HIERARCHICAL CLUSTER-ANALYSIS OF ENVIRONMENTAL-POLLUTANTS THROUGH P450 INDUCTION IN CULTURED HEPATIC CELLS - INDICATIONS FOR A TOXICITY SCREENING-TEST

Environmental pollutants are classically associated with increased dru g metabolism. Cultures of rat hepatocytes, quail hepatocytes, and huma n hepatoma (Hep G2) cells were used to study the effects of pesticides on drug-metabolizing enzymes. Membrane integrity and mitochondrial ac tivity were evaluated and induction of ethoxycoumarin-O-deethylase and ethoxyresorufin-O-deethylase activities were measured. Induced P450s were identified by immunoblotting. Pentachlorophenol and lindane appea red as the strongest inducers. On the immunoblots, specific antibodies revealed induced CYP1A1 in fetal rat hepatocytes, CYP2B in quail hepa tocytes, and CYP3A7 in Hep G2 cells. Pesticide effects on these differ ent activities in each type of cultured cells were compared by cluster analysis. Results obtained under similar conditions with reference in ducers phenobarbital (PB) and benzo[a]anthracene and other environment al pollutants (polychlorobiphenyls) were added to previous data prior to multivariate analysis. The tested products fell into four major gro ups: a first group with pentachlorophenol, identified as a CYP3A induc er; a second group containing the methylcholanthrene-type inducers tha t increase CYP1A-related activities; a third class represented by diel drin, a PB-type inducer; a fourth group including inert compounds or w eak inducers. Lindane shares the criteria of the second and third grou ps and seems to induce both CYP1A and CYP2B activities. The current st udy results highlight the advantage of using several types of cultured hepatocytes to evaluate the short-term toxicity of environmental poll utants in vitro and constitute a useful model for predicting the poten tial toxicity of pesticides in humans (Hep G2 cells) and wildlife (fet al quail hepatocytes). (C) 1996 Academic Press, Inc.