Activating mutations of the c-kit proto-oncogene in a human mast cell leukemia cell line.

The c-kit proto-oncogene encodes a receptor tyrosine kinase that is known to play a crucial role in mast cell growth and differentiation. In a human mast cell leukemia cell line (HMC-1), KitR was found to be constitutively phosphorylated on tyrosine, activated and associated with phosphatidylinositol 3-kinase (P13K) in the absence of autocrine production of SCF. Sequencing of c-kit cDNA revealed that c-kit genes of HMC-1 cells were composed of a normal, wild-type allele and a mutant allele with two point mutations in codon 560 and codon 816, resulting in intracellular amino acid substitutions of Gly-560 for Val and Val-816 for Asp, respectively.

Protection against programmed electrical stimulation-induced ventricular tachycardia and sudden cardiac death by NE-10064, a class III antiarrhythmic drug.

The electrophysiologic and antifibrillatory properties of NE-10064 were studied in vivo in a conscious canine model of sudden cardiac death. Purpose bred male mongrel dogs weighing 14.5-21.

Identification of mutations in the coding sequence of the proto-oncogene c-kit in a human mast cell leukemia cell line causing ligand-independent activation of c-kit product.

The c-kit proto-oncogene encodes a receptor tyrosine kinase. Binding of c-kit ligand, stem cell factor (SCF) to c-kit receptor (c-kitR) is known to activate c-kitR tyrosine kinase, thereby leading to autophosphorylation of c-kitR on tyrosine and to association of c-kitR with substrates such as phosphatidylinositol 3-kinase (PI3K). In a human mast cell leukemia cell line HMC-1, c-kitR was found to be constitutively phosphorylated on tyrosine, activated, and associated with PI3K without the addition of SCF.

Phorbol ester 12-O-tetradecanoylphorbol-13-acetate down-regulates expression of the c-kit proto-oncogene product.

Modulation of expression of the c-kit proto-oncogene product, the receptor for the recently identified stem cell factor, was studied on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated cultures of CD34+ normal bone marrow progenitor cells, blast cells from patients with primary acute myelogenous leukemia, cells from the leukemia cell lines HEL and MO7E, as well as cultured HMC-1 mast cells. Expression of c-kit was assessed on both RNA and protein level employing standard Northern blotting, reverse transcription, and polymerase chain reaction-based Southern blotting, as well as cell surface labeling with anti-c-kit mAb YB5.B8.

The circulation in diabetes, from HL523 to the NO era.

In 1955, F R Barany, a Swedish research physician interested in diabetes, summarised his dissertation (Acta Med Scand 1955; suppl 1304: 127) with the words "The ultimate cause of the various abnormal vascular reactions in diabetes might be assumed to be the cause of diabetic neuropathy in which autonomic pathways are the first to be destroyed...

Tumor necrosis factor alpha and interleukin-1 beta mRNA expression in HMC-1 cells: differential regulation of gene product expression by recombinant interleukin-4.

Cytokine-activation pathways in mast cells are supposed to play a significant role in host defense mechanisms and allergic reactions. Interleukin-4 (IL-4) is a well-characterized regulator of growth and function of mast cells. The human mast cell line HMC-1 was established from a patient suffering from mast cell leukemia and was shown to expose IL-4 binding sites.

Mast cells, neutrophils, and eosinophils in prurigo nodularis.

Background And Design: Prurigo nodularis is a disease of unknown cause. To characterize the involvement of mast cells, neutrophils, and eosinophils in lesional tissue, we analyzed seven skin biopsy specimens by an indirect immunofluorescence technique for localization of mast cell tryptase, neutrophil elastase, and eosinophil granule major basic protein, eosinophil cationic protein, and eosinophil-derived neurotoxin.

Results: Mast cells were detected in all of the specimens, with prominent numbers of mast cells in three specimens; there was minimal or no extracellular deposition of tryptase in any of the tissues.

Nodules, eosinophilia, rheumatism, dermatitis and swelling (NERDS): a novel eosinophilic disorder.

This study presents the clinical and laboratory findings of a novel syndrome associated with eosinophilia. Two young women presented with marked eosinophilia, and large, non-tender compressible articular nodules arising from the tenosynovium of extensor tendons, dermatitis, episodic swelling of the hands and/or feet and pain in adjacent muscles and joints. Tissue specimens were examined by routine haematoxylin and eosin staining, immunofluorescent staining for eosinophil granule major basic protein (MBP) and rhodamine-avidin or tryptase staining for mast cells.

The human mast cell chymase gene (CMA1): mapping to the cathepsin G/granzyme gene cluster and lineage-restricted expression.

Genes encoding T-cell-receptor alpha/delta chains, neutrophil cathepsin G, and lymphocyte CGL/granzymes are closely linked on chromosomal band 14q11.2. The current work identifies the human mast cell chymase gene (CMA1) as the fourth protease in this cluster and maps the gene to within 150 kb of the cathepsin G gene.

Immunofluorescent staining for mast cells in idiopathic pulmonary fibrosis: quantification and evidence for extracellular release of mast cell tryptase.

In many diseases, retrospective analysis for determining the presence of mast cells has been difficult because of their loss of metachromatic staining properties once tissue has undergone formalin fixation. We quantified mast cells in peribronchiolar tissue of idiopathic pulmonary fibrosis (IPF) and in normal human lung by using rabbit antiserum to human mast cell tryptase. In lung biopsy specimens from 15 patients with IPF, the mean number of mast cells per high-power field in connective tissue directly adjacent to the lumen of small airways (0.

Elevated serum levels of interleukin-5 in patients with the syndrome of episodic angioedema and eosinophilia.

The syndrome of episodic angioedema and eosinophilia is characterized by cyclic edema, marked peripheral blood eosinophilia, and eosinophil degranulation in the dermis. Using a sensitive immunoenzymetric method, we measured serum interleukin (IL)-5 levels in four patients with this syndrome. We also determined the percentage of activated T cells in the peripheral blood of a new patient before and during an attack.

IL-4 regulates c-kit proto-oncogene product expression in human mast and myeloid progenitor cells.

The c-kit proto-oncogene encodes the receptor for a novel hemopoietic cytokine, termed stem cell factor (SCF) or mast cell growth factor (MGF) according to its stimulating spectrum. The human receptor for SCF/MGF is expressed in a subset of normal bone marrow progenitor cells, in leukemic myeloid cells, and in mast cells. In the present study, the effects of recombinant human growth regulators (IL-1 through -9, granulocyte-macrophage/granulocyte/macrophage-CSF, IFN, and TNF) on c-kit proto-oncogene product expression were analyzed by indirect immunofluorescence, by using the anti-SCF/MGFR mAb YB5.

Eosinophil differentiation of human umbilical cord mononuclear cells and prolonged survival of mature eosinophils by murine EL-4 thymoma cell conditioned medium.

Umbilical cord mononuclear cells, HL-60 cells, HL-60 clones selected for eosinophil differentiation, and the eosinophil leukemia cell line EoL were tested for their ability to produce eosinophil peroxidase. HL-60 clones selected for eosinophil differentiation produced eosinophil peroxidase, as judged by staining of cells for cyanide-resistant peroxidase activity; however, these cells lost their ability to produce eosinophil peroxidase in long-term culture. In contrast, eosinophil precursors from human umbilical cord blood mononuclear cells stimulated with murine EL-4 conditioned medium (EL-4 CM) were regularly induced to eosinophil protein synthesis, including eosinophil peroxidase, major basic protein, eosinophil cationic protein, and eosinophil-derived neurotoxin, as assessed by cyanide-resistant peroxidase and immunofluorescence staining.

Interleukin 4 promotes expression of mast cell ICAM-1 antigen.

Cell recognition molecules play a crucial role in the regulation of immune cells. We recently found that mast cells (MCs) express leukocyte recognition molecules, including ICAM-1 antigen, a natural ligand of LFA-1. We here report that interleukin 4 (IL-4), a pleiotropic cytokine and mast cell differentiation factor, selectively promotes expression of surface ICAM-1 antigen and ICAM-1 mRNA in human MCs.

Failure to detect IL-3-binding sites on human mast cells.

IL-3, a pleiotropic lymphokine, has been termed mast cell growth factor because it promotes growth and differentiation of murine mast cells. Murine mast cells, in turn, express cell surface receptors for IL-3. Human rIL-3 has been shown to induce proliferation and differentiation of human basophils and to activate basophils via high affinity binding sites.

Comparison of the effects of intravenous LNC-834, a new antiarrhythmic agent, and quinidine in canine models of arrhythmia.

The effects of intravenous LNC-834, a new antiarrhythmic agent, and quinidine sulfate were evaluated and compared in 24-h infarction, programmed electrical stimulation (PES), and ventricular fibrillation threshold (VFT) canine models of cardiac arrhythmias. In the 24-h infarction model (24 h after myocardial infarction), animals averaged 85% arrhythmic beats before treatment. LNC-834 gave greater suppression of these spontaneous arrhythmias (97%) and had a longer duration of action (150 min) than did quinidine (70% and 85 min, respectively) at 10 mg of base/kg, although plasma levels were comparable (1.

Purification of tryptase from a human mast cell line.

The neutral protease tryptase has been isolated from a human mast cell line, HMC-1. The HMC-1 line was established from the peripheral blood of a patient with mast cell leukemia and maintained as continuously proliferating clones in vitro and as solid mast cell tumors in nude mice. HMC-1-derived tryptase was purified by sequential chromatography on Dowex 1, DEAE 5 PW, and heparin-agarose.

Sequestration of eosinophil major basic protein in human mast cells.

Previous studies showed that lung and skin mast cells do not contain eosinophil granule major basic protein (MBP). However, MBP has been localized by immunofluorescence to mast cells from a recently established human mast cell line. Analysis of MBP in human mast cell-1 cell lysates by radioimmunoassay showed immunochemical similarity to eosinophil MBP as judged by comparison of dose-response regression lines.

Regulation of ornithine decarboxylase gene expression in MCF-7 breast cancer cells by antiestrogens.

Ornithine decarboxylase (ODC) is an enzyme intimately related to cell growth regulation. The metabolic products of ODC, the polyamines, are known to play a vital role in the structure and function of biological macromolecules including nucleic acids and proteins. The activity of ODC is stimulated by estrogens in their target cells.

In vitro sensitivity of immature human mast cells to chemotherapeutic agents.

Cells from the human immature mast cell line, HMC-1, were tested for their sensitivity to 11 chemotherapeutic agents by changes in viability and incorporation of tritiated thymidine ([3H]-thymidine) after 72 h of in vitro drug exposure. Doxorubicin hydrochloride and cytosine arabinoside were the most active agents against HMC-1 cells at the concentrations tested. Doxorubicin hydrochloride inhibited the incorporation of [3H]-thymidine and decreased the viability of HMC-1 cells by greater than 90% at a concentration of 0.

Polyunsaturated fatty acids stimulate superoxide formation in tumor cells: a mechanism for specific cytotoxicity and a model for tumor necrosis factor?

Some neoplastic cell lines are readily killed when incubated in the presence of polyunsaturated fatty acids (PUFA). In an attempt to elucidate this phenomenon, we studied PUFA-driven superoxide (O2-) production by cultured NS-1 cells (murine lymphoid tumor cells). We find: (1) Even in the absence of added PUFA, NS-1 cells generate O2- (i.

Phosphorylation of tyrosine enhances its electron transfer capability: a model of redox modulation as oncogene expression?

The influence of tyrosine and o-phosphotyrosine on the transfer of electrons to nitrobluetetrazolium (NBT) was studied. Tyrosine phosphate was found to strongly promote the transfer of electrons from ferrous iron to NBT, while tyrosine was inhibitory. The enhancement of NBT reduction by tyrosine phosphate was blocked by superoxide dismutase (SOD).

The dopaminergic D receptor: another example of reductive activation?

We have previously suggested that several intercellular messengers activate their receptors via reductive activation. Adenylate cyclase activation involves exposure of a sulfhydryl group. The dopamine D1 receptor activates this enzyme.