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Carrasco RA, Salih AK, Garcia MD, Khozeimeh ES, Adams GP, Phenix CP, Price EW. Development and Biodistribution of a Nerve Growth Factor Radioactive Conjugate for PET Imaging. Mol Imaging Biol 2023; 25:977-988. [PMID: 36692661 DOI: 10.1007/s11307-023-01805-w] [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] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/16/2023] [Accepted: 01/16/2023] [Indexed: 01/25/2023]
Abstract
PURPOSE The purpose of these studies was to develop a nerve growth factor (NGF) radiometal-chelator conjugate to determine the biodistribution and brain uptake of NGF by positron emission tomography/computerized tomography (PET-CT). PROCEDURES Purified NGF from llama seminal plasma was conjugated with FITC, and the chelator NOTA or DFO. NGF conjugates were evaluated for bioactivity. NOTA- and DFO-conjugated NGF were radiolabeled with gallium-68 or zirconium-89 ([68 Ga]GaCl3, half-life = 68 min; [89Zr]Zr(oxalate)4, half-life = 3.3 days). [89Zr]Zr-NGF was evaluated for biodistribution (0.5, 1, or 24 h), PET imaging (60 min), and brain autoradiography in mice. RESULTS Cell-based in vitro assays confirmed that the NGF conjugates maintained NGF receptor-binding and biological activity. Zirconium-89 and gallium-68 radiolabeling showed a high efficiency; however, only[89Zr]Zr-NGF was stable in vitro. Biodistribution studies showed that, as with most small proteins < 70 kDa, [89Zr]Zr-NGF uptake was predominantly in the kidney and was cleared rapidly with almost complete elimination of NGF at 24 h. Dynamic PET imaging from 0-60 min showed a similar pattern to ex vivo biodistribution with some transient liver uptake. Interestingly, although absolute brain uptake was very low, at 24 h after treatment, cerebral cortex uptake was higher than any other brain area examined and blood. CONCLUSIONS We conclude that conjugation of DFO to NGF through a thiourea linkage allows effective radiolabeling with zirconium-89 while maintaining NGF bioactivity. Following intravenous administration, the radiolabeled NGF targets non-neuronal tissues (e.g., kidney, liver), and although absolute brain uptake was very low, the brain uptake that was observed was restricted to the cortex.
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Affiliation(s)
- R A Carrasco
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N5C9, Canada
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, S7N5B4, Canada
| | - A K Salih
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N5C9, Canada
| | - M Dominguez Garcia
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N5C9, Canada
| | - E S Khozeimeh
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N5C9, Canada
| | - G P Adams
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, S7N5B4, Canada
| | - C P Phenix
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N5C9, Canada.
| | - E W Price
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N5C9, Canada.
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Aigbogun OP, Phenix CP, Krol ES, Price EW. The Chemistry of Creating Chemically Programmed Antibodies (cPAbs): Site-Specific Bioconjugation of Small Molecules. Mol Pharm 2023; 20:853-874. [PMID: 36696533 DOI: 10.1021/acs.molpharmaceut.2c00821] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Small-molecule drugs have been employed for years as therapeutics in the pharmaceutical industry. However, small-molecule drugs typically have short in vivo half-lives which is one of the largest impediments to the success of many potentially valuable pharmacologically active small molecules. The undesirable pharmacokinetics and pharmacology associated with some small molecules have led to the development of a new class of bioconjugates known as chemically programmed antibodies (cPAbs). cPAbs are bioconjugates in which antibodies are used to augment small molecules with effector functions and prolonged pharmacokinetic profiles, where the pharmacophore of the small molecule is harnessed for target binding and therefore biological targeting. Many different small molecules can be conjugated to large proteins such as full monoclonal antibodies (IgG), fragment crystallizable regions (Fc), or fragment antigen binding regions (Fab). In order to successfully and site-specifically conjugate small molecules to any class of antibodies (IgG, Fc, or Fab), the molecules must be derivatized with a functional group for ease of conjugation without altering the pharmacology of the small molecules. In this Review, we summarize the different synthetic or biological methods that have been employed to produce cPAbs. These unique chemistries have potential to be applied to other fields of antibody modification such as antibody drug conjugates, radioimmunoconjugates, and fluorophore-tagged antibodies.
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Affiliation(s)
- Omozojie P Aigbogun
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, S7N-5C9 Saskatchewan, Canada
| | - Christopher P Phenix
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, S7N-5C9 Saskatchewan, Canada
| | - Ed S Krol
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, 107 Wiggins Road, Saskatoon, S7N-5E5 Saskatchewan, Canada
| | - Eric W Price
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, S7N-5C9 Saskatchewan, Canada
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3
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Aigbogun OP, Nwabufo CK, Owens MN, Allen KJH, Lee JS, Phenix CP, Krol ES. An HPLC-UV validated bioanalytical method for measurement of in vitro phase 1 kinetics of α-synuclein binding bifunctional compounds. Xenobiotica 2022; 52:916-927. [PMID: 36282181 DOI: 10.1080/00498254.2022.2140315] [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] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Aggregates of the protein α-synuclein are associated with pathophysiology of Parkinson's disease and are present in Lewy Bodies found in the brains of Parkinson's patients. We previously demonstrated that bifunctional compounds composed of caffeine linked via a six carbon chain to either 1-aminoindan (C8-6-I) or nicotine (C8-6-N) bind α-synuclein and protect yeast cells from α-synuclein mediated toxicity.A critical step in development of positron emission tomography (PET) probes for neurodegenerative diseases is evaluation of their metabolic stability. We determined that C8-6-I, and C8-6-N both undergo phase 1 P450 metabolism in mouse, rat, and human liver microsomes. We utilised this metabolic information to guide the design of fluorinated analogues for use as PET probes and determined that the fluorine in 19F-C8-6-I and 19F-C8-6-N is stable to P450 enzymes.We have developed and validated an analytical HPLC-UV method following FDA and EMA guidelines to measure in vitro phase 1 kinetics of these compounds and determine their Vmax, KM and CLint,u in mouse liver microsomes. We found that C8-6-I and 19F-C8-6-I have a two- to fourfold lower CLint,u than C8-6-N, and 19F-C8-6-N. Our approach shows a simple, specific, and effective system to design and develop compounds as PET probes.
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Affiliation(s)
- Omozojie P Aigbogun
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Chukwunonso K Nwabufo
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Madeline N Owens
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Kevin J H Allen
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jeremy S Lee
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Christopher P Phenix
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Ed S Krol
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Nwabufo CK, Aigbogun OP, Allen KJH, Owens MN, Lee JS, Phenix CP, Krol ES. Employing in vitro metabolism to guide design of F-labelled PET probes of novel α-synuclein binding bifunctional compounds. Xenobiotica 2021; 51:885-900. [PMID: 34187286 DOI: 10.1080/00498254.2021.1943566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A challenge in the development of novel 18F-labelled positron emission tomography (PET) imaging probes is identification of metabolically stable sites to incorporate the 18F radioisotope. Metabolic loss of 18F from PET probes in vivo can lead to misleading biodistribution data as displaced 18F can accumulate in various tissues.In this study we report on in vitro hepatic microsomal metabolism of novel caffeine containing bifunctional compounds (C8-6-I, C8-6-N, C8-6-C8) that can prevent in vitro aggregation of α-synuclein, which is associated with the pathophysiology of Parkinson's disease. The metabolic profile obtained guided us to synthesize stable isotope 19F-labelled analogues in which the fluorine was introduced at the metabolically stable N7 of the caffeine moiety.An in vitro hepatic microsomal metabolism study of the 19F-labelled analogues resulted in similar metabolites to the unlabelled compounds and demonstrated that the fluorine was metabolically stable, suggesting that these analogues are appropriate PET imaging probes. This straightforward in vitro strategy is valuable for avoiding costly stability failures when designing radiolabelled compounds for PET imaging.
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Affiliation(s)
- Chukwunonso K Nwabufo
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada
| | | | - Kevin J H Allen
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada
| | - Madeline N Owens
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Jeremy S Lee
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Canada
| | | | - Ed S Krol
- Drug Discovery and Development Research Group, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada
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Huska B, Niccoli S, Phenix CP, Lees SJ. Leucine Potentiates Glucose-mediated 18F-FDG Uptake in Brown Adipose Tissue via β-Adrenergic Activation. Biomedicines 2020; 8:biomedicines8060159. [PMID: 32545834 PMCID: PMC7345234 DOI: 10.3390/biomedicines8060159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 05/27/2020] [Accepted: 06/10/2020] [Indexed: 01/07/2023] Open
Abstract
Significant depots of brown adipose tissue (BAT) have been identified in many adult humans through positron emission tomography (PET), with the amount of BAT being inversely correlated with obesity. As dietary activation of BAT has implications for whole body glucose metabolism, leucine was used in the present study to determine its ability to promote BAT activation resulting in increased glucose uptake. In order to assess this, 2-deoxy-2-(fluorine-18)fluoro-d-glucose (18F-FDG) uptake was measured in C57BL/6 mice using microPET after treatment with leucine, glucose, or both in interscapular BAT (IBAT). Pretreatment with propranolol (PRP) was used to determine the role of β-adrenergic activation in glucose and leucine-mediated 18F-FDG uptake. Analysis of maximum standardized uptake values (SUVMAX) determined that glucose administration increased 18F-FDG uptake in IBAT by 25.3%. While leucine did not promote 18F-FDG uptake alone, it did potentiate glucose-mediated 18F-FDG uptake, increasing 18F-FDG uptake in IBAT by 22.5%, compared to glucose alone. Pretreatment with PRP prevented the increase in IBAT 18F-FDG uptake following the combination of glucose and leucine administration. These data suggest that leucine is effective in promoting BAT 18F-FDG uptake through β-adrenergic activation in combination with glucose.
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Affiliation(s)
- Brenda Huska
- Biology, Lakehead University, Thunder Bay, ON P7B 5E1, Canada;
| | - Sarah Niccoli
- Medical Sciences, Lakehead University Faculty of Medicine, Thunder Bay, ON P7B 5E1, Canada;
- Northern Ontario School of Medicine, Medical Sciences Division, Thunder Bay, ON P7B 5E1, Canada
| | - Christopher P. Phenix
- Northern Ontario School of Medicine, Medical Sciences Division, Thunder Bay, ON P7B 5E1, Canada
- Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada
- Thunder Bay Regional Health Research Institute, Thunder Bay, ON P7A 7T1, Canada
- Correspondence: (C.P.P.); (S.J.L.); Tel.: +1-(306)-966-4193 (C.P.P.); +1-(807)-766-7435 (S.J.L.); Fax: +1-(306)-966-4730 (C.P.P.); +1-(807)-766-7362 (S.J.L.)
| | - Simon J. Lees
- Biology, Lakehead University, Thunder Bay, ON P7B 5E1, Canada;
- Medical Sciences, Lakehead University Faculty of Medicine, Thunder Bay, ON P7B 5E1, Canada;
- Northern Ontario School of Medicine, Medical Sciences Division, Thunder Bay, ON P7B 5E1, Canada
- Correspondence: (C.P.P.); (S.J.L.); Tel.: +1-(306)-966-4193 (C.P.P.); +1-(807)-766-7435 (S.J.L.); Fax: +1-(306)-966-4730 (C.P.P.); +1-(807)-766-7362 (S.J.L.)
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Wang S, Vigliarolo BG, Chowdhury MA, Nyarko JNK, Mousseau DD, Phenix CP. Design and synthesis of fluorogenic substrate-based probes for detecting Cathepsin B activity. Bioorg Chem 2019; 92:103194. [PMID: 31493706 DOI: 10.1016/j.bioorg.2019.103194] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/27/2019] [Accepted: 08/11/2019] [Indexed: 11/18/2022]
Abstract
Cathepsin B plays key roles in tumor progression with its overexpression being associated with invasive and metastatic phenotypes and is a primary target of protease activated antibody-directed prodrug therapy. It therefore represents a potential therapeutic and diagnostic target and effort has been made to develop fluorescent probes to report on Cathepsin B activity in cells and animal models of cancer. We have designed, synthesized, and thoroughly evaluated four novel "turn on" probes that employ a lysosomotropic dansylcadaverine dye to report on Cathepsin B activity. Enzyme activity assays using a recombinant human enzyme and cancer cell lysates coupled with confocal microscopy experiments demonstrated that one of the probes, derivatized with the self-immolative prodrug linker p-aminobenzyl alcohol, can selectively report on Cathepsin B in biological samples including live cells.
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Affiliation(s)
- Shusheng Wang
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Brady G Vigliarolo
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Morshed A Chowdhury
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Jennifer N K Nyarko
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | - Darrell D Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | - Christopher P Phenix
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
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7
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Abstract
Hydrolytic enzymes are a large class of biological catalysts that play a vital role in a plethora of critical biochemical processes required to maintain human health. However, the expression and/or activity of these important enzymes can change in many different diseases and therefore represent exciting targets for the development of positron emission tomography (PET) and single-photon emission computed tomography (SPECT) radiotracers. This review focuses on recently reported radiolabeled substrates, reversible inhibitors, and irreversible inhibitors investigated as PET and SPECT tracers for imaging hydrolytic enzymes. By learning from the most successful examples of tracer development for hydrolytic enzymes, it appears that an early focus on careful enzyme kinetics and cell-based studies are key factors for identifying potentially useful new molecular imaging agents.
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Affiliation(s)
- Brian P Rempel
- 1 Department of Science, Augustana Faculty, University of Alberta, Edmonton, Alberta, Canada
| | - Eric W Price
- 2 Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Christopher P Phenix
- 2 Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,3 Biomarker Discovery, Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
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8
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Davidson CQ, Phenix CP, Tai TC, Khaper N, Lees SJ. Searching for novel PET radiotracers: imaging cardiac perfusion, metabolism and inflammation. Am J Nucl Med Mol Imaging 2018; 8:200-227. [PMID: 30042871 PMCID: PMC6056242] [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] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/20/2018] [Indexed: 06/08/2023]
Abstract
Advances in medical imaging technology have led to an increased demand for radiopharmaceuticals for early and accurate diagnosis of cardiac function and diseased states. Myocardial perfusion, metabolism, and hypoxia positron emission tomography (PET) imaging radiotracers for detection of cardiac disease lack specificity for targeting inflammation that can be an early indicator of cardiac disease. Inflammation can occur at all stages of cardiac disease and currently, 18F-fluorodeoxyglucose (FDG), a glucose analog, is the standard for detecting myocardial inflammation. 18F-FDG has many ideal characteristics of a radiotracer but lacks the ability to differentiate between glucose uptake in normal cardiomyocytes and inflammatory cells. Developing a PET radiotracer that differentiates not only between inflammatory cells and normal cardiomyocytes, but between types of immune cells involved in inflammation would be ideal. This article reviews current PET radiotracers used in cardiac imaging, their limitations, and potential radiotracer candidates for imaging cardiac inflammation in early stages of development of acute and chronic cardiac diseases. The select radiotracers reviewed have been tested in animals and/or show potential to be developed as a radiotracer for the detection of cardiac inflammation by targeting the enzymatic activities or subpopulations of macrophages that are recruited to an injured or infected site.
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Affiliation(s)
| | - Christopher P Phenix
- Department of Chemistry, University of SaskatchewanSaskatoon, Saskatchewan, Canada
| | - TC Tai
- Medical Sciences Division, Northern Ontario School of Medicine, Laurentian UniversitySudbury, Ontario, Canada
| | - Neelam Khaper
- Department of Biology, Lakehead UniversityThunder Bay, Ontario, Canada
- Medical Sciences Division, Northern Ontario School of Medicine, Lakehead UniversityThunder Bay, Ontario, Canada
| | - Simon J Lees
- Department of Biology, Lakehead UniversityThunder Bay, Ontario, Canada
- Medical Sciences Division, Northern Ontario School of Medicine, Lakehead UniversityThunder Bay, Ontario, Canada
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9
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Niccoli S, Boreham DR, Phenix CP, Lees SJ. Non-radioactive 2-deoxy-2-fluoro-D-glucose inhibits glucose uptake in xenograft tumours and sensitizes HeLa cells to doxorubicin in vitro. PLoS One 2017; 12:e0187584. [PMID: 29095925 PMCID: PMC5667878 DOI: 10.1371/journal.pone.0187584] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/23/2017] [Indexed: 12/23/2022] Open
Abstract
A glucose analog called 2-deoxy-D-glucose (2DG) has been successfully used to sensitize cancer cells to ROS-inducing cancer treatments such as ionizing radiation, through the inhibition of glycolysis. However, the use of 2DG can be limited by several factors such as availability, non-specific cytotoxicity, and chemoresistance under hypoxic conditions. The purpose of this study was to investigate the use of non-radioactive 2-deoxy-2-fluoro-D-glucose (19FDG), a drug that potentially addresses current limitations of 2DG. The effectiveness of using either 2DG or 19FDG in combination with doxorubicin (Dox) in HeLa cells was determined in both normoxia and hypoxia. We have also shown that under both oxygen conditions, 19FDG-treated cells produce less lactate than 2DG-treated cells, an important finding that suggests improved inhibition of glycolysis, the preferential pathway for cancerous cells. When used in combination with Dox, we have demonstrated a significant decrease in the number of viable cells, with the effect of 19FDG remaining stable across both normoxic and hypoxic conditions. Moreover, the assessment of apoptosis and necrosis revealed that 19FDG maintained its ability to sensitize HeLa cells to Dox in hypoxia, but 2DG was only effective under normoxic conditions. The retained effectiveness of 19FDG in combination with Dox under hypoxic conditions, suggests that 19FDG may be efficacious for sensitizing hypoxic regions of solid tumour masses. Importantly, the ability of 19FDG to inhibit glucose uptake in vivo was also confirmed using positron emission tomography (PET) of xenograft tumours. The results displayed here suggest 19FDG is a promising combination therapy, which may lead to decreased ROS scavenging via glycolysis, and enhanced treatment success.
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Affiliation(s)
- Sarah Niccoli
- Medical Sciences, Lakehead University Faculty of Medicine, Thunder Bay, Ontario, Canada
| | - Douglas R. Boreham
- Medical Sciences Division, Northern Ontario School of Medicine, Thunder Bay, Ontario, Canada
| | - Christopher P. Phenix
- Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
| | - Simon J. Lees
- Medical Sciences, Lakehead University Faculty of Medicine, Thunder Bay, Ontario, Canada
- Medical Sciences Division, Northern Ontario School of Medicine, Thunder Bay, Ontario, Canada
- Biology, Lakehead University, Thunder Bay, Ontario, Canada
- * E-mail:
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Kamstra RL, Dadgar S, Wigg J, Chowdhury MA, Phenix CP, Floriano WB. Creating and virtually screening databases of fluorescently-labelled compounds for the discovery of target-specific molecular probes. J Comput Aided Mol Des 2014; 28:1129-42. [PMID: 25150502 DOI: 10.1007/s10822-014-9789-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 08/14/2014] [Indexed: 10/24/2022]
Abstract
Our group has recently demonstrated that virtual screening is a useful technique for the identification of target-specific molecular probes. In this paper, we discuss some of our proof-of-concept results involving two biologically relevant target proteins, and report the development of a computational script to generate large databases of fluorescence-labelled compounds for computer-assisted molecular design. The virtual screening of a small library of 1,153 fluorescently-labelled compounds against two targets, and the experimental testing of selected hits reveal that this approach is efficient at identifying molecular probes, and that the screening of a labelled library is preferred over the screening of base compounds followed by conjugation of confirmed hits. The automated script for library generation explores the known reactivity of commercially available dyes, such as NHS-esters, to create large virtual databases of fluorescence-tagged small molecules that can be easily synthesized in a laboratory. A database of 14,862 compounds, each tagged with the ATTO680 fluorophore was generated with the automated script reported here. This library is available for downloading and it is suitable for virtual ligand screening aiming at the identification of target-specific fluorescent molecular probes.
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Affiliation(s)
- Rhiannon L Kamstra
- Department of Chemistry, Lakehead University, Thunder Bay, ON, P7B 5E1, Canada
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11
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Chowdhury MA, Moya IA, Bhilocha S, McMillan CC, Vigliarolo BG, Zehbe I, Phenix CP. Prodrug-inspired probes selective to cathepsin B over other cysteine cathepsins. J Med Chem 2014; 57:6092-104. [PMID: 24940640 DOI: 10.1021/jm500544p] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cathepsin B (CTB) is a cysteine protease believed to be an important therapeutic target or biomarker for several diseases including aggressive cancer, arthritis, and parasitic infections. The development of probes capable of assessing CTB activity in cell lysates, living cells, and animal models of disease are needed to understand its role in disease progression. However, discovering probes selective to cathepsin B over other cysteine cathepsins is a significant challenge due to overlap of preferred substrates and binding site homology in this family of proteases. Herein we report the synthesis and detailed evaluation of two prodrug-inspired fluorogenic peptides designed to be efficient and selective substrate-based probes for CTB. Through cell lysate and cell assays, a promising lead candidate was identified that is efficiently processed and has high specificity for CTB over other cysteine cathepsins. This work represents a key step toward the design of rapid release prodrugs or substrate-based molecular imaging probes specific to CTB.
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Affiliation(s)
- Morshed A Chowdhury
- Thunder Bay Regional Research Institute, 2321-290 Munro Street, Thunder Bay, Ontario, Canada , P7A 7T1
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Phenix CP, Palmer DRJ. Isothermal Titration Microcalorimetry Reveals the Cooperative and Noncompetitive Nature of Inhibition of Sinorhizobium meliloti L5-30 Dihydrodipicolinate Synthase by (S)-Lysine. Biochemistry 2008; 47:7779-81. [DOI: 10.1021/bi800629n] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher P. Phenix
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - David R. J. Palmer
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
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Phenix CP, Nienaber K, Tam PH, Delbaere LTJ, Palmer DRJ. Structural, Functional and Calorimetric Investigation of MosA, a Dihydrodipicolinate Synthase fromSinorhizobium melilotiL5–30, does not Support Involvement in Rhizopine Biosynthesis. Chembiochem 2008; 9:1591-602. [DOI: 10.1002/cbic.200700569] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Leduc YA, Phenix CP, Puttick J, Nienaber K, Palmer DRJ, Delbaere LTJ. Crystallization, preliminary X-ray diffraction and structure solution of MosA, a dihydrodipicolinate synthase from Sinorhizobium meliloti L5-30. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:49-51. [PMID: 16511261 PMCID: PMC2150934 DOI: 10.1107/s1744309105040893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 12/08/2005] [Indexed: 11/10/2022]
Abstract
The structure of MosA, a dihydrodipicolinate synthase and reported methyltransferase from Sinorhizobium meliloti, has been solved using molecular replacement with Escherichia coli dihydrodipicolinate synthase as the model. A crystal grown in the presence of pyruvate diffracted X-rays to 2.3 A resolution using synchrotron radiation and belonged to the orthorhombic space group C222(1), with unit-cell parameters a = 69.14, b = 138.87, c = 124.13 A.
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Affiliation(s)
- Yvonne A. Leduc
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Christopher P. Phenix
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Jennifer Puttick
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Kurt Nienaber
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - David R. J. Palmer
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Louis T. J. Delbaere
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
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Daniellou R, Phenix CP, Tam PH, Laliberte MC, Palmer DRJ. Stereoselective oxidation of protected inositol derivatives catalyzed by inositol dehydrogenase from Bacillus subtilis. Org Biomol Chem 2005; 3:401-3. [PMID: 15678175 DOI: 10.1039/b417757f] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inositol dehydrogenase (EC 1.1.1.18) from Bacillus subtilis is shown to have a nonpolar cavity adjacent to the active site, allowing racemic protected inositol derivatives such as 4-O-benzyl-myo-inositol to be recognized with very high apparent stereoselectivity.
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Tam PH, Phenix CP, Palmer DRJ. MosA, a protein implicated in rhizopine biosynthesis in Sinorhizobium meliloti L5-30, is a dihydrodipicolinate synthase. J Mol Biol 2004; 335:393-7. [PMID: 14672649 DOI: 10.1016/j.jmb.2003.10.063] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
MosA is a gene product encoded on a pSym megaplasmid of Sinorhizobium meliloti L5-30. The gene is part of an operon reported to be essential for the synthesis of the rhizopine 3-O-methyl-scyllo-inosamine. MosA has been assigned the function of an O-methyltransferase. However, the reported sequence of this protein is very much like that of dihydrodipicolinate synthase (DHDPS), except for a 40 amino acid residue C-terminal domain. This similarity contradicts accepted ideas regarding structure-function relationships of enzymes. We have cloned and overexpressed the recombinant gene in Escherichia coli, and discovered that the reported sequence contains an error resulting in a frame-shift. The correct sequence contains a new stop codon, truncating the C-terminal 41 amino acid residues of the reported sequence. The expressed protein, bearing an N-terminal polyhistidine tag, catalyzes the condensation of pyruvate and aspartate beta-semialdehyde efficiently, suggesting that this activity is not a side-reaction, but an activity for which this enzyme has evolved. Electro-spray mass spectrometry experiments and inhibition by L-lysine are consistent with the enzyme being a DHDPS. E.coli AT997, a mutant host normally requiring exogenous diaminopimelate for growth, could be complemented by transformation with a plasmid bearing the gene encoding MosA. A role for this enzyme in rhizopine synthesis cannot be ruled out, but is called into question.
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Affiliation(s)
- Pui Hang Tam
- Department of Biochemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Sask., Canada S7N 5C9
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