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)

The relationship between muscarinic receptor-mediated inositol lipid hydrolysis and the generation of Ca2+ signals has been examined in human SK-N-SH neuroblastoma cells. The resting cytoplasmic calcium concentration [( Ca2+]i) as determined by fura-2 fluorescence measurements was 59 +/- 2 nM. Upon the addition of oxotremorine-M, there was a 4-fold increase in [Ca2+]i (293 +/- 18 nM), with half-maximal stimulation obtained at an agonist concentration of 8 microM, a value similar to that previously observed for the enhancement of phosphoinositide hydrolysis. Addition of partial muscarinic agonists for phosphoinositide turnover (bethanechol, oxo-2, and arecoline) elicited correspondingly smaller increases in [Ca2+]i than did oxotremorine-M. Inclusion of EGTA lowered the basal [Ca2+]i within 2 min and markedly reduced (greater than 60%) the magnitude of the agonist-induced rise in [Ca2+]i. Addition of muscarinic agonists to SK-N-SH cells that had been prelabeled with [3H]inositol led to the rapid (5-15 sec) release of inositol mono-, bis-, and triphosphates. When assayed under conditions similar to those employed for the fluorescence measurements, EGTA also inhibited both the basal and oxotremorine-M-stimulated release of inositol phosphates by 45-61%. Conversely, ionomycin both elevated [Ca2+]i and stimulated the release of inositol phosphates. The addition of Ca2+ (10 nM-2 microM) to digitonin-permeabilized cells directly stimulated the release of labeled inositol mono-, bis-, and trisphosphates by 3-4-fold with a half-maximal effect (EC50) observed at 145 nM free Ca2+ (Ca2+f). A further (6-fold) calcium-dependent increase in inositol phosphate release was obtained by inclusion of either guanosine-5-O-(3-thio)-trisphosphate (GTP gamma S) or oxotremorine-M. In the combined presence of agonist and GTP gamma S, a synergistic release of all three inositol phosphates occurred, with half-maximal stimulation observed at 35-40 nM Ca2+f, a value similar to the [Ca2+]i in quiescent cells. These results indicate (i) that the magnitude of the initial rise in [Ca2+]i is directly related to the production of phosphoinositide-derived second messenger molecules and (ii) that the phospholipase C-mediated breakdown of inositol lipids in SK-N-SH cells is particularly sensitive to regulation by physiologically relevant Ca2+ concentrations. It is concluded that, in SK-N-SH cells, either an elevation above or reduction below basal [Ca2+]i can modulate the extent of hydrolysis of inositol lipids and the subsequent generation of calcium signals.
Mol Pharmacol 1989 Feb
PMID:Muscarinic receptor regulation of cytoplasmic Ca2+ concentrations in human SK-N-SH neuroblastoma cells: Ca2+ requirements for phospholipase C activation. 253 57

125I-Bolton Hunter-cholecystokinin octapeptide (BH-CCK8) and (-)-[3H]L-364718 membrane binding assays were used to identify and characterize cholecystokinin (CCK) receptors in CHP212 human neuroblastoma cells. The ligand binding properties of CCK receptors in these cells are similar to those found in pancreas (CCK-A sites) and differ from the predominant type of CCK binding site found in brain (CCK-B sites). The specific binding of 125I-BH-CCK8 but not (-)-[3H]L-364718 was reduced by the metabolically stable GTP analog guanosine 5'-(beta-delta-imido)trisphosphate. A substantial difference in the Bmax for the radiolabeled agonist (125I-BH-CCK8) and antagonist [(-)-[3H]L-364718] was noted. These observations are consistent with CCK receptors existing in guanine nucleotide-binding protein-coupled and -uncoupled states. Similar to its action in pancreatic acinar cells, CCK8(S) stimulated the accumulation of [3H]inositol phosphates in cells prelabeled with [3H]myo-inositol (EC50 = 3.2 +/- 0.4 nM; maximum response = 4.5 +/- 0.4 x basal). The intrinsic activity of CCK analogues in stimulating phosphoinositide hydrolysis was substantially less than their reported intrinsic activity in stimulating phosphoinositide hydrolysis in pancreatic acinar cells. The CHP212 neuroblastoma cell may serve as a useful model for the recently reported CCK-A binding site found in the central nervous system.
Mol Pharmacol 1989 Apr
PMID:Type-A cholecystokinin receptors in CHP212 neuroblastoma cells: evidence for association with G protein and activation of phosphoinositide hydrolysis. 253 54

Regulation of proenkephalin A expression was studied in the human neuroblastoma SK-N-MC cell line with respect to mRNA-level, translation, posttranslational processing of the prohormone and secretion of the processed products into the culture medium. Cells were treated with either norepinephrine (NE), dexamethasone (DEX), dibutyryl-3',5'-cyclic AMP (dbcAMP) or the combination of NE and DEX. In an additional investigation, proenkephalin A mRNA levels were determined after 9 h of treatment with dbcAMP, NE, isoproterenol, NE + propranolol and dbcAMP + DEX. NE or dbcAMP for 1-48 h transiently elevated proenkephalin A mRNA 1.5-4.5 times compared to control. The effect of NE was partially blocked by the beta-adrenoceptor antagonist propranolol and was reproduced by the beta-adrenoceptor agonist isoproterenol, suggesting involvement of the beta-adrenoceptor. DEX alone had no significant effect. However it markedly antagonized the effect of NE but not that of dbcAMP suggesting an action on the beta-adrenoceptor. The intracellular content of Met-enkephalin-Arg6,Phe7 immunoreactivity was increased during drug treatment in parallel with changes in proenkephalin A mRNA. DEX gave no effect. No significant change in the ratio of low versus high molecular weight immunoreactive material could be detected in the cell extracts as determined at different time points. Secretion of immunoreactivity into the culture medium increased 5-fold after 18 h of treatment with NE, whereas dbcAMP gave a 2-fold increase. The proportion of low-molecular weight secreted material increased markedly. DEX alone did not induce any change but inhibited the effect of NE. Apparently, regulation of gene expression, prohormone processing and secretion are coordinated by a cAMP-dependent mechanism.
Brain Res Mol Brain Res 1989 May
PMID:Modulation of proenkephalin A gene expression by cyclic AMP. 254 16

The marine dinoflagellate toxin maitotoxin (MTX) stimulates phosphoinositide breakdown in pheochromocytoma PC12 cells and in neuroblastoma hybrid NCB-20 cells. In both cell lines, the stimulation of phosphoinositide breakdown by MTX is dependent on extracellular calcium, but it is not reduced by organic or inorganic calcium channel blockers. In PC12 cells, the maximal stimulation of phosphoinositide breakdown occurs at 1.5 mM [Ca2+]o, whereas in NCB-20 cells the maximal stimulation is observed at 2.5-4.5 mM [Ca2+]o. Phosphoinositide breakdown is known to lead to formation of both inositol phosphates and diacylglycerols. The latter, through stimulation of protein kinase C, would, like phorbol esters, be expected to augment cyclic AMP accumulation in PC12 cells and to inhibit receptor-mediated cyclic AMP accumulation in NCB-20 cells. MTX does potentiate forskolin-induced accumulation of cyclic AMP in PC12 cells and does inhibit prostaglandin E2-induced accumulation of cyclic AMP in NCB-20 cells. The effects of MTX on accumulation of cyclic AMP are calcium dependent and the concentrations of calcium required for maximal responses are the same as the ones required for maximal stimulation of phosphoinositide breakdown. MTX increases intracellular calcium in both cell lines, as measured by calcium-quin2 fluorescence. But the effects of MTX on forskolin- and prostaglandin E2-mediated cyclic AMP accumulation are not mimicked by a calcium ionophore and are not blocked by nifedipine, a calcium channel blocker. Translocation of protein kinase C occurs after treatment with MTX in both cell lines; the protein kinase C activity and content are reduced in the cytosol and increased in membranes after exposure to either MTX or a phorbol ester. The results confirm previous studies on the heterogeneous input of protein kinase C to cyclic AMP-generating systems performed with phorbol esters and demonstrate the utility of MTX as a unique tool for studies of systems that involve second messengers generated through stimulation of phosphoinositide breakdown.
Mol Pharmacol 1989 Jul
PMID:Calcium-dependent effects of maitotoxin on phosphoinositide breakdown and on cyclic AMP accumulation in PC12 and NCB-20 cells. 254 52

Studies have established that major increases in muscarinic acetylcholine receptor (mAchR) binding in the brain appear to coincide with synaptogenesis. The neuroblastoma x glioma hybrid NG108-15 cell line has been demonstrated to possess numerous functional characteristics of intact neurons, including synapse formation with myotubes. The present study examines and characterizes the mAchR on the hybrid NG108-15 cells during differentiation, induced by 1 mM dBcAMP. Specific binding of [3H]-QNB for differentiated cells increases gradually to a final level of 130% (P less than 0.05) over the control undifferentiated cells during the first 24 hr of incubation. Further, this increase of receptor sites appears to correlate proportionately to the degree of neurite extension of the differentiating cells. The dissociation rate constant at equilibrium (Kd) and maximum binding capacity (Bmax) have been determined to be 5.6 nM and 920 fmol/10(6) cells, respectively, for differentiated cells, and 4.4 nM and 400 fmol/10(6) cells, respectively, for undifferentiated cells. Computer analyses of the data obtained from saturation experiments reveal a single class of binding sites for [3H]-QNB on both differentiated and undifferentiated cells. The Hill plot analysis of the QNB-binding indicates a Hill coefficient (nH) of 1.0 and 0.91 for differentiated and undifferentiated cells, respectively, suggesting the unity of receptor sites with no co-operativity. Our results depict that increases of mAchRs on intact cells correlate with the degree of cellular differentiation.
Mol Cell Biochem 1989 Apr 11
PMID:Characterization of muscarinic acetylcholine receptors on intact neuroblastoma x glioma NG108-15 cell upon induced differentiation. 254 90

Compound BM5 [N-methyl-N(1-methyl-4-pyrrolidino-2-butynyl) acetamide] has previously been described as an agonist at postsynaptic muscarinic receptors and as an antagonist at presynaptic receptors. In the current work, we studied the ability of this compound to selectively stimulate phosphoinositide (PI) turnover in Chinese hamster ovary cells transfected with m1 muscarinic receptors and in SK-N-SH neuroblastoma cells that express only m3 receptors. We also studied the ability of this compound to stimulate adenylate cyclase inhibition in m2 muscarinic receptors from heart tissue and in m4 receptors expressed in NG108-15 cells. BM5 stimulated the two muscarinic receptor subtypes coupled to adenylate cyclase inhibition. In NG108-15 cells, 100 microM BM5 inhibited prostaglandin E1-stimulated cAMP formation by 36 +/- 1.5%, whereas 100 microM of the full agonist oxotremorine-M inhibited cAMP formation by 64.1 +/- 1.9%. The half-maximal concentration for BM5 inhibition of cAMP formation was 0.4 +/- 0.1 microM. In heart membranes, BM5 inhibited isoproterenol-stimulated adenylate cyclase by 24 +/- 2%, whereas oxotremorine inhibited this activity by 34 +/- 3%. In contrast to its activity at these receptor subtypes, BM5 did not stimulate the m1 or m3 receptor subtypes, which couple to PI turnover. In these latter two subtypes, BM5 inhibited oxotremorine-M-stimulated PI turnover with IC50 values of 10-20 microM. Therefore, BM5 is a partial agonist at adenylate cyclase-coupled muscarinic receptor subtypes and is a pure antagonist at PI turnover-coupled muscarinic receptor subtypes. These studies also suggest that, at least in some parts of the brain, postsynaptic muscarinic receptors are coupled to adenylate cyclase, whereas presynaptic muscarinic receptors are coupled to PI turnover.
Mol Pharmacol 1989 Sep
PMID:An agonist that is selective for adenylate cyclase-coupled muscarinic receptors. 255 Jul 80

The abilities of lipophilic cannabinoid drugs to regulate adenylate cyclase activity in neuroblastoma cell membranes were analyzed by thermodynamic studies. Arrhenius plots of hormone-stimulated adenylate cyclase activity exhibited a break point at 20 degrees. The break point was reduced to 14 degrees by benzyl alcohol, consistent with results from other laboratories that have correlated this response with the increase in membrane fluidity induced by benzyl alcohol. Because cannabinoid drugs partition into membrane lipids and alter membrane fluidity parameters in a number of model systems, it was of interest to examine the influence of delta 9-tetrahydrocannabinol and cannabidiol on enzyme activity analyzed by the Arrhenius plot. delta 9-Tetrahydrocannabinol, known to inhibit adenylate cyclase, failed to decrease the transition temperature either at 1 microM or at concentrations exceeding its aqueous solubility (30 microM), suggesting that delta 9-tetrahydrocannabinol could not mimic the effects observed with benzyl alcohol. In contrast, 30 microM cannabidiol, which stimulated enzyme activity slightly, decreased the Arrhenius plot break point to 17.5 degrees. The decrease in the transition temperature in response to benzyl alcohol or cannabidiol was not accompanied by a change in activation energies above or below the transition temperature. delta 9-Tetrahydrocannabinol inhibits adenylate cyclase activity via Gi as does the muscarinic agonist carbachol (Howlett et al., Mol Pharmacol 29: 307-313, 1986). Both carbachol and delta 9-tetrahydrocannabinol decreased the enthalpy and entropy of activation. The net free energy of activation at 37 degrees was increased in the presence of both of these inhibitory agonists. These data suggest that, for the entropy-driven hormone-stimulated adenylate cyclase enzyme, less disorder of the system occurs in the presence of regulators that inhibit the enzyme via Gi. In summary, thermodynamic data suggest that cannabidiol can influence adenylate cyclase by increasing membrane fluidity, but that the inhibition of adenylate cyclase by delta 9-tetrahydrocannabinol is not related to membrane fluidization.
 ...
PMID:Regulation of adenylate cyclase by cannabinoid drugs. Insights based on thermodynamic studies. 255 20

Expression of a multidrug resistance gene (mdr1) and its protein product, P-glycoprotein (Pgp), has been correlated with the onset of multidrug resistance in vitro in human cell lines selected for resistance to chemotherapeutic agents derived from natural products. Expression of this gene has also been observed in normal tissues and human tumors, including neuroblastoma. We therefore examined total RNA prepared from human neuroblastoma cell lines before and after differentiation with retinoic acid or sodium butyrate. An increase in the level of mdr1 mRNA was observed after retinoic acid treatment of four neuroblastoma cell lines, including the SK-N-SH cell line. Western blot (immunoblot) analysis demonstrated concomitant increases in Pgp. However, studies of 3H-vinblastine uptake failed to show a concomitant Pgp-mediated decrease in cytotoxic drug accumulation. To provide evidence that Pgp was localized on the cell surface, an immunotoxin conjugate directed against Pgp was added to cells before and after treatment with retinoic acid. Incorporation of [3H]leucine was decreased by the immunotoxin in the retinoic acid-treated cells compared with the undifferentiated cells. These results demonstrate that whereas expression of the mdr1 gene can be modulated by differentiating agents, increased levels of expression are not necessarily associated with increased cytotoxic drug accumulation.
Mol Cell Biol 1989 Oct
PMID:Expression of a drug resistance gene in human neuroblastoma cell lines: modulation by retinoic acid-induced differentiation. 257 30

The actions of diphenylhydantoin (DPH) and carbamazepine (CBZ) on sodium channels in mouse neuroblastoma cells (clone N18) were analyzed using the patch voltage clamp procedure in the whole cell configuration. DPH and CBZ reduced sodium currents without effect on the voltage dependence of sodium channel activation. Half-maximal inhibition was observed with approximately 30 microM of each drug. Depolarization increased and hyperpolarization reversed channel block by these two drugs in the voltage range from -90 to -45 mV. Repetitive stimulation at 2 Hz or greater enhanced inhibition of sodium channels. The half-time for recovery from voltage-dependent inhibition was greater for DPH (1.36 sec) than for CBZ (0.38 sec). A combination of prolonged depolarizing pulses of 15 mV with superimposed brief maximal depolarizations designed to mimic the electrical activity in an epileptic focus gave additive effects of voltage-dependent and frequency-dependent inhibition. The results support the previous proposal that DPH and CBZ are sodium channel-selective anticonvulsants and provide a potential basis for specific inhibition of neurons in epileptic foci. The mechanism of DPH and CBZ action is considered in terms of an allosteric or modulated receptor model of drug binding and action.
Mol Pharmacol 1985 May
PMID:Voltage clamp analysis of the inhibitory actions of diphenylhydantoin and carbamazepine on voltage-sensitive sodium channels in neuroblastoma cells. 258 Nov 24

Quantitative structure-activity relationships between pharmacological activities and physical properties of a series of 2,2-diphenylpropionate compounds were used to define the topography of the antagonist binding site of muscarinic receptors. XICAMM, a computer molecular modeling program, was used to calculate geometrical and topological values of the compounds. The compounds were tested for their antimuscarinic activities by: (a) inhibition of [N-methyl-3H]scopolamine binding to the muscarinic receptors of N4TG1 neuroblastoma cells, (b) inhibition of carbachol-induced alpha-amylase release from rat pancreas acini, and (c) blocking of acetylcholine-induced contraction of guinea pig ileum. To evaluate as clearly as possible only the effect of the bond distance on the potency of the synthesized antimuscarinics, the compounds contained as many constant features as possible. Neither the hydrophobic nor the ester moieties of the compounds were changed, and the rings containing the protonated nitrogen were saturated and restricted. The antimuscarinic activities obtained from the three assays were significantly correlated with each other, with the exception of two compounds, 9 and 13. The latter two compounds demonstrated specificity for the m3 muscarinic receptor subtype expressed in the pancreas. Furthermore, it was demonstrated that the antimuscarinic activities were significantly related to the bond distances between the carbonyl oxygen (constant electronegative locus) and the protonated nitrogen (center of cationic charge) of the 2,2-diphenylpropionate compounds. Parabolic relationships between the pharmacological activities and bond distances were empirically established. The shortest calculated bond distance of these compounds was approximately 4.4 A, whereas the longest was about 5.9 A. The maximum antimuscarinic potency was observed with a calculated bond distance of about 5.2 A in all three assays.
Mol Pharmacol 1989 Nov
PMID:Distance geometry of alpha-substituted 2,2-diphenylpropionate antimuscarinics. 258 91


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