CYTOLOGICAL CHARACTERIZATION OF CHINESE-HAMSTER OVARY X-RAY-SENSITIVE MUTANT-CELLS, XRS-5 AND XRS-6 .2. INDUCTION OF SISTER-CHROMATID EXCHANGES AND CHROMOSOMAL-ABERRATIONS BY X-RAYS AND UV-IRRADIATION AND THEIR MODULATION BY INHIBITORS OF POLY(ADP-RIBOSE) SYNTHETASE AND ALPHA-POLYMERASE
CYTOLOGICAL CHARACTERIZATION OF CHINESE-HAMSTER OVARY X-RAY-SENSITIVE MUTANT-CELLS, XRS-5 AND XRS-6 .2. INDUCTION OF SISTER-CHROMATID EXCHANGES AND CHROMOSOMAL-ABERRATIONS BY X-RAYS AND UV-IRRADIATION AND THEIR MODULATION BY INHIBITORS OF POLY(ADP-RIBOSE) SYNTHETASE AND ALPHA-POLYMERASE
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DOI：
10.1016/0027-5107(87)90030-3
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发表时间：
1987-03-01
期刊：
影响因子：
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通讯作者：
NATARAJAN, AT
中科院分区：
文献类型：
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作者：
DARROUDI, F;NATARAJAN, AT
本文研究了X射线和短波紫外线（UV）照射与DNA修复抑制剂3-氨基苯甲酰胺（3AB）、阿糖胞苷（ara-C）和阿非迪霉素（APC）联合作用对野生型CHO-KI和两种X射线敏感突变体xrs 5和xrs 6细胞的杀伤作用和对位点染色单体交换（SCE）的诱导作用。SCE的自发频率在突变体和野生型CHO-K1细胞中相似（8.4-10.3 SCE/细胞）。虽然已知X射线是SCE的不良诱导剂，但发现xrs 6细胞中SCE频率的剂量依赖性增加（在150 rad下加倍），而xrs 5细胞中SCE频率略有增加，野生型CHO-K1细胞中没有增加。聚ADP核糖合成酶抑制剂3AB能增加所有细胞SCE的自发频率。3AB不增强任何细胞系中X射线诱导的SCE频率。Ara-C，DNA聚合酶α的抑制剂，增加了所有细胞系中SCE的频率。在与X射线的联合处理中，ara-C对xrs 5和xrs 6细胞没有协同作用，但在用ara-C处理后的X射线照射的野生型CHO-K1细胞中SCE的频率增加。对于SCE的诱导频率，用X射线加阿糖胞苷处理的CHO-K1细胞表现得像单独用X射线处理的xrs 6细胞，这表明除了已知的DNA双链断裂（DSB）修复缺陷之外，xrs 6细胞中DNA碱基损伤修复可能存在缺陷。生存实验显示，与野生型CHO-K1细胞相比，xrs 5和xrs 6突变细胞对S期X射线的细胞杀伤作用具有更高的敏感性。突变体对阿糖胞苷和APC的杀伤敏感性低于CHO-K1细胞，对阿糖胞苷和APC的相对敏感性为CHO-K1 > xrs 5 > xrs 6细胞。当X射线照射与阿糖胞苷结合时，获得的存活结果与SCE试验的结果相似，即，与野生型CHO-K1不同，在xrs 5或xrs 6细胞中没有观察到协同效应。紫外线照射后，SCE的频率在野生型CHO-K1和xrs 6细胞中增加相似，但xrs 5细胞的SCE频率较低。当紫外线照射后用阿糖胞苷后处理时，在CHO-K1细胞中获得了协同效应，但在xrs 5或xrs 6细胞中没有。单独在G1期的UV增加了所有细胞系中染色单体型畸变的频率，但与野生型CHO-K1细胞相比，在突变体xrs 5和xrs 6中的反应更明显。紫外线通常不会诱导G1期染色体类型畸变。在CHO-K1（P < 0.01）和xrs 5（P < 0.01）中，阿糖胞苷与阿糖胞苷偶联可引起染色体畸变。0.05），但在XRS 6细胞中没有获得染色体型畸变的诱导。在此基础上，讨论了X射线或紫外线照射细胞引起SCE和染色体畸变的DNA损伤的机制。
The cell killing and induction of siter-chromatid exchanges (SCEs) by X-rays and short-wave ultraviolet (UV) irradiation in combination with inhibitors of DNA repair, 3-aminobenzamide (3AB), cytosine arabinoside (ara-C) or aphidicolin (APC) were studied in wild-type CHO-KI and two X-ray sensitive mutants, xrs 5 and xrs 6 cells. The spontaneous frequency of SCEs was similar in the mutants and the wild-type CHO-K1 cells (8.4-10.3 SCEs/cell). Though X-rays are known to be poor inducers of SCEs, a dose-dependent increase in the frequency of SCEs in xrs 6 cells (doubling at 150 rad) was found in comparison to a small increase in xrs 5 and no increase in wild-type CHO-K1 cells. 3AB, an inhibitor of poly(ADP-ribose) synthetase increased the spontaneous frequency of SCEs in all the cell types. 3AB did not potentiate the X-ray-induced frequency of SCEs in any of the cell lines. Ara-C, an inhibitor of DNA polymerase .alpha., increased the frequency of SCEs in all the cell lines. In combined treatment with X-rays, ara-C had no synergistic effect in xrs 5 and xrs 6 cells, but the frequency of SCEs increased in X-irradiated wild-type CHO-K1 cells post-treated with ara-C. For the induced frequency of SCEs, CHO-K1 cells treated with X-rays plus ara-C behaved like xrs 6 cells treated with X-rays alone, suggesting a possible defect in DNA base damage repair in xrs 6 cells, in addition to the known defective repair of DNA double-strand breaks (DSBs). Survival experiments revealed higher sensitivity of xrs 5 and xrs 6 mutant cells to the cell killing effect of X-rays in S-phase when compared to wild-type CHO-K1 cells. The mutants responded with lesser sensitivity to cell killing effect of ara-C and APC than CHO-K1 cells, the relative sensitivity to ara-C or APC being CHO-K1 > xrs 5 > xrs 6 cells. When X-irradiation was coupled with ara-C, the results obtained for survival were similar to those of the SCE test, i.e., unlike wild-type CHO-K1, no synergistic effect was observed in xrs 5 or xrs 6 cells. After UV-irradiation, the frequency of SCEs increased similarly in wild-type CHO-K1 and xrs 6 cells, but xrs 5 cells responded with lower frequency of SCEs. When UV-irradiation was followed by post-treatment with ara-C, a synergistic effect was obtained in CHO-K1 cells, but not in xrs 5 or xrs 6 cells. UV alone in G1-stage increased the frequencies of chromatid-type of aberrations in all cell lines, but the response was more pronounced in mutants xrs 5 and xrs 6 when compared to wild-type CHO-K1 cells. UV generally does not induce chromosome-type aberrations in G1. It induced chromosome-type aberrations when coupled with ara-C in CHO-K1 (P < 0.01) and in xrs 5 (P .ltoreq. 0.05), but no induction of chromosome-type aberrations was obtained in xrs 6 cells. On the basis of these findings, the mechanism of involvement of specific type of DNA lesion responsible for formation of SCE and chromosomal aberration in X- or UV-irradiated cells is discussed.