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Hickerson BT, Daniels-Wells TR, Payes C, Clark LE, Candelaria PV, Bailey KW, Sefing EJ, Zink S, Ziegenbein J, Abraham J, Helguera G, Penichet ML, Gowen BB. Host receptor-targeted therapeutic approach to counter pathogenic New World mammarenavirus infections. Nat Commun 2022; 13:558. [PMID: 35091550 PMCID: PMC8799657 DOI: 10.1038/s41467-021-27949-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 12/22/2021] [Indexed: 12/25/2022] Open
Abstract
Five New World mammarenaviruses (NWMs) cause life-threatening hemorrhagic fever (HF). Cellular entry by these viruses is mediated by human transferrin receptor 1 (hTfR1). Here, we demonstrate that an antibody (ch128.1/IgG1) which binds the apical domain of hTfR1, potently inhibits infection of attenuated and pathogenic NWMs in vitro. Computational docking of the antibody Fab crystal structure onto the known structure of hTfR1 shows an overlapping receptor-binding region shared by the Fab and the viral envelope glycoprotein GP1 subunit that binds hTfR1, and we demonstrate competitive inhibition of NWM GP1 binding by ch128.1/IgG1 as the principal mechanism of action. Importantly, ch128.1/IgG1 protects hTfR1-expressing transgenic mice against lethal NWM challenge. Additionally, the antibody is well-tolerated and only partially reduces ferritin uptake. Our findings provide the basis for the development of a novel, host receptor-targeted antibody therapeutic broadly applicable to the treatment of HF of NWM etiology.
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MESH Headings
- A549 Cells
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/pharmacology
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Arenaviridae/drug effects
- Arenaviridae/metabolism
- Arenaviridae/physiology
- Chlorocebus aethiops
- Hemorrhagic Fever, American/metabolism
- Hemorrhagic Fever, American/prevention & control
- Hemorrhagic Fever, American/virology
- Host-Pathogen Interactions/drug effects
- Humans
- Junin virus/drug effects
- Junin virus/physiology
- Mice, Inbred C57BL
- Mice, Transgenic
- Molecular Docking Simulation
- Protein Binding/drug effects
- Receptors, Transferrin/antagonists & inhibitors
- Receptors, Transferrin/immunology
- Receptors, Transferrin/metabolism
- Vero Cells
- Viral Envelope Proteins/metabolism
- Mice
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Affiliation(s)
- Brady T Hickerson
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, USA
- Division of Biotechnology Review and Research-III, Office of Biotechnology Products, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA
| | - Tracy R Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Cristian Payes
- Instituto de Biología y Medicina Experimental (IBYME CONICET), Buenos Aires, Argentina
| | - Lars E Clark
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Pierre V Candelaria
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Kevin W Bailey
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, USA
| | - Eric J Sefing
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, USA
| | - Samantha Zink
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - James Ziegenbein
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Jonathan Abraham
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Medicine, Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA, USA
| | - Gustavo Helguera
- Instituto de Biología y Medicina Experimental (IBYME CONICET), Buenos Aires, Argentina.
- Department of Chemistry and Biochemistry, University of California, Los Angeles (UCLA), Los Angeles, CA, USA.
| | - Manuel L Penichet
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
- UCLA Molecular Biology Institute, Los Angeles, CA, USA.
- UCLA Jonsson Comprehensive Cancer Center, Los Angeles, CA, USA.
- UCLA AIDS Institute, Los Angeles, CA, USA.
| | - Brian B Gowen
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, USA.
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2
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Candelaria PV, Leoh LS, Penichet ML, Daniels-Wells TR. Antibodies Targeting the Transferrin Receptor 1 (TfR1) as Direct Anti-cancer Agents. Front Immunol 2021; 12:607692. [PMID: 33815364 PMCID: PMC8010148 DOI: 10.3389/fimmu.2021.607692] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 02/15/2021] [Indexed: 12/15/2022] Open
Abstract
The transferrin receptor 1 (TfR1), also known as cluster of differentiation 71 (CD71), is a type II transmembrane glycoprotein that binds transferrin (Tf) and performs a critical role in cellular iron uptake through the interaction with iron-bound Tf. Iron is required for multiple cellular processes and is essential for DNA synthesis and, thus, cellular proliferation. Due to its central role in cancer cell pathology, malignant cells often overexpress TfR1 and this increased expression can be associated with poor prognosis in different types of cancer. The elevated levels of TfR1 expression on malignant cells, together with its extracellular accessibility, ability to internalize, and central role in cancer cell pathology make this receptor an attractive target for antibody-mediated therapy. The TfR1 can be targeted by antibodies for cancer therapy in two distinct ways: (1) indirectly through the use of antibodies conjugated to anti-cancer agents that are internalized by receptor-mediated endocytosis or (2) directly through the use of antibodies that disrupt the function of the receptor and/or induce Fc effector functions, such as antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), or complement-dependent cytotoxicity (CDC). Although TfR1 has been used extensively as a target for antibody-mediated cancer therapy over the years, interest continues to increase for both targeting the receptor for delivery purposes and for its use as direct anti-cancer agents. This review focuses on the developments in the use of antibodies targeting TfR1 as direct anti-tumor agents.
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Affiliation(s)
- Pierre V. Candelaria
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at the University of California, Los Angeles (UCLA), Los Angeles, CA, United States
| | - Lai Sum Leoh
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at the University of California, Los Angeles (UCLA), Los Angeles, CA, United States
| | - Manuel L. Penichet
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at the University of California, Los Angeles (UCLA), Los Angeles, CA, United States
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, United States
- The Molecular Biology Institute, UCLA, Los Angeles, CA, United States
- UCLA AIDS Institute, UCLA, Los Angeles, CA, United States
| | - Tracy R. Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at the University of California, Los Angeles (UCLA), Los Angeles, CA, United States
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3
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Rodríguez-García A, García-Vicente R, Morales ML, Ortiz-Ruiz A, Martínez-López J, Linares M. Protein Carbonylation and Lipid Peroxidation in Hematological Malignancies. Antioxidants (Basel) 2020; 9:E1212. [PMID: 33271863 PMCID: PMC7761105 DOI: 10.3390/antiox9121212] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/20/2020] [Accepted: 11/28/2020] [Indexed: 02/07/2023] Open
Abstract
Among the different mechanisms involved in oxidative stress, protein carbonylation and lipid peroxidation are both important modifications associated with the pathogenesis of several diseases, including cancer. Hematopoietic cells are particularly vulnerable to oxidative damage, as the excessive production of reactive oxygen species and associated lipid peroxidation suppress self-renewal and induce DNA damage and genomic instability, which can trigger malignancy. A richer understanding of the clinical effects of oxidative stress might improve the prognosis of these diseases and inform therapeutic strategies. The most common protein carbonylation and lipid peroxidation compounds, including hydroxynonenal, malondialdehyde, and advanced oxidation protein products, have been investigated for their potential effect on hematopoietic cells in several studies. In this review, we focus on the most important protein carbonylation and lipid peroxidation biomarkers in hematological malignancies, their role in disease development, and potential treatment implications.
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Affiliation(s)
- Alba Rodríguez-García
- Department of Translational Hematology, Instituto de Investigación Hospital 12 de Octubre (i+12), Hematological Malignancies Clinical Research Unit H120-CNIO, CIBERONC, ES 28041 Madrid, Spain; (A.R.-G.); (R.G.-V.); (M.L.M.); (A.O.-R.); (J.M.-L.)
| | - Roberto García-Vicente
- Department of Translational Hematology, Instituto de Investigación Hospital 12 de Octubre (i+12), Hematological Malignancies Clinical Research Unit H120-CNIO, CIBERONC, ES 28041 Madrid, Spain; (A.R.-G.); (R.G.-V.); (M.L.M.); (A.O.-R.); (J.M.-L.)
| | - María Luz Morales
- Department of Translational Hematology, Instituto de Investigación Hospital 12 de Octubre (i+12), Hematological Malignancies Clinical Research Unit H120-CNIO, CIBERONC, ES 28041 Madrid, Spain; (A.R.-G.); (R.G.-V.); (M.L.M.); (A.O.-R.); (J.M.-L.)
| | - Alejandra Ortiz-Ruiz
- Department of Translational Hematology, Instituto de Investigación Hospital 12 de Octubre (i+12), Hematological Malignancies Clinical Research Unit H120-CNIO, CIBERONC, ES 28041 Madrid, Spain; (A.R.-G.); (R.G.-V.); (M.L.M.); (A.O.-R.); (J.M.-L.)
| | - Joaquín Martínez-López
- Department of Translational Hematology, Instituto de Investigación Hospital 12 de Octubre (i+12), Hematological Malignancies Clinical Research Unit H120-CNIO, CIBERONC, ES 28041 Madrid, Spain; (A.R.-G.); (R.G.-V.); (M.L.M.); (A.O.-R.); (J.M.-L.)
- Department of Medicine, Medicine School, Universidad Complutense de Madrid, ES 28040 Madrid, Spain
| | - María Linares
- Department of Translational Hematology, Instituto de Investigación Hospital 12 de Octubre (i+12), Hematological Malignancies Clinical Research Unit H120-CNIO, CIBERONC, ES 28041 Madrid, Spain; (A.R.-G.); (R.G.-V.); (M.L.M.); (A.O.-R.); (J.M.-L.)
- Department of Biochemistry and Molecular Biology, Pharmacy School, Universidad Complutense de Madrid, ES 28040 Madrid, Spain
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Pfeifhofer-Obermair C, Tymoszuk P, Petzer V, Weiss G, Nairz M. Iron in the Tumor Microenvironment-Connecting the Dots. Front Oncol 2018; 8:549. [PMID: 30534534 PMCID: PMC6275298 DOI: 10.3389/fonc.2018.00549] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 11/06/2018] [Indexed: 12/18/2022] Open
Abstract
Iron metabolism and tumor biology are intimately linked. Iron facilitates the production of oxygen radicals, which may either result in iron-induced cell death, ferroptosis, or contribute to mutagenicity and malignant transformation. Once transformed, malignant cells require high amounts of iron for proliferation. In addition, iron has multiple regulatory effects on the immune system, thus affecting tumor surveillance by immune cells. For these reasons, inconsiderate iron supplementation in cancer patients has the potential of worsening disease course and outcome. On the other hand, chronic immune activation in the setting of malignancy alters systemic iron homeostasis and directs iron fluxes into myeloid cells. While this response aims at withdrawing iron from tumor cells, it may impair the effector functions of tumor-associated macrophages and will result in iron-restricted erythropoiesis and the development of anemia, subsequently. This review summarizes our current knowledge of the interconnections of iron homeostasis with cancer biology, discusses current clinical controversies in the treatment of anemia of cancer and focuses on the potential roles of iron in the solid tumor microenvironment, also speculating on yet unknown molecular mechanisms.
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Affiliation(s)
- Christa Pfeifhofer-Obermair
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Innsbruck, Austria
| | - Piotr Tymoszuk
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Innsbruck, Austria
| | - Verena Petzer
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Innsbruck, Austria
| | - Günter Weiss
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Innsbruck, Austria.,Christian Doppler Laboratory for Iron Metabolism and Anemia Research, Medical University of Innsbruck, Innsbruck, Austria
| | - Manfred Nairz
- Department of Internal Medicine II, Infectious Diseases, Immunology, Rheumatology, Pneumology, Medical University of Innsbruck, Innsbruck, Austria
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5
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Leoh LS, Kim YK, Candelaria PV, Martínez-Maza O, Daniels-Wells TR, Penichet ML. Efficacy and Mechanism of Antitumor Activity of an Antibody Targeting Transferrin Receptor 1 in Mouse Models of Human Multiple Myeloma. THE JOURNAL OF IMMUNOLOGY 2018; 200:3485-3494. [PMID: 29654211 DOI: 10.4049/jimmunol.1700787] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 03/22/2018] [Indexed: 01/17/2023]
Abstract
The transferrin receptor 1 (TfR1) is an attractive target for Ab-mediated cancer therapy. We previously developed a mouse/human chimeric IgG3 Ab (ch128.1) targeting human TfR1, which exhibits direct in vitro cytotoxicity against certain human malignant B cells through TfR1 degradation and iron deprivation. ch128.1 also demonstrates exceptional antitumor activity against the B cell malignancy multiple myeloma (MM) in xenograft models of SCID-Beige mice bearing either disseminated ARH-77 or KMS-11 cells in an early disease setting. Interestingly, this activity is observed even against KMS-11 cells, which show no sensitivity to the direct cytotoxic activity of ch128.1 in vitro. To understand the contributions of the Fc fragment, we generated a ch128.1 mutant with impaired binding to FcγRs and to the complement component C1q, which retains binding to the neonatal Fc receptor. We now report that this mutant Ab does not show antitumor activity in these two MM models, indicating a crucial role of the Fc fragment in the antitumor activity of ch128.1, which can be attributed to effector functions (Ab-dependent cell-mediated cytotoxicity, Ab-dependent cell-mediated phagocytosis, and/or complement-dependent cytotoxicity). Interestingly, in the KMS-11 model, complement depletion does not affect protection, whereas macrophage depletion does. Consistent with this observation, we found that ch128.1 induces Ab-dependent cell-mediated cytotoxicity and Ab-dependent cell-mediated phagocytosis against KMS-11 cells in the presence of murine bone marrow-derived macrophages. Finally, we found that ch128.1 therapy effectively increases survival in a late MM disease setting. Our results suggest that macrophages play a major role in ch128.1-mediated antitumor protection in our models and that ch128.1 can be effective against human B cell malignancies such as MM.
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Affiliation(s)
- Lai Sum Leoh
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Yoon Kyung Kim
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Pierre V Candelaria
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Otoniel Martínez-Maza
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095.,Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095.,Department of Epidemiology, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA 90095.,UCLA AIDS Institute, Los Angeles, CA 90024; and
| | - Tracy R Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Manuel L Penichet
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095; .,Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095.,UCLA AIDS Institute, Los Angeles, CA 90024; and.,The Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
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6
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Zheng W, Song Y, Xie Y, Lin N, Tu M, Liu W, Ping L, Ying Z, Zhang C, Deng L, Wang X, Lu Y, Zhu J. Cerebrospinal Fluid Proteins Identification Facilitates the Differential Diagnosis of Central Nervous System Diffuse Large B Cell Lymphoma. J Cancer 2017; 8:3631-3640. [PMID: 29151949 PMCID: PMC5687180 DOI: 10.7150/jca.20267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 08/06/2017] [Indexed: 11/05/2022] Open
Abstract
Background: Diagnosis of central nervous system (CNS) lymphoma remains a challenge. This study aimed to identify cerebrospinal fluid (CSF) proteins that distinguish patients with and without CNS lymphoma. Methods: We used one-dimensional SDS-polyacrylamide gel electrophoresis coupled with liquid chromatography- electrospray ionization-quadrupole-time of flight-mass spectrometry (LC-ESI-Q-TOF MS) to identify CSF proteins in CNS diffuse large B cell lymphoma (DLBCL) patients and controls. Results: Approximately 166 CSF proteins were identified, 12 for the first time in the CSF of lymphoma patients. Three proteins with significantly increased expression in CNS lymphoma patients compared with controls - haemopexin, apolipoprotein A1, and transferrin were verified by immunohistochemistry, and found to be strongly expressed in CNS DLBCL and nodal DLBCL. These proteins were found to be localized in the cytoplasm of a human DLBCL cell line by indirect immunofluorescence. ELISA confirmed expression at higher concentrations in the CSF of CNS lymphoma patients. CSF haemopexin, apolipoprotein A1, and transferrin concentrations were detected in CNS lymphoma patients and had diagnostic sensitivities of 80%, 83%, and 70%, and specificities of 75%, 89%, and 90%, respectively. Conclusion: Our study suggests that CSF proteins may be potential diagnostic biomarker for CNS lymphoma, especially for patients in which imaging and cytology do not provide a clear diagnosis.
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Affiliation(s)
- Wen Zheng
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - YuQin Song
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - Yan Xie
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - NingJing Lin
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - MeiFeng Tu
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - WeiPing Liu
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - LingYan Ping
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - ZhiTao Ying
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - Chen Zhang
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - LiJuan Deng
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - XiaoPei Wang
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - YouYong Lu
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
| | - Jun Zhu
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Lymphoma, Peking University Cancer Hospital & Institute. No. 52 Fucheng Road, Haidian District Beijing 100142, China
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7
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Luria-Pérez R, Helguera G, Rodríguez JA. Antibody-mediated targeting of the transferrin receptor in cancer cells. BOLETIN MEDICO DEL HOSPITAL INFANTIL DE MEXICO 2016; 73:372-379. [PMID: 29421281 DOI: 10.1016/j.bmhimx.2016.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 11/23/2016] [Indexed: 12/13/2022] Open
Abstract
Iron is essential for cell growth and is imported into cells in part through the action of transferrin (Tf), a protein that binds its receptor (TfR1 or CD71) on the surface of a cell, and then releases iron into endosomes. TfR1 is a single pass type-II transmembrane protein expressed at basal levels in most tissues. High expression of TfR1 is typically associated with rapidly proliferating cells, including various types of cancer. TfR1 is targeted by experimental therapeutics for several reasons: its cell surface accessibility, constitutive endocytosis into cells, essential role in cell growth and proliferation, and its overexpression by cancer cells. Among the therapeutic agents used to target TfR1, antibodies stand out due to their remarkable specificity and affinity. Clinical trials are being conducted to evaluate the safety and efficacy of agents targeting TfR1 in cancer patients with promising results. These observations suggest that therapies targeting TfR1 as direct therapeutics or delivery conduits remain an attractive alternative for the treatment of cancers that overexpress the receptor.
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Affiliation(s)
- Rosendo Luria-Pérez
- Unidad de Investigación en Enfermedades Oncológicas, Hospital Infantil de México Federico Gómez, Mexico City, Mexico
| | - Gustavo Helguera
- Instituto de Biología y Medicina Experimental, Ciudad Autónoma de Buenos Aires, Argentina.
| | - José A Rodríguez
- Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, California, USA.
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8
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Shapiro JM, Chung W, Ogawa K, Barker L, Carlson R, Wands JR, Li J. Identification of Tumor Antigen AF20 as Glycosylated Transferrin Receptor 1 in Complex with Heat Shock Protein 90 and/or Transporting ATPase. PLoS One 2016; 11:e0165227. [PMID: 27802297 PMCID: PMC5089552 DOI: 10.1371/journal.pone.0165227] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 10/07/2016] [Indexed: 11/18/2022] Open
Abstract
We previously isolated AF20, a murine monoclonal antibody that recognizes a cell surface glycoprotein of approximately 90-110 kDa. The AF20 antigen is specifically expressed in human hepatoma and colon cancer cell lines, and thus could serve as a cancer biomarker. To uncover the molecular identity of the AF20 antigen, a combination of ion-exchange chromatography, immunoprecipitation, and SDS-polyacrylamide gel electrophoresis was employed to purify the AF20 antigen followed by trypsin digestion and mass spectrometry. Surprisingly, three host proteins were thus purified from human hepatoma and colon cancer cell lines: transferrin receptor 1 (TFR1), heat shock protein 90 (HSP90), and Na+/K+ ATPase or Mg++ ATPase. Co-immunoprecipitation followed by Western blot analysis confirmed interaction among the three proteins. However, only the cDNA encoding TFR1 conferred strong cell surface staining by the AF20 antibody following its transient transfection into a cell line lacking endogenous AF20. In support of the molecular identity of AF20 as TFR1, diferric but not iron-free transferrin could prevent AF20 antigen-antibody interaction during immunoprecipitation. Moreover, very similar patterns of AF20 and TFR1 overexpression was documented in colon cancer tissues. In conclusion, AF20 is glycosylated TFR1. This finding could explain the molecular structure of AF20, its cell surface localization, as well as overexpression in cancer cells. Glycosylated TFR1 should serve as a usefulness target for anti-cancer therapy, or a vehicle for delivery of anti-tumor drugs with high affinity and specificity. The biological significance of the complex formation between TFR1, HSP90, and/or transporting ATPase warrants further investigation.
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Affiliation(s)
- Jason M. Shapiro
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- Division of Pediatric Gastroenterology, Nutrition and Liver Diseases, Hasbro Children’s Hospital, Providence, Rhode Island, United States of America
| | - Waihong Chung
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Kosuke Ogawa
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Luke Barker
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Rolf Carlson
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Jack R. Wands
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
| | - Jisu Li
- Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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9
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Daniels-Wells TR, Penichet ML. Transferrin receptor 1: a target for antibody-mediated cancer therapy. Immunotherapy 2016; 8:991-4. [PMID: 27373880 DOI: 10.2217/imt-2016-0050] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
- Tracy R Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 54-140, Box 951782, Los Angeles, CA 90095-1782, USA
| | - Manuel L Penichet
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, 10833 Le Conte Ave, CHS 54-140, Box 951782, Los Angeles, CA 90095-1782, USA.,Department of Microbiology, Immunology, & Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.,The Molecular Biology Institute, UCLA, Los Angeles, CA USA.,Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, USA.,UCLA AIDS Institute, CA, USA
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10
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Efficacy of an Anti-transferrin Receptor 1 Antibody Against AIDS-related Non-Hodgkin Lymphoma: A Brief Communication. J Immunother 2016; 38:307-10. [PMID: 26325374 PMCID: PMC4592199 DOI: 10.1097/cji.0000000000000092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The transferrin receptor 1 (TfR1), also known as CD71, is a target for antibody-based cancer immunotherapy due to its high expression on the surface of cancer cells and its ability to internalize. We have previously developed a mouse/human chimeric IgG3 specific for human TfR1 genetically fused to avidin, as a vector to deliver biotinylated anticancer agents into malignant cells. However, we found that this fusion protein (ch128.1Av), and to a lesser extent the same antibody without avidin (ch128.1), exhibits direct cytotoxic activity in vitro against certain malignant hematopoietic cells through the induction of TfR1 degradation and lethal iron starvation. Importantly, both ch128.1 and ch128.1Av have also shown significant anticancer activity in 2 xenograft models of the B-cell malignancy multiple myeloma. It is interesting to note that ch128.1 exhibited superior anticancer activity in both models compared with ch128.1Av, even against malignant cells that show no sensitivity to ch128.1 in vitro. In the present study, we evaluated the efficacy of ch128.1 against an AIDS-related human Burkitt lymphoma cell line (2F7) to determine if ch128.1 can eliminate these cells in vitro and in an in vivo model of AIDS-related non-Hodgkin lymphoma (AIDS-NHL). Even though 2F7 cells expressed high TfR1 levels, these cells lacked sensitivity to the cytotoxicity induced by ch128.1 in vitro. However, ch128.1 showed significant anticancer activity against these AIDS-NHL cells in vivo by significantly prolonging the survival of immunodeficient mice bearing 2F7 tumors. Therefore, ch128.1 warrants further study as a candidate for the treatment of AIDS-NHL and other B-cell malignancies.
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Leoh LS, Daniels-Wells TR, Martínez-Maza O, Penichet ML. Insights into the effector functions of human IgG3 in the context of an antibody targeting transferrin receptor 1. Mol Immunol 2015; 67:407-15. [PMID: 26232328 DOI: 10.1016/j.molimm.2015.07.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 06/19/2015] [Accepted: 07/01/2015] [Indexed: 12/29/2022]
Abstract
The transferrin receptor 1 (TfR1) is involved in cellular iron uptake and regulation of cell proliferation. The increased expression of TfR1 observed in malignant cells, compared to normal cells, together with its extracellular accessibility, make this receptor an attractive target for antibody-mediated cancer therapy. We have developed a mouse/human chimeric IgG3 specific for human TfR1 (ch128.1), which shows anti-tumor activity against certain malignant B cells in vitro through TfR1 degradation and iron deprivation, and in vivo through a mechanism yet to be defined. To further explore potential mechanisms of action of ch128.1, we examined its ability to induce antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-mediated cytotoxicity (CDC). We now report that ch128.1 is capable of mediating ADCC and CDC against malignant B cells, which is consistent with its ability to bind FcγRI, FcγRIIIa, and the complement component C1q. To delineate the residues involved in these effector functions, we developed a panel of three constructs with mutations in the lower hinge region and CH2 domain: 1) L234A/L235A, 2) P331S, and 3) L234A/L235A/P331S. The triple mutant consistently displayed a significant reduction in ADCC, while the L234A/L235A mutant exhibited less reduction in ADCC, and the P331S mutant did not show reduced ADCC. However, all three mutants exhibited impaired binding to FcγRI and FcγRIIIa. These results suggest that all three residues contribute to ADCC, although to different degrees. The P331S mutant showed drastically decreased C1q binding and abolished CDC, confirming the critical role of this residue in complement activation, while the other residues play a less important role in CDC. Our study provides insights into the effector functions of human IgG3 in the context of an antibody targeting TfR1.
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Affiliation(s)
- Lai Sum Leoh
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Tracy R Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Otoniel Martínez-Maza
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Epidemiology, UCLA Fielding School of Public Health, Los Angeles, CA, USA; Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA; UCLA AIDS Institute, Los Angeles, CA, USA
| | - Manuel L Penichet
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA; UCLA AIDS Institute, Los Angeles, CA, USA; The Molecular Biology Institute, University of California, Los Angeles, CA, USA.
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Leoh LS, Morizono K, Kershaw KM, Chen ISY, Penichet ML, Daniels-Wells TR. Gene delivery in malignant B cells using the combination of lentiviruses conjugated to anti-transferrin receptor antibodies and an immunoglobulin promoter. J Gene Med 2014; 16:11-27. [PMID: 24436117 DOI: 10.1002/jgm.2754] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 12/05/2013] [Accepted: 01/09/2014] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND We previously developed an antibody-avidin fusion protein (ch128.1Av) specific for the human transferrin receptor 1 (TfR1; CD71) to be used as a delivery vector for cancer therapy and showed that ch128.1Av delivers the biotinylated plant toxin saporin-6 into malignant B cells. However, as a result of widespread expression of TfR1, delivery of the toxin to normal cells is a concern. Therefore, we explored the potential of a dual targeted lentiviral-mediated gene therapy strategy to restrict gene expression to malignant B cells. Targeting occurs through the use of ch128.1Av or its parental antibody without avidin (ch128.1) and through transcriptional regulation using an immunoglobulin promoter. METHODS Flow cytometry was used to detect the expression of enhanced green fluorescent protein (EGFP) in a panel of cell lines. Cell viability after specific delivery of the therapeutic gene FCU1, a chimeric enzyme consisting of cytosine deaminase genetically fused to uracil phosphoribosyltransferse that converts the 5-fluorocytosine (5-FC) prodrug into toxic metabolites, was monitored using the MTS or WST-1 viability assay. RESULTS We found that EGFP was specifically expressed in a panel of human malignant B-cell lines, but not in human malignant T-cell lines. EGFP expression was observed in all cell lines when a ubiquitous promoter was used. Furthermore, we show the decrease of cell viability in malignant plasma cells in the presence of 5-FC and the FCU1 gene. CONCLUSIONS The present study demonstrates that gene expression can be restricted to malignant B cells and suggests that this dual targeted gene therapy strategy may help to circumvent the potential side effects of certain TfR1-targeted protein delivery approaches.
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Affiliation(s)
- Lai Sum Leoh
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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Parenti R, Salvatorelli L, Magro G. Anaplastic Thyroid Carcinoma: Current Treatments and Potential New Therapeutic Options with Emphasis on TfR1/CD71. Int J Endocrinol 2014; 2014:685396. [PMID: 25097549 PMCID: PMC4102021 DOI: 10.1155/2014/685396] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/15/2014] [Accepted: 06/17/2014] [Indexed: 12/24/2022] Open
Abstract
Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human cancers. Actually, ATC is refractory to conventional therapies, including surgery, chemotherapy, radiotherapy, and radioiodine ((131)I) therapy. Accordingly, genetic and molecular characterizations of ATC have been frequently and periodically reviewed in order to identify potential biological markers exploitable for target therapy. This review briefly focuses on main molecular events that characterize ATC and provides an update about preclinical studies. In addition, the overexpression of transferrin receptor 1 (TfR1/CD71) by neoplastic cells of ATC is emphasized in that it could represent a potential therapeutic target. In this regard, new therapeutic approaches based on the use of monoclonal or recombinant antibodies, or transferrin-gallium-TfR1/CD71 molecular complexes, or lastly small interfering RNAs (siRNAs) are proposed.
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Affiliation(s)
- Rosalba Parenti
- Department of Bio-Medical Sciences, Physiology Section, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
- *Rosalba Parenti:
| | - Lucia Salvatorelli
- Department G.F. Ingrassia, Section of Anatomic Pathology, University of Catania, Via S. Sofia 87, 95123 Catania, Italy
| | - Gaetano Magro
- Department G.F. Ingrassia, Section of Anatomic Pathology, University of Catania, Via S. Sofia 87, 95123 Catania, Italy
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Heath JL, Weiss JM, Lavau CP, Wechsler DS. Iron deprivation in cancer--potential therapeutic implications. Nutrients 2013; 5:2836-59. [PMID: 23887041 PMCID: PMC3775231 DOI: 10.3390/nu5082836] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/12/2013] [Accepted: 07/16/2013] [Indexed: 02/04/2023] Open
Abstract
Iron is essential for normal cellular function. It participates in a wide variety of cellular processes, including cellular respiration, DNA synthesis, and macromolecule biosynthesis. Iron is required for cell growth and proliferation, and changes in intracellular iron availability can have significant effects on cell cycle regulation, cellular metabolism, and cell division. Perhaps not surprisingly then, neoplastic cells have been found to have higher iron requirements than normal, non-malignant cells. Iron depletion through chelation has been explored as a possible therapeutic intervention in a variety of cancers. Here, we will review iron homeostasis in non-malignant and malignant cells, the widespread effects of iron depletion on the cell, the various iron chelators that have been explored in the treatment of cancer, and the tumor types that have been most commonly studied in the context of iron chelation.
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Affiliation(s)
- Jessica L. Heath
- Division of Pediatric Hematology-Oncology, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA; E-Mails: (J.L.H.); (J.M.W.); (C.P.L.)
| | - Joshua M. Weiss
- Division of Pediatric Hematology-Oncology, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA; E-Mails: (J.L.H.); (J.M.W.); (C.P.L.)
| | - Catherine P. Lavau
- Division of Pediatric Hematology-Oncology, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA; E-Mails: (J.L.H.); (J.M.W.); (C.P.L.)
| | - Daniel S. Wechsler
- Division of Pediatric Hematology-Oncology, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA; E-Mails: (J.L.H.); (J.M.W.); (C.P.L.)
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-919-684-3401; Fax: +1-919-681-7950
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Hong Y, Yang J, Shen X, Zhu H, Sun X, Wen X, Bian J, Hu H, Yuan L, Tao J, Lei P, Shen G. Sinomenine hydrochloride enhancement of the inhibitory effects of anti-transferrin receptor antibody-dependent on the COX-2 pathway in human hepatoma cells. Cancer Immunol Immunother 2013; 62:447-54. [PMID: 22941037 PMCID: PMC11028739 DOI: 10.1007/s00262-012-1337-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 08/09/2012] [Indexed: 10/27/2022]
Abstract
Transferrin receptor (TfR) has been used as a target for the antibody-based therapy of cancer due to its higher expression in tumors relative to normal tissues. Great potential has been shown by anti-TfR antibodies combined with chemotherapeutic drugs as a possible cancer therapeutic strategy. In our study, we investigated the anti-tumor effects of anti-TfR monoclonal antibody (mAb) alone or in combination with sinomenine hydrochloride in vitro. Results suggested that anti-TfR mAb or sinomenine hydrochloride could induce apoptosis, inhibit proliferation, and affect the cell cycle. A synergistic effect was found in relation to tumor growth inhibition and the induction of apoptosis when anti-TfR mAb and sinomenine hydrochloride were used simultaneously. The expression of COX-2 and VEGF protein in HepG2 cells treated with anti-TfR mAb alone was increased in line with increasing dosage of the agent. In contrast, COX-2 expression was dramatically decreased in HepG2 cells treated with sinomenine hydrochloride alone. Furthermore, we demonstrated that the inhibitory effects of sinomenine hydrochloride and anti-TfR mAb administered in combination were more prominent than when the agents were administered singly. To sum up, these results showed that the combined use of sinomenine hydrochloride and anti-TfR mAb may exert synergistic inhibitory effects on human hepatoma HepG2 cells in a COX-2-dependent manner. This finding provides new insight into how tumor cells overcome the interference of iron intake to survive and forms the basis of a new therapeutic strategy involving the development of anti-TfR mAb combined with sinomenine hydrochloride for liver cancer.
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Affiliation(s)
- Yi Hong
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, No. 13 Hongkong Road, Wuhan, 430030, People's Republic of China.
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Abstract
Multiple myeloma is a non-curable B-cell malignancy in which iron metabolism plays an important role. Patients with this disorder almost universally suffer from clinically significant anemia, which is often symptomatic, and which is due to impaired iron utilization. Recent studies have indicated that the proximal cause of dysregulated iron metabolism and anemia in these patients is cytokine-induced upregulation of hepcidin expression. Malignant myeloma cells are dependent on an increased influx of iron, and therapeutic efforts are being made to target this requirement. The studies detailing the characteristics and biochemical abnormalities in iron metabolism causing anemia and the initial attempts to target iron therapeutically are described in this review.
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Affiliation(s)
- Kristina VanderWall
- Division of Hematology-Oncology, Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, California
| | - Tracy R Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, UCLA David Geffen School of Medicine, Los Angeles, California
| | - Manuel Penichet
- Division of Surgical Oncology, Department of Surgery, UCLA David Geffen School of Medicine, Los Angeles, California
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California
- Molecular Biology Institute, UCLA, Los Angeles, California
- Department of Microbiology, Immunology and Molecular Genetics, UCLA, Los Angeles, California
| | - Alan Lichtenstein
- Division of Hematology-Oncology, Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, California
- Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, California
- Greater Los Angeles VA Medical Center, Los Angeles, California
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Daniels-Wells TR, Helguera G, Rodríguez JA, Leoh LS, Erb MA, Diamante G, Casero D, Pellegrini M, Martínez-Maza O, Penichet ML. Insights into the mechanism of cell death induced by saporin delivered into cancer cells by an antibody fusion protein targeting the transferrin receptor 1. Toxicol In Vitro 2012; 27:220-31. [PMID: 23085102 DOI: 10.1016/j.tiv.2012.10.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 10/04/2012] [Accepted: 10/08/2012] [Indexed: 02/07/2023]
Abstract
We previously developed an antibody-avidin fusion protein (ch128.1Av) that targets the human transferrin receptor 1 (TfR1) and exhibits direct cytotoxicity against malignant B cells in an iron-dependent manner. ch128.1Av is also a delivery system and its conjugation with biotinylated saporin (b-SO6), a plant ribosome-inactivating toxin, results in a dramatic iron-independent cytotoxicity, both in malignant cells that are sensitive or resistant to ch128.1Av alone, in which the toxin effectively inhibits protein synthesis and triggers caspase activation. We have now found that the ch128.1Av/b-SO6 complex induces a transcriptional response consistent with oxidative stress and DNA damage, a response that is not observed with ch128.1Av alone. Furthermore, we show that the antioxidant N-acetylcysteine partially blocks saporin-induced apoptosis suggesting that oxidative stress contributes to DNA damage and ultimately saporin-induced cell death. Interestingly, the toxin was detected in nuclear extracts by immunoblotting, suggesting the possibility that saporin might induce direct DNA damage. However, confocal microscopy did not show a clear and consistent pattern of intranuclear localization. Finally, using the long-term culture-initiating cell assay we found that ch128.1Av/b-SO6 is not toxic to normal human hematopoietic stem cells suggesting that this critical cell population would be preserved in therapeutic interventions using this immunotoxin.
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Affiliation(s)
- Tracy R Daniels-Wells
- Division of Surgical Oncology, Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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