Comparative assessment of polychlorinated biphenyls’ toxic potential in ovary cells

Abstract

PCBs are considered as potential endocrine disruptors with various deleterious effects on female reproductive system. Although, the environmental PCB levels have been declining due to legislation, in the Republic of Croatia risk is still high due to destructions of the facilities containing PCBs during the Patriotic War (1991–1995). The toxic profiles of PCBs are congener-specific and the major structural factor in determining the toxic properties is the presence of chlorine atom in ortho position. A comparative assessment of dioxin-like, coplanar PCB 77 and non-dioxin-like, ortho-substituted PCB 153 effects has been performed in this study to evaluate the potential risk and mode of action for inducing cytotoxicity in Chinese hamster ovary cells. In order to assess and quantify toxic effects of PCBs (10–100 μM) three in vitro methods with distinct endpoints were chosen: Trypan blue (TB), Neutral red (NR) and Kenacid blue assays (KB). Overall, a dose dependent cytotoxicity for PCB-77 was confirmed with all assays applied, whereas for PCB-153 only with TB and NR. Extent of the cellular viability loss and accelerated cell death were greater for non-ortho-substituted PCB-77 (after 72 h: IC50-TB = 24.0 μM ; IC50-NR = 55.4 μM ; IC50-KB = 94.2 μM) than for di-ortho-substituted congener PCB-153 (after 72 h: IC50-TB = 55.5 μM ; IC50-NR = 51.0 μM ; IC50-KB = 111.1 μM). To determine if exposure to PCBs perturbs cellular proliferation, CHO-K1 cells were incubated with 50 μM PCB-77 or PCB-153 for 6 or 48 h and assayed for cell cycle phase distributions using flow cytometry. Major induced alterations were detected for PCB 77 with a slight increase in apoptotic peak vs. no observed effect for PCB-153.