title: Malignant transformation of cultured rat hepatocytes by (+)- and (-)-trans-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene.
abstract: Rat hepatocyte cultures (RL-PR-C) were tested with the (+)- or (-)-trans-7,8-dihydrodiol isomers of benzo(a)pyrene [B(a)P] and were assessed for growth inhibition, chromosomal damage, growth in soft agar, and tumor formation. Because early-passage cells have a noninducible low specific activity, aryl hydrocarbon hydroxylase parallel inhibition studies were performed on aryl hydrocarbon hydroxylase-inducible late-passage cultures. Early-passage cells exhibited little inhibition in the presence of B(a)P or either isomer. Comparable later-passage cells demonstrated inhibitory effects with B(a)P and the (+)- and (-)-trans-7,8-dihydrodiol metabolites. No treated cultures grew in soft agar, and the modal number of chromosomes was unaffected by carcinogen treatment. However, both (+) and (-) isomer-treated early-passage cells formed tumors in isogeneic animals, the (+) isomer being more efficient in this regard. These results indicate that noninhibitory doses of either the (+)- or (-)-trans-7,8-dihydrodiol isomer of B(a)P are nonetheless capable of malignantly transforming hepatocyte cells in vitro.
mesh_terms: D000818:Animals; D001580:Benzopyrenes / Q000633:toxicity*; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D004101:Dihydroxydihydrobenzopyrenes; D008099:Liver / Q000187:drug effects*; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000235:genetics; D051381:Rats; D013237:Stereoisomerism
chemical_list: D001580:Benzopyrenes; D004101:Dihydroxydihydrobenzopyrenes; C017228:benzo(a)pyrene 7,8-dihydrodiol