Assessment of PCBs and hydroxylated PCBs as potential xenoestrogens: In vitro studies based on MCF-7 cell proliferation and induction of vitellogeninin primary culture of rainbow trout hepatocytes

In the present study, four structurally diverse polychlorinated biphenyls ( PCBs) were chosen from a set of 20 PCBs selected to represent the 154 tetra - through heptachlorinated biphenyls. The purpose was to determine estrogen ic activities of the chosen PCBs and five of their hydroxylated derivatives (OH-PCBs). A human breast cancer cell line (MCF-7) and primary cultures of rainbow trout (Oncorhyncus mykiss) hepatocytes were used to determine estr ogenic effects. The PCBs 2,2',4,6,6'-pentachlorobiphenyl (104) and 2,2',3,4 ', 5,6,6'-heptachlorobiphenyl (188),and the hydroxylated PCBs 2,2',4',6'-te trachloro-4-biphenylol (4'-50), 2',4',6'-trichloro-4-biphenylol (4'-30), 2' ,3,5,5'-tetrachloro-4-biphenylol (4'-72), 2',3,3',5',6'-pentachloro-4-biphe nylol (4'-112), and 2',3,4',5,6'-pentachloro-4-biphenylol (4'-121) signific antly increased MCF-7 cell proliferation. The coaddition of hydroxytamoxife n an estrogen antagonist, inhibited increased cell proliferation. The activ ity of the hydroxylated PCBs 4'-50 and 4'-30 was significantly higher at al l nominal concentrations tested as compared to the corresponding PCB, viz., PCB 104. The hydroxylated PCBs 4'-50, 4'-30, 4'-72 and 4'-112 induced vite llogenin synthesis in rainbow trout hepatocytes. Significant differences we re found in the MCF-7 system between the parent PCB and its hydroxylated de rivative, viz., for 4'-50/4'-30 and 104, and in the rainbow trout hepatocyt e assay between 4'-112 and 112, respectively. No activity was observed for PCB 58 in any of the two assays in the present study. Even though cells fro m two different species (human and fish) are used in the present study, the results obtained by the two methods agree fairly well. In both studies the hydroxylated PCBs were more active than the PCBs, and 4'-30 was the most a ctive compound second only to 17 beta-estradiol.