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Puris E, Fricker G, Gynther M. The Role of Solute Carrier Transporters in Efficient Anticancer Drug Delivery and Therapy. Pharmaceutics 2023; 15:pharmaceutics15020364. [PMID: 36839686 PMCID: PMC9966068 DOI: 10.3390/pharmaceutics15020364] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/15/2023] [Accepted: 01/18/2023] [Indexed: 01/24/2023] Open
Abstract
Transporter-mediated drug resistance is a major obstacle in anticancer drug delivery and a key reason for cancer drug therapy failure. Membrane solute carrier (SLC) transporters play a crucial role in the cellular uptake of drugs. The expression and function of the SLC transporters can be down-regulated in cancer cells, which limits the uptake of drugs into the tumor cells, resulting in the inefficiency of the drug therapy. In this review, we summarize the current understanding of low-SLC-transporter-expression-mediated drug resistance in different types of cancers. Recent advances in SLC-transporter-targeting strategies include the development of transporter-utilizing prodrugs and nanocarriers and the modulation of SLC transporter expression in cancer cells. These strategies will play an important role in the future development of anticancer drug therapies by enabling the efficient delivery of drugs into cancer cells.
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2
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Vaskó B, Juhász V, Tóth B, Kurunczi A, Fekete Z, Krisjanis Zolnerciks J, Kis E, Magnan R, Bidon-Chanal Badia A, Pastor-Anglada M, Hazai E, Bikadi Z, Fülöp F, Krajcsi P. Inhibitor selectivity of CNTs and ENTs. Xenobiotica 2018; 49:840-851. [PMID: 30022699 DOI: 10.1080/00498254.2018.1501832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The concentrative nucleoside transporters (CNT; solute carrier family 28 (SLC28)) and the equilibrative nucleoside transporters (ENT; solute carrier family 29 (SLC29)) are important therapeutic targets but may also mediate toxicity or adverse events. To explore the relative role of the base and the monosaccharide moiety in inhibitor selectivity we selected compounds that either harbor an arabinose moiety or a cytosine moiety, as these groups had several commercially available drug members. The screening data showed that more compounds harboring a cytosine moiety displayed potent interactions with the CNTs than compounds harboring the arabinose moiety. In contrast, ENTs showed a preference for compounds with an arabinose moiety. The correlation between CNT1 and CNT3 was good as five of six compounds displayed IC50 values within the threefold threshold and one displayed a borderline 4-fold difference. For CNT1 and CNT2 as well as for CNT2 and CNT3 only two of six IC50 values correlated and one displayed a borderline 4-fold difference. Interestingly, of the six compounds that potently interacted with both ENT1 and ENT2 only nelarabine displayed selectivity. Our data show differences between inhibitor selectivities of CNTs and ENTs as well as differences within the CNT family members.
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Affiliation(s)
| | | | - Beáta Tóth
- b SOLVO Biotechnology , Budaörs , Hungary
| | | | | | | | - Emese Kis
- a SOLVO Biotechnology , Szeged , Hungary
| | | | - Axel Bidon-Chanal Badia
- c Departament de Nutrició, Ciències de l'Alimentació i Gastronomia, Facultat de Farmàcia i Ciències de l'Alimentació and Institute of Biomedicine (IBUB), Campus de l'Alimentació de Torribera , Universitat de Barcelona , Santa Coloma de Gramenet , Spain
| | - Marçal Pastor-Anglada
- d Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia and Institute of Biomedicine (IBUB) , Universitat de Barcelona , Barcelona , Spain.,e Oncology Program , National Biomedical Research Institute on Liver and Gastrointestinal Diseases (CIBER EHD), Instituto de Salud Carlos III , Madrid , Spain
| | | | | | - Ferenc Fülöp
- g Institute of Pharmaceutical Chemistry, University of Szeged , Szeged , Hungary
| | - Peter Krajcsi
- a SOLVO Biotechnology , Szeged , Hungary.,h Department of Morphology and Physiology, Faculty of Health Sciences , Semmelweis University , Budapest , Hungary.,i Faculty of Information Technology and Bionics , Pázmány Péter Catholic University , Budapest , Hungary
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3
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Tatani K, Hiratochi M, Kikuchi N, Kuramochi Y, Watanabe S, Yamauchi Y, Itoh F, Isaji M, Shuto S. Identification of Adenine and Benzimidazole Nucleosides as Potent Human Concentrative Nucleoside Transporter 2 Inhibitors: Potential Treatment for Hyperuricemia and Gout. J Med Chem 2016; 59:3719-31. [DOI: 10.1021/acs.jmedchem.5b01884] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Kazuya Tatani
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Masahiro Hiratochi
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Norihiko Kikuchi
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Yu Kuramochi
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Shinjiro Watanabe
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Yuji Yamauchi
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Fumiaki Itoh
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
| | - Masayuki Isaji
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Hotakakashiwabara, Azumino, Nagano 399-8304, Japan
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4
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Mandíková J, Volková M, Pávek P, Navrátilová L, Hyršová L, Janeba Z, Pavlík J, Bárta P, Trejtnar F. Entecavir Interacts with Influx Transporters hOAT1, hCNT2, hCNT3, but Not with hOCT2: The Potential for Renal Transporter-Mediated Cytotoxicity and Drug-Drug Interactions. Front Pharmacol 2016; 6:304. [PMID: 26779022 PMCID: PMC4700268 DOI: 10.3389/fphar.2015.00304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 12/11/2015] [Indexed: 12/29/2022] Open
Abstract
Entecavir (ETV) is one of the most potent agents for the treatment of the hepatitis B viral infection. The drug is principally eliminated by the kidney. The goal of this study was to investigate the potential of ETV to interact in vitro with the renal SLC transporters hOAT1, hOCT2, hCNT2 and hCNT3. Potential drug–drug interactions of ETV at the renal transporters with antiviral drugs known to be excreted by the kidney (adefovir, tenofovir, cidofovir) as well as transporter-dependent cytotoxicity were also examined. Interactions with the selected transporters along with cytotoxicity were studied in several transiently transfected cellular models using specific substrates and inhibitors. ETV was found to be both a substrate and inhibitor of hOAT1 (IC50 = 175.3 μM), hCNT2 (IC50 = 241.9 μM) and hCNT3 (IC50 = 278.4 μM) transporters, although it interacted with the transporters with relatively low affinities. ETV inhibited the cellular uptake of adefovir, tenofovir, and cidofovir by hOAT1; however, effective inhibition was shown at ETV concentrations exceeding therapeutic levels. In comparison with adefovir, tenofovir, and cidofovir, ETV displayed no transporter-mediated cytotoxicity in cells transfected with hOAT1, hCNT2, and hCNT3. No significant interaction of ETV with hOCT2 was detected. The study demonstrates interactions of ETV with several human renal transporters. For the first time, an interaction of ETV with the hCNTs was proved. We show that the potency of ETV to cause nephrotoxicity and/or clinically significant drug-drug interactions related to the tested transporters is considerably lower than that of adefovir, tenofovir, and cidofovir.
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Affiliation(s)
- Jana Mandíková
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
| | - Marie Volková
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
| | - Petr Pávek
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
| | - Lucie Navrátilová
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
| | - Lucie Hyršová
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
| | - Zlatko Janeba
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic Prague, Czech Republic
| | - Jan Pavlík
- Cayman Pharma Ltd. Neratovice, Czech Republic
| | - Pavel Bárta
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
| | - František Trejtnar
- Department of Pharmacology and Toxicology, Faculty of Pharmacy in Hradec Králové, Charles University in Prague Hradec Králové, Czech Republic
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5
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Tatani K, Hiratochi M, Nonaka Y, Isaji M, Shuto S. Identification of 8-aminoadenosine derivatives as a new class of human concentrative nucleoside transporter 2 inhibitors. ACS Med Chem Lett 2015; 6:244-8. [PMID: 25815140 DOI: 10.1021/ml500343r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Accepted: 01/28/2015] [Indexed: 11/30/2022] Open
Abstract
Purine-rich foods have long been suspected as a major cause of hyperuricemia. We hypothesized that inhibition of human concentrative nucleoside transporter 2 (hCNT2) would suppress increases in serum urate levels derived from dietary purines. To test this hypothesis, the development of potent hCNT2 inhibitors was required. By modifying adenosine, an hCNT2 substrate, we successfully identified 8-aminoadenosine derivatives as a new class of hCNT2 inhibitors. Compound 12 moderately inhibited hCNT2 (IC50 = 52 ± 3.8 μM), and subsequent structure-activity relationship studies led to the discovery of compound 48 (IC50 = 0.64 ± 0.19 μM). Here we describe significant findings about structural requirements of 8-aminoadenosine derivatives for exhibiting potent hCNT2 inhibitory activity.
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Affiliation(s)
- Kazuya Tatani
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Kashiwabara,
Hotaka, Azumino, Nagano 399-8304, Japan
- Faculty
of Pharmaceutical Science and §Center for Research and Education on Drug Discovery, Hokkaido University, Kita-12, Nishi-6, Kita-Ku, Sapporo 060-0812, Japan
| | - Masahiro Hiratochi
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Kashiwabara,
Hotaka, Azumino, Nagano 399-8304, Japan
| | - Yoshinori Nonaka
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Kashiwabara,
Hotaka, Azumino, Nagano 399-8304, Japan
| | - Masayuki Isaji
- Central
Research Laboratories, Kissei Pharmaceutical Co., Ltd., 4365-1, Kashiwabara,
Hotaka, Azumino, Nagano 399-8304, Japan
| | - Satoshi Shuto
- Faculty
of Pharmaceutical Science and §Center for Research and Education on Drug Discovery, Hokkaido University, Kita-12, Nishi-6, Kita-Ku, Sapporo 060-0812, Japan
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6
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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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7
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Stashkevych MA. Distribution of 5-fluorouracil between lymphocytes and blood plasma. UKRAINIAN BIOCHEMICAL JOURNAL 2013. [DOI: 10.15407/ubj85.04.094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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8
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Paproski RJ, Yao SYM, Favis N, Evans D, Young JD, Cass CE, Zemp RJ. Human concentrative nucleoside transporter 3 transfection with ultrasound and microbubbles in nucleoside transport deficient HEK293 cells greatly increases gemcitabine uptake. PLoS One 2013; 8:e56423. [PMID: 23441192 PMCID: PMC3575408 DOI: 10.1371/journal.pone.0056423] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 01/09/2013] [Indexed: 02/06/2023] Open
Abstract
Gemcitabine is a hydrophilic clinical anticancer drug that requires nucleoside transporters to cross plasma membranes and enter cells. Pancreatic adenocarcinomas with low levels of nucleoside transporters are generally resistant to gemcitabine and are currently a clinical problem. We tested whether transfection of human concentrative nucleoside transporter 3 (hCNT3) using ultrasound and lipid stabilized microbubbles could increase gemcitabine uptake and sensitivity in HEK293 cells made nucleoside transport deficient by pharmacologic treatment with dilazep. To our knowledge, no published data exists regarding the utility of using hCNT3 as a therapeutic gene to reverse gemcitabine resistance. Our ultrasound transfection system - capable of transfection of cell cultures, mouse muscle and xenograft CEM/araC tumors - increased hCNT3 mRNA and 3H-gemcitabine uptake by >2,000– and 3,400–fold, respectively, in dilazep-treated HEK293 cells. Interestingly, HEK293 cells with both functional human equilibrative nucleoside transporters and hCNT3 displayed 5% of 3H-gemcitabine uptake observed in cells with only functional hCNT3, suggesting that equilibrative nucleoside transporters caused significant efflux of 3H-gemcitabine. Efflux assays confirmed that dilazep could inhibit the majority of 3H-gemcitabine efflux from HEK293 cells, suggesting that hENTs were responsible for the majority of efflux from the tested cells. Oocyte uptake transport assays were also performed and provided support for our hypothesis. Gemcitabine uptake and efflux assays were also performed on pancreatic cancer AsPC-1 and MIA PaCa-2 cells with similar results to that of HEK293 cells. Using the MTS proliferation assay, dilazep-treated HEK293 cells demonstrated 13-fold greater resistance to gemcitabine compared to dilazep-untreated HEK293 cells and this resistance could be reversed by transfection of hCNT3 cDNA. We propose that transfection of hCNT3 cDNA using ultrasound and microbubbles may be a method to reverse gemcitabine resistance in pancreatic tumors that have little nucleoside transport activity which are resistant to almost all current anticancer therapies.
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Affiliation(s)
- Robert J. Paproski
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada
| | - Sylvia Y. M. Yao
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Nicole Favis
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - David Evans
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - James D. Young
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Carol E. Cass
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Roger J. Zemp
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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9
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Hiratochi M, Tatani K, Shimizu K, Kuramochi Y, Kikuchi N, Kamada N, Itoh F, Isaji M. Hypouricemic effects of novel concentrative nucleoside transporter 2 inhibitors through suppressing intestinal absorption of purine nucleosides. Eur J Pharmacol 2012; 690:183-91. [DOI: 10.1016/j.ejphar.2012.06.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/10/2012] [Accepted: 06/10/2012] [Indexed: 11/17/2022]
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10
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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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11
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Fernández-Calotti PX, Lopez-Guerra M, Colomer D, Pastor-Anglada M. Enhancement of fludarabine sensitivity by all-trans-retinoic acid in chronic lymphocytic leukemia cells. Haematologica 2011; 97:943-51. [PMID: 22180426 DOI: 10.3324/haematol.2011.051557] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND A subset of patients with fludarabine-resistant chronic lymphocytic leukemia has previously been shown to express elevated intracellular levels of the concentrative high-affinity fludarabine transporter hCNT3, without any detectable related activity. We have recently shown that all-trans-retinoic acid is capable of inducing hCNT3 trafficking to plasma membrane in the MEC1 cell line. We, therefore, evaluated the effect of all-trans-retinoic acid on hCNT3 in primary chronic lymphocytic leukemia cells as a suitable mechanism to improve fludarabine-based therapy of chronic lymphocytic leukemia. DESIGN AND METHODS Cells from 23 chronic lymphocytic leukemia patients wild-type for P53 were analyzed for ex vivo sensitivity to fludarabine. hCNT3 activity in chronic lymphocytic leukemia cell samples was evaluated by measuring the uptake of [8-(3)H]-fludarabine. The amounts of transforming growth factor-β1 and hCNT3 messenger RNA were analyzed by real-time polymerase chain reaction. The effect of all-trans-retinoic acid on hCNT3 subcellular localization was analyzed by confocal microscopy and its effect on fludarabine-induced apoptosis was evaluated by flow cytometry analysis using annexin V staining. RESULTS Chronic lymphocytic leukemia cases showing higher ex vivo basal sensitivity to fludarabine also had a greater basal hCNT3-associated fludarabine uptake capacity compared to the subset of patients showing ex vivo resistance to the drug. hCNT3 transporter activity in chronic lymphocytic leukemia cells from the latter patients was either negligible or absent. Treatment of the fludarabine-resistant subset of chronic lymphocytic leukemia cells with all-trans-retinoic acid induced increased fludarabine transport via hCNT3 which was associated with a significant increase in fludarabine sensitivity. CONCLUSIONS Improvement of ex vivo fludarabine sensitivity in chronic lymphocytic leukemia cells is associated with increased hCNT3 activity after all-trans-retinoic acid treatment.
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Affiliation(s)
- Paula X Fernández-Calotti
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, IBUB & CIBER EHD Diagonal 645, 08028 Barcelona, Spain.
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12
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Okayama T, Yoshisue K, Kuwata K, Komuro M, Ohta S, Nagayama S. Involvement of Concentrative Nucleoside Transporter 1 in Intestinal Absorption of Trifluorothymidine, a Novel Antitumor Nucleoside, in Rats. J Pharmacol Exp Ther 2011; 340:457-62. [DOI: 10.1124/jpet.111.186296] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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13
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Abstract
BACKGROUND Nucleoside/nucleobase transporters have been investigated since the 1960s. In particular, equilibrative nucleoside transporters were thought to be valuable drug targets, since they are involved in various kinds of viral and parasitic diseases as well as cancers. DISCUSSION In the postgenomic era multiple transporters, including different subtypes, have been cloned and characterized on the molecular level. In this article we summarize recent advances regarding structure, function and localization of nucleoside/nucleobase transporters as well as the pharmacological profile of selected drugs. CONCLUSION Knowledge of the different kinetic properties and structural features of nucleoside transporters can either be used for the rational design of therapeutics directly targeting the transporter itself or for the delivery of drugs using the transporter as a port of entry into the target cell. Equilibrative nucleoside transporters are of considerable pharmacological interest as drug targets for the development of drugs tailored to each patient's need for the treatment of cardiac disease, cancer and viral infections.
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14
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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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15
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Molina-Arcas M, Pastor-Anglada M. Role of Nucleoside Transporters in Nucleoside-Derived Drug Sensitivity. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2010; 29:335-46. [DOI: 10.1080/15257771003729823] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Errasti-Murugarren E, Pastor-Anglada M. Drug transporter pharmacogenetics in nucleoside-based therapies. Pharmacogenomics 2010; 11:809-41. [PMID: 20504255 DOI: 10.2217/pgs.10.70] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
This article focuses on the different types of transporter proteins that have been implicated in the influx and efflux of nucleoside-derived drugs currently used in the treatment of cancer, viral infections (i.e., AIDS) and other conditions, including autoimmune and inflammatory diseases. Genetic variations in nucleoside-derived drug transporter proteins encoded by the gene families SLC15, SLC22, SLC28, SLC29, ABCB, ABCC and ABCG will be specifically considered. Variants known to affect biological function are summarized, with a particular emphasis on those for which clinical correlations have already been established. Given that relatively little is known regarding the genetic variability of the players involved in determining nucleoside-derived drug bioavailability, it is anticipated that major challenges will be faced in this area of research.
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Affiliation(s)
- Ekaitz Errasti-Murugarren
- The Department of Biochemistry and Molecular Biology, Institute of Biomedicine, University of Barcelona, Diagonal 645, 08028 Barcelona, Spain
- Center for Biomedical Research Network in the Subject Area of Liver and Digestive Diseases (CIBERehd), Barcelona 08071, Spain
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Damaraju VL, Sawyer MB, Mackey JR, Young JD, Cass CE. Human nucleoside transporters: biomarkers for response to nucleoside drugs. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2010; 28:450-63. [PMID: 20183595 DOI: 10.1080/15257770903044499] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
This review describes recent advances in developing human nucleoside transporters (hNTs) as biomarkers to predict response to nucleoside analog drugs with clinical activity. Understanding processes that contribute to drug response or lack thereof will provide strategies to potentiate efficacy or avoid toxicities of nucleoside analog drugs. hNT abundance, evaluated by immunohistochemical methods, has shown promise as a predictive marker to assess clinical drug response that could be used to identify patients who would most likely benefit from nucleoside analog drug treatment.
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Affiliation(s)
- Vijaya L Damaraju
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
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18
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Spurgeon S, Yu M, Phillips JD, Epner EM. Cladribine: not just another purine analogue? Expert Opin Investig Drugs 2010; 18:1169-81. [PMID: 19604118 DOI: 10.1517/13543780903071038] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cladribine was synthesized as a purine analogue drug that inhibited adenosine deaminase. It received FDA approval in the 1980s for treatment of hairy cell leukemia. Given its toxicity towards lymphocytes and its corresponding immunosuppressive effects, it has been studied and found efficacious in a variety of hematologic malignancies and autoimmune conditions, most recently multiple sclerosis. This review highlights pharmacological, toxicological and clinical data for the use of cladribine. It also discusses existing and new mechanisms that may contribute to its unique clinical activity. Emerging data show that in addition to its known purine nucleoside analogue activity, cladribine possesses epigenetic properties, inhibiting S-adenosylhomocysteine hydrolase and DNA methylation. This may contribute to its efficacy and highlights the importance of studying combination therapy with other epigenetic or targeted agents. Clinical trials are underway in a variety of malignant and nonmalignant conditions.
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Affiliation(s)
- Stephen Spurgeon
- Oregon Health Sciences University, Medicine, 4130 Sam Jackson Park Road, Portland, OR 97239, USA
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19
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Lee TB, Choi CH. Detection of drug transporter expression using a 25-multiplex RT-PCR assay. Biotechnol Lett 2009; 31:1485-92. [PMID: 19495564 DOI: 10.1007/s10529-009-0039-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 05/17/2009] [Accepted: 05/19/2009] [Indexed: 11/29/2022]
Abstract
Membrane transporters play important roles in mediating chemoresistance and chemosensitivity of tumor cells. Five sets of 5 genes were designed to simultaneously detect drug transporter expression in a single reaction tube using multiplex RT-PCR for 25 genes, including 17 ABC transporters, one non-ABC transporter, 4 SLC transporters, 2 copper transporters and one housekeeping gene. We optimized the multiplex RT-PCR conditions using chemosensitive cancer cells and then validated the system using chemoresistant cancer cells. This reliable multiplex RT-PCR assay can be utilized not only to investigate anticancer drug-resistance mechanisms but also to estimate the efficacy of anticancer chemotherapy in the clinic.
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Affiliation(s)
- Tae-Bum Lee
- Research Center for Resistant Cells, Chosun University Medical School, Gwangju, 501-759, Korea
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20
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Pastor-Anglada M, Cano-Soldado P, Errasti-Murugarren E, Casado FJ. SLC28 genes and concentrative nucleoside transporter (CNT) proteins. Xenobiotica 2008; 38:972-94. [PMID: 18668436 DOI: 10.1080/00498250802069096] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The human concentrative nucleoside transporter (hCNT) protein family has three members, hCNT1, 2, and 3, encoded by SLC28A1, A2, and A3 genes, respectively. hCNT1 and hCNT2 translocate pyrimidine- and purine-nucleosides, respectively, by a sodium-dependent mechanism, whereas hCNT3 shows broad substrate selectivity and the unique ability of translocating nucleosides both in a sodium- and a proton-coupled manner. hCNT proteins are also responsible for the uptake of most nucleoside-derived antiviral and anticancer drugs. Thus, hCNTs are key pharmacological targets. This review focuses on several crucial aspects of hCNT biology and pharmacology: protein structure-function, structural determinants for transportability, pharmacogenetics of hCNT-encoding genes, role of hCNT proteins in nucleoside-based therapeutics, and finally hCNT physiology.
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Affiliation(s)
- M Pastor-Anglada
- Facultat de Biologia, Departament de Bioquimica i Biologia Molecular, Institut de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, Barcelona, Spain.
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21
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Leung GPH, Tse CM. The role of mitochondrial and plasma membrane nucleoside transporters in drug toxicity. Expert Opin Drug Metab Toxicol 2008; 3:705-18. [PMID: 17916056 DOI: 10.1517/17425255.3.5.705] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many anticancer and antiviral drugs are nucleoside analogues, which interfere with nucleotide metabolism and DNA replication to produce pharmacological effects. Clinical efficacy and toxicity of nucleoside drugs are closely associated with nucleoside transporters because they mediate the transport of nucleoside drugs across biological membranes. Two families of human nucleoside transporters (equilibrative nucleoside transporters and concentrative nucleoside transporters) have been extensively studied for several decades. They are widely distributed, from the plasma membrane to membranes of organelles such as mitochondria, and the distribution differs in different tissues. In addition, they have different specificities to nucleoside drugs. The characteristics of equilibrative and concentrative nucleoside transporters affect the therapeutic outcomes achieved with anticancer and antiviral nucleoside drugs. In this review, an overview of the role of mitochondrial and plasma membrane nucleoside transporters in nucleoside drug toxicity is provided. Rational design and therapeutic application of nucleoside analogues are also discussed.
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Affiliation(s)
- George P H Leung
- The University of Hong Kong, Department of Pharmacology, Hong Kong.
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22
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Govindarajan R, Bakken AH, Hudkins KL, Lai Y, Casado FJ, Pastor-Anglada M, Tse CM, Hayashi J, Unadkat JD. In situ hybridization and immunolocalization of concentrative and equilibrative nucleoside transporters in the human intestine, liver, kidneys, and placenta. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1809-22. [PMID: 17761511 DOI: 10.1152/ajpregu.00293.2007] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To better understand the role of human equilibrative (hENTs) and concentrative (hCNTs) nucleoside transporters in physiology and pharmacology, we investigated the regional, cellular, and spatial distribution of two hCNTs (hCNT1 and hCNT2) and two hENTs (hENT1 and hENT2) in four human tissues. Using in situ hybridization and immunohistochemical techniques, we found that the duodenum expressed hCNT1 and hCNT2 mRNAs in enterocytes and hENT1 and hENT2 mRNAs in crypt cells. In these cells, the hCNT and hENT proteins were predominantly localized in the apical and lateral membrane, respectively. Hepatocytes expressed higher levels of mRNAs of hENT1, hCNT1, and hENT2 than of hCNT2 and expressed all these proteins at hepatocyte cell borders and in the cytoplasm. While the kidney expressed hCNT1 and hCNT2 mRNAs in the proximal tubules, hENT1 and hENT2 mRNAs were present in the distal tubules, glomeruli, endothelial cells, and vascular smooth muscle cells. Proximal tubules adjacent to corticomedullary junctions expressed hENT1, hCNT1, and hCNT2 mRNA. Immunolocalization studies revealed predominant localization of hCNTs in the brush-border membrane of the proximal tubular epithelial cells and hENTs in the basolateral membrane of the distal tubular epithelial cells. Chorionic villi sections of human term placenta expressed mRNAs and proteins for hENT1 and hENT2 but only mRNA for hCNT2. Immunolocalization studies showed presence of hENT1 in the brush-border membrane of the syncytiotrophoblasts. These data are critical for a better understanding of the role of nucleoside transporters in the physiological and pharmacological effects of nucleosides and nucleoside drugs, respectively.
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Affiliation(s)
- Rajgopal Govindarajan
- Dept. of Pharmaceutics, University of Washington, Box 357610, Seattle, WA 98195, USA
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23
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Zhang J, Visser F, King KM, Baldwin SA, Young JD, Cass CE. The role of nucleoside transporters in cancer chemotherapy with nucleoside drugs. Cancer Metastasis Rev 2007; 26:85-110. [PMID: 17345146 DOI: 10.1007/s10555-007-9044-4] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nucleoside analogs are important components of treatment regimens for various malignancies. Nucleoside-specific membrane transporters mediate plasma membrane permeation of physiologic nucleosides and most nucleoside analogs, for which the initial event is cellular conversion of nucleosides to active agents. Understanding of the roles of nucleoside transporters in nucleoside drug toxicity and resistance will provide opportunities for potentiating anticancer efficacy and avoiding resistance. Because transportability is a possible determinant of toxicity and resistance of many nucleoside analogs, nucleoside transporter abundance might be a prognostic marker to assess drug resistance. Elucidation of the structural determinants of nucleoside analogs for interaction with transporter proteins as well as the structural features of transporter proteins required for permeant interaction and translocation will lead to "transportability guidelines" for the rational design and therapeutic application of nucleoside analogs as anticancer drugs. It should eventually be possible to develop clinical assays that predict sensitivity and/or resistance to nucleoside anti-cancer drugs and thus to identify those patient populations that will most likely benefit from optimal nucleoside analog treatments. This review discusses recent results from structure/function studies of human nucleoside transporters, the role of nucleoside transport processes in the cytotoxicity and resistance of several anticancer nucleoside analogs and strategies to improve the nucleoside transporter-related anticancer effects of nucleoside analogs.
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Affiliation(s)
- Jing Zhang
- Membrane Protein Research Group, University of Alberta, Edmonton, AB, Canada
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24
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Pastor-Anglada M, Errasti-Murugarren E, Aymerich I, Casado FJ. Concentrative nucleoside transporters (CNTs) in epithelia: from absorption to cell signaling. J Physiol Biochem 2007; 63:97-110. [PMID: 17722647 DOI: 10.1007/bf03174089] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Concentrative and Equilibrative Nucleoside Transporter proteins (CNT and ENT, respectively) are encoded by gene families SLC28 and SLC29. They mediate the uptake of natural nucleosides and a variety of nucleoside-derived drugs, mostly used in anticancer therapy. CNT and ENT proteins are mostly localized in the apical and basolateral sides, respectively, in (re)absorptive epithelia. This anatomic distribution determines nucleoside and nucleoside-derived vectorial flux. CNT expression (particularly CNT2) is associated with differentiation and is also nutritionally regulated in intestinal epithelia, whereas ENT protein amounts (mostly ENT1) are increased when cells are exposed to proliferative stimuli such as EGF, TGF-alpha or wounding. Although all these features suggest a role for NT proteins in nucleoside salvage and (re)absorption, recent data demonstrate that CNT2 might be under purinergic control, in a manner that is dependent on energy metabolism. A physiological link between CNT2 function and intracellular metabolism is also supported by the evidence that extracellular adenosine can activate the AMP-dependent kinase (AMPK), by a mechanism which relies upon adenosine transport and phosphorylation. Thus the complex pattern of NT isoform expression in mammalian cells can fulfill physiological roles other than salvage.
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Affiliation(s)
- M Pastor-Anglada
- Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina de la Universitat de Barcelona, Spain.
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25
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Larráyoz IM, Fernández-Nistal A, Garcés A, Gorraitz E, Lostao MP. Characterization of the rat Na+/nucleoside cotransporter 2 and transport of nucleoside-derived drugs using electrophysiological methods. Am J Physiol Cell Physiol 2006; 291:C1395-404. [PMID: 16837649 DOI: 10.1152/ajpcell.00110.2006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Na+-dependent nucleoside transporter 2 (CNT2) mediates active transport of purine nucleosides and uridine as well as therapeutic nucleoside analogs. We used the two-electrode voltage-clamp technique to investigate rat CNT2 (rCNT2) transport mechanism and study the interaction of nucleoside-derived drugs with the transporter expressed in Xenopus laevis oocytes. The kinetic parameters for sodium, natural nucleosides, and nucleoside derivatives were obtained as a function of membrane potential. For natural substrates, apparent affinity ( K0.5) was in the low micromolar range (12–34) and was voltage independent for hyperpolarizing membrane potentials, whereas maximal current ( Imax) was voltage dependent. Uridine and 2′-deoxyuridine analogs modified at the 5-position were substrates of rCNT2. Lack of the 2′-hydroxyl group decreased affinity but increased Imax. Increase in the size and decrease in the electronegativity of the residue at the 5-position affected the interaction with the transporter by decreasing both affinity and Imax. Fludarabine and formycin B were also transported with higher Imaxthan uridine and moderate affinity (102 ± 10 and 66 ± 6 μM, respectively). Analysis of the pre-steady-state currents revealed a half-maximal activation voltage of about −39 mV and a valence of about −0.8. K0.5for Na+was 2.3 mM at −50 mV and decreased at hyperpolarizing membrane potentials. The Hill coefficient was 1 at all voltages. Direct measurements of radiolabeled nucleoside fluxes with the charge associated showed a ratio of two positive inward charges per nucleoside, suggesting a stoichiometry of two Na+per nucleoside. This discrepancy in the number of Na+molecules that bind rCNT2 may indicate a low degree of cooperativity between the Na+binding sites.
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Affiliation(s)
- Ignacio M Larráyoz
- Department of Physiology and Nutrition, University of Navarra, Pamplona, Spain
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26
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Takahashi E, Inanami O, Ohta T, Matsuda A, Kuwabara M. Lipid raft disruption prevents apoptosis induced by 2-chloro-2′-deoxyadenosine (Cladribine) in leukemia cell lines. Leuk Res 2006; 30:1555-61. [PMID: 16730061 DOI: 10.1016/j.leukres.2006.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 04/10/2006] [Accepted: 04/15/2006] [Indexed: 10/24/2022]
Abstract
To clarify the role of lipid rafts in 2-chloro-2'-deoxyadenosine (2CdA; Cladribine)-induced apoptosis, the effects of disruption of lipid rafts by methyl-beta-cyclodextrin (MbetaCD) and filipin on 2CdA-induced apoptosis were investigated in four human acute lymphoblastic leukemia (ALL) cell lines comprised of T cells (MOLT-4, Jurkat) and B cells (NALM, BALL-1). The disruption of lipid rafts significantly inhibited 2CdA-induced apoptosis, indicating the crucial role of lipid rafts in the induction of apoptosis in leukemia cells. These reagents significantly inhibited 2CdA-induced elevation of the intracellular calcium concentration ([Ca(2+)](i)) in MOLT-4 cells, and 2CdA-induced apoptosis was partly inhibited by the Ca(2+) chelators BAPTA-AM and EGTA, and the L-type Ca(2+) channel blocker nifedipine. On the other hand, they had no effects on the cellular uptake of 2CdA. These results indicated that lipid rafts partly contributed to 2CdA-induced apoptosis by regulating Ca(2+) influx via the plasma membrane.
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Affiliation(s)
- Eriko Takahashi
- Laboratory of Radiation Biology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18 jo Nishi 9 chome, Sapporo, Japan
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27
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Chen P, Chien PY, Khan AR, Sheikh S, Ali SM, Ahmad MU, Ahmad I. In-vitro and in-vivo anti-cancer activity of a novel gemcitabine-cardiolipin conjugate. Anticancer Drugs 2006; 17:53-61. [PMID: 16317290 DOI: 10.1097/01.cad.0000185182.80227.48] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Our objectives were to study the biological activity of a novel gemcitabine-cardiolipin conjugate (NEO6002) and compare that with gemcitabine. Cytotoxicity in vitro was determined against several gemcitabine-sensitive parental and gemcitabine-resistant cancer cell lines using the sulforhodamine B assay. The in vivo toxicity was examined by changes in body weight and hematologic indices of conventional mice. Immunodeficient SCID mice bearing P388 and BxPC-3 tumor xenografts were used to evaluate the in-vivo therapeutic efficacy. Both NEO6002 and gemcitabine showed pro-apoptotic and cytotoxic effects against all gemcitabine-sensitive cell lines tested. Unlike gemcitabine, the cytotoxicity of NEO6002 was independent of nucleoside transporter (NT) inhibitors, indicating a different internalization route of NEO6002. The conjugate demonstrated a favorable activity not only in ARAC-8C, a NT-deficient gemcitabine-resistant human leukemia cell line, but also in several other gemcitabine-resistant cell lines. At the in-vivo level, a comparative toxicity study showed a significant body weight loss and a decrease in white blood cell counts in gemcitabine-treated mice, whereas the influence of NEO6002 was mild. Treatment of NEO6002 at 27 micromol/kg increased the median survival of CD2F1 mice bearing P388 cells by up to 73%, while at the same doses and schedule of gemcitabine resulted in toxic deaths of all treated mice. At a dose of 18 micromol/kg, NEO6002 inhibited the growth of BxPC-3 xenografts by 52%, while only 32% of tumor inhibition was achieved with gemcitabine. We conclude that NEO6002 may be an effective chemotherapeutic agent with improved tolerability and can potentially circumvent NT-deficient, gemcitabine-resistant tumors.
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Affiliation(s)
- Paul Chen
- Research and Development, NeoPharm Inc., Waukegan, Illinois 60085, USA
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28
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Clarke ML, Damaraju VL, Zhang J, Mowles D, Tackaberry T, Lang T, Smith KM, Young JD, Tomkinson B, Cass CE. The Role of Human Nucleoside Transporters in Cellular Uptake of 4′-Thio-β-d-arabinofuranosylcytosine and β-d-Arabinosylcytosine. Mol Pharmacol 2006; 70:303-10. [PMID: 16617163 DOI: 10.1124/mol.105.021543] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
4'-Thio-beta-D-arabinofuranosyl cytosine (TaraC) is in phase I development for treatment of cancer. In human equilibrative nucleoside transporter (hENT) 1-containing CEM cells, initial rates of uptake (10 microM; picomoles per microliter of cell water per second) of [3H]TaraC and [3H]1-beta-D-arabinofuranosyl cytosine (araC) were low (0.007 +/- 003 and 0.034 +/- 0.003, respectively) compared with that of [3H]uridine (0.317 +/- 0.048), a highactivity hENT1 permeant. In hENT1- and hENT2-containing HeLa cells, initial rates of uptake (10 microM; picomoles per cell per second) of [3H]TaraC, [3H]araC, and [3H]deoxycytidine were low (0.30 +/- 0.003, 0.42 +/- 0.03, and 0.51 +/- 0.11, respectively) and mediated primarily by hENT1 (approximately 74, approximately 65, and approximately 61%, respectively). In HeLa cells with recombinant human concentrative nucleoside transporter (hCNT) 1 or hCNT3 and pharmacologically blocked hENT1 and hENT2, transport of 10 microM[3H]TaraC and [3H]araC was not detected. The apparent affinities of recombinant transporters (produced in yeast) for a panel of cytosine-containing nucleosides yielded results that were consistent with the observed low-permeant activities of TaraC and araC for hENT1/2 and negligible permeant activities for hCNT1/2/3. During prolonged drug exposures of CEM cells with hENT1 activity, araC was more cytotoxic than TaraC, whereas coexposures with nitrobenzylthioinosine (to pharmacologically block hENT1) yielded identical cytotoxicities for araC and TaraC. The introduction by gene transfer of hENT2 and hCNT1 activities, respectively, into nucleoside transport-defective CEM cells increased sensitivity to both drugs moderately and slightly. These results demonstrated that nucleoside transport capacity (primarily via hENT1, to a lesser extent by hENT2 and possibly by hCNT1) is a determinant of pharmacological activity of both drugs.
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Affiliation(s)
- Marilyn L Clarke
- Department of Oncology, Cross Cancer Institute, 11560 University Ave., Edmonton, AB, T6G 1Z2 Canada
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29
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Fotoohi AK, Lindqvist M, Peterson C, Albertioni F. Involvement of the concentrative nucleoside transporter 3 and equilibrative nucleoside transporter 2 in the resistance of T-lymphoblastic cell lines to thiopurines. Biochem Biophys Res Commun 2006; 343:208-15. [PMID: 16530731 DOI: 10.1016/j.bbrc.2006.02.134] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2006] [Accepted: 02/22/2006] [Indexed: 02/08/2023]
Abstract
Mechanisms of resistance to thiopurines, 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) were investigated in human leukemia cell lines. We developed two 6-MP- and 6-TG-resistant cell lines from the human T-lymphoblastic cell line (MOLT-4) by prolonged exposure to these drugs. The resistant cells were highly cross resistant to 6-MP and 6-TG, and exhibited marked reduction in cellular uptake of 6-MP (70% and 80%, respectively). No significant modification of the activities of hypoxanthine-guanine phosphoribosyl transferase, thiopurine methyltransferase or inosine monophosphate dehydrogenase was observed. Real-time PCR of concentrative nucleoside transporter 3 (CNT3) and equilibrative nucleoside transporter 2 (ENT2) of resistant cells showed substantial reductions in expression of messenger RNAs. Small interfering RNA designed to silence the CNT3 and ENT2 genes down-regulated the expression of these genes in leukemia cells. These decreases were accompanied by reduction of transport of 6-MP (47% and 21%, respectively) as well as its cytocidal effect (30% and 21%, respectively). Taken together these results show that CNT3 and ENT2 play a key role in the transport of 6-MP and 6-TG by leukemia cells. From a clinical point of view determination of CNT3 and ENT2 levels in leukemia cells may be useful in predicting the efficacy of thiopurine treatment.
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Affiliation(s)
- Alan Kambiz Fotoohi
- Department of Oncology and Pathology, Cancer Center Karolinska, Karolinska Institute, Stockholm, Sweden
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30
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King KM, Damaraju VL, Vickers MF, Yao SY, Lang T, Tackaberry TE, Mowles DA, Ng AML, Young JD, Cass CE. A comparison of the transportability, and its role in cytotoxicity, of clofarabine, cladribine, and fludarabine by recombinant human nucleoside transporters produced in three model expression systems. Mol Pharmacol 2005; 69:346-53. [PMID: 16234483 DOI: 10.1124/mol.105.015768] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
2-Chloro-9-(2'-deoxy-2'-fluoro-beta-d-arabinofuranosyl)adenine (Cl-F-ara-A, clofarabine), a purine nucleoside analog with structural similarity to 2-chloro-2'-deoxyadenosine (Cl-dAdo, cladribine) and 9-beta-d-arabinofuranosyl-2-fluoroadenine (F-ara-A, fludarabine), has activity in adult and pediatric leukemias. Mediated transport of the purine nucleoside analogs is believed to occur through the action of two structurally unrelated protein families, the equilibrative nucleoside transporters (ENTs) and the concentrative nucleoside transporters (CNTs). The current work assessed the transportability of Cl-F-ara-A, Cl-dAdo, and F-ara-A in cultured human leukemic CEM cells that were either nucleoside transport-defective or possessed individual human nucleoside transporter types and in Xenopus laevis oocytes and Saccharomyces cerevisiae yeast that produced individual recombinant human nucleoside transporter types. Cells producing hENT1 or hCNT3 exhibited the highest uptake of Cl-F-ara-A, whereas nucleoside transport-deficient cells and cells producing hCNT1 lacked uptake altogether. When Cl-F-ara-A transport rates by hENT1 were compared with those of Cl-dAdo and F-ara-A, Cl-dAdo had the highest efficiency of transport, although Cl-F-ara-A showed the greatest accumulation during 5-min exposures. In cytotoxicity studies with the CEM lines, Cl-F-ara-A was more cytotoxic to cells producing hENT1 than to the nucleoside transport-deficient cells. The efficiency of Cl-F-ara-A transport by oocytes with recombinant transporters was hCNT3 > hENT2 > hENT1 > hCNT2; no transport was observed with hCNT1. Affinity studies with recombinant transporters produced in yeast showed that hENT1, hENT2, and hCNT3 all had higher affinities for Cl-F-ara-A than for either Cl-dAdo or F-ara-A. These results suggest that the nature and activity of the plasma membrane proteins capable of inward transport of nucleosides are important determinants of Cl-F-ara-A activity in human cells.
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Affiliation(s)
- Karen M King
- Department of Oncology, Cross Cancer Institute, 11560 University Avenue, Edmonton, AB, Canada, T6G 1Z2
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31
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Damaraju S, Zhang J, Visser F, Tackaberry T, Dufour J, Smith KM, Slugoski M, Ritzel MWL, Baldwin SA, Young JD, Cass CE. Identification and functional characterization of variants in human concentrative nucleoside transporter 3, hCNT3 (SLC28A3), arising from single nucleotide polymorphisms in coding regions of the hCNT3 gene. Pharmacogenet Genomics 2005; 15:173-82. [PMID: 15861042 DOI: 10.1097/01213011-200503000-00006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
INTRODUCTION Human concentrative nucleoside transporter 3, hCNT3 (SLC28A3), which mediates transport of purine and pyrimidine nucleosides and a variety of antiviral and anticancer nucleoside drugs, was investigated to determine if there are single nucleotide polymorphisms in the coding regions of the hCNT3 gene. METHODS AND RESULTS Ninety-six DNA samples from Caucasians (Coriell Panel) were sequenced and sixteen variants in exons and flanking intronic regions were identified, of which five were coding variants; three of these were non-synonymous (S5N, L131F, Y513F) and were further investigated for functional alterations of the resulting recombinant proteins in Saccharomyces cerevisiae and Xenopus laevis oocytes. In yeast, immunostaining and fluorescence quantitation of the reference (wild-type) and variant CNT3 proteins showed similar levels of expression. Kinetic studies were undertaken in yeast with a high through-put semi-automated assay process; reference hCNT3 exhibited Km values of 1.7+/-0.3, 3.6+/-1.3, 2.2+/-0.7, and 2.1+/-0.6 muM and Vmax values of 1402+/-286, 1310+/-113, 1020+/-44, and 1740+/-114 pmol/mg/min, respectively, for uridine, cytidine, adenosine and inosine. Similar Km and Vmax values were obtained for the three variant proteins assayed in yeast under identical conditions. All of the characterized hCNT3 variants produced in oocytes retained sodium and proton dependence of uridine transport based on measurements of radioisotope flux and two-electrode voltage-clamp studies. CONCLUSION These results suggested a high degree of conservation of function for hCNT3 in the Caucasian population.
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Zhang J, Smith KM, Tackaberry T, Visser F, Robins MJ, Nielsen LPC, Nowak I, Karpinski E, Baldwin SA, Young JD, Cass CE. Uridine binding and transportability determinants of human concentrative nucleoside transporters. Mol Pharmacol 2005; 68:830-9. [PMID: 15955867 DOI: 10.1124/mol.105.012187] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Human concentrative nucleoside transporters 1, 2, and 3 (hCNT1, hCNT2, and hCNT3) exhibit different functional characteristics, and a better understanding of their permeant selectivities is critical for development of nucleoside analog drugs with optimal pharmacokinetic properties. In this study, the sensitivity of a high-throughput yeast expression system used previously for hCNT1 and hCNT3 was improved and used to characterize determinants for interaction of uridine (Urd) with hCNT2. The observed changes of binding energy between hCNT2 and different Urd analogs suggested that it interacts with C3'-OH, C5'-OH, and N3-H of Urd. The C2' and C5 regions of Urd played minor but significant roles for Urd-hCNT2 binding, possibly through Van der Waals interactions. Because the yeast assay only provided information about potential transportability, the permeant selectivities of recombinant hCNT1, hCNT2, and hCNT3 produced in Xenopus laevis oocytes were investigated using a two-electrode voltage clamp assay. hCNT1-mediated transport was sensitive to modifications of the N3, C3', and C5' positions of Urd. hCNT2 showed some tolerance for transporting Urd analogs with C2' or C5 modifications, little tolerance for N3 modifications, and no tolerance for any modifications at C3' or C5' of Urd. Although hCNT3 was sensitive to C3' modifications, it transported a broad range of variously substituted Urd analogs. The transportability profiles identified in this study, which reflected the binding profiles well, should prove useful in the development of anticancer and antiviral therapies with nucleoside drugs that are permeants of members of the hCNT protein family.
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Affiliation(s)
- Jing Zhang
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11540 University Ave., Edmonton, Alberta, Canada T6H 1Z2
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Pastor-Anglada M, Cano-Soldado P, Molina-Arcas M, Lostao MP, Larráyoz I, Martínez-Picado J, Casado FJ. Cell entry and export of nucleoside analogues. Virus Res 2005; 107:151-64. [PMID: 15649561 DOI: 10.1016/j.virusres.2004.11.005] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Some nucleoside analogues currently used as antiretroviral agents might promote mutagenesis besides their putative ability to interfere with endogenous nucleotide metabolism and/or inhibit viral transcription. The intracellular concentration of nucleosides and nucleobases is to some extent the result of the metabolic background of the specific cell line used for infection studies, its particular suit of enzymes and transporters. This review focuses on the transporter-mediated pathways implicated in either the uptake or the efflux of nucleoside- and nucleobase-derivatives. From a biochemical point of view, four different types of transport processes for nucleoside-related antiviral drugs have been described: (1) equilibrative uniport, (2) substrate exchange, (3) concentrative Na+- or H+-dependent uptake and finally, (4) substrate export through primary ATP-dependent active efflux pumps. These mechanisms are mainly related to the following set of transporter families: Concentrative Nucleoside Transporter (CNT), Equilibrative Nucleoside Transporter (ENT), Organic Anion Transporter (OAT) and Organic Cation Transporter (OCT), Peptide Transporter (PEPT) and Multidrug Resistance Protein (MRP). The basic properties of these carrier proteins and their respective role in the transport across the plasma membrane of nucleoside-derived antiviral drugs are reviewed.
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Affiliation(s)
- Marçal Pastor-Anglada
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
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34
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Damaraju VL, Visser F, Zhang J, Mowles D, Ng AML, Young JD, Jayaram HN, Cass CE. Role of human nucleoside transporters in the cellular uptake of two inhibitors of IMP dehydrogenase, tiazofurin and benzamide riboside. Mol Pharmacol 2004; 67:273-9. [PMID: 15486050 DOI: 10.1124/mol.104.004408] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Benzamide riboside (BR) and tiazofurin (TR) are converted to analogs of NAD that inhibit IMP dehydrogenase (IMPDH), resulting in cellular depletion of GTP and dGTP and inhibition of proliferation. The current work was undertaken to identify the human nucleoside transporters involved in cellular uptake of BR and TR and to evaluate their role in cytotoxicity. Transportability was examined in Xenopus laevis oocytes and Saccharomyces cerevisiae that produced individual recombinant human concentrative nucleoside transporter (CNT) and equilibrative nucleoside transporter (ENT) types (hENT1, hENT2, hCNT1, hCNT2, or hCNT3). TR was a better permeant than BR with a rank order of transportability in oocytes of hCNT3 >> hENT1 > hENT2 > hCNT2 >> hCNT1. The concentration dependence of inhibition of [(3)H]uridine transport in S. cerevisiae by TR exhibited lower K(i) values than BR: hCNT3 (5.4 versus 226 microM), hENT2 (16 versus 271 microM), hENT1 (57 versus 168 microM), and hCNT1 (221 versus 220 microM). In cytotoxicity experiments, BR was more cytotoxic than TR to cells that were either nucleoside transport-defective or -competent, and transport-competent cells were more sensitive to both drugs. Exposure to nitrobenzylmercaptopurine ribonucleoside conferred resistance to BR and TR cytotoxicity to hENT1-containing CEM cells, thereby demonstrating the importance of transport capacity for manifestation of cytoxicity. A breast cancer cell line with mutant p53 exhibited 9-fold higher sensitivity to BR than the otherwise similar cell line with wild-type p53, suggesting that cells with mutant p53 may be potential targets for IMPDH inhibitors. Further studies are warranted to determine whether this finding can be generalized to other cell types.
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Affiliation(s)
- Vijaya L Damaraju
- Department of Oncology, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
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35
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Lang TT, Young JD, Cass CE. Interactions of Nucleoside Analogs, Caffeine, and Nicotine with Human Concentrative Nucleoside Transporters 1 and 2 Stably Produced in a Transport-Defective Human Cell Line. Mol Pharmacol 2004; 65:925-33. [PMID: 15044622 DOI: 10.1124/mol.65.4.925] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Pharmacologically important drugs were examined as potential inhibitors or permeants of human concentrative nucleoside transporters 1 (hCNT1)- and 2 (hCNT2)-producing stable transfectants by assessing their abilities to inhibit uridine transport. hCNT1 exhibited high affinities for uridine analogs (5-fluorouridine, 2'-deoxyuridine, 5-fluoro-2'-deoxyuridine, and 5-fluoro-5'-deoxyuridine) with K(i) values of 22 to 33 microM, whereas hCNT2 exhibited moderate affinities for 5-fluoro-2'-deoxyuridine, high affinities for 2'-deoxyuridine and 5-fluorouridine, and low affinity for 5-fluoro-5'-deoxyuridine. The uridine analogs were transported at 2-fold higher rates (at 10 microM) by hCNT1 than by hCNT2. Enantiomeric configuration and the 3'-hydroxyl group of the ribose ring were important determinants for interaction with hCNTs, whereas the 2'-hydroxyl group was less important. Both transporters bound N(6)-(p-aminobenzyl)adenosine with affinities similar to those of adenosine (K(i) = 28-39 microM). Other adenosine receptor ligands, including caffeine, bound better to hCNT1 than to hCNT2 (K(i) = 46 versus 103 microM, respectively), whereas 2-chloroadenosine bound better to hCNT2 than to hCNT1 (K(i) = 37 and 101 microM, respectively). There was a greater than 3-fold difference in binding affinities between hCNT1 and hCNT2 for nicotine (K(i) = 63 versus 227 microM). However, direct measurements of nicotine and caffeine uptake rates (10 microM) failed to demonstrate mediated uptake by either transporter. Although hCNT1 bound several adenosine analogs relatively well, it did not transport 2-chloro-2'-deoxyadenosine (cladribine) or 2-fluoro-9-beta-d-arabinofuranosyladenine (fludarabine), whereas hCNT2 transported both, albeit with low activities. The results indicated that although hCNT1 and hCNT2 possess some overlap in transport of several uridine and adenosine analogs, they also exhibit distinct differences in capacity to interact with some adenosine receptor ligands, adenosine-based drugs, and nicotine.
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Affiliation(s)
- Thack T Lang
- Canadian Institutes of health Research Molecular Biology of membranes Group, University of Alberta, Alberta, Canada T6G 1Z2
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36
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Pastor-Anglada M, Molina-Arcas M, Casado FJ, Bellosillo B, Colomer D, Gil J. Nucleoside transporters in chronic lymphocytic leukaemia. Leukemia 2004; 18:385-93. [PMID: 14737075 DOI: 10.1038/sj.leu.2403271] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Nucleoside derivatives have important therapeutic activity in chronic lymphocytic leukaemia (CLL). Experimental evidence indicates that in CLL cells most of these drugs induce apoptosis ex vivo, suggesting that programmed cell death is the mechanism of their therapeutic action, relying upon previous uptake and metabolic activation. Although defective apoptosis and poor metabolism often cause resistance to treatment, differential uptake and/or export of nucleosides and nucleotides may significantly modulate intracellular drug bioavailability and, consequently, responsiveness to therapy. Two gene families, SLC28 and SLC29, encode transporter proteins responsible for concentrative and equilibrative nucleoside uptake (CNT and ENT, respectively). Furthermore, selected members of the expanding ATP-binding cassette (ABC) protein family have recently been identified as putative efflux pumps for the phosphorylated forms of these nucleoside-derived drugs, ABCC11 (MRP8) being a good candidate to modulate cell sensitivity to fluoropyrimidines. Sensitivity of CLL cells to fludarabine has also been recently correlated with ENT-type transport function, suggesting that, besides the integrity of apoptotic pathways and appropriate intracellular metabolism, transport across the plasma membrane is also a relevant event during CLL treatment. As long as nucleoside transporter expression in leukaemia cells is not constitutive, the possibility of regulating nucleoside transporter function by pharmacological means may also contribute to improve therapy.
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Affiliation(s)
- M Pastor-Anglada
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain.
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37
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Chang C, Swaan PW, Ngo LY, Lum PY, Patil SD, Unadkat JD. Molecular requirements of the human nucleoside transporters hCNT1, hCNT2, and hENT1. Mol Pharmacol 2004; 65:558-70. [PMID: 14978234 DOI: 10.1124/mol.65.3.558] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Concentrative nucleoside transporters (CNTs) and equilibrative nucleoside transporters (ENTs) are important in physiological and pharmacological activity and disposition of nucleosides and nucleoside drugs. A better understanding of the structural requirements of inhibitors for these transporters will aid in designing therapeutic agents. To define the relative and unified structural requirements of nucleoside analogs for interaction with hCNT1, hCNT2, and hENT1, we applied an array of structure-activity techniques. Unique pharmacophore models for each respective nucleoside transporter were generated. These models reveal that hCNT2 affinity is dominated by hydrogen bonding features, whereas hCNT1 and hENT1 displayed mainly electrostatic and steric features. Hydrogen bond formation over 3'-OH is essential for all nucleoside transporters. Inhibition of nucleoside transporters by a series of uridine and adenosine analogs and a variety of drugs was analyzed by comparative molecular field analysis. Cross-validated r2 (q2) values were 0.65, 0.52, and 0.74 for hCNT1, hCNT2, and hENT1, respectively. The predictive quality of the models was further validated by successful prediction of the inhibition of a set of test compounds. Addition of a hydroxyl group around the 2-position of purine (or 3-position of pyrimidine) may increase inhibition to hCNT2 transporter; addition of hydroxyl group around the 2,7-position of purine (or the 3,5-position of pyrimidine) would increase the inhibition to hENT1 transporter. Utilization of these models should assist the design of high-affinity nucleoside transporter inhibitors and substrates for both anticancer and antiviral therapy.
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Affiliation(s)
- C Chang
- Biophysics Program, the Ohio State University, Columbus, USA
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38
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Damaraju VL, Damaraju S, Young JD, Baldwin SA, Mackey J, Sawyer MB, Cass CE. Nucleoside anticancer drugs: the role of nucleoside transporters in resistance to cancer chemotherapy. Oncogene 2003; 22:7524-36. [PMID: 14576856 DOI: 10.1038/sj.onc.1206952] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The clinical efficacy of anticancer nucleoside drugs depends on a complex interplay of transporters mediating entry of nucleoside drugs into cells, efflux mechanisms that remove drugs from intracellular compartments and cellular metabolism to active metabolites. Nucleoside transporters (NTs) are important determinants for salvage of preformed nucleosides and mediated uptake of antimetabolite nucleoside drugs into target cells. The focus of this review is the two families of human nucleoside transporters (hENTs, hCNTs) and their role in transport of cytotoxic chemotherapeutic nucleoside drugs. Resistance to anticancer nucleoside drugs is a major clinical problem in which NTs have been implicated. Single nucleotide polymorphisms (SNPs) in drug transporters may contribute to interindividual variation in response to nucleoside drugs. In this review, we give an overview of the functional and molecular characteristics of human NTs and their potential role in resistance to nucleoside drugs and discuss the potential use of genetic polymorphism analyses for NTs to address drug resistance.
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Affiliation(s)
- Vijaya L Damaraju
- Membrane Protein Research Group, University of Alberta, 11560 University Avenue, Edmonton, Alberta, Canada T6G 1Z2
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Shin HC, Landowski CP, Sun D, Vig BS, Kim I, Mittal S, Lane M, Rosania G, Drach JC, Amidon GL. Functional expression and characterization of a sodium-dependent nucleoside transporter hCNT2 cloned from human duodenum. Biochem Biophys Res Commun 2003; 307:696-703. [PMID: 12893280 DOI: 10.1016/s0006-291x(03)01259-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have cloned and functionally expressed a sodium-dependent human nucleoside transporter, hCNT2, from a CNS cancer cell line U251. Our cDNA clone of hCNT2 had the same predicted amino acid sequence as the previously cloned hCNT2 transporter. Of the several cell lines studied, the best hCNT2 transport function was obtained when transiently expressed in U251 cells. Na(+)-dependent uptake of [3H]inosine in U251 cells transiently expressing hCNT2 was 50-fold greater than that in non-transfected cells, and uptake in Na(+)-containing medium was approximately 30-fold higher than that at Na(+)-free condition. The hCNT2 displayed saturable uptake of [3H]inosine with K(m) of 12.8 microM and V(max) of 6.66 pmol/mg protein/5 min. Uptake of [3H]inosine was significantly inhibited by the purine nucleoside drugs dideoxyinosine and cladribine, but not by acyclic nucleosides including acyclovir, ganciclovir, and their prodrugs valacyclovir and valganciclovir. This indicates that the closed ribose ring is important for binding of nucleoside drugs to hCNT2. Among several pyrimidine nucleosides, hCNT2 favorably interacted with the uridine analogue floxuridine. Interestingly, we found that benzimidazole analogues, including maribavir, 5,6-dichloro-2-bromo-1-beta-D-ribofuranosylbenzimidazole (BDCRB), and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), were strong inhibitors of inosine transport, even though they have a significantly different heterocycle structure compared to a typical purine ring. As measured by GeneChip arrays, mRNA expression of hCNT2 in human duodenum was 15-fold greater than that of hCNT1 or hENT2. Further, the rCNT2 expression in rat duodenum was 20-fold higher than rCNT1, rENT1 or rENT2. This suggests that hCNT2 (and rCNT2) may have a significant role in uptake of nucleoside drugs from the intestine and is a potential transporter target for the development of nucleoside and nucleoside-mimetic drugs.
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Affiliation(s)
- Ho-Chul Shin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA
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40
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Loewen SK, Ng AML, Mohabir NN, Baldwin SA, Cass CE, Young JD. Functional characterization of a H+/nucleoside co-transporter (CaCNT) from Candida albicans, a fungal member of the concentrative nucleoside transporter (CNT) family of membrane proteins. Yeast 2003; 20:661-75. [PMID: 12794928 DOI: 10.1002/yea.1000] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human and other mammalian concentrative (Na(+)-linked) nucleoside transport proteins belong to a membrane protein family (CNT, TC 2.A.41) that also includes Escherichia coli H(+)-dependent nucleoside transport protein NupC. Here, we report the cDNA cloning and functional characterization of a CNT family member from the pathogenic yeast Candida albicans. This 608 amino acid residue H(+)/nucleoside symporter, designated CaCNT, contains 13 predicted transmembrane domains (TMs), but lacks the exofacial, glycosylated carboxyl-terminus of its mammalian counterparts. When produced in Xenopus oocytes, CaCNT exhibited transport activity for adenosine, uridine, inosine and guanosine but not cytidine, thymidine or the nucleobase hypoxanthine. Apparent K(m) values were in the range 16-64 micro M, with V(max) : K(m) ratios of 0.58-1.31. CaCNT also accepted purine and uridine analogue nucleoside drugs as permeants, including cordycepin (3'-deoxyadenosine), a nucleoside analogue with anti-fungal activity. Electrophysiological measurements under voltage clamp conditions gave a H(+) to [(14)C]uridine coupling ratio of 1 : 1. CaCNT, obtained from logarithmically growing cells, is the first described cation-coupled nucleoside transporter in yeast, and the first member of the CNT family of proteins to be characterized from a unicellular eukaryotic organism.
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Affiliation(s)
- Shaun K Loewen
- Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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41
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Cabrita MA, Baldwin SA, Young JD, Cass CE. Molecular biology and regulation of nucleoside and nucleobase transporter proteins in eukaryotes and prokaryotes. Biochem Cell Biol 2003; 80:623-38. [PMID: 12440702 DOI: 10.1139/o02-153] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The molecular cloning of cDNAs encoding nucleoside transporter proteins has greatly advanced understanding of how nucleoside permeants are translocated across cell membranes. The nucleoside transporter proteins identified thus far have been categorized into five distinct superfamilies. Two of these superfamilies, the equilibrative and concentrative nucleoside transporters, have human members and these will be examined in depth in this review. The human equilibrative nucleoside transporters translocate nucleosides and nucleobases bidirectionally down their concentration gradients and are important in the uptake of anticancer and antiviral nucleoside drugs. The human concentrative nucleoside transporters cotranslocate nucleosides and sodium unidirectionally against the nucleoside concentration gradients and play a vital role in certain tissues. The regulation of nucleoside and nucleobase transporters is being studied more intensely now that more tools are available. This review provides an overview of recent advances in the molecular biology and regulation of the nucleoside and nucleobase transporters.
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Affiliation(s)
- Miguel A Cabrita
- Department of Biochemistry, Cross Cancer Institute, University of Alberta, Edmonton, Canada
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42
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Molina-Arcas M, Bellosillo B, Casado FJ, Montserrat E, Gil J, Colomer D, Pastor-Anglada M. Fludarabine uptake mechanisms in B-cell chronic lymphocytic leukemia. Blood 2003; 101:2328-34. [PMID: 12411296 DOI: 10.1182/blood-2002-07-2236] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nucleoside derivatives are currently used in the treatment of hematologic malignancies. Although intracellular events involved in the pharmacologic action of these compounds have been extensively studied, the role of plasma membrane transporters in nucleoside-derived drug bioavailability and action in leukemia cells has not been comprehensively addressed. We have monitored the amounts of mRNA for the 5 nucleoside transporter isoforms cloned so far (CNT1, CNT2, CNT3, ENT1, and ENT2) in several human cell types and in normal human leukocytes. We then examined the expression patterns of these plasma membrane proteins in patients with chronic lymphocytic leukemia (CLL) and correlated them with in vitro fludarabine cytotoxicity. Despite a huge individual variability in the mRNA amounts for every transporter gene expressed in CLL cells (CNT2, CNT3, ENT1, and ENT2), no relationship between mRNA levels and in vitro fludarabine cytotoxicity was observed. Fludarabine accumulation in CLL cells was mostly, if not exclusively, mediated by ENT-type transporters whose biologic activity was clearly correlated with fludarabine cytotoxicity, which reveals a role of ENT-mediated uptake in drug responsiveness in patients with CLL.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adaptor Proteins, Vesicular Transport
- Adult
- Aged
- Aged, 80 and over
- Biological Transport
- Carrier Proteins/genetics
- Cell Survival/drug effects
- Drug Resistance, Neoplasm
- Equilibrative Nucleoside Transporter 1/genetics
- Female
- Gene Expression
- Humans
- Immunoglobulin G/metabolism
- Immunoglobulin G/pharmacology
- Immunoglobulin G/therapeutic use
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Leukocytes/metabolism
- Male
- Melphalan/metabolism
- Melphalan/pharmacology
- Melphalan/therapeutic use
- Membrane Transport Proteins/genetics
- Middle Aged
- RNA, Messenger/analysis
- Reverse Transcriptase Polymerase Chain Reaction
- Saccharomyces cerevisiae Proteins
- Tumor Cells, Cultured
- Vidarabine/analogs & derivatives
- Vidarabine/metabolism
- Vidarabine/pharmacology
- Vidarabine/therapeutic use
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Affiliation(s)
- Míriam Molina-Arcas
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona, Spain
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Casado FJ, Lostao MP, Aymerich I, Larráyoz IM, Duflot S, Rodríguez-Mulero S, Pastor-Anglada M. Nucleoside transporters in absorptive epithelia. J Physiol Biochem 2002; 58:207-16. [PMID: 12744303 DOI: 10.1007/bf03179858] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
There are two families of nucleoside transporters, concentrative (termed CNTs) and equilibrative (called ENTs). The members of both families mediate the transmembrane transport of natural nucleosides and some drugs whose structure is based on nucleosides. CNT transporters show a high affinity for their natural substrates (with Km values in the low micromolar range) and are substrate selective. In contrast, ENT transporters show lower affinity and are more permissive regarding the substrates they accept. Both types of transporters are tightly regulated in all cell types studied so far, both by endocrine and growth factors and by substrate availability. The degree of cell differentiation and the proliferation status of a cell also affect the pattern of expressed transporters. Although the presence of both types of transporters in the cells of absortive epithelia suggested the possibility of a transepithelial flux of nucleosides, their exact localization in the different plasma membrane domains of epithelial cells had not been demonstrated until recently. Concentrative transporters are found in the apical membrane while equlibrative transporters are located in the basolateral membrane, thus strengthening the hypothesis of a transepithelial flux of nucleosides.
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Affiliation(s)
- F J Casado
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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