title: Transport of the cooked-food mutagen 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) across the human intestinal Caco-2 cell monolayer: role of efflux pumps.
abstract: Cooked-food mutagens formed when frying meat have been suggested to contribute to the etiology of colon, breast and prostate cancer. The most prevalent of these mutagens is 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which after absorption is bioactivated by both phase I and phase II enzymes. Although available data suggest absorption of PhIP in humans, the extent and mechanism of absorption are unknown. In the present study we examined the transport of [(3)H]PhIP through the human Caco-2 intestinal epithelial cell monolayer, a well-accepted model of human intestinal absorption. The influx, or absorption, was extensive and linear for 2 h and up to a PhIP concentration of 5 microM. Still, the basolateral to apical efflux [apparent permeability coefficient (P(app)) 54.2 +/- 0.7x10(-6) cm/s, mean +/- SEM, n = 24] was 3.6 times greater than the apical to basolateral influx (P(app) 15.1 +/- 0.6x10(-6) cm/s, n = 21, P < 0.0001). Equilibrium exchange experiments demonstrated the efflux to be a true active process. Preincubations with verapamil, an inhibitor of P-glycoprotein-mediated transport, or MK-571, an inhibitor of multidrug resistance-associated protein-mediated transport, stimulated influx and reduced efflux of PhIP, suggesting that PhIP is a substrate for both of these transporters. These findings should be considered when determining exposure to the cooked food mutagens.
authors.affiliation: Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: U K
authors.initials: UK
authors.lastname: Walle
authors.forename: T
authors.initials: T
authors.lastname: Walle
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors; D001692:Biological Transport; D018938:Caco-2 Cells; D005502:Food; D006801:Humans; D007093:Imidazoles / Q000493:pharmacokinetics*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D009153:Mutagens / Q000493:pharmacokinetics*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D007093:Imidazoles; D009153:Mutagens; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine; D014700:Verapamil