Substrate-dependent ligand inhibition of the human organic cation transporter OCT2

Mathew Belzer, Mark Morales, Bhumasamudram Jagadish, Eugene A Mash, Stephen Wright

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

Organic cation transporter 2 (OCT2) mediates the initial step in renal secretion of organic cations: uptake from the blood, across the basolateral membrane, and into the renal proximal tubule cells. Because of its potential as a target for unwanted drug-drug interactions (DDIs), considerable attention has been directed toward understanding the basis of OCT2 selectivity. These studies typically assess selectivity based on ligand inhibition profiles for OCT2-mediated transport of a probe substrate. However, little attention has been given to the potential influence of the substrate on the profile of ligand inhibition. Here we compared the IC50 values obtained for a set of structurally distinct inhibitors against OCT2-mediated transport of three structurally distinct substrates: 1-methyl-4-phenylpyridinium (MPP); metformin; and a novel fluorescent substrate, N,N,Ntrimethyl- 2-[methyl(7-nitrobenzo[c][l, 2,5]oxadiazol-4-yl)amino] ethanaminium iodide (NBD-MTMA). The median IC 50 value for inhibition of MPP transport was 9-fold higher than that for inhibition of metformin transport. Similarly, the median IC50 value for inhibition of MPP transport was 5-fold higher than that for NBD-MTMA transport. However, this was not a systematic difference in inhibitory efficacy; the ratio of IC50 values, MPP versus NBD-MTMA, ranged from 88-fold (ipratropium) to 0.3-fold (metformin). These data show that 1) the choice of OCT2 substrate significantly influences both quantitative and qualitative inhibitory interactions with cationic drugs; and 2) ligand interactions with OCT2 are not restricted to competition for a common ligand binding site, consistent with a binding surface characterized by multiple, possibly overlapping interaction sites. Development of predictive models of DDIs with OCT2 must take into account the substrate dependence of ligand interaction with this protein.

Original languageEnglish (US)
Pages (from-to)300-310
Number of pages11
JournalJournal of Pharmacology and Experimental Therapeutics
Volume346
Issue number2
DOIs
StatePublished - Aug 2013

Fingerprint

Cations
1-Methyl-4-phenylpyridinium
Ligands
Metformin
Inhibitory Concentration 50
Drug Interactions
Organic Cation Transporter 1
Pharmaceutical Preparations
Ipratropium
Proximal Kidney Tubule
Iodides
Binding Sites
Kidney
Membranes
N,N,N-trimethyl-2-(methyl(7-nitrobenzo(c)(l,2,5)oxadiazol-4-yl)amino)ethanaminium
Proteins

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine

Cite this

Substrate-dependent ligand inhibition of the human organic cation transporter OCT2. / Belzer, Mathew; Morales, Mark; Jagadish, Bhumasamudram; Mash, Eugene A; Wright, Stephen.

In: Journal of Pharmacology and Experimental Therapeutics, Vol. 346, No. 2, 08.2013, p. 300-310.

Research output: Contribution to journalArticle

@article{b5eeeb19c9e64e969a994bde2254f54c,
title = "Substrate-dependent ligand inhibition of the human organic cation transporter OCT2",
abstract = "Organic cation transporter 2 (OCT2) mediates the initial step in renal secretion of organic cations: uptake from the blood, across the basolateral membrane, and into the renal proximal tubule cells. Because of its potential as a target for unwanted drug-drug interactions (DDIs), considerable attention has been directed toward understanding the basis of OCT2 selectivity. These studies typically assess selectivity based on ligand inhibition profiles for OCT2-mediated transport of a probe substrate. However, little attention has been given to the potential influence of the substrate on the profile of ligand inhibition. Here we compared the IC50 values obtained for a set of structurally distinct inhibitors against OCT2-mediated transport of three structurally distinct substrates: 1-methyl-4-phenylpyridinium (MPP); metformin; and a novel fluorescent substrate, N,N,Ntrimethyl- 2-[methyl(7-nitrobenzo[c][l, 2,5]oxadiazol-4-yl)amino] ethanaminium iodide (NBD-MTMA). The median IC 50 value for inhibition of MPP transport was 9-fold higher than that for inhibition of metformin transport. Similarly, the median IC50 value for inhibition of MPP transport was 5-fold higher than that for NBD-MTMA transport. However, this was not a systematic difference in inhibitory efficacy; the ratio of IC50 values, MPP versus NBD-MTMA, ranged from 88-fold (ipratropium) to 0.3-fold (metformin). These data show that 1) the choice of OCT2 substrate significantly influences both quantitative and qualitative inhibitory interactions with cationic drugs; and 2) ligand interactions with OCT2 are not restricted to competition for a common ligand binding site, consistent with a binding surface characterized by multiple, possibly overlapping interaction sites. Development of predictive models of DDIs with OCT2 must take into account the substrate dependence of ligand interaction with this protein.",
author = "Mathew Belzer and Mark Morales and Bhumasamudram Jagadish and Mash, {Eugene A} and Stephen Wright",
year = "2013",
month = "8",
doi = "10.1124.jpet.113.203257",
language = "English (US)",
volume = "346",
pages = "300--310",
journal = "Journal of Pharmacology and Experimental Therapeutics",
issn = "0022-3565",
publisher = "American Society for Pharmacology and Experimental Therapeutics",
number = "2",

}

TY - JOUR

T1 - Substrate-dependent ligand inhibition of the human organic cation transporter OCT2

AU - Belzer, Mathew

AU - Morales, Mark

AU - Jagadish, Bhumasamudram

AU - Mash, Eugene A

AU - Wright, Stephen

PY - 2013/8

Y1 - 2013/8

N2 - Organic cation transporter 2 (OCT2) mediates the initial step in renal secretion of organic cations: uptake from the blood, across the basolateral membrane, and into the renal proximal tubule cells. Because of its potential as a target for unwanted drug-drug interactions (DDIs), considerable attention has been directed toward understanding the basis of OCT2 selectivity. These studies typically assess selectivity based on ligand inhibition profiles for OCT2-mediated transport of a probe substrate. However, little attention has been given to the potential influence of the substrate on the profile of ligand inhibition. Here we compared the IC50 values obtained for a set of structurally distinct inhibitors against OCT2-mediated transport of three structurally distinct substrates: 1-methyl-4-phenylpyridinium (MPP); metformin; and a novel fluorescent substrate, N,N,Ntrimethyl- 2-[methyl(7-nitrobenzo[c][l, 2,5]oxadiazol-4-yl)amino] ethanaminium iodide (NBD-MTMA). The median IC 50 value for inhibition of MPP transport was 9-fold higher than that for inhibition of metformin transport. Similarly, the median IC50 value for inhibition of MPP transport was 5-fold higher than that for NBD-MTMA transport. However, this was not a systematic difference in inhibitory efficacy; the ratio of IC50 values, MPP versus NBD-MTMA, ranged from 88-fold (ipratropium) to 0.3-fold (metformin). These data show that 1) the choice of OCT2 substrate significantly influences both quantitative and qualitative inhibitory interactions with cationic drugs; and 2) ligand interactions with OCT2 are not restricted to competition for a common ligand binding site, consistent with a binding surface characterized by multiple, possibly overlapping interaction sites. Development of predictive models of DDIs with OCT2 must take into account the substrate dependence of ligand interaction with this protein.

AB - Organic cation transporter 2 (OCT2) mediates the initial step in renal secretion of organic cations: uptake from the blood, across the basolateral membrane, and into the renal proximal tubule cells. Because of its potential as a target for unwanted drug-drug interactions (DDIs), considerable attention has been directed toward understanding the basis of OCT2 selectivity. These studies typically assess selectivity based on ligand inhibition profiles for OCT2-mediated transport of a probe substrate. However, little attention has been given to the potential influence of the substrate on the profile of ligand inhibition. Here we compared the IC50 values obtained for a set of structurally distinct inhibitors against OCT2-mediated transport of three structurally distinct substrates: 1-methyl-4-phenylpyridinium (MPP); metformin; and a novel fluorescent substrate, N,N,Ntrimethyl- 2-[methyl(7-nitrobenzo[c][l, 2,5]oxadiazol-4-yl)amino] ethanaminium iodide (NBD-MTMA). The median IC 50 value for inhibition of MPP transport was 9-fold higher than that for inhibition of metformin transport. Similarly, the median IC50 value for inhibition of MPP transport was 5-fold higher than that for NBD-MTMA transport. However, this was not a systematic difference in inhibitory efficacy; the ratio of IC50 values, MPP versus NBD-MTMA, ranged from 88-fold (ipratropium) to 0.3-fold (metformin). These data show that 1) the choice of OCT2 substrate significantly influences both quantitative and qualitative inhibitory interactions with cationic drugs; and 2) ligand interactions with OCT2 are not restricted to competition for a common ligand binding site, consistent with a binding surface characterized by multiple, possibly overlapping interaction sites. Development of predictive models of DDIs with OCT2 must take into account the substrate dependence of ligand interaction with this protein.

UR - http://www.scopus.com/inward/record.url?scp=84880428300&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84880428300&partnerID=8YFLogxK

U2 - 10.1124.jpet.113.203257

DO - 10.1124.jpet.113.203257

M3 - Article

VL - 346

SP - 300

EP - 310

JO - Journal of Pharmacology and Experimental Therapeutics

JF - Journal of Pharmacology and Experimental Therapeutics

SN - 0022-3565

IS - 2

ER -