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Park J, Wasim S, Jung JH, Kim MH, Lee BC, Alam MM, Lee SY. Synthesis, In Silico and In Vitro Characterization of Novel N, N-Substituted Pyrazolopyrimidine Acetamide Derivatives for the 18KDa Translocator Protein (TSPO). Pharmaceuticals (Basel) 2023; 16:ph16040576. [PMID: 37111333 PMCID: PMC10142799 DOI: 10.3390/ph16040576] [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: 02/08/2023] [Revised: 04/01/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
The translocator protein (TSPO) is an interesting biological target for molecular imaging and therapy because the overexpression of TSPO is associated with microglial activation caused by neuronal damage or neuroinflammation, and these activated microglia are involved in various central nervous system (CNS) diseases. The TSPO is a target for neuroprotective treatment, which is used with the aim of reducing microglial cell activation. The novel N,N-disubstituted pyrazolopyrimidine acetamides scaffold (GMA 7-17), which bears a fluorine atom and is directly linked to the phenyl moiety, was synthesized, and each of the novel ligands was characterized in vitro. All of the newly synthesized ligands displayed picomolar to nanomolar affinity for the TSPO. Particularly, an in vitro affinity study led to the discovery of 2-(5,7-diethyl-2-(4-fluorophenyl)pyrazolo [1,5-a]pyrimidin-3-yl)-N-ethyl-N-phenylacetamide GMA 15 (Ki = 60 pM), a novel TSPO ligand that exhibits a 61-fold enhancement in affinity compared to the reference standard DPA-714 (Ki = 3.66 nM). Molecular dynamic (MD) studies of the highest affinity binder, GMA 15, were carried out to check its time-dependent stability with the receptor compared to DPA-714 and PK11195. The hydrogen bond plot also indicated that GMA 15 formed higher hydrogen bonds compared to DPA-714 and PK11195. We anticipate that further optimization to enhance the potency in a cellular assay needs to be followed, but our strategy of identifying potential TSPO binding novel scaffolds may open up a new avenue to develop novel TSPO ligands suited for potential molecular imaging and a wide range of therapeutic applications.
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Affiliation(s)
- Jaekyung Park
- Gachon Advanced Institute for Health Science and Technology, Graduate School, Gachon University, Incheon 21999, Republic of Korea
| | - Sobia Wasim
- Department of Biochemistry, College of Medicine, Gachon University, Incheon 21999, Republic of Korea
| | - Jae Ho Jung
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea
| | - Mi-Hyun Kim
- Gachon Institute of Pharmaceutical Science and Department of Pharmacy, College of Pharmacy, Gachon University, Incheon 21936, Republic of Korea
| | - Byung Chul Lee
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Republic of Korea
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon 16229, Republic of Korea
| | | | - Sang-Yoon Lee
- Gachon Advanced Institute for Health Science and Technology, Graduate School, Gachon University, Incheon 21999, Republic of Korea
- Neuroscience Research Institute, Gachon University, Incheon 20565, Republic of Korea
- Department of Neuroscience, College of Medicine, Gachon University, Incheon 21936, Republic of Korea
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2
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Multi-Targeted Neutron Capture Therapy Combined with an 18 kDa Translocator Protein-Targeted Boron Compound Is an Effective Strategy in a Rat Brain Tumor Model. Cancers (Basel) 2023; 15:cancers15041034. [PMID: 36831378 PMCID: PMC9953932 DOI: 10.3390/cancers15041034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/30/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
BACKGROUND Boron neutron capture therapy (BNCT) has been adapted to high-grade gliomas (HG); however, some gliomas are refractory to BNCT using boronophenylalanine (BPA). In this study, the feasibility of BNCT targeting the 18 kDa translocator protein (TSPO) expressed in glioblastoma and surrounding environmental cells was investigated. METHODS Three rat glioma cell lines, an F98 rat glioma bearing brain tumor model, DPA-BSTPG which is a boron-10 compound targeting TSPO, BPA, and sodium borocaptate (BSH) were used. TSPO expression was evaluated in the F98 rat glioma model. Boron uptake was assessed in three rat glioma cell lines and in the F98 rat glioma model. In vitro and in vivo neutron irradiation experiments were performed. RESULTS DPA-BSTPG was efficiently taken up in vitro. The brain tumor has 16-fold higher TSPO expressions than its brain tissue. The compound biological effectiveness value of DPA-BSTPG was 8.43 to F98 rat glioma cells. The boron concentration in the tumor using DPA-BSTPG convection-enhanced delivery (CED) administration was approximately twice as high as using BPA intravenous administration. BNCT using DPA-BSTPG has significant efficacy over the untreated group. BNCT using a combination of BPA and DPA-BSTPG gained significantly longer survival times than using BPA alone. CONCLUSION DPA-BSTPG in combination with BPA may provide the multi-targeted neutron capture therapy against HG.
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3
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Laferriere-Holloway TS, Rios A, Lu Y, Okoro CC, van Dam RM. A rapid and systematic approach for the optimization of radio thin-layer chromatography resolution. J Chromatogr A 2023; 1687:463656. [PMID: 36463649 PMCID: PMC9894532 DOI: 10.1016/j.chroma.2022.463656] [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: 09/28/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022]
Abstract
Radiopharmaceutical analysis is limited by conventional methods. Radio-HPLC may be inaccurate for some compounds (e.g., 18F-radiopharmaceuticals) due to radionuclide sequester. Radio-TLC is simpler, faster, and detects all species but has limited resolution. Imaging-based readout of TLC plates (e.g., using Cerenkov luminescence imaging) can improve readout resolution, but the underlying chromatographic separation efficiency may be insufficient to resolve chemically similar species such as product and precursor-derived impurities. This study applies a systematic mobile phase optimization method, PRISMA, to improve radio-TLC resolution. The PRISMA method optimizes the mobile phase by selecting the correct solvent, optimizing solvent polarity, and optimizing composition. Without prior knowledge of impurities and by simply observing the separation resolution between a radiopharmaceutical and its nearest radioactive or non-radioactive impurities (observed via UV imaging) for different mobile phases, the PRISMA method enabled the development of high-resolution separation conditions for a wide range of 18F-radiopharmaceuticals ( [18F]PBR-06, [18F]FEPPA, [18F]Fallypride, [18F]FPEB, and [18F]FDOPA). Each optimization required a single batch of crude radiopharmaceutical and a few hours. Interestingly, the optimized TLC method provided greater accuracy (compared to other published TLC methods) in determining the product abundance of one radiopharmaceutical studied in more depth ( [18F]Fallypride) and was capable of resolving a comparable number of species as isocratic radio-HPLC. We used the PRISMA-optimized mobile phase for [18F]FPEB in combination with multi-lane radio-TLC techniques to evaluate reaction performance during high-throughput synthesis optimization of [18F]FPEB. The PRISMA methodology, in combination with high-resolution radio-TLC readout, enables a rapid and systematic approach to achieving high-resolution and accurate analysis of radiopharmaceuticals without the need for radio-HPLC.
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Affiliation(s)
- Travis S Laferriere-Holloway
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA.
| | - Alejandra Rios
- Physics and Biology in Medicine Interdepartmental Graduate Program, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA
| | - Yingqing Lu
- Physics and Biology in Medicine Interdepartmental Graduate Program, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA
| | - Chelsea C Okoro
- Institute for Society and Genetics, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA
| | - R Michael van Dam
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA; Physics and Biology in Medicine Interdepartmental Graduate Program, UCLA, Los Angeles, CA, USA; Crump Institute for Molecular Imaging, UCLA, Los Angeles, CA, USA.
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4
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18F-Radiolabeled Translocator Protein (TSPO) PET Tracers: Recent Development of TSPO Radioligands and Their Application to PET Study. Pharmaceutics 2022; 14:pharmaceutics14112545. [PMID: 36432736 PMCID: PMC9697781 DOI: 10.3390/pharmaceutics14112545] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
Translocator protein 18 kDa (TSPO) is a transmembrane protein in the mitochondrial membrane, which has been identified as a peripheral benzodiazepine receptor. TSPO is generally present at high concentrations in steroid-producing cells and plays an important role in steroid synthesis, apoptosis, and cell proliferation. In the central nervous system, TSPO expression is relatively modest under normal physiological circumstances. However, some pathological disorders can lead to changes in TSPO expression. Overexpression of TSPO is associated with several diseases, such as neurodegenerative diseases, neuroinflammation, brain injury, and cancers. TSPO has therefore become an effective biomarker of related diseases. Positron emission tomography (PET), a non-invasive molecular imaging technique used for the clinical diagnosis of numerous diseases, can detect diseases related to TSPO expression. Several radiolabeled TSPO ligands have been developed for PET. In this review, we describe recent advances in the development of TSPO ligands, and 18F-radiolabeled TSPO in particular, as PET tracers. This review covers pharmacokinetic studies, preclinical and clinical trials of 18F-labeled TSPO PET ligands, and the synthesis of TSPO ligands.
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5
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Singh P, Adhikari A, Singh D, Gond C, Tiwari AK. The 18-kDa Translocator Protein PET Tracers as a Diagnostic Marker for Neuroinflammation: Development and Current Standing. ACS OMEGA 2022; 7:14412-14429. [PMID: 35557664 PMCID: PMC9089361 DOI: 10.1021/acsomega.2c00588] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/05/2022] [Indexed: 05/13/2023]
Abstract
Translocator protein (TSPO, 18 kDa) is an evolutionary, well-preserved, and tryptophan-rich 169-amino-acid protein which localizes on the contact sites between the outer and inner mitochondrial membranes of steroid-synthesizing cells. This mitochondrial protein is implicated in an extensive range of cellular activities, including steroid synthesis, cholesterol transport, apoptosis, mitochondrial respiration, and cell proliferation. The upregulation of TSPO is well documented in diverse disease conditions including neuroinflammation, cancer, brain injury, and inflammation in peripheral organs. On the basis of these outcomes, TSPO has been assumed to be a fascinating subcellular target for early stage imaging of the diseased state and for therapeutic purposes. The main outline of this Review is to give an update on dealing with the advances made in TSPO PET tracers for neuroinflammation, synchronously emphasizing the approaches applied for the design and advancement of new tracers with reference to their structure-activity relationship (SAR).
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Affiliation(s)
- Priya Singh
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Anupriya Adhikari
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Deepika Singh
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Chandraprakash Gond
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Anjani Kumar Tiwari
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
- Address:
Department of Chemistry,
Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh. Tel.: +91-7503381343. Fax: +91-522-2440821. E-mail:
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Zinnhardt B, Roncaroli F, Foray C, Agushi E, Osrah B, Hugon G, Jacobs AH, Winkeler A. Imaging of the glioma microenvironment by TSPO PET. Eur J Nucl Med Mol Imaging 2021; 49:174-185. [PMID: 33721063 DOI: 10.1007/s00259-021-05276-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/18/2021] [Indexed: 12/13/2022]
Abstract
Gliomas are highly dynamic and heterogeneous tumours of the central nervous system (CNS). They constitute the most common neoplasm of the CNS and the second most common cause of death from intracranial disease after stroke. The advances in detailing the genetic profile of paediatric and adult gliomas along with the progress in MRI and PET multimodal molecular imaging technologies have greatly improved prognostic stratification of patients with glioma and informed on treatment decisions. Amino acid PET has already gained broad clinical application in the study of gliomas. PET imaging targeting the translocator protein (TSPO) has recently been applied to decipher the heterogeneity and dynamics of the tumour microenvironment (TME) and its various cellular components especially in view of targeted immune therapies with the goal to delineate pro- and anti-glioma immune cell modulation. The current review provides a comprehensive overview on the historical developments of TSPO PET for gliomas and summarizes the most relevant experimental and clinical data with regard to the assessment and quantification of various cellular components with the TME of gliomas by in vivo TSPO PET imaging.
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Affiliation(s)
- Bastian Zinnhardt
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-University Münster (WWU), Münster, Germany
- Biomarkers and Translational Technologies, Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Federico Roncaroli
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Brain and Mental Health, University of Manchester, Manchester, UK
| | - Claudia Foray
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-University Münster (WWU), Münster, Germany
| | - Erjon Agushi
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Brain and Mental Health, University of Manchester, Manchester, UK
| | - Bahiya Osrah
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Brain and Mental Health, University of Manchester, Manchester, UK
| | - Gaëlle Hugon
- Laboratoire d'Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Université Paris-Saclay, Orsay, France
| | - Andreas H Jacobs
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-University Münster (WWU), Münster, Germany
- Department of Geriatrics and Neurology, Johanniter Hospital, Bonn, Germany
| | - Alexandra Winkeler
- Laboratoire d'Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Université Paris-Saclay, Orsay, France.
- CEA, DRF, JOLIOT, SHFJ, Orsay, France.
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7
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Kim K, Christov PP, Romaine I, Tian J, Jana S, Lamers AP, Dutter BF, Scaggs T, Jeon K, Guttentag B, Weaver CD, Lindsley CW, Waterson AG, Sulikowski GA. Ten-Year Retrospective of the Vanderbilt Institute of Chemical Biology Chemical Synthesis Core. ACS Chem Biol 2021; 16:787-793. [PMID: 33877812 DOI: 10.1021/acschembio.0c00818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chemical synthesis has been described as a central science. Its practice provides access to the chemical structures of known and/or designed function. In particular, human health is greatly impacted by synthesis that enables advancements in both basic science discoveries in chemical biology as well as translational research that can lead to new therapeutics. To support the chemical synthesis needs of investigators across campus, the Vanderbilt Institute of Chemical Biology established a chemical synthesis core as part of its foundation in 2008. Provided in this Review are examples of synthetic products, known and designed, produced in the core over the past 10 years.
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Affiliation(s)
- Kwangho Kim
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Plamen P. Christov
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Ian Romaine
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Jianhua Tian
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Somnath Jana
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Alexander P. Lamers
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Brendan F. Dutter
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Toya Scaggs
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Kyouk Jeon
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Benjamin Guttentag
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - C. David Weaver
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
- Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Alex G. Waterson
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Gary A. Sulikowski
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
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8
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Adhikari A, Singh P, Mahar KS, Adhikari M, Adhikari B, Zhang MR, Tiwari AK. Mapping of Translocator Protein (18 kDa) in Peripheral Sterile Inflammatory Disease and Cancer through PET Imaging. Mol Pharm 2021; 18:1507-1529. [PMID: 33645995 DOI: 10.1021/acs.molpharmaceut.1c00002] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Positron emission tomography (PET) imaging of the translocator 18 kDa protein (TSPO) with radioligands has become an effective means of research in peripheral inflammatory conditions that occur in many diseases and cancers. The peripheral sterile inflammatory diseases (PSIDs) are associated with a diverse group of disorders that comprises numerous enduring insults including the cardiovascular, respiratory, gastrointestinal, or musculoskeletal system. TSPO has recently been introduced as a potential biomarker for peripheral sterile inflammatory diseases (PSIDs). The major critical issue related to PSIDs is its timely characterization and localization of inflammatory foci for proper therapy of patients. As an alternative to metabolic imaging, protein imaging expressed on immune cells after activation is of great importance. The five transmembrane domain translocator protein-18 kDa (TSPO) is upregulated on the mitochondrial cell surface of macrophages during inflammation, serving as a potential ligand for PET tracers. Additionally, the overexpressed TSPO protein has been positively correlated with various tumor malignancies. In view of the association of escalated TSPO expression in both disease conditions, it is an immensely important biomarker for PET imaging in oncology and PSIDs. In this review, we summarize the most outstanding advances on TSPO-targeted PSIDs and cancer in the development of TSPO ligands as a potential diagnostic tool, specifically discussing the last five years.
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Affiliation(s)
- Anupriya Adhikari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, (A Central University), Lucknow, Uttar Pradesh 226025, India
| | - Priya Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, A Central University, Lucknow, Uttar Pradesh 226025, India
| | - Kamalesh S Mahar
- Birbal Sahni Institute of Palaeosciences, Lucknow, Uttar Pradesh 226007, India
| | - Manish Adhikari
- The George Washington University, Washington, D.C. 20052, United States
| | - Bhawana Adhikari
- Plasma Bio-science Research Center, Kwangwoon University, Seoul 01897, South Korea
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Anjani Kumar Tiwari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, (A Central University), Lucknow, Uttar Pradesh 226025, India
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9
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Cohen AS, Li J, Hight MR, McKinley E, Fu A, Payne A, Liu Y, Zhang D, Xie Q, Bai M, Ayers GD, Tantawy MN, Smith JA, Revetta F, Washington MK, Shi C, Merchant N, Manning HC. TSPO-targeted PET and Optical Probes for the Detection and Localization of Premalignant and Malignant Pancreatic Lesions. Clin Cancer Res 2020; 26:5914-5925. [PMID: 32933996 DOI: 10.1158/1078-0432.ccr-20-1214] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/24/2020] [Accepted: 09/10/2020] [Indexed: 12/28/2022]
Abstract
PURPOSE Pancreatic cancer is among the most aggressive malignancies and is rarely discovered early. However, pancreatic "incidentalomas," particularly cysts, are frequently identified in asymptomatic patients through anatomic imaging for unrelated causes. Accurate determination of the malignant potential of cystic lesions could lead to life-saving surgery or spare patients with indolent disease undue risk. Current risk assessment of pancreatic cysts requires invasive sampling, with attendant morbidity and sampling errors. Here, we sought to identify imaging biomarkers of high-risk pancreatic cancer precursor lesions. EXPERIMENTAL DESIGN Translocator protein (TSPO) expression, which is associated with cholesterol metabolism, was evaluated in premalignant and pancreatic cancer lesions from human and genetically engineered mouse (GEM) tissues. In vivo imaging was performed with [18F]V-1008, a TSPO-targeted PET agent, in two GEM models. For image-guided surgery (IGS), V-1520, a TSPO ligand for near-IR optical imaging based upon the V-1008 pharmacophore, was developed and evaluated. RESULTS TSPO was highly expressed in human and murine pancreatic cancer. Notably, TSPO expression was associated with high-grade, premalignant intraductal papillary mucinous neoplasms (IPMNs) and pancreatic intraepithelial neoplasia (PanIN) lesions. In GEM models, [18F]V-1008 exhibited robust uptake in early pancreatic cancer, detectable by PET. Furthermore, V-1520 localized to premalignant pancreatic lesions and advanced tumors enabling real-time IGS. CONCLUSIONS We anticipate that combined TSPO PET/IGS represents a translational approach for precision pancreatic cancer care through discrimination of high-risk indeterminate lesions and actionable surgery.
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Affiliation(s)
- Allison S Cohen
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jun Li
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Matthew R Hight
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Eliot McKinley
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee
| | - Allie Fu
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Adria Payne
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yang Liu
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dawei Zhang
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Qing Xie
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Mingfeng Bai
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Gregory D Ayers
- Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Mohammed Noor Tantawy
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jarrod A Smith
- Vanderbilt University Center for Structural Biology, Vanderbilt University, Nashville, Tennessee
| | - Frank Revetta
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - M Kay Washington
- Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Chanjuan Shi
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Nipun Merchant
- Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
| | - H Charles Manning
- Vanderbilt Center for Molecular Probes, Vanderbilt University Medical Center, Nashville, Tennessee. .,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee
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10
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Tang D, Li J, Nickels ML, Huang G, Cohen AS, Manning HC. Preclinical Evaluation of a Novel TSPO PET Ligand 2-(7-Butyl-2-(4-(2-[ 18F]Fluoroethoxy)phenyl)-5-Methylpyrazolo[1,5-a]Pyrimidin-3-yl)-N,N-Diethylacetamide ( 18F-VUIIS1018A) to Image Glioma. Mol Imaging Biol 2019; 21:113-121. [PMID: 29869061 DOI: 10.1007/s11307-018-1198-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE There is an urgent need for the development of novel positron emission tomography (PET) tracers for glioma imaging. In this study, we developed a novel PET probe ([18F]VUIIS1018A) by targeting translocator protein (TSPO), an imaging biomarker for glioma. The purpose of this preclinical study was to evaluate this novel TSPO probe for glioma imaging. PROCEDURES In this study, we synthesized [19F]VUIIS1018A and the precursor for radiosynthesis of [18F]VUIIS1018A. TSPO binding affinity was confirmed using a radioligand competitive binding assay in C6 glioma cell lysate. Further, dynamic imaging studies were performed in rats using a microPET system. These studies include displacement and blocking studies for ligand reversibility and specificity evaluation, and compartment modeling of PET data for pharmacokinetic parameter measurement using metabolite-corrected arterial input functions and PMOD. RESULTS Compared to previously reported TSPO tracers including [18F]VUIIS1008 and [18F]DPA-714, the novel tracer [18F]VUIIS1018A demonstrated higher binding affinity and BPND. Pretreatment with the cold analog [19F]VUIIS1018A could partially block tumor accumulation of this novel tracer. Further, compartment modeling of this novel tracer also exhibited a greater tumor-to-background ratio, a higher tumor binding potential and a lower brain binding potential when compared with other TSPO probes, such as [18F]DPA-714 and [18F]VUIIS1008. CONCLUSIONS These studies illustrate that [18F]VUIIS1018A can serve as a promising TSPO PET tracer for glioma imaging and potentially imaging of other solid tumors.
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Affiliation(s)
- Dewei Tang
- Center for Molecular Imaging, Shanghai University of Medicine & Health Sciences, Shanghai, China.,Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Jun Li
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael L Nickels
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Gang Huang
- Center for Molecular Imaging, Shanghai University of Medicine & Health Sciences, Shanghai, China.,Department of Nuclear Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Allison S Cohen
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA.,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA
| | - H Charles Manning
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA. .,Vanderbilt Center for Molecular Probes (CMP), Vanderbilt University Medical School, 1161 21st Ave. S., AA 1105 MCN, Nashville, TN, 37232-2310, USA. .,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA. .,Program in Chemical and Physical Biology, Vanderbilt University Medical Center, Nashville, TN, USA. .,Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN, USA. .,Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA. .,Department of Neurosurgery, Vanderbilt University Medical Center, Nashville, TN, USA.
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11
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Xia Y, Ledwitch K, Kuenze G, Duran A, Li J, Sanders CR, Manning C, Meiler J. A unified structural model of the mammalian translocator protein (TSPO). JOURNAL OF BIOMOLECULAR NMR 2019; 73:347-364. [PMID: 31243635 PMCID: PMC8006375 DOI: 10.1007/s10858-019-00257-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Accepted: 06/10/2019] [Indexed: 05/10/2023]
Abstract
The translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), is a membrane protein located on the outer mitochondrial membrane. Experimentally-derived structures of mouse TSPO (mTSPO) and its homologs from bacterial species have been determined by NMR spectroscopy and X-ray crystallography, respectively. These structures and ligand interactions within the TSPO binding pocket display distinct differences. Here, we leverage experimental and computational studies to derive a unified structural model of mTSPO in the presence and absence of the TSPO ligand, PK11195, and study the effects of DPC detergent micelles on the TSPO structure and ligand binding. From this work, we conclude that that the lipid-mimetic system used to solubilize mTSPO for NMR studies thermodynamically destabilizes the protein, introduces structural perturbations, and alters the characteristics of ligand binding. Furthermore, we used Rosetta to construct a unified mTSPO model that reconciles deviating features of the mammalian and bacterial TSPO. These deviating features are likely a consequence of the detergent system used for structure determination of mTSPO by NMR. The unified mTSPO model agrees with available experimental NMR data, appears to be physically realistic (i.e. thermodynamically not frustrated as judged by the Rosetta energy function), and simultaneously shares the structural features observed in sequence-conserved regions of the bacterial proteins. Finally, we identified the binding site for an imaging ligand VUIIS8310 that is currently positioned for clinical translation using NMR spectroscopy and propose a computational model of the VUIIS8310-mTSPO complex.
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Affiliation(s)
- Yan Xia
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Kaitlyn Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Amanda Duran
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Jun Li
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN, 37240, USA
| | - Charles Manning
- Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN, 37240, USA.
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Chemistry, Center for Structural Biology, Vanderbilt University, MRBIII 5144B, Nashville, TN, 37232, USA.
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12
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Keller T, López-Picón FR, Krzyczmonik A, Forsback S, Kirjavainen AK, Takkinen JS, Alzghool O, Rajander J, Teperi S, Cacheux F, Damont A, Dollé F, Rinne JO, Solin O, Haaparanta-Solin M. [ 18F]F-DPA for the detection of activated microglia in a mouse model of Alzheimer's disease. Nucl Med Biol 2018; 67:1-9. [PMID: 30317069 DOI: 10.1016/j.nucmedbio.2018.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/03/2018] [Accepted: 09/23/2018] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Neuroinflammation is associated with several neurological disorders, including Alzheimer's disease (AD). The translocator protein 18 kDa (TSPO), due to its overexpression during microglial activation and relatively low levels in the brain under normal neurophysiological conditions, is commonly used as an in vivo biomarker for neuroinflammation. Reported here is the preclinical evaluation of [18F]F-DPA, a promising new TSPO-specific radioligand, as a tool for the detection of activated microglia at different ages in the APP/PS1-21 mouse model of AD and a blocking study to determine the specificity of the tracer. METHODS [18F]F-DPA was synthesised by the previously reported electrophilic 18F-fluorination methodology. In vivo PET and ex vivo brain autoradiography were used to observe the tracer distribution in the brains of APP/PS1-21 and wildtype mice at different ages (4.5-24 months). The biodistribution and degree of metabolism of [18F]F-DPA were analysed and the specificity of [18F]F-DPA for its target was determined by pre-treatment with PK11195. RESULTS The in vivo PET imaging and ex vivo brain autoradiography data showed that [18F]F-DPA uptake in the brains of the transgenic animals increased with age, however, there was a drop in the tracer uptake at 19 mo. Despite the slight increase in [18F]F-DPA uptake with age in healthy animal brains, significant differences between wildtype and transgenic animals were seen in vivo at 9 months and ex vivo already at 4.5 months. The specificity study demonstrated that PK11195 can be used to significantly block [18F]F-DPA uptake in all the brain regions studied. CONCLUSIONS In vivo time activity curves plateaued at approximately 20-40 min suggesting that this is the optimal imaging time. Significant differences in vivo are seen at 9 and 12 mo. Due to the higher resolution, ex vivo autoradiography with [18F]F-DPA can be used to visualise activated microglia at an early stage of AD pathology.
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Affiliation(s)
- Thomas Keller
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Finland.
| | - Francisco R López-Picón
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Finland; MediCity Research Laboratory, University of Turku, Finland
| | - Anna Krzyczmonik
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Finland
| | - Sarita Forsback
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Finland; Department of Chemistry, University of Turku, Finland
| | - Anna K Kirjavainen
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Finland
| | - Jatta S Takkinen
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Finland; MediCity Research Laboratory, University of Turku, Finland
| | - Obada Alzghool
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Finland; MediCity Research Laboratory, University of Turku, Finland
| | - Johan Rajander
- Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Finland
| | - Simo Teperi
- Department of Biostatistics, University of Turku, Finland
| | - Fanny Cacheux
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | | | - Frédéric Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Juha O Rinne
- Turku PET Centre, Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland
| | - Olof Solin
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Finland; Department of Chemistry, University of Turku, Finland; Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Finland
| | - Merja Haaparanta-Solin
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Finland; MediCity Research Laboratory, University of Turku, Finland
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13
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Berroterán-Infante N, Balber T, Fürlinger P, Bergmann M, Lanzenberger R, Hacker M, Mitterhauser M, Wadsak W. [ 18F]FEPPA: Improved Automated Radiosynthesis, Binding Affinity, and Preliminary in Vitro Evaluation in Colorectal Cancer. ACS Med Chem Lett 2018. [PMID: 29541356 DOI: 10.1021/acsmedchemlett.7b00367] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The overexpression of the translocator protein (TSPO) has been amply reported for a variety of conditions, including neurodegenerative disorders, heart failure, and cancer. Thus, TSPO has been proposed as an excellent imaging biomarker, allowing, in this manner, to obtain an accurate diagnosis and to follow disease progression and therapy response. Accordingly, several radioligands have been developed to accomplish this purpose. In this work, we selected [18F]FEPPA, as one of the clinical established tracers, and assessed its in vitro performance in colorectal cancer. Moreover, we setup an improved radiosynthesis method and assessed the in vitro binding affinity of the nonradioactive ligand toward the human TSPO. Our results show an excellent to moderate affinity, in the subnanomolar and nanomolar range, as well as the suitability of [18F]FEPPA as an imaging agent for the TSPO in colorectal cancer.
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Affiliation(s)
- Neydher Berroterán-Infante
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria
- Department of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Vienna A-1090, Austria
| | - Theresa Balber
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria
- Department of Pharmaceutical Technology, Faculty of Life Sciences, University of Vienna, Vienna A-1090, Austria
| | - Petra Fürlinger
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria
| | - Michael Bergmann
- Surgical Research Laboratories, Department of Surgery, Medical University of Vienna, Vienna A-1090, Austria
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna A-1090, Austria
| | - Marcus Hacker
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria
| | - Markus Mitterhauser
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria
- Department of Pharmaceutical Technology, Faculty of Life Sciences, University of Vienna, Vienna A-1090, Austria
- Ludwig Boltzmann Institute Applied Diagnostics, Vienna A-1090, Austria
| | - Wolfgang Wadsak
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna A-1090, Austria
- Department of Inorganic Chemistry, Faculty of Chemistry, University of Vienna, Vienna A-1090, Austria
- Center for Biomarker Research in Medicine, CBmed GmbH, Graz A-8010, Austria
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14
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Li J, Smith JA, Dawson ES, Fu A, Nickels ML, Schulte ML, Manning HC. Optimized Translocator Protein Ligand for Optical Molecular Imaging and Screening. Bioconjug Chem 2017; 28:1016-1023. [PMID: 28156095 DOI: 10.1021/acs.bioconjchem.6b00711] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Translocator protein (TSPO) is a validated target for molecular imaging of a variety of human diseases and disorders. Given its involvement in cholesterol metabolism, TSPO expression is commonly elevated in solid tumors, including glioma, colorectal cancer, and breast cancer. TSPO ligands capable of detection by optical imaging are useful molecular tracers for a variety of purposes that range from quantitative biology to drug discovery. Leveraging our prior optimization of the pyrazolopyrimidine TSPO ligand scaffold for cancer imaging, we report herein a new generation of TSPO tracers with superior binding affinity and suitability for optical imaging and screening. In total, seven candidate TSPO tracers were synthesized and vetted in this study; the most promising tracer identified (29, Kd = 0.19 nM) was the result of conjugating a high-affinity TSPO ligand to a fluorophore used routinely in biological sciences (FITC) via a functional carbon linker of optimal length. Computational modeling suggested that an n-alkyl linker of eight carbons in length allows for positioning of the bulky fluorophore distal to the ligand binding domain and toward the solvent interface, minimizing potential ligand-protein interference. Probe 29 was found to be highly suitable for in vitro imaging of live TSPO-expressing cells and could be deployed as a ligand screening and discovery tool. Competitive inhibition of probe 29 quantified by fluorescence and 3H-PK11195 quantified by traditional radiometric detection resulted in equivalent affinity data for two previously reported TSPO ligands. This study introduces the utility of TSPO ligand 29 for in vitro imaging and screening and provides a structural basis for the development of future TSPO imaging ligands bearing bulky signaling moieties.
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Affiliation(s)
- Jun Li
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Jarrod A Smith
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Eric S Dawson
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Allie Fu
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Michael L Nickels
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - Michael L Schulte
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
| | - H Charles Manning
- Interdisciplinary Materials Science Program, ∥Vanderbilt University Center for Structural Biology, and ■Department of Biomedical Engineering, Vanderbilt University , Nashville, Tennessee 37232, United States.,Vanderbilt University Institute of Imaging Science (VUIIS), §Center for Molecular Probes, ⊥Department of Radiology and Radiological Sciences, #Department of Biochemistry, ¶Vanderbilt-Ingram Cancer Center (VICC), and ▽Department of Neurosurgery, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
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