Induction of oxidative single- and double-strand breaks in DNA by ferric citrate.
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.
Molecular Biology Branch, Center for Devices and Radiological Health, Food and Drug Administration, Rockville, MD 20857.
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S
Toyokuni
J L
JL
Sagripanti
D001205:Ascorbic Acid / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D003545:Cysteine / Q000494:pharmacology; D004249:DNA Damage; D004278:DNA, Superhelical / Q000187:drug effects*; D003676:Deferoxamine / Q000494:pharmacology; D005290:Ferric Compounds / Q000494:pharmacology*; D016166:Free Radical Scavengers; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D010957:Plasmids; D013481:Superoxides / Q000494:pharmacology
D004278:DNA, Superhelical; D005290:Ferric Compounds; D016166:Free Radical Scavengers; D013481:Superoxides; C025314:ferric citrate; D006861:Hydrogen Peroxide; D002374:Catalase; D003676:Deferoxamine; D003545:Cysteine; D001205:Ascorbic Acid