柠檬酸铁对DNA中氧化性单链和双链断裂的诱导作用。

Induction of oxidative single- and double-strand breaks in DNA by ferric citrate.

作者信息

Toyokuni S, Sagripanti J L

机构信息

Molecular Biology Branch, Center for Devices and Radiological Health, Food and Drug Administration, Rockville, MD 20857.

出版信息

Free Radic Biol Med. 1993 Aug;15(2):117-23. doi: 10.1016/0891-5849(93)90050-5.

DOI:10.1016/0891-5849(93)90050-5

PMID:8397139

Abstract

The relative risk of primary hepatocellular carcinoma in genetic hemochromatosis (GH) is estimated at over 200 times as that of control populations. Recently, ferric ion chelated to citrate (Fe-citrate) was identified as the major non-transferrin-bound iron in the serum of GH patients. We investigated whether low concentration of Fe-citrate plus reductant could damage supercoiled plasmid DNA under physiological pH and ionic strength. Incubation of Fe-citrate with either H2O2, L-ascorbate, or L-cysteine induced single- and double-strand breaks in supercoiled plasmid pZ189 in a concentration- and time-dependent fashion. DNA strand breaks produced by Fe-citrate plus H2O2 increased at reduced pH (< or = 6.9). Catalase and free radical scavengers inhibited the DNA breakage produced by Fe-citrate in combination with each reductant, suggesting that H2O2 and finally .OH are responsible DNA damaging species. The catalytic ability of Fe-citrate to induce DNA strand breaks, particularly double-strand breaks (DSBs), may contribute to the carcinogenic processes observed in GH.

摘要

遗传性血色素沉着症（GH）患者发生原发性肝细胞癌的相对风险估计是对照人群的200多倍。最近，与柠檬酸盐螯合的铁离子（柠檬酸铁）被确定为GH患者血清中主要的非转铁蛋白结合铁。我们研究了低浓度的柠檬酸铁加还原剂在生理pH值和离子强度下是否会损伤超螺旋质粒DNA。柠檬酸铁与过氧化氢、L-抗坏血酸或L-半胱氨酸孵育，以浓度和时间依赖性方式诱导超螺旋质粒pZ189出现单链和双链断裂。在pH值降低（≤6.9）时，柠檬酸铁加过氧化氢产生的DNA链断裂增加。过氧化氢酶和自由基清除剂抑制了柠檬酸铁与每种还原剂结合产生的DNA断裂，表明过氧化氢以及最终的·OH是造成DNA损伤的物质。柠檬酸铁诱导DNA链断裂，特别是双链断裂（DSB）的催化能力，可能与GH中观察到的致癌过程有关。