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Cong GZ, Ghosh KK, Mishra S, Gulyás M, Kovács T, Máthé D, Padmanabhan P, Gulyás B. Targeted pancreatic beta cell imaging for early diagnosis. Eur J Cell Biol 2020; 99:151110. [PMID: 33070042 DOI: 10.1016/j.ejcb.2020.151110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 06/29/2020] [Accepted: 07/22/2020] [Indexed: 12/12/2022] Open
Abstract
Pancreatic beta cells are important in blood glucose level regulation. As type 1 and 2 diabetes are getting prevalent worldwide, we need to explore new methods for early detection of beta cell-related afflictions. Using bioimaging techniques to measure beta cell mass is crucial because a decrease in beta cell density is seen in diseases such as diabetes and thus can be a new way of diagnosis for such diseases. We also need to appraise beta cell purity in transplanted islets for type 1 diabetes patients. Sufficient amount of functional beta cells must also be determined before being transplanted to the patients. In this review, indirect imaging of beta cells will be discussed. This includes membrane protein on pancreatic beta cells whereby specific probes are designed for different imaging modalities mainly magnetic resonance imaging, positron emission tomography and fluorescence imaging. Direct imaging of insulin is also explored though probes synthesized for such function are relatively fewer. The path for successful pancreatic beta cell imaging is fraught with challenges like non-specific binding, lack of beta cell-restricted targets, the requirement of probes to cross multiple lipid layers to bind to intracellular insulin. Hence, there is an urgent need to develop new imaging techniques and innovative probing constructs in the entire imaging chain of bioengineering to provide early detection of beta cell-related pathology.
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Affiliation(s)
- Goh Zheng Cong
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Krishna Kanta Ghosh
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Sachin Mishra
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore
| | - Miklós Gulyás
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Dag Hammarskölds väg 20, Uppsala Se-751 85, Sweden
| | - Tibor Kovács
- Institute of Radiochemistry and Radioecology, University of Pannonia, Egyetem u. 10, H-8200 Veszprém, Hungary
| | - Domokos Máthé
- Department of Biophysics and Radiation Biology, Semmelweis University Faculty of Medicine, Tűzoltó u. 37-47, Budapest H-1094, Hungary
| | - Parasuraman Padmanabhan
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore.
| | - Balázs Gulyás
- Lee Kong Chian School of Medicine, Nanyang Technological University, 59 Nanyang Drive, Singapore 636921, Singapore.
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Wei W, Ehlerding EB, Lan X, Luo QY, Cai W. Molecular imaging of β-cells: diabetes and beyond. Adv Drug Deliv Rev 2019; 139:16-31. [PMID: 31378283 DOI: 10.1016/j.addr.2018.06.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/27/2018] [Accepted: 06/26/2018] [Indexed: 02/09/2023]
Abstract
Since diabetes is becoming a global epidemic, there is a great need to develop early β-cell specific diagnostic techniques for this disorder. There are two types of diabetes (i.e., type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM)). In T1DM, the destruction of pancreatic β-cells leads to reduced insulin production or even absolute insulin deficiency, which consequently results in hyperglycemia. Actually, a central issue in the pathophysiology of all types of diabetes is the relative reduction of β-cell mass (BCM) and/or impairment of the function of individual β-cells. In the past two decades, scientists have been trying to develop imaging techniques for noninvasive measurement of the viability and mass of pancreatic β-cells. Despite intense scientific efforts, only two tracers for positron emission tomography (PET) and one contrast agent for magnetic resonance (MR) imaging are currently under clinical evaluation. β-cell specific imaging probes may also allow us to precisely and specifically visualize transplanted β-cells and to improve transplantation outcomes, as transplantation of pancreatic islets has shown promise in treating T1DM. In addition, some of these probes can be applied to the preoperative detection of hidden insulinomas as well. In the present review, we primarily summarize potential tracers under development for imaging β-cells with a focus on tracers for PET, SPECT, MRI, and optical imaging. We will discuss the advantages and limitations of the various imaging probes and extend an outlook on future developments in the field.
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99mTc-labeled glimepiride as a tracer for targeting pancreatic β-cells mass: preparation and preclinical evaluation. J Radioanal Nucl Chem 2017. [DOI: 10.1007/s10967-017-5615-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Kniess T, Laube M, Brust P, Steinbach J. 2-[18F]Fluoroethyl tosylate – a versatile tool for building18F-based radiotracers for positron emission tomography. MEDCHEMCOMM 2015. [DOI: 10.1039/c5md00303b] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The review highlights the role of 2-[18F]fluoroethyltosylate ([18F]FETs) in PET radiotracer design since it is a preferred labeling reagent according to its high reactivity to phenolic, amine, thiophenolic and carboxylic functions.
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Affiliation(s)
- Torsten Kniess
- Helmholtz-Zentrum Dresden-Rossendorf
- Institute of Radiopharmaceutical Cancer Research
- Dresden
- Germany
| | - Markus Laube
- Helmholtz-Zentrum Dresden-Rossendorf
- Institute of Radiopharmaceutical Cancer Research
- Dresden
- Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf
- Institute of Radiopharmaceutical Cancer Research
- Dresden
- Germany
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf
- Institute of Radiopharmaceutical Cancer Research
- Dresden
- Germany
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Synthesis and evaluation of 18F-labeled mitiglinide derivatives as positron emission tomography tracers for β-cell imaging. Bioorg Med Chem 2014; 22:3270-8. [DOI: 10.1016/j.bmc.2014.04.059] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 04/26/2014] [Accepted: 04/28/2014] [Indexed: 12/30/2022]
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Furazan and furoxan sulfonamides are strong α-carbonic anhydrase inhibitors and potential antiglaucoma agents. Bioorg Med Chem 2014; 22:3913-21. [PMID: 25022971 DOI: 10.1016/j.bmc.2014.06.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 06/05/2014] [Accepted: 06/06/2014] [Indexed: 12/15/2022]
Abstract
A series of furazan and furoxan sulfonamides were prepared and studied for their ability to inhibit human carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I, hCA II, hCA IX, and hCA XII. The simple methyl substituted products 3-5 were potent inhibitors. Differing structural modifications of these leads had differing effects on potency and selectivity. In particular, products in which the sulfonamide group is separated from the hetero ring by a phenylene bridge retained high potency only on the hCA XII isoform. The sulfonamides 3-5 exerted intraocular pressure (IOP) lowering effects in vivo in hypertensive rabbits more efficiently than dorzolamide. Some other products (39-42), although less effective in vitro hCA II/XII inhibitors, also effectively lowered IOP in two different animal models of glaucoma.
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Wu Z, Kandeel F. Radionuclide probes for molecular imaging of pancreatic beta-cells. Adv Drug Deliv Rev 2010; 62:1125-38. [PMID: 20854861 DOI: 10.1016/j.addr.2010.09.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 09/09/2010] [Accepted: 09/13/2010] [Indexed: 12/16/2022]
Abstract
Islet transplantation is a promising treatment option for patients with type 1 diabetes (T1D); however, the fate of the graft over time remains difficult to follow, due to the lack of available tools capable of monitoring graft rejection and inflammation prior to islet graft loss. Due to the challenges imposed by the location of the pancreas and the sparsely dispersed beta-cell population within the pancreas, currently, the clinical verification of beta-cell abnormalities can only be obtained indirectly via metabolic studies, which typically is not possible until after a significant deterioration in islet function has already occurred. The development of non-invasive imaging methods for the assessment of the pancreatic beta-cells, however, offers the potential for the early detection of beta-cell dysfunction prior to the clinical onset of T1D and type 2 diabetes (T2D). Ideal islet imaging agents would have an acceptable residence time in the human body, be capable of providing high-resolution images with minimal uptake in surrounding tissues (e.g., the liver), would not be toxic to islets, and would not require pre-treatment of islets prior to transplantation. A variety of currently available imaging techniques, including magnetic resonance imaging (MRI), bioluminescence imaging (BLI), and nuclear imaging have been tested for the study of beta-cell diseases. In this article, we summarize the recent advances made in nuclear imaging techniques for non-invasive imaging of pancreatic beta-cells. The use of radioactive probes for islet imaging is also discussed.
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Ueberberg S, Schneider S. Phage library-screening: A powerful approach for generation of targeting-agents specific for normal pancreatic islet-cells and islet-cell carcinoma in vivo. ACTA ACUST UNITED AC 2010; 160:1-8. [DOI: 10.1016/j.regpep.2009.11.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 11/14/2009] [Accepted: 11/26/2009] [Indexed: 01/09/2023]
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Ueberberg S, Meier JJ, Waengler C, Schechinger W, Dietrich JW, Tannapfel A, Schmitz I, Schirrmacher R, Köller M, Klein HH, Schneider S. Generation of novel single-chain antibodies by phage-display technology to direct imaging agents highly selective to pancreatic beta- or alpha-cells in vivo. Diabetes 2009; 58:2324-34. [PMID: 19592622 PMCID: PMC2750237 DOI: 10.2337/db09-0658] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 07/03/2009] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Noninvasive determination of pancreatic beta-cell mass in vivo has been hampered by the lack of suitable beta-cell-specific imaging agents. This report outlines an approach for the development of novel ligands homing selectively to islet cells in vivo. RESEARCH DESIGN AND METHODS To generate agents specifically binding to pancreatic islets, a phage library was screened for single-chain antibodies (SCAs) on rat islets using two different approaches. 1) The library was injected into rats in vivo, and islets were isolated after a circulation time of 5 min. 2) Pancreatic islets were directly isolated, and the library was panned in the islets in vitro. Subsequently, the identified SCAs were extensively characterized in vitro and in vivo. RESULTS We report the generation of SCAs that bind highly selective to either beta- or alpha-cells. These SCAs are internalized by target cells, disappear rapidly from the vasculature, and exert no toxicity in vivo. Specific binding to beta- or alpha-cells was detected in cell lines in vitro, in rats in vivo, and in human tissue in situ. Electron microscopy demonstrated binding of SCAs to the endoplasmatic reticulum and the secretory granules. Finally, in a biodistribution study the labeling intensity derived from [(125)I]-labeled SCAs after intravenous administration in rats strongly predicted the beta-cell mass and was inversely related to the glucose excursions during an intraperitoneal glucose tolerance test. CONCLUSIONS Our data provide strong evidence that the presented SCAs are highly specific for pancreatic beta-cells and enable imaging and quantification in vivo.
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Affiliation(s)
- Sandra Ueberberg
- Department of Internal Medicine I, Division of Endocrinology and Metabolism, Berufsgenossenschaftliches University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
| | - Juris J. Meier
- Department of Internal Medicine I, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Carmen Waengler
- Department of Nuclear Medicine, Hospital of the Ludwig-Maximilians-University, Munich, Germany
- Department of Neurology & Neurosurgery, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada
| | - Wolfgang Schechinger
- Department of Internal Medicine I, Division of Endocrinology and Metabolism, Berufsgenossenschaftliches University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
| | - Johannes W. Dietrich
- Department of Internal Medicine I, Division of Endocrinology and Metabolism, Berufsgenossenschaftliches University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
| | - Andrea Tannapfel
- Institute for Pathology, Ruhr-University Bochum, Bochum, Germany
| | - Inge Schmitz
- Institute for Pathology, Ruhr-University Bochum, Bochum, Germany
| | - Ralf Schirrmacher
- Department of Neurology & Neurosurgery, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada
| | - Manfred Köller
- Chirurgische Forschung, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil, Ruhr-Universität Bochum, Bochum, Germany
| | - Harald H. Klein
- Department of Internal Medicine I, Division of Endocrinology and Metabolism, Berufsgenossenschaftliches University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
| | - Stephan Schneider
- Department of Internal Medicine I, Division of Endocrinology and Metabolism, Berufsgenossenschaftliches University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany
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Abstract
Visualization and quantification of the native beta-cell mass in vivo in humans appear to be important in the study of the natural course of diabetes, and in ongoing trials aimed at preserving beta-cell mass in patients with diabetes. This cannot be done by biopsy sampling, and therefore there is a great need for development of a non-invasive method. This article discusses the principle theoretical requirements for reaching this goal. In addition, it provides an overview of tracer probes, which have been examined as potential beta-cell mass imaging agents in the past. Finally, some future perspectives are discussed.
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Affiliation(s)
- S Schneider
- Medical Department 1, Division of Endocrinology and Metabolism, University Hospital Bergmannsheil, Ruhr-University of Bochum, Germany.
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Prenant C, Gillies J, Bailey J, Chimon G, Smith N, Jayson GC, Zweit J. Synthesis of [18F]fluoroacetaldehyde. Application to [18F]fluoroethylation of benzylamine under reductive alkylation conditions. J Labelled Comp Radiopharm 2008. [DOI: 10.1002/jlcr.1514] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Olma S, Ermert J, Coenen HH. 4-[18F]fluorophenyl ureas via carbamate-4-nitrophenyl esters and 4-[18F]fluoroaniline. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.1121] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wängler B, Beck C, Shiue CY, Schneider S, Schwanstecher C, Schwanstecher M, Feilen PJ, Alavi A, Rösch F, Schirrmacher R. Synthesis and in vitro evaluation of (S)-2-([11C]methoxy)-4-[3-methyl-1-(2-piperidine-1-yl-phenyl)-butyl-carbamoyl]-benzoic acid ([11C]methoxy-repaglinide): a potential beta-cell imaging agent. Bioorg Med Chem Lett 2005; 14:5205-9. [PMID: 15380228 DOI: 10.1016/j.bmcl.2004.07.059] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 07/01/2004] [Accepted: 07/22/2004] [Indexed: 11/28/2022]
Abstract
The 11C-labeled sulfonylurea receptor 1 (SUR1) ligand (S)-2-([11C]methoxy)-4-[3-methyl-1-(2-piperidine-1-yl-phenyl)-butyl-carbamoyl]-benzoic acid ([11C]methoxy-repaglinide) was synthesized in an overall radiochemical yield of 35% after 55 min with a radiochemical purity higher than 99%. This compound is considered for the noninvasive investigation of the SUR1 receptor status of pancreatic beta-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. The specific activity was 40-70 GBq/micromol. In vitro testing of the nonradioactive methoxy-repaglinide was performed to characterize the affinity for binding to the human SUR1 isoform. Methoxy-repaglinide induced a complete monophasic inhibition curve with a Hill coefficient close to 1 (1.03) yielding a dissociation constant (KD) of 83 nM and an IC50 of 163 nM. Insulin secretion experiments on isolated rat islets were performed to prove biological activity, which was determined to be in the same range as that of original repaglinide.
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Affiliation(s)
- Björn Wängler
- Institute of Nuclear Chemistry, University of Mainz, Mainz, Germany
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Wängler B, Schneider S, Thews O, Schirrmacher E, Comagic S, Feilen P, Schwanstecher C, Schwanstecher M, Shiue CY, Alavi A, Höhnemann S, Piel M, Rösch F, Schirrmacher R. Synthesis and evaluation of (S)-2-(2-[18F]fluoroethoxy)-4-([3-methyl-1-(2-piperidin-1-yl-phenyl)-butyl-carbamoyl]-methyl)-benzoic acid ([18F]repaglinide): a promising radioligand for quantification of pancreatic beta-cell mass with positron emission tomography (PET). Nucl Med Biol 2004; 31:639-47. [PMID: 15219283 DOI: 10.1016/j.nucmedbio.2004.01.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2004] [Revised: 01/25/2004] [Accepted: 01/25/2004] [Indexed: 11/20/2022]
Abstract
18F-labeled non-sulfonylurea hypoglycemic agent (S)-2-(2-[(18)F]fluoroethoxy)-4-((3-methyl-1-(2-piperidin-1-yl-phenyl)-butylcarbamoyl)-methyl)-benzoic acid ([(18)F]repaglinide), a derivative of the sulfonylurea-receptor (SUR) ligand repaglinide, was synthesized as a potential tracer for the non-invasive investigation of the sulfonylurea 1 receptor status of pancreatic beta-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. [(18)F]Repaglinide could be obtained in an overall radiochemical yield (RCY) of 20% after 135 min with a radiochemical purity higher than 98% applying the secondary labeling precursor 2-[(18)F]fluoroethyltosylate. Specific activity was in the range of 50-60 GBq/micromol. Labeling was conducted by exchanging the ethoxy-moiety into a 2-[(18)F]fluoroethoxy group. To characterize the properties of fluorinated repaglinide, the affinity of the analogous non-radioactive (19)F-compound for binding to the human SUR1 isoform was assessed. [(19)F]Repaglinide induced a complete monophasic inhibition curve with a Hill coefficient close to 1 (1.03) yielding a dissociation constant (K(D)) of 134 nM. Biological activity was proven via insulin secretion experiments on isolated rat islets and was comparable to that of repaglinide. Finally, biodistribution of [(18)F]repaglinide was investigated in rats by measuring the concentration of the compound in different organs after i.v. injection. Pancreatic tissue displayed a stable accumulation of approximately 0.12% of the injected dose from 10 min to 30 min p.i. 50% of the radioactive tracer could be displaced by additional injection of unlabeled repaglinide, indicating that [(18)F]repaglinide might be suitable for in vivo investigation with PET.
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Affiliation(s)
- B Wängler
- Institute of Nuclear Chemistry, Johannes Gutenberg-University of Mainz, Fritz Strassmann-Weg 2, D-55128 Mainz, Germany
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Sweet IR, Cook DL, Lernmark A, Greenbaum CJ, Krohn KA. Non-invasive imaging of beta cell mass: a quantitative analysis. Diabetes Technol Ther 2004; 6:652-9. [PMID: 15628819 DOI: 10.1089/dia.2004.6.652] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Currently there are major efforts to develop strategies for the in vivo imaging of pancreatic beta cell mass as a clinical and investigational tool for detecting and tracking the loss of beta cells that underlies the progression of Type I diabetes. However, beta cells constitute only about 1% of pancreatic mass and are distributed throughout the pancreas within tiny islets of Langerhans that are each less than the spatial resolution of non-invasive imaging technologies. METHODS To estimate the requisite binding characteristics of a candidate beta cell imaging agent, calculations of the beta cell contribution to a positron emission tomography signal were made using simple equations. These were based on the relative population of beta cells and non-beta cells within the pancreas and surrounding tissue and an equation describing equilibrium ligand binding. RESULTS The calculations show that two criteria must be met: (1) The low-volume fraction of beta cells within the exocrine pancreas (about 1:100) requires that beta cells retain labeled imaging agents at least 1,000-fold more strongly than exocrine cells. (2) Agents that label cell surface receptors, even if beta cell-specific, must do so at a high enough level so that the imaging signal arising from unbound label retained in extracellular spaces must not overwhelm signals from labeled beta cells. CONCLUSIONS The limits developed here can serve as criteria for identifying candidate imaging agents for the in vivo imaging of beta cell mass, thereby avoiding expensive preclinical development using compounds that have no chance of success.
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Affiliation(s)
- Ian R Sweet
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
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Schmitz A, Shiue CY, Feng Q, Shiue GG, Deng S, Pourdehnad MT, Schirrmacher R, Vatamaniuk M, Doliba N, Matschinsky F, Wolf B, Rösch F, Naji A, Alavi AA. Synthesis and evaluation of fluorine-18 labeled glyburide analogs as beta-cell imaging agents. Nucl Med Biol 2004; 31:483-91. [PMID: 15093819 DOI: 10.1016/j.nucmedbio.2003.12.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2003] [Revised: 11/28/2003] [Accepted: 12/03/2003] [Indexed: 01/20/2023]
Abstract
Glyburide is a prescribed hypoglycemic drug for the treatment of type 2 diabetic patients. We have synthesized two of its analogs, namely N-[4-[beta-(2-(2'-fluoroethoxy)-5-chlorobenzenecarboxamido)ethyl]benzenesulfonyl]-N'-cyclohexylurea (2-fluoroethoxyglyburide, 8b) and N-[4-[beta-(2-(2'-fluoroethoxy)-5-iodobenzenecarboxamido)ethyl]benzenesulfonyl]-N'-cyclohexylurea (2-fluoroethoxy-5-deschloro-5-iodoglyburide, 8a), and their fluorine-18 labeled analogs as beta-cell imaging agents. Both F-18 labeled compound 8a and compound 8b were synthesized by alkylation of the corresponding multistep synthesized hydroxy precursor 4a and 4b with 2-[(18)F]fluoroethyl tosylate in DMSO at 120 degrees C for 20 minutes followed by HPLC purification in an overall radiochemical yield of 5-10% with a synthesis time of 100 minutes from EOB. The octanol/water partition coefficients of compounds 8a and 8b were 141.21 +/- 27.77 (n = 8) and 124.33 +/- 21.61 (n = 8), respectively. Insulin secretion experiments of compounds 8a and 8b on rat islets showed that both compounds have a similar stimulating effect on insulin secretion as that of glyburide. In vitro binding studies showed that approximately 2% of compounds 8a and 8b bound to beta TC3 and Min6 cells and that the binding was saturable. Preliminary biodistribution studies in mice showed that the uptake of both compounds 8a and 8b in liver and small intestine were high, whereas the uptake in other organs studied including pancreas were low. Additionally, the uptake of compound 8b in vivo was nonsaturable. These results tend to suggest that compounds 8a and 8b may not be the ideal beta-cell imaging agents.
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Affiliation(s)
- A Schmitz
- Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
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Sweet IR, Cook DL, Lernmark A, Greenbaum CJ, Wallen AR, Marcum ES, Stekhova SA, Krohn KA. Systematic screening of potential beta-cell imaging agents. Biochem Biophys Res Commun 2004; 314:976-83. [PMID: 14751228 DOI: 10.1016/j.bbrc.2003.12.182] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The beta-cell loss seen in diabetes mellitus could be monitored clinically by positron emission tomography (PET) if imaging agents were sufficiently specific for beta-cells to overcome the high ratio of non-beta-cell to beta-cell tissue in pancreas. In this report, we present a screening assay for identifying beta-cell-specific compounds that is based on the relative accumulation and retention by islet, INS-1, and exocrine (PANC-1) cells of candidate molecules. Molecules thought to have a high affinity for beta-cells were tested and included glibenclamide, tolbutamide, serotonin, L-DOPA, dopamine, nicotinamide, fluorodeoxyglucose, and fluorodithizone. Glibenclamide and fluorodithizone were the most specific, but the specificity ratios fell well below those needed to attain robust signal to background ratio as a PET imaging agent for quantifying beta-cell mass. In vivo tests of the biodistribution of glibenclamide and fluorodithizone in rats indicated that the compounds were not specifically associated with pancreas, bearing out the predictions of the in vitro screen.
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Affiliation(s)
- Ian R Sweet
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA.
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