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Lin Y, Malins LR. An Electrochemical Approach to Designer Peptide α-Amides Inspired by α-Amidating Monooxygenase Enzymes. J Am Chem Soc 2021; 143:11811-11819. [PMID: 34288681 DOI: 10.1021/jacs.1c05718] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Designer C-terminal peptide amides are accessed in an efficient and epimerization-free approach by pairing an electrochemical oxidative decarboxylation with a tandem hydrolysis/reduction pathway. Resembling Nature's dual enzymatic approach to bioactive primary α-amides, this method delivers secondary and tertiary amides bearing high-value functional motifs, including isotope labels and handles for bioconjugation. The protocol leverages the inherent reactivity of C-terminal carboxylates, is compatible with the vast majority of proteinogenic functional groups, and proceeds in the absence of epimerization, thus addressing major limitations associated with conventional coupling-based approaches. The utility of the method is exemplified through the synthesis of natural product acidiphilamide A via a key diastereoselective reduction, as well as bioactive peptides and associated analogues, including an anti-HIV lead peptide and blockbuster cancer therapeutic leuprolide.
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Affiliation(s)
- Yutong Lin
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
| | - Lara R Malins
- Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia.,Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, Australian National University, Canberra, ACT 2601, Australia
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Hoppenz P, Els‐Heindl S, Beck‐Sickinger AG. Identification and stabilization of a highly selective gastrin‐releasing peptide receptor agonist. J Pept Sci 2019; 25:e3224. [DOI: 10.1002/psc.3224] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 09/24/2019] [Accepted: 09/25/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Paul Hoppenz
- Institute of BiochemistryLeipzig University Leipzig Germany
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Ramos-Alvarez I, Lee L, Mantey SA, Jensen RT. Development and Characterization of a Novel, High-Affinity, Specific, Radiolabeled Ligand for BRS-3 Receptors. J Pharmacol Exp Ther 2019; 369:454-465. [PMID: 30971479 DOI: 10.1124/jpet.118.255141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 04/05/2019] [Indexed: 02/06/2023] Open
Abstract
Bombesin (Bn) receptor subtype 3(BRS-3) is an orphan G-protein-coupled receptor of the Bn family, which does not bind any natural Bn peptide with high affinity. Receptor knockout studies show that the animals develop diabetes, obesity, altered temperature control, and other central nervous system (CNS)/endocrine/gastrointestinal changes. It is present in CNS, peripheral tissues, and tumors; however, its role in normal physiology/pathophysiology, as well as its receptor localization/pharmacology is largely unknown, in part due to the lack of a convenient, specific, direct radiolabeled ligand. This study was designed to address this problem and to develop and characterize a specific radiolabeled ligand for BRS-3. The peptide antagonist Bantag-1 had >10,000-fold selectivity for human BRS-3 (hBRS-3) over other mammalian Bn receptors (BnRs) [i.e., gastrin-releasing peptide receptor (GRPR) and neuromedin B receptor (NMBR)]. Using iodogen and basic conditions, it was radiolabeled to high specific activity (2200 Ci/mmol) and found to bind with high affinity/specificity to hBRS-3. Binding was saturable, rapid, and reversible. The ligand only interacted with known BRS-3 ligands, and not with other specific GRPR/NMBR ligands or ligands for unrelated receptors. The magnitude of 125I-Bantag-1 binding correlated with BRS-3 mRNA expression and the magnitude of activation of phospholipase C in lung cancer cells, as well as readily identifying BRS-3 in lung cancer cells and normal tissues, allowing the direct assessment of BRS-3 receptor pharmacology/numbers on cells containing BRS-3 with other BnRs, which is usually the case. This circumvents the need for subtraction assays, which are now frequently used to assess BRS-3 indirectly using radiolabeled pan-ligands, which interact with all BnRs.
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Affiliation(s)
- Irene Ramos-Alvarez
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Lingaku Lee
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Samuel A Mantey
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Robert T Jensen
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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González N, Moreno P, Jensen RT. Bombesin receptor subtype 3 as a potential target for obesity and diabetes. Expert Opin Ther Targets 2015; 19:1153-70. [PMID: 26066663 DOI: 10.1517/14728222.2015.1056154] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Diabetes mellitus and obesity are important health issues; increasing in prevalence, both in the USA and globally. There are only limited pharmacological treatments, and although bariatric surgery is effective, new effective pharmacologic treatments would be of great value. This review covers one area of increasing interest that could yield new novel treatments of obesity/diabetes mellitus. It involves recognition of the central role the G-protein-coupled receptor, bombesin receptor subtype 3 (BRS-3) plays in energy/glucose metabolism. AREAS COVERED Since the initial observation that BRS-3 knockout mice develop obesity, hypertension, impaired glucose metabolism and hyperphagia, there have been numerous studies of the mechanisms involved and the development of selective BRS-3 agonists/antagonists, which have marked effects on body weight, feeding and glucose/insulin homeostasis. In this review, each of these areas is briefly reviewed. EXPERT OPINION BRS-3 plays an important role in glucose/energy homeostasis. The development of potent, selective BRS-3 agonists demonstrates promise as a novel approach to treat obesity/diabetic states. One important question that needs to be addressed is whether BRS-3 agonists need to be centrally acting. This is particularly important in light of recent animal and human studies that report transient cardiovascular side effects with centrally acting oral BRS agonists.
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Affiliation(s)
- Nieves González
- The Autonomous University of Madrid, IIS-Jiménez Díaz Foundation, Renal, Vascular and Diabetes Research Laboratory, Spanish Biomedical Research Network in Diabetes and, Associated Metabolic Disorders (CIBERDEM) , Madrid , Spain
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Abstract
PURPOSE OF REVIEW This review summarizes the results of recent studies regarding the biology and pharmacology of novel synthetic agonists and antagonists of the bombesin receptor subtype-3 (BRS-3). RECENT FINDINGS All three mammalian bombesin receptors including gastrin-releasing peptide receptor, the neuromedin B receptor, and the BRS-3 have been shown to regulate energy balance and appetite and satiety. Studies indicate that the orphan BRS-3 is an important regulator of body weight, energy expenditure, and glucose homeostasis. Endogenous bombesin-like peptides bombesin, gastrin-releasing peptide, and neuromedin B receptor do not bind to BRS-3 and the endogenous BRS-3 ligand remains unknown. The novel synthesis of selective, high-affinity BRS-3 agonists and antagonists has recently been accomplished and showed that BRS-3 regulates energy balance independent of other established pathways and glucose-stimulated insulin secretion in the pancreatic islet cells. The availability of new BRS-3 selective agonists and antagonists will facilitate further elucidation of its role in energy homeostasis, and provides a potential approach for the pharmacological treatment of obesity and type 2 diabetes. SUMMARY The native ligand of the G protein-coupled BRS-3 has not been identified as of now. However, novel synthesis of small-molecule, high-affinity agonists and antagonists on the BRS-3 was used in the recent studies and demonstrated an important role of BRS-3 in the regulation of energy homeostasis and glucose metabolism.
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Affiliation(s)
- Ishita D Majumdar
- Section of Gastroenterology, Boston University School of Medicine, Boston, Massachusetts, USA
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6
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Abstract
Studies on bombesin-like peptides (BLP) and their respective mammalian receptors (Bn-r) have demonstrated a significant biological impact on a broad array of physiological and pathophysiological conditions. Pharmacological experiments in vitro and in vivo as well as utilization of genetic rodent models of the gastrin-releasing peptide receptor (GRP-R/BB2-receptor), neuromedin B receptor (NMB-R/BB1-receptor), and the bombesin receptor subtype-3 (BRS-3/BB3-receptor) further delineated their role in health and disease. All three mammalian bombesin receptors have been shown to possess some role in the regulation of energy balance and appetite and satiety. Compelling experimental evidence has accumulated indicating that the orphan BRS-3 is an important regulator of body weight, energy expenditure, and glucose homeostasis. BRS-3 possesses no high affinity to the endogenous bombesin-like peptides (BLP) bombesin, GRP, and NMB, and its endogenous ligand remains unknown. Recently, the synthesis of novel, selective high-affinity BRS-3 agonists and antagonists has been accomplished and has demonstrated that BRS-3 regulates energy balance independent of other established pathways. Accordingly, the availability of new BRS-3 selective agonists and antagonists will facilitate further elucidation of its role in energy homeostasis and provides a potential approach for the pharmacological treatment of obesity.
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Pyridinesulfonylureas and pyridinesulfonamides as selective bombesin receptor subtype-3 (BRS-3) agonists. Bioorg Med Chem Lett 2011; 21:2040-3. [PMID: 21354793 DOI: 10.1016/j.bmcl.2011.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 02/02/2011] [Accepted: 02/03/2011] [Indexed: 10/18/2022]
Abstract
Bombesin receptor subtype-3 (BRS-3) is an orphan G-protein coupled receptor belonging to the subfamily of bombesin-like receptors. BRS-3 is implicated in the development of obesity and diabetes. We report here small-molecule agonists that are based on a 4-(alkylamino)pyridine-3-sulfonamide core. We describe the discovery of 2a, which has mid-nanomolar potency, selectivity for human BRS-3 versus the other bombesin-like receptors, and good bioavailability.
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Abstract
PURPOSE OF REVIEW This review will highlight recent advances in the understanding of mammalian bombesin receptor-related pathophysiological roles in disease states and new insights into bombesin receptor pharmacology. RECENT FINDINGS Studies regarding bombesin-like peptides and mammalian bombesin receptor functions have demonstrated significant biological impact on a broad array of physiological and pathophysiological conditions. Pharmacological experiments in vitro and in vivo as well as utilization of genetic rodent models of the gastrin-releasing peptide receptor (GRP-R/BB2) and neuromedin B receptor (NMB-R/BB1) further delineated roles in memory and fear behavior, inhibition of tumor cell growth, mediating signals for pruritus and male reproductive behavior. All three mammalian bombesin receptors were shown to possess some role in the regulation of energy balance. Novel synthesis of selective high affinity agonists and antagonists of the orphan bombesin receptor subtype-3 (BRS-3/BB3) has been accomplished and will facilitate further studies using animal model systems. SUMMARY Mammalian bombesin receptors participate in the regulation of energy homeostasis and may represent an attractive target for pharmacological treatment of obesity and certain eating disorders. Novel pharmacological insights of bombesin-like peptides and the interaction with their respective receptors have been elucidated to aid future treatment and imaging of epithelial cell-derived tumors.
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Affiliation(s)
- Ishita D Majumdar
- Section of Gastroenterology, Boston University School of Medicine, Boston, Massachusetts, USA
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9
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Sebhat IK, Franklin C, Lo MMC, Chen D, Jewell JP, Miller R, Pang J, Palyha O, Kan Y, Kelly TM, Guan XM, Marsh DJ, Kosinski JA, Metzger JM, Lyons K, Dragovic J, Guzzo PR, Henderson AJ, Reitman ML, Nargund RP, Wyvratt MJ, Lin LS. Discovery of MK-5046, a Potent, Selective Bombesin Receptor Subtype-3 Agonist for the Treatment of Obesity. ACS Med Chem Lett 2011; 2:43-7. [PMID: 24900253 DOI: 10.1021/ml100196d] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 10/06/2010] [Indexed: 11/29/2022] Open
Abstract
We report the development and characterization of compound 22 (MK-5046), a potent, selective small molecule agonist of BRS-3 (bombesin receptor subtype-3). In pharmacological testing using diet-induced obese mice, compound 22 caused mechanism-based, dose-dependent reductions in food intake and body weight.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Peter R. Guzzo
- AMRI, 26 Corporate Circle, Albany, New York 12212, United States
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Sancho V, Moody TW, Mantey SA, Di Florio A, Uehara H, Coy DH, Jensen RT. Pharmacology of putative selective hBRS-3 receptor agonists for human bombesin receptors (BnR): affinities, potencies and selectivity in multiple native and BnR transfected cells. Peptides 2010; 31:1569-78. [PMID: 20438784 PMCID: PMC2905478 DOI: 10.1016/j.peptides.2010.04.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/23/2010] [Accepted: 04/23/2010] [Indexed: 11/28/2022]
Abstract
The orphan receptor, bombesin receptor subtype-3(BRS-3) is a G-protein-coupled receptor classified in the bombesin (Bn) receptor family because of its high homology (47-51%) with other members of this family [gastrin-releasing peptide receptor [GRPR] and neuromedin B receptor [NMBR]]. There is increasing interest in BRS-3, because primarily from receptor knockout studies, it seems important in energy metabolism, glucose control, insulin secretion, motility and tumor growth. Pharmacological tools to study the role of BRS-3 in physiology/pathophysiology are limited because the natural ligand is unknown and BRS-3 has low affinity for all naturally occurring Bn-related peptides. However, a few years ago a synthetic high-affinity agonist [dTyr(6),betaAla(11),Phe(13),Nle(14)]Bn-(6-14) was described but was nonselective for BRS-3 over other Bn receptors. Based on this peptide, in various studies a number of putative selective, high-potency hBRS-3 agonists were described, however the results on their selectivity are conflicting in a number of cases. The purpose of the present study was to thoroughly study the pharmacology of four of the most select/potent putative hBRS-3 agonists (#2-4, 16a). Each was studied in multiple well-characterized Bn receptor-transfected cells and native Bn receptor bearing cells, using binding studies, alterations in cellular signaling (PLC, PKD) and changes in cellular function(growth). Two peptides (#2, #3) had nM affinities/potencies for hBRS-3, peptide #4 had low affinity/potency, and peptide #16a very low (>3000 nM). Peptide#3 had the highest selectivity for hBRS-3 (100-fold), whereas #2, 4 had lower selectivity. Peptide #16a's selectivity could not be determined because of its low affinity/potencies for all hBn receptors. These results show that peptide #3 is the preferred hBRS-3 agonist for studies at present, although its selectivity of only 100-fold may limit its utility in some cases. This study underscores the importance of full pharmacological characterization of newly reported selective agonists.
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Affiliation(s)
- Veronica Sancho
- Digestive Diseases Branch, NIDDK, and Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892-1804
| | - Terry W. Moody
- NCI Office of the Director, CCR, NCI and Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892-1804
| | - Samuel A. Mantey
- Digestive Diseases Branch, NIDDK, and Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892-1804
| | - Alessia Di Florio
- Digestive Diseases Branch, NIDDK, and Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892-1804
| | - Hirotsugu Uehara
- Digestive Diseases Branch, NIDDK, and Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892-1804
| | - David H. Coy
- Peptide Research Laboratories, Department of Medicine, Tulane Health Sciences Center, New Orleans, Louisiana 70112-2699
| | - Robert T. Jensen
- Digestive Diseases Branch, NIDDK, and Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892-1804
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Liu J, He S, Jian T, Dobbelaar PH, Sebhat IK, Lin LS, Goodman A, Guo C, Guzzo PR, Hadden M, Henderson AJ, Pattamana K, Ruenz M, Sargent BJ, Swenson B, Yet L, Tamvakopoulos C, Peng Q, Pan J, Kan Y, Palyha O, Kelly TM, Guan XM, Howard AD, Marsh DJ, Metzger JM, Reitman ML, Wyvratt MJ, Nargund RP. Synthesis and SAR of derivatives based on 2-biarylethylimidazole as bombesin receptor subtype-3 (BRS-3) agonists for the treatment of obesity. Bioorg Med Chem Lett 2010; 20:2074-7. [DOI: 10.1016/j.bmcl.2010.02.076] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 02/16/2010] [Accepted: 02/18/2010] [Indexed: 10/19/2022]
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Discovery of substituted biphenyl imidazoles as potent, bioavailable bombesin receptor subtype-3 agonists. Bioorg Med Chem Lett 2010; 20:1913-7. [DOI: 10.1016/j.bmcl.2010.01.154] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 01/21/2010] [Accepted: 01/27/2010] [Indexed: 11/22/2022]
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Kauffman C, Karypis G. LIBRUS: combined machine learning and homology information for sequence-based ligand-binding residue prediction. Bioinformatics 2009; 25:3099-107. [PMID: 19786483 DOI: 10.1093/bioinformatics/btp561] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
MOTIVATION Identifying residues that interact with ligands is useful as a first step to understanding protein function and as an aid to designing small molecules that target the protein for interaction. Several studies have shown that sequence features are very informative for this type of prediction, while structure features have also been useful when structure is available. We develop a sequence-based method, called LIBRUS, that combines homology-based transfer and direct prediction using machine learning and compare it to previous sequence-based work and current structure-based methods. RESULTS Our analysis shows that homology-based transfer is slightly more discriminating than a support vector machine learner using profiles and predicted secondary structure. We combine these two approaches in a method called LIBRUS. On a benchmark of 885 sequence-independent proteins, it achieves an area under the ROC curve (ROC) of 0.83 with 45% precision at 50% recall, a significant improvement over previous sequence-based efforts. On an independent benchmark set, a current method, FINDSITE, based on structure features achieves an ROC of 0.81 with 54% precision at 50% recall, while LIBRUS achieves an ROC of 0.82 with 39% precision at 50% recall at a smaller computational cost. When LIBRUS and FINDSITE predictions are combined, performance is increased beyond either reaching an ROC of 0.86 and 59% precision at 50% recall. AVAILABILITY Software developed for this study is available at http://bioinfo.cs.umn.edu/supplements/binf2009 along with Supplementary data on the study.
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Affiliation(s)
- Chris Kauffman
- Department of Computer Science, University of Minnesota, 117 Pleasant St SE, Room 464, Minneapolis, MN 55455, USA.
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Discovery of small molecule agonists for the bombesin receptor subtype 3 (BRS-3) based on an omeprazole lead. Bioorg Med Chem Lett 2008; 18:5451-5. [DOI: 10.1016/j.bmcl.2008.09.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 09/05/2008] [Accepted: 09/08/2008] [Indexed: 11/23/2022]
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Jensen RT, Battey JF, Spindel ER, Benya RV. International Union of Pharmacology. LXVIII. Mammalian bombesin receptors: nomenclature, distribution, pharmacology, signaling, and functions in normal and disease states. Pharmacol Rev 2008; 60:1-42. [PMID: 18055507 PMCID: PMC2517428 DOI: 10.1124/pr.107.07108] [Citation(s) in RCA: 395] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The mammalian bombesin receptor family comprises three G protein-coupled heptahelical receptors: the neuromedin B (NMB) receptor (BB(1)), the gastrin-releasing peptide (GRP) receptor (BB(2)), and the orphan receptor bombesin receptor subtype 3 (BRS-3) (BB(3)). Each receptor is widely distributed, especially in the gastrointestinal (GI) tract and central nervous system (CNS), and the receptors have a large range of effects in both normal physiology and pathophysiological conditions. The mammalian bombesin peptides, GRP and NMB, demonstrate a broad spectrum of pharmacological/biological responses. GRP stimulates smooth muscle contraction and GI motility, release of numerous GI hormones/neurotransmitters, and secretion and/or hormone release from the pancreas, stomach, colon, and numerous endocrine organs and has potent effects on immune cells, potent growth effects on both normal tissues and tumors, potent CNS effects, including regulation of circadian rhythm, thermoregulation; anxiety/fear responses, food intake, and numerous CNS effects on the GI tract as well as the spinal transmission of chronic pruritus. NMB causes contraction of smooth muscle, has growth effects in various tissues, has CNS effects, including effects on feeding and thermoregulation, regulates thyroid-stimulating hormone release, stimulates various CNS neurons, has behavioral effects, and has effects on spinal sensory transmission. GRP, and to a lesser extent NMB, affects growth and/or differentiation of various human tumors, including colon, prostate, lung, and some gynecologic cancers. Knockout studies show that BB(3) has important effects in energy balance, glucose homeostasis, control of body weight, lung development and response to injury, tumor growth, and perhaps GI motility. This review summarizes advances in our understanding of the biology/pharmacology of these receptors, including their classification, structure, pharmacology, physiology, and role in pathophysiological conditions.
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Affiliation(s)
- R T Jensen
- Digestive Diseases Branch, National Institute of Diabetes Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
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Mantey SA, Gonzalez N, Schumann M, Pradhan TK, Shen L, Coy DH, Jensen RT. Identification of Bombesin Receptor Subtype-Specific Ligands: Effect ofN-Methyl Scanning, Truncation, Substitution, and Evaluation of Putative Reported Selective Ligands. J Pharmacol Exp Ther 2006; 319:980-9. [PMID: 16943256 DOI: 10.1124/jpet.106.107011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammalian bombesin (Bn) receptors include the gastrin-releasing peptide receptor, neuromedin B receptor, and bombesin receptor subtype 3 (BRS-3). These receptors are involved in a variety of physiological/pathologic processes, including thermoregulation, secretion, motility, chemotaxis, and mitogenic effects on both normal and malignant cells. Tumors frequently overexpress these receptors, and their presence is now used for imaging and receptor-mediated cytotoxicity. For these reasons, there is an increased need to develop synthetic, selective receptor subtype-specific ligands, especially agonists for these receptors. In this study, we used a number of strategies to identify useful receptor subtype-selective ligands, including synthesizing new analogs (N-methyl-substituted constrained analogs, truncations, and substitutions) in [d-Tyr(6),betaAla(11),Phe(13),Nle(14)]Bn(6-14), which has high affinity for all Bn receptors and is metabolically stable, as well as completely pharmacologically characterized analogs recently reported to be selective for these receptors in [Ca(2+)](i) assays. Affinities and potencies of each analog were determined for each human Bn receptor subtype. N-Methyl substitutions in positions 14, 12, 11, 10, 9, and 8 did not result in selective analogs, with the exception of position 11, which markedly decreased affinity/potency. N-Terminal truncations or position 12 substitutions did not increase selectivity as previously reported by others. Of the four shortened analogs of [d-Phe(6),betaAla(11),Phe(13),Nle(14)]Bn(6-14) reported to be potent selective BRS-3 ligands on [Ca(2+)](i) assays, only AcPhe,Trp,Ala,His(tauBzl),Nip,Gly,Arg-NH(2) had moderate selectivity for hBRS-3; however, it was less selective than previously reported Apa(11) analogs, demonstrating these are still the most selective BRS-3 analogs available. However, both of these analogs should be useful templates to develop more selective BRS-3 ligands.
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Affiliation(s)
- Samuel A Mantey
- DHHS/NIH, NIDDK, DDB, Bldg. 10, Rm. 9C103, 31 Center Drive, Bethesda, MD 20892, USA
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Boyle RG, Humphries J, Mitchell T, Showell GA, Apaya R, Iijima H, Shimada H, Arai T, Ueno H, Usui Y, Sakaki T, Wada E, Wada K. The design of a new potent and selective ligand for the orphan bombesin receptor subtype 3 (BRS3). J Pept Sci 2005; 11:136-41. [PMID: 15635635 DOI: 10.1002/psc.599] [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: 11/12/2022]
Abstract
Extensive SAR studies on the unselective BRS3 agonist, [H-D-Phe6,beta-Ala11,Phe13,Nle14]-bombesin-(6-14)-nonapeptide amide, have highlighted structural features important for BRS3 activity and have provided guidance as to the design of selective agonists. A radically modified heptapeptide agonist, maintaining only the Trp-Ala moiety of the parent [H-D-Phe6,betaAla11,Phe13,Nle14]-peptide amide, and with a very different carboxyl terminal region, has been produced which was potent at BRS3 and essentially had no NMB or GRP receptor activity. Its structure is Ac-Phe-Trp-Ala-His(tauBzl)-Nip-Gly-Arg-NH2.
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Mantey SA, Coy DH, Entsuah LK, Jensen RT. Development of Bombesin Analogs with Conformationally Restricted Amino Acid Substitutions with Enhanced Selectivity for the Orphan Receptor Human Bombesin Receptor Subtype 3. J Pharmacol Exp Ther 2004; 310:1161-70. [PMID: 15102928 DOI: 10.1124/jpet.104.066761] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human bombesin receptor subtype 3 (hBRS-3) orphan receptor, which has a high homology to bombesin (Bn) receptors [gastrin-releasing peptide (GRP) and neuromedin B (NMB) receptors], is widely distributed in the rat central nervous system. Its natural ligand or role in physiology is unknown due to lack of selective ligands. Its target disruption leads to obesity, diabetes, and hypertension. A synthetic high-affinity agonist, [D-Tyr6,beta-Ala11,Phe13,Nle14]Bn(6-14), has been described, but it is nonselective for hBRS-3 over other Bn receptors; however, substitution of (R)- or (S)-amino-3-phenylpropionic acid (Apa) for beta-Ala11 resulted in a modestly selective ligand. In the present study, we have attempted to develop a more selective hBRS-3 ligand by using two strategies: substitutions on phenyl ring of Apa11 and the substitution of other conformationally restricted amino acids into position 11 of [D-Tyr6,beta-Ala11,Phe13,Nle14]Bn(6-14). Fifteen analogs were synthesized and affinities were determined for hBRS-3 and Bn receptors (hGRP-R and hNMB-R). Selective analogs were tested for their ability to activate each receptor by stimulating phospholipase C. One analog, [D-Tyr6,Apa-4Cl,Phe13,Nle14]Bn(6-14), retained high affinity for the hBRS-3 (Ki=8 nM) and had enhanced selectivity (>230-fold) for hBRS-3 over hGRP-R or hNMB-R. This analog specifically interacted with hBRS-3, fully activated hBRS-3 receptors, and was a potent agonist at the hBRS-3 receptor. This enhanced selectivity should allow this analog to be useful for investigating the possible role of hBRS-3 in physiological or pathological processes.
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Affiliation(s)
- Samuel A Mantey
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bldg. 10, Room 9C-103, 10 Center Dr., MSC 1804, Bethesda, MD 20892-1804l, USA
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Scopinaro F, De Vincentis G, Corazziari E, Massa R, Osti M, Pallotta N, Covotta A, Remediani S, Paolo MD, Monteleone F, Varvarigou A. Detection of Colon Cancer with99mTc-Labeled Bombesin Derivative (99mTc-leu13-BN1). Cancer Biother Radiopharm 2004; 19:245-52. [PMID: 15186605 DOI: 10.1089/108497804323072020] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Breast, prostate, and lung cancer have been successfully detected with 99mTc bombesin (99mTc-leu13-BN1), the radiopharmaceutical that our group developed from synthesis to diagnostic trials. Overexpression of bombesin receptors (BNRs) in colon cancer is well known: the aim of this study was to assess whether or not colon cancer can be detected with a 99mTc-leu13-BN1 scan. Thirteen (13) patients, 7 of whom with known rectal cancer and 6 scheduled to undergo endoscopic removal of polyps for suspicion of colon cancer, were studied with a 99mTc-leu13-BN1 scan. Dynamic, single photon emission computed tomography, and whole-body scans were performed within 1 hour, before discharge of radioactivity from the liver into the duodenum. Sixteen (16) of 17 colorectal cancer locations were detected with a 99mTc-leu13-BN1 scan with 94.1% sensitivity. Six (6) lesions were benign: 1 Crohn's disease, 1 polyp with mild dysplasia, 4 polyps with simple hyperplasia; 99mTc-leu13-BN1 scans were positive in two nontumoral lesions, Crohn's disease, and mild dysplasia and true negative in 4: specificity was 67%. Of the 7 patients with known rectal cancer, 5, who underwent operations instead of radiation therapy, showed lymph-node invasion on 99mTc-leu13-BN1 scans. Operations confirmed the scintigraphic staging. 99mTc-leu13-BN1 is taken up by colon cancer. Scans are sensitive, although scarcely specific. 99mTc-leu13-BN1 allows for node-invasion detection.
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Weber D, Berger C, Eickelmann P, Antel J, Kessler H. Design of selective peptidomimetic agonists for the human orphan receptor BRS-3. J Med Chem 2003; 46:1918-30. [PMID: 12723954 DOI: 10.1021/jm0210921] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New tool substances may help to unravel the physiological role of the human orphan receptor BRS-3 and its possible use as a drug target for the treatment of obesity and cancer. In continuation of our work on BRS-3, the solid- and solution-phase synthesis of a library of low molecular weight peptidomimetic agonists based on the recently developed short peptide agonist 4 is described. Functional potencies of the compounds were determined measuring calcium mobilization in a fluorometric imaging plate reader (FLIPR) assay. Focusing on the N-terminus, the d-Phe-Gln moiety of 4 was modified in a combinatorial SAR-oriented medicinal chemistry approach. With the incorporation of N-arylated glycine and alanine building blocks azaglycine, piperazine, or piperidine and the synthesis of semicarbazides and semicarbazones, a number of highly potent and selective compounds with a reduced number of peptide bonds were obtained, which also should have enhanced metabolic stability.
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Affiliation(s)
- Dirk Weber
- Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
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Biologic relevance of mammalian bombesin-like peptides and their receptors in human malignancies. ACTA ACUST UNITED AC 2003. [DOI: 10.1097/00060793-200302000-00010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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