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Gijs M, Aerts A, Impens N, Baatout S, Luxen A. Aptamers as radiopharmaceuticals for nuclear imaging and therapy. Nucl Med Biol 2015; 43:253-71. [PMID: 26746572 DOI: 10.1016/j.nucmedbio.2015.09.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/24/2015] [Accepted: 09/10/2015] [Indexed: 12/27/2022]
Abstract
Today, radiopharmaceuticals belong to the standard instrumentation of nuclear medicine, both in the context of diagnosis and therapy. The majority of radiopharmaceuticals consist of targeting biomolecules which are designed to interact with a disease-related molecular target. A plethora of targeting biomolecules of radiopharmaceuticals exists, including antibodies, antibody fragments, proteins, peptides and nucleic acids. Nucleic acids have some significant advantages relative to proteinaceous biomolecules in terms of size, production, modifications, possible targets and immunogenicity. In particular, aptamers (non-coding, synthetic, single-stranded DNA or RNA oligonucleotides) are of interest because they can bind a molecular target with high affinity and specificity. At present, few aptamers have been investigated preclinically for imaging and therapeutic applications. In this review, we describe the use of aptamers as targeting biomolecules of radiopharmaceuticals. We also discuss the chemical modifications which are needed to turn aptamers into valuable (radio-)pharmaceuticals, as well as the different radiolabeling strategies that can be used to radiolabel oligonucleotides and, in particular, aptamers.
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Affiliation(s)
- Marlies Gijs
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK·CEN), Mol, Belgium; Cyclotron Research Centre, University of Liège, Liège, Belgium
| | - An Aerts
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK·CEN), Mol, Belgium
| | - Nathalie Impens
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK·CEN), Mol, Belgium
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre (SCK·CEN), Mol, Belgium
| | - André Luxen
- Cyclotron Research Centre, University of Liège, Liège, Belgium.
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2
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Abstract
Oligonucleotides radiolabeled with isotopes emitting γ-rays (for SPECT imaging) or positrons (for PET imaging) can be useful for targeting messenger RNA (mRNA) thereby serving as non-invasive imaging tools for detection of gene expression in vivo (antisense imaging). Radiolabeled oligonucleotides may also be used for monitoring their in vivo fate, thereby helping us better understand the barriers to its delivery for antisense targeting. These developments have led to a new area of molecular imaging and targeting, utilizing radiolabeled antisense oligonucleotides. However, the success of antisense imaging relies heavily on overcoming the barriers for its targeted delivery in vivo. Furthermore, the low ability of the radiolabeled antisense oligonucleotide to subsequently internalize into the cell and hybridize with its target mRNA poses additional challenges in realizing its potentials. This review covers the advances in the antisense imaging probe development for PET and SPECT, with an emphasis on radiolabeling strategies, stability, delivery and in vivo targeting.
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Affiliation(s)
- Arun K Iyer
- Center for Molecular and Functional Imaging, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA 94143
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3
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Schulz J, Vimont D, Bordenave T, James D, Escudier JM, Allard M, Szlosek-Pinaud M, Fouquet E. Silicon-based chemistry: an original and efficient one-step approach to [18F]-nucleosides and [18F]-oligonucleotides for PET imaging. Chemistry 2011; 17:3096-100. [PMID: 21312302 DOI: 10.1002/chem.201003234] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/10/2011] [Indexed: 12/13/2022]
Abstract
Take it eaSi! Nucleosides, dinucleotides, and one oligonucleotide, all modified by click chemistry, have for the first time been directly and very efficiently labeled with (18)F by using a silicon-based, one-step approach that opens the way for the development of a new class of positron emission tomography (PET) tracers (see graphic).
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Affiliation(s)
- Jürgen Schulz
- Université de Bordeaux, LIMF, UMR5231, 146, rue Léo Saignat, Bordeaux, 33076, France
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4
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James D, Escudier JM, Amigues E, Schulz J, Vitry C, Bordenave T, Szlosek-Pinaud M, Fouquet E. A ‘click chemistry’ approach to the efficient synthesis of modified nucleosides and oligonucleotides for PET imaging. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2009.12.120] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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5
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Abstract
Assessment of gene function following the completion of human genome sequencing may be done using radionuclide imaging procedures. These procedures are needed for the evaluation of genetically manipulated animals or newly designed biomolecules which require a thorough understanding of physiology, biochemistry and pharmacology. The experimental approaches will involve many new technologies, including in-vivo imaging with SPECT and PET. Nuclear medicine procedures may be applied for the determination of gene function and regulation using established and new tracers or using in-vivo reporter genes, such as genes encoding enzymes, receptors, antigens or transporters. Visualization of in-vivo reporter gene expression can be done using radiolabeled substrates, antibodies or ligands. Combinations of specific promoters and in-vivo reporter genes may deliver information about the regulation of the corresponding genes. Furthermore, protein-protein interactions and the activation of signal transduction pathways may be visualized noninvasively. The role of radiolabeled antisense molecules for the analysis of mRNA content has to be investigated. However, possible applications are therapeutic interventions using triplex oligonucleotides with therapeutic isotopes, which can be brought near to specific DNA sequences to induce DNA strand breaks at selected loci. After the identification of new genes, functional information is required to investigate the role of these genes in living organisms. This can be done by analysis of gene expression, protein-protein interaction or the biodistribution of new molecules and may result in new diagnostic and therapeutic procedures, which include visualization of and interference with gene transcription, and the development of new biomolecules to be used for diagnosis and treatment. Furthermore, the characterization of tumor cell-specific properties allows the design of new treatment modalities, such as gene therapy, which circumvent resistance mechanisms towards conventional chemotherapeutic drugs.
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Affiliation(s)
- Uwe Haberkorn
- Department of Nuclear Medicine, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.
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6
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Haberkorn U. Modulation of tracer accumulation in malignant tumors: gene expression, gene transfer, and phage display. Curr Top Dev Biol 2008; 70:145-69. [PMID: 16338341 DOI: 10.1016/s0070-2153(05)70007-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Assessment of gene function following the completion of human genome sequencing may be done using radionuclide imaging procedures. These procedures are needed for the evaluation of genetically manipulated animals or new designed biomolecules which requires a thorough understanding of physiology, biochemistry and pharmacology. The experimental approaches will involve many new technologies including in vivo imaging with SPECT and PET. Nuclear medicine procedures may be applied for the determination of gene function and regulation using established and new tracers or using in vivo reporter genes such as genes encoding enzymes, receptors, antigens or transporters. Visualization of in vivo reporter gene expression can be done using radiolabeled substrates, antibodies or ligands. Combinations of specific promoters and in vivo reporter genes may deliver information about the regulation of the corresponding genes. Furthermore, protein-protein interactions and activation of signal transduction pathways may be visualized non-invasively. The role of radiolabeled antisense molecules for the analysis of mRNA content has to be investigated. However, possible applications are therapeutic intervention using triplex oligonucleotides with therapeutic isotopes which can be brought near to specific DNA sequences to induce DNA strand breaks at selected loci. Imaging of labeled siRNA's makes sense if these are used for therapeutic purposes in order to assess the delivery of these new drugs to their target tissue. Finally, new biomolecules will be developed by bioengineering methods which may be used for isotope-based diagnosis and treatment of disease.
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Affiliation(s)
- Uwe Haberkorn
- Department of Nuclear Medicine, University of Heidelberg Clinical Cooperation Unit Nuclear Medicine German Cancer Research Center, Heidelberg, Germany
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7
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Segura J, Fillat C, Andreu D, Llop J, Millan O, de la Torre BG, Nikolovski Z, Gomez V, Andreu N, Pinyot A, Castelo R, Gispert JD, Pascual JA. Monitoring gene therapy by external imaging of mRNA: pilot study on murine erythropoietin. Ther Drug Monit 2007; 29:612-8. [PMID: 17898652 DOI: 10.1097/ftd.0b013e31811f3af6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Gene therapy is anticipated as being an important medical development. Essential to its effectiveness is the appropriate activity (protein expression) in the expected target cells. A noninvasive diagnostic procedure of successful gene expression will be of paramount importance to validate its use or its misuse (eg, sports gene doping). Externally detectable labeled oligonucleotide hybridizing with the messenger RNA generated by the transferred gene has been proposed as a possibility to monitor successful gene therapy. The authors selected the erythropoietin gene (Epo) for a pilot study on erythropoietin protein expression in mouse muscle. Oligonucleotides of peptide nucleic acid (PNA) type capable of antisense binding to unique murine Epo-mRNA sequences were synthesized by solid phase methods, and elongated at the N-terminus with the HIV Tat (48-60) cell penetrating peptide. They were labeled with fluorescence and radioactive tags to verify penetration and longer half-life properties in Epo gene transfected C2C12 mouse muscle cells as compared with corresponding wild-type cells. Downregulation of newly expressed erythropoietin protein in such cells additionally confirmed the penetration and hybridizing properties of the selected labeled oligonucleotide. I-labeled Tat-PNAs were intravenously injected into mice that had previously received the Epo gene into the right tibialis muscle by DNA electrotransfer. Preferential accumulation of radioactivity in the transferred limb as compared with the contralateral limb was ascertained, especially for I-Tat-CTA CGT AGA CCA CT (labeled Tat-PNA 1). This study provides experimental data to support the potential use of external noninvasive image detection to monitor gene therapy. The extension of the approach to more sensitive methods for whole-body external detection such as positron emission tomography appears feasible.
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Affiliation(s)
- J Segura
- Institut Municipal d'Investigació Mèdica IMIM-Hospital del Mar, Barcelona, Spain.
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8
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Study on biodistribution and imaging of radioiodinated antisense oligonucleotides in nude mice bearing human lymphoma. J Radioanal Nucl Chem 2007. [DOI: 10.1007/s10967-007-0704-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Bergmann R, Pietzsch J. Small animal positron emission tomography in food sciences. Amino Acids 2005; 29:355-76. [PMID: 16142524 DOI: 10.1007/s00726-005-0237-2] [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: 06/01/2005] [Accepted: 07/13/2005] [Indexed: 02/07/2023]
Abstract
Positron emission tomography (PET) is a 3-dimensional imaging technique that has undergone tremendous developments during the last decade. Non-invasive tracing of molecular pathways in vivo is the key capability of PET. It has become an important tool in the diagnosis of human diseases as well as in biomedical and pharmaceutical research. In contrast to other imaging modalities, radiotracer concentrations can be determined quantitatively. By application of appropriate tracer kinetic models, the rate constants of numerous different biological processes can be determined. Rapid progress in PET radiochemistry has significantly increased the number of biologically important molecules labelled with PET nuclides to target a broader range of physiologic, metabolic, and molecular pathways. Progress in PET physics and technology strongly contributed to better scanners and image processing. In this context, dedicated high resolution scanners for dynamic PET studies in small laboratory animals are now available. These developments represent the driving force for the expansion of PET methodology into new areas of life sciences including food sciences. Small animal PET has a high potential to depict physiologic processes like absorption, distribution, metabolism, elimination and interactions of biologically significant substances, including nutrients, 'nutriceuticals', functional food ingredients, and foodborne toxicants. Based on present data, potential applications of small animal PET in food sciences are discussed.
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Affiliation(s)
- R Bergmann
- Positron Emission Tomography Center, Institute of Bioinorganic and Radiopharmaceutical Chemistry, Research Center Rossendorf, Dresden, Germany.
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10
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Tavitian B. Oligonucleotides as radiopharmaceuticals. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2005:1-34. [PMID: 15524208 DOI: 10.1007/3-540-26809-x_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Affiliation(s)
- B Tavitian
- INSERM ERM 103 Service Hospitalier, Frédéric Joliot CEA Direction des Sciences du Vivant Direction de la Recherche Medicale, Orsay, France.
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11
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Abstract
Labeled oligonucleotide analogues for antisense imaging of messenger RNA (mRNA) have great potential for detection of endogenous gene expression in vivo. Successful antisense imaging may be useful for detecting cellular gene expression patterns and early molecular changes in disease. Conclusive demonstration of this technique has been hindered by formidable challenges in surmounting biological barriers and detecting low concentrations of target mRNA. Recent advances in the development of novel antisense molecules, high specific activity radiolabeling chemistry, sophisticated drug targeting technology, and complementary molecular imaging modalities make it quite possible that true antisense imaging will be realized in the near future.
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Affiliation(s)
- Michael R Lewis
- Department of Veterinary Medicine and Surgery, University of Missouri-Columbia, Columbia, Missouri 65211, USA.
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12
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Haberkorn U, Altmann A, Mier W, Eisenhut M. Impact of functional genomics and proteomics on radionuclide imaging. Semin Nucl Med 2004; 34:4-22. [PMID: 14735455 DOI: 10.1053/j.semnuclmed.2003.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The assessment of gene function following the completion of human genome sequencing may be performed using radionuclide imaging procedures. These procedures are needed for the evaluation of genetically manipulated animals or newly designed biomolecules, which requires a thorough understanding of physiology, biochemistry, and pharmacology. The experimental approaches will involve many new technologies, including in vivo imaging with single photon emission computed tomography and positron emission tomography. Nuclear medicine procedures may be applied for the determination of gene function and regulation using established and new tracers, or using in vivo reporter genes, such as genes encoding enzymes, receptors, antigens, or transporters. Visualization of in vivo reporter gene expression can be performed using radiolabeled substrates, antibodies, or ligands. Combinations of specific promoters and in vivo reporter genes may deliver information about the regulation of the corresponding genes. Furthermore, protein-protein interactions and activation of signal transduction pathways may be visualized noninvasively. The role of radiolabeled antisense molecules for the analysis of messenger ribonucleic acid (RNA) content has to be investigated. However, possible applications are therapeutic intervention using triplex oligonucleotides with therapeutic isotopes, which can be brought near to specific deoxyribonucleic acid sequences to induce deoxyribonucleic acid strand breaks at selected loci. Imaging of labeled siRNA makes sense if these are used for therapeutic purposes to assess the delivery of these new drugs to their target tissue. Pharmacogenomics will identify new surrogate markers for therapy monitoring, which may represent potential new tracers for imaging. Drug distribution studies for new therapeutic biomolecules are needed at least during preclinical stages of drug development. New treatment modalities, such as gene therapy with suicide genes, will need procedures for therapy planning and monitoring. Finally, new biomolecules will be developed by bioengineering methods, which may be used for the isotope-based diagnosis and treatment of disease.
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Affiliation(s)
- Uwe Haberkorn
- Department of Nuclear Medicine, University of Heidelberg, Germany.
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13
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Haberkorn U. Future directions in molecular imaging. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2004:111-34. [PMID: 15248519 DOI: 10.1007/978-3-662-07310-0_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
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14
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Abstract
The assessment of gene function, which follows the completion of human genome sequencing, may be performed using the tools of the genome program. These tools represent high-throughput methods evaluating changes in the expression of many or all genes of an organism at the same time in order to investigate genetic pathways for normal development and disease. They describe proteins on a proteome-wide scale, thereby, creating a new way of doing cell research which results in the determination of three dimensional protein structures and the description of protein networks. These descriptions may then be used for the design of new hypotheses and experiments in the traditional physiological, biochemical, and pharmacological sense. The evaluation of genetically manipulated animals or new designed biomolecules will require a thorough understanding of physiology, biochemistry, and pharmacology and the experimental approaches will involve many new technologies including in vivo imaging with SPECT and positron emission tomography (PET). Nuclear medicine procedures may be applied for the determination of gene function and regulation using established and new tracers or using in vivo reporter genes such as genes encoding enzymes, receptors, antigens, or transporters. Pharmacogenomics will identify new surrogate markers for therapy monitoring which may represent potential new tracers for imaging. Also drug distribution studies for new therapeutic biomolecules are needed at least during preclinical stages of drug development. Finally, new biomolecules will be developed by bioengineering methods, which may be used for isotope-based diagnosis and treatment of disease.
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Affiliation(s)
- Uwe Haberkorn
- Department of Nuclear Medicine, University of Heidelberg, Germany.
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15
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Boado RJ, Pardridge WM. Imaging gene expression in the brain with peptide nucleic acid (PNA) antisense radiopharmaceuticals and drug targeting technology. Int J Pept Res Ther 2003. [DOI: 10.1007/s10989-004-4918-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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de Vries EFJ, Vroegh J, Elsinga PH, Vaalburg W. Evaluation of fluorine-18-labeled alkylating agents as potential synthons for the labeling of oligonucleotides. Appl Radiat Isot 2003; 58:469-76. [PMID: 12672626 DOI: 10.1016/s0969-8043(03)00022-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Six fluorine-18-labeled alkylating agents were selected as potentially suitable synthons for the labeling of antisense oligonucleotides. The selected synthons were evaluated in a model reaction with the monomer adenosine 5'-O-thiomonophosphate. Of these synthons, alpha-bromo-alpha'-[18F]fluoro-m-xylene and N-(4-[18F]fluorobenzyl)-2-bromoacetamide were found to be the most promising. Labeling with the former synthon was less complicated and time consuming and gave higher uncorrected overall yields. The latter synthon required smaller amounts of the costly precursor to achieve acceptable labeling yields.
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Affiliation(s)
- Erik F J de Vries
- PET Center, Groningen University Hospital, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands.
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17
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Abstract
After the sequencing of the human genome has been completed, non-invasive imaging studies are needed to assess the function of new genes in living organisms. The evaluation of genetically manipulated animals or new designed biomolecules will require a thorough understanding of physiology, biochemistry and pharmacology, and the experimental approaches will involve many new technologies including in vivo imaging with single photon emission computed tomography (SPECT) and positron emission tomography (PET). Nuclear medicine procedures may be applied for the determination of gene function and regulation using established and new tracers or using in vivo reporter genes such as enzymes, receptors, antigens or transporters. Pharmacogenomics will identify new surrogate markers for therapy monitoring which may represent potential new tracers for imaging. Also, drug distribution studies for new therapeutic biomolecules are needed at least during preclinical stages of drug development. Clinical gene therapy needs non-invasive tools to evaluate the efficiency of gene transfer. These informations can be used for therapy planning, follow-up studies in treated tumors and as an indicator of prognosis. Therapy planning is performed by the assessment of gene expression for example using radio-labeled specific substrates to determine the activity of suicide enzymes such as the Herpes Simplex Virus thymidine kinase. Follow-up studies with single photon emission tomography or positron emission tomography may be done to evaluate early or late effects of gene therapy on tumor metabolism or proliferation. Finally, new biomolecules will be developed by bioengineering methods which may be used for isotope-based diagnosis and treatment of disease.
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Affiliation(s)
- Uwe Haberkorn
- Department of Nuclear Medicine, University of Heidelberg and Clinical Cooperation Unit, Nuclear Medicine, German Cancer Research Center, Heidelberg, FRG.
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18
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Wagner S, Eritja R, Zuhayra M, Oberdorfer F, Mohammed A, Mier W, Haberkorn U, Eisenhut M. Synthesis and properties of radiolabeled CPTA-oligonucleotides. J Labelled Comp Radiopharm 2003. [DOI: 10.1002/jlcr.656] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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19
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O'Connell-Rodwell CE, Burns SM, Bachmann MH, Contag CH. Bioluminescent indicators for in vivo measurements of gene expression. Trends Biotechnol 2002. [DOI: 10.1016/s0167-7799(02)02001-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Stoessl AJ. Antisense strategies for the treatment of neurological disease. Expert Opin Ther Pat 2001. [DOI: 10.1517/13543776.11.4.547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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21
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Shi N, Boado RJ, Pardridge WM. Antisense imaging of gene expression in the brain in vivo. Proc Natl Acad Sci U S A 2000; 97:14709-14. [PMID: 11106372 PMCID: PMC18983 DOI: 10.1073/pnas.250332397] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antisense radiopharmaceuticals could be used to image gene expression in the brain in vivo, should these polar molecules be made transportable through the blood-brain barrier. The present studies describe an antisense imaging agent comprised of an iodinated peptide nucleic acid (PNA) conjugated to a monoclonal antibody to the rat transferrin receptor by using avidin-biotin technology. The PNA was a 16-mer antisense to the sequence around the methionine initiation codon of the luciferase mRNA. C6 rat glioma cells were permanently transfected with a luciferase expression plasmid, and C6 experimental brain tumors were developed in adult rats. The expression of the luciferase transgene in the tumors in vivo was confirmed by measurement of luciferase enzyme activity in the tumor extract. The [(125)I]PNA conjugate was injected intravenously in anesthetized animals with brain tumors and killed 2 h later for frozen sectioning of brain and film autoradiography. No image of the luciferase gene expression was obtained after the administration of either the unconjugated antiluciferase PNA or a PNA conjugate that was antisense to the mRNA of a viral transcript. In contrast, tumors were imaged in all rats administered the [(125)I]PNA that was antisense to the luciferase sequence and was conjugated to the targeting antibody. In conclusion, these studies demonstrate gene expression in the brain in vivo can be imaged with antisense radiopharmaceuticals that are conjugated to a brain drug-targeting system.
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Affiliation(s)
- N Shi
- Department of Medicine, University of California School of Medicine, Los Angeles, CA 90095-1682, USA
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22
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MacLaren DC, Toyokuni T, Cherry SR, Barrio JR, Phelps ME, Herschman HR, Gambhir SS. PET imaging of transgene expression. Biol Psychiatry 2000; 48:337-48. [PMID: 10978717 DOI: 10.1016/s0006-3223(00)00970-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A vital step in transgenic animal study and gene therapy is the ability to assay the extent of transgene expression. Unfortunately, classic methods of assaying transgene expression require biopsies or death of the subject. We are developing techniques to noninvasively and repetitively determine the location, duration, and magnitude of transgene expression in living animals. This will allow investigators and clinicians to assay the effectiveness of their particular experimental and therapeutic paradigms. Of radionuclide (single photon emission computed tomography, positron emission tomography [PET]), optical (green fluorescent protein, luciferase), and magnetic (magnetic resonance imaging) approaches, only the radionuclide approach has sufficient sensitivity and quantitation to measure the expression of genes in vivo. We describe the instrumentation involved in high resolution PET scanning. We also describe the principles of PET reporter gene/reporter probe in vivo imaging, the development of two in vivo reporter gene imaging systems, and the validation of our ability to noninvasively, quantitatively, and repetitively image gene expression in murine viral gene transfer and transgenic models. We compare the two reporter gene systems and discuss their utility for the study of transgenic animals and gene therapies. Finally, we mention alternative approaches to image gene expression by using radiolabeled antibody fragments to image specific proteins and radiolabeled oligonucleotides to image RNA messages directly.
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Affiliation(s)
- D C MacLaren
- The Crump Institute for Biological Imaging, UCLA School of Medicine, Los Angeles, California, USA
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