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Khalil A, Adam MSS. Nucleoside Scaffolds and Carborane Clusters for Boron Neutron Capture Therapy: Developments and Future Perspective. Curr Med Chem 2024; 31:5739-5754. [PMID: 37818562 DOI: 10.2174/0109298673245020230929152030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 06/19/2023] [Accepted: 08/24/2023] [Indexed: 10/12/2023]
Abstract
Nucleosides containing carboranes are one of the most important boron delivery agents for boron neutron capture therapy, BNCT, which are good substrates of hTK1. The development of several nucleosides containing carboranes at early stages led to the discovery of the first generation of 3CTAs by incorporating a hydrocarbon spacer between the thymidine scaffold and carborane cluster and attaching dihydroxylpropyl group on the second carbon (C2) atom of the carborane cluster (e.g., N5 and N5-2OH). Phosphorylation rate, tumor cellular uptake, and retention have been evaluated in parallel to change the length of the tether arm of spacers in these compounds. Many attempts were reported and discussed to overcome the disadvantage of the first generation of 3CTAs by a) incorporating modified spacers between thymidine and carborane clusters, such as ethyleneoxide, polyhydroxyl, triazole, and tetrazole units, b) attaching hydrophilic groups at C2 of the carborane cluster, c) transforming lipophilic closo-carboranes to hydrophilic nidocarborane. The previous modifications represented the second generation of 3CTAs to improve the hydrogen bond formation with the hTK1 active site. Moreover, amino acid prodrugs were developed to enhance biological and physicochemical properties. The structure-activity relationship (SAR) of carboranyl thymidine analogues led to the roadmap for the development of the 3rd generation of the 3CTAs for BNCT.
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Affiliation(s)
- Ahmed Khalil
- Department of Chemistry, College of Science, King Faisal University, Al Ahsa 31982, Saudi Arabia
- Department of Chemistry, Faculty of Science, Zagazig University, Zagazig 44519, Egypt
| | - Mohamed Shaker S Adam
- Department of Chemistry, College of Science, King Faisal University, Al Ahsa 31982, Saudi Arabia
- Department of Chemistry, Faculty of Science, Sohag University, Sohag 82534, Egypt
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Li F, Luo Z. Boron delivery agents for boron neutron capture therapy. CHINESE SCIENCE BULLETIN-CHINESE 2021. [DOI: 10.1360/tb-2021-1013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wong AAWL, Lozada J, Lepage ML, Zhang C, Merkens H, Zeisler J, Lin KS, Bénard F, Perrin DM. Synthesis and 18F-radiolabeling of thymidine AMBF 3 conjugates. RSC Med Chem 2020; 11:569-576. [PMID: 33479658 PMCID: PMC7578706 DOI: 10.1039/d0md00054j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/09/2020] [Indexed: 01/08/2023] Open
Abstract
In pursuit of 18F-labeled nucleosides for positron emission tomography (PET) imaging, we report on the chemical and radiochemical synthesis of two thymidine (dT) analogs, dT-C5-AMBF3 and dT-N3-AMBF3, that are radiofluorinated by isotope exchange (IEX) and studied as PET imaging agents in mice with tumor xenografts. dT-C5-AMBF3 shows preferential, and tumor-specific, uptake over dT-N3-AMBF3. This work provides a new synthetic method in order to access new nucleoside tracers for PET imaging.
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Affiliation(s)
- Antonio A W L Wong
- Department of Chemistry , University of British Columbia (UBC) , 2036 Main Mall , Vancouver , BC , V6T 1Z1 Canada .
| | - Jerome Lozada
- Department of Chemistry , University of British Columbia (UBC) , 2036 Main Mall , Vancouver , BC , V6T 1Z1 Canada .
| | - Mathieu L Lepage
- Department of Chemistry , University of British Columbia (UBC) , 2036 Main Mall , Vancouver , BC , V6T 1Z1 Canada .
| | - Chengcheng Zhang
- Department of Molecular Oncology , B.C. Cancer Research Centre (BCCRC) , 675 West 10th Avenue , Vancouver , BC , V5Z 1L3 Canada
| | - Helen Merkens
- Department of Molecular Oncology , B.C. Cancer Research Centre (BCCRC) , 675 West 10th Avenue , Vancouver , BC , V5Z 1L3 Canada
| | - Jutta Zeisler
- Department of Molecular Oncology , B.C. Cancer Research Centre (BCCRC) , 675 West 10th Avenue , Vancouver , BC , V5Z 1L3 Canada
| | - Kuo-Shyan Lin
- Department of Molecular Oncology , B.C. Cancer Research Centre (BCCRC) , 675 West 10th Avenue , Vancouver , BC , V5Z 1L3 Canada
| | - François Bénard
- Department of Molecular Oncology , B.C. Cancer Research Centre (BCCRC) , 675 West 10th Avenue , Vancouver , BC , V5Z 1L3 Canada
| | - David M Perrin
- Department of Chemistry , University of British Columbia (UBC) , 2036 Main Mall , Vancouver , BC , V6T 1Z1 Canada .
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Balzarini J, Celen S, Karlsson A, de Groot T, Verbruggen A, Bormans G. The Effect of a Methyl or 2-fluoroethyl Substituent at the N-3 Position of Thymidine, 3′-fluoro-3′-deoxythymi-dine and 1-β-D-arabinosylthymine on Their Antiviral and Cytostatic Activity in Cell Culture. ACTA ACUST UNITED AC 2016; 17:17-23. [PMID: 16542002 DOI: 10.1177/095632020601700103] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Thymidine (Thd), 1-β-D-arabinosylthymine (ara-T) and 3′-fluoro-3′-deoxythymidine (FLT) have been substituted at N-3 by a methyl or a 2-fluoroethyl group. FLT and ara-T are markedly inhibitory against human immunodeficiency virus type 1 (HIV-1) and HIV-2, and herpes simplex virus type 1 (HSV-1) and HSV-2, respectively. Modification at N-3 of these compounds markedly decreases both the antiviral and cytostatic activity of the parent compounds FLT and ara-T except for N-3-(methyl)-Thd that proved highly cytostatic for murine leukaemia L1210 cells. The decreased biological activity of the N-3-substituted pyrimidine nucleo-side analogues coincides with a significantly lower affinity of the modified Thd analogues for the cellular and viral (activating) nucleoside kinases.
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Affiliation(s)
- Jan Balzarini
- Rega Institute for Medical Research, K.U. Leuven, Leuven, Belgium.
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Leśnikowski ZJ. Challenges and Opportunities for the Application of Boron Clusters in Drug Design. J Med Chem 2016; 59:7738-58. [PMID: 27124656 DOI: 10.1021/acs.jmedchem.5b01932] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
There are two branches in boron medicinal chemistry: the first focuses on single boron atom compounds, and the second utilizes boron clusters. Boron clusters and their heteroatom counterparts belong to the family of cage compounds. A subset of this extensive class of compounds includes dicarbadodecaboranes, which have the general formula C2B10H12, and their metal biscarboranyl complexes, metallacarboranes, with the formula [M(C2B10H12)2(-2)]. The unique properties of boron clusters have resulted in their utilization in applications such as in pharmacophores, as scaffolds in molecular construction, and as modulators of bioactive compounds. This Perspective presents an overview of the properties of boron clusters that are pertinent for drug discovery, recent applications in the design of various classes of drugs, and the potential use of boron clusters in the construction of new pharmaceuticals.
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Affiliation(s)
- Zbigniew J Leśnikowski
- Institute of Medical Biology, Polish Academy of Sciences , Laboratory of Molecular Virology and Biological Chemistry, 106 Lodowa St., Lodz 93-232, Poland
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Evaluation of TK1 targeting carboranyl thymidine analogs as potential delivery agents for neutron capture therapy of brain tumors. Appl Radiat Isot 2015; 106:251-5. [PMID: 26282567 DOI: 10.1016/j.apradiso.2015.06.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 05/11/2015] [Accepted: 06/25/2015] [Indexed: 01/26/2023]
Abstract
In this report we describe studies with N5-2OH, a carboranyl thymidine analog (CTA), which is a substrate for thymidine kinase 1 (TK1), using the F98 rat glioma model. In vivo BNCT studies have demonstrated that intracerebral (i.c.) osmotic pump infusion of N5-2OH yielded survival data equivalent to those obtained with i.v. administration of boronophenylalanine (BPA). The combination of N5-2OH and BPA resulted in a modest increase in MST of F98 glioma bearing rats compared to a statistically significant increase with the RG2 glioma model, as has been previously reported by us (Barth et al., 2008). This had lead us to synthesize a second generation of CTAs that have improved in vitro enzyme kinetics and in vivo tumor uptake (Agarwal et al., 2015).
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Wojtczak BA, Olejniczak AB, Wang L, Eriksson S, Lesnikowski ZJ. Phosphorylation of nucleoside-metallacarborane and carborane conjugates by nucleoside kinases. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2014; 32:571-88. [PMID: 24124690 DOI: 10.1080/15257770.2013.838259] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A library of purine and pyrimidine nucleosides modified with carborane or metallacarborane boron clusters at different locations, consisting of new molecules as well as already described compounds, was prepared. The compounds were tested as substrates for human deoxynucleoside kinases. Some conjugates, with modification attached to N3 of thymidine via a linker containing the triazole moiety, were efficiently phosphorylated by cytosolic thymidine kinase 1 and mitochondrial thymidine kinase 2. Higher phosphorylation levels were observed with thymidine kinase 1, the phosphorylation of nucleosides modified with metallacarboranes was observed for the first time.
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Affiliation(s)
- Blazej A Wojtczak
- a Laboratory of Molecular Virology and Biological Chemistry, Institute of Medical Biology, Polish Academy of Sciences , Lodz , Poland
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Alauddin MM. Nucleoside-based probes for imaging tumor proliferation using positron emission tomography. J Labelled Comp Radiopharm 2013; 56:237-43. [PMID: 24285330 DOI: 10.1002/jlcr.3003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 07/03/2012] [Accepted: 11/06/2012] [Indexed: 02/03/2023]
Abstract
Cancer is one of the leading causes of human death, and early detection can be beneficial for its timely therapy and management. For the early detection of cancer, positron emission tomography (PET) is more accurate and sensitive than other imaging modalities, such as computed tomography and magnetic resonance imaging. [(18) F]-Labeled fluorodeoxyglucose is the most useful PET probe in early detection of cancer; however, its nonspecific accumulation and consequent false-positive findings warrant the identification of other PET probes. Thymidine (TdR) and its analogs have been radiolabeled for PET imaging of cellular proliferation and DNA synthesis. Because of its in vivo instability, radiolabeled TdR has not been successful in PET imaging. However, some of its radiolabeled analogs have been developed for PET imaging of cellular proliferation and DNA synthesis. In this review, the radiochemistry and production of (11) C-TdR and (11) C/(18) F-labeled TdR analogs published to date are presented.
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Affiliation(s)
- Mian M Alauddin
- Department of Experimental Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Agarwal HK, McElroy CA, Sjuvarsson E, Eriksson S, Darby MV, Tjarks W. Synthesis of N3-substituted carboranyl thymidine bioconjugates and their evaluation as substrates of recombinant human thymidine kinase 1. Eur J Med Chem 2012; 60:456-68. [PMID: 23318906 DOI: 10.1016/j.ejmech.2012.11.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 11/23/2012] [Accepted: 11/29/2012] [Indexed: 01/19/2023]
Abstract
Four different libraries of overall twenty three N3-substituted thymidine (dThd) analogues, including eleven 3-carboranyl thymidine analogues (3CTAs), were synthesized. The latter are potential agents for Boron Neutron Capture Therapy (BNCT) of cancer. Linker between the dThd scaffold and the m-carborane cluster at the N3-position of the 3CTAs contained amidinyl-(3e and 3f), guanidyl-(7e-7g), tetrazolylmethyl-(9b1/2-9d1/2), or tetrazolyl groups (11b1/2-11d1/2) to improve human thymidine kinase 1 (hTK1) substrate characteristics and water solubilities compared with 1st generation 3CTAs, such as N5 and N5-2OH. The amidinyl- and guanidyl-type N3-substitued dThd analogues (3a-3f and 7a-7g) had hTK1 phosphorylation rates of <30% relative to that of dThd, the endogenous hTK1 substrate, whereas the tetrazolyl-type N3-substitued dThd analogues (9a, 9b1/2-9d1/2 and 11a, 11b1/2-11d1/2) had relative phosphorylation rates (rPRs) of >40%. Compounds 9a, 9b1/2-9d1/2 and 11a, 11b1/2-11d1/2 were subjected to in-depth enzyme kinetics studies and the obtained rk(cat)/K(m) (k(cat)/K(m) relative to that of dThd) ranged from 2.5 to 26%. The tetrazolyl-type N3-substitued dThd analogues 9b1/2 and 11d1/2 were the best substrates of hTK1 with rPRs of 52.4% and 42.5% and rk(cat)/K(m) values of 14.9% and 19.7% respectively. In comparison, the rPR and rk(cat)/K(m) values of N5-2OH in this specific study were 41.5% and 10.8%, respectively. Compounds 3e and 3f were >1900 and >1500 times, respectively, better soluble in PBS (pH 7.4) than N5-2OH whereas solubilities for 9b1/2-9d1/2 and 11b1/2-11d1/2 were only 1.3-13 times better.
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Affiliation(s)
- Hitesh K Agarwal
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA.
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Smith G, Sala R, Carroll L, Behan K, Glaser M, Robins E, Nguyen QD, Aboagye EO. Synthesis and evaluation of nucleoside radiotracers for imaging proliferation. Nucl Med Biol 2012; 39:652-65. [PMID: 22321533 DOI: 10.1016/j.nucmedbio.2011.12.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 11/29/2011] [Accepted: 12/07/2011] [Indexed: 10/14/2022]
Abstract
INTRODUCTION Uncontrolled proliferation is a fundamental characteristic of cancer, and consequently, imaging of tumor proliferative status finds interest clinically both as a diagnostic tool and for evaluation of response to treatment. Positron emission tomography (PET) radiotracers based on a nucleoside core, such as 3'-[18F]fluoro-3'-deoxythymidine ([18F]FLT), have been extensively studied for this purpose. However, [18F]FLT suffers from poor DNA incorporation leading to occasional poor correlation of [18F]FLT tumor uptake with other proliferation indicators such as Ki-67 immunostaining. METHODS N3-((1-(2-[18F]fluoroethyl)-1H-[1,2,3]-triazol-4-yl)methyl)thymidine ([18F]2) and N3-((1-(2-[18F]fluoroethyl)-1H-[1,2,3]-triazol-4-yl)methyl)-4'-thio-β-thymidine ([18F]3) were synthesized by click chemistry from [18F]fluoroethyl azide and by direct nucleophilic substitution of a tosylate precursor. Metabolic stability and phosphorylation potential of the radiotracers were evaluated in vitro and compared to [18F]FLT. Further, metabolic stability and biodistribution analysis of [18F]2 and [18F]3 were evaluated in vivo. RESULTS Stable isotope standards and radiochemistry precursors were synthesized by modification of existing literature procedures. [18F]2 and [18F]3 were synthesized in a radiochemical yield of 8%-12% (end of synthesis, non-decay corrected). Both nucleosides were stable to metabolic degradation by thymidine phosphorylase, and in vivo stability analysis showed only one metabolite for [18F]3. No phosphorylation of [18F]2 could be detected in HCT116 cell homogenates, and in the same assay, only minor (∼8%) phosphorylation of [18F]3 was observed. Biodistribution in Balb/c mice indicated rapid clearance for [18F]2 and [18F]3 to a lesser extent. CONCLUSIONS The favorable biodistribution and metabolic profile of [18F]3 warrant further investigation as a next-generation PET proliferation marker.
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Affiliation(s)
- Graham Smith
- Comprehensive Cancer Imaging Centre, Faculty of Medicine, Imperial College London, Hammersmith Hospital, W12 0NN London, UK
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Calvaresi M, Zerbetto F. In Silico Carborane Docking to Proteins and Potential Drug Targets. J Chem Inf Model 2011; 51:1882-96. [DOI: 10.1021/ci200216z] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Matteo Calvaresi
- Dipartimento di Chimica “G. Ciamician”, Università di Bologna, V. F. Selmi 2, 40126 Bologna, Italy
| | - Francesco Zerbetto
- Dipartimento di Chimica “G. Ciamician”, Università di Bologna, V. F. Selmi 2, 40126 Bologna, Italy
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Skeletal myosin light chain kinase regulates skeletal myogenesis by phosphorylation of MEF2C. EMBO J 2011; 30:2477-89. [PMID: 21556048 DOI: 10.1038/emboj.2011.153] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 04/19/2011] [Indexed: 12/18/2022] Open
Abstract
The MEF2 factors regulate transcription during cardiac and skeletal myogenesis. MEF2 factors establish skeletal muscle commitment by amplifying and synergizing with MyoD. While phosphorylation is known to regulate MEF2 function, lineage-specific regulation is unknown. Here, we show that phosphorylation of MEF2C on T(80) by skeletal myosin light chain kinase (skMLCK) enhances skeletal and not cardiac myogenesis. A phosphorylation-deficient MEF2C mutant (MEFT80A) enhanced cardiac, but not skeletal myogenesis in P19 stem cells. Further, MEFT80A was deficient in recruitment of p300 to skeletal but not cardiac muscle promoters. In gain-of-function studies, skMLCK upregulated myogenic regulatory factor (MRF) expression, leading to enhanced skeletal myogenesis in P19 cells and more efficient myogenic conversion. In loss-of-function studies, MLCK was essential for efficient MRF expression and subsequent myogenesis in embryonic stem (ES) and P19 cells as well as for proper activation of quiescent satellite cells. Thus, skMLCK regulates MRF expression by controlling the MEF2C-dependent recruitment of histone acetyltransferases to skeletal muscle promoters. This work identifies the first kinase that regulates MyoD and Myf5 expression in ES or satellite cells.
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Struthers H, Viertl D, Kosinski M, Spingler B, Buchegger F, Schibli R. Charge dependent substrate activity of C3' and N3 functionalized, organometallic technetium and rhenium-labeled thymidine derivatives toward human thymidine kinase 1. Bioconjug Chem 2010; 21:622-34. [PMID: 20359195 DOI: 10.1021/bc900380n] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Human cytosolic thymidine kinase (hTK1) has proven to be a suitable target for the noninvasive imaging of cancer cell proliferation using radiolabeled thymidine analogues such as [(18)F]3'-fluoro-3'-deoxythymidine ([(18)F]FLT). A thymidine analogue for single photon emission computed tomography (SPECT), which incorporates the readily available and inexpensive nuclide technetium-99m, would be of considerable practical interest. hTK1 is known to accommodate modification of the structure of the natural substrate thymidine at the positions N3 and C3' and, to a lesser extent, C5. In this work, we used the copper-catalyzed azide-alkyne cycloaddition to synthesize two series of derivatives in which thymidine is functionalized at either the C3' or N3 position with chelating systems suitable for the M(CO)(3) core (M = (99m)Tc, Re). The click chemistry approach enabled complexes with different structures and overall charges to be synthesized from a common precursor. Using this strategy, the first organometallic hTK1 substrates in which thymidine is modified at the C3' position were identified. Phosphorylation of the organometallic derivatives was measured relative to thymidine. We have shown that the influence of the overall charge of the derivatives is dependent on the position of functionalization. In the case of the C3'-functionalized derivatives, neutral and anionic substrates were most readily phosphorylated (20-28% of the value for the parent ligand thymidine), whereas for the N3-functionalized derivatives, cationic and neutral complexes were apparently better substrates for the enzyme (14-18%) than anionic derivatives (9%).
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Affiliation(s)
- Harriet Struthers
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
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Alberto R, N’Dongo HP, Clericuzio M, Bonetti S, Gabano E, Cassino C, Ravera M, Osella D. Functionalized thymidine derivatives as carriers for the γ-emitter technetium tricarbonyl moiety. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2009.06.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Advances in computer software technology have led to enormous progress that has enabled increasing levels of complexity to be incorporated into radiotherapy treatment planning systems. Because of these changes, the delivery of radiotherapy evolved from therapy designed primarily on plain 2-dimensional X-ray images and hand calculations to therapy based on 3-dimensional images incorporating increasingly complex computer algorithms in the planning process. In addition, challenges in treatment planning and radiation delivery, such as problems with setup error and organ movement, have begun to be systematically addressed, ushering in an era of so-called 4-dimensional radiotherapy. This review article discusses how these advances have changed the way in which many common neoplasms of the central nervous system are being treated at present.
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Bartholomä MD, Ouellette W, Zubieta J. 1-(Phthalimidometh-yl)pyridinium p-toluene-sulfonate. Acta Crystallogr Sect E Struct Rep Online 2008; 65:o61. [PMID: 21581702 PMCID: PMC2967974 DOI: 10.1107/s1600536808038816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 11/19/2008] [Indexed: 11/13/2022]
Abstract
In the crystal of the title compound, C14H11N2O2+·C7H7O3S−, the cation and anion interact by way of an aromatic π–π interaction [centroid–centroid separation = 3.5783 (2) Å] and a T-stacking (C—H⋯π) interaction between cations. The dihedral angle between the aromatic rings in the cation is 61.73 (8)°. The ionic units are aligned in a zigzag fashion in the b-axis direction.
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Mukhopadhyay U, Soghomonyan S, Yeh HH, Flores LG, Shavrin A, Volgin AY, Gelovani JG, Alauddin MM. N(3)-Substituted thymidine analogues V: synthesis and preliminary PET imaging of N(3)-[(18)F]fluoroethyl thymidine and N(3)-[(18)F]fluoropropyl thymidine. Nucl Med Biol 2008; 35:697-705. [PMID: 18678355 DOI: 10.1016/j.nucmedbio.2008.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 03/18/2008] [Accepted: 03/25/2008] [Indexed: 10/21/2022]
Abstract
INTRODUCTION [(18)F]-Labeled analogues of thymidine have demonstrated efficacy for PET imaging of cellular proliferation. We have synthesized two [(18)F]-labeled N(3)-substituted thymidine analogues, N(3)-[(18)F]fluoroethyl thymidine (N(3)-[(18)F]-FET) and N(3)-[(18)F]fluoropropyl thymidine (N(3)-[(18)F]-FPrT), and performed preliminary PET imaging studies in tumor-bearing mice. METHODS Thymidine was converted to its 3',5'-O-bis-tetrahydropyranyl ether, which was then converted to the N(3)-ethyl and propyl-substituted mesylate precursors. Reactions of these mesylate precursors with n-Bu(4)N[(18)F] or K[(18)F]/kryptofix followed by acid hydrolysis and HPLC purification yielded N(3)-[(18)F]-FET and N(3)-[(18)F]-FPrT, respectively. Subcutaneous (sc) xenografts of H441 human non-small cell lung cancer were established in two groups of mice (each n=6). Micro-PET images of the tumor-bearing animals were acquired after intravenous injection of N(3)-[(18)F]-FET or N(3)-[(18)F]-FPrT (3700 KBq/animal). RESULTS The radiochemical yields were 2-12% (d.c.) for N(3)-[(18)F]-FET and 30-38% (d.c.) for N(3)-[(18)F]-FPrT. Radiochemical purity was >99% and calculated specific activity was >74 GBq/mumol at the end of synthesis. The accumulation of N(3)-[(18)F]-FET and N(3)-[(18)F]-FPrT in the tumor tissue at 2 h postinjection was 1.81+/-0.78 and 2.95+/-1.14 percent injected dose per gram (%ID/g), respectively; tumor/muscle ratios were 5.57+/-0.82 and 7.69+/-2.18, respectively; the unidirectional influx rates (K(i)) were 0.013 and 0.018 ml/g per minute, respectively. CONCLUSION Two novel [(18)F]- N(3)-substituted thymidine analogues have been synthesized in good yields, high purity and high specific activity. Preliminary in vivo studies demonstrated the efficacy of these [(18)F]- N(3)-substituted thymidine analogues for PET imaging of tumors.
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Affiliation(s)
- Uday Mukhopadhyay
- Department of Experimental Diagnostic Imaging, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Desbouis D, Struthers H, Spiwok V, Küster T, Schibli R. Synthesis, In Vitro, and In Silico Evaluation of Organometallic Technetium and Rhenium Thymidine Complexes with Retained Substrate Activity toward Human Thymidine Kinase Type 1. J Med Chem 2008; 51:6689-98. [PMID: 18837546 DOI: 10.1021/jm800530p] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Dominique Desbouis
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Center for Radiopharmaceutical Science, ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland, Department of Structure and Function of Saccharides, Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 84538 Bratislava, Slovak Republic
| | - Harriet Struthers
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Center for Radiopharmaceutical Science, ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland, Department of Structure and Function of Saccharides, Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 84538 Bratislava, Slovak Republic
| | - Vojtech Spiwok
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Center for Radiopharmaceutical Science, ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland, Department of Structure and Function of Saccharides, Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 84538 Bratislava, Slovak Republic
| | - Tatiana Küster
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Center for Radiopharmaceutical Science, ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland, Department of Structure and Function of Saccharides, Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 84538 Bratislava, Slovak Republic
| | - Roger Schibli
- Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland, Center for Radiopharmaceutical Science, ETH-PSI-USZ, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland, Department of Structure and Function of Saccharides, Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, 84538 Bratislava, Slovak Republic
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Boron neutron capture therapy for glioblastoma. Cancer Lett 2008; 262:143-52. [DOI: 10.1016/j.canlet.2008.01.021] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/11/2008] [Accepted: 01/14/2008] [Indexed: 11/23/2022]
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Celen S, de Groot T, Balzarini J, Vunckx K, Terwinghe C, Vermaelen P, Van Berckelaer L, Vanbilloen H, Nuyts J, Mortelmans L, Verbruggen A, Bormans G. Synthesis and evaluation of a 99mTc-MAMA-propyl-thymidine complex as a potential probe for in vivo visualization of tumor cell proliferation with SPECT. Nucl Med Biol 2007; 34:283-91. [PMID: 17383578 DOI: 10.1016/j.nucmedbio.2007.01.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2006] [Revised: 12/18/2006] [Accepted: 01/05/2007] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Cytosolic thymidine kinase (TK1) catalyzes phosphorylation of thymidine to its monophosphate. TK1 activity is closely related with DNA synthesis, and thymidine analogs derivatized with bulky carboranylalkyl groups at the N-3 position were reported to be good substrates for TK1. Accordingly, we have synthesized (99m)Tc-MAMA-propyl-thymidine and evaluated it as a potential tumor tracer. METHODS The bis(S-trityl)-protected MAMA-propyl-thymidine precursor (3-N-[S-trityl-2-mercaptoethyl]-N-[N'-(S-trityl-2-mercaptoethyl)amidoacetyl]-aminopropyl-thymidine) was prepared in three steps, and its structure was confirmed with (1)H NMR and mass spectrometry. Deprotection of the thiols and labeling with (99m)Tc were done in a two-step, one-pot procedure, yielding (99m)Tc-MAMA-propyl-thymidine, which was analyzed with high-performance liquid chromatography, radio-LC-MS analysis (ESI+) and electrophoresis, and its log P was determined. The biodistribution in normal mice was evaluated, and its biodistribution in a radiation-induced fibrosarcoma (RIF) tumor mouse was compared with that of 3'-deoxy-3'-[(18)F] fluorothymidine [(18)F]FLT. RESULTS (99m)Tc-MAMA-propyl-thymidine was obtained with a radiochemical yield of 70%. Electrophoresis indicated that the complex is uncharged, and its log P was 1.0. The molecular ion mass of the Tc complex was 589 Da, which is compatible with the hypothesized N(2)S(2)-oxotechnetium structure. Tissue distribution showed fast clearance from plasma primarily by the hepatobiliary pathway. Whole-body planar imaging after injection of (99m)Tc-MAMA-propyl-thymidine in an RIF tumor-bearing mouse showed high uptake in the liver and the intestines. No uptake was observed in the tumor, in contrast to the clear uptake observed for [(18)F] FLT visualized with muPET. CONCLUSIONS Although it has been reported that TK1 accepts large substituents at the N-3 position of the thymine ring, the results of this study show that (99m)Tc-MAMA-propyl-thymidine cannot be used as a single photon emission computed tomography tumor tracer, probably because the (99m)Tc-MAMA ligand is too bulky to be tolerated by TK1.
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Affiliation(s)
- Sofie Celen
- Laboratory for Radiopharmacy, K.U. Leuven, B-3000 Leuven, Belgium
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Tjarks W, Tiwari R, Byun Y, Narayanasamy S, Barth RF. Carboranyl thymidine analogues for neutron capture therapy. Chem Commun (Camb) 2007:4978-91. [DOI: 10.1039/b707257k] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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23
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Ghosh P, Gelovani JG, Alauddin MM. N3-Substituted thymidine analogues III: radiosynthesis of N3-[(4-[18F]fluoromethyl-phenyl)butyl]thymidine ([18F]-FMPBT) and N3-[(4-[18F]fluoromethyl-phenyl)pentyl] thymidine ([18F]-FMPPT) for PET. J Labelled Comp Radiopharm 2007. [DOI: 10.1002/jlcr.1425] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Thirumamagal BTS, Johnsamuel J, Cosquer GY, Byun Y, Yan J, Narayanasamy S, Tjarks W, Barth RF, Al-Madhoun AS, Eriksson S. Boronated thymidine analogues for boron neutron capture therapy. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2006; 25:861-6. [PMID: 16901817 DOI: 10.1080/15257770600793844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Concise synthetic methods for synthesizing 3-carboranyl thymidine analogues (3CTAs) modified with cyclic and acyclic alcohols have been developed. The synthesis of these potential boron neutron capture therapy (BNCT) agents and their preliminary biological evaluation is described.
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Affiliation(s)
- B T S Thirumamagal
- College of Pharmacy, The Ohio State University, Columbus, Ohio 43120, USA
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25
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Bandyopadhyaya AK, Tiwari R, Tjarks W. Comparative molecular field analysis and comparative molecular similarity indices analysis of boron-containing human thymidine kinase 1 substrates. Bioorg Med Chem 2006; 14:6924-32. [PMID: 16828556 DOI: 10.1016/j.bmc.2006.06.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Revised: 06/14/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
Three-dimensional quantitative structure-activity relationship (3D-QSAR) using CoMFA and CoMSIA techniques was applied to evaluate 56 pyrimidine nucleosides as substrates of human thymidine kinase 1 (hTK1), 27 of them containing a carborane substituent either at the 3-, 5-, or 3'-position of the 2'-deoxyuridine scaffold. This is the first report describing 3D-QSAR studies of compounds containing boron atoms. Both CoMFA and CoMSIA models were derived from a training set of 47 molecules and the predictive capacity of the CoMSIA model was successfully validated by accurately calculating known phosphorylation rates of both boronated and non-boron hTK1 substrates that were not included in the training set. The optimal CoMSIA model provided the following values: q(2) 0.622, r(2) 0.983, s 0.165, and F 187.5. Contour maps obtained from the CoMSIA model were in agreement with the experimentally determined biological data.
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Affiliation(s)
- Achintya K Bandyopadhyaya
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA.
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Toyohara J, Hayashi A, Gogami A, Hamada M, Hamashima Y, Katoh T, Node M, Fujibayashi Y. Alkyl-fluorinated thymidine derivatives for imaging cell proliferation. Nucl Med Biol 2006; 33:751-64. [PMID: 16934694 DOI: 10.1016/j.nucmedbio.2006.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 06/16/2006] [Accepted: 06/19/2006] [Indexed: 10/24/2022]
Abstract
Derivatives of 2'-deoxyuridine that contain fluoroalkyl groups at the C5 position and derivatives of thymidine that contain fluoroalkyl groups at the N3 position were synthesized and examined in three in vitro assays designed to evaluate their potential as radiopharmaceuticals for imaging cellular proliferation. Three of the former nucleosides and five of the latter were synthesized. The three assays were as follows: (a) phosphoryl transfer assay, which showed that all three of the former nucleosides and four of the latter ones were phosphorylated by recombinant human thymidine kinase 1 (TK1) and that N(3)-(2-fluoroethyl)-thymidine (NFT202) was the most potent substrate of the eight nucleosides studied; (b) transport assay, which indicated that all eight nucleosides had good affinity for an 6-[(4-nitrobenzyl)thio]-9-beta-d-ribofuranosylpurine-sensitive mouse erythrocyte nucleoside transporter, with inhibition constants in the range of 0.02-0.55 mM; and (c) degradation assay, which showed that all but one of the former nucleosides and none of the latter were degraded by recombinant Escherichia coli thymidine phosphorylase (an enzyme that catalyzes the glycosidic bond of thymidine and 2'-deoxyuridine derivatives). From these in vitro screening assays, we selected NFT202 as a candidate for subsequent in vivo evaluation because this compound met the three minimum requirements of the in vitro screening assays and had the most potent phosphorylation activity as a substrate for recombinant human TK1.
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Affiliation(s)
- Jun Toyohara
- Probe Research Section, Department of Molecular Probe, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
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Aspland SE, Ballatore C, Castillo R, Desharnais J, Eustaquio T, Goelet P, Guo Z, Li Q, Nelson D, Sun C, Castellino AJ, Newman MJ. Kinase-mediated trapping of bi-functional conjugates of paclitaxel or vinblastine with thymidine in cancer cells. Bioorg Med Chem Lett 2006; 16:5194-8. [PMID: 16870428 DOI: 10.1016/j.bmcl.2006.07.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 07/03/2006] [Accepted: 07/05/2006] [Indexed: 11/20/2022]
Abstract
In the present work, we explore the possibility of introducing selectivity to existing chemotherapeutics via the design of non-pro-drug, bi-functional molecules comprising a microtubule-binding agent and a substrate for a disease-associated kinase. The design, synthesis, and in vitro biological evaluation of paclitaxel-thymidine and vinblastine-thymidine bi-functional conjugates are reported here. This work provides the first account of 'kinase-mediated trapping' of cancer therapeutics.
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Affiliation(s)
- Simon E Aspland
- Acidophil LLC, 2330 W. Joppa Road, Suite 330, Lutherville, MD 21093, USA.
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Narayanasamy S, Thirumamagal BTS, Johnsamuel J, Byun Y, Al-Madhoun AS, Usova E, Cosquer GY, Yan J, Bandyopadhyaya AK, Tiwari R, Eriksson S, Tjarks W. Hydrophilically enhanced 3-carboranyl thymidine analogues (3CTAs) for boron neutron capture therapy (BNCT) of cancer. Bioorg Med Chem 2006; 14:6886-99. [PMID: 16831554 DOI: 10.1016/j.bmc.2006.06.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 06/16/2006] [Accepted: 06/19/2006] [Indexed: 11/30/2022]
Abstract
Five novel 3-carboranyl thymidine analogues (3CTAs) were designed and synthesized for boron neutron capture therapy (BNCT) of cancer. Phosphorylation of all five 3CTAs was catalyzed by recombinant human thymidine kinase (hTK1) using adenosine triphosphate (ATP) as the phosphate donor. The obtained phosphorylation rates ranged from 4% to 64.5% relative to that of thymidine. The compound with the most favorable hTK1 binding properties had a k(cat)/K(M) value of 57.4% relative to that of thymidine and an IC(50) of inhibition of thymidine phosphorylation by hTK1 of 92 microM. Among the five synthesized 3CTAs, this agent had also the overall most favorable physicochemical properties. Therefore, it may have the potential to replace N5-2OH, the current lead 3CTA, in preclinical studies. An in silico model for the binding of this compound to hTK1 was developed.
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Alauddin MM, Ghosh P, Gelovani JG. Synthesis of [18F]-labeled N-3(substituted) thymidine analogues: N-3([18F]fluorobutyl) thymidine ([18F]-FBT) and N-3([18F]fluoropentyl) thymidine ([18F]-FPT) for PET. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.1127] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Barth RF, Coderre JA, Vicente MGH, Blue TE. Boron neutron capture therapy of cancer: current status and future prospects. Clin Cancer Res 2005; 11:3987-4002. [PMID: 15930333 DOI: 10.1158/1078-0432.ccr-05-0035] [Citation(s) in RCA: 655] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10 is irradiated with low-energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Clinical interest in BNCT has focused primarily on the treatment of high-grade gliomas and either cutaneous primaries or cerebral metastases of melanoma, most recently, head and neck and liver cancer. Neutron sources for BNCT currently are limited to nuclear reactors and these are available in the United States, Japan, several European countries, and Argentina. Accelerators also can be used to produce epithermal neutrons and these are being developed in several countries, but none are currently being used for BNCT. BORON DELIVERY AGENTS Two boron drugs have been used clinically, sodium borocaptate (Na(2)B(12)H(11)SH) and a dihydroxyboryl derivative of phenylalanine called boronophenylalanine. The major challenge in the development of boron delivery agents has been the requirement for selective tumor targeting to achieve boron concentrations ( approximately 20 microg/g tumor) sufficient to deliver therapeutic doses of radiation to the tumor with minimal normal tissue toxicity. Over the past 20 years, other classes of boron-containing compounds have been designed and synthesized that include boron-containing amino acids, biochemical precursors of nucleic acids, DNA-binding molecules, and porphyrin derivatives. High molecular weight delivery agents include monoclonal antibodies and their fragments, which can recognize a tumor-associated epitope, such as epidermal growth factor, and liposomes. However, it is unlikely that any single agent will target all or even most of the tumor cells, and most likely, combinations of agents will be required and their delivery will have to be optimized. CLINICAL TRIALS Current or recently completed clinical trials have been carried out in Japan, Europe, and the United States. The vast majority of patients have had high-grade gliomas. Treatment has consisted first of "debulking" surgery to remove as much of the tumor as possible, followed by BNCT at varying times after surgery. Sodium borocaptate and boronophenylalanine administered i.v. have been used as the boron delivery agents. The best survival data from these studies are at least comparable with those obtained by current standard therapy for glioblastoma multiforme, and the safety of the procedure has been established. CONCLUSIONS Critical issues that must be addressed include the need for more selective and effective boron delivery agents, the development of methods to provide semiquantitative estimates of tumor boron content before treatment, improvements in clinical implementation of BNCT, and a need for randomized clinical trials with an unequivocal demonstration of therapeutic efficacy. If these issues are adequately addressed, then BNCT could move forward as a treatment modality.
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Affiliation(s)
- Rolf F Barth
- Department of Pathology, The Ohio State University, Columbus, Ohio 43210, USA.
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Leśnikowski ZJ, Paradowska E, Olejniczak AB, Studzińska M, Seekamp P, Schüssler U, Gabel D, Schinazi RF, Plesek J. Towards new boron carriers for boron neutron capture therapy: metallacarboranes and their nucleoside conjugates. Bioorg Med Chem 2005; 13:4168-75. [PMID: 15878666 DOI: 10.1016/j.bmc.2005.04.042] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2004] [Accepted: 04/15/2005] [Indexed: 11/17/2022]
Abstract
Thymidine conjugates containing metallacarborane, {8-[5-(N(3)-thymidine)-3-oxa-pentoxy]-3-cobalt bis(1,2-dicarbollide)}- (5) and {8-[5-(O(4)-thymidine)-3-oxa-pentoxy]-3-cobalt bis(1,2-dicarbollide)}- (6) ions and several simple [3-cobalt bis(1,2-dicarbollide)]- ion (1) derivatives have been studied as potential boron carriers for BNCT. Compound 6 and some nonnucleoside derivatives of 1 were not toxic above 100 microM. The partition coefficient for both metallacarborane bearing thymidine conjugates 5 and 6 was more than 500 times higher than that of unmodified nucleoside. The cellular uptake studies showed accumulation of compounds 6 in V79 Chinese hamster cells but not of compound 5. The low toxicity of conjugate type of 6 together with its high partition coefficient suggest that judicially designed derivatives of metallacarboranes can be considered as potential boron carriers for BNCT.
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Affiliation(s)
- Zbigniew J Leśnikowski
- Center of Medical Biology, Laboratory of Molecular Virology and Biological Chemistry, Polish Academy of Sciences, 106 Lodowa Street, Lodz 93-232, Poland
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Al-Madhoun AS, Eriksson S, Wang ZX, Naimi E, Knaus EE, Wiebe LI. Phosphorylation of isocarbostyril- and difluorophenyl-nucleoside thymidine mimics by the human deoxynucleoside kinases. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2005; 23:1865-74. [PMID: 15628745 DOI: 10.1081/ncn-200040634] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The thymidine mimics isocarbostyril nucleosides and difluorophenyl nucleosides were tested as deoxynucleoside kinase substrates using recombinant human cytosolic thymidine kinase (TK1) and deoxycytidine kinase (dCK), and mitochondrial thymidine kinase (TK2) and deoxyguanosine kinase (dGK). The isocarbostyril nucleoside compound 1-(2-deoxy-beta-D-ribofuranosyl)-isocarbostyril (EN1) was a poor substrate with all the enzymes. The phosphorylation rates of EN1 with TK1 and TK2 were <1% relative to Thd, where as the phosphorylation rates for EN1 were 1.4% and 1.1% with dCK and dGK relative to dCyd and dGuo, respectively. The analogue 1-(2-deoxy-beta-D-ribofuranosyl)-7-iodoisocarbostyril (EN2) showed poor relative-phosphorylation efficiencies (kcat/Km) with both TK1 and dGK, but not with TK2. The kcat/Km value for EN2 with TK2 was 12.6% relative to that for Thd. Of the difluorophenyl nucleosides, 5-(1'-(2'-deoxy-beta-D-ribofuranosyl))-2,4-difluorotoluene (JW1) and 1-(1'-(2'-deoxy-beta-D-ribofuranosyl))-2,4-difluoro-5-iodobenzene (JW2) were substrates for TK1 with phosphorylation efficiencies of about 5% relative to that for Thd. Both analogues were considerably more efficient substrates for TK2, with kcat/Km values of 45% relative to that for Thd. 2,5-Difluoro-4-[1-(2-deoxy-beta-L-ribofuranosyl)]-aniline (JW5), a L-nucleoside mimic, was phosphorylated up to 15% as efficiently as deoxycytidine by dCK. These data provide a possible explanation for the previously reported lack of cytotoxicity of the isocarbostyril- and difluorophenyl nucleosides, but potential mitochondrial effects of EN2, JW1 and JW2 should be further investigated.
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Affiliation(s)
- Ashraf Said Al-Madhoun
- Division of Cardiology, Vascular Biology Laboratory, University of Ottawa Heart Institute, Ottawa, Canada
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Byun Y, Yan J, Al-Madhoun AS, Johnsamuel J, Yang W, Barth RF, Eriksson S, Tjarks W. Synthesis and Biological Evaluation of Neutral and Zwitterionic 3-Carboranyl Thymidine Analogues for Boron Neutron Capture Therapy. J Med Chem 2005; 48:1188-98. [PMID: 15715485 DOI: 10.1021/jm0491896] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Novel 3-carboranyl thymidine analogues (3CTAs) were synthesized as potential boron delivery agents for boron neutron capture therapy (BNCT). This library includes six zwitterionic NH(3)(+)-nido-m-carborane-substituted thymidine analogues (Thds) and the corresponding neutral NH(2)-closo-m-carborane-substituted counterparts. All compounds of this library were good substrates for recombinant human thymidine kinase 1 (TK1) with phosphorylation rates up to 89% relative to that of Thd. One compound out of this library, 3-[3-(7-NH(3)(+)-nido-m-carboran-1-yl)propan-1-yl]thymidine (19b), showed selective retention in TK1-expressing murine L929 wild-type tumors versus L929 TK1 (-) tumors in biodistribution studies. The biological evaluation of the zwitterionic NH(3)(+)-nido-m-carborane-substituted Thds indicated improved aqueous solubility and similar or even superior potential as BNCT agents compared with different classes of 3CTAs (Cancer Res. 2004, 64, 6280-6286 and 6287-6295). To complete previous structure-activity relationship (SAR) studies, 3-[(closo-o-carboranyl)methyl]thymidine (4) was also synthesized and evaluated.
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Affiliation(s)
- Youngjoo Byun
- Division of Medicinal Chemistry & Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio 43210, USA
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Welin M, Kosinska U, Mikkelsen NE, Carnrot C, Zhu C, Wang L, Eriksson S, Munch-Petersen B, Eklund H. Structures of thymidine kinase 1 of human and mycoplasmic origin. Proc Natl Acad Sci U S A 2004; 101:17970-5. [PMID: 15611477 PMCID: PMC539776 DOI: 10.1073/pnas.0406332102] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Indexed: 11/18/2022] Open
Abstract
Cytosolic thymidine kinase 1, TK1, is a well known cell-cycle-regulated enzyme of importance in nucleotide metabolism as well as an activator of antiviral and anticancer drugs such as 3'-azido-3'-deoxythymidine (AZT). We have now determined the structures of the TK1 family, the human and Ureaplasma urealyticum enzymes, in complex with the feedback inhibitor dTTP. The TK1s have a tetrameric structure in which each subunit contains an alpha/beta-domain that is similar to ATPase domains of members of the RecA structural family and a domain containing a structural zinc. The zinc ion connects beta-structures at the root of a beta-ribbon that forms a stem that widens to a lasso-type loop. The thymidine of dTTP is hydrogen-bonded to main-chain atoms predominantly coming from the lasso loop. This binding is in contrast to other deoxyribonucleoside kinases where specific interactions occur with side chains. The TK1 structure differs fundamentally from the structures of the other deoxyribonucleoside kinases, indicating a different evolutionary origin.
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Affiliation(s)
- Martin Welin
- Department of Molecular Biology, Swedish University of Agricultural Sciences, S-751 24 Uppsala, Sweden
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Byun Y, Yan J, Al-Madhoun ASAS, Johnsamuel J, Yang W, Barth RFRF, Eriksson S, Tjarks W. The synthesis and biochemical evaluation of thymidine analogues substituted with nido carborane at the N-3 position. Appl Radiat Isot 2004; 61:1125-30. [PMID: 15308203 DOI: 10.1016/j.apradiso.2004.05.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Several thymidine analogues substituted with closo- and nido-carborane at the N-3 position were synthesized. The nido-carboranyl thymidine analogues were designed to be effective substrates for human thymidine kinase 1 in combination with an increased water solubility sufficient for clinical application in boron neutron capture therapy. This was done because N-3 substituted closo-carboranyl thymidine analogues previously synthesized in our laboratories were good TK1 substrates but were poorly water-soluble. Newly synthesized zwitterionic amino nido- and the corresponding neutral closo-m-carboranyl thymidine analogues exhibited excellent TK1 phosphorylation rates up to 75% relative to thymidine, indicating that these compounds were good substrates for thymidine kinase 1. Thin layer chromatographic studies were indicative of increased hydrophilicity of the synthesized nido-carboranyl thymidine analogues compared with their closo-carboranyl counterparts and previously reported closo-carboranyl thymidine analogues.
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Affiliation(s)
- Youngjoo Byun
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, 422, Parks Hall, 500, West 12th Avenue, The Ohio State University, Columbus, OH 43210, USA
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Binello E, Mitchell RN, Harling OK. T cell uptake for the use of boron neutron capture as an immunologic research tool. Appl Radiat Isot 2004; 61:959-62. [PMID: 15308175 DOI: 10.1016/j.apradiso.2004.05.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
An immunologic tool based on manipulation of the boron neutron capture reaction was previously proposed in the context of heart transplantation research to examine the temporal relationship between parenchymal rejection (representing immune cell infiltration) and transplantation-associated arteriosclerosis (characterized by progressive vascular occlusion). Critical to the development of this method is the uptake of boron by specific cells of the immune system, namely T cells, without adverse effects on cell function, which may be assessed by the ability of boron-loaded cells to produce IFNgamma, a protein with substantial impact on rejection. This work presents the evaluation of two carboranyl thymidine analogs. Advantages of this type of boron compound are reduced risk of leakage and effective dose delivery based on their incorporation into cellular nuclear material. Results indicate that uptake of these boronated nucleosides is high with no adverse effects on cell function, thereby warranting the continued development of this technique that has potentially wide applicability in immunological models.
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Affiliation(s)
- E Binello
- Harvard-MIT Division of Health Sciences & Technology, Cambridge/Boston, MA, USA.
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Johnsamuel J, Lakhi N, Al-Madhoun AS, Byun Y, Yan J, Eriksson S, Tjarks W. Synthesis of ethyleneoxide modified 3-carboranyl thymidine analogues and evaluation of their biochemical, physicochemical, and structural properties. Bioorg Med Chem 2004; 12:4769-81. [PMID: 15336255 DOI: 10.1016/j.bmc.2004.07.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2004] [Revised: 07/08/2004] [Accepted: 07/16/2004] [Indexed: 11/21/2022]
Abstract
Eleven 3-carboranyl thymidine analogues (3CTAs) containing highly hydrophilic and flexible ethyleneoxide moieties were synthesized as potential agents for boron neutron capture therapy (BNCT) and their biochemical and physicochemical properties were evaluated. Based on specific structural features, this library of 3CTAs was divided into three subgroups. The first group contained 3CTAs with 1-4 ethyleneoxide units between the thymidine (Thd) scaffold and a carborane cluster. The second group of 3CTAs contained a pentylene spacer between Thd and the carborane and 2-4 ethyleneoxide units additionally attached to the carborane cluster. The third group contained three 3CTAs all with pentylene spacers and four ethylene units but with different carborane cages. The ethyleneoxide modified 3CTAs were good substrates of thymidine kinase 1 (TK1) and poor substrates of human mitochondrial thymidine kinase 2 (TK2) as determined in phosphoryl transfer assays. In the first group of 3CTAs, all the compounds were efficiently phosphorylated regardless of varying spacer lengths (37-42% of the activity of Thd). The second group of 3CTAs was less effectively phosphorylated (17-26% of the activity of Thd) probably due to a less favorable sterical orientation of Thd within the active site of TK1 and/or an increased lipophilicity compared with the first group. In the third group of structural isomers, no significant differences in phosphorylation rates were observed (17-25%). A structure-function hypothesis explaining these results is presented.
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Barth RF, Yang W, Al-Madhoun AS, Johnsamuel J, Byun Y, Chandra S, Smith DR, Tjarks W, Eriksson S. Boron-Containing Nucleosides as Potential Delivery Agents for Neutron Capture Therapy of Brain Tumors. Cancer Res 2004; 64:6287-95. [PMID: 15342417 DOI: 10.1158/0008-5472.can-04-0437] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The purpose of the present study was to evaluate both in vitro and in vivo a series of boron-containing nucleosides that potentially could be used as delivery agents for neutron capture therapy. The rationale for their synthesis was based on the fact that proliferating neoplastic cells have increased requirements for nucleic acid precursors, and, therefore, they should preferentially localize in the tumor. A series of 3-carboranlyalkyl thymidine analogs has been synthesized and a subset, designated N4, N5, and N7, and the corresponding 3-dihydroxypropyl derivatives, designated N4-2OH, N5-2OH, and N7-2OH, have been selected for evaluation. Using these compounds as substrates for recombinant human thymidine kinase-1 and the mitochondrial isoenzyme thymidine kinase-2, the highest phosphorylation levels relative to thymidine were seen with N5 and the corresponding dihydroxypropyl analog N5-2OH. In contrast, N4, N4-OH, N7, and N7-OH had substantially lower phosphorylation levels. To compare compounds with high and low thymidine kinase-1 substrate activity, N5 and N7 and the corresponding dihydroxypropyl derivatives were selected for evaluation of their cellular toxicity, uptake and retention by the F98 rat glioma, human MRA melanoma, and murine L929 cell lines, all of which are thymidine kinase-1(+), and a mutant L929 cell line that is thymidine kinase-1(-). N5-2OH was the least toxic (IC50, 43-70 microm), and N7 and N7-2OH were the most toxic (IC50, 18-49 microm). The highest boron uptake was seen with N7-2OH by the MRA 27 melanoma and L929 wild-type (wt) cell lines. The highest retention was seen with L929 (wt) cells, and this ranged from 29% for N5-2OH to 46% for N7. Based on the in vitro toxicity and uptake data, N5-2OH was selected for in vivo biodistribution studies either in rats bearing intracerebral implants of the F98 glioma or in mice bearing either s.c. or intracerebral implants of L929 (wt) tumors. At 2.5 hours after convection-enhanced delivery, the boron values for the F98 glioma and normal brain were 16.2 +/- 2.3 and 2.2 microg/g, respectively, and the tumor to brain ratio was 8.5. Boron values at 4 hours after convection-enhanced delivery of N5-2OH to mice bearing intracerebral implants of L929 (wt) or L929 thymidine kinase-1(-) tumors were 39.8 +/- 10.8 and 12.4 +/- 1.6 microg/g, respectively, and the corresponding normal brain values were 4.4 and 1.6 microg/g, thereby indicating that there was selective retention by the thymidine kinase-1(+) tumors. Based on these favorable in vitro and in vivo data, neutron capture therapy studies will be initiated using N5-2OH in combination with two non-cell cycle dependent boron delivery agents, boronophenylalanine and sodium borocaptate.
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Affiliation(s)
- Rolf F Barth
- Department of Pathology, The Ohio State University, Columbus, Ohio 43210, USA.
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Al-Madhoun AS, Johnsamuel J, Barth RF, Tjarks W, Eriksson S. Evaluation of Human Thymidine Kinase 1 Substrates as New Candidates for Boron Neutron Capture Therapy. Cancer Res 2004; 64:6280-6. [PMID: 15342416 DOI: 10.1158/0008-5472.can-04-0197] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Thymidine analogs containing o-carboranylalkyl groups at the 3-position were screened as potential substrates for human thymidine kinase 1 (TK1), an enzyme that is selectively expressed in a variety of rapidly proliferating cells, including tumor cells. On the basis of previous studies, 12 of these were identified as potential delivery agents for boron neutron capture therapy, a therapeutic method used for the treatment of high-grade brain tumors. Compound 4 with a pentylene spacer between the o-carborane cage and the thymidine scaffold and compound 10, which has an additional dihydroxypropyl substituent at the o-carborane cage, were the best substrates for TK1 with kcat/Km values of 27% and 36% relative to that of thymidine, respectively. These compounds showed partial competitive inhibition for thymidine phosphorylation by TK1. Neither compound was a substrate of recombinant human thymidine phosphorylase nor were their respective 5'-monophosphates substrates of 5'-deoxynucleotidase 1, thereby indicating potential in vivo stability. The octanol/water partition coefficient for compound 10 was 2.09, suggesting that it has excellent physiochemical properties for crossing the blood brain barrier and penetrating brain tissue. The in vitro cytotoxic effect of the 12 analogs was moderate to low in mammalian cell cultures with IC50 values between 10 and 160 micromol/L. Compounds 4 and 10 were taken up selectively and retained by the murine fibroblast L929 cell line, in contrast to its TK1-deficient variant. These findings suggest that compound 10 is a promising candidate for selective delivery of boron-10 to malignant cells, and additional in vivo studies are planned to evaluate it for boron neutron capture therapy of brain tumors.
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Affiliation(s)
- Ashraf S Al-Madhoun
- Department of Molecular Biosciences, Division of Veterinary Medical Biochemistry, Swedish University of Agricultural Sciences, Biomedical Center, Uppsala, Sweden.
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Johnsamuel J, Byun Y, Jones TP, Endo Y, Tjarks W. A new strategy for molecular modeling and receptor-based design of carborane containing compounds. J Organomet Chem 2003. [DOI: 10.1016/s0022-328x(03)00389-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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