MAMMALIAN-CELLS ARE NOT KILLED BY DNA SINGLE-STRAND BREAKS CAUSED BY HYDROXYL RADICALS FROM HYDROGEN-PEROXIDE
MAMMALIAN-CELLS ARE NOT KILLED BY DNA SINGLE-STRAND BREAKS CAUSED BY HYDROXYL RADICALS FROM HYDROGEN-PEROXIDE
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DOI：
10.2307/3576760
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发表时间：
1985-01-01
影响因子：
3.4
通讯作者：
JONER, EI
中科院分区：
文献类型：
--
作者：
WARD, JF;BLAKELY, WF;JONER, EI
电离辐射的细胞杀伤已被证明是由水辐射分解形成的羟基自由基引起的。我们先前提出，杀伤不是由单个OH自由基引起的，而是由大量高自由基密度与DNA相互作用引起局部损伤位点（LMDS）引起的（J.F. Ward, Radiat）。Res. 86, 185-195, 1985)。在这里，我们用过氧化氢作为OH自由基的替代来源来检验这一假设。从H2O2生成OH的途径预计会导致单个位点受损，而不是LMDS。用不同浓度、不同时间、0℃的H2O2处理中国仓鼠V79-171细胞。C.用碱性洗脱法测定细胞内双倍DNA损伤，并以灰色当量损伤为定量指标，将碱性洗脱法与γ - γ DNA洗脱法进行比较。辐照细胞。DNA损伤产率随H2O2浓度的增加和暴露时间的延长而增加。H2O2能有效地产生单链断裂；处理面积50亩。照射30分钟产生的伤害相当于10gy的γ射线所造成的伤害。辐照。在羟基自由基清除剂二甲基亚砜（DMSO）存在的情况下，损伤率随DMSO浓度的增加而降低，清除羟基自由基的平均行程为15 . ang。在与DNA反应之前与DNA损伤的产生相反，0度H2O2处理对细胞的杀伤作用。是低效的。浓度为5。10-2 M H2O2持续10分钟才能产生显著的细胞杀伤作用；这种处理产生的DNA损伤当量可以计算为相当于6000戈瑞的γ射线。辐照。得出的结论是，单个DNA损伤位点在杀死细胞方面是无效的。建议在0度下杀死的机制。在37℃时H2O2对细胞的有效杀伤。浓度低得多的C。
Cell killing by ionizing radiation has been shown to be caused by hydroxyl free radicals formed by water radiolysis. We have previously suggested that the killing is not caused by individual OH free radicals but by the interaction of volumes of high radical density with DNA to cause locally multiply damaged sites (LMDS) (J.F. Ward, Radiat. Res. 86, 185-195, 1985). Here we test this hypothesis using hydrogen peroxide as an alternate source of OH radicals. The route to OH production from H2O2 is expected to cause singly damaged sites rather than LMDS. Chinese hamster V79-171 cells were treated with H2O2 at varying concentrations for varying times at 0.degree. C. DNA damage doubled intracellulary was measured by alkaline elution and quantitated in terms of Gray-eqivalent damage by comparing the rat of its elution with that of DNA from .gamma.-irradiated cells. The yields of DNA damage produced increase with increasing concentration of H2O2 and with time of exposure. H2O2 is efficient in producing single-strand breaks; treatment with 50 .mu.M for 30 min produces damage equivalent to that formed by 10 Gy of .gamma. irradiation. In the presence of a hydroxyl radical scavenger, dimethyl sulfoxide (DMSO), the yield of damage decreases with increasing DMSO concentration consistent with the scavenging of hydroxyl radicals traveling an average of 15 .ANG. prior to reacting with the DNA. In contrast to DNA damage production, cell killing by H2O2 treatment at 0.degree. is inefficient. Concentrations of 5 .times. 10-2 M H2O2 for 10 min are required to produce significant cell killing; the DNA damage yield from this treatment can be calculated to be equivalent to 6000 Gy of .gamma. irradiation. The conclusion drawn is that individual DNA damage sites are ineffectual in killing cells. Mechanisms are suggested for killing at 0.degree. C at high concentrations and for the efficient cell killing by H2O2 at 37.degree. C at much lower concentrations.