Glycosaminoglycan synthesis in mouse mastocytoma

The glycosaminoglycan synthesis in Furth solid mastocytoma tissue has been studied. Approx. 10% of the polysaccharide isolated after incubation in vitro with [(14)C]-glucosamine was digestible with chondroitinase ABC and the product of digestion was identified as 2-acetamido-2-deoxy-3-O-(beta-d-gluco-4-enepyranosyluronic acid)-4-O-sulpho-d-galactose. Similarly, labelling of polysaccharide in vivo with (35)SO(4) (2-) followed by isolation of mast-cell fractions by density-gradient centrifugation on colloidal silica revealed the presence of a polysaccharide which migrated as did chondroitin sulphate on electrophoresis in barium acetate. Chondroitinase ABC produced the same digestion product as before. Finally, the presence of the UDP-N-acetylgalactosamine-chondroitin 6-sulphate hexasaccharide N-acetylgalactosaminyltransferase previously implicated in chondroitin sulphate biosynthesis was demonstrated in microsomal particles from fractions of purified mast cells.     

ATP-dependent leukotriene export from mastocytoma cells

The biosynthesis of leukotrienes (LT) C4 and B4 is followed by an export of these mediators into the extracellular space. This transport was characterized using plasma membrane vesicles prepared from mastocytoma cells and identified as an ATP-dependent primary active process. The apparent Km-values were 110 nM for LTC4 and 48 microM for ATP. The transport rate was highest for LTC4, whereas LTD4, LTE4, and N-acetyl-LTE4 were transported with relative rates of 31, 12 and 8%, respectively, at a concentration of 10 nM. LTB4 transport was also dependent on ATP. LTC4 transport was inhibited by LTD4 receptor antagonists (IC50 = 1.0 microM for MK-571 and 1.3 microM for LY245769) and by the inhibitor of leukotriene biosynthesis MK-886 (IC50 = 1.8 microM). The ATP-dependent export carrier for leukotrienes in leukotriene-synthesizing cells represents a novel member of the family of ATP-dependent exit pumps.     

Establishment of four mouse mastocytoma cell lines

Four mastocytoma cell lines were isolated from four different mouse mastocytoma tumors. The tumors had been induced in mice treated with tetramethylpentadecane (pristane) and infected with Abelson murine leukemia virus. The cell lines have been carried in culture for over a year and can induce tumors when injected into the mouse strain in which the tumor originated. The cells contain histamine, have high affinity IgE receptors and release histamine by IgE, immune complex or ionophore A23187-induced reactions. This histamine release reaction requires Ca2+, is optimal at 37 degrees C, and is blocked by a number of metabolic inhibitors. There is no requirement for phosphatidylserine. Cloned sublines have been obtained which will be useful for Fc epsilon R, Fc gamma R; and histamine release studies.     

Degradation of heparin in mouse mastocytoma tissue

1. Heparin was prepared from mouse mastocytoma tissue by mild procedures, including extraction of mast-cell granules with 2m-potassium chloride, precipitation of the extracted polysaccharide with cetylpyridinium chloride from 0.8m-potassium chloride and finally digestion of the isolated material with testicular hyaluronidase. The resulting product (fraction GE(H)) represented approx. 40% of the total heparin content of the tissue. 2. Fraction GE(H) was fractionated by gel chromatography on Sepharose 4B into three subfractions, with average molecular weights ( M(w)) of approx. 60000-70000 (highly polydisperse material), 26000 and 9000 respectively. Treatment of each of the subfractions with alkali or with papain did not affect their behaviour on gel chromatography. Amino acid and neutral sugar analyses indicated that the two low-molecular-weight fractions consisted largely of single polysaccharide chains lacking the carbohydrate-protein linkage region. It was suggested that these heparin molecules had been degraded by an endopolysaccharidase. 3. Pulse labelling in vivo of mastocytoma heparin with [(35)S]sulphate showed initial labelling of large molecules followed by a progressive shift of radioactivity toward fractions of lower molecular weight. Further, heparin-depolymerizing activity was demonstrated by incubating (35)S-labelled heparin in vitro with a mastocytoma 10000g-supernatant fraction. Appreciable degradation of the polysaccharide occurred, as demonstrated by gel chromatography. In contrast, no depolymerization was observed on subjecting (14)C-labelled chondroitin sulphate to the same procedure.     

Lectin-binding studies of a human skin mastocytoma

Summary A solitary mastocytoma of the skin was investigated to assess the lectin-binding pattern of human mast cells. Of 18 Fluorescein-labelled lectins tested, nine reacted with mast cell granules. While lectins recognizingN-acetylgalactosamine or fucose residues did not stain mast cells, lectins with binding sites forN-acetylglucosamine, -methyl mannopyranoside, galactose, complex carbohydrates ofN-acetyl-lactosamine type and sialic acid gave a positive reaction.     

Biosynthesis of glycosaminoglycans by cultured mastocytoma cells

Biosynthesis of glycosaminoglycans by several lines of cultured neoplastic mouse mast cells was studied by incorporation of [³⁵S]sulphate (and in some cases [6-³H]glucosamine) into macromolecular materials found in both the cells and their growth media. Such intracellular and extracellular radioactively labelled materials (shown to be glycosaminoglycans by susceptibility to digestion with heparinase) were further characterized by ion-exchange chromatography and by digestion with testicular hyaluronidase and chondroitinase. All but one cell line produced chondroitin sulphate as the major sulphated glycosaminoglycan; the remainder of the glycosaminoglycan was heparin-like material. No [³H]hyaluronic acid was synthesized. Cells of a newly derived line, termed P815S, synthesized more glycosaminoglycan than the other lines. This glycosaminoglycan, found in both cells and growth medium, was almost entirely chondroitin 4-sulphate. No chondroitin 6-sulphate was found. The chondroitin 4-sulphate from the cells was shown by gel filtration to be smaller than the chondroitin 4-sulphate in the media of these cultures. This discovery of relatively high proportions of chondroitin 4-sulphate in these mastocytoma-derived cells is noteworthy, since mast cells have generally been considered to produce heparin as their major glycosaminoglycan.     

Proteoglycans of soluble fraction of mouse mastocytoma.

Proteoglycans have been isolated from a high speed supernatant fraction of a mouse mastocytoma by procedures which should minimize alteration of the native protein-polysaccharide molecule. The methods used include in vivo labeling proteoglycans with 35S-sulfate, 3H-leucine and 3H-lysine, centrifugation of the tumor homogenate at 105,000 g, cetylpyridinium fractionation of the supernatant, and further purification of some of the fractions obtained by DEAE-cellulose column chromatography, gel filtration on Sepharose 4B and cellulose acetate electrophoresis. Two major sulfated proteoglycans were obtained, one containing keratan sulfate-like material (KSP-S), the other a heparin-like polymer (HP-S). The presence in HP-S of a compound similar to heparin was confirmed by its digestibility with flavobacterium heparinase. HP-S contained about 4 per cent protein. Glycine was the predominant amino acid, and serine did not appear to be involved in the peptide-carbohydrate linkage. The proteoglycan present in HP-S appeared to be homogeneous when examined using cellulose acetate electrophoresis. KSP-S was found to contain sialic acid and its protein content was significantly higher than that of HP-S. Glutamic and aspartic acids were the most abundant amino acids in KSP-S.     

儿童皮肤肥大细胞瘤的临床病理分析

目的探讨儿童皮肤肥大细胞瘤的临床病理特征。方法对5例皮肤肥大细胞瘤进行临床病理观察和免疫组化检测。结果患者年龄3个月-8岁,3例出生时即有病变,1例在出生后半年内,另一例在7岁时发现病变,均无明显症状,免疫组化示CD43、CD117、LCA、VIM阳性,甲苯胺蓝染色见胞浆内有紫红色颗粒。结论皮肤肥大细胞瘤好发于儿童,大多数在出生时即有或6个月内发病,临床医生易诊断为脉管瘤。组织病理学上关键在于认识肥大细胞,结合免疫组化和甲苯胺蓝染色,并通过询问病史可以确诊。儿童皮肤肥大细胞瘤预后良好,在青春期会自动消退。     

Induction of granulopoiesis of mastocytoma cells: ultrastructural and cytochemical studies on production of serotonin in a cultured mouse mastocytoma cell line

Electron microscopic observations of an originally established mouse mastocytoma cell line (BSP-MST-2) revealed that the cytoplasm of many of the MST-2 cells contained small and low osmiophilic granules and a few mature electron-dense granules. Fluorescent- and immuno-histochemical examinations also suggested the immaturity of granules as the cytoplasmic reaction for serotonin (5-HT) was weak. Induction of further maturation of granules was investigated by administration of various chemical agents. Among the chemicals examined, sodium butyrate and hydrocortisone were effective. In the presence of 1 mM sodium butyrate for 24 h, the cytoplasmic granules contained an abundant dense matrix. MST-2 cells incubated with hydrocortisone at 5 micrograms/ml for 24 h showed a somewhat different granulopoietic pattern from those incubated with sodium butyrate, including numerous electron-dense progranules. Fluorescent- and immuno-histochemical studies showed increased reactions of cytoplasmic 5-HT of both butyrate- and hydrocortisone-treated MST-2 cells. The specificity of these morphological and cytochemical changes was confirmed by treatment with reserpine, a drug which depletes cellular 5-HT; electron-dense materials were virtually diminished and cytochemical reactions were significantly decreased. The mode of induced production of 5-HT in mastocytoma granules is discussed, in relation to mastocyte differentiation.     

NADH-specific dihydropteridine reductase in mastocytoma P-815 cells

NADH-specific dihydropteridine reductase [EC 1.6.99.7] was purified from mouse mastocytoma P-815 cells. Km values for NADH and NADPH were determined to be 1.4 microM and 32 microM, respectively, using tetrahydro-6-methylpterin. Molecular weight was 50,000, and subunit molecular weight was 25,000. The enzymes from P-815 and liver of host mouse (DBA/2) showed similar electrophoretic mobility on polyacrylamide gel. The P-815 enzyme reacted with antiserum against bovine liver NADH-specific dihydropteridine reductase, forming a single precipitin line.     

Cyclic AMP calcium and the growth of mastocytoma cells

Arresting P815 mastocytoma cell growth with N6, O2'-dibutyryladenosine 3':5' cyclic monophosphate (db cAMP) and theophylline increased 45Ca2+ uptake and efflux by the cells (i.e, Ca2+ cycling) without altering cytoplasmic free Ca2+ concentrations or the amount or distribution of protein kinase C in the cells. Attempts to identify the Ca2+ channels involved using a wide variety of drugs were unsuccessful. However, the inhibitory effect of db cAMP on growth was greatly increase in medium containing low Ca2+ concentrations, confirming that interactions between Ca2+ and cyclic AMP can affect mastocytoma cell growth.     

Regulation of topoisomerase II by murine mastocytoma cells.

Nuclei from K21 murine mastocytoma cells do not form topoisomerase II-DNA adducts in response to amsacrine in the absence of a cytoplasmic factor tentatively identified as a type of casein kinase (Darkin, S.J. and Ralph, R.K. (1991) Biochim. Biophys. Acta 1088, 285-291). The stimulatory activity was present in extracts from cells grown in horse serum but not in calf serum. Activity was lost following growth arrest by serum deprivation. In contrast, topoisomerase II activity in isolated nuclei did not decline during growth arrest. These results suggest that the resistance of some non-cycling tumour cells to anti-cancer drugs may result from decreased activation of topoisomerase II.