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The polychlorinated biphenyls (PCBs) are persistent and their dose-dependent toxicities studies are not well-established. In this study, cytotoxic and genotoxic effects of PCB150 and PCB180 in HeLa cells were studied. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay indicated that the cell proliferation was stimulated at low doses (10-3 and 10-2 mg/mL for 12, 24, 48, and 72 hours) and inhibited at high doses (10 and 15 mg/mL for 24, 48, and 72 hours) for both PCBs. Increase in reactive oxygen species formation was observed in the HeLa cells in a time- and dose-dependent manner. Malondialdehyde and superoxide dismutase showed increased levels at high concentrations of PCBs over the time. Glutathione peroxidase expression was downregulated after PCBs exposure, suggested that both PCB congeners may attributable to cytotoxicity. Comet assay elicited a significant increase in genotoxicity at high concentrations of PCBs as compared to low concentrations indicating genotoxic effects. PCB150 and PCB180 showed decrease in the activity of extracellular signal--regulated kinase 1/2 and c-Jun N-terminal kinase at high concentrations after 12 and 48 hours. These findings may contribute to understanding the mechanism of PCBs-induced toxicity, thereby improving the risk assessment of toxic compounds in humans. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) are persistent pollutants and pose toxic effects to humans and environment. In the current study, we focused to assess the effects of PCBs congeners (PCB70 and PCB75) upon HeLa cells using different concentrations (10-3, 10-2, 1, 10 and 15 µg/mL) and time (12, 24 and 48 h). The 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay revealed that PCB70 and PCB75 induces cell proliferation at low doses (10-3, 10-2 and 1 µg/g) and inhibit the proliferation at high doses (10 and 15 µg/g) with different time suggesting cytotoxicity. The HeLa cells were analyzed for quantification of membrane integrity and it is found that PCB70 did not cause deformity in membrane integrity. However, PCB75 showed to cause deformity in membrane integrity in dose and time dependent manners. The results from western blot assay demonstrated that PCB70 and PCB75 exposure induced the expression of extracellular signal regulated-kinases (ERK1/2) and Jun N-terminal kinases (JNK) in dose- and time-dependent manners in the HeLa cells. The findings might provide mechanistic insight of PCB congeners induced cytotoxicity to HeLa cells. [ABSTRACT FROM AUTHOR]