The multidrug transporters BCRP, MDR1, MRP2 and MRP3 eliminate toxic compounds from tissues and the body, and affect the pharmacokinetics of many drugs and other potentially toxic compounds. The food-derived carcinogen PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) is transported by BCRP, MDR1 and MRP2. To investigate the overlapping functions of Bcrp1, Mdr1a/b and Mrp2 in vivo, we generated Bcrp1;Mdr1a/b;Mrp2-/- mice, which are viable and fertile. These mice, together with Bcrp1;Mrp2;Mrp3-/- mice, were used to study the effects of the multidrug transporters on the pharmacokinetics of PhIP and its metabolites. 30 minutes after oral or i.v. administration of PhIP (1 mg/kg), PhIP levels in small intestine were 4-6-fold reduced in Bcrp1;Mdr1a/b;Mrp2-/- and Bcrp1;Mrp2;Mrp3-/- mice compared to wild-type mice. Fecal excretion of PhIP was 8-20-fold reduced in knockouts. Biliary PhIP excretion was 41-fold reduced in Bcrp1;Mdr1a/b;Mrp2-/- mice. Biliary and small intestinal levels of PhIP metabolites were reduced in Bcrp1;Mrp2-deficient mice. Furthermore, in both knockout strains kidney levels and urinary excretion of genotoxic PhIP-metabolites were significantly increased, suggesting that reduced biliary excretion of PhIP and PhIP-metabolites leads to increased urinary excretion of these metabolites, and increased systemic exposure. Bcrp1 and Mdr1a limited PhIP brain accumulation. In Bcrp1;Mrp2;Mrp3-/-, but not Bcrp1;Mdr1a/b;Mrp2-/- mice, the carcinogenic metabolites N2-OH-PhIP and PhIP-5-sulphate (a genotoxicity marker) accumulated in liver, indicating that Mrp3 is involved in the sinusoidal secretion of these compounds. We conclude that Bcrp1, Mdr1a/b, Mrp2 and Mrp3 significantly affect tissue disposition and biliary and fecal elimination of PhIP and its carcinogenic metabolites and may affect PhIP-induced carcinogenesis as a result.
Vlaming, M. A. J., Teunissen, S. F., Steeg, van de, E., Esch, van, A., Wagenaar, E., Brunsveld, L., ... Schinkel, A. H. (2014). Bcrp1;Mdr1a/b;Mrp2 combination knockout mice : altered disposition of the dietary carcinogen PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) and its genotoxic metabolites. Molecular Pharmacology, 85(3), 520-530. https://doi.org/10.1124/mol.113.088823