红细胞生成素受体1

b Coch Contents 1. Introd 2. Structu 2.1. 2.2. 2.3. 2.4. 3. Functi 3.1. 3.2. 3.3. 4. Expres 4.1. 4.2. 4.3. 5. Clinic 5.1. 5.2. 5.3. 5.4. Review Ackno Refere Biogra Abstract The horm receptor (E ∗ Correspo E-mail a 1040-8428/$ doi:10.1016/ Critical Reviews in Oncology/Hematology 67 (2008) 39–61 The erythropoietin receptor in normal and cancer tissues Wolfgang Jelkmann a,∗, Julia Bohlius b, Michael Hallek b, Arthur J. Sytkowski c a Institute of Physiology, University of Luebeck, Ratzeburger Allee 160, D-23538 Luebeck, Germany rane Haematological Malignancies Group (CHMG), Department I Internal Medicine, University of Cologne, D-50937 Cologne, Germany c Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA Accepted 19 March 2008 uction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 re and function of the erythropoietin receptor (EPO-R) in erythroid tissues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Identification of the EPO-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 The EPO-R gene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 The structure of the EPO-R: a member of the cytokine receptor superfamily . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.3.1. Overall structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.3.2. The extracellular portion of the EPO-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.3.3. The cytoplasmic portion of the EPO-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Signal transduction pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.4.1. Phosphorylation of the EPO-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.4.2. EPO’s signal transduction cascade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 on of the EPO-R in non-malignant non-hemopoietic tissues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Heart and blood vessels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Kidneys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Central and peripheral nervous system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 sion and functionality of the EPO-R in tumor cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 The EPO-R in solid tumor biopsies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Human cancer cell cultures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Animal models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 al relevance of anemia in cancer patients and treatment options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Recombinant human ESAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 5.1.1. Effectiveness and safety of ESA therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Clinical trials in cancer patients receiving ESAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 5.2.1. Evidence for improved tumor control or survival in patients receiving ESAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 5.2.2. Evidence for decreased tumor control or survival in patients receiving ESAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Thromboembolic events in cancer patients receiving ESAs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 5.3.1. Methodological considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Implications for practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 wledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 nces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 phies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 one erythropoietin (EPO) is essential for the survival, proliferation and differentiation of the erythrocytic progenitors. The EPO PO-R) of erythrocytic cells belongs to the cytokine class I receptor family and signals through various protein kinases and STAT nding author. Tel.: +49 451 500 4150; fax: +49 451 500 4151. ddress: Jelkmann@physio.uni-luebeck.de (W. Jelkmann). – see front matter © 2008 Elsevier Ireland Ltd. All rights reserved. j.critrevonc.2008.03.006 40 W. Jelkmann et al. / Critical Reviews in Oncology/Hematology 67 (2008) 39–61 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 b mote t that the adm mor g (i) ESAs sho or red patients with y, (iii) of a chemot and (v have not bee © 2008 Else Keywords: A 1. Introdu The gly the surviva throcytic p production with chron mainly of the etiolog patients w to a lack o are the inh progenitors cient iron a bleeding. I erythropoie binant hum patients wi proportion fusions. In FDA for th and non-m In 2002, th etin alfa w cancer pati nant erythr entered the and surgery Evidenc the EPO re poietic cell cardiovascu promise be peutic analogues as tissue-protective factors, for example in ischemic and degenerative heart and brain diseases [2], fear has also arisen that EPO may promote tumor cell survival and stimulate tumor growth [3,4]. The first part of this article reviews the structure and function of the EPO-R of the erythrocytic progenitors. The second part describes the alleged role of the EPO-R outside the bone marrow. In particular, the controversial preclinical studies on the action of EPO on tumor cells are considered. Finally, the recent developments in the use of rhuEPO and alogu ned. ructu tor (E Identi e ini tor (E expec publis rial – ssible ion of ted in or rec lls bea O wa n of tri adiola nstrat e pres of fou eled E tor bi nce rH n to stu norm rom 3 ted. H h are p imately 1000 EPO-R/cell [11]. Interestingly, studies of the thermodynamics of binding frequently revealed two differ- ent affinity classes of EPO-R (binding sites) with the higher affinity class ranging from KD ≈ 90–900 pM and the lower affinity from KD ≈ 200–9000 pM [8,12]. Other studies iden- tified only a single class of receptors [13,14]. There is no clear molecular explanation for these different observations. There was also some evidence that differential glycosylation of the receptor was responsible for the two affinity classes, but it was later disproven [15]. e necessary to maintain the viability of endothelial cells and to pro inistration of erythropoiesis stimulating agents (ESAs) promotes tu uld be administered at the lowest dose sufficient to avoid the need f active malignant disease not receiving chemotherapy or radiotherap herapy course, (iv) the target Hb should be 12 g/dL and not higher n excluded when ESAs are dosed to target Hb <12 g/dL. vier Ireland Ltd. All rights reserved. nemia; Cancer; Erythropoiesis stimulating agents; EPO receptor ction coprotein erythropoietin (EPO) is essential for l, proliferation and differentiation of the ery- rogenitors in the bone marrow. Insufficient EPO is the main cause of the anemia in patients ic kidney disease (CKD) as circulating EPO is renal origin. In contrast to the anemia of CKD, y of the anemia of chronic disease (ACD) in ith cancer is multifactorial and only partly due f EPO [1]. Other pathogenetic factors in ACD ibition of the proliferation of the erythrocytic by immunomodulatory peptides, the insuffi- vailability, the increased hemolysis and, possibly, n addition, myelosuppressive therapeutics inhibit sis. Nevertheless, the administration of recom- an EPO (rhuEPO) and its analogues to anemic th cancer receiving chemotherapy can reduce the of patients who require red blood cell (RBC) trans- 1993, the use of rHuEPO was approved by the e treatment of anemia in patients with solid tumors yeloid malignancies undergoing chemotherapy. e hyperglycosylated rHuEPO mutein Darbepo- as also licensed for the treatment of anemia in ents receiving chemotherapy. Additional recombi- opoiesis stimulating agents (ESAs) have recently European market for use in nephrology, oncology . e has accumulated during the past 20 years that ceptor (EPO-R) is not only expressed by erythro- s but by a number of other tissues including the lar system and the brain. While these findings neficial effects of endogenous EPO and its thera- its an outli 2. St recep 2.1. Th recep been been mate impo dinat resul less f of ce EP ratio this r demo in th one a lab recep O bega both ing f repor whic umor angiogenesis. Although there is no clinical proof rowth and mortality, present recommendations are that blood cell transfusions, (ii) ESAs should not be used in ESAs should be discontinued following the completion ) the risks of shortened survival and tumor progression es in cancer patients receiving chemotherapy are re and function of the erythropoietin PO-R) in erythroid tissues fication of the EPO-R tial identification of the erythropoietin (EPO) PO-R) proved more difficult than would have ted. Although a method of EPO purification had hed in detail [5], the striking shortage of starting the urine of anemic humans – made it virtually for the feat to be repeated. Secondly, the radioio- EPO using the then popular chloramine T method inactivation of the hormone, thus making it use- eptor studies. Lastly, a highly enriched population ring the EPO-R was not generally available. s first radiolabeled for receptor studies by incorpo- tiated thymidine into its sialic acid residues. Using beled EPO, specific binding sites (“EPO-R”) were ed on erythroid cells [6]. Later, radioiodination ence of IodogenTM, which appears to label only r available tyrosyl residues in EPO, resulted in PO with preserved biologic activity, useful for nding studies [7,8]. uEPO became available, numerous investigators dy the EPO-R on a variety of erythroid cell types, al and transformed, and receptor numbers rang- 4/cell [9] to approximately 3000/cell [10] were ighly enriched erythroid colony forming cells, redominantly CFU-E, reportedly express approx- W. Jelkmann et al. / Critical Reviews in Oncology/Hematology 67 (2008) 39–61 41 Various crosslinking studies were also carried out, usu- ally by incubating 125I labeled EPO with cells (to permit binding to the EPO-R) followed by addition of a homobi- functional (DSS). Afte PAGE and investigato 85–150 kD species wa ences in the altered pos tein [18]. A These obse of the appa observed b It is pos and the bio ment of an E erythroleuk polar/plana biologic res cells respon left shifted sensitivity DMSO tre to over 20 mRNA lev revealed a S tive of pos 6.75, indica comprising accessory p 2.2. The E D’Andr dicted 507 library con pectedly, w original Fri expression classes. A structed fro independen fetal liver b human gen EPO-R gen eight exon (exoplasmi domain and Importantly been detect brain, kidn macrophag as numerou of EPO and Although the EPO-R is transcribed continuously [30], hypoxia and anemia may upregulate EPO-R expression in hematopoietic tissue and brain [31]. EPO-R mRNA splicing re effi gulato factor , and [34], ing reg ents. T 79 to + The st ine re . Ove e unp o acid ly 56 -affin cular urine estern a we d cells ht, als ns inc ubiqu other h is cl huma in the ytopla e EPO ber of des an ber ha n, a v n wit portio XWS” r ligan 5]. No it any egion mal re ox 2 f the . The e 22 uman ins [4 seven mino crosslinking reagent like disuccinimidyl suberate r dissolution, cell proteins were subjected to SDS- autoradiography. Using such methods, numerous rs reported radiolabeled crosslinked species of a, and frequently more than one radiolabeled s seen [7,12,16,17]. It was suggested that differ- size of the EPO/EPO-R complex might be due to ttranslational processing of a single EPO-R pro- lso, a receptor heterodimer was proposed [19]. rvations have not been explained fully in light rent molecular mass of the EPO-R (62–66 kDa) y Western blotting. sible to modulate cell surface EPO-R expression logic response to EPO in erythroid cells. Pretreat- PO sensitive erythroid cell line (Rauscher murine emia [20,21]) with dimethyl sulfoxide or other r compounds led to a marked amplification of the ponse to EPO, including an increase in number of ding, increase in rate of response and a markedly EPO dose/response curve, consistent with greater to the hormone [22]. Binding studies showed that atment increased EPO-R density from 3000/cell ,000/cell with no significant change in receptor els [23]. Interestingly, thermodynamic analysis catchard curve that was upwardly convex, indica- itive cooperativity with a Hill coefficient, nH, of ting the presence of receptor oligomers or clusters several EPO-R molecules and, potentially, other roteins. PO-R gene ea et al. [24] isolated a cDNA encoding a pre- amino acid murine EPO-R by using an expression structed from Friend erythroleukemia cells. Unex- hereas radiolabeled EPO binding studies of the end cells revealed a single affinity class of EPO-R, of the cDNA in COS cells resulted in two affinity 508 amino acid human EPO-R cDNA was con- m a partial cDNA and an exon sequence [24] and, tly, from OCIM1 erythroleukemia cells and from y screening with murine EPO-R cDNA [25]. The e is localized to chromosome 19pter-q12 [26]. The e is approximately 6 kb in length and comprises s [27–29]. Exons 1–5 encode the extracellular c) domain, exon 6 encodes the transmembrane exons 7 and 8 encode the cytoplasmic domain. , EPO-R mRNA and/or EPO-R protein have/has ed in several non-hematopoietic tissues including ey, placenta, endothelial cells, myocardiocytes, es, retinal cells, cells of the adrenal cortex as well s human cancers. The non-hematopoietic actions non-hematopoietic EPO-R are discussed below. is mo sic re cell lators PMA flank elem the + [36]. 2.3. cytok 2.3.1 Th amin imate photo mole the m by W 66 kD throi weig natio site), with whic of the acids the c Th mem inclu mem regio regio lular “WS cal fo [44,4 exhib mic r proxi and B tion o 2.3.2 Th the h doma these ing a cient in erythroid cells than in brain [31]. Extrin- rs of EPO-R gene expression also include stem [32] and interleukin-1� [33], which are stimu- interferon-� [34], ionomycin and phorbol ester which are inhibitors. The EPO-R gene prime 5′ ion contains GATA1 [35] and SP1 [35] regulatory here is also a negative CCACC motif located in 135 fragment of the human EPO-R gene promoter ructure of the EPO-R: a member of the ceptor superfamily rall structure rocessed human EPO-R protein consists of 508 s with a predicted molecular mass of approx- kDa. It should be noted that crosslinking and ity labeling experiments have resulted in higher mass estimates of 65–105 kDa [19,25,37]. When EPO-R was expressed in COS cells followed blotting, multiple EPO-R bands of 62, 64, and re detected [38]. The endogenous EPO-R of ery- , though of somewhat higher apparent molecular o appeared as more than one size. Possible expla- lude glycosylation (there is one glycosylation itination and other modifications or interactions proteins. There is a 24 amino acid signal peptide, eaved upon processing. The extracellular portion n EPO-R contains 225 amino acids with 22 amino transmembrane domain and 236 amino acids in smic portion. -R, along with the IL-2R beta chain, is a founding the cytokine receptor superfamily [39-41], which array of other family members. Each family s a single hydrophobic transmembrane spanning ariable cytoplasmic region and an extracellular h an overall 15–35% homology. The extracel- n contains conserved cysteine residues and a motif [40–43]. This motif in the EPO-R is criti- d binding, internalization and signal transduction ne of the cytokine receptor superfamily members kinase or other enzymatic domain in the cytoplas- . There are limited homologies in the membrane gions and the so-called Box 1/proline rich motif motif [46–48], which support the mitogenic func- receptor. extracellular portion of the EPO-R 5 amino acids of the extracellular portion of EPO-R comprise two fibronectin type III-like 9]. Each domain has seven beta strands, and beta strands are connected by six loops contain- acid residues involved in EPO binding. Solution 42 W. Jelkmann et al. / Critical Reviews in Oncology/Hematology 67 (2008) 39–61 and X-ray crystallographic studies of the interaction of non-glycosylated, mutated EPO with the extracellular por- tion of the EPO-R (the so called soluble EPO-R; sEpoR) demonstrat although,