Journal Article

Production of DNA Strand Breaks <i>in Vitro</i> and Reactive Oxygen Species <i>in Vitro</i> and in HL-60 Cells by PCB Metabolites

Anandi Srinivasan, Hans-Joachim Lehmler, Larry W. Robertson and Gabriele Ludewig

in Toxicological Sciences

Volume 60, issue 1, pages 92-102
Published in print March 2001 | ISSN: 1096-6080
Published online March 2001 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/60.1.92
Production of DNA Strand Breaks in Vitro and Reactive Oxygen Species in Vitro and in HL-60 Cells by PCB Metabolites

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PCBs are industrial chemicals that continue to contaminate our environment. They cause various toxic effects in animals and in exposed human populations. The mechanisms of toxicity, however, are not completely understood. PCBs are metabolized by cytochromes P450 to mono- and dihydroxylated compounds. Dihydroxy-PCBs can potentially be oxidized to the corresponding quinones. We hypothesized that reactive oxygen species (ROS) are produced by redox reactions of PCB metabolites. We tested several synthetic dihydroxy- and quinoid-PCBs with 1-3 chlorines for their potential to produce ROS in vitro and in HL-60 human leukemia cells, and DNA strand breaks in vitro. All dihydroxy-PCBs tested produced superoxide. The quinones generated superoxide only in the presence of GSH, probably during the autoxidation of the glutathione conjugates. We observed increased superoxide production with decreasing halogenation. Incubation of dihydroxy-PCBs or PCB quinones + GSH with plasmid DNA resulted in DNA strand break induction in the presence of Cu(II). Tests with various ROS scavengers indicated that hydroxyl radicals and singlet oxygen are likely involved in this strand break induction. Finally, dihydroxy- and quinoid PCBs also produced ROS in HL-60 cells in a dose- and time-dependent manner. We conclude that dihydroxylated PCBs, and PCB quinones after reaction with GSH, produce superoxide and other ROS both in vitro and in HL-60 cells, and oxidative DNA damage in the form of DNA strand breaks in vitro. The reactions seen in vitro and in cells may well be a predictor of the toxicity of PCBs in animals.

Keywords: PCBs; ROS production; DNA strand breaks; quinones; hydroquinones

Journal Article.  7258 words.  Illustrated.

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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