γ-ray and hydrogen peroxide induction of gene amplification in hamster cells deficient in DNA double strand break repair
γ-ray and hydrogen peroxide induction of gene amplification in hamster cells deficient in DNA double strand break repair
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DOI：
10.1016/s1568-7864(02)00035-6
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发表时间：
2002-06-21
期刊：
影响因子：
3.8
通讯作者：
Nuzzo, F
中科院分区：
文献类型：
--
作者：
Mondello, C;Guasconi, V;Nuzzo, F
为了研究 DNA 双链断裂 (DSB) 及其修复在基因扩增中的作用，我们分析了暴露于伽马射线和过氧化氢 (H2O2) 后的 V3 中国仓鼠细胞系和亲本系 AA8 中的这一过程。 V3 在 DSB 修复中存在缺陷，因为 DNA 依赖性蛋白激酶催化亚基 (DNA-PKcs) 基因发生突变，该基因参与非同源末端连接途径。作为基因扩增的测量，我们使用对 N-(膦乙酰基)-L-天冬氨酸 (PALA) 抗性的菌落频率，因为在啮齿动物细胞中，PALA 抗性主要是通过 CAD（氨甲酰-p-合成酶、天冬氨酸转氨甲酰酶、二氢乳清酶）基因的扩增来实现的。经过不同剂量的伽马射线和 H2O2 治疗后，我们发现基因扩增和染色体畸变的频率与剂量相关。当使用相同剂量的损伤剂时，V3 中的增量高于 AA8 中的增量。这些结果表明，未有效修复的 DSB 可能是诱导基因扩增的原因。 H2O2 和伽马射线一样刺激基因扩增，但是，在相似的扩增诱导水平下，染色体损伤要低约 50%。这表明 H2O2 可以通过替代直接 DNA 损伤的途径诱导基因扩增。 H2O2（有氧代谢的产物之一）对基因扩增的刺激支持了这样的假设：细胞代谢产物本身可能是基因组不稳定的根源。 (C) 2002 Elsevier Science B.V. 保留所有权利。
To investigate the role of DNA double strand breaks (DSBs) and of their repair in gene amplification, we analyzed this process in the V3 Chinese hamster cell line and in the parental line AA8, after exposure to gamma-rays and to hydrogen peroxide (H2O2). V3 is defective in DSB repair because of a mutation in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) gene, a gene involved in the non-homologous end-joining pathway. As a measure of gene amplification we used the frequency of colonies resistant to N-(phosphonacetyl)-L-aspartate (PALA), since in rodent cells PALA resistance is mainly achieved through the amplification of the CAD (carbamyl-p-synthetase, aspartate transcarbamylase, dihydro-orotase) gene. After treatment with different doses of gamma-rays and of H2O2, we found a dose related increase in the frequency of gene amplification and of chromosome aberrations. When the same doses of damaging agents were used, these increments were higher in V3 than in AA8. These results indicate that DSBs that are not efficiently repaired can be responsible for the induction of gene amplification. H2O2 Stimulates gene amplification as well as gamma-rays, however, at similar levels of amplification induction, chromosome damage was about 50% lower. This suggests that gene amplification can be induced by H2O2 through pathways alternative to a direct DNA damage. Stimulation of gene amplification by H2O2, which is one of the products of the aerobic metabolism, supports the hypothesis that cellular metabolic products themselves can be a source of genome instability. (C) 2002 Elsevier Science B.V. All rights reserved.