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)

Prion diseases result from conformational alteration of PrPC, a cell surface glycoprotein expressed in brain, spinal cord, and several peripheral tissues, into PrPSc, a protease-resistant isoform that is the principal component of infectious prion particles. Although a great deal is known about the pathogenic role of PrPSc, the physiological function of PrPC has remained a mystery. Several lines of evidence have recently suggested the possibility that PrPC may play a role in the metabolism of copper. To further investigate the interaction of PrPC and copper, we have analyzed the effect of this metal ion on the endocytic trafficking of PrPC in cultured neuroblastoma cells. We report here that copper rapidly and reversibly stimulates endocytosis of PrPC from the cell surface. This effect may be physiologically relevant and suggests the hypothesis that PrPC could serve as a recycling receptor for uptake of copper ions from the extracellular milieu.
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PMID:Copper stimulates endocytosis of the prion protein. 983 73

The biotransformation of nociceptin/orphanin FQ (NOFQ) by enzyme activity isolated from U1690 human lung carcinoma and SH-SY5Y human neuroblastoma cell lines, and from rat brain cortex cells in primary culture was investigated. The identification and quantification of the cleavage products were performed using electrospray ionization mass spectrometry linked to size-exclusion chromatography. The effect of chronic morphine treatment of the cells (5 days) on NOFQ biotransformation was also studied. It was found that major products generated from NOFQ were the amino-terminal peptides N1-9 and N1-13. The pattern of NOFQ biotransformation was quite similar for all three cell cultures. However, different proportions of the formed peptides were noted. The cleavage was inhibited by EDTA, PMSF, Hg2+, Cu2+ and Zn2+. Dynorphin A2-13 inhibited NOFQ cleavage in a manner suggesting competition of the two peptides for the same enzyme. Chronic morphine treatment of the cell cultures resulted in a substantial increase in the enzyme activity, leading to higher levels of the major fragments and accumulation of N1-12 and the shorter peptides N1-5, N1-6. Since the effect of morphine treatment of the cells was blocked by naloxone, it is likely that it was receptor specific. Taken together, the findings suggest that a metallosensitive endopeptidase, the activity of which is increased by chronic morphine treatment of the cells, is responsible for the biotransformation of NOFQ with fragments N1-9 and N1-13 being the major products.
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PMID:Biotransformation of nociceptin/orphanin FQ by enzyme activity from morphine-naive and morphine-treated cell cultures. 1008 6

Pineal and retinal melatonin synthesis is controlled by the enzymatic activity of arylalkylamine N-acetyltransferase (AA-NAT, EC 2.3.1.87), which is regulated by light/dark signals and circadian factors. This enzyme converts serotonin to N-acetylserotonin by the transfer of an acetyl group from acetyl coenzyme A. Endogenous AA-NAT instability during routine purification has made enzyme characterization difficult, but now a stable recombinant protein for AA-NAT has been synthesized to investigate the intrinsic biochemical properties of AA-NAT from a rat pineal cDNA encoding a 205 amino acid, 23 kilodalton protein, by using a glutathione-S-transferase (GST) fusion protein system. Recombinant GST-AA-NAT showed substrate specificity for arylalkylamines and stability at 4 degrees C; however, the enzyme activity was reduced by 40% upon preincubation at 37 degrees C for 2 hr. GST-AA-NAT is preferentially phosphorylated by either cyclic AMP- or cyclic GMP-dependent kinases in vitro, but no detrimental effect was observed on AA-NAT enzymatic activity. Among the metal cations tested in this study, Ca2+, Mg2+, Mn2+, Fe2+, and Co2 showed little or no inhibitory potency, while either 1 mM Zn2+ or 0.1 mM Cu2+ nearly abolished the enzymatic activity. GST-AA-NAT enzyme activity is also inhibited by reagents that are known biochemically to modify thiol groups (N-ethylmaleimide, NEM) and histidine residues (p-chloromercuribenzoate, NBS and diethyl pyrocarbonate, DEPC), suggesting the presence of essential cysteine and histidine moieties. Moreover, preincubation of acetyl CoA completely protects the recombinant AA-NAT from inactivation by NEM and DEPC, indicating that specific cysteine and histidine residues may be at the acetylation site. The conclusion is that the biochemical properties of rat recombinant AA-NAT is similar to the endogenous pineal and retinal AA-NAT with respect to the sensitivity to temperature, metal cations, as well as the thiol modification reagents. These data also suggest that the phosphorylation status of the AA-NAT does not affect enzymatic activity directly, and histidine residues are potentially important residues required for high catalytic activity.
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PMID:Biochemical characterization of recombinant serotonin N-acetyltransferase. 1045 Oct 24

We have investigated the response to oxidative stress in a model system obtained by stable transfection of the human neuroblastoma cell line SH-SY5Y with plasmids directing constitutive expression of either wild-type human Cu,Zn superoxide dismutase or a mutant of this enzyme (H46R) associated with familial amyotrophic lateral sclerosis. We report that expression of mutant H46R Cu,Zn superoxide dismutase induces a selective increase in paraquat sensitivity that is reverted by addition of D-penicillamine. Furthermore, expression of this mutant enzyme affects the activity of the endogenous wild-type enzyme both in basal conditions and in copper overloading experiments. Our data indicate that aberrant metal chemistry of this mutant enzyme is the actual mediator of oxidative stress and that concurrent impairment of the activity of wild-type endogenous enzyme compromises the cell's ability to respond to oxidative stress.
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PMID:Aberrant copper chemistry as a major mediator of oxidative stress in a human cellular model of amyotrophic lateral sclerosis. 1046 9

Effects of the heavy metal chelator N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) were investigated on cytotoxicity in clonal NG108-15 neuroblastoma-glioma hybrid cells. Three min after addition of 100 microM TPEN, cells began to retract their neurites and lose their characteristic multipolar shape; by 3-4 hr of exposure, most cells detached from the substrate, either singly or as variable-sized aggregates. Viability was assessed by monitoring uptake of calcein AM and propidium iodide, fluorescent dyes that served as markers for live and dead cells, respectively. Incubation of cultures in 100 microM TPEN led to a gradual decrease in the population exhibiting calcein fluorescence (viable cells) and a corresponding increase in the population displaying propidium iodide fluorescence (nonviable cells). Loss of cell viability reached 12% at 8 hr, 61% at 24 hr and 83% by 48 hr. Ultrastructural examination of TPEN-treated cells revealed condensed chromatin and fragmented nuclei, characteristic of apoptosis, as well as plasma membrane defects and organelle swelling, generally associated with necrosis. Addition of an equimolar concentration of Zn2+ or Cu2+ but not Fe2+ or Mn2+ prevented morphological abnormalities and cell death.
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PMID:Cytotoxic actions of the heavy metal chelator TPEN on NG108-15 neuroblastoma-glioma cells. 1049 56

Brain cell-free extract greatly stimulates the polymerization rate of purified tubulin with a reduction of the nucleation period and without a significant alteration of the final assembly state. This effect is mimicked by neuroblastoma extract at 10-fold lower extract concentration, but not by excess muscle extract. Copper inhibits microtubule assembly in vitro but in the presence of brain extract the copper effect is suspended. Electron microscopic images showed that intact microtubules are formed and decorated by cytosolic proteins in the absence and presence of copper, while the copper alone induces the formation of S-shaped sheets and oligomeric threads. The flux of triosephosphate formation from glucose is enhanced by microtubules in brain extract, but not in muscle extract. Copper inhibits the glycolytic flux; however, the presence of microtubules not only suspends the inhibition by copper but the activation of glycolysis by microtubules is also preserved. We conclude that the organization of neuronal proteins modifies both the rates of microtubule assembly and glycolysis, and reduces their sensitivities against the inhibition caused by copper.
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PMID:Combined enhancement of microtubule assembly and glucose metabolism in neuronal systems in vitro: decreased sensitivity to copper toxicity. 1052 10

Nitric oxide (NO) challenge to human neuroblastoma cells (SH-SY5Y) ultimately results in apoptosis. Tumor suppressor protein p53 and cell cycle inhibitor p21 accumulate as an early sign of S-nitrosoglutathione-mediated toxicity. Cytochrome c release from mitochondria and caspase 3 activation also occurred. Cells transfected with either wild type (WT) or mutant (G93A) Cu, Zn-superoxide dismutase (Cu,Zn-SOD) produced comparable amounts of nitrite/nitrate but showed different degree of apoptosis. G93A cells were the most affected and WT cells the most protected; however, Cu, Zn-SOD content of these two cell lines was 2-fold the SH-SY5Y cells under both resting and treated conditions. We linked decreased susceptibility of the WT cells to higher and more stable Bcl-2 and decreased reactive oxygen species. Conversely, we linked G93A susceptibility to increased reactive oxygen species production since simultaneous administration of S-nitrosoglutathione and copper chelators protects from apoptosis. Furthermore, G93A cells showed a significant decrease of Bcl-2 expression and, as target of NO-derived radicals, showed lower cytochrome c oxidase activity. These results demonstrate that resistance to NO-mediated apoptosis is strictly related to the level and integrity of Cu,Zn-SOD and that the balance between reactive nitrogen and reactive oxygen species regulates neuroblastoma apoptosis.
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PMID:Cu,Zn-superoxide dismutase-dependent apoptosis induced by nitric oxide in neuronal cells. 1067 49

The peptide-linked copper chelators CPTA-triglycyl-L-p-isothiocyanato-phenylalanine (CPTA-R1-NCS) as well as DOTA-triglycyl-L-p-isocyanato-phenylalanine (DOTA-R1-NCS) were synthesized and coupled to F(ab')2 fragments of the anti-neuroblastoma monoclonal antibody (MAb) chCE7. 67Cu-labeled conjugates were compared with the original CPTA- and DO3A-F(ab')2 in vitro and in vivo in mice bearing neuroblastoma xenografts. With the CPTA-R1-F(ab')2, biodistributions were improved, because radioactivity present in the kidney was reduced. With the DOTA-R1-F(ab')2, clearance from the blood was slower and tumor uptake was higher compared with the other conjugates. DOTA-R1-F(ab')2 achieved the best tumor/tissue ratios.
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PMID:A triglycine linker improves tumor uptake and biodistributions of 67-Cu-labeled anti-neuroblastoma MAb chCE7 F(ab')2 fragments. 1070 9

Ceramide glycanase (CGase) activities have been detected in different human tumor cells (colon, carcinoma Colo-205; neuroblastoma, IMR-32; breast cancer lines, SKBr3 and MCF7). However, the level of enzymatic activity is lower in these cells compared to that present in other mammalian tissues reported before (Basu, M., Kelly, P., Girzadas, M. A., Li, Z., and Basu, S. Methods Enzymol. (in press)). The majority of CGase activity was found in the 100,000 g soluble supernatant fraction isolated from all these cell lines and tissues. Using the soluble enzyme, the requirement for optimum CGase activity was found to be consistent with previous observations found for rat and rabbit tissues (Basu, M., Dastgheib, S., Girzadas, M. A., O'Donnell, P. H., Westervelt, C. W., Li, Z., Inokuchi, J. I., and Basu, S. (1998) Acta Pol. Biochim. 42:327). The CGase activities from both Colo-205 and IMR-32 cells are optimum at a protein to detergent ratio of one. All the mammalian CGases, including human cancer cells, show an optimum pH between 5.5 and 5.8 in sodium acetate buffer. The CGase activities from cancer cells are found to be cation-independent; however, mercury, zinc, and copper ions seem to inhibit the enzyme activity substantially in both tumor cells lines. The mercury ion inhibition of CGase activities from all different sources indicates a possible structural homology in the CGase proteins. Radiolabeled substrates, labeled at the sphingosine double bond or at the 3-position of sphingosine without modifying double bond of sphingosine were used in this investigation. Both were active substrates with all enzyme preparations isolated from different cancer cells (apparent Km, 500 microM for nLcOse5[3H-DT]Cer and 350 microM for GgOse4[sph-3-3H]Cer with Colo-205 enzyme). Structural analogues of ceramide and sphingosine (L-PPMP. L-PDMP, alkylamines, and Tamoxifen) inhibited cancer cell CGase activities in vitro.
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PMID:Ceramide glycanase activities in human cancer cells. 1076 12

Dopamine-beta-hydroxylase (DbetaH) is a copper-containing enzyme that uses molecular oxygen and ascorbate to catalyze the addition of a hydroxyl group on the beta-carbon of dopamine to form norepinephrine. While norepinephrine causes vasoconstriction following reflex sympathetic stimulation, nitric oxide (NO) formation results in vasodilatation via a guanylyl cyclase-dependent mechanism. In this report, we investigated the relationship between NO and DbetaH enzymatic activity. In the initial in vitro experiments, the activity of purified DbetaH was inhibited by the NO donor, diethylamine/NO (DEA/NO), with an IC(50) of 1 mm. The inclusion of either azide or GSH partially restored DbetaH activity, suggesting the involvement of the reactive nitrogen oxide species, N(2)O(3). Treatment of human neuroblastoma cells (SK-N-MC) with diethylamine/NO decreased cellular DbetaH activity without affecting their growth rate and was augmented by the depletion of intracellular GSH. Co-culture of the SK-N-MC cells with interferon-gamma and lipopolysaccharide-activated macrophages, which release NO, also reduced the DbetaH activity in the neuroblastoma cells. Our results are consistent with the hypothesis that nitrosative stress, mediated by N(2)O(3), can result in the inhibition of norepinephrine biosynthesis and may contribute to the regulation of neurotransmission and vasodilatation.
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PMID:Inhibitory effects of nitric oxide and nitrosative stress on dopamine-beta-hydroxylase. 1088 4


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