Peak M J, Jones C A, Sedita B A, Dudek E J, Spitz D R, Peak J G
Biological and Medical Research Division, Argonne National Laboratory, Illinois 60439.
Radiat Res. 1990 Aug;123(2):220-3.
We compared measurements of cell survival and DNA single-strand breaks (SSBs) caused by hydrogen peroxide (H2O2) and UVA radiation (365-nm) in both a parental and a H2O2-resistant variant of the Chinese hamster ovary HA1 line derived by culturing cells in progressively higher concentrations of H2O2. Both RNA slot blot analysis and enzyme analysis confirmed that the variant possesses high levels of both catalase activity and mRNA. The variant was completely resistant to the lethal effects of H2O2 over the concentration range tested (up to 480 microM), whereas the parental strain showed less than 1% survival at this concentration. Similarly, the H2O2-resistant strain exhibited far fewer SSBs after exposure to H2O2 than the parental strain. Addition of o-phenanthroline to the parental cells during H2O2 exposure almost completely inhibited SSB induction, evidence that these SSBs are produced via the Fenton pathway of Haber-Weiss reactions. Very little difference was found between the variant and the parent after exposure to 365-nm radiation: only a minor difference in survival kinetics and no difference is SSB induction were observed between the two cell lines. These results are consistent with a hypothesis that most lethal events caused in cells by UVA occur by pathways that do not involve the H2O2 that is produced by sensitized reactions within the cells.
我们比较了过氧化氢（H₂O₂）和紫外线A辐射（365纳米）对中国仓鼠卵巢HA1细胞系的亲代细胞以及通过在浓度逐渐升高的H₂O₂中培养细胞而获得的H₂O₂抗性变体所造成的细胞存活和DNA单链断裂（SSB）情况。RNA斑点印迹分析和酶分析均证实，该变体同时具有高水平的过氧化氢酶活性和mRNA。在所测试的浓度范围内（高达480微摩尔），该变体对H₂O₂的致死效应完全具有抗性，而亲代菌株在此浓度下的存活率不到1%。同样，H₂O₂抗性菌株在暴露于H₂O₂后所表现出的SSB比亲代菌株少得多。在H₂O₂暴露期间向亲代细胞中添加邻菲罗啉几乎完全抑制了SSB的诱导，这证明这些SSB是通过哈伯-维伊斯反应的芬顿途径产生的。在暴露于365纳米辐射后，变体和亲代细胞之间几乎没有发现差异：仅在存活动力学上有微小差异，且在两个细胞系之间未观察到SSB诱导方面的差异。这些结果与一个假设一致，即紫外线A在细胞中引起的大多数致死事件是通过不涉及细胞内敏化反应产生的H₂O₂的途径发生的。
