title: Succinate dehydrogenase activity regulates PCB3-quinone-induced metabolic oxidative stress and toxicity in HaCaT human keratinocytes.
abstract: Polychlorinated biphenyls (PCBs) and their metabolites are environmental pollutants that are known to have adverse health effects. 1-(4-Chlorophenyl)-benzo-2,5-quinone (4-ClBQ), a quinone metabolite of 4-monochlorobiphenyl (PCB3, present in the environment and human blood) is toxic to human skin keratinocytes, and breast and prostate epithelial cells. This study investigates the hypothesis that 4-ClBQ-induced metabolic oxidative stress regulates toxicity in human keratinocytes. Results from Seahorse XF96 Analyzer showed that the 4-ClBQ treatment increased extracellular acidification rate, proton production rate, oxygen consumption rate and ATP content, indicative of metabolic oxidative stress. Results from a q-RT-PCR assay showed significant increases in the mRNA levels of hexokinase 2 (hk2), pyruvate kinase M2 (pkm2) and glucose-6-phosphate dehydrogenase (g6pd), and decreases in the mRNA levels of succinate dehydrogenase (complex II) subunit C and D (sdhc and sdhd). Pharmacological inhibition of G6PD-activity enhanced the toxicity of 4-ClBQ, suggesting that the protective function of the pentose phosphate pathway is functional in 4-ClBQ-treated cells. The decrease in sdhc and sdhd expression was associated with a significant decrease in complex II activity and increase in mitochondrial levels of ROS. Overexpression of sdhc and sdhd suppressed 4-ClBQ-induced inhibition of complex II activity, increase in mitochondrial levels of ROS, and toxicity. These results suggest that the 4-ClBQ treatment induces metabolic oxidative stress in HaCaT cells, and while the protective function of the pentose phosphate pathway is active, inhibition of complex II activity sensitizes HaCaT cells to 4-ClBQ-induced toxicity.
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA.
authors.forename: Wusheng
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA.
authors.forename: Ehab H
authors.initials: EH
authors.lastname: Sarsour
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA.
authors.forename: Brett A
authors.initials: BA
authors.lastname: Wagner
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Doskey
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA.
authors.forename: Garry R
authors.initials: GR
authors.lastname: Buettner
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA.
authors.forename: Frederick E
authors.initials: FE
authors.lastname: Domann
authors.affiliation: Free Radical and Radiation Biology Division, Department of Radiation Oncology, B180 Medical Laboratories, The University of Iowa, Iowa City, IA, 52242, USA. prabhat-goswami@uiowa.edu.
authors.forename: Prabhat C
authors.initials: PC
authors.lastname: Goswami
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D016227:Benzoquinones / Q000633:toxicity*; D001713:Biphenyl Compounds / Q000633:toxicity; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D006593:Hexokinase / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D013963:Thyroid Hormones / Q000235:genetics / Q000378:metabolism; D000097810:Thyroid Hormone-Binding Proteins
chemical_list: D000255:Adenosine Triphosphate; D016227:Benzoquinones; D001713:Biphenyl Compounds; D002352:Carrier Proteins; D006593:Hexokinase; D008565:Membrane Proteins; D013385:Succinate Dehydrogenase; D013963:Thyroid Hormones; D000097810:Thyroid Hormone-Binding Proteins; C000597136:1-(4-chlorophenyl)-benzo-2,5-quinone; C108096:SDHC protein, human; C004532:quinone; C000609700:HK2 protein, human; C006983:4-chlorobiphenyl
keywords: G6PD; Glucose metabolism; Metabolic oxidative stress; PCB3-quinone; Polychlorinated biphenyls; Succinate dehydrogenase