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)

Many agonist ligands are known experimentally to display a range of efficacies and potencies in different tissues and preparations. To analyze the role of the levels of receptor expression and availability in the intrinsic activities and potencies of agonists, the function of a number of beta-adrenoceptor ligands was examined in clones of neuroblastoma x glioma hybrid NG108-15 cells transfected to express differing levels of the human beta 2-adrenoceptor, as well as after treatment of these cell lines with the irreversible beta-adrenoceptor antagonist bromoacetyl alprenolol menthane (BAAM). Clone beta N22 expressed approximately 10-fold higher levels of the receptor than did clone beta N17. In measurements of agonist stimulation of adenylyl cyclase activity in membranes of these cells or agonist stimulation of the formation of the complex of Gs alpha and adenylyl cyclase, which acts as the high affinity binding site for [3H]forskolin in whole cells, a series of beta-adrenoceptor agonists, including dichloroisoprenaline, ephedrine, dobutamine, and salbutamol, displayed higher intrinsic activity and showed concentration-response curves that were substantially to the left (lower EC50 values) in clone beta N22, compared with clone beta N17. Treatment of clone beta N22 cells with varying concentrations of BAAM reduced the intrinsic activity of these ligands and shifted the concentration-response curves for these agents to the right. In clone beta N22 cells and membranes, reduction in the observed intrinsic activity for ephedrine required elimination of a smaller fraction of the beta 2-adrenoceptor reserve than for salbutamol and reduction in the effect of the full agonists isoprenaline and epinephrine was noted only with high fractional elimination of the receptor pool. The effect of isoprenaline was substantially reduced, however, by BAAM treatment of clone beta N17 cells, where the beta 2-adrenoceptor number approached extremely low levels. Analysis of the data using the formalisms of Whaley et al. [Mol. Pharmacol. 45:481-489 (1994)] showed that prediction of alterations in agonist potency with receptor number for full agonists can be adequately extended to partial agonists.
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PMID:Analysis of the role of receptor number in defining the intrinsic activity and potency of partial agonists in neuroblastoma x glioma hybrid NG108-15 cells transfected to express differing levels of the human beta 2-adrenoceptor. 765 65

Secretin is a 27-amino acid neuroendocrine peptide that stimulates fluid and electrolyte secretion in the gastrointestinal tract, activates tyrosine hydroxylase activity in the central nervous system, and affects cardiac and renal function. Specific receptors for secretin have been previously characterized on neuroblastoma cells, pancreatic acini, gastric glands, and liver cholangiocytes. We report here the isolation of a 1616-base pair cDNA from human lung tissue that encodes a 440-amino acid, 50-kDa, G protein-coupled human secretin receptor (HSR), with homology of 80% with the rat secretin receptor and 37% with the human type I vasoactive intestinal peptide receptor. Northern blot analysis of human tissue mRNA revealed that the relative intensity for expression of a 2.1-kilobase HSR transcript was pancreas > kidney > small intestine > lung > liver, with trace levels in brain, heart, and ovary. Stable transfectants of HSR in human embryonic kidney 293 cells, termed 293S12, expressed 10(5) binding sites/cell for 125I-secretin, with an apparent Kd of 3.2 nM. Vasoactive intestinal peptide, pituitary adenylyl cyclase-activating peptide-38, and glucagon were less potent (by 3 orders of magnitude) than secretin in competitively inhibiting 125I-secretin binding to 293S12 cells. Secretin evoked concurrent dose-dependent increases in intracellular cAMP and calcium levels in 293S12 cells and stimulated a 4-fold increase in phosphatidylinositol hydrolysis. Thus, the HSR expressed by stable transfectants can couple to two distinct intracellular signaling pathways.
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PMID:Molecular cloning and expression of a human secretin receptor. 770 Feb 44

Cyclic AMP-mediated desensitization of D1 dopamine receptor-coupled adenylyl cyclase was investigated using NS20Y neuroblastoma cells. Pretreatment of the cells for 24 h with 8-(4-chlorophenylthio)-adenosine-3':5'-cyclic monophosphate (CPT-cAMP), a membrane-permeable analog of cAMP, resulted in an approximately 90% reduction of the maximum dopamine-stimulated adenylyl cyclase activity. In addition, there was a twofold reduction in the potency of dopamine for stimulating cAMP production that was not dependent on the concentration of Mg2+ in the assay. These effects of CPT-cAMP pretreatment were time dependent, showing a t1/2 of about 3 h and a maximum reduction after about 8 h. Receptor-binding activity, as measured using the D1-selective antagonist [3H]SCH-23390, also declined following CPT-cAMP pretreatment with a t1/2 of about 5 h and a maximum reduction of about 70% after 20 h. Saturation analysis indicated that the loss in radioligand binding was due to a reduction in maximum binding capacity (Bmax) with no alteration in receptor affinity (KD). The EC50 of CPT-cAMP for producing enzyme desensitization and D1 receptor downregulation was determined to be about 30 microM with a maximal response occurring at 1 mM. These regulatory effects of CPT-cAMP were pharmacologically specific as other analogs of cAMP, such as dibutryl-cAMP, 8-bromo-cAMP, and Sp-cAMPS, were capable of inducing D1 receptor desensitization and downregulation, whereas treatment of the cells with the cAMP antagonist Rp-cAMPS had no effect. Conversely, Rp-cAMPS was capable of blocking the regulatory effects of CPT-cAMP but was apparently without effect in blocking dopamine-induced desensitization.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cyclic AMP-mediated desensitization of D1 dopamine receptor-coupled adenylyl cyclase in NS20Y neuroblastoma cells. 770 30

In neuroblastoma x glioma hybrid NG108-15 cells, ATP induced a concentration-dependent increase in the intracellular Ca2+ concentration ([Ca2+]i), accompanied by inositol phosphate formation. Under the same conditions, we found a marked increase in cAMP levels produced by ATP at concentrations similar to those required to increase [Ca2+]i. The Ca2+ ionophore A23187 or bradykinin, which evoked inositol phosphate formation and increases in [Ca2+]i, did not increase, and instead slightly decreased, cAMP content, indicating that ATP-induced cAMP accumulation was not due to activation of Ca(2+)-sensitive adenylyl cyclase. The effect of ATP on cAMP production was not dependent on generation of adenosine caused by ATP hydrolysis. Among several P2 purinoceptor agonists, adenosine-5'-O-(3-thio)triphosphate, 5'-adenylylimidodiphosphate, and adenosine-5'-O-(2-thio)diphosphate evoked both cAMP accumulation and Ca2+ mobilization. In contrast, beta,gamma-methylene-ATP selectively elicited cAMP accumulation, whereas 2-methylthio-ATP and UTP induced only Ca2+ mobilization, without affecting cAMP levels. The potent P2x purinoceptor agonist alpha,beta-methylene-ATP did not induce cAMP accumulation or Ca2+ mobilization. The cAMP accumulation induced by ATP was not affected by the P2 receptor antagonist suramin but was inhibited by P1 receptor antagonists such as 8-(p-sulfophenyl)theophylline, 3-isobutyl-1-methylxanthine, and xanthine amine congener. However, the ATP-induced increase in [Ca2+]i was not affected by suramin or xanthine amine congener. Taken together, these results indicate that ATP activates two distinct purinoceptors that are coupled to different signal transduction systems, one being adenylyl cyclase and the other phospholipase C, in NG108-15 cells. Furthermore, pharmacological profiles of the adenylyl cyclase-coupled receptor were quite different from those of any known purinoceptor subtypes, especially in the unusual sensitivity of the receptor to P1 and P2 receptor agonists and antagonists. It is therefore suggested that ATP-induced cAMP accumulation may be mediated by a novel subtype of purinoceptor in NG108-15 cells.
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PMID:Extracellular ATP stimulates adenylyl cyclase and phospholipase C through distinct purinoceptors in NG108-15 cells. 772 48

Muscarinic receptor in human neuroblastoma SK-N-BE(2)C cells was identified and characterized. Treatment of the cells with carbachol evoked the generation of inositol 1,4,5-trisphosphate (IP3) with a peak level reached at 1 min after stimulation. Carbachol increased intracellular Ca2+ ([Ca2+]i) with an EC50 value of 35 microM. In addition, carbachol produced a 1.3-3-fold increase in the cyclic AMP (cAMP) level compared with untreated control and elevated synergistically the cAMP level in the treatment with prostaglandin E2 (PGE2). The M3 antagonist p-fluorohexahydrosiladifenidol (IC50 = 0.5-0.8 microM) inhibited the increases in [Ca2+]i, IP3, and cAMP more effectively than the M1 antagonist pirenzepine (IC50 = 5-9 microM) and the M2 antagonist methoctramine (IC50 = 20-30 microM). The involvements of [Ca2+]i elevation and protein kinase C activation induced by phospholipase C activation were tested in the carbachol-induced cAMP production. The calcium chelator BAPTA/AM (75 microM) inhibited significantly the synergistic effects of carbachol and PGE2 on the production of cAMP, whereas the Ca2+ ionophore ionomycin (1 microM) clearly enhanced PGE2-induced cAMP production. However, phorbol 12-myristate 13-acetate did not enhance PGE2-stimulated cAMP production. These data suggest that phospholipase C-linked M3 receptors are present and that stimulation of the receptors activates adenylyl cyclase, at least in part, by the Ca(2+)-dependent system in the neuronal cells.
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PMID:Stimulation of adenylyl cyclase mediated by phospholipase C-linked M3 muscarinic receptor in human neuroblastoma SK-N-BE (2) C cells. 776 29

Neuroblastoma NS20Y cells possess a high density of stereoselective delta opioid receptors as determined by competition binding with 3H-diprenorphine and various opioid ligands. Scatchard analysis of [3H]diprenorphine saturation binding data revealed a Kd = 0.79 +/- 0.17 nM and Bmax = 370 +/- 50 fmol/mg protein. These opioid binding sites have highest affinity for delta opioid receptor selective agonists and lowest affinity for mu opioid receptor selective agonists. Agonist binding was sensitive to the presence of the monovalent cation, Na+. Activation of receptor with D-Ala2, D-Leu5-enkephalin (DADLE) resulted in dose-dependent inhibition of forskolin-stimulated intracellular [3H]cAMP accumulation, which was antagonized by (-)-naloxone but not (+)-naloxone. Relative potencies of various opioid agonists to inhibit intracellular cAMP production paralleled those observed in neuroblastoma x glioma NG108-15 hybrid cells. Pretreatment of NS20Y cells with pertussis toxin (PTX) eliminated opioid agonist inhibition of adenylyl cyclase activity. Chronic DADLE treatment resulted in desensitization and down-regulation of opioid receptor. An increase in intracellular [3H]cAMP level above the control was observed in the presence of naloxone after chronic DADLE treatment. Therefore, opioid binding sites in neuroblastoma NS20Y cells possess properties of the classical delta opioid receptor type. After neuroblastoma NS20Y was growth arrested by culturing the cells in serum-free medium for 72 hr, proliferation was reinitiated by addition of fetal calf serum (FCS), 0.01% to 12%, and was monitored by either [3H]thymidine incorporation or by dye viability assay. It was demonstrated that naloxone and naltriben but not Met5-enkephalin could attenuate FCS-induced proliferation in a dose-dependent manner. Naltriben was 54-fold more potent than naloxone to attenuate NS20Y proliferation. The maximal level of viable cells per well was reduced (35.2 +/- 1.9%) with no alteration in FCS concentration-dependent stimulation of growth. Similar inhibition by naloxone (37.3 +/- 2.7%) was observed with [3H]thymidine incorporation studies. This naloxone effect was serum concentration-dependent and could be blocked by culturing NS20Y cells in the presence of both naloxone and Met5-enkephalin. Although pretreatment of NS20Y cells with pertussis toxin could attenuate FCS-stimulated proliferation, naloxone effect on growth was not affected by pertussis toxin pretreatment. Furthermore, the naloxone effect was not NS20Y specific. A similar naloxone effect was observed with neuroblastoma N1E115, although not with neuroblastoma x glioma NG108-15, nor human neuroblastoma SHSY5Y, cell lines that have been reported to contain delta opioid receptors. Therefore, activation of delta opioid receptor could modulate FCS-induced growth in some but not all neuroblastoma cell lines.
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PMID:Properties of delta opioid receptor in neuroblastoma NS20Y: receptor activation and neuroblastoma proliferation. 781 47

Acute ethanol treatment of NG108-15 neuroblastoma x glioma hybrid cells results in inhibition of adenosine uptake with consequent increases in extracellular adenosine and intracellular cAMP concentrations. Chronic exposure to ethanol, however, causes heterologous desensitization of receptors coupled to adenylyl cyclase via stimulatory guanine nucleotide regulatory protein. This heterologous desensitization is correlated with a decrease in the amount of protein and mRNA for the GTP-binding subunit of stimulatory guanine nucleotide regulatory protein. In addition, after chronic exposure to ethanol, the adenosine transporter becomes tolerant to acute ethanol inhibition of adenosine uptake, and there is no longer an increase in extracellular adenosine. We have previously shown that extracellular adenosine is required for the development of ethanol-induced heterologous desensitization. To examine the role of adenosine receptors in mediating these responses to ethanol, we used BW A1434U, an adenosine receptor antagonist that does not inhibit nucleoside transport. BW A1434U caused a concentration-dependent inhibition of (-)-N6-(R-phenyl-isopropyl)-adenosine-stimulated cAMP production in NG108-15 cells. BW A1434U also completely blocked acute ethanol-induced increases in intracellular cAMP levels and prevented the development of ethanol-induced heterologous desensitization and the reduction in the GTP-binding subunit of stimulatory guanine nucleotide regulatory protein. In addition, BW A1434U prevented the development of tolerance to ethanol-induced inhibition of adenosine transport. Our results indicate that in NG108-15 cells, adenosine receptors mediate ethanol-induced changed in cAMP signal transduction and adenosine transport and that an adenosine receptor antagonist can block both these acute and chronic affects of ethanol.
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PMID:Adenosine receptors mediate cellular adaptation to ethanol in NG108-15 cells. 796 54

In our earlier studies we have demonstrated that recombinant human interferon-alpha 2A (rHu-IFN-alpha 2A) inhibits hypothalamo-pituitary-adrenocortical (HPA) secretion following both peripheral and central administration. Furthermore, this effect is antagonized by mu-opioid receptor antagonists, suggesting transduction by this subtype of opioid receptors. In the present studies, we demonstrate that this effect is also observed with the hybrid recombinant preparation, rHu-IFN-alpha A/D, and a leucocyte-derived rat IFN-alpha preparation. The inhibitory effects on HPA activity were observed after intraperitoneal (i.p.) injections of rHu-IFN-alpha 2A (10(3) U), rHu-IFN-alpha A/D (10(4) U), and of Rat-IFN-alpha (1 and 10 U). Similar effects were observed with intracerebroventricular (i.c.v.) administration of all three IFN-alpha preparations. No increases in plasma concentrations of corticosterone were observed with doses of rHu-IFN-alpha A/D up to 10(6) U (i.p.) or 7 x 10(5) U (i.c.v.), but increases were found following i.c.v. administration of high doses of Rat-IFN-alpha (10(3) and 5 x 10(3) U). The inhibitory effects of all of the IFN-alpha preparations tested were antagonized by naloxone, but the stimulatory effects of 5 x 10(3) U Rat-IFN-alpha were not. Injections of rHu-IFN-alpha 2A (10(4) U i.p.) to urethane-anesthetized rats decreased the electrical activity of the majority of hypothalamic paraventricular nucleus neurons tested, including putative corticotropin-releasing factor-secreting neurons antidromically identified as projecting to the median eminence. These electrophysiological data suggest that the decreases in HPA activity evoked by IFN-alpha are mediated by a rapid inhibitory effect at the level of the corticotropin-releasing factor-secreting neurons. The sensitivity of many central nervous system effects of IFN-alpha to mu-receptor antagonists strongly suggests that the cytokine serves as an endogenous opioid agonist arising from the immune system. In support of this hypothesis we have shown that SH-SY5Y human neuroblastoma cells, differentiated with retinoic acid treatment to express predominantly mu-receptors, are sensitive to rHu-IFN-alpha 2A in vitro. This sensitivity took the form of a dose-dependent inhibition of forskolin-stimulated adenylyl cyclase activity. The data yielded an IC50 (95% confidence intervals) value of 7.93 (5.70-11.04) nM for this effect. Neither undifferentiated SH-SY5Y cells nor NG108-15 mouse neuroblastoma x rat glioma hybrid cells (expressing delta-receptors) were affected by rHu-IFN-alpha 2A.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Inhibition of neural and neuroendocrine activity by alpha-interferon: neuroendocrine, electrophysiological, and biochemical studies in the rat. 800 70

In membranes from SH-SY5Y human neuroblastoma cells differentiated with retinoic acid, the mu-selective agonist Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol (DAMGO) inhibited cAMP formation with an IC50 of 26 nM. Two separate antibodies raised against distinct regions of the Go alpha sequence attenuated the effect of DAMGO by 50-60%, whereas antibodies to Gi alpha 1,2 or Gi alpha 3 reduced the mu-opioid signal insignificantly or to a lesser extent. In contrast, inhibition of adenylyl cyclase by the delta-opioid agonist Tyr-D-Pen-Gly-Phe-D-Pen-OH (DPDPE; Pen = penicillamine) was very sensitive to the Gi alpha 1,2 antibody. In membranes from rat brain striatum, coupling of the mu opioid receptor to adenylyl cyclase was also maximally blocked by antibodies to Go alpha. After long-term treatment of the cells with DAMGO, the content of Go alpha was reduced by 26%, whereas the levels of Gi alpha 1,2, Gi alpha 3, and Gs alpha were unaltered. Addition of Go, purified from bovine brain, to membranes from pertussis toxin-treated SH-SY5Y cells restored the inhibition of adenylyl cyclase by DAMGO to 70% of that in toxin-untreated cells. To comparably restore the effect of DPDPE, much higher concentrations of Go were required. By demonstrating mediation of cAMP-dependent signal transduction by Go, these results describe (i) an additional role for this G protein present at a high concentration in brain, (ii) preferential, although not exclusive, interaction of mu and delta opioid receptors with different G protein subtypes in coupling to adenylyl cyclase, and (iii) reduced levels of Go following chronic opioid treatment of SH-SY5Y cells with mu opioids.
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PMID:Go mediates the coupling of the mu opioid receptor to adenylyl cyclase in cloned neural cells and brain. 809 84

Cyclic AMP formation was found to increase in mouse neuroblastoma N18TG2 cells exposed to 5-hydroxytryptamine (5-HT). This response was concentration-dependent with an EC50 value of 0.22 microM. Tryptamine and other tryptamine-related compounds were also agonists in this assay with a rank order of potency of 5-methoxytryptamine > 5-HT > tryptamine > 2-methyl-5-HT > 5-carboxamidotryptamine >> alpha-methyl-5-HT. (D)-Lysergic acid diethylamide and 2-bromo-lysergic acid diethylamide were partial agonists in this system with maximal responses of 44 and 34%, respectively, compared to 5-HT. 5-HT-stimulated cyclic AMP formation was inhibited by clozapine, mianserin and methiothepin with pA2 values of 6.6, 6.5 and 6.4, respectively. Radioligand binding studies using [125I]iodolysergic acid diethylamide revealed a binding site present at a density of 10.4 fmol/mg of protein, with an affinity for the ligand of 1.18 nM. In competition studies this binding site displayed a pharmacology similar to that defined in studies of cyclic AMP formation. The pharmacological profile of this receptor, characterized by both radioligand binding and functional coupling to adenylyl cyclase, does not correspond to that of any of the currently classified subtypes of 5-HT receptor, but is similar to the 5-HT receptor cloned recently from rat striatum and referred to as the 5-HT6 receptor. The N18TG2 cell line represents a useful model system in which this novel 5-HT receptor may be characterized fully.
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PMID:Characterization of a 5-hydroxytryptamine receptor in mouse neuroblastoma N18TG2 cells. 816 32


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