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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Anaemia is frequent in cancer and may increase tumour hypoxia that stimulates angiogenesis. However, erythropoietin is a hypoxia-inducible stimulator of erythropoiesis which seems to improve quality of life in cancer patients. Two recent phase III randomized studies showed negative results using erythropoietin in head and neck cancer patients and in metastatic breast cancer patients with impaired specific survival. In vitro and in vivo experiments have provided erythropoietin-receptor expression in endothelial cancer cells including malignant tumours of the breast, prostate, cervix, lung, head and neck, ovary, melanoma, stomach, gut, kidney etc. Biologic effect of erythropoietin and its receptor linkage induces proliferation of human breast cancer and angiogenesis and may limit anti-tumour effect of cancer treatment, in part, by tumour vascularization improvement. In addition, the use of exogenous erythropoietin could be able to favour tumour progression by improving tumour oxygenation and nutriment supply. If erythropoietin receptor were functional in human cancer, the assessment of erythropoietin receptor expression on tumour cell may help to select patients benefiting from exogenous erythropoietin. However, the relationship between erythropoietin receptor expression, tumour growth and exogenous erythropoietin, requires more studies. The results of recent clinical trials suggest that using erythropoietin should be avoided in non-anemic patients and discussed in patients receiving curative therapy.
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PMID:[Anaemia and radiation therapy]. 1567 42

Anemia is very common in head and neck cancer patients, and seems to be correlated with intratumoral hypoxia. Anemia is one of the main prognostic factors of locoregional recurrence and, in some studies, of poor survival. Blood transfusions and human recombinant erythropoietin (rHuEPO) are the two main methods used in clinical practice to correct hemoglobin level during curative treatment. Blood transfusions were rarely evaluated, and did not influence locoregional control of patients treated with radiotherapy with or without chemotherapy. Retrospective studies evaluating combined treatment of rHuEPO and radiotherapy reported positive impact on locoregional recurrence and actuarial survival. Since the end of 2003, this approach is a matter for debate after the negative results of a prospective randomized study on progression-free survival concerning head and neck cancer patients treated with definitive or postoperative external radiotherapy with or without rHuEPO. Although many biases were reported against this publication, several questions are to be answered in the near future. Among them, erythropoietin receptor expression and activation on tumour cell seem to be the more appropriate explanation of these negative results. In October 2004, preliminary results of the RTOG 99-03 study have been presented at the Astro annual meeting in Atlanta. This prospective randomized trial was designed to determine if concurrent rHuEPO administration (40,000 units) with radiotherapy (with or without chemotherapy) could improve locoregional control in non-operative head and neck cancers. In the rHuEPO arm, haemoglobin level was significantly increased compared with control arm. However, the addition of concurrent rHuEPO to definitive radiotherapy did not improve locoregional control or survival for mildly/moderately anemic patients with head and neck squamous cell carcinoma. Future clinical trials using biological markers are thus imperative to target which patients could benefit from these molecules.
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PMID:[Anemia in head and neck cancers]. 1593 8

Erythropoietin (Epo) is used for managing anemia in cancer patients. However, recent studies have raised concerns for this practice. We investigated the expression and function of Epo and the erythropoietin receptor (EpoR) in tumor biopsies and cell lines from human head and neck cancer. Epo responsiveness of the cell lines was assessed by Epoetin-alpha-induced tyrosine phosphorylation of the Janus kinase 2 (JAK2) protein kinase. Transmigration assays across Matrigel-coated filters were used to examine the effects of Epoetin-alpha on cell invasiveness. In 32 biopsies, we observed a significant association between disease progression and expression of Epo and its receptor, EpoR. Expression was highest in malignant cells, particularly within hypoxic and infiltrating tumor regions. Although both Epo and EpoR were expressed in human head and neck carcinoma cell lines, only EpoR was upregulated by hypoxia. Epoetin-alpha treatment induced prominent JAK2 phosphorylation and enhanced cell invasion. Inhibition of JAK2 phosphorylation reduced both basal and Epo-induced invasiveness. Our findings support a role for autocrine or paracrine Epo signaling in the malignant progression and local invasiveness of head and neck cancer. This mechanism may also be activated by recombinant Epo therapy and could potentially produce detrimental effects in rhEpo-treated cancer patients.
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PMID:Erythropoietin signaling promotes invasiveness of human head and neck squamous cell carcinoma. 1596 6

The management of cancer-related anemia with erythropoietic agents presents many unresolved issues. We reviewed the literature relating to epoetin alfa (Eprex)/Epypo); Ortho Biotech/Janssen-Cilag, High Wycombe, United Kingdom, http://www.orthobiotech.co.uk; Procrit); Ortho Biotech Products, L.P., Bridgewater, NJ, http://www.orthobiotech.com), epoetin beta (NeoRecormon); Hoffman-La Roche, Basel, Switzerland, http://www.roche.com), and darbepoetin alfa (Aranesp); Amgen Inc., Thousand Oaks, CA, http://www.amgen.com) highlighting the results of published clinical trials, safety, and cost-effectiveness. Studies were identified through MEDLINE and the bibliographies of relevant articles. Epoetin alfa, epoetin beta, and darbepoetin alfa have differing pharmacokinetic and pharmacodynamic profiles. They are all effective at reducing transfusion requirements and improving health-related quality-of-life parameters, irrespective of tumor response. A direct comparison between epoetin alfa and darbe poetin alfa is based on limited evidence, which does not allow definitive conclusions about relative efficacy and cost-effectiveness. No predictive factors for response to erythropoietic agents have been validated in prospective trials. The most consistent adverse events are thrombotic and may occur irrespective of an increase in hemoglobin. Recent research indicates that the erythropoietin receptor is expressed in several cancer cell lines, raising the concern of possible stimulation of tumor cell growth by these drugs. Studies on the cost-effectiveness of erythropoietins, particularly compared with transfusion therapy, have been challenging to conduct and analyze and have generated ambiguous results. The use of erythropoietins needs to be optimized in terms of cost-effectiveness, and issues surrounding safety need to be clarified. A stronger methodology for clinical studies and the design of new, randomized, clinical trials is a major priority.
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PMID:Management of cancer-related anemia with erythropoietic agents: doubts, certainties, and concerns. 1607 21

Erythropoietin is a hypoxia-induced hormone that is a major regulator of normal erythropoiesis. Over the last decade, the production of recombinant human erythropoietin has revolutionized the treatment of anemia associated with chronic renal failure, and has led to a greater understanding of anemia pathophysiology and to the elucidation of the interactions of erythropoietin, iron, and erythropoiesis. Anemia has been shown to be independently associated with increased mortality and disease progression. Potential survival benefits associated with correction of anemia have expanded considerably the indications of erythropoietin use in various patient populations and are leading to consideration of earlier, more aggressive treatment of mild to moderate anemia. The results of such treatment are promising in a variety of new clinical settings, including anemia associated with congestive heart failure. Furthermore, the erythropoietin receptor is widely distributed in the cardiovascular system, including endothelial cells, smooth muscle cells and cardiomyocytes and preclinical studies have established erythropoietin to be a pleiotropic cytokine with anti-apoptotic activity and tissue-protective actions in the cardiovascular system, beyond correction of hemoglobin levels. Despite some potential adverse effects, such as hypertension, and the occurrence of erythropoietin resistance, early studies in heart failure patients with anemia suggest that erythropoietin therapy is safe and effective in reducing left ventricular hypertrophy, enhancing exercise performance and increasing ejection fraction. Anemia is found in about one-third of all cases of congestive heart failure (CHF). The most likely common cause is chronic renal insufficiency, which is present in about half of all CHF cases. However, anemia can occur in CHF without renal insufficiency and is likely to be due to excessive cytokine production. The anemia itself can worsen cardiac function, both because it causes cardiac stress through tachycardia and increased stroke volume, and because it can cause a reduced renal blood flow and fluid retention, adding further stress to the heart. Long-standing anemia of any cause can cause left ventricular hypertrophy, which can lead to cardiac cell death through apoptosis and worsen CHF. Therefore, a vicious circle, cardio-renal anemia syndrome, is set up wherein CHF causes anemia, and the anemia causes more CHF and both damage the kidneys worsening the anemia and the CHF further and increasing mortality. There is now evidence that early correction of the CHF anemia with subcutaneous erythropoietin and intravenous iron improves shortness of breath and fatigue, cardiac function, renal function and exercise capacity, reducing the need for hospitalization and improving quality of life. In the present review we discuss the data on current clinical use of erythropoietin in cardiovascular disease, with the main focus on the treatment of congestive heart failure, and summarize the advances and progress made in the understanding of the hematopoietic and pleiotropic effects of erythropoietin in the cardiovascular system.
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PMID:Erythropoietin in heart failure and other cardiovascular diseases: hematopoietic and pleiotropic effects. 1624 29

Up-regulation of tumor necrosis factor alpha (TNFalpha) is linked to solid tumors as well as to hematologic disorders including different forms of anemia and multiple myeloma. This cytokine was shown to contribute to inhibition of erythroid maturation mechanisms which are characterized by the expression of specific genes regulated by GATA-1 and NF-E2 transcription factors. Here, we assessed the inhibiting effect of TNFalpha on erythroid differentiation using K562 cells which can be chemically induced to differentiate towards the erythroid pathway by aclacinomycin A, an anthracyclin. Results show that induced hemoglobinization of K562 cells as well as gamma-globin and erythropoietin receptor gene expression are decreased by TNFalpha via the inhibition of GATA-1 at its mRNA and protein expression level. Additionally, both constitutive and induced binding activity of GATA-1 is abolished and induced activation of a GATA-1 driven luciferase reporter construct is inhibited. Altogether, our results provide insight into the molecular mechanisms of inflammation-induced inhibition of erythroid differentiation.
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PMID:Tumor necrosis factor alpha inhibits aclacinomycin A-induced erythroid differentiation of K562 cells via GATA-1. 1627 27

Cytokine signaling plays an important role in the survival and differentiation of vertebrate hematopoietic cells. In red blood cells, erythropoietin is a key component of the differentiation program and maintains the homeostasis of the erythroid compartment. In the adult, anemia stimulates high levels of circulating erythropoietin that drives erythropoiesis to restore normal levels of red blood cells in circulation. Erythropoietin activates the erythropoietin receptor on immature red blood cell precursors to promote their survival and differentiation. Although extensively studied in mammalian systems, a complete understanding of the function of the erythropoietin receptor during primitive erythropoiesis has been lacking. To address this problem, we have cloned the Xenopus laevis erythropoietin receptor in order to further understand the development of primitive erythropoiesis. The amphibian erythropoietin receptor shares 33% amino acid sequence identity with the mammalian erythropoietin receptors and contains the conserved extracellular ligand binding and fibronectin domains, the WSXWS motif common to cytokine receptors, and several tyrosine phosphorylation sites located on the intracellular domain of the receptor. Expression of the erythropoietin receptor is first detected by in situ hybridization in the ventral blood island during tailbud stages.
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PMID:Cloning and expression pattern of the Xenopus erythropoietin receptor. 1637 61

Evidence for erythropoietin signaling has been shown in several nonhematopoietic tissues, including many tumor types. Clinically, recombinant erythropoietin treatment of malignancy-related anemia has yet to be definitively associated with any modulation of chemotherapy or radiotherapy efficacy. Preclinically, recombinant erythropoietin has been shown to increase tumor oxygenation, but the direct effects of recombinant erythropoietin on tumor cells that express erythropoietin receptor are not yet fully characterized. This study examined the effects of exogenous recombinant erythropoietin on rodent mammary adenocarcinoma cells (R3230) in vitro and in vivo, and determined the effects of systemic recombinant erythropoietin on tumor growth delay in Taxol treatment. We showed that systemic recombinant erythropoietin treatment of rats bearing R3230 mammary carcinomas induced an increase in phospho-Akt levels within tumor cells. This was associated with a decrease in the frequency of apoptotic cells in tumors from recombinant erythropoietin-treated animals, but did not noticeably affect tumor growth rate. In vitro studies revealed that not only does recombinant erythropoietin induce Akt phosphorylation, but it also stimulates phosphorylation of p44/42 mitogen-activated protein kinases, Erk1 and Erk2. Activation of erythropoietin-mediated signaling in R3230 cells was associated with dose-dependent inhibition of apoptosis in response to Taxol treatment and serum starvation, an effect that was blocked by the addition of a phosphatidylinositol-3-kinase inhibitor. Despite its cytoprotective effects in vitro, recombinant erythropoietin did not significantly affect tumor growth delay in Taxol treatment. This study shows direct recombinant erythropoietin-mediated activation of specific intracellular signaling pathways in mammary adenocarcinoma cells in vivo and in vitro. Modulation of tumor apoptosis pathways by recombinant erythropoietin may have negative consequences by decreasing the chemosensitivity and radiosensitivity of erythropoietin receptor-positive breast tumors, although it did not have any obvious effects on growth with or without chemotherapy in this model.
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PMID:Erythropoietin inhibits apoptosis in breast cancer cells via an Akt-dependent pathway without modulating in vivo chemosensitivity. 1650 9

The nuclear proto-oncogene c-myb plays crucial roles in the growth, survival, and differentiation of hematopoietic cells. We established three lines of erythropoietin receptor-transgenic mice and found that one of them exhibited anemia, thrombocythemia, and splenomegaly. These abnormalities were independent of the function of the transgenic erythropoietin receptor and were observed exclusively in mice harboring the transgene homozygously, suggesting transgenic disruption of a certain gene. The transgene was inserted 77 kb upstream of the c-myb gene, and c-Myb expression was markedly decreased in megakaryocyte/erythrocyte lineage-restricted progenitors (MEPs) of the homozygous mutant mice. In the bone marrows and spleens of the mutant mice, numbers of megakaryocytes were increased and numbers of erythroid progenitors were decreased. These abnormalities were reproducible in vitro in a coculture assay of MEPs with OP9 cells but eliminated by the retroviral expression of c-Myb in MEPs. The erythroid/megakaryocytic abnormalities were reconstituted in mice in vivo by transplantation of mutant mouse bone marrow cells. These results demonstrate that the transgene insertion into the c-myb gene far upstream regulatory region affects the gene expression at the stage of MEPs, leading to an imbalance between erythroid and megakaryocytic cells, and suggest that c-Myb is an essential regulator of the erythroid-megakaryocytic lineage bifurcation.
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PMID:Transgene insertion in proximity to the c-myb gene disrupts erythroid-megakaryocytic lineage bifurcation. 1694 Jan 83

Recent evidence confirms the presence of erythropoietin receptors on a variety of cancer cells. This has raised concerns about the use of erythropoiesis-stimulating agents in the treatment of cancer-related anemia. Having previously identified expression of functional erythropoietin receptors in a non-small cell lung carcinoma cell line, H838, which activated key signaling pathways in response to erythropoietin stimulation, we now demonstrate impaired downregulation of the erythropoietin receptor in these tumor cells. The erythropoietin receptor is not ubiquitinated following erythropoietin stimulation in this cancer cell line, and there is no turnover of the receptor in either unstimulated or stimulated cells. Compounding this blunted response is impaired SOCS3 induction downstream of erythropoietin stimulation and an extremely delayed SOCS1 response. If this finding in non-small cell lung carcinoma is a widespread phenomenon, then impaired erythropoietin receptor downregulation and degradation in tumor cells has clinical implications for those patients receiving erythropoiesis-stimulating agents for cancer-related anemia.
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PMID:Impaired downregulation following erythropoietin receptor activation in non-small cell lung carcinoma. 1703 66


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