title: Methotrexate pharmacokinetics in transgenic mice with liver-specific expression of human organic anion-transporting polypeptide 1B1 (SLCO1B1).
abstract: Human organic anion-transporting polypeptide 1B1 (OATP1B1) is an important hepatic uptake transporter that can transport a wide variety of drugs. In the present study, we have generated and characterized a transgenic mouse model with specific and functional expression of human OATP1B1 (SLCO1B1) in the liver. Immunohistochemical staining revealed basolateral localization of transgenic OATP1B1 in the liver, whereas no expression of OATP1B1 was found in the kidney and small intestine. Using this transgenic model, the in vivo role of human OATP1B1 in the disposition of the anticancer drug methotrexate (MTX) was studied. In mice on a semisynthetic diet, the area under the plasma concentration-time curve for intravenous methotrexate in SLCO1B1 transgenic mice was 1.5-fold decreased compared with wild-type mice. Furthermore, the amount of MTX in the liver was markedly higher ( approximately 2-fold) in the SLCO1B1 transgenic mice compared with wild-type mice, resulting in 2- to 4-fold higher liver-plasma ratios of MTX. Some murine liver Slco genes were markedly down-regulated on the semisynthetic diet compared with a standard diet, which probably reduced murine Oatp-mediated MTX uptake in the liver and therefore facilitated detection of the function of the transgenic OATP1B1. Taken together, these data demonstrate a marked and possibly rate-limiting role for human OATP1B1 in MTX elimination in vivo. Variation in OATP1B1 activity due to genetic polymorphisms, drug-drug interactions, and possibly dietary conditions may therefore play a role in the severity of MTX-related toxicity. SLCO1B1 transgenic mice could be a useful tool in studying the in vivo role of human OATP1B1 in drug pharmacokinetics.
authors.affiliation: Division of Experimental Therapy, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands. a.schinkel@nki.nl.
authors.forename: Evita
authors.initials: E
authors.lastname: van de Steeg
authors.forename: Cornelia M M
authors.initials: CM
authors.lastname: van der Kruijssen
authors.forename: Els
authors.initials: E
authors.lastname: Wagenaar
authors.forename: Johanna E C
authors.initials: JE
authors.lastname: Burggraaff
authors.forename: Elly
authors.initials: E
authors.lastname: Mesman
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Kenworthy
authors.forename: Alfred H
authors.initials: AH
authors.lastname: Schinkel
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004032:Diet; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008727:Methotrexate / Q000493:pharmacokinetics* / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism*; D029362:Organic Anion Transporters, Sodium-Independent / Q000235:genetics / Q000378:metabolism*; D011110:Polymorphism, Genetic; D051381:Rats
chemical_list: D027361:Organic Anion Transporters; D029362:Organic Anion Transporters, Sodium-Independent; D008727:Methotrexate