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Wodtke R, Laube M, Hauser S, Meister S, Ludwig FA, Fischer S, Kopka K, Pietzsch J, Löser R. Preclinical evaluation of an 18F-labeled N ε-acryloyllysine piperazide for covalent targeting of transglutaminase 2. EJNMMI Radiopharm Chem 2024; 9:1. [PMID: 38165538 PMCID: PMC10761660 DOI: 10.1186/s41181-023-00231-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024] Open
Abstract
BACKGROUND Transglutaminase 2 (TGase 2) is a multifunctional protein and has a prominent role in various (patho)physiological processes. In particular, its transamidase activity, which is rather latent under physiological conditions, gains importance in malignant cells. Thus, there is a great need of theranostic probes for targeting tumor-associated TGase 2, and targeted covalent inhibitors appear to be particularly attractive as vector molecules. Such an inhibitor, equipped with a radionuclide suitable for noninvasive imaging, would be supportive for answering the general question on the possibility for functional characterization of tumor-associated TGase 2. For this purpose, the recently developed 18F-labeled Nε-acryloyllysine piperazide [18F]7b, which is a potent and selective irreversible inhibitor of TGase 2, was subject to a detailed radiopharmacological characterization herein. RESULTS An alternative radiosynthesis of [18F]7b is presented, which demands less than 300 µg of the respective trimethylammonio precursor per synthesis and provides [18F]7b in good radiochemical yields (17 ± 7%) and high (radio)chemical purities (≥ 99%). Ex vivo biodistribution studies in healthy mice at 5 and 60 min p.i. revealed no permanent enrichment of 18F-activity in tissues with the exception of the bone tissue. In vivo pretreatment with ketoconazole and in vitro murine liver microsome studies complemented by mass spectrometric analysis demonstrated that bone uptake originates from metabolically released [18F]fluoride. Further metabolic transformations of [18F]7b include mono-hydroxylation and glucuronidation. Based on blood sampling data and liver microsome experiments, pharmacokinetic parameters such as plasma and intrinsic clearance were derived, which substantiated the apparently rapid distribution of [18F]7b in and elimination from the organisms. A TGase 2-mediated uptake of [18F]7b in different tumor cell lines could not be proven. Moreover, evaluation of [18F]7b in melanoma tumor xenograft models based on A375-hS100A4 (TGase 2 +) and MeWo (TGase 2 -) cells by ex vivo biodistribution and PET imaging studies were not indicative for a specific targeting. CONCLUSION [18F]7b is a valuable radiometric tool to study TGase 2 in vitro under various conditions. However, its suitability for targeting tumor-associated TGase 2 is strongly limited due its unfavorable pharmacokinetic properties as demonstrated in rodents. Consequently, from a radiochemical perspective [18F]7b requires appropriate structural modifications to overcome these limitations.
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Affiliation(s)
- Robert Wodtke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany.
| | - Markus Laube
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Sandra Hauser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Sebastian Meister
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069, Dresden, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069, Dresden, Germany
| | - Reik Löser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328, Dresden, Germany.
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069, Dresden, Germany.
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Gates EWJ, Calvert ND, Cundy NJ, Brugnoli F, Navals P, Kirby A, Bianchi N, Adhikary G, Shuhendler AJ, Eckert RL, Keillor JW. Cell-Impermeable Inhibitors Confirm That Intracellular Human Transglutaminase 2 Is Responsible for the Transglutaminase-Associated Cancer Phenotype. Int J Mol Sci 2023; 24:12546. [PMID: 37628729 PMCID: PMC10454375 DOI: 10.3390/ijms241612546] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/24/2023] [Accepted: 07/31/2023] [Indexed: 08/27/2023] Open
Abstract
Transglutaminase 2 (TG2) is a multifunctional enzyme primarily responsible for crosslinking proteins. Ubiquitously expressed in humans, TG2 can act either as a transamidase by crosslinking two substrates through formation of an Nε(ɣ-glutaminyl)lysine bond or as an intracellular G-protein. These discrete roles are tightly regulated by both allosteric and environmental stimuli and are associated with dramatic changes in the conformation of the enzyme. The pleiotropic nature of TG2 and multi-faceted activities have resulted in TG2 being implicated in numerous disease pathologies including celiac disease, fibrosis, and cancer. Targeted TG2 therapies have not been selective for subcellular localization, such that currently no tools exist to selectively target extracellular over intracellular TG2. Herein, we have designed novel TG2-selective inhibitors that are not only highly potent and irreversible, but also cell impermeable, targeting only extracellular TG2. We have also further derivatized the scaffold to develop probes that are intrinsically fluorescent or bear an alkyne handle, which target both intra- and extracellular TG2, in order to facilitate cellular labelling and pull-down assays. The fluorescent probes were internalized and imaged in cellulo, and provide the first implicit experimental evidence that by comparison with their cell-impermeable analogues, it is specifically intracellular TG2, and presumably its G-protein activity, that contributes to transglutaminase-associated cancer progression.
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Affiliation(s)
- Eric W. J. Gates
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Nicholas D. Calvert
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Nicholas J. Cundy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Federica Brugnoli
- Department of Translational Medicine, University of Ferrara, 44021 Ferrara, Italy; (F.B.); (N.B.)
| | - Pauline Navals
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Alexia Kirby
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Nicoletta Bianchi
- Department of Translational Medicine, University of Ferrara, 44021 Ferrara, Italy; (F.B.); (N.B.)
| | - Gautam Adhikary
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (G.A.); (R.L.E.)
| | - Adam J. Shuhendler
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
| | - Richard L. Eckert
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; (G.A.); (R.L.E.)
| | - Jeffrey W. Keillor
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (E.W.J.G.); (N.D.C.); (N.J.C.); (P.N.); (A.K.); (A.J.S.)
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