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Skorik YA, Golyshev AA, Kritchenkov AS, Gasilova ER, Poshina DN, Sivaram AJ, Jayakumar R. Development of drug delivery systems for taxanes using ionic gelation of carboxyacyl derivatives of chitosan. Carbohydr Polym 2017; 162:49-55. [DOI: 10.1016/j.carbpol.2017.01.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/26/2016] [Accepted: 01/05/2017] [Indexed: 11/30/2022]
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Moody TW, Berna MJ, Mantey S, Sancho V, Ridnour L, Wink DA, Chan D, Giaccone G, Jensen RT. Neuromedin B receptors regulate EGF receptor tyrosine phosphorylation in lung cancer cells. Eur J Pharmacol 2010; 637:38-45. [PMID: 20388507 PMCID: PMC3921891 DOI: 10.1016/j.ejphar.2010.03.057] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 03/15/2010] [Accepted: 03/29/2010] [Indexed: 10/19/2022]
Abstract
Neuromedin B (NMB), a member of the bombesin family of peptides, is an autocrine growth factor for many lung cancer cells. The present study investigated the ability of NMB to cause transactivation of the epidermal growth factor (EGF) receptor in lung cancer cells. By Western blot, addition of NMB or related peptides to NCI-H1299 human non-small cell lung cancer (NSCLC) cells, caused phosphorylation of Tyr(1068) of the EGF receptor. The signal was amplified using NCI-H1299 cells stably transected with NMB receptors. The transactivation of the EGF receptor or the tyrosine phosphorylation of ERK caused by NMB-like peptides was inhibited by AG1478 or gefitinib (tyrosine kinase inhibitors) and NMB receptor antagonist PD168368 but not the GRP receptor antagonist, BW2258U89. The transactivation of the EGF receptor caused by NMB-like peptides was inhibited by GM6001 (matrix metalloprotease inhibitor), PP2 (Src inhibitor), or transforming growth factor (TGF)alpha antibody. The transactivation of the EGF receptor and the increase in reactive oxygen species caused by NMB-like peptides was inhibited by N-acetylcysteine (NAC) or Tiron. Gefitinib inhibited the proliferation of NCI-H1299 cells and its sensitivity was increased by the addition of PD168368. The results indicate that the NMB receptor regulates EGF receptor transactivation by a mechanism dependent on Src as well as metalloprotease activation and generation of reactive oxygen species.
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Affiliation(s)
- Terry W Moody
- Department of Health and Human Services, National Cancer Institute, Center for Cancer Research, Office of the Director, Bethesda, Maryland 20892, USA.
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González N, Mantey SA, Pradhan TK, Sancho V, Moody TW, Coy DH, Jensen RT. Characterization of putative GRP- and NMB-receptor antagonist's interaction with human receptors. Peptides 2009; 30:1473-86. [PMID: 19463875 PMCID: PMC2766550 DOI: 10.1016/j.peptides.2009.05.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 05/11/2009] [Accepted: 05/11/2009] [Indexed: 01/08/2023]
Abstract
The mammalian bombesin (Bn) peptides neuromedin B (NMB) and gastrin-releasing peptide (GRP) actions are mediated by two receptors (NMB-receptor, GRP-receptor) which are widely distributed in the GI tract and CNS. From primarily animal studies NMB/GRP-receptor activation has physiological/pathophysiological effects in the CNS and GI tract including stimulating of growth of cancers and normal tissues. Whereas these Bn-receptors' effects have been extensively studied in nonhuman cells and animals, little is known of the physiological/pathological role(s) in humans, largely due to lack of potent antagonists. To address this issue we compared NMB/GRP-receptor affinity/potency of 10 chemical classes of putative antagonists (35 compounds) for human Bn-receptors by performing binding studies or assessing abilities to activate hGRP/hNMB-receptor [assessing phospholipase C activation] in four different cells containing native Bn-receptors or transfected receptors. From binding studies 23 were GRP-receptor-preferring, 4 were NMB-receptor, and 8 nonselective. For the hGRP-receptor-preferring analogues none showed hGRP-receptor agonist activity, but 13 were full or partial hNMB-receptor agonists at hNMB-receptors. For hNMB-receptor-preferring analogues none were agonists. Analogue #24 ([(3-Ph-Pr(6)), His(7), d-Ala(11), d-Pro(13), Psi(13-14), Phe(14)]Bn(6-14)NH2) and analogue #7 [d-Phe(6), Leu(13), Psi(CH(2)NH), Cpa(14)]Bn(6-14) were the most potent (0.2-1.4nM) and selective (>10,000-fold) for the hGRP-receptor with analogue #7.5 [d-Tpi(6), Leu(13), Psi(CH2NH), Leu(14)]Bn(6-14)[RC-3095] (0.2-1.4nM) slightly less selective. Analogue #34 (PD168368) had the highest affinity for hNMB-receptor (1.32-1.58nM) and the greatest selectivity (2298-6952-fold) for the hNMB-receptor. These results demonstrate numerous putative hGRP/hNMB-receptor antagonists identified in nonhuman cells and/or animals have agonist activity at the hNMB-receptor, limiting their potential usefulness. However, a number were identified which were potent/selective for human Bn-receptors and should be useful for investigating their roles in human physiological/pathophysiological conditions.
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Affiliation(s)
- Nieves González
- Digestive Diseases Branch, NIDDK, 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
| | - Tapas K. Pradhan
- Digestive Diseases Branch, NIDDK, and Department of Health and Human
Services, National Institutes of Health, Bethesda, Maryland 20892-1804
| | - 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
| | - 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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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: 394] [Impact Index Per Article: 24.6] [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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Podstawka E. Investigation of molecular structure of bombesin and its modified analogues nonadsorbed and adsorbed on electrochemically roughened silver surface. Biopolymers 2008; 89:506-21. [DOI: 10.1002/bip.20909] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cornelio DB, Roesler R, Schwartsmann G. Gastrin-releasing peptide receptor as a molecular target in experimental anticancer therapy. Ann Oncol 2007; 18:1457-66. [PMID: 17351255 DOI: 10.1093/annonc/mdm058] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Over the last two decades, several lines of experimental evidence have suggested that the gastrin-releasing peptide (GRP) may act as a growth factor in many types of cancer. For that reason, gastrin-releasing peptide receptor (GRPR) antagonists have been developed as anticancer candidate compounds, exhibiting impressive antitumoral activity both in vitro and in vivo in various murine and human tumors. In this article, the GRPR cell surface expression profile in human malignancies is reviewed aiming at the identification of potential tumor types for future clinical trials with GRP analogues and antagonists. In this review, we summarize the current literature regarding the GRPR status in human malignancies. Source data were obtained by searching all published material available through Medline, PubMed and relevant articles from 1971 to 2006. The data available demonstrated a high expression of GRPRs in a large spectrum of human cancers, demonstrating the potential relevance of this intracellular signaling pathway in various human tumor models. The GRPR may be an interesting target for therapeutic intervention in human malignancies, as carriers for cytotoxins, immunotoxins or radioactive compounds, being also a potential tool for tumor detection.
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Affiliation(s)
- D B Cornelio
- Cancer Research Laboratory, Academic Hospital Research Center, Porto Alegre, Brazil
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Ganesh T. Improved biochemical strategies for targeted delivery of taxoids. Bioorg Med Chem 2007; 15:3597-623. [PMID: 17419065 PMCID: PMC2374751 DOI: 10.1016/j.bmc.2007.03.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 03/13/2007] [Accepted: 03/14/2007] [Indexed: 12/21/2022]
Abstract
Paclitaxel (Taxol) and docetaxel (Taxotere) are very important anti-tumor drugs in clinical use for cancer. However, their clinical utility is limited due to systemic toxicity, low solubility and inactivity against drug resistant tumors. To improve chemotherapeutic levels of these drugs, it would be highly desirable to design strategies which bypass the above limitations. In this respect various prodrug and drug targeting strategies have been envisioned either to improve oral bioavailability or tumor specific delivery of taxoids. Abnormal properties of cancer cells with respect to normal cells have guided in designing of these protocols. This review article records the designed biochemical strategies and their biological efficacies as potential taxoid chemotherapeutics.
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Affiliation(s)
- Thota Ganesh
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA 30322, USA.
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Martínez A, Zudaire E, Julián M, Moody TW, Cuttitta F. Gastrin-releasing peptide (GRP) induces angiogenesis and the specific GRP blocker 77427 inhibits tumor growth in vitro and in vivo. Oncogene 2005; 24:4106-13. [PMID: 15750618 DOI: 10.1038/sj.onc.1208581] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Angiogenesis is becoming a major target for antitumor therapies, and identifying new angiogenic factors and their specific inhibitors may provide new avenues for tumor management. Here we identify gastrin-releasing peptide (GRP) as a new angiogenic molecule that is secreted by tumors and acts directly upon GRP receptors in the endothelial cells. Addition of GRP increases endothelial cell migration and cord formation in vitro, and induces angiogenesis in an in vivo assay. We have recently identified a small molecule GRP blocker, compound 77427. This inhibitor significantly reduced endothelial cell cord formation in vitro and angiogenesis in vivo. Conversely, when applied to VEGF-induced angiogenesis, the small molecule did not have any effect, demonstrating its specificity. Furthermore, this GRP blocker was able to reduce lung tumor cell growth in vitro as demonstrated by MTT and clonogenic assays. When applied to a xenograft model with lung cancer cells, compound 77427 reduced tumor volume to undetectable sizes, although when the treatment was suspended, tumors began to grow again at normal rates. Our collective observations indicate that GRP is a new angiogenic peptide and that its inhibition offers an attractive tool to reduce tumor burden.
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Affiliation(s)
- Alfredo Martínez
- Cell and Cancer Biology Branch and Vascular Biology Faculty, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Weber HC, Walters J, Leyton J, Casibang M, Purdom S, Jensen RT, Coy DH, Ellis C, Clark G, Moody TW. A bombesin receptor subtype-3 peptide increases nuclear oncogene expression in a MEK-1 dependent manner in human lung cancer cells. Eur J Pharmacol 2001; 412:13-20. [PMID: 11166731 PMCID: PMC8855643 DOI: 10.1016/s0014-2999(00)00941-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A synthetic peptide, (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was used to investigate the signal transduction mechanisms of bombesin receptor subtype-3. Using NCI-1299#5 human lung cancer cells stably transfected with bombesin receptor subtype-3, 100 nM (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) elevated the cytosolic Ca2+ from 150 to 250 nM within 10 s. Addition of (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused phosphorylation of mitogen activated protein kinase in a time- and concentration-dependent manner. The mitogen activated protein kinase phosphorylation caused by (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was inhibited by 2'-amino-3'-methyoxyflavone (PD98059), a mitogen activated protein kinase kinase (MEK-1) inhibitor. Using a luciferase reporter gene construct, (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused Elk-1 activation after 10 min and the increase in Elk-1 activation caused by (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was inhibited by PD98059 as well as a dominant-negative MEK-1. (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused increased c-fos as well as c-jun mRNAs 1 h after addition to NCI-H1299#5 cells. The 47-fold increase in c-fos mRNA caused by 100 nM (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) was inhibited by PD98059, a dominant-negative MEK-1 and a substance P antagonist but not (3-phenylpropanoyl-D-Ala(24), Pro(26), Psi(26,27), Phe(27))GRP-(20-27) (BW2258U89), a GRP receptor antagonist. These results indicate that (D-Phe(6), beta-Ala(11), Phe(13), Nle(14))bombesin-(6-14) caused increased nuclear oncogene expression and upstream events include mitogen activated protein kinase phosphorylation and Elk-1 activation.
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Affiliation(s)
- H. Christian Weber
- Section of Gastroenterology, Boston University School of Medicine, Boston, MA 02118, USA
| | - James Walters
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
| | - Julius Leyton
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
| | - Marchessini Casibang
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
| | - Sally Purdom
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
| | | | - David H. Coy
- Department of Medicine, Peptide Research Laboratories, Tulane University, New Orleans, LA 701112, USA
| | - Chad Ellis
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
| | - Geoffrey Clark
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
| | - Terry W. Moody
- Medicine Branch, Cell and Cancer Biology Department, NCI, Bldg. KWC, Rm. 300, 9610 Medical Center Drive, Rockville, MD 20850, USA
- Corresponding author. Tel.: +1-301-402-3128, ext. 315; fax: +1-301-402-4422. (T.W. Moody)
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Abstract
(Tyr(0),Bpa(4))bombesin, (YB)BB was synthesized and its biologic activity evaluated using T47D breast cancer cells. ((125)I-Tyr(0), Bpa(4))BB bound with high affinity (K(d) = 5 nM) to T47D cells. Specific ((125)I-Tyr(0),Bpa(4))BB binding was inhibited with high affinity by BB, BW2258U89, GRP, GRP(14-27) and NMB (IC(50) values of 10, 2, 15, 20, and 150 nM)but not GRP(1-16) (IC(50) value of > 1000 nM). ((125)I-Tyr(0),Bpa(4))BB bound to the surface of T47D cells at 4 degrees C but was internalized at 37 degrees C. After binding at 4 degrees C followed by irradiation using ultraviolet light, ((125)I-Tyr(0),Bpa(4))BB labeled a 75 kDa protein using T47D cells. (Tyr(0),Bpa(4))BB, 10 nM, elevated cytosolic calcium using T47D cells within 10 s. Also (Tyr(0),Bpa(4))BB, 10 nM, elevated c-fos mRNA after 45 min. These results indicate that (Tyr(0),Bpa(4))BB is an agonist for GRP receptors.
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Affiliation(s)
- M Casibang
- Cell and Cancer Biology Department, Medicine Branch, National Cancer Institute, Bldg. KWC, Rm. 300, 9610 Medical Ctr. Dr., 20850, Rockville, MD 20850, USA
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Abstract
BW2258U89 is a gastrin releasing peptide (GRP) receptor antagonist which inhibits the proliferation of the neuroendocrine tumor small cell lung cancer (SCLC). Here the biological activity of BW2258U89 and its metabolite were investigated. Using mass spectroscopy (LC-ESI/MS) techniques, three major peaks for BW2258U89 were observed with mass/charge (m/z) ratios of 1081.6, 541.4 and 361.4. After metabolism by mouse plasma enzymes, the major product had a m/z ratio of 1082.5, 541.9 and 361.8 suggesting that BW2258U89 was deamidated. Deamidated (Da) BW2258U89 was synthesized and it inhibited ((125)I-Tyr(4)) BB binding to NCI-H345 SCLC cells with an IC(50)value of 450 nM; BW2258U89 had an IC(50)value of 17 nM. BW2258U89 (1 microM) antagonized the ability of 50 nM BB to elevate cytosolic Ca(2+)in NCI-H345 cells, whereas 1 microM (Da) BW2258U89 did not. One micromolar BW2258U89 antagonized the increase in NCI-H345 c-fos mRNA caused by 10 nM BB, whereas 1 microM (Da) BW2258U89 had little effect. One microM BW2258U89 inhibited NCI-H345 clonal growth significantly whereas 1 microM (Da) BW2258U89 did not. These data suggest that an amidated C-terminal is important for antagonism of SCLC GRP receptors by BW2258U89.
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Affiliation(s)
- C Marquez
- Cell and Cancer Biology Department, Medicine Branch, National Cancer Institute, Rockville, MD 20876 USA
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Pradhan TK, Katsuno T, Taylor JE, Kim SH, Ryan RR, Mantey SA, Donohue PJ, Weber HC, Sainz E, Battey JF, Coy DH, Jensen RT. Identification of a unique ligand which has high affinity for all four bombesin receptor subtypes. Eur J Pharmacol 1998; 343:275-87. [PMID: 9570477 DOI: 10.1016/s0014-2999(97)01527-6] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Four subtypes of bombesin receptors are identified (gastrin-releasing peptide receptor, neuromedin B receptor, the orphan receptor bombesin receptor subtype 3 (BB3 or BRS-3) and bombesin receptor subtype 4 (BB4)), however, only the pharmacology of the gastrin-releasing peptide receptor has been well studied. This lack of data is due in part to the absence of a general ligand. Recently we have discovered a ligand, 125I-[D-Tyr6,betaAla11,Phe13,Nle14]bombesin-(6-1 4) that binds to BRS-3 receptors. In this study we investigate its ability to interact with all four bombesin receptor subtypes. In rat pancreatic acini containing only gastrin-releasing peptide receptor and in BB4 transfected BALB cells, this ligand and 125I-[Tyr4]bombesin, the conventional gastrin-releasing peptide receptor ligand, gave similar results for receptor number, affinity for bombesin and affinity for the unlabeled ligand. In neuromedin B receptor transfected BALB cells, this ligand and 125I-[D-Tyr0]neuromedin B, the generally used neuromedin B receptor ligand, gave similar results for receptor number, neuromedin B affinity or the unlabeled ligand affinity. Lastly, in BRS-3 transfected BALB cells, only this ligand had high affinity. For all four bombesin receptors this ligand had an affinity of 1-8 nM and was equal or greater in affinity than any other specific ligands for any receptor. The unlabeled ligand is specific for gastrin-releasing peptide receptors on rat pancreatic acini and did not inhibit binding of 125I-cholecystokinin octapeptide (125I-CCK-8), 125I-vasoactive intestinal peptide (125I-VIP) or 125I-endothelin to their receptors. The unlabeled ligand was an agonist only at the gastrin-releasing peptide receptor in rat acini and did not interact with CCK(A) receptors or muscarinic M3 acetylcholine receptors to increase [3H]inositol phosphates. These results demonstrate 125I-[D-Tyr6,betaAla11,Phe13,Nle14]bombesin-(6-1 4) is a unique ligand with high affinity for all subtypes of bombesin receptors. Because of the specificity for bombesin receptors, this ligand will be a valuable addition for such pharmacological studies as screening for bombesin receptor agonists or antagonists and, in particular, for investigating BRS-3 cell biology, a receptor for which no ligand currently exists.
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Affiliation(s)
- T K Pradhan
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
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