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Abstract
Development of new radiopharmaceuticals and their availability are crucial factors influencing the expansion of clinical nuclear medicine. The number of new (68)Ga-based imaging agents for positron emission tomography (PET) is increasing greatly. (68)Ga has been used for labeling of a broad range of molecules (small organic molecules, peptides, proteins, and oligonucleotides) as well as particles, thus demonstrating its potential to become a PET analog of the legendary generator-produced gamma-emitting (99m)Tc but with added value of higher sensitivity and resolution as well as quantitation and dynamic scanning. Further, the availability of technology for GMP-compliant automated tracer production can facilitate the introduction of new radiopharmaceuticals and enable standardized, harmonized multicenter studies to be conducted for regulatory approval. This chapter presents some examples of tracers for targeted, pretargeted, and nontargeted imaging with emphasis on the potential of (68)Ga to facilitate clinically practical PET development and to promote the PET technique worldwide for earlier and better diagnostics, and personalized medicine with the ultimate objective of improved therapeutic outcome.
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Affiliation(s)
- Irina Velikyan
- Department of Radiology, Uppsala University, Uppsala, Sweden.
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van Vliet EI, Teunissen JJM, Kam BLR, de Jong M, Krenning EP, Kwekkeboom DJ. Treatment of gastroenteropancreatic neuroendocrine tumors with peptide receptor radionuclide therapy. Neuroendocrinology 2013; 97:74-85. [PMID: 22237390 DOI: 10.1159/000335018] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 11/14/2011] [Indexed: 12/25/2022]
Abstract
The primary treatment of gastroenteropancreatic neuroendocrine tumors (GEPNETs) is surgery with curative intent or debulking of the tumor mass. In case of metastatic disease, cytoreductive options are limited. A relatively new therapeutic modality, peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin analogs, is currently available in a number of mostly European centers. Complete and partial responses obtained after treatment with [90Y-DOTA0,Tyr3]octreotide are in the same range as after treatment with [177Lu-DOTA0,Tyr3]octreotate (i.e. 10-30%). However, significant nephrotoxicity has been observed after treatment with [90Y-DOTA0,Tyr3]octreotide. Options to improve PRRT may include combinations of radioactive labeled somatostatin analogs, intra-arterial administration, and the use of radiosensitizing drugs combined with PRRT. Other therapeutic applications of PRRT may include additional therapy cycles in patients with progressive disease after benefit from initial therapy, PRRT in adjuvant or neoadjuvant setting, or PRRT combined with new targeted therapies, such as sunitinib or everolimus. Randomized clinical trials comparing PRRT with other treatment modalities, or comparing various radioactive labeled somatostatin analogs should be undertaken to determine the best treatment options and treatment sequelae for patients with GEPNETs.
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Affiliation(s)
- Esther I van Vliet
- Department of Nuclear Medicine, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
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Abstract
Single photon emission computed tomography (SPECT) is the state-of-the-art imaging modality in nuclear medicine despite the fact that only a few new SPECT tracers have become available in the past 20 years. Critical for the future success of SPECT is the design of new and specific tracers for the detection, localization, and staging of a disease and for monitoring therapy. The utility of SPECT imaging to address oncologic questions is dependent on radiotracers that ideally exhibit excellent tissue penetration, high affinity to the tumor-associated target structure, specific uptake and retention in the malignant lesions, and rapid clearance from non-targeted tissues and organs. In general, a target-specific SPECT radiopharmaceutical can be divided into two main parts: a targeting biomolecule (e.g. peptide, antibody fragment) and a γ-radiation emitting radionuclide (e.g. (99m)Tc, (123)I). If radiometals are used as the radiation source, a bifunctional chelator is needed to link the radioisotope to the targeting entity. In a rational SPECT tracer design these single components have to be critically evaluated in order to achieve a balance among the demands for adequate target binding, and a rapid clearance of the radiotracer. The focus of this chapter is to depict recent developments of tumor-targeted SPECT radiotracers for imaging of cancer diseases. Possibilities for optimization of tracer design and potential causes for design failure are discussed and highlighted with selected examples.
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Affiliation(s)
- Cristina Müller
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Paul Scherrer Institute, Villigen-PSI, Switzerland.
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Wang X, Fani M, Schulz S, Rivier J, Reubi JC, Maecke HR. Comprehensive evaluation of a somatostatin-based radiolabelled antagonist for diagnostic imaging and radionuclide therapy. Eur J Nucl Med Mol Imaging 2012; 39:1876-85. [DOI: 10.1007/s00259-012-2231-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 08/09/2012] [Indexed: 11/24/2022]
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55
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Fani M, Braun F, Waser B, Beetschen K, Cescato R, Erchegyi J, Rivier JE, Weber WA, Maecke HR, Reubi JC. Unexpected Sensitivity of sst2 Antagonists to N-Terminal Radiometal Modifications. J Nucl Med 2012; 53:1481-9. [DOI: 10.2967/jnumed.112.102764] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Fani M, Maecke HR. Radiopharmaceutical development of radiolabelled peptides. Eur J Nucl Med Mol Imaging 2012; 39 Suppl 1:S11-30. [PMID: 22388624 DOI: 10.1007/s00259-011-2001-z] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Receptor targeting with radiolabelled peptides has become very important in nuclear medicine and oncology in the past few years. The overexpression of many peptide receptors in numerous cancers, compared to their relatively low density in physiological organs, represents the molecular basis for in vivo imaging and targeted radionuclide therapy with radiolabelled peptide-based probes. The prototypes are analogs of somatostatin which are routinely used in the clinic. More recent developments include somatostatin analogs with a broader receptor subtype profile or with antagonistic properties. Many other peptide families such as bombesin, cholecystokinin/gastrin, glucagon-like peptide-1 (GLP-1)/exendin, arginine-glycine-aspartic acid (RGD) etc. have been explored during the last few years and quite a number of potential radiolabelled probes have been derived from them. On the other hand, a variety of strategies and optimized protocols for efficient labelling of peptides with clinically relevant radionuclides such as (99m)Tc, M(3+) radiometals ((111)In, (86/90)Y, (177)Lu, (67/68)Ga), (64/67)Cu, (18)F or radioisotopes of iodine have been developed. The labelling approaches include direct labelling, the use of bifunctional chelators or prosthetic groups. The choice of the labelling approach is driven by the nature and the chemical properties of the radionuclide. Additionally, chemical strategies, including modification of the amino acid sequence and introduction of linkers/spacers with different characteristics, have been explored for the improvement of the overall performance of the radiopeptides, e.g. metabolic stability and pharmacokinetics. Herein, we discuss the development of peptides as radiopharmaceuticals starting from the choice of the labelling method and the conditions to the design and optimization of the peptide probe, as well as some recent developments, focusing on a selected list of peptide families, including somatostatin, bombesin, cholecystokinin/gastrin, GLP-1/exendin and RGD.
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Affiliation(s)
- Melpomeni Fani
- Department of Nuclear Medicine, University Hospital Freiburg, Hugstetterstrasse 55, 79106 Freiburg, Germany.
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Tatsi A, Maina T, Cescato R, Waser B, Krenning EP, de Jong M, Cordopatis P, Reubi JC, Nock BA. [111In-DOTA]Somatostatin-14 analogs as potential pansomatostatin-like radiotracers - first results of a preclinical study. EJNMMI Res 2012; 2:25. [PMID: 22682002 PMCID: PMC3407795 DOI: 10.1186/2191-219x-2-25] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 06/09/2012] [Indexed: 02/04/2023] Open
Abstract
Background In this study, we report on the synthesis, radiolabeling, and biological evaluation of two new somatostatin-14 (SS14) analogs, modified with the universal chelator DOTA. We were interested to investigate if and to what extent such radiotracer prototypes may be useful for targeting sst1-5-expressing tumors in man but, most importantly, to outline potential drawbacks and benefits associated with their use. Methods AT1S and AT2S (DOTA-Ala1-Gly2-c[Cys3-Lys4-Asn5-Phe6-Phe7-Trp8/DTrp8-Lys9-Thr10-Phe11-Thr12-Ser13-Cys14-OH], respectively) were synthesized on the solid support and labeled with 111In. The sst1-5 affinity profile of AT1S/AT2S was determined by receptor autoradiography using [Leu8,dTrp22,125I-Tyr25]SS28 as radioligand. The ability of AT2S to stimulate sst2 or sst3 internalization was qualitatively analyzed by an immunofluorescence-based internalization assay using hsst2- or hsst3-expressing HEK293 cells. Furthermore, the internalization of the radioligands [111In]AT1S and [111In]AT2S was studied at 37 °C in AR4-2J cells endogenously expressing sst2. The in vivo stability of [111In]AT1S and [111In]AT2S was tested by high-performance liquid chromatography analysis of mouse blood collected 5 min after radioligand injection, and biodistribution was studied in normal mice. Selectively for [111In]AT2S, biodistribution was further studied in SCID mice bearing AR4-2J, HEK293-hsst2A+, -hsst3+ or -hsst5+ tumors. Results The new SS14-derived analogs were obtained by solid phase peptide synthesis and were easily labeled with 111In. Both SS14 conjugates, AT1S, and its DTrp8 counterpart, AT2S, showed a pansomatostatin affinity profile with the respective hsst1-5 IC50 values in the lower nanomolar range. In addition, AT2S behaved as an agonist for sst2 and sst3 since it stimulated receptor internalization. The 111In radioligands effectively and specifically internalized into rsst2A-expressing AR4-2J cells with [111In]AT2S internalizing faster than [111In]AT1S. Ex vivo mouse blood analysis revealed a rapid degradation of both radiopeptides in the bloodstream with the DTrp8 analog showing higher stability. Biodistribution results in healthy mice were consistent with these findings with only [111In]AT2S showing specific uptake in the sst2-rich pancreas. Biodistribution of [111In]AT2S in tumor-bearing mice revealed receptor-mediated uptake in the AR4-2J (1.82 ± 0.36 %ID/g - block 0.21 ± 0.17 %ID/g at 4 h post injection (pi)), the HEK293-hsst2A+ (1.49 ± 0.2 %ID/g - block 0.27 ± 0.20 %ID/g at 4 h pi), the HEK293-hsst3+ (1.24 ± 0.27 %ID/g - block 0.32 ± 0.06 %ID/g at 4 h pi), and the HEK293-hsst5+ tumors (0.41 ± 0.12 %ID/g - block 0.22 ± 0.006 %ID/g at 4 h pi). Radioactivity washed out from blood and background tissues via the kidneys. Conclusions This study has revealed that the native SS14 structure can indeed serve as a motif for the development of promising pansomatostatin-like radiotracers. Further peptide stabilization is required to increase in vivo stability and, consequently, to enhance in vivo delivery and tumor targeting.
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Affiliation(s)
- Aikaterini Tatsi
- Molecular Radiopharmacy, Institute of Radioisotopes - Radiodiagnostic Products, National Center for Scientific Research "Demokritos", 153 10 Ag, Paraskevi Attikis, Athens, GR-153 10, Greece.
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Stengel A, Taché Y. Activation of somatostatin 2 receptors in the brain and the periphery induces opposite changes in circulating ghrelin levels: functional implications. Front Endocrinol (Lausanne) 2012; 3:178. [PMID: 23335913 PMCID: PMC3542632 DOI: 10.3389/fendo.2012.00178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 12/17/2012] [Indexed: 12/26/2022] Open
Abstract
Somatostatin is an important modulator of neurotransmission in the central nervous system and acts as a potent inhibitor of hormone and exocrine secretion and regulator of cell proliferation in the periphery. These pleiotropic actions occur through interaction with five G protein-coupled somatostatin receptor subtypes (sst(1) (-) (5)) that are widely expressed in the brain and peripheral organs. The characterization of somatostatin's effects can be investigated by pharmacological or genetic approaches using newly developed selective sst agonists and antagonists and mice lacking specific sst subtypes. Recent evidence points toward a divergent action of somatostatin in the brain and in the periphery to regulate circulating levels of ghrelin, an orexigenic hormone produced by the endocrine X/A-like cells in the rat gastric mucosa. Somatostatin interacts with the sst(2) in the brain to induce an increase in basal ghrelin plasma levels and counteracts the visceral stress-related decrease in circulating ghrelin. By contrast, stimulation of peripheral somatostatin-sst(2) signaling results in the inhibition of basal ghrelin release and mediates the postoperative decrease in circulating ghrelin. The peripheral sst(2)-mediated reduction of plasma ghrelin is likely to involve a paracrine action of D cell-derived somatostatin acting on sst(2) bearing X/A-like ghrelin cells in the gastric mucosa. The other member of the somatostatin family, named cortistatin, in addition to binding to sst(1) (-) (5) also directly interacts with the ghrelin receptor and therefore may simultaneously modulate ghrelin release and actions at target sites bearing ghrelin receptors representing a link between the ghrelin and somatostatin systems.
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Affiliation(s)
- Andreas Stengel
- Division Psychosomatic Medicine and Psychotherapy, Department of Medicine, Obesity Center Berlin, Charité, Universitätsmedizin BerlinBerlin, Germany
- *Correspondence: Andreas Stengel, Division Psychosomatic Medicine and Psychotherapy, Department of Medicine, Obesity Center Berlin, Charité, Universitätsmedizin Berlin, Luisenstr. 13a, 10117 Berlin, Germany. e-mail: ; Yvette Taché, Digestive Diseases Division, CURE: Digestive Diseases Research Center, Center for Neurobiology of Stress and Women’s Health, Department of Medicine, VA Greater Los Angeles Health Care System, University of California at Los Angeles, CURE Building 115, Room 117, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA. e-mail:
| | - Yvette Taché
- Digestive Diseases Division, CURE: Digestive Diseases Research Center, Center for Neurobiology of Stress and Women’s Health, Department of Medicine, VA Greater Los Angeles Health Care System, University of California at Los AngelesLos Angeles, CA, USA
- *Correspondence: Andreas Stengel, Division Psychosomatic Medicine and Psychotherapy, Department of Medicine, Obesity Center Berlin, Charité, Universitätsmedizin Berlin, Luisenstr. 13a, 10117 Berlin, Germany. e-mail: ; Yvette Taché, Digestive Diseases Division, CURE: Digestive Diseases Research Center, Center for Neurobiology of Stress and Women’s Health, Department of Medicine, VA Greater Los Angeles Health Care System, University of California at Los Angeles, CURE Building 115, Room 117, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA. e-mail:
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Cescato R, Waser B, Fani M, Reubi JC. Evaluation of 177Lu-DOTA-sst2 Antagonist Versus 177Lu-DOTA-sst2 Agonist Binding in Human Cancers In Vitro. J Nucl Med 2011; 52:1886-90. [DOI: 10.2967/jnumed.111.095778] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Erchegyi J, Cescato R, Waser B, Rivier JE, Reubi JC. N-imidazolebenzyl-histidine substitution in somatostatin and in its octapeptide analogue modulates receptor selectivity and function. J Med Chem 2011; 54:5981-7. [PMID: 21806016 DOI: 10.1021/jm200307v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Despite 3 decades of focused chemical, biological, structural, and clinical developments, unusual properties of somatostatin (SRIF, 1) analogues are still being uncovered. Here we report the unexpected functional properties of 1 and the octapeptide cyclo(3-14)H-Cys-Phe-Phe-Trp(8)-Lys-Thr-Phe-Cys-OH (somatostatin numbering; OLT-8, 9) substituted by imBzl-l- or -d-His at position 8. These analogues were tested for their binding affinity to the five human somatostatin receptors (sst(1-5)), as well as for their functional properties (or functionalities) in an sst(3) internalization assay and in an sst(3) luciferase reporter gene assay. While substitution of Trp(8) in somatostatin by imBzl-l- or -d-His(8) results in sst(3) selectivity, substitution of Trp(8) in the octapeptide 9 by imBzl-l- or -d-His(8) results in loss of binding affinity for sst(1,2,4,5) and a radical functional switch from agonist to antagonist.
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Affiliation(s)
- Judit Erchegyi
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, 10010 N. Torrey Pines Road, La Jolla, California 92037, USA
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Stengel A, Goebel-Stengel M, Wang L, Shaikh A, Lambrecht NWG, Rivier J, Taché Y. Abdominal surgery inhibits circulating acyl ghrelin and ghrelin-O-acyltransferase levels in rats: role of the somatostatin receptor subtype 2. Am J Physiol Gastrointest Liver Physiol 2011; 301:G239-48. [PMID: 21636529 PMCID: PMC3154605 DOI: 10.1152/ajpgi.00018.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Clinical studies are evaluating the efficacy of synthetic ghrelin agonists in postoperative ileus management. However, the control of ghrelin secretion under conditions of postoperative gastric ileus is largely unknown. Peripheral somatostatin inhibits ghrelin secretion in animals and humans. We investigated the time course of ghrelin changes postsurgery in fasted rats and whether somatostatin receptor subtype 2 (sst(2)) signaling is involved. Abdominal surgery (laparotomy and 1-min cecal palpation) induced a rapid and long-lasting decrease in plasma acyl ghrelin levels as shown by the 64, 67, and 59% reduction at 0.5, 2, and 5 h postsurgery, respectively, compared with sham (anesthesia alone for 10 min, P < 0.05). Levels were partly recovered at 7 h and fully restored at 24 h. The percentage of acyl ghrelin reduction was significantly higher than that of desacyl ghrelin at 2 h postsurgery and not at any other time point. This was associated with a 48 and 23% decrease in gastric and plasma ghrelin-O-acyltransferase protein concentrations, respectively (P < 0.001). Ghrelin-positive cells in the oxyntic mucosa expressed sst(2a) receptor and the sst(2) agonist S-346-011 inhibited fasting acyl ghrelin levels by 64 and 77% at 0.5 and 2 h, respectively. The sst(2) antagonist S-406-028 prevented the abdominal surgery-induced decreased circulating acyl ghrelin but not the delayed gastric emptying assessed 0.5 h postinjection. These data show that activation of sst(2) receptor located on gastric X/A-like cells plays a key role in the rapid inhibition of circulating acyl ghrelin induced by abdominal surgery while not being primarily involved in the early phase of postoperative gastric ileus.
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Affiliation(s)
- Andreas Stengel
- 1Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles;
| | - Miriam Goebel-Stengel
- 1Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles;
| | - Lixin Wang
- 1Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles;
| | - Almaas Shaikh
- 1Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles;
| | - Nils W. G. Lambrecht
- 2Gastrointestinal Endocrinology, Veterans Affairs Long Beach Healthcare System, Long Beach; and
| | - Jean Rivier
- 3Peptide Biology Laboratories, Salk Institute, La Jolla, California
| | - Yvette Taché
- 1Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles;
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Fani M, Del Pozzo L, Abiraj K, Mansi R, Tamma ML, Cescato R, Waser B, Weber WA, Reubi JC, Maecke HR. PET of Somatostatin Receptor–Positive Tumors Using 64Cu- and 68Ga-Somatostatin Antagonists: The Chelate Makes the Difference. J Nucl Med 2011; 52:1110-8. [DOI: 10.2967/jnumed.111.087999] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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STENGEL A, GOEBEL-STENGEL M, WANG L, LARAUCHE M, RIVIER J, TACHÉ Y. Central somatostatin receptor 1 activation reverses acute stress-related alterations of gastric and colonic motor function in mice. Neurogastroenterol Motil 2011; 23:e223-36. [PMID: 21564422 PMCID: PMC3683311 DOI: 10.1111/j.1365-2982.2011.01706.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Corticotropin-releasing factor (CRF) signaling induced by stress is well established to delay gastric emptying (GE) and stimulate colonic functions. The somatostatin receptor (sst(1-5) ) agonist, ODT8-SST acts in the brain to inhibit stress-induced adrenocorticotropic hormone and epinephrine secretion. We investigated whether ODT8-SST acts in the brain to influence stress-related alterations of gastric and colonic motor function and sst receptor subtype(s) involved. METHODS Peptides were injected intracerebroventricularly (i.c.v.) under short isoflurane anesthesia and GE, fecal pellet output (FPO) and distal colonic motility monitored in conscious mice. KEY RESULTS The stress of acute anesthesia/vehicle i.c.v. injection reduced GE by 67% and increased defecation by 99% compared to non-injected controls. Both responses were abolished by ODT8-SST (1μg= 0.75nmol) or sst(1) agonist (0.65-1.95nmol). The sst(1) agonist (1.95nmol) also prevented the abdominal surgery-induced delayed GE. Octreotide (sst(2) >sst(5) > sst(3) ) and the sst(2) or sst(4) agonists (1μg=0.78 or 0.70nmol, respectively) injected i.c.v. did not influence FPO while i.c.v. somatostatin-28 mimicked ODT8-SST's effect. The ODT8-SST-induced increased food intake was inhibited by i.c.v. sst(2) antagonist while the reduced FPO was unchanged. ODT8-SST i.c.v. reduced distal colonic motility in semi-restrained mice compared with vehicle and blocked water avoidance- and i.c.v. CRF (0.5μg=0.09nmol)-induced stimulated FPO while a similar colonic secretomotor response to i.p. 5-hydroxytryptophane (10mgkg(-1) =36.4μmol kg(-1) ) was unaltered. Conclusions & Inferences ODT8-SST counteracts stress/i.c.v. CRF-related stimulation of colonic motor function and delayed GE which can be reproduced mainly by activation of sst(1) receptors. These data opens new insight to brain somatostatinergic signaling pathways interfering with brain circuitries involved in gut motor responses to acute stress.
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Affiliation(s)
- A. STENGEL
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - M. GOEBEL-STENGEL
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - L. WANG
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - M. LARAUCHE
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - J. RIVIER
- Peptide Biology Laboratories, Salk Institute, La Jolla, CA, USA
| | - Y. TACHÉ
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
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Maecke HR, Reubi JC. Somatostatin receptors as targets for nuclear medicine imaging and radionuclide treatment. J Nucl Med 2011; 52:841-4. [PMID: 21571797 DOI: 10.2967/jnumed.110.084236] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Radiolabeled peptides have been an important class of compounds in radiopharmaceutical sciences and nuclear medicine for more than 20 years. Despite strong research efforts, only somatostatin-based radiopeptides have a real impact on patient care, diagnostically and therapeutically. [(111)In-diethylenetriaminepentaacetic acid(0)]octreotide is commercially available for imaging. Imaging was highly improved by the introduction of PET radionuclides such as (68)Ga, (64)Cu, and (18)F. Two peptides are successfully used in targeted radionuclide therapy when bound to DOTA and labeled with (90)Y and (177)Lu.
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Affiliation(s)
- Helmut R Maecke
- Department of Nuclear Medicine, University Hospital Freiburg, Freiburg, Germany.
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Seebach D, Lukaszuk A, Patora-Komisarska K, Podwysocka D, Gardiner J, Ebert MO, Reubi JC, Cescato R, Waser B, Gmeiner P, Hübner H, Rougeot C. On the Terminal Homologation of Physiologically Active Peptides as a Means of Increasing Stability in Human Serum - Neurotensin, Opiorphin, B27-KK10 Epitope, NPY. Chem Biodivers 2011; 8:711-39. [DOI: 10.1002/cbdv.201100093] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Chen K, Chen X. Design and development of molecular imaging probes. Curr Top Med Chem 2011; 10:1227-36. [PMID: 20388106 DOI: 10.2174/156802610791384225] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 02/27/2010] [Indexed: 01/17/2023]
Abstract
Molecular imaging, the visualization, characterization and measurement of biological processes at the cellular, subcellular level, or even molecular level in living subjects, has rapidly gained importance in the dawning era of personalized medicine. Molecular imaging takes advantage of the traditional diagnostic imaging techniques and introduces molecular imaging probes to determine the expression of indicative molecular markers at different stages of diseases and disorders. As a key component of molecular imaging, molecular imaging probe must be able to specifically reach the target of interest in vivo while retaining long enough to be detected. A desirable molecular imaging probe with clinical translation potential is expected to have unique characteristics. Therefore, design and development of molecular imaging probe is frequently a challenging endeavor for medicinal chemists. This review summarizes the general principles of molecular imaging probe design and some fundamental strategies of molecular imaging probe development with a number of illustrative examples.
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Affiliation(s)
- Kai Chen
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, USA.
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Wängler C, Waser B, Alke A, Iovkova L, Buchholz HG, Niedermoser S, Jurkschat K, Fottner C, Bartenstein P, Schirrmacher R, Reubi JC, Wester HJ, Wängler B. One-Step 18F-Labeling of Carbohydrate-Conjugated Octreotate-Derivatives Containing a Silicon-Fluoride-Acceptor (SiFA): In Vitro and in Vivo Evaluation as Tumor Imaging Agents for Positron Emission Tomography (PET). Bioconjug Chem 2010; 21:2289-96. [DOI: 10.1021/bc100316c] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Carmen Wängler
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Beatrice Waser
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Andrea Alke
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Ljuba Iovkova
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Hans-Georg Buchholz
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Sabrina Niedermoser
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Klaus Jurkschat
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Christian Fottner
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Peter Bartenstein
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Ralf Schirrmacher
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Jean-Claude Reubi
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Hans-Jürgen Wester
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Björn Wängler
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany, Institute of Pathology, University of Berne, Berne, Switzerland, Department of Nuclear Medicine, Technical University Munich, Munich, Germany, Department of Inorganic Chemistry II, University of Dortmund, Dortmund, Germany, Department of Nuclear Medicine and I. Medical Clinic, University of Mainz, Germany, and McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Canada
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Fani M, Mueller A, Tamma ML, Nicolas G, Rink HR, Cescato R, Reubi JC, Maecke HR. Radiolabeled Bicyclic Somatostatin-Based Analogs: A Novel Class of Potential Radiotracers for SPECT/PET of Neuroendocrine Tumors. J Nucl Med 2010; 51:1771-9. [DOI: 10.2967/jnumed.110.076695] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Waser B, Cescato R, Tamma ML, Maecke HR, Reubi JC. Absence of somatostatin SST2 receptor internalization in vivo after intravenous SOM230 application in the AR42J animal tumor model. Eur J Pharmacol 2010; 644:257-62. [DOI: 10.1016/j.ejphar.2010.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 07/01/2010] [Accepted: 07/09/2010] [Indexed: 12/19/2022]
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Stengel A, Coskun T, Goebel M, Wang L, Craft L, Alsina-Fernandez J, Rivier J, Taché Y. Central injection of the stable somatostatin analog ODT8-SST induces a somatostatin2 receptor-mediated orexigenic effect: role of neuropeptide Y and opioid signaling pathways in rats. Endocrinology 2010; 151:4224-35. [PMID: 20610566 PMCID: PMC2940496 DOI: 10.1210/en.2010-0195] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Somatostatin and octreotide injected into the brain have been reported to modulate food intake. However, little is known regarding the underlying mechanisms. The stable oligosomatostatin analog, des-AA(1,2,4,5,12,13)-[DTrp(8)]-somatostatin (ODT8-SST), like somatostatin, binds to all five somatostatin receptors (sst(1-5)). We characterized the effects of ODT8-SST injected intracerebroventricularly (i.c.v.) on food consumption and related mechanisms of action in freely fed rats. ODT8-SST (0.3 and 1 microg per rat, i.c.v.) injected during the light or dark phase induced an early onset (within 1 h) and long-lasting (4 h) increase in food intake in nonfasted rats. By contrast, i.p. injection (0.3-3 mg/kg) or i.c.v. injection of selective sst(1) or sst(4) agonists (1 microg per rat) had no effect. The 2 h food intake response during the light phase was blocked by i.c.v. injection of a sst(2) antagonist, the neuropeptide Y (NPY) Y(1) receptor antagonist, BIBP-3226, and ip injection of the mu-opioid receptor antagonist, naloxone, and not associated with changes in plasma ghrelin levels. ODT8-SST (1 microg per rat, i.c.v.) stimulated gastric emptying of a solid meal which was also blocked by naloxone. The increased food intake was accompanied by a sustained increase in respiratory quotient, energy expenditure, and drinking as well as mu-opioid receptor-independent grooming behavior and hyperthermia, while ambulatory movements were not altered after ODT8-SST (1 microg per rat, i.c.v.). These data show that ODT8-SST acts primarily through brain sst(2) receptors to induce a long-lasting orexigenic effect that involves the activation of Y(1) and opiate-receptors, accompanied by enhanced gastric transit and energy expenditure suggesting a modulation of NPYergic and opioidergic orexigenic systems by brain sst(2) receptors.
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MESH Headings
- Animals
- Anti-Anxiety Agents/administration & dosage
- Anti-Anxiety Agents/pharmacology
- Arginine/administration & dosage
- Arginine/analogs & derivatives
- Arginine/pharmacology
- Body Temperature/drug effects
- Eating/drug effects
- Eating/physiology
- Energy Metabolism/drug effects
- Gastric Emptying/drug effects
- Grooming/drug effects
- Injections, Intraperitoneal
- Injections, Intraventricular
- Male
- Mice
- Mice, Inbred C57BL
- Naloxone/administration & dosage
- Naloxone/pharmacology
- Peptide Fragments/administration & dosage
- Peptide Fragments/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Neuropeptide Y/antagonists & inhibitors
- Receptors, Neuropeptide Y/physiology
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/physiology
- Receptors, Somatostatin/agonists
- Receptors, Somatostatin/antagonists & inhibitors
- Receptors, Somatostatin/physiology
- Somatostatin/administration & dosage
- Somatostatin/analogs & derivatives
- Somatostatin/pharmacology
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Affiliation(s)
- Andreas Stengel
- Department of Medicine, Center for Ulcer Research and Education, Digestive Diseases Division, University of California Los Angeles, and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA
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71
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Oberg KE, Reubi JC, Kwekkeboom DJ, Krenning EP. Role of somatostatins in gastroenteropancreatic neuroendocrine tumor development and therapy. Gastroenterology 2010; 139:742-53, 753.e1. [PMID: 20637207 DOI: 10.1053/j.gastro.2010.07.002] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 07/06/2010] [Accepted: 07/08/2010] [Indexed: 12/02/2022]
Abstract
The incidence and prevalence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) have increased in the past 20 years. GEP-NETs are heterogeneous tumors, in terms of clinical and biological features, that originate from the pancreas or the intestinal tract. Some GEP-NETs grow very slowly, some grow rapidly and do not cause symptoms, and others cause hormone hypersecretion and associated symptoms. Most GEP-NETs overexpress receptors for somatostatins. Somatostatins inhibit the release of many hormones and other secretory proteins; their effects are mediated by G protein-coupled receptors that are expressed in a tissue-specific manner. Most GEP-NETs overexpress the somatostatin receptor SSTR2; somatostatin analogues are the best therapeutic option for functional neuroendocrine tumors because they reduce hormone-related symptoms and also have antitumor effects. Long-acting formulations of somatostatin analogues stabilize tumor growth over long periods. The development of radioactive analogues for imaging and peptide receptor radiotherapy has improved the management of GEP-NETs. Peptide receptor radiotherapy has significant antitumor effects, increasing overall survival times of patients with tumors that express a high density of SSTRs, particularly SSTR2 and SSTR5. The multi-receptor somatostatin analogue SOM230 (pasireotide) and chimeric molecules that bind SSTR2 and the dopamine receptor D2 are also being developed to treat patients with GEP-NETs. Combinations of radioactive labeled and unlabeled somatostatin analogues and therapeutics that inhibit other signaling pathways, such as mammalian target of rapamycin (mTOR) and vascular endothelial growth factor, might be the most effective therapeutics for GEP-NETs.
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Affiliation(s)
- Kjell E Oberg
- Department of Endocrine Oncology, University Hospital, Uppsala, Sweden.
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72
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Chen K, Conti PS. Target-specific delivery of peptide-based probes for PET imaging. Adv Drug Deliv Rev 2010; 62:1005-22. [PMID: 20851156 DOI: 10.1016/j.addr.2010.09.004] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/08/2010] [Accepted: 09/08/2010] [Indexed: 12/19/2022]
Abstract
Positron emission tomography (PET) is one of the most rapidly growing areas of medical imaging, with many applications in the clinical management of patients with various diseases. The principal goal of PET imaging is to visualize, characterize, and measure biological processes at the cellular, subcellular, and molecular level in living subjects with non-invasive procedures. PET imaging takes advantage of the traditional diagnostic imaging techniques and introduces positron-emitting probes to determine the expression of indicative molecular targets at different stages of disease. During the last decade, advances in molecular biology have revealed an increasing number of potential molecular targets, including peptide receptors and peptide-related biomolecules. With the help of sophisticated bioconjugation and radiolabeling techniques, numerous peptide-based agents have been developed and evaluated for delivery of PET radionuclides to the specific molecular targets in preclinical and clinical studies. As compared to macromolecules, such as proteins or antibodies, low-molecular-weight peptides have their distinctive advantages and predominantly demonstrate their favorable pharmacokinetics for in vivo PET applications. This review summarizes the criteria of peptide-based PET probes design, the selection of radioisotopes, labeling methods, and provides an overview of the current status and trends in the development of target-specific peptide-based probes with respect to their unique PET imaging applications.
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73
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Lee S, Xie J, Chen X. Peptides and peptide hormones for molecular imaging and disease diagnosis. Chem Rev 2010; 110:3087-111. [PMID: 20225899 DOI: 10.1021/cr900361p] [Citation(s) in RCA: 253] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Seulki Lee
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 31 Center Drive, Suite 1C14, Bethesda, Maryland 20892-2281, USA
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Stengel A, Goebel M, Wang L, Rivier J, Kobelt P, Monnikes H, Tache Y. Selective central activation of somatostatin receptor 2 increases food intake, grooming behavior and rectal temperature in rats. JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY : AN OFFICIAL JOURNAL OF THE POLISH PHYSIOLOGICAL SOCIETY 2010; 61:399-407. [PMID: 20814067 PMCID: PMC4040268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 07/15/2010] [Indexed: 05/29/2023]
Abstract
The consequences of selective activation of brain somatostatin receptor-2 (sst2) were assessed using the sst2 agonist, des-AA(1,4-6,11-13)-[DPhe(2),Aph7(Cbm),DTrp(8)]-Cbm-SST-Thr-NH2. Food intake (FI) was monitored in ad libitum fed rats chronically implanted with an intracerebroventricular (i.c.v.) cannula. The sst(2) agonist injected i.c.v. at 0.1 and 1 microg/rat dose-dependently increased light phase FI from 2 to 6 hours post injection (2.3+/-0.5 and 7.5+/-1.2 respectively vs. vehicle: 0.2+/-0.2 g/300 g bw, P<0.001). Peptide action was reversed by i.c.v. injection of the sst2 antagonist, des-AA(1,4-6,11-13)-[pNO(2)-Phe(2),DCys(3),Tyr(7),DAph(Cbm)8]-SST-2Nal-NH(2) and not reproduced by intraperitoneal injection (30 microg/rat). The sst(2) antagonist alone i.c.v. significantly decreased the cumulative 14-hours dark phase FI by 29.5%. Other behaviors, namely grooming, drinking and locomotor activity were also increased by the sst(2) agonist (1 microg/rat, i.c.v.) as monitored during the 2(nd) hour post injection while gastric emptying of solid food was unaltered. Rectal temperature rose 1 hour after the sst(2) agonist (1 microg/rat, i.c.v.) with a maximal response maintained from 1 to 4 hours post injection. These data show that selective activation of the brain sst(2) receptor induces a feeding response in the light phase not associated with changes in gastric emptying. The food intake reduction following sst(2) receptor blockade suggests a role of this receptor in the orexigenic drive during the dark phase.
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Affiliation(s)
- A Stengel
- CURE: Digestive Diseases Research Center and Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
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75
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LC/MS evaluation of metabolism and membrane transport of bombesin peptides. Amino Acids 2010; 40:669-75. [PMID: 20676905 DOI: 10.1007/s00726-010-0696-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 07/10/2010] [Indexed: 10/19/2022]
Abstract
Two bombsin peptides, GRPR agonist [Aca-QWAVGHLM-NH(2)] and antagonist [fQWAVGHL-NHEthyl] were evaluated. We employed the highly sensitive Waters Q-Tof Premier MS coupled with a UPLC system to identify the metabolites produced by rat hepatocytes or PC-3 human prostate cancer cells; and we utilized the AB/MDS 4000 Q-Trap LC/MS/MS system with highly sensitive quantitative and qualitative performance, to quantitatively analyze the internalization of GRPR agonist and antagonist in PC-3 cells. The major metabolites of both GRPR agonist and antagonist were the result of peptide bond hydrolysis between W and A which was demonstrated by observation of the N-terminal fragment m/z 446 (Aca-QW-OH) for agonist and m/z 480 (fQW-OH) for antagonist. Both peptides were also hydrolyzed between A and V which formed peaks m/z 517 [Aca-QWA-OH] and m/z 555 (VGHLM-NH2) for the agonist and m/z 551 [fQWA-OH] and m/z 452 (VGHL-NHEthyl) for the antagonist. The peptide agonist also formed a unique metabolite that resulted from hydrolysis of the C-terminal amide. The antagonist showed significantly slower metabolism as compared to the agonist in both rat hepatocytes and PC-3 cells. The antagonist also showed significantly lower PC-3 cell internalization rate than that of the agonist. In conclusion, the metabolism profiles of both GRPR agonist and antagonist peptides were identified by LC/MS. The antagonist peptide was more stable than the agonist peptide in rat hepatocyte incubation. One major factor could be the hydrolysis-resistant C-terminal L-NHEthyl group compared with the unsubstituted amide of the agonist. Another factor could be different amino acid sequences of the agonist and antagonist that may also influence the enzymatic hydrolysis. The antagonist ligand is potentially more useful for receptor-targeted imaging due primarily to its higher metabolic stability.
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Di Cianni A, Carotenuto A, Brancaccio D, Novellino E, Reubi JC, Beetschen K, Papini AM, Ginanneschi M. Novel Octreotide Dicarba-analogues with High Affinity and Different Selectivity for Somatostatin Receptors. J Med Chem 2010; 53:6188-97. [DOI: 10.1021/jm1005868] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Alessandra Di Cianni
- Laboratory of Peptides & Proteins, Chemistry & Biology, University of Firenze, Via della Lastruccia 13, I-50019 Sesto Fiorentino, Italy
- Department of Chemistry “Ugo Schiff”, University of Firenze, Via della Lastruccia 5-13, I-50019, Sesto Fiorentino, Italy
| | - Alfonso Carotenuto
- Department of Pharmaceutical Chemistry and Toxicology, University of Napoli, Via Domenico Montesano 49, I-80131 Napoli, Italy
| | - Diego Brancaccio
- Department of Pharmaceutical Chemistry and Toxicology, University of Napoli, Via Domenico Montesano 49, I-80131 Napoli, Italy
| | - Ettore Novellino
- Department of Pharmaceutical Chemistry and Toxicology, University of Napoli, Via Domenico Montesano 49, I-80131 Napoli, Italy
| | - Jean Claude Reubi
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Murtenstrasse 31, CH-3010 Berne, Switzerland
| | - Karin Beetschen
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Murtenstrasse 31, CH-3010 Berne, Switzerland
| | - Anna Maria Papini
- Laboratory of Peptides & Proteins, Chemistry & Biology, University of Firenze, Via della Lastruccia 13, I-50019 Sesto Fiorentino, Italy
- Department of Chemistry “Ugo Schiff”, University of Firenze, Via della Lastruccia 5-13, I-50019, Sesto Fiorentino, Italy
| | - Mauro Ginanneschi
- Laboratory of Peptides & Proteins, Chemistry & Biology, University of Firenze, Via della Lastruccia 13, I-50019 Sesto Fiorentino, Italy
- Department of Chemistry “Ugo Schiff”, University of Firenze, Via della Lastruccia 5-13, I-50019, Sesto Fiorentino, Italy
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Goebel M, Stengel A, Wang L, Coskun T, Alsina-Fernandez J, Rivier J, Taché Y. Pattern of Fos expression in the brain induced by selective activation of somatostatin receptor 2 in rats. Brain Res 2010; 1351:150-164. [PMID: 20637739 DOI: 10.1016/j.brainres.2010.07.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/28/2010] [Accepted: 07/08/2010] [Indexed: 02/08/2023]
Abstract
Central activation of somatostatin (sst) receptors by oligosomatostatin analogs inhibits growth hormone and stress-related rise in catecholamine plasma levels while stimulating grooming, feeding behaviors, gastric transit and acid secretion, which can be mimicked by selective sst(2) receptor agonist. To evaluate the pattern of neuronal activation induced by peptide sst receptor agonists, we assessed Fos-expression in rat brain after intracerebroventricular (i.c.v.) injection of a newly developed selective sst(2) agonist compared to the oligosomatostatin ODT8-SST, a pan-sst(1-5) agonist. Ninety min after injection of vehicle (10 microl) or previously established maximal orexigenic dose of peptides (1 microg=1 nmol/rat), brains were assessed for Fos-immunohistochemistry and doublelabeling. Food and water were removed after injection. The sst(2) agonist and ODT8-SST induced a similar Fos distribution pattern except in the arcuate nucleus where only the sst(2) agonist increased Fos. Compared to ODT8-SST, the sst(2) agonist induced higher Fos-expression by 3.7-times in the basolateral amygdaloid nucleus, 1.2-times in the supraoptic nucleus (SON), 1.6-times in the magnocellular paraventricular hypothalamic nucleus (mPVN), 4.1-times in the external lateral parabrachial nucleus, and 2.6-times in both the inferior olivary nucleus and superficial layer of the caudal spinal trigeminal nucleus. Doublelabeling in the hypothalamus showed that ODT8-SST activates 36% of oxytocin, 63% of vasopressin and 79% of sst(2) immunoreactive neurons in the mPVN and 28%, 55% and 25% in the SON, respectively. Selective activation of sst(2) receptor results in a more robust neuronal activation than the pan-sst(1-5) agonist in various brain regions that may have relevance in sst(2) mediated alterations of behavioral, autonomic and endocrine functions.
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Affiliation(s)
- Miriam Goebel
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, David Geffen School of Medicine, UCLA and VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Andreas Stengel
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, David Geffen School of Medicine, UCLA and VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Lixin Wang
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, David Geffen School of Medicine, UCLA and VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - Tamer Coskun
- Biotechnology Discovery Research, Eli Lilly and Company, Indianapolis, IN, USA
| | | | - Jean Rivier
- Peptide Biology Laboratories, Salk Institute, La Jolla, CA, USA
| | - Yvette Taché
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, David Geffen School of Medicine, UCLA and VA Greater Los Angeles Healthcare System, Los Angeles, California, USA.
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Reubi JC, Erchegyi J, Cescato R, Waser B, Rivier JE. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog. Eur J Nucl Med Mol Imaging 2010; 37:1551-8. [PMID: 20396884 DOI: 10.1007/s00259-010-1445-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 03/08/2010] [Indexed: 12/13/2022]
Abstract
PURPOSE Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. METHODS Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst(1)-sst(5)) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst(2) and sst(3) internalization in vitro in HEK293 cells stably expressing the human sst(2) or sst(3) receptor, using an immunofluorescence microscopy-based internalization assay. RESULTS All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst(2) internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst(3) internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. CONCLUSION Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst(3) receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added.
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Affiliation(s)
- Jean Claude Reubi
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, PO Box 62, Murtenstrasse 31, 3010 Berne, Switzerland.
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Abstract
Targeted molecular imaging techniques have become indispensable tools in modern diagnostics because they provide accurate and specific diagnosis of disease information. Conventional nonspecific contrast agents suffer from low targeting efficiency; thus, the use of molecularly targeted imaging probes is needed depending on different imaging modalities. Although recent technologies have yielded various strategies for designing smart probes, utilization of peptide-based probes has been most successful. Phage display technology and combinatorial peptide chemistry have profoundly impacted the pool of available targeting peptides for the efficient and specific delivery of imaging labels. To date, selected peptides that target a variety of disease-related receptors and biomarkers are in place. These targeting peptides can be coupled with the appropriate imaging moieties or nanoplatforms on demand with the help of sophisticated bioconjugation or radiolabeling techniques. This review article examines the current trends in peptide-based imaging probes developed for in vivo applications. We discuss the advantage of and challenges in developing peptide-based probes and summarize current systems with respect to their unique design strategies and applications.
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Affiliation(s)
- Seulki Lee
- Laboratory for Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 31 Center Drive, Suite 1C14, Bethesda, Maryland 20892-2281, USA
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80
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Abstract
IMPORTANCE OF THE FIELD Tumor targeting with peptides is based on the discovery that receptors for many regulatory peptides are overexpressed in tumor cells, compared with their expression in normal tissues. Consequently, these peptides and their analogues can be used as carriers/targeting moieties for the preparation of diagnostic and therapeutic agents that have increased selectivity and decreased peripheral toxicity. AREAS COVERED IN THIS REVIEW Here an overview is given of the most relevant gonadotropin-releasing hormone (GnRH) and somatostatin derivatives, as well as of their applications in cancer diagnosis and therapy. For this purpose, recently published data in these areas (mostly articles published from 2000 to 2009) were reviewed. WHAT THE READER WILL GAIN In contrast to other regulatory peptides that stimulate the tumor growth, GnRH and somatostatin derivatives have inhibitory effect; therefore, they were used primarily for the preparation of various conjugates to be used in targeted chemotherapy, targeted radiotherapy, photodynamic therapy, boron neutron capture therapy and cancer diagnosis. Some of these conjugates have already found clinical applications, whereas others are now in preclinical and clinical trials. TAKE HOME MESSAGE Tumor targeting with hormone peptides provides a basis for the development of new diagnostic and therapeutic approaches for cancer.
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Affiliation(s)
- Gábor Mezo
- Eötvös Loránd University, Research Group of Peptide Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Hungary.
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81
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Msaouel P, Galanis E, Koutsilieris M. Somatostatin and somatostatin receptors: implications for neoplastic growth and cancer biology. Expert Opin Investig Drugs 2010; 18:1297-316. [PMID: 19678799 DOI: 10.1517/13543780903176399] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Somatostatin agonists (SM-As) are capable of achieving durable symptomatic relief and significant clinical responses in certain tumours. Herein, we review the diverse direct and indirect mechanisms of antineoplastic activity elicited by SM-As as well as the hurdles that complicate their use as monotherapies in a broader range of malignancies. Emphasis is placed on recent clinical attempts to neutralise the IGF-mediated survival factor effects in the bone metastasis microenvironment in advanced prostate cancer. The first clinical trials of this 'anti-survival factor manipulation' strategy utilised the ability of SM-As to suppress the growth hormone-dependent liver-derived IGF-I bioavailability in combination with other drugs, such as dexamethasone, zolendronate and oestrogens, acting systemically and at the bone metastasis microenvironment. These regimens restored androgen ablation responsiveness in stage D3 prostate cancer patients and successfully produced objective clinical responses while only mild toxicities were observed. Furthermore, we focus on the preclinical experimental data of a targeted SM-A coupled to the super-potent doxorubicin derivative AN-201. The resulting conjugate (AN-238) has shown increased antitumour potency with a favourable toxicity profile. The potential use of novel SM-As as anticancer drugs is discussed in relation to data suggesting other direct and indirect treatment approaches pertaining to the somatostatin system.
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Affiliation(s)
- Pavlos Msaouel
- National & Kapodistrian University of Athens, Medical School, Department of Experimental Physiology, 75 Micras Asias St, Goudi-Athens 11527, Greece
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82
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Nanda PK, Lane SR, Retzloff LB, Pandey US, Smith CJ. Radiolabeled regulatory peptides for imaging and therapy. Curr Opin Endocrinol Diabetes Obes 2010; 17:69-76. [PMID: 19901831 PMCID: PMC2892114 DOI: 10.1097/med.0b013e32833392ac] [Citation(s) in RCA: 19] [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] [Indexed: 01/27/2023]
Abstract
PURPOSE OF REVIEW The purpose of the present review is to describe new, innovative strategies of diagnosing and treating specific human cancers using a cadre of radiolabeled regulatory peptides. RECENT FINDINGS Peptide receptor-targeted radionuclide therapy is a method of site-directed radiotherapy that specifically targets human cancers expressing a cognate receptor-subtype in very high numbers. Ideally, the procedure targets only the primary or metastatic disease and is minimally invasive, with little radiation damage to normal, collateral tissues. For treatment strategies of this type to be effective, it is critical to evaluate the toxicity of the treatment protocol, the radiation dosimetry of the therapeutic regimen, and the biological profile of the radiopharmaceutical, including biodistribution and pharmacokinetics of the drug. Site-directed molecular imaging procedures via gamma-scintigraphy can address many of the critical issues associated with peptide receptor-targeted radionuclide therapy and it is, therefore, necessary to describe the effective balance between the clinical benefits and risks of this treatment strategy. SUMMARY Continued development in the design or chemical structure of radiolabeled, biologically active peptides could do much to improve the targeting ability of these drugs, thereby creating new and innovative strategies for diagnosis or treatment of human cancers.
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Affiliation(s)
- Prasant K. Nanda
- Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Stephanie R. Lane
- Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri, USA
- Department of Chemistry, University of Missouri, Columbia, Missouri, USA
| | - Lauren B. Retzloff
- Department of Molecular Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Usha S. Pandey
- Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Charles Jeffrey Smith
- Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri, USA
- Research Division, Harry S. Truman Memorial Veterans’ Hospital, University of Missouri School of Medicine, Columbia, Missouri, USA
- Department of Molecular Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA
- The Radiopharmaceutical Sciences Institute, University of Missouri School of Medicine, Columbia, Missouri, USA
- University of Missouri Research Reactor Center, Columbia, Missouri, USA
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83
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Cescato R, Loesch KA, Waser B, Mäcke HR, Rivier JE, Reubi JC, Schonbrunn A. Agonist-biased signaling at the sst2A receptor: the multi-somatostatin analogs KE108 and SOM230 activate and antagonize distinct signaling pathways. Mol Endocrinol 2009; 24:240-9. [PMID: 19910453 DOI: 10.1210/me.2009-0321] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Somatostatin analogs that activate the somatostatin subtype 2A (sst2A) receptor are used to treat neuroendocrine cancers because they inhibit tumor secretion and growth. Recently, new analogs capable of activating multiple somatostatin receptor subtypes have been developed to increase tumor responsiveness. We tested two such multi-somatostatin analogs for functional selectivity at the sst2A receptor: SOM230, which activates sst1, sst2, sst3, and sst5 receptors, and KE108, which activates all sst receptor subtypes. Both compounds are reported to act as full agonists at their target sst receptors. In sst2A-expressing HEK293 cells, somatostatin inhibited cAMP production, stimulated intracellular calcium accumulation, and increased ERK phosphorylation. SOM230 and KE108 were also potent inhibitors of cAMP accumulation, as expected. However, they antagonized somatostatin stimulation of intracellular calcium and behaved as partial agonists/antagonists for ERK phosphorylation. In pancreatic AR42J cells, which express sst2A receptors endogenously, SOM230 and KE108 were both full agonists for cAMP inhibition. However, although somatostatin increased intracellular calcium and ERK phosphorylation, SOM230 and KE108 again antagonized these effects. Distinct mechanisms were involved in sst2A receptor signaling in AR42J cells; pertussis toxin pretreatment blocked somatostatin inhibition of cAMP accumulation but not the stimulation of intracellular calcium and ERK phosphorylation. Our results demonstrate that SOM230 and KE108 behave as agonists for inhibition of adenylyl cyclase but antagonize somatostatin's actions on intracellular calcium and ERK phosphorylation. Thus, SOM230 and KE108 are not somatostatin mimics, and their functional selectivity at sst2A receptors must be considered in clinical applications where it may have important consequences for therapy.
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Affiliation(s)
- Renzo Cescato
- Division of Cell Biology, Institute of Pathology, University of Berne, Berne, Switzerland
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84
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Erchegyi J, Cescato R, Grace CRR, Waser B, Piccand V, Hoyer D, Riek R, Rivier JE, Reubi JC. Novel, potent, and radio-iodinatable somatostatin receptor 1 (sst1) selective analogues. J Med Chem 2009; 52:2733-46. [PMID: 19351180 DOI: 10.1021/jm801314f] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The proposed sst(1) pharmacophore (J. Med. Chem. 2005, 48, 523-533) derived from the NMR structures of a family of mono- and dicyclic undecamers was used to design octa-, hepta-, and hexamers with high affinity and selectivity for the somatostatin sst(1) receptor. These compounds were tested for their in vitro binding properties to all five somatostatin (SRIF) receptors using receptor autoradiography; those with high SRIF receptor subtype 1 (sst(1)) affinity and selectivity were shown to be agonists when tested functionally in a luciferase reporter gene assay. Des-AA(1,4-6,10,12,13)-[DTyr(2),DAgl(NMe,2naphthoyl)(8),IAmp(9)]-SRIF-Thr-NH(2) (25) was radio-iodinated ((125)I-25) and specifically labeled sst(1)-expressing cells and tissues. 3D NMR structures were calculated for des-AA(1,4-6,10,12,13)-[DPhe(2),DTrp(8),IAmp(9)]-SRIF-Thr-NH(2) (16), des-AA(1,2,4-6,10,12,13)-[DAgl(NMe,2naphthoyl)(8),IAmp(9)]-SRIF-Thr-NH(2) (23), and des-AA(1,2,4-6,10,12,13)-[DAgl(NMe,2naphthoyl)(8),IAmp(9),Tyr(11)]-SRIF-NH(2) (27) in DMSO. Though the analogues have the sst(1) pharmacophore residues at the previously determined distances from each other, the positioning of the aromatic residues in 16, 23, and 27 is different from that described earlier, suggesting an induced fit mechanism for sst(1) binding of these novel, less constrained sst(1)-selective family members.
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Affiliation(s)
- Judit Erchegyi
- The Clayton Foundation Laboratories for Peptide Biology, La Jolla, California 92037, USA
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85
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Schottelius M, Wester HJ. Molecular imaging targeting peptide receptors. Methods 2009; 48:161-77. [DOI: 10.1016/j.ymeth.2009.03.012] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 03/11/2009] [Indexed: 02/08/2023] Open
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86
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Akgün E, Körner M, Gao F, Harkumar KG, Waser B, Reubi JC, Portoghese PS, Miller LJ. Synthesis and in vitro characterization of radioiodinatable benzodiazepines selective for type 1 and type 2 cholecystokinin receptors. J Med Chem 2009; 52:2138-47. [PMID: 19271701 PMCID: PMC2666544 DOI: 10.1021/jm801439x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Radiolabeled antagonists of specific peptide receptors identify a higher number of receptor binding sites than agonists and may thus be preferable for in vivo tumor targeting. In this study, two novel radioiodinated 1,4-benzodiazepines, (S)-1-(3-iodophenyl)-3-(1-methyl-2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)urea (9) and (R)-1-(3-iodophenyl)-3-(1-methyl-2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)urea (7), were developed. They were characterized in vitro as high affinity selective antagonists at cholecystokinin types 1 and 2 (CCK(1) and CCK(2)) receptors using receptor binding, calcium mobilization, and internalization studies. Their binding to human tumor tissues was assessed with in vitro receptor autoradiography and compared with an established peptidic CCK agonist radioligand. The (125)I-labeled CCK(1) receptor-selective compound 9 often revealed a substantially higher amount of CCK(1) receptor binding sites in tumors than the agonist (125)I-CCK. Conversely, the radioiodinated CCK(2) receptor-selective compound 7 showed generally weaker tumor binding than (125)I-CCK. In conclusion, compound 9 is an excellent radioiodinated nonpeptidic antagonist ligand for direct and selective labeling of CCK(1) receptors in vitro. Moreover, it represents a suitable candidate to test antagonist binding to CCK(1) receptor-expressing tumors in vivo.
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Affiliation(s)
- Eyup Akgün
- University of Minnesota, Department of Medicinal Chemistry, College of Pharmacy, Minneapolis, MN 55455
| | - Meike Körner
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, AZ 85259
| | - Fan Gao
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, AZ 85259
| | - Kaleeckal G. Harkumar
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, AZ 85259
| | - Beatrice Waser
- Institute of Pathology of the University of Berne, Division of Cell Biology and Experimental Cancer Research, 3010 Berne, Switzerland
| | - Jean Claude Reubi
- Institute of Pathology of the University of Berne, Division of Cell Biology and Experimental Cancer Research, 3010 Berne, Switzerland
| | - Philip S. Portoghese
- University of Minnesota, Department of Medicinal Chemistry, College of Pharmacy, Minneapolis, MN 55455
| | - Laurence J. Miller
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, AZ 85259
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87
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Feytens D, De Vlaeminck M, Cescato R, Tourwé D, Reubi JC. Highly Potent 4-Amino-indolo[2,3-c]azepin-3-one-Containing Somatostatin Mimetics with a Range of sst Receptor Selectivities. J Med Chem 2008; 52:95-104. [DOI: 10.1021/jm801205x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Debby Feytens
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
| | - Magali De Vlaeminck
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
| | - Renzo Cescato
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
| | - Dirk Tourwé
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
| | - Jean Claude Reubi
- Department of Organic Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
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Abstract
Receptors for regulatory peptides are overexpressed in a variety of human cancers. They represent the molecular basis for in vivo imaging with radiolabeled peptide probes. Somatostatin-derived tracers, designed to image the sst2-overexpressing neuroendocrine tumors, have enjoyed almost 2 decades of successful development and extensive clinical applications. More recent developments include second- and third-generation somatostatin analogs, with a broader receptor subtype profile or with antagonistic properties. Emerging tracers for other peptide receptors, including cholecystokinin/gastrin and GLP-1 analogs for neuroendocrine tumors, bombesin and neuropeptide-Y analogs for prostate or breast cancers, or Arg-Gly-Asp peptides for neoangiogenesis labeling, are also in current development. Application fields include both SPECT/CT and PET/CT.
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89
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Grace CRR, Erchegyi J, Samant M, Cescato R, Piccand V, Riek R, Reubi JC, Rivier JE. Ring size in octreotide amide modulates differently agonist versus antagonist binding affinity and selectivity. J Med Chem 2008; 51:2676-81. [PMID: 18410083 DOI: 10.1021/jm701445q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
H-DPhe (2)-c[Cys (3)-Phe (7)-DTrp (8)-Lys (9)-Thr (10)-Cys (14)]-Thr (15)-NH2 (1) (a somatostatin agonist, SRIF numbering) and H-Cpa (2)-c[DCys (3)-Tyr (7)-DTrp (8)-Lys (9)-Thr (10)-Cys (14)]-Nal (15)-NH2 (4) (a somatostatin antagonist) are based on the structure of octreotide that binds to three somatostatin receptor subtypes (sst 2/3/5) with significant binding affinity. Analogues of 1 and 4 were synthesized with norcysteine (Ncy), homocysteine (Hcy), or D-homocysteine (DHcy) at positions 3 and/or 14. Introducing Ncy at positions 3 and 14 constrained the backbone flexibility, resulting in loss of binding affinity at all sst s. The introduction of Hcy at positions 3 and 14 improved selectivity for sst 2 as a result of significant loss of binding affinity at the other sst s. Substitution by DHcy at position 3 in the antagonist scaffold (5), on the other hand, resulted in a significant loss of binding affinity at sst 2 and sst 3 as compared to the different affinities of the parent compound (4). The 3D NMR structures of the analogues in dimethylsulfoxide are consistent with the observed binding affinities.
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Affiliation(s)
- Christy Rani R Grace
- Structural Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA
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