title: Catalase ameliorates polychlorinated biphenyl-induced cytotoxicity in nonmalignant human breast epithelial cells.
abstract: Polychlorinated biphenyls (PCBs) are environmental chemical contaminants believed to adversely affect cellular processes. We investigated the hypothesis that PCB-induced changes in the levels of cellular reactive oxygen species (ROS) induce DNA damage resulting in cytotoxicity. Exponentially growing cultures of human nonmalignant breast epithelial cells (MCF10A) were incubated with PCBs for 3 days and assayed for cell number, ROS levels, DNA damage, and cytotoxicity. Exposure to 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153) or 2-(4-chlorophenyl)benzo-1,4-quinone (4-Cl-BQ), a metabolite of 4-chlorobiphenyl (PCB3), significantly decreased cell number and MTS reduction and increased the percentage of cells with sub-G1 DNA content. Results from electron paramagnetic resonance (EPR) spectroscopy showed a 4-fold increase in the steady-state levels of ROS, which was suppressed in cells pretreated with catalase. EPR measurements in cells treated with 4-Cl-BQ detected the presence of a semiquinone radical, suggesting that the increased levels of ROS could be due to the redox cycling of 4-Cl-BQ. A dose-dependent increase in micronuclei frequency was observed in PCB-treated cells, consistent with an increase in histone 2AX phosphorylation. Treatment of cells with catalase blunted the PCB-induced increase in micronuclei frequency and H2AX phosphorylation that was consistent with an increase in cell survival. Our results demonstrate a PCB-induced increase in cellular levels of ROS causing DNA damage, resulting in cell killing.
authors.affiliation: Free Radical and Radiation Biology Program, B180 Medical Laboratories, Department of Radiation Oncology, The University of Iowa, Iowa City, IA 52242-1181, USA.
authors.forename: Venkatasubbaiah A
authors.initials: VA
authors.lastname: Venkatesha
authors.forename: Sujatha
authors.initials: S
authors.lastname: Venkataraman
authors.forename: Ehab H
authors.initials: EH
authors.lastname: Sarsour
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Kalen
authors.forename: Garry R
authors.initials: GR
authors.lastname: Buettner
authors.forename: Larry W
authors.initials: LW
authors.lastname: Robertson
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Lehmler
authors.forename: Prabhat C
authors.initials: PC
authors.lastname: Goswami
mesh_terms: D001940:Breast / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D002374:Catalase / Q000378:metabolism*; D002478:Cells, Cultured; D004578:Electron Spin Resonance Spectroscopy; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D005260:Female; D006657:Histones / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: C468783:H2AX protein, human; D006657:Histones; D017382:Reactive Oxygen Species; D011078:Polychlorinated Biphenyls; D002374:Catalase