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

Thrombopoietin (Tpo), the ligand for c-mpl, has been shown to be the principal regulator of megakaryocytopoiesis and platelet production. The ability of Tpo to potently stimulate the growth of committed megakaryocyte (Mk) progenitor cells has been studied in detail. Murine fetal liver cells, highly enriched in primitive progenitors, have been shown to express c-mpl, but little is known about the ability of Tpo to stimulate the growth and differentiation of primitive multipotent bone marrow (BM) progenitor cells. Here, we show that Tpo alone and in combination with early acting cytokines can stimulate the growth and multilineage differentiation of Lin- Sca-1+ BM progenitor cells. In particular, Tpo potently synergized with the ligands for c-kit (stem cell factor [SCF]) and flt3 (FL) to stimulate an increase in the number and size of clones formed from Lin- Sca-1+ progenitors. When cells were plated at 1 cell per well, the synergistic effect of Tpo was observed both in fetal calf serum-supplemented and serum-depleted medium and was decreased if the addition of Tpo to cultures was delayed for as little as 24 hours, suggesting that Tpo is acting directly on the primitive progenitors. Tpo added to SCF + erythropoietin (Epo)-supplemented methylcellulose cultures potently enhanced the formation of multilineage colonies containing granulocytes, macrophages, erythrocytes, and Mks. SCF potently enhanced Tpo-stimulated production of high-ploidy Mks from Lin- Sca-1+ progenitors, whereas the increased growth response obtained when combining Tpo with FL did not translate into increased Mk production. The ability of Tpo and SCF to synergistically enhance the growth of Lin- Sca-1+ progenitors was predominantly observed in the more primitive rhodamine 123(lo) fraction. Tpo also enhanced growth of Lin- Sca-1+ progenitors when combined with interleukin-3 (IL-3) and IL-11 but not with IL-12, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, or Epo. Epo, which has high homology to Tpo, was unable to stimulate the growth of Lin- Sca-1+ progenitors alone or in combination with SCF or FL, suggesting that c-mpl is expressed on more primitive stages of progenitors than the Epo receptor. Thus, the present studies show the potent ability of Tpo to enhance the growth of primitive multipotent murine BM progenitors in combination with multiple early acting cytokines and documents its unique ability to synergize with SCF to enhance Mk production from such progenitors.
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PMID:Thrombopoietin, but not erythropoietin, directly stimulates multilineage growth of primitive murine bone marrow progenitor cells in synergy with early acting cytokines: distinct interactions with the ligands for c-kit and FLT3. 897 40

The effects of human recombinant megakaryocyte growth and development factor (MGDF) (also known as thrombopoietin (TPO)), alone or in combination with other growth factors, on the proliferation and on the clonal growth of clonogenic progenitors from 24 acute myeloblastic leukemia (AML) patients were evaluated. A significant proliferative response to MGDF alone (proliferation index > 1.5) was observed in nine of 23 cases; the responding cases belonged to all FAB subtypes. However, the greatest response (proliferation index > 7) was found in one M6 and in one M7 case. MGDF also enhanced interleukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), c-kit ligand (KL) and FLT3 ligand (FL) stimulated blast cell proliferation. MGDF as a single factor induced or significantly enhanced colony formation by clonogenic precursor cells in 12 of 14 AML cases. MGDF strongly increased KL-induced leukemic colony growth in seven cases, whereas it only moderately enhanced IL-3- or GM-CSF-induced colony growth. The analysis of tyrosine phosphorylated protein(s) upon MGDF stimulation in fresh AML cells was also performed. The results demonstrated a band of approximately 90 kDa phosphorylated protein(s) upon MGDF stimulation in AML responsive cases, but not in unresponsive ones. Taken together the present findings suggest that, in a consistent proportion of AML cases, MGDF stimulates blast cell growth and induces tyrosine protein phosphorylation.
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PMID:Megakaryocyte growth and development factor (MGDF)-induced acute leukemia cell proliferation and clonal growth is associated with functional c-mpl. 909 94

The authors have recently shown that direct contact with primary porcine microvascular endothelial cell monolayers (PMVECs) in combination with haematopoietic growth factors enhances the expansion of primitive human haematopoietic CD34+ bone marrow progenitor cells. It is now demonstrated that serum-free conditioned medium (PMVEC CM, concentrated 70x for proteins >30 kDa) from untreated PMVECs contains haematopoietic growth factor activity that enhances the in vitro proliferation, haematopoietic cell production, and colony cell formation of primitive human haematopoietic progenitor cells. In combination with exogeneously added human growth factors such as interleukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF) and EPO, PMVEC CM enhances the proliferation and colony growth of human haematopoietic CD34+ cells. In contrast, PMVEC CM has no significant synergistic activity on either stem cell factor (SCF) or flt3-ligand-induced CD34+ cell proliferation, cell production or colony formation. Blocking mAbs against the c-kit receptor have no effect on PMVEC CM-induced CD34+ cell proliferation at titres that completely suppress SCF-induced proliferation. Moreover, it is shown that this haematopoietic growth factor supports the proliferation and colony formation of murine, non-human primate, and porcine marrow progenitor cells without any apparent species-specific restrictions in its activity. These finding suggest that PMVEC CM contains a novel early haematopoietic activity.
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PMID:Conditioned medium from primary porcine endothelial cells alone promotes the growth of primitive human haematopoietic progenitor cells with a high replating potential: evidence for a novel early haematopoietic activity. 911 35

Mast cells (MC) are proinflammatory immune cells residing in various organs. Tissue-specific heterogeneity of MC has been described. The aim of this study was to establish the phenotype and functional profile of human tonsillar mast cells (ToMC) and to compare ToMC with lung-, skin-, and uterus MC. Tonsillar tissue was obtained from 23 patients suffering from hyperplastic tonsils and dispersed by enzymatic digestion. With the use of a combined toluidine blue/immunofluorescence staining technique, isolated ToMC were found to react with monoclonal antibodies (mAb) to immunoglobulin E, CD9, CD43, CD44, CD46, CD54, CD55, and CD59, as well as mAb to stem cell factor (SCF) receptor (CD117/c-kit). ToMC were not recognized by mAb to other cytokine receptors or mAb to CD3, CD11b, CD14, CDw17, the skin MC marker CD88 (C5aR) or CD89 (Fc alphaR). Activation of ToMC by recombinant human (rh) SCF or anti-IgE resulted in histamine secretion, whereas no effects were seen with rhC5a, rh granulocyte-macrophage colony-stimulating factor, or rh interleukin-1 through -10. In summary, ToMC exhibit functional and phenotypic properties similar to lung- or uterus MC. Unlike skin MC, ToMC lack C5aR and are unresponsive to rhC5a.
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PMID:Immunophenotypic and functional characterization of human tonsillar mast cells. 912 8

A coculture system of a murine erythroblastic leukemia cell line (ELM-D) with its supportive stromal cell line (MS-5) was established. Long-term growth of ELM-D cells is strictly stroma cell dependent. Interaction between stem cell factor (SCF) and its receptor, c-kit, was demonstrated to be important for stroma cell-dependent growth by anti c-kit neutralizing monoclonal antibody (mAb) inhibition experiments. Significantly, soluble growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3) or SCF of MS-5 stromal cells (MS-5 CM) could replace the requirement of stroma cells for a considerable period. However, ELM-D cells maintained in these growth factors underwent clonal extinction after 3-6 weeks unless contact with stroma was re-established. Furthermore, IL-3 or GM-CSF acted in a dominant manner in inducing cell death in the presence of stroma cells. Cells showing clonal extinction undergo programmed cell death and do not differentiate. These altered growth properties of ELM-D cells exposed to soluble growth factors or to stroma cells appear to be analogous to those described for T or B cells primed by antigen presenting cells and then grown in growth factors.
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PMID:The role of soluble growth factors in inducing transient growth and clonal extinction of stroma cell dependent erythroblastic leukemia cells. 932 97

Selected CD34+ cells from mobilized apheresis products were cultured in serum-free or serum-containing media supplemented with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and stem cell factor (SCF; c-kit ligand). We examined the emergence of a CD15+CD11b- population, which appeared morphologically to be promyelocytes. This CD15+CD11b- population can be further expanded in culture into morphologically mature granulocytes. In an attempt to characterize this culture-derived CD15+CD11b- promyelocytic population, single cells were clone sorted into wells of a Terasaki plate containing various growth factors. We compared the growth factor requirements and kinetics of this apheresis culture-derived CD15+CD11b- population to the CD15+CD11b- population from fresh bone marrow samples. Our studies indicate that the CD15+CD11b- promyelocytic population from bone marrow and blood are equivalent in their ability to proliferate and in their requirements for growth factors. The CD15+CD11b- population in vitro shows a high proliferative capacity when compared with the other CD15/CD11b populations (CD15-CD11b-, CD15+CD11b+, CD15-CD11b+). Thus, we can manipulate CD34+ cells in vitro to proliferate and differentiate toward a mature neutrophil lineage. The CD15+CD11b- promyelocytic population derived from this culture may represent the most effective cultured cell population for therapeutic reduction of neutropenia in vivo based on both its stage of differentiation and its proliferative potential.
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PMID:Characterization of a culture-derived CD15+CD11b- promyelocytic population from CD34+ peripheral blood cells. 933 18

The cDNAs encoding wild type (WT) human receptor tyrosine kinase c-Kit and a constitutively activated mutant, V816Kit, were introduced into granulocyte-macrophage colony-stimulating factor (GM-CSF )-dependent early murine hemopoietic cells, which had been transformed with activated Myb. WTKit cells were able to grow in the presence of the human ligand for Kit, stem cell factor (SCF ), but displayed reduced growth and clonogenic potential in either SCF or GM-CSF compared with the parental cells in GM-CSF. In contrast, V816Kit cells grew without factor at a higher rate than the parental cells in GM-CSF and displayed increased clonogenicity. Dissection of the growth characteristics in liquid culture showed that in the presence of appropriate factors, the different populations had similar proliferation rates, but that V816Kit profoundly increased cell survival compared with WTKit or parental cells. This suggests that the signals transduced by WTKit activated with SCF, and by V816Kit, were not identical. Also, WTKit and V816Kit-expressing cells both varied from the early myeloid progenitor phenotype of the parental cells and gave rise to a small number of large to giant adherent cells that expressed macrophage (alpha-naphthyl acetate) esterase and neutrophil (naphtol-AS-D-chloroacetate) esterase, were highly phagocytic and phenotypically resembled histiocytes. Thus, WTKit activated by SCF and V816Kit were able to induce differentiation in a proportion of Myb-transformed myeloid cells. The factor independent V816Kit cells, unlike the parental and WTKit expressing cells, were shown to produce tumors of highly mitotic, invasive cells at various stages of differentiation in syngeneic mice. These results imply that constitutively activated Kit can promote the development of differentiated myeloid tumors and that its oncogenic effects are not restricted to lineages (mast cell and B-cell acute lymphoblastic leukemia), which have been reported previously. Furthermore, the mixed populations of cells in culture and in the tumors phenotypically resembled the leukemic cells from patients with monocytic leukemia with histiocytic differentiation (acute myeloid leukemia-M5c), a newly proposed subtype of myeloid leukemia.
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PMID:Expression of constitutively activated human c-Kit in Myb transformed early myeloid cells leads to factor independence, histiocytic differentiation, and tumorigenicity. 937 65

Here we review our recent data addressing the role of recombinant human (rh) interleukin 9 (IL-9) in acute myeloblastic leukemia (AML). We first evaluated the proliferative response of 3 leukemic cell lines and 32 primary samples from AML patients to IL-9 alone and combined with rh-IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF) and stem cell factor (SCF, c-kit ligand). The colony forming ability of leukemic cells was assessed by a clonogenic assay in methylcellulose, whereas the cell cycle characteristics of the same samples were determined by the acridine-orange (AO) flow cytometric technique and the bromodeoxyuridine (BRDU) incorporation assay. In addition, the terminal deoxynucleotidyl transferase Assay (TDTA) and standard analysis of DNA cleavage by gel electrophoresis were used to evaluate induction or prevention of apoptosis by IL-9. IL-9, used as a single cytokine, at various concentrations stimulated the colony formation of the 3 myeloid cell lines under serum-containing and serum-free conditions and this effect was completely abrogated by anti-IL-9 monoclonal antibodies (MoAbs). When tested on fresh AML samples, optimal concentrations of IL-9 resulted in the increase of the blast colony formation in all the cases studied and was the most effective CSF for promoting leukemic cell growth among those tested in this study including SCF, IL-3, and GM-CSF. The addition of SCF to IL-9 demonstrated an additive or synergistic effect of the 2 cytokines in 5 out of 8 AML cases tested for their CFU-L growth (187 +/- 79 colonies in comparison with 107 +/- 32 CFU-L; p = 0.05). Positive interaction was also observed when IL-9 was combined with IL-3 and GM-CSF. Studies of cell cycle distribution of AML samples demonstrated that IL-9 alone significantly augmented the number of leukemic cells in S-phase in the majority of the cases evaluated. IL-9 and SCF in combination resulted in a remarkable decrease of the G0 cell fraction (38.2 +/- 24% compared to 58.6 +/- 22% of control cultures; p < 0.05) and induced an increase of G1 and S-phase cells. Conversely, neither IL-9 alone nor the combination of IL-9 and SCF had any effect on induction or prevention of apoptosis of leukemic cells. Furthermore, in this study, reverse transcriptase-polymerase chain reaction amplification (RT-PCR) did not show the constitutive expression of IL-9 mRNA in the cell lines and the AML samples studied at diagnosis. In summary, IL-9 may play a role in the development of acute myeloid leukemia by stimulating the proliferation of leukemic cells perhaps through a paracrine growth loop.
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PMID:Interleukin-9 in human myeloid leukemia cells. 938 63

Patients with head and neck squamous cell carcinoma (HNSCC) have profound immune deficiencies. In 65% of these patients, there is an increased intra-tumoral presence of immune-suppressive CD34+ progenitor cells. The goal of the present study was to determine whether CD34+ cell levels were also increased in the peripheral blood of HNSCC patients and if these immune-suppressive cells could be differentiated into dendritic cells. Our results showed that CD34+ cell levels are increased in the peripheral blood of HNSCC patients. To assess if these CD34+ cells could differentiate into dendritic cells, they were isolated from the blood of HNSCC patients and cultured for 12 days with various cytokine combinations. Culturing CD34+ cells with stem cell factor (c-kit ligand) plus granulocyte-macrophage colony-stimulating factor resulted in the appearance of a significant proportion of cells expressing phenotypic markers characteristic of dendritic cells. Also, including tumor necrosis factor-alpha yielded a significant proportion of cells resembling the bipotential precursor cells for dendritic cells and monocytes (CD14+CD1a+), in addition to the dendritic-like cells. When the differentiation inducer 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] was added along with the cytokine combinations, the yield of cells having characteristics of dendritic cells was further increased. Cells that were derived from CD34+ cell cultures containing 1,25(OH)2D3 had a more potent capacity to present the recall antigen tetanus toxoid to autologous peripheral blood leukocytes and to stimulate a mixed leukocyte response compared to cultures to which 1,25(OH)2D3 had not been added. Our results show that CD34+ cells, whose frequency is increased in HNSCC patients, can be differentiated into cells that phenotypically and functionally resemble dendritic cells and that 1,25(OH)2D3 accentuates this differentiation.
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PMID:Increased presence of CD34+ cells in the peripheral blood of head and neck cancer patients and their differentiation into dendritic cells. 939 43

In normal hematopoiesis, stem cell factor (SCF) stimulates survival, proliferation and differentiation of hematopoietic progenitors. Although SCF acts synergistically with a variety of cytokines, the mechanism of growth factor-cooperation remains to be determined. To analyze the synergism between SCF and granulocyte-macrophage colony-stimulating factor (GM-CSF), we established a new megakaryoblastic cell line, HML-2, by culture in the presence of both SCF and GM-CSF. While SCF alone or GM-CSF alone supported modest cell growth, SCF and GM-CSF together induced substantial growth of this cell line. SCF alone tyrosine-phosphorylated several bands including the 145 kDa subunit of c-kit. GM-CSF alone did not cause the tyrosine phosphorylation of the 145 kDa subunit, but markedly up-regulated the expression of the 145 kDa subunit of c-kit. The combination of SCF and GM-CSF resulted in a synergistic increase in tyrosine phosphorylation of the 145 kDa subunit of c-kit. Several proliferation inhibitors which removed the two-factor interaction on the growth of the HML-2 cells down-regulated the 145 kDa subunit of c-kit. Thus, a synergistic increase in tyrosine phosphorylation of the 145 kDa subunit of c-kit may be one possible mechanism underlying the cooperation of SCF and GM-CSF on the HML-2 cell growth.
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PMID:Analysis of synergism between stem cell factor and granulocyte-macrophage colony-stimulating factor on human megakaryoblastic cells: an increase in tyrosine phosphorylation of 145 kDa subunit of c-kit in two-factor combination. 944 44


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