1
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Zhang W, Liu QY, Haqqani AS, Liu Z, Sodja C, Leclerc S, Baumann E, Delaney CE, Brunette E, Stanimirovic DB. Differential Expression of ABC Transporter Genes in Brain Vessels vs. Peripheral Tissues and Vessels from Human, Mouse and Rat. Pharmaceutics 2023; 15:pharmaceutics15051563. [PMID: 37242805 DOI: 10.3390/pharmaceutics15051563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/13/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
BACKGROUND ATP-binding cassette (ABC) transporters comprise a superfamily of genes encoding membrane proteins with nucleotide-binding domains (NBD). These transporters, including drug efflux across the blood-brain barrier (BBB), carry a variety of substrates through plasma membranes against substrate gradients, fueled by hydrolyzing ATP. The expression patterns/enrichment of ABC transporter genes in brain microvessels compared to peripheral vessels and tissues are largely uncharacterized. METHODS In this study, the expression patterns of ABC transporter genes in brain microvessels, peripheral tissues (lung, liver and spleen) and lung vessels were investigated using RNA-seq and WesTM analyses in three species: human, mouse and rat. RESULTS The study demonstrated that ABC drug efflux transporter genes (including ABCB1, ABCG2, ABCC4 and ABCC5) were highly expressed in isolated brain microvessels in all three species studied; the expression of ABCB1, ABCG2, ABCC1, ABCC4 and ABCC5 was generally higher in rodent brain microvessels compared to those of humans. In contrast, ABCC2 and ABCC3 expression was low in brain microvessels, but high in rodent liver and lung vessels. Overall, most ABC transporters (with the exception of drug efflux transporters) were enriched in peripheral tissues compared to brain microvessels in humans, while in rodent species, additional ABC transporters were found to be enriched in brain microvessels. CONCLUSIONS This study furthers the understanding of species similarities and differences in the expression patterns of ABC transporter genes; this is important for translational studies in drug development. In particular, CNS drug delivery and toxicity may vary among species depending on their unique profiles of ABC transporter expression in brain microvessels and BBB.
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Affiliation(s)
- Wandong Zhang
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Qing Yan Liu
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Arsalan S Haqqani
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Ziying Liu
- Scientific Data Mining/Digital Technology Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Caroline Sodja
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Sonia Leclerc
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Ewa Baumann
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Christie E Delaney
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Eric Brunette
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
| | - Danica B Stanimirovic
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
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2
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A Structure-Based View on ABC-Transporter Linked to Multidrug Resistance. Molecules 2023; 28:molecules28020495. [PMID: 36677553 PMCID: PMC9862083 DOI: 10.3390/molecules28020495] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 11/29/2022] [Accepted: 12/16/2022] [Indexed: 01/06/2023] Open
Abstract
The discovery of the first ATP-binding cassette (ABC) transporter, whose overexpression in cancer cells is responsible for exporting anticancer drugs out of tumor cells, initiated enormous efforts to overcome tumor cell multidrug resistance (MDR) by inhibition of ABC-transporter. Because of its many physiological functions, diverse studies have been conducted on the mechanism, function and regulation of this important group of transmembrane transport proteins. In this review, we will focus on the structural aspects of this transporter superfamily. Since the resolution revolution of electron microscope, experimentally solved structures increased rapidly. A summary of the structures available and an overview of recent structure-based studies are provided. More specifically, the artificial intelligence (AI)-based predictions from AlphaFold-2 will be discussed.
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3
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Wong ILK, Zhu X, Chan KF, Liu Z, Chan CF, Chow TS, Chong TC, Law MC, Cui J, Chow LMC, Chan TH. Flavonoid Monomers as Potent, Nontoxic, and Selective Modulators of the Breast Cancer Resistance Protein (ABCG2). J Med Chem 2021; 64:14311-14331. [PMID: 34606270 DOI: 10.1021/acs.jmedchem.1c00779] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We synthesize various substituted triazole-containing flavonoids and identify potent, nontoxic, and highly selective BCRP inhibitors. Ac18Az8, Ac32Az19, and Ac36Az9 possess m-methoxycarbonylbenzyloxy substitution at C-3 of the flavone moiety and substituted triazole at C-4' of the B-ring. They show low toxicity (IC50 toward L929 > 100 μM), potent BCRP-inhibitory activity (EC50 = 1-15 nM), and high BCRP selectivity (BCRP selectivity over MRP1 and P-gp > 67-714). They inhibit the efflux activity of BCRP, elevate the intracellular drug accumulation, and restore the drug sensitivity of BCRP-overexpressing cells. Like Ko143, Ac32Az19 remarkably exhibits a 100% 5D3 shift, indicating that it can bind and cause a conformational change of BCRP. Moreover, it significantly reduces the abundance of functional BCRP dimers/oligomers by half to retain more mitoxantrone in the BCRP-overexpressing cell line and that may account for its inhibitory activity. They are promising candidates to be developed into combination therapy to overcome MDR cancers with BCRP overexpression.
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Affiliation(s)
- Iris L K Wong
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Xuezhen Zhu
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Kin-Fai Chan
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Zhen Liu
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Chin-Fung Chan
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Tsun Sing Chow
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Tsz Cheung Chong
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Man Chun Law
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Jiahua Cui
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Larry M C Chow
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China
| | - Tak Hang Chan
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery, Hong Kong Polytechnic University, Hong Kong SAR 999077, China.,Department of Chemistry, McGill University, Montreal, Quebec H3A 2K6, Canada
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4
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Eckenstaler R, Benndorf RA. 3D structure of the transporter ABCG2-What's new? Br J Pharmacol 2020; 177:1485-1496. [PMID: 31985041 PMCID: PMC7060357 DOI: 10.1111/bph.14991] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/20/2019] [Accepted: 01/07/2020] [Indexed: 12/13/2022] Open
Abstract
ABCG2 belongs to the ABC transporter superfamily and functions as a poly-specific efflux pump. As it can transport a broad spectrum of substrates out of cells, ABCG2 is thought to alter the pharmacokinetics of drugs applied to treat certain diseases. Especially, its potential to induce resistance to chemotherapy is currently the object of intense research. To foster understanding of mechanisms relevant for substrate recognition and selection of ABCG2 substrates and to finally develop selective therapeutic modulators (e.g. inhibitors) of ABCG2 transport activity, it is important to further explore the precise 3D structure of the transporter. While efforts to elucidate the three-dimensional structure of ABCG2 using X-ray crystal structure analysis have not been successful so far, high-resolution cryo-electron microscopy-based investigations have revealed exciting new insights into the structure and function of the transporter. In this review, we will focus on these seminal publications to summarize the current understanding of tertiary and quaternary structure, homodimerization or oligomerization, and functions of the ABCG2 transporter protein.
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Affiliation(s)
| | - Ralf A Benndorf
- Institute of Pharmacy, Martin-Luther-University, Halle, Germany
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5
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Amawi H, Sim HM, Tiwari AK, Ambudkar SV, Shukla S. ABC Transporter-Mediated Multidrug-Resistant Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1141:549-580. [PMID: 31571174 DOI: 10.1007/978-981-13-7647-4_12] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
ATP-binding cassette (ABC) transporters are involved in active pumping of many diverse substrates through the cellular membrane. The transport mediated by these proteins modulates the pharmacokinetics of many drugs and xenobiotics. These transporters are involved in the pathogenesis of several human diseases. The overexpression of certain transporters by cancer cells has been identified as a key factor in the development of resistance to chemotherapeutic agents. In this chapter, the localization of ABC transporters in the human body, their physiological roles, and their roles in the development of multidrug resistance (MDR) are reviewed. Specifically, P-glycoprotein (P-GP), multidrug resistance-associated proteins (MRPs), and breast cancer resistance protein (BCRP/ABCG2) are described in more detail. The potential of ABC transporters as therapeutic targets to overcome MDR and strategies for this purpose are discussed as well as various explanations for the lack of efficacy of ABC drug transporter inhibitors to increase the efficiency of chemotherapy.
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Affiliation(s)
- Haneen Amawi
- Department of Pharmacy Practice, Faculty of Pharmacy, Yarmouk University, Irbid, Jordan
| | - Hong-May Sim
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Amit K Tiwari
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy & Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Suresh V Ambudkar
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Suneet Shukla
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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6
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Zhu X, Wong ILK, Chan KF, Cui J, Law MC, Chong TC, Hu X, Chow LMC, Chan TH. Triazole Bridged Flavonoid Dimers as Potent, Nontoxic, and Highly Selective Breast Cancer Resistance Protein (BCRP/ABCG2) Inhibitors. J Med Chem 2019; 62:8578-8608. [PMID: 31465686 DOI: 10.1021/acs.jmedchem.9b00963] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present work describes the syntheses of diverse triazole bridged flavonoid dimers and identifies potent, nontoxic, and highly selective BCRP inhibitors. A homodimer, Ac22(Az8)2, with m-methoxycarbonylbenzyloxy substitution at C-3 of the flavone moieties and a bis-triazole-containing linker (21 atoms between the two flavones) showed low toxicity (IC50 toward L929, 3T3, and HFF-1 > 100 μM), potent BCRP-inhibitory activity (EC50 = 1-2 nM), and high BCRP selectivity (BCRP selectivity over MRP1 and P-gp > 455-909). Ac22(Az8)2 inhibits BCRP-ATPase activity, blocks the drug efflux activity of BCRP, elevates the intracellular drug accumulation, and finally restores the drug sensitivity of BCRP-overexpressing cells. It does not down-regulate the surface BCRP protein expression to enhance the drug retention. Therefore, Ac22(Az8)2 and similar flavonoid dimers appear to be promising candidates for further development into combination therapy to overcome MDR cancers with BCRP overexpression.
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Affiliation(s)
- Xuezhen Zhu
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Iris L K Wong
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Kin-Fai Chan
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Jiahua Cui
- School of Environmental Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , China
| | - Man Chun Law
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Tsz Cheung Chong
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Xuesen Hu
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Larry M C Chow
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China
| | - Tak Hang Chan
- Department of Applied Biology and Chemical Technology and State Key Laboratory of Chemical Biology and Drug Discovery , Hong Kong Polytechnic University , Hong Kong SAR, China.,Department of Chemistry , McGill University , Montreal , Quebec H3A 2K6 , Canada
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7
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Crawford RR, Potukuchi PK, Schuetz EG, Schuetz JD. Beyond Competitive Inhibition: Regulation of ABC Transporters by Kinases and Protein-Protein Interactions as Potential Mechanisms of Drug-Drug Interactions. Drug Metab Dispos 2018. [PMID: 29514827 DOI: 10.1124/dmd.118.080663] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ATP-binding cassette (ABC) transporters are transmembrane efflux transporters mediating the extrusion of an array of substrates ranging from amino acids and lipids to xenobiotics, and many therapeutic compounds, including anticancer drugs. The ABC transporters are also recognized as important contributors to pharmacokinetics, especially in drug-drug interactions and adverse drug effects. Drugs and xenobiotics, as well as pathologic conditions, can influence the transcription of ABC transporters, or modify their activity or intracellular localization. Kinases can affect the aforementioned processes for ABC transporters as do protein interactions. In this review, we focus on the ABC transporters ABCB1, ABCB11, ABCC1, ABCC4, and ABCG2 and illustrate how kinases and protein-protein interactions affect these transporters. The clinical relevance of these factors is currently unknown; however, these examples suggest that our understanding of drug-drug interactions will benefit from further knowledge of how kinases and protein-protein interactions affect ABC transporters.
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Affiliation(s)
- Rebecca R Crawford
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Praveen K Potukuchi
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Erin G Schuetz
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - John D Schuetz
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee
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8
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Teodori E, Dei S, Bartolucci G, Perrone MG, Manetti D, Romanelli MN, Contino M, Colabufo NA. Structure-Activity Relationship Studies on 6,7-Dimethoxy-2-phenethyl-1,2,3,4-tetrahydroisoquinoline Derivatives as Multidrug Resistance Reversers. ChemMedChem 2017; 12:1369-1379. [DOI: 10.1002/cmdc.201700239] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/01/2017] [Indexed: 01/30/2023]
Affiliation(s)
- Elisabetta Teodori
- Dipartimento NEUROFARBA-Sezione di Farmaceutica e Nutraceutica; Università di Firenze; via Ugo Schiff 6 50019 Sesto Fiorentino FI Italy
| | - Silvia Dei
- Dipartimento NEUROFARBA-Sezione di Farmaceutica e Nutraceutica; Università di Firenze; via Ugo Schiff 6 50019 Sesto Fiorentino FI Italy
| | - Gianluca Bartolucci
- Dipartimento NEUROFARBA-Sezione di Farmaceutica e Nutraceutica; Università di Firenze; via Ugo Schiff 6 50019 Sesto Fiorentino FI Italy
| | - Maria Grazia Perrone
- Dipartimento di Farmacia-Scienze del Farmaco; Università degli Studi di Bari “A. Moro”; via Orabona 4 70125 Bari Italy
| | - Dina Manetti
- Dipartimento NEUROFARBA-Sezione di Farmaceutica e Nutraceutica; Università di Firenze; via Ugo Schiff 6 50019 Sesto Fiorentino FI Italy
| | - Maria Novella Romanelli
- Dipartimento NEUROFARBA-Sezione di Farmaceutica e Nutraceutica; Università di Firenze; via Ugo Schiff 6 50019 Sesto Fiorentino FI Italy
| | - Marialessandra Contino
- Dipartimento di Farmacia-Scienze del Farmaco; Università degli Studi di Bari “A. Moro”; via Orabona 4 70125 Bari Italy
| | - Nicola Antonio Colabufo
- Dipartimento di Farmacia-Scienze del Farmaco; Università degli Studi di Bari “A. Moro”; via Orabona 4 70125 Bari Italy
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9
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Abstract
ABCG2 is one of at least three human ATP binding cassette (ABC) transporters which can facilitate the export from cells of a wide range of chemically unrelated drug molecules. This capacity for multidrug transport is not only a confounding factor in chemotherapy, but is also one of the more perplexing phenomena in transporter biochemistry. Since its discovery in the last decade of the 20th century much has been revealed about ABCG2’s localization, physiological function and its broad substrate range. There have also been many investigations of its structure and molecular mechanism. In this mini review article we take a Rumsfeldian approach to ABCG2 and essentially ask what we do know about this transporter, and what we will need to know about this transporter if we wish to use modulation of ABCG2 activity as a therapeutic approach.
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10
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Krapf MK, Gallus J, Wiese M. 4-Anilino-2-pyridylquinazolines and -pyrimidines as Highly Potent and Nontoxic Inhibitors of Breast Cancer Resistance Protein (ABCG2). J Med Chem 2017; 60:4474-4495. [PMID: 28471656 DOI: 10.1021/acs.jmedchem.7b00441] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Multidrug resistance (MDR) mediated by ATP-binding cassette (ABC) transport proteins remains a major problem in the chemotherapeutic treatment of cancer and might be overcome by inhibition of the transporter. Because of the lack of understanding, the complex mechanisms involved in the transport process, in particular for breast cancer resistance protein (BCRP/ABCG2), there is a persistent need for studies of inhibitors of ABCG2. In this study, we investigated a systematic series of 4-substituted-2-pyridylquinazolines in terms of their inhibitory potency as well as selectivity toward ABCG2. For comparison, the quinazoline scaffold was reduced to the significantly smaller 4-methylpyrimidine basic structure. Furthermore, the cytotoxicity and the ability to reverse MDR was tested with the chemotherapeutic agents SN-38 and mitoxantrone (MX). Interaction of the compounds with ABCG2 was investigated by a colorimetric ATPase assay. Enzyme kinetic studies were carried out with Hoechst 33342 as fluorescent dye and substrate of ABCG2 to elucidate the compounds binding modes.
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Affiliation(s)
- Michael K Krapf
- Pharmaceutical Institute, University of Bonn , An der Immenburg 4, 53121 Bonn, Germany
| | - Jennifer Gallus
- Pharmaceutical Institute, University of Bonn , An der Immenburg 4, 53121 Bonn, Germany
| | - Michael Wiese
- Pharmaceutical Institute, University of Bonn , An der Immenburg 4, 53121 Bonn, Germany
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11
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Toussaint F, Pierman B, Bertin A, Lévy D, Boutry M. Purification and biochemical characterization of NpABCG5/NpPDR5, a plant pleiotropic drug resistance transporter expressed in Nicotiana tabacum BY-2 suspension cells. Biochem J 2017; 474:1689-1703. [PMID: 28298475 DOI: 10.1042/bcj20170108] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 03/13/2017] [Accepted: 03/15/2017] [Indexed: 11/17/2022]
Abstract
Pleiotropic drug resistance (PDR) transporters belong to the ABCG subfamily of ATP-binding cassette (ABC) transporters and are involved in the transport of various molecules across plasma membranes. During evolution, PDR genes appeared independently in fungi and in plants from a duplication of a half-size ABC gene. The enzymatic properties of purified PDR transporters from yeast have been characterized. This is not the case for any plant PDR transporter, or, incidentally, for any purified plant ABC transporter. Yet, plant PDR transporters play important roles in plant physiology such as hormone signaling or resistance to pathogens or herbivores. Here, we describe the expression, purification, enzymatic characterization and 2D analysis by electron microscopy of NpABCG5/NpPDR5 from Nicotiana plumbaginifolia, which has been shown to be involved in the plant defense against herbivores. We constitutively expressed NpABCG5/NpPDR5, provided with a His-tag in a homologous system: suspension cells from Nicotiana tabacum (Bright Yellow 2 line). NpABCG5/NpPDR5 was targeted to the plasma membrane and was solubilized by dodecyl maltoside and purified by Ni-affinity chromatography. The ATP-hydrolyzing specific activity (27 nmol min-1 mg-1) was stimulated seven-fold in the presence of 0.1% asolectin. Electron microscopy analysis indicated that NpABCG5/NpPDR5 is monomeric and with dimensions shorter than those of known ABC transporters. Enzymatic data (optimal pH and sensitivity to inhibitors) confirmed that plant and fungal PDR transporters have different properties. These data also show that N. tabacum suspension cells are a convenient host for the purification and biochemical characterization of ABC transporters.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5/chemistry
- ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics
- ATP Binding Cassette Transporter, Subfamily G, Member 5/isolation & purification
- ATP Binding Cassette Transporter, Subfamily G, Member 5/metabolism
- Adenosine Triphosphatases/chemistry
- Adenosine Triphosphatases/genetics
- Adenosine Triphosphatases/isolation & purification
- Adenosine Triphosphatases/metabolism
- Adenosine Triphosphate/metabolism
- Batch Cell Culture Techniques
- Bioreactors
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cell Membrane/ultrastructure
- Cells, Cultured
- Chromatography, Affinity
- Detergents/chemistry
- Glucosides/chemistry
- Hydrogen-Ion Concentration
- Image Processing, Computer-Assisted
- Membrane Transport Modulators/pharmacology
- Microscopy, Electron
- Molecular Weight
- Phosphatidylcholines/chemistry
- Plant Proteins/chemistry
- Plant Proteins/genetics
- Plant Proteins/isolation & purification
- Plant Proteins/metabolism
- Protein Conformation
- Protein Transport/drug effects
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/isolation & purification
- Recombinant Fusion Proteins/metabolism
- Solubility
- Nicotiana/cytology
- Nicotiana/enzymology
- Nicotiana/metabolism
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Affiliation(s)
- Frédéric Toussaint
- Institut des Sciences de la Vie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Baptiste Pierman
- Institut des Sciences de la Vie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris, France
| | - Daniel Lévy
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR168, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris, France
| | - Marc Boutry
- Institut des Sciences de la Vie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
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12
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Vesel M, Rapp J, Feller D, Kiss E, Jaromi L, Meggyes M, Miskei G, Duga B, Smuk G, Laszlo T, Karner I, Pongracz JE. ABCB1 and ABCG2 drug transporters are differentially expressed in non-small cell lung cancers (NSCLC) and expression is modified by cisplatin treatment via altered Wnt signaling. Respir Res 2017; 18:52. [PMID: 28340578 PMCID: PMC5364604 DOI: 10.1186/s12931-017-0537-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 03/14/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Lung cancer (LC) is still the most common cause of cancer related deaths worldwide. Non-small cell lung cancer (NSCLC) accounts for 85% of all LC cases but is not a single entity. It is now accepted that, apart from the characteristic driver mutations, the unique molecular signatures of adeno- (AC) and squamous cell carcinomas (SCC), the two most common NSCLC subtypes should be taken into consideration for their management. Therapeutic interventions, however, frequently lead to chemotherapy resistance highlighting the need for in-depth analysis of regulatory mechanisms of multidrug resistance to increase therapeutic efficiency. METHODS Non-canonical Wnt5a and canonical Wnt7b and ABC transporter expressions were tested in primary human LC (n = 90) resections of AC and SCC. To investigate drug transporter activity, a three dimensional (3D) human lung aggregate tissue model was set up using differentiated primary human lung cell types. Following modification of the canonical, beta-catenin dependent Wnt pathway or treatment with cisplatin, drug transporter analysis was performed at mRNA, protein and functional level using qRT-PCR, immunohistochemistry, immune-fluorescent staining and transport function analysis. RESULTS Non-canonical Wnt5a is significantly up-regulated in SCC samples making the microenvironment different from AC, where the beta-catenin dependent Wnt7b is more prominent. In primary cancer tissues ABCB1 and ABCG2 expression levels were different in the two NSCLC subtypes. Non-canonical rhWnt5a induced down-regulation of both ABCB1 and ABCG2 transporters in the primary human lung aggregate tissue model recreating the SCC-like transporter pattern. Inhibition of the beta-catenin or canonical Wnt pathway resulted in similar down-regulation of both ABC transporter expression and function. In contrast, cisplatin, the frequently used adjuvant chemotherapeutic agent, activated beta-catenin dependent signaling that lead to up-regulation of both ABCB1 and ABCG2 transporter expression and activity. CONCLUSIONS The difference in the Wnt microenvironment in AC and SCC leads to variations in ABC transporter expression. Cisplatin via induction of canonical Wnt signaling up-regulates ABCB1 and ABCG2 drug transporters that are not transporters for cisplatin itself but are transporters for drugs that are frequently used in combination therapy with cisplatin modulating drug response.
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Affiliation(s)
- M Vesel
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Scientific Unit, Osijek University Hospital, Huttlerova 4, Osijek, HR31000, Croatia
| | - J Rapp
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Humeltis Ltd, Pecs, Hungary
| | - D Feller
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Humeltis Ltd, Pecs, Hungary
| | - E Kiss
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Humeltis Ltd, Pecs, Hungary
| | - L Jaromi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
| | - M Meggyes
- Department of Microbiology and Immunology, School of Medicine, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
- Humeltis Ltd, Pecs, Hungary
| | - G Miskei
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary
| | - B Duga
- Humeltis Ltd, Pecs, Hungary
| | - G Smuk
- Department of Pathology, School of Medicine, University of Pecs, Pecs, Hungary
| | - T Laszlo
- Department of Pathology, School of Medicine, University of Pecs, Pecs, Hungary
| | - I Karner
- Department of Pathophysiology, Faculty of Medicine, University of Osijek, Cara Hadrijana 10, Osijek, HR31300, Croatia
| | - J E Pongracz
- Department of Pharmaceutical Biotechnology, School of Pharmacy, University of Pecs, Pecs, Hungary.
- Szentagothai Research Centre, University of Pecs, Pecs, Hungary.
- Humeltis Ltd, Pecs, Hungary.
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13
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Pires ADRA, Lecerf-Schmidt F, Guragossian N, Pazinato J, Gozzi GJ, Winter E, Valdameri G, Veale A, Boumendjel A, Di Pietro A, Pérès B. New, highly potent and non-toxic, chromone inhibitors of the human breast cancer resistance protein ABCG2. Eur J Med Chem 2016; 122:291-301. [DOI: 10.1016/j.ejmech.2016.05.053] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 04/28/2016] [Accepted: 05/22/2016] [Indexed: 12/20/2022]
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14
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Mohammad MM, Tomita N, Ohta M, Movileanu L. The Transmembrane Domain of a Bicomponent ABC Transporter Exhibits Channel-Forming Activity. ACS Chem Biol 2016; 11:2506-18. [PMID: 27379442 PMCID: PMC5026576 DOI: 10.1021/acschembio.6b00383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that expresses two unique forms of lipopolysaccharides (LPSs) on its bacterial surface, the A- and B-bands. The A-band polysaccharides (A-band PSs) are thought to be exported into the periplasm via a bicomponent ATP-binding cassette (ABC) transporter located within the inner membrane. This ABC protein complex consists of the transmembrane (TMD) Wzm and nucleotide-binding (NBD) Wzt domain proteins. Here, we were able to probe ∼1.36 nS-average conductance openings of the Wzm-based protein complex when reconstituted into a lipid membrane buffered by a 200 mM KCl solution, demonstrating the large-conductance, channel-forming ability of the TMDs. In agreement with this finding, transmission electron microscopy (TEM) imaging revealed the ring-shaped structure of the transmembrane Wzm protein complex. As hypothesized, using liposomes, we demonstrated that Wzm interacts with Wzt. Further, the Wzt polypeptide indeed hydrolyzed ATP but exhibited a ∼75% reduction in the ATPase activity when its Walker A domain was deleted. The distribution and average unitary conductance of the TMD Wzm protein complex were altered by the presence of the NBD Wzt protein, confirming the regulatory role of the latter polypeptide. To our knowledge, the large-conductance, channel-like activity of the Wzm protein complex, although often hypothesized, has not previously been demonstrated. These results constitute a platform for future structural, biophysical, and functional explorations of this bicomponent ABC transporter.
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Affiliation(s)
- Mohammad M. Mohammad
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Noriko Tomita
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
- The Syracuse Biomaterials Institute, Syracuse University, 121 Link Hall, Syracuse, New York 13244, USA
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15
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Wong K, Briddon SJ, Holliday ND, Kerr ID. Plasma membrane dynamics and tetrameric organisation of ABCG2 transporters in mammalian cells revealed by single particle imaging techniques. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:19-29. [DOI: 10.1016/j.bbamcr.2015.10.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/17/2015] [Accepted: 10/06/2015] [Indexed: 10/22/2022]
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16
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Rosenberg MF, Bikadi Z, Hazai E, Starborg T, Kelley L, Chayen NE, Ford RC, Mao Q. Three-dimensional structure of the human breast cancer resistance protein (BCRP/ABCG2) in an inward-facing conformation. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:1725-35. [PMID: 26249353 PMCID: PMC4528803 DOI: 10.1107/s1399004715010676] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 06/02/2015] [Indexed: 11/10/2022]
Abstract
ABCG2 is an efflux drug transporter that plays an important role in drug resistance and drug disposition. In this study, the first three-dimensional structure of human full-length ABCG2 analysed by electron crystallography from two-dimensional crystals in the absence of nucleotides and transported substrates is reported at 2 nm resolution. In this state, ABCG2 forms a symmetric homodimer with a noncrystallographic twofold axis perpendicular to the two-dimensional crystal plane, as confirmed by subtomogram averaging. This configuration suggests an inward-facing configuration similar to murine ABCB1, with the nucleotide-binding domains (NBDs) widely separated from each other. In the three-dimensional map, densities representing the long cytoplasmic extensions from the transmembrane domains that connect the NBDs are clearly visible. The structural data have allowed the atomic model of ABCG2 to be refined, in which the two arms of the V-shaped ABCG2 homodimeric complex are in a more closed and narrower conformation. The structural data and the refined model of ABCG2 are compatible with the biochemical analysis of the previously published mutagenesis studies, providing novel insight into the structure and function of the transporter.
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Affiliation(s)
- Mark F. Rosenberg
- Faculty of Life Science, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, England
- Computational and Systems Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, England
| | | | - Eszter Hazai
- Faculty of Life Science, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, England
| | - Tobias Starborg
- Faculty of Life Science, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, England
| | - Lawrence Kelley
- Centre for Bioinformatics, Division of Molecular Biosciences, Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, England
| | - Naomi E. Chayen
- Computational and Systems Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, England
| | - Robert C. Ford
- Faculty of Life Science, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, England
| | - Qingcheng Mao
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, WA 98195, USA
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17
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LEE YOUNGSEOK, RYU SEUNGWON, BAE SEJONG, PARK TAEHWAN, KWON KANG, NOH YUNHEE, KIM SUNGYOUNG. Cross-platform meta-analysis of multiple gene expression profiles identifies novel expression signatures in acquired anthracycline-resistant breast cancer. Oncol Rep 2015; 33:1985-93. [DOI: 10.3892/or.2015.3810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/02/2015] [Indexed: 11/06/2022] Open
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18
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Beers MF, Zhao M, Tomer Y, Russo SJ, Zhang P, Gonzales LW, Guttentag SH, Mulugeta S. Disruption of N-linked glycosylation promotes proteasomal degradation of the human ATP-binding cassette transporter ABCA3. Am J Physiol Lung Cell Mol Physiol 2013; 305:L970-80. [PMID: 24142515 DOI: 10.1152/ajplung.00184.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The lipid transport protein, ABCA3, expressed in alveolar type 2 (AT2) cells, is critical for surfactant homeostasis. The first luminal loop of ABCA3 contains three putative N-linked glycosylation sites at residues 53, 124, and 140. A common cotranslational modification, N-linked glycosylation, is critical for the proper expression of glycoproteins by enhancing folding, trafficking, and stability through augmentation of the endoplasmic reticulum (ER) folding cycle. To understand its role in ABCA3 biosynthesis, we utilized EGFP-tagged fusion constructs with either wild-type or mutant ABCA3 cDNAs that contained glutamine for asparagine substitutions at the putative glycosylation motifs. In A549 cells, inhibition of glycosylation by tunicamycin increased the electrophoretic mobility (Mr) and reduced the expression level of wild-type ABCA3 in a dose-dependent manner. Fluorescence imaging of transiently transfected A549 or primary human AT2 cells showed that although single motif mutants exhibited a vesicular distribution pattern similar to wild-type ABCA3, mutation of N124 and N140 residues resulted in a shift toward an ER-predominant distribution. By immunoblotting, the N53 mutation exhibited no effect on either the Mr or ABCA3 expression level. In contrast, substitutions at N124 or N140, as well a N124/N140 double mutation, resulted in increased electrophoretic mobility indicative of a glycosylation deficiency accompanied by reduced overall expression levels. Diminished steady-state levels of glycan-deficient ABCA3 isoforms were rescued by treatment with the proteasome inhibitor MG132. These results suggest that cotranslational N-linked glycosylation at N124 and N140 is critical for ABCA3 stability, and its disruption results in protein destabilization and proteasomal degradation.
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Affiliation(s)
- Michael F Beers
- Pulmonary, Allergy, and Critical Care Division, Univ. of Pennsylvania, Perelman School of Medicine, Smilow Center for Translational Research, Suite 11-111, 3400 Civic Center Blvd., Philadelphia, PA 19104-5159.
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19
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Eadie LN, Hughes TP, White DL. Interaction of the efflux transporters ABCB1 and ABCG2 with imatinib, nilotinib, and dasatinib. Clin Pharmacol Ther 2013; 95:294-306. [PMID: 24107928 DOI: 10.1038/clpt.2013.208] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 09/28/2013] [Indexed: 12/16/2022]
Abstract
The efflux transporters adenosine triphosphate (ATP)-binding cassette (ABC)B1 and ABCG2 have been demonstrated to interact with the tyrosine kinase inhibitors (TKIs) imatinib, nilotinib, and dasatinib. However, although some studies conclude that TKIs are substrates of one or both transporters, other studies demonstrate only an inhibitory function. This variation is probably due to differences in the concentration of TKIs assayed and the experimental systems used. This article examines the evidence for clinically relevant interactions between three currently approved TKIs and ABCB1/ABCG2.
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Affiliation(s)
- L N Eadie
- 1] Cancer Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia [2] Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - T P Hughes
- 1] Cancer Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia [2] Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia [3] Centre for Cancer Biology, Adelaide, South Australia, Australia
| | - D L White
- 1] Cancer Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia [2] Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia [3] Centre for Cancer Biology, Adelaide, South Australia, Australia
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20
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Singh DR, Mohammad MM, Patowary S, Stoneman MR, Oliver JA, Movileanu L, Raicu V. Determination of the quaternary structure of a bacterial ATP-binding cassette (ABC) transporter in living cells. Integr Biol (Camb) 2013; 5:312-23. [PMID: 23223798 DOI: 10.1039/c2ib20218b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium that affects patients with cystic fibrosis and immunocompromised individuals. This bacterium coexpresses two unique forms of lipopolysaccharides (LPSs) on its surface, the A- and B-band LPS, which are among the main virulence factors that contribute to its pathogenicity. The polysaccharides in A-band LPSs are synthesized in the cytoplasm and translocated into the periplasm via an ATP-binding cassette (ABC) transporter consisting of a transmembrane protein, Wzm, and a cytoplasmic nucleotide-binding protein, Wzt. Most of the biochemical studies of A-band PSs in Pseudomonas aeruginosa are focused on the stages of the synthesis and ligation of PS, leaving the export stage involving the ABC transporter mostly unexplored. This difficulty is compounded by the fact that the subunit composition and structure of this bi-component ABC transporter are still unknown. Here we propose a simple but powerful method, based on Förster Resonance Energy Transfer (FRET) and optical micro-spectroscopy technology, to probe the structure of dynamic (as opposed to static) protein complexes in living cells. We use this method to determine the association stoichiometry and quaternary structure of the Wzm-Wzt complex in living cells. It is found that Wzt forms a rhombus-shaped homo-tetramer which becomes a square upon co-expression with Wzm, and that Wzm forms a square-shaped homo-tetramer both in the presence and absence of Wzt. Based on these results, we propose a structural model for the double-tetramer complex formed by the bi-component ABC transporter in living cells. An understanding of the structure and behavior of this ABC transporter will help develop antibiotics targeting the biosynthesis of the A-band LPS endotoxin.
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Affiliation(s)
- Deo R Singh
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
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21
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Fotinou C, Aittoniemi J, de Wet H, Polidori A, Pucci B, Sansom MSP, Vénien-Bryan C, Ashcroft FM. Tetrameric structure of SUR2B revealed by electron microscopy of oriented single particles. FEBS J 2013; 280:1051-63. [PMID: 23253866 PMCID: PMC3599479 DOI: 10.1111/febs.12097] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 11/26/2012] [Accepted: 12/03/2012] [Indexed: 12/25/2022]
Abstract
The ATP-sensitive potassium (KATP) channel is a hetero-octameric complex that links cell metabolism to membrane electrical activity in many cells, thereby controlling physiological functions such as insulin release, muscle contraction and neuronal activity. It consists of four pore-forming Kir6.2 and four regulatory sulfonylurea receptor (SUR) subunits. SUR2B serves as the regulatory subunit in smooth muscle and some neurones. An integrative approach, combining electron microscopy and homology modelling, has been used to obtain information on the structure of this large (megadalton) membrane protein complex. Single-particle electron microscopy of purified SUR2B tethered to a lipid monolayer revealed that it assembles as a tetramer of four SUR2B subunits surrounding a central hole. In the absence of an X-ray structure, a homology model for SUR2B based on the X-ray structure of the related ABC transporter Sav1866 was used to fit the experimental images. The model indicates that the central hole can readily accommodate the transmembrane domains of the Kir tetramer, suggests a location for the first transmembrane domains of SUR2B (which are absent in Sav1866) and suggests the relative orientation of the SUR and Kir6.2 subunits.
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Affiliation(s)
- Constantina Fotinou
- Department of Physiology, Henry Wellcome Centre for Gene Function, University of Oxford, Oxford, UK
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22
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Dezi M, Fribourg PF, Cicco AD, Jault JM, Chami M, Lévy D. Binding, reconstitution and 2D crystallization of membrane or soluble proteins onto functionalized lipid layer observed in situ by reflected light microscopy. J Struct Biol 2010; 174:307-14. [PMID: 21163357 DOI: 10.1016/j.jsb.2010.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/06/2010] [Accepted: 12/08/2010] [Indexed: 12/20/2022]
Abstract
Monolayer of functionalized lipid spread at the air/water interface is used for the structural analysis of soluble and membrane proteins by electron crystallography and single particle analysis. This powerful approach lacks of a method for the screening of the binding of proteins to the surface of the lipid layer. Here, we described an optical method based on the use of reflected light microscopy to image, without the use of any labeling, the lipid layer at the surface of buffers in the Teflon wells used for 2D crystallization. Images revealed that the lipid layer was made of a monolayer coexisting with liposomes or aggregates of lipids floating at the surface. Protein binding led to an increase of the contrast and the decrease of the fluidity of the lipid surface, as demonstrated with the binding of soluble Shiga toxin B subunit, of purple membrane and of solubilized His-BmrA, a bacterial ABC transporter. Moreover the reconstitution of membrane proteins bound to the lipidic surface upon detergent removal can be followed through the appearance of large recognizable domains at the surface. Proteins binding and reconstitution were further confirmed by electron microcopy. Overall, this method provides a quick evaluation of the monolayer trials, a significant reduction in screening by transmission electron microscopy and new insights in the proteins binding and 2D crystallogenesis at the lipid surface.
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Affiliation(s)
- Manuela Dezi
- Institut Curie, Centre de Recherche, Paris F-75231, France
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