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Wittern CI, Schröder S, Jensen O, Brockmöller J, Gebauer L. Comprehensive characterization of the OCT1 phenylalanine-244-alanine substitution reveals highly substrate-dependent effects on transporter function. J Biol Chem 2024:107835. [PMID: 39342994 DOI: 10.1016/j.jbc.2024.107835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 09/09/2024] [Accepted: 09/18/2024] [Indexed: 10/01/2024] Open
Abstract
Organic cation transporters (OCTs) can transport structurally highly diverse substrates. The molecular basis of this extensive polyspecificity has been further elucidated by cryogenic electron microscopy. Apparently, in addition to negatively charged amino acids, aromatic residues may contribute to substrate binding and substrate selectivity. In this study, we provide a comprehensive characterization of phenylalanine 244 in OCT1 function. We analyzed the uptake of 144 OCT1 substrates for the phenylalanine 244 to alanine substitution compared to wild-type OCT1. This substitution had highly substrate-specific effects ranging from transport reduced to 10% of wild-type activity up to 8-fold increased transport rates. Four percent of substrates showed strongly increased uptake (> 200% of wild type) whereas 39% showed strongly reduced transport (< 50% of wild type). Particularly with larger, more hydrophobic, and more aromatic substrates, the Phe244Ala substitution resulted in higher transport rates and lower inhibition of the transporter. In contrast, substrates with a lower molecular weight and less aromatic rings showed generally decreased uptake rates. A comparison of our data to available transport kinetic data demonstrates that generally, high-affinity low-capacity substrates show increased uptake by the Phe244Ala substitution whereas low-affinity high-capacity substrates are characterized by reduced transport rates. Altogether, our study provides the first comprehensive characterization of the functional role of an aromatic amino acid within the substrate translocation pathway of OCT1. The pleiotropic function further highlights that Phenylalanine 244 interacts in a highly specific manner with OCT1 substrates and inhibitors.
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Affiliation(s)
- Carla Isabel Wittern
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Sophie Schröder
- Department for Epigenetics and Systems Medicine in Neurodegenerative Diseases, German Center for Neurodegenerative Diseases (DZNE), D-37075 Göttingen, Germany
| | - Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany.
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2
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Okubo K, Kudo T, Yoshihara S, Nakabayashi Y, Nakauchi K, Tanaka A, Saito M, Tsujisawa A, Goda H, Yamagishi Y, Otake C, Makino K, Takahashi H, Ito K. Physiologically based pharmacokinetic model analysis of the inhibitory effect of vonoprazan on the metabolic activation of proguanil. Drug Metab Pharmacokinet 2024; 54:100537. [PMID: 38086197 DOI: 10.1016/j.dmpk.2023.100537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 09/15/2023] [Accepted: 10/30/2023] [Indexed: 02/06/2024]
Abstract
We previously reported that repeated oral administration of vonoprazan (VPZ) followed by oral administration of proguanil (PG) in healthy adults increased blood concentration of PG and decreased blood concentration of its metabolite cycloguanil (CG) compared with administration of PG alone. In this study, we investigated whether this interaction can be quantitatively explained by VPZ inhibition of PG metabolism. In an in vitro study using human liver microsomes, VPZ inhibited CG formation from PG in a concentration-dependent manner, and the inhibition was enhanced depending on preincubation time. Then, a physiologically based pharmacokinetic (PBPK) model analysis was performed incorporating the obtained inhibition parameters. By fitting the blood concentration profiles of VPZ and PG/CG after VPZ and PG were orally administered alone to our PBPK model, parameters were obtained which can reproduce their concentration profiles. In contrast, when the VPZ inhibition parameters for CG formation from the in vitro study were incorporated, the predicted blood PG and CG concentrations were unchanged; the apparent dissociation constant had to be set to about 1/23 of the obtained in vitro value to reproduce the observed interaction. Further comprehensive evaluation is required, including the possibility that mechanisms other than metabolic inhibition may be involved.
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Affiliation(s)
- Kenjiro Okubo
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Toshiyuki Kudo
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan; Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan.
| | - Sae Yoshihara
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Yu Nakabayashi
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Kana Nakauchi
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Akimi Tanaka
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Moe Saito
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Ayumi Tsujisawa
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Hitomi Goda
- Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan
| | - Yoshiaki Yamagishi
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan; Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan.
| | - Chinatsu Otake
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan
| | - Kosho Makino
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan.
| | - Hideyo Takahashi
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba, 278-8510, Japan.
| | - Kiyomi Ito
- Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan; Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo, 202-8585, Japan.
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3
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Gebauer L, Jensen O, Rafehi M, Brockmöller J. Stereoselectivity in Cell Uptake by SLC22 Organic Cation Transporters 1, 2, and 3. J Med Chem 2023; 66:15990-16001. [PMID: 38052451 PMCID: PMC10726348 DOI: 10.1021/acs.jmedchem.3c01436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 10/30/2023] [Accepted: 11/24/2023] [Indexed: 12/07/2023]
Abstract
Stereoselectivity can be most relevant in drug metabolism and receptor binding. Although drug membrane transport might be equally important for small-molecule pharmacokinetics, the extent of stereoselectivity in membrane transport is largely unknown. Here, we characterized the stereoselective transport of 18 substrates of SLC22 organic cation transporters (OCTs) 1, 2, and 3. OCT2 and OCT3 showed highly stereoselective cell uptake with several substrates and, interestingly, often with opposite stereoselectivity. In contrast, transport by OCT1 was less stereoselective, although (R)-tamsulosin was transported by OCT1 with higher apparent affinity than the (S)-enantiomer. Using OCT1 and CYP2D6 co-overexpressing cells, an additive effect of the stereoselectivities was demonstrated. This indicates that pharmacokinetic stereoselectivity may be the result of combined effects in transport and metabolism. This study highlights that the pronounced polyspecificity of OCTs not contradicts stereoselectivity in the transport. Nevertheless, stereoselectivity is highly substrate-specific and for most substrates and OCTs, there was no major selectivity.
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Affiliation(s)
- Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
| | - Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
| | - Muhammad Rafehi
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
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4
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Lu Y, Zhang W, Zhang Y, Wu S, Ma M, Peng X, Zeng Z, Zeng D. Metabolite Identification of Isopropoxy Benzene Guanidine in Rat Liver Microsomes by Using UHPLC-Q-TOF-MS/MS. Int J Mol Sci 2023; 24:ijms24087313. [PMID: 37108473 PMCID: PMC10138866 DOI: 10.3390/ijms24087313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/07/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Isopropoxy benzene guanidine (IBG) is a guanidine derivative with antibacterial activity against multidrug-resistant bacteria. A few studies have revealed the metabolism of IBG in animals. The aim of the current study was to identify potential metabolic pathways and metabolites of IBG. The detection and characterization of metabolites were performed with high-performance liquid chromatography tandem mass spectrometry (UHPLC-Q-TOF-MS/MS). Seven metabolites were identified from the microsomal incubated samples by using the UHPLC-Q-TOF-MS/MS system. The metabolic pathways of IBG in the rat liver microsomes involved O-dealkylation, oxygenation, cyclization, and hydrolysis. Hydroxylation was the main metabolic pathway of IBG in the liver microsomes. This research investigated the in vitro metabolism of IBG to provide a basis for the further pharmacology and toxicology of this compound.
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Affiliation(s)
- Yixing Lu
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
| | - Wanying Zhang
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
| | - Yongxiang Zhang
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
| | - Sujuan Wu
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
| | - Minglang Ma
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
| | - Xianfeng Peng
- Guangzhou Insighter Biotechnology Co., Ltd., Guangzhou 510663, China
| | - Zhenling Zeng
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
| | - Dongping Zeng
- Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, Guangzhou 510642, China
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5
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Evaluation of CYP2C19-Mediated Pharmacokinetic Drug Interaction of Tegoprazan, Compared with Vonoprazan or Esomeprazole. Clin Pharmacokinet 2023; 62:599-608. [PMID: 36897544 PMCID: PMC10085907 DOI: 10.1007/s40262-023-01228-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2023] [Indexed: 03/11/2023]
Abstract
BACKGROUND AND OBJECTIVE CYP2C19-mediated drug interactions of acid-reducing agents are clinically important given the high possibility of concomitant administration with CYP2C19 substrates. This study aimed to evaluate the effect of tegoprazan on the pharmacokinetics (PK) of a CYP2C19 substrate, proguanil, compared with vonoprazan or esomeprazole. METHODS A two-part, randomized, open-label, two-sequence, three-period crossover study was conducted in 16 healthy CYP2C19 extensive metabolizers (eight subjects per part). In each period, a single oral dose of atovaquone/proguanil 250/100 mg was administered alone or co-administered with tegoprazan 50 mg, esomeprazole 40 mg (Part 1 only) or vonoprazan 20 mg (Part 2 only). The plasma and urine concentrations of proguanil and its metabolite, cycloguanil, were measured up to 48 h post-dose. PK parameters were calculated using a non-compartmental method and compared between administered alone and co-administered with tegoprazan, vonoprazan or esomeprazole. RESULTS Co-administration of tegoprazan did not significantly affect the systemic exposure of proguanil and cycloguanil. In contrast, co-administration of vonoprazan or esomeprazole increased proguanil systemic exposure and decreased cycloguanil systemic exposure, and the magnitude of the corresponding change was greater with esomeprazole co-administration than vonoprazan co-administration. CONCLUSION Tegoprazan, unlike vonoprazan and esomeprazole, exhibited negligible CYP2C19-mediated PK interaction. It suggests that as an alternative to other acid-reducing agents, tegoprazan can be used concomitantly with CYP2C19 substrates in clinical settings. TRIAL REGISTRATION Clinicaltrials.gov identifier: NCT04568772 (Registered on September 29, 2020).
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Nies AT, Schaeffeler E, Schwab M. Hepatic solute carrier transporters and drug therapy: Regulation of expression and impact of genetic variation. Pharmacol Ther 2022; 238:108268. [DOI: 10.1016/j.pharmthera.2022.108268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/25/2022] [Accepted: 08/15/2022] [Indexed: 11/30/2022]
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7
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Gebauer L, Jensen O, Brockmöller J, Dücker C. Substrates and Inhibitors of the Organic Cation Transporter 3 and Comparison with OCT1 and OCT2. J Med Chem 2022; 65:12403-12416. [PMID: 36067397 DOI: 10.1021/acs.jmedchem.2c01075] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Organic cation transporters (OCTs) 1, 2, and 3 facilitate cellular uptake of structurally diverse endogenous and exogenous substances. However, their substrate and inhibitor specificity are not fully understood. We performed a broad in vitro screening for OCT3 substrates and inhibitors, allowing us to compare the substrate spectra and to study the relationship between transport and inhibition of transport. Generally, substrates were smaller and more hydrophilic than OCT3 inhibitors. The best model-based predictor of transport was the positive charge, while the best predictor of inhibition was the aromatic ring count. OCT3 inhibition was well correlated between different model substrates. Substrates of OCT3 were mainly weak inhibitors, and the best inhibitors were not substrates. As tested with 264 substances, OCT3 transport had significantly more overlap with OCT2 than OCT1. Our data further substantiate that specificity of OCT transport varies with minor substitutions rather than with the general scaffolds of substrates.
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Affiliation(s)
- Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
| | - Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
| | - Christof Dücker
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Straße 40, D-37075 Göttingen, Germany
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8
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Liu X, Li W, Zhang H, Wang X, Huang Y, Li Y, Pan G. Biodistribution and pharmacokinetic profile of berberine and its metabolites in hepatocytes. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2022; 104:154288. [PMID: 35785560 DOI: 10.1016/j.phymed.2022.154288] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/09/2022] [Accepted: 06/18/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Berberine has been shown in clinical studies to have many health benefits, including anti-inflammatory and antioxidant properties, along with gut-flora balancing properties. However, its clinical efficacy is hindered by its low oral bioavailability and rapid metabolism. PURPOSE This study aims to identify the berberine metabolites' forms and characterize their biodistribution patterns in and out of HepG2 cells. METHODS The qualitative analysis of metabolites of berberine in HepG2 cells was performed using the LC/MSn-IT-TOF method. Subsequent cellular pharmacokinetics characterization of intracellular and extracellular berberine and its metabolites was performed by LC-MS/MS analysis. RESULTS Berberine's metabolites of phase I metabolism were demethyleneberberine, jatrorrhizine, columbamine, berberrubine, etc., while its phase II metabolites were sulfate and glucuronide conjugates of phase I metabolites. Among the phase I metabolites of berberine, jatrorrhizine+columbamine accounted for over two-thirds of the total, followed by demethyleneberberine, which accounted for about a quarter. The intracellular demethyleneberberine is 25.14 times more enriched than extracellular demethyleneberberine. On the other hand, jatrorrhizine+columbamine and berberrubine were primarily distributed extracellularly, and their extracellular concentrations were 7.13 times and 15.61 times of their intracellular concentrations, respectively. Berberine metabolites produced in phase II metabolism are predominantly sulfate conjugates. CONCLUSION Our results show that demethyleneberberine is highly concentrated intracellularly in HepG2, possibly because it is an essential metabolite of berberine that likely contributes to berberine's efficacy. In light of our findings, berberine's poor plasma concentration-effectiveness characteristics have been partially explained.
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Affiliation(s)
- Xiaomei Liu
- Tianjin University of Traditional Chinese Medicine, 10 Poyanghu Road, Jinghai, Tianjin 301617, China
| | - Wenfang Li
- Tianjin University of Traditional Chinese Medicine, 10 Poyanghu Road, Jinghai, Tianjin 301617, China
| | - Han Zhang
- Tianjin University of Traditional Chinese Medicine, 10 Poyanghu Road, Jinghai, Tianjin 301617, China
| | - Xiaoming Wang
- Tianjin University of Traditional Chinese Medicine, 10 Poyanghu Road, Jinghai, Tianjin 301617, China.
| | - Yuhong Huang
- Second Affiliated Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300250, China
| | - Yuhong Li
- Tianjin University of Traditional Chinese Medicine, 10 Poyanghu Road, Jinghai, Tianjin 301617, China
| | - Guixiang Pan
- Second Affiliated Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin 300250, China.
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9
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Giacomini KM, Yee SW, Koleske ML, Zou L, Matsson P, Chen EC, Kroetz DL, Miller MA, Gozalpour E, Chu X. New and Emerging Research on Solute Carrier and ATP Binding Cassette Transporters in Drug Discovery and Development: Outlook From the International Transporter Consortium. Clin Pharmacol Ther 2022; 112:540-561. [PMID: 35488474 PMCID: PMC9398938 DOI: 10.1002/cpt.2627] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/16/2022] [Indexed: 02/06/2023]
Abstract
Enabled by a plethora of new technologies, research in membrane transporters has exploded in the past decade. The goal of this state-of-the-art article is to describe recent advances in research on membrane transporters that are particularly relevant to drug discovery and development. This review covers advances in basic, translational, and clinical research that has led to an increased understanding of membrane transporters at all levels. At the basic level, we describe the available crystal structures of membrane transporters in both the solute carrier (SLC) and ATP binding cassette superfamilies, which has been enabled by the development of cryogenic electron microscopy methods. Next, we describe new research on lysosomal and mitochondrial transporters as well as recently deorphaned transporters in the SLC superfamily. The translational section includes a summary of proteomic research, which has led to a quantitative understanding of transporter levels in various cell types and tissues and new methods to modulate transporter function, such as allosteric modulators and targeted protein degraders of transporters. The section ends with a review of the effect of the gut microbiome on modulation of transporter function followed by a presentation of 3D cell cultures, which may enable in vivo predictions of transporter function. In the clinical section, we describe new genomic and pharmacogenomic research, highlighting important polymorphisms in transporters that are clinically relevant to many drugs. Finally, we describe new clinical tools, which are becoming increasingly available to enable precision medicine, with the application of tissue-derived small extracellular vesicles and real-world biomarkers.
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Affiliation(s)
- Kathleen M. Giacomini
- Department of Bioengineering and Therapeutic SciencesUniversity of California, San FranciscoSan FranciscoCaliforniaUSA
| | - Sook W. Yee
- Department of Bioengineering and Therapeutic SciencesUniversity of California, San FranciscoSan FranciscoCaliforniaUSA
| | - Megan L. Koleske
- Department of Bioengineering and Therapeutic SciencesUniversity of California, San FranciscoSan FranciscoCaliforniaUSA
| | - Ling Zou
- Pharmacokinetics and Drug MetabolismAmgen Inc.South San FranciscoCaliforniaUSA
| | - Pär Matsson
- Department of PharmacologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Eugene C. Chen
- Department of Drug Metabolism and PharmacokineticsGenentech, Inc.South San FranciscoCaliforniaUSA
| | - Deanna L. Kroetz
- Department of Bioengineering and Therapeutic SciencesUniversity of California, San FranciscoSan FranciscoCaliforniaUSA
| | - Miles A. Miller
- Center for Systems BiologyMassachusetts General HospitalBostonMassachusettsUSA
| | - Elnaz Gozalpour
- Drug Safety and MetabolismIMED Biotech UnitSafety and ADME Translational Sciences DepartmentAstraZeneca R&DCambridgeUK
| | - Xiaoyan Chu
- Department of ADME and Discovery ToxicologyMerck & Co. IncKenilworthNew JerseyUSA
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10
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Overlap and Specificity in the Substrate Spectra of Human Monoamine Transporters and Organic Cation Transporters 1, 2, and 3. Int J Mol Sci 2021; 22:ijms222312816. [PMID: 34884618 PMCID: PMC8657982 DOI: 10.3390/ijms222312816] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 11/24/2021] [Accepted: 11/24/2021] [Indexed: 12/23/2022] Open
Abstract
Human monoamine transporters (MATs) are cation transporters critically involved in neuronal signal transmission. While inhibitors of MATs have been intensively studied, their substrate spectra have received far less attention. Polyspecific organic cation transporters (OCTs), predominantly known for their role in hepatic and renal drug elimination, are also expressed in the central nervous system and might modulate monoaminergic signaling. Using HEK293 cells overexpressing MATs or OCTs, we compared uptake of 48 compounds, mainly phenethylamine and tryptamine derivatives including matched molecular pairs, across noradrenaline, dopamine and serotonin transporters and OCTs (1, 2, and 3). Generally, MATs showed surprisingly high transport activities for numerous analogs of neurotransmitters, but their substrate spectra were limited by molar mass. Human OCT2 showed the broadest substrate spectrum, and also the highest overlap with MATs substrates. Comparative kinetic analyses revealed that the radiotracer meta-iodobenzylguanidine had the most balanced uptake across all six transporters. Matched molecular pair analyses comparing MAT and OCT uptake using the same methodology could provide a better understanding of structural determinants for high cell uptake by MATs or OCTs. The data may result in a better understanding of pharmacokinetics and toxicokinetics of small molecular organic cations and, possibly, in the development of more specific radiotracers for MATs.
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11
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Meyer MJ, Tzvetkov MV. OCT1 Polyspecificity-Friend or Foe? Front Pharmacol 2021; 12:698153. [PMID: 34149437 PMCID: PMC8206551 DOI: 10.3389/fphar.2021.698153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/18/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Marleen J Meyer
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
| | - Mladen V Tzvetkov
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
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12
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Matthaei J, Brockmöller J, Steimer W, Pischa K, Leucht S, Kullmann M, Jensen O, Ouethy T, Tzvetkov MV, Rafehi M. Effects of Genetic Polymorphism in CYP2D6, CYP2C19, and the Organic Cation Transporter OCT1 on Amitriptyline Pharmacokinetics in Healthy Volunteers and Depressive Disorder Patients. Front Pharmacol 2021; 12:688950. [PMID: 34093211 PMCID: PMC8175851 DOI: 10.3389/fphar.2021.688950] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/04/2021] [Indexed: 12/23/2022] Open
Abstract
The tricyclic antidepressant amitriptyline is frequently prescribed but its use is limited by its narrow therapeutic range and large variation in pharmacokinetics. Apart from interindividual differences in the activity of the metabolising enzymes cytochrome P450 (CYP) 2D6 and 2C19, genetic polymorphism of the hepatic influx transporter organic cation transporter 1 (OCT1) could be contributing to interindividual variation in pharmacokinetics. Here, the impact of OCT1 genetic variation on the pharmacokinetics of amitriptyline and its active metabolite nortriptyline was studied in vitro as well as in healthy volunteers and in depressive disorder patients. Amitriptyline and nortriptyline were found to inhibit OCT1 in recombinant cells with IC50 values of 28.6 and 40.4 µM. Thirty other antidepressant and neuroleptic drugs were also found to be moderate to strong OCT1 inhibitors with IC50 values in the micromolar range. However, in 35 healthy volunteers, preselected for their OCT1 genotypes, who received a single dose of 25 mg amitriptyline, no significant effects on amitriptyline and nortriptyline pharmacokinetics could be attributed to OCT1 genetic polymorphism. In contrast, the strong impact of the CYP2D6 genotype on amitriptyline and nortriptyline pharmacokinetics and of the CYP2C19 genotype on nortriptyline was confirmed. In addition, acylcarnitine derivatives were measured as endogenous biomarkers for OCT1 activity. The mean plasma concentrations of isobutyrylcarnitine and 2-methylbutyrylcarnitine were higher in participants with two active OCT1 alleles compared to those with zero OCT1 activity, further supporting their role as endogenous in vivo biomarkers for OCT1 activity. A moderate reduction in plasma isobutyrylcarnitine concentrations occurred at the time points at which amitriptyline plasma concentrations were the highest. In a second, independent study sample of 50 patients who underwent amitriptyline therapy of 75 mg twice daily, a significant trend of increasing amitriptyline plasma concentrations with decreasing OCT1 activity was observed (p = 0.018), while nortriptyline plasma concentrations were unaffected by the OCT1 genotype. Altogether, this comprehensive study showed that OCT1 activity does not appear to be a major factor determining amitriptyline and nortriptyline pharmacokinetics and that hepatic uptake occurs mainly through other mechanisms.
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Affiliation(s)
- Johannes Matthaei
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Werner Steimer
- Institute for Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Konstanze Pischa
- Institute for Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Stefan Leucht
- Section Evidence Based Medicine in Psychiatry and Psychotherapy, Department of Psychiatry and Psychotherapy, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Maria Kullmann
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Typhaine Ouethy
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
| | - Mladen Vassilev Tzvetkov
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany.,Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
| | - Muhammad Rafehi
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Göttingen, Germany
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13
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Jensen O, Matthaei J, Klemp HG, Meyer MJ, Brockmöller J, Tzvetkov MV. Isobutyrylcarnitine as a Biomarker of OCT1 Activity and Interspecies Differences in its Membrane Transport. Front Pharmacol 2021; 12:674559. [PMID: 34040533 PMCID: PMC8141810 DOI: 10.3389/fphar.2021.674559] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/26/2021] [Indexed: 11/24/2022] Open
Abstract
Genome-wide association studies have identified an association between isobutyrylcarnitine (IBC) and organic cation transporter 1 (OCT1) genotypes. Higher IBC blood concentrations in humans with active OCT1 genotypes and experimental studies with mouse OCT1 suggested an OCT1-mediated efflux of IBC. In this study, we wanted to confirm the suggested use of IBC as an endogenous biomarker of OCT1 activity and contribute to a better understanding of the mechanisms behind the association between blood concentrations of carnitine derivatives and OCT1 genotype. Blood and urine IBC concentrations were quantified in healthy volunteers regarding intra- and interindividual variation and correlation with OCT1 genotype and with pharmacokinetics of known OCT1 substrates. Furthermore, IBC formation and transport were studied in cell lines overexpressing OCT1 and its naturally occurring variants. Carriers of high-activity OCT1 genotypes had about 3-fold higher IBC blood concentrations and 2-fold higher amounts of IBC excreted in urine compared to deficient OCT1. This was likely due to OCT1 function, as indicated by the fact that IBC correlated with the pharmacokinetics of known OCT1 substrates, like fenoterol, and blood IBC concentrations declined with a 1 h time delay following peak concentrations of the OCT1 substrate sumatriptan. Thus, IBC is a suitable endogenous biomarker reflecting both, human OCT1 (hOCT1) genotype and activity. While murine OCT1 (mOCT1) was an efflux transporter of IBC, hOCT1 exhibited no IBC efflux activity. Inhibition experiments confirmed this data showing that IBC and other acylcarnitines, like butyrylcarnitine, 2-methylbutyrylcarnitine, and hexanoylcarnitine, showed reduced efflux upon inhibition of mOCT1 but not of hOCT1. IBC and other carnitine derivatives are endogenous biomarkers of hOCT1 genotype and phenotype. However, in contrast to mice, the mechanisms underlying the IBC-OCT1 correlation in humans is apparently not directly the OCT1-mediated efflux of IBC. A plausible explanation could be that hOCT1 mediates cellular concentrations of specific regulators or co-substrates in lipid and energy metabolism, which is supported by our in vitro finding that at baseline intracellular IBC concentration is about 6-fold lower alone by OCT1 overexpression.
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Affiliation(s)
- Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Johannes Matthaei
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Henry G Klemp
- Institute of Pediatrics and Adolescent Medicine, University Medical Center Göttingen, Göttingen, Germany
| | - Marleen J Meyer
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Mladen V Tzvetkov
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
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14
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Römer S, Meyer MJ, Klein K, Schneider LV, Matthaei J, Tzvetkova A, Łapczuk-Romańska J, Gaedcke J, Droździk M, Brockmöller J, Nies AT, Tzvetkov MV. Effects of a Common Eight Base Pairs Duplication at the Exon 7-Intron 7 Junction on Splicing, Expression, and Function of OCT1. Front Pharmacol 2021; 12:661480. [PMID: 34025422 PMCID: PMC8137991 DOI: 10.3389/fphar.2021.661480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/14/2021] [Indexed: 11/13/2022] Open
Abstract
Organic cation transporter 1 (OCT1, SLC22A1) is localized in the sinusoidal membrane of human hepatocytes and mediates hepatic uptake of weakly basic or cationic drugs and endogenous compounds. Common amino acid substitutions in OCT1 were associated with altered pharmacokinetics and efficacy of drugs like sumatriptan and fenoterol. Recently, the common splice variant rs35854239 has also been suggested to affect OCT1 function. rs35854239 represents an 8 bp duplication of the donor splice site at the exon 7-intron 7 junction. Here we quantified the extent to which this duplication affects OCT1 splicing and, as a consequence, the expression and the function of OCT1. We used pyrosequencing and deep RNA-sequencing to quantify the effect of rs35854239 on splicing after minigene expression of this variant in HepG2 and Huh7 cells and directly in human liver samples. Further, we analyzed the effects of rs35854239 on OCT1 mRNA expression in total, localization and activity of the resulting OCT1 protein, and on the pharmacokinetics of sumatriptan and fenoterol. The 8 bp duplication caused alternative splicing in 38% (deep RNA-sequencing) to 52% (pyrosequencing) of the minigene transcripts when analyzed in HepG2 and Huh7 cells. The alternatively spliced transcript encodes for a truncated protein that after transient transfection in HEK293 cells was not localized in the plasma membrane and was not able to transport the OCT1 model substrate ASP+. In human liver, however, the alternatively spliced OCT1 transcript was detectable only at very low levels (0.3% in heterozygous and 0.6% in homozygous carriers of the 8 bp duplication, deep RNA-sequencing). The 8 bp duplication was associated with a significant reduction of OCT1 expression in the human liver, but explained only 9% of the general variability in OCT1 expression and was not associated with significant changes in the pharmacokinetics of sumatriptan and fenoterol. Therefore, the rs35854239 variant only partially changes splicing, causing moderate changes in OCT1 expression and may be of only limited therapeutic relevance.
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Affiliation(s)
- Sarah Römer
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
| | - Marleen J Meyer
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
| | - Kathrin Klein
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany.,University of Tuebingen, Tuebingen, Germany
| | - Lennart V Schneider
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Johannes Matthaei
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Ana Tzvetkova
- Institute of Bioinformatics, University Medicine Greifswald, Greifswald, Germany.,Human Molecular Genetics Group, Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Joanna Łapczuk-Romańska
- Department of Experimental and Clinical Pharmacology, Pomeranian Medical University, Szczecin, Poland
| | - Jochen Gaedcke
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Marek Droździk
- Department of Experimental and Clinical Pharmacology, Pomeranian Medical University, Szczecin, Poland
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Anne T Nies
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany.,University of Tuebingen, Tuebingen, Germany.,Cluster of Excellence iFIT (EXC2180) "Image-Guided and Functionally Instructed Tumor Therapies", University of Tuebingen, Tuebingen, Germany
| | - Mladen V Tzvetkov
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
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15
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Morse BL, Fallon JK, Kolur A, Hogan AT, Smith PC, Hillgren KM. Comparison of Hepatic Transporter Tissue Expression in Rodents and Interspecies Hepatic OCT1 Activity. AAPS J 2021; 23:58. [PMID: 33903987 DOI: 10.1208/s12248-021-00583-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/16/2021] [Indexed: 11/30/2022] Open
Abstract
Hepatic clearance may be uptake rate limited by organic anion transporting polypeptides (OATPs) and organic cation transporter 1 (OCT1). While comparison of OATP activity has been investigated across species, little has been reported for OCT1. Additionally, while data on interspecies transporter expression in the liver exist, quantitative comparison of these transporters in multiple tissues is lacking. In the current research, the pharmacokinetics of OCT1 substrates (sumatriptan and metformin) were assessed in Oct knockout rats for comparison with previous Oct1/2-/- mice data and OCT1 pharmacogenetics in humans. Effect of OCT1 inhibitors verapamil and erlotinib on OCT1 substrate liver partitioning was also evaluated in rats. Expression of 18 transporters, including Oatps and Octs, in 9 tissues from mice and rats was quantitated using nanoLC/MS-MS, along with uptake transporters in hepatocytes from 5 species. Interspecies differences in OCT1 activity were further evaluated via uptake of OCT1 substrates in hepatocytes with corresponding in vivo liver partitioning in rodents and monkey. In Oct1-/- rats, sumatriptan hepatic clearance and liver partitioning decreased; however, metformin pharmacokinetics were unaffected. OCT1 inhibitor coadministration decreased sumatriptan liver partitioning. In rodents, Oatp expression was highest in the liver, although comparable expression of Oatps in other tissues was determined. Expression of Octs was highest in the kidney, with liver Oct1 expression comparably lower than Oatps. Liver partitioning of OCT1 substrates was lower in rodents than in monkey, in agreement with the highest OCT1 expression and uptake of OCT1 substrates in monkey hepatocytes. Species-dependent OCT1 activity requires consideration when translating preclinical data to the clinic.
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Affiliation(s)
- Bridget L Morse
- Drug Disposition, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, 46285, USA.
| | - John K Fallon
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Anil Kolur
- Drug Disposition, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, 46285, USA
| | - Andrew T Hogan
- Drug Disposition, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, 46285, USA
| | - Philip C Smith
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kathleen M Hillgren
- Drug Disposition, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, 46285, USA
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16
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Haberkorn B, Fromm MF, König J. Transport of Drugs and Endogenous Compounds Mediated by Human OCT1: Studies in Single- and Double-Transfected Cell Models. Front Pharmacol 2021; 12:662535. [PMID: 33967805 PMCID: PMC8100673 DOI: 10.3389/fphar.2021.662535] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/19/2021] [Indexed: 12/11/2022] Open
Abstract
Organic Cation Transporter 1 (OCT1, gene symbol: SLC22A1) is predominately expressed in human liver, localized in the basolateral membrane of hepatocytes and facilitates the uptake of endogenous compounds (e.g. serotonin, acetylcholine, thiamine), and widely prescribed drugs (e.g. metformin, fenoterol, morphine). Furthermore, exogenous compounds such as MPP+, ASP+ and Tetraethylammonium can be used as prototypic substrates to study the OCT1-mediated transport in vitro. Single-transfected cell lines recombinantly overexpressing OCT1 (e.g., HEK-OCT1) were established to study OCT1-mediated uptake and to evaluate transporter-mediated drug-drug interactions in vitro. Furthermore, double-transfected cell models simultaneously overexpressing basolaterally localized OCT1 together with an apically localized export protein have been established. Most of these cell models are based on polarized grown MDCK cells and can be used to analyze transcellular transport, mimicking the transport processes e.g. during the hepatobiliary elimination of drugs. Multidrug and toxin extrusion protein 1 (MATE1, gene symbol: SLC47A1) and the ATP-driven efflux pump P-glycoprotein (P-gp, gene symbol: ABCB1) are both expressed in the canalicular membrane of human hepatocytes and are described as transporters of organic cations. OCT1 and MATE1 have an overlapping substrate spectrum, indicating an important interplay of both transport proteins during the hepatobiliary elimination of drugs. Due to the important role of OCT1 for the transport of endogenous compounds and drugs, in vitro cell systems are important for the determination of the substrate spectrum of OCT1, the understanding of the molecular mechanisms of polarized transport, and the investigation of potential drug-drug interactions. Therefore, the aim of this review article is to summarize the current knowledge on cell systems recombinantly overexpressing human OCT1.
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Affiliation(s)
- Bastian Haberkorn
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Martin F Fromm
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jörg König
- Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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17
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Wenzel C, Drozdzik M, Oswald S. Organic Cation Transporter 1 an Intestinal Uptake Transporter: Fact or Fiction? Front Pharmacol 2021; 12:648388. [PMID: 33935750 PMCID: PMC8080103 DOI: 10.3389/fphar.2021.648388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/01/2021] [Indexed: 01/11/2023] Open
Abstract
Intestinal transporter proteins are known to affect the pharmacokinetics and in turn the efficacy and safety of many orally administered drugs in a clinically relevant manner. This knowledge is especially well-established for intestinal ATP-binding cassette transporters such as P-gp and BCRP. In contrast to this, information about intestinal uptake carriers is much more limited although many hydrophilic or ionic drugs are not expected to undergo passive diffusion but probably require specific uptake transporters. A transporter which is controversially discussed with respect to its expression, localization and function in the human intestine is the organic cation transporter 1 (OCT1). This review article provides an up-to-date summary on the available data from expression analysis as well as functional studies in vitro, animal findings and clinical observations. The current evidence suggests that OCT1 is expressed in the human intestine in small amounts (on gene and protein levels), while its cellular localization in the apical or basolateral membrane of the enterocytes remains to be finally defined, but functional data point to a secretory function of the transporter at the basolateral membrane. Thus, OCT1 should not be considered as a classical uptake transporter in the intestine but rather as an intestinal elimination pathway for cationic compounds from the systemic circulation.
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Affiliation(s)
- Christoph Wenzel
- Department of Pharmacology, Center of Drug Absorption and Transport, University Medicine Greifswald, Greifswald, Germany
| | - Marek Drozdzik
- Department of Experimental and Clinical Pharmacology, Pomeranian Medical University, Szczecin, Poland
| | - Stefan Oswald
- Institute of Pharmacology and Toxicology, Rostock University Medical Center, Rostock, Germany
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18
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Morse BL, Chen LH, Catlow JT, Fallon JK, Smith PC, Hillgren KM. Expansion of Knowledge on OCT1 Variant Activity In Vitro and In Vivo Using Oct1/2 -/- Mice. Front Pharmacol 2021; 12:631793. [PMID: 33658943 PMCID: PMC7917185 DOI: 10.3389/fphar.2021.631793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022] Open
Abstract
The role of organic cation transporter 1 (OCT1) in humans is gaining attention as data emerges regarding its role in physiology, drug exposure, and drug response. OCT1 variants with decreased in vitro function correlate well with altered exposure of multiple OCT1 substrates in variant carriers. In the current research, we investigate mechanisms behind activity of OCT1 variants in vitro by generating cell lines expressing known OCT1 variants and quantifying membrane OCT1 protein expression with corresponding OCT1 activity and kinetics. Oct knockout mice have provided additional insight into the role of Oct1 in the liver and have reproduced effects of altered OCT1 activity observed in the clinic. To assess the complex effect of Oct1 depletion on pharmacokinetics of prodrug proguanil and its active moiety cycloguanil, both of which are OCT1 substrates, Oct1/2-/- mice were used. Decreased membrane expression of OCT1 was demonstrated for all variant cell lines, although activity was substrate-dependent, as reported previously. Lack of change in activity for OCT1*2 resulted in increased intrinsic activity per pmol of OCT1 protein, particularly for sumatriptan but also for proguanil and cycloguanil. Similar to that reported in humans with decreased OCT1 function, systemic exposure of proguanil was minimally affected in Oct1/2-/- mice. However, proguanil liver partitioning and exposure decreased. Cycloguanil exposure decreased following proguanil administration in Oct1/2-/- mice, as did the systemic metabolite:parent ratio. When administered directly, systemic exposure of cycloguanil decreased slightly; however liver partitioning and exposure were decreased in Oct1/2-/- mice. Unexpectedly, following proguanil administration, the metabolite ratio in the liver changed only minimally, and liver partitioning of cycloguanil was affected in Oct1/2-/- mice to a lesser extent following proguanil administration than direct administration of cycloguanil. In conclusion, these in vitro and in vivo data offer additional complexity in understanding mechanisms of OCT1 variant activity as well as the effects of these variants in vivo. From cell lines, it is apparent that intrinsic activity is not directly related to OCT1 membrane expression. Additionally, in situations with a more complicated role of OCT1 in drug pharmacokinetics there is difficulty translating in vivo impact simply from intrinsic activity from cellular data.
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Affiliation(s)
- Bridget L. Morse
- Drug Disposition, Eli Lilly and Company, Indianapolis, IN, United States
| | - Lisa Hong Chen
- Drug Disposition, Eli Lilly and Company, Indianapolis, IN, United States
| | - John T. Catlow
- Drug Disposition, Eli Lilly and Company, Indianapolis, IN, United States
| | - John K. Fallon
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Philip C. Smith
- Division of Pharmacoengineering and Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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19
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Jensen O, Rafehi M, Gebauer L, Brockmöller J. Cellular Uptake of Psychostimulants - Are High- and Low-Affinity Organic Cation Transporters Drug Traffickers? Front Pharmacol 2021; 11:609811. [PMID: 33551812 PMCID: PMC7854383 DOI: 10.3389/fphar.2020.609811] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/09/2020] [Indexed: 12/20/2022] Open
Abstract
Psychostimulants are used therapeutically and for illegal recreational purposes. Many of these are inhibitors of the presynaptic noradrenaline, dopamine, and serotonin transporters (NET, DAT, and SERT). According to their physicochemical properties, some might also be substrates of polyspecific organic cation transporters (OCTs) that mediate uptake in liver and kidneys for metabolism and excretion. OCT1 is genetically highly polymorphic, with strong effects on transporter activity and expression. To study potential interindividual differences in their pharmacokinetics, 18 psychostimulants and hallucinogens were assessed in vitro for transport by different OCTs as well as by the high-affinity monoamine transporters NET, DAT, and SERT. The hallucinogenic natural compound mescaline was found to be strongly transported by wild-type OCT1 with a Km of 24.3 µM and a vmax of 642 pmol × mg protein−1 × min−1. Transport was modestly reduced in variants *2 and *7, more strongly reduced in *3 and *4, and lowest in *5 and *6, while *8 showed a moderately increased transport capacity. The other phenylethylamine derivatives methamphetamine, para-methoxymethamphetamine, (-)-ephedrine, and cathine ((+)-norpseudoephedrine), as well as dimethyltryptamine, were substrates of OCT2 with Km values in the range of 7.9–46.0 µM and vmax values between 70.7 and 570 pmol × mg protein−1 × min−1. Affinities were similar or modestly reduced and the transport capacities were reduced down to half in the naturally occurring variant A270S. Cathine was found to be a substrate for NET and DAT, with the Km being 21-fold and the vmax 10-fold higher for DAT but still significantly lower compared to OCT2. This study has shown that several psychostimulants and hallucinogens are substrates for OCTs. Given the extensive cellular uptake of mescaline by the genetically highly polymorphic OCT1, strong interindividual variation in the pharmacokinetics of mescaline might be possible, which could be a reason for highly variable adverse reactions. The involvement of the polymorphic OCT2 in the renal excretion of several psychostimulants could be one reason for individual differences in toxicity.
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Affiliation(s)
- Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Muhammad Rafehi
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
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20
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Abstract
The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.
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Affiliation(s)
- Hermann Koepsell
- Institute of Anatomy and Cell Biology and Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Würzburg, Germany
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21
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Jensen O, Ansari S, Gebauer L, Müller SF, Lowjaga KAAT, Geyer J, Tzvetkov MV, Brockmöller J. A double-Flp-in method for stable overexpression of two genes. Sci Rep 2020; 10:14018. [PMID: 32820202 PMCID: PMC7441062 DOI: 10.1038/s41598-020-71051-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 07/30/2020] [Indexed: 12/29/2022] Open
Abstract
Overexpression of single genes in mammalian cells is widely used to investigate protein function in basic and applied biosciences and in drug research. A better understanding of interactions of two proteins is an important next step in the advancement of our understanding of complex biological systems. However, simultaneous and robust overexpression of two or more genes is challenging. The Flp-In system integrates a vector into cell lines at a specific genomic locus, but has not been used for integration of more than one gene. Here we present a modification of the Flp-In system that enables the simultaneous targeted integration of two genes. We describe the modification and generation of the vectors required and give the complete protocol for transfection and validation of correct genomic integration and expression. We also provide results on the stability and reproducibility, and we functionally validated this approach with a pharmacologically relevant combination of a membrane transporter facilitating drug uptake and an enzyme mediating drug metabolism.
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Affiliation(s)
- Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Str. 40, 37075, Göttingen, Germany.
| | - Salim Ansari
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Simon F Müller
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Kira A A T Lowjaga
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Joachim Geyer
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University Giessen, 35392, Giessen, Germany
| | - Mladen V Tzvetkov
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Str. 40, 37075, Göttingen, Germany.,Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medical Center Greifswald, 17489, Greifswald, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Georg-August University, Robert-Koch-Str. 40, 37075, Göttingen, Germany
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22
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Jensen O, Matthaei J, Blome F, Schwab M, Tzvetkov MV, Brockmöller J. Variability and Heritability of Thiamine Pharmacokinetics With Focus on OCT1 Effects on Membrane Transport and Pharmacokinetics in Humans. Clin Pharmacol Ther 2019; 107:628-638. [PMID: 31593619 DOI: 10.1002/cpt.1666] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 09/08/2019] [Indexed: 12/21/2022]
Abstract
Thiamine is substrate of the hepatic uptake transporter organic cation transporter 1 (OCT1), and pathological lipid metabolism was associated with OCT1-dependent thiamine transport. However, it is unknown whether clinical pharmacokinetics of thiamine is modulated by OCT1 genotype. We analyzed thiamine transport in vitro, thiamine blood concentrations after high-dose and low-dose (nutritional) intake, and heritability of thiamine and thiamine-phosphate blood concentrations. The variant OCT1*2 had reduced and OCT1*3 to OCT1*6 had deficient thiamine uptake activity. However, pharmacokinetics of thiamine did not differ depending on OCT1 genotype. Further studies in primary human hepatocytes indicated that several cation transporters, including OCT1, OCT3, and THTR-2, contribute to hepatic uptake of thiamine. As much as 54% of the variation in thiamine and 75% in variation of thiamine monophosphate plasma concentrations was determined by heritable factors. Apparently, thiamine is not useful as a probe drug for OCT1 activity, but the high heritability, particularly of thiamine monophosphate, may stimulate further genomic research.
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Affiliation(s)
- Ole Jensen
- Department of Clinical Pharmacology, University Medical Center, Georg August University, Goettingen, Germany
| | - Johannes Matthaei
- Department of Clinical Pharmacology, University Medical Center, Georg August University, Goettingen, Germany
| | - Felix Blome
- Department of Clinical Pharmacology, University Medical Center, Georg August University, Goettingen, Germany
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, University of Tübingen, Stuttgart, Germany.,iFIT Cluster of Excellence, University of Tübingen, Tübingen, Germany.,Departments of Clinical Pharmacology, Pharmacy, and Biochemistry, University Tübingen, Tübingen, Germany
| | - Mladen V Tzvetkov
- Department of Clinical Pharmacology, University Medical Center, Georg August University, Goettingen, Germany.,Department of Pharmacology, University Medical Center, Ernst-Moritz-Arndt-University, Greifswald, Germany
| | - Jürgen Brockmöller
- Department of Clinical Pharmacology, University Medical Center, Georg August University, Goettingen, Germany
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23
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Brosseau N, Ramotar D. The human organic cation transporter OCT1 and its role as a target for drug responses. Drug Metab Rev 2019; 51:389-407. [PMID: 31564168 DOI: 10.1080/03602532.2019.1670204] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The human organic cation uptake transporter OCT1, encoded by the SLC22A1 gene, is highly expressed in the liver and reported to possess a broad substrate specificity. OCT1 operates by facilitated diffusion and allows the entry of nutrients into cells. Recent findings revealed that OCT1 can mediate the uptake of drugs for treating various diseases such as cancers. The levels of OCT1 expression correlate with the responses towards many drugs and functionally defective OCT1 lead to drug resistance. It has been recently proposed that OCT1 should be amongst the crucial drug targets used for pharmacogenomic analyses. Several single nucleotide polymorphisms exist and are distributed across the entire OCT1 gene. While there are differences in the OCT1 gene polymorphisms between populations, there are at least five variants that warrant consideration in any genetic screen. To date, and despite two decades of research into OCT1 functional role, it still remains uncertain what are the define substrates for this uptake transporter, although studies from mice revealed that one of the substrates is vitamin B1. It is also unclear how OCT1 recognizes a broad array of ligands and whether this involves specific modifications and interactions with other proteins. In this review, we highlight the current findings related to OCT1 with the aim of propelling further studies on this key uptake transporter.
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Affiliation(s)
- Nicolas Brosseau
- Department of Medicine, Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Montréal, Québec, Canada
| | - Dindial Ramotar
- Department of Medicine, Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Montréal, Québec, Canada
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24
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Panfen E, Chen W, Zhang Y, Sinz M, Marathe P, Gan J, Shen H. Enhanced and Persistent Inhibition of Organic Cation Transporter 1 Activity by Preincubation of Cyclosporine A. Drug Metab Dispos 2019; 47:1352-1360. [PMID: 31427432 DOI: 10.1124/dmd.119.087197] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 08/16/2019] [Indexed: 01/18/2023] Open
Abstract
Recent pharmacogenetic evidence indicates that hepatic organic cation transporter (OCT) 1 can serve as the locus of drug-drug interactions (DDIs) with significant pharmacokinetic and pharmacodynamic consequences. We examined the impact of preincubation on the extent of OCT1 inhibition in transfected human embryonic kidney 293 (HEK293) cells. Following 30-minute preincubation with an inhibitor, approximately 50-fold higher inhibition potency was observed for cyclosporine A (CsA) against OCT1-mediated uptake of metformin compared with coincubation, with IC50 values of 0.43 ± 0.12 and 21.6 ± 4.5 µM, respectively. By comparison, only small shifts (≤2-fold) in preincubation IC50 versus coincubation were observed for quinidine, pyrimethamine, ritonavir, and trimethoprim. The shift in CsA OCT1 IC50 was substrate dependent since it ranged from >1.2- to 50.2-fold using different experimental substrates. The inhibition potential of CsA toward OCT1 was confirmed by fenoterol hepatocyte uptake experiment. Furthermore, no shift in CsA IC50 was observed with HEK293 cells transfected with OCT2 and organic anion transporter (OAT) 1 and OAT3. Short exposure (30 minutes) to 10 µM CsA produced long-lasting inhibition (at least 120 minutes) of the OCT1-mediated uptake of metformin in OCT1-HEK293 cells, which was likely attributable to the retention of CsA in the cells, as shown by the fact that inhibitory cellular concentrations of CsA were maintained long after the removal of the compound from the incubation buffer. The potent and persistent inhibitory effect after exposure to CsA warrants careful consideration in the design and interpretation of clinical OCT1 DDI studies. SIGNIFICANCE STATEMENT: Preincubation of OATP1B1 and OATP1B3 with their inhibitor may result in the enhancement of the inhibitory potency in a cell-based assay. However, limited data are available on potentiation of OCT1 inhibition by preincubation, which is a clinically relevant drug transporter. For the first time, we observed a 50-fold increase in CsA inhibitory potency against OCT1-mediated transport of metformin following a preincubation step. The CsA preincubation effect on OCT1 inhibition is substrate dependent. Moreover, the inhibition potential of CsA toward OCT1 is confirmed by hepatocyte uptake experiment. This study delivers clear evidences about the potent and persistent inhibitory effect on OCT1 after exposure to CsA. Further studies are needed to assess the effect of CsA on OCT1 drug substrates in vivo.
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Affiliation(s)
- Erika Panfen
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
| | - Weiqi Chen
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
| | - Yueping Zhang
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
| | - Michael Sinz
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
| | - Punit Marathe
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
| | - Jinping Gan
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
| | - Hong Shen
- Department of Metabolism and Pharmacokinetics, Bristol-Myers Squibb Company, Princeton, New Jersey
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25
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Funakoshi R, Tomoda Y, Kudo T, Furihata K, Kusuhara H, Ito K. Effects of proton pump inhibitors, esomeprazole and vonoprazan, on the disposition of proguanil, a CYP2C19 substrate, in healthy volunteers. Br J Clin Pharmacol 2019; 85:1454-1463. [PMID: 30845361 DOI: 10.1111/bcp.13914] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 01/18/2019] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
AIMS Vonoprazan, a new class of potassium-competitive proton pump inhibitors has been found to attenuate the antiplatelet function of clopidogrel in a recent clinical study, despite weak in vitro activity against CYP2C19. To elucidate the mechanism of this interaction, the present study investigated the effects of esomeprazole and vonoprazan on the pharmacokinetics of proguanil, a CYP2C19 substrate. METHODS Seven healthy male volunteers (CYP2C19 extensive metabolizers) received a single oral administration of 100 mg proguanil/250 mg atovaquone (control phase), oral esomeprazole (20 mg) for 5 days followed by proguanil/atovaquone (esomeprazole phase) and oral vonoprazan (20 mg) for 5 days followed by proguanil/atovaquone (vonoprazan phase). Concentrations of proguanil and its metabolite, cycloguanil, in plasma and urine in each phase were determined using liquid chromatography-tandem mass spectrometry. RESULTS Coadministration with proton pump inhibitors resulted in increase and decrease in the area under the plasma concentration-time curve (AUC) of proguanil and cycloguanil, respectively, significantly reducing their AUC ratio (cycloguanil/proguanil) to 0.317-fold (95% confidence interval [CI] 0.256-0.379) and 0.507-fold (95% CI 0.409-0.605) in esomeprazole phase and vonoprazan phase, respectively. Esomeprazole and vonoprazan also significantly reduced the apparent formation clearance (cumulative amount of cycloguanil in urine divided by AUC of proguanil) to 0.324-fold (95% CI 0.212-0.436) and 0.433-fold (95% CI 0.355-0.511), respectively, without significant changes in renal clearance of proguanil and cycloguanil. CONCLUSIONS Although further studies are needed, both esomeprazole and vonoprazan potentially inhibit CYP2C19 at clinical doses, suggesting caution in the coadministration of these drugs with CYP2C19 substrates.
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Affiliation(s)
- Ryohkan Funakoshi
- Research Institute of Pharmaceutical Sciences, Musashino University, Nishitokyo-shi, Tokyo, Japan.,Department of Pharmacy, Kameda Medical Center, Kamogawa-shi, Chiba, Japan
| | - Yukana Tomoda
- Laboratory of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Toshiyuki Kudo
- Research Institute of Pharmaceutical Sciences, Musashino University, Nishitokyo-shi, Tokyo, Japan
| | - Kenichi Furihata
- P-One Clinic, Keikokai Medical Corporation, Hachioji-shi, Tokyo, Japan
| | - Hiroyuki Kusuhara
- Laboratory of Molecular Pharmacokinetics, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kiyomi Ito
- Research Institute of Pharmaceutical Sciences, Musashino University, Nishitokyo-shi, Tokyo, Japan
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26
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Najjar N, McColl ER, Weckman A, Kain KC, Piquette-Miller M. Dysregulation of solute carrier transporters in malaria-infected pregnant mice. Parasite Immunol 2019; 41:e12614. [PMID: 30703256 DOI: 10.1111/pim.12614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/24/2019] [Accepted: 01/25/2019] [Indexed: 12/18/2022]
Abstract
AIMS Malaria in pregnancy (MiP) alters the expression of ATP-binding cassette efflux transporters in maternal and foetal tissues, as well as the placenta. Malaria induces oxidative stress, and pregnancy is associated with arginine deficiency. We hypothesized that reducing oxidative stress during MiP by supplementation with L-arginine, a NO precursor, would attenuate transcriptional changes in a second superfamily of transporters, solute carrier (SLC) transporters, and improve pregnancy outcomes. METHODS AND RESULTS Pregnant BALB/c mice receiving L-arginine (1.2%) in water, or water alone, were infected with Plasmodium berghei ANKA on gestational day 13 and sacrificed on gestational day 19. Compared to controls, the mRNA of numerous SLC transporters was downregulated in maternal and foetal tissues, as well as in the placentas of infected mice. While supplementation with L-arginine did improve foetal viability, it did not improve the mRNA expression of oxidative stress markers, transporters nor other indices of foetal and maternal health. Moreover, amino acid uptake transporters were downregulated upon infection, which could potentially contribute to decreased foetal birthweight. CONCLUSIONS Malaria in pregnancy significantly alters the expression of SLC transporters in maternal and foetal tissues as well as the placenta, regardless of L-arginine supplementation. Further studies to investigate methods of reducing oxidative stress in MiP are warranted.
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Affiliation(s)
- Najwa Najjar
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Eliza R McColl
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Andrea Weckman
- Sandra Rotman Centre for Global Health, University Health Network: Toronto General Hospital, Toronto, Ontario, Canada
| | - Kevin C Kain
- Sandra Rotman Centre for Global Health, University Health Network: Toronto General Hospital, Toronto, Ontario, Canada
| | - Micheline Piquette-Miller
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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27
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Bokelmann K, Brockmöller J, Tzvetkov MV. Impact of Promoter Polymorphisms on the Transcriptional Regulation of the Organic Cation Transporter OCT1 (SLC22A1). J Pers Med 2018; 8:jpm8040042. [PMID: 30544975 PMCID: PMC6313513 DOI: 10.3390/jpm8040042] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/20/2018] [Accepted: 12/05/2018] [Indexed: 01/12/2023] Open
Abstract
The organic cation transporter 1 (OCT1, SLC22A1) is strongly expressed in the human liver and facilitates the hepatic uptake of drugs such as morphine, metformin, tropisetron, sumatriptan and fenoterol and of endogenous substances such as thiamine. OCT1 expression is inter-individually highly variable. Here, we analyzed SNPs in the OCT1 promoter concerning their potential contribution to the variability in OCT1 expression. Using electrophoretic mobility shift and luciferase reporter gene assays in HepG2, Hep3B, and Huh7 cell lines, we identified the SNPs −1795G>A (rs6935207) and −201C>G (rs58812592) as having effects on transcription factor binding and/or promoter activity. The A-allele of the −1795G>A SNP showed allele-specific binding of the transcription factor NF-Y leading to 2.5-fold increased enhancer activity of the artificial SV40 promoter. However, the −1795G>A SNP showed no significant effects on the native OCT1 promoter activity. Furthermore, the −1795G>A SNP was not associated with the pharmacokinetics of metformin, fenoterol, sumatriptan and proguanil in healthy individuals or tropisetron efficacy in patients undergoing chemotherapy. Allele-dependent differences in USF1/2 binding and nearly total loss in OCT1 promoter activity were detected for the G-allele of −201C>G, but the SNP is apparently very rare. In conclusion, common OCT1 promoter SNPs have only minor effects on OCT1 expression.
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Affiliation(s)
- Kristin Bokelmann
- Institute of Clinical Pharmacology, University Medical Center, Georg-August-University, 37075 Göttingen, Germany.
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center, Georg-August-University, 37075 Göttingen, Germany.
| | - Mladen V Tzvetkov
- Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, 17487 Greifswald, Germany.
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