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Halder R, Ma G, Rickmeier J, McDaniel JW, Petzold R, Neumann CN, Murphy JM, Ritter T. Deoxyfluorination of phenols for chemoselective 18F-labeling of peptides. Nat Protoc 2023; 18:3614-3651. [PMID: 37853158 DOI: 10.1038/s41596-023-00890-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 07/14/2023] [Indexed: 10/20/2023]
Abstract
The challenge of forming C-18F bonds is often a bottleneck in the development of new 18F-labeled tracer molecules for noninvasive functional imaging studies using positron emission tomography (PET). Nucleophilic aromatic substitution is the most widely employed reaction to functionalize aromatic substrates with the radioactive fluorine-18 but its scope is restricted to arenes containing electron-withdrawing substituents. Furthermore, many protic functional groups are incompatible with basic fluoride anions. Peptide substrates, which are highly desirable targets for PET molecular imaging, are particularly challenging to label with fluorine-18 because they are densely functionalized and sensitive to high temperatures and basic conditions. To expand the utility of nucleophilic aromatic substitution with fluorine-18, we describe two complementary procedures for the radiodeoxyfluorination of bench-stable and easy-to-access phenols that ensure rapid access to densely functionalized electron-rich and electron-poor 18F-aryl fluorides. The first procedure details the synthesis of an 18F-synthon and its subsequent ligation to the cysteine residue of Arg-Gly-Asp-Cys in 10.5 h from commercially available starting materials (189-min radiosynthesis). The second procedure describes the incorporation of commercially available CpRu(Fmoc-tyrosine)OTf into a fully protected peptide Lys-Met-Glu-(CpRu-Tyr)-Leu via solid-phase peptide synthesis and subsequent ruthenium-mediated uronium deoxyfluorination with fluorine-18 followed by deprotection, accomplished within 7 d (116-min radiosynthesis). Both radiolabeling methods are highly chemoselective and have conveniently been automated using commercially available radiosynthesis equipment so that the procedures described can be employed for the synthesis of peptide-based PET probes for in vivo imaging studies according to as low as reasonably achievable (ALARA) principles.
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Affiliation(s)
- Riya Halder
- Department of Organic Synthesis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
- Institute of Organic Chemistry, RWTH Aachen University, Aachen, Germany
| | - Gaoyuan Ma
- Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Strateos Inc., San Diego, CA, USA
| | - Jens Rickmeier
- Department of Organic Synthesis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - James W McDaniel
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Roland Petzold
- Department of Organic Synthesis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
| | - Constanze N Neumann
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
| | - Jennifer M Murphy
- Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
| | - Tobias Ritter
- Department of Organic Synthesis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany.
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Ma G, McDaniel JW, Murphy JM. One-Step Synthesis of [ 18F]Fluoro-4-(vinylsulfonyl)benzene: A Thiol Reactive Synthon for Selective Radiofluorination of Peptides. Org Lett 2021; 23:530-534. [PMID: 33373261 DOI: 10.1021/acs.orglett.0c04054] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Radiolabeled peptide-based molecular imaging probes exploit the advantages of large biologics and small molecules, providing both exquisite selectivity and favorable pharmacokinetic properties. Here, we report an operationally simple and broadly applicable approach for the 18F-fluorination of unprotected peptides via a new radiosynthon, [18F]fluoro-4-(vinylsulfonyl)benzene. This reagent demonstrates excellent chemoselectivity at the cysteine residue and rapid 18F-labeling of a diverse scope of peptides to generate stable thioether constructs.
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Affiliation(s)
- Gaoyuan Ma
- Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, United States
| | - James W McDaniel
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, United States
| | - Jennifer M Murphy
- Department of Molecular and Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California 90095, United States
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Choi JH, Oh D, Kim IS, Kim HS, Kim M, Kim EM, Lim ST, Sohn MH, Kim DH, Jeong HJ. Light-Triggered Radiochemical Synthesis: A Novel 18F-Labelling Strategy Using Photoinducible Click Reaction to Prepare PET Imaging Probes. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:4617493. [PMID: 30046295 PMCID: PMC6036826 DOI: 10.1155/2018/4617493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 04/25/2018] [Accepted: 05/07/2018] [Indexed: 11/29/2022]
Abstract
Novel probe development for positron emission tomography (PET) is leading to expanding the scope of molecular imaging. To begin responding to challenges, several biomaterials such as natural products and small molecules, peptides, engineered proteins including affibodies, and antibodies have been used in the development of targeted molecular imaging probes. To prepare radiotracers, a few bioactive materials are unique challenges to radiolabelling because of their complex structure, poor stability, poor solubility in aqueous or chemical organic solutions, and sensitivity to temperature and nonphysiological pH. To overcome these challenges, we developed a new radiolabelling strategy based on photoactivated 1,3-dipolar cycloaddition between alkene dipolarophile and tetrazole moiety containing compounds. Herein, we describe a light-triggered radiochemical synthesis via photoactivated click reaction to prepare 18F-radiolabelled PET tracers using small molecular and RGD peptide.
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Affiliation(s)
- Ji Hae Choi
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Doori Oh
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - In Sun Kim
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Hyeon-Soo Kim
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Minjoo Kim
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Eun-Mi Kim
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Seok Tae Lim
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Myung-Hee Sohn
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Dong Hyun Kim
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Kaibiotech, 20 Geonji-ro, Deokjin-gu, Jeonju, Jeollabuk-do 54896, Republic of Korea
| | - Hwan-Jeong Jeong
- Department of Nuclear Medicine, Molecular Imaging and Therapeutic Medicine Research Center, Chonbuk National University Medical School and Hospital, Jeonju, Jeollabuk-do 54896, Republic of Korea
- Research Institute of Clinical Medicine, Biomedical Research Institute, Chonbuk National University Hospital, Chonbuk National University, Jeonju, Jeollabuk-do 54896, Republic of Korea
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Krishnan HS, Ma L, Vasdev N, Liang SH. 18 F-Labeling of Sensitive Biomolecules for Positron Emission Tomography. Chemistry 2017; 23:15553-15577. [PMID: 28704575 PMCID: PMC5675832 DOI: 10.1002/chem.201701581] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Indexed: 12/21/2022]
Abstract
Positron emission tomography (PET) imaging study of fluorine-18 labeled biomolecules is an emerging and rapidly growing area for preclinical and clinical research. The present review focuses on recent advances in radiochemical methods for incorporating fluorine-18 into biomolecules via "direct" or "indirect" bioconjugation. Recently developed prosthetic groups and pre-targeting strategies, as well as representative examples in 18 F-labeling of biomolecules in PET imaging research studies are highlighted.
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Affiliation(s)
- Hema S. Krishnan
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Longle Ma
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Neil Vasdev
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Steven H. Liang
- Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
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Alkylation of phosphorothioated thrombin binding aptamers improves the selectivity of inhibition of tumor cell proliferation upon anticoagulation. Biochim Biophys Acta Gen Subj 2017; 1861:1864-1869. [PMID: 28389332 DOI: 10.1016/j.bbagen.2017.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/14/2017] [Accepted: 04/02/2017] [Indexed: 12/23/2022]
Abstract
BACKGROUND Recently, aptamers have been extensively researched for therapy and diagnostic applications. Thrombin-binding aptamer is a 15nt deoxyribonucleic acid screened by SELEX, it can specifically bind to thrombin and inhibit blood coagulation. Since it is also endowed with excellent antitumor activity, the intrinsic anticoagulation advantage converted to a main potential side effect for its further application in antiproliferative therapy. METHODS Site-specific alkylation was conducted through nucleophilic reaction of phosphorothioated TBAs using bromide reagents. Circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR) measurements were used to evaluate anticoagulation activity, and a CCK-8 assay was used to determine cell proliferation activity. RESULTS The CD spectra of the modified TBAs were weakened, and their affinity for thrombin was dramatically reduced, as reflected by the KD values. On the other hand, their inhibition of A549 cells was retained. CONCLUSIONS Incorporation of different alkyls apparently disrupted the binding of TBA to thrombin while maintaining the antitumor activity. GENERAL SIGNIFICANCE A new modification strategy was established for the use of TBA as a more selective antitumor agent.
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Inkster JAH, Colin DJ, Seimbille Y. A novel 2-cyanobenzothiazole-based (18)F prosthetic group for conjugation to 1,2-aminothiol-bearing targeting vectors. Org Biomol Chem 2015; 13:3667-76. [PMID: 25678209 DOI: 10.1039/c4ob02637c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In a bid to find an efficient means to radiolabel biomolecules under mild conditions for PET imaging, a bifunctional (18)F prosthetic molecule has been developed. The compound, dubbed [(18)F]FPyPEGCBT, consists of a 2-substituted pyridine moiety for [(18)F]F(-) incorporation and a 2-cyanobenzothiazole moiety for coupling to terminal cysteine residues. The two functionalities are separated by a mini-PEG chain. [(18)F]FPyPEGCBT could be prepared from its corresponding 2-trimethylammonium triflate precursor (100 °C, 15 min, MeCN) in preparative yields of 11% ± 2 (decay corrected, n = 3) after HPLC purification. However, because the primary radiochemical impurity of the fluorination reaction will not interact with 1,2-aminothiol functionalities, the (18)F prosthetic could be prepared for bioconjugation reactions by way of partial purification on a molecularly imprinted polymer solid-phase extraction cartridge. [(18)F]FPyPEGCBT was used to (18)F-label a cyclo-(RGDfK) analogue which was modified with a terminal cysteine residue (TCEP·HCl, DIPEA, 30 min, 43 °C, DMF). Final decay-corrected yields of (18)F peptide were 7% ± 1 (n = 9) from end-of-bombardment. This novel integrin-imaging agent is currently being studied in murine models of cancer. We argue that [(18)F]FPyPEGCBT holds significant promise owing to its straightforward preparation, 'click'-like ease of use, and hydrophilic character. Indeed, the water-tolerant radio-bioconjugation protocol reported herein requires only one HPLC step for (18)F peptide purification and can be carried out remotely using a single automated synthesis unit over 124-132 min.
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Affiliation(s)
- James A H Inkster
- University Hospitals of Geneva, Cyclotron Unit, Geneva, Switzerland.
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Wang L, Jacobson O, Avdic D, Rotstein BH, Weiss ID, Collier L, Chen X, Vasdev N, Liang SH. Ortho-Stabilized (18) F-Azido Click Agents and their Application in PET Imaging with Single-Stranded DNA Aptamers. Angew Chem Int Ed Engl 2015; 54:12777-81. [PMID: 26308650 PMCID: PMC4698351 DOI: 10.1002/anie.201505927] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Indexed: 12/20/2022]
Abstract
Azido (18) F-arenes are important and versatile building blocks for the radiolabeling of biomolecules via Huisgen cycloaddition ("click chemistry") for positron emission tomography (PET). However, routine access to such clickable agents is challenged by inefficient and/or poorly defined multistep radiochemical approaches. A high-yielding direct radiofluorination for azido (18) F-arenes was achieved through the development of an ortho-oxygen-stabilized iodonium derivative (OID). This OID strategy addresses an unmet need for a reliable azido (18) F-arene clickable agent for bioconjugation reactions. A ssDNA aptamer was radiolabeled with this agent and visualized in a xenograft mouse model of human colon cancer by PET, which demonstrates that this OID approach is a convenient and highly efficient way of labeling and tracking biomolecules.
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Affiliation(s)
- Lu Wang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA)
| | - Orit Jacobson
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (USA)
| | - Din Avdic
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA)
| | - Benjamin H Rotstein
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA)
| | - Ido D Weiss
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 (USA)
| | - Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA)
| | - Xiaoyuan Chen
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (USA).
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA).
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA 02114 (USA).
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Wang L, Jacobson O, Avdic D, Rotstein BH, Weiss ID, Collier L, Chen X, Vasdev N, Liang SH. Ortho-Stabilized18F-Azido Click Agents and their Application in PET Imaging with Single-Stranded DNA Aptamers. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201505927] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Li J, Zheng H, Bates PJ, Malik T, Li XF, Trent JO, Ng CK. Aptamer imaging with Cu-64 labeled AS1411: preliminary assessment in lung cancer. Nucl Med Biol 2013; 41:179-85. [PMID: 24373858 DOI: 10.1016/j.nucmedbio.2013.10.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 10/15/2013] [Accepted: 10/22/2013] [Indexed: 01/14/2023]
Abstract
INTRODUCTION AS1411 is a 26-base guanine-rich oligonucleotide aptamer shown binding to surface nucleolin, a protein over-expressed in multiple cancer cells, thus AS1411 labeled with a PET isotope can be explored as a potential diagnostic imaging agent. Our objective was to perform preliminary biological characterization of (64)Cu-labeled AS1411 in vitro and in vivo. METHODS Four chelators (DOTA, CB-TE2A, DOTA-Bn and NOTA-Bn) were selected to label AS1411 with Cu-64. 185kBq (5μCi) of each tracer was incubated in each well with H460 cells at 37°C for 1, 3, 6, 12, 24 and 48h, respectively (n=4). For microPET/CT imaging, 7.4MBq (200μCi) of AS1411 labeled with either (64)Cu-DOTA or (64)Cu-CB-TE2A was I.V. injected and multiple scans were obtained at 1, 3, 6 and 24h post injection. Afterward in vivo biodistribution studies were performed. RESULTS Percent uptake of (64)Cu-DOTA-AS1411 and (64)Cu-CB-TE2A-AS1411 was significantly higher than that of (64)Cu-DOTA-Bn-AS1411 and (64)Cu-NOTA-Bn-AS1411. About 90% of uptake for (64)Cu-DOTA-AS1411 and (64)Cu-CB-TE2A-AS1411 was internalized into cells within 3h and the internalization process was completed before 24h. Both tracers demonstrated reasonable in vivo stability and high binding affinity to the cells. MicroPET imaging with (64)Cu-CB-TE2A-AS1411 showed clear tumor uptake at both legs from 1 to 24h post injection, whereas both tumors were undetectable for up to 24h with (64)Cu-DOTA-AS1411. In addition, (64)Cu-CB-TE2A-AS1411 had faster in vivo pharmacokinetics than (64)Cu-DOTA-AS1411 with lower liver uptake and higher tumor to background contrast. CONCLUSION CB-TE2A is a preferred chelator with higher tumor-to-background ratio, lower liver uptake and faster clearance than DOTA. Aptamer imaging with (64)Cu-CB-TE2A-AS1411 may be feasible for detecting lung cancer, if an appropriate chelator can be identified and further validation can be performed with a known control oligonucleotide. It may also be used as a companion diagnostic imaging agent for AS1411 in the treatment of cancer.
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Affiliation(s)
- Junling Li
- Department of Diagnostic Radiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Huaiyu Zheng
- Department of Diagnostic Radiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Paula J Bates
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA; James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Tariq Malik
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA; James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Xiao-Feng Li
- Department of Diagnostic Radiology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - John O Trent
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40202, USA; James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Chin K Ng
- Department of Diagnostic Radiology, University of Louisville School of Medicine, Louisville, KY 40202, USA.
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von Guggenberg E, Shahhosseini S, Koslowsky I, Lavasanifar A, Murray D, Mercer J. In vitro characterization of two novel biodegradable vectors for the delivery of radiolabeled antisense oligonucleotides. Cancer Biother Radiopharm 2011; 25:723-31. [PMID: 21204767 DOI: 10.1089/cbr.2010.0813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The development of antisense oligonucleotides suitable for tumor targeting applications is hindered by low stability and bioavailability of oligonucleotides in vivo and by the absence of efficient and safe vectors for oligonucleotide delivery. Stabilization in vivo has been achieved through chemical modification of oligonucleotides by various means, but effective approaches to enhance their intracellular delivery are lacking. This study reports on the characterization in vitro of a fully phosphorothioated 20-mer oligonucleotide, complementary to p21 mRNA, radiolabeled with fluorine-18 using a thiol reactive prosthetic group. The potential of two novel synthetic block copolymers containing grafted polyamines on their hydrophobic blocks for vector-assisted cell delivery was studied in vitro. Extensive cellular uptake studies were performed in human colon carcinoma cell lines with enhanced or deficient p21 expression to evaluate and compare the uptake mechanism of naked and vectorized radiolabeled formulations. Uptake studies with the two novel biodegradable vectors showed a moderate increase in cell uptake of the radiofluorinated antisense oligonucleotide. The two vectors show, however, promising advantages over conventional lipidic vectors regarding their biocompatibility and subcellular distribution.
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Li Z, Conti PS. Radiopharmaceutical chemistry for positron emission tomography. Adv Drug Deliv Rev 2010; 62:1031-51. [PMID: 20854860 DOI: 10.1016/j.addr.2010.09.007] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/11/2010] [Accepted: 09/13/2010] [Indexed: 12/13/2022]
Abstract
Molecular imaging is an emerging technology that allows the visualization of interactions between molecular probes and biological targets. Molecules that either direct or are subject to homeostatic controls in biological systems could be labeled with the appropriate radioisotopes for the quantitative measurement of selected molecular interactions during normal tissue homeostasis and again after perturbations of the normal state. In particular, positron emission tomography (PET) offers picomolar sensitivity and is a fully translational technique that requires specific probes radiolabeled with a usually short-lived positron-emitting radionuclide. PET has provided the capability of measuring biological processes at the molecular and metabolic levels in vivo by the detection of the gamma rays formed as a result of the annihilation of the positrons emitted. Despite the great wealth of information that such probes can provide, the potential of PET strongly depends on the availability of suitable PET radiotracers. However, the development of new imaging probes for PET is far from trivial and radiochemistry is a major limiting factor for the field of PET. In this review, we provided an overview of the most common chemical approaches for the synthesis of PET-labeled molecules and highlighted the most recent developments and trends. The discussed PET radionuclides include ¹¹C (t₁(/)₂=20.4min), ¹³N (t₁(/)₂=9.9min), ¹⁵O (t₁(/)₂=2min), ⁶⁸Ga (t₁(/)₂=68min), ¹⁸F (t₁(/)₂=109.8min), ⁶⁴Cu (t₁(/)₂=12.7h), and ¹²⁴I (t₁(/)₂=4.12d).
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Daniels S, Tohid SFM, Velanguparackel W, Westwell AD. The role and future potential of fluorinated biomarkers in positron emission tomography. Expert Opin Drug Discov 2010; 5:291-304. [DOI: 10.1517/17460441003652967] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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