAC可诱导Kasumi-1和KG-1细胞p15/INK4b区域去甲基化，但对KG-1a细胞影响不大。去甲基化与诱导p15/INK4b蛋白表达有关。DAC在Kasumi-1细胞中的生长抑制和促凋亡活性显著高于KG-1a细胞，并观察到细胞对全反式维甲酸和组蛋白脱乙酰酶(HDAC)抑制剂曲古抑素A的协同作用敏感。当AML1/ETO在AML1/ETO阴性的U-937细胞中有条件表达时，DAC诱导的生长抑制和凋亡增加。总之，髓系细胞中p15/INK4b的低甲基化和重新激活是与DAC诱导的生长停滞和凋亡相关的分子事件之一。进一步研究AML1/ETO作为髓系细胞表观类型和对DNMTs和HDACs抑制剂敏感性的修饰物似乎是有必要的。(C)2006爱思唯尔有限公司。保留所有权利。
In vitro and in vivo, myeloid leukemic and preleukemic cells exhibit variable sensitivity to the antiproliferative and proapoptotic effects induced already at low concentrations of DNA methyltransferase (DNMT) inhibitors. The molecular mechanisms underlying this variable sensitivity of leukemic blasts to azanucleosides such as 5-azacytidine and 5-aza-2'-deoxycytidine (DAC) may involve modifier effects of specific fusion proteins such as AML1/ETO. The cyclin-dependent kinase inhibitor p15/INK4b is one potential target of DNA demethylating activity in AML and MDS where it is frequently silenced by hypermethylation. To study sensitivity to DAC in myeloid leukemia cells, we chose the myeloid cell lines Kasumi-1 (expressing AML1/ETO), KG-I and KG-la (both AML1/ETO-negative) all of which a highly methylated p15/INK4b gene. Treatment with DAC resulted in dose-dependent regional demethylation of p15/INK4b in Kasumi-1 and KG-1, but only to a modest degree in KG-la cells. Demethylation was associated with induction of p15/INK4b protein expression. Growth-inhibitory and proapoptotic activity of DAC was significantly higher in Kasumi-1 than in KG-1a cells, and sensitization of cells to a cooperating effect of All-trans retinoic acid and of the histone deacetylase (HDAC) inhibitor Trichostatin A was observed. DAC-induced growth inhibition and apoptosis were enhanced when AML1/ETO was conditionally expressed in AML1/ETO-negative U-937 cells. In conclusion, hypomethylation and reactivation of p15/INK4b in myeloid cell lines are among the molecular events associated with DAC-induced growth arrest and apoptosis. Further studies of AML1/ETO as a modifier of the epigenotype and sensitivity of myeloid cells to inhibitors of DNMTs and HDACs appear warranted. (c) 2006 Elsevier Ltd. All rights reserved.