Measurement of Hepatic ABCB1 and ABCG2 Transport Activity with [11C]Tariquidar and PET in Humans and Mice.

Abstract

P-Glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) in the canalicular membrane of hepatocytes mediate the biliary excretion of drugs and drug metabolites. To measure hepatic ABCB1 and ABCG2 activity, we performed positron emission tomography (PET) scans with the ABCB1/ABCG2 substrate [11C]tariquidar in healthy volunteers and wild-type, Abcb1a/b(-/-), Abcg2(-/-), and Abcb1a/b(-/-)Abcg2(-/-) mice without and with coadministration of unlabeled tariquidar. PET data were analyzed with a three-compartment pharmacokinetic model. [11C]Tariquidar underwent hepatobiliary excretion in both humans and mice, and tariquidar coadministration caused a significant reduction in the rate constant for the transfer of radioactivity from the liver into bile (by -74% in humans and by -62% in wild-type mice), suggesting inhibition of canalicular efflux transporter activity. Radio-thin-layer chromatography analysis revealed that the majority of radioactivity (>87%) in the mouse liver and bile was composed of unmetabolized [11C]tariquidar. PET data in transporter knockout mice revealed that both ABCB1 and ABCG2 mediated biliary excretion of [11C]tariquidar. In vitro experiments indicated that tariquidar is not a substrate of major hepatic basolateral uptake transporters (SLCO1B1, SLCO1B3, SLCO2B1, SLC22A1, and SLC22A3). Our data suggest that [11C]tariquidar can be used to measure hepatic canalicular ABCB1/ABCG2 transport activity without a confounding effect of uptake transporters.

• Authors: Irene Hernández Lozano, Martin Bauer, Beatrix Wulkersdorfer, Alexander Traxl, Cécile Philippe, Maria Weber, Stephanie Häusler, Bruno Stieger, Walter Jäger, Severin Mairinger, Thomas Wanek, Marcus Hacker, Markus Zeitlinger, Oliver Langer
• Journal: Molecular pharmaceutics (Mol Pharm) Vol. 17 Issue 1 Pg. 316-326 (01 06 2020) ISSN: 1543-8392 [Electronic] United States
• PMID: 31790256 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ABCB1 protein, human
• ABCG2 protein, human
• ATP Binding Cassette Transporter, Subfamily B
• ATP Binding Cassette Transporter, Subfamily G, Member 2
• Abcg2 protein, mouse
• Carbon Isotopes
• Neoplasm Proteins
• Quinolines
• Radiopharmaceuticals
• tariquidar

Topics

• ATP Binding Cassette Transporter, Subfamily B (metabolism)
• ATP Binding Cassette Transporter, Subfamily G, Member 2 (genetics, metabolism)
• Adult
• Animals
• Bile (metabolism)
• Carbon Isotopes (chemistry)
• Gallbladder (diagnostic imaging)
• Humans
• Liver (diagnostic imaging, metabolism)
• Male
• Mice
• Mice, Knockout
• Neoplasm Proteins (metabolism)
• Positron-Emission Tomography
• Quinolines (chemistry, pharmacokinetics)
• Radiopharmaceuticals (pharmacokinetics)
• Tissue Distribution