Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04141 (granulocyte-macrophage colony-stimulating factor)
 6,790 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The lymphokine interleukin-3 (IL-3) promotes the growth and survival of immature hematopoietic cells. Previous studies have shown that IL-3 induces rapid increases in protein-tyrosine kinase (PTK) activity in IL-3--dependent cells. Unlike some other hematopoietic growth factor receptors (eg, c-fms and c-kit), however, the known subunits of the IL-3 receptor (IL-3R) lack intrinsic kinase activity. Recently, it was reported that the IL-2R (whose p75 beta-subunit shares sequence homology with a known murine IL-3R subunit and a common beta-subunit of the human IL-3R and granulocyte-macrophage colony-stimulating factor [GM-CSF] receptors) can physically associate with and regulate the activity of the SRC-family PTK, p56-LCK. Because most IL-3--dependent cells contain p53/56-LYN, but not p56-LCK, we explored the effects of IL-3 on the activities of LYN and other SRC-like PTKs in two human leukemic cell lines, AML-193 and TALL-101, which are phenotypically myeloid, and whose in vitro growth is dependent on IL-3. These cells expressed four of the eight known SRC-family proto-oncogenes: lyn, fyn, yes, and hck. When these factor-dependent leukemic cell lines were deprived of lymphokine to achieve cellular quiescence and then restimulated with IL-3, rapid increases (detectable within 1 minute and maximal by 10 minutes) were observed in the activity of the p53/56-LYN kinase, as assessed by in vitro kinase assays. In contrast, no alteration in the activities of other SRC-family PTKs present in these cells was detected after restimulation with IL-3 under the same conditions. This effect of IL-3 reflected an increase in the specific activity of the LYN kinase, because levels of the 53-Kd and 56-Kd LYN proteins were unaltered by IL-3 stimulation, as assessed by immunoblotting. Furthermore, the magnitude of these inducible increases in LYN kinase activity was dependent on the concentration of IL-3, and correlated with IL-3--induced proliferation. The IL-3--induced upregulation of LYN kinase activity may be mediated by the 120-Kd common subunit of the human IL-3 and GM-CSF receptors, because GM-CSF also stimulated marked increases in the activity of the LYN kinase, whereas granulocyte-CSF (G-CSF) did not, despite inducing cellular proliferation. These observations provide the first example of an IL-3--regulable PTK, and strongly suggest that the p53/56-LYN kinase participates in early IL-3--initiated signalling events, at least in some human leukemic cell lines.
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PMID:Interleukin-3 regulates the activity of the LYN protein-tyrosine kinase in myeloid-committed leukemic cell lines. 163 19

Mast cell growth factor (MGF), the ligand for the c-kit receptor, has been shown to be a hematopoietic growth factor that preferentially stimulates the proliferation of immature hematopoietic progenitor cells (HPC). We studied the effect of MGF on the in vitro growth of clonogenic leukemic precursor cells in the presence or absence of interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), and/or erythropoietin (EPO). Leukemic blood and bone marrow cells from patients with various types of acute myeloid leukemia (AML), chronic myeloid leukemia (CML) in chronic phase, as well as bone marrow samples from patients with myelodysplastic syndromes (MDS) were studied. MGF as a single factor did not induce significant colony formation by clonogenic leukemic precursor cells. In the presence of IL-3 and/or GM-CSF, MGF weakly stimulated the colony formation by clonogenic precursor cells from patients with AML. In contrast, in the presence of IL-3 and/or GM-CSF, MGF strongly induced both size and number of leukemic colonies from patients with CML in chronic phase. Furthermore, in the presence of EPO, MGF strongly stimulated erythroid colony formation by CML precursor cells. Cytogenetic analysis of the colonies showed that all metaphases after 1 week of culture were derived from the leukemic clone. In patients with MDS, MGF strongly stimulated myeloid colony formation in the presence of IL-3 and/or GM-CSF (up to fourfold), and erythroid colony formation in the presence of EPO (up to eightfold). Not only the number, but also the size of the colonies increased. In the presence of MGF, the percentage of normal metaphases increased in three patients tested after 1 week of culture compared with the initial suspension, suggesting that the normal HPC were preferentially stimulated compared with the preleukemic precursor cells. In the absence of exogenous EPO and in the presence of 10% human AB serum, MGF in the presence of IL-3 and/or GM-CSF induced erythroid colony formation from normal bone marrow and patients with MDS or CML, illustrating that MGF greatly diminished the EPO requirement for erythroid differentiation. These results indicate that MGF may be a candidate as a hematopoietic growth factor to stimulate normal hematopoiesis in patients with acute myeloid leukemia, or with myelodysplastic syndromes.
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PMID:Effect of mast cell growth factor (c-kit ligand) on clonogenic leukemic precursor cells. 163 26

We examined the effects of various hemopoietins on c-kit mRNA and protein expression. Interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor, and erythropoietin, but not IL-4, down-regulated levels of c-kit mRNA expressed by mast cells and stem cell progenitors. The effect of IL-3 was dominant and independent of cell growth or viability and was paralleled by reduced expression in c-kit protein. These observations indicate that regulation of c-kit expression is closely interlinked with the molecular mechanisms triggered by erythropoietin, IL-3, and granulocyte-macrophage colony-stimulating factor.
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PMID:Modulation of c-kit mRNA and protein by hemopoietic growth factors. 170 97

Purified natural (n) and recombinant (r) murine (mu) mast cell growth factor (MGF, a c-kit ligand) were evaluated alone and in combination with r human (hu) erythropoietin (Epo), rhu granulocyte-macrophage colony-stimulating factor (rhuGM-CSF), rhuG-CSF, and/or rhuM-CSF for effects in vitro on colony formation by multipotential (colony-forming unit-granulocyte, erythroid, monocyte, megakaryocyte [CFU-GEMM]), erythroid (burst-forming unit erythroid [BFU-E]) and granulocyte-macrophage (CFU-GM) progenitor cells from normal human bone marrow. MGF was a potent enhancing cytokine for Epo-dependent CFU-GEMM and BFU-E colony formation, stimulating more colonies and of a larger size than either rhu interleukin-3 (rhuIL-3) or rhuGM-CSF. MGF, especially at lower concentrations, also acted with rhuIL-3 or rhuGM-CSF to enhance Epo-dependent CFU-GEMM and BFU-E colony formation. MGF had little stimulating activity for CFU-GM colonies by itself, but in combination with suboptimal to optimal amounts of rhuGM-CSF enhanced the numbers and the size of CFU-GM colonies in an additive to greater than additive manner. While we did not detect an effect of MGF on CFU-G colony numbers stimulated by maximal concentrations of rhuG-CSF, MGF did enhance the size of CFU-G-derived colonies. MGF did not enhance the activity of rhuM-CSF. In a comparative assay, maximal concentrations of rmu and rhuMGF were equally effective in the enhancement of human bone marrow colony formation, but rhuMGF, in contrast to rmuMGF, did not at the concentrations tested enhance colony formation by mouse bone marrow cells. MGF effects on BFU-E, CFU-GM, and CFU-GEMM may be direct acting ones as MGF-enhanced colony formation by these cells in highly enriched progenitor cell populations of CD34 HLA-DR+ and CD34 HLA-DR+CD33- sorted cells in which greater than or equal to 1 of 2 cells was a BFU-E plus CFU-GM plus CFU-GEMM. MGF appears to be an early acting cytokine that preferentially stimulates the growth of immature hematopoietic progenitor cells.
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PMID:Effect of murine mast cell growth factor (c-kit proto-oncogene ligand) on colony formation by human marrow hematopoietic progenitor cells. 170 71

Murine mast cell growth factor (muMGF), a c-kit ligand, has additive to greater-than-additive effects on in vitro colony formation of murine and human myeloid progenitor cells stimulated with erythropoietin, granulocyte-macrophage colony-stimulating factor (GM-CSF), and/or interleukin (IL)-3. To confirm direct-acting effects on responding cells, MGF was assessed alone and in combination with other cytokines for effects on the proliferation of the human factor-dependent cell line, M07e. Proliferation was assayed in liquid culture by [3H]thymidine uptake and in semisolid medium by colony formation. Purified recombinant (r) muMGF (25-50 ng/ml) by itself had proliferative activity but less than r human (hu) GM-CSF. In combination with rhuGM-CSF (250 U/ml) or IL-3 (500 U/ml), rmuMGF (25 ng/ml) enhanced [3H]thymidine uptake two- to sevenfold greater than the sum of the effects of each factor alone. Similar enhancement was seen in the number and size of colonies formed. When MGF was used in combination with rhuIL-4 (500-1000 U/ml), rhuIL-6 (5 ng/ml), rhuIL-9 (5-10 U/ml), or rhu interferon gamma (IFN-gamma; 250-500 U/ml) (factors that alone stimulate little proliferation), [3H]thymidine uptake and colony formation were respectively increased 2- to 11- and 3- to 55-fold over the sum of each of the effects of the factors alone. Exposure of 5 x 10(5) cells/ml to 50 ng/ml MGF for 24 h, a time during which synergism is noted with MGF plus either GM-CSF or IL-3, did not change GM-CSF or IL-3 receptor binding affinity or the number of binding sites. Exposure of cells to MGF for 48 h did not alter subsequent GM-CSF- or IL-3-stimulated proliferation. The results suggest that M07e cells will be useful as a model for the analysis of intracellular biochemical mechanisms of the direct-acting proliferative and synergistic effects of MGF.
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PMID:Mast cell growth factor (c-kit ligand) enhances cytokine stimulation of proliferation of the human factor-dependent cell line, M07e. 171 2

To provide insights into the pathogenesis of Diamond-Blackfan anemia, we examined the in vitro response of erythroid progenitors to the recently isolated ligand for c-kit (stem cell factor, SCF). For these studies, marrow or blood mononuclear cells from 10 Diamond-Blackfan patients were cultured with erythropoietin (Ep), Ep and interleukin-3, Ep and granulocyte-macrophage colony-stimulating factor, or Ep and lymphocyte conditioned media (LCM). These combinations were tested in the presence or absence of SCF. The mean number of cells per erythroid burst increased 5 to 50-fold in cultures containing SCF. Furthermore, many additional erythroid bursts were seen (mean increment 3.2 x baseline values). Although burst-forming unit-erythroid (BFU-E) from all patients responded, there were differences among individuals in the sensitivity of their BFU-E to SCF. In six patients and all control studies, plateau frequencies of erythroid bursts were achieved with less than or equal to 10 ng/mL SCF, whereas in studies from the other four patients, over 50 ng/mL SCF was required. These data invite speculation that the c-kit receptor/ligand axis is involved in the pathogenesis of Diamond-Blackfan anemia. More importantly and regardless of whether the observed patterns of response reflect the primary defect or an epiphenomenon, our data strongly support a therapeutic trial of SCF in patients with Diamond-Blackfan anemia.
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PMID:Diamond-blackfan anemia: in vitro response of erythroid progenitors to the ligand for c-kit. 171 87

The replating capability of human multipotential (colony-forming unit-granulocyte-erythrocyte-macrophage-megakaryocyte [CFU-GEMM]) and erythroid (burst-forming unit-erythroid [BFU-E]) progenitors was assessed in vitro as a potential measure of self-renewal using purified, recombinant (r) human (hu) or murine (mu) mast cell growth factor (MGF), a ligand for the c-kit proto-oncogene receptor. Primary cultures of human umbilical cord blood or adult human bone marrow cells were initiated in methylcellulose with erythropoietin (Epo) alone or in combination with rhu interleukin-3 (IL-3) or MGF. Individual day 14 to 18 CFU-GEMM or BFU-E colonies were removed from primary cultures and reseeded into secondary methylcellulose cultures containing a combination of Epo, MGF, and rhu granulocyte-macrophage colony-stimulating factor (GM-CSF). The data showed a high replating efficiency of cord blood and bone marrow CFU-GEMM in response to Epo + MGF in terms of the percentage of colonies that could be replated and the number of secondary colonies formed per replated primary colony. The average number of hematopoietic colonies and clusters apparent from replated cultures of cord blood or bone marrow CFU-GEMM stimulated by Epo + MGF was greater than with Epo + rhuIL-3 or Epo alone. Replated cord blood CFU-GEMM gave rise to CFU-GEMM, BFU-E, and GM colony-forming units (CFU-GM) in secondary cultures. Replated bone marrow CFU-GEMM gave rise mainly to CFU-GM in secondary cultures. A more limited capacity for replating of cord blood and bone marrow BFU-E was observed. These studies show that CFU-GEMM responding to MGF have an enhanced replating potential, which may be promoted by MGF. These studies also support the concept that MGF acts on more primitive progenitors than IL-3.
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PMID:Mast cell growth factor (c-kit ligand) supports the growth of human multipotential progenitor cells with a high replating potential. 171 90

An evaluation of the effects of a recombinant, soluble form of the c-kit ligand alone and in combination with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3) on the regulation of human megakaryocytopoiesis was performed using a serum-depleted clonal assay system and a long-term bone marrow culture system. The effects of the c-kit ligand on the primitive megakaryocyte (MK) progenitor cell, the burst-forming unit-megakaryocyte (BFU-MK), and the more differentiated colony-forming unit-megakaryocyte (CFU-MK) were determined. The c-kit ligand alone had no megakaryocyte colony-stimulating activity (MK-CSA) but was capable of augmenting the MK-CSA of both GM-CSF and IL-3. The range of synergistic interactions of c-kit ligand varied with the class of MK progenitor cell assayed. In the case of the BFU-MK, the c-kit ligand synergistically augmented the numbers of colonies formed in the presence of IL-3, but not GM-CSF, but increased the size of BFU-MK-derived colonies cloned in the presence of both of these cytokines. However, at the level of the CFU-MK, c-kit ligand synergized with both GM-CSF and IL-3 by increasing both colony numbers and size. Although the c-kit ligand alone exhibited limited potential in sustaining long-term megakaryocytopoiesis in vitro, it synergistically augmented the ability of IL-3, but not GM-CSF, to promote long-term megakaryocytopoiesis. These data indicate that multiple cytokines are necessary to optimally stimulate the proliferation of both classes of MK progenitor cells and that the c-kit ligand plays a significant role in this process by amplifying the MK-CSA of both GM-CSF and IL-3.
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PMID:Effect of c-kit ligand on in vitro human megakaryocytopoiesis. 172 39

The c-kit proto-oncogene encodes a receptor tyrosine kinase that is thought to play an important role in hematopoiesis. In a series of human acute myeloblastic leukemia (AML), the expression of the c-kit proto-oncogene and its product was studied by means of Northern blot and immunoblot analyses. The c-kit mRNA was expressed in 20 of 25 cases of AML, and in those cases the product of the c-kit proto-oncogene was detected by immunoblotting with anti-c-kit antibody. The expression of c-kit transcripts and protein was barely detectable in normal bone marrow cells as a control. The expression of c-kit transcript did not correlate with the French-American-British classification nor clinical manifestations. In 6 of 11 cases that expressed c-kit product, AML cells were found to proliferate in response to recombinant human stem cell factor (rhSCF), the ligand for c-kit, and the synergistic stimulation of AML cells was observed by rhSCF and granulocyte-macrophage colony-stimulating factor. Immunoblotting with anti-phosphotyrosine antibody showed that the c-kit receptor protein was detectably phosphorylated in 7 of 12 cases tested before the stimulation with rhSCF, while the rhSCF treatment resulted in an increased tyrosine phosphorylation of c-kit in AML cells. These results indicate that c-kit proto-oncogene is expressed in most cases of AML and is functional in terms of supporting proliferation.
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PMID:Expression and functional role of the proto-oncogene c-kit in acute myeloblastic leukemia cells. 172 40

The c-kit proto-oncogene encodes a receptor having tyrosine-specific kinase activity and has been mapped to chromosome 4 in the human and chromosome 5 in the mouse, at the dominant white spotting locus (W). Mutations at the W locus affect various aspects of murine hematopoiesis. The c-kit proto-oncogene has been shown to be expressed by leukemic myeloblasts, but not by normal unseparated human bone marrow cells. The role of this oncogene in differentiation and proliferation of human hematopoietic progenitors is presently undefined. To determine c-kit expression by normal hematopoietic progenitors, CD34+ cells were isolated from disease-free human bone marrow, and RNA-based polymerase chain reaction (PCR) techniques were used to assess expression. By this method, we have demonstrated c-kit expression by CD34+ bone marrow progenitors. To address the functional requirement for c-kit expression in normal human hematopoiesis, CD34+ cells were incubated in the presence of sense, antisense, or missense oligonucleotides to c-kit, and subsequently cultured in the presence of either recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or recombinant human interleukin-3 (rhIL-3). Exposure of CD34+ cells to c-kit antisense oligonucleotides significantly inhibited colony-forming ability of cells cultured in the presence of rhIL-3, but had no effect on colony formation of cells cultured in rhGM-CSF. Together, these data suggest a possible role for c-kit in hematopoietic proliferation and differentiation that may be linked to some, but not all, stimulatory factors.
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PMID:c-kit expression by CD34+ bone marrow progenitors and inhibition of response to recombinant human interleukin-3 following exposure to c-kit antisense oligonucleotides. 172 Jun 96


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