Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The toxic effects of physostigmine, an anticholinesterase drug, and its metabolite eseroline were investigated in three neuronal cell culture systems, mouse neuroblastoma N1E-115, rat glioma C6, and neuroblastoma-glioma hybrid NG 108-15. Physostigmine and eseroline (0.5 nM) elicited a time-dependent leakage of lactic acid dehydrogenase (LDH) from all three cell types. An increased release of [14C]adenine nucleotides was also detected from cells when they were prelabeled with [14C]adenine. Eseroline was comparatively more toxic than the parent compound, physostigmine. Eseroline elicited a dose- and time-dependent leakage of LDH and release of adenine nucleotides from the neuronal cells. A nonneuronal cell line, rat liver ARL-15, was comparatively the most resistant cell type to eseroline toxicity. The concentrations of eseroline needed for 50% release of adenine nucleotides or 50% leakage of LDH from NG-108-15 and N1E-115 cells in 24 hr ranged from 40 to 75 microM. The concentrations of eseroline needed to obtain similar responses in C6 and ARL-15 cells were much higher and ranged from 80 to 120 microM. Phase contrast microscopy showed extensive damage to three neuronal cell lines at concentrations of eseroline as low as 75 microM. The loss of ATP from N1E-115 cells exceeded 50% when they were treated with 0.3 mM eseroline for 1 hr--at which time the leakage of LDH was not detectable. It seems that eseroline causes neuronal cell death by a mechanism involving loss of cell ATP. Thus, the formation of eseroline may contribute to the toxic effect of physostigmine.
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PMID:Eseroline, a metabolite of physostigmine, induces neuronal cell death. 225 81

As assessed both by cholera-toxin-catalysed ADP-ribosylation and by immunoblotting with an anti-peptide antiserum raised against the C-terminal decapeptide of forms of Gs alpha (the alpha subunit of the stimulatory guanine nucleotide-binding protein), rat glioma C6 BU1 cells express two forms of Gs alpha: a major 44 kDa form and a much less prevalent 42 kDa form. We examined the effects of guanine nucleotides on the interaction of the 44 kDa form with the plasma membrane. Incubation of membranes of C6 BU1 cells with poorly hydrolysed analogues of GTP, but not with analogues of either ATP or GDP, caused the release of this Gs alpha from the membrane fraction. Release of Gs alpha was observed within 5 min, and continued throughout the incubation period. After treatment with guanosine 5'-[beta gamma-imido]triphosphate for 60 min, some 75% of this polypeptide had been released from its site of membrane attachment. These experiments demonstrate that Gs alpha need not remain associated invariantly with the plasma membrane.
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PMID:Persistent activation of the alpha subunit of Gs promotes its removal from the plasma membrane. 250 50

The susceptibility of purified protein kinase C to oxidative inactivation by H2O2 was found to be increased by Ca2+ either alone at a high (5 mM) concentration or at a low (approximately 50 microM) concentration along with phosphatidylserine and diacylglycerol and by tumor-promoting phorbol esters even in the absence of Ca2+. This suggested that the membrane-bound and/or catalytically active form of protein kinase C is relatively more susceptible to oxidative inactivation. Although both the regulatory and catalytic domains of protein kinase C were susceptible to oxidative inactivation, a selective modification of the regulatory domain was obtained under mild oxidative conditions by protecting the catalytic site with ATP/Mg2+. Under these conditions there was a loss of both phorbol ester binding and Ca2+/phospholipid-stimulated kinase activity. However, this modified form of enzyme exhibited an increase in Ca2+/phospholipid-independent kinase activity. This suggests that selective oxidative modification of the regulatory domain may negate the requirement for Ca2+ and lipids for activation. Treatment of intact C6 glioma or B16 melanoma cells with H2O2 resulted in a time- and temperature-dependent decrease in Ca2+/phospholipid-dependent protein kinase C activity along with a concomitant transient increase in an oxidatively modified isoform of protein kinase C that exhibited activity in the absence of Ca2+ and phospholipids. Since protein kinase C can initially be activated by mild oxidative modification and subsequently inactivated by further oxidation, this dual activation-inactivation of protein kinase C in response to H2O2 suggests an effective on/off signal mechanism to influence cellular events.
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PMID:Ca2+- and phospholipid-independent activation of protein kinase C by selective oxidative modification of the regulatory domain. 250 61

The effect of GTP on Ca2+ uptake and release was studied in a microsomal fraction isolated from neuroblastoma x glioma hybrid NG108-15 cells. GTP did not alter the ATP-dependent initial uptake of Ca2+ but markedly enhanced the efflux of Ca2+ from microsomes. GTP-dependent Ca2+ release requires the presence of millimolar concentration of Mg2+. The effect of GTP was not mimicked by other nucleotides and was competitively blocked by the thiophosphate analogue of GTP, GTP gamma S but not by the non-hydrolyzable nucleotide GMP-PNP. Addition of an inhibiting concentration of GTP gamma S after completion of GTP-induced calcium release did not result in a re-uptake of Ca2+, showing the irreversibility of the releasing effect of GTP. Our data are consistent with the hypothesis of Ca2+-dependent GTP-induced opening of a channel responsible for vectorial transport of Ca2+ ions from one intracellular compartment to another. A model is proposed suggesting that the GTP-binding protein is a GTP-specific diacylglycerol kinase.
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PMID:Evidence for a GTP-dependent increase in membrane permeability for calcium in NG108-15 microsomes. 251 40

A type II calcium/calmodulin-dependent protein kinase (CaM kinase II) was purified approximately 300-fold from cultured neuroblastoma/glioma (NG108) cell homogenate. The purification of the kinase, which used a combination of differential centrifugation and chromatography on cation-exchange, calmodulin-affinity, and gel-filtration resins, was monitored by the ability of the kinase to phosphorylate the high-molecular-weight microtubule-associated protein 2 (MAP-2). The kinase was compared with authentic CaM kinase II purified from rat brain cytosol. Based upon holoenzyme molecular weight, subunit composition and molecular weight, calcium-dependent calmodulin-binding to subunits, calcium/calmodulin-dependent autophosphorylation of subunits, substrate specificity, apparent km's for ATP and calmodulin, phosphopeptide maps of subunits, time course, and heat lability, the kinase was identified as a type II calcium/calmodulin-dependent protein kinase. When cellular differentiation was induced under specific conditions of cell culture, a significant increase in the apparent activity and amount of the kinase per mg protein was observed relative to control cells. These studies suggest that there is an increase in CaM kinase II expression during cellular differentiation, which may relate to the concurrent development of electrical excitability, synaptogenesis, and elaboration of cytoskeletal elements. Thus, the NG108 cell should provide a useful model to study the physiological functions of CaM kinase II.
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PMID:Differentiation increases type II calmodulin-dependent protein kinase in the neuroblastoma/glioma cell line 108CC15 (NG108-15). 253 90

When added to intact C6 glioma cells in the micromolar range of concentrations, ADP and ATP induce an inhibition of the isoproterenol-elicited cAMP responses. ATP is rapidly hydrolyzed by the ectonucleotidases present on these cells, with an apparent Km of 50 microM and a Vmax of 1.1 nmol/min/10(6) cells. cAMP responses are also inhibited by millimolar concentrations of either ATP in the presence of an ATP-regenerating system to prevent ADP accumulation or AMP-PCP. These observations show that, in C6 glioma cells, ADP is a more potent inhibitor of cAMP production than ATP, the latter acting indirectly, via its rapid hydrolysis to ADP. The additive inhibition of isoproterenol-elicited cAMP responses induced, on one hand, by the treatment of the cells with a phorbol ester and by addition of ADP to the cells, and, on the other hand, by the progressive disappearance of the effects of ADP and ATP when cells are treated with increasing concentrations of Pertussis toxin, demonstrate that ADP and ATP exert their action in C6 glioma cells via a P2 purinoceptor probably negatively coupled to adenylate cyclase and a G regulatory protein.
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PMID:ADP and, indirectly, ATP are potent inhibitors of cAMP production in intact isoproterenol-stimulated C6 glioma cells. 255 Dec 69

The aim of this work was to determine if the total (Na+ + K+)-ATPase of the plasma membrane of a cell population could be assayed without cell homogenization and partial purification of the enzyme. Several types of intact cells that were placed in an assay medium containing MgATP, Na+, and K+ hydrolyzed little or none of the added ATP. When the cells were pretreated with the ionophore alamethicin and then placed in the assay medium, they exhibited an ouabain-sensitive (Na+ + K+)-ATPase activity that increased and reached a limiting value with increasing alamethicin concentration. Since alamethicin did not increase the activity of the purified membrane-bound (Na+ + K+)-ATPase, its effects on the intact cells are probably due to the formation of large channels within the plasma membrane that allow the free access of the components of the assay medium to the intracellular domains of (Na+ + K+)-ATPase. Utilizing whole cells treated with alamethicin, total (Na+ + K+)-ATPase activity was determined in clonal pheochromocytoma cells (PC12), neuroblastoma x glioma hybrid cells (NG108-15), and myocytes isolated from adult and neonatal rat hearts. With the use of this whole-cell assay, the ouabain sensitivities of the enzymes in adult and neonatal rat heart myocytes were determined and found to be the same as those that have been determined with the use of partially purified enzymes.
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PMID:Determination of total (Na+ + K+)-ATPase activity of isolated or cultured cells. 256 Mar 48

It is known that nerve growth factor (NGF) induces neurite outgrowth and elevation of the activity of adrenergic marker enzyme, tyrosine hydroxylase (TH) in clonal rat pheochromocytoma cells (PC12), whereas glioma-conditioned medium (GCM) induces neurite outgrowth and elevation of the activity of cholinergic marker enzyme, choline acetyltransferase (ChAT) in PC12 cells. In the previous study we have shown that retinoic acid (RA) induces specific elevation of ChAT activity and depression of TH activity without morphological differentiation (Matsuoka, I. et al., Brain Res., 502 (1989]. In the present study, we compared the effects of NGF, GCM and RA on the intracellular signalings in PC12 cells in relation to the mechanism of cholinergic differentiation. Addition of NGF, GCM or RA to the culture medium of PC12 cells caused a rapid rise in intracellular Ca2+ concentration [( Ca2+]i) reaching the level of almost 2.5-fold the resting condition within 3-18 h. Thereafter, [Ca2+]i of NGF-treated cells were decreased to the resting level within 12 h. On the other hand, [Ca2+]i of GCM-and RA-treated cells decreased to a level which was 1.8- to 2-fold the resting condition within 24-48 h and stayed at this level for up to 4-7 days. When homogenates of GCM- and RA-treated PC12 cells were incubated with [gamma-32P]ATP, phosphorylation of a protein with molecular mass of 27 kDa (27 K-protein) was specifically enhanced. The phosphorylation of the 27 K-protein was not seen in the homogenate of the NGF-treated cells. The phosphorylation of the 27 K-protein was dependent on Ca2+ and inhibited by inhibitors of Ca2+-dependent protein kinase, H-7 and W-7. Addition of H-7 and W-7 to the culture medium of PC12 cells abolished the elevation of ChAT activity specifically induced by GCM and RA. These observations suggested that the sustained increase of [Ca2+]i and Ca2+-dependent protein phosphorylation are involved in the intracellular signaling mechanism required for the cholinergic differentiation of PC12 cells induced by GCM and RA.
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PMID:Possible involvements of intracellular Ca2+ and Ca2+ -dependent protein phosphorylation in cholinergic differentiation of clonal rat pheochromocytoma cells (PC12) induced by glioma-conditioned medium and retinoic acid. 258

DNA damaging agents such as nitrosoureas are widely used for the treatment of malignant gliomas. Therefore, quantitative measurement of DNA damages induced by antineoplastic drugs is useful to judge the efficacy of the drug and understand the pharmacological action of the drug. We have utilized in situ nick translation method to demonstrate "nicks" in DNA of glioma cells treated by various antineoplastic agents. Exponentially growing rat 9 L glioma cells (4 x 10(4] were seeded in the chamber slide. After fourty eight hours, the medium was changed to that containing various concentration of the drug (ACNU, cis-DDP, BLM, ADM and VP-16) and the cell was treated for 1 hour. Then, the cell was fixed for 10 minutes in methanol-acetic acid (v/v 3:1). Following fixation, the cell was incubated in the nick translation mixture containing E. coli DNA polymerase I, 3H-TTP, and 4 dNTP's (ATP, GTP, CTP, CTP and TTP) for 10 minutes at room temperature. The slide was dipped in the autoradiographic emulsion, exposed for 4 days at 4 degrees C, and then developed, the number of the silver grains over nuclei was counted under the microscope. For comparison of the effect of the drug to glioma cells, IC50 (inhibitory concentration of the drug for 50% cell kill) of each drug was determined by treating the cell for 48 hours at the various concentration of the drug. Small number of the silver grains was noted in cells with no treatment. Over IC50 as the concentration of the drug increased, the number of the nick increased in cells treated with bleomycin or adriamycin which are known to produce single strand breaks in DNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[In situ nick translation for detection of DNA damages in glioma cells]. 262 7

Mitochondrially bound hexokinase (ATP-D-hexose-6-phosphotransferase; EC 2.7.1.1) was dissociatively extracted from normal rat brains and intracerebral and subcutaneous implants of the 36B-10 glioma. At least 70% of the total hexokinase enzyme activity in normal and glioma tissue was associated with the mitochondrial fraction. Purification of the crude tissue extracts by ion-exchange and affinity chromatography followed by analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a successive purification of the enzyme to homogeneity with a molecular size of 98 kilodaltons. Enzyme kinetics with glucose or 2-deoxyglucose (2-DG) as the substrate were measured spectrophotometrically by coupling the appropriate reactions to either NADPH or NAD+ formation. The Km of hexokinase with glucose as the substrate in the intracerebral glioma (0.138 mM) and subcutaneous glioma (0.183 mM) tissues was 2.1-2.7-fold higher than that observed in normal brain tissue (0.067 mM) (p less than 0.001). No significant differences were observed in the Km for hexokinase with 2-DG as the substrate in the glioma and normal brain tissue. The phosphorylation ratio for normal brain was 0.320 and was increased in the intracerebral glioma to 0.694 and in the subcutaneous glioma to 0.519. The ratios of deoxyglucose and glucose volumes of distribution in normal brain and intracerebral glioma tissues were 1.70 and 1.85, respectively. The lumped constants calculated directly from the phosphorylation ratios and the volumes of distribution of deoxyglucose and glucose were 0.517 in normal brain and 1.168 in intracerebral glioma. Our results indicate the lumped constant is increased 2.26-fold in intracerebral glioma compared with normal brain.
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PMID:Determination of the deoxyglucose and glucose phosphorylation ratio and the lumped constant in rat brain and a transplantable rat glioma. 272 62


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