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Zámbó B, Mózner O, Bartos Z, Török G, Várady G, Telbisz Á, Homolya L, Orbán TI, Sarkadi B. Cellular expression and function of naturally occurring variants of the human ABCG2 multidrug transporter. Cell Mol Life Sci 2020; 77:365-378. [PMID: 31254042 PMCID: PMC6971004 DOI: 10.1007/s00018-019-03186-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/29/2019] [Accepted: 06/06/2019] [Indexed: 12/20/2022]
Abstract
The human ABCG2 multidrug transporter plays a crucial role in the absorption and excretion of xeno- and endobiotics; thus the relatively frequent polymorphic and mutant ABCG2 variants in the population may significantly alter disease conditions and pharmacological effects. Low-level or non-functional ABCG2 expression may increase individual drug toxicity, reduce cancer drug resistance, and result in hyperuricemia and gout. In the present work we have studied the cellular expression, trafficking, and function of nine naturally occurring polymorphic and mutant variants of ABCG2. A comprehensive analysis of the membrane localization, transport, and ATPase activity, as well as retention and degradation in intracellular compartments was performed. Among the examined variants, R147W and R383C showed expression and/or protein folding defects, indicating that they could indeed contribute to ABCG2 functional deficiency. These studies and the applied methods should significantly promote the exploration of the medical effects of these personal variants, promote potential therapies, and help to elucidate the specific role of the affected regions in the folding and function of the ABCG2 protein.
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Affiliation(s)
- Boglárka Zámbó
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - Orsolya Mózner
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - Zsuzsa Bartos
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - György Török
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - György Várady
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - Ágnes Telbisz
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - László Homolya
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - Tamás I Orbán
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary
| | - Balázs Sarkadi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudosok krt. 2, Budapest, 1117, Hungary.
- Department of Biophysics and Radiation Biology, Semmelweis University, Tuzolto u. 37-47, Budapest, 1094, Hungary.
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52
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The ABCG2 multidrug transporter is a pump gated by a valve and an extracellular lid. Nat Commun 2019; 10:5433. [PMID: 31780715 PMCID: PMC6883074 DOI: 10.1038/s41467-019-13302-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 09/02/2019] [Indexed: 12/23/2022] Open
Abstract
The human ATP-binding cassette transporter ABCG2 is a key to anticancer resistance and physiological detoxification. However, the molecular mechanism of substrate transport remains enigmatic. A hydrophobic di-leucine motif in the ABCG2 core separates a large intracellular cavity from a smaller upper cavity. We show that the di-leucine motif acts as a valve that controls drug extrusion. Moreover, the extracellular structure engages the re-entry helix and all extracellular loops to form a roof architecture on top of the upper cavity. Disulfide bridges and a salt bridge limit roof flexibility, but provide a lid-like function to control drug release. We propose that drug translocation from the central to the upper cavities through the valve is driven by a squeezing motion, suggesting that ABCG2 operates similar to a peristaltic pump. Finally, the roof contains essential residues, offering therapeutic options to block ABCG2 by either targeting the valve or essential residues in the roof. The human ATP-binding cassette transporter ABCG2 plays critical roles in anticancer resistance but the molecular mechanism of ABCG2-mediated substrate transport remains enigmatic. Here authors use extensive mutagenesis and molecular dynamics simulations to reveal a mechanistic basis for the function of the di-leucine valve and the roof organization in the transport cycle.
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53
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Wang ZZ, Zhang YF, Huang WC, Wang XP, Ni XJ, Lu HY, Hu JQ, Deng SH, Zhu XQ, Xie HS, Chen HZ, Zhang M, Qiu C, Wen YG, Shang DW. Effects of Comedication and Genetic Factors on the Population Pharmacokinetics of Lamotrigine: A Prospective Analysis in Chinese Patients With Epilepsy. Front Pharmacol 2019; 10:832. [PMID: 31404235 PMCID: PMC6669232 DOI: 10.3389/fphar.2019.00832] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 06/28/2019] [Indexed: 12/18/2022] Open
Abstract
Lamotrigine (LTG) is a second-generation anti-epileptic drug widely used for focal and generalized seizures in adults and children, and as a first-line medication in pregnant women and women of childbearing age. However, LTG pharmacokinetics shows high inter-individual variability, thus potentially leading to therapeutic failure or side effects in patients. This prospective study aimed to establish a population pharmacokinetics model for LTG in Chinese patients with epilepsy and to investigate the effects of genetic variants in uridine diphosphate glucuronosyltransferase (UGT) 1A4, UGT2B7, MDR1, ABCG2, ABCC2, and SLC22A1, as well as non-genetic factors, on LTG pharmacokinetics. The study population consisted of 89 patients with epilepsy, with 419 concentrations of LTG. A nonlinear mixed effects model was implemented in NONMEM software. A one-compartment model with first-order input and first-order elimination was found to adequately characterize LTG concentration. The population estimates of the apparent volume of distribution (V/F) and apparent clearance (CL/F) were 12.7 L and 1.12 L/h, respectively. The use of valproic acid decreased CL/F by 38.5%, whereas the co-administration of rifampicin caused an increase in CL/F of 64.7%. The CL/F decreased by 52.5% in SLC22A1-1222AA carriers. Patients with the ABCG2-34AA genotype had a 42.0% decrease in V/F, whereas patients with the MDR1-2677TT and C3435TT genotypes had a 136% increase in V/F. No obvious genetic effect of UGT enzymes was found relative to the concentrations of LTG in Chinese patients. Recommended dose regimens for patients with different gene polymorphisms and comedications were estimated on the basis of Monte Carlo simulations and the established model. These findings should be valuable for developing individualized dosage regimens in adult and adolescent Chinese patients 13–65 years of age.
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Affiliation(s)
- Zhan-Zhang Wang
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China.,Guangdong Engineering Technology Research Center for Translational Medicine of Mental Disorders, Guangzhou, China
| | - Yue-Feng Zhang
- Department of Neurology, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Wen-Can Huang
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China.,Department of Pharmacy, Guangzhou Bureau of Civil Affairs Psychiatric Hospital, Guangzhou, China
| | - Xi-Pei Wang
- Medical Research Center, Guangdong Province People's Hospital, Guangdong Academy of Medical Sciences, Cardiovascular Institute, Guangzhou, China
| | - Xiao-Jiao Ni
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Hao-Yang Lu
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Jin-Qing Hu
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Shu-Hua Deng
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Xiu-Qing Zhu
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Huan-Shan Xie
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Hong-Zhen Chen
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Ming Zhang
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Chang Qiu
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Yu-Guan Wen
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China.,Guangdong Engineering Technology Research Center for Translational Medicine of Mental Disorders, Guangzhou, China
| | - De-Wei Shang
- Department of Pharmacy, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China.,Guangdong Engineering Technology Research Center for Translational Medicine of Mental Disorders, Guangzhou, China
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54
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Mealey KL, Martinez SE, Villarino NF, Court MH. Personalized medicine: going to the dogs? Hum Genet 2019; 138:467-481. [PMID: 31032534 DOI: 10.1007/s00439-019-02020-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 04/19/2019] [Indexed: 12/13/2022]
Abstract
Interindividual variation in drug response occurs in canine patients just as it does in human patients. Although canine pharmacogenetics still lags behind human pharmacogenetics, significant life-saving discoveries in the field have been made over the last 20 years, but much remains to be done. This article summarizes the available published data about the presence and impact of genetic polymorphisms on canine drug transporters, drug-metabolizing enzymes, drug receptors/targets, and plasma protein binding while comparing them to their human counterparts when applicable. In addition, precision medicine in cancer treatment as an application of canine pharmacogenetics and pertinent considerations for canine pharmacogenetics testing is reviewed. The field is poised to transition from single pharmacogene-based studies, pharmacogenetics, to pharmacogenomic-based studies to enhance our understanding of interindividual variation of drug response in dogs. Advances made in the field of canine pharmacogenetics will not only improve the health and well-being of dogs and dog breeds, but may provide insight into individual drug efficacy and toxicity in human patients as well.
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Affiliation(s)
- Katrina L Mealey
- Program in Individualized Medicine (PrIMe), Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99163, USA.
| | - Stephanie E Martinez
- Program in Individualized Medicine (PrIMe), Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99163, USA
| | - Nicolas F Villarino
- Program in Individualized Medicine (PrIMe), Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99163, USA
| | - Michael H Court
- Program in Individualized Medicine (PrIMe), Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99163, USA
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55
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Toyoda Y, Mančíková A, Krylov V, Morimoto K, Pavelcová K, Bohatá J, Pavelka K, Pavlíková M, Suzuki H, Matsuo H, Takada T, Stiburkova B. Functional Characterization of Clinically-Relevant Rare Variants in ABCG2 Identified in a Gout and Hyperuricemia Cohort. Cells 2019; 8:E363. [PMID: 31003562 PMCID: PMC6523779 DOI: 10.3390/cells8040363] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/13/2022] Open
Abstract
ATP-binding cassette subfamily G member 2 (ABCG2) is a physiologically important urate transporter. Accumulating evidence demonstrates that congenital dysfunction of ABCG2 is an important genetic risk factor in gout and hyperuricemia; recent studies suggest the clinical significance of both common and rare variants of ABCG2. However, the effects of rare variants of ABCG2 on the risk of such diseases are not fully understood. Here, using a cohort of 250 Czech individuals of European descent (68 primary hyperuricemia patients and 182 primary gout patients), we examined exonic non-synonymous variants of ABCG2. Based on the results of direct sequencing and database information, we experimentally characterized nine rare variants of ABCG2: R147W (rs372192400), T153M (rs753759474), F373C (rs752626614), T421A (rs199854112), T434M (rs769734146), S476P (not annotated), S572R (rs200894058), D620N (rs34783571), and a three-base deletion K360del (rs750972998). Functional analyses of these rare variants revealed a deficiency in the plasma membrane localization of R147W and S572R, lower levels of cellular proteins of T153M and F373C, and null urate uptake function of T434M and S476P. Accordingly, we newly identified six rare variants of ABCG2 that showed lower or null function. Our findings contribute to deepening the understanding of ABCG2-related gout/hyperuricemia risk and the biochemical characteristics of the ABCG2 protein.
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Affiliation(s)
- Yu Toyoda
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo 113-8655, Japan.
| | - Andrea Mančíková
- Department of Cell Biology, Faculty of Science, Charles University, 128 00 Prague 2, Czech Republic.
| | - Vladimír Krylov
- Department of Cell Biology, Faculty of Science, Charles University, 128 00 Prague 2, Czech Republic.
| | - Keito Morimoto
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo 113-8655, Japan.
| | | | - Jana Bohatá
- Institute of Rheumatology, 128 50 Prague 2, Czech Republic.
| | - Karel Pavelka
- Institute of Rheumatology, 128 50 Prague 2, Czech Republic.
| | - Markéta Pavlíková
- Department of Probability and Mathematical Statistics, Faculty of Mathematics and Physics, Charles University, 121 16 Prague 2, Czech Republic.
| | - Hiroshi Suzuki
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo 113-8655, Japan.
| | - Hirotaka Matsuo
- Department of Integrative Physiology and Bio-Nano Medicine, National Defense Medical College, Saitama 359-8513, Japan.
| | - Tappei Takada
- Department of Pharmacy, The University of Tokyo Hospital, Tokyo 113-8655, Japan.
| | - Blanka Stiburkova
- Institute of Rheumatology, 128 50 Prague 2, Czech Republic.
- Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital, 121 08 Prague 2, Czech Republic.
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56
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Toyoda Y, Takada T, Suzuki H. Inhibitors of Human ABCG2: From Technical Background to Recent Updates With Clinical Implications. Front Pharmacol 2019; 10:208. [PMID: 30890942 PMCID: PMC6411714 DOI: 10.3389/fphar.2019.00208] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 02/19/2019] [Indexed: 12/30/2022] Open
Abstract
The ATP-binding cassette transporter G2 (ABCG2; also known as breast cancer resistance protein, BCRP) has been suggested to be involved in clinical multidrug resistance (MDR) in cancer like other ABC transporters such as ABCB1 (P-glycoprotein). As an efflux pump exhibiting a broad substrate specificity localized on cellular plasma membrane, ABCG2 excretes a variety of endogenous and exogenous substrates including chemotherapeutic agents, such as mitoxantrone and several tyrosine kinase inhibitors. Moreover, in the normal tissues, ABCG2 is expressed on the apical membranes and plays a pivotal role in tissue protection against various xenobiotics. For this reason, ABCG2 is recognized to be an important determinant of the pharmacokinetic characteristics of its substrate drugs. Although the clinical relevance of reversing the ABCG2-mediated MDR has been inconclusive, an appropriate modulation of ABCG2 function during chemotherapy should logically enhance the efficacy of anti-cancer agents by overcoming the MDR phenotype and/or improving their pharmacokinetics. To confirm this possibility, considerable efforts have been devoted to developing ABCG2 inhibitors, although there is no clinically available substance for this purpose. As a clue for addressing this issue, this mini-review provides integrated information covering the technical backgrounds necessary to evaluate the ABCG2 inhibitory effects on the target compounds and a current update on the ABCG2 inhibitors. This essentially includes our recent findings, as we serendipitously identified febuxostat, a well-used agent for hyperuricemia as a strong ABCG2 inhibitor, that possesses some promising potentials. We hope that an overview described here will add value to further studies involving in the multidrug transporters.
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Affiliation(s)
- Yu Toyoda
- Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Tappei Takada
- Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroshi Suzuki
- Department of Pharmacy, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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57
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ABCG2: does resolving its structure elucidate the mechanism? Biochem Soc Trans 2018; 46:1485-1494. [PMID: 30464049 DOI: 10.1042/bst20180145] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/27/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022]
Abstract
ABCG2 is one of a few human membrane transporters which display the amazing ability to transport multiple different chemicals out of cells. These multidrug pumps, which have orthologues in all organisms, are important in humans in the context of drug pharmacokinetics, especially with respect to resistance to chemotherapy. In 2016, we presented a mini-review on ABCG2 which identified many areas of exciting research progress as well as many areas of frustrating ignorance. Just 2 years on the field has advanced, particularly with respect to structural biology as the cryo-electron microscopy revolution has brought us new insights into the structure and mechanism of ABCG2. In this update, we evaluate the degree to which new data have enhanced our understanding of the structure and mechanism of ABCG2 and whether we are now in a position to translate some of these findings into inhibitor design and development.
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