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)

Cationic selena- and tellurapyrylium dyes 1d-g and 1i were found to inhibit cytochrome c oxidase upon irradiation of isolated mitochondrial suspensions treated with 10 microM solutions of dye. The amount of inhibition by these dyes was found to be related to oxygen concentration and inversely related to the concentration of added imidazole, a singlet-oxygen trap, suggesting that singlet oxygen is responsible, at least in part, for the inhibition of the enzyme. Dyes 1d-g and 1i, containing either selenium or tellurium, produce singlet oxygen with a quantum efficiency, phi (1O2), between 0.005 and 0.09 in methanol. Dyes 1a-c, containing the lighter chalcogens oxygen and sulfur, have values of phi (1O2) that are less than 0.0008 in methanol and do not inhibit cytochrome c oxidase in irradiated mitochondrial suspensions. Dyes 1c and 1d have nearly identical spectral and redox properties. Only the selenapyrylium dye 1d inhibits the enzyme, suggesting that neither ground-state nor excited-state electron transfer is important in inhibition of the enzyme. Electron micrographs of human U251 glioma cells, treated in vitro with 1i and light, showed pronounced morphology changes in the mitochondrial membranes relative to electron micrographs of untreated cells. Epifluorescence microscopy of the treated cells showed granular yellow-green fluorescence presumably from photooxidized dye in the mitochondria.
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PMID:Chalcogenapyrylium dyes as photochemotherapeutic agents. 2. Tumor uptake, mitochondrial targeting, and singlet-oxygen-induced inhibition of cytochrome c oxidase. 215 6

Suramin, a drug used in the treatment of trypanosomiasis and onchocerciasis inhibits growth-factor-induced mitogenesis. We have investigated the effect of suramin on the growth rate and the morphology of C6 glioma cells cultured in the presence of serum or in a serum-free defined medium. Exponentially growing cells were seeded in multi-dish plates (5 x 10(4) cells/2 cm2 well) in DMEM supplemented with 5% fetal calf serum and were continuously exposed to 1 microgram/ml to 1,000 micrograms/ml suramin. Growth rate (determined 9 days after seeding) was reduced by 5%, 33%, 56% and 97%, respectively for suramin concentrations of 1, 10, 100 and 1000 micrograms/ml. Similar results were obtained in serum-free defined medium (DMEM/F12, 1:1, v:v, EGF 5 ng/ml, transferrin 5 micrograms/ml, selenium 10 ng/ml). Moreover, the concentration of suramin in the culture medium remained constant, demonstrating that the drug was not actively metabolized by the cells. Suramin also induced marked changes in cell morphology: the usual bipolar shape of C6 cells evolved toward a more differentiated appearance, with numerous cellular processes allowing a wide number of cell-cell contacts. In parallel, we monitored expression of an adhesion molecule (N-CAM) at both the mRNA and protein levels. Indirect immunofluoresence technique showed an important increase in cell surface N-CAM expression, starting from a dose of 10 micrograms/ml suramin, whereas total cellular content of N-CAM protein as well as its mRNA levels were unaffected. We also observed that the levels of expression of actin and N-CAM mRNAs decreased by a factor of two in cells maintained in defined medium. However, the relative ratio of N-CAM mRNA over actin mRNA was virtually unchanged following suramin treatment. Taken together, our results suggest that suramin (i) exerts a blocking effect of autocrine growth factors, (ii) interferes with the turn-over mechanisms of N-CAM expressed at the cell surface, either by impairing its endocytosis and/or the process of release of the N-CAM 120 isoform.
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PMID:Suramin inhibits proliferation of rat glioma cells and alters N-CAM cell surface expression. 230 43

A serum-free defined medium has been formulated that supports proliferation and morphologic differentiation of U-251 MGsp human and C6-2BD rat glioma cells. This defined medium consists of a basal medium supplemented with transferrin, fibroblast growth factor, hydrocortisone, selenium, biotin, and fibronectin (G2 medium). When U-251 cells were plated in G2 medium on poly-D-lysine precoated dishes, their growth rate was 77% and final cell density was 82% of serum-grown counterparts. The growth rate of C6 cells in G2 medium was 67% compared to cells cultured in serum supplemented medium. Although G2 medium supported the growth of human and rat glioma cells, LA-N-1 human neuroblastoma and WI-38 human fibroblast cells showed no increase in cell number when grown in G2 medium compared to basal medium. A similar formulation (G3 medium), lacking fibroblast growth factor and hydrocortisone, supported the proliferation of RN-22 rat schwannoma cells. Morphologic differences were observed between cells grown in the presence of serum and in defined media. All three glial cell lines changed from a flattened shape in serum supplemented medium to a more spherical appearance in defined medium. In addition, both U-251 and C6 cells developed numerous processes, some reaching several cell diameters in length. These defined media will facilitate studies of the growth and differentiation of glial-derived cells.
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PMID:Proliferation of glial-derived cells in defined media. 621 93

Some reports have demonstrated that selenium can inhibit tumorigenesis in some tissues of animal. However, little is known about the inhibitory effect on malignant tumor cells of brain. The purpose of our study was to determine the biological effect of selenium on growth of rat glioma and human glioblastoma cell lines. Cell lines C6 and A172 were obtained from Japanese Cancer Research Resources Bank, Tokyo, Japan (JCRB). Cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal calf serum at 37 degrees C in a humidified atmosphere of air and 5% CO2. Antiproliferative effects of selenium were evaluated using growth rate assay quantifying cell number by MTT assay. An antiproliferative effect of selenium was found in two cell lines, which was more effective on human A172 glioblastoma and less effective on rat C6 glioma.
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PMID:Effect of selenium on malignant tumor cells of brain. 757 18

Several studies have shown that selenium can inhibit tumorigenesis in tissues. However, little is known about the mechanism and the effect of selenium on DNA, especially in brain tumor cells. In this study we examined the biological effect of selenium on human glioma cell lines (A172 and T98G). Selenium exhibited an antiproliferative effect on these cell lines (and induced the typical ladder pattern of DNA fragmentation commonly found in apoptosis), which were prevented by catalase. Few effects of selenium on NT14 fibroblasts were found. These findings demonstrate that selenium may induce, by apoptosis, cell death of human glioma cell lines, which are resulting from free radical oxygen forming.
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PMID:Apoptosis induced by selenium in human glioma cell lines. 888 12

Supranutrition dietary levels of the element selenium (Se) that have been shown to reduce or retard tumor development resulting from transplantation. The rat placental form of glutathione-S-transferase (GST-p) has been reported to be a good marker for pre-neoplastic or neoplastic lesions. Four groups of rats with glioma were exposed to Se-free, 0.05, 2.0, and 4.0 ppm sodium selenite GST-p was investigated. Normal brain tissue did not differ significantly in all groups. In contrast, GST-p in tumor was significantly higher in Se-free and 4.0-ppm groups compared to 0.5- and 2.0-ppm groups. The concentration of Se in normal brain tissue did not differ significantly in Se-supplement groups. By contrast, Se in tumors was significantly higher in the 0.5- and 2.0-ppm groups compared to the Se-free and 4.0-ppm groups. Mean group survival at 30 d after treatment was determined and compared with previous dietary Se. Survival was significantly longer in the 0.5- and 2.0-ppm groups than in the Se-free and 4.0-ppm groups. The 2.0-ppm group had enhanced survival, similar to the 0.5-ppm group. The Se-free and 4.0-ppm groups might have no protection against carcinogenesis.
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PMID:The decrement of carcinogenesis by dietary selenium and expression of placental form of glutathione-S-transferase in rat glioma. 928 62

Effects of Pb2+, Ni2+, Hg2+ and Se4+ on cultured human glioma U-343MG cells were investigated considering uptake, toxicity and, in combination with radiation, clonogenic cells survival. The cells were exposed to 0-100 microM of the metals for a week before the evaluation. The tests showed a tendency to toxicity with 10 microM nickel although not significant (P > 0.05). Selenium, lead and mercury exerted a significant toxicity (P < 0.05) at 2.5 microM, 10 microM and 1 microM, respectively. To challenge the clonogenic cell survival capacity, the cells were irradiated with 60Co photons after being exposed to the highest nontoxic concentration of the different metals. The clonogenic cell survival tests, after irradiation, showed no significant change if the cells were exposed to 5 microM nickel, 0.5 microM selenium or 5 microM lead compared with those not exposed. Mercury, 0.1 microM, gave a relative reduction in survival compared with only irradiated cells of 58 +/- 17%. Thus, only mercury affected the radiation-induced damage and/or repair. When exposed to the highest nontoxic concentrations of the different metals, the cultures did not display a significant uptake ratio (metal concentration ratio of exposed cells to control cells) of nickel (3.1 +/- 3.3), only a small uptake ratio of selenium (4.0 +/- 0.4), while there was a large uptake ratio of both lead (2.6 +/- 1.7) x 10(2) and mercury (1.5 +/- 0.2) x 10(1). The results indicated that nickel was neither especially toxic nor influenced the clonogenic cell survival after irradiation. Mercury was more toxic and also influenced the radiation sensitivity. Lead was taken up strongly but did not influence the radiation sensitivity. Selenium accumulated but gave no detectable effect on the radiation sensitivity.
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PMID:Effects of Pb2+, Ni2+, Hg2+ and Se4+ on cultured cells. Analysis of uptake, toxicity and influence on radiosensitivity. 935 73

Erythrocyte antioxidant enzymes were analysed in 100 patients with intracranial neoplasm and in 47 controls. There was a significant decrease in RBC glutathione reductase (GRx) and superoxide dismutase (SOD) activity in most types of brain tumor cases. Patients with acoustic neurinoma showed a significant reduction in selenium-dependent glutathione peroxidase (Se-GPx) activity. A decrease in catalase (CT) activity was seen in most of the brain tumor patients but remained statistically insignificant when compared to controls. A significant increase in plasma ceruloplasmin concentration was observed in patients with glioma. These enzymes were also studied in 27 post-treatment cases. GRx activity returned to normal levels in these patients. RBC SOD and plasma ceruloplasmin levels showed a tendency to return to normal. Hence, a marked decrease in the antioxidant enzymes may have a role in the genesis of considerable oxidative stress in patients with brain tumors.
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PMID:Role of antioxidant enzymes in brain tumours. 1080 83

To gain a better understanding of the biological consequences of the exposure of tumor cells to selenium, we evaluated the selenium-dependent responses of two selenoproteins (glutathione peroxidase and the recently characterized 15-kDa selenoprotein) in three human glioma cell lines. Protein levels, mRNA levels, and the relative distribution of the two selenocysteine tRNA isoacceptors (designated mcm(5)U and mcm(5)Um) were determined for standard as well as selenium-supplemented conditions. The human malignant glioma cell lines D54, U251, and U87 were maintained in normal or selenium-supplemented (30 nM sodium selenite) conditions. Northern blot analysis demonstrated only minor increases in steady-state GSHPx-1 mRNA in response to selenium addition. Baseline glutathione peroxidase activity was 10.7 +/- 0.7, 7.6 +/- 0.7, and 4.3 +/- 0.7 nmol NADPH oxidized/min/mg protein for D54, U251, and U87, respectively, as determined by the standard coupled spectrophotometric assay. Glutathione peroxidase activity increased in a cell line-specific manner to 19.7 +/- 1.4, 15.6 +/- 2.1, and 6. 7 +/- 0.5 nmol NADPH oxidized/min/mg protein, respectively, as did a proportional increase in cellular resistance to H(2)O(2), in response to added selenium. The 15-kDa selenoprotein mRNA levels likewise remained constant despite selenium supplementation. The selenium-dependent change in distribution between the two selenocysteine tRNA isoacceptors also occurred in a cell line-specific manner. The percentage of the methylated isoacceptor, mcm(5)Um, changed from 35.5 to 47.2 for D54, from 38.1 to 47.3 for U251, and from 49.0 to 47.6 for U87. These data represent the first time that selenium-dependent changes in selenoprotein mRNA and protein levels, as well as selenocysteine tRNA distribution, were examined in human glioma cell lines.
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PMID:Multiple levels of regulation of selenoprotein biosynthesis revealed from the analysis of human glioma cell lines. 1087 23

We examined the effect of the trace element selenium on human glioma cell lines: T98G, U373MG, and U87MG, in addition to dermal fibroblast cells. Cultures were incubated with sodium selenite, and the following parameters were studied: cell growth, mitochondrial function, and ultrastructure. Cell growth was assayed by counting the number of viable cells after treatment with selenium. Mitochondrial function was analyzed using the MTT (tetrazolium salt reduction) assay. Apoptosis was determined by evaluating nuclear chromatin condensation by electron microscopy. The results indicated that selenium had a significant inhibitory effect on the growth of the tumor cells but had little effect upon dermal fibroblasts which had been passaged numerous times. Selenium also induced mitochondrial damage as shown by MTT assay in two brain tumor cell lines and in minimally passaged fibroblasts, but it had little effect upon the high-passage fibroblasts. Ultrastructurally, mitochondria had electron-dense inclusions resulting from selenium treatment. High rates of apoptosis were induced by selenium in the tumor cell lines and in the minimally passaged fibroblasts, whereas the fibroblasts with a high number of passages had some resistance to selenium treatment. This study correlates the adverse effects of selenium on mitochondrial function, inhibition of cell growth, and apoptosis and shows that selenium similarly affects three different brain tumor cell lines and minimally passaged fibroblasts. Further, the results with fibroblasts show that some types of cells after repeated passages can develop resistance to selenium damage.
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PMID:Selenium causes growth inhibition and apoptosis in human brain tumor cell lines. 1089 65


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