Inhibitory mechanisms of heterocyclic carboxaldehyde thiosemicabazones for two forms of human ribonucleotide reductase
Inhibitory mechanisms of heterocyclic carboxaldehyde thiosemicabazones for two forms of human ribonucleotide reductase
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杂环甲醛缩氨基硫腙对两种形式人核糖核苷酸还原酶的抑制机制
DOI：
10.1016/j.bcp.2009.06.103
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发表时间：
2009-11-01
影响因子：
5.8
通讯作者：
Yen, Yun
中科院分区：
文献类型：
--
作者：
Zhu, Lijun;Zhou, Bingsen;Yen, Yun
两种形式的核糖核苷酸还原酶(RR)分别参与DNA复制和损伤修复，其中M1含有M2亚基，M1含有p53R2亚基。3-氨基吡啶-2-甲醛缩氨基硫脲(3AP)是杂环缩氨基硫脲(HCTS)的一种，是一种有效的RR抑制剂，用于癌症的临床试验。在本研究中，3AP及其7个衍生物对KB鼻咽癌细胞的抑制率是羟基脲的100-1000倍，并且对羟基脲和吉西他滨耐药的KB细胞具有完全的活性。两种重组受体的体外RR分析表明，8种重组受体均以剂量依赖的方式抑制这两种受体的活性，其抑制作用与抑制细胞增殖的作用一致。铁对化合物对RRS的行为有不同的影响。在没有铁的情况下，HCRs对p53R2-M1的选择性抑制比M2-M1更强，而铁的加入增加了它们的活性，但降低了它们对两种RRs的选择性。放射配基结合分析表明，[H-3]3AP直接与小亚基结合。电子顺磁共振测量表明，这些HCRs与亚铁产生了活性氧物种，从而猝灭了小亚基的二铁-酪氨酸自由基共因子，从而抑制了酶的活性。虽然ROS可能是导致HCRs活性的共同介质，但小亚基蛋白的不同特征可能与抑制的亚基选择性有关。更好地了解RR抑制的作用机制可能有助于设计新的有效和亚单位选择性的RR抑制剂用于癌症治疗。(C)2009 Elsevier Inc.保留所有权利。
Two forms of ribonucleotide reductase (RR), consisting of M1 with M2 subunits and M1 with p53R2 subunits, are involved in DNA replication and damage repair, respectively. 3-Aminopyridine-2-carboxaldehyde thiosemicarbazone (3AP), one of the heterocyclic carboxaldehyde thiosemicabazones (HCTs), is a potent RR inhibitor in clinical trial for cancer treatment. In this study, 3AP and its 7 derivatives showed 100-1000-fold higher inhibitory potency on KB nasopharyngeal carcinoma cells than hydroxyurea and were fully active against hydroxyurea- and gemcitabine-resistant KB cells. In vitro RR assays using two recombinant RRs showed that all 8 HCrs decreased the activity of both RRs in a dose-dependent manner and the efficiency was compatible with that on cell proliferation inhibition. Iron has different impact on the behavior of the compounds toward RRs. In the absence of iron, the HCrs showed more selective inhibition for p53R2-M1 than M2-M1, while addition of iron increased their activity but reduced their selectivity for two RRs. Radioligand binding assays showed that [H-3]3AP directly bounded to the small subunits. Electron paramagnetic resonance measurements demonstrated that these HCrs generated reactive oxygen species with ferrous iron, which quenched the diiron-tyrosyl radical co-factor of the small subunits and hence the enzyme activity. While the ROS may be a common mediator responsible for the potent activity of the HCrs, the different characteristics of the small subunit proteins are probably associated with the subunit-selectivity of inhibition. Better understanding of the mechanism of action of RR inhibition may improve design of new potent and subunit-selective RR inhibitors for cancer therapy. (C) 2009 Elsevier Inc. All rights reserved.