1
|
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.
Collapse
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
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Bukhari SNA. An insight into the multifunctional role of ghrelin and structure activity relationship studies of ghrelin receptor ligands with clinical trials. Eur J Med Chem 2022; 235:114308. [PMID: 35344905 DOI: 10.1016/j.ejmech.2022.114308] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 02/06/2022] [Accepted: 03/18/2022] [Indexed: 11/30/2022]
Abstract
Ghrelin is a multifunctional gastrointestinal acylated peptide, primarily synthesized in the stomach and regulates the secretion of growth hormone and energy homeostasis. It plays a central role in modulating the diverse biological, physiological and pathological functions in vertebrates. The synthesis of ghrelin receptor ligands after the finding of growth hormone secretagogue developed from Met-enkephalin led to reveal the endogenous ligand ghrelin and the receptors. Subsequently, many peptides, small molecules and peptidomimetics focusing on the ghrelin receptor, GHS-R1a, were derived. In this review, the key features of ghrelin's structure, forms, its bio-physiological functions, pathological roles and therapeutic potential have been highlighted. A few peptidomimetics and pseudo peptide synthetic perspectives have also been discussed to make ghrelin receptor ligands, clinical trials and their success.
Collapse
Affiliation(s)
- Syed Nasir Abbas Bukhari
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jouf University, Sakaka, Aljouf, 2014, Saudi Arabia.
| |
Collapse
|
4
|
Giorgioni G, Del Bello F, Quaglia W, Botticelli L, Cifani C, Micioni Di Bonaventura E, Micioni Di Bonaventura MV, Piergentili A. Advances in the Development of Nonpeptide Small Molecules Targeting Ghrelin Receptor. J Med Chem 2022; 65:3098-3118. [PMID: 35157454 PMCID: PMC8883476 DOI: 10.1021/acs.jmedchem.1c02191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ghrelin is an octanoylated peptide acting by the activation of the growth hormone secretagogue receptor, namely, GHS-R1a. The involvement of ghrelin in several physiological processes, including stimulation of food intake, gastric emptying, body energy balance, glucose homeostasis, reduction of insulin secretion, and lipogenesis validates the considerable interest in GHS-R1a as a promising target for the treatment of numerous disorders. Over the years, several GHS-R1a ligands have been identified and some of them have been extensively studied in clinical trials. The recently resolved structures of GHS-R1a bound to ghrelin or potent ligands have provided useful information for the design of new GHS-R1a drugs. This perspective is focused on the development of recent nonpeptide small molecules acting as GHS-R1a agonists, antagonists, and inverse agonists, bearing classical or new molecular scaffolds, as well as on radiolabeled GHS-R1a ligands developed for imaging. Moreover, the pharmacological effects of the most studied ligands have been discussed.
Collapse
Affiliation(s)
- Gianfabio Giorgioni
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| | - Fabio Del Bello
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| | - Wilma Quaglia
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| | - Luca Botticelli
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - E Micioni Di Bonaventura
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - M V Micioni Di Bonaventura
- School of Pharmacy, Pharmacology Unit, University of Camerino, Via Madonna delle Carceri 9, 62032 Camerino, Italy
| | - Alessandro Piergentili
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
| |
Collapse
|
5
|
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.
Collapse
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
| | | |
Collapse
|
6
|
Ye H, Yang Y, Chen R, Shi X, Fang Y, Yang J, Dong Y, Chen L, Xia J, Wang C, Yang C, Feng J, Wang Y, Feng X, Lü C. Recognition of Invasive Prostate Cancer Using a GHRL Polypeptide Probe Targeting GHSR in a Mouse Model In Vivo. Curr Pharm Des 2020; 26:1614-1621. [PMID: 31880242 DOI: 10.2174/1381612826666191227160001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/23/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Ghrelin (GHRL) is a polypeptide that can specifically bind to the growth hormone secretagogue receptor (GHSR). The expression of GHSR is significantly different in normal and prostate cancer (PC) tissues in humans. It is important to find an effective diagnostic method for the diagnosis and prognosis of invasive PC/neuroendocrine prostate cancer (NEPC). METHODS GHRL and GHSR mRNA levels were determined by a quantitative real-time polymerase chain reaction in PC tissues. The expression of GHRL and GHSR proteins was assessed by Western blot assay and immunohistochemistry. A GHRL polypeptide probe was synthesized by standard solid-phase polypeptide synthesis, and labeled with Alexa Fluor 660. Confocal microscopy was used to capture fluorescence images. Living imaging analysis showed tumor areas of different invasiveness in mice models. RESULTS The levels of GHRL and GHSR copy number amplification and mRNA expression were increased in invasive PC/NEPC, and the protein expression levels of GHRL and GHSR were similarly increased in NEPC. The GHRL polypeptide probe could effectively bind to GHSR. In PC3 cells, it was found that the GHRL probe specifically binds to GHSR on the cell membrane and accumulates in the cells through internalization after binding. Live imaging in mice models showed that there were different signal intensities in tumor areas with different invasiveness. CONCLUSION GHSR and GHRL might be used in molecular imaging diagnosis for invasive PC/NEPC in the future.
Collapse
Affiliation(s)
- Huamao Ye
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Yue Yang
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Rui Chen
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Xiaolei Shi
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Yu Fang
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Jun Yang
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Yuanzhen Dong
- State Key Laboratory of Innovative Drugs and Pharmaceutical Technology, Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Lili Chen
- State Key Laboratory of Innovative Drugs and Pharmaceutical Technology, Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Jianghua Xia
- State Key Laboratory of Innovative Drugs and Pharmaceutical Technology, Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Chao Wang
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Chenghua Yang
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Jun Feng
- State Key Laboratory of Innovative Drugs and Pharmaceutical Technology, Shanghai Institute of Pharmaceutical Industry, Shanghai, China
| | - Yang Wang
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Xiang Feng
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China
| | - Chen Lü
- Department of Urology, Shanghai Changhai Hospital Affiliated to the Second Military Medical University, Shanghai, China.,Department of Urology, Shanghai East Hospital Affiliated to Shanghai Tongji University, Shanghai, China
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|