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Al-Jamaei AAH, Subramanyam RV, Helder MN, Forouzanfar T, van der Meij EH, Al-Jamei S, de Visscher JGAM. A narrative review of the role of Eph receptors in head and neck squamous cell carcinoma. Oral Dis 2024; 30:833-845. [PMID: 37279081 DOI: 10.1111/odi.14625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 05/10/2023] [Accepted: 05/18/2023] [Indexed: 06/08/2023]
Abstract
Tyrosine kinase receptors (TKR) coordinate a variety of pathological processes in head and neck squamous cell carcinoma (HNSCC), and eventually play a role in patient outcomes. In this review, the role of Eph receptors in HNSCC progression and the possibility of targeting these receptors are illustrated. All relevant studies were identified through a comprehensive search of four electronic databases, including PubMed, Scopus, web of science, and Embase till August 2022. EphA2 and EphB4, along with ephrin-B2, were the most extensively studied proteins in this family. However, overexpression of EphB4 and its ligand ephrin-B2 were the only proteins that consistently showed association with a poor outcome, indicating that these proteins might serve as valuable prognostic markers in HNSCC. High expression of EphA3 and EphB4 was found to play a crucial role in radioresistance of HNSCC. EphB4 loss, in particular, was observed to induce an immunosuppression phenotypic HNSCC. Currently, ongoing clinical trials are investigating the benefits of EphB4-ephrin-B2 blockade in combination with standard of care treatment in HNSCC. Further efforts are needed to explore the biological role and behavioral complexity of this family of TKR in HNSCC with great attention to avoid heterogeneity of HNSCC subsites.
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Affiliation(s)
- Aisha A H Al-Jamaei
- Department of Oral and Maxillofacial Surgery/Oral Pathology, AmsterdamUMC-location VUmc/Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
- Department of Oral Surgery and Oral Medicine, Collage of Dentistry, Al-Razi University, Sana'a, Yemen
| | | | - Marco N Helder
- Department of Oral and Maxillofacial Surgery/Oral Pathology, AmsterdamUMC-location VUmc/Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
| | - Tymour Forouzanfar
- Department of Oral and Maxillofacial Surgery/Oral Pathology, AmsterdamUMC-location VUmc/Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
- Department of Oral and Maxillofacial Surgery, Leiden University Medical Centre (LUMC), Leiden, The Netherlands
| | - Erik H van der Meij
- Department of Oral and Maxillofacial Surgery/Oral Pathology, AmsterdamUMC-location VUmc/Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
- Department of Oral and Maxillofacial Surgery, Medical Centre Leeuwarden, Leeuwarden, The Netherlands
| | - Sayida Al-Jamei
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus TU, Dresden and Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Jan G A M de Visscher
- Department of Oral and Maxillofacial Surgery/Oral Pathology, AmsterdamUMC-location VUmc/Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands
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Oh ST, Yang KJ, Bae JM, Park HJ, Yoo DS, Park YM. The differential expression of EPHB4 and ephrin B2 in cutaneous squamous cell carcinoma according to the grade of tumor differentiation: a clinicopathological study. Int J Dermatol 2021; 60:736-741. [PMID: 33598934 DOI: 10.1111/ijd.15445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 12/23/2020] [Accepted: 01/11/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND EPHB4 and its ligand, ephrin B2, which are receptor tyrosine kinases of the erythropoietin-producing hepatocellular (EPH) family, are known to be linked to several human cancers. The aim of this study was to investigate their expression patterns in cutaneous squamous cell carcinoma (CSCC) in association with tumor differentiation and other variable clinical characteristics. MATERIALS AND METHODS Immunohistochemical staining for EPHB4 and ephrin B2 was performed in 32 cases of CSCC with different histologic grades. The clinical characteristics and histologic grades of CSCC were evaluated in association with EPHB4 and ephrin B2 expression patterns. RESULTS EPHB4 and ephrin B2 expression levels were significantly inversely proportional to the grade of differentiation of CSCC (P < 0.001 and P < 0.001, respectively). CONCLUSION These results indicated that EPHB4 and ephrin B2 can be useful markers for poorly differentiated CSCC.
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Affiliation(s)
- Shin Taek Oh
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Keum Jin Yang
- Clinical Research Institute, Daejeon St. Mary's Hospital, Daejeon, Korea
| | | | - Hyun Jeong Park
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Dong Soo Yoo
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Young Min Park
- Department of Dermatology, College of Medicine, The Catholic University of Korea, Seoul, Korea
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Wang Q, Liu Y, Zhao Y, Sun LZ, Wang LX, Han M, Mi FL. [Research progress on the expression and function of erythropoietin-producing hepatomocellular receptors and their receptor-interacting proteins in oral-related diseases]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2020; 38:218-223. [PMID: 32314898 DOI: 10.7518/hxkq.2020.02.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Erythropoietin-producing hepatomocellular receptors and their receptor-interacting proteins (Eph/ephrin) can participate in the regulation of growth and development and promote the development of diseases through short-distance signal transduction between cells. To study the mechanism of Eph/ephrin and oral-related diseases, we provided a new theoretical basis and a strategy for the treatment of oral diseases. The Eph/ephrin pathway has been used to regulate oral diseases, especially in periodontal disease prevention, orthodontic bone reconstruction, and biological treatment of oral tumors. This paper reviews the research progress of Eph/ephrin pathway in oral-related diseases.
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Affiliation(s)
- Qi Wang
- Dept. of Stomatology, North Sichuan Medical College, Nanchong 637000, China
| | - Yan Liu
- Dept. of Prosthodontics, the Affiliated Hospital of North Sichuan Medical College, Nanchong 637000, China
| | - Yun Zhao
- Dept. of Stomatology, North Sichuan Medical College, Nanchong 637000, China
| | - Li-Zhong Sun
- Dept. of Stomatology, North Sichuan Medical College, Nanchong 637000, China
| | - Lin-Xuan Wang
- Dept. of Stomatology, North Sichuan Medical College, Nanchong 637000, China
| | - Mei Han
- Dept. of Stomatology, North Sichuan Medical College, Nanchong 637000, China
| | - Fang-Lin Mi
- Dept. of Stomatology, North Sichuan Medical College, Nanchong 637000, China
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Bhatia S, Oweida A, Lennon S, Darragh LB, Milner D, Phan AV, Mueller AC, Van Court B, Raben D, Serkova NJ, Wang XJ, Jimeno A, Clambey ET, Pasquale EB, Karam SD. Inhibition of EphB4-Ephrin-B2 Signaling Reprograms the Tumor Immune Microenvironment in Head and Neck Cancers. Cancer Res 2019; 79:2722-2735. [PMID: 30894369 PMCID: PMC6522285 DOI: 10.1158/0008-5472.can-18-3257] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/15/2019] [Accepted: 03/14/2019] [Indexed: 12/26/2022]
Abstract
Identifying targets present in the tumor microenvironment that contribute to immune evasion has become an important area of research. In this study, we identified EphB4-ephrin-B2 signaling as a regulator of both innate and adaptive components of the immune system. EphB4 belongs to receptor tyrosine kinase family that interacts with ephrin-B2 ligand at sites of cell-cell contact, resulting in bidirectional signaling. We found that EphB4-ephrin-B2 inhibition alone or in combination with radiation (RT) reduced intratumoral regulatory T cells (Tregs) and increased activation of both CD8+ and CD4+Foxp3- T cells compared with the control group in an orthotopic head and neck squamous cell carcinoma (HNSCC) model. We also compared the effect of EphB4-ephrin-B2 inhibition combined with RT with combined anti-PDL1 and RT and observed similar tumor growth suppression, particularly at early time-points. A patient-derived xenograft model showed reduction of tumor-associated M2 macrophages and favored polarization towards an antitumoral M1 phenotype following EphB4-ephrin-B2 inhibition with RT. In vitro, EphB4 signaling inhibition decreased Ki67-expressing Tregs and Treg activation compared with the control group. Overall, our study is the first to implicate the role of EphB4-ephrin-B2 in tumor immune response. Moreover, our findings suggest that EphB4-ephrin-B2 inhibition combined with RT represents a potential alternative for patients with HNSCC and could be particularly beneficial for patients who are ineligible to receive or cannot tolerate anti-PDL1 therapy. SIGNIFICANCE: These findings present EphB4-ephrin-B2 inhibition as an alternative to anti-PDL1 therapeutics that can be used in combination with radiation to induce an effective antitumor immune response in patients with HNSCC.
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Affiliation(s)
- Shilpa Bhatia
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Ayman Oweida
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Shelby Lennon
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Laurel B Darragh
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Dallin Milner
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Andy V Phan
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Adam C Mueller
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Benjamin Van Court
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - David Raben
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Natalie J Serkova
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Xiao-Jing Wang
- Department of Pathology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
- Veterans Affairs Medical Center, VA Eastern Colorado Health Care System, Aurora, Colorado
| | - Antonio Jimeno
- Division of Medical Oncology, Department of Medicine, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Eric T Clambey
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Elena B Pasquale
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Sana D Karam
- Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
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Salgia R, Kulkarni P, Gill PS. EphB4: A promising target for upper aerodigestive malignancies. Biochim Biophys Acta Rev Cancer 2018; 1869:128-137. [PMID: 29369779 PMCID: PMC5955724 DOI: 10.1016/j.bbcan.2018.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/11/2018] [Accepted: 01/11/2018] [Indexed: 12/14/2022]
Abstract
The erythropoietin-producing hepatocellular carcinoma (Eph) receptors are the largest family of receptor tyrosine kinases (RTKs) that include two major subclasses, EphA and EphB. They form an important cell communication system with critical and diverse roles in a variety of biological processes during embryonic development. However, dysregulation of the Eph/ephrin interactions is implicated in cancer contributing to tumour growth, metastasis, and angiogenesis. Here, we focus on EphB4 and review recent developments in elucidating its role in upper aerodigestive malignancies to include lung cancer, head and neck cancer, and mesothelioma. In particular, we summarize information regarding EphB4 structure/function and role in disease pathobiology. We also review the data supporting EphB4 as a potential pharmacological and immunotherapy target and finally, progress in the development of new therapeutic strategies including small molecule inhibitors of its activity is discussed. The emerging picture suggests that EphB4 is a valuable and attractive therapeutic target for upper aerodigestive malignancies.
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MESH Headings
- Animals
- Antineoplastic Agents/therapeutic use
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Squamous Cell/drug therapy
- Carcinoma, Squamous Cell/genetics
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/pathology
- Gene Expression Regulation, Neoplastic
- Head and Neck Neoplasms/drug therapy
- Head and Neck Neoplasms/genetics
- Head and Neck Neoplasms/metabolism
- Head and Neck Neoplasms/pathology
- Humans
- Lung Neoplasms/drug therapy
- Lung Neoplasms/genetics
- Lung Neoplasms/metabolism
- Lung Neoplasms/pathology
- Mesothelioma/drug therapy
- Mesothelioma/genetics
- Mesothelioma/metabolism
- Mesothelioma/pathology
- Mesothelioma, Malignant
- Molecular Targeted Therapy
- Receptor, EphB4/antagonists & inhibitors
- Receptor, EphB4/genetics
- Receptor, EphB4/metabolism
- Signal Transduction
- Squamous Cell Carcinoma of Head and Neck
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Affiliation(s)
- Ravi Salgia
- Department of Medical Oncology & Therapeutics Research, City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA, United States.
| | - Prakash Kulkarni
- Department of Medical Oncology & Therapeutics Research, City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA, United States
| | - Prakash S Gill
- Department of Medicine, Division of Medical Oncology, University of Southern California, Los Angeles, CA, United States
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Sasabe E, Tomomura A, Tomita R, Sento S, Kitamura N, Yamamoto T. Ephrin-B2 reverse signaling regulates progression and lymph node metastasis of oral squamous cell carcinoma. PLoS One 2017; 12:e0188965. [PMID: 29190834 PMCID: PMC5708812 DOI: 10.1371/journal.pone.0188965] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 11/16/2017] [Indexed: 01/06/2023] Open
Abstract
Oral squamous cell carcinoma (OSCC) is a common malignant tumor of the head and neck and frequently metastasizes to cervical lymph nodes. Aggressive local invasion and metastasis of OSCC are significant factors for poor prognosis. In this study, we investigated whether ephrin-B2 expressed in OSCC contributed to tumor progression and lymph node metastasis. Clinical specimens from patients with OSCC had robust ephrin-B2-positive tumor cells and ephrin-B2 protein level was associated with clinical stage, lymph node metastasis, and poor survival outcomes. We also determined that ephrin-B2 protein level was increased in OSCC cell lines compared to normal human oral keratinocytes and that its levels were associated with the migratory and invasive potential of OSCC cell lines. Transfection of an EFNB2-specific small interfering RNA (siRNA) into SAS-L1 cells significantly reduced proliferation, attachment, migration, and invasion through phosphorylation of the epidermal growth factor receptor, FAK, ERK1/2, p38, AKT, and JNK1/2 pathways. Furthermore, knockdown of EFNB2 significantly suppressed adhesion and transmigration of SAS-L1 cells toward human lymphatic endothelial cells. In addition, the growth rate of tumor xenografts and cervical lymph node metastases of OSCC were suppressed by local injection of EFNB2 siRNA. These results suggest that ephrin-B2 overexpression and activation of the ephrin-B2 reverse signaling pathway in tumor microenvironment in OSCC facilitates progression and lymph node metastasis via enhancement of malignant potential and interaction with surrounding cells.
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Affiliation(s)
- Eri Sasabe
- Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku-city, Kochi, Japan
- * E-mail:
| | - Ayumi Tomomura
- Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku-city, Kochi, Japan
| | - Riki Tomita
- Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku-city, Kochi, Japan
| | - Shinya Sento
- Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku-city, Kochi, Japan
| | - Naoya Kitamura
- Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku-city, Kochi, Japan
| | - Tetsuya Yamamoto
- Department of Oral and Maxillofacial Surgery, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku-city, Kochi, Japan
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Enhancing radiosensitization in EphB4 receptor-expressing Head and Neck Squamous Cell Carcinomas. Sci Rep 2016; 6:38792. [PMID: 27941840 PMCID: PMC5150255 DOI: 10.1038/srep38792] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 11/11/2016] [Indexed: 12/14/2022] Open
Abstract
Members of the Eph family of receptor tyrosine kinases have been implicated in a wide array of human cancers. The EphB4 receptor is ubiquitously expressed in head and neck squamous cell carcinoma (HNSCC) and has been shown to impart tumorigenic and invasive characteristics to these cancers. In this study, we investigated whether EphB4 receptor targeting can enhance the radiosensitization of HNSCC. Our data show that EphB4 is expressed at high to moderate levels in HNSCC cell lines and patient-derived xenograft (PDX) tumors. We observed decreased survival fractions in HNSCC cells following EphB4 knockdown in clonogenic assays. An enhanced G2 cell cycle arrest with activation of DNA damage response pathway and increased apoptosis was evident in HNSCC cells following combined EphB4 downregulation and radiation compared to EphB4 knockdown and radiation alone. Data using HNSCC PDX models showed significant reduction in tumor volume and enhanced delay in tumor regrowth following sEphB4-HSA administration with radiation compared to single agent treatment. sEphB4-HSA is a protein known to block the interaction between the EphB4 receptor and its ephrin-B2 ligand. Overall, our findings emphasize the therapeutic relevance of EphB4 targeting as a radiosensitizer that can be exploited for the treatment of human head and neck carcinomas.
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Dimasi N, Fleming R, Hay C, Woods R, Xu L, Wu H, Gao C. Development of a Trispecific Antibody Designed to Simultaneously and Efficiently Target Three Different Antigens on Tumor Cells. Mol Pharm 2015; 12:3490-501. [PMID: 26176328 DOI: 10.1021/acs.molpharmaceut.5b00268] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Targeting Eph (erythropoietin producing hepatoma) receptors with monoclonal antibodies is being explored as therapy for several types of cancer. To test whether simultaneous targeting of EphA2, EphA4, and EphB4 would be an effective approach to cancer therapy, we generated a recombinant trispecific antibody using the variable domain genes of anti-EphA2, anti-EphA4, and anti-EphB4 monoclonal antibodies. A multidisciplinary approach combining biochemical, biophysical, and cellular-based assays was used to characterize the trispecific antibody in vitro and in vivo. Here we demonstrate that the trispecific antibody is expressed at high levels by mammalian cells, monodispersed in solution, thermostable, capable of simultaneously binding the three receptors, and able to activate the three targets effectively as evidenced by receptor internalization and degradation both in vitro and in vivo. Furthermore, pharmacokinetic analysis using tumor-bearing nude mice showed that the trispecific antibody remains in the circulation similarly to its respective parental antibodies. These results indicate that simultaneous blockade of EphA2, EphA4, and EphB4 could be an attractive approach to cancer therapy.
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Affiliation(s)
- Nazzareno Dimasi
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
| | - Ryan Fleming
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
| | - Carl Hay
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
| | - Rob Woods
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
| | - Linda Xu
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
| | - Herren Wu
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
| | - Changshou Gao
- Antibody Discovery and Protein Engineering and ‡Oncology Research, MedImmune , Gaithersburg, Maryland 20878, United States
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Ebert K, Wiemer J, Caballero J, Köckerling M, Steinbach J, Pietzsch J, Mamat C. Development of indazolylpyrimidine derivatives as high-affine EphB4 receptor ligands and potential PET radiotracers. Bioorg Med Chem 2015; 23:6025-35. [PMID: 26189032 DOI: 10.1016/j.bmc.2015.06.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 01/06/2023]
Abstract
Due to their essential role in the pathogenesis of cancer, members of the Eph (erythropoietin-producing hepatoma cell line-A2) receptor tyrosine kinase family represent promising candidates for molecular imaging. Thus, the development and preparation of novel radiotracers for the noninvasive imaging of the EphB4 receptor via positron emission tomography (PET) is described. First in silico investigations with the indazolylpyrimidine lead compound which is known to be highly affine to EphB4 were executed to identify favorable labeling positions for an introduction of fluorine-18 to retain the affinity. Based on this, reference compounds as well as precursors were developed and labeled with carbon-11 and fluorine-18, respectively. For this purpose, a protecting group strategy essentially had to be generated to prevent unwanted methylation and to enable the introduction of fluorine-18. Further, a convenient radiolabeling strategy using [(11)C]methyl iodide was established which afforded the isotopically labeled radiotracer in 30-35% RCY (d.c.) which is identical with the original inhibitor molecule. A spiro ammonium precursor was prepared for radiolabeling with fluorine-18. Unfortunately, the labeling did not lead to the desired (18)F-radiotracer under the chosen conditions.
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Affiliation(s)
- Kristin Ebert
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Jens Wiemer
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany
| | - Julio Caballero
- Universidad de Talca, Centro de Bioinformática y Simulación Molecular, 2 Norte 685, Casilla 721, Talca, Chile
| | - Martin Köckerling
- Universität Rostock, Institut für Chemie, Anorganische Festkörperchemie, Albert-Einstein-Straße 3a, D-18057 Rostock, Germany
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany; TU Dresden, Fachbereich Chemie und Lebensmittelchemie, D-01062 Dresden, Germany
| | - Jens Pietzsch
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany; TU Dresden, Fachbereich Chemie und Lebensmittelchemie, D-01062 Dresden, Germany
| | - Constantin Mamat
- Helmholtz-Zentrum Dresden-Rossendorf, Institut für Radiopharmazeutische Krebsforschung, Bautzner Landstraße 400, D-01328 Dresden, Germany; TU Dresden, Fachbereich Chemie und Lebensmittelchemie, D-01062 Dresden, Germany.
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