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

Oxidative stress is known to induce cell death in a wide variety of cell types, apparently by modulating intracellular signaling pathways. Activation of extracellular signal-regulated kinase (ERK) in oxidative stress remains controversial. In some cellular systems, the ERK activation is associated with protection against oxidative stress, while in other system, the ERK activation is involved in apoptotic cell death. The present study was undertaken to examine the role of ERK activation in H2O2-induced cell death of human glioma (A172) cells. H2O2 resulted in a time- and dose-dependent cell death, which was largely attributed to apoptosis. H2O2 treatment caused marked sustained activation of ERK. The ERK activation and cell death induced by H2O2 was prevented by catalase, the hydrogen peroxide scavenger, and U0126, an inhibitor of ERK upstream kinase MEK1/2. Transient transfection with constitutive active MEK1, an upstream activator of ERK1/2, increased H2O2-induced cell death, whereas transfection with dominant-negative mutants of MEK1 decreased the cell death. The ERK activation and cell death caused by H2O2 was inhibited by antioxidants (N-acetylcysteine and trolox), Ras inhibitor, and suramin. H2O2 produced depolarization of mitochondrial membrane potential and its effect was prevented by catalase and U0126. Taken together, these findings suggest that growth factor receptor/Ras/MEK/ERK signaling pathway plays an active role in mediating H2O2-induced apoptosis of human glioma cells and functions upstream of mitochondria-dependent pathway to initiate the apoptotic signal.
 ...
PMID:Role of ERK in hydrogen peroxide-induced cell death of human glioma cells. 1589 30

n-3 polyunsaturated fatty acids (PUFAs) have been described to have beneficial effects on brain development and in the prevention and treatment of brain damage. C6 glioma cells were incubated with 100 microM of either C20:4n-6 (ARA), or C20:5n-3 (EPA), or C22:6n-3 (DHA) for different time periods to assess whether these acids altered the cellular oxidative state. The ARA and EPA were promptly metabolised to C22:4n-6 and C22:5n-3, respectively, whereas DHA treatment simply increased the amount of DHA in the cells. Cell viability was not affected by ARA, while a cytotoxic effect was observed 72 h after n-3 PUFAs supplementation. The levels of reactive oxygen species and thiobarbituric acid-reactive substances were significantly higher in DHA-treated cells than in EPA- and ARA-treated groups. This modification in the oxidative cellular status was also highlighted by a significant increase in catalase activity and a decrease in glutathione content in DHA-supplemented cells. Glucose-6-phosphate dehydrogenase activity, an enzyme involved in redox regulation, and O2*- release were significantly increased both in EPA and DHA groups. The effect of DHA was more severe than that of EPA. No significant changes were observed in the ARA group with respect to untreated cells. These data show that EPA and DHA induce alterations in the oxidative status that could affect the glial function.
 ...
PMID:Effect of arachidonic, eicosapentaenoic and docosahexaenoic acids on the oxidative status of C6 glioma cells. 1603 67

Salicylate and jasmonates are two different types of plant hormone that play critical roles in plant defense responses against insect herbivores and microbial pathogens, through activating defense genes. These two natural products have been shown to have similar activities in animal cells: the compounds are able to induce cell cycle arrest or apoptosis in a variety of human cancer cells including those of colon, prostate, breast, and leukemia, suggesting the chemicals may potentially be a novel class of anti-cancer drugs. Since sodium salicylate can induce the heat shock response in animals, we examined the effects of jasmonates on the heat shock response in C6 glioma cells. Here, we show that brief exposure to methyl jasmonate (MeJA), but not to jasmonic acid, induces heat shock protein 72 (HSP72), but not HSP73 and HSP90, via heat shock factor I (HSF1) activation in C6 glioma cells without affecting cell viability. Intracellular H2O2 and O2-, and mitochondrial ROS were prominently increased in response to 5 mM MeJA in C6 cells. MeJA-induced HSP72 expression, HSF1 DNA binding, and human HSP70 promoter-driven CAT activity were prevented by N-acetyl-L-cysteine (a general antioxidant), catalase (a specific antioxidant for H2O2), and sodium formate (an inhibitor of OH.), but not by Rac1 dominant negative mutant Rac1N17 and diphenyleneiodonium (a NADPH oxidase inhibitor), indicating that MeJA induces HSP72 expression though HSF1 that is activated via Rac1-NADPH oxidase-independent ROS production pathway. These results suggest that the plant stress hormones share the ability to induce heat shock response in animal cells.
 ...
PMID:Induction of heat shock protein 72 in C6 glioma cells by methyl jasmonate through ROS-dependent heat shock factor 1 activation. 1621 Dec 52

Maple syrup urine disease (MSUD) is an inherited neurometabolic disorder biochemically characterized by the accumulation of the branched-chain alpha-keto acids (BCKA) alpha-ketoisocaproic (KIC), alpha-keto-beta-methylvaleric (KMV) and alpha-ketoisovaleric (KIV) and their respective branched-chain alpha-amino acids in body fluids and tissues. Affected MSUD patients have predominantly neurological features, including cerebral edema and atrophy whose pathophysiology is not well established. In the present study we investigated the effects of KIC, KMV and KIV on cell morphology, cytoskeleton reorganization, actin immunocontent and on various parameters of oxidative stress, namely total antioxidant reactivity (TAR), glutathione (GSH) and nitric oxide concentrations, and on the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) in C6 glioma cells. We initially observed that C6 cultivated cells exposed for 3 h to the BCKA (1 and 10 mM) changed their usual rounded morphology to a fusiform or process-bearing cell appearance, while 24 h exposure to these organic acids elicited massive cell death. Rhodamine-labelled phalloidin analysis revealed that these organic acids induced reorganization of the actin cytoskeleton with no modifications on total actin content. It was also observed that 3h cell exposure to low doses of all BCKA (1 mM) resulted in a marked reduction of the non-enzymatic antioxidant defenses, as determined by TAR and GSH measurements. In addition, KIC provoked a reduced activity of SOD and GPx, whereas KMV caused a diminution of SOD activity. In contrast, CAT activity was not modified by the metabolites. Furthermore, nitric oxide production was significantly increased by all BCKA. Finally, we observed that the morphological features caused by BCKA on C6 cells were prevented by the use of the antioxidants GSH (1.0 mM), alpha-tocopherol (trolox; 10 microM) and Nomega-nitro-L-arginine methyl ester (L-NAME; 500 microM). These results strongly indicate that oxidative stress might be involved in the cell morphological alterations and death, as well as in the cytoskeletal reorganization elicited by the BCKA. It is presumed that these findings are possibly implicated in the neuropathological features observed in patients affected by MSUD.
 ...
PMID:Morphological alterations and induction of oxidative stress in glial cells caused by the branched-chain alpha-keto acids accumulating in maple syrup urine disease. 1682 90

Molecular and genetic signatures may predict brain tumor behavior and may soon guide tumor classification, diagnosis, and tumor-specific treatment strategies. Free oxygen radicals (FOR) are thought to take part in oncogenesis and cellular differentiation. This article explored the state of FORs and antioxidant system in patients with cerebral tumor. The serum concentrations of malondialdehyde (MDA), catalase, and glutathione peroxidase (GSH-Px) enzyme activities were measured in the serum of 35 patients with cerebral tumors (21 glioma, 14 meningioma) and 11 controls. MDA measurement was done with fluorometric method and catalase and GSH-Px enzyme activities were done with photometric method. Mean serum MDA levels, catalase, and GSH-Px enzyme activities were significantly higher for both glial and meningiomal tumor cases when compared to controls (p < .05). There is no significant difference between glioma and meningioma groups in terms of the aforementioned parameters (p > .05). In conclusion, lipid peroxidation and antioxidant enzymes as assessed by MDA, catalase, and GSH-Px were increased in patients with brain tumors, for this respect there is no difference between gliomas and meningiomas.
 ...
PMID:Lipid peroxidation in patients with brain tumor. 1686 Nov 59

Gliomas are extremely resistant to anticancer therapies resulting in poor patient survival, due, in part, to altered expression of antioxidant enzymes. The primary antioxidant enzyme, catalase, is elevated constitutively in gliomas compared to normal astrocytes. We hypothesized that downregulating catalase in glioma cells would sensitize these cells to oxidative stress. To test this hypothesis, we implemented two approaches. The first, a pharmacological approach, used 3-amino-1,2,4-triazole, an irreversible inhibitor that reduced catalase enzymatic activity by 75%. Pharmacological inhibition of catalase was not associated with a reduction in rat 36B10 glioma cell viability until the cells were challenged with additional oxidative stress, i.e., ionizing radiation or hydrogen peroxide (H(2)O(2)). In the second molecular approach, we generated 36B10 glioma cells stably expressing catalase shRNA; a stable cell line displayed a 75% reduction in catalase immunoreactive protein and enzymatic activity. This was accompanied by an increase in intracellular reactive oxygen species and extracellular H(2)O(2). These cells exhibited increased sensitivity to radiation and H(2)O(2), which was rescued by the antioxidant, N-acetylcysteine. These results support the hypothesis that catalase is a major participant in the defense of 36B10 glioma cells against oxidative stress mediated by anticancer agents capable of increasing steady-state levels of H(2)O(2).
 ...
PMID:Inhibiting catalase activity sensitizes 36B10 rat glioma cells to oxidative stress. 1732 Jul 61

Malignant gliomas are resistant to various proapoptotic therapies, such as radiotherapy and conventional chemotherapy. In this study, we show that selenite is preferentially cytotoxic to various human glioma cells over normal astrocytes via autophagic cell death. Overexpression of Akt, survivin, XIAP, Bcl-2, or Bcl-xL failed to block selenite-induced cell death, suggesting that selenite treatment may offer a potential therapeutic strategy against malignant gliomas with apoptotic defects. Before selenite-induced cell death in glioma cells, disruption of the mitochondrial cristae, loss of mitochondrial membrane potential, and subsequent entrapment of disorganized mitochondria within autophagosomes or autophagolysosomes along with degradation of mitochondrial proteins were noted, showing that selenite induces autophagy in which mitochondria serve as the main target. At the early phase of selenite treatment, high levels of superoxide anion were generated and overexpression of copper/zinc superoxide dismutase or manganese superoxide dismutase, but not catalase, significantly blocked selenite-induced mitochondrial damage and subsequent autophagic cell death. Furthermore, treatment with diquat, a superoxide generator, induced autophagic cell death in glioma cells. Taken together, our study clearly shows that superoxide anion generated by selenite triggers mitochondrial damage and subsequent mitophagy, leading to irreversible cell death in glioma cells.
 ...
PMID:Sodium selenite induces superoxide-mediated mitochondrial damage and subsequent autophagic cell death in malignant glioma cells. 1761 90

Gliomas represent 50% of primary brain tumors, and their prognosis remains poor despite the advances in diagnosis and therapeutic strategies. Low grade gliomas (LGG) are infiltrative tumors and they constantly undergo malignant transformation. Metabolic exploration of human gliomas in vivo, in animals and by using cell culture models showed important differences between tumor tissues and normal brain tissues, which can provide new markers for diagnosis, prognosis and therapeutic targets. In this study, energetic and oxidant metabolisms were explored in biopsy extracts of LGG obtained from the centre and the periphery of tumors. Metabolic pattern of these tumors was explored and the differences between the centre and the periphery pointed. Our study showed a metabolic heterogeneity between tumors, with hypermetabolic and hypometabolic profiles. Lactate to pyruvate ratio was>1, suggesting that the energy metabolism in LGG is glycolytic in nature, particularly in the centre of the tumors. Peripheral samples of tumors showed increased glucose consumption and cytochrome c oxidase activity. Lipid peroxidation and catalase activity were also increased in the periphery compared to the centre of tumors. A relationship between the main antioxidant and energy metabolism enzymes activities was observed, suggesting that periphery of tumors is more active metabolically and more resistant to free radical injury.
 ...
PMID:[Biochemical exploration of energetic metabolism and oxidative stress in low grade gliomas: central and peripheral tumor tissue analysis]. 1839 Apr 24

Oxidative stress is implicated in a variety of disorders including neurodegenerative diseases, and H(2)O(2) is important in the generation of reactive oxygen and oxidative stress. In this study, we have examined the rate of extracellular H(2)O(2) elimination and relevant enzyme activities in cultured astrocytes and C6 glioma cells and have analyzed the results based on a mathematical model. As compared with other types of cultured cells, astrocytes showed higher activity of glutathione peroxidase (GPx) but lower activities for GSH recycling. C6 cells showed relatively low GPx activity, and treatment of C6 cells with dibutyryl-cAMP, which induces astrocytic differentiation, increased catalase activity and H(2)O(2) permeation rate but exerted little effect on other enzyme activities. A mathematical model [N. Makino, K. Sasaki, N. Hashida, Y. Sakakura, A metabolic model describing the H(2)O(2) elimination by mammalian cells including H(2)O(2) permeation through cytoplasmic and peroxisomal membranes: comparison with experimental data, Biochim. Biophys. Acta 1673 (2004) 149-159.], which includes relevant enzymes and H(2)O(2) permeation through membranes, was found to be fitted well to the H(2)O(2) concentration dependences of removal reaction with the permeation rate constants as variable parameters. As compared with PC12 cells as a culture model for neuron, H(2)O(2) removal activity of astrocytes was considerably higher at physiological H(2)O(2) concentrations. The details of the mathematical model are presented in Appendix.
 ...
PMID:Kinetics of hydrogen peroxide elimination by astrocytes and C6 glioma cells analysis based on a mathematical model. 1840 82

Our study explored the influence of diet on gliomagenesis and associated systemic effects (SE) in rats. The experimental diet contained various ingredients supposed to interfere with carcinogenesis, mainly phytochemicals (PtcD for phytochemical diet) and its effects were compared to those of the same diet without the phytochemicals (BD for basal diet). Glioma was induced by ethylnitrosourea to pregnant females fed the diets from the start of gestation until the moment of sacrifice of the offpsrings. In male rats fed the PtcD or the BD the incidence of gliomas was markedly reduced compared to rats fed a standard diet (StD). In females this effect was weaker and was limited to the PtcD. A significant proportion of rats with brain tumors and fed the StD exhibited SE evidenced by weight loss, a shorter survival, reduction in liver weight and an increased proportion of liver mitochondria, effects that were not observed in their counterpart fed PtcD. Comparison of the expression of genes involved in the balance proliferation/apoptosis and in the response to oxidative stress in male brain tumors showed that the prevention of SE was associated with an increase in bcl-2 and catalase and a decrease in ki-67, sod-1 and sod-2 transcripts. These results show that the degree of agressiveness of gliomas can be modulated by dietary interventions and suggest that some phytochemicals with antioxidant properties could participate to the mechanism.
 ...
PMID:Dietary prevention of malignant glioma aggressiveness, implications in oxidant stress and apoptosis. 1841 41


<< Previous 1 2 3 4 5 6 7 8 Next >>