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Mollick T, Darekar S, Dalarun B, Plastino F, Zhang J, Fernández AP, Alkasalias T, André H, Laín S. Retinoblastoma vulnerability to combined de novo and salvage pyrimidine ribonucleotide synthesis pharmacologic blockage. Heliyon 2024; 10:e23831. [PMID: 38332874 PMCID: PMC10851301 DOI: 10.1016/j.heliyon.2023.e23831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 12/05/2023] [Accepted: 12/13/2023] [Indexed: 02/10/2024] Open
Abstract
Retinoblastoma is an eye cancer that commonly affects young children. Despite significant advances, current treatments cause side effects even when administered locally, and patients may still have to undergo enucleation. This is particularly disheartening in cases of bilateral retinoblastoma. Hence, there is an urgent need for novel therapeutic strategies. Inhibitors of the enzyme dihydroorotate dehydrogenase (DHODH), which is involved in the de novo pyrimidine ribonucleotide synthesis pathway, have proven to be effective in preclinical trials against several cancers including pediatric cancers. Here we tested whether blocking pyrimidine ribonucleotide synthesis promotes retinoblastoma cell death. Cultured retinoblastoma cell lines were treated with small molecule inhibitors of DHODH alone or in combination with inhibitors of nucleoside uptake to also block the salvage pathway for pyrimidine ribonucleotide formation. On their own, DHODH inhibitors had a moderate killing effect. However, the combination with nucleoside uptake inhibitors greatly enhanced the effect of DHODH inhibition. In addition, we observed that pyrimidine ribonucleotide synthesis blockage can cause cell death in a p53 mutant retinoblastoma cell line derived from a patient with metastasis. Explaining these results, the analysis of a published patient cohort revealed that loss of chr16q22.2 (containing the DHODH gene) is amongst the most frequent alterations in retinoblastoma and that these tumors often show gains in chromosome regions expressing pyrimidine ribonucleotide salvage factors. Furthermore, these genome alterations associate with malignancy. These results indicate that targeting pyrimidine ribonucleotide synthesis may be an effective therapeutic strategy to consider as a treatment for retinoblastoma.
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Affiliation(s)
- Tanzina Mollick
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Suhas Darekar
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Basile Dalarun
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Flavia Plastino
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Juan Zhang
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Andres Pastor Fernández
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
| | - Twana Alkasalias
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
- General Directorate of Scientific Research Center, Salahaddin University-Erbil, Erbil, Kurdistan Region, Iraq
| | - Helder André
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Sonia Laín
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17165, Solna, Stockholm, Sweden
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2
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Hau RK, Wright SH, Cherrington NJ. Addressing the Clinical Importance of Equilibrative Nucleoside Transporters in Drug Discovery and Development. Clin Pharmacol Ther 2023; 114:780-794. [PMID: 37404197 DOI: 10.1002/cpt.2984] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 05/30/2023] [Indexed: 07/06/2023]
Abstract
The US Food and Drug Administration (FDA), European Medicines Agency (EMA), and Pharmaceuticals and Medical Devices Agency (PMDA) guidances on small-molecule drug-drug interactions (DDIs), with input from the International Transporter Consortium (ITC), recommend the evaluation of nine drug transporters. Although other clinically relevant drug uptake and efflux transporters have been discussed in ITC white papers, they have been excluded from further recommendation by the ITC and are not included in current regulatory guidances. These include the ubiquitously expressed equilibrative nucleoside transporters (ENT) 1 and ENT2, which have been recognized by the ITC for their potential role in clinically relevant nucleoside analog drug interactions for patients with cancer. Although there is comparatively limited clinical evidence supporting their role in DDI risk or other adverse drug reactions (ADRs) compared with the nine highlighted transporters, several in vitro and in vivo studies have identified ENT interactions with non-nucleoside/non-nucleotide drugs, in addition to nucleoside/nucleotide analogs. Some noteworthy examples of compounds that interact with ENTs include cannabidiol and selected protein kinase inhibitors, as well as the nucleoside analogs remdesivir, EIDD-1931, gemcitabine, and fialuridine. Consequently, DDIs involving the ENTs may be responsible for therapeutic inefficacy or off-target toxicity. Evidence suggests that ENT1 and ENT2 should be considered as transporters potentially involved in clinically relevant DDIs and ADRs, thereby warranting further investigation and regulatory consideration.
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Affiliation(s)
- Raymond K Hau
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, Arizona, USA
| | - Stephen H Wright
- Department of Physiology, College of Medicine, The University of Arizona, Tucson, Arizona, USA
| | - Nathan J Cherrington
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, Arizona, USA
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3
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Fernandez CA. Pharmacological strategies for mitigating anti-TNF biologic immunogenicity in rheumatoid arthritis patients. Curr Opin Pharmacol 2023; 68:102320. [PMID: 36580770 PMCID: PMC10540078 DOI: 10.1016/j.coph.2022.102320] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 10/19/2022] [Indexed: 12/28/2022]
Abstract
Tumor necrosis factor alpha (TNFα) inhibitors are a mainstay of treatment for rheumatoid arthritis (RA) patients after failed responses to conventional disease-modifying antirheumatic drugs (DMARDs). Despite the clinical efficacy of TNFα inhibitors (TNFi), many RA patients experience TNFi treatment failure due to the development of anti-drug antibodies (ADAs) that can neutralize drug levels and lead to RA disease relapse. Methotrexate (MTX) therapy with concomitant TNFα inhibitors decreases the risk of TNFi immunogenicity, but additional and/or alternative strategies are needed to reduce MTX-associated toxicities and to further increase its potency for preventing TNFα inhibitor immunogenicity. In this review, we highlight the limitations of MTX for mitigating TNFα inhibitor immunogenicity, and we discuss potential alternative pharmacological targets for decreasing the risk of immunogenicity during TNFα inhibitor therapy based on the key kinases, second messengers, and shared signaling mechanisms of lymphocyte receptor signaling.
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Affiliation(s)
- Christian A Fernandez
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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4
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Gao J, Zhou C, Zhong Y, Shi L, Luo X, Su H, Li M, Xu Y, Zhang N, Zhou H. Dipyridamole interacts with the N-terminal domain of HSP90 and antagonizes the function of the chaperone in multiple cancer cell lines. Biochem Pharmacol 2023; 207:115376. [PMID: 36513142 DOI: 10.1016/j.bcp.2022.115376] [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: 10/14/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
Molecular chaperone HSP90 has been considered as a promising target for anti-cancer drug development for years. However, due to the heat shock response induced by the ATP competitive inhibitors against HSP90, the therapeutic efficacies of the compounds are compromised, which consequently restricts the clinical use of HSP90-targeted inhibitors. Therefore, there is a need to discover novel HSP90-targeted modulators which exhibit acceptable inhibition activity against the chaperone and do not induce significant heat shock response in the meantime. Here in this study, we firstly developed a tip-based affinity selection-mass spectrometry platform with optimized experimental conditions/parameters for HSP90-targeted active compound screening, and then applied it to fish out inhibitors against HSP90 from a collection of 2,395 compounds composed of FDA-approved drugs and drug candidates. Dipyridamole, which acts as an anti-thrombotic agent by modulating multiple targets and has a long history of safe use, was identified to interact with HSP90's N-terminal domain. The following conducted biophysical and biochemical experiments demonstrated that Dipyridamole could bind to HSP90's ATP binding pocket and function as an ATP competitive inhibitor of the chaperone. Finally, cellular-based assays including CESTA, cell viability assessment and proteomic analysis etc. were performed to evaluate whether the interaction between HSP90 and Dipyridamole contributes to the anti-tumor effects of the compound. We then found that Dipyridamole inhibits the growth and proliferation of human cancer cells by downregulating cell cycle regulators and upregulating apoptotic cell signaling, which are potentially mediated by the binding of Dipyridamole to HSP90 and to PDEs (phosphodiesterases), respectively.
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Affiliation(s)
- Jing Gao
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Chen Zhou
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Yan Zhong
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Li Shi
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
| | - Xuanyang Luo
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Haixia Su
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Minjun Li
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Yechun Xu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Naixia Zhang
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
| | - Hu Zhou
- Analytical Research Center for Organic and Biological Molecules, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China; University of the Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China.
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5
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Heterologous (Over) Expression of Human SoLute Carrier (SLC) in Yeast: A Well-Recognized Tool for Human Transporter Function/Structure Studies. LIFE (BASEL, SWITZERLAND) 2022; 12:life12081206. [PMID: 36013385 PMCID: PMC9410066 DOI: 10.3390/life12081206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/02/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022]
Abstract
For more than 20 years, yeast has been a widely used system for the expression of human membrane transporters. Among them, more than 400 are members of the largest transporter family, the SLC superfamily. SLCs play critical roles in maintaining cellular homeostasis by transporting nutrients, ions, and waste products. Based on their involvement in drug absorption and in several human diseases, they are considered emerging therapeutic targets. Despite their critical role in human health, a large part of SLCs' is 'orphans' for substrate specificity or function. Moreover, very few data are available concerning their 3D structure. On the basis of the human health benefits of filling these knowledge gaps, an understanding of protein expression in systems that allow functional production of these proteins is essential. Among the 500 known yeast species, S. cerevisiae and P. pastoris represent those most employed for this purpose. This review aims to provide a comprehensive state-of-the-art on the attempts of human SLC expression performed by exploiting yeast. The collected data will hopefully be useful for guiding new attempts in SLCs expression with the aim to reveal new fundamental data that could lead to potential effects on human health.
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6
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Wright NJ, Lee SY. Recent advances on the inhibition of human solute carriers: Therapeutic implications and mechanistic insights. Curr Opin Struct Biol 2022; 74:102378. [PMID: 35487145 DOI: 10.1016/j.sbi.2022.102378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/02/2022] [Accepted: 03/18/2022] [Indexed: 11/03/2022]
Abstract
Solute carriers (SLCs) are membrane transport proteins tasked with mediating passage of hydrophilic molecules across lipid bilayers. Despite the extensive roles played in all aspects of human biology, SLCs remain vastly under-explored as therapeutic targets. In this brief review, we first discuss a few successful cases of drugs that exert their mechanisms of action through inhibition of human SLCs, and introduce select examples of human SLCs that have untapped therapeutic potential. We then highlight two recent structural studies which uncovered detailed structural mechanisms of inhibition exhibited against two different human major facilitator superfamily (MFS) transporters of clinical relevance.
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Affiliation(s)
- Nicholas J Wright
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA. https://twitter.com/@nick_rite
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, NC, 27710, USA.
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7
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Müller JP, Gründemann D. Does Intracellular Metabolism Render Gemcitabine Uptake Undetectable in Mass Spectrometry? Int J Mol Sci 2022; 23:ijms23094690. [PMID: 35563081 PMCID: PMC9101085 DOI: 10.3390/ijms23094690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 02/06/2023] Open
Abstract
The ergothioneine transporter ETT (formerly OCTN1; human gene symbol SLC22A4) is a powerful and highly specific transporter for the uptake of ergothioneine (ET). Recently, Sparreboom et al. reported that the ETT would transport nucleosides and nucleoside analogues such as cytarabine and gemcitabine with the highest efficiency. In our assay system, we could not detect any such transport. Subsequently, Sparreboom suggested that the intracellular metabolization of the nucleosides occurs so fast that the original compounds cannot be detected by LC–MS/MS after inward transport. Our current experiments with 293 cells disprove this hypothesis. Uptake of gemcitabine was easily detected by LC–MS/MS measurements when we expressed the Na+/nucleoside cotransporter CNT3 (SLC28A3). Inward transport was 1280 times faster than the intracellular production of gemcitabine triphosphate. The deoxycytidine kinase inhibitor 2-thio-2′-deoxycytidine markedly blocked the production of gemcitabine triphosphate. There was no concomitant surge in intracellular gemcitabine, however. This does not fit the rapid phosphorylation of gemcitabine. Uptake of cytarabine was very slow, but detection by MS was still possible. When the ETT was expressed and incubated with gemcitabine, there was no increase in intracellular gemcitabine triphosphate. We conclude that the ETT does not transport nucleosides.
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8
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Walter M, Herr P. Re-Discovery of Pyrimidine Salvage as Target in Cancer Therapy. Cells 2022; 11:cells11040739. [PMID: 35203388 PMCID: PMC8870348 DOI: 10.3390/cells11040739] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/10/2022] [Accepted: 02/18/2022] [Indexed: 02/06/2023] Open
Abstract
Nucleotides are synthesized through two distinct pathways: de novo synthesis and nucleoside salvage. Whereas the de novo pathway synthesizes nucleotides from amino acids and glucose, the salvage pathway recovers nucleosides or bases formed during DNA or RNA degradation. In contrast to high proliferating non-malignant cells, which are highly dependent on the de novo synthesis, cancer cells can switch to the nucleoside salvage pathways to maintain efficient DNA replication. Pyrimidine de novo synthesis remains the target of interest in cancer therapy and several inhibitors showed promising results in cancer cells and in vivo models. In the 1980s and 1990s, poor responses were however observed in clinical trials with several of the currently existing pyrimidine synthesis inhibitors. To overcome the observed limitations in clinical trials, targeting pyrimidine salvage alone or in combination with pyrimidine de novo inhibitors was suggested. Even though this approach showed initially promising results, it received fresh attention only recently. Here we discuss the re-discovery of targeting pyrimidine salvage pathways for DNA replication alone or in combination with inhibitors of pyrimidine de novo synthesis to overcome limitations of commonly used antimetabolites in various preclinical cancer models and clinical trials. We also highlight newly emerged targets in pyrimidine synthesis as well as pyrimidine salvage as a promising target in immunotherapy.
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9
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Cladribine as a Potential Object of Nucleoside Transporter-Based Drug Interactions. Clin Pharmacokinet 2021; 61:167-187. [PMID: 34894346 PMCID: PMC8813788 DOI: 10.1007/s40262-021-01089-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2021] [Indexed: 12/15/2022]
Abstract
Cladribine is a nucleoside analog that is phosphorylated in its target cells (B and T-lymphocytes) to its active 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. Cladribine has been shown to be a substrate of various nucleoside transporters (NTs). Intestinal absorption and distribution of cladribine throughout the body appear to be essentially mediated by equilibrative NTs (ENTs) and concentrative NTs (CNTs), specifically by ENT1, ENT2, ENT4, CNT2 (low affinity), and CNT3. Other efficient transporters of cladribine are the ABC efflux transporters, specifically breast cancer resistance protein, which likely modulates the oral absorption and renal excretion of cladribine. A key transporter for the intracellular uptake of cladribine into B and T-lymphocytes is ENT1 with ancillary contributions of ENT2 and CNT2. Transporter-based drug interactions affecting absorption and target cellular uptake of a prodrug such as cladribine are likely to reduce systemic bioavailability and target cell exposure, thereby possibly hampering clinical efficacy. In order to manage optimized therapy, i.e., to ensure uncompromised target cell uptake to preserve the full therapeutic potential of cladribine, it is important that clinicians are aware of the existence of NT-inhibiting medicinal products, various lifestyle drugs, and food components. This article reviews the existing knowledge on inhibitors of NT, which may alter cladribine absorption, distribution, and uptake into target cells, thereby summarizing the existing knowledge on optimized methods of administration and concomitant drugs that should be avoided during cladribine treatment.
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10
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Rattray Z, Deng G, Zhang S, Shirali A, May CK, Chen X, Cuffari BJ, Liu J, Zou P, Rattray NJ, Johnson CH, Dubljevic V, Campbell JA, Huttner A, Baehring JM, Zhou J, Hansen JE. ENT2 facilitates brain endothelial cell penetration and blood-brain barrier transport by a tumor-targeting anti-DNA autoantibody. JCI Insight 2021; 6:e145875. [PMID: 34128837 PMCID: PMC8410084 DOI: 10.1172/jci.insight.145875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 06/10/2021] [Indexed: 11/18/2022] Open
Abstract
The blood-brain barrier (BBB) prevents antibodies from penetrating the CNS and limits conventional antibody-based approaches to brain tumors. We now show that ENT2, a transporter that regulates nucleoside flux at the BBB, may offer an unexpected path to circumventing this barrier to allow targeting of brain tumors with an anti-DNA autoantibody. Deoxymab-1 (DX1) is a DNA-damaging autoantibody that localizes to tumors and is synthetically lethal to cancer cells with defects in the DNA damage response. We found that DX1 penetrated brain endothelial cells and crossed the BBB, and mechanistic studies identify ENT2 as the key transporter. In efficacy studies, DX1 crosses the BBB to suppress orthotopic glioblastoma and breast cancer brain metastases. ENT2-linked transport of autoantibodies across the BBB has potential to be exploited in brain tumor immunotherapy, and its discovery raises hypotheses on actionable mechanisms of CNS penetration by neurotoxic autoantibodies in CNS lupus.
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Affiliation(s)
| | - Gang Deng
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA
| | - Shenqi Zhang
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA
| | | | | | | | | | - Jun Liu
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA
| | - Pan Zou
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA
| | | | - Caroline H Johnson
- Yale School of Public Health, New Haven, Connecticut, USA.,Yale Cancer Center, New Haven, Connecticut, USA
| | | | | | - Anita Huttner
- Yale Cancer Center, New Haven, Connecticut, USA.,Department of Pathology and
| | - Joachim M Baehring
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA.,Yale Cancer Center, New Haven, Connecticut, USA.,Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Jiangbing Zhou
- Department of Neurosurgery, Yale School of Medicine, New Haven, Connecticut, USA.,Yale Cancer Center, New Haven, Connecticut, USA
| | - James E Hansen
- Department of Therapeutic Radiology and.,Yale Cancer Center, New Haven, Connecticut, USA
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11
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Rasmussen HB, Jürgens G, Thomsen R, Taboureau O, Zeth K, Hansen PE, Hansen PR. Cellular Uptake and Intracellular Phosphorylation of GS-441524: Implications for Its Effectiveness against COVID-19. Viruses 2021; 13:v13071369. [PMID: 34372575 PMCID: PMC8310262 DOI: 10.3390/v13071369] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/27/2021] [Accepted: 07/07/2021] [Indexed: 12/22/2022] Open
Abstract
GS-441524 is an adenosine analog and the parent nucleoside of the prodrug remdesivir, which has received emergency approval for treatment of COVID-19. Recently, GS-441524 has been proposed to be effective in the treatment of COVID-19, perhaps even being superior to remdesivir for treatment of this disease. Evaluation of the clinical effectiveness of GS-441524 requires understanding of its uptake and intracellular conversion to GS-441524 triphosphate, the active antiviral substance. We here discuss the potential impact of these pharmacokinetic steps of GS-441524 on the formation of its active antiviral substance and effectiveness for treatment of COVID-19. Available protein expression data suggest that several adenosine transporters are expressed at only low levels in the epithelial cells lining the alveoli in the lungs, i.e., the alveolar cells or pneumocytes from healthy lungs. This may limit uptake of GS-441524. Importantly, cellular uptake of GS-441524 may be reduced during hypoxia and inflammation due to decreased expression of adenosine transporters. Similarly, hypoxia and inflammation may lead to reduced expression of adenosine kinase, which is believed to convert GS-441524 to GS-441524 monophosphate, the perceived rate-limiting step in the intracellular formation of GS-441524 triphosphate. Moreover, increases in extracellular and intracellular levels of adenosine, which may occur during critical illnesses, has the potential to competitively decrease cellular uptake and phosphorylation of GS-441524. Taken together, tissue hypoxia and severe inflammation in COVID-19 may lead to reduced uptake and phosphorylation of GS-441524 with lowered therapeutic effectiveness as a potential outcome. Hypoxia may be particularly critical to the ability of GS-441524 to eliminate SARS-CoV-2 from tissues with low basal expression of adenosine transporters, such as alveolar cells. This knowledge may also be relevant to treatments with other antiviral adenosine analogs and anticancer adenosine analogs as well.
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Affiliation(s)
- Henrik Berg Rasmussen
- Institute of Biological Psychiatry, Mental Health Centre Sct. Hans, DK-4000 Roskilde, Denmark
- Department of Science and Environment, Roskilde University Center, DK-4000 Roskilde, Denmark; (K.Z.); (P.E.H.)
- Correspondence:
| | - Gesche Jürgens
- Clinical Pharmacology Unit, Zealand University Hospital, DK-4000 Roskilde, Denmark;
| | - Ragnar Thomsen
- Section of Forensic Chemistry, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark;
| | - Olivier Taboureau
- INSERM U1133, CNRS UMR 8251, Université de Paris, F-75013 Paris, France;
| | - Kornelius Zeth
- Department of Science and Environment, Roskilde University Center, DK-4000 Roskilde, Denmark; (K.Z.); (P.E.H.)
| | - Poul Erik Hansen
- Department of Science and Environment, Roskilde University Center, DK-4000 Roskilde, Denmark; (K.Z.); (P.E.H.)
| | - Peter Riis Hansen
- Department of Cardiology, Herlev and Gentofte Hospital, DK-2900 Hellerup, Denmark;
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12
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Zhang Y, Wernly B, Cao X, Mustafa SJ, Tang Y, Zhou Z. Adenosine and adenosine receptor-mediated action in coronary microcirculation. Basic Res Cardiol 2021; 116:22. [PMID: 33755785 PMCID: PMC7987637 DOI: 10.1007/s00395-021-00859-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 03/08/2021] [Indexed: 12/20/2022]
Abstract
Adenosine is an ubiquitous extracellular signaling molecule and plays a fundamental role in the regulation of coronary microcirculation through activation of adenosine receptors (ARs). Adenosine is regulated by various enzymes and nucleoside transporters for its balance between intra- and extracellular compartments. Adenosine-mediated coronary microvascular tone and reactive hyperemia are through receptors mainly involving A2AR activation on both endothelial and smooth muscle cells, but also involving interaction among other ARs. Activation of ARs further stimulates downstream targets of H2O2, KATP, KV and KCa2+ channels leading to coronary vasodilation. An altered adenosine-ARs signaling in coronary microcirculation has been observed in several cardiovascular diseases including hypertension, diabetes, atherosclerosis and ischemic heart disease. Adenosine as a metabolite and its receptors have been studied for its both therapeutic and diagnostic abilities. The present review summarizes important aspects of adenosine metabolism and AR-mediated actions in the coronary microcirculation.
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Affiliation(s)
- Ying Zhang
- The International Collaborative Centre On Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Bernhard Wernly
- Department of Anaesthesiology, Perioperative Medicine and Intensive Care Medicine, Paracelsus Medical University of Salzburg, Salzburg, Austria
| | - Xin Cao
- The International Collaborative Centre On Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - S Jamal Mustafa
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, USA
| | - Yong Tang
- The International Collaborative Centre On Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China
| | - Zhichao Zhou
- Division of Cardiology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, 17176, Stockholm, Sweden.
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13
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Takenaka R, Yasujima T, Furukawa J, Hishikawa Y, Yamashiro T, Ohta K, Inoue K, Yuasa H. Functional Analysis of the Role of Equilibrative Nucleobase Transporter 1 (ENBT1/SLC43A3) in Adenine Transport in HepG2 Cells. J Pharm Sci 2020; 109:2622-2628. [PMID: 32339528 DOI: 10.1016/j.xphs.2020.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 03/24/2020] [Accepted: 04/20/2020] [Indexed: 11/19/2022]
Abstract
Equilibrative nucleobase transporter 1 (ENBT1/SLC43A3) has recently been identified as a purine-selective nucleobase transporter. Although it is highly expressed in the liver, its role in nucleobase transport has not been confirmed yet in hepatocytes or any relevant cell models. We, therefore, examined its role in adenine transport in the HepG2 cell line as a human hepatocyte model. The uptake of [3H]adenine in HepG2 cells was highly saturable, indicating the involvement of carrier-mediated transport. The carrier-mediated transport component, for which the Michaelis constant was estimated to be 0.268 μM, was sensitive to decynium-22, an ENBT1 inhibitor, with the half maximal inhibitory concentration of 2.59 μM, which was comparable to that of 2.30 μM for [3H]adenine uptake by ENBT1 in its transient transfectant human embryonic kidney 293 cells. Although equilibrative nucleoside transporter 1 (ENT1/SLC29A1) and ENT2/SLC29A2 are also known to be able to transport adenine, [3H]adenine uptake in HepG2 cells was not inhibited by the ENT1/2-specific inhibitor of either dipyridamole or nitrobenzylthioinosine. Finally, [3H]adenine uptake was extensively reduced by silencing of ENBT1 by RNA interference in the hepatocyte model. All these results, taken together, suggest the predominant role of ENBT1 in the uptake of adenine in HepG2 cells.
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Affiliation(s)
- Risa Takenaka
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Tomoya Yasujima
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
| | - Junji Furukawa
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Yosuke Hishikawa
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Takahiro Yamashiro
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
| | - Kinya Ohta
- College of Pharmacy, Kinjo Gakuin University, 2-1723 Omori, Moriyama-ku, Nagoya 463-8521, Japan
| | - Katsuhisa Inoue
- Department of Biopharmaceutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
| | - Hiroaki Yuasa
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
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14
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Pechalrieu D, Assemat F, Halby L, Marcellin M, Yan P, Chaoui K, Sharma S, Chiosis G, Burlet-Schiltz O, Arimondo PB, Lopez M. Bisubstrate-Type Chemical Probes Identify GRP94 as a Potential Target of Cytosine-Containing Adenosine Analogs. ACS Chem Biol 2020; 15:952-961. [PMID: 32191434 DOI: 10.1021/acschembio.9b00965] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We synthesized affinity-based chemical probes of cytosine-adenosine bisubstrate analogs and identified several potential targets by proteomic analysis. The validation of the proteomic analysis identified the chemical probe as a specific inhibitor of glucose-regulated protein 94 (GRP94), a potential drug target for several types of cancers. Therefore, as a result of the use of bisubstrate-type chemical probes and a chemical-biology methodology, this work opens the way to the development of a new family of GRP94 inhibitors that could potentially be of therapeutic interest.
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Affiliation(s)
- Dany Pechalrieu
- ETaC, CNRS FRE3600, Centre de Recherche et Développement Pierre Fabre, Toulouse, France
| | - Fanny Assemat
- ETaC, CNRS FRE3600, Centre de Recherche et Développement Pierre Fabre, Toulouse, France
| | - Ludovic Halby
- ETaC, CNRS FRE3600, Centre de Recherche et Développement Pierre Fabre, Toulouse, France
- EpiCBio, Epigenetic Chemical Biology, Department Structural Biology and Chemistry, Institut Pasteur, CNRS UMR no. 3523, 28 rue du Dr Roux, 75015 Paris, France
| | - Marlene Marcellin
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Pengrong Yan
- Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, New York, United States
| | - Karima Chaoui
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Sahil Sharma
- Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, New York, United States
| | - Gabriela Chiosis
- Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, New York, United States
| | - Odile Burlet-Schiltz
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Paola B. Arimondo
- ETaC, CNRS FRE3600, Centre de Recherche et Développement Pierre Fabre, Toulouse, France
- EpiCBio, Epigenetic Chemical Biology, Department Structural Biology and Chemistry, Institut Pasteur, CNRS UMR no. 3523, 28 rue du Dr Roux, 75015 Paris, France
| | - Marie Lopez
- ETaC, CNRS FRE3600, Centre de Recherche et Développement Pierre Fabre, Toulouse, France
- Institut des Biomolécules Max Mousseron (IBMM), CNRS, Univ Montpellier, ENSCM UMR 5247, 240 Avenue du Prof. E. Jeanbrau, 34296 Montpellier Cedex 5, France
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15
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Chambers ED, White A, Vang A, Wang Z, Ayala A, Weng T, Blackburn M, Choudhary G, Rounds S, Lu Q. Blockade of equilibrative nucleoside transporter 1/2 protects against Pseudomonas aeruginosa-induced acute lung injury and NLRP3 inflammasome activation. FASEB J 2020; 34:1516-1531. [PMID: 31914698 PMCID: PMC7045807 DOI: 10.1096/fj.201902286r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 11/11/2022]
Abstract
Pseudomonas aeruginosa infections are increasingly multidrug resistant and cause healthcare-associated pneumonia, a major risk factor for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Adenosine is a signaling nucleoside with potential opposing effects; adenosine can either protect against acute lung injury via adenosine receptors or cause lung injury via adenosine receptors or equilibrative nucleoside transporter (ENT)-dependent intracellular adenosine uptake. We hypothesized that blockade of intracellular adenosine uptake by inhibition of ENT1/2 would increase adenosine receptor signaling and protect against P. aeruginosa-induced acute lung injury. We observed that P. aeruginosa (strain: PA103) infection induced acute lung injury in C57BL/6 mice in a dose- and time-dependent manner. Using ENT1/2 pharmacological inhibitor, nitrobenzylthioinosine (NBTI), and ENT1-null mice, we demonstrated that ENT blockade elevated lung adenosine levels and significantly attenuated P. aeruginosa-induced acute lung injury, as assessed by lung wet-to-dry weight ratio, BAL protein levels, BAL inflammatory cell counts, pro-inflammatory cytokines, and pulmonary function (total lung volume, static lung compliance, tissue damping, and tissue elastance). Using both agonists and antagonists directed against adenosine receptors A2AR and A2BR, we further demonstrated that ENT1/2 blockade protected against P. aeruginosa -induced acute lung injury via activation of A2AR and A2BR. Additionally, ENT1/2 chemical inhibition and ENT1 knockout prevented P. aeruginosa-induced lung NLRP3 inflammasome activation. Finally, inhibition of inflammasome prevented P. aeruginosa-induced acute lung injury. Our results suggest that targeting ENT1/2 and NLRP3 inflammasome may be novel strategies for prevention and treatment of P. aeruginosa-induced pneumonia and subsequent ARDS.
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Affiliation(s)
- Eboni D. Chambers
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
| | - Alexis White
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
| | - Alexander Vang
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
| | - Zhengke Wang
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
| | - Alfred Ayala
- Division of Surgical Research, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI 02908
| | - Tingting Weng
- Departments of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, TX 77030
| | - Michael Blackburn
- Departments of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, TX 77030
| | - Gaurav Choudhary
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
| | - Sharon Rounds
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
| | - Qing Lu
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Alpert Medical School of Brown University, Providence, RI 02908
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16
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Sosa Y, Deniskin R, Frame IJ, Steiginga MS, Bandyopadhyay D, Graybill TL, Kallal LA, Ouellette MT, Pope AJ, Widdowson KL, Young RJ, Akabas MH. Identification via a Parallel Hit Progression Strategy of Improved Small Molecule Inhibitors of the Malaria Purine Uptake Transporter that Inhibit Plasmodium falciparum Parasite Proliferation. ACS Infect Dis 2019; 5:1738-1753. [PMID: 31373203 DOI: 10.1021/acsinfecdis.9b00168] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Emerging resistance to current antimalarial medicines underscores the importance of identifying new drug targets and novel compounds. Malaria parasites are purine auxotrophic and import purines via the Plasmodium falciparum equilibrative nucleoside transporter type 1 (PfENT1). We previously showed that PfENT1 inhibitors block parasite proliferation in culture. Our goal was to identify additional, possibly more optimal chemical starting points for a drug discovery campaign. We performed a high throughput screen (HTS) of GlaxoSmithKline's 1.8 million compound library with a yeast-based assay to identify PfENT1 inhibitors. We used a parallel progression strategy for hit validation and expansion, with an emphasis on chemical properties in addition to potency. In one arm, the most active hits were tested for human cell toxicity; 201 had minimal toxicity. The second arm, hit expansion, used a scaffold-based substructure search with the HTS hits as templates to identify over 2000 compounds; 123 compounds had activity. Of these 324 compounds, 175 compounds inhibited proliferation of P. falciparum parasite strain 3D7 with IC50 values between 0.8 and ∼180 μM. One hundred forty-two compounds inhibited PfENT1 knockout (pfent1Δ) parasite growth, indicating they also hit secondary targets. Thirty-two hits inhibited growth of 3D7 but not pfent1Δ parasites. Thus, PfENT1 inhibition was sufficient to block parasite proliferation. Therefore, PfENT1 may be a viable target for antimalarial drug development. Six compounds with novel chemical scaffolds were extensively characterized in yeast-, parasite-, and human-erythrocyte-based assays. The inhibitors showed similar potencies against drug sensitive and resistant P. falciparum strains. They represent attractive starting points for development of novel antimalarial drugs.
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Affiliation(s)
| | | | | | - Matthew S. Steiginga
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Deepak Bandyopadhyay
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Todd L. Graybill
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Lorena A. Kallal
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Michael T. Ouellette
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Andrew J. Pope
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Katherine L. Widdowson
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
| | - Robert J. Young
- Platform Technology & Science and Discovery Partners in Academia, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
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17
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Krys D, Hamann I, Wuest M, Wuest F. Effect of hypoxia on human equilibrative nucleoside transporters hENT1 and hENT2 in breast cancer. FASEB J 2019; 33:13837-13851. [PMID: 31601121 DOI: 10.1096/fj.201900870rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Elevated proliferation rates in cancer can be visualized with positron emission tomography (PET) using 3'-deoxy-3'-l-[18F]fluorothymidine ([18F]FLT). This study investigates whether [18F]FLT transport proteins are regulated through hypoxia. Expression and function of human equilibrative nucleoside transporter (hENT)-1, hENT2, and thymidine kinase 1 (TK1) were studied under normoxic and hypoxic conditions, and assessed with [18F]FLT-PET in estrogen receptor positive (ER+)-MCF7, triple-negative MDA-MB231 breast cancer (BC) cells, and MCF10A cells (human mammary epithelial cells). Functional involvement of hENT2 [18F]FLT transport was demonstrated in all cell lines. In vitro [18F]FLT uptake was higher in MDA-MB231 than in MCF7: 242 ± 9 vs. 147 ± 18% radioactivity/mg protein after 60 min under normoxia. Hypoxia showed no significant change in radiotracer uptake. Protein analysis revealed increased hENT1 (P < 0.0963) in MDA-MB231. Hypoxia did not change expression of either hENT1, hENT2, or TK1. In vitro inhibition experiments suggested involvement of hENT1, hENT2, and human concentrative nucleoside transporters during [18F]FLT uptake into all cell lines. In vivo PET imaging revealed comparable tumor uptake in MCF7 and MDA-MB231 tumors over 60 min, reaching standardized uptake values of 0.96 ± 0.05 vs. 0.89 ± 0.08 (n = 3). Higher hENT1 expression in MDA-MB231 seems to drive nucleoside transport, whereas TK1 expression in MCF7 seems responsible for comparable [18F]FLT retention in ER+ tumors. Our study demonstrates that hypoxia does not significantly affect nucleoside transport as tested with [18F]FLT in BC.-Krys, D., Hamann, I., Wuest, M., Wuest, F. Effect of hypoxia on human equilibrative nucleoside transporters hENT1 and hENT2 in breast cancer.
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Affiliation(s)
- Daniel Krys
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - Ingrit Hamann
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - Melinda Wuest
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
| | - Frank Wuest
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Cancer Research Institute of Northern Alberta, University of Alberta, Edmonton, Alberta, Canada
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18
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Bidirectional transport of 2-chloroadenosine by equilibrative nucleoside transporter 4 (hENT4): Evidence for allosteric kinetics at acidic pH. Sci Rep 2019; 9:13555. [PMID: 31537831 PMCID: PMC6753126 DOI: 10.1038/s41598-019-49929-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/02/2019] [Indexed: 01/23/2023] Open
Abstract
Adenosine has been reported to be transported by equilibrative nucleoside transporter 4 (ENT4), encoded by the SLC29A4 gene, in an acidic pH-dependent manner. This makes hENT4 of interest as a therapeutic target in acidic pathologies where adenosine is protective (e.g. vascular ischaemia). We examined the pH-sensitivity of nucleoside influx and efflux by hENT4 using a recombinant transfection model that lacks the confounding influences of other nucleoside transporters (PK15-NTD). We established that [3H]2-chloroadenosine, which is resistant to metabolism by adenosine deaminase, is a substrate for hENT4. Transport of [3H]2-chloroadenosine at a pH of 6.0 in PK15-NTD cells stably transfected with SLC29A4 was biphasic, with a low capacity (Vmax ~ 30 pmol/mg/min) high-affinity component (Km ~ 50 µM) apparent at low substrate concentrations, which shifted to a high capacity (Vmax ~ 500 pmol/mg/min) low affinity system (Km > 600 µM) displaying positive cooperativity at concentrations above 200 µM. Only the low affinity component was observed at a neutral pH of 7.5 (Km ~ 2 mM). Efflux of [3H]2-chloroadenosine from these cells was also enhanced by more than 4-fold at an acidic pH. Enhanced influx and efflux of nucleosides by hENT4 under acidic conditions supports its potential as a therapeutic target in pathologies such as ischaemia-reperfusion injury.
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19
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Rehan S, Shahid S, Salminen TA, Jaakola VP, Paavilainen VO. Current Progress on Equilibrative Nucleoside Transporter Function and Inhibitor Design. SLAS DISCOVERY 2019; 24:953-968. [PMID: 31503511 DOI: 10.1177/2472555219870123] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Physiological nucleosides are used for the synthesis of DNA, RNA, and ATP in the cell and serve as universal mammalian signaling molecules that regulate physiological processes such as vasodilation and platelet aggregation by engaging with cell surface receptors. The same pathways that allow uptake of physiological nucleosides mediate the cellular import of synthetic nucleoside analogs used against cancer, HIV, and other viral diseases. Physiological nucleosides and nucleoside drugs are imported by two families of nucleoside transporters: the SLC28 concentrative nucleoside transporters (CNTs) and SLC29 equilibrative nucleoside transporters (ENTs). The four human ENT paralogs are expressed in distinct tissues, localize to different subcellular sites, and transport a variety of different molecules. Here we provide an overview of the known structure-function relationships of the ENT family with a focus on ligand binding and transport in the context of a new hENT1 homology model. We provide a generic residue numbering system for the different ENTs to facilitate the interpretation of mutational data produced using different ENT homologs. The discovery of paralog-selective small-molecule modulators is highly relevant for the design of new therapies and for uncovering the functions of poorly characterized ENT family members. Here, we discuss recent developments in the discovery of new paralog-selective small-molecule ENT inhibitors, including new natural product-inspired compounds. Recent progress in the ability to heterologously produce functional ENTs will allow us to gain insight into the structure and functions of different ENT family members as well as the rational discovery of highly selective inhibitors.
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Affiliation(s)
- Shahid Rehan
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland.,HiLIFE, University of Helsinki, Helsinki, Finland
| | - Saman Shahid
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Tiina A Salminen
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Veli-Pekka Jaakola
- Chemical Biology & Therapeutics, Novartis Institutes for BioMedical Research, Novartis Pharma AG, Basel, Switzerland
| | - Ville O Paavilainen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland.,HiLIFE, University of Helsinki, Helsinki, Finland
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20
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Identification, soluble expression, and characterization of a novel endo-inulinase from Lipomyces starkeyi NRRL Y-11557. Int J Biol Macromol 2019; 137:537-544. [DOI: 10.1016/j.ijbiomac.2019.06.096] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 01/13/2023]
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21
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Influence of Multidrug Resistance-Associated Proteins on the Excretion of the ABCC1 Imaging Probe 6-Bromo-7-[ 11C]Methylpurine in Mice. Mol Imaging Biol 2019; 21:306-316. [PMID: 29942989 PMCID: PMC6449286 DOI: 10.1007/s11307-018-1230-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Purpose Multidrug resistance-associated proteins (MRPs) mediate the hepatobiliary and renal excretion of many drugs and drug conjugates. The positron emission tomography (PET) tracer 6-bromo-7-[11C]methylpurine is rapidly converted in tissues by glutathione-S-transferases into its glutathione conjugate, and has been used to measure the activity of Abcc1 in the brain and the lungs of mice. Aim of this work was to investigate if the activity of MRPs in excretory organs can be measured with 6-bromo-7-[11C]methylpurine. Procedures We performed PET scans with 6-bromo-7-[11C]methylpurine in groups of wild-type, Abcc4(−/−) and Abcc1(−/−) mice, with and without pre-treatment with the prototypical MRP inhibitor MK571. Results 6-Bromo-7-[11C]methylpurine-derived radioactivity predominantly underwent renal excretion. In blood, MK571 treatment led to a significant increase in the AUC and a decrease in the elimination rate constant of radioactivity (kelimination,blood). In the kidneys, there were significant decreases in the rate constant for radioactivity uptake from the blood (kuptake,kidney), kelimination,kidney, and the rate constant for tubular secretion of radioactivity (kurine). Experiments in Abcc4(−/−) mice indicated that Abcc4 contributed to renal excretion of 6-bromo-7-[11C]methylpurine-derived radioactivity. Conclusions Our data suggest that 6-bromo-7-[11C]methylpurine may be useful to assess the activity of MRPs in the kidneys as well as in other organs (brain, lungs), although further work is needed to identify the MRP subtypes involved in the disposition of 6-bromo-7-[11C]methylpurine-derived radioactivity. Electronic supplementary material The online version of this article (10.1007/s11307-018-1230-y) contains supplementary material, which is available to authorized users.
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22
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Structures of human ENT1 in complex with adenosine reuptake inhibitors. Nat Struct Mol Biol 2019; 26:599-606. [PMID: 31235912 PMCID: PMC6705415 DOI: 10.1038/s41594-019-0245-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 05/08/2019] [Indexed: 02/06/2023]
Abstract
The human Equilibrative Nucleoside Transporter 1 (hENT1), a member of the SLC29 family, plays crucial roles in adenosine signaling, cellular uptake of nucleoside for DNA and RNA synthesis, and nucleoside-derived anticancer and antiviral drug transport in human. Because of its central role in adenosine signaling, it is the target of adenosine reuptake inhibitors (AdoRI), several of which are clinically used. Despite its importance in human physiology and pharmacology, the molecular basis of hENT1-mediated adenosine transport and its inhibition by AdoRIs are limited due to the absence of structural information on hENT1. Here we present crystal structures of hENT1 in complex with two chemically distinct AdoRIs: dilazep and S-(4-Nitrobenzyl)-6-thioinosine (NBMPR). Combined with mutagenesis study, our structural analyses elucidate two distinct inhibitory mechanisms exhibited on hENT1, while giving insight into adenosine recognition and transport. Our studies provide the platform for improved pharmacological intervention of adenosine and nucleoside analog drug transport by hENT1.
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23
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Role of cysteine 416 in N-ethylmaleimide sensitivity of human equilibrative nucleoside transporter 1 (hENT1). Biochem J 2018; 475:3293-3309. [PMID: 30254099 DOI: 10.1042/bcj20180543] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/19/2018] [Accepted: 09/25/2018] [Indexed: 12/23/2022]
Abstract
Human equilibrative nucleoside transporter 1 (hENT1), the first identified member of the ENT family of integral membrane proteins, is the primary mechanism for cellular uptake of physiologic nucleosides and many antineoplastic and antiviral nucleoside drugs. hENT1, which is potently inhibited by nitrobenzylthioinosine (NBMPR), possesses 11 transmembrane helical domains with an intracellular N-terminus and an extracellular C-terminus. As a protein with 10 endogenous cysteine residues, it is sensitive to inhibition by the membrane permeable sulfhydryl-reactive reagent N-ethylmaleimide (NEM) but is unaffected by the membrane impermeable sulfhydryl-reactive reagent p-chloromercuriphenyl sulfonate. To identify the residue(s) involved in NEM inhibition, we created a cysteine-less version of hENT1 (hENT1C-), with all 10 endogenous cysteine residues mutated to serine, and showed that it displays wild-type uridine transport and NBMPR-binding characteristics when produced in the Xenopus oocyte heterologous expression system, indicating that endogenous cysteine residues are not essential for hENT1 function. We then tested NEM sensitivity of recombinant wild-type hENT1, hENT1 mutants C1S to C10S (single cysteine residues replaced by serine), hENT1C- (all cysteine residues replaced by serine), and hENT1C- mutants S1C to S10C (single serine residues converted back to cysteine). Mutants C9S (C416S/hENT1) and S9C (S416C/hENT1C-) were insensitive and sensitive, respectively, to inhibition by NEM, identifying Cys416 as the endofacial cysteine residue in hENT1 responsible for NEM inhibition. Kinetic experiments suggested that NEM modification of Cys416, which is located at the inner extremity of TM10, results in the inhibition of hENT1 uridine transport and NBMPR binding by constraining the protein in its inward-facing conformation.
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24
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Aherne CM, Collins CB, Rapp CR, Olli KE, Perrenoud L, Jedlicka P, Bowser JL, Mills TW, Karmouty-Quintana H, Blackburn MR, Eltzschig HK. Coordination of ENT2-dependent adenosine transport and signaling dampens mucosal inflammation. JCI Insight 2018; 3:121521. [PMID: 30333323 PMCID: PMC6237472 DOI: 10.1172/jci.insight.121521] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/30/2018] [Indexed: 12/19/2022] Open
Abstract
Intestinal epithelial barrier repair is vital for remission in inflammatory bowel disease (IBD). Extracellular adenosine signaling has been implicated in promoting restoration of epithelial barrier function. Currently, no clinically approved agents target this pathway. Adenosine signaling is terminated by uptake from the extracellular space via equilibrative nucleoside transporters (ENTs). We hypothesized that ENT inhibition could dampen intestinal inflammation. Initial studies demonstrated transcriptional repression of ENT1 and ENT2 in IBD biopsies or in murine IBD models. Subsequent studies in mice with global Ent1 or Ent2 deletion revealed selective protection of Ent2-/- mice. Elevated intestinal adenosine levels in conjunction with abolished protection following pharmacologic blockade of A2B adenosine receptors implicate adenosine signaling as the mechanism of gut protection in Ent2-/- mice. Additional studies in mice with tissue-specific deletion of Ent2 uncovered epithelial Ent2 as the target. Moreover, intestinal protection provided by a selective Ent2 inhibitor was abolished in mice with epithelium-specific deletion of Ent2 or the A2B adenosine receptor. Taken together, these findings indicate that increased mucosal A2B signaling following repression or deletion of epithelial Ent2 coordinates the resolution of intestinal inflammation. This study suggests the presence of a targetable purinergic network within the intestinal epithelium designed to limit tissue inflammation.
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Affiliation(s)
- Carol M. Aherne
- Department of Anesthesiology, and
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Colm B. Collins
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Digestive Health Institute, Children’s Hospital Colorado, Aurora, Colorado, USA
| | - Caroline R. Rapp
- Department of Anesthesiology, and
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Kristine E. Olli
- Department of Anesthesiology, and
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Loni Perrenoud
- Department of Anesthesiology, and
- Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Paul Jedlicka
- Department of Pathology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jessica L. Bowser
- Department of Anesthesiology, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Tingting W. Mills
- Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Harry Karmouty-Quintana
- Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Michael R. Blackburn
- Department of Biochemistry and Molecular Biology, McGovern Medical School at UTHealth, Houston, Texas, USA
| | - Holger K. Eltzschig
- Department of Anesthesiology, and
- Department of Anesthesiology, McGovern Medical School at UTHealth, Houston, Texas, USA
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25
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Abstract
Staphylococcus aureus colonizes large segments of the human population and causes invasive infections due to its ability to escape phagocytic clearance. During infection, staphylococcal nuclease and adenosine synthase A convert neutrophil extracellular traps to deoxyadenosine (dAdo), which kills phagocytes. The mechanism whereby staphylococcal dAdo intoxicates phagocytes is not known. Here we used CRISPR-Cas9 mutagenesis to show that phagocyte intoxication involves uptake of dAdo via the human equilibrative nucleoside transporter 1, dAdo conversion to dAMP by deoxycytidine kinase and adenosine kinase, and signaling via subsequent dATP formation to activate caspase-3-induced cell death. Disruption of this signaling cascade confers resistance to dAdo-induced intoxication of phagocytes and may provide therapeutic opportunities for the treatment of infections caused by antibiotic-resistant S. aureus strains.
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Abstract
Nucleobases are water-soluble compounds that need specific transporters to cross biological membranes. Cumulative evidence based on studies using animal tissues and cells indicates that the carrier-mediated transport systems for purine and pyrimidine nucleobases can be classified into the following two types: concentrative transport systems that mediate nucleobase transport depending on the sodium ion concentration gradient; and other systems that mediate facilitated diffusion depending on the concentration gradient of the substrate. Recently, several molecular transporters that are involved in both transport systems have been identified. The function and activity of these transporters could be of pharmacological significance considering the roles that they play not only in nucleotide synthesis and metabolism but also in the pharmacokinetics and delivery of a variety of nucleobase analogues used in anticancer and antiviral drug therapy. The present review provides an overview of the recent advances in our understanding of the molecular basis of nucleobase transport systems, focusing on the transporters that mediate purine nucleobases, and discusses the involvement of intracellular metabolism in purine nucleobase transport and chemotherapy using ganciclovir.
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Affiliation(s)
- Katsuhisa Inoue
- Department of Biopharmaceutics, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
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27
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Sharma HP, Halder N, Singh SB, Velpandian T. Involvement of nucleoside transporters in the transcorneal permeation of topically instilled substrates in rabbits in-vivo. Eur J Pharm Sci 2018; 114:364-371. [DOI: 10.1016/j.ejps.2017.12.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 11/09/2017] [Accepted: 12/29/2017] [Indexed: 01/02/2023]
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28
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Vector-independent transmembrane transport of oligodeoxyribonucleotides involves p38 mitogen activated protein kinase phosphorylation. Sci Rep 2017; 7:13571. [PMID: 29051621 PMCID: PMC5648841 DOI: 10.1038/s41598-017-14099-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 10/02/2017] [Indexed: 11/20/2022] Open
Abstract
The main roles of equilibrative nucleoside transporters (ENTs) and concentrative nucleoside transporters (CNTs) are to transfer single nucleosides and analogues for the nucleic acid salvage pathway. Oligodeoxyribonucleotides (ODNs) can be transported into the cytoplasm or nucleus of cells under certain conditions. Among ODNs composed of a single type of nucleotide, the transport efficiency differs with the length and nucleotide composition of the ODNs and varies in different types of leukaemia cells; among the 5 tested random sequence ODNs and 3 aptamers with varying sequences, the data showed that some sequences were associated with significantly higher transport efficiency than others. The transport of ODNs was sodium, energy, and pH-independent, membrane protein-dependent, substrate nonspecific for ODNs and 4-nitrobenzylthioinosine (NBMPR)-insensitive, but it showed a low sensitivity to dipyridamole (IC50 = 35.44 µmol/L), distinguishing it from ENT1-4 and CNTs. The delivery efficiency of ODNs was superior to that of Lipofection and Nucleofection, demonstrating its potential applications in research or therapeutics. Moreover, this process was associated with p38 mitogen activated protein kinase (p38MAPK) instead of c-Jun N-terminal kinase (JNK) signalling pathways. We have denoted ODN transmembrane transport as equilibrative nucleic acid transport (ENAT). Overall, these findings indicate a new approach and mechanism for transmembrane transport of ODNs.
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29
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Rahman MF, Askwith C, Govindarajan R. Molecular determinants of acidic pH-dependent transport of human equilibrative nucleoside transporter 3. J Biol Chem 2017; 292:14775-14785. [PMID: 28729424 DOI: 10.1074/jbc.m117.787952] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/11/2017] [Indexed: 12/16/2022] Open
Abstract
Equilibrative nucleoside transporters (ENTs) translocate hydrophilic nucleosides across cellular membranes and are essential for salvage nucleotide synthesis and purinergic signaling. Unlike the prototypic human ENT members hENT1 and hENT2, which mediate plasma membrane nucleoside transport at pH 7.4, hENT3 is an acidic pH-activated lysosomal transporter partially localized to mitochondria. Recent studies demonstrate that hENT3 is indispensable for lysosomal homeostasis, and that mutations in hENT3 can result in a spectrum of lysosomal storage-like disorders. However, despite hENT3's prominent role in lysosome pathophysiology, the molecular basis of hENT3-mediated transport is unknown. Therefore, we sought to examine the mechanistic basis of acidic pH-driven hENT3 nucleoside transport with site-directed mutagenesis, homology modeling, and [3H]adenosine flux measurements in mutant RNA-injected Xenopus oocytes. Scanning mutagenesis of putative residues responsible for pH-dependent transport via hENT3 revealed that the ionization states of Asp-219 and Glu-447, and not His, strongly determined the pH-dependent transport permissible-impermissible states of the transporter. Except for substitution with certain isosteric and polar residues, substitution of either Asp-219 or Glu-447 with any other residues resulted in robust activity that was pH-independent. Dual substitution of Asp-219 and Glu-447 to Ala sustained pH-independent activity over a broad range of physiological pH (pH 5.5-7.4), which also maintained stringent substrate selectivity toward endogenous nucleosides and clinically used nucleoside drugs. Our results suggest a putative pH-sensing role for Asp-219 and Glu-447 in hENT3 and that the size, ionization state, or electronegative polarity at these positions is crucial for obligate acidic pH-dependent activity.
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Affiliation(s)
- Md Fazlur Rahman
- From the Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy
| | | | - Rajgopal Govindarajan
- From the Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, .,the Translational Therapeutics Program, Ohio State University Comprehensive Cancer Center, Ohio State University, Columbus, Ohio 43210
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30
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Huang W, Zeng X, Shi Y, Liu M. Functional characterization of human equilibrative nucleoside transporter 1. Protein Cell 2017; 8:284-295. [PMID: 27995448 PMCID: PMC5359181 DOI: 10.1007/s13238-016-0350-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/04/2016] [Indexed: 12/15/2022] Open
Abstract
Equilibrative nucleoside transporters (ENTs), which facilitate cross-membrane transport of nucleosides and nucleoside-derived drugs, play an important role in the salvage pathways of nucleotide synthesis, cancer chemotherapy, and treatment for virus infections. Functional characterization of ENTs at the molecular level remains technically challenging and hence scant. In this study, we report successful purification and biochemical characterization of human equilibrative nucleoside transporter 1 (hENT1) in vitro. The HEK293F-derived, recombinant hENT1 is homogenous and functionally active in proteoliposome-based counter flow assays. hENT1 transports the substrate adenosine with a Km of 215 ± 34 µmol/L and a Vmax of 578 ± 23.4 nmol mg-1 min-1. Adenosine uptake by hENT1 is competitively inhibited by nitrobenzylmercaptopurine ribonucleoside (NBMPR), nucleosides, deoxynucleosides, and nucleoside-derived anti-cancer and anti-viral drugs. Binding of hENT1 to adenosine, deoxyadenosine, and adenine by isothermal titration calorimetry is in general agreement with results of the competitive inhibition assays. These results validate hENT1 as a bona fide target for potential drug target and serve as a useful basis for future biophysical and structural studies.
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Affiliation(s)
- Weiyun Huang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Xin Zeng
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Minhao Liu
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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31
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Boswell-Casteel RC, Hays FA. Equilibrative nucleoside transporters-A review. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2016; 36:7-30. [PMID: 27759477 DOI: 10.1080/15257770.2016.1210805] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Equilibrative nucleoside transporters (ENTs) are polytopic integral membrane proteins that mediate the transport of nucleosides, nucleobases, and therapeutic analogs. The best-characterized ENTs are the human transporters hENT1 and hENT2. However, non-mammalian eukaryotic ENTs have also been studied (e.g., yeast, parasitic protozoa). ENTs are major pharmaceutical targets responsible for modulating the efficacy of more than 30 approved drugs. However, the molecular mechanisms and chemical determinants of ENT-mediated substrate recognition, binding, inhibition, and transport are poorly understood. This review highlights findings on the characterization of ENTs by surveying studies on genetics, permeant and inhibitor interactions, mutagenesis, and structural models of ENT function.
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Affiliation(s)
- Rebba C Boswell-Casteel
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Franklin A Hays
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA.,b Stephenson Cancer Center , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA.,c Harold Hamm Diabetes Center , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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32
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Qi H, Lu J, Li J, Wang M, Xu Y, Wang Y, Zhang H. Enhanced Antitumor Activity of Monophosphate Ester Prodrugs of Gemcitabine: In Vitro and In Vivo Evaluation. J Pharm Sci 2016; 105:2966-2973. [DOI: 10.1016/j.xphs.2016.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 12/11/2022]
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33
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Damaraju VL, Weber D, Kuzma M, Cass CE, Sawyer MB. Selective Inhibition of Human Equilibrative and Concentrative Nucleoside Transporters by BCR-ABL Kinase Inhibitors: IDENTIFICATION OF KEY hENT1 AMINO ACID RESIDUES FOR INTERACTION WITH BCR-ABL KINASE INHIBITORS. J Biol Chem 2016; 291:18809-17. [PMID: 27432881 DOI: 10.1074/jbc.m116.741074] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Indexed: 01/10/2023] Open
Abstract
Human nucleoside transporters (hNTs) mediate cellular influx of anticancer nucleoside drugs, including cytarabine, cladribine, and fludarabine. BCR-ABL tyrosine kinase inhibitors (TKIs) imatinib and dasatinib inhibit fludarabine and cytarabine uptake. We assessed interactions of bosutinib, dasatinib, imatinib, nilotinib, and ponatinib with recombinant hNTs (hENT1, 2; hCNT1, -2, and -3) produced individually in yeast Saccharomyces cerevisiae Nilotinib inhibited hENT1-mediated uridine transport most potently (IC50 value, 0.7 μm) followed by ponatinib > bosutinib > dasatinib > imatinib. Imatinib inhibited hCNT2 with an IC50 value of 2.3 μm Ponatinib inhibited all five hNTs with the greatest effect seen for hENT1 (IC50 value, 9 μm). TKIs inhibited [(3)H]uridine uptake in a competitive manner. Studies in yeast with mutants at two amino acid residues of hENT1 (L442I, L442T, M33A, M33A/L442I) previously shown to be involved in uridine and dipyridamole binding, suggested that BCR-ABL TKIs interacted with Met(33) (TM1) and Leu(442) (TM11) residues of hENT1. In cultured human CEM lymphoblastoid cells, which possess a single hNT type (hENT1), accumulation of [(3)H]cytarabine, [(3)H]cladribine, or [(3)H]fludarabine was reduced by each of the five TKIs, and also caused a reduction in cell surface expression of hENT1 protein. In conclusion, BCR-ABL TKIs variously inhibit five different hNTs, cause a decrease in cell surface hENT1 expression, and decrease uridine accumulation when presented together with uridine or when given before uridine. In experiments with mutant hENT1, we showed for the first time interaction of Met(33) (involved in dipyridamole binding) with BCR-ABL inhibitors and reduced interaction with M33A mutant hENT1.
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Affiliation(s)
- Vijaya L Damaraju
- From the Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada
| | - Dwayne Weber
- From the Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada
| | - Michelle Kuzma
- From the Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada
| | - Carol E Cass
- From the Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada
| | - Michael B Sawyer
- From the Department of Oncology, University of Alberta and Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada
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34
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Nguyen MD, Ross AE, Ryals M, Lee ST, Venton BJ. Clearance of rapid adenosine release is regulated by nucleoside transporters and metabolism. Pharmacol Res Perspect 2015; 3:e00189. [PMID: 27022463 PMCID: PMC4777247 DOI: 10.1002/prp2.189] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 08/24/2015] [Indexed: 12/30/2022] Open
Abstract
Adenosine is a neuromodulator that regulates neurotransmission in the brain and central nervous system. Recently, spontaneous adenosine release that is cleared in 3-4 sec was discovered in mouse spinal cord slices and anesthetized rat brains. Here, we examined the clearance of spontaneous adenosine in the rat caudate-putamen and exogenously applied adenosine in caudate brain slices. The V max for clearance of exogenously applied adenosine in brain slices was 1.4 ± 0.1 μmol/L/sec. In vivo, the equilibrative nucleoside transport 1 (ENT1) inhibitor, S-(4-nitrobenzyl)-6-thioinosine (NBTI) (1 mg/kg, i.p.) significantly increased the duration of adenosine, while the ENT1/2 inhibitor, dipyridamole (10 mg/kg, i.p.), did not affect duration. 5-(3-Bromophenyl)-7-[6-(4-morpholinyl)-3-pyrido[2,3-d]byrimidin-4-amine dihydrochloride (ABT-702), an adenosine kinase inhibitor (5 mg/kg, i.p.), increased the duration of spontaneous adenosine release. The adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) (10 mg/kg, i.p.), also increased the duration in vivo. Similarly, NBTI (10 μmol/L), ABT-702 (100 nmol/L), or EHNA (20 μmol/L) also decreased the clearance rate of exogenously applied adenosine in brain slices. The increases in duration for blocking ENT1, adenosine kinase, or adenosine deaminase individually were similar, about 0.4 sec in vivo; thus, the removal of adenosine on a rapid time scale occurs through three mechanisms that have comparable effects. A cocktail of ABT-702, NBTI, and EHNA significantly increased the duration by 0.7 sec, so the mechanisms are not additive and there may be additional mechanisms clearing adenosine on a rapid time scale. The presence of multiple mechanisms for adenosine clearance on a time scale of seconds demonstrates that adenosine is tightly regulated in the extracellular space.
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Affiliation(s)
- Michael D Nguyen
- Department of Chemistry University of Virginia Charlottesville Virginia
| | - Ashley E Ross
- Department of Chemistry University of Virginia Charlottesville Virginia
| | - Matthew Ryals
- Department of Chemistry University of Virginia Charlottesville Virginia
| | - Scott T Lee
- Department of Chemistry University of Virginia Charlottesville Virginia
| | - B Jill Venton
- Department of Chemistry University of Virginia Charlottesville Virginia
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35
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Beno BR, Yeung KS, Bartberger MD, Pennington LD, Meanwell NA. A Survey of the Role of Noncovalent Sulfur Interactions in Drug Design. J Med Chem 2015; 58:4383-438. [DOI: 10.1021/jm501853m] [Citation(s) in RCA: 468] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Brett R. Beno
- Department of Computer-Assisted Drug Design, Bristol-Myers Squibb Research and Development, 5 Research Parkway Wallingford Connecticut 06492, United States
| | - Kap-Sun Yeung
- Department of Discovery Chemistry, Bristol-Myers Squibb Research and Development, 5 Research Parkway Wallingford Connecticut 06492, United States
| | - Michael D. Bartberger
- Department of Therapeutic Discovery, Amgen Inc., One Amgen Center Drive Thousand Oaks California 91320, United States
| | - Lewis D. Pennington
- Department of Therapeutic Discovery, Amgen Inc., One Amgen Center Drive Thousand Oaks California 91320, United States
| | - Nicholas A. Meanwell
- Department of Discovery Chemistry, Bristol-Myers Squibb Research and Development, 5 Research Parkway Wallingford Connecticut 06492, United States
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36
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Pastor-Anglada M, Pérez-Torras S. Nucleoside transporter proteins as biomarkers of drug responsiveness and drug targets. Front Pharmacol 2015; 6:13. [PMID: 25713533 PMCID: PMC4322540 DOI: 10.3389/fphar.2015.00013] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/13/2015] [Indexed: 12/13/2022] Open
Abstract
Nucleoside and nucleobase analogs are currently used in the treatment of solid tumors, lymphoproliferative diseases, viral infections such as hepatitis and AIDS, and some inflammatory diseases such as Crohn. Two gene families are implicated in the uptake of nucleosides and nucleoside analogs into cells, SCL28 and SLC29. The former encodes hCNT1, hCNT2, and hCNT3 proteins. They translocate nucleosides in a Na+ coupled manner with high affinity and some substrate selectivity, being hCNT1 and hCNT2 pyrimidine- and purine-preferring, respectively, and hCNT3 a broad selectivity transporter. SLC29 genes encode four members, being hENT1 and hENT2 the only two which are unequivocally implicated in the translocation of nucleosides and nucleobases (the latter mostly via hENT2) at the cell plasma membrane. Some nucleoside-derived drugs can also interact with and be translocated by members of the SLC22 gene family, particularly hOCT and hOAT proteins. Inter-individual differences in transporter function and perhaps, more importantly, altered expression associated with the disease itself might modulate the transporter profile of target cells, thereby determining drug bioavailability and action. Drug transporter pharmacology has been periodically reviewed. Thus, with this contribution we aim at providing a state-of-the-art overview of the clinical evidence generated so far supporting the concept that these membrane proteins can indeed be biomarkers suitable for diagnosis and/or prognosis. Last but not least, some of these transporter proteins can also be envisaged as drug targets, as long as they can show “transceptor” functions, in some cases related to their role as modulators of extracellular adenosine levels, thereby providing a functional link between P1 receptors and transporters.
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Affiliation(s)
- Marçal Pastor-Anglada
- Molecular Pharmacology and Experimental Therapeutics, Department of Biochemistry and Molecular Biology, Institute of Biomedicine, University of Barcelona, Barcelona Spain ; Oncology Program, CIBER ehd, National Biomedical Research Institute on Liver and Gastrointestinal Diseases, Instituto de Salud Carlos III, Barcelona Spain
| | - Sandra Pérez-Torras
- Molecular Pharmacology and Experimental Therapeutics, Department of Biochemistry and Molecular Biology, Institute of Biomedicine, University of Barcelona, Barcelona Spain ; Oncology Program, CIBER ehd, National Biomedical Research Institute on Liver and Gastrointestinal Diseases, Instituto de Salud Carlos III, Barcelona Spain
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37
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Damaraju VL, Kuzma M, Mowles D, Cass CE, Sawyer MB. Interactions of Multitargeted Kinase Inhibitors and Nucleoside Drugs: Achilles Heel of Combination Therapy? Mol Cancer Ther 2014; 14:236-45. [DOI: 10.1158/1535-7163.mct-14-0337] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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38
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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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39
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Ceschin J, Saint-Marc C, Laporte J, Labriet A, Philippe C, Moenner M, Daignan-Fornier B, Pinson B. Identification of yeast and human 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAr) transporters. J Biol Chem 2014; 289:16844-54. [PMID: 24778186 DOI: 10.1074/jbc.m114.551192] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAr) is the precursor of the active monophosphate form (AICAR), a small molecule with potent anti-proliferative and low energy mimetic properties. The molecular bases for AICAR toxicity at the cellular level are poorly understood. Here, we report the isolation and characterization of several yeast AICAr-hypersensitive mutants. Identification of the cognate genes allowed us to establish that thiamine transporters Thi7 and Thi72 can efficiently take up AICAr under conditions where they are overexpressed. We establish that, under standard growth conditions, Nrt1, the nicotinamide riboside carrier, is the major AICAr transporter in yeast. A study of AICAR accumulation in human cells revealed substantial disparities among cell lines and confirmed that AICAr enters cells via purine nucleoside transporters. Together, our results point to significant differences between yeast and human cells for both AICAr uptake and AICAR accumulation.
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Affiliation(s)
- Johanna Ceschin
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Christelle Saint-Marc
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Jean Laporte
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Adrien Labriet
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Chloé Philippe
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Michel Moenner
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Bertrand Daignan-Fornier
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
| | - Benoît Pinson
- From the Université de Bordeaux IBGC UMR 5095 1, F-33077 Bordeaux, France and the Centre National de la Recherche Scientifique IBGC UMR 5095 1, F-33077 Bordeaux, France
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40
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Wang C, Lin W, Playa H, Sun S, Cameron K, Buolamwini J. Dipyridamole analogs as pharmacological inhibitors of equilibrative nucleoside transporters. Identification of novel potent and selective inhibitors of the adenosine transporter function of human equilibrative nucleoside transporter 4 (hENT4). Biochem Pharmacol 2013; 86:1531-40. [PMID: 24021350 PMCID: PMC3866046 DOI: 10.1016/j.bcp.2013.08.063] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 08/27/2013] [Accepted: 08/27/2013] [Indexed: 01/04/2023]
Abstract
To identify needed human equilibrative nucleoside transporter 4 (hENT4) inhibitors, we cloned and stably expressed the recombinant protein in PK15NTD (nucleoside transporter deficient) cells, and, investigated its interaction with a series of dipyridamole analogs synthesized in our laboratory. Compounds were tested in this newly established hENT4 expressing system as well in previous stably expressed hENT1 and hENT2 expressing systems. Of the dipyridamole analogs evaluated, about one fourth of the compounds inhibited hENT4 with higher potencies than dipyridamole. The most potent of them, Compound 30 displayed an IC₅₀ of 74.4 nM, making it about 38 times more potent than dipyridamole (IC₅₀=2.8 μM), and selectivities of about 80-fold and 20-fold relative to ENT1 and ENT2, respectively. Structure-activity relationship showed nitrogen-containing monocyclic rings and noncyclic substituents at the 4- and 8-positions of the pyrimido[5,4-d]pyrimidine were important for the inhibitory activity against hENT4. The most potent and selective hENT4 inhibitors tended to have a 2,6-di(N-monohydroxyethyl) substitution on the pyrimidopyrimidine ring system. The inhibitors of hENT4 identified in this study are the most selective and potent inhibitors of hENT4 adenosine transporter function to date, and should serve as useful pharmacological/biochemical tools and/or potential leads for ENT4-based therapeutics. Also, the new hENT4-expressing PK15 cell line established will serve as a useful screening tool for the discovery and design of hENT4 ligands.
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Affiliation(s)
- Chunmei Wang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | | | - Hilaire Playa
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | - Shan Sun
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | - Kenyuna Cameron
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
| | - John Buolamwini
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Damaraju VL, Scriver T, Mowles D, Kuzma M, Ryan AJ, Cass CE, Sawyer MB. Erlotinib, gefitinib, and vandetanib inhibit human nucleoside transporters and protect cancer cells from gemcitabine cytotoxicity. Clin Cancer Res 2013; 20:176-86. [PMID: 24170548 DOI: 10.1158/1078-0432.ccr-13-2293] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Combinations of tyrosine kinase inhibitors (TKI) with gemcitabine have been attempted with little added benefit to patients. We hypothesized that TKIs designed to bind to ATP-binding pockets of growth factor receptors also bind to transporter proteins that recognize nucleosides. EXPERIMENTAL DESIGN TKI inhibition of uridine transport was studied with recombinant human (h) equilibrative (E) and concentrative (C) nucleoside transporters (hENT, hCNT) produced individually in yeast. TKIs effects on uridine transport, gemcitabine accumulation, regulation of hENT1 activity, and cell viability in the presence or absence of gemcitabine were evaluated in human pancreatic and lung cancer cell lines. RESULTS Erlotinib, gefitinib and vandetanib inhibited [(3)H]uridine transport in yeast and [(3)H]uridine and [(3)H]gemcitabine uptake in the four cell lines. Treatment of cell lines with erlotinib, gefitinib, or vandetanib for 24 hours reduced hENT1 activity which was reversed by subsequent incubation in drug-free media for 24 hours. Greater cytotoxicity was observed when gemcitabine was administered before erlotinib, gefitinib, or vandetanib than when administered together and synergy, evaluated using the CalcuSyn Software, was observed in three cell lines resulting in combination indices under 0.6 at 50% reduction of cell growth. CONCLUSIONS Vandetanib inhibited hENT1, hENT2, hCNT1, hCNT2, and hCNT3, whereas erlotinib inhibited hENT1 and hCNT3 and gefitinib inhibited hENT1 and hCNT1. The potential for reduced accumulation of nucleoside chemotherapy drugs in tumor tissues due to inhibition of hENTs and/or hCNTs by TKIs indicates that pharmacokinetic properties of these agents must be considered when scheduling TKIs and nucleoside chemotherapy in combination.
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Affiliation(s)
- Vijaya L Damaraju
- Authors' Affiliations: Department of Oncology, University of Alberta; Department of Medical Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada; and Department of Oncology, University of Oxford, Oxford, United Kingdom
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42
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Begandt D, Bader A, Dreyer L, Eisert N, Reeck T, Ngezahayo A. Biphasic increase of gap junction coupling induced by dipyridamole in the rat aortic A-10 vascular smooth muscle cell line. J Cell Commun Signal 2013; 7:151-60. [PMID: 23483357 DOI: 10.1007/s12079-013-0196-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 02/18/2013] [Indexed: 12/11/2022] Open
Abstract
The rat aortic smooth muscle cell line A-10 was used to investigate the effect of dipyridamole on the gap junction coupling of smooth muscle cells. The scrape loading/dye transfer (SL/DT) technique revealed that dipyridamole concentrations between 5 μM and 100 μM significantly increased gap junction coupling. The adenosine receptor antagonist MRS 1754, as well as the PKA inhibitors Rp-cAMPS and H-89 were able to inhibit the dipyridamole-related increase in coupling, while forskolin and Br-cAMP also induced an enhancement of the gap junction coupling. Regarding the time-dependent behaviour of dipyridamole, a short-term effect characterised by an oscillatory reaction was observed for application times of less than 5 h, while applications times of at least 6 h resulted in a long-term effect, characterised by a constant increase of gap junction coupling to its maximum levels. This increase was not altered by prolonged presence of dipyridamole. In parallel, a short application of dipyridamole for at least 15 min was found to be sufficient to evoke the long-term effect measured 6 h after drug washout. We propose that in both the short-term and long-term effect, cAMP-related pathways are activated. The short-term phase could be related to an oscillatory cAMP effect, which might directly affect connexin trafficking, assembly and/or gap junction gating. The long-term effect is most likely related to the new expression and synthesis of connexins. With previous data from a bovine aortic endothelial cell line, the present results show that gap junction coupling of vascular cells is a target for dipyridamole.
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Affiliation(s)
- Daniela Begandt
- Institute of Biophysics, Leibniz University Hannover, Herrenhäuserstr. 2, 30419, Hannover, Germany
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43
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Lu Q, Sakhatskyy P, Newton J, Shamirian P, Hsiao V, Curren S, Gabino Miranda GA, Pedroza M, Blackburn MR, Rounds S. Sustained adenosine exposure causes lung endothelial apoptosis: a possible contributor to cigarette smoke-induced endothelial apoptosis and lung injury. Am J Physiol Lung Cell Mol Physiol 2013; 304:L361-70. [PMID: 23316066 DOI: 10.1152/ajplung.00161.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Pulmonary endothelial cell (EC) apoptosis has been implicated in the pathogenesis of emphysema. Cigarette smoke (CS) causes lung EC apoptosis and emphysema. In this study, we show that CS exposure increased lung tissue adenosine levels in mice, an effect associated with increased lung EC apoptosis and the development of emphysema. Adenosine has a protective effect against apoptosis via adenosine receptor-mediated signaling. However, sustained elevated adenosine increases alveolar cell apoptosis in adenosine deaminase-deficient mice. We established an in vitro model of sustained adenosine exposure by incubating lung EC with adenosine in the presence of an adenosine deaminase inhibitor, deoxycoformicin. We demonstrated that sustained adenosine exposure caused lung EC apoptosis via nucleoside transporter-facilitated intracellular adenosine uptake, subsequent activation of p38 and JNK in mitochondria, and ultimately mitochondrial defects and activation of the mitochondria-mediated intrinsic pathway of apoptosis. Our results suggest that sustained elevated adenosine may contribute to CS-induced lung EC apoptosis and emphysema. Our data also reconcile the paradoxical effects of adenosine on apoptosis, demonstrating that prolonged exposure causes apoptosis via nucleoside transporter-mediated intracellular adenosine signaling, whereas acute exposure protects against apoptosis via activation of adenosine receptors. Inhibition of adenosine uptake may become a new therapeutic target in treatment of CS-induced lung diseases.
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Affiliation(s)
- Qing Lu
- Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Department of Medicine, Alpert Medical School of Brown University, Providence, RI 02908, USA.
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Valdés R, Shinde U, Landfear SM. Cysteine cross-linking defines the extracellular gate for the Leishmania donovani nucleoside transporter 1.1 (LdNT1.1). J Biol Chem 2012; 287:44036-45. [PMID: 23150661 DOI: 10.1074/jbc.m112.414433] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Equilibrative nucleoside transporters are a unique family of proteins that enable uptake of nucleosides/nucleobases into a wide range of eukaryotes and internalize a myriad of drugs used in the treatment of cancer, heart disease, AIDs, and parasitic infections. In previous work we generated a structural model for such a transporter, the LdNT1.1 nucleoside permease from the parasitic protozoan Leishmania donovani, using ab initio computation. The model suggested that aromatic residues present in transmembrane helices 1, 2, and 7 interact to form an extracellular gate that closes the permeation pathway in the inward-open conformation. Mutation of residues Phe-48(TM1) and Trp-75(TM2) abrogated transport activity, consistent with such prediction. In this study cysteine mutagenesis and oxidative cross-linking were combined to analyze proximity relationships of helices 1, 2, and 7 in LdNT1.1. Disulfide bond formation between introduced paired cysteines at the interface of such helices (A61C(TM1)/F74C(TM2), A61C(TM1)/G350C(TM7), and F74C(TM2)/G350C(TM7)) was analyzed by transport measurement and gel mobility shifts upon oxidation with Cu (II)-(1,10-phenanthroline)(3). In all cases cross-linking inhibited transport. However, if LdNT1.1 ligands were included during cross-linking, inhibition of transport was reduced, suggesting that ligands moved the three gating helices apart. Moreover, all paired cysteine mutants exhibited a mobility shift upon oxidation, corroborating the formation of a disulfide bond. These data support the notion that helices 1, 2, and 7 constitute the extracellular gate of LdNT1.1, thus further validating the computational model and the previously demonstrated importance of F48(TM1) and Trp-75(TM2) in tethering together helices that are part of the gate.
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Affiliation(s)
- Raquel Valdés
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, Oregon 97239, USA
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45
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Brito R, Pereira MR, Paes-de-Carvalho R, Calaza KDC. Expression of A1 adenosine receptors in the developing avian retina: in vivo modulation by A(2A) receptors and endogenous adenosine. J Neurochem 2012; 123:239-49. [PMID: 22862679 DOI: 10.1111/j.1471-4159.2012.07909.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 07/30/2012] [Accepted: 08/01/2012] [Indexed: 12/13/2022]
Abstract
Little is known about the mechanisms that regulate the expression of adenosine receptors during CNS development. We demonstrate here that retinas from chick embryos injected in ovo with selective adenosine receptor ligands show changes in A1 receptor expression after 48 h. Exposure to A1 agonist N⁶-cyclohexyladenosine (CHA) or antagonist 8-Cyclopentyl-1, 3-dipropylxanthine (DPCPX) reduced or increased, respectively, A1 receptor protein and [³H]DPCPX binding, but together, CHA+DPCPX had no effect. Interestingly, treatment with A(2A) agonist 3-[4-[2-[[6-amino-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxy-oxolan-2-yl]purin-2-yl]amino] ethyl]phenyl] propanoic acid (CGS21680) increased A1 receptor protein and [³H]DPCPX binding, and reduced A(2A) receptors. The A(2A) antagonists 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-trizolo[1,5-c] pyrimidine (SCH58261) and 4-(2-[7-amino-2-[2-furyl][1,2,4]triazolo[2,3-a][1,3,5]triazo-5-yl-amino]ethyl)phenol (ZM241385) had opposite effects on A1 receptor expression. Exposure to CGS21680 + CHA did not change A1 receptor levels, whereas CHA + ZM241385 or CGS21680 + DPCPX had no synergic effect. The blockade of adenosine transporter with S-(4-nitrobenzyl)-6-thioinosine (NBMPR) also reduced [³H]DPCPX binding, an effect blocked by DPCPX, but not enhanced by ZM241385. [³H]DPCPX binding kinetics showed that treatment with CHA reduced and CGS21680 increased the Bmax, but did not affect Kd values. CHA, DPCPX, CGS21680, and ZM241385 had no effect on A1 receptor mRNA. These data demonstrated an in vivo regulation of A1 receptor expression by endogenous adenosine or long-term treatment with A1 and A(2A) receptors modulators.
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Affiliation(s)
- Rafael Brito
- Neurobiology of the Retina Laboratory, Department of Neurobiology and Program of Neurosciences, Institute of Biology, Fluminense Federal University, Niteroi, RJ, Brazil
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46
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Lu Q, Newton J, Hsiao V, Shamirian P, Blackburn MR, Pedroza M. Sustained adenosine exposure causes lung endothelial barrier dysfunction via nucleoside transporter-mediated signaling. Am J Respir Cell Mol Biol 2012; 47:604-13. [PMID: 22744860 DOI: 10.1165/rcmb.2012-0012oc] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Previous studies by our group as well as others have shown that acute adenosine exposure enhances lung vascular endothelial barrier integrity and protects against increased permeability lung edema. In contrast, there is growing evidence that sustained adenosine exposure has detrimental effects on the lungs, including lung edema. It is well established that adenosine modulates lung inflammation. However, little is known concerning the effect of sustained adenosine exposure on lung endothelial cells (ECs), which are critical to the maintenance of the alveolar-capillary barrier. We show that exogenous adenosine plus adenosine deaminase inhibitor caused sustained elevation of adenosine in lung ECs. This sustained adenosine exposure decreased EC barrier function, elevated cellular reactive oxygen species levels, and activated p38, JNK, and RhoA. Inhibition of equilibrative nucleoside transporters (ENTs) prevented sustained adenosine-induced p38 and JNK activation and EC barrier dysfunction. Inhibition of p38, JNK, or RhoA also partially attenuated sustained adenosine-induced EC barrier dysfunction. These data indicate that sustained adenosine exposure causes lung EC barrier dysfunction via ENT-dependent intracellular adenosine uptake and subsequent activation of p38, JNK, and RhoA. The antioxidant N-acetylcysteine and the NADPH inhibitor partially blunted sustained adenosine-induced JNK activation but were ineffective in attenuation of p38 activation or barrier dysfunction. p38 was activated exclusively in mitochondria, whereas JNK was activated in mitochondria and cytoplasm by sustained adenosine exposure. Our data further suggest that sustained adenosine exposure may cause mitochondrial oxidative stress, leading to activation of p38, JNK, and RhoA in mitochondria and resulting in EC barrier dysfunction.
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Affiliation(s)
- Qing Lu
- Alpert Medical School of Brown University, Providence VA Medical Center, Research Services, 830 Chalkstone Avenue, Providence, RI 02908, USA.
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47
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Damaraju VL, Mowles D, Yao S, Ng A, Young JD, Cass CE, Tong Z. Role of human nucleoside transporters in the uptake and cytotoxicity of azacitidine and decitabine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2012; 31:236-55. [PMID: 22356238 DOI: 10.1080/15257770.2011.652330] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The nucleoside analogs 5-azacytidine (azacitidine) and 5-aza-2'-deoxycytidine (decitabine) are active against acute myeloid leukemia and myelodysplastic syndromes. Cellular transport across membranes is crucial for uptake of these highly polar hydrophilic molecules. We assessed the ability of azacitidine, decitabine, and, for comparison, gemcitabine, to interact with human nucleoside transporters (hNTs) in Saccharomyces cerevisiae cells (hENT1/2, hCNT1/2/3) or Xenopus laevis oocytes (hENT3/4). All three drugs inhibited hCNT1/3 potently (K (i) values, 3-26 μM), hENT1/2 and hCNT2 weakly (K (i) values, 0.5-3.1 mM), and hENT3/4 poorly if at all. Rates of transport of [(3)H]gemcitabine, [(14)C]azacitidine, and [(3)H]decitabine observed in Xenopus oocytes expressing individual recombinant hNTs differed substantially. Cytotoxicity of azacitidine and decitabine was assessed in hNT-expressing or hNT-deficient cultured human cell lines in the absence or presence of transport inhibitors where available. The rank order of cytotoxic sensitivities (IC (50) values, μM) conferred by hNTs were hCNT1 (0.1) > hENT1 (0.3) ≫ hCNT2 (8.3), hENT2 (9.0) for azacitidine and hENT1 (0.3) > hCNT1 (0.8) ⋙ hENT2, hCNT2 (>100) for decitabine. Protection against cytotoxicity was observed for both drugs in the presence of inhibitors of nucleoside transport, thus suggesting the importance of hNTs in manifestation of toxicity. In summary, all seven hNTs transported azacitidine, with hCNT3 showing the highest rates, whereas hENT1 and hENT2 showed modest transport and hCNT1 and hCNT3 poor transport of decitabine. Our results show for the first time that azacitidine and decitabine exhibit different human nucleoside transportability profiles and their cytotoxicities are dependent on the presence of hNTs, which could serve as potential biomarkers of clinical response.
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Affiliation(s)
- Vijaya L Damaraju
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
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48
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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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49
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Damaraju VL, Mowles D, Smith KM, Yao SYM, Young JD, Marquez VE, Cass CE. Influence of Sugar Ring Conformation on the Transportability of Nucleosides by Human Nucleoside Transporters. Chembiochem 2011; 12:2774-8. [DOI: 10.1002/cbic.201100567] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Indexed: 11/09/2022]
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50
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Cano-Soldado P, Pastor-Anglada M. Transporters that translocate nucleosides and structural similar drugs: structural requirements for substrate recognition. Med Res Rev 2011; 32:428-57. [DOI: 10.1002/med.20221] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Pedro Cano-Soldado
- Departament de Bioquímica i Biologia Molecular; Institut de Biomedicina de la Universitat de Barcelona (IBUB); Universitat de Barcelona and CIBER EHD; Barcelona Spain
| | - Marçal Pastor-Anglada
- Departament de Bioquímica i Biologia Molecular; Institut de Biomedicina de la Universitat de Barcelona (IBUB); Universitat de Barcelona and CIBER EHD; Barcelona Spain
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