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Thale I, Maskri S, Grey L, Todesca LM, Budde T, Maisuls I, Strassert CA, Koch O, Schwab A, Wünsch B. Imaging of K Ca 3.1 Channels in Tumor Cells with PET and Small-Molecule Fluorescent Probes. ChemMedChem 2023; 18:e202200551. [PMID: 36315933 PMCID: PMC10098740 DOI: 10.1002/cmdc.202200551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/31/2022] [Indexed: 01/20/2023]
Abstract
The Ca2+ activated K+ channel KCa 3.1 is overexpressed in several human tumor cell lines, e. g. clear cell renal carcinoma, prostate cancer, non-small cell lung cancer. Highly aggressive cancer cells use this ion channel for key processes of the metastatic cascade such as migration, extravasation and invasion. Therefore, small molecules, which are able to image this KCa 3.1 channel in vitro and in vivo represent valuable diagnostic and prognostic tool compounds. The [18 F]fluoroethyltriazolyl substituted senicapoc was used as positron emission tomography (PET) tracer and showed promising properties for imaging of KCa 3.1 channels in lung adenocarcinoma cells in mice. The novel senicapoc BODIPY conjugates with two F-atoms (9 a) and with a F-atom and a methoxy moiety (9 b) at the B-atom led to the characteristic punctate staining pattern resulting from labeling of single KCa 3.1 channels in A549-3R cells. This punctate pattern was completely removed by preincubation with an excess of senicapoc confirming the high specificity of KCa 3.1 labeling. Due to the methoxy moiety at the B-atom and the additional oxyethylene unit in the spacer, 9 b exhibits higher polarity, which improves solubility and handling without reduction of fluorescence quantum yield. Docking studies using a cryo-electron microscopy (EM) structure of the KCa 3.1 channel confirmed the interaction of 9 a and 9 b with a binding pocket in the channel pore.
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Affiliation(s)
- Insa Thale
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstraße 48, 48149, Münster, Germany
| | - Sarah Maskri
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstraße 48, 48149, Münster, Germany
| | - Lucie Grey
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstraße 48, 48149, Münster, Germany
| | - Luca Matteo Todesca
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Universitätsklinikum Münster, Institute of Physiology II, Robert-Koch-Straße 27b, 48149, Münster, Germany
| | - Thomas Budde
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Universitätsklinikum Münster, Institute of Physiology I, Robert-Koch-Straße 27a, 48149, Münster, Germany
| | - Ivan Maisuls
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie CiMIC, SoN, Corrensstraße 28, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, CeNTech, Heisenbergstraße 11, 48149, Münster, Germany
| | - Cristian A Strassert
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie CiMIC, SoN, Corrensstraße 28, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, CeNTech, Heisenbergstraße 11, 48149, Münster, Germany
| | - Oliver Koch
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstraße 48, 48149, Münster, Germany
| | - Albrecht Schwab
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Universitätsklinikum Münster, Institute of Physiology II, Robert-Koch-Straße 27b, 48149, Münster, Germany
| | - Bernhard Wünsch
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Corrensstraße 48, 48149, Münster, Germany.,Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstraße 48, 48149, Münster, Germany
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Konken CP, Heßling K, Thale I, Schelhaas S, Dabel J, Maskri S, Bulk E, Budde T, Koch O, Schwab A, Schäfers M, Wünsch B. Imaging of the calcium activated potassium channel 3.1 (K Ca 3.1) in vivo using a senicapoc-derived positron emission tomography tracer. Arch Pharm (Weinheim) 2022; 355:e2200388. [PMID: 36161669 DOI: 10.1002/ardp.202200388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 11/10/2022]
Abstract
The calcium-activated potassium channel 3.1 (KCa 3.1) is overexpressed in many tumor entities and has predictive power concerning disease progression and outcome. Imaging of the KCa 3.1 channel in vivo using a radiotracer for positron emission tomography (PET) could therefore establish a potentially powerful diagnostic tool. Senicapoc shows high affinity and excellent selectivity toward the KCa 3.1 channel. We have successfully pursued the synthesis of the 18 F-labeled derivative [18 F]3 of senicapoc using the prosthetic group approach with 1-azido-2-[18 F]fluoroethane ([18 F]6) in a "click" reaction. The biological activity of the new PET tracer was evaluated in vitro and in vivo. Inhibition of the KCa 3.1 channel by 3 was demonstrated by patch clamp experiments and the binding pose was analyzed by docking studies. In mouse and human serum, [18 F]3 was stable for at least one half-life of [18 F]fluorine. Biodistribution experiments in wild-type mice were promising, showing rapid and predominantly renal excretion. An in vivo study using A549-based tumor-bearing mice was performed. The tumor signal could be delineated and image analysis showed a tumor-to-muscle ratio of 1.47 ± 0.24. The approach using 1-azido-2-[18 F]fluoroethane seems to be a good general strategy to achieve triarylacetamide-based fluorinated PET tracers for imaging of the KCa 3.1 channel in vivo.
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Affiliation(s)
- Christian P Konken
- Department of Nuclear Medicine, University Hospital Münster, Münster, Germany
| | - Kathrin Heßling
- Institute of Pharmaceutical and Medicinal Chemistry, Westphalian Wilhelms-University Münster, Münster, Germany
| | - Insa Thale
- Institute of Pharmaceutical and Medicinal Chemistry, Westphalian Wilhelms-University Münster, Münster, Germany.,GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Sonja Schelhaas
- European Institute for Molecular Imaging (EIMI), Westphalian Wilhelms-University Münster, Münster, Germany.,Cells-in-Motion Interfaculty Center, Westphalian Wilhelms-University Münster, Münster, Germany
| | - Jennifer Dabel
- European Institute for Molecular Imaging (EIMI), Westphalian Wilhelms-University Münster, Münster, Germany
| | - Sarah Maskri
- Institute of Pharmaceutical and Medicinal Chemistry, Westphalian Wilhelms-University Münster, Münster, Germany.,GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Etmar Bulk
- Institute for Physiology II, University Hospital Münster, Münster, Germany
| | - Thomas Budde
- GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany.,Institute for Physiology I, University Hospital Münster, Münster, Germany
| | - Oliver Koch
- Institute of Pharmaceutical and Medicinal Chemistry, Westphalian Wilhelms-University Münster, Münster, Germany.,GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Albrecht Schwab
- GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany.,Institute for Physiology II, University Hospital Münster, Münster, Germany
| | - Michael Schäfers
- Department of Nuclear Medicine, University Hospital Münster, Münster, Germany.,European Institute for Molecular Imaging (EIMI), Westphalian Wilhelms-University Münster, Münster, Germany.,Cells-in-Motion Interfaculty Center, Westphalian Wilhelms-University Münster, Münster, Germany
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, Westphalian Wilhelms-University Münster, Münster, Germany.,GRK 2515, Chemical Biology of Ion Channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany.,Cells-in-Motion Interfaculty Center, Westphalian Wilhelms-University Münster, Münster, Germany
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