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)

Human brain tumors (obtained as surgical specimens) and nude mouse-borne human neuroblastomas and gliomas were analyzed for sigma and opioid receptor content. Sigma binding was assessed using [3H]1,3-di-o-tolylguanidine (DTG), whereas opoid receptor subtypes were measured with tritiated forms of the following: mu, [D-ala2,mePhe4,gly-ol5]enkephalin (DAMGE); kappa, ethylketocyclazocine (EKC) or U69,593; delta, [D-pen2,D-pen5]enkephalin (DPDPE) or [D-ala2,D-leu5]enkephalin (DADLE) with mu suppressor present. Binding parameters were estimated by homologous displacement assays followed by analysis using the LIGAND program. Sigma binding was detected in 15 of 16 tumors examined with very high levels (pmol/mg protein) found in a brain metastasis from an adenocarcinoma of lung and a human neuroblastoma (SK-N-MC) passaged in nude mice. kappa opioid receptor binding was detected in 4 of 4 glioblastoma multiforme specimens and 2 of 2 human astrocytoma cell lines tested but not in the other brain tumors analyzed.
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PMID:Sigma and opioid receptors in human brain tumors. 197 2

A 23-kDa (p23k) rat brain protein was stereospecifically eluted from a 14 beta-bromoacetamidomorphine affinity column, purified to apparent homogeneity by reverse phase HPLC, and partially sequenced. Three degenerate oligodeoxynucleotide probes were synthesized based on this partial amino acid sequence. A rat brain cDNA library was screened using these probes, and a full-length cDNA was isolated. The deduced protein, 187 amino acids long, is rich in glutamic and aspartic acid residues, endowing p23k with a net negative charge at neutral pH. The protein lacks a signal sequence as well as any transmembrane domains. Based on predictions of secondary structure, p23k is a globular protein composed of 30% alpha-helices and 18% beta-pleated sheets. Northern blot analysis revealed p23k transcripts in rat brain, liver, and the mouse x rat neuroblastoma-glioma NG108-14 cell line. Although not an opioid receptor itself, this protein may be associated with such a receptor or be related to a protein that has been shown to be cross-linked to the opioid peptide beta-endorphin.
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PMID:Purification, cloning, and tissue distribution of a 23-kDa rat protein isolated by morphine affinity chromatography. 197 48

Chronic opioid treatment of neuroblastoma x glioma NG108-15 cells induces desensitization of the opioid receptor and this may involve a change in membrane protein phosphorylation. In an attempt to mimic this possible mechanism, we studied effects of phorbol ester activation of protein kinase C on opioid receptor activity. Incubation of NG108-15 hybrid cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) abolished up to 45% of opioid inhibition of cyclic AMP accumulation in intact cells, while basal accumulation and prostaglandin E1-stimulated cyclic AMP accumulation were unaltered. This decrease of opioid inhibition was dose- and time-dependent and the potency order of phorbol esters and apparent K activation (90 nM) for TPA were consistent with phorbol esters acting through the stimulation of protein kinase C. TPA also decreased the inhibition of cyclic AMP accumulation mediated through muscarinic and alpha-2 adrenergic receptors. These effects of TPA were best explained by a TPA-induced alteration of the inhibitory nucleotide-binding protein (Gi), the common transducer protein of these receptors. Impairment of Gi by TPA treatment was evidenced by a reduction in agonist-stimulated GTP hydrolysis and activation by GTP. Quantification of Gi by pertussis toxin-catalyzed ADP-ribosylation revealed that TPA decreased maximal labeling. In summary, phorbol esters appeared to attenuate opioid receptor activity by altering the activity of the transducer protein Gi.
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PMID:Attenuation of opioid receptor activity by phorbol esters in neuroblastoma x glioma NG108-15 hybrid cells. 215 50

Mouse neuroblastoma x rat glioma hybrid cells (NG108-15) express an opioid receptor of the delta subclass which both stimulates high-affinity GTPase activity and inhibits adenylate cyclase by interacting with a pertussis-toxin-sensitive guanine-nucleotide-binding protein(s) (G-protein). Four such G-proteins have now been identified without photoreceptor-containing tissues. We have generated anti-peptide antisera against synthetic peptides which correspond to the C-terminal decapeptides of the alpha-subunit of each of these G-proteins and also to the stimulatory G-protein of the adenylate cyclase cascade (Gs). Using these antisera, we demonstrate the expression of three pertussis-toxin-sensitive G-proteins in these cells, which correspond to the products of the Gi2, Gi3 and Go genes, as well as Gs. Gi1, however, is not expressed in detectable amounts. IgG fractions from each of these antisera and from normal rabbit serum were used to attempt to interfere with the interaction of the opioid receptor with the G-protein system by assessing ligand stimulation of high-affinity GTPase activity, inhibition of adenylate cyclase activity and conversion of the receptor to a state which displays reduced affinity for agonists. The IgG fraction from the antiserum (AS7) which specifically identifies Gi2 in these cells attenuated the effects of the opioid receptor. This effect was complete and was not mimicked by any of the other antisera. We conclude that the delta-opioid receptor of these cells interacts directly and specifically with Gi2 to cause inhibition of adenylate cyclase, and that Gi2 represents the true Gi of the adenylate cyclase cascade. The ability to measure alterations in agonist affinity for receptors following the use of specific antisera against a range of G-proteins implies that such techniques should be applicable to investigations of the molecular identity of the G-protein(s) which interacts with any receptor.
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PMID:Delta-opioid-receptor-mediated inhibition of adenylate cyclase is transduced specifically by the guanine-nucleotide-binding protein Gi2. 215 80

Endogenous opioids and opioid receptors (i.e. endogenous opioid systems) are involved in carcinogenesis. Using homogenates of S20Y neuroblastoma (NB) cells grown in culture, the binding of a growth-selective ligand, [Met5]enkephalin, was examined to ascertain the zeta (zeta) opioid receptor. Specific and saturable binding of [3H]-[Met5]enkephalin was detected in NB cells; the data were consistent with a single binding site. Scatchard analysis yielded a Kd of 1.6 nM and a binding capacity (Bmax) of 48.1 fmol/mg protein; 14,000 receptors per cell were estimated. Binding was dependent on protein concentration, time, temperature, and pH, and was sensitive to 100 nM, but not 5 nM, Na+, Ca2+, and Mg2+; GppNHp at concentrations of 100-500 mM had little effect on binding. Optimal binding required protease inhibitors, and pretreatment of the tumor cell homogenates with trypsin markedly reduced [3H]-[Met5]enkephalin binding, suggesting that the binding site was proteinaceous in character. Displacement experiments indicated that [Met5]enkephalin was the most potent displacer of [3H]-[Met5]enkephalin. Cell density (log, confluence, postconfluence) did not alter the Kd or Bmax. This study serves as the first demonstration and characterization of the zeta (zeta) opioid receptor in tissue culture cells. The homogeneous nature of NB cell cultures, along with the enrichment in receptor number, provides an excellent model system to isolate and purify the zeta receptor.
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PMID:Demonstration and characterization of zeta (zeta), a growth-related opioid receptor, in a neuroblastoma cell line. 215 55

Though opioid receptors are more difficult to purify and characterize than other cell surface receptors, significant progress has been made in the past several years. At least a dozen groups have now reported purification of opioid-binding proteins, either in a form that retains ligand-binding properties, or in a covalently bound form. Although there are some discrepancies in the molecular weights of these proteins, it is significant that many investigators have reported a molecular weight of about 60 kd for the receptor, regardless of whether it is of the mu, delta, or kappa type. This finding, together with immunological evidence, suggests that different opioid receptor types may be highly similar, and could conceivably even share a common ligand-binding subunit. Several groups have prepared monoclonal or polyclonal antibodies to purified opioid-binding proteins, which should be useful in mapping the brain regional distribution of the opioid receptors, determining the regions in the peptide involved in ligand binding and association with second messengers, and in determining the relationships among different opioid receptor types. One group has in fact already established an antigenic similarity between a mu-selective opioid-binding protein in mammalian brain, and the delta opioid receptor in NG108-15 neuroblastoma-glioma hybrid cells. One group has reported cloning of the cDNA for a purified opioid-binding protein. Somewhat surprisingly, its predicted amino acid sequence places it in the immunoglobulin superfamily, with strongest homologies to cell-adhesion molecules such as N-CAM. MAG, amalgam and fasciclin II, as well as receptors for peptides such as PDGF and interleukin-6. However, this is consistent with evidence that opioids can modulate cell-cell interactions of monocytes, and provides further support for links between opioids and the immune system. The second messengers mediating opioid actions are still unknown. Opioid agonists affect the activity of adenylate cyclase and ion channels in some tissues, but neither has been shown to mediate opioid analgesia. The sequence homologies of the purified opioid-binding protein OBCAM with tyrosine kinase growth factor receptors suggest additional possibilities for second messengers.
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PMID:Molecular characterization of opioid receptors. 216 Jul 90

Opioid receptors reportedly exist on neuronal tissue of central and peripheral origin as well as on cells of the immune system. Previously, an opioid receptor has been purified from the neuroblastoma x glioma hybrid cell line, NG108-15 cells. In an effort to compare these results with opioid receptors isolated from primary neuronal tissue, we employed a methodology based on the molecular recognition theory to develop a monoclonal antibody which was used to isolate and biochemically characterize murine brain opioid receptors. We herein report the purification of an opioid receptor from mouse brain with a molecular weight of 65,000 daltons (range was 62-70 kD under reducing conditions) using a monoclonal antibody to an (the) opioid receptor. In situ labeling experiments with the delta-class selective opioid receptor affinity ligand, cis-(+)-3-methylfentanylisothiocyanate (SUPERFIT) of brain membrane confirmed these observations. Moreover, SUPERFIT, when coupled to the binding site, could block the recognition of the receptor by the monoclonal antibody. However, the selective, mu-class opioid receptor affinity reagent, 2-(p-ethoxybenzyl)-1-N,N-diethylaminoethyl-5-isothiocyanatobenz imidazole was ineffective at masking the binding site from recognition by the monoclonal antibody. Likewise, opioid-like receptors were purified from murine leukocytes which migrated at a molecular weight of 58,000 daltons under nonreducing conditions and 70,000 daltons under reducing conditions. In addition, immunoaffinity-purified receptor is shown to specifically bind the delta-class-selective opioid ligand, cis-(+)-3-methylfentanylisothiocyanate as well as the endogenous opioid peptides, beta-endorphin and [Met]-enkephalin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Anti-opioid receptor antibody recognition of a binding site on brain and leukocyte opioid receptors. 216 12

Individual G-proteins are highly similar in primary sequence. It is thus pertinent to ask what degree of specificity of interaction each of these display with the various receptors and effector systems. Many of the identified G-proteins are co-expressed in a single tissue or cell. As the extreme C-terminus of the alpha-subunit of each G-protein appears to be a key domain for the interactions of receptors and G-proteins, we have generated a series of G-protein-selective anti-peptide antisera against this region and then have used these antisera to attempt to interfere with receptor-G-protein coupling. With this approach, we have demonstrated that delta-opioid receptor-mediated inhibition of adenylate cyclase in neuroblastoma x glioma (NG108-15) cell membranes is transduced specifically by Gi2 and in the same cell that alpha 2-adrenergic inhibition of Ca2+ currents is transduced by G0.
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PMID:Specificity of interactions of receptors and effectors with GTP-binding proteins in native membranes. 217 90

In previous studies, we have demonstrated that chronic treatment of rats with either etorphine or D-Ala2, D-Leu5-enkephalin (DADLE) resulted in the reduction of opioid receptor binding activities during the course of tolerance development. In both cases, mu-opioid receptor binding capacity was attenuated together with the delta-opioid receptor binding capacity. Because both etorphine and DADLE are relatively non-specific opioid ligands, interacting with both mu and delta receptors, these studies could not determine whether down-regulation of a specific receptor type is possible. Therefore, in the current studies, animals were rendered tolerant to the mu-opioid receptor-selective ligand PL017 and the receptor binding capacity was measured afterwards. Treating Sprague-Dawley rats with increasing doses of PL017 (2.5-20 micrograms/kg) i.c.v. for 5 days resulted in a 30- to 40-fold increase in the AD50 of the peptide to elicit the antinociceptive response and about 14-fold increase in the ED50 of the peptide to elicit the catatonic effect. When mu- and delta-binding was determined using [3H]diprenorphine in the presence of morphiceptin or DPDPE respectively, a significant decrease (20-30%) in the mu-opioid receptor binding but not in delta-opioid receptor binding was observed in all the brain areas tested after 5 days of PL017 treatment. Scatchard analysis of the [3H]DAMGO saturation binding data revealed a decrease in Bmax values and no change in the Kd values. Hence, mu-opioid receptors can be specifically regulated by ligand in the brain as delta-receptors are in neuroblastoma x glioma NG 108-15 cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Decrease in mu-opioid receptor binding capacity in rat brain after chronic PL017 treatment. 217 41

Endogenous opioids play a role in carcinogenic events by serving as inhibitory growth factors that alter cell proliferative events by interaction with opioid receptors. The present study addresses the question of whether endogenous opioid systems function tonically in tissue culture. Using S20Y neuroblastoma, a cell line that produces a growth-related opioid peptide (i.e.[Met5]enkephalin) and contains the zeta receptor known to be associated with growth, the effects of opioid receptor blockade by naltrexone, a potent opioid antagonist, was examined. Drug concentrations of 10(-4) to 10(-8) M naltrexone stimulated cell proliferation, with 32-86% more cells found in the naltrexone groups than control from 12 to 48 h after initiating drug exposure; drug concentrations of 10(-9) to 10(-13) M had no effect on growth. Evaluation of labeling and mitotic indices revealed that both DNA synthesis and mitosis were increased by naltrexone, as were the number of cells with process lengths greater than 40 microns. Naltrexone (10(-6) M) also stimulated the growth of N115 murine neuroblastoma, SK-N-MC human neuroblastoma, and HT-1080 human fibrosarcoma. These results indicate that endogenous opioids function in vitro to regulate growth by inhibitory mechanisms, and do so actively. This autocrine mechanism in tissue culture also occurs in other animal neuroblastoma cell lines, as well as for human neuroblastoma and fibrosarcoma cell lines.
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PMID:Opioid antagonist (naltrexone) stimulation of cell proliferation in human and animal neuroblastoma and human fibrosarcoma cells in culture. 224 94


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