Abstract
Membrane transporters can play a clinically important role in drug absorption and disposition; Caco-2 and Madin-Darby canine kidney (MDCK) cells are the most widely used in vitro models for studying the functions of these transporters and associated drug interactions. Transport studies using these cell models are mostly focused on apical transporters, whereas basolateral drug transport processes are largely ignored. However, for some hydrophilic drugs, a basolateral uptake transporter may be required for drugs to enter cells before they can interact with apical efflux transporters. The objective of this study was to evaluate potential differences in drug transport across Caco-2 and MDCK basolateral membrane that could cause discrepancy in the identification of efflux transporter substrates and to elucidate the underlying factors that may cause such differences, using rosuvastatin as a model substrate. Bidirectional transport results in Caco-2 and breast cancer resistance protein-MDCK cells demonstrated the necessity of an uptake transporter at the basolateral membrane for rosuvastatin. Kinetic study revealed saturable and nonsaturable processes for rosuvastatin uptake across the Caco-2 basolateral membrane, with the saturable process encompassing >75% of overall rosuvastatin basolateral uptake at concentrations below the Km (4.2 μM). Furthermore, rosuvastatin basolateral transport exhibited cis-inhibition and trans-stimulation phenomena, indicating a facilitated diffusion mechanism. This basolateral transporter appeared to be a prerequisite for rosuvastatin and perhaps for other hydrophilic substrates to interact with apical efflux transporters. Deficit of such a basolateral transporter in certain cell models may lead to false-negative results when screening drug interactions with apical efflux transporters.
Footnotes
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
ABBREVIATIONS:
- DDI
- drug-drug interaction
- A
- apical
- B
- basolateral
- BCRP
- breast cancer resistance protein
- Caco-2
- human epithelial colorectal adenocarcinoma cells
- HBSS
- Hanks' balanced salt solution
- MDCK
- Madin-Darby canine kidney cells
- OATP
- organic anion-transporting polypeptide
- OST
- organic solute transporter
- Papp
- apparent permeability coefficient
- P-gp
- P-glycoprotein
- qPCR
- real-time quantitative polymerase chain reaction
- NTCP
- Na+-taurocholate cotransporting polypeptide
- ER
- efflux ratio
- Ko143
- 3-(6-isobutyl-9-methoxy-1,4-dioxo-1,2,3,4,6,7,12,12α-octahydropyrazino[1′,2′:1,6]pyrido[3,4-b]indol-3-yl)-propionic acid tert-butyl ester.
- Received March 10, 2012.
- Accepted August 1, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|