51
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Shetty D, Jeong JM, Shim H. Stroma targeting nuclear imaging and radiopharmaceuticals. INTERNATIONAL JOURNAL OF MOLECULAR IMAGING 2012; 2012:817682. [PMID: 22685650 PMCID: PMC3364577 DOI: 10.1155/2012/817682] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 02/29/2012] [Indexed: 01/27/2023]
Abstract
Malignant transformation of tumor accompanies profound changes in the normal neighboring tissue, called tumor stroma. The tumor stroma provides an environment favoring local tumor growth, invasion, and metastatic spreading. Nuclear imaging (PET/SPECT) measures biochemical and physiologic functions in the human body. In oncology, PET/SPECT is particularly useful for differentiating tumors from postsurgical changes or radiation necrosis, distinguishing benign from malignant lesions, identifying the optimal site for biopsy, staging cancers, and monitoring the response to therapy. Indeed, PET/SPECT is a powerful, proven diagnostic imaging modality that displays information unobtainable through other anatomical imaging, such as CT or MRI. When combined with coregistered CT data, [(18)F]fluorodeoxyglucose ([(18)F]FDG)-PET is particularly useful. However, [(18)F]FDG is not a target-specific PET tracer. This paper will review the tumor microenvironment targeting oncologic imaging such as angiogenesis, invasion, hypoxia, growth, and homing, and also therapeutic radiopharmaceuticals to provide a roadmap for additional applications of tumor imaging and therapy.
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Affiliation(s)
- Dinesh Shetty
- Department of Radiology and Imaging Sciences, Emory University, 1701 Uppergate Drive, C5008, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
| | - Jae-Min Jeong
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul 110744, Republic of Korea
| | - Hyunsuk Shim
- Department of Radiology and Imaging Sciences, Emory University, 1701 Uppergate Drive, C5008, Atlanta, GA 30322, USA
- Winship Cancer Institute, Emory University, Atlanta, GA 30322, USA
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52
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Hennrich U, Seyler L, Schäfer M, Bauder-Wüst U, Eisenhut M, Semmler W, Bäuerle T. Synthesis and in vitro evaluation of 68Ga-DOTA-4-FBn-TN14003, a novel tracer for the imaging of CXCR4 expression. Bioorg Med Chem 2012; 20:1502-10. [PMID: 22264762 DOI: 10.1016/j.bmc.2011.12.052] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 12/23/2011] [Accepted: 12/23/2011] [Indexed: 01/30/2023]
Abstract
The expression of the chemokine receptor CXCR4 in tumors is associated with tumor aggressiveness and poor prognosis for the patient and contributes to metastatic seeding. Therefore it is of high interest to find a specific PET tracer for the imaging of CXCR4 expression in tumors. The aim of this study was the synthesis, (68)Ga labeling and first evaluation of DOTA-4-FBn-TN14003 as a potential PET tracer for this purpose. DOTA-4-FBn-TN14003 was synthesized using solid phase peptide synthesis and radiolabeling of this versatile precursor was performed with (68)Ga, which was obtained from a (68)Ge/(68)Ga generator. (68)Ga-DOTA-4-FBn-TN14003 was reproducibly obtained in isolated radiochemical yields of 72.5±4.9% with an excellent radiochemical purity of >99.5%. Specific activities of up to 29.8±3.1 GBq/μmol were achieved. In competition binding assays with SDF-1α, human T cell lymphoma Jurkat cells expressed high levels of CXCR4 whereas human breast cancer MDA-MB-231 cells expressed significantly lower levels of this chemokine receptor. The inhibition constants (IC(50)) of Ga-DOTA-4-FBn-TN14003 and 4-FBn-TN14003 to CXCR4 were determined in a competition assay against (125)I-SDF-1α using Jurkat as well as MDA-MB-231 cells. The IC(50) values of Ga-DOTA-4-FBn-TN14003 (1.99±0.31 nM) and 4-FBn-TN14003 (4.07±1.00 nM) proved to be comparable, indicating negligible influence of the metal complex. These results suggest (68)Ga-DOTA-4-FBn-TN14003 as a promising agent for the imaging of CXCR4 expression in tumors and metastases.
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Affiliation(s)
- Ute Hennrich
- Department of Medical Physics in Radiology, DKFZ, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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53
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Knight JC, Wuest FR. Nuclear (PET/SPECT) and optical imaging probes targeting the CXCR4 chemokine receptor. MEDCHEMCOMM 2012. [DOI: 10.1039/c2md20117h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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54
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Oishi S, Fujii N. Peptide and peptidomimetic ligands for CXC chemokine receptor 4 (CXCR4). Org Biomol Chem 2012; 10:5720-31. [DOI: 10.1039/c2ob25107h] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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55
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Abstract
Chemokine receptor 4 (CXCR4)-chemokine ligand 12 (CXCL12) interactions have been shown to play key roles in cancer cell survival, proliferation, chemotaxis, homing, adhesion, tumor angiogenesis, and resistance to conventional and targeted therapies. Given its extensive involvement in cancer progression, the CXCR4-CXCL12 axis has been considered a therapeutic target. Several inhibitors blocking this signaling cascade are in phase I trials. Because CXCR4 is constitutively expressed in a wide variety of normal tissues, patient stratification and noninvasive monitoring would improve therapeutic outcome and reduce unnecessary toxicities. This review focuses on recent developments in CXCR4-based imaging agents and their potential role in the molecular diagnosis and treatment of cancer.
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Affiliation(s)
- Lauren E Woodard
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland 21231, USA
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56
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Kuil J, Buckle T, Oldenburg J, Yuan H, Josephson L, van Leeuwen FW. Hybrid peptide dendrimers for imaging of chemokine receptor 4 (CXCR4) expression. Mol Pharm 2011; 8:2444-53. [PMID: 22085282 PMCID: PMC3711081 DOI: 10.1021/mp200401p] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The chemokine receptor 4 (CXCR4), which is overexpressed in many types of cancer, is an emerging target in the field of molecular imaging and therapeutics. The CXCR4 binding of several peptides, including the cyclic Ac-TZ14011, has already been validated. In this study mono-, di- and tetrameric Ac-TZ14011-containing dendrimers were prepared and functionalized with a multimodal (hybrid) label, consisting of a Cy5.5-like fluorophore and a DTPA chelate. Confocal microscopy revealed that all three dendrimers were membrane bound at 4 °C, consistent with CXCR4 binding in vitro. The unlabeled dimer and tetramer had a somewhat lower affinity for CXCR4 than the unlabeled monomer. However, when labeled with the multimodal label the CXCR4 affinity of the dimer and tetramer was considerably higher compared to that of the labeled monomer. On top of that, biodistribution studies revealed that the additional peptides in the dimer and tetramer reduced nonspecific muscle uptake. Thus, multimerization of the cyclic Ac-TZ14011 peptide reduces the negative influence of the multimodal label on the receptor affinity and the biodistribution.
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Affiliation(s)
- Joeri Kuil
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
| | - Tessa Buckle
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
| | - Joppe Oldenburg
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
| | - Hushan Yuan
- Center for Molecular Imaging Research, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
| | - Lee Josephson
- Center for Molecular Imaging Research, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
| | - Fijs W.B. van Leeuwen
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
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57
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Gourni E, Demmer O, Schottelius M, D'Alessandria C, Schulz S, Dijkgraaf I, Schumacher U, Schwaiger M, Kessler H, Wester HJ. PET of CXCR4 Expression by a 68Ga-Labeled Highly Specific Targeted Contrast Agent. J Nucl Med 2011; 52:1803-10. [DOI: 10.2967/jnumed.111.098798] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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58
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Demmer O, Dijkgraaf I, Schumacher U, Marinelli L, Cosconati S, Gourni E, Wester HJ, Kessler H. Design, synthesis, and functionalization of dimeric peptides targeting chemokine receptor CXCR4. J Med Chem 2011; 54:7648-62. [PMID: 21905730 DOI: 10.1021/jm2009716] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The chemokine receptor CXCR4 is a critical regulator of inflammation and immune surveillance, and it is specifically implicated in cancer metastasis and HIV-1 infection. On the basis of the observation that several of the known antagonists remarkably share a C(2) symmetry element, we constructed symmetric dimers with excellent antagonistic activity using a derivative of a cyclic pentapeptide as monomer. To optimize the binding affinity, we investigated the influence of the distance between the monomers and the pharmacophoric sites in the synthesized constructs. The affinity studies in combination with docking computations support a two-site binding model. In a final step, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was introduced as chelator for (radio-)metals, thus allowing to exploit these compounds as a new group of CXCR4-binding peptidic probes for molecular imaging and endoradiotherapeutic purposes. Both the DOTA conjugates and some of their corresponding metal complexes retain good CXCR4 affinity, and one (68)Ga labeled compound was studied as PET tracer.
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Affiliation(s)
- Oliver Demmer
- Institute for Advanced Study, Technische Universität München , Lichtenbergstrasse 4, D-85748 Garching, Germany
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59
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Demmer O, Gourni E, Schumacher U, Kessler H, Wester HJ. PET imaging of CXCR4 receptors in cancer by a new optimized ligand. ChemMedChem 2011; 6:1789-91. [PMID: 21780290 PMCID: PMC3229844 DOI: 10.1002/cmdc.201100320] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Indexed: 12/16/2022]
Affiliation(s)
- Oliver Demmer
- Institute for Advanced Study and Center of Integrated Protein Science at the Department Chemie, Technische Universität MünchenLichtenbergstraße 4, 85748 Garching (Germany) E-mail:
| | - Eleni Gourni
- Lehrstuhl für Pharmazeutische Radiochemie, Technische Universität MünchenWalther-Meißner-Str. 3, 85748 Garching (Germany) E-mail:
| | - Udo Schumacher
- Institute for Anatomy II: Experimental Morphology, Universitätsklinikum Hamburg-EppendorfMartinistrasse 52, 20246 Hamburg (Germany)
| | - Horst Kessler
- Institute for Advanced Study and Center of Integrated Protein Science at the Department Chemie, Technische Universität MünchenLichtenbergstraße 4, 85748 Garching (Germany) E-mail:
- Chemistry Department, Faculty of Science, King Abdulaziz UniversityP.O. Box 80203, Jeddah 21589 (Saudi Arabia)
| | - Hans-Jürgen Wester
- Lehrstuhl für Pharmazeutische Radiochemie, Technische Universität MünchenWalther-Meißner-Str. 3, 85748 Garching (Germany) E-mail:
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60
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Immunohistochemical detection of the CXCR4 expression in tumor tissue using the fluorescent peptide antagonist Ac-TZ14011-FITC. Transl Oncol 2011; 4:234-40. [PMID: 21804919 DOI: 10.1593/tlo.11115] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 02/23/2011] [Accepted: 03/02/2011] [Indexed: 02/05/2023] Open
Abstract
Pathology is fundamental in grading, staging, and treatment planning of malignancies. One relatively novel biomarker that may become more important in therapy and diagnostics is the chemokine receptor 4 (CXCR4). Ac-TZ14011 peptide derivatives, functionalized with a radiolabel, can be used for molecular imaging of tumors. Direct fluorescent labeling of the small peptide Ac-TZ14011 with the fluorescent dye fluorescein isothiocyanate (FITC), however, provides an alternative for the detection of CXCR4 expression levels in cells and tumor tissue. In this study, Ac-TZ14011-FITC was validated for CXCR4 staining in human breast cancer cell lines MDAMB231 and MDAMB231(CXCR4+) during flow cytometric analysis. Its efficacy was compared to commercially available antibodies. Competition experiments validated the staining specificity. Confocal imaging revealed that CXCR4 staining was predominantly found on the cell membrane and/or in vesicles formed after endocytosis. Next to being able to differentiate "high" and "low" CXCR4-expressing tumor cells, the fluorescent peptide demonstrates potential in fluorescent immunohistochemistry of tumor tissue. Ac-TZ14011-FITC was able to differentiate MDAMB231 from MDAMB231(CXCR4+) tumor cells and tissue, proving its applicability in the detection of differences in CXCR4 expression levels.
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61
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De Silva RA, Peyre K, Pullambhatla M, Fox JJ, Pomper MG, Nimmagadda S. Imaging CXCR4 expression in human cancer xenografts: evaluation of monocyclam 64Cu-AMD3465. J Nucl Med 2011; 52:986-93. [PMID: 21622896 DOI: 10.2967/jnumed.110.085613] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The chemokine receptor 4 (CXCR4) is overexpressed in several cancers and metastases and as such presents an enticing target for molecular imaging of metastases and metastatic potential of the primary tumor. CXCR4-based imaging agents could also be useful for diagnosis, staging, and therapeutic monitoring. Here we evaluated a positron-emitting monocyclam analog, (64)Cu-{N-[1,4,8,11-tetraazacyclotetradecanyl-1,4-phenylenebis(methylene)]-2-(aminomethyl)pyridine} ((64)Cu-AMD3465), in subcutaneous U87 brain tumors and U87 tumors stably expressing CXCR4 (U87-stb-CXCR4) and in colon tumors (HT-29) using dynamic and whole-body PET supported by ex vivo biodistribution studies. Both dynamic and whole-body PET/CT studies show specific accumulation of radioactivity in U87-stb-CXCR4 tumors, with the percentage injected dose per gram reaching a maximum of 102.70 ± 20.80 at 60 min and tumor-to-muscle ratios reaching a maximum of 362.56 ± 153.51 at 90 min after injection of the radiotracer. Similar specificity was also observed in the HT-29 colon tumor model. Treatment with AMD3465 inhibited uptake of radioactivity by the tumors in both models. Our results show that (64)Cu-AMD3465 is capable of detecting lesions in a CXCR4-dependent fashion, with high target selectivity, and may offer a scaffold for the synthesis of clinically translatable agents.
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Affiliation(s)
- Ravindra A De Silva
- Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland 21231, USA
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62
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Kuil J, Steunenberg P, Chin PTK, Oldenburg J, Jalink K, Velders AH, van Leeuwen FWB. Peptide-functionalized luminescent iridium complexes for lifetime imaging of CXCR4 expression. Chembiochem 2011; 12:1897-903. [PMID: 21739561 DOI: 10.1002/cbic.201100271] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Indexed: 01/31/2023]
Abstract
The chemokine receptor 4 (CXCR4) is over-expressed in 23 types of cancer in which it plays a role in, among others, the metastatic spread. For this reason it is a potential biomarker for the field of diagnostic oncology. The antagonistic Ac-TZ14011 peptide, which binds to CXCR4, has been conjugated to luminescent iridium dyes to allow for CXCR4 visualization. The iridium dyes are cyclometalated octahedral iridium(III) 2-phenylpyridine complexes that can be functionalized with one, two or three targeting Ac-TZ14011 peptides. Confocal microscopy and fluorescence lifetime imaging microscopy (FLIM) showed that the peptide-iridium complex conjugates can be used to visualize CXCR4 expression in tumor cells. The CXCR4 receptor affinity and specific cell binding of the mono-, di- and trimeric peptide derivatives were assessed by using flow cytometry. The three derivatives possessed nanomolar receptor affinity and could distinguish between cell lines with different CXCR4 expression levels. This yields the first example of a neutral iridium(III) complex functionalized with peptides for FLIM-based visualization of a cancer associated membrane receptor.
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Affiliation(s)
- Joeri Kuil
- Division of Diagnostic Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
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63
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Kuil J, Yuan H, Buckle T, Oishi S, Fujii N, Josephson L, van Leeuwen FW. Synthesis and evaluation of a bimodal CXCR4 antagonistic peptide. Bioconjug Chem 2011; 22:859-64. [PMID: 21480671 PMCID: PMC3711080 DOI: 10.1021/bc2000947] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The antagonistic Ac-TZ14011 peptide, which binds to the chemokine receptor 4, has been labeled with a multifunctional single attachment point reagent that contains a DTPA chelate and a fluorescent dye with Cy5.5 spectral properties. Flow cytometry and confocal microscopy showed that the bimodal labeled peptide gave a specific receptor binding that is similar to monofunctionalized peptide derivatives. Therefore, the newly developed bimodal peptide derivative can be used in multimodal imaging applications.
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Affiliation(s)
- Joeri Kuil
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
| | - Hushan Yuan
- Center for Molecular Imaging Research, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
| | - Tessa Buckle
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
| | - Shinya Oishi
- Department of Bioorganic Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Nobutaka Fujii
- Department of Bioorganic Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Lee Josephson
- Center for Molecular Imaging Research, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
| | - Fijs W.B. van Leeuwen
- Division of Diagnostic Oncology, the Netherlands Cancer Institute Antoni van Leeuwenhoek Hospital, 1066 CX Amsterdam, The Netherlands
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64
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Jacobson O, Weiss ID, Szajek LP, Niu G, Ma Y, Kiesewetter DO, Farber JM, Chen X. PET imaging of CXCR4 using copper-64 labeled peptide antagonist. Theranostics 2011; 1:251-62. [PMID: 21544263 PMCID: PMC3085282 DOI: 10.7150/thno/v01p0251] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Accepted: 04/18/2011] [Indexed: 02/04/2023] Open
Abstract
Expression of CXCR4 in cancer has been found to correlate with poor prognosis and resistance to chemotherapy. In this study we developed a derivative of the CXCR4 peptide antagonist, T140-2D, that can be labeled easily with the PET isotope copper-64, and thereby enable in vivo visualization of CXCR4 in tumors. T140 was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid mono (N-hydroxysuccinimide ester) (DOTA-NHS) to give T140-2D, which contains a DOTA molecule on each of the two lysine residues. 64Cu-T140-2D was evaluated in vitro by migration and binding experiments, and in vivo by microPET imaging and biodistribution, in mice bearing CXCR4-positive and CXCR4-negative tumor xenografts. T140-2D was labeled with copper-64 to give 64Cu-T140-2D in a high radiochemical yield of 86 ± 3% (not decay-corrected) and a specific activity of 0.28 - 0.30 mCi/µg (10.36 - 11.1 MBq/µg). 64Cu-T140-2D had antagonistic and binding characteristics to CXCR4 that were similar to those of T140. In vivo, 64Cu-T140-2D tended to bind to red blood cells and had to be used in a low specific activity form. In this new form 64Cu-T140-2D enabled specific imaging of CXCR4-positive, but not CXCR4-negative tumors. Undesirably, however, 64Cu-T140-2D also displayed high accumulation in the liver and kidneys. In conclusion, 64Cu-T140-2D was easily labeled and, in its low activity form, enabled imaging of CXCR4 in tumors. It had high uptake, however, in metabolic organs. Further research with imaging tracers targeting CXCR4 is required.
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65
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Masuda R, Oishi S, Ohno H, Kimura H, Saji H, Fujii N. Concise site-specific synthesis of DTPA-peptide conjugates: application to imaging probes for the chemokine receptor CXCR4. Bioorg Med Chem 2011; 19:3216-20. [PMID: 21524584 DOI: 10.1016/j.bmc.2011.03.059] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 03/25/2011] [Accepted: 03/26/2011] [Indexed: 11/28/2022]
Abstract
Diethylenetriaminepentaacetic acid (DTPA) is a useful chelating agent for radionuclides such as (68)Ga, (99m)Tc and (111)In, which are applicable to nuclear medicine imaging. In this study, we established a facile synthetic protocol for the production of mono-DTPA-conjugated peptide probes. A novel monoreactive DTPA precursor reagent was synthesized in two steps using the chemistry of the o-nitrobenzenesulfonyl (Ns) protecting group, and under mild conditions this DTPA precursor was incorporated onto an N(ε)-bromoacetylated Lys of a protected peptide resin. The site-specific DTPA conjugation was facilitated by using a highly acid-labile 4-methyltrityl (Mtt) protecting group for the target site of the bioactive peptide during the solid-phase synthesis. A combination of both techniques yielded peptides with disulfide bonds, such as octreotide and polyphemusin II-derived CXCR4 antagonists. DTPA-peptide conjugates were purified in a single step following cleavage from the resin and disulfide bond formation. This site-specific on-resin construction strategy was used for the design and synthesis of a novel In-DTPA-labeled CXCR4 antagonist, which exhibited highly potent inhibitory activity against SDF-1-CXCR4 binding.
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Affiliation(s)
- Ryo Masuda
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Japan
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66
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van Oosten M, Crane LM, Bart J, van Leeuwen FW, van Dam GM. Selecting Potential Targetable Biomarkers for Imaging Purposes in Colorectal Cancer Using TArget Selection Criteria (TASC): A Novel Target Identification Tool. Transl Oncol 2011; 4:71-82. [PMID: 21461170 PMCID: PMC3069650 DOI: 10.1593/tlo.10220] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 10/23/2010] [Accepted: 11/01/2010] [Indexed: 12/19/2022] Open
Abstract
Peritoneal carcinomatosis (PC) of colorectal origin is associated with a poor prognosis. However, cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is available for a selected group of PC patients, which significantly increases overall survival rates up to 30%. As a consequence, there is substantial room for improvement. Tumor targeting is expected to improve the treatment efficacy of colorectal cancer (CRC) further through 1) more sensitive preoperative tumor detection, thus reducing overtreatment; 2) better intraoperative detection and surgical elimination of residual disease using tumor-specific intraoperative imaging; and 3) tumor-specific targeted therapeutics. This review focuses, in particular, on the development of tumor-targeted imaging agents. A large number of biomarkers are known to be upregulated in CRC. However, to date, no validated criteria have been described for the selection of the most promising biomarkers for tumor targeting. Such a scoring system might improve the selection of the correct biomarker for imaging purposes. In this review, we present the TArget Selection Criteria (TASC) scoring system for selection of potential biomarkers for tumor-targeted imaging. By applying TASC to biomarkers for CRC, we identified seven biomarkers (carcinoembryonic antigen, CXC chemokine receptor 4, epidermal growth factor receptor, epithelial cell adhesion molecule, matrix metalloproteinases, mucin 1, and vascular endothelial growth factor A) that seem most suitable for tumor-targeted imaging applications in colorectal cancer. Further cross-validation studies in CRC and other tumor types are necessary to establish its definitive value.
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Affiliation(s)
- Marleen van Oosten
- Department of Surgery, Division of Surgical Oncology, Surgical Research Laboratory/BioOptical Imaging Center, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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67
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Franzen S. A comparison of peptide and folate receptor targeting of cancer cells: from single agent to nanoparticle. Expert Opin Drug Deliv 2011; 8:281-98. [DOI: 10.1517/17425247.2011.554816] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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68
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Current molecular imaging positron emitting radiotracers in oncology. Nucl Med Mol Imaging 2011; 45:1-14. [PMID: 24899972 DOI: 10.1007/s13139-011-0075-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 01/21/2011] [Indexed: 12/21/2022] Open
Abstract
Molecular imaging is one of the fastest growing areas of medical imaging. Positron emission tomography (PET) has been widely used in the clinical management of patients with cancer. Nuclear imaging provides biological information at the cellular, subcellular, and molecular level in living subjects with non-invasive procedures. In particular, PET imaging takes advantage of traditional diagnostic imaging techniques and introduces positron-emitting probes to determine the expression of indicative molecular targets at different stages of cancer. (18)F-fluorodeoxyglucose ((18)F-FDG), the only FDA approved oncological PET tracer, has been widely utilized in cancer diagnosis, staging, restaging, and even monitoring response to therapy; however, (18)F-FDG is not a tumor-specific PET tracer. Over the last decade, many promising tumor-specific PET tracers have been developed and evaluated in preclinical and clinical studies. This review provides an overview of the current non-(18)F-FDG PET tracers in oncology that have been developed based on tumor characteristics such as increased metabolism, hyperproliferation, angiogenesis, hypoxia, apoptosis, and tumor-specific antigens and surface receptors.
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69
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Kuil J, Velders AH, van Leeuwen FWB. Multimodal tumor-targeting peptides functionalized with both a radio- and a fluorescent label. Bioconjug Chem 2011; 21:1709-19. [PMID: 20812730 DOI: 10.1021/bc100276j] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The use of monolabeled tumor-targeting peptides for molecular imaging is widespread. However, it is often desirable to use the same compound for different clinical applications, e.g., combined pre- and intraoperative tumor detection. On the basis of their detection sensitivity, the combination of radioactivity and fluorescence is probably the most valuable in multimodal molecular imaging. In this review, we compare multimodal peptide derivatives and discuss the influence of the diagnostic labels on receptor affinity and biodistribution. On the basis of the described constructs, we propose improvements for the design of future multimodal tumor-targeting peptide derivatives.
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Affiliation(s)
- Joeri Kuil
- Division of Diagnostic Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands
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Correia JDG, Paulo A, Raposinho PD, Santos I. Radiometallated peptides for molecular imaging and targeted therapy. Dalton Trans 2011; 40:6144-67. [DOI: 10.1039/c0dt01599g] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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71
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Abstract
UNLABELLED Expression of the chemokine receptor CXCR4 by cancers has been shown to correlate with tumor aggressiveness and poor prognosis and may also contribute to metastatic seeding of organs that express its ligand SDF-1. However, fully optimized PET agents for determining CXCR4 expression by tumor cells in vivo are not yet available. This study aims to develop a stable, (18)F-labeled peptide that enables in vivo quantification of CXCR4 in cancer. METHODS 4-F-benzoyl-TN14003 (4-F-T140), a short peptide antagonist of CXCR4 with 1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl protecting groups on the ε-amino groups of the lysine residues, was labeled with (18)F-fluoride via N-succinimidyl-4-(18)F-fluorobenzoate conjugation, followed by deprotection to give 4-(18)F-T140 that was exclusively labeled on the α-amine at the N terminus. Cell binding, migration, biodistribution, and small-animal PET studies of 4-(18)F-T140 were performed. RESULTS 4-F-T140 was radiolabeled by coupling with N-succinimidyl-4-(18)F-fluorobenzoate, with an overall decay-corrected radiochemical yield of 15% ± 5% calculated from the start of synthesis. The mean measured specific activity (±SD) was 7 ± 2 GBq/μmol (0.19 ± 0.05 Ci/μmol), and radiochemical purity was greater than 99%. 4-(18)F-T140 was found to bind specifically to red blood cells in vitro and in vivo. The binding of 4-(18)F-T140 to red blood cells was blocked with a small amount of cold 4-F-T140, which led to higher uptake of 4-(18)F-T140 by Chinese hamster ovarian (CHO)-CXCR4 tumors. Biodistribution experiments at 3 h after injection with the addition of 10 μg of cold 4-F-T140 showed a 3.03 ± 0.31 percentage injected dose per gram uptake in CHO-CXCR4 tumors, with a tumor-to-blood ratio of 27.1 ± 8.7 and a tumor-to-muscle ratio of 21.6 ± 7.1. PET studies demonstrated clear visualization of CXCR4-transfected, but not CXCR4-negative, CHO tumors. CONCLUSION 4-(18)F-T140 can be used as a PET tracer to image tumor expression of CXCR4, with a high tumor-to-background ratio. The knowledge of whether tumors express or do not express CXCR4 might be beneficial in determining appropriate treatment and monitoring.
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Affiliation(s)
- Orit Jacobson
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland
| | - Ido D. Weiss
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Dale O. Kiesewetter
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland
| | - Joshua M. Farber
- Laboratory of Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Xiaoyuan Chen
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland
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72
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Narumi T, Ochiai C, Yoshimura K, Harada S, Tanaka T, Nomura W, Arai H, Ozaki T, Ohashi N, Matsushita S, Tamamura H. CD4 mimics targeting the HIV entry mechanism and their hybrid molecules with a CXCR4 antagonist. Bioorg Med Chem Lett 2010; 20:5853-8. [DOI: 10.1016/j.bmcl.2010.07.106] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 07/22/2010] [Accepted: 07/26/2010] [Indexed: 11/24/2022]
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73
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Lee S, Xie J, Chen X. Peptides and peptide hormones for molecular imaging and disease diagnosis. Chem Rev 2010; 110:3087-111. [PMID: 20225899 DOI: 10.1021/cr900361p] [Citation(s) in RCA: 253] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Seulki Lee
- Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 31 Center Drive, Suite 1C14, Bethesda, Maryland 20892-2281, USA
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74
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Nimmagadda S, Pullambhatla M, Stone K, Green G, Bhujwalla ZM, Pomper MG. Molecular imaging of CXCR4 receptor expression in human cancer xenografts with [64Cu]AMD3100 positron emission tomography. Cancer Res 2010; 70:3935-44. [PMID: 20460522 DOI: 10.1158/0008-5472.can-09-4396] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The chemokine receptor CXCR4 and its cognate ligand CXCL12 are pivotal for establishing metastases from many tumor types. Thus, CXCR4 may offer a cell surface target for molecular imaging of metastases, assisting diagnosis, staging, and therapeutic monitoring. Furthermore, noninvasive detection of CXCR4 status of a primary tumor may provide an index of the metastatic potential of the lesion. Here, we report the development and evaluation of [(64)Cu]AMD3100, a positron-emitting analogue of the stem cell mobilizing agent plerixafor to image CXCR4 in human tumor xenografts preselected for graded expression of this receptor. This imaging method was evaluated in lung metastases derived from human MDA-MB-231 breast cancer cells. Ex vivo biodistribution studies, performed to validate the in vivo imaging data, confirmed the ability of [(64)Cu]AMD3100 to image CXCR4 expression. Our findings show the feasibility of imaging CXCR4 by positron emission tomography using a clinically approved agent as a molecular scaffold.
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Affiliation(s)
- Sridhar Nimmagadda
- Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland 21231, USA.
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75
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Abstract
Targeted molecular imaging techniques have become indispensable tools in modern diagnostics because they provide accurate and specific diagnosis of disease information. Conventional nonspecific contrast agents suffer from low targeting efficiency; thus, the use of molecularly targeted imaging probes is needed depending on different imaging modalities. Although recent technologies have yielded various strategies for designing smart probes, utilization of peptide-based probes has been most successful. Phage display technology and combinatorial peptide chemistry have profoundly impacted the pool of available targeting peptides for the efficient and specific delivery of imaging labels. To date, selected peptides that target a variety of disease-related receptors and biomarkers are in place. These targeting peptides can be coupled with the appropriate imaging moieties or nanoplatforms on demand with the help of sophisticated bioconjugation or radiolabeling techniques. This review article examines the current trends in peptide-based imaging probes developed for in vivo applications. We discuss the advantage of and challenges in developing peptide-based probes and summarize current systems with respect to their unique design strategies and applications.
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Affiliation(s)
- Seulki Lee
- Laboratory for Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 31 Center Drive, Suite 1C14, Bethesda, Maryland 20892-2281, USA
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76
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Synthesis and preliminary evaluation of a novel 125I-labeled T140 analog for quantitation of CXCR4 expression. J Radioanal Nucl Chem 2010. [DOI: 10.1007/s10967-010-0484-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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77
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Nimmagadda S, Pullambhatla M, Pomper MG. Immunoimaging of CXCR4 expression in brain tumor xenografts using SPECT/CT. J Nucl Med 2009; 50:1124-30. [PMID: 19525448 DOI: 10.2967/jnumed.108.061325] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
UNLABELLED Chemokine receptor 4 (CXCR4) is expressed in a variety of cancers, including breast, brain, ovarian, and prostate. CXCR4-CXCL12 interactions are critical for tumor development, growth, and metastasis. Compared with normal tissue, neoplastic tissue (including metastases) expresses high levels of CXCR4. Previous clinical and preclinical observations suggest that CXCR4 levels could be used as a predictive marker of metastatic potential. Here we report the results of SPECT/CT of CXCR4 expression levels in experimental brain tumors using (125)I-labeled anti-CXCR4 monoclonal antibodies (mAbs). METHODS hCXCR4 antibody 12G5 and control IgG(2A) antibody were radiolabeled. Radio-mAbs were obtained in 40%-60% yield, with 1.4-1.9 MBq/microg specific radioactivities and greater than 95% purity. Severe combined immunodeficient mice harboring U87 xenografts were used for ex vivo biodistribution and imaging studies. Surface CXCR4 expression levels on U87 tumor-derived cells were analyzed by flow cytometry. RESULTS Biodistribution and imaging studies showed a specific accumulation of (125)I-12G5 in U87 tumors, with tumor-to-muscle uptake ratios reaching 15 +/- 3 at 48 h after injection. The tumor-to-tumor uptake ratio for (125)I-12G5 and (125)I-IgG(2A) was 2.5 at 48 h after injection. Flow cytometry analysis of tumor-derived cells showed a 2- to 7-fold increase in CXCR4 expression relative to inoculums, accounting for the high mAb uptake observed in the tumors. CONCLUSION Our data demonstrate the feasibility of imaging CXCR4 expression in experimental brain tumors. The elevated CXCR4 levels observed may have been, in part, due to the hypoxic tumor microenvironment.
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Affiliation(s)
- Sridhar Nimmagadda
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA
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78
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Schottelius M, Wester HJ. Molecular imaging targeting peptide receptors. Methods 2009; 48:161-77. [DOI: 10.1016/j.ymeth.2009.03.012] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 03/11/2009] [Indexed: 02/08/2023] Open
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79
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Jacobson O, Weiss ID, Szajek L, Farber JM, Kiesewetter DO. 64Cu-AMD3100--a novel imaging agent for targeting chemokine receptor CXCR4. Bioorg Med Chem 2009; 17:1486-93. [PMID: 19188071 DOI: 10.1016/j.bmc.2009.01.014] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/07/2009] [Accepted: 01/09/2009] [Indexed: 10/21/2022]
Abstract
CXCR4 is a chemokine receptor which has been shown to be exploited by various tumors for increased survival, invasion, and homing to target organs. We developed a one step radiosynthesis for labeling the CXCR4-specific antagonist AMD3100 with Cu-64 to produce (64)Cu-AMD3100 with a specific activity of 11.28Ci/ micromol (417GBq/ micromol) at the end of radiosynthesis. Incorporation of Cu(II) ion into AMD3100 did not change its ability to inhibit cellular migration in response to the (only) CXCR4 ligand, SDF-1/CXCL12. (64)Cu-AMD3100 binding affinity to CXCR4 was found to be 62.7 microM. Biodistribution of (64)Cu-AMD3100 showed accumulation in CXCR4-expressing organs and tissues, a renal clearance pathway, and an anomalous specific accumulation in the liver. We conclude that (64)Cu-AMD3100 exhibits promise as a potential PET imaging agent for visualization of CXCR4-positive tumors and metastases and might be used to guide and monitor anti-CXCR4 tumor therapy.
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Affiliation(s)
- Orit Jacobson
- Positron Emission Tomography Radiochemistry Group, National Institute of Biomedical Imaging and Bioengineering, Bethesda, MD 20892, USA
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80
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Shim H, Oishi S, Fujii N. Chemokine receptor CXCR4 as a therapeutic target for neuroectodermal tumors. Semin Cancer Biol 2008; 19:123-34. [PMID: 19084067 DOI: 10.1016/j.semcancer.2008.11.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/17/2008] [Accepted: 11/17/2008] [Indexed: 12/20/2022]
Abstract
Chemokines (chemotactic cytokines) are a family of proteins associated with the trafficking and activation of leukocytes and other cell types in immune surveillance and inflammatory response. Besides their roles in the immune system, they play pleiotropic roles in tumor initiation, promotion, and progression. Chemokines can be classified into four subfamilies of chemokines, CXC, CC, C, or CX3C, based on their number and spacing of conserved cysteine residues near the N-terminus. This CXC subfamily can be further subclassified into two groups, depending on the presence or absence of a tripeptide motif glutamic acid-leucine-arginine (ELR) in the N-terminal domain. ELR(-)CXCL12, which binds to CXCR4 has been frequently implicated in various cancers. Over the past several years, studies have increasingly shown that the CXCR4/CXCL12 axis plays critical roles in tumor progression, such as invasion, angiogenesis, survival, homing to metastatic sites. This review focuses on involvement of CXCR4/CXCL12 interaction in neuroectodermal cancers and their therapeutic potentials. As an attractive therapeutic target of CXCR4/CXCL12 axis for cancer chemotherapy, development history and application of CXCR4 antagonists are described.
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Affiliation(s)
- Hyunsuk Shim
- Department of Radiology, Emory University, Atlanta, GA 30322, USA
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81
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Nomura W, Tanabe Y, Tsutsumi H, Tanaka T, Ohba K, Yamamoto N, Tamamura H. Fluorophore labeling enables imaging and evaluation of specific CXCR4-ligand interaction at the cell membrane for fluorescence-based screening. Bioconjug Chem 2008; 19:1917-20. [PMID: 18707146 DOI: 10.1021/bc800216p] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Development of CXCR4-specific ligands is an important issue in chemotherapy of HIV infection, cancer metastasis, and rheumatoid arthritis, and numerous potential ligands have been developed to date. However, it is difficult to assess their binding mode and specificity because of uncertainties in the structure of the CXCR4-ligand complexes. To address this problem, we have synthesized fluorophore labeled Ac-TZ14011, which is derived from T140, a powerful CXCR4 antagonist. Binding of Ac-TZ14011 to CXCR4 on the cell membrane was observed by fluorescence microscope, and analysis of the binding data produced IC 50 values of several ligands comparable to those obtained in RI-based assays. This fluorescence-based assay is applicable to explore new pharmacophores of CXCR4-specific ligands with high-throughput screening and also to screening of the other GPCR binding ligands.
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Affiliation(s)
- Wataru Nomura
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Chiyoda-ku, Tokyo 101-0062, Japan
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82
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Winnard PT, Pathak AP, Dhara S, Cho SY, Raman V, Pomper MG. Molecular imaging of metastatic potential. J Nucl Med 2008; 49 Suppl 2:96S-112S. [PMID: 18523068 DOI: 10.2967/jnumed.107.045948] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
If molecular imaging is to prove clinically useful it will have to surpass current, primarily anatomic techniques in terms of sensitivity and the ability to detect minimal changes in tissue. One of the most important tests for molecular imaging is to determine whether it can image the metastatic potential of tumors. Like all predictive endeavors, the imaging of such "potential" is a daunting task, but one that only molecular imaging--rather than standard, anatomic techniques--is likely to solve. Although difficult, imaging of metastatic potential is also arguably the most important task for molecular imaging of cancer because it is generally the dissemination of malignant tissue, not its prolonged residence in an inopportune site, which kills the patient. Below are examples of uses of molecular imaging of metastases as well as of metastatic potential, the former being a far more developed area of clinical inquiry.
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Affiliation(s)
- Paul T Winnard
- Russell H Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore 21231, Maryland, USA
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83
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Oishi S, Masuda R, Evans B, Ueda S, Goto Y, Ohno H, Hirasawa A, Tsujimoto G, Wang Z, Peiper SC, Naito T, Kodama E, Matsuoka M, Fujii N. Synthesis and application of fluorescein- and biotin-labeled molecular probes for the chemokine receptor CXCR4. Chembiochem 2008; 9:1154-8. [PMID: 18412193 DOI: 10.1002/cbic.200700761] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The design, synthesis, and bioevaluation of fluorescence- and biotin-labeled CXCR4 antagonists are described. The modification of D-Lys8 at an epsilon-amino group in the peptide antagonist Ac-TZ14011 derived from polyphemusin II had no significant influence on the potent binding of the peptide to the CXCR4 receptor. The application of the labeled peptides in flow cytometry and confocal microscopy studies demonstrated the selectivity of their binding to the CXCR4 receptor, but not to CXCR7, which was recently reported to be another receptor for stromal cell-derived factor 1 (SDF-1)/CXCL12.
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Affiliation(s)
- Shinya Oishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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84
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Abstract
Due to their favorable properties and pharmacokinetics, peptides are often regarded as "agents of choice" for imaging and radiotherapy. Chemical strategies have been developed that allow their site specific labeling with various radionuclides for PET and SPECT, without compromising their biological integrity. Together with the overexpression of a wide range of peptide receptors and binding sites on tumor cells or matrix components, this class of compounds offers multiple imaging applications. Furthermore, radiolabeled peptides have great potential as carrier molecules for site-specific delivery of other signalling units, such as fluorescent moieties, cyctotoxic compounds or metals for magnetic resonance imaging. In addition, great efforts have been made to exploit the favorable characteristics of peptides for the development of larger constructs, such as multimeric ligands, polymer-peptide conjugates and "peptide-coated" liposomes and nanoparticles. Some peptides have already entered clinical routine application; some are currently being evaluated in clinical studies. However, a variety of peptides is still "waiting" to enter the imaging arena. This chapter presents a brief overview of the highly active field of peptide radiopharmaceuticals and the future potential of multimeric and polymeric peptide constructs.
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Affiliation(s)
- I Dijkraaf
- Department of Nuclear Medicine, Technische Universität München, Ismaninger Strasse 22, 81675 München, Germany
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85
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Abstract
PURPOSE OF REVIEW To describe advances in the development of biomarkers for pancreatic cancer over the past year. RECENT FINDINGS Several new approaches were taken in the search for biomarkers for pancreatic cancer. Studies of CA19-9 revealed new prognostic abilities of the already well known biomarker. New blood biomarkers were investigated and CEACAM1 and MIC-1 were found to be superior to CA19-9 at distinguishing cancer from normal but, unfortunately, not from chronic pancreatitis. MUC1 was reported to be superior to CA19-9 based on the use of a novel immunoassay. The superiority of the concept of a panel of biomarkers as opposed to single biomarkers was supported by several studies, but no such panel was identified. RNA levels in blood and DNA methylation in pancreatic juice yielded some promising findings. Advancements were also made in the area of tissue biomarkers, which can improve the diagnostic accuracy of fine-needle aspirations and provide prognostic information. A new source of potential biomarkers, microRNAs, also made its debut in the past year. SUMMARY The tools to identify pancreatic-cancer biomarkers and sources of samples needed in this search are expanding. The field has not yet achieved its aims, but several encouraging breakthroughs have been made.
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Affiliation(s)
- Tobias Grote
- Department of Cancer Biology, University of Texas, M.D. Anderson Cancer Center, Houston, Texas, USA
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86
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Arya M, Ahmed H, Silhi N, Williamson M, Patel HRH. Clinical importance and therapeutic implications of the pivotal CXCL12-CXCR4 (chemokine ligand-receptor) interaction in cancer cell migration. Tumour Biol 2007; 28:123-31. [PMID: 17510563 DOI: 10.1159/000102979] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Accepted: 12/01/2006] [Indexed: 12/20/2022] Open
Abstract
Chemokines are small, secreted proteins and are now the largest known cytokine family. They mediate their effects through a family of G-protein-coupled receptors and were initially recognized for their ability to act as chemo-attractants and activators of specific types of leucocytes in a variety of immune and inflammatory responses. However, during the past 5 years there has been a chemokine revolution in cancer and all scientists and clinicians in oncology-related fields are now aware of their crucial role at all stages of neoplastic transformation and progression. The most important chemokine ligand-receptor interaction is that of the CXCL12 (stromal cell-derived factor-1, SDF-1) ligand with its exclusive receptor CXCR4; this interaction has a pivotal role in the directional migration of cancer cells during the metastatic process. This has been demonstrated by in vitro and in vivo experiments in addition to retrospective clinical studies. These findings have exciting implications in the field of cancer therapeutics, with several small molecule CXCR4 antagonists having been developed, which may provide clinical benefit in the therapy of cancer metastasis. Interestingly, it is likely that the effect of the anti-HER2 antibody [trastuzumab (Herceptin] in breast cancer involves downregulation of the CXCR4 receptor. Unfortunately, a major problem is that chemokine receptors are expressed in other cells within the body, particularly those of the immune system and it is not clear what effects long-term CXCR4 antagonism could have on innate and adaptive immunity. However, there is little doubt that the great strides made in elucidating the complex relationship between chemokines and their role in cancer will soon translate into significant survival benefits for patients.
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