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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Erythropoietin (Epo) is the major regulator of erythroid viability, proliferation, and differentiation. These functions are transduced following binding of Epo to a specific cell surface receptor, the erythropoietin receptor (EpoR), a member of a new cytokine receptor superfamily of receptors. An activating mutation in the murine EpoR has been described (cEpoR) and confers growth factor-independent growth upon an IL-3-dependent pro-B cell. To determine the effect of an activating mutation in the EpoR upon erythropoiesis specifically and hematopoiesis generally, we infected hematopoietic progenitors and mice with a recombinant erythroleukemic spleen focus-forming virus (SFFV), lacking its pathogenic env gene but expressing cEpoR (SFFVcEpoR). In vitro, infection with SFFVcEpoR resulted in factor-independent growth and development of CFU-Es yet had no effect on BFU-E growth, mixed colony growth, or myeloid colony growth. Mice infected with SFFVcEpoR, but not a virus expressing wild type EpoR (SFFVEpoR), developed erythrocytosis and splenomegaly.
Leukemia 1992
PMID:Mutation in murine erythropoietin receptor induces erythropoietin-independent erythroid proliferation in vitro, polycythemia in vivo. 131 65

The recently derived J2E cell lines differentiate in response to erythropoietin. However, during the course of growth in culture, a subclone has emerged which fails to synthesize hemoglobin or show accelerated proliferation following hormonal stimulation. The inability to respond to erythropoietin is not due to autocrine production of the hormone by these cells. Moreover, it appears unlikely that the block occurs at the level of the erythropoietin receptor as the number of receptors per cell was only marginally reduced and both ligand binding and internalization were normal. It is likely, therefore, that the intracellular signal transduction mechanism is faulty or a defect in hemoglobin production has developed.
Leukemia 1990 Jan
PMID:Evolution of a mutant J2E erythroid cell line which does not respond to erythropoietin. 168 37

We have characterized the structure of the erythropoietin receptor gene promoter in normal murine erythroid tissues and in Friend-induced tumor cells. Using primer extension analysis, we identified two distinct transcriptional start sites, which were located 2 base pairs apart in anemic spleens, fetal liver, Friend-induced tumoral spleens, and mouse erythro-leukemia cells. In contrast, transcription was initiated 37 base pairs upstream of the normal cap sites in T3Cl-2, a Friend virus-induced murine erythroleukemia cell line. Also, the erythropoietin receptor mRNA in T3Cl-2 was overexpressed when compared with other erythroleukemia cell lines. We found that abnormal transcription occurring in T3Cl-2 cells resulted from an erythropoietin receptor gene alteration. Indeed, one erythropoietin receptor allele was rearranged by insertion of a spleen focus-forming virus long terminal repeat within the noncoding region of the first exon, 45 bases upstream of the ATG initiation codon and in the same 5'----3' orientation. The transcription of the rearranged allele was shown to be directed from the long terminal repeat promoter, leading to a long terminal repeat-erythropoietin receptor fusion transcript, whereas the normal erythropoietin receptor allele was weakly transcribed. Such altered receptor gene activation may provide a positive pressure in the development of tumorigenic erythroleukemia.
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PMID:Spleen focus-forming virus long terminal repeat insertional activation of the murine erythropoietin receptor gene in the T3Cl-2 friend leukemia cell line. 184 97

The Friend or Moloney mink cell focus-forming (MCF) virus encodes a recombinant-type envelope glycoprotein, gp70, that is closely related to the membrane glycoprotein, gp55, of Friend spleen focus-forming virus (SFFV). We have shown previously that gp55 has the ability to activate cell growth by binding to the cellular receptor for erythropoietin. Here we show that gp70 encoded by either the Friend or Moloney MCF virus also binds to the erythropoietin receptor and that coexpression of the receptor and gp70 in an interleukin-3 (IL-3)-dependent cell line can activate IL-3-independent growth. Furthermore, when the cDNA for the human IL-2 receptor beta chain, which is related by sequence to the erythropoietin receptor, was introduced into this cell line, it became growth factor independent after infection either with SFFV or with one of the two MCF viruses but not with an ecotropic virus. Based on these observations, we propose a mechanism for the early stage of leukemogenesis induced by the MCF-type murine leukemia viruses.
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PMID:Mechanism of leukemogenesis induced by mink cell focus-forming murine leukemia viruses. 185 20

The GM-CSF receptor belongs to the cytokine receptor superfamily. The high-affinity receptors of this class are lacking intrinsic tyrosine kinase domains. The GM-CSF receptor consists of alpha and beta subunits. The beta subunit is shared with the receptors of IL-3 and IL-5. In addition to the membrane bound forms the receptors have been found to possess soluble isoforms. Since retroviral infection of the human GM-CSF dependent cell line, TF-1, leads to factor independent growth by increased expression of the GM-CSF receptor alpha chain in a subgroup of infected clones, we were interested in studying the role of this chain in human AML. Further considering that a point mutation in the extracellular domain of the erythropoietin receptor, also a member of the cytokine receptor superfamily, resulted in constitutive activation of a murine cell line, we investigated the possibility that a point mutation of the GM-CSF receptor was responsible for autonomous growth of AML cells. We sequenced a segment of the receptor coding for the extracellular domain of the alpha subunit. cDNA was prepared from peripheral blood or bone marrow cells from 24 patients with AML, from four patients with MDS and from three human myeloid cell lines. The region of interest was amplified with two rounds of PCR reactions with nested primers, covering five overlapping fragments, and directly sequenced using a non-radioactive technique. No point mutations were found in the investigated samples. Thus, point mutations in this segment of the GM-CSF receptor gene do not seem to play an important role in the transformation process of human acute leukemia.
Leukemia 1995 Jan
PMID:Absence of point mutations in the extracellular domain of the alpha subunit of the GM-CSF receptor in a series of patients with acute myeloid leukemia (AML). 784 15

The development of retroviral vectors that target specific cell types could have important implications for the design of gene therapy strategies. A chimeric protein containing the polypeptide hormone erythropoietin and part of the env protein of ecotropic Moloney murine leukemia virus was engineered into the virus. This murine virus became several times more infectious for murine cells bearing the erythropoietin receptor, and it also became infectious for human cells bearing the erythropoietin receptor. This type of tissue-specific targeting by means of ligand-receptor interactions may have broad applications to a variety of gene delivery systems.
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PMID:Tissue-specific targeting of retroviral vectors through ligand-receptor interactions. 797 23

The 10A1 murine leukemia virus induces tumors that lack lineage-specific markers found on myeloid, T-cell, and B-cell lineages. Either erythroid or multipotent stem cells can have this phenotype; therefore we have used fluorescence-activated cell sorter analysis with either multipotent stem cell markers or markers found on lineage-restricted precursors to differentiate between these two possibilities. The results showed that tumors induced by 10A1 expressed multipotent stem cell markers as well as some lineage-restricted precursor markers. To further study the tumor phenotype, we analyzed total RNAs from 10A1-induced tumors by Northern blotting for c-kit, erythropoietin receptor, and T-cell gamma receptor mRNAs. Most of the tumors contained these mRNAs, which are characteristic of early hematopoietic cells. These results are consistent with the hypothesis that 10A1-induced tumor cells are early multipotent hematopoietic stem cells. Southern blot analysis revealed that 14 of 14 10A1-induced tumor cell DNAs examined contained MuLV integrations into the fli-1 gene. The results strongly suggested that promoter insertion into fli-1 is required for tumor formation.
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PMID:10A1 MuLV induces a murine leukemia that expresses hematopoietic stem cell markers by a mechanism that includes fli-1 integration. 797 58

If the env gene of spleen focus-forming virus (SFFV) is replaced by a cDNA encoding a constitutively active form of the erythropoietin receptor, EPO-R(R129C), the resultant recombinant virus, SFFVcEPO-R, induces transient thrombocytosis and erythrocytosis in infected mice. Clonogenic progenitor cell assays of cells from the bone marrow and spleens of these infected mice suggest that EPO-R(R129C) can stimulate proliferation of committed megakaryocytic and erythroid progenitors as well as nonerythroid multipotent progenitors. From the spleens of SFFVcEPO-R-infected mice, eight multiphenotypic immortal cell lines were isolated and characterized. These included primitive erythroid, lymphoid, and monocytic cells. Some expressed proteins characteristic of more than one lineage. All cell lines resulting from SFFVcEPO-R infection contained a mutant form of the p53 gene. However, in contrast to infection by SFFV, activation of PU.1 gene expression, by retroviral integration, was not observed. One cell line had integrated a provirus upstream of the fli-1 gene, in a location typically seen in erythroleukemic cells generated by Friend murine leukemia virus infection. This event led to increased expression of fli-1 in this cell line. Thus, infection by SFFVcEPO-R can induce proliferation and lead to transformation of nonerythroid as well as very immature erythroid progenitor cells. The sites of proviral integration in clonal cell lines are distinct from those in SFFV-derived lines.
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PMID:A constitutively activated erythropoietin receptor stimulates proliferation and contributes to transformation of multipotent, committed nonerythroid and erythroid progenitor cells. 813 32

Erythropoietin (EPO) regulates proliferation and differentiation and prevents apoptosis of erythroid progenitor cells by binding to erythropoietin receptor (EPOR) expressed on the surface of those cells. The mechanism by which EPO signal is transmitted to the cells through EPOR is still unclear. In the present study, we introduced and expressed EPOR in an interleukin-3 (IL-3) dependent pro-B cell line, BAF-B03 and an interleukin-2 (IL-2)-dependent cytotoxic T cell line, CTLL-2 and analyzed their growth response to EPO and the DNA breakdown characteristic to apoptosis after deprivation of the growth factor. BAF-B03-derived cells expressing EPOR proliferated in response to EPO but CTLL-2-derived cells expressing EPOR (C/EPOR) did not. DNA from C/EPOR cells cultured in the absence of IL-2 with or without EPO had similar patterns of DNA breakdown. These results suggest that downstream signaling pathways for the cell proliferation and apoptosis-block are, at least, partially different between EPOR and IL-2 receptor (IL-2R).
Leukemia 1994 Apr
PMID:Erythropoietin receptor and interleukin-2 receptor use different downstream signaling pathways for proliferation and apoptosis-block. 815 74

Several motifs are conserved in the extracellular domain of the cloned chains of the recently described cytokine receptor superfamily. One of them, usually close to the transmembrane region, is the 'WS motif'. Its function remains unknown, but it has been recently shown that the integrity of this motif is essential for interleukin 2 receptor beta-chain and erythropoietin receptor activity [Miyazaki, T., Maruyama, M., Yamada, G., Hatakeyama, M. & Taniguchi, T. (1991). EMBO J., 10, 3191-3197; Watowich, S.S., Yoshimura, A., Longmore, G.D., Hilton, D.J., Hoshimura, Y. & Lodish, H.R. (1992). Proc. Natl. Acad. Sci. USA, 89, 2140-2144]. This WS motif is present in the v-mpl oncogene, which has been transduced in the myeloproliferative leukemia virus (MPLV). v-mpl encodes a truncated transmembrane protein that belongs to this growth factor receptor family. We demonstrate that determinants of MPLV pathogenesis are encoded by the env-mpl fusion gene and that the complete deletion of the WS motif does not abolish MPLV oncogenic properties.
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PMID:The 'WS motif' common to v-mpl and members of the cytokine receptor superfamily is dispensable for myeloproliferative leukemia virus pathogenicity. 838 60


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