Cytotoxicity of cigarette smoke condensate is not due to DNA double strand breaks: Comparative studies using radiosensitive mutant and wild-type CHO cells.
Cytotoxicity of cigarette smoke condensate is not due to DNA double strand breaks: Comparative studies using radiosensitive mutant and wild-type CHO cells.
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香烟烟雾冷凝物的细胞毒性不是由于 DNA 双链断裂：使用放射敏感性突变体和野生型 CHO 细胞的比较研究。
DOI：
10.1080/09553000701481790
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发表时间：
2007
影响因子：
2.6
通讯作者：
Bedford,JoelS
中科院分区：
文献类型：
--
作者：
Kato,Takamitsu;Nagasawa,Hatsumi;Warner,Christy;Okayasu,Ryuichi;Bedford,JoelS
目的：确定无代谢激活的香烟烟雾凝聚物（CSC）是否在G1期诱导各种CHO细胞放射敏感突变体的DNA双链断裂（DSB），以及这些断裂是否在细胞杀伤方面表现出对CSC的侧枝超敏反应。材料与方法：我们用不同浓度的CSC处理野生型和DNA修复缺陷突变体CHO细胞的g1期培养物，并通过集落形成实验和恒场凝胶电泳诱导DNA双链断裂以及磷酸化组蛋白H2-A变体X （γ-H2AX）实验检测细胞存活率。结果：凝胶分析和γ-H2AX聚焦分析显示，与电离辐射（IR）暴露相比，CSC治疗后每个细胞的DSB水平显著减少，但仍可检测到，即使等量辐射暴露以低剂量率传递，与CSC治疗相同的8小时暴露。与野生型细胞相比，三种非同源末端连接（NHEJ）缺陷突变体对CSC均不敏感。相比之下，对几种碱基损伤和交联剂过敏的UV-1细胞对CSC的敏感性高于其他CHO细胞系。结论：CSC直接产生的DNA DSB不是其细胞毒性的主要原因。此外，本研究不排除其中一些病变可能继发导致DSB的可能性，例如可能发生在DNA复制受阻期间，其修复可能需要NHEJ以外的系统。
Purpose:To determine whether cigarette smoke condensate (CSC) without metabolic activation induces direct DNA double strand breaks (DSB) in the G1 phase of various radiosensitive mutants of CHO cells and whether these breaks display collateral hypersensitivity to CSC with respect to cell killing.Materials & methods:We treated the G1-phase cultures of wild-type and DNA repair deficient mutants of CHO cells with various concentrations of CSC and examined the cell survival by colony formation assay and the induction of DNA double strand breaks by constant field gel electrophoresis as well as the phophorylated histone H2-A variant X (γ-H2AX) assay.Results:Gel analysis and γ-H2AX focus assay showed significantly fewer, but still detectable levels of DSB per cell after CSC treatment compared to ionizing radiation (IR) exposures, even when equitoxic radiation exposures were delivered at a low dose rate over the same 8-hour exposure used for CSC treatments. None of the three non-homologous end joining (NHEJ) deficient mutants were remarkably hypersensitive to CSC compared to wild-type cells. In contrast, UV-1 cells that are hypersensitive to several base damage and cross-linking agents showed a higher sensitivity to CSC compared to the other CHO cell lines.Conclusions:DNA DSB produced directly by CSC are not principally responsible for its cytotoxicity. Further, the present study does not rule out the possibility that some of these lesions may secondarily result in DSB, such as may occur during impeded DNA replication and whose repair may require systems other than NHEJ.