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)

Two different -SH groups associated with the opiate receptors of the mouse neuroblastoma X rat glioma hybrid NG108-15 have been identified. Modification of these by N-ethylmaleimide (NEM) (presumed to be via alkylation) or by para-chloromercuribenzoic acid (presumed to be via formation of mercury adducts) decreases the binding of both opiate agonists and antagonists to these receptors. Agonist binding is more sensitive than antagonist binding to modification by NEM. Losses in antagonist binding are accounted for totally by decreases in the number of binding sites; there are no corresponding losses in antagonist affinity. Losses of antagonist binding exhibit a pseudo-first order rate constant; the modification of only one such group completely destroys the binding site. Both agonists and antagonists protect against modification of this group by NEM. Sodium and lithium, but not GTP, also protect this group, indicating that the action of these monovalent cations is directly on the receptor moiety. Losses in agonist binding stem not only from decreases in receptor number but also from selective losses in affinity. This -SH group appears to be different from the one at the binding site as sodium, GTP, and antagonist ligands do not protect against losses in agonist affinity. Agonist high affinity also is lost in a pseudo-first order fashion indicating that an alteration of only one -SH group per receptor complex is sufficient to produce this effect. The possible roles of two sulfhydryls in opiate receptor function are discussed.
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PMID:Protection of opiate receptors in NG108-15 against modification by N-ethylmaleimide. 629 30

It has been repeatedly demonstrated that the neuroblastoma-glioma (NG 108-15) cell line has opiate receptors that inhibit adenylate cyclase and it has been proposed that this inhibition is mediated by a naloxone reversible stimulation of a low Km GTPase (Koski and Klee, Proc. Natl. Acad. Sci. 78:4185, 1981). The guanine nucleotides of NG cells were labeled with [3H]guanine followed by incubation with 10(-6)M guanine. Etorphine (10(-6)M) or vehicle were added and the incubations continued for 1-4 min. The reaction was stopped with 5 percent TCA containing nucleotides as carriers and markers for the HPLC. Marker nucleotides were detected at 254 nm and the labeled nucleotides by liquid scintillation spectrometry. In several experiments, etorphine failed to produce any measurable change in the labeled nucleotides or in the GTP/GDP ratios. To verify that the opiate receptors were functional we measured its capacity to inhibit the formation of cAMP induced by PGE1. We also studied the effects of naloxone and PGE1 on the formation of cAMP in opiate tolerant cells. Tolerant cells responded to naloxone with a 50 percent increase in cAMP, indicating again that the opiate receptors were functional. Our results are consistent with the idea that in intact NG108-15 cells the opiate-mediated hydrolysis of GTP observed in cell membrane preparations is of very small magnitude.
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PMID:Failure of opiates to increase the hydrolysis of GTP in neuroblastoma-glioma 108-15 cells. 631 Mar 3

beta-Adrenergic receptors were demonstrated in membrane preparations from 6 human Ewing's sarcomas and compared to those from 46 other pediatric cancers with the use of the beta-adrenergic antagonist (-)-(3H)dihydroalprenolol [(-)[3H]DHA]. In contrast to the high numbers of receptor sites found in Ewing's sarcomas (55-640 fmol x mg-1 protein; dissociation constant Kd, 1-2 nM), other childhood cancers (neuroblastoma, rhabdomyosarcoma, brain tumors, lymphoma, osteosarcoma, hepatoblastoma, yolk sac, and Wilms' tumor) contained in general fewer beta-adrenergic receptor sites. Characteristics of (-)-[3H]DHA binding were therefore more fully characterized in the Ewing's tumors. Competition of (-)-[3H]DHA binding by classical catecholamine agonists, as well as by subtype selective agents metoprolol and zinterol, demonstrated the presence of a homogeneous population of beta 1-adrenergic sites in several Ewing's tumors. Adenylate cyclase activity in all Ewing's sarcomas was enhanced by GTP and NaF. However, in spite of high numbers of beta-adrenergic receptors, (-)-isoproterenol was not very effective in the activation of adenylate cyclase activity in several of the Ewing's tumors tested. Neither guanyl-5'-yl-imidophosphate nor GTP altered agonist potency for the receptor site in these catecholamine-insensitive tumors. Hill coefficients obtained from the competition experiments with (-)-isoproterenol (in the presence or absence of guanine nucleotide) were approximately 1.0. These uncoupled receptors were resistant to N-ethylmaleimide denaturation and were densensitized only 50% during culture in the presence of (-)-isoproterenol. Thus Ewing's sarcomas are relatively rich in beta-adrenergic sites, and several tumors appear to have a coupling lesion involving guanine nucleotide-dependent regulatory protein interaction with beta-adrenergic receptors and adenylate cyclase, similar in phenotype to that described in the (unc) variant of S49 mouse lymphoma.
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PMID:beta-Adrenergic receptors in pediatric tumors: uncoupled beta 1-adrenergic receptor in Ewing's sarcoma. 631 52

The incorporation of methionine, lysine, and leucine into protein was studied in Ca2+-depleted and Ca2+-restored preparations of C-6 glial tumor cells in minimal medium. Although incorporation proceeded at linear rates in both preparations for more than 1 h and into the same spectrum of proteins, Ca2+-restored cells incorporated amino acid 5- to 10-fold more rapidly than Ca2+-depleted cells. Addition of approximately 200 microM Ca2+ in excess of chelator was required to achieve maximal rates of incorporation in Ca2+-depleted preparations. Stimulation by Ca2+ was rapid in onset (several minutes) and slowly reversible by chelator. Ca2+ was uniquely potent and specific among physiologically occurring cations in conferring such stimulation. Stimulation of amino acid incorporation by Ca2+ occurred over a broad range of pH and osmolarities and was facilitated by Mg2+. The effects of Ca2+ in stimulating amino acid incorporation were not traceable to changes in cAMP metabolism, amino acid uptake, protein catabolism, cell ATP or GTP content, or aminoacylation of transfer RNA. Actinomycin D (1 microgram/ml) did not block the stimulatory effects of Ca2+ although puromycin and cycloheximide did. The stimulatory effects of Ca2+ on protein synthesis were not restricted to C-6 in minimal medium. Protein synthesis was reduced by ethylene glycol bis(B-aminoethyl ether)-N,N,N',N'-tetraacetic acid 40 to 75% in C-6 glioma, GH3 pituitary tumor, PC-12 adrenal tumor, N2A neuroblastoma, and HeLa cells incubated under simulated growth conditions with various enriched media and sera. Ca2+-depleted S49 lymphoma, CHO ovarian tumor, and normal, dispersed chicken embryo cells in enriched medium responded to Ca2+ restoration with increased rates of protein synthesis as did collagenase-dispersed normal rat liver cells in minimal medium. Protein synthesis in rabbit reticulocyte lysates was also inhibited by Ca2+-selective chelators or by Ca2+ removal by parvalbumin affinity chromatography and the inhibition was reversed by Ca2+. These findings are consistent with the existence of a Ca2+ requirement in the translational phase of protein synthesis in eukaryotic cells.
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PMID:Identification of a Ca2+ requirement for protein synthesis in eukaryotic cells. 631 27

Previous studies with membranes from rat heart (Mol. Pharmacol. 21: 570-580, 1982) and human platelets (J. Biol. Chem. 257: 2829-2833, 1982) have suggested that inhibition of adenylate cyclase by occupation of hormone receptors is blocked by pretreatment of membranes with relatively low concentrations of N-ethylmaleimide (NEM). Using membranes derived from NG108-15 neuroblastoma X glioma cells as a model system, we have examined the effect of NEM on the interaction of three inhibitory receptors with adenylate cyclase. Pretreatment of membranes with 100 to 216 microM NEM resulted in a loss of the capacity of agonists to inhibit adenylate cyclase through muscarinic cholinergic and opiate receptors and a loss of GTP-sensitive high-affinity binding of agonists to both of these receptors. Under the same conditions, stimulation of adenylate cyclase by prostaglandin E1 was unchanged. In contrast to the total loss of capacity to inhibit adenylate cyclase by muscarinic and opiate receptor activation, the inhibition of adenylate cyclase by activation of alpha-2 adrenergic receptors was only partially blocked by maximally effective concentrations of NEM. Similarly, GTP-sensitive high-affinity binding of epinephrine to alpha-2 receptors still occurred in NEM (316 microM)-treated membranes. Whereas only a decrease in the efficacy of muscarinic and opiate receptor agonists for inhibition of adenylate cyclase occurred as a result of NEM treatment, pretreatment of membranes with 316 microM NEM resulted in a 30-fold decrease in the potency of epinephrine for inhibition of adenylate cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Modification of receptor-mediated inhibition of adenylate cyclase in NG108-15 neuroblastoma X glioma cells by n-ethylmaleimide. 631 78

Tetrahydrobiopterin content was determined in several clonal cell lines by reversed-phase HPLC and subsequent electrochemical detection. The same chromatography system was used to determine the total biopterin (tetrahydrobiopterin and 7,8-dihydrobiopterin) by fluorescence detection. The catecholamine-producing clones neuroblastoma N1E-115 and pheochromocytoma PC-12 contained 96 and 60 ng tetrahydrobiopterin/mg protein, respectively. The corresponding amount for the neuroblastoma clone N2A was 36 ng/mg protein. The tetrahydrobiopterin content in C-6 glioma cells was below the limit of detection. The total biopterin is about 20% above the tetrahydrobiopterin content. Tetrahydrobiopterin and biopterin from the cells were identified by coelution with standard solutions and by potential-current relationship or emission and excitation spectra, respectively. Addition of 2,4-diamino-6-hydroxypyrimidine, an inhibitor of biopterin synthesis from GTP, to the culture medium of PC-12 cells resulted in a dose-dependent decrease of tetrahydrobiopterin and total biopterin content within 4 h, suggesting that the cells are capable of synthesising the biopterin which was found. A decrease in intracellular tetrahydrobiopterin levels by different concentrations of 2,4-diamino-6-hydroxypyrimidine reduces the cellular production of dihydroxyphenylalanine after inhibition of aromatic L-amino acid decarboxylase, indicating that the concentration of tetrahydrobiopterin might be a limiting factor for catecholamine synthesis in catecholamine-producing cells.
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PMID:Tetrahydrobiopterin and total biopterin content of neuroblastoma (N1E-115, N2A) and pheochromocytoma (PC-12) clones and the dependence of catecholamine synthesis on tetrahydrobiopterin concentration in PC-12 cells. 669 75

Na+ has been implicated as a requirement for the inhibition of adenylate cyclase by hormones and neurotransmitters. This study examines effects of salt concentration on neuroblastoma plasma membranes that occur in the absence of an inhibitory hormone. The adenylate cyclase response to stimulatory agonists (GTP plus PGE1 (3), PGI2 or PGE2) was influenced by NaCl. As the [NaCl] increased to 150 mM, an increase in maximal activity and a decrease in apparent affinity was observed. At concentrations above 150 mM, NaCl decreased prostaglandin affinity and progressively decreased maximal activation. The GTP requirement was not altered by 30 or 150 mM NaCl in the presence of PGE1 or PGI2. The rate of Gpp(NH)p stimulated activity increased as the [NaCl] was increased in the assay. This increased rate was conserved when membranes activated in the presence of Gpp(NH)p and NaCl were reassayed in the absence of guanine nucleotide or salt. The salt evoked rate increase was proportionally greater at submaximal MgCl2 concentrations. The concentration requirement for Mg2+ was reduced by salt for adenylate cyclase in the presence of GTP or Gpp(NH)p. However, the enzyme stimulated by hormone exhibited a Mg2+ requirement that was low in the absence of salt and could not be further reduced by increased [NaCl]. Alternative monovalent cations (150 mM Li+, K+, Cs+, but not choline or tetramethylammonium) and anions (SO4=) substituted for NaCl. The observed effects were reversible upon washing the membranes and neither ouabain nor tetrodotoxin altered the response. These effects may result from a conformational alteration of a protein particularly sensitive to neutral salts in the assay.
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PMID:Effects of NaCl concentration on adenylate cyclase regulation by prostaglandins and guanine nucleotides. 675 90

Clonal cell line NCB-20 (a hybrid of mouse neuroblastoma N18TG2 and Chinese hamster 18-day embryonic brain explant) expressed both high- (KD 180 nM) and low-affinity (greater than 3000 nM) binding sites for [3H]serotonin (5-HT) which were absent from the parent neuroblastoma. The low-affinity binding site was eliminated by 1 microM spiperone. The order of drug potency for inhibition of high-affinity [3H]5-HT binding was consistent with a 5-HT1 receptor (5,6 - dihydroxytryptamine = 5-HT = methysergide = 5-methoxytryptamine greater than cyproheptadine = clozapine = mianserin greater than spiperone greater than dopamine = morphine = ketanserin = norepinephrine). [3H]5-HT binding was inhibited by guanine nucleotides (e.g., GTP and Gpp(NH)p), whereas antagonist binding was not; ascorbate was also inhibitory. A 30-min exposure of cells to 1-2 microM 5-HT or other agonists produced a three- to fivefold stimulation of cyclic AMP levels. The order of potency for 5-HT agonist stimulation of basal cyclic AMP levels and 5-HT antagonist reversal of agonist-stimulated levels was the same as the order of drug potency for inhibition of high-affinity [3H]5-HT binding, suggesting linkage of the 5-HT1 receptor to adenylate cyclase in NCB-20 cells.
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PMID:Characterization of an adenylate cyclase-linked serotonin (5-HT1) receptor in a neuroblastoma X brain explant hybrid cell line (NCB-20). 683 55

The ATP signaling mechanism in neuroblastoma x glioma hybrid NG108-15 cells differentiated by exposure to dibutyryl-cAMP was characterized. In cells loaded with fura-2, ATP rapidly raised the cytosolic Ca2+ concentration ([Ca2+]i); the magnitude of the rise was inversely proportional to the extracellular Na+ concentration. Large increases in cytosolic Na+ concentration, measured with the fluorescent Na+ indicator sodium-binding benzofuran isophthalate, were dose-dependently elicited by ATP. ATP also evoked the entry of ethidium bromide into cells, and this process was inhibited by Mg2+. Inositol-1,4,5-trisphosphate (IP3) generation induced by ATP was totally blocked by removal of extracellular Ca2+, but residual IP3 generation still remained in nondifferentiated cells. In addition, ATP produced a concentration-, time-, and Mg(2+)-dependent biphasic uptake of 45Ca2+. A range of nucleotides and ATP analogues, including CTP, UTP, and GTP, induced only 9-29% of the ATP response. However, adenosine 5'-thiotriphosphate evoked 79% of ATP-induced 45Ca2+ uptake. 45Ca2+ uptake elicited by ATP could be potently blocked by purinoceptor antagonists, but other tested reagents less effectively blocked the action of ATP. When bradykinin was used as an agonist, the [Ca2+]i rise was transient and was insensitive to the extracellular Na+ concentration. Na+ influx, entry of ethidium bromide, and 45Ca2+ uptake were unaffected by bradykinin. Furthermore, bradykinin-evoked IP3 generation was insensitive to extracellular Ca2+. Neither ATP nor bradykinin had any effect on cAMP levels within cells. These data suggest that ATP induces a [Ca2+]i rise in differentiated NG108-15 cells via two distinct Ca2+ influx mechanisms, i.e., a receptor-operated cation channel and pores formed by ATP4-. These mechanisms are distinct from those elicited by bradykinin.
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PMID:Two distinct ATP signaling mechanisms in differentiated neuroblastoma x glioma hybrid NG108-15 cells. 751 80

Murine N1E-115 neuroblastoma cells are shown to express a single class of angiotensin II (Ang II) receptors that display all the pharmacological properties defining the Ang II receptor subtype 2 (AT2): high affinity for 125I-labelled AT2-selective agonist CGP 42112 (Kd 91 +/- 19 pM); expected rank order of potency (CGP 42112 = (Sar1,Ile8)Ang II > or = Ang II > PD 123319 >> DUP 753) for several Ang II analogues; increased binding in the presence of the reducing reagent dithiothreitol (DTT); and insensitivity to analogues of GTP. Molecular cloning of cDNA encoding AT2 receptors from N1E-115 cells reveals nucleotide sequence identity with the AT2 subtype expressed in fetal tissue. Murine AT2 receptors transiently expressed in COS cells display the same pharmacological profile as endogenous Ang II receptors of N1E-115 cells. Taken together, these data reveal the exclusive presence of the AT2 receptor subtype in N1E-115 cells. Incubation of N1E-115 cells with Ang II leads to a marked decrease in the level of tyrosine phosphorylation of several proteins with apparent molecular masses of 80, 97, 120, 150 and 180 kDa respectively. Tyrosine dephosphorylation of the same set of proteins is observed after treatment with the AT2-specific agonist CGP 42112. The response to both effectors is rapid and transient, showing a maximum between 5 and 10 min, and returning to basal levels after 20-30 min. In both cases, tyrosine dephosphorylation can be prevented by co-incubation with an excess of the antagonist Sarile. These data thus establish that AT2 receptor activation leads to protein tyrosine dephosphorylation in N1E-115 cells, and support a possible role for AT2 receptors in the negative regulation of cell proliferation.
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PMID:Angiotensin II AT2 receptors are functionally coupled to protein tyrosine dephosphorylation in N1E-115 neuroblastoma cells. 753 1


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