A. Vamvakas et al., IN-VITRO INDUCTION OF CYP1A1-ASSOCIATED ACTIVITIES IN HUMAN AND RODENT CELL-LINES BY COMMERCIAL AND TISSUE-EXTRACTED HALOGENATED AROMATIC-HYDROCARBONS, Environmental toxicology and chemistry, 15(6), 1996, pp. 814-823
Despite reports of species-specific differences, the rat cell line H4I
IE continues to be used to assess the toxicity of many halogenated aro
matic hydrocarbon (HAH) contaminants for diverse populations using an
approach that relates aryl hydrocarbon (Ah) receptor-mediated response
s by HAHs to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). To as
sess the relevance of H4IIE for human populations, we examined levels
of aryl hydrocarbon hydroxylase (AHH) and ethyoxyresorufin O-deethylas
e (EROD) activities in H4IIE rat liver, HepG2 human liver, and MCF-7 h
uman breast cells treated with TCDD and three coplanar polychlorinated
biphenyl (PCB) congeners (77, 126, 169), alone or in combination, and
to fractions extracted from the muscle tissue of Lake Ontario rainbow
trout (Oncorhynchus ml kiss). H4IIB was generally more sensitive to a
ll HAH treatments. Both AHH and EROD activities were induced in all ce
lls treated with TCDD and PCB-126, alone or combined with each other.
In contrast, neither activity was induced in human cells treated with
PCB-77 or PCB-169. For inducing concentrations of PCBs, the induction
response in all cell lines treated with 5 nM TCDD-PCB mixtures was gen
erally nonadditive; only the response in H4IIE treated with 10(-3) nM
TCDD-PCB mixtures was generally additive. With tissue extracts, induct
ion was restricted to H4IIE cells treated with TCDD/PCB-or organochlor
ide pesticide-containing fractions. Our initial results suggest that d
ifferences in the properties of each HAH or in levels of Ah receptor i
n each cell line are not likely to underlie the significant difference
s in the murine/human induction responses.