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)

Ten cell lines recently established from paediatric patients with acute lymphoblastic leukaemia (ALL) were examined for expression of P145c-kit, the growth factor receptor encoded by the c-kit proto-oncogene, by immunofluorescence and flow cytometry using monoclonal antibody YB5.B8. Three of five T-ALL cell lines, but none of five B lineage ALL cell lines displayed significant binding of the antibody. The cell line with the highest level of binding was PER-423 (Kees et al, Leukemia Res 1993; 17: 51-59 which has the phenotype CD7+, CD56bright, CD2-, CD4-, CD5-, CD8-, CD16-, has rearranged T cell receptor beta-chain genes, expresses cytoplasmic CD3 and is strictly dependent on interleukin 2 (IL-2) for proliferation. Recombinant to act in synergy with IL-2 to promote proliferation of PER-423 cells. In five experiments, SLF increased the maximal amount of proliferation by 105 +/- 15%, and decreased the level of IL-2 required for a half-maximal response by 43 +/- 7%. The cells constitutively express the intermediate affinity IL-2 receptor (beta/gamma), but can be induced in the presence of phorbol ester to express the alpha chain (CD25, Tac) which confers high affinity binding of IL-2. In contrast, the alpha chain was not induced by SLF. The enhancement of proliferation of PER-423 cells by SLF could be prevented by inclusion in the assay of a blocking monoclonal antibody to P145c-kit. These experiments demonstrate that SLF/P145c-kit can provide a significant growth stimulus for ALL cells, and PER-423 cells may be a useful system for investigating the mechanism of synergy between SLF and IL-2.
Leukemia 1995 Jun
PMID:Synergistic action of interleukin-2 and Steel factor (SLF) on a human T lymphoblastoid cell line. 754 Oct 97

We have investigated the stimulative effects of mast cell growth factor (MGF) in primary acute myeloid leukemia (AML) in vitro. MGF stimulated DNA synthesis of purified leukemic blasts in eight out of 10 cases and colony formation in four cases in serum-free (SF) culture. MGF synergized with interleukin-3 (IL-3; four out of 10 cases), granulocyte-macrophage colony-stimulating factor (GM-CSF; three out of 10 cases), granulocyte colony-stimulating factor (G-CSF; six out of 10 cases), macrophage colony-stimulating factor (M-CSF; one out of 10 cases) and erythropoietin (EPO; one out of 10 cases) when added to culture in combination. Synergistic effects of MGF in combination with other CSFs were also seen in the colony assay. Antibodies against GM-CSF, M-CSF, G-CSF, and IL-6 did not inhibit the MGF response, suggesting that the stimulative effect of MGF was not mediated through autocrine release of those cytokines. Cell recovery data in liquid cultures that contained MGF, IL-3, or MGF + IL-3, indicated that both MGF and IL-3 augmented the maintenance of clonogenic cells as compared to nonsupplemented cultures, but the effect of the combination of IL-3 + MGF did not show synergy. In contrast, activation of DNA synthesis by MGF was abrogated in the presence of tumor necrosis factor (TNF; four out of 10 cases) and interleukin-4 (IL-4; two out of 10 cases). Fluorescence-activated cell sorting (FACS) analysis with anti c-kit antibodies revealed MGF receptor expression in eight out of nine cases, often in a subpopulation of the cells. Scatchard analysis of MGF receptors in two cases indicated the presence of 1460 and 41,500 (mean) binding sites, respectively, of high affinity (Kd 40-160 pmol/l). The MGF dose-response curve in the presence of IL-3 or GM-CSF resulted in a higher plateau of DNA synthesis, however no shift in the dose response was apparent. The respective reciprocal dose response relations to GM-CSF, IL-3, or G-CSF were similarly elevated when MGF was added. MGF did not alter IL-3 and GM-CSF receptor expression, nor did IL-3, GM-CSF, G-CSF, TNF, or IL-4 influence MGF binding to AML cells.(ABSTRACT TRUNCATED AT 400 WORDS)
Leukemia 1993 Mar
PMID:Effects of mast cell growth factor on acute myeloid leukemia cells in vitro: effects of combinations with other cytokines. 768 Apr 1

The KIT proto-oncogene encodes a tyrosine kinase receptor which plays a critical role in haemopoiesis. We have screened genomic DNA from bone marrow mononuclear cells of 46 patients with myelodysplasia (MDS) for mutations/deletions of exons 6, 13, 17, and 21 of the KIT gene (stem cell factor receptor) using polymerase chain reaction (PCR), polyacrylamide gel electrophoresis, and autoradiography to detect single-stranded conformational polymorphisms (SSCP). These exons include positions analogous to those mutated in the FMS gene (colony-stimulating factor-1 receptor) in myelodysplastic syndrome (MDS) and mutated/deleted in the Dominant White Spotting mouse (W locus) which results in macrocytic anaemia. Two different gel running conditions were used for each exon. Polymorphisms were identified only at 4 degrees C in exon 17 (three out of 44 MDS samples and two of 21 DNA samples from normal subjects), and in the non-coding region of exon 21 (five out of 34 MDS samples and seven out of 19 normals). Direct sequencing identified a G to A base change at nucleotide 3169 within exon 21, and a C to T change at position 2415 in exon 17. No conformational changes suggestive of mutations or deletions have been found to date, although we cannot rule out low frequency clonal abnormalities undetectable by our method, which has a sensitivity in our hands of approximately 5%. Polymorphisms occur frequently in the KIT gene. Together with this study, a total of five have been described.
Leukemia 1993 Nov
PMID:Two new polymorphisms but no mutations of the KIT gene in patients with myelodysplasia at positions corresponding to human FMS and murine W locus mutational hot spots. 769 8

The proto-oncogenes c-fms and c-kit belong to a family of growth factor receptors possessing protein kinase activity. It has been shown that transfection of a c-fms gene carrying a point mutation at codon 301, leads to a ligand-independent transformation of mouse NIH3T3 cells. In human acute myeloid leukemia (AML), point mutations at codon 301 of the c-fms gene have been observed implying an important role in the transformation process. The possibility of a point mutation of the c-kit proto-oncogene was investigated. We sequenced a segment of the c-kit proto-oncogene coding for a part of the extracellular domain. This segment was 40.7% homologous to the c-fms region encompassing codon 301. c-DNA was prepared from peripheral blood or bone marrow cells from 25 patients with AML, from four patients with myelodysplastic syndrome (MDS) and from three human myeloid cell lines. The region of interest was amplified with two rounds of polymerase chain reactions (PCR) with nested primers and directly sequenced. No point mutations were found in the investigated samples. Thus, point mutations in this segment of the c-kit gene do not seem to play an important role in the transformation process of human acute leukemia.
Leukemia 1994 Mar
PMID:Absence of point mutations in a functionally important part of the extracellular domain of the c-kit proto-oncogene in a series of patients with acute myeloid leukemia (AML). 812 54

We produced a monoclonal antibody MTK1 which recognized c-kit protein. Using MTK1, 31 leukemia cell lines and 76 leukemia blasts from pediatric patients were analyzed for expression of the c-kit receptor by flow cytometry. The c-kit receptor was detectable on four of four cell lines assigned to the megakaryo/erythromegakaryoblastic lineage and on one of seven cell lines of myeloid lineage. C-kit expression was not seen on any of 20 cell lines of erythroid and lymphoid lineages. Furthermore, c-kit was expressed on 16 of 24 nonlymphoid blasts without platelet surface antigens (67%) and on six of eight non-lymphoid blasts with platelet surface antigens (75%), but was not detectable on 44 lymphoid blasts from pediatric leukemia patients. In these cases CD34 was expressed on 26 of 32 myeloid blasts (81%) and on 27 of 44 lymphoid blasts (61%). The findings indicate a dominant expression of the c-kit receptor on established cell lines assigned to the megakaryo/erythromegakaryoblastic lineage, though a high percentage of leukemic myeloblasts also expressed the c-kit receptor on their surface.
Leukemia 1996 Jan
PMID:Cell surface c-kit receptors in human leukemia cell lines and pediatric leukemia: selective preservation of c-kit expression on megakaryoblastic cell lines during adaptation to in vitro culture. 855 13

The phenotypic and biologic properties of malignant cells in a case of aggressive mastocytosis with multi-organ involvement, circulating mast cell precursors and absence of skin infiltrates were analyzed. Circulating mast cell precursors were detected by immunostaining using antibodies against mast cell tryptase as well as by electron microscopy. These progenitors were tryptase+/chymase- (MCT) and accounted for 10 to 20% of nucleated mononuclear blood cells (MNC). A subset of them contained metachromatic granules. As assessed by combined toluidine blue/immunofluorescence staining, the granulated mast cell precursors were found to express CD9 (P24), CD33 (gp67) and CD44 (Pgp-1), but not basophil-related markers (CD11b (C3biR), CDw17 (lactosylceramide), CD123 (il-3R alpha))or monocyte-related antigens (CD14, CD15). Expression of the mast cell growth factor (MGF) receptor, c-kit(CD117), was also demonstrable, whereas the skin mast cell marker C5aR (CD88) could not be detected on mast cell precursors. The ligand of c-kit, recombinant human (rh) stem cell factor (SCF = MGF), induced histamine release from circulating mast cell progenitors, whereas rhC5a, a potent skin mast cell-/basophil-agonist, was ineffective over the dose-range (10(-9) to 10(-7(M)) tested. Analysis of mast cell antigens in malignant mastocytosis or mast cell leukemias may be helpful to establish a diagnosis and to determine the phenotype of the clone.
Leukemia 1996 Jan
PMID:A case of malignant mastocytosis with circulating mast cell precursors: biologic and phenotypic characterization of the malignant clone. 855 22

Characteristic of Philadelphia (Ph)+ chronic myelogenous leukemia (CML) is the presence of the chimeric BCR/ABL (p210) protein possessing elevated protein tyrosine kinase activity relative to the normal c-abl tyrosine kinase. Our previous studies demonstrated subtle differences in the growth, phenotypic and morphologic characteristics of the most primitive subpopulations of primary lin-Ph+ chronic phase CML blasts and comparable primary lin- normal blasts. Recently, in comparing proteins phosphorylated on tyrosine in these cell populations, we reported a prominent 62 kDa phosphotyrosyl (P-tyr) protein constitutively present in primary primitive lin- CML chronic phase blasts which was virtually undetectable in primary primitive lin- normal blasts. In the present studies, we demonstrate that this P-tyr p62 from primary primitive lin- chronic phase CML blasts co-immunoprecipitates with ras-GAP. Furthermore, in addition to the p210 protein, we show in whole cell lysates the presence of other clearly consistent but less prominent P-tyr proteins with molecular weights of approximately 155, 140, 110, 55 and 45 kDa as well as more minor P-tyr proteins of approximately 190, 85, 52, 42 and 39 kDa constitutively present in primary primitive lin- chronic phase CML blasts. In analyzing proteins tyrosine phosphorylated in primary primitive lin- normal blasts in response to various hematopoietic growth factors, we found a striking similarity in the phosphorylation of four major (approximately 140, 110, 62 and 56 kDa) and three minor (approximately 51, 45 and 42 kDa) P-tyr proteins after stimulation with c-kit ligand and the P-tyr proteins constitutively phosphorylated in primary primitive lin- chronic phase CML blasts. Other growth factors tested (ie GM-CSF, G-CSF, IL-3, FLT3 ligand and EPO) were much less active or stimulated phosphorylation of other proteins. It is provocative that at least seven proteins rapidly and transiently phosphorylated on tyrosine in the c-kit ligand signal transduction pathway in lin- normal blasts may be constitutive substrates for the p210 activated tyrosine kinase in comparable lin- chronic phase CML blasts. In addition, it is intriguing that some of the biological effects on hematopoietic progenitors attributed to the c-kit ligand may be similar to some of the observed biological consequences of the p210 protein, including survival and expansion of a more mature stem cell population, probably at the time of lineage commitment rather than at the level of the earliest self-renewing stem cell.
Leukemia 1996 Feb
PMID:c-kit ligand stimulates tyrosine phosphorylation of a similar pattern of phosphotyrosyl proteins in primary primitive normal hematopoietic progenitors that are constitutively phosphorylated in comparable primitive progenitors in chronic phase chronic myelogenous leukemia. 863 31

Cell surface levels of the receptor tyrosine kinase P145(c-kit), the product of the c-kit proto-oncogens, in a panel of 80 primary adult acute myeloid leukaemia (AML) specimens collected at presentation were quantitated by immunofluorescence and flow cytometry, and compared with levels on CD34+ bone marrow cells from normal donors. Receptor levels on AML blast cells were extremely variable and were similar to, or less than, those on normal stem and progenitor cells. In general P145(c-kit) expression was higher on cells of immature phenotype (FAB M1 and M2). c-kit mRNA was quantitated by ribonuclease protection assay (RPA) and was shown to be correlated with cell surface protein expression (r=0.76; P<0.001). This indicates that ligand-mediated receptor internalisation or other mechanisms of increased protein turnover are not responsible for variations in the level of P145(c-kit) in AML specimens. Quantitative Southern blotting was used to examine c-kit gene copy number in 25 of these specimens and was found to be normal in all but one. Thus we have found little evidence of over-expression of c-kit in adult AML. mRNA for the c-kit ligand, Steel Factor (SLF) was also quantitated by RPA in these specimens. While SLF message was detectable (limit of detection approximately 10(4) copies per 10 microgram total RNA; equivalent to 1 copy per 100 cells) in 19% of cases, these specimens in general contained low levels of c-kit mRNA. Thus, an autocrine cycle involving c-kit and SLF does not appear to be a common feature of AML.
Leukemia 1996 Feb
PMID:Increased expression of c-Kit or its ligand Steel Factor is not a common feature of adult acute myeloid leukaemia. 863 38

Ineffective erythropoiesis due to an impaired response to erythropoietin (EPO) is a prominent abnormality in myelodysplastic syndromes (MDS). The growth factor kit ligand (KL) may restore the in vitro erythroid colony-forming response to EPO in a subset of patients. The inability of MDS erythroid progenitors to react properly to EPO and/or KL has not been resolved. We have investigated erythropoietin receptor (EPO-R) and KL receptor (c-kit) expression in 15 cases of MDS by FACS analysis. The percentage of bone marrow cells expressing the EPO-R from patients with MDS were comparable to normal marrow. No apparent correlation was found between the number of MDS cells coexpressing the EPO-R and CD34 and impaired erythroid response. C-kit was expressed in most MDS patients, including those not responding to KL in EPO-induced cultures. In nine MDS cases the different splice variants of the EPO-R were analyzed. MDS cells, like normal marrow, expressed the full length EPO-R. These results show that impaired erythroid response in MDS cannot be explained by a quantitative lack of receptors for EPO or KL and that most likely suppression of erythroid response is caused by defective receptor signalling following ligand binding, representing a functional defect within the receptor itself or at a level downstream of the receptor.
Leukemia 1996 Mar
PMID:Erythropoiesis in myelodysplastic syndrome: expression of receptors for erythropoietin and kit ligand. 864 63

Recombinant human interferon-inducible protein-10 (rIP-10) has been recently identified, purified and shown to suppress the multiplication of normal marrow early hemopoietic progenitors. In the present study we investigated the effect of rIP-10 on different normal and acute myelogenous leukemia (AML) progenitor populations. We first studied hematologically normal bone marrow using the delta culture assay, in which marrow low-density cells were incubated in liquid culture with recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) for 1 week, to allow the differentiation of mature progenitors, and thereafter cultured in methylcellulose in the presence of rGM-CSF and recombinant erythropoietin (rEPO). In this assay rIP-10 significantly inhibited the proliferation of normal marrow hemopoietic progenitors in a dose-dependent fashion. However, when fresh normal marrow cells were cultured in methylcellulose without preincubation in liquid culture, rIP-10 did not affect the growth of colony-forming cells. In contrast, when recombinant c-kit ligand (rKL) was added to rGM-CSF and rEPO, an increment in colony numbers was observed that was eliminated by rIP-10. Similar experiments performed with low-density, non-adherent, T cell-depleted AML marrow cells, obtained from 12 untreated adult AML patients, revealed qualitatively similar results: rIP-10 inhibited the proliferation of AML progenitors in the AML delta assay but did not affect the growth of rGM-CSF-responsive AML colony-forming cells when plated in semisolid media in the presence of rGM-CSF. When rKL was added to rGM-CSF during plating in an effort to recruit additional AML progenitor populations, there was an increment in leukemic blast colony numbers that was eliminated by rIP-10. As observed with normal progenitors, the effect of rIP-10 on these AML progenitors was concentration-dependent, statistically significant and reversible with a rIP-10-neutralizing antiserum. To delineate the mechanism of action of rIP-10 we used the thymidine suicide assay and found that rIP-10 significantly reduced the fraction of leukemic progenitors synthesizing DNA. Our data suggest the rIP-10 inhibits the proliferation of (probably immature) AML progenitor populations by reducing the fraction of cells undergoing DNA synthesis. Additional studies are needed to further elucidate the mechanism of this inhibition and to determine the potential clinical benefits of rIP-10 in future therapies for AML.
Leukemia 1996 May
PMID:Human recombinant interferon-inducible protein-10 inhibits the proliferation of normal and acute myelogenous leukemia progenitors. 865 68


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