Baojian Wu1, Wen Jiang, Taijun Yin, Song Gao, Ming Hu. 1. Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston, 1441 Moursund Street, Houston, Texas 77030, USA.
Abstract
PURPOSE: The efflux transporter breast cancer resistance protein (BCRP/ABCG2) plays an important role in excretion of anionic drugs and metabolites including glucuronides in humans. METHODS: In this article, our recently published cell model (i.e., HeLa cells over-expressing UGT1A9 (HeLa1A9)) is used to determine the kinetic parameters of BCRP-mediated transport of glucuronides. RESULTS: After incubation of the aglycone with the cells, a steady-state (i.e., zero-order or near zero-order) excretion of its glucuronide is rapidly achieved and then maintained. Kinetic profiling with different (intracellular) glucuronide concentrations and their corresponding excretion rates is enabled by varying the concentration of the aglycone, which allows for the determination of kinetic parameters responsible for BCRP-mediated efflux of glucuronides. This approach was validated theoretically using a cellular pharmacokinetic model incorporating various enzymatic and transporter-mediated kinetic processes. It was also validated experimentally in that kinetic parameters of efflux of glucuronides of 6-hydroxyflavone and 4-methylumberiferone in the HeLa1A9 cell model were shown to be consistent with those derived with BCRP-overexpressing membrane vesicles. CONCLUSION: This study provides a new strategy for rapidly evaluating the kinetics of glucuronide efflux by BCRP.
PURPOSE: The efflux transporter breast cancer resistance protein (BCRP/ABCG2) plays an important role in excretion of anionic drugs and metabolites including glucuronides in humans. METHODS: In this article, our recently published cell model (i.e., HeLa cells over-expressing UGT1A9 (HeLa1A9)) is used to determine the kinetic parameters of BCRP-mediated transport of glucuronides. RESULTS: After incubation of the aglycone with the cells, a steady-state (i.e., zero-order or near zero-order) excretion of its glucuronide is rapidly achieved and then maintained. Kinetic profiling with different (intracellular) glucuronide concentrations and their corresponding excretion rates is enabled by varying the concentration of the aglycone, which allows for the determination of kinetic parameters responsible for BCRP-mediated efflux of glucuronides. This approach was validated theoretically using a cellular pharmacokinetic model incorporating various enzymatic and transporter-mediated kinetic processes. It was also validated experimentally in that kinetic parameters of efflux of glucuronides of 6-hydroxyflavone and 4-methylumberiferone in the HeLa1A9 cell model were shown to be consistent with those derived with BCRP-overexpressing membrane vesicles. CONCLUSION: This study provides a new strategy for rapidly evaluating the kinetics of glucuronide efflux by BCRP.
Authors: Clinton F Stewart; Markos Leggas; John D Schuetz; John C Panetta; Pamela J Cheshire; Jennifer Peterson; Najat Daw; Jesse J Jenkins; Richard Gilbertson; Glen S Germain; Franklin C Harwood; Peter J Houghton Journal: Cancer Res Date: 2004-10-15 Impact factor: 12.701
Authors: John T Szilagyi; Ludwik Gorczyca; Anita Brinker; Brian Buckley; Jeffrey D Laskin; Lauren M Aleksunes Journal: Toxicol Sci Date: 2019-04-01 Impact factor: 4.849