Abstract
Abstract ABC transporters such as BCRP, P-gp, Mrp2 and Mrp3 are thought to protect organisms from xenobiotics, including dietary carcinogens and anticancer drugs. These multidrug transporters reduce the oral uptake, systemic availability and tissue or cellular accumulation of transported substrates by mediating their extrusion from cells and the body in general. Therefore, they could have very important roles in the distribution of carcinogens to certain tissues and cell types, and carcinogen susceptibility. In this study, we aimed to investigate the role of ABC transporters in the tumorigenicity of a dietary carcinogen, PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine), which is produced during high-temperature cooking of meat. We have performed a pharmacokinetic experiment in wild-type FVB and ABC transporter knockout strains (Bcrp;Mrp2;Mrp3-/- and Bcrp;Mdr1a/1b;Mrp2-/-) with 200 mg/kg orally administered PhIP and observed that ABC transporters have an impact on the distribution of PhIP metabolites to several organs. There was an accumulation of N-OH-PhIP, a potentially carcinogenic metabolite, in the liver of Bcrp;Mrp2;Mrp3-/- mice and a decrease in the levels of PhIP-5-sulfate, a surrogate marker for DNA exposure to reactive compound, in small intestine of Bcrp;Mrp2;Mrp3-/- and Bcrp;Mdr1a/1b;Mrp2-/- mice compared to wild-type FVB. For carcinogenesis experiments, we used a chemically-induced colon carcinogenesis model where wild-type FVB and ABC transporter compound knock-out mice received a single, oral administration of 200 mg/kg PhIP for initiation and seven days administration of Dextran Sodium Sulfate (DSS) in drinking water for promotion of the tumorigenesis process via colonic inflammation. During the whole experiment, mice were closely checked for their body weight loss, diarrhea and rectal bleeding. Our results showed that PhIP and DSS treatment together induced colonic tumors in all strains over 180 days. No tumor formation could be found in only PhIP-treated, only DSS-treated and negative control groups that received vehicle. Tumor incidence was lower in both knock-outs compared to the wild-type FVB when inflammation levels between the groups were corrected. Our results suggest that these ABC transporters are not protecting the intestinal tract from PhIP-induced carcinogenesis upon oral ingestion in mice, and perhaps even partially enhance PhIP-induced carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4419. doi:1538-7445.AM2012-4419
Published Version
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