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Sullivan R, Hou J, Yu L, Wilk B, Sykes J, Biernaski H, Butler J, Kovacs M, Hicks J, Thiessen JD, Dharmakumar R, Prato FS, Wisenberg G, Luyt LG, Dhanvantari S. Design, Synthesis, and Preclinical Evaluation of a High-Affinity 18F-Labeled Radioligand for Myocardial Growth Hormone Secretagogue Receptor Before and After Myocardial Infarction. J Nucl Med 2024; 65:1633-1639. [PMID: 39266294 DOI: 10.2967/jnumed.124.267578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 08/13/2024] [Indexed: 09/14/2024] Open
Abstract
The peptide hormone ghrelin is produced in cardiomyocytes and acts through the myocardial growth hormone secretagogue receptor (GHSR) to promote cardiomyocyte survival. Administration of ghrelin may have therapeutic effects on post-myocardial infarction (MI) outcomes. Therefore, there is a need to develop molecular imaging probes that can track the dynamics of GHSR in health and disease to better predict the effectiveness of ghrelin-based therapeutics. We designed a high-affinity GHSR ligand labeled with 18F for imaging by PET and characterized its in vivo properties in a canine model of MI. Methods: We rationally designed and radiolabeled with 18F a quinazolinone derivative ([18F]LCE470) with subnanomolar binding affinity to GHSR. We determined the sensitivity and in vivo and ex vivo specificity of [18F]LCE470 in a canine model of surgically induced MI using PET/MRI, which allowed for anatomic localization of tracer uptake and simultaneous determination of global cardiac function. Uptake of [18F]LCE470 was determined by time-activity curve and SUV analysis in 3 regions of the left ventricle-area of infarct, territory served by the left circumflex coronary artery, and remote myocardium-over a period of 1.5 y. Changes in cardiac perfusion were tracked by [13N]NH3 PET. Results: The receptor binding affinity of LCE470 was measured at 0.33 nM, the highest known receptor binding affinity for a radiolabeled GHSR ligand. In vivo blocking studies in healthy hounds and ex vivo blocking studies in myocardial tissue showed the specificity of [18F]LCE470, and sensitivity was demonstrated by a positive correlation between tracer uptake and GHSR abundance. Post-MI changes in [18F]LCE470 uptake occurred independently of perfusion tracer distributions and changes in global cardiac function. We found that the regional distribution of [18F]LCE470 within the left ventricle diverged significantly within 1 d after MI and remained that way throughout the 1.5-y duration of the study. Conclusion: [18F]LCE470 is a high-affinity PET tracer that can detect changes in the regional distribution of myocardial GHSR after MI. In vivo PET molecular imaging of the global dynamics of GHSR may lead to improved GHSR-based therapeutics in the treatment of post-MI remodeling.
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Affiliation(s)
- Rebecca Sullivan
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada
| | - Jinqiang Hou
- Lakehead University and Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
| | - Lihai Yu
- London Regional Cancer Program, London, Ontario, Canada
| | - Benjamin Wilk
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Jane Sykes
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Heather Biernaski
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
| | - John Butler
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Michael Kovacs
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Justin Hicks
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Jonathan D Thiessen
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | | | - Frank S Prato
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Gerald Wisenberg
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada
| | - Leonard G Luyt
- London Regional Cancer Program, London, Ontario, Canada
- Departments of Chemistry, Oncology, and Medical Imaging, Western University, London, Ontario, Canada
| | - Savita Dhanvantari
- Imaging Research Program, Lawson Health Research Institute, London, Ontario, Canada;
- Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada
- Department of Medical Biophysics, Western University, London, Ontario, Canada
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2
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Esteban JJ, Mason JR, Kaminski J, Ramachandran R, Luyt LG. A survey of stapling methods to increase affinity, activity, and stability of ghrelin analogues. RSC Med Chem 2024; 15:254-266. [PMID: 38283230 PMCID: PMC10809362 DOI: 10.1039/d3md00441d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 11/29/2023] [Indexed: 01/30/2024] Open
Abstract
The growth hormone secretagogue receptor (GHSR) is a G protein-coupled receptor which regulates various important physiological and pathophysiological processes in the body such as energy homeostasis, growth hormone secretion and regulation of appetite. As a result, it has been postulated as a potential therapeutic target for the treatment of cancer cachexia and other metabolic disorders, as well as a potential imaging agent target for cancers and cardiovascular diseases. Ghrelin is the primary high affinity endogenous ligand for GHSR and has limited secondary structure in solution, which makes it proteolytically unstable. This inherent instability in ghrelin can be overcome by incorporating helix-inducing staples that stabilize its structure and improve affinity and activity. We present an analysis of different stapling methods at positions 12 and 16 of ghrelin(1-20) analogues with the goal of increasing proteolytic stability and to retain or improve affinity and activity towards the GHSR. Ghrelin(1-20) analogues were modified with a wide range of chemical staples, including a lactam staple, triazole staple, hydrocarbon staple, Glaser staple, and xylene-thioether staple. Once synthesized, the receptor affinity and α-helicity were measured using competitive binding assays and circular dichroism spectroscopy, respectively. Generally, an increase in alpha-helicity using a flexible staple linker led to improved affinity towards GHSR. Ghrelin(1-20) analogues with a lactam, triazole, and hydrocarbon staple resulted in helical analogues with stronger affinity towards GHSR than unstapled ghrelin(1-20), a compound that lacks helical character. Compounds were also investigated for their agonist activity through β-arrestin 1 & 2 recruitment BRET assays and for their metabolic stability through serum stability analysis.
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Affiliation(s)
- Juan J Esteban
- Department of Chemistry, University of Western Ontario 1151 Richmond Street London Ontario N6A 3K7 Canada
| | - Julia R Mason
- Department of Chemistry, University of Western Ontario 1151 Richmond Street London Ontario N6A 3K7 Canada
| | - Jakob Kaminski
- Department of Chemistry, University of Western Ontario 1151 Richmond Street London Ontario N6A 3K7 Canada
| | - Rithwik Ramachandran
- Department of Physiology and Pharmacology, University of Western Ontario 1151 Richmond Street London Ontario N6A 5C1 Canada
| | - Leonard G Luyt
- Department of Chemistry, University of Western Ontario 1151 Richmond Street London Ontario N6A 3K7 Canada
- Departments of Medical Imaging and Oncology, University of Western Ontario 1151 Richmond Street London Ontario N6A 3K7 Canada
- London Regional Cancer Program, Lawson Health Research Institute 800 Commissioners Road East London Ontario N6A 4L6 Canada
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3
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Childs M, Chandrabalan A, Hodgson D, Ramachandran R, Luyt LG. Discovery of Ghrelin(1-8) Analogues with Improved Stability and Functional Activity for PET Imaging. ACS Pharmacol Transl Sci 2023; 6:1075-1086. [PMID: 37470019 PMCID: PMC10353549 DOI: 10.1021/acsptsci.3c00088] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Indexed: 07/21/2023]
Abstract
The highest affinity ghrelin-based analogue for fluorine-18 positron emission tomography, [Inp1,Dpr3(6-FN),1Nal4,Thr8]ghrelin(1-8) amide (1), has remarkable subnanomolar receptor affinity (IC50 = 0.11 nM) toward the growth hormone secretagogue receptor 1a (GHSR). However, initial in vivo PET imaging and biodistribution of [18F]1 in mice demonstrated an unfavorable pharmacokinetic profile with rapid clearance and accumulation in liver and intestinal tissue, prompting concerns about the metabolic stability of this probe. The aims of the present study were to examine the proteolytic stability of ghrelin analogue 1 in the presence of blood and liver enzymes, structurally modify the peptide to improve stability without impeding the strong binding affinity, and measure the presently unknown functional activity of ghrelin(1-8) analogues. The in vitro stability and metabolite formation of 1 in human serum and liver S9 fraction revealed a metabolic soft spot between amino acids Leu5 and Ser6 in the peptide sequence. A focused library of ghrelin(1-8) analogues was synthesized and evaluated in a structure-activity-stability relationship study to further understand the structural importance of the residues at these positions in the context of stability and receptor affinity. The critical nature of l-stereochemistry at position 5 was identified and substitution of Ser6 with l-2,3-diaminopropionic acid led to a novel ligand with substantially improved in vitro stability while maintaining subnanomolar GHSR affinity. Despite the highly modified nature of these analogues compared to human ghrelin, ghrelin(1-8) analogues were found to recruit all G protein subtypes (Gαq/11/13/i1/oB) known to associate with GHSR as well as β-arrestins with low micromolar to nanomolar potencies. The study of these analogues demonstrates the ability to balance desirable ligand properties, including affinity, stability, and potency to produce well-rounded candidate molecules for further in vivo evaluation.
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Affiliation(s)
- Marina
D. Childs
- Department
of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3K7, Canada
| | - Arundhasa Chandrabalan
- Department
of Physiology and Pharmacology, University
of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5C1, Canada
| | - Derian Hodgson
- Department
of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3K7, Canada
| | - Rithwik Ramachandran
- Department
of Physiology and Pharmacology, University
of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5C1, Canada
| | - Leonard G. Luyt
- Department
of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3K7, Canada
- Departments
of Medical Imaging and Oncology, University
of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3K7, Canada
- London
Regional Cancer Program, Lawson Health Research
Institute, 800 Commissioners
Road East, London, Ontario, N6A 4L6, Canada
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4
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Moussaron A, Jouan-Hureaux V, Collet C, Pierson J, Thomas N, Choulier L, Veran N, Doyen M, Arnoux P, Maskali F, Dumas D, Acherar S, Barberi-Heyob M, Frochot C. Preliminary Study of New Gallium-68 Radiolabeled Peptide Targeting NRP-1 to Detect Brain Metastases by Positron Emission Tomography. Molecules 2021; 26:7273. [PMID: 34885871 PMCID: PMC8659110 DOI: 10.3390/molecules26237273] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/11/2021] [Accepted: 11/23/2021] [Indexed: 12/11/2022] Open
Abstract
Due to their very poor prognosis and a fatal outcome, secondary brain tumors are one of the biggest challenges in oncology today. From the point of view of the early diagnosis of these brain micro- and macro-tumors, the sensitivity and specificity of the diagnostic tools constitute an obstacle. Molecular imaging, such as Positron Emission Tomography (PET), is a promising technique but remains limited in the search for cerebral localizations, given the commercially available radiotracers. Indeed, the [18F]FDG PET remains constrained by the physiological fixation of the cerebral cortex, which hinders the visualization of cerebral metastases. Tumor angiogenesis is recognized as a crucial phenomenon in the progression of malignant tumors and is correlated with overexpression of the neuropilin-1 (NRP-1) receptor. Here, we describe the synthesis and the photophysical properties of the new gallium-68 radiolabeled peptide to target NRP-1. The KDKPPR peptide was coupled with gallium-68 anchored into a bifunctional NODAGA chelating agent, as well as Cy5 for fluorescence detection. The Cy5 absorbance spectra did not change, whereas the molar extinction coefficient (ε) decreased drastically. An enhancement of the fluorescence quantum yield (φF) could be observed due to the better water solubility of Cy5. [68Ga]Ga-NODAGA-K(Cy5)DKPPR was radiosynthesized efficiently, presented hydrophilic properties (log D = -1.86), and had high in vitro stability (>120 min). The molecular affinity and the cytotoxicity of this new chelated radiotracer were evaluated in vitro on endothelial cells (HUVEC) and MDA-MB-231 cancer cells (hormone-independent and triple-negative line) and in vivo on a brain model of metastasis in a nude rat using the MDA-MB-231 cell line. No in vitro toxicity has been observed. The in vivo preliminary experiments showed promising results, with a high contrast between the healthy brain and metastatic foci for [68Ga]Ga-NODAGA-K(Cy5)DKPPR.
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Affiliation(s)
- Albert Moussaron
- Université de Lorraine, CNRS, LRGP, F-54000 Nancy, France; (A.M.); (P.A.)
| | - Valérie Jouan-Hureaux
- Université de Lorraine, CNRS, CRAN, F-54000 Nancy, France; (V.J.-H.); (J.P.); (N.T.); (M.B.-H.)
| | - Charlotte Collet
- Nancyclotep Molecular Imaging Platform, F-54500 Vandœuvre-lès-Nancy, France; (C.C.); (N.V.); (M.D.); (F.M.)
- Université de Lorraine, INSERM, U1254, IADI, F-54500 Vandœuvre-lès-Nancy, France
| | - Julien Pierson
- Université de Lorraine, CNRS, CRAN, F-54000 Nancy, France; (V.J.-H.); (J.P.); (N.T.); (M.B.-H.)
| | - Noémie Thomas
- Université de Lorraine, CNRS, CRAN, F-54000 Nancy, France; (V.J.-H.); (J.P.); (N.T.); (M.B.-H.)
| | | | - Nicolas Veran
- Nancyclotep Molecular Imaging Platform, F-54500 Vandœuvre-lès-Nancy, France; (C.C.); (N.V.); (M.D.); (F.M.)
| | - Matthieu Doyen
- Nancyclotep Molecular Imaging Platform, F-54500 Vandœuvre-lès-Nancy, France; (C.C.); (N.V.); (M.D.); (F.M.)
- Université de Lorraine, INSERM, U1254, IADI, F-54500 Vandœuvre-lès-Nancy, France
| | - Philippe Arnoux
- Université de Lorraine, CNRS, LRGP, F-54000 Nancy, France; (A.M.); (P.A.)
| | - Fatiha Maskali
- Nancyclotep Molecular Imaging Platform, F-54500 Vandœuvre-lès-Nancy, France; (C.C.); (N.V.); (M.D.); (F.M.)
| | | | - Samir Acherar
- Université de Lorraine, CNRS, LCPM, F-54000 Nancy, France;
| | - Muriel Barberi-Heyob
- Université de Lorraine, CNRS, CRAN, F-54000 Nancy, France; (V.J.-H.); (J.P.); (N.T.); (M.B.-H.)
| | - Céline Frochot
- Université de Lorraine, CNRS, LRGP, F-54000 Nancy, France; (A.M.); (P.A.)
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5
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Childs MD, Yu L, Kovacs MS, Luyt LG. Radiofluorination of non-activated aromatic prosthetic groups for synthesis and evaluation of fluorine-18 labelled ghrelin(1-8) analogues. Org Biomol Chem 2021; 19:8812-8820. [PMID: 34590643 DOI: 10.1039/d1ob01023a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The growth hormone secretagogue receptor 1a (GHSR) is differentially expressed in various disease states compared to healthy tissues and thus is a target for molecular imaging. The endogenous ligand for the GHSR is ghrelin, a 28 amino acid peptide with a unique octanoyl group on the serine-3 residue. A recently reported ghrelin analogue revealed the successful use of fluorine-containing, polycyclic aromatic groups in place of the octanoyl side chain, thereby providing potential access to new 18F-PET imaging probes. The peptide [Inp1,Dpr3(6-FN),1Nal4,Thr8]ghrelin(1-8) amide (1) showed sub-nanomolar receptor affinity (IC50 = 0.11 nM) toward the GHSR making it the strongest affinity ghrelin analogue reported to date. However, attempts to label such non-activated aromatic groups with fluoride-18 through conventional substitution methods resulted in low radiochemical yields, impractical for use in vivo. Since larger, non-activated aromatic groups appear to be of value for incorporating fluorine into ghrelin(1-8) analogues, an additional peptide bearing a 4'-fluorobiphenyl-4-carboxyl (4'-FBC) group in place of the octanoyl side chain was also of interest. Herein, we describe the radiosynthesis of [Inp1,Dpr3([18F]6-FN),1Nal4,Thr8]ghrelin(1-8) amide ([18F]1) and [Inp1,Dpr3([18F]4'-FBC),1Nal4,Thr8]ghrelin(1-8) amide ([18F]2) using a prosthetic group approach from iodonium ylide precursors as well as initial in vitro and in vivo evaluation of [18F]1 as a potential PET tracer for targeted imaging of the GHSR.
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Affiliation(s)
- Marina D Childs
- Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3 K7, Canada.
| | - Lihai Yu
- London Regional Cancer Program, Lawson Health Research Institute, 800 Commissioners Road East, London, Ontario, N6A 4L6, Canada
| | - Michael S Kovacs
- Department of Medical Imaging, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3 K7, Canada
- Department of Medical Biophysics, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3 K7, Canada
- Lawson Cyclotron & PET Radiochemistry Facility, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario, N6A 5 W9, Canada
| | - Leonard G Luyt
- Department of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3 K7, Canada.
- London Regional Cancer Program, Lawson Health Research Institute, 800 Commissioners Road East, London, Ontario, N6A 4L6, Canada
- Department of Medical Imaging, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3 K7, Canada
- Department of Oncology, University of Western Ontario, 1151 Richmond Street, London, Ontario, N6A 3 K7, Canada
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6
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Bergmann R, Chollet C, Els-Heindl S, Ullrich M, Berndt N, Pietzsch J, Máthé D, Bachmann M, Beck-Sickinger AG. Development of a ghrelin receptor inverse agonist for positron emission tomography. Oncotarget 2021; 12:450-474. [PMID: 33747360 PMCID: PMC7939532 DOI: 10.18632/oncotarget.27895] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/01/2021] [Indexed: 12/21/2022] Open
Abstract
Imaging of Ghrelin receptors in vivo provides unique potential to gain deeper understanding on Ghrelin and its receptors in health and disease, in particular, in cancer. Ghrelin, an octanoylated 28-mer peptide hormone activates the constitutively active growth hormone secretagogue receptor type 1a (GHS-R1a) with nanomolar activity. We developed novel compounds, derived from the potent inverse agonist K-(D-1-Nal)-FwLL-NH2 but structurally varied by lysine conjugation with 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA), palmitic acid and/or diethylene glycol (PEG2) to allow radiolabeling and improve pharmacokinetics, respectively. All compounds were tested for receptor binding, potency and efficacy in vitro, for biodistribution and -kinetics in rats and in preclinical prostate cancer models on mice. Radiolabeling with Cu-64 and Ga-68 was successfully achieved. The Cu-64- or Ga-68-NODAGA-NH-K-K-(D-1-NaI)-F-w-L-L-NH2 radiotracer were specifically accumulated by the GHS-R1a in xenotransplanted human prostate tumor models (PC-3, DU-145) in mice. The tumors were clearly delineated by PET. The radiotracer uptake was also partially blocked by K-(D-1-Nal)-FwLL-NH2 in stomach and thyroid. The presence of the GHS-R1a was also confirmed by immunohistology. In the arterial rat blood plasma, only the original compounds were found. The Cu-64 or Ga-68-NODAGA-NH-K-K-(D-1-NaI)-F-w-L-L-NH2 radiolabeled inverse agonists turned out to be potent and safe. Due to their easy synthesis, high affinity, medium potency, metabolic stability, and the suitable pharmacokinetic profiles, they are excellent tools for imaging and quantitation of GHS-R1a expression in normal and cancer tissues by PET. These compounds can be used as novel biomarkers of the Ghrelin system in precision medicine.
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Affiliation(s)
- Ralf Bergmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.,Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.,These authors contributed equally to this work
| | - Constance Chollet
- Institute of Biochemistry, Faculty of Life Sciences, Universität Leipzig, Leipzig, Germany.,These authors contributed equally to this work
| | - Sylvia Els-Heindl
- Institute of Biochemistry, Faculty of Life Sciences, Universität Leipzig, Leipzig, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany
| | - Nicole Berndt
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Dresden, Germany
| | - Domokos Máthé
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Michael Bachmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.,Tumor Immunology, University Cancer Center, Carl Gustav Carus Technische Universität Dresden, Dresden, Germany.,National Center for Tumor Diseases, Carl Gustav Carus Technische Universität Dresden, Dresden, Germany
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7
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Childs MD, Luyt LG. A Decade's Progress in the Development of Molecular Imaging Agents Targeting the Growth Hormone Secretagogue Receptor. Mol Imaging 2020; 19:1536012120952623. [PMID: 33104445 PMCID: PMC8865914 DOI: 10.1177/1536012120952623] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The growth hormone secretagogue receptor 1a (GHSR), also called the ghrelin receptor, is a G protein-coupled receptor known to play an important metabolic role in the regulation of various physiological processes, including energy expenditure, growth hormone secretion, and cell proliferation. This receptor has been implicated in numerous health issues including obesity, gastrointestinal disorders, type II diabetes, and regulation of body weight in patients with Prader-Willi syndrome, and there has been growing interest in studying its mechanism of behavior to unlock further applications of GHSR-targeted therapeutics. In addition, the GHSR is expressed in various types of cancer including prostate, breast, and testicular cancers, while aberrant expression has been reported in cardiac disease. Targeted molecular imaging of the GHSR could provide insights into its role in biological processes related to these disease states. Over the past decade, imaging probes targeting this receptor have been discovered for the imaging modalities PET, SPECT, and optical imaging. High-affinity analogues of ghrelin, the endogenous ligand for the GHSR, as well as small molecule inhibitors have been developed and evaluated both in vitro and in pre-clinical models. This review provides a comprehensive overview of the molecular imaging agents targeting the GHSR reported to the end of 2019.
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Affiliation(s)
- Marina D Childs
- Department of Chemistry, University of Western Ontario, London, Ontario, Canada
| | - Leonard G Luyt
- Department of Chemistry, University of Western Ontario, London, Ontario, Canada.,Lawson Health Research Institute, London, Ontario, Canada.,Department of Oncology, University of Western Ontario, London, Ontario, Canada.,Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada
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8
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Sinnes JP, Nagel J, Waldron BP, Maina T, Nock BA, Bergmann RK, Ullrich M, Pietzsch J, Bachmann M, Baum RP, Rösch F. Instant kit preparation of 68Ga-radiopharmaceuticals via the hybrid chelator DATA: clinical translation of [ 68Ga]Ga-DATA-TOC. EJNMMI Res 2019; 9:48. [PMID: 31123943 PMCID: PMC6533321 DOI: 10.1186/s13550-019-0516-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 05/06/2019] [Indexed: 01/29/2023] Open
Abstract
Purpose The widespread use of 68Ga for positron emission tomography (PET) relies on the development of radiopharmaceutical precursors that can be radiolabelled and dispensed in a simple, quick, and convenient manner. The DATA (6-amino-1,4-diazapine-triacetate) scaffold represents a novel hybrid chelator architecture possessing both cyclic and acyclic character that may allow for facile access to 68Ga-labelled tracers in the clinic. We report the first bifunctional DATA chelator conjugated to [Tyr3]octreotide (TOC), a somatostatin subtype 2 receptor (SST2)-targeting vector for imaging and functional characterisation of SSTR2 expressing tumours. Methods The radiopharmaceutical precursor, DATA-TOC, was synthesised as previously described and used to complex natGa(III) and 68Ga(III). Competition binding assays of [natGa]Ga-DATA-TOC or [natGa]Ga-DOTA-TOC against [125I-Tyr25]LTT-SS28 were conducted in membranes of HEK293 cells transfected to stably express one of the hSST2,3,5 receptor subtypes (HEK293-hSST2/3/5 cells). First in vivo studies were performed in female NMRI-nude mice bearing SST2-positive mouse phaeochromocytoma mCherry (MPC-mCherry) tumours to compare the in vivo SST2-specific tumour-targeting of [68Ga]Ga-DATA-TOC and its overall pharmacokinetics versus the [68Ga]Ga-DOTA-TOC reference. A direct comparison of [68Ga]Ga-DATA-TOC with the well-established PET radiotracer [68Ga]Ga-DOTA-TOC was additionally performed in a 46-year-old male patient with a well-differentiated NET (neuroendocrine tumour), representing the first in human administration of [68Ga]Ga-DATA-TOC. Results DATA-TOC was labelled with 68Ga with a radiolabelling efficiency of > 95% in less than 10 min at ambient temperature. A molar activity up to 35 MBq/nmol was achieved. The hSST2-affinities of [natGa]Ga-DATA-TOC and [natGa]Ga-DOTA-TOC were found similar with only sub-nanomolar differences in the respective IC50 values. In mice, [68Ga]Ga-DATA-TOC was able to visualise the tumour lesions, showing standardised uptake values (SUVs) similar to [68Ga]Ga-DOTA-TOC. Direct comparison of the two PET tracers in a NET patient revealed very similar tumour uptake for the two 68Ga-radiotracers, but with a higher tumour-to-liver contrast for [68Ga]Ga-DATA-TOC. Conclusion [68Ga]Ga-DATA-TOC was prepared, to a quality appropriate for in vivo use, following a highly efficient kit type process. Furthermore, the novel radiopharmaceutical was comparable or better than [68Ga]Ga-DOTA-TOC in all preclinical tests, achieving a higher tumour-to-liver contrast in a NET-patient. The results illustrate the potential of the DATA-chelator to facilitate the access to and preparation of 68Ga-radiotracers in a routine clinical radiopharmacy setting. Electronic supplementary material The online version of this article (10.1186/s13550-019-0516-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jean-Philippe Sinnes
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Johannes Nagel
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Bradley P Waldron
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Theodosia Maina
- Molecular Radiopharmacy, INRASTES NCSR 'Demokritos', Athens, Greece
| | - Berthold A Nock
- Molecular Radiopharmacy, INRASTES NCSR 'Demokritos', Athens, Greece
| | - Ralf K Bergmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.,School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Michael Bachmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden, Germany.,Technische Universität Dresden, Universitätsklinikum 'Carl Gustav Carus', UniversitätsKrebsCentrum (UCC), Tumorimmunology, Dresden, Germany.,National Center for Tumor Diseases (NCT), Technische Universität Dresden, Dresden, Germany
| | - Richard P Baum
- Zentralklinik Bad Berka GmbH, Clinic for Molecular Radiotherapy, Bad Berka, Germany
| | - Frank Rösch
- Institute of Nuclear Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany.
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9
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Franco Machado J, Silva RD, Melo R, G Correia JD. Less Exploited GPCRs in Precision Medicine: Targets for Molecular Imaging and Theranostics. Molecules 2018; 24:E49. [PMID: 30583594 PMCID: PMC6337414 DOI: 10.3390/molecules24010049] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 12/07/2018] [Accepted: 12/09/2018] [Indexed: 12/18/2022] Open
Abstract
Precision medicine relies on individually tailored therapeutic intervention taking into account individual variability. It is strongly dependent on the availability of target-specific drugs and/or imaging agents that recognize molecular targets and patient-specific disease mechanisms. The most sensitive molecular imaging modalities, Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET), rely on the interaction between an imaging radioprobe and a target. Moreover, the use of target-specific molecular tools for both diagnostics and therapy, theranostic agents, represent an established methodology in nuclear medicine that is assuming an increasingly important role in precision medicine. The design of innovative imaging and/or theranostic agents is key for further accomplishments in the field. G-protein-coupled receptors (GPCRs), apart from being highly relevant drug targets, have also been largely exploited as molecular targets for non-invasive imaging and/or systemic radiotherapy of various diseases. Herein, we will discuss recent efforts towards the development of innovative imaging and/or theranostic agents targeting selected emergent GPCRs, namely the Frizzled receptor (FZD), Ghrelin receptor (GHSR-1a), G protein-coupled estrogen receptor (GPER), and Sphingosine-1-phosphate receptor (S1PR). The pharmacological and clinical relevance will be highlighted, giving particular attention to the studies on the synthesis and characterization of targeted molecular imaging agents, biological evaluation, and potential clinical applications in oncology and non-oncology diseases. Whenever relevant, supporting computational studies will be also discussed.
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Affiliation(s)
- João Franco Machado
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
- Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal.
| | - Rúben D Silva
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
| | - Rita Melo
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
- Center for Neuroscience and Cell Biology; Rua Larga, Faculdade de Medicina, Polo I, 1ºandar, Universidade de Coimbra, 3004-504 Coimbra, Portugal.
| | - João D G Correia
- Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, CTN, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
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10
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Abbas A, Yu L, Lalonde T, Wu D, Thiessen JD, Luyt LG, Dhanvantari S. Development and Characterization of an 18F-labeled Ghrelin Peptidomimetic for Imaging the Cardiac Growth Hormone Secretagogue Receptor. Mol Imaging 2018; 17:1536012118809587. [PMID: 30394854 PMCID: PMC6236854 DOI: 10.1177/1536012118809587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
One-third of patients with heart disease develop heart failure, which is diagnosed
through imaging and detection of circulating biomarkers. Imaging strategies reveal
morphologic and functional changes but fall short of detecting molecular abnormalities
that can lead to heart failure, and circulating biomarkers are not cardiac specific. Thus,
there is critical need for biomarkers that are endogenous to myocardial tissues. The
cardiac growth hormone secretagogue receptor 1a (GHSR1a), which binds the hormone ghrelin,
is a potential biomarker for heart failure. We have synthesized and characterized a novel
ghrelin peptidomimetic tracer, an 18F-labeled analogue of G-7039, for positron
emission tomography (PET) imaging of cardiac GHSR1a. In vitro analysis showed enhanced
serum stability compared to natural ghrelin and significantly increased cellular uptake in
GHSR1a-expressing OVCAR cells. Biodistribution studies in mice showed that tissue uptake
of the tracer was independent of circulating ghrelin levels, and there was negligible
cardiac uptake and high uptake in the liver, intestines, and kidneys. Specificity of
tracer uptake was assessed using ghsr −/− mice; both static and dynamic PET imaging revealed no difference in cardiac
uptake, and there was no significant correlation between cardiac standardized uptake
values and GHSR1a expression. Our study lays the groundwork for further refinement of
peptidomimetic PET tracers targeting cardiac GHSR1a.
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Affiliation(s)
- Ahmed Abbas
- 1 Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Lihai Yu
- 2 Department of Chemistry, Western University, London, Ontario, Canada
| | - Tyler Lalonde
- 2 Department of Chemistry, Western University, London, Ontario, Canada
| | - Derek Wu
- 3 Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada
| | - Jonathan D Thiessen
- 1 Department of Medical Biophysics, Western University, London, Ontario, Canada.,4 Imaging Research, Lawson Health Research Institute, London, Ontario, Canada
| | - Leonard G Luyt
- 2 Department of Chemistry, Western University, London, Ontario, Canada.,4 Imaging Research, Lawson Health Research Institute, London, Ontario, Canada.,5 Department of oncology, Western University, London, Ontario, Canada
| | - Savita Dhanvantari
- 1 Department of Medical Biophysics, Western University, London, Ontario, Canada.,3 Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada.,4 Imaging Research, Lawson Health Research Institute, London, Ontario, Canada.,6 Metabolism/Diabetes, Lawson Health Research Institute, London, Ontario, Canada
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11
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Charron CL, McFarland MS, Dhanvantari S, Luyt LG. Development of a [ 68Ga]-ghrelin analogue for PET imaging of the ghrelin receptor (GHS-R1a). MEDCHEMCOMM 2018; 9:1761-1767. [PMID: 30429981 DOI: 10.1039/c8md00210j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 09/09/2018] [Indexed: 01/16/2023]
Abstract
The ghrelin receptor is a member of the growth hormone secretagogue receptor (GHS-R) family and is present at low concentrations in tissues such as the brain, kidney, cardiovascular system, and prostate. The ghrelin receptor plays an important role in cellular proliferation, apoptosis, invasion, and migration associated with the progression of many cancers, including prostate, breast, ovarian, testicular, and intestinal carcinomas. Ghrelin, the endogenous ligand, is a 28 amino acid peptide (IC50 = 3.1 nM) known to have poor in vivo stability. Herein, we report the synthesis and evaluation of [Dpr3(octanoyl),Lys19(Ga-DOTA)]ghrelin(1-19). This new ghrelin analogue has a binding affinity (IC50 = 5.9 nM) comparable to that of natural ghrelin. Preliminary in vivo evaluation shows higher uptake of [Dpr3(octanoyl),Lys19(68Ga-DOTA)]ghrelin(1-19) in HT1080/GHSR-1a xenografts than the non-transfected HT1080 xenografts in NOD-SCID mice, although considerable uptake is observed in the kidneys. This is the first example of ghrelin receptor PET imaging in a xenograft model using a peptide derived directly from the endogenous ligand and serves as motivation for developing more effective ghrelin-based radiopeptides.
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Affiliation(s)
- C L Charron
- Department of Chemistry , University of Western Ontario , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada .
| | - M S McFarland
- Department of Chemistry , University of Western Ontario , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada .
| | - S Dhanvantari
- Lawson Health Research Institute , 268 Grosvenor Street , London , Ontario N6A 4V2 , Canada.,Departments of Medical Biophysics , University of Western Ontario , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada
| | - L G Luyt
- Department of Chemistry , University of Western Ontario , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada . .,Department of Oncology , University of Western Ontario , 1151 Richmond Street , London , Ontario N6A 5B7 , Canada.,London Regional Cancer Program , Lawson Health Research Institute , 800 Commissioners Road East , London , Ontario N6A 5W9 , Canada
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12
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Fowkes MM, Lalonde T, Yu L, Dhanvantari S, Kovacs MS, Luyt LG. Peptidomimetic growth hormone secretagogue derivatives for positron emission tomography imaging of the ghrelin receptor. Eur J Med Chem 2018; 157:1500-1511. [PMID: 30282322 DOI: 10.1016/j.ejmech.2018.08.062] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 08/16/2018] [Accepted: 08/22/2018] [Indexed: 02/06/2023]
Abstract
The ghrelin receptor is a seven-transmembrane (7-TM) receptor known to have an increased level of expression in human carcinoma and heart failure. Recent work has focused on the synthesis of positron emission tomography (PET) probes designed to target and image this receptor for disease diagnosis and staging. However, these probes have been restricted to small-molecule quinalizonones and peptide derivatives of the endogenous ligand ghrelin. We describe the design, synthesis and biological evaluation of a series of 4-fluorobenzoylated growth hormone secretagogues (GHSs) derived from peptidic (GHRP-1, GHPR-2 and GHRP-6) and peptidomimetic (G-7039, [1-Nal4]G-7039 and ipamorelin) families in order to test locations for the insertion of fluorine-18 for PET imaging. The peptidomimetic G-7039 was found to be the most suitable for 18F-radiolabelling as its non-radioactive 4-fluorobenzoylated analogue ([1-Nal4,Lys5(4-FB)]G-7039), had both a high binding affinity (IC50 = 69 nM) and promising in vitro efficacy (EC50 = 1.1 nM). Prosthetic group radiolabelling of the precursor compound [1-Nal4]G-7039 using N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) delivered the PET probe [1-Nal4,Lys5(4-[18F]-FB)]G-7039 in an average decay-corrected radiochemical yield of 48%, a radio-purity ≥ 99% and an average molar activity of >34 GBq/μmol. This compound could be investigated as a PET probe for the detection of diseases that are characterised by overexpression of the ghrelin receptor.
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Affiliation(s)
- Milan M Fowkes
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada; London Regional Cancer Program, Lawson Health Research Institute, 790 Commissioners Road East, London, Ontario, N6A 4L6, Canada
| | - Tyler Lalonde
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada; London Regional Cancer Program, Lawson Health Research Institute, 790 Commissioners Road East, London, Ontario, N6A 4L6, Canada
| | - Lihai Yu
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada; London Regional Cancer Program, Lawson Health Research Institute, 790 Commissioners Road East, London, Ontario, N6A 4L6, Canada
| | - Savita Dhanvantari
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario, N6A 4V2, Canada
| | - Michael S Kovacs
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario, N6A 4V2, Canada
| | - Leonard G Luyt
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario, N6A 5B7, Canada; London Regional Cancer Program, Lawson Health Research Institute, 790 Commissioners Road East, London, Ontario, N6A 4L6, Canada; Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario, N6A 4V2, Canada.
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13
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Hou J, Kovacs MS, Dhanvantari S, Luyt LG. Development of Candidates for Positron Emission Tomography (PET) Imaging of Ghrelin Receptor in Disease: Design, Synthesis, and Evaluation of Fluorine-Bearing Quinazolinone Derivatives. J Med Chem 2018; 61:1261-1275. [DOI: 10.1021/acs.jmedchem.7b01754] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jinqiang Hou
- London Regional Cancer Program, London N6A 4L6, Canada
- Lawson Health Research Institute, London N6C 2R5, Canada
| | | | | | - Leonard G. Luyt
- London Regional Cancer Program, London N6A 4L6, Canada
- Lawson Health Research Institute, London N6C 2R5, Canada
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14
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15
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Charron CL, Hou J, McFarland MS, Dhanvantari S, Kovacs MS, Luyt LG. Structure–Activity Study of Ghrelin(1–8) Resulting in High Affinity Fluorine-Bearing Ligands for the Ghrelin Receptor. J Med Chem 2017; 60:7256-7266. [DOI: 10.1021/acs.jmedchem.7b00164] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Carlie L. Charron
- Department
of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
| | - Jinqiang Hou
- London
Regional Cancer Program, Lawson Health Research Institute, 790 Commissioners Road East, London, Ontario N6A 4L6, Canada
| | - Mark S. McFarland
- Department
of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
| | - Savita Dhanvantari
- Imaging
Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
- Department
of Medical Biophysics, University of Western Ontario, 1151 Richmond
Street, London, Ontario N6A 5B7, Canada
| | - Michael S. Kovacs
- Imaging
Program, Lawson Health Research Institute, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
- Department
of Medical Biophysics, University of Western Ontario, 1151 Richmond
Street, London, Ontario N6A 5B7, Canada
| | - Leonard G. Luyt
- Department
of Chemistry, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
- London
Regional Cancer Program, Lawson Health Research Institute, 790 Commissioners Road East, London, Ontario N6A 4L6, Canada
- Departments
of Oncology and Medical Imaging, University of Western Ontario, 1151
Richmond Street, London, Ontario N6A 5B7, Canada
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16
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Clarifying the Ghrelin System's Ability to Regulate Feeding Behaviours Despite Enigmatic Spatial Separation of the GHSR and Its Endogenous Ligand. Int J Mol Sci 2017; 18:ijms18040859. [PMID: 28422060 PMCID: PMC5412441 DOI: 10.3390/ijms18040859] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/04/2017] [Accepted: 04/11/2017] [Indexed: 12/23/2022] Open
Abstract
Ghrelin is a hormone predominantly produced in and secreted from the stomach. Ghrelin is involved in many physiological processes including feeding, the stress response, and in modulating learning, memory and motivational processes. Ghrelin does this by binding to its receptor, the growth hormone secretagogue receptor (GHSR), a receptor found in relatively high concentrations in hypothalamic and mesolimbic brain regions. While the feeding and metabolic effects of ghrelin can be explained by the effects of this hormone on regions of the brain that have a more permeable blood brain barrier (BBB), ghrelin produced within the periphery demonstrates a limited ability to reach extrahypothalamic regions where GHSRs are expressed. Therefore, one of the most pressing unanswered questions plaguing ghrelin research is how GHSRs, distributed in brain regions protected by the BBB, are activated despite ghrelin’s predominant peripheral production and poor ability to transverse the BBB. This manuscript will describe how peripheral ghrelin activates central GHSRs to encourage feeding, and how central ghrelin synthesis and ghrelin independent activation of GHSRs may also contribute to the modulation of feeding behaviours.
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17
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Moldovan RP, Els-Heindl S, Worm DJ, Kniess T, Kluge M, Beck-Sickinger AG, Deuther-Conrad W, Krügel U, Brust P. Development of Fluorinated Non-Peptidic Ghrelin Receptor Ligands for Potential Use in Molecular Imaging. Int J Mol Sci 2017; 18:ijms18040768. [PMID: 28379199 PMCID: PMC5412352 DOI: 10.3390/ijms18040768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/23/2017] [Accepted: 03/31/2017] [Indexed: 12/19/2022] Open
Abstract
The ghrelin receptor (GhrR) is a widely investigated target in several diseases. However, the current knowledge of its role and distribution in the brain is limited. Recently, the small and non-peptidic compound (S)-6-(4-bromo-2-fluorophenoxy)-3-((1-isopropylpiperidin-3-yl)methyl)-2-methylpyrido[3,2-d]pyrimidin-4(3H)-one ((S)-9) has been described as a GhrR ligand with high binding affinity. Here, we describe the synthesis of fluorinated derivatives, the in vitro evaluation of their potency as partial agonists and selectivity at GhrRs, and their physicochemical properties. These results identified compounds (S)-9, (R)-9, and (S)-16 as suitable parent molecules for 18F-labeled positron emission tomography (PET) radiotracers to enable future investigation of GhrR in the brain.
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Affiliation(s)
- Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
| | - Sylvia Els-Heindl
- Institute of Biochemistry, Universität Leipzig, 04103 Leipzig, Germany.
| | - Dennis J Worm
- Institute of Biochemistry, Universität Leipzig, 04103 Leipzig, Germany.
| | - Torsten Kniess
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
| | - Michael Kluge
- Department of Psychiatry, Universität Leipzig, 04103 Leipzig, Germany.
| | | | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
| | - Ute Krügel
- Rudolf Boehm Institute of Pharmacology and Toxicology, Medical Faculty, Universität Leipzig, 04107 Leipzig, Germany.
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
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18
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Cryogel-supported stem cell factory for customized sustained release of bispecific antibodies for cancer immunotherapy. Sci Rep 2017; 7:42855. [PMID: 28205621 PMCID: PMC5311951 DOI: 10.1038/srep42855] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/18/2017] [Indexed: 12/21/2022] Open
Abstract
Combining stem cells with biomaterial scaffolds provides a promising strategy for the development of drug delivery systems. Here we propose an innovative immunotherapeutic organoid by housing human mesenchymal stromal cells (MSCs), gene-modified for the secretion of an anti-CD33-anti-CD3 bispecific antibody (bsAb), in a small biocompatible star-shaped poly(ethylene glycol)-heparin cryogel scaffold as a transplantable and low invasive therapeutic machinery for the treatment of acute myeloid leukemia (AML). The macroporous biohybrid cryogel platform displays effectiveness in supporting proliferation and survival of bsAb-releasing-MSCs overtime in vitro and in vivo, avoiding cell loss and ensuring a constant release of sustained and detectable levels of bsAb capable of triggering T-cell-mediated anti-tumor responses and a rapid regression of CD33+ AML blasts. This therapeutic device results as a promising and safe alternative to the continuous administration of short-lived immunoagents and paves the way for effective bsAb-based therapeutic strategies for future tumor treatments.
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19
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Els-Heindl S, Bellmann-Sickert K, Beck-Sickinger AG. C-terminus of a hexapeptidic ghrelin receptor inverse agonist can switch peptide behavior from inverse agonism to agonism. Biopolymers 2017; 106:101-8. [PMID: 26566778 DOI: 10.1002/bip.22768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 11/10/2022]
Abstract
Subtle changes in the sequence at the N-terminus and in the aromatic core of hexapeptidic ghrelin receptor inverse agonists can switch behavior from inverse agonism to agonism, but the C-terminal role of the sequence is unclear. Thus, analogs of the ghrelin receptor inverse agonist KbFwLL-NH2 (b = β-(3-benzothienyl)-d-alanine) were synthesized by solid phase peptide synthesis in order to identify the influence of aromaticity, charge, and hydrophobicity. Potency and efficacy of the hexapeptides were evaluated in inositol triphosphate turnover assays. Notably, modifications directly at the C-terminal Leu(6) could influence peptide efficacy leading to decreased constitutive activity. High hydrophobicity at the C-terminal position was of importance for elevated inverse agonist activity, the introduction of charged amino acids led to decreased potency. In contrast, structure-activity relationship studies of Leu(5) located closer to the aromatic core revealed an agonism-inducing position. These findings imply that amino acids with possible cation-π or π-π interactions and a suitable orientation at the C-terminus of the aromatic core induce agonism. Receptor binding studies showed that most peptides bind to the receptor at a concentration of 1 µM and modification directly at the C-terminus is generally more accepted than Leu(5) substitution. Interestingly, this observation is not dependent on the type of modification. These studies reveal another switch region of the short ghrelin receptor ligand pointing out the sensitivity of the ghrelin receptor binding pocket.
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Affiliation(s)
- Sylvia Els-Heindl
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, Leipzig, 04103, Germany
| | - Kathrin Bellmann-Sickert
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, Leipzig, 04103, Germany
| | - Annette G Beck-Sickinger
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, Leipzig, 04103, Germany
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20
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Xie F, Bergmann R, Kniess T, Deuther-Conrad W, Mamat C, Neuber C, Liu B, Steinbach J, Brust P, Pietzsch J, Jia H. (18)F-Labeled 1,4-Dioxa-8-azaspiro[4.5]decane Derivative: Synthesis and Biological Evaluation of a σ1 Receptor Radioligand with Low Lipophilicity as Potent Tumor Imaging Agent. J Med Chem 2015; 58:5395-407. [PMID: 26090686 DOI: 10.1021/acs.jmedchem.5b00593] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We report the syntheses and evaluation of series of novel piperidine compounds with low lipophilicity as σ1 receptor ligands. 8-(4-(2-Fluoroethoxy)benzyl)-1,4-dioxa-8-azaspiro[4.5]decane (5a) possessed high affinity (K(i) = 5.4 ± 0.4 nM) for σ1 receptors and selectivity for σ2 receptors (30-fold) and the vesicular acetylcholine transporter (1404-fold). [(18)F]5a was prepared using a one-pot, two-step labeling procedure in an automated synthesis module, with a radiochemical purity of >95%, and a specific activity of 25-45 GBq/μmol. Cellular association, biodistribution, and autoradiography with blocking experiments indicated specific binding of [(18)F]5a to σ1 receptors in vitro and in vivo. Small animal positron emission tomography (PET) imaging using mouse tumor xenograft models demonstrated a high accumulation in human carcinoma and melanoma. Treatment with haloperidol significantly reduced the accumulation of the radiotracer in tumors. These findings suggest that radiotracer with suitable lipophilicity and appropriate affinity for σ1 receptors could be used for tumor imaging.
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Affiliation(s)
- Fang Xie
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,‡Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ralf Bergmann
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Torsten Kniess
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Winnie Deuther-Conrad
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Constantin Mamat
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,§Technische Universität Dresden, Department of Chemistry and Food Chemistry, D-01062 Dresden, Germany
| | - Christin Neuber
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Boli Liu
- ‡Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jörg Steinbach
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,§Technische Universität Dresden, Department of Chemistry and Food Chemistry, D-01062 Dresden, Germany
| | - Peter Brust
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Jens Pietzsch
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,§Technische Universität Dresden, Department of Chemistry and Food Chemistry, D-01062 Dresden, Germany
| | - Hongmei Jia
- ‡Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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21
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Kilian TM, Klöting N, Bergmann R, Els-Heindl S, Babilon S, Clément-Ziza M, Zhang Y, Beck-Sickinger AG, Chollet C. Rational design of dual peptides targeting ghrelin and Y2 receptors to regulate food intake and body weight. J Med Chem 2015; 58:4180-93. [PMID: 25905598 DOI: 10.1021/jm501702q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Ghrelin and Y2 receptors play a central role in appetite regulation inducing opposite effects. The Y2 receptor induces satiety, while the ghrelin receptor promotes hunger and weight gain. However, the food regulating system is tightly controlled by interconnected pathways where redundancies can lead to poor efficacy and drug tolerance when addressing a single molecule. We developed a multitarget strategy to synthesize dual peptides simultaneously inhibiting the ghrelin receptor and stimulating the Y2 receptor. Dual peptides showed dual activity in vitro, and one compound induced a slight diminution of food intake in a rodent model of obesity. In addition, stability studies in rats revealed different behaviors between the dual peptide and its corresponding monomers. The Y2 receptor agonist was unstable in blood, while the dual peptide showed an intermediate stability compared to that of the highly stable ghrelin receptor inverse agonist.
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Affiliation(s)
- Tom-Marten Kilian
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Nora Klöting
- ‡Integrated Research and Treatment Center Adiposity Diseases (IFB), Core Unit "Animal Models", Universität Leipzig, Liebigstrasse 21, 04103 Leipzig, Germany
| | - Ralf Bergmann
- §Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
| | - Sylvia Els-Heindl
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Stefanie Babilon
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Mathieu Clément-Ziza
- ∥CECAD - Cluster of Excellence, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Yixin Zhang
- ⊥B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstrasse 18, 01307 Dresden, Germany
| | - Annette G Beck-Sickinger
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Constance Chollet
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany.,⊥B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstrasse 18, 01307 Dresden, Germany
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22
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Rodríguez-Rodríguez A, Garda Z, Ruscsák E, Esteban-Gómez D, de Blas A, Rodríguez-Blas T, Lima LMP, Beyler M, Tripier R, Tircsó G, Platas-Iglesias C. Stable Mn2+, Cu2+ and Ln3+ complexes with cyclen-based ligands functionalized with picolinate pendant arms. Dalton Trans 2015; 44:5017-31. [DOI: 10.1039/c4dt02985b] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclen-based ligands containing two picolinate pendant arms form Gd3+ complexes remarkably stable and inert with respect to metal ion dissociation.
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Affiliation(s)
| | - Zoltán Garda
- Department of Inorganic and Analytical Chemistry
- Faculty of Science and Technology
- University of Debrecen
- H-4032 Debrecen
- Hungary
| | - Erika Ruscsák
- Department of Inorganic and Analytical Chemistry
- Faculty of Science and Technology
- University of Debrecen
- H-4032 Debrecen
- Hungary
| | | | - Andrés de Blas
- Departamento de Química Fundamental
- Universidade da Coruña
- A Coruña
- Spain
| | | | - Luís M. P. Lima
- Université de Bretagne Occidentale
- UMR-CNRS 6521
- SFR ScInBioS
- UFR des Sciences et Techniques
- 29238 Brest Cedex 3
| | - Maryline Beyler
- Université de Bretagne Occidentale
- UMR-CNRS 6521
- SFR ScInBioS
- UFR des Sciences et Techniques
- 29238 Brest Cedex 3
| | - Raphaël Tripier
- Université de Bretagne Occidentale
- UMR-CNRS 6521
- SFR ScInBioS
- UFR des Sciences et Techniques
- 29238 Brest Cedex 3
| | - Gyula Tircsó
- Department of Inorganic and Analytical Chemistry
- Faculty of Science and Technology
- University of Debrecen
- H-4032 Debrecen
- Hungary
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23
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High metabolic in vivo stability and bioavailability of a palmitoylated ghrelin receptor ligand assessed by mass spectrometry. Bioorg Med Chem 2014; 23:3925-32. [PMID: 25541202 DOI: 10.1016/j.bmc.2014.12.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/30/2014] [Accepted: 12/04/2014] [Indexed: 11/20/2022]
Abstract
The constitutive activity of the ghrelin receptor is of high physiological and pathophysiological relevance. In-depth structure-activity relationship studies revealed a palmitoylated ghrelin receptor ligand that displays an in vitro binding affinity in the low nanomolar range. Activity studies revealed inverse agonistic as well as antagonistic properties and in vitro metabolic analysis indicated a high stability in blood serum and liver homogenate. For metabolic testing in vivo, a combined approach of stable isotopic labeling and mass spectrometry-based analysis was established. Therefore, a heavy isotopic version of the peptide containing a (13)C-labeled palmitic acid was synthesized and a 1:1 ratio of a (12)C/(13)C-peptide mixture was injected into rats. Biological samples were analyzed by multiple reaction monitoring allowing simultaneous peptide detection and quantification. Measurements revealed a suitable bioavailability over 24h in rat serum and subsequent high-resolution mass spectrometry investigations showed only negligible degradation and slow body clearance. Hence, this method combination allowed the identification and evaluation of a highly potent and metabolically stable ghrelin receptor ligand in vivo.
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Callaghan B, Kosari S, Pustovit RV, Sartor DM, Ferens D, Ban K, Baell J, Nguyen TV, Rivera LR, Brock JA, Furness JB. Hypotensive effects of ghrelin receptor agonists mediated through a novel receptor. Br J Pharmacol 2014; 171:1275-86. [PMID: 24670149 DOI: 10.1111/bph.12527] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 09/27/2013] [Accepted: 11/12/2013] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Some agonists of ghrelin receptors cause rapid decreases in BP. The mechanisms by which they cause hypotension and the pharmacology of the receptors are unknown. EXPERIMENTAL APPROACH The effects of ligands of ghrelin receptors were investigated in rats in vivo, on isolated blood vessels and on cells transfected with the only molecularly defined ghrelin receptor, growth hormone secretagogue receptor 1a (GHSR1a). KEY RESULTS Three agonists of GHSR1a receptors, ulimorelin, capromorelin and CP464709, caused a rapid decrease in BP in the anaesthetized rat. The effect was not reduced by either of two GHSR1a antagonists, JMV2959 or YIL781, at doses that blocked effects on colorectal motility, in vivo. The rapid hypotension was not mimicked by ghrelin, unacylated ghrelin or the unacylated ghrelin receptor agonist, AZP531. The early hypotension preceded a decrease in sympathetic nerve activity. Early hypotension was not reduced by hexamethonium or by baroreceptor (sino-aortic) denervation. Ulimorelin also relaxed isolated segments of rat mesenteric artery, and, less potently, relaxed aorta segments. The vascular relaxation was not reduced by JMV2959 or YIL781. Ulimorelin, capromorelin and CP464709 activated GHSR1a in transfected HEK293 cells at nanomolar concentrations. JMV2959 and YIL781 both antagonized effects in these cells, with their pA2 values at the GHSR1a receptor being 6.55 and 7.84. CONCLUSIONS AND IMPLICATIONS Our results indicate a novel vascular receptor or receptors whose activation by ulimorelin, capromorelin and CP464709 lowered BP. This receptor is activated by low MW GHSR1a agonists, but is not activated by ghrelin.
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Affiliation(s)
- Brid Callaghan
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic., Australia
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25
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Abnormal relationships between the neural response to high- and low-calorie foods and endogenous acylated ghrelin in women with active and weight-recovered anorexia nervosa. Psychiatry Res 2014; 223:94-103. [PMID: 24862390 PMCID: PMC4090258 DOI: 10.1016/j.pscychresns.2014.04.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 03/03/2014] [Accepted: 04/29/2014] [Indexed: 11/20/2022]
Abstract
Evidence contributing to the understanding of neurobiological mechanisms underlying appetite dysregulation in anorexia nervosa draws heavily on separate lines of research into neuroendocrine and neural circuitry functioning. In particular, studies consistently cite elevated ghrelin and abnormal activation patterns in homeostatic (hypothalamus) and hedonic (striatum, amygdala, insula) regions governing appetite. The current preliminary study examined the interaction of these systems, based on research demonstrating associations between circulating ghrelin levels and activity in these regions in healthy individuals. In a cross-sectional design, we studied 13 women with active anorexia nervosa (AN), 9 women weight-recovered from AN (AN-WR), and 12 healthy-weight control women using a food cue functional magnetic resonance imaging paradigm, with assessment of fasting levels of acylated ghrelin. Healthy-weight control women exhibited significant positive associations between fasting acylated ghrelin and activity in the right amygdala, hippocampus, insula, and orbitofrontal cortex in response to high-calorie foods, associations which were absent in the AN and AN-WR groups. Women with AN-WR demonstrated a negative relationship between ghrelin and activity in the left hippocampus in response to high-calorie foods, while women with AN showed a positive association between ghrelin and activity in the right orbitofrontal cortex in response to low-calorie foods. Findings suggest a breakdown in the interaction between ghrelin signaling and neural activity in relation to reward responsivity in AN, a phenomenon that may be further characterized using pharmacogenetic studies.
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26
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Callaghan B, Furness JB. Novel and Conventional Receptors for Ghrelin, Desacyl-Ghrelin, and Pharmacologically Related Compounds. Pharmacol Rev 2014; 66:984-1001. [DOI: 10.1124/pr.113.008433] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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27
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Camus N, Halime Z, Le Bris N, Bernard H, Platas-Iglesias C, Tripier R. Full Control of the Regiospecific N-Functionalization of C-Functionalized Cyclam Bisaminal Derivatives and Application to the Synthesis of their TETA, TE2A, and CB-TE2A Analogues. J Org Chem 2014; 79:1885-99. [DOI: 10.1021/jo4028566] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Nathalie Camus
- Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences
et Techniques, 6 Avenue Victor le Gorgeu,
C.S. 93837, 29238 Brest, France
| | - Zakaria Halime
- Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences
et Techniques, 6 Avenue Victor le Gorgeu,
C.S. 93837, 29238 Brest, France
| | - Nathalie Le Bris
- Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences
et Techniques, 6 Avenue Victor le Gorgeu,
C.S. 93837, 29238 Brest, France
| | - Hélène Bernard
- Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences
et Techniques, 6 Avenue Victor le Gorgeu,
C.S. 93837, 29238 Brest, France
| | - Carlos Platas-Iglesias
- Departamento
de Química Fundamental, Universidade da Coruña, Campus
da Zapateira, Rúa da Fraga 10, 15008 A Coruña, Spain
| | - Raphaël Tripier
- Université de Brest, UMR-CNRS 6521/SFR148 ScInBioS, UFR Sciences
et Techniques, 6 Avenue Victor le Gorgeu,
C.S. 93837, 29238 Brest, France
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28
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Meckel M, Fellner M, Thieme N, Bergmann R, Kubicek V, Rösch F. In vivo comparison of DOTA based 68Ga-labelled bisphosphonates for bone imaging in non-tumour models. Nucl Med Biol 2014; 40:823-30. [PMID: 23915801 DOI: 10.1016/j.nucmedbio.2013.04.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/26/2013] [Accepted: 04/29/2013] [Indexed: 01/28/2023]
Abstract
Bone metastases are a class of cancerous metastases that result from the invasion of a tumor into bone. The solid mass which forms inside the bone is often associated with a constant dull ache and severe spikes in pain, which greatly reduce the quality of life of the patient. Numerous (99m)Tc-labeled bisphosphonate functionalised complexes are well established tracers for bone metastases imaging. The objective of this research was to evaluate the pharmacokinetics and behaviour of three DOTA based bisphosphonate functionalised ligands (BPAMD, BPAPD and BPPED), using both (68)Ga μ-PET in vivo imaging and ex vivo biodistribution studies in healthy Wistar rats. The compounds were labelled with (68)Ga in high yields using an ammonium acetate buffer, and subsequently purified using a cation exchange resin. High bone uptake values were observed for all (68)Ga-labelled bisphosphonates at 60 minutes p.i. The highest uptake was observed for [(68)Ga]BPPED (2.6 ± 0.3% ID/g) which compares favourably with that of [(99m)Tc]MDP (2.7 ± 0.1 ID/g) and [(18)F]fluoride (2.4 ± 0.2% ID/g). The (68)Ga-labelled DOTA-bisphosphonates showed rapid clearance from the blood and renal system, as well as low binding to soft tissue, resulting in a high bone to blood ratio (9.9 at 60 minutes p.i. for [(68)Ga]BPPED, for example). Although further studies are required to assess their performance in tumor models, the results obtained suggest that these ligands could be useful both in imaging ((68)Ga) and therapeutic treatment ((177)Lu) of bone metastases.
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Affiliation(s)
- Marian Meckel
- Institute of Nuclear Chemistry, Johannes-Gutenberg-University Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz, Germany
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29
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Abstract
Ingestion of food affects the secretion of hormones from specialized endocrine cells scattered within the intestinal mucosa. Upon release, these hormones mostly decrease food intake by signaling information to the brain. Although enteroendocrine cells in the small intestine were thought to represent the predominant gut-brain regulators of food intake, recent advances also established a major role for gastric hormones in these regulatory pathways. First and foremost, the gastric endocrine X/A-like cell was in the focus of many studies due to the production of ghrelin, which is until now the only known orexigenic hormone that is peripherally produced and centrally acting. Although X/A-cells were initially thought to only release one hormone that stimulates food intake, this view has changed with the identification of additional peptide products also derived from this cell, namely desacyl ghrelin, obestatin, and nesfatin-1. Desacyl ghrelin may play a counter-regulatory role to the food intake stimulatory effect of ghrelin. The same property was suggested for obestatin; however, this hypothesis could not be confirmed in numerous subsequent studies. Moreover, the description of the stomach as the major source of the novel anorexigenic hormone nesfatin-1 derived from the NUCB2 gene further corroborated the assumption that the gastric X/A-like cell products are not only stimulant but also inhibitors of feeding, thereby acting as so far unique dual regulator of food intake located in a logistically important place where the gastrointestinal tract has initial contact with food.
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Affiliation(s)
- Andreas Stengel
- Charité Center for Internal Medicine and Dermatology, Division Psychosomatic Medicine, Obesity Center Berlin, Charité Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany.
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30
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Chopin LK, Seim I, Walpole CM, Herington AC. The ghrelin axis--does it have an appetite for cancer progression? Endocr Rev 2012; 33:849-91. [PMID: 22826465 DOI: 10.1210/er.2011-1007] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHSR), is a peptide hormone with diverse physiological roles. Ghrelin regulates GH release, appetite and feeding, gut motility, and energy balance and also has roles in the cardiovascular, immune, and reproductive systems. Ghrelin and the GHSR are expressed in a wide range of normal and tumor tissues, and a fluorescein-labeled, truncated form of ghrelin is showing promise as a biomarker for prostate cancer. Plasma ghrelin levels are generally inversely related to body mass index and are unlikely to be useful as a biomarker for cancer, but may be useful as a marker for cancer cachexia. Some single nucleotide polymorphisms in the ghrelin and GHSR genes have shown associations with cancer risk; however, larger studies are required. Ghrelin regulates processes associated with cancer, including cell proliferation, apoptosis, cell migration, cell invasion, inflammation, and angiogenesis; however, the role of ghrelin in cancer is currently unclear. Ghrelin has predominantly antiinflammatory effects and may play a role in protecting against cancer-related inflammation. Ghrelin and its analogs show promise as treatments for cancer-related cachexia. Further studies using in vivo models are required to determine whether ghrelin has a role in cancer progression.
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Affiliation(s)
- Lisa K Chopin
- Ghrelin Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Australian Prostate Cancer Research Centre-Queensland, Brisbane, Queensland 4001, Australia.
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