Heterozygous Disruption of the DNA Topoisomerase I Gene Confers Cellular Resistance to Camptothecin in Human Cells
Heterozygous Disruption of the DNA Topoisomerase I Gene Confers Cellular Resistance to Camptothecin in Human Cells
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DOI：
10.1248/bpb.32.724
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发表时间：
2009-04-01
影响因子：
2
通讯作者：
Adachi, Noritaka
中科院分区：
文献类型：
--
作者：
Toyoda, Eriko;Kurosawa, Aya;Adachi, Noritaka
DNA 拓扑异构酶 I (Top1) 是一种普遍存在的核酶，在转录或复制等各种细胞过程中发挥重要作用。针对 Top1 的药物（包括喜树碱及其衍生物）是临床上使用的最有效的抗癌药物之一。先前的工作表明Top1表达水平与喜树碱的细胞毒性相关，但迄今为止尚未在具有严格同基因遗传背景的人类细胞的背景下提供直接证据。在这项研究中，我们通过基因打靶对人类前 B 细胞系 Nalm-6 进行 Top1 基因 (TOP1) 的杂合破坏，该细胞系核型稳定且 p53 状态正常。我们表明，TOP1 基因的杂合性缺失确实赋予了细胞对喜树碱的抗性，其程度与在功能性 p53 蛋白缺失的情况下观察到的程度相当。其他靶向 DNA 拓扑异构酶 II 的药物并未观察到这种耐受性。我们的结果提供了直接证据，表明 Top1 水平降低的人类细胞比其他同基因细胞更能抵抗喜树碱的杀伤作用。
DNA topoisomerase I (Top1) is a ubiquitous nuclear enzyme that plays essential roles in various cellular processes, such as transcription or replication. Agents that target Top1, involving camptothecin and its derivatives, are among the most effective anticancer drugs used in the clinic. Previous work has suggested that the level of Top1 expression correlates with the cytotoxicity of camptothecin, but no direct evidence has been provided thus far in the context of human cells with a strictly isogenic genetic background. In this study, we perform heterozygous disruption of the Top1 gene (TOP1) by gene targeting in a human pre-B cell line, Nalm-6, which is karyotypically stable and normal for p53 status. We show that the heterozygous loss of the TOP1 gene does confer cellular resistance to camptothecin, to an extent comparable to that observed in the absence of functional p53 protein. Such a tolerance was not observed with other agents that target DNA topoisomerase II. Our results provide direct evidence that human cells with decreased Top1 levels are significantly more resistant to killing by camptothecin than are otherwise isogenic cells.