The antineoplastic efficacy of the prodrug Cloretazine™ is produced by the synergistic interaction of carbamoylating and alkylating products of its activation
The antineoplastic efficacy of the prodrug Cloretazine™ is produced by the synergistic interaction of carbamoylating and alkylating products of its activation
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DOI：
10.3727/096504005776404553
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发表时间：
2005-01-01
影响因子：
3.1
通讯作者：
Sartorelli, AC
中科院分区：
文献类型：
--
作者：
Baumann, RP;Seow, HA;Sartorelli, AC
氯雷他嗪(TM){1,2-双(甲基磺酰基)-1-[(2-氯乙基)-2-(甲基氨基)羰基]肼； VNP40101M； 101M}）是一种磺酰肼前药，对移植的小鼠和人类肿瘤模型具有广谱抗肿瘤功效，并在针对复发或难治性急性髓性白血病的临床试验中显示出活性。该前药的碱催化激活产生两种不同的反应中间体：氯乙基化物质，其在鸟嘌呤残基的 O-6 位上与 DNA 共价相互作用，并发展成 G-C 链间交联，以及氨基甲酰化剂异氰酸甲酯。该实验室之前的研究结果提供了初步证据，表明异氰酸甲酯可以通过增强所产生的氯乙基化物质的细胞毒性来提高氯雷他嗪 (TM) 的功效。这种作用可能部分归因于 DNA 修复蛋白 O-6-烷基鸟嘌呤-DNA 烷基转移酶 (AGT) 的抑制；然而，缺乏 AGT 的细胞中的活性表明协同细胞毒性涉及其他作用。在此，我们证明O-6-苄基鸟嘌呤还可以与氯雷他嗪（TM）的烷基化成分产生协同细胞杀伤作用，但与异氰酸甲酯的不同之处在于，这种增强作用发生在含有AGT的细胞中，而不是在缺乏AGT的细胞中。 1,2-双(甲基磺酰基)-1[甲基氨基羰基]肼分解产生的异氰酸甲酯也可增强多种DNA交联剂的活性，同时仅与甲基化剂产生附加的细胞毒性。使用膜联蛋白作为细胞凋亡标记物的细胞计数研究表明，在中国仓鼠卵巢细胞和人类白血病细胞中，氯雷他嗪 (TM) 诱导的细胞凋亡主要是由生成的异氰酸甲酯引起的。旨在检测完整细胞中 DNA 交联的彗星测定表明，氯雷他嗪 (TM) 活化产生的氯乙基化物质产生 DNA 交联，同时产生的异氰酸甲酯增加了反应性氯乙基化物质产生的交联程度。这些发现进一步证明氯雷他嗪 (TM) 活化产生的异氰酸甲酯可能是该抗肿瘤药物产生细胞毒性的主要因素。
Cloretazine (TM) {1,2-bis(methylsulfonyl)-1-[(2-chloroethyl)-2-(methylamino)carbonyl]hydrazine; VNP40101M; 101M}) is a sulfonylhydrazine prodrug that possesses broad spectrum antitumor efficacy against transplanted murine and human tumor models and has shown activity in clinical trials against relapsed or refractory acute myeloid leukemia. Base catalyzed activation of this prodrug generates two different reactive intermediates: chloroethylating species that covalently interact with DNA at the O-6-poSition of guanine residues that progress to a G-C interstrand cross-link, and a carbamoylating agent, methyl isocyanate. Previous findings from this laboratory have provided initial evidence that methyl isocyanate can contribute to the efficacy of Cloretazinc (TM) by enhancing the cytotoxicity of the generated chloroethylating species. This action may be due in part to inhibition of the DNA repair protein O-6-alkylguanine-DNA alkyltransferase (AGT); however, activity in cells devoid of AGT indicates that other actions are involved in the synergistic cytotoxicity. Herein we demonstrate that O-6-benzylguanine can also produce synergistic cell kill with the alkylating component of Cloretazine (TM) but differs from methyl isocyanate in that the enhancement occurs in AGT-containing cells, but not in cells devoid of AGT. Methyl isocyanate generated by the decomposition of 1,2-bis(methylsulfonyl)-1[methylaminocarbonyl]hydrazine also acts to enhance the activity of a variety of DNA cross-linking agents, while only producing additive cytotoxicity with methylating agents. How cytometric studies using annexin as a marker for apoptosis indicate that in Chinese hamster ovary cells and in human leukemia cells Cloretazine (TM)-induced apoptosis is primarily caused by the generated methyl isocyanate. Comet assays designed to detect DNA cross-links in intact cells indicate that the chloroethylating species generated by the activation of Cloretazine (TM) produce DNA cross-links, with the co-generated methyl isocyanate increasing the degree of cross-linking produced by the reactive chloroethylating species. These findings provide further evidence that the methyl isocyanate produced by the activation of Cloretazine (TM) can be a major contributor to the cytotoxicity produced by this antineoplastic agent.