INDUCTION AND REPAIR OF DNA DAMAGE IN NORMAL AND ATAXIATELANGIECTASIA SKIN FIBROBLASTS TREATED WITH NEOCARZINOSTATIN
INDUCTION AND REPAIR OF DNA DAMAGE IN NORMAL AND ATAXIATELANGIECTASIA SKIN FIBROBLASTS TREATED WITH NEOCARZINOSTATIN
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DOI：
10.1093/carcin/4.7.917
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发表时间：
1983-01-01
期刊：
影响因子：
4.7
通讯作者：
BECKER, Y
中科院分区：
文献类型：
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作者：
SHILOH, Y;VANDERSCHANS, GP;BECKER, Y
遗传性多系统疾病共济失调-毛细血管扩张症(A-T)患者的细胞对X射线、博莱霉素和新卡西汀(NCS)等DNA断裂剂的细胞毒作用高度敏感。这三种药物导致的特定DNA损伤的修复缺陷可能是这种超敏反应的基础。这种DNA损伤可能是某种类型的DNA链断裂。以前用X射线和博莱霉素进行的大多数实验都没有显示出在A-T细胞中DNA链断裂的重新连接方面有任何延迟。由于A-T纯合子和杂合子细胞对NCS特别敏感，我们用碱性或中性洗脱的敏感方法研究了NCS处理的A-T皮肤成纤维细胞株诱导和修复链断裂的时间过程。NCS诱导的单链和双链断裂均呈线性剂量效应。与正常细胞相比，A-T细胞对链断裂的初始程度没有反应。由于NCS在细胞中的快速作用，它是研究重新连接链断裂动力学的合适试剂；这种作用在2-4分钟内完成，通过监测链断裂的诱导、DNA合成的抑制和细胞存活的减少来研究。NCS处理后发现的链断裂再连接的时间过程与X射线照射后的非常相似：在单链和双链断裂的情况下，首先观察到快速连接阶段(T1/2[半衰期].apprx)。单链断裂为5分钟，双链断裂为20-25分钟)。随后是第二个缓慢的阶段，持续了几个小时。在正常和A-T细胞之间，没有检测到在治疗几个小时后重新连接的时间进程或未连接的断裂的比例方面的差异。
Cells from patients with the hereditary multisystem disorder ataxia-telangiectasia (A-T) are hypersensitive to the cytotoxic action of DNA-breaking agents, such as X-rays, bleomycin and neocarzinostatin (NCS). A defect in the repair of a certain DNA lesion induced by all 3 agents may underlie this hypersensitivity. This DNA lesion may be a certain type of DNA strand break. Most of the previous experiments done with X-rays and bleomycin failed to show any retardation in the rejoining of DNA strand breaks in A-T cells. Since both A-T homozygous and heterozygous cells are particularly hypersensitive to NCS, the time course of strand breakage induction and repair in A-T skin fibroblast strains treated with NCS was studied using the sensitive method of alkaline or neutral elution. A linear dose response was obtained for the induction by NCS of single-strand breaks and double-strand breaks. A-T cells did not respond with a higher initial extent of strand breakage compared with normal cells. NCS is an appropriate agent for studying the kinetics of rejoining strand breaks, due to its rapid action in the cells; this action, which is completed within 2-4 min, was studied by monitoring strand break induction, inhibition of DNA synthesis and decrease in cellular survival. The time course of strand break rejoining found after NCS treatment was very similar to that found following X-irradiation: with both single- and double-strand breaks, a rapid phase of rejoining was first noticed (t1/2 [half-time] .apprx. 5 min for single-strand breaks and 20-25 min for double-strand breaks). This was followed by a 2nd, slow phase that continued for several hours. No difference could be detected between normal and A-T cells with regard to the time course of rejoining or the fraction of non-rejoined breaks remaining several hours after treatment.