1
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Stepanova M, Aherne CM. Adenosine in Intestinal Epithelial Barrier Function. Cells 2024; 13:381. [PMID: 38474346 DOI: 10.3390/cells13050381] [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: 12/23/2023] [Revised: 02/13/2024] [Accepted: 02/18/2024] [Indexed: 03/14/2024] Open
Abstract
At the intestinal front, several lines of defense are in place to resist infection and injury, the mucus layer, gut microbiome and strong epithelial junctions, to name a few. Their collaboration creates a resilient barrier. In intestinal disorders, such as inflammatory bowel disease (IBD), barrier function is compromised, which results in rampant inflammation and tissue injury. In response to the destruction, the intestinal epithelium releases adenosine, a small but powerful nucleoside that functions as an alarm signal. Amidst the chaos of inflammation, adenosine aims to restore order. Within the scope of its effects is the ability to regulate intestinal epithelial barrier integrity. This review aims to define the contributions of adenosine to mucus production, microbiome-dependent barrier protection, tight junction dynamics, chloride secretion and acid-base balance to reinforce its importance in the intestinal epithelial barrier.
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Affiliation(s)
- Mariya Stepanova
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
| | - Carol M Aherne
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
- School of Medicine, University College Dublin, Belfield, Dublin 4, Ireland
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2
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Honan LE, Fraser-Spears R, Daws LC. Organic cation transporters in psychiatric and substance use disorders. Pharmacol Ther 2024; 253:108574. [PMID: 38072333 PMCID: PMC11052553 DOI: 10.1016/j.pharmthera.2023.108574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/01/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
Psychiatric and substance use disorders inflict major public health burdens worldwide. Their widespread burden is compounded by a dearth of effective treatments, underscoring a dire need to uncover novel therapeutic targets. In this review, we summarize the literature implicating organic cation transporters (OCTs), including three subtypes of OCTs (OCT1, OCT2, and OCT3) and the plasma membrane monoamine transporter (PMAT), in the neurobiology of psychiatric and substance use disorders with an emphasis on mood and anxiety disorders, alcohol use disorder, and psychostimulant use disorder. OCTs transport monoamines with a low affinity but high capacity, situating them to play a central role in regulating monoamine homeostasis. Preclinical evidence discussed here suggests that OCTs may serve as promising targets for treatment of psychiatric and substance use disorders and encourage future research into their therapeutic potential.
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Affiliation(s)
- Lauren E Honan
- The University of Texas Health Science Center at San Antonio, Department of Cellular & Integrative Physiology, USA
| | - Rheaclare Fraser-Spears
- University of the Incarnate Word, Feik School of Pharmacy, Department of Pharmaceutical Sciences, USA
| | - Lynette C Daws
- The University of Texas Health Science Center at San Antonio, Department of Cellular & Integrative Physiology, USA; The University of Texas Health Science Center at San Antonio, Department of Pharmacology, USA.
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3
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Mullen NJ, Thakur R, Shukla SK, Chaika NV, Kollala SS, Wang D, He C, Fujii Y, Sharma S, Mulder SE, Sykes DB, Singh PK. ENT1 blockade by CNX-774 overcomes resistance to DHODH inhibition in pancreatic cancer. Cancer Lett 2023; 552:215981. [PMID: 36341997 PMCID: PMC10305837 DOI: 10.1016/j.canlet.2022.215981] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022]
Abstract
Inhibitors of dihydroorotate dehydrogenase (DHODH), a key enzyme for de novo synthesis of pyrimidine nucleotides, have failed in clinical trials for various cancers despite robust efficacy in preclinical animal models. To probe for druggable mediators of DHODH inhibitor resistance, we performed a combination screen with a small molecule library against pancreatic cancer cell lines that are highly resistant to the DHODH inhibitor brequinar (BQ). The screen revealed that CNX-774, a preclinical Bruton tyrosine kinase (BTK) inhibitor, sensitizes resistant cell lines to BQ. Mechanistic studies showed that this effect is independent of BTK and instead results from inhibition of equilibrative nucleoside transporter 1 (ENT1) by CNX-774. We show that ENT1 mediates BQ resistance by taking up extracellular uridine, which is salvaged to generate pyrimidine nucleotides in a DHODH-independent manner. In BQ-resistant cell lines, BQ monotherapy slowed proliferation and caused modest pyrimidine nucleotide depletion, whereas combination treatment with BQ and CNX-774 led to profound cell viability loss and pyrimidine starvation. We also identify N-acetylneuraminic acid accumulation as a potential marker of the therapeutic efficacy of DHODH inhibitors. In an aggressive, immunocompetent pancreatic cancer mouse model, combined targeting of DHODH and ENT1 dramatically suppressed tumor growth and prolonged mouse survival. Overall, our study defines CNX-774 as a previously uncharacterized ENT1 inhibitor and provides strong proof of concept support for dual targeting of DHODH and ENT1 in pancreatic cancer.
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Affiliation(s)
- Nicholas J Mullen
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Ravi Thakur
- Department of Oncology Science, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73014, USA
| | - Surendra K Shukla
- Department of Oncology Science, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73014, USA
| | - Nina V Chaika
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Sai Sundeep Kollala
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Dezhen Wang
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Chunbo He
- Department of Oncology Science, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73014, USA
| | - Yuki Fujii
- Department of Oncology Science, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73014, USA
| | - Shikhar Sharma
- Department of Oncology Science, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73014, USA
| | - Scott E Mulder
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - David B Sykes
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, USA; Harvard Stem Cell Institute, Cambridge, MA, 02114, USA
| | - Pankaj K Singh
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA; Department of Oncology Science, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73014, USA; OU Health Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
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4
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Di Magno L, Di Pastena F, Bordone R, Coni S, Canettieri G. The Mechanism of Action of Biguanides: New Answers to a Complex Question. Cancers (Basel) 2022; 14:cancers14133220. [PMID: 35804992 PMCID: PMC9265089 DOI: 10.3390/cancers14133220] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/20/2022] [Accepted: 06/23/2022] [Indexed: 01/27/2023] Open
Abstract
Biguanides are a family of antidiabetic drugs with documented anticancer properties in preclinical and clinical settings. Despite intensive investigation, how they exert their therapeutic effects is still debated. Many studies support the hypothesis that biguanides inhibit mitochondrial complex I, inducing energy stress and activating compensatory responses mediated by energy sensors. However, a major concern related to this “complex” model is that the therapeutic concentrations of biguanides found in the blood and tissues are much lower than the doses required to inhibit complex I, suggesting the involvement of additional mechanisms. This comprehensive review illustrates the current knowledge of pharmacokinetics, receptors, sensors, intracellular alterations, and the mechanism of action of biguanides in diabetes and cancer. The conditions of usage and variables affecting the response to these drugs, the effect on the immune system and microbiota, as well as the results from the most relevant clinical trials in cancer are also discussed.
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Affiliation(s)
- Laura Di Magno
- Department of Molecular Medicine, Sapienza University of Rome, 00189 Rome, Italy; (L.D.M.); (F.D.P.); (R.B.); (S.C.)
| | - Fiorella Di Pastena
- Department of Molecular Medicine, Sapienza University of Rome, 00189 Rome, Italy; (L.D.M.); (F.D.P.); (R.B.); (S.C.)
| | - Rosa Bordone
- Department of Molecular Medicine, Sapienza University of Rome, 00189 Rome, Italy; (L.D.M.); (F.D.P.); (R.B.); (S.C.)
| | - Sonia Coni
- Department of Molecular Medicine, Sapienza University of Rome, 00189 Rome, Italy; (L.D.M.); (F.D.P.); (R.B.); (S.C.)
| | - Gianluca Canettieri
- Department of Molecular Medicine, Sapienza University of Rome, 00189 Rome, Italy; (L.D.M.); (F.D.P.); (R.B.); (S.C.)
- Istituto Pasteur—Fondazione Cenci—Bolognetti, 00161 Rome, Italy
- Correspondence:
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5
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Ali SS, Raj R, Kaur T, Weadick B, Nayak D, No M, Protos J, Odom H, Desai K, Persaud AK, Wang J, Govindarajan R. Solute Carrier Nucleoside Transporters in Hematopoiesis and Hematological Drug Toxicities: A Perspective. Cancers (Basel) 2022; 14:cancers14133113. [PMID: 35804885 PMCID: PMC9264962 DOI: 10.3390/cancers14133113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/18/2022] [Accepted: 06/22/2022] [Indexed: 02/04/2023] Open
Abstract
Simple Summary Anticancer nucleoside analogs are promising treatments that often result in damaging toxicities and therefore ineffective treatment. Mechanisms of this are not well-researched, but cellular nucleoside transport research in mice might provide additional insight given transport’s role in mammalian hematopoiesis. Cellular nucleoside transport is a notable component of mammalian hematopoiesis due to how mutations within it relate to hematological abnormities. This review encompasses nucleoside transporters, focusing on their inherent properties, hematopoietic role, and their interplay in nucleoside drug treatment side effects. We then propose potential mechanisms to explain nucleoside transport involvement in blood disorders. Finally, we point out and advocate for future research areas that would improve therapeutic outcomes for patients taking nucleoside analog therapies. Abstract Anticancer nucleoside analogs produce adverse, and at times, dose-limiting hematological toxicities that can compromise treatment efficacy, yet the mechanisms of such toxicities are poorly understood. Recently, cellular nucleoside transport has been implicated in normal blood cell formation with studies from nucleoside transporter-deficient mice providing additional insights into the regulation of mammalian hematopoiesis. Furthermore, several idiopathic human genetic disorders have revealed nucleoside transport as an important component of mammalian hematopoiesis because mutations in individual nucleoside transporter genes are linked to various hematological abnormalities, including anemia. Here, we review recent developments in nucleoside transporters, including their transport characteristics, their role in the regulation of hematopoiesis, and their potential involvement in the occurrence of adverse hematological side effects due to nucleoside drug treatment. Furthermore, we discuss the putative mechanisms by which aberrant nucleoside transport may contribute to hematological abnormalities and identify the knowledge gaps where future research may positively impact treatment outcomes for patients undergoing various nucleoside analog therapies.
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Affiliation(s)
- Syed Saqib Ali
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Ruchika Raj
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Tejinder Kaur
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Brenna Weadick
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Debasis Nayak
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Minnsung No
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Jane Protos
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Hannah Odom
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Kajal Desai
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Avinash K. Persaud
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
| | - Joanne Wang
- Department of Pharmaceutics, College of Pharmacy, University of Washington, Seattle, WA 98195, USA;
| | - Rajgopal Govindarajan
- Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA; (S.S.A.); (R.R.); (T.K.); (B.W.); (D.N.); (M.N.); (J.P.); (H.O.); (K.D.); (A.K.P.)
- Translational Therapeutics, The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210, USA
- Correspondence: ; Tel.: +1-614-247-8269; Fax: +1-614-292-2588
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6
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Lopez Quiñones AJ, Vieira LS, Wang J. Clinical Applications and the Roles of Transporters in Disposition, Tumor Targeting, and Tissue Toxicity of meta-Iodobenzylguanidine (mIBG). Drug Metab Dispos 2022; 50:DMD-MR-2021-000707. [PMID: 35197314 PMCID: PMC9488973 DOI: 10.1124/dmd.121.000707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 02/01/2022] [Accepted: 02/17/2022] [Indexed: 11/22/2022] Open
Abstract
Transporters on the plasma membrane of tumor cells are promising molecular "Trojan horses" to deliver drugs and imaging agents into cancer cells. Radioiodine-labeled meta-iodobenzylguanidine (mIBG) is used as a diagnostic agent (123I-mIBG) and a targeted radiotherapy (131I-mIBG) for neuroendocrine cancers. mIBG enters cancer cells through the norepinephrine transporter (NET) where the radioactive decay of 131I causes DNA damage, cell death, and tumor necrosis. mIBG is predominantly eliminated unchanged by the kidney. Despite its selective uptake by neuroendocrine tumors, mIBG accumulates in several normal tissues and leads to tissue-specific radiation toxicities. Emerging evidences suggest that the polyspecific organic cation transporters play important roles in systemic disposition and tissue-specific uptake of mIBG. In particular, human organic cation transporter 2 (hOCT2) and toxin extrusion proteins 1 and 2-K (hMATE1/2-K) likely mediate renal secretion of mIBG whereas hOCT1 and hOCT3 may contribute to mIBG uptake into normal tissues such as the liver, salivary glands, and heart. This mini-review focuses on the clinical applications of mIBG in neuroendocrine cancers and the differential roles of NET, OCT and MATE transporters in mIBG disposition, response and toxicity. Understanding the molecular mechanisms governing mIBG transport in cancer and normal cells is a critical step for developing strategies to optimize the efficacy of 131I-mIBG while minimizing toxicity in normal tissues. Significance Statement Radiolabeled mIBG has been used as a diagnostic tool and as radiotherapy for neuroendocrine cancers and other diseases. NET, OCT and MATE transporters play differential roles in mIBG tumor targeting, systemic elimination, and accumulation in normal tissues. The clinical use of mIBG as a radiopharmaceutical in cancer diagnosis and treatment can be further improved by taking a holistic approach considering mIBG transporters in both cancer and normal tissues.
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Affiliation(s)
| | | | - Joanne Wang
- Dept. of Pharmaceutics, University of Washington, United States
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7
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Hermann R, Krajcsi P, Fluck M, Seithel-Keuth A, Bytyqi A, Galazka A, Munafo A. Review of Transporter Substrate, Inhibitor, and Inducer Characteristics of Cladribine. Clin Pharmacokinet 2021; 60:1509-1535. [PMID: 34435310 PMCID: PMC8613159 DOI: 10.1007/s40262-021-01065-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2021] [Indexed: 12/23/2022]
Abstract
Cladribine is a nucleoside analog that is phosphorylated in its target cells (B- and T-lymphocytes) to its active adenosine triphosphate form (2-chlorodeoxyadenosine triphosphate). Cladribine tablets 10 mg (Mavenclad®) administered for up to 10 days per year in 2 consecutive years (3.5-mg/kg cumulative dose over 2 years) are used to treat patients with relapsing multiple sclerosis. The ATP-binding cassette, solute carrier, and nucleoside transporter substrate, inhibitor, and inducer characteristics of cladribine are reviewed in this article. Available evidence suggests that the distribution of cladribine across biological membranes is facilitated by a number of uptake and efflux transporters. Among the key ATP-binding cassette efflux transporters, only breast cancer resistance protein has been shown to be an efficient transporter of cladribine, while P-glycoprotein does not transport cladribine well. Intestinal absorption, distribution throughout the body, and intracellular uptake of cladribine appear to be exclusively mediated by equilibrative and concentrative nucleoside transporters, specifically by ENT1, ENT2, ENT4, CNT2 (low affinity), and CNT3. Renal excretion of cladribine appears to be most likely driven by breast cancer resistance protein, ENT1, and P-glycoprotein. The latter may play a role despite its poor cladribine transport efficiency in view of the renal abundance of P-glycoprotein. There is no evidence that solute carrier uptake transporters such as organic anion transporting polypeptides, organic anion transporters, and organic cation transporters are involved in the transport of cladribine. Available in vitro studies examining the inhibitor characteristics of cladribine for a total of 13 major ATP-binding cassette, solute carrier, and CNT transporters indicate that in vivo inhibition of any of these transporters by cladribine is unlikely.
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Affiliation(s)
- Robert Hermann
- Clinical Research Appliance (cr.appliance), Heinrich-Vingerhut-Weg 3, 63571, Gelnhausen, Germany.
| | | | | | | | | | | | - Alain Munafo
- Institute of Pharmacometrics, an Affiliate of Merck KGaA, Lausanne, Switzerland
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8
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Sun A, Wang J. Choroid Plexus and Drug Removal Mechanisms. AAPS JOURNAL 2021; 23:61. [PMID: 33942198 DOI: 10.1208/s12248-021-00587-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 03/24/2021] [Indexed: 01/08/2023]
Abstract
Timely and efficient removal of xenobiotics and metabolites from the brain is crucial in maintaining the homeostasis and normal function of the brain. The choroid plexus (CP) forms the blood-cerebrospinal fluid barrier and vitally removes drugs and wastes from the brain through several co-existing clearance mechanisms. The CP epithelial (CPE) cells synthesize and secrete the cerebrospinal fluid (CSF). As the CSF passes through the ventricular and subarachnoid spaces and eventually drains into the general circulation, it collects and removes drugs, toxins, and metabolic wastes from the brain. This bulk flow of the CSF serves as a default and non-selective pathway for the removal of solutes and macromolecules from the brain interstitium. Besides clearance by CSF bulk flow, the CPE cells express several multispecific membrane transporters to actively transport substrates from the CSF side into the blood side. In addition, several phase I and II drug-metabolizing enzymes are expressed in the CPE cells, which enzymatically inactivate a broad spectrum of reactive or toxic substances. This review summarizes our current knowledge of the functional characteristics and key contributors to the various clearance pathways in the CP-CSF system, overviewing recent developments in our understanding of CSF flow dynamics and the functional roles of CP uptake and efflux transporters in influencing CSF drug concentrations.
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Affiliation(s)
- Austin Sun
- Department of Pharmaceutics, University of Washington, Health Science Building Room H-272J, Box 357610, Seattle, Washington, 98195-7610, USA
| | - Joanne Wang
- Department of Pharmaceutics, University of Washington, Health Science Building Room H-272J, Box 357610, Seattle, Washington, 98195-7610, USA.
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9
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Pizzagalli MD, Bensimon A, Superti‐Furga G. A guide to plasma membrane solute carrier proteins. FEBS J 2021; 288:2784-2835. [PMID: 32810346 PMCID: PMC8246967 DOI: 10.1111/febs.15531] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/07/2020] [Accepted: 08/17/2020] [Indexed: 12/13/2022]
Abstract
This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.
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Affiliation(s)
- Mattia D. Pizzagalli
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Ariel Bensimon
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
| | - Giulio Superti‐Furga
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of SciencesViennaAustria
- Center for Physiology and PharmacologyMedical University of ViennaAustria
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10
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Abstract
Precise control of monoamine neurotransmitter levels in the central nervous system (CNS) is crucial for proper brain function. Dysfunctional monoamine signaling is associated with several neuropsychiatric and neurodegenerative disorders. The plasma membrane monoamine transporter (PMAT) is a new polyspecific organic cation transporter encoded by the SLC29A4 gene. Capable of transporting monoamine neurotransmitters with low affinity and high capacity, PMAT represents a major uptake2 transporter in the brain. Broadly expressed in multiple brain regions, PMAT can complement the high-affinity, low-capacity monoamine uptake mediated by uptake1 transporters, the serotonin, dopamine, and norepinephrine transporters (SERT, DAT, and NET, respectively). This chapter provides an overview of the molecular and functional characteristics of PMAT together with its regional and cell-type specific expression in the mammalian brain. The physiological functions of PMAT in brain monoamine homeostasis are evaluated in light of its unique transport kinetics and brain location, and in comparison with uptake1 and other uptake2 transporters (e.g., OCT3) along with corroborating experimental evidences. Lastly, the possibility of PMAT's involvement in brain pathophysiological processes, such as autism, depression, and Parkinson's disease, is discussed in the context of disease pathology and potential link to aberrant monoamine pathways.
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11
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Substrates and Inhibitors of Organic Cation Transporters (OCTs) and Plasma Membrane Monoamine Transporter (PMAT) and Therapeutic Implications. Handb Exp Pharmacol 2021; 266:119-167. [PMID: 34495395 DOI: 10.1007/164_2021_516] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The gene products of the SLC22A gene family (hOCT1, hOCT2, and hOCT3) and of the SLC29A4 gene (hPMAT or hENT4) are all polyspecific organic cation transporters. Human OCTs (including hPMAT) are expressed in peripheral tissues such as small intestine, liver, and kidney involved in the pharmacokinetics of drugs. In the human brain, all four transporters are expressed at the blood-brain barrier (BBB), hOCT2 is additionally expressed in neurons, and hOCT3 and hPMAT in glia. More than 40% of the presently used drugs are organic cations. This chapter lists and discusses all known drugs acting as substrates or inhibitors of these four organic cation transporters, independently of whether the transporter is expressed in the central nervous system (CNS) or in peripheral tissues. Of interest is their involvement in drug absorption, distribution, and excretion as well as potential OCT-associated drug-drug interactions (DDIs), with a focus on drugs that act in the CNS.
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12
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Liao MZ, Flood Nichols SK, Ahmed M, Clark S, Hankins GD, Caritis S, Venkataramanan R, Haas D, Quinney SK, Haneline LS, Tita AT, Manuck T, Wang J, Thummel KE, Brown LM, Ren Z, Easterling TR, Hebert MF. Effects of Pregnancy on the Pharmacokinetics of Metformin. Drug Metab Dispos 2020; 48:264-271. [PMID: 31980499 PMCID: PMC7076518 DOI: 10.1124/dmd.119.088435] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 12/30/2019] [Indexed: 12/22/2022] Open
Abstract
This study's primary objective was to fully characterize the pharmacokinetics of metformin in pregnant women with gestational diabetes mellitus (GDM) versus nonpregnant controls. Steady-state oral metformin pharmacokinetics in pregnant women with GDM receiving either metformin monotherapy (n = 24) or a combination with glyburide (n = 30) as well as in nonpregnant women with type 2 diabetes mellitus (T2DM) (n = 24) were determined utilizing noncompartmental techniques. Maternal and umbilical cord blood samples were collected at delivery from 38 women. With both 500- and 1000-mg doses, metformin bioavailability, volume of distribution beta (V β ), clearance, and renal clearance were significantly increased during pregnancy. In addition, in the women receiving metformin 500 mg, significantly higher metformin apparent oral clearance (CL/F) (27%), weight-adjusted renal secretion clearance (64%), and apparent oral volume of distribution beta (V β /F) (33%) were seen during pregnancy. Creatinine clearance was significantly higher during pregnancy. Increasing metformin dose from 500 to 1000 mg orally twice daily significantly increased V β /F by 28%, weight-adjusted V β /F by 32% and CL/F by 25%, and weight-adjusted CL/F by 28% during pregnancy. Mean metformin umbilical cord arterial-to-venous plasma concentration ratio was 1.0 ± 0.1, venous umbilical cord-to-maternal concentration ratio was 1.4 ± 0.5, and arterial umbilical cord-to-maternal concentration ratio was 1.5 ± 0.5. Systemic exposure after a 500-mg dose of metformin was lower during pregnancy compared with the nonpregnant women with T2DM. However, in patients receiving metformin 1000 mg, changes in estimated bioavailability during pregnancy offset the changes in clearance leading to no significant change in CL/F with the higher dose. SIGNIFICANCE STATEMENT: Gestational diabetes mellitus complicates 5%-13% of pregnancies and is often treated with metformin. Pregnant women undergo physiological changes that alter drug disposition. Preliminary data suggest that pregnancy lowers metformin concentrations, potentially affecting efficacy and safety. This study definitively describes pregnancy's effects on metformin pharmacokinetics and expands the mechanistic understanding of pharmacokinetic changes across the dosage range. Here we report the nonlinearity of metformin pharmacokinetics and the increase in bioavailability, clearance, renal clearance, and volume of distribution during pregnancy.
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Affiliation(s)
- Michael Z Liao
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Shannon K Flood Nichols
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Mahmoud Ahmed
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Shannon Clark
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Gary D Hankins
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Steve Caritis
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Raman Venkataramanan
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - David Haas
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Sara K Quinney
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Laura S Haneline
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Alan T Tita
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Tracy Manuck
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Joanne Wang
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Kenneth E Thummel
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Linda Morris Brown
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Zhaoxia Ren
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Thomas R Easterling
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
| | - Mary F Hebert
- University of Washington, Departments of Pharmaceutics (M.Z.L., J.W., K.E.T.), Obstetrics and Gynecology (T.R.E., M.F.H.), and Pharmacy (T.R.E., M.F.H.), Seattle, Washington; Madigan Army Medical Center, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Tacoma, Washington (S.K.F.N.); University of Texas Medical Branch in Galveston, Department of Obstetrics and Gynecology, Galveston, Texas (M.A., S.Cl., G.D.H.); University of Pittsburgh, Departments of Obstetrics and Gynecology (S.Ca.), Pharmacy and Pharmaceutical Sciences (R.V.), Pittsburgh, Pennsylvania; Indiana University, Departments of Obstetrics and Gynecology (D.H., S.K.Q.) and Pediatrics (L.S.H.), Indianapolis, Indiana; University of Alabama at Birmingham, Department of Obstetrics and Gynecology, Birmingham, Alabama (A.T.T.); University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, North Carolina (T.M.); Biostatistics and Epidemiology Division, Environmental and Health Science Unit, RTI International, Rockville, Maryland (L.M.B.); and Obstetric and Pediatric Pharmacology and Therapeutic Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland (Z.R.)
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Shen H, Scialis RJ, Lehman-McKeeman L. Xenobiotic Transporters in the Kidney: Function and Role in Toxicity. Semin Nephrol 2019; 39:159-175. [DOI: 10.1016/j.semnephrol.2018.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Wang Q, Zuo Z. Impact of transporters and enzymes from blood–cerebrospinal fluid barrier and brain parenchyma on CNS drug uptake. Expert Opin Drug Metab Toxicol 2018; 14:961-972. [DOI: 10.1080/17425255.2018.1513493] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Qianwen Wang
- School of Pharmacy, The Chinese University of Hong Kong, Hong Kong, P. R. China
| | - Zhong Zuo
- School of Pharmacy, The Chinese University of Hong Kong, Hong Kong, P. R. China
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15
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Moon SJ, Oh J, Lee SH, Choi Y, Yu KS, Chung JY. Effect of plasma membrane monoamine transporter genetic variants on pharmacokinetics of metformin in humans. Transl Clin Pharmacol 2018; 26:79-85. [PMID: 32055553 PMCID: PMC6989255 DOI: 10.12793/tcp.2018.26.2.79] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 05/31/2018] [Accepted: 06/04/2018] [Indexed: 11/29/2022] Open
Abstract
Metformin, an oral hypoglycemic agent belonging to biguanide class, is widely used to treat type 2 diabetes mellitus, and several drug transporters such as organic cation transporters (OCTs), multidrug and toxin extrusion transporter (MATE), and plasma membrane monoamine transporter (PMAT) are thought to affect its disposition. We evaluated the role of PMAT genetic variations on the pharmacokinetic characteristics of metformin in a Korean population. In this retrospective study, 91 healthy subjects from four different metformin pharmacokinetic studies were analyzed; in each study, the subjects were administered two oral doses of metformin at intervals of 12 hours and dose-normalized pharmacokinetic parameters were compared between the subjects' genotypes. Subjects who had more than one allele of c.883-144A>G single nucleotide polymorphism (SNP) in PMAT gene (rs3889348) showed increased renal clearance of metformin compared to wild-type subjects (814.79 ± 391.73 vs. 619.90 ± 195.43 mL/min, p=0.003), whereas no differences in metformin exposure were observed between the PMAT variant subjects and wild-type subjects. Similarly, subjects with variant rs316019 SNP in OCT2 showed decreased renal clearance of metformin compared to wild-type subjects (586.01 ± 160.54 vs. 699.13 ± 291.40 mL/min, p=0.048). Other SNPs in PMAT and MATE1/2-K genes did not significantly affect metformin pharmacokinetics. In conclusion, the genetic variation of c.883-144A>G SNP in PMAT significantly affects the renal clearance of metformin in healthy Korean male subjects.
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Affiliation(s)
- Seol Ju Moon
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Republic of Korea
| | - Jaeseong Oh
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Republic of Korea
| | - Seung Hwan Lee
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Republic of Korea
| | - Yewon Choi
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Republic of Korea
| | - Kyung-Sang Yu
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul 03080, Republic of Korea
| | - Jae-Yong Chung
- Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Bundang Hospital, Seongnam 13620, Republic of Korea
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Hibma JE, Zur AA, Castro RA, Wittwer MB, Keizer RJ, Yee SW, Goswami S, Stocker SL, Zhang X, Huang Y, Brett CM, Savic RM, Giacomini KM. The Effect of Famotidine, a MATE1-Selective Inhibitor, on the Pharmacokinetics and Pharmacodynamics of Metformin. Clin Pharmacokinet 2017; 55:711-21. [PMID: 26597253 DOI: 10.1007/s40262-015-0346-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Pharmacokinetic outcomes of transporter-mediated drug-drug interactions (TMDDIs) are increasingly being evaluated clinically. The goal of our study was to determine the effects of selective inhibition of multidrug and toxin extrusion protein 1 (MATE1), using famotidine, on the pharmacokinetics and pharmacodynamics of metformin in healthy volunteers. METHODS Volunteers received metformin alone or with famotidine in a crossover design. As a positive control, the longitudinal effects of famotidine on the plasma levels of creatinine (an endogenous substrate of MATE1) were quantified in parallel. Famotidine unbound concentrations in plasma reached 1 µM, thus exceeding the in vitro concentrations that inhibit MATE1 [concentration of drug producing 50 % inhibition (IC50) 0.25 µM]. Based on current regulatory guidance, these concentrations are expected to inhibit MATE1 clinically [i.e. maximum unbound plasma drug concentration (C max,u)/IC50 >0.1]. RESULTS Consistent with MATE1 inhibition, famotidine administration significantly altered creatinine plasma and urine levels in opposing directions (p < 0.005). Interestingly, famotidine increased the estimated bioavailability of metformin [cumulative amount of unchanged drug excreted in urine from time zero to infinity (A e∞)/dose; p < 0.005] without affecting its systemic exposure [area under the plasma concentration-time curve (AUC) or maximum concentration in plasma (C max)] as a result of a counteracting increase in metformin renal clearance. Moreover, metformin-famotidine co-therapy caused a transient effect on oral glucose tolerance tests [area under the glucose plasma concentration-time curve between time zero and 0.5 h (AUCglu,0.5); p < 0.005]. CONCLUSIONS These results suggest that famotidine may improve the bioavailability and enhance the renal clearance of metformin.
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Affiliation(s)
- Jennifer E Hibma
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA.,Department of Clinical Pharmacy, University of California San Francisco, San Francisco, CA, USA
| | - Arik A Zur
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Richard A Castro
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Matthias B Wittwer
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Ron J Keizer
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Srijib Goswami
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Sophie L Stocker
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | | | - Yong Huang
- Optivia Biotechnology Inc., Menlo Park, CA, USA
| | - Claire M Brett
- Department of Anesthesiology, University of California San Francisco, San Francisco, CA, USA
| | - Radojka M Savic
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, 1550 4th St, RH 584, Box 2911, San Francisco, CA, 94158, USA.
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17
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Smolders EJ, Colbers A, de Kanter CTMM, Velthoven-Graafland K, Wolberink LT, van Ewijk-Beneken Kolmer N, Drenth JPH, Aarnoutse RE, Tack CJ, Burger DM. Metformin and daclatasvir: absence of a pharmacokinetic-pharmacodynamic drug interaction in healthy volunteers. Br J Clin Pharmacol 2017; 83:2225-2234. [PMID: 28474741 DOI: 10.1111/bcp.13323] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/24/2017] [Accepted: 04/30/2017] [Indexed: 12/27/2022] Open
Abstract
AIM The aim of the present study was to evaluate the effect of the proposed organic cation transporter (OCT) inhibitor daclatasvir on the pharmacokinetics and pharmacodynamics of the OCT substrate metformin. METHODS This was an open-label, two-period, randomized, crossover trial in 20 healthy subjects. Treatment A consisted of metformin and treatment B consisted of metformin + daclatasvir. Pharmacokinetic curves were recorded at steady-state. Geometric mean ratios (GMRs) with 90% confidence intervals (CIs) were calculated for metformin area under the concentration-time curve from 0 h to 12 h (AUC0-12 ), maximum plasma concentration (Cmax ) and final plasma concentration (Clast ). An oral glucose tolerance test was performed, measuring insulin, glucose and lactate levels. RESULTS The GMRs (90% CI) of metformin AUC0-12 , Cmax and Clast (B vs. A) were 109% (102-116%), 108% (101-116%) and 112% (103-122%). The geometric mean AUC0-2 for insulin, glucose and lactate during treatments A and B were 84 h. mEl-1 and 90 h. mEl-1 , 13.6 h. mmol l-1 and 13.4 h. mmol l-1 , and 3.4 h. mmol l-1 and 3.5 h. mmol l-1 , respectively. CONCLUSIONS Bioequivalence analysis showed that daclatasvir does not influence the pharmacokinetics of metformin in healthy subjects. Pharmacodynamic parameters were also comparable between treatments.
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Affiliation(s)
- Elise J Smolders
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
| | - Angela Colbers
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
| | | | - Kirsten Velthoven-Graafland
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
| | - Leonie T Wolberink
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
| | - Noor van Ewijk-Beneken Kolmer
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
| | - Joost P H Drenth
- Department of Gastroenterology and Hepatology, Radboud university medical center, Nijmegen, the Netherlands
| | - Rob E Aarnoutse
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
| | - Cees J Tack
- Department of Internal Medicine, Radboud university medical center, Nijmegen, the Netherlands
| | - David M Burger
- Department of Pharmacy and Radboud Institute for Health Sciences (RIHS), Radboud university medical center, Nijmegen, the Netherlands
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18
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Transporters Involved in Metformin Pharmacokinetics and Treatment Response. J Pharm Sci 2017; 106:2245-2250. [PMID: 28495567 DOI: 10.1016/j.xphs.2017.04.078] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/15/2017] [Accepted: 04/17/2017] [Indexed: 01/26/2023]
Abstract
Metformin, widely used as first-line treatment for type 2 diabetes, exists primarily as a hydrophilic cation at physiological pHs. As such, membrane transporters play a substantial role in its absorption, tissues distribution, and renal elimination. Multiple organic cation transporters are determinants of the pharmacokinetics of metformin, and many of them are important in its pharmacological action, as mediators of metformin entry into target tissues. Furthermore, a recent genome-wide association study in a large multi-ethnic population implicated polymorphisms in SLC2A2, encoding the glucose transporter, GLUT2, as important determinants of response to metformin. Here, we describe the key transporters associated with metformin pharmacokinetics and response.
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Christensen M, Jensen JB, Jakobsen S, Jessen N, Frøkiær J, Kemp BE, Marciszyn AL, Li H, Pastor-Soler NM, Hallows KR, Nørregaard R. Renoprotective Effects of Metformin are Independent of Organic Cation Transporters 1 &2 and AMP-activated Protein Kinase in the Kidney. Sci Rep 2016; 6:35952. [PMID: 27782167 PMCID: PMC5080611 DOI: 10.1038/srep35952] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 10/07/2016] [Indexed: 01/11/2023] Open
Abstract
The type-2 diabetes drug metformin has proven to have protective effects in several renal disease models. Here, we investigated the protective effects in a 3-day unilateral ureteral obstruction (3dUUO) mouse model. Compared with controls, ureteral obstructed animals displayed increased tubular damage and inflammation. Metformin treatment attenuated inflammation, increased the anti-oxidative response and decreased tubular damage. Hepatic metformin uptake depends on the expression of organic cation transporters (OCTs). To test whether the effects of metformin in the kidney are dependent on these transporters, we tested metformin treatment in OCT1/2-/- mice. Even though exposure of metformin in the kidney was severely decreased in OCT1/2-/- mice when evaluated with [11C]-Metformin and PET/MRI, we found that the protective effects of metformin were OCT1/2 independent when tested in this model. AMP-activated protein kinase (AMPK) has been suggested as a key mediator of the effects of metformin. When using an AMPK-β1 KO mouse model, the protective effects of metformin still occurred in the 3dUUO model. In conclusion, these results show that metformin has a beneficial effect in early stages of renal disease induced by 3dUUO. Furthermore, these effects appear to be independent of the expression of OCT1/2 and AMPK-β1, the most abundant AMPK-β isoform in the kidney.
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Affiliation(s)
| | - Jonas B. Jensen
- Department of Clinical Medicine, Aarhus University, Denmark
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Denmark
| | - Steen Jakobsen
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Denmark
| | - Niels Jessen
- Department of Clinical Medicine, Aarhus University, Denmark
| | - Jørgen Frøkiær
- Department of Clinical Medicine, Aarhus University, Denmark
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Denmark
| | - Bruce E. Kemp
- St. Vincent’s Institute of Medical Research, University of Melbourne, Mary MacKillop Institute for Health Research Australian Catholic University, Victoria Parade, Fitzroy VIC 3065, Australia
| | - Allison L. Marciszyn
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Hui Li
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
| | - Núria M. Pastor-Soler
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
| | - Kenneth R. Hallows
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
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Wang J. The plasma membrane monoamine transporter (PMAT): Structure, function, and role in organic cation disposition. Clin Pharmacol Ther 2016; 100:489-499. [PMID: 27506881 DOI: 10.1002/cpt.442] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 07/25/2016] [Indexed: 12/25/2022]
Abstract
Plasma membrane monoamine transporter (PMAT) is a new polyspecific organic cation transporter that transports a variety of biogenic amines and xenobiotic cations. Highly expressed in the brain, PMAT represents a major uptake2 transporter for monoamine neurotransmitters. At the blood-cerebrospinal fluid (CSF) barrier, PMAT is the principal organic cation transporter for removing neurotoxins and drugs from the CSF. Here I summarize our latest understanding of PMAT and its roles in monoamine uptake and xenobiotic disposition.
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Affiliation(s)
- J Wang
- Department of Pharmaceutics, University of Washington, Seattle, Washington, USA.
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21
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Shirasaka Y, Lee N, Duan H, Ho H, Pak J, Wang J. Interspecies comparison of the functional characteristics of plasma membrane monoamine transporter (PMAT) between human, rat and mouse. J Chem Neuroanat 2016; 83-84:99-106. [PMID: 27641077 DOI: 10.1016/j.jchemneu.2016.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/13/2016] [Accepted: 09/14/2016] [Indexed: 12/11/2022]
Abstract
Plasma membrane monoamine transporter (PMAT) is a newly discovered monoamine transporter belonging to the equilibrative nucleoside transporter family. Highly expressed in the brain, PMAT represents a major uptake2 transporter that may play a role in monoamine clearance. Although human PMAT has been functionally characterized at the molecular level, rodent models are often used to evaluate PMAT function in ex vivo and in vivo studies. The aim of this study was to examine if there is potential species difference in the functional characteristics of PMAT between human, rat and mouse. A set of transfected cells stably expressing human PMAT (MDCK/hPMAT), rat Pmat (MDCK/rPmat) and mouse Pmat (Flp293/mPmat) were constructed. In MDCK/hPMAT, MDCK/rPmat and Flp293/mPmat cells, cellular localization analyses revealed that hPMAT, rPmat and mPmat are expressed and mainly localized to the plasma membranes of cells. The uptake of MPP+, serotonin and dopamine by MDCK/hPMAT, MDCK/rPmat and Flp293/mPmat cells was significantly increased compared with those by the mock transfection control. In contrast, two nucleosides, uridine and adenosine, minimally interacted with PMAT/Pmat in all species. The hPMAT-, rPmat- and mPmat-mediated uptakes of MPP+, serotonin and dopamine were saturable, with Km values of 33.7μM, 70.2μM and 49.5μM (MPP+), 116μM, 82.9μM and 231μM (serotonin), and 201μM, 271μM and 466μM (dopamine), respectively, suggesting similar substrate affinities between human and rodent PMAT/Pmat. The prototypical inhibitors, decynium 22 and GBR12935, also showed similar inhibition potencies between species. In conclusion, the present study demonstrated interspecies similarities in the functional characteristics of human and rodent PMAT/Pmat, which indicate a practical utility of rat and mouse animal models for further investigating and extrapolating the in vivo function of PMAT in humans.
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Affiliation(s)
- Yoshiyuki Shirasaka
- Department of Pharmaceutics, School of Pharmacy, University of Washington, H272 Health Sciences Building, Seattle, WA 98195-7610, USA; Department of Biopharmaceutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Nora Lee
- Department of Pharmaceutics, School of Pharmacy, University of Washington, H272 Health Sciences Building, Seattle, WA 98195-7610, USA
| | - Haichuan Duan
- Department of Pharmaceutics, School of Pharmacy, University of Washington, H272 Health Sciences Building, Seattle, WA 98195-7610, USA
| | - Horace Ho
- Department of Pharmaceutics, School of Pharmacy, University of Washington, H272 Health Sciences Building, Seattle, WA 98195-7610, USA
| | - Joanna Pak
- Department of Pharmaceutics, School of Pharmacy, University of Washington, H272 Health Sciences Building, Seattle, WA 98195-7610, USA
| | - Joanne Wang
- Department of Pharmaceutics, School of Pharmacy, University of Washington, H272 Health Sciences Building, Seattle, WA 98195-7610, USA.
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Wagner DJ, Hu T, Wang J. Polyspecific organic cation transporters and their impact on drug intracellular levels and pharmacodynamics. Pharmacol Res 2016; 111:237-246. [PMID: 27317943 DOI: 10.1016/j.phrs.2016.06.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 06/02/2016] [Indexed: 01/11/2023]
Abstract
Most drugs are intended to act on molecular targets residing within a specific tissue or cell type. Therefore, the drug concentration within the target tissue or cells is most relevant to its pharmacological effect. Increasing evidences suggest that drug transporters not only play a significant role in governing systemic drug levels, but are also an important gate keeper for intra-tissue and intracellular drug concentrations. This review focuses on polyspecific organic cation transporters, which include the organic cation transporters 1-3 (OCT1-3), the multidrug and toxin extrusion proteins 1-2 (MATE1-2) and the plasma membrane monoamine transporter (PMAT). Following an overview of the tissue distribution, transport mechanisms, and functional characteristics of these transporters, we highlight the studies demonstrating the ability of locally expressed OCTs to impact intracellular drug concentrations and directly influence their pharmacological and toxicological activities. Specifically, OCT1-mediated metformin access to its site of action in the liver is impacted by genetic polymorphisms and chemical inhibition of OCT1. The impact of renal OCT2 and MATE1/2-K in cisplatin intrarenal accumulation and nephrotoxicity is reviewed. New data demonstrating the role of OCT3 in salivary drug accumulation and secretion is discussed. Whenever possible, the pharmacodynamic response and toxicological effects is presented and discussed in light of intra-tissue and intracellular drug exposure. Current challenges, knowledge gaps, and future research directions are discussed. Understanding the impact of transporters on intra-tissue and intracellular drug concentrations has important implications for rational-based optimization of drug efficacy and safety.
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Affiliation(s)
- David J Wagner
- Department of Pharmaceutics, University of Washington, Seattle, WA, United States.
| | - Tao Hu
- Department of Pharmaceutics, University of Washington, Seattle, WA, United States.
| | - Joanne Wang
- Department of Pharmaceutics, University of Washington, Seattle, WA, United States.
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23
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Wu KC, Lu YH, Peng YH, Hsu LC, Lin CJ. Effects of lipopolysaccharide on the expression of plasma membrane monoamine transporter (PMAT) at the blood-brain barrier and its implications to the transport of neurotoxins. J Neurochem 2015; 135:1178-88. [DOI: 10.1111/jnc.13363] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 08/26/2015] [Accepted: 08/28/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Kuo-Chen Wu
- School of Pharmacy; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Ya-Hsuan Lu
- School of Pharmacy; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Yi-Hsuan Peng
- School of Pharmacy; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Lih-Ching Hsu
- School of Pharmacy; College of Medicine; National Taiwan University; Taipei Taiwan
| | - Chun-Jung Lin
- School of Pharmacy; College of Medicine; National Taiwan University; Taipei Taiwan
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Frame IJ, Deniskin R, Arora A, Akabas MH. Purine import into malaria parasites as a target for antimalarial drug development. Ann N Y Acad Sci 2014; 1342:19-28. [PMID: 25424653 DOI: 10.1111/nyas.12568] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Infection with Plasmodium species parasites causes malaria. Plasmodium parasites are purine auxotrophs. In all life cycle stages, they require purines for RNA and DNA synthesis and other cellular metabolic processes. Purines are imported from the host erythrocyte by equilibrative nucleoside transporters (ENTs). They are processed via purine salvage pathway enzymes to form the required purine nucleotides. The Plasmodium falciparum genome encodes four putative ENTs (PfENT1-4). Genetic, biochemical, and physiologic evidence suggest that PfENT1 is the primary purine transporter supplying the purine salvage pathway. Protein mass spectrometry shows that PfENT1 is expressed in all parasite stages. PfENT1 knockout parasites are not viable in culture at purine concentrations found in human blood (<10 μM). Thus, PfENT1 is a potential target for novel antimalarial drugs, but no PfENT1 inhibitors have been identified to test the hypothesis. Identifying inhibitors of PfENT1 is an essential step to validate PfENT1 as a potential antimalarial drug target.
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Affiliation(s)
- I J Frame
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York
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25
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Grün B, Kiessling MK, Burhenne J, Riedel KD, Weiss J, Rauch G, Haefeli WE, Czock D. Trimethoprim-metformin interaction and its genetic modulation by OCT2 and MATE1 transporters. Br J Clin Pharmacol 2014; 76:787-96. [PMID: 23305245 DOI: 10.1111/bcp.12079] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 12/22/2012] [Indexed: 12/11/2022] Open
Abstract
AIMS Metformin pharmacokinetics depends on the presence and activity of membrane-bound drug transporters and may be affected by transport inhibitors. The aim of this study was to investigate the effects of trimethoprim on metformin pharmacokinetics and genetic modulation by organic cation transporter 2 (OCT2) and multidrug and toxin extrusion 1 (MATE1) polymorphisms. METHODS Twenty-four healthy volunteers received metformin 500 mg three times daily for 10 days and trimethoprim 200 mg twice daily from day 5 to 10. Effects of trimethoprim on steady-state metformin pharmacokinetics were analysed. RESULTS In the population as a whole, trimethoprim significantly reduced the apparent systemic metformin clearance (CL/F) from 74 to 54 l h(-1) and renal metformin clearance from 31 to 21 l h(-1) , and prolonged half-life from 2.7 to 3.6 h (all P < 0.01). This resulted in an increase in the maximal plasma concentration by 38% and in the area under the plasma concentration-time curve by 37%. In volunteers polymorphic for both OCT2 and MATE1, trimethoprim had no relevant inhibitory effects on metformin kinetics. Trimethoprim was associated with a decrease in creatinine clearance from 133 to 106 ml min(-1) (P < 0.01) and an increase in plasma lactate from 0.94 to 1.2 mmol l(-1) (P = 0.016). CONCLUSIONS The extent of inhibition by trimethoprim was moderate, but might be clinically relevant in patients with borderline renal function or high-dose metformin.
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Affiliation(s)
- Barbara Grün
- Department of Clinical Pharmacology and Pharmacoepidemiology, University Hospital Heidelberg, 69120, Heidelberg, Germany
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26
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Quantitation of Metformin in Human Plasma and Urine by Hydrophilic Interaction Liquid Chromatography and Application to a Pharmacokinetic Study. Ther Drug Monit 2014; 36:211-7. [DOI: 10.1097/ftd.0b013e3182a4598a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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A gene-gene interaction between polymorphisms in the OCT2 and MATE1 genes influences the renal clearance of metformin. Pharmacogenet Genomics 2014; 23:526-34. [PMID: 23873119 DOI: 10.1097/fpc.0b013e328364a57d] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE The aim of this study was to determine the association between the renal clearance (CL(renal)) of metformin in healthy Caucasian volunteers and the single-nucleotide polymorphism (SNP) c.808G>T (rs316019) in OCT2 as well as the relevance of the gene-gene interactions between this SNP and (a) the promoter SNP g.-66T>C (rs2252281) in MATE1 and (b) the OCT1 reduced-function diplotypes. METHODS Fifty healthy volunteers genotyped for the c.808G>T were enrolled in the study. The distribution was 25 GG, 20 GT, and 5 TT volunteers. The pharmacokinetics of a 500 mg single oral dose of metformin was studied. RESULTS When analyzed alone, the c.808 (G>T) affected neither the CL(renal) nor the secretory clearance (CL(sec)) of metformin. However, both CL(renal) and CL(sec) were increased for the volunteers with minor alleles in c.808 (G>T) who were also homozygous for the reference variant g.-66T>C: CL(renal): GG, GT, and TT: 28.1, 34.5, and 44.8 l/h (P = 0.004), respectively and CL(sec): GG, GT, and TT: 21.4, 27.8, and 37.6 l/h (P = 0.005), respectively. In the volunteers with minor alleles in c.808 (G>T) who were also heterozygous for g.-66T>C, both CL(renal) and CL(sec) were found to be reduced (P < 0.028) when compared with volunteers with minor alleles in c.808 (G>T) carrying the g.-66T>C reference genotype. CONCLUSION We report counteracting effects of the c.808 (G>T) and g.-66T>C on the renal elimination of metformin. When adjusted for the genetic variation g.-66T>C, our results suggest that c.808 (G>T) could have a dominant genotype to phenotype correlation.
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Mwangi IW, Ngila JC, Ndung'u P, Msagati TAM. Removal of phenolics from aqueous media using quaternised maize tassels. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2014; 134:70-79. [PMID: 24463851 DOI: 10.1016/j.jenvman.2013.12.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 12/14/2013] [Accepted: 12/21/2013] [Indexed: 06/03/2023]
Abstract
This paper reports on the preparation and modification of powdered maize tassels with polydiallyldimethylammonium chloride (polyDADMAC). The modified tassel were applied for the removal of phenolic compounds from water, through adsorption. The effect of contact time, sorbent dose, pH of the sample and the adsorption capacity were investigated at fixed temperature (25 °C). The optimum pH was 6.0 and the uptake was more than 90% within the first 10 min of contact. The adsorption prescribed to Langmuir model of monolayer adsorption implying a chemisorption process. The adsorption capacities were found to be 7.09, 8.23, 8.84 and 4.74 mg g(-1) for chlorobenzoic acid, 2,4,6-trichlorophenol, 2,4-dichlorophenol and 1,2-dihyroxybenzene respectively. These were fairly higher than many other reported systems. The removal efficiency was found to be 75, 64, 55 and 40% for Chlorobenzoic acid, 2,4,6-Trichlorophenol, 2,4-dichlorophenol and 1,2-dihyroxybenzene, respectively. This proved that quaternised maize tassels can be used as an efficient adsorbent material for removal of phenolic compounds from water and wastewater.
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Affiliation(s)
- Isaac W Mwangi
- Department of Applied Chemistry, University of Johannesburg, Doornfontein Campus, P.O Box 17011, Doornfontein 2028, South Africa; Kenyatta University, Chemistry Department, P.O Box 43844, Nairobi, Kenya
| | - J Catherine Ngila
- Department of Applied Chemistry, University of Johannesburg, Doornfontein Campus, P.O Box 17011, Doornfontein 2028, South Africa.
| | - Patrick Ndung'u
- School of Chemistry and Physics, University of KwaZulu-Natal, P/Bag X45001, Westville Durban 4000, South Africa
| | - Titus A M Msagati
- Department of Applied Chemistry, University of Johannesburg, Doornfontein Campus, P.O Box 17011, Doornfontein 2028, South Africa
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Tachikawa M, Uchida Y, Ohtsuki S, Terasaki T. Recent Progress in Blood–Brain Barrier and Blood–CSF Barrier Transport Research: Pharmaceutical Relevance for Drug Delivery to the Brain. DRUG DELIVERY TO THE BRAIN 2014. [DOI: 10.1007/978-1-4614-9105-7_2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Intestinal drug transporters: an overview. Adv Drug Deliv Rev 2013; 65:1340-56. [PMID: 23041352 DOI: 10.1016/j.addr.2012.09.042] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 02/07/2023]
Abstract
The importance of drug transporters as one of the determinants of pharmacokinetics has become increasingly evident. While much research has been conducted focusing the role of drug transporters in the liver and kidney less is known about the importance of uptake and efflux transporters identified in the intestine. Over the past years the effects of intestinal transporters have been studied using in vivo models, in situ organ perfusions, in vitro tissue preparations and cell lines. This review aims to describe up to date findings regarding the importance of intestinal transporters on drug absorption and bioavailability, highlighting areas in need of further research. Wu and Benet proposed a Biopharmaceutics Drug Disposition Classification System (BDDCS) that allows the prediction of transporter effects on the drug disposition of orally administered drugs. This review also discusses BDDCS predictions with respect to the role of intestinal transporters and intestinal transporter-metabolizing enzyme interplay on oral drug pharmacokinetics.
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The Role of Metformin in Metformin-Associated Lactic Acidosis (MALA): Case Series and Formulation of a Model of Pathogenesis. Drug Saf 2013; 36:733-46. [DOI: 10.1007/s40264-013-0038-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mannino GC, Sesti G. Individualized therapy for type 2 diabetes: clinical implications of pharmacogenetic data. Mol Diagn Ther 2013; 16:285-302. [PMID: 23018631 DOI: 10.1007/s40291-012-0002-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance, abnormally elevated hepatic glucose production, and reduced glucose-stimulated insulin secretion. Treatment with antihyperglycemic agents is initially successful in type 2 diabetes, but it is often associated with a high secondary failure rate, and the addition of insulin is eventually necessary for many patients, in order to restore acceptable glycemic control and to reduce the risk of development and progression of disease complications. Notably, even patients who appear to have similar requirements of antidiabetic regimens show great variability in drug disposition, glycemic response, tolerability, and incidence of adverse effects during treatment. Pharmacogenomics is a promising area of investigation and involves the search for genetic polymorphisms that may explain the interindividual variability in antidiabetic therapy response. The initial positive results portend that genomic efforts will be able to shed important light on variability in pharmacologic traits. In this review, we summarize the current understanding of genetic polymorphisms that may affect the responses of subjects with T2DM to antidiabetic treatment. These genes belong to three major classes: genes involved in drug metabolism and transporters that influence pharmacokinetics (including the cytochrome P450 [CYP] superfamily, the organic anion transporting polypeptide [OATP] family, and the polyspecific organic cation transporter [OCT] family); genes encoding drug targets and receptors (including peroxisome proliferator-activated receptor gamma [PPARG], the adenosine triphosphate [ATP]-sensitive potassium channel [K(ATP)], and incretin receptors); and genes involved in the causal pathway of T2DM that are able to modify the effects of drugs (including adipokines, transcription factor 7-like 2 (T cell specific, HMG-box) [TCF7L2], insulin receptor substrate 1 [IRS1], nitric oxide synthase 1 (neuronal) adaptor protein [NOS1AP], and solute carrier family 30 (zinc transporter), member 8 [SLC30A8]). In addition to these three major classes, we also review the available evidence on novel genes (CDK5 regulatory subunit associated protein 1-like 1 [CDKAL1], insulin-like growth factor 2 mRNA binding protein 2 [IGF2BP2], potassium voltage-gated channel, KQT-like subfamily, member 1 [KCNQ1], paired box 4 [PAX4] and neuronal differentiation 1 [NEUROD1] transcription factors, ataxia telangiectasia mutated [ATM], and serine racemase [SRR]) that have recently been proposed as possible modulators of therapeutic response in subjects with T2DM.
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Affiliation(s)
- Gaia Chiara Mannino
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Catanzaro, Italy
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Emami Riedmaier A, Fisel P, Nies AT, Schaeffeler E, Schwab M. Metformin and cancer: from the old medicine cabinet to pharmacological pitfalls and prospects. Trends Pharmacol Sci 2012; 34:126-35. [PMID: 23277337 DOI: 10.1016/j.tips.2012.11.005] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 11/19/2012] [Accepted: 11/26/2012] [Indexed: 12/21/2022]
Abstract
Metformin is a biguanide derivative used in the treatment of type II diabetes (T2D) and one of the world's most widely prescribed drugs. Owing to its safety profile, it has been recently promoted for a range of other indications, particularly for its role in cancer prevention. There is evidence from studies in diabetic cohorts, as well as laboratory studies, that the action of metformin depends on a balance between the concentration and duration of exposure, which depends crucially on cell- and tissue-specific pharmacological factors. Mechanistic studies have revealed the involvement of increasingly complex pathways. Yet, there are several missing links regarding the role of drug transporters and drug-drug interactions, as well as the expression levels of transporters in normal versus tumor tissues, which may affect patient exposure and dosing when metformin is used in cancer prevention. This review highlights the current knowledge on metformin action and pharmacology, including novel insights into genomic factors, with a specific focus on cancer prevention. Furthermore, future challenges that may influence therapeutic outcome will be discussed.
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Duan H, Wang J. Impaired monoamine and organic cation uptake in choroid plexus in mice with targeted disruption of the plasma membrane monoamine transporter (Slc29a4) gene. J Biol Chem 2012; 288:3535-44. [PMID: 23255610 DOI: 10.1074/jbc.m112.436972] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The choroid plexus (CP) forms the blood-cerebrospinal fluid (CSF) barrier and protects the brain from circulating metabolites, drugs, and toxins. The plasma membrane monoamine transporter (PMAT, SLC29A4) is a new polyspecific organic cation transporter that transports a wide variety of organic cations including biogenic amines, cationic drugs, and neurotoxins. PMAT is known to be expressed in the CP, but its specific role in CP transport of organic cations has not been clearly defined. Here we showed that PMAT transcript is highly expressed in human and mouse CPs, whereas transcripts of other functionally related transporters are minimally expressed in the CPs. Immunofluorescence staining further revealed that PMAT protein is localized to the apical (CSF-facing) membrane of the CP epithelium, consistent with a role of transporting organic cations from the CSF into CP epithelial cells. To further evaluate the role of PMAT in the CP, mice with targeted deletion of the Slc29a4 gene were generated and validated. Although Pmat(-/-) mice showed no overt abnormalities, the uptake of monoamines and the neurotoxin 1-methyl-4-phenylpyridinium was significantly reduced in CP tissues isolated from the knock-out mice. Together, our data demonstrated that PMAT is a major transporter for CP uptake of bioactive amines and xenobiotic cations. By removing its substrates from the CSF, PMAT may play an important role in protecting the brain from cationic neurotoxins and other potentially toxic organic cations.
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Affiliation(s)
- Haichuan Duan
- Department of Pharmaceutics, University of Washington, Seattle, Washington 98195, USA
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Ho HTB, Dahlin A, Wang J. Expression Profiling of Solute Carrier Gene Families at the Blood-CSF Barrier. Front Pharmacol 2012; 3:154. [PMID: 22936914 PMCID: PMC3426838 DOI: 10.3389/fphar.2012.00154] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/01/2012] [Indexed: 12/12/2022] Open
Abstract
The choroid plexus (CP) is a highly vascularized tissue in the brain ventricles and acts as the blood-cerebrospinal fluid (CSF) barrier (BCSFB). A main function of the CP is to secrete CSF, which is accomplished by active transport of small ions and water from the blood side to the CSF side. The CP also supplies the brain with certain nutrients, hormones, and metal ions, while removing metabolites and xenobiotics from the CSF. Numerous membrane transporters are expressed in the CP in order to facilitate the solute exchange between the blood and the CSF. The solute carrier (SLC) superfamily represents a major class of transporters in the CP that constitutes the molecular mechanisms for CP function. Recently, we systematically and quantitatively examined Slc gene expression in 20 anatomically comprehensive brain areas in the adult mouse brain using high-quality in situ hybridization data generated by the Allen Brain Atlas. Here we focus our analysis on Slc gene expression at the BCSFB using previously obtained data. Of the 252 Slc genes present in the mouse brain, 202 Slc genes were found at detectable levels in the CP. Unsupervised hierarchical cluster analysis showed that the CP Slc gene expression pattern is substantially different from the other 19 analyzed brain regions. The majority of the Slc genes in the CP are expressed at low to moderate levels, whereas 28 Slc genes are present in the CP at the highest levels. These highly expressed Slc genes encode transporters involved in CSF secretion, energy production, and transport of nutrients, hormones, neurotransmitters, sulfate, and metal ions. In this review, the functional characteristics and potential importance of these Slc transporters in the CP are discussed, with particular emphasis on their localization and physiological functions at the BCSFB.
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Affiliation(s)
- Horace T B Ho
- Department of Pharmaceutics, University of Washington Seattle, WA, USA
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The pharmacogenetics of metformin and its impact on plasma metformin steady-state levels and glycosylated hemoglobin A1c. Pharmacogenet Genomics 2012; 21:837-50. [PMID: 21989078 DOI: 10.1097/fpc.0b013e32834c0010] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The aim of this study was to evaluate the effect of genetic variations in OCT1, OCT2, MATE1, MATE 2, and PMAT on the trough steady-state plasma concentration of metformin and hemoglobin A1c (Hb1Ac). METHOD The South Danish Diabetes Study was a 2 x 2 x 2 factorial, prospective, randomized, double-blind, placebo-controlled, multicentre study. One hundred and fifty-nine patients received 1 g of metformin, twice daily continuously, and 415 repeated plasma metformin measurements were obtained after 3, 6, and 9 months of treatment. RESULTS The mean trough steady-state metformin plasma concentration was estimated to be 576 ng/ml (range, 54–4133 ng/ml, p = 0.55) and correlated to the number of reduced function alleles in OCT1 (none, one or two: 642, 542, 397 ng/ml; P = 0.001). The absolute decrease in Hb1Ac both initially and long term was also correlated to the number of reduced function alleles in OCT1 resulting in diminished pharmacodynamic effect of metformin after 6 and 24 months. CONCLUSION In a large cohort of type 2 diabetics, we either confirm or show for the first time: (a) an enormous (80-fold) variability in trough steady-state metformin plasma concentration, (b) OCT1 activity affects metformin steady-state pharmacokinetics, and (c) OCT1 genotype has a bearing on HbA1c during metformin treatment.
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Ho HTB, Xia L, Wang J. Residue Ile89 in human plasma membrane monoamine transporter influences its organic cation transport activity and sensitivity to inhibition by dilazep. Biochem Pharmacol 2012; 84:383-90. [PMID: 22562044 DOI: 10.1016/j.bcp.2012.04.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/24/2012] [Accepted: 04/27/2012] [Indexed: 01/11/2023]
Abstract
Plasma membrane monoamine transporter (PMAT) is a polyspecific organic cation transporter belonging to the equilibrative nucleoside transporter (ENT) family. Despite its distinct substrate specificity from the classic nucleoside transporters ENT1 and 2, PMAT appears to share similar protein architecture with ENT1/2 and retains low affinity binding to classic ENT inhibitors such as nitrobenzylmercaptopurine riboside (NBMPR) and the coronary vasodilators dilazep and dipyridamole. Here we investigated the role of residue Ile89, a position known to be important for ENT interaction with dilazep, dipyridamole, and nucleoside substrates, in PMAT transport function and its interaction with classic ENT inhibitors using Madin-Darby canine kidney (MDCK) cells stably expressing human PMAT. Substitution of Ile89 in PMAT with Met, the counterpart residue in ENT1, resulted in normal plasma membrane localization and protein expression. Transport kinetic analysis revealed that I89M mutant had a 2.7-fold reduction in maximal transport velocity (V(max)) with no significant change in apparent binding affinity (K(m)) towards the prototype PMAT substrate 1-methyl-4-phenylpyridinium (MPP+), suggesting that I89 is an important determinant for the catalytic activity of PMAT. Dose-dependent inhibition studies further showed that the I89M mutation significantly increased PMAT's sensitivity to dilazep by 2.5-fold without affecting its sensitivity to dipyridamole and NBMPR. Located at the extracellular end of transmembrane domain 1 of PMAT, I89 may occupy an important position close to the substrate permeation pathway and may be involved in direct interaction with the vasodilator dilazep.
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Affiliation(s)
- Horace T B Ho
- Department of Pharmaceutics, University of Washington, Seattle, WA 98195, USA.
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Itagaki S, Ganapathy V, Ho HTB, Zhou M, Babu E, Wang J. Electrophysiological characterization of the polyspecific organic cation transporter plasma membrane monoamine transporter. Drug Metab Dispos 2012; 40:1138-43. [PMID: 22396231 DOI: 10.1124/dmd.111.042432] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Plasma membrane monoamine transporter (PMAT) is a polyspecific organic cation (OC) transporter that transports a variety of endogenous biogenic amines and xenobiotic cations. Previous radiotracer uptake studies showed that PMAT-mediated OC transport is sensitive to changes in membrane potential and extracellular pH, but the precise role of membrane potential and protons on PMAT-mediated OC transport is unknown. Here, we characterized the electrophysiological properties of PMAT in Xenopus laevis oocytes using a two-microelectrode voltage-clamp approach. PMAT-mediated histamine uptake is associated with inward currents under voltage-clamp conditions, and the currents increased in magnitude as the holding membrane potential became more negative. A similar effect was also observed for another cation, nicotine. Substrate-induced currents were largely independent of Na+ but showed strong dependence on membrane potential and pH of the perfusate. Detailed kinetic analysis of histamine uptake revealed that the energizing effect of membrane potentials on PMAT transport is mainly due to an augmentation of Imax with little effect on K0.5. At most holding membrane potentials, Imax at pH 6.0 is approximately 3- to 4-fold higher than that at pH 7.5, whereas K0.5 is not dependent on pH. Together, these data unequivocally demonstrate PMAT as an electrogenic transporter and establish the physiological inside-negative membrane potential as a driving force for PMAT-mediated OC transport. The important role of membrane potential and pH in modulating the transport activity of PMAT toward OCs suggests that the in vivo activity of PMAT could be regulated by pathophysiological processes that alter physiological pH or membrane potential.
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Affiliation(s)
- Shiro Itagaki
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia, USA
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Ho HTB, Pan Y, Cui Z, Duan H, Swaan PW, Wang J. Molecular analysis and structure-activity relationship modeling of the substrate/inhibitor interaction site of plasma membrane monoamine transporter. J Pharmacol Exp Ther 2011; 339:376-85. [PMID: 21816955 DOI: 10.1124/jpet.111.184036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Plasma membrane monoamine transporter (PMAT) is a new polyspecific transporter that interacts with a wide range of structurally diverse organic cations. To map the physicochemical descriptors of cationic compounds that allow interaction with PMAT, we systematically analyzed the interactions between PMAT and three series of structural analogs of known organic cation substrates including phenylalkylamines, n-tetraalkylammonium (n-TAA) compounds, and β-carbolines. Our results showed that phenylalkylamines with a distance between the aromatic ring and the positively charged amine nitrogen atom of ∼6.4 Å confer optimal interactions with PMAT, whereas studies with n-TAA compounds revealed an excellent correlation between IC(50) values and hydrophobicity. The five β-carbolines that we tested, which possess a pyridinium-like structure and are structurally related to the neurotoxin 1-methyl-4-phenylpyridinium, inhibited PMAT with high affinity (IC(50) values of 39.1-65.5 μM). Cytotoxicity analysis further showed that cells expressing PMAT are 14- to 15-fold more sensitive to harmalan and norharmanium, suggesting that these two β-carbolines are also transportable substrates of PMAT. We then used computer-aided modeling to generate qualitative and quantitative three-dimensional pharmacophore models on the basis of 23 previously reported and currently identified PMAT inhibitors and noninhibitors. These models are characterized by a hydrogen bond donor and two to three hydrophobic features with distances between the hydrogen bond donor and hydrophobic features ranging between 5.20 and 7.02 Å. The consistency between the mapping results and observed PMAT affinity of a set of test compounds indicates that the models performed well in inhibitor prediction and could be useful for future virtual screening of new PMAT inhibitors.
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Affiliation(s)
- Horace T B Ho
- Department of Pharmaceutics, University of Washington, H272J Health Sciences Building, Seattle, WA 98195, USA
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Okura T, Kato S, Takano Y, Sato T, Yamashita A, Morimoto R, Ohtsuki S, Terasaki T, Deguchi Y. Functional characterization of rat plasma membrane monoamine transporter in the blood-brain and blood-cerebrospinal fluid barriers. J Pharm Sci 2011; 100:3924-38. [PMID: 21538354 DOI: 10.1002/jps.22594] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 04/02/2011] [Accepted: 04/12/2011] [Indexed: 01/06/2023]
Abstract
This study investigated the expression and functional roles of rat plasma membrane monoamine transporter (rPMAT) in the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier by using in vitro brain barrier model cells (TR-BBB13 and TR-CSFB3 cells) and multiple in vivo experimental techniques. Quantitative reverse transcription-polymerase chain reaction analysis showed relatively high expression of rPMAT mRNA in TR-BBB13 and TR-CSFB3 cells. 1-Methyl-4-phenylpyridinium (MPP(+) ) was transported into rPMAT-expressing cells in a sodium-independent manner. [(3) H]MPP(+) was taken up concentration dependently by TR-BBB13 and TR-CSFB3 cells with K(m) values similar to that of rPMAT-expressing cells. [(3) H]MPP(+) transports into these cells were markedly inhibited by serotonin, dopamine, and cationic drugs. rPMAT small interfering RNA (siRNA) significantly suppressed the [(3) H]MPP(+) uptake by TR-BBB13 cells. Intracerebrally injected [(3) H]MPP(+) was eliminated from the brain parenchymal region, whereas brain [(3) H]MPP(+) uptake did not increase with time during in situ brain perfusion, suggesting that the brain-to-blood transport across the BBB predominates over the blood-to-brain transport. Brain microdialysis studies revealed that the elimination across the BBB was significantly decreased by coperfusion of unlabelled MPP(+) , serotonin, or dopamine. [(3) H]MPP(+) was also eliminated from the CSF. These findings suggest that PMAT in brain barriers functions as the brain-to-blood transporter to regulate brain concentrations of organic cations including monoamines and cationic neurotoxins.
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Affiliation(s)
- Takashi Okura
- Department of Drug Disposition and Pharmacokinetics, School of Pharmaceutical Sciences, Teikyo University, Sagamihara, Japan
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Graham K, Yao S, Johnson L, Mowles D, Ng A, Wilkinson J, Young JD, Cass CE. Nucleoside transporter gene expression in wild-type and mENT1 knockout miceThis paper is one of a selection of papers published in a Special Issue entitled CSBMCB 53rd Annual Meeting — Membrane Proteins in Health and Disease, and has undergone the Journal’s usual peer review process. Biochem Cell Biol 2011; 89:236-45. [DOI: 10.1139/o10-152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Owing to the overlapping and redundant roles of the seven mammalian nucleoside transporters (NTs), which belong to two protein families (ENTs and CNTs), the physiological importance of individual NTs has been difficult to assess. Mice that have NT genes knocked out can be a valuable tool in gaining an understanding of the NT proteins. We have generated a strain of mice that is homozygous for a disruption mutation between exons 2 and 3 of the mouse equilibrative nucleoside transporter, mENT1. We have undertaken a quantitative survey of NT gene expression in 10 tissues, as well as microarray analysis of heart and kidney, from wild-type and mENT1 knockout mice. Rather than a consistent change in expression of NT genes in all tissues of mENT1 knockout mice, a complex pattern of changes was found. Some genes, such as those encoding mCNT1 and mCNT3 in colon tissue, exhibited increased expression, whereas other genes, such as those encoding mCNT2 and mENT4 in lung tissue, exhibited decreased expression. Although mCNT3 has been shown to be important in human and rat kidney tissue, we were unable to detect mCNT3 transcripts in the kidney of either the wild-type or mENT1 knockout mice, suggesting differences in renal nucleoside resorption between species.
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Affiliation(s)
- Kathryn Graham
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Sylvia Yao
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Lorelei Johnson
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Delores Mowles
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Amy Ng
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Jodi Wilkinson
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - James D. Young
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Carol E. Cass
- Cross Cancer Institute, 11560 University Avenue, Edmonton, AB T6G 1Z2, Canada
- Department of Oncology, School of Cancer, Engineering & Imaging Sciences, University of Alberta, Edmonton, AB T6G 1Z2, Canada
- Department of Physiology, School of Molecular & Systems Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Ho HTB, Wang J. Tyrosine 112 is essential for organic cation transport by the plasma membrane monoamine transporter. Biochemistry 2010; 49:7839-46. [PMID: 20687515 DOI: 10.1021/bi100560q] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Plasma membrane monoamine transporter (PMAT) is a polyspecific organic cation transporter in the solute carrier 29 (SLC29) family. Previous studies suggested that the major substrate recognition sites are located within transmembrane domains (TM) 1-6, and interaction of PMAT with organic cations may involve aromatic residues. In this study, we analyzed the roles of tyrosine and tryptophan residues located within TM1-6 with a goal of identifying potential residues involved in substrate recognition and translocation. The six tyrosines and one tryptophan in this region were each mutated to alanine followed by analysis of the mutant's membrane localization and transport activity toward 1-methyl-4-phenylpyridinium (MPP(+)), serotonin (5-HT), and dopamine. Two mutants, Y85A and Y112A, exhibited normal cell surface expressions but lost their transport activities toward organic cations. At position Y85, aromatic substitution with phenylalanine or tryptophan fully restored organic cation transport activity. Interestingly, at position Y112, phenylalanine substitution was not allowed. Tryptophan substitution at Y112 partially restored transport activity toward 5-HT and dopamine but severely impaired MPP(+) transport. Detailed kinetic analyses revealed that tryptophan substitution at Y85 and Y112 affected the apparent binding affinity (K(m)) and maximal transport velocity (V(max)) in a substrate-dependent manner. Together, our data suggest that Y85 and Y112 are important molecular determinants for PMAT function, and Y112 is indispensable for optimal interaction with organic cation substrates. Our analyses also suggest the involvement of transmembrane domains 1 and 2 in forming the substrate permeation pathway of PMAT.
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Affiliation(s)
- Horace T B Ho
- Department of Pharmaceutics, University of Washington, Seattle, Washington 98195, USA
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Suzuki T, Ohmuro A, Miyata M, Furuishi T, Hidaka S, Kugawa F, Fukami T, Tomono K. Involvement of an influx transporter in the blood-brain barrier transport of naloxone. Biopharm Drug Dispos 2010; 31:243-52. [PMID: 20437463 DOI: 10.1002/bdd.707] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Naloxone, a potent and specific opioid antagonist, has been shown in previous studies to have an influx clearance across the rat blood-brain barrier (BBB) two times greater than the efflux clearance. The purpose of the present study was to characterize the influx transport of naloxone across the rat BBB using the brain uptake index (BUI) method. The initial uptake rate of [(3)H]naloxone exhibited saturability in a concentration-dependent manner (concentration range 0.5 microM to 15 mM) in the presence of unlabeled naloxone. These results indicate that both passive diffusion and a carrier-mediated transport mechanism are operating. The in vivo kinetic parameters were estimated as follows: the Michaelis constant, K(t), was 2.99+/-0.71 mM; the maximum uptake rate, J(max), was 0.477+/-0.083 micromol/min/g brain; and the nonsaturable first-order rate constant, K(d), was 0.160+/-0.044 ml/min/g brain. The uptake of [(3)H]naloxone by the rat brain increased as the pH of the injected solution was increased from 5.5 to 8.5 and was strongly inhibited by cationic H(1)-antagonists such as pyrilamine and diphenhydramine and cationic drugs such as lidocaine and propranolol. In contrast, the BBB transport of [(3)H]naloxone was not affected by any typical substrates for organic cation transport systems such as tetraethylammonium, ergothioneine or L-carnitine or substrates for organic anion transport systems such as p-aminohippuric acid, benzylpenicillin or pravastatin. The present results suggest that a pH-dependent and saturable influx transport system that is a selective transporter for cationic H(1)-antagonists is involved in the BBB transport of naloxone in the rat.
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Affiliation(s)
- Toyofumi Suzuki
- Department of Pharmaceutics, School of Pharmacy, Nihon University, 7-7-1 Narashinodai, Funabashi, Chiba, Japan
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Inyushin M, Kucheryavykh Y, Kucheryavykh L, Sanabria P, Jiménez-Rivera C, Struganova I, Eaton M, Skatchkov S. Membrane potential and pH-dependent accumulation of decynium-22 (1,1'-diethyl-2,2'-cyanine iodide) flourencence through OCT transporters in astrocytes. BOLETIN DE LA ASOCIACION MEDICA DE PUERTO RICO 2010; 102:5-12. [PMID: 23875515 PMCID: PMC3721433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
1,1 '-Diethyl-2,2'-cyanine iodide (decynium22; D22) is a potent blocker of the organic cation family of transporters (EMT/OCT) known to move endogenous monoamines like dopamine and norepinephrine across cell membranes. Decynium22 is a cation with a relatively high affinity for all members of the OCT family in both human and rat cells. The mechanism through which decynium22 blocks OCT transporters are poorly understood. We tested the hypothesis that denynium22 may compete with monoamines utilizing OCT to permeate the cells. Using the ability of D22 to aggregate and produce fluorescence at 570 nm, we measured D22 uptake in cultured astrocytes. The rate of D22 uptake was strongly depressed by acid pH and by elevated external K+. The rate of uptake was similar to that displayed by 4-(4-(dimethylamino)-styryl)-N-methylpyridinium (ASP+), a well established substrate for OCT and high-affinity Na+-dependent monoamine transporters. These data were supported by measurement of electrogenic uptake using whole cell voltage clamp recording. Decynium22 depressed norepinephrine, but not glutamate uptake. These data are also consistent with the described OCT transporter characteristics. Taken together, our results suggest that decynium22 accumulation might be a useful instrument to study monoamine transport in the brain, and particularly in astrocytes, where they may play a prominent role in monoamine uptake during brain dysfunction related to monoamines (like Parkinson disease) and drug addiction.
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Affiliation(s)
- Mikhail Inyushin
- Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - Yuri Kucheryavykh
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - Lilia Kucheryavykh
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - Priscilla Sanabria
- Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - Carlos Jiménez-Rivera
- Department of Physiology, University of Puerto Rico, Medical Sciences Campus, San Juan, PR
| | | | - Misty Eaton
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
| | - Serguei Skatchkov
- Department of Physiology, Universidad Central del Caribe, School of Medicine, Bayamón, PR
- Department of Biochemistry, Universidad Central del Caribe, School of Medicine, Bayamón, PR
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Zhou M, Duan H, Engel K, Xia L, Wang J. Adenosine transport by plasma membrane monoamine transporter: reinvestigation and comparison with organic cations. Drug Metab Dispos 2010; 38:1798-805. [PMID: 20592246 DOI: 10.1124/dmd.110.032987] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The plasma membrane monoamine transporter (PMAT) belongs to the equilibrative nucleoside transporter family (solute carrier 29) and was alternatively named equilibrative nucleoside transporter 4. Previous studies from our laboratory characterized PMAT as a polyspecific organic cation transporter that minimally interacts with nucleosides. Recently, PMAT-mediated uptake of adenosine (a purine nucleoside) was reported, and the transporter was proposed to function as a dual nucleoside/organic cation transporter. To clarify the substrate specificity of PMAT, we comprehensively analyzed the transport activity of human PMAT toward nucleosides, nucleobases, and organic cations in heterologous expression systems under well controlled conditions. Among 12 naturally occurring nucleosides and nucleobases, only adenosine was significantly transported by PMAT. PMAT-mediated adenosine transport is saturable, pH-dependent, and membrane-potential sensitive. Under both neutral (pH 7.4) and acidic (pH 6.6) conditions, adenosine is transported by PMAT at an efficiency (V(max)/K(m)) at least 10-fold lower than that of the organic cation substrates 1-methyl-4-phenylpyridinium and serotonin. PMAT-mediated adenosine uptake rate was significantly enhanced by an acidic extracellular pH. However, the effect of acidic pH was not adenosine-specific but was common to organic cation substrates as well. Our results demonstrated that although PMAT transports adenosine, the transporter kinetically prefers organic cation substrates. Functionally, PMAT should be viewed as a polyspecific organic cation transporter rather than an archetypical nucleoside transporter.
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Affiliation(s)
- Mingyan Zhou
- University of Washington, Health Sciences Building, Seattle, WA 98195-7610, USA
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Klaassen CD, Aleksunes LM. Xenobiotic, bile acid, and cholesterol transporters: function and regulation. Pharmacol Rev 2010; 62:1-96. [PMID: 20103563 PMCID: PMC2835398 DOI: 10.1124/pr.109.002014] [Citation(s) in RCA: 561] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transporters influence the disposition of chemicals within the body by participating in absorption, distribution, and elimination. Transporters of the solute carrier family (SLC) comprise a variety of proteins, including organic cation transporters (OCT) 1 to 3, organic cation/carnitine transporters (OCTN) 1 to 3, organic anion transporters (OAT) 1 to 7, various organic anion transporting polypeptide isoforms, sodium taurocholate cotransporting polypeptide, apical sodium-dependent bile acid transporter, peptide transporters (PEPT) 1 and 2, concentrative nucleoside transporters (CNT) 1 to 3, equilibrative nucleoside transporter (ENT) 1 to 3, and multidrug and toxin extrusion transporters (MATE) 1 and 2, which mediate the uptake (except MATEs) of organic anions and cations as well as peptides and nucleosides. Efflux transporters of the ATP-binding cassette superfamily, such as ATP-binding cassette transporter A1 (ABCA1), multidrug resistance proteins (MDR) 1 and 2, bile salt export pump, multidrug resistance-associated proteins (MRP) 1 to 9, breast cancer resistance protein, and ATP-binding cassette subfamily G members 5 and 8, are responsible for the unidirectional export of endogenous and exogenous substances. Other efflux transporters [ATPase copper-transporting beta polypeptide (ATP7B) and ATPase class I type 8B member 1 (ATP8B1) as well as organic solute transporters (OST) alpha and beta] also play major roles in the transport of some endogenous chemicals across biological membranes. This review article provides a comprehensive overview of these transporters (both rodent and human) with regard to tissue distribution, subcellular localization, and substrate preferences. Because uptake and efflux transporters are expressed in multiple cell types, the roles of transporters in a variety of tissues, including the liver, kidneys, intestine, brain, heart, placenta, mammary glands, immune cells, and testes are discussed. Attention is also placed upon a variety of regulatory factors that influence transporter expression and function, including transcriptional activation and post-translational modifications as well as subcellular trafficking. Sex differences, ontogeny, and pharmacological and toxicological regulation of transporters are also addressed. Transporters are important transmembrane proteins that mediate the cellular entry and exit of a wide range of substrates throughout the body and thereby play important roles in human physiology, pharmacology, pathology, and toxicology.
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Affiliation(s)
- Curtis D Klaassen
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160-7417, USA.
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Haenisch B, Bönisch H. Interaction of the human plasma membrane monoamine transporter (hPMAT) with antidepressants and antipsychotics. Naunyn Schmiedebergs Arch Pharmacol 2009; 381:33-9. [PMID: 20012264 DOI: 10.1007/s00210-009-0479-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2009] [Accepted: 11/18/2009] [Indexed: 11/25/2022]
Abstract
Monoamine neurotransmission is efficiently terminated through synaptic reuptake of released neurotransmitters by high-affinity Na(+)- and Cl(-)-dependent neuronal monoamine transporters of the SLC6A family located in the plasma membrane of presynaptic nerve terminals. Recently, a low-affinity, high-capacity Na(+)- and Cl(-)-independent plasma membrane monoamine transporter (PMAT) belonging to the SLC29 solute carrier family has been cloned. PMAT was shown to transport monoamine neurotransmitters as well as organic cations such as 1-phenyl-4-methyl-pyridinium (MPP(+)). Thus, the PMAT which is highly expressed in the human brain may be involved in the modulation of central monoaminergic neurotransmission and it may be a target for drugs used to treat depression and schizophrenia, i.e., dysregulations of the monoamine homeostasis in the central nervous system (CNS). Therefore, we examined in transfected cells the influence on [(3)H]-MPP(+) transport by the human PMAT (hPMAT) of nine monoamine transport inhibiting antidepressants (ADs) belonging to pharmacologically diverse classes (imipramine, desipramine, amitriptyline, bupropion, fluoxetine, sertraline, paroxetine, reboxetine, and venlafaxine), of the atypical ADs tianeptine and trimipramine and of five antipsychotics (levomepromazine, haloperidol, clozapine, olanzapine, and risperidone). All examined drugs inhibited the hPMAT; however, half-maximum inhibition (IC(50)) was observed at concentrations which were much higher than reported clinical plasma concentrations of these drugs. Thus, inhibition of the hPMAT by these CNS drugs may not (or only marginally) contribute to their therapeutic effects.
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Affiliation(s)
- Britta Haenisch
- Institute of Pharmacology and Toxicology, University of Bonn, Reuterstrasse 2b, 53113, Bonn, Germany
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Clonidine transport at the mouse blood-brain barrier by a new H+ antiporter that interacts with addictive drugs. J Cereb Blood Flow Metab 2009; 29:1293-304. [PMID: 19458607 DOI: 10.1038/jcbfm.2009.54] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Identifying drug transporters and their in vivo significance will help to explain why some central nervous system (CNS) drugs cross the blood-brain barrier (BBB) and reach the brain parenchyma. We characterized the transport of the drug clonidine at the luminal BBB by in situ mouse brain perfusion. Clonidine influx was saturable, followed by Michaelis-Menten kinetics (K(m)=0.62 mmol/L, V(max)=1.76 nmol/sec per g at pH 7.40), and was insensitive to both sodium and trans-membrane potential. In vivo manipulation of intracellular and/or extracellular pH and trans-stimulation showed that clonidine was transported by an H+-coupled antiporter regulated by both proton and clonidine gradients, and that diphenhydramine was also a substrate. Organic cation transporters (Oct1-3), P-gp, and Bcrp did not alter clonidine transport at the BBB in knockout mice. Secondary or tertiary amine CNS compounds such as oxycodone, morphine, diacetylmorphine, methylenedioxyamphetamine (MDMA), cocaine, and nicotine inhibited clonidine transport. However, cationic compounds that interact with choline, Mate, Octn, and Pmat transporters did not. This suggests that clonidine is transported at the luminal mouse BBB by a new H+-coupled reversible antiporter.
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Elwi AN, Damaraju VL, Kuzma ML, Mowles DA, Baldwin SA, Young JD, Sawyer MB, Cass CE. Transepithelial fluxes of adenosine and 2′-deoxyadenosine across human renal proximal tubule cells: roles of nucleoside transporters hENT1, hENT2, and hCNT3. Am J Physiol Renal Physiol 2009; 296:F1439-51. [DOI: 10.1152/ajprenal.90411.2008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
This study examined the roles of human nucleoside transporters (hNTs) in mediating transepithelial fluxes of adenosine, 2′-deoxyadenosine, and three purine nucleoside anti-cancer drugs across polarized monolayers of human renal proximal tubule cells (hRPTCs), which were shown in previous studies to have human equilibrative NT 1 (hENT1) and 2 (hENT2) and human concentrative NT 3 (hCNT3) activities ( 11 ). Early passage hRPTCs were cultured on transwell inserts under conditions that induced formation of polarized monolayers with experimentally accessible apical and basolateral domains. Polarized hRPTC cultures were monitored for inhibitor sensitivities and sodium-dependence of the following: 1) transepithelial fluxes of radiolabeled adenosine, 2′-deoxyadenosine, fludarabine (9-β-d-arabinosyl-2-fluoroadenine), cladribine (2-chloro-2′-deoxyadenosine), and clofarabine (2-chloro-2′-fluoro-deoxy-9-β-d-arabinofuranosyladenine); 2) mediated uptake of radiolabeled adenosine, 2′-deoxyadenosine, fludarabine, cladribine, and clofarabine from either apical or basolateral surfaces; and 3) relative apical cell surface hCNT3 protein levels. Transepithelial fluxes of adenosine were mediated from apical-to-basolateral sides by apical hCNT3 and basolateral hENT2, whereas transepithelial fluxes of 2′-deoxyadenosine were mediated from basolateral-to-apical sides by apical hENT1 and basolateral human organic anion transporters (hOATs). The transepithelial fluxes of adenosine, hCNT3-mediated cellular uptake of adenosine, and relative apical cell surface hCNT3 protein levels correlated positively in polarized hRPTCs. The purine nucleoside anti-cancer drugs fludarabine, cladribine, and clofarabine, like adenosine exhibited apical-to-basolateral fluxes. Collectively, this evidence suggested that apical hCNT3 and basolateral hENT2 are involved in proximal tubular reabsorption of adenosine and some nucleoside drugs and that apical hENT1 and basolateral hOATs are involved in proximal tubular secretion of 2′-deoxyadenosine.
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