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Jelkmann W, Bohlius J, Hallek M, Sytkowski AJ. The erythropoietin receptor in normal and cancer tissues. Crit Rev Oncol Hematol 2008; 67:39-61. [PMID: 18434185 DOI: 10.1016/j.critrevonc.2008.03.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 02/25/2008] [Accepted: 03/19/2008] [Indexed: 01/27/2023] Open
Abstract
The hormone erythropoietin (EPO) is essential for the survival, proliferation and differentiation of the erythrocytic progenitors. The EPO receptor (EPO-R) of erythrocytic cells belongs to the cytokine class I receptor family and signals through various protein kinases and STAT transcription factors. The EPO-R is also expressed in many organs outside the bone marrow, suggesting that EPO is a pleiotropic anti-apoptotic factor. The controversial issue as to whether the EPO-R is functional in tumor tissue is critically reviewed. Importantly, most studies of EPO-R detection in tumor tissue have provided falsely positive results because of the lack of EPO-R specific antibodies. However, endogenous EPO appears to be necessary to maintain the viability of endothelial cells and to promote tumor angiogenesis. Although there is no clinical proof that the administration of erythropoiesis stimulating agents (ESAs) promotes tumor growth and mortality, present recommendations are that (i) ESAs should be administered at the lowest dose sufficient to avoid the need for red blood cell transfusions, (ii) ESAs should not be used in patients with active malignant disease not receiving chemotherapy or radiotherapy, (iii) ESAs should be discontinued following the completion of a chemotherapy course, (iv) the target Hb should be 12 g/dL and not higher and (v) the risks of shortened survival and tumor progression have not been excluded when ESAs are dosed to target Hb <12 g/dL.
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Affiliation(s)
- Wolfgang Jelkmann
- Institute of Physiology, University of Luebeck, Ratzeburger Allee 160, D-23538 Luebeck, Germany.
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Jelkmann W, Wagner K. Beneficial and ominous aspects of the pleiotropic action of erythropoietin. Ann Hematol 2004; 83:673-86. [PMID: 15322761 DOI: 10.1007/s00277-004-0911-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 06/17/2004] [Indexed: 02/07/2023]
Abstract
The primary function of the glycoprotein hormone erythropoietin (Epo) is to promote red cell production by inhibiting apoptosis of erythrocytic progenitors in hemopoietic tissues. However, functional Epo receptors (Epo-R) have recently been demonstrated in various nonhemopoietic tissues indicating that Epo is a more pleiotropic viability and growth factor. Herein, in vitro and in vivo effects of Epo in the brain and the cardiovascular system are reviewed. In addition, the therapeutic impact of Epo in oncology is considered, including the question of whether Epo might promote tumor growth. Convincing evidence is available that Epo acts as a neurotrophic and neuroprotective factor in the brain. Epo prevents neuronal cells from hypoxia-induced and glutamate-induced cell death. Epo-R is expressed by neurons and glia cells in specific regions of the brain. Epo supports the survival of neurons in the ischemic brain. The neuroprotective potential of Epo has already been confirmed in a clinical trial on patients with acute stroke. With respect to the vasculature, Epo acts on both endothelial and smooth muscle cells. Epo promotes angiogenesis and stimulates the production of endothelin and other vasoactive mediators. In addition, Epo-R is expressed by cardiomyocytes. The role of Epo as a myocardial protectant is at the focus of present research. Epo therapy in tumor patients is practiced primarily to maintain the hemoglobin concentration above the transfusion trigger and to reduce fatigue. In addition, increased tumor oxygenation may improve the efficacy of chemotherapy and radiotherapy. However, tumor cells often express Epo-R. Therefore, careful studies are required to fully exclude that recombinant human Epo (rHuEpo) promotes tumor growth.
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Affiliation(s)
- Wolfgang Jelkmann
- Institute of Physiology, University of Luebeck, Ratzeburger Allee 160, 23538, Luebeck, Germany.
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Elliott S, Lorenzini T, Yanagihara D, Chang D, Elliott G. Activation of the erythropoietin (EPO) receptor by bivalent anti-EPO receptor antibodies. J Biol Chem 1996; 271:24691-7. [PMID: 8798737 DOI: 10.1074/jbc.271.40.24691] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Oligomerization of cytokine receptors including the erythropoietin (EPO) receptor has been advanced as a model for activation. If homodimerization of the EPO receptor activates it, then bivalent antibodies raised to the extracellular domain of the EPO receptor should also homodimerize and activate. Mouse monoclonal antibodies (IgG) raised to the soluble, extracellular domain of the human EPO receptor (EPOR) were found that would stimulate thymidine uptake of an human EPO-dependent cell line, UT-7/EPO. Dose response curves showed bell shapes where activity was low at low and high concentrations. Monovalent (Fab) fragments bound to the receptor but did not stimulate thymidine uptake, which indicates that two antibody binding sites are required for activation. The anti-EPOR antibodies stimulated the formation of burst forming unit erythroid colonies from human CD34(+) cells purified from peripheral blood. This indicates that homodimerization of the EPO receptor by anti-EPOR antibodies is sufficient for both proliferation and differentiation of erythroid progenitor cells and that the constraints on dimerization necessary for activation are rather loose.
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Affiliation(s)
- S Elliott
- Amgen, Amgen Center, Thousand Oaks, California 91320, USA
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4
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Cho IK, Huh IH, Lee SJ, Kim DS, Ann HS. Potential role of Ca++ on the differentiation of erythroid progenitor cells. Arch Pharm Res 1995. [DOI: 10.1007/bf02979142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Affiliation(s)
- S T Sawyer
- Division of Hematology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2287
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Pacifici R, Thomason A. Hybrid tyrosine kinase/cytokine receptors transmit mitogenic signals in response to ligand. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42059-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Affiliation(s)
- S J Schuster
- Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pa 19107-5099
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Showers MO, D'Andrea AD. Subunit structure and transmembrane signaling of the erythropoietin receptor. INTERNATIONAL REVIEW OF CYTOLOGY 1993; 137B:99-120. [PMID: 1336006 DOI: 10.1016/s0074-7696(08)62601-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- M O Showers
- Division of Pediatric Oncology, Dana Farber Cancer Institute, Children's Hospital, Harvard Medical School, Boston, Massachusetts
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Koury MJ, Bondurant MC. The molecular mechanism of erythropoietin action. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 210:649-63. [PMID: 1483451 DOI: 10.1111/j.1432-1033.1992.tb17466.x] [Citation(s) in RCA: 195] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- M J Koury
- Division of Hematology, Vanderbilt University School of Medicine, Nashville, TN 37232-2287
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10
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D'Andrea AD, Moreau JF, Showers MO. Molecular mimicry of erythropoietin by the spleen focus-forming virus gp55 glycoprotein: the first stage of Friend virus-induced erythroleukemia. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1114:31-41. [PMID: 1390869 DOI: 10.1016/0304-419x(92)90004-i] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- A D D'Andrea
- Dana-Farber Cancer Institute, Children's Hospital, Harvard Medical School, Boston, MA 02115
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Abstract
Molecular analysis of the human erythropoietin receptor (EpoR) promises to yield a greater mechanistic understanding of erythropoiesis and disease states that affect red cell production. The cloned receptor molecule is a 66 kDa membrane protein that is structurally related to a large superfamily of haemopoietin/growth factor receptors. The 66 kDa EpoR alone is capable of binding to erythropoietin (Epo) with nanomolar affinity. The native EpoR may form dimers before or after binding Epo. EpoR dimers and/or associated molecules are probably necessary for high-affinity Epo binding. The 66 kDa EpoR probably exists as a protein complex with as yet unidentified proteins of 100 and 85 kDa. The molecular mechanism of Epo signal transduction remains largely undefined. The possible role of the EpoR in human diseases has been studied in a variety of clinical conditions. A structurally abnormal EpoR gene has been identified in a human erythroleukemia cell line. In polycythemia vera, red cell progenitors exhibit exaggerated sensitivity to Epo and express only low-affinity EpoR. Some cases of hereditary polycythemia may be due to a mutant EpoR conferring enhanced Epo sensitivity. Other pathologic conditions may also be associated with abnormalities of the EpoR or its associated molecules. Soluble, immunoreactive EpoR is detectable in human serum, but its physiological significance is unknown.
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Affiliation(s)
- J C Winkelmann
- Department of Medicine, University of Minnesota Medical School, Minneapolis
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Mayeux P, Lacombe C, Casadevall N, Chretien S, Dusanter I, Gisselbrecht S. Structure of the murine erythropoietin receptor complex. Characterization of the erythropoietin cross-linked proteins. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54507-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Brizzi MF, Avanzi GC, Pegoraro L. Hematopoietic growth factor receptors. INTERNATIONAL JOURNAL OF CELL CLONING 1991; 9:274-300. [PMID: 1894957 DOI: 10.1002/stem.5530090404] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The molecular cloning for most of the hematopoietic growth factor receptors has been achieved over the past few years and revealed that they can by assigned to two discrete receptor families, namely the hematopoietic growth factor superfamily (HRS) and the receptor tyrosine kinase family (RTK). The members of the HRS, including granulocyte-macrophage colony-stimulating factor receptor (GM-CSF-R), interleukin 3 receptor (IL-3-R), granulocyte CSF receptor (G-CSF-R) and erythropoietin receptor (Epo-R), share a common binding domain and the absence of a tyrosine kinase domain in their cytoplasmic portion. In some cases (e.g., GM-CSF-R), the high-affinity receptor structure is obtained through the association of the low-affinity binding chain (alpha chain) with an accessory protein (beta chain). It is conceivable that this protein might also represent the common subunit shared by GM-CSF-R and by IL-3-R when they are co-expressed to form the putative GM-CSF-R/IL-3-R complex. Although tyrosine phosphorylation following ligand receptor activation seems to be a common event in the HRS, its role in the signal transduction mechanisms is unknown. Due to the structural analogies among the members of this family any new insight into one particular receptor member, such as its subunit structure and its signal transduction pathways, will be generalizable to the other family members. The subclass III of the RTK family, including the CSF-1-R and c-kit, is characterized by an additional insert into the kinase domain that recognizes and binds protein substrates. Ligand induced activation of the kinase domain and its signaling potential are mediated by receptor oligomerization which stabilizes interactions between adjacent cytoplasmic domains and leads to activation of kinase function by molecular interaction. Interestingly, the receptors included in this subclass are the products of well known cellular proto-oncogenes. A large variety of structural alteration found in receptor-derived oncogene products may lead to constitutive activation of receptor signals that, consequently, result in the subversion of the mechanisms controlling the cell growth.
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Affiliation(s)
- M F Brizzi
- Dipartimento di Scienze Biomediche e Oncologia Umana, Universitá di Torino, Italy
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Abstract
Murine erythropoietin-responsive Rauscher Red 5-1.5 cells were used to determine the contribution of glycosylation to the size and function of the erythropoietin receptor. The half life of the receptors was determined to be 4 h. The number of receptors was not significantly decreased in cells treated for 48 h with inhibitors of glycosylation (tunicamycin, glucosamine or swainsonine) and their affinity was slightly enhanced in tunicamycin- or glucosamine-treated cells. Erythropoietin was cross-linked with two proteins of 104 and 86 kDa. Their molecular masses were not significantly reduced in cells treated with the glycosylation inhibitors. When immunoprecipitated cross-linked receptors were digested with endoglycosidases, the molecular masses of both proteins were only slightly modified giving values of 100 and 82 kDa. Thus we can conclude that the proteins cross-linked to erythropoietin are very weakly glycosylated.
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Affiliation(s)
- P Mayeux
- ICGM, Inserm U152, Hôpital Cochin, Paris, France
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Im JH, Lee SJ, Kim HD. Partial purification and characterization of erythropoietin receptors from erythroid progenitor cells. Arch Biochem Biophys 1990; 278:486-91. [PMID: 2158283 DOI: 10.1016/0003-9861(90)90290-f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have partially purified and characterized erythropoietin (Epo) receptors of erythroid progenitor cells which were obtained from the spleens of anemia-inducing Friend virus infected mice. Membrane proteins of splenic erythroid progenitor cells were solubilized with 1% Triton X-102. Upon chromatography on DEAE-Sephacel anion-exchange columns, two distinct Epo receptor peak fractions referred to as Peak I and Peak II were identified by 125I-Epo binding assays using the polyethylene glycol precipitation method. The Peak I and Peak II samples were then individually chromatographed on an S-Sepharose column. The S-Sepharose-purified Peak I and Peak II samples were crosslinked with 125I-Epo in the presence and absence of excess unlabeled Epo by disuccinimidyl suberate treatment, and then analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. Both Peak I and Peak II samples showed a radiolabeled peptide with a Mr 135K and the labeling was blocked by excess unlabeled Epo. Since the Mr of Epo is about 35K, Epo receptor peptide has a Mr approximately 100K. To determine whether Epo stimulates autophosphorylation of the receptors, the S-Sepharose-purified Peak I and Peak II samples were incubated with or without Epo, and then briefly incubated in the presence of [gamma-32P]ATP and Mn2+. The tyrosine residue phosphorylated protein was isolated by an immunochemical technique, and then analyzed by SDS-PAGE and autoradiography. The result showed that Epo stimulates phosphorylation of a 100-kDa peptide.
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Affiliation(s)
- J H Im
- Department of Pharmacology, School of Medicine, University of Missouri, Columbia 65212
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Dessypris EN, Krantz SB. Erythropoietin: regulation of erythropoiesis and clinical use. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1990; 21:127-47. [PMID: 2265125 DOI: 10.1016/s1054-3589(08)60341-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- E N Dessypris
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
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Krantz SB, Sawyer ST, Sawada K, Wolfe F, Bocagno J. Erythropoietin: receptors and clinical use in rheumatoid arthritis. INTERNATIONAL JOURNAL OF CELL CLONING 1990; 8 Suppl 1:181-95; discussion 195-8. [PMID: 2157776 DOI: 10.1002/stem.5530080717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Erythropoietin (Epo) receptors have been delineated using radioiodinated recombinant erythropoietin (rEpo) and highly purified murine and human erythroid colony-forming units (CFU-e). The murine CFU-e had 950 receptors/cell. One-third had a Kd of 0.09 nM while two-thirds had a Kd of 0.57 nM. Human CFU-e had 1,050 receptors/cell. Two hundred had a Kd of 0.10 nM and 850 had a Kd of 0.57 nM. 125I-rEpo was rapidly internalized and degraded by the CFU-e. Cross-linking of 125I-rEpo to human Epo receptors demonstrated two proteins of 100 and 90 kDa and proteolytic peptide mapping of each protein showed identical fragments indicating that they are very similar. rEpo was also used to treat patients with the anemia of rheumatoid arthritis, and one case is presented in which the patient's hematocrit rose from 32.5% to 44% in eight weeks. When the rEpo was discontinued, the hematocrit fell back to 33%.
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Affiliation(s)
- S B Krantz
- Department of Medicine, Veterans Administration Medical Center, Nashville, Tennessee
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Sawyer ST. Receptors for Erythropoietin Distribution, Structure, and Role in Receptor-Mediated Endocytosis in Erythroid Cells. BLOOD CELL BIOCHEMISTRY 1990. [DOI: 10.1007/978-1-4757-9528-8_12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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