Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary astrocyte cultures, C6 glioma cells, and N18 neuroblastoma cells were assayed for nitric oxide synthase (NOS) activity with a bioassay of cyclic GMP production in RFL-6 fibroblasts. Treatment of astrocyte cultures for 16-18 h with lipopolysaccharide (LPS) induced NOS-like activity that was L-arginine and NADPH dependent, Ca2+ independent, and potentiated by superoxide dismutase. Induction was evident after 4 h, was dependent on the dose of LPS, and required protein synthesis. Treatment of astrocyte cultures with leucine methyl ester reduced microglial cell contamination from 7 to 1%, with a loss of 44% of NOS-like activity. C6 cells treated with LPS also showed Ca(2+)-independent and L-arginine-dependent NOS-like activity. N18 cells demonstrated constitutive Ca(2+)-dependent NOS-like activity that was not enhanced by LPS induction. These data indicate that NOS-like activity can be induced in microglia, astrocytes, and a related glioma cell line as it can in numerous other cell types, but not in neuron-like N18 cells.
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PMID:Induction of nitric oxide synthase in glial cells. 137 33

This study evaluates the role of N-hydroxylamine (NH2OH) in activating soluble guanylate cyclase in the mouse neuroblastoma clone N1E-115. It has been proposed that NH2OH is a putative intermediate in the biochemical pathway for the generation of nitric oxide (NO)/endothelium-derived relaxing factor (EDRF) from L-arginine. NH2OH caused a time- and concentration-dependent increase in cyclic GMP formation in intact cells. This response was not dependent on Ca2+. In cytosol preparations the activation of guanylate cyclase by L-arginine was dose-dependent and required Ca2+ and NADPH. In contrast, NH2OH itself did not activate cytosolic guanylate cyclase but it inhibited the basal activity of this enzyme in a concentration-dependent manner. The formation of cyclic GMP in the cytosolic fractions in response to NH2OH required the addition of catalase and H2O2. On the other hand, catalase and/or H2O2 lead to a decrease in L-arginine-induced cyclic GMP formation. Furthermore, NH2OH inhibited L-arginine- and sodium nitroprusside-induced cyclic GMP formation in the cytosol. The inhibition of L-arginine-induced cyclic GMP formation in the cytosol by NH2OH was not reversed by the addition of superoxide dismutase. These data strongly suggest that NH2OH is not a putative intermediate in the metabolism of L-arginine to an activator of guanylate cyclase.
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PMID:N-hydroxylamine is not an intermediate in the conversion of L-arginine to an activator of soluble guanylate cyclase in neuroblastoma N1E-115 cells. 167 45

We have studied receptor-mediated generation of an activator of soluble guanylate cyclase in cultured mouse neuroblastoma cells (clone N1E-115) by ESR/spin trapping spectroscopy. A spin adduct was detected during the activation of muscarinic receptors by carbamylcholine in the presence of the spin trap 3,5-dibromo 4-nitrosobenzene sulphonate (DBNBS). The spin adduct does not correspond to that originating from the free radical nitric oxide or hydroxylamine. The same adduct was generated in cytosol preparations from N1E-115 cells incubated with L-arginine, NADPH, in the presence of calcium. The use of isotopically labelled guanidino-N15-L-arginine supported the generation of a DBNBS spin trapped adduct originating from the guanidino moiety of L-arginine. Superoxide dismutase (SOD) stabilized the precursor of the spin adduct as well as the activator of soluble guanylate cyclase derived from L-arginine. Our results provide direct evidence for the receptor-mediated formation of a diffusible precursor of NO. derived from L-arginine.
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PMID:Receptor-mediated generation of an EDRF-like intermediate in a neuronal cell line detected by spin trapping techniques. 197 69

In this study, hepatic microsomes from 5,6-benzoflavone induced C57BL/10 mice were used. To inhibit monooxygenase activities, the monoclonal antibody MAb 1-7-1 recognizing two isoenzymes of methylcholanthrene-induced cytochrome P-450 was applied. Microsomes were incubated with tritium labeled benzo(a)pyrene [G-3H]BP for 10 min at 37 degrees C. The incubation mixture contained: 50 mM potassium phosphate buffer, pH 7.25; 30 mM KCl; 3 mM MgCl2; 2 mM NADPH; 80 microM [G-3H]BP (specific activity 50 mCi/mmol); and monoclonal antibody MAb 1-7-1 or ascites fluid (NBS) containing nonspecific IgG as a control. The ratio of antibody protein/microsomal protein was 2:5. BP metabolites were extracted from incubation mixtures by ethyl acetate. The organic layer was dried over sodium sulfate, and evaporated under a stream of nitrogen. To separate BP metabolites HPLC technology was used. The column was eluted with methanol gradient (60-100%) for 45 minutes. The radio-activity of collected samples was determined using liquid scintillation counter. Differential inhibitory effects of MAb 1-7-1 on BP-metabolites formation were found, e.g. 7,8-diol was inhibited by 86.1% and quinones by 62.5%. The predominant metabolite, 3-OH-BP, was inhibited by 80.4%. Moreover, it was found that MAb 1-7-1 inhibition of benzo(a)pyrene hydroxylase activity (by 75.8%, as measured by fluorescent technique) was very similar to the inhibition of 3-OH-BP along with 9-OH-BP formation (as measured by HPLC).
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PMID:[Effect of monoclonal antibody against methylcholanthrene-induced cytochrome P-450 forms on benzo(a)pyrene metabolism in hepatic microsomes of C57BL/10 mice]. 209 79

Accumulation of cyclic GMP in cultured rat lung fibroblasts was used to test the hypothesis that N1E-115 neuroblastoma cells produce an endothelium-derived relaxing factor (EDRF)-like activity. By using this assay, the production of an EDRF-like activity in homogenates and cytosolic fractions of N1E-115 neuroblastoma cells was observed. Detection of the activity required the presence of superoxide dismutase and was inhibited by hemoglobin. Production of the EDRF-like factor was dependent on L-arginine and NADPH. The apparent Km for L-arginine was 1.25 microM and the apparent Km for NADPH was 1.67 microM. The production of the EDRF-like activity was inhibited by the L-arginine analogs, NG-monomethyl-L-arginine and NG-nitro-L-arginine, with apparent Ki values of 1.0 and 0.3 microM, respectively.
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PMID:Production of an EDRF-like activity in the cytosol of N1E-115 neuroblastoma cells. 215 50

Stimulation of soluble guanylyl cyclase in rat fetal lung fibroblasts (RFL-6 cells) was used as a sensitive assay for endothelium-derived relaxing factor/nitric oxide (EDRF/NO) formation. Intact N1E-115 cells released an EDRF/NO-like material that enhanced cyclic GMP levels in RFL-6 cells. The synthesis of this substance could be stimulated with the receptor agonist neurotensin (10 microM) or by addition of the EDRF/NO substrate L-arginine (100 microM). In Ca2(+)-free Locke's solution, stimulation of EDRF/NO production by both neurotensin and L-arginine was abolished. The EDRF/NO-synthesizing activity was localized in the cytosol of N1E-115 cells. The activity was lost after boiling and it was highly sensitive to Ca2+ with the major increase in activity occurring between 100 and 500 nM Ca2+. L-Arginine and NADPH were required for maximal synthesis of EDRF/NO by the enzyme(s). The synthesis of EDRF/NO was inhibited by the following antagonists of calmodulin-regulated functions (with the approximate IC50 values given in parentheses): calmidazolium (7 microM), trifluoperazine (10 microM), fendiline (80 microM), W-7 (N-[6-aminohexyl]-5-chloro-1-naphthalenesulfonamide) (120 microM), and compound 48/80 (3 micrograms/ml). The EDRF/NO-synthesizing activity was partially purified from N1E-115 cytosol by DE 52 anion exchange chromatography. The activity was eluted with 0.1 M KCl. The enzyme(s) showed very little activity in the presence of L-arginine (100 microM) and NADPH (100 microM), but the activity could be fully restored by addition of exogenous calmodulin (EC50, approximately 2 units/ml). At 0.3 M KCl, a fraction eluted from the DE 52 column that was also able to fully restore the EDRF/NO-synthesizing activity. Thus, this fraction is likely to contain the endogenous Ca2(+)-binding protein. It is concluded that the activity of the EDRF/NO-synthesizing enzyme(s) in N1E-115 neuroblastoma cells is regulated by Ca2+ and calmodulin.
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PMID:Hormone-induced biosynthesis of endothelium-derived relaxing factor/nitric oxide-like material in N1E-115 neuroblastoma cells requires calcium and calmodulin. 237 Aug 55

The cytosolic fraction of N1E-115 neuroblastoma cells catalysed the L-arginine- and NADPH-dependent formation of a substance that relaxed endothelium-denuded strips of rabbit aorta. Relaxations in response to this substance were enhanced in the presence of superoxide dismutase. N omega-Nitro-L-arginine and NG-monomethyl-L-arginine, two inhibitors of EDRF synthesis, markedly attenuated the relaxations. Hemoglobin, a scavenger of EDRF, and methylene blue, an inhibitor of soluble guanylate cyclase, completely abolished the relaxation to N1E-115 cytosol. In contrast, the cyclo-oxygenase inhibitor indomethacin did not alter the relaxations. These data demonstrate that the cytosol of a neuronally-derived cell line is able to synthesize a substance with pharmacological properties similar to EDRF.
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PMID:The cytosol of N1E-115 neuroblastoma cells synthesizes an EDRF-like substance that relaxes rabbit aorta. 263 48

Previous electron spin resonance studies have demonstrated that the decay of ascorbyl plus semiquinone radicals, produced in an aqueous mixture of ascorbate and 2,6-dimethoxy-p-quinone, is accelerated by ascites cells. This effect was concluded to involve a sulfhydryl-containing NAD(P)H-enzyme, and work on cultured cell lines showed that on neoplastic transformation the activity against the radicals was increased. We show here that at least three disulfide-oxidoreductases are able to quench the radicals in a similar way to that of viable cells. Glutathione reductase (EC 1.6.4.2) in the presence of NADPH and oxidised glutathione, and dihydrolipoamide dehydrogenase (EC 1.8.1.4) with NADH and lipoamide, are found to accelerate the radical decay by reducing the quinone or semiquinone. DT-diaphorase (EC 1.6.99.2) in the presence of NAD(P)H can also achieve this by reducing the quinone directly. Lipoamide dehydrogenase and glutathione reductase are also capable of reducing nitroxide spin labels, a finding considered of relevance to the reported reduction of such spin labels by neuroblastoma cells.
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PMID:Electron spin resonance studies of the interaction of oxidoreductases with 2,6-dimethoxy-p-quinone and semiquinone. 302 90

Dihydropyrimidine dehydrogenase (DPD), the initial, rate-limiting step in pyrimidine degradation, was studied in two cell lines of murine neuroblastoma (MNB-T1 and MNB-T2) that were derived from C-1300 MNB tumor carried in A/J mice. The MNB-T2 (low malignancy) cell line was originally derived from the in situ tumor and carried in tissue culture for more than 100 passages; the MNB-T1 (high malignancy) line consisted of a new sub-culture that was also established from the in situ MNB tumor. DPD activity was determined in cytosolic preparations of MNB utilizing high performance liquid chromatography to separate the radiolabeled substrate ([2-14C]thymine) from [2-14C]dihydrothymine. The apparent affinity of DPD for NADPH in MNB cells (Km approximately 0.08 mM) was identical to that of A/J mouse brain and liver. The DPD activity of the high malignancy (MNB-T1) cell line was 14.3% of that observed in the low malignancy (MNB-T2) line. In situ tumors formed after implantation of high malignancy (MNB-T1) cells into A/J mice had only 25.2% of the DPD activity observed in tumors derived from low malignancy (MNB-T2) cells. When MNB-T2 cells were injected into naive A/J mice, tumors developed in only 68% of animals, the tumor growth rate was slow and a mortality of 20% was observed. In contrast, tumors derived from injected MNB-T1 cells showed a faster growth rate and 100% mortality. Most MNB-T2 derived tumors were not lethal and ultimately resolved while the MNB-T1 derived tumors were invariably lethal. These studies support the concept that the levels of DPD activity in neoplastic cells are inversely related to their malignant expression and also provide a model to study differences between neuroblastoma cell lines derived from the same in situ tumor but which manifest different neoplastic behavior.
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PMID:Pyrimidine base degradation in cultured murine C-1300 neuroblastoma cells and in situ tumors. 333 27

NADPH diaphorase activity is used as a histochemical marker for neuronal nitric oxide (NO) synthase; however, it remains unclear whether these activities are directly correlated in all tissues. In N1E-115 neuroblastoma cells, NADPH diaphorase activity was found primarily in the particulate fraction, whereas NO synthase activity was mostly soluble. Non-induced macrophages expressed significant NADPH diaphorase activity (which was mostly particulate) but virtually no NO synthase activity. Induction of macrophages produced marked increases in both NO synthase and NADPH diaphorase activities in the soluble and particulate fractions. In endothelial cells, both NO synthase and NADPH diaphorase activities were found mostly in the particulate fraction. Purified NO synthases from brain (type I), macrophages (type II), and endothelium (type III) all showed NADPH diaphorase activity; relative activities were: macrophage > endothelium > brain. These data indicate that all known NO synthases are NADPH diaphorases; however, NO synthases represent only a fraction of total cellular NADPH diaphorase activity and these activities are not always co-localized.
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PMID:Nitric oxide synthases in neuronal cells, macrophages and endothelium are NADPH diaphorases, but represent only a fraction of total cellular NADPH diaphorase activity. 769 May 49


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