DNA-DAMAGE RESULTING FROM THE OXIDATION OF HYDROQUINONE BY COPPER - ROLE FOR A CU(II)/CU(I) REDOX CYCLE AND REACTIVE OXYGEN GENERATION
DNA-DAMAGE RESULTING FROM THE OXIDATION OF HYDROQUINONE BY COPPER - ROLE FOR A CU(II)/CU(I) REDOX CYCLE AND REACTIVE OXYGEN GENERATION
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DOI：
10.1093/carcin/14.7.1303
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发表时间：
1993-07-01
期刊：
影响因子：
4.7
通讯作者：
TRUSH, MA
中科院分区：
文献类型：
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作者：
LI, YB;TRUSH, MA
与苯暴露相关的骨髓毒性，包括白血病，归因于苯衍生代谢物的进一步活化。在之前的研究中，我们发现Cu（II）通过Cu(II)/Cu(I)氧化还原机制强烈地介导对苯二酚（HQ）的氧化生成苯醌（BQ）和H2O2。由于铜存在于细胞核中，并且与染色体和DNA密切相关，在本研究中，我们研究了这种化学-金属氧化还原系统是否会诱导phiX-174 RFI质粒DNA的链断裂。当存在微摩尔浓度的Cu（II）和HQ时，单链和双链断裂都被诱导，而在所使用的浓度下，HQ、Cu（II）、H2O2或BQ单独对DNA没有明显的损伤。HQ/Cu（II）体系诱导DNA链断裂的效率至少是H2O2/Cu（II）体系的两倍。在Cu（II）、Fe（III）、Mn（II）、Cd（II）和Zn（II）中，只有HQ/Cu（II）诱导了广泛的DNA链断裂。在HQ、1,2,4-苯三醇（BT）、儿茶酚和苯酚中，HQ/Cu（II）和BT/Cu（II）是两种最有效的DNA切割体系。二磺酸（BCS）或过氧化氢酶的存在阻止了HQ/Cu（II）诱导的DNA链断裂。此外，HQ/Cu（II）诱导的DNA链断裂可以被还原型谷胱甘肽和二硫苏糖醇完全阻断，但不能被l -半胱氨酸阻断。在没有HQ的情况下，l -半胱氨酸与铜的相互作用诱导了显著的DNA链断裂，其断裂模式与HQ/Cu(II) + l -半胱氨酸相同。与HQ/Cu（II）系统相比，HQ/髓过氧化物酶(MPO)/H2O2系统没有诱导任何DNA链断裂，而且MPO的存在抑制了HQ/Cu（Il）诱导的DNA链断裂。当用Cu（II）预处理过的DNA暴露于HQ时，DNA链断裂，而BCS或过氧化氢酶可以阻止DNA链断裂，这表明DNA结合的铜可以在HQ存在下进行氧化还原循环，产生H2O2。与H2O2/Cu（II）体系类似，HQ/Cu（II）诱导的DNA链断裂不能被羟基自由基清除剂有效抑制，但可以被单线态氧清除剂保护，这表明在HQ/Cu（II）诱导的DNA链断裂中，单线态氧或单线态氧样实体（可能是铜-过氧化物配合物）的局部生成可能起作用，而不是自由羟基自由基。上述结果提示，大分子相关铜和活性氧的产生可能是红旗诱导靶细胞DNA损伤机制的重要因素。
The myelotoxicity, including leukemia, associated with benzene exposure has been attributed to the further activation of benzene-derived metabolites. In a previous study, we observed that Cu(II) strongly mediates the oxidation of hydroquinone (HQ) producing benzoquinone (BQ) and H2O2 through Cu(II)/Cu(I) redox mechanism. Since copper exists in the nucleus and is closely associated with chromosomes and DNA, in this study we investigated whether this chemical-metal redox system induces strand breaks in phiX-174 RFI plasmid DNA. In the presence of micromolar concentrations of Cu(II) and HQ, both single and double strand breaks were induced, whereas HQ, Cu(II), H2O2 or BQ alone at the employed concentrations elicited no significant damage to DNA. The HQ/Cu(II) system was at least twice as efficient as a H2O2/Cu(II) system at inducing DNA strand breaks. Of Cu(II), Fe(III), Mn(II), Cd(II) and Zn(II), only HQ/Cu(II) induced extensive DNA strand breaks. Among HQ, 1,2,4-benzenetriol (BT), catechol and phenol, HQ/Cu(II) and BT/Cu(II) were the two most efficient DNA cleaving systems. The presence of bathocuproinedisulfonic acid (BCS) or catalase prevented the HQ/Cu(II)-induced DNA strand breaks. In addition, the HQ/Cu(II)-induced DNA strand breaks could be completely blocked by reduced glutathione and dithiothreitol, but not by L-cysteine. The interaction of L-cysteine with copper in the absence of HQ induced significant DNA strand breaks with the same pattern of DNA strand breaks as that of HQ/Cu(II) plus L-cysteine. In contrast to the HQ/Cu(II) system, a HQ/myeloperoxidase (MPO)/H2O2 system did not induce any DNA strand breaks, and furthermore, the presence of MPO inhibited the HQ/Cu(Il)-induced DNA strand breaks. When DNA pretreated with Cu(II) was exposed to HQ, DNA strand breaks were formed that could be prevented by BCS or catalase, indicating that DNA-bound copper can undergo redox cycling in the presence of HQ, generating H2O2. Similar to the H2O2/Cu(II) system, the HQ/Cu(II)-induced DNA strand breaks could not be efficiently inhibited by hydroxyl radical scavengers but could be protected by singlet oxygen scavengers, indicating that the localized generation of singlet oxygen or a singlet oxygen-like entity, possibly a copper - peroxide complex, rather than free hydroxyl radical probably plays a role in the HQ/Cu(II)-induced DNA strand breaks. The above results suggest that macromolecule-associated copper and reactive oxygen generation may be important factors in the mechanism of HQ-induced DNA damage in target cells.