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Patronas EM, Balber T, Miller A, Geist BK, Michligk A, Vraka C, Krisch M, Rohr-Udilova N, Haschemi A, Viernstein H, Hacker M, Mitterhauser M. A fingerprint of 2-[ 18F]FDG radiometabolites - How tissue-specific metabolism beyond 2-[ 18F]FDG-6-P could affect tracer accumulation. iScience 2023; 26:108137. [PMID: 37867937 PMCID: PMC10585399 DOI: 10.1016/j.isci.2023.108137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/01/2023] [Accepted: 10/02/2023] [Indexed: 10/24/2023] Open
Abstract
Studies indicate that the radiotracer 2-[18F]fluoro-2-deoxy-D-glucose (2-[18F]FDG) can be metabolized beyond 2-[18F]FDG-6-phosphate (2-[18F]FDG-6-P), but its metabolism is incompletely understood. Most importantly, it remains unclear whether downstream metabolism affects tracer accumulation in vivo. Here we present a fingerprint of 2-[18F]FDG radiometabolites over time in cancer cells, corresponding tumor xenografts and murine organs. Strikingly, radiometabolites representing glycogen metabolism or the oxPPP correlated inversely with tracer accumulation across all examined tissues. Recent studies suggest that not only hexokinase, but also hexose-6-phosphate dehydrogenase (H6PD), an enzyme of the oxidative pentose phosphate pathway (oxPPP), determines 2-[18F]FDG accumulation. However, little is known about the corresponding enzyme glucose-6-phosphate dehydrogenase (G6PD). Our mechanistic in vitro experiments on the role of the oxPPP propose that 2-[18F]FDG can be metabolized via both G6PD and H6PD, but data from separate enzyme knockdown suggest diverging roles in downstream tracer metabolism. Overall, we propose that tissue-specific metabolism beyond 2-[18F]FDG-6-P could matter for imaging.
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Affiliation(s)
- Eva-Maria Patronas
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
- Division of Pharmaceutical Technology and Biopharmaceutics, Department of Pharmaceutical Sciences, University of Vienna, Vienna 1090, Austria
| | - Theresa Balber
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
- Ludwig Boltzmann Institute Applied Diagnostics, Vienna 1090, Austria
| | - Anne Miller
- Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna 1090, Austria
| | - Barbara Katharina Geist
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
| | - Antje Michligk
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
| | - Chrysoula Vraka
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
| | - Maximilian Krisch
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
| | - Nataliya Rohr-Udilova
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna 1090, Austria
| | - Arvand Haschemi
- Department of Laboratory Medicine, Medical University of Vienna, Vienna 1090, Austria
| | - Helmut Viernstein
- Division of Pharmaceutical Technology and Biopharmaceutics, Department of Pharmaceutical Sciences, University of Vienna, Vienna 1090, Austria
| | - Marcus Hacker
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
| | - Markus Mitterhauser
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna 1090, Austria
- Ludwig Boltzmann Institute Applied Diagnostics, Vienna 1090, Austria
- University of Vienna, Faculty of Chemistry, Institute of Inorganic Chemistry, Vienna 1090, Austria
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Giraudo A, Pallavicini M, Bolchi C. Small molecule ligands for α9* and α7 nicotinic receptors: a survey and an update, respectively. Pharmacol Res 2023; 193:106801. [PMID: 37236412 DOI: 10.1016/j.phrs.2023.106801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/16/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023]
Abstract
The α9- and α7-containing nicotinic acetylcholine receptors (nAChRs) mediate numerous physiological and pathological processes by complex mechanisms that are currently the subject of intensive study and debate. In this regard, selective ligands serve as invaluable investigative tools and, in many cases, potential therapeutics for the treatment of various CNS disfunctions and diseases, neuropathic pain, inflammation, and cancer. However, the present scenario differs significantly between the two aforementioned nicotinic subtypes. Over the past few decades, a large number of selective α7-nAChR ligands, including full, partial and silent agonists, antagonists, and allosteric modulators, have been described and reviewed. Conversely, reports on selective α9-containing nAChR ligands are relatively scarce, also due to a more recent characterization of this receptor subtype, and hardly any focusing on small molecules. In this review, we focus on the latter, providing a comprehensive overview, while providing only an update over the last five years for α7-nAChR ligands.
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Affiliation(s)
- Alessandro Giraudo
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, I-20133 Milano, Italy
| | - Marco Pallavicini
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, I-20133 Milano, Italy
| | - Cristiano Bolchi
- Department of Pharmaceutical Sciences, University of Milan, via Mangiagalli 25, I-20133 Milano, Italy.
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Andralojc K, Srinivas M, Brom M, Joosten L, de Vries IJM, Eizirik DL, Boerman OC, Meda P, Gotthardt M. Obstacles on the way to the clinical visualisation of beta cells: looking for the Aeneas of molecular imaging to navigate between Scylla and Charybdis. Diabetologia 2012; 55:1247-57. [PMID: 22358499 PMCID: PMC3328679 DOI: 10.1007/s00125-012-2491-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 01/09/2012] [Indexed: 12/25/2022]
Abstract
For more than a decade, researchers have been trying to develop non-invasive imaging techniques for the in vivo measurement of viable pancreatic beta cells. However, in spite of intense research efforts, only one tracer for positron emission tomography (PET) imaging is currently under clinical evaluation. To many diabetologists it may remain unclear why the imaging world struggles to develop an effective method for non-invasive beta cell imaging (BCI), which could be useful for both research and clinical purposes. Here, we provide a concise overview of the obstacles and challenges encountered on the way to such BCI, in both native and transplanted islets. We discuss the major difficulties posed by the anatomical and cell biological features of pancreatic islets, as well as the chemical and physical limits of the main imaging modalities, with special focus on PET, SPECT and MRI. We conclude by indicating new avenues for future research in the field, based on several remarkable recent results.
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Affiliation(s)
- K. Andralojc
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - M. Srinivas
- Department of Tumour Immunology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - M. Brom
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - L. Joosten
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - I. J. M. de Vries
- Department of Tumour Immunology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - D. L. Eizirik
- Laboratory of Experimental Medicine, Université Libre de Bruxelles, Brussels, Belgium
| | - O. C. Boerman
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - P. Meda
- Deparment of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - M. Gotthardt
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
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