Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10721 (c-kit)
 6,575 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have evaluated the immunophenotype, functional activity and clonogenic potential of CD34+ cells from peripheral blood (PB) of normal donors before and after 4 and 6 days of G-CSF administration. The percentage and absolute number of CD34+ cells significantly increased at days 4 and 6 of G-CSF administration, compared to the steady-state level (P < 0.0001). Two-colour fluorescence analysis showed, at days 4 and 6, a lower proportion of CD34+/c-kit+ compared to the steady-state level (P < 0.0001), but a similar expression of CD13, CD33, CD38, HLA-DR and Thy-1 antigens on CD34+ cells. The expression of adhesion molecules on CD34+ cells revealed a significant reduction of CD11a (P = 0.009), CD18, CD49d and CD62L (P < 0.0001) at days 4 and 6, compared to the baseline level. Three-colour staining showed a reduction of the more immature compartment (34+/DR-/13-) and an increase of the more differentiated compartment (34+/DR+/13+). Downregulation of VLA-4 during mobilisation was seen almost exclusively on more committed cells (34+/13+); downregulation of CD62L, on the contrary, was observed on both early progenitors (34+/13-) and more committed cells (34+/13+). The expression of 34+/VLA-4+ decreased on both c-kit+ and c-kit- cells, while the expression of 34+/62L+ decreased on the c-kit+ cells only. In vivo administration of G-CSF reduced the adherence capacity of CD34+ cells to normal BM stroma; in vitro incubation with SCF or IL-3 enhanced the expression of CD49d on CD34+ cells, while GM-CSF reduced the expression of CD62L. SCF was the only cytokine able to induce a significant increase of CD34+ cell adherence to preformed stroma. Pre-incubation with the blocking beta2 integrin monoclonal antibody caused a reduction of CD34+ cell adherence. In conclusion, the decrease of CD49d expression on mobilized CD34+ cells correlates with a poor adhesion to BM stroma; CD34+ cells incubated in vitro with SCF showed, conversely, a higher expression of CD49d and a greater adherence capacity on normal preformed stroma.
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PMID:Modulation of VLA-4 and L-selectin expression on normal CD34+ cells during mobilization with G-CSF. 1003 43

Melanoma cells in culture express a variety of growth factors and cytokines and some of their autocrine and paracrine roles have been investigated. However, less information is available on the potential dynamic changes in expression of these molecules on cells during melanoma development and progression in situ. Using immunohistochemistry, we tested 40 nevi and primary and metastatic melanoma lesions for the expression of 10 growth factors and cytokines and the respective receptors representing 10 cell surface molecules. Nevi and thin (< 1 mm) primary melanomas showed little expression of ligands except weak reactivity of tumor necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), interleukin-8 (IL-8) and reactivity of TGF-betaR and c-kit. Marked up-regulation of growth factors, cytokines and receptor expression was observed in thick (> 1 mm) primary melanomas, which were stained with polyclonal or monoclonal antibodies (MAbs) for IL-1alpha, IL-1beta, IL-6, IL-8, TNF-alpha, TGF-beta, granulocyte-macrophage colony-stimulating factor (GMCSF) and stem cell factor (SCF), but not IL-2. Metastases showed similar expression patterns except that SCF was absent. Co-expression of ligand and receptor was observed for TGF-beta, GM-CSF and IL-6, suggesting an autocrine role for these ligands. TNF-alpha appears to be a marker of benign lesions; IL-6 and IL-8 expression is associated with biologically early malignancy; TGF-beta, GM-CSF and IL-1alpha are highly expressed in biologically late lesions; and TNF-beta is an apparent marker of metastatic dissemination. Our results indicate that melanoma cells utilize cascades of growth factors and cytokines for their progression.
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PMID:Immunohistochemical evidence of cytokine networks during progression of human melanocytic lesions. 1009 49

Thrombopoietin (TPO) is established as a powerful stimulant of megakaryocyte differentiation and platelet production both in vivo and in vitro. In preparation for future transplantation of ex vivo expanded CD34+ hematopoietic progenitor cells (HPCs), we have examined the in vitro effect of TPO on cultures of HPC when combined with other early-acting hematopoietic growth factors (GFs) in an attempt to decrease post-transplant thrombocytopenia and accelerate engraftment. By adding TPO to all possible combinations of GM-CSF, IL-3, and c-kit ligand (CKL) in a suspension culture system, we found a significant increase in both relative and absolute numbers of cells in cultures containing TPO of the megakaryocytic lineage and CD34+ cells after 14 days of culture. The most efficient GF combinations for expansion of cell populations of the megakaryocytic lineage and HPCs were TPO, GM-CSF, and CKL, which increased the number of cells of the megakaryocytic lineage 78 fold and the number of CD34+ cells 1.8 fold. The number of CD34+ cells decreased in the cultures containing GM-CSF and CKL with no TPO present, and the number of cells of the megakaryocytic lineage was increased merely 27 fold. Based on our findings, we suggest adding cells from HPCs expanded in cultures containing TPO, GM-CSF, and CKL to unexpanded stem cells for stem cell transplantation.
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PMID:Thrombopoietin combined with early-acting growth factors effectively expands human hematopoietic progenitor cells in vitro. 1021 99

The regulation of cell differentiation and cell death in crucial to the generation of hematopoietic cells both in vitro and in vivo. The biologic role of stem cell factor (SCF) in hematopoietic cell development is not well known. We monitored the survival, proliferation and differentiation of mouse hematopoietic cells in culture in the presence of SCF. Examination of colony formation, MTT and thymidine killing of mouse bone marrow indicated that SCF is mainly a survival factor. Our results show that SCF maintains cells in a "undifferentiated" state. Committed granulocytic and monocytic progenitors (CFU-GM) survive for seven days in the presence of SCF alone, under conditions where no maturing granulocytic monocytic cells could be recovered. On transfer to GM-CSF containing cultures, these cells proliferate and differentiate terminally. Together, our data indicate that SCF induces survival in hematopoietic progenitors. Furthermore, SCF favors the survival of granulocytic progenitors over that of monocytic progenitors. In the absence of later acting factors such as GM-CSF, cells that progress beyond the CFU-GM stage lose c-kit expression and die by default. Hence, lack of cell expansion in the presence of SCF by itself is due to constant cell proliferation and survival, which is counterbalanced by cell death. In contrast, the presence of both SCF and GM-CSF allows for the continuous survival and expansion of hematopoietic progenitor cells in culture, as well as favoring their terminal differentiation along granulocytic and monocytic pathways. Furthermore, GM-CSF induces colonies of macrophages that produce G-CSF and IL-6, two molecules involved in granulopoiesis, and these in turn stimulate granulocyte colony formation. Finally, our data suggest that survival signals by SCF are crucial during the differentiative process of granulocytes, giving strength to deterministic model.
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PMID:[Stem cell factor (SCF) supports granulocyte progenitor survival in mouse bone marrow cultures]. 1041 May 90

The biological effects of flt3-L, and the expression of its tyrosine kinase receptor (flt3, CD135) were investigated on the immature subsets of human circulating peripheral blood progenitors obtained from cancer patients or normal volunteer donors, after mobilization with rhG-CSF or chemotherapy. flt3 was expressed at low levels, and its expression increased concomitantly with expression of CD38 within the CD34+ cell population. Despite this low-level expression, flt3-L exerted synergistic effects with a combination of c-kit ligand, IL-3, IL-6, GM-CSF and G-CSF, mainly to induce proliferation of CD34+/CD38- cells. In addition, flt3-L increased the detection of HPP-CFC, both immediately after cell selection, and after 7 and 14 d of cultures. We conclude that flt3-L is active on circulating early mobilized haemopoietic progenitors, despite the low- level expression of its receptor.
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PMID:Early progenitor cells from human mobilized peripheral blood express low levels of the flt3 receptor, but exhibit various biological responses to flt3-L. 1046 May 91

Cell lines RPMI 8226, JJN3, U266 B1, NCI-H929 (all EBV-) and ARH77 and HS-Sultan (both EBV+) have been extensively characterized in this study. EBV- lines expressed the phenotype (CD138-, CD19+, CD20+) whereas EBV+ were (CD138+, CD19-, CD20-). CD56 expression was restricted to EBV- cell lines, with the exception of U266 B1, whereas PCA-1 was strongly expressed on five of the six cell lines. Only EBV+ cell lines bound peanut-agglutinin (PNA). However, all cell lines bound the lectin Jacalin that binds the same receptor as PNA, irrespective of the receptors sialylation status. By RT-PCR and direct sequencing of their IgH V/D/J domains, ARH77 was demonstrated to use the germline sequence VH4-34/dm1/JH6b, whereas no arrangement was demonstrated for RPMI 8226, suggesting IgH gene deletion or mutation. HLA class I and II antigens were detected using HLA typing on all cell lines warranting their use as suitable targets for HLA-restricted cytotoxic T cells. By sensitive RT-PCR, mRNA for IL-6, IL-6R and TNFbeta was found expressed in all cell lines. IL-1 mRNA expression was predominantly associated with the EBV+ phenotype. Although mRNA for IL-3 and GM-CSF was never detected, transcripts for c-kit ligand and, more commonly, its receptor were. Likewise GM-CSF, M-CSF and erythropoietin mRNA transcripts were detected in the majority of cell lines.
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PMID:Phenotypic and molecular analysis of six human cell lines derived from patients with plasma cell dyscrasia. 1191 67

Dendritic cells (DCs) are essential for the presentation of antigens in the primary immune response. To examine the generation of DCs from hemopoietic stem cells in the bone marrow (BM), lineage-negative (Lin-)/CD71- bone marrow cells (BMCs) from C57BL/6 mice were separated into major histocompatibility complex (MHC) class Ihigh/ c-kit(low) and MHC class Ihigh/c-kit(low)(phenotypically c-kit-negative, but c-kit message only detected by reverse transcriptase-polymerase chain reaction) populations. A large number of cells with the morphological, phenotypical, and functional characteristics of DCs was generated from both c-kit(low) and c-kit(low) populations when cultured with a combination of cytokines (GM-CSF, tumor necrosis factor-a [TNF-a], interleukin 7 [IL-7], IL-3, stem cell factor [SCF], and flt3 ligand); the cytokine combination studies revealed that SCF and IL-3 in addition to GM-CSF and TNF-a are essential for DCs to be generated from these primitive populations. To our surprise most (>80%) generated cells expressed high levels of DC surface markers such as DEC205 and MHC class II, and they were potent stimulators in the primary allogeneic T cell activation. The development of DCs from c-kit(<low) cells was slower than that from c-kit(low) cells. These results indicate that c-kit(<low) cells are more primitive than c-kit(low) cells, although both c-kit*(low) cells and c-kit(<low) cells can differentiate into DCs. It should be noted that the combination of these cytokines selectively induces DCs from both c-kit(<low) and c-kit(low) cells in vitro, suggesting that the ex vivo expansion of DCs using these primitive cells would be applicable to immunotherapy.
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PMID:Development of mouse dendritic cells from lineage-negative c-kit(low) pluripotent hemopoietic stem cells in vitro. 1066 72

Bone marrow lineage-negative (Lin(-)) c-Kit(+) Sca-1(+) hematopoietic cells from human GM-CSF receptor gene transgenic mice were cultured on established bone marrow stromal cell (TBR59) layers and on semisolid medium. In the semisolid assay, an increasing number of larger colonies were observed in the presence of hGM-CSF. By coculture with the stromal cells, cobblestones containing myeloid and lymphoid lineages of cells were formed from the stem cell enriched fraction, and addition of hGM-CSF strongly stimulated formation of the cobblestones containing both lineages. Repeating passages of the cobblestones on TBR59 stromal cells in the presence of hGM-CSF gradually decreased cobblestone formation and inversely increased macrophages and granulocytes, while mast cells were generated when the cells derived from the semisolid assay were cultured in a liquid medium containing hGM-CSF. These results consistently suggest that cytokines such as GM-CSF may costimulate the immature hematopoietic cells at their stroma-dependent phase before lineage commitment, and after commitment that occurs by an intrinsic program of the cells, they may stimulate maintenance and maturation of progenitor cells.
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PMID:Effect of human granulocyte-macrophage colony stimulating factor (hGM-CSF) on lymphoid and myeloid differentiation of sorted hematopoietic stem cells from hGM-CSF receptor gene transgenic mice. 1073 50

The appearance of blasts in acute myeloid leukemia (AML) reflects a shift from cellular processes inducing maturation and cell death to those favouring survival and accumulation. We have monitored changes in the growth factor signalling molecule MAPKinase, in the cytoprotective protein Bcl-2 and in the cell death protein Bax, during maturation of proliferating and non-proliferating AML blasts in vitro. Eighteen AML samples were cultured for 7 d in serum-free medium with or without a supplement of recombinant cytokines comprising c-kit ligand, IL3 and GMCSF. Maturation of AML blasts, as assessed by morphology on Romanowsky-stained slides of 7/18 samples and by changes in surface CD markers on all 18 leukemias, occurred in both the absence and presence of cytokines. Cell numbers decreased to a mean of 71% after 7 d of cytokine-free culture, but increased to 210% in cytokine-supplemented cultures. The proportion of CD15-positive cells, assessed by flow cytometry, increased over 7 d in 17/18 samples, from a mean of 22% to 68% in cytokine-free cultures and to 72% in cytokine-supplemented cultures (p = < 0.0001 for both). By immunofluorescence/flow cytometry, there was no significant change in Bcl-2 over 7 d of culture, while Bax increased, particularly in cytokine-free cultures (2.2-fold), which led to a significant decrease in the Bcl-2/Bax ratio. Immunoblotting demonstrated that ERK was briefly phosphorylated after seeding AML blasts into culture. PD98059, an inhibitor of MAPKinase kinase (MEK) which activates MAPKinase, inhibited this transient ERK phosphorylation but was unable to block maturation as measured by acquisition of CD15 in samples from 12 patients with low starting numbers of CD15-positive cells. PD98059, however, reduced cell numbers in 7-d liquid culture and, in cytokine-supplemented cultures, this was associated with a 1.3-fold increase in Bcl-2 (p = 0.012) and a 1.4-fold increase in Bax (p = 0.02). Overall, these data demonstrate that most leukemic populations can partially differentiate in vitro without the need for cytokines or inducers. The MAPKinase pathway is not required for this maturation, but it does maintain cell viability in the absence or presence of cytokines. A rise in Bcl-2 may not protect AML blasts in the face of elevated Bax.
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PMID:The MEK inhibitor, PD98059, reduces survival but does not block acute myeloid leukemia blast maturation in vitro. 1077 91

To understand regulation of myeloid development, it is necessary to obtain the myeloid progenitor cell lines with self-renewal and differentiation capacities. Because prolonged hematopoiesis occurs with the production of myeloid cells at all stages of differentiation in the Dexter-type long-term bone marrow cultures, we tried to obtain stroma-dependent myeloid progenitor cells starting from the long-term bone marrow culture. Murine cobblestone areas generated in long-term bone marrow cultures were serially passaged every 10 days. After 4 months, the resultant hematopoietic cells, designated as DFC, were passaged on a monolayer of established spleen stromal cell line, MSS62. After 10-12 passages of DFC cells on MSS62, several clones were obtained by colony formation on MSS62 cell layer. Among these clones, DFC-a cells could be maintained for a long period by coculturing with the established stromal cell line, MSS62.DFC-a cells proliferated by forming cobblestones and contained blast cells, granulocytes, and macrophages. Cell sorting and coculture experiments indicated that the blast type cells exhibiting c-Kit(+) Gr-1(-) Mac-1(-), stroma-dependently self-renewed, and spontaneously differentiated toward granulocytes (c-Kit(+) Gr-1(+) Mac-1(+)) and macrophages (c-Kit(low/+) Gr-1(-) Mac-1(high)). Although most of DFC-a cells expressed c-Kit, SCF-c-Kit interaction was not always necessary for their growth. In the presence of stromal cells, growth and differentiation of DFC-a cells were stimulated by GM-CSF or IL-3. Without stromal cells, DFC-a was transiently expanded by GM-CSF or IL-3 but could not be maintained constantly by these cytokines. The present study demonstrated that DFC-a is a novel bipotent myeloid progenitor cell clone as a simple model system of stroma-dependent myeloid development. It may reflect distinct properties for the earliest myeloid progenitor cells in vivo. It is of interest to know what signals are provided by MSS62 stromal cells to maintain the myeloid progenitor cells.
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PMID:Self-renewal and differentiation of a novel bipotent myeloid progenitor clone in the stroma-dependent culture. 1088 Jul 51


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