1
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Liu W, Hopkins AM, Yan P, Du S, Luyt LG, Li Y, Hou J. Can machine learning 'transform' peptides/peptidomimetics into small molecules? A case study with ghrelin receptor ligands. Mol Divers 2023; 27:2239-2255. [PMID: 36331785 DOI: 10.1007/s11030-022-10555-w] [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: 09/06/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022]
Abstract
There has been considerable interest in transforming peptides into small molecules as peptide-based molecules often present poorer bioavailability and lower metabolic stability. Our studies looked into building machine learning (ML) models to investigate if ML is able to identify the 'bioactive' features of peptides and use the features to accurately discriminate between binding and non-binding small molecules. The ghrelin receptor (GR), a receptor that is implicated in various diseases, was used as an example to demonstrate whether ML models derived from a peptide library can be used to predict small molecule binders. ML models based on three different algorithms, namely random forest, support vector machine, and extreme gradient boosting, were built based on a carefully curated dataset of peptide/peptidomimetic and small molecule GR ligands. The results indicated that ML models trained with a dataset exclusively composed of peptides/peptidomimetics provide limited predictive power for small molecules, but that ML models trained with a diverse dataset composed of an array of both peptides/peptidomimetics and small molecules displayed exceptional results in terms of accuracy and false rates. The diversified models can accurately differentiate the binding small molecules from non-binding small molecules using an external validation set with new small molecules that we synthesized previously. Structural features that are the most critical contributors to binding activity were extracted and are remarkably consistent with the crystallography and mutagenesis studies.
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Affiliation(s)
- Wenjie Liu
- Department of Chemistry, Lakehead University and Thunder Bay Regional Health Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada
| | - Austin M Hopkins
- Department of Chemistry, Lakehead University and Thunder Bay Regional Health Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada
| | - Peizhi Yan
- Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, BC, Canada
| | - Shan Du
- Department of Computer Science, Mathematics, Physics and Statistics, The University of British Columbia, Okanagan, Kelowna, BC, Canada
| | - Leonard G Luyt
- Department of Chemistry, University of Western Ontario, London, ON, Canada
- London Regional Cancer Program, Lawson Health Research Institute, London, ON, Canada
| | - Yifeng Li
- Department of Computer Science, Brock University, Saint Catharines, ON, Canada
| | - Jinqiang Hou
- Department of Chemistry, Lakehead University and Thunder Bay Regional Health Research Institute, 980 Oliver Road, Thunder Bay, ON, P7B 6V4, Canada.
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2
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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.
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Affiliation(s)
- Syed Nasir Abbas Bukhari
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jouf University, Sakaka, Aljouf, 2014, Saudi Arabia.
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3
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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.
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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
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4
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Abstract
2-Aminopyridine is a simple, low molecular weight and perfectly functionalised moiety known for the synthesis of diverse biological molecules. Many pharmaceutical companies across the globe aim to synthesise low-molecular weight molecules for use as pharmacophores against various biological targets. 2-Aminopyridine can serve as a perfect locomotive in the synthesis and pulling of such molecules towards respective pharmacological goals. The major advantage of this moiety is its simple design, which can be used to produce single products with minimum side reactions. Moreover, the exact weight of synthesised compounds is low, which enables facile identification of toxicity-causing metabolites in drug discovery programmes. This manuscript is a quick review of such pharmacophores derived from 2-aminopyridine.
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Affiliation(s)
- Ramdas Nishanth Rao
- Department of Chemistry, School of Advanced Science, Vellore Institute of Technology, Vellore 632014, India.
| | - Kaushik Chanda
- Department of Chemistry, School of Advanced Science, Vellore Institute of Technology, Vellore 632014, India.
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5
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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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6
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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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7
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Worm DJ, Els‐Heindl S, Beck‐Sickinger AG. Targeting of peptide‐binding receptors on cancer cells with peptide‐drug conjugates. Pept Sci (Hoboken) 2020. [DOI: 10.1002/pep2.24171] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Dennis J. Worm
- Faculty of Life Sciences, Institute of BiochemistryLeipzig University Leipzig Germany
| | - Sylvia Els‐Heindl
- Faculty of Life Sciences, Institute of BiochemistryLeipzig University Leipzig Germany
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8
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Acylated Ghrelin Renders Chemosensitive Ovarian Cancer Cells Resistant to Cisplatin Chemotherapy via Activation of the PI3K/Akt/mTOR Survival Pathway. Anal Cell Pathol (Amst) 2019; 2019:9627810. [PMID: 31360627 PMCID: PMC6644235 DOI: 10.1155/2019/9627810] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 04/27/2019] [Accepted: 04/30/2019] [Indexed: 12/17/2022] Open
Abstract
This study investigated the effect of acylated synthetic ghrelin (AG) on the survival and proliferation of human chemosensitive ovarian cancer cells (A2780) and explored some mechanisms of action with a focus on the p53 apoptotic pathway and PI3K/Akt and NF-κB survival pathways. Human A2780 ovarian cancer cells were cultured with or without AG treatment in the presence or absence of cisplatin. In some cases, cisplatin+AG-treated cells were pre-incubated either with [D-Lys3]-GHRP-6, a ghrelin receptor antagonist, or with LY294002, a PI3K inhibitor. mRNA of ghrelin receptors(GHS-R1a and GHS-R1b), as well as, protein levels of GHS-R1a, were expressed abundantly in A2780 cells. AG treatment did not affect the mRNA and protein levels of GHS-R1a and GHS-R1b in both control and Cis-treated cells. However, while AG treatment had no effect on control cell viability, it significantly increased cell viability and proliferation and inhibited cell death in Cis-treated cells. In both control and Cis-treated cells, AG treatment significantly increased PI3K/Akt/mTOR signaling and enhanced the nuclear accumulation of NF-κB. Concomitantly, in both control and Cis-treated cells, AG significantly lowered the protein levels of p53, p-p53 (Ser16), PUMA, cytochrome C, and cleaved caspase-3. Interestingly, pre-incubating the cells with either [D-Lys3]-GHRP-6 or LY294002 completely abolished the above-mentioned effect of AG in both control and Cis-treated cells. In conclusion, the findings of this study show that AG promotes cell survival of the OC cells and renders them resistat to Cis therapy, an effect that is mediated by the activation of PI3K/Akt/mTOR and activation of NF-κB, and requires GHS-R1a.
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9
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Less Exploited GPCRs in Precision Medicine: Targets for Molecular Imaging and Theranostics. Molecules 2018; 24:molecules24010049. [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] [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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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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Pham PH, Doan SH, Vuong NTH, Nguyen VHH, Ha PTM, Phan NTS. Copper-catalyzed domino sequences: a new route to pyrido-fused quinazolinones from 2′-haloacetophenones and 2-aminopyridines. RSC Adv 2018; 8:20314-20318. [PMID: 35541660 PMCID: PMC9080829 DOI: 10.1039/c8ra03744b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 05/25/2018] [Indexed: 01/05/2023] Open
Abstract
A new pathway to access pyrido-fused quinazolinones via a Cu(OAc)2-catalyzed domino sequential transformation between 2′-haloacetophenones and 2-aminopyridines was demonstrated. The solvent and base exhibited a remarkable effect on the transformation, in which the combination of DMSO and NaOAc emerged as the best system. Cu(OAc)2·H2O was more active towards the reaction than numerous other catalysts. This methodology is new and would be complementary to previous protocols for the synthesis of pyrido-fused quinazolinones. A new pathway to access pyrido-fused quinazolinones via a Cu(OAc)2-catalyzed domino sequential transformation between 2′-haloacetophenones and 2-aminopyridines was demonstrated.![]()
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Affiliation(s)
- Phuc H. Pham
- Faculty of Chemical Engineering
- HCMC University of Technology
- VNU-HCM
- Ho Chi Minh City
- Vietnam
| | - Son H. Doan
- Faculty of Chemical Engineering
- HCMC University of Technology
- VNU-HCM
- Ho Chi Minh City
- Vietnam
| | - Ngan T. H. Vuong
- Faculty of Chemical Engineering
- HCMC University of Technology
- VNU-HCM
- Ho Chi Minh City
- Vietnam
| | - Vu H. H. Nguyen
- Faculty of Chemical Engineering
- HCMC University of Technology
- VNU-HCM
- Ho Chi Minh City
- Vietnam
| | - Phuong T. M. Ha
- Faculty of Chemical Engineering
- HCMC University of Technology
- VNU-HCM
- Ho Chi Minh City
- Vietnam
| | - Nam T. S. Phan
- Faculty of Chemical Engineering
- HCMC University of Technology
- VNU-HCM
- Ho Chi Minh City
- Vietnam
| |
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