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Pandya AN, Baraiya AB, Jalani HB, Pandya D, Kaila JC, Kachler S, Salmaso V, Moro S, Klotz KN, Vasu KK. Discovery of 2-aminoimidazole and 2-amino imidazolyl-thiazoles as non-xanthine human adenosine A 3 receptor antagonists: SAR and molecular modeling studies. MEDCHEMCOMM 2018; 9:676-684. [PMID: 30108958 DOI: 10.1039/c7md00643h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/27/2018] [Indexed: 01/07/2023]
Abstract
A small-molecule combinatorial library of 24 compounds with 2-aminoimidazole and 2-aminoimidazolyl-thiazole derivatives was synthesized using a 2-chloro trityl resin. The generated compound library was tested against all the human adenosine receptors subtypes. The 2-aminoimidazole derivatives (6a-6l) showed weak to moderate affinity towards the human adenosine receptors. Further modification to 2-aminoimidazolyl-thiazole derivatives (12a-12l) resulted in an improvement of affinity at adenosine A1, A2A and A3 receptor subtypes. Compound 12b was the most potent and selective non-xanthine human adenosine A3 receptor antagonist of this series. A receptor-based modeling study was performed to explore the possible binding mode of these novel 2-aminoimidazole and 2-aminoimidazolyl-thiazole derivatives into human adenosine A1, A2A and A3 receptor subtypes.
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Affiliation(s)
- Amit N Pandya
- Department of Medicinal Chemistry , B. V. Patel Pharmaceutical Education and Research Development (PERD) Centre , Sarkej-Gandhinagar Highway, Thaltej , Ahmedabad 380e054 , Gujarat , India . ;
| | - Arshi B Baraiya
- Department of Medicinal Chemistry , B. V. Patel Pharmaceutical Education and Research Development (PERD) Centre , Sarkej-Gandhinagar Highway, Thaltej , Ahmedabad 380e054 , Gujarat , India . ;
| | - Hitesh B Jalani
- Department of Medicinal Chemistry , B. V. Patel Pharmaceutical Education and Research Development (PERD) Centre , Sarkej-Gandhinagar Highway, Thaltej , Ahmedabad 380e054 , Gujarat , India . ;
| | - Dhaivat Pandya
- Department of Medicinal Chemistry , B. V. Patel Pharmaceutical Education and Research Development (PERD) Centre , Sarkej-Gandhinagar Highway, Thaltej , Ahmedabad 380e054 , Gujarat , India . ;
| | - Jitendra C Kaila
- Department of Medicinal Chemistry , B. V. Patel Pharmaceutical Education and Research Development (PERD) Centre , Sarkej-Gandhinagar Highway, Thaltej , Ahmedabad 380e054 , Gujarat , India . ;
| | - Sonja Kachler
- Institut für Pharmakologie und Toxikologie , Julius-Maximilians-Universität Würzburg , Germany
| | - Veronica Salmaso
- Molecular Modeling Section (MMS) , Dipartimento di Scienze Farmaceutiche , Università degli Studi di Padova , via Marzolo 5 , 35131 Padova , Italy
| | - Stefano Moro
- Molecular Modeling Section (MMS) , Dipartimento di Scienze Farmaceutiche , Università degli Studi di Padova , via Marzolo 5 , 35131 Padova , Italy
| | - Karl-Norbert Klotz
- Institut für Pharmakologie und Toxikologie , Julius-Maximilians-Universität Würzburg , Germany
| | - Kamala K Vasu
- Department of Medicinal Chemistry , B. V. Patel Pharmaceutical Education and Research Development (PERD) Centre , Sarkej-Gandhinagar Highway, Thaltej , Ahmedabad 380e054 , Gujarat , India . ;
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Kazemi MH, Raoofi Mohseni S, Hojjat-Farsangi M, Anvari E, Ghalamfarsa G, Mohammadi H, Jadidi-Niaragh F. Adenosine and adenosine receptors in the immunopathogenesis and treatment of cancer. J Cell Physiol 2017; 233:2032-2057. [DOI: 10.1002/jcp.25873] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 02/21/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Mohammad H. Kazemi
- Student Research Committee, Department of Immunology, School of Medicine; Iran University of Medical Sciences (IUMS); Tehran Iran
- Immunology Research Center; Tabriz University of Medical Sciences; Tabriz Iran
| | - Sahar Raoofi Mohseni
- Department of Immunology, School of Public Health; Tehran University of Medical Sciences; Tehran Iran
| | - Mohammad Hojjat-Farsangi
- Department of Oncology-Pathology, Immune and Gene Therapy Lab, Cancer Center Karolinska (CCK); Karolinska University Hospital Solna and Karolinska Institute; Stockholm Sweden
- Department of Immunology, School of Medicine; Bushehr University of Medical Sciences; Bushehr Iran
| | - Enayat Anvari
- Faculty of Medicine, Department of Physiology; Ilam University of Medical Sciences; Ilam Iran
| | - Ghasem Ghalamfarsa
- Medicinal Plants Research Center; Yasuj University of Medical Sciences; Yasuj Iran
| | - Hamed Mohammadi
- Immunology Research Center; Tabriz University of Medical Sciences; Tabriz Iran
- Faculty of Medicine, Department of Immunology; Tabriz University of Medical Sciences; Tabriz Iran
| | - Farhad Jadidi-Niaragh
- Immunology Research Center; Tabriz University of Medical Sciences; Tabriz Iran
- Department of Immunology, School of Public Health; Tehran University of Medical Sciences; Tehran Iran
- Faculty of Medicine, Department of Immunology; Tabriz University of Medical Sciences; Tabriz Iran
- Drug Applied Research Center; Tabriz University of Medical Sciences; Tabriz Iran
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3
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Fan W, Li YR, Jiang B, Li G. Cascade bicyclization of triethylammonium thiolates with hydrazines: efficient access to pyrazolo[3,4-c]quinolines. Org Biomol Chem 2016; 14:9080-9087. [PMID: 27722433 PMCID: PMC5113139 DOI: 10.1039/c6ob01728b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A new bicyclization strategy has been established, allowing a flexible and practical approach to 33 examples of pyrazolo[3,4-c]quinolines from low-cost and readily accessible triethylammonium thiolates with hydrazines. Notably, the features of this work include broad functional group compatibility, mild reaction conditions and good reaction yields.
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Affiliation(s)
- Wei Fan
- Institute of Chemistry & BioMedical Sciences, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing, 210093, P. R. China.
| | - Yan-Rong Li
- Institute of Chemistry & BioMedical Sciences, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing, 210093, P. R. China.
| | - Bo Jiang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA and School of Chemistry and Chemical Engineering, Jiangsu Normal University, Xuzhou 221116, P. R. China.
| | - Guigen Li
- Institute of Chemistry & BioMedical Sciences, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing University, Nanjing, 210093, P. R. China. and Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA
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Odagaki Y, Kinoshita M, Ota T, Javier Meana J, Callado LF, García-Sevilla JA. Adenosine A1( )receptors are selectively coupled to Gα(i-3) in postmortem human brain cortex: Guanosine-5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) binding/immunoprecipitation study. Eur J Pharmacol 2015. [PMID: 26213104 DOI: 10.1016/j.ejphar.2015.07.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
By means of guanosine-5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) binding assay combined with immunoprecipitation using anti-Gα subunit antibody, we recently reported 5-HT2A receptor- and M1 muscarinic acetylcholine receptor-mediated Gαq activation in rat cerebral cortical membranes (Odagaki et al., 2014). In the present study, this method has been applied to postmortem human brains, with focusing on adenosine receptor-mediated G-protein activation. In the exploratory experiments using a series of agonists and the antibodies specific to each Gα subtypes in the presence of low (10 nM) or high (50 μM) concentration of GDP, the most prominent increases in specific [(35)S]GTPγS binding in the membranes prepared from human prefrontal cortex were obtained for the combinations of adenosine (1mM)/anti-Gαi-3 in the presence of 50 μM GDP as well as 5-HT (100 μM)/anti-Gαq and carbachol (1mM)/anti-Gαq in the presence of 10nM GDP. Adenosine-induced activation of Gαi-3 emerged only when GDP concentrations were increased higher than 10 μM, and the following experiments were performed in the presence of 300 μM GDP. Adenosine increased specific [(35)S]GTPγS binding to Gαi-3 in a concentration-dependent manner to 251.4% of the basal unstimulated binding, with an EC50 of 1.77 μM. The involvement of adenosine A1 receptor was verified by the experiments using selective agonists and antagonists at adenosine A1 or A3 receptor. Among the α subunits of Gi/o class (Gαi-1, Gαi-2, Gαi-3, and Gαo.), only Gαi-3 was activated by 1mM adenosine, indicating that human brain adenosine A1 receptor is coupled preferentially, if not exclusively, to Gαi-3.
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Affiliation(s)
- Yuji Odagaki
- Department of Psychiatry, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Iruma-gun, Moroyama-machi, Saitama 350-0495, Japan.
| | - Masakazu Kinoshita
- Department of Psychiatry, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Iruma-gun, Moroyama-machi, Saitama 350-0495, Japan
| | - Toshio Ota
- Department of Psychiatry, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Iruma-gun, Moroyama-machi, Saitama 350-0495, Japan
| | - J Javier Meana
- Department of Pharmacology, University of the Basque Country, UPV/EHU, E-48940 Leioa, Bizkaia, and Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain
| | - Luis F Callado
- Department of Pharmacology, University of the Basque Country, UPV/EHU, E-48940 Leioa, Bizkaia, and Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain
| | - Jesús A García-Sevilla
- Laboratory of Neuropharmacology, IUNICS/IdISPa, University of the Balearic Islands (UIB), and Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), Spain
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Adenosine-A3 receptors in neutrophil microdomains promote the formation of bacteria-tethering cytonemes. EMBO Rep 2013; 14:726-32. [PMID: 23817552 PMCID: PMC3736131 DOI: 10.1038/embor.2013.89] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 06/04/2013] [Accepted: 06/06/2013] [Indexed: 01/09/2023] Open
Abstract
These study shows that A3ARs aggregate in polarized immunomodulatory microdomains on human neutrophils and induce filipodia-like projections that tether and 'reel-in' pathogens, increasing phagocytic efficiency. The A3-adenosine receptor (A3AR) has recently emerged as a key regulator of neutrophil behaviour. Using a fluorescent A3AR ligand, we show that A3ARs aggregate in highly polarized immunomodulatory microdomains on human neutrophil membranes. In addition to regulating chemotaxis, A3ARs promote the formation of filipodia-like projections (cytonemes) that can extend up to 100 μm to tether and ‘reel in' pathogens. Exposure to bacteria or an A3AR agonist stimulates the formation of these projections and bacterial phagocytosis, whereas an A3AR-selective antagonist inhibits cytoneme formation. Our results shed new light on the behaviour of neutrophils and identify the A3AR as a potential target for modulating their function.
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Padovan M, Vincenzi F, Govoni M, Bortoluzzi A, Borea PA, Varani K. Adenosine and adenosine receptors in rheumatoid arthritis. ACTA ACUST UNITED AC 2013. [DOI: 10.2217/ijr.12.76] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Xu Z, Cheng F, Li J, Zhou Y, Su N, Li W, Liu G, Tang Y. Comparative pharmacophore modeling of human adenosine receptor A1 and A3 antagonists. Sci China Chem 2012. [DOI: 10.1007/s11426-012-4606-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Baraldi PG, Saponaro G, Romagnoli R, Aghazadeh Tabrizi M, Baraldi S, Moorman AR, Cosconati S, Di Maro S, Marinelli L, Gessi S, Merighi S, Varani K, Borea PA, Preti D. Water-soluble pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidines as human A₃ adenosine receptor antagonists. J Med Chem 2012; 55:5380-90. [PMID: 22568637 DOI: 10.1021/jm300323t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A relevant problem of the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine nucleus, an attractive scaffold for the preparation of adenosine receptor antagonists, is the low water solubility. We originally functionalized the C(5) position with a salifiable 4-pyridylcarbamoyl moiety that conferred good water solubility at low pH (<4.0) but poor solubility at physiologic pH, indicative of the dissociation of the pyridinium species. Here we replaced the pyridin-4-yl moiety with a 1-(substituted)piperidin-4-yl ring to exploit the higher basicity of this nucleus and for the the possibility to generate stable, water-soluble salts. The hydrochloride salt of the 1-(cyclohexylmethyl)piperidin-4-yl derivative (10, K(i)(hA(3)) = 9.7 nM, IC(50)(hA(3)) = 30 nM, K(i)(hA(1)/hA(3)) = 351, K(i)(hA(2A)/hA(3)) > 515, IC(50)(hA(2B)) > 5 μM) showed a solubility of 8 mg/mL at physiological pH and gave a stable aqueous system suitable for intravenous infusion. Molecular modeling studies were helpful in rationalizing the available structure-activity relationships and the selectivity profile of the new ligands.
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Baraldi PG, Preti D, Borea PA, Varani K. Medicinal Chemistry of A3 Adenosine Receptor Modulators: Pharmacological Activities and Therapeutic Implications. J Med Chem 2012; 55:5676-703. [DOI: 10.1021/jm300087j] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Pier Giovanni Baraldi
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
| | - Delia Preti
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
| | - Pier Andrea Borea
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
| | - Katia Varani
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
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Baraldi PG, Saponaro G, Aghazadeh Tabrizi M, Baraldi S, Romagnoli R, Moorman AR, Varani K, Borea PA, Preti D. Pyrrolo- and pyrazolo-[3,4-e][1,2,4]triazolo[1,5-c]pyrimidines as adenosine receptor antagonists. Bioorg Med Chem 2011; 20:1046-59. [PMID: 22204739 DOI: 10.1016/j.bmc.2011.11.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/17/2011] [Accepted: 11/18/2011] [Indexed: 01/11/2023]
Abstract
The discovery and development of adenosine receptor antagonists have represented for years an attractive field of research from the perspective of identifying new drugs for the treatment of widespread disorders such as inflammation, asthma and Parkinson's disease. The present work can be considered as an extension of our structure-activity relationship studies on the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine (PTP) nucleus, extensively investigated by us as a useful template, in particular, for the identification of A(2A) and A(3) adenosine receptor antagonists. In order to explore the role of the nitrogen at the 7-position, we performed a new synthetic strategy for the preparation of pyrrolo[3,4-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives which can be considered as 7-deaza analogues of the parent PTPs. We also synthesised a novel series of pyrazolo[3,4-e][1,2,4]triazolo[1,5-c]pyrimidines as junction isomers of the reference compounds. In both cases we obtained some examples of potent antagonists (K(i) in the low nanomolar range) with variable selectivity profiles in relation to the nature of substituents introduced at the C(5)-, N(8)- and/or N(9)-positions. The pyrrolo-triazolo-pyrimidine derivative 9b appeared to be a potent A(3) adenosine receptor antagonist (K(i)=10 nM) with good selectivity over hA(1) (74-fold) and hA(2A) (20-fold) adenosine receptors combined with low activity at the hA(2B) subtype (IC(50)=906 nM). Moreover, some examples of high-affinity A(1)/A(2A) dual antagonists have been identified in both series. This work constitutes a new and important contribution for the comprehension of the interaction between PTPs and adenosine receptors.
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Gessi S, Merighi S, Fazzi D, Stefanelli A, Varani K, Borea PA. Adenosine receptor targeting in health and disease. Expert Opin Investig Drugs 2011; 20:1591-609. [PMID: 22017198 DOI: 10.1517/13543784.2011.627853] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION The adenosine receptors A(1), A(2A), A(2B) and A(3) are important and ubiquitous mediators of cellular signaling that play vital roles in protecting tissues and organs from damage. In particular, adenosine triggers tissue protection and repair by different receptor-mediated mechanisms, including increasing the oxygen supply:demand ratio, pre-conditioning, anti-inflammatory effects and the stimulation of angiogenesis. AREAS COVERED The state of the art of the role of adenosine receptors which have been proposed as targets for drug design and discovery, in health and disease, and an overview of the ligands for these receptors in clinical development. EXPERT OPINION Selective ligands of A(1), A(2A), A(2B) and A(3) adenosine receptors are likely to find applications in the treatment of pain, ischemic conditions, glaucoma, asthma, arthritis, cancer and other disorders in which inflammation is a feature. The aim of this review is to provide an overview of the present knowledge regarding the role of these adenosine receptors in health and disease.
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Affiliation(s)
- Stefania Gessi
- University of Ferrara, Department of Clinical and Experimental Medicine, Pharmacology Section, 44100 Ferrara, Italy
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Gessi S, Merighi S, Varani K, Borea PA. Adenosine receptors in health and disease. ADVANCES IN PHARMACOLOGY 2011; 61:41-75. [PMID: 21586355 DOI: 10.1016/b978-0-12-385526-8.00002-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The adenosine receptors A(1), A(2A), A(2B), and A(3) are important and ubiquitous mediators of cellular signaling, which play vital roles in protecting tissues and organs from damage. In particular, adenosine triggers tissue protection and repair by different receptor-mediated mechanisms, including an increase of oxygen supply/demand ratio, preconditioning, anti-inflammatory effects, and stimulation of angiogenesis. Considerable advances have been recently achieved in the pharmacological and molecular characterization of adenosine receptors, which have been proposed as targets for drug design and discovery. At the present time, it can be speculated that adenosine A(1), A(2A), A(2B), and A(3) receptor-selective ligands may show utility in the treatment of pain, ischemic conditions, glaucoma, asthma, arthritis, cancer, and other disorders in which inflammation is a feature. This chapter documents the present state of knowledge of adenosine receptors' role in health and disease.
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Affiliation(s)
- Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Section, University of Ferrara, Italy
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Riyadh SM, Farghaly TA, Gomha SM. Novel polyazaheterocyclic systems: Synthesis, antitumor, and antimicrobial activities. Arch Pharm Res 2010; 33:1721-8. [PMID: 21116773 DOI: 10.1007/s12272-010-1102-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 05/16/2010] [Accepted: 05/16/2010] [Indexed: 11/29/2022]
Abstract
A series of new polyazaheterocyclic ring systems was synthesized via the reaction of enaminone 5 with active methylene compounds, hydrazine hydrate, hydroxylamine, and heterocyclic amines. The structures of the newly synthesized compounds were substantiated on the basis of spectral data and elemental analyses. The antitumor activity of the enaminone 5 against the human breast cell line MCF-7, the liver carcinoma cell line HEPG2-1, and HELA cells was determined. In addition, the antimicrobial activity of some selected products was evaluated.
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Affiliation(s)
- Sayed M Riyadh
- Department of Chemistry, University of Cairo, Giza, Egypt
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Synthesis and pharmacological evaluation of novel substituted 9-deazaxanthines as A2B receptor antagonists. Eur J Med Chem 2010; 45:2884-92. [DOI: 10.1016/j.ejmech.2010.03.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/05/2010] [Accepted: 03/09/2010] [Indexed: 11/18/2022]
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Courjaret R, Tröger M, Deitmer JW. Suppression of GABA input by A1 adenosine receptor activation in rat cerebellar granule cells. Neuroscience 2009; 162:946-58. [PMID: 19477241 DOI: 10.1016/j.neuroscience.2009.05.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 05/07/2009] [Accepted: 05/21/2009] [Indexed: 12/01/2022]
Abstract
Synaptic transmission has been shown to be modulated by purinergic receptors. In the cerebellum, spontaneous inhibitory input to Purkinje neurons is enhanced by ATP via P2 receptors, while evoked excitatory input via the granule cell parallel fibers is reduced by presynaptic P1 (A1) adenosine receptors. We have now studied the modulation of the complex GABAergic input to granule cells by the purinergic receptor agonists ATP and adenosine in acute rat cerebellar tissue slices using the whole-cell patch-clamp technique. Our experiments indicate that ATP and adenosine substantially reduce the bicuculline- and gabazine-sensitive GABAergic input to granule cells. Both phasic and tonic inhibitory components were reduced leading to an increased excitability of granule cells. The effect of ATP and adenosine could be blocked by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), but not by other P1 and P2 receptor antagonists, indicating that it was mediated by activation of A1 adenosine receptors. Our results suggest that, in the cerebellar network, A1 receptor activation, known to decrease the excitatory output of granule cells, also increases their excitability by reducing their complex GABAergic input. These findings extend our knowledge on purinergic receptors, mediating multiple modulations at both inhibitory and excitatory input and output sites in the cerebellar network.
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Affiliation(s)
- R Courjaret
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Universität Kaiserslautern, Postfach 3049, Erwin-Schrödinger-strasse 13, D-67653, Kaiserslautern, Germany.
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Fornai M, Antonioli L, Colucci R, Ghisu N, Buccianti P, Marioni A, Chiarugi M, Tuccori M, Blandizzi C, Del Tacca M. A1 and A2a receptors mediate inhibitory effects of adenosine on the motor activity of human colon. Neurogastroenterol Motil 2009; 21:451-66. [PMID: 19019012 DOI: 10.1111/j.1365-2982.2008.01213.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Experimental evidence in animal models suggests that adenosine is involved in the regulation of digestive functions. This study examines the influence of adenosine on the contractile activity of human colon. Reverse transcription-polymerase chain reaction revealed A(1) and A(2a) receptor expression in colonic neuromuscular layers. Circular muscle preparations were connected to isotonic transducers to determine the effects of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; A(1) receptor antagonist), ZM 241385 (A(2a) receptor antagonist), CCPA (A(1) receptor agonist) and 2-[(p-2-carboxyethyl)-phenethylamino]-5'-N-ethyl-carboxamide-adenosine (CGS 21680; A(2a) receptor agonist) on motor responses evoked by electrical stimulation or carbachol. Electrically evoked contractions were enhanced by DPCPX and ZM 241385, and reduced by CCPA and CGS 21680. Similar effects were observed when colonic preparations were incubated with guanethidine (noradrenergic blocker), L-732,138, GR-159897 and SB-218795 (NK receptor antagonists). However, in the presence of guanethidine, NK receptor antagonists and N(omega)-propyl-L-arginine (NPA; neuronal nitric oxide synthase inhibitor), the effects of DPCPX and CCPA were still evident, while those of ZM 241385 and CGS 21680 no longer occurred. Carbachol-induced contractions were unaffected by A(2a) receptor ligands, but they were enhanced or reduced by DPCPX and CCPA, respectively. When colonic preparations were incubated with guanethidine, NK antagonists and atropine, electrically induced relaxations were partly reduced by ZM 241385 or NPA, but unaffected by DPCPX. Dipyridamole or application of exogenous adenosine reduced electrically and carbachol-evoked contractions, whereas adenosine deaminase enhanced such motor responses. In conclusion, adenosine exerts an inhibitory control on human colonic motility. A(1) receptors mediate direct modulating actions on smooth muscle, whereas A(2a) receptors operate through inhibitory nitrergic nerve pathways.
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Affiliation(s)
- M Fornai
- Division of Pharmacology and Chemotherapy, Department of Internal Medicine, University of Pisa, Pisa, Italy
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Baraldi PG, Tabrizi MA, Gessi S, Borea PA. Adenosine Receptor Antagonists: Translating Medicinal Chemistry and Pharmacology into Clinical Utility. Chem Rev 2008; 108:238-63. [DOI: 10.1021/cr0682195] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Pier Giovanni Baraldi
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
| | - Mojgan Aghazadeh Tabrizi
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
| | - Stefania Gessi
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
| | - Pier Andrea Borea
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
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Gessi S, Merighi S, Varani K, Cattabriga E, Benini A, Mirandola P, Leung E, Mac Lennan S, Feo C, Baraldi S, Borea PA. Adenosine receptors in colon carcinoma tissues and colon tumoral cell lines: focus on the A(3) adenosine subtype. J Cell Physiol 2007; 211:826-36. [PMID: 17348028 DOI: 10.1002/jcp.20994] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Adenosine may affect several pathophysiological processes, including cellular proliferation, through interaction with A(1), A(2A), A(2B), and A(3) receptors. In this study we characterized adenosine receptors in human colon cancer tissues and in colon cancer cell lines Caco2, DLD1, HT29. mRNA of all adenosine subtypes was detected in cancer tissues and cell lines. At a protein levels low amount of A(1), A(2A), and A(2B) receptors were detected, whilst the A(3) was the most abundant subtype in both cancer tissues and cells, with a pharmacological profile typical of the A(3) subtype. All the receptors were coupled to stimulation/inhibition of adenylyl-cyclase in cancer cells, with the exception of A(1) subtype. Adenosine increased cell proliferation with an EC(50) of 3-12 microM in cancer cells. This effect was not essentially reduced by adenosine receptor antagonists. However dypiridamol, an adenosine transport inhibitor, increased the stimulatory effect induced by adenosine, suggesting an action at the cell surface. Addition of adenosine deaminase makes the A(3) agonist 2-chloro-N6-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (Cl-IB-MECA) able to stimulate cell proliferation with an EC(50) of 0.5-0.9 nM in cancer cells, suggesting a tonic proliferative effect induced by endogenous adenosine. This effect was antagonized by 5-N-(4-methoxyphenyl-carbamoyl)amino-8-propyl-2(2furyl)-pyrazolo-[4,3e]-1,2,4-triazolo [1,5-c] pyrimidine (MRE 3008F20) 10 nM. Cl-IB-MECA-stimulated cell proliferation involved extracellular-signal-regulated-kinases (ERK1/2) pathway, as demonstrated by reduction of proliferation with 1,4-diamino-2,3-dicyano-1,4-bis-[2-amino-phenylthio]-butadiene (U0126) and by ERK1/2 phosphorylation. In conclusion this study indicates for the first time that in colon cancer cell lines endogenous adenosine, through the interaction with A(3) receptors, mediates a tonic proliferative effect.
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Affiliation(s)
- Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, Ferrara, Italy
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Yates L, Clark JH, Martin TJ, James S, Broadley KJ, Kidd EJ. Radioligand binding and functional responses of ligands for human recombinant adenosine A(3) receptors. ACTA ACUST UNITED AC 2006; 26:191-200. [PMID: 16553647 DOI: 10.1111/j.1474-8673.2006.00372.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The binding and functional properties of adenosine receptor ligands were compared in Chinese hamster ovary cells transfected with human adenosine A(3) receptors. Inhibition of [(125)I]-aminobenzyl-5'-N-methylcarboamidoadenosine ([(125)I]-AB-MECA) binding by adenosine receptor ligands was examined in membrane preparations. Inhibition of forskolin-induced cAMP accumulation by agonists was measured using a cAMP enzyme immunoassay. The rank order of agonist potency for both assays was N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) > 5'-N-ethylcarboxamidoadenosine (NECA) > (-)-N(6)-[(R)-phenylisopropyl] adenosine (R-PIA) > 4-aminobenzyl-5'-N-methylcarboxamidoadenosine (AB-MECA) > N(6)-cyclopentyl adenosine (CPA) > adenosine. The radioligand binding rank order of antagonist potency was N-[9-chloro-2-(2-furanyl)[1,2,4]-triazolo[1,5-c]quinazolin-5-benzeneacetamide (MRS1220) > 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) > 8-phenyltheophylline (8-PT) > 8-(p-sulfophenyl)-theophylline (8-SPT). MRS1220 competitively inhibited the effect of IB-MECA on cAMP production, with a K(B) value of 0.35 nm. These data are characteristic of adenosine A(3) receptors. The absence of Mg(2+) and presence of guanosine 5'-(gamma-thio)triphosphate (GTPgammaS) significantly reduced agonist binding inhibition potency, indicating binding to high- and low-affinity states. The IB-MECA, NECA and R-PIA IC(50) values were greater for the cAMP assay than for radioligand binding, suggesting an efficient stimulus-response transduction pathway.
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Affiliation(s)
- L Yates
- Division of Pharmacology, Welsh School of Pharmacy, Cardiff University, King Edward VII Avenue, Cardiff CF10 3XF, UK
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Duggineni S, Sawant D, Saha B, Kundu B. Application of modified Pictet–Spengler reaction for the synthesis of thiazolo- and pyrazolo-quinolines. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.01.063] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Carotti A, Cadavid MI, Centeno NB, Esteve C, Loza MI, Martinez A, Nieto R, Raviña E, Sanz F, Segarra V, Sotelo E, Stefanachi A, Vidal B. Design, synthesis, and structure-activity relationships of 1-,3-,8-, and 9-substituted-9-deazaxanthines at the human A2B adenosine receptor. J Med Chem 2006; 49:282-99. [PMID: 16392813 DOI: 10.1021/jm0506221] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Over two hundred 1-, 3-, 8-, and 9-substituted-9-deazaxanthines were prepared and evaluated for their binding affinity at the recombinant human adenosine receptors, in particular at the hA(2B) and hA(2A) subtypes. Several ligands endowed with sub-micromolar to low nanomolar binding affinity at hA(2B) receptors, good selectivity over hA(2A) and hA(3), but a relatively poor selectivity over hA(1) were obtained. Good antagonistic potencies and efficacies, with pA(2) values close to the corresponding pK(i)s, were observed in functional assays in vitro performed on a selected series of compounds. 1,3-Dimethyl-8-phenoxy-(N-p-halogenophenyl)-acetamido-9-deazaxanthine derivatives appeared as the most interesting leads, some of them showing outstanding hA(2B) affinities, high selectivity over hA(2A) and hA(3), but low selectivity over hA(1). Structure-affinity relationships suggested that the binding potency at the hA(2B) receptor was mainly modulated by the steric (lipophilic) properties of the substituents at positions 1 and 3 and by the electronic and lipophilic characteristics of the substituents at position 8. A comparison among affinity and selectivity profiles of 9-deazaxanthines with the corresponding xanthines suggested some possible differences in their binding mode.
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Affiliation(s)
- Angelo Carotti
- Dipartimento Farmaco-chimico, Università di Bari, via Orabona 4, I-70125 Bari, Italy.
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New heterocyclic ligands for the adenosine receptors P1 and for the ATP receptors P2. ACTA ACUST UNITED AC 2005; 60:185-202. [PMID: 15784237 DOI: 10.1016/j.farmac.2004.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 07/08/2004] [Accepted: 09/15/2004] [Indexed: 11/26/2022]
Abstract
Extracellular adenosine and adenine nucleotides induce various cellular responses through activation of P1 and P2 receptors. P1 receptors preferentially recognize adenosine and four different G protein-coupled receptors (A(1), A(2A), A(2B), and A(3) subtypes) have been identified. On the other hand, P2 receptors are activated by adenine and/or uridine nucleotides and classified into two families: ionotropic P2X and G protein-coupled P2Y receptors. In this article, we summarize our studies which led to development of new potent and selective heterocyclic ligands for the adenosine receptors P1 and for the ATP receptors P2X(7).
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Baraldi PG, Preti D, Tabrizi MA, Fruttarolo F, Romagnoli R, Zaid NA, Moorman AR, Merighi S, Varani K, Borea PA. New pyrrolo[2,1-f]purine-2,4-dione and imidazo[2,1-f]purine-2,4-dione derivatives as potent and selective human A3 adenosine receptor antagonists. J Med Chem 2005; 48:4697-701. [PMID: 16000006 DOI: 10.1021/jm058008c] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Compounds presenting an additional fused ring on the xanthine nucleus have been reported to exhibit antagonistic activity with various levels of affinity and selectivity toward the four adenosine receptors subtypes A(1), A(2A), A(2B), and A(3). This paper reports synthesis and biological evaluation of new 1-benzyl-3-propyl-1H,6H-pyrrolo[2,1-f]purine-2,4-diones and 1-benzyl-3-propyl-1H,8H-imidazo[2,1-f]purine-2,4-diones, among which we identified potent and selective A(3) adenosine receptors antagonists. In particular, 1-benzyl-7-methyl-3-propyl-1H,8H-imidazo[2,1-f]purine-2,4-dione (11e) shows a K(i) (hA(3)) value from binding assay of 0.8 nM.
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Carotti A, Stefanachi A, Raviña E, Sotelo E, Loza MI, Cadavid MI, Centeno NB, Nicolotti O. 8-Substituted-9-deazaxanthines as adenosine receptor ligands: design, synthesis and structure-affinity relationships at A2B. Eur J Med Chem 2004; 39:879-87. [PMID: 15464622 DOI: 10.1016/j.ejmech.2004.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 06/24/2004] [Accepted: 07/07/2004] [Indexed: 10/26/2022]
Abstract
A number of 8-substituted-9-deazaxanthine derivatives (1,3-dialkyl-6-substituted-1H-pyrrolo[3,2-d]pyrimidine-2,4(3H,5H)-diones) were prepared and tested for their antagonistic activity at the recombinant human adenosine receptors, in particular at the A(2B) and A(2A) receptor subtypes. Compounds endowed with micromolar to nanomolar binding affinities, but with poor A(2B)/A(2A) selectivity, were obtained. Preliminary quantitative structure-affinity relationships suggested that the binding potency at the A(2B) receptor is mainly modulated by the electronic and lipophilic properties of the ligands.
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Affiliation(s)
- Angelo Carotti
- Dipartimento Farmacochimico, Università di Bari, via Orabona 4, 70125 Bari, Italy.
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Baraldi PG, Tabrizi MA, Preti D, Bovero A, Fruttarolo F, Romagnoli R, Moorman AR, Gessi S, Merighi S, Varani K, Borea PA. [3H]-MRE 2029-F20, a selective antagonist radioligand for the human A2B adenosine receptors. Bioorg Med Chem Lett 2004; 14:3607-10. [PMID: 15177484 DOI: 10.1016/j.bmcl.2004.03.084] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 03/19/2004] [Accepted: 03/29/2004] [Indexed: 11/29/2022]
Abstract
MRE 2029-F20 [N-benzo[1,3]dioxol-5-yl-2-[5-(2,6-dioxo-1,3-dipropyl-2,3,6,7-tetrahydro-1H-purin-8-yl)-1-methyl-1H-pyrazol-3-yloxy]-acetamide] is a selective antagonist ligand of A2B adenosine receptors. For use as a radioligand, 1,3-diallyl-xanthine, the precursor of [3H]-MRE 2029-F20, was synthesized, and tritiated on the allyl groups. [3H]-MRE 2029-F20 bound to human A2B receptors expressed in CHO cells showed a KD value of 1.65+/-0.10 nM and Bmax value of 36+/-4 fmol/mg protein. [3H]-MRE2029-F20 represents a useful tool for the pharmacological characterization of human A2B adenosine receptor subtype.
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Okamura T, Kurogi Y, Hashimoto K, Nishikawa H, Nagao Y. Facile synthesis of fused 1,2,4-triazolo[1,5-c]pyrimidine derivatives as human adenosine A3 receptor ligands. Bioorg Med Chem Lett 2004; 14:2443-6. [PMID: 15109629 DOI: 10.1016/j.bmcl.2004.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Revised: 03/03/2004] [Accepted: 03/04/2004] [Indexed: 10/26/2022]
Abstract
A facile synthetic method for fused triazolopyrimidine derivatives having high affinity and selectivity for human adenosine A(3) receptors is reported. The fused triazolopyrimidine derivatives were easily prepared by one-pot reaction using acylhydrazines and imidates prepared from amine derivatives bearing cyano group and orthoesters in situ. This synthetic method was useful in finding new tricyclic adenosine A(3) receptor antagonists and also in diversifying the substituents at two positions on the fused triazolopyrimidine ring.
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Affiliation(s)
- Takashi Okamura
- Pharmaceutical Technology Institute, Otsuka Pharmaceutical Factory, Inc. Tateiwa, Muya-cho, Naruto, Tokushima 772-8601, Japan.
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Gessi S, Varani K, Merighi S, Cattabriga E, Avitabile A, Gavioli R, Fortini C, Leung E, Mac Lennan S, Borea PA. Expression of A3 adenosine receptors in human lymphocytes: up-regulation in T cell activation. Mol Pharmacol 2004; 65:711-9. [PMID: 14978250 DOI: 10.1124/mol.65.3.711] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study investigates mRNA and protein levels of A3 adenosine receptors in resting (R) and activated (A) human lymphocytes. The receptors were evaluated by the antagonist radioligand [3H]5-N-(4-methoxyphenyl-carbamoyl)amino-8-propyl-2(2furyl)-pyrazolo-[4,3e]-1,2,4-triazolo-[1,5-c]-pyrimidine ([3H]MRE 3008F20), which yielded Bmax values of 125 +/- 15 and 225 +/- 23 fmol/mg of protein and KD values of 1.79 +/- 0.30 and 1.85 +/- 0.25 nM in R and A cells, respectively. The protein seems to be induced with remarkable rapidity starting at 15 min and reaches a plateau at 30 min. Western blot assays revealed that the up-regulation of the A3 subtype after lymphocyte activation was caused by an increase in an enriched CD4+ cell fraction. Real-time reverse transcription-polymerase chain reaction experiments confirmed the rapid increase of A3 mRNA after T cell activation. Competition of radioligand binding by adenosine ligands displayed a rank order of potency typical of the A3 subtype. Thermodynamic data indicated that the binding is enthalpy- and entropy-driven in both R and A cells, suggesting that the activation process does not involve, at a molecular level, receptor alterations leading to modifications in the A3-related binding mechanisms. Functionally, the up-regulation of A3 adenosine receptors in A versus R cells corresponded to a potency increase of the A3 agonist N6-(3-iodo-benzyl)-2-chloro-adenosine-5'-N-methyluronamide in inhibiting cAMP accumulation (IC50=1.5 +/- 0.4 and 2.7 +/- 0.3 nM, respectively); this effect was antagonized by MRE 3008F20 (IC50=5.0 +/- 0.3 nM). In conclusion, our results provide, for the first time, an in-depth investigation of A3 receptors in human lymphocytes and demonstrate that, under activating conditions, they are up-regulated and may contribute to the effects triggered by adenosine.
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Affiliation(s)
- Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
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Morrone FB, Jacques-Silva MC, Horn AP, Bernardi A, Schwartsmann G, Rodnight R, Lenz G. Extracellular nucleotides and nucleosides induce proliferation and increase nucleoside transport in human glioma cell lines. J Neurooncol 2003; 64:211-8. [PMID: 14558596 DOI: 10.1023/a:1025699932270] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Extracellular purines (adenosine triphosphate (ATP), adenosine 5'-diphosphate (ADP) and adenosine) and pyrimidines (uridine 5'-triphosphate (UTP) and UDP) are important signaling molecules that mediate diverse biological effects via P1 and P2 purinergic receptors. The human glioma cell lines U87 MG, U251 MG and U138 MG were treated with purines and pyrimidines for 24 or 48 h and proliferation was measured by [3H]-thymidine incorporation, flow cytometry and cell counting. The studies showed that extracellular nucleotides and nucleosides induce proliferation of the studied glioma cells. Incorporation of [3H]-thymidine followed the order of ATP approximately equal to guanosine approximately equal to inosine approximately equal to adenosine > UTP > ADP while ATPgammaS and 2MeSATP had no effect. The effect of ATP was partially inhibited by suramin and by reactive blue 2 (RB2). Co-treatment with the following antagonists of P1 purinoreceptors DPCPX, CPT or 8PT did not block the effect of adenosine while a specific antagonist of the A3 receptor, MRS1220, totally blocked the effect of adenosine. ATP and adenosine also increased the overall uptake of [3H]-thymidine into the cell, producing a positive effect on the [3H]-thymidine incorporation measurements. These data indicate that the uptake of thymidine and proliferation of gliomas can be induced by purines and pyrimidines via both P1 and P2 purinoceptors.
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Affiliation(s)
- Fernanda B Morrone
- Departamento de Bioquimica, ICBS Faculdade de Farmácia, PUCRS, Porto Alegre, RS, Brazil
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Merighi S, Mirandola P, Varani K, Gessi S, Leung E, Baraldi PG, Tabrizi MA, Borea PA. A glance at adenosine receptors: novel target for antitumor therapy. Pharmacol Ther 2003; 100:31-48. [PMID: 14550503 DOI: 10.1016/s0163-7258(03)00084-6] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Adenosine can be released from a variety of cells throughout the body, as the result of increased metabolic rates, in concentrations that can have a profound impact on the vasculature, immunoescaping, and growth of tumor masses. It is recognized that the concentrations of this nucleoside are increased in cancer tissues. Therefore, it is not surprising that adenosine has been shown to be a crucial factor in determining the cell progression pathway, either during apoptosis or during cytostatic state. From the perspective of cancer, the most important question then may be "Can activation and/or blockade of the pathways downstream of the adenosine receptor contribute to tumor development?" Rigorous examinations of the role of adenosine in in vivo and in vitro systems need to be investigated. The present review therefore proposes multiple adenosine-sustained ways that could prime tumor development together with the critical combinatorial role played by adenosine receptors in taking a choice between proliferation and death. This review proposes that adenosine acts as a potent regulator of normal and tumor cell growth. It is hypothesized that this effect is dependent on extracellular adenosine concentrations, cell surface expression of different adenosine receptor subtypes, and signal transduction mechanisms activated following the binding of specific agonists. We venture to suggest that the clarification of the role of adenosine and its receptors in cancer development may hold great promise for the treatment of chemotherapy in patients affected by malignancies.
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Affiliation(s)
- Stefania Merighi
- Pharmacology Unit, Department of Clinical and Experimental Medicine, Via Fossato di Mortara 17-19, 44100, Ferrara, Italy
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Merighi S, Mirandola P, Varani K, Gessi S, Capitani S, Leung E, Baraldi PG, Tabrizi MA, Borea PA. Pyrazolotriazolopyrimidine derivatives sensitize melanoma cells to the chemotherapic drugs: taxol and vindesine. Biochem Pharmacol 2003; 66:739-48. [PMID: 12948854 DOI: 10.1016/s0006-2952(03)00400-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In this study, we have evaluated the "in vitro" modulatory activity of a series of pyrazolotriazolopyrimidine derivatives (PTP-d) in sensitizing malignant melanoma cells to the chemotherapic drugs: taxol and vindesine. To that end, we have described the impact of chemotherapeutic agents on the cell cycle and on the induction of apoptosis when used alone or in combination with PTP-d. We have demonstrated that four PTP-d reduced chemotherapic drugs EC(50) doses of the G(2)/M accumulation with an average of 1.7-fold for taxol and 9.5-fold for vindesine when challenged on A375 human melanoma cell line. This sensitization activity was also confirmed by analyzing the apoptosis degree induced by the chemotherapic drugs. Interestingly, PTP-d had no effects on the response to cytotoxic agents by skin-derived human keratinocyte cells, NCTC 2544. Therefore, we have investigated the signaling pathway sustaining the sensitizing effect of PTP-d, providing functional evidence that active compounds are able to inhibit multidrug resistance-associated ATP-binding cassette drug transporter. These results suggested that PTP-d hold great promise for the treatment of multidrug resistance in cancers, leading to potential new therapies for melanoma.
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Affiliation(s)
- Stefania Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, 44100 Ferrara, Italy
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Baraldi PG, Tabrizi MA, Fruttarolo F, Bovero A, Avitabile B, Preti D, Romagnoli R, Merighi S, Gessi S, Varani K, Borea PA. Recent developments in the field of A3 adenosine receptor antagonists. Drug Dev Res 2003. [DOI: 10.1002/ddr.10167] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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34
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Merighi S, Baraldi PG, Gessi S, Iannotta V, Klotz KN, Leung E, Mirandola P, Tabrizi MA, Varani K, Borea PA. Adenosine receptors and human melanoma. Drug Dev Res 2003. [DOI: 10.1002/ddr.10181] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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35
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Baraldi PG, Fruttarolo F, Tabrizi MA, Preti D, Romagnoli R, El-Kashef H, Moorman A, Varani K, Gessi S, Merighi S, Borea PA. Design, synthesis, and biological evaluation of C9- and C2-substituted pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines as new A2A and A3 adenosine receptors antagonists. J Med Chem 2003; 46:1229-41. [PMID: 12646033 DOI: 10.1021/jm021023m] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the past few years, our group has been involved in the development of A(2A) and A(3) adenosine receptor antagonists which led to the synthesis of SCH58261 (5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine, 61), potent and very selective at the A(2A) receptor subtype, and N(8)-substituted-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines-N(5)-urea or amide (MRE series, b), very selective at the human A(3) adenosine receptor subtype. We now describe a large series of C(9)- and C(2)-substituted pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines to represent an extension of structure-activity relationship work on this class of tricyclic compounds. The introduction of a substituent at 9 position of the tricyclic antagonistic structure led to retention of receptor affinity but a loss of selectivity in respect to the lead compounds b, N(8)-substituted-pirazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidines-N(5)-urea or -amide. The substitution of the furanyl moiety of compound 61, necessary for receptor binding, with a phenyl or a substituted aromatic ring (compounds 5a-d, 6-8), caused a complete loss of the affinity at all the adenosine receptor subtypes, demonstrating that the furanyl ring is a necessary structural element to guarantee interaction with the adenosine receptor surface. The introduction of an ethoxy group at the ortho position of the aromatic ring to mimic the oxygen of the furan (compound 5c, 5-amino-7-(2-phenylethyl)-2-(2-ethoxyphenyl)pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine) did not enhance affinity. The introduction of the cycloaminomethyl function by Mannich reaction at the 5' position of the furanyl ring of 61 and the C(9)-substituted compound 41 (5-amino-8-methyl-9-methylsulfanyl-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine) resulted in complete water solubility but a loss of receptor affinity. We can conclude that modifications or substitutions at the furanyl ring are not allowed and the introduction of a substituent at the 9-position of the core pyrazolo-triazolo-pyrimidine structure caused a severe loss of selectivity, probably due to an increased steric hindrance of the radical introduced.
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Affiliation(s)
- Pier Giovanni Baraldi
- Dipartimento di Scienze Farmaceutiche and Dipartimento di Medicina Clinica e Sperimentale-Sezione di Farmacologia, Università di Ferrara, 44100 Ferrara, Italy.
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Fossetta J, Jackson J, Deno G, Fan X, Du XK, Bober L, Soudé-Bermejo A, de Bouteiller O, Caux C, Lunn C, Lundell D, Palmer RK. Pharmacological analysis of calcium responses mediated by the human A3 adenosine receptor in monocyte-derived dendritic cells and recombinant cells. Mol Pharmacol 2003; 63:342-50. [PMID: 12527805 DOI: 10.1124/mol.63.2.342] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Extensive characterization of adenosine receptors expressed by human monocyte-derived dendritic cells (MDDCs) was performed with quantitative polymerase chain reaction, radioligand binding, and calcium signaling. Transcript for the A3 adenosine receptor was elevated more than 100-fold in immature MDDCs compared with monocyte precursors. A3 receptor transcript was substantially diminished, and A2A receptor transcript increased, by lipopolysaccharide maturation of MDDCs. Saturation binding of N(6)-(3-[(125)I]iodo-4-aminobenzyl)-adenosine-5'-N-methyluronamide ([(125)I]AB-MECA) to membranes from immature MDDCs yielded B(max) of 298 fmol/mg of protein and K(D) of 0.7 nM. Competition against [(125)I]AB-MECA binding confirmed the site to be the A3 receptor. Adenosine elicited pertussis toxin-sensitive calcium responses with EC(50) values ranging as low as 2 nM. The order of potency for related agonists was N(6)-(3-iodobenzyl)-adenosine-5'-N-methylcarboxamide (IB-MECA) >/= I-AB-MECA > 2Cl-IB-MECA >/= adenosine > 2-[p-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxyamidoadenosine (CGS21680). The order of efficacy was adenosine >/= CGS21680 > IB-MECA >/= I-AB-MECA > 2Cl-IB-MECA. Calcium responses to 2Cl-IB-MECA and CGS21680, and the lower range of adenosine concentrations, were completely blocked by 10 nM N-(2-methoxyphenyl)-N-[2-(3-pyridyl)quinazolin-4-yl]urea (VUF5574) but not by 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH58261) or 8-cyclopentyl-1,3-dipropylxanthine. Pretreatment with 100 nM 2Cl-IB-MECA eliminated responses to CGS21680 but not to monocyte inhibitory protein-1alpha. For comparison, dose-response functions were obtained from double-recombinant human embryonic kidney 293 cells expressing the human A3 receptor and a chimeric Galphaq-i3 protein, which was required to establish A3-mediated calcium signaling. The pharmacological profile of calcium signaling elicited by adenosine-related agonists in the double-recombinant cells was essentially identical to that obtained from immature MDDCs. Our results provide an extensive analysis of A3-mediated calcium signaling and unequivocally identify immature MDDCs as native expressers of the human A3 receptor.
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Affiliation(s)
- James Fossetta
- Immunology Department, Schering-Plough Research Institute, Kenilworth, New Jersey 07033, USA
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DeNinno MP, Masamune H, Chenard LK, DiRico KJ, Eller C, Etienne JB, Tickner JE, Kennedy SP, Knight DR, Kong J, Oleynek JJ, Tracey WR, Hill RJ. 3'-Aminoadenosine-5'-uronamides: discovery of the first highly selective agonist at the human adenosine A3 receptor. J Med Chem 2003; 46:353-5. [PMID: 12540233 DOI: 10.1021/jm0255724] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Selective adenosine A(3) agonists have potential utility for the prevention of perioperative myocardial ischemic injury. Herein, we report on the discovery and synthesis of compound 7. This amino nucleoside agonist possesses unprecedented levels of selectivity for the human adenosine A(3) receptor.
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Affiliation(s)
- Michael P DeNinno
- PGRD Groton Laboratories, Pfizer Inc., Groton, Connecticut 06340, USA.
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Merighi S, Mirandola P, Milani D, Varani K, Gessi S, Klotz KN, Leung E, Baraldi PG, Borea PA. Adenosine receptors as mediators of both cell proliferation and cell death of cultured human melanoma cells. J Invest Dermatol 2002; 119:923-33. [PMID: 12406340 DOI: 10.1046/j.1523-1747.2002.00111.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Adenosine displays contradictory effects on cell growth: it improves cell proliferation, but it may also induce apoptosis and impair cell survival. Following the pharmacologic characterization of adenosine receptor expression on the human melanoma cell line A375, we chose A375 as our cellular model to define how the extracellular adenosine signals are conveyed from each receptor. By using selective adenosine receptor agonists or antagonists, we found that A2A stimulation reduced cell viability and cell clone formation, whereas, at the same time, it improved cell proliferation. In support of this finding we demonstrated that the stimulation of A2A adenosine receptors stably expressed in Chinese hamster ovary cell clone reproduced deleterious effects observed in human melanoma cells. A3 stimulation counteracted A2A-induced cell death but also reduced cell proliferation. Furthermore, we found that A3 stimulation ensures cell survival. We demonstrated that adenosine triggers a survival signal via A3 receptor activation and it kills the cell through A2A receptor inducing a signaling pathway that involves protein kinase C and mitogen-activated protein kinases.
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Affiliation(s)
- Stefania Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Italy
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Gessi S, Varani K, Merighi S, Cattabriga E, Iannotta V, Leung E, Baraldi PG, Borea PA. A(3) adenosine receptors in human neutrophils and promyelocytic HL60 cells: a pharmacological and biochemical study. Mol Pharmacol 2002; 61:415-24. [PMID: 11809867 DOI: 10.1124/mol.61.2.415] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This work compares the pharmacological and biochemical properties of A(3) adenosine receptors in human polymorphonuclear neutrophil granulocytes (PMNs) and promyelocytic HL60 cells. The gene expression of A(3) receptors was examined by reverse transcription-polymerase chain reaction experiments, whereas the amount of A(3) subtype on the plasma membrane was quantified by using the high-affinity and selective A(3) antagonist [(3)H]5N-(4-methoxyphenyl-carbamoyl)amino-8-propyl-2-(2-furyl)pyrazolo-[4,3-e]1,2,4-triazolo[1,5-c]pyrimidine ([(3)H]MRE 3008F20). Saturation experiments reveal a single high-affinity binding site with K(D) values of 2.3 +/- 0.3, 2.6 +/- 0.4 nM, and B(max) values of 430 +/- 35, 345 +/- 31 fmol/mg of protein for PMNs and HL60 cells, respectively. Competition of radioligand binding by adenosine ligands displays a rank order of potency typical of the A(3) subtype. EC(50) values of N(6)-(3-iodo-benzyl)-2-chloro-adenosine-5'-N-methyluronamide (Cl-IB-MECA) for inhibition of cAMP levels via A(3) receptors are in good agreement with the binding data; furthermore, the response is potently inhibited by MRE 3008F20. In contrast, the high micromolar concentrations of Cl-IB-MECA and MRE 3008F20 in stimulating and blocking Ca(2+) mobilization, respectively, are not completely consistent with the involvement of an A(3) receptor. Furthermore, an important finding of this work is that the inhibition of PMNs oxidative burst is predominantly A(2A)-mediated, even though an effect of A(3) subtype could not be excluded. This conclusion is based on potent blockade of Cl-IB-MECA-mediated inhibition of oxidative burst by SCH 58261 and a minor but significant blockade by MRE 3008F20. In conclusion, HL60 cells express A(3) receptors similar to those in PMNs, thus providing a useful model for investigation of biochemical pathways leading to A(3) receptor activation.
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Affiliation(s)
- Stefania Gessi
- Department of Clinical and Experimental Medicine, University of Ferrara, Italy
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Merighi S, Varani K, Gessi S, Klotz KN, Leung E, Baraldi PG, Borea PA. Binding thermodynamics at the human A(3) adenosine receptor. Biochem Pharmacol 2002; 63:157-61. [PMID: 11841789 DOI: 10.1016/s0006-2952(01)00825-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The thermodynamic parameters DeltaG , DeltaH and DeltaS of the binding equilibrium of six adenosine receptor agonists and five antagonists at adenosine A(3) receptors were determined by means of affinity measurements at six different temperatures (4, 10, 15, 20, 25 and 30) and van't Hoff plots were constructed. Affinity constants were measured on Chinese hamster ovary (CHO) cells transfected with the human A(3) receptors by inhibition assays of the binding of the selective A(3) antagonist [3H]MRE 3008F20. van't Hoff plots were linear for agonists and antagonists in the temperature range 4-30 degree. Their thermodynamic parameters fall in the ranges 21 < or = DeltaH < or = 67kJmol(-1) and 208 < or = DeltaS < or =410 J(Kmol)(-1) for agonists and -52 < or = DeltaH < or = -9 kJmol(-1) and 16 < or = DeltaS < or =81 J(K/mol)(-1) for antagonists, showing that agonist binding is always totally entropy-driven while antagonist binding is enthalpy- and entropy-driven. The results are discussed with the aim of obtaining new details on the nature of the forces driving the A(3) binding at a molecular level.
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Affiliation(s)
- Stefania Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, Centro Nazionale di Eccellenza per lo Sviluppo di Metodologie Innovative per lo Studio ed il Trattamento delle Patologie Infiammatorie, University of Ferrara, Ferrara, Italy
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Merighi S, Varani K, Gessi S, Cattabriga E, Iannotta V, Ulouglu C, Leung E, Borea PA. Pharmacological and biochemical characterization of adenosine receptors in the human malignant melanoma A375 cell line. Br J Pharmacol 2001; 134:1215-26. [PMID: 11704641 PMCID: PMC1573044 DOI: 10.1038/sj.bjp.0704352] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The present work characterizes, from a pharmacological and biochemical point of view, adenosine receptors in the human malignant melanoma A375 cell line. 2. Adenosine receptors were detected by RT - PCR experiments. A1 receptors were characterized using [3H]-DPCPX binding with a KD of 1.9+/-0.2 nM and Bmax of 23+/-7 fmol x mg(-1) of protein. A2A receptors were studied with [3H]-SCH 58261 binding and revealed a KD of 5.1+/-0.2 nM and a Bmax of 220+/-7 fmol x mg(-1) of protein. A3 receptors were studied with the new A3 adenosine receptor antagonist [3H]-MRE 3008F20, the only A3 selective radioligand currently available. Saturation experiments revealed a single high affinity binding site with KD of 3.3+/-0.7 nM and Bmax of 291+/-50 fmol x mg(-1) of protein. 3. The pharmacological profile of radioligand binding on A375 cells was established using typical adenosine ligands which displayed a rank order of potency typical of the different adenosine receptor subtype. 4. Thermodynamic data indicated that radioligand binding to adenosine receptor subtypes in A375 cells was entropy- and enthalpy-driven. 5. In functional assays the high affinity A2A agonists HE-NECA, CGS 21680 and A2A - A2B agonist NECA were able to increase cyclic AMP accumulation in A375 cells whereas A3 agonists Cl-IB-MECA, IB-MECA and NECA were able to stimulate Ca2+ mobilization. In conclusion, all these data indicate, for the first time, that adenosine receptors with a pharmacological and biochemical profile typical of the A1, A2A, A2B and A3 receptor subtype are present on A375 melanoma cell line.
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Affiliation(s)
- Stefania Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Centro Nazionale Di Eccellenza Per Lo Sviluppo Di Metodologie Innovative Per Lo Studio Ed Il Trattamento Delle Patologie Infiammatorie, Italy
| | - Katia Varani
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Centro Nazionale Di Eccellenza Per Lo Sviluppo Di Metodologie Innovative Per Lo Studio Ed Il Trattamento Delle Patologie Infiammatorie, Italy
| | - Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Centro Nazionale Di Eccellenza Per Lo Sviluppo Di Metodologie Innovative Per Lo Studio Ed Il Trattamento Delle Patologie Infiammatorie, Italy
| | - Elena Cattabriga
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Centro Nazionale Di Eccellenza Per Lo Sviluppo Di Metodologie Innovative Per Lo Studio Ed Il Trattamento Delle Patologie Infiammatorie, Italy
| | - Valeria Iannotta
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Centro Nazionale Di Eccellenza Per Lo Sviluppo Di Metodologie Innovative Per Lo Studio Ed Il Trattamento Delle Patologie Infiammatorie, Italy
| | - Canan Ulouglu
- Department of Pharmacology, Gazi University, Medical Faculty, Ankara, Turkey
| | - Edward Leung
- King Pharmaceuticals, Cary, North Carolina, U.S.A
| | - Pier Andrea Borea
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Centro Nazionale Di Eccellenza Per Lo Sviluppo Di Metodologie Innovative Per Lo Studio Ed Il Trattamento Delle Patologie Infiammatorie, Italy
- Author for correspondence:
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Gessi S, Varani K, Merighi S, Morelli A, Ferrari D, Leung E, Baraldi PG, Spalluto G, Borea PA. Pharmacological and biochemical characterization of A3 adenosine receptors in Jurkat T cells. Br J Pharmacol 2001; 134:116-26. [PMID: 11522603 PMCID: PMC1572937 DOI: 10.1038/sj.bjp.0704254] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2001] [Revised: 05/24/2001] [Accepted: 06/25/2001] [Indexed: 01/11/2023] Open
Abstract
1. The present work was devoted to the study of A3 adenosine receptors in Jurkat cells, a human leukemia line. 2. The A3 subtype was found by means of RT-PCR experiments and characterized by using the new A3 adenosine receptor antagonist [3H]-MRE 3008F20, the only A3 selective radioligand currently available. Saturation experiments revealed a single high affinity binding site with K(D) of 1.9+/-0.2 nM and B(max) of 1.3+/-0.1 pmol mg(-1) of protein. 3. The pharmacological profile of [3H]-MRE 3008F20 binding on Jurkat cells was established using typical adenosine ligands which displayed a rank order of potency typical of the A3 subtype. 4. Thermodynamic data indicated that [3H]-MRE 3008F20 binding to A3 subtype in Jurkat cells was entropy- and enthalpy-driven, according with that found in cells expressing the recombinant human A3 subtype. 5. In functional assays the high affinity A3 agonists Cl-IB-MECA and IB-MECA were able to inhibit cyclic AMP accumulation and stimulate Ca(2+) release from intracellular Ca(2+) pools followed by Ca(2+) influx. 6. The presence of the other adenosine subtypes was investigated in Jurkat cells. A1 receptors were characterized using [3H]-DPCPX binding with a K(D) of 0.9+/-0.1 nM and B(max) of 42+/-3 fmol mg(-1) of protein. A2A receptors were studied with [3H]-SCH 58261 binding and revealed a K(D) of 2.5+/-0.3 nM and a B(max) of 1.4+/-0.2 pmol mg(-1) of protein. 7. In conclusion, by means of the first antagonist radioligand [3H]-MRE 3008F20 we could demonstrate the existence of functional A3 receptors on Jurkat cells.
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Affiliation(s)
- Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Italy
| | - Katia Varani
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Italy
| | - Stefania Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Italy
| | - Anna Morelli
- Section of General Pathology, Department of Experimental and Diagnostic Medicine, Biotechnology Center, University of Ferrara, Italy
| | - Davide Ferrari
- Section of General Pathology, Department of Experimental and Diagnostic Medicine, Biotechnology Center, University of Ferrara, Italy
| | - Edward Leung
- King Pharmaceutical Research, Research Triangle Park, North Carolina, U.S.A
| | | | | | - Pier Andrea Borea
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Italy
- University of Ferrara, ‘Centro Nazionale di Eccellenza per lo Sviluppo di Metodologie Innovative per lo Studio ed il Trattamento delle Patologie Infiammatorie'
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