Polychlorinated biphenyls and their metabolites are environmental pollutants that are believed to have adverse health effects presumably by inducing oxidative stress. To determine if 1-(4-Chlorophenyl)-benzo-2,5-quinone (4-ClBQ; metabolite of 4-monochlorobiphenyl, PCB3)-induced oxidative stress is associated with changes in the expression of specific antioxidant genes, mRNA levels of 92 oxidative stress-response genes were analyzed using TaqMan Array Human Antioxidant Mechanisms (Life Technologies), and results were verified by performing quantitative RT-PCR assays. The expression of selenoprotein P (sepp1) was significantly downregulated (8- to 10-fold) in 4-ClBQ-treated HaCaT human skin keratinocytes, which correlated with a significant increase in MitoSOX oxidation. Overexpression of Mn-superoxide dismutase or catalase or treatment with N-acetyl-l-cysteine suppressed 4-ClBQ-induced toxicity. Sodium selenite supplementation also suppressed 4-ClBQ-induced decrease in sepp1 expression, which was associated with a significant inhibition in cell death. Furthermore, HaCaT cells overexpressing sepp1 were resistant to 4-ClBQ-induced oxidative stress and toxicity. These results demonstrate that SEPP1 represents a previously unrecognized regulator of PCB-induced biological effects. These results support the speculation that selenoproteins can be an attractive countermeasure for PCB-induced adverse biological effects.
Keywords: 1-(4-Chlorophenyl)-benzo-2,5-quinone; 4-ClBQ; 4-monochlorobiphenyl; AdCAT; AdEmpty; AdMnSOD; Free radicals; HaCaT; MFI; N-acetyl-L-cysteine; NAC; Oxidative stress; PCB3; PEG-CAT; PEG-SOD; Polychlorinated biphenyls; ROS; SECIS; SEPP1; Selenoprotein P; adenovirus carrying a control vector without an insert; adenovirus carrying a human Mn-superoxide dismutase cDNA; adenovirus carrying a human catalase cDNA; mean fluorescence intensity; polyethylene glycol–catalase; polyethylene glycol–superoxide dismutase; reactive oxygen species; selenocysteine insertion sequence; selenoprotein P.
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