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

Abstract

The multidrug transporters breast cancer resistance protein (BCRP), multidrug-resistance protein 1 (MDR1), and multidrugresistance-associated protein (MRP) 2 and 3 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 2/2 mice, which are viable and fertile. These mice, together with Bcrp1;Mrp2;Mrp3 2/2 mice, were used to study the effects of the multidrug transporters on the pharmacokinetics of PhIP and its metabolites. Thirty minutes after oral or intravenous administration of PhIP (1 mg/kg), the PhIP levels in the small intestine were reduced 4-to 6-fold in Bcrp1;Mdr1a/b;Mrp2 2/ 2 and Bcrp1;Mrp2;Mrp3 2/2 mice compared with wild-type mice. Fecal excretion of PhIP was reduced 8-to 20-fold in knockouts. Biliary PhIP excretion was reduced 41-fold in Bcrp1;Mdr1a/b;Mrp2 2/2 mice. Biliary and small intestine levels of PhIP metabolites were reduced in Bcrp1;Mrp2-deficient mice. Furthermore, in both knockout strains, kidney levels and urinary excretion of genotoxic PhIPmetabolites 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 2/2 , but not Bcrp1; Mdr1a/b;Mrp 2/2 mice, the carcinogenic metabolites N2-OHPhIP (2-hydroxyamino-1-methyl-6-phenylimidazo [4,5-b]pyridine) and PhIP-5-sulfate (a genotoxicity marker) accumulated in liver tissue, 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.

Apical ABC Transporters and Cancer Chemotherapeutic Drug Disposition

“…Focusing on ABC transporters, there are two functionally relevant locations, one at the intestinal epithelium (enterocytes) and one in the liver (hepatocytes), that limit oral bioavailability of drugs, primarily via the apical ABC transporters, ABCB1, ABCC2, and ABCG2 (Dietrich, Geier, & Oude Elferink, 2003;Misaka, Muller, & Fromm, 2013). These transporters can restrict the systemic availability of orally administered drugs and other xenotoxins (e.g., the dietary phototoxin pheophorbide A and the dietary carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) by mediating their intestinal and biliary excretion (Agarwal et al, 2011;Dietrich, de Waart, Ottenhoff, Schoots, & Elferink, 2001;Jonker et al, 2002;Vlaming et al, 2014). Therefore, increased bioavailability can be obtained when ABC transporters are absent or inhibited, which has been experimentally shown for several drugs .…”

Handling of Drugs, Metabolites, and Uremic Toxins by Kidney Proximal Tubule Drug Transporters

“…The ABC transporter, P-gp (MDR1), which transports a wide range of molecules, is one of the best understood from the viewpoint of protein structure in relation to transport function (1,36,37). P-gp has been widely studied in the context of cancer biology and its contribution to tumor resistance to chemotherapy (with increased expression of MDR1 on cancer cells associated with greater resistance).…”

Inhibition of organic cation transporter (OCT) activities by carcinogenic heterocyclic aromatic amines

“…BCRP also handles Trp-P-1 and IQ (van Herwaarden et al, 2006). Because ABC transporters are notably localized at the apical domain of enterocytes and at the canalicular domain of hepatocytes, they likely reduce systemic exposure to HAAs by preventing their intestinal absorption and by contributing to their biliary elimination (Dietrich et al, 2001;Vlaming et al, 2014). Besides ABC efflux pumps, solute carrier (SLC) transporters, which mainly mediate drug uptake into cells through facilitated diffusion or secondary active transport (Giacomini et al, 2010), are presumed to also interact with HAAs.…”