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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The C6 glioma cell line contains nerve growth factor (NGF) which can be released into the medium. Treatment of the cells with beta-adrenoceptor agonists resulted in increased content of NGF in both the cells and the medium within a few hours, whereas alpha-adrenoceptor agonists were ineffective. The response was blocked by beta- but not alpha-adrenoceptor antagonists. The increase of the NGF content of glioma cells appeared to be mediated by an elevation of cyclic AMP or GMP. The addition to the cell cultures of other putative neurotransmitters failed to change the content of either NGF or cyclic AMP. These results are discussed with respect to a model for adrenergic neuron-glial interactions.
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PMID:Regulation of nerve growth factor content in C6 glioma cells by beta-adrenergic receptor stimulation. 2 24

Using a quantitative reverse transcription-polymerase chain reaction (RT-PCR) we have investigated the expression of the neurotrophin receptors p75NGFR, trkA, and trkB mRNAs in cultures of rat pup type I astrocytes and in the C6 rat glioma cell line. All three neurotrophin receptor mRNAs are expressed in both C6 cells and in type I astrocytic cultures. p75NGFR mRNA levels are increased by either cycloheximide or nerve growth factor (NGF) treatment of C6 cells as measured using RT-PCR. Type I astrocyte cultures also expressed p75NGFR mRNA and NGF treatment increased p75NGFR mRNA levels in these cultures. TrkB mRNA levels were increased by cycloheximide treatment of type I astrocyte cultures but not by NGF treatment. Using RT-PCR, trkA mRNA was detected in astrocytic cultures as well as in the rat C6 and PC-12 cell lines. We conclude that cultures of type I astrocytes express active NGF receptors and that glia can elicit a response to NGF as seen by an increase in p75NGFR mRNA levels following exposure to NGF.
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PMID:Expression of p75NGFR TrkA, and TrkB mRNA in rat C6 glioma and type I astrocyte cultures. 127 89

Two types of nerve growth factor (NGF) receptors have been described: high affinity (class I) and low affinity (class II). Biological responses to NGF are thought to be mediated by class I receptors, whereas the role of class II receptors is less clear. While some neuronal cells express both receptor types, only class II receptors have been detected on glial cells. Two glial cell lines, peripheral Schwannoma D6P2T and central 33B glioma cells, were employed to investigate the properties of class II receptors in the absence of class I receptors. These cell lines were found to express NGF receptors identified as class II by a low nanomolar dissociation constant, rapid dissociation kinetics at 4 degrees C, and trypsin sensitivity. The receptor was found to bind brain-derived neurotrophic factor with similar affinity as NGF. The responsible binding molecule appeared in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a heterogeneously glycosylated protein of 60-80 kDa with a tendency to aggregate. All receptor bands affinity-labeled with radioiodinated NGF were immunoprecipitated with anti-p75NGFR antibody, but not with anti-p140prototrk antiserum. In these cells, which express p75NGFR as only NGF receptor, a time- and temperature-dependent appearance of a nondisplaceable, trypsin-resistant, acid wash-stable ligand fraction, followed by an increase of trichloroacetic acid-soluble radiolabel in the medium was observed. This sequestration resembled receptor-mediated internalization with subsequent degradation of NGF. Whether this ligand processing indicates a functional role of p75NGFR in glial cells remains to be shown.
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PMID:Nerve growth factor (NGF) receptor on rat glial cell lines. Evidence for NGF internalization via p75NGFR. 132 Nov 30

The rationale behind the evaluation of natural differentiating agents, such as nerve growth factor (NGF), for reverse transforming potential is based on the theory that such compounds may represent a nontoxic means of controlling tumor growth. Previous in vitro experiments have shown that NGF is capable of retarding growth and of inducing persistent differentiation of neurogenic tumor cell lines. In vivo, NGF is capable of causing a persistent reduction in the number of ethylnitrosourea-induced neurinomas and of increasing survival time following intracerebral implantation of F98 anaplastic glioma cells. In this study, anaplastic glioma and neurinoma implants were treated with NGF to evaluate the reverse transforming potential of NGF in vivo. Results indicate that NGF is capable of causing a significant decrease in the growth rate of subcutaneous T9 (anaplastic glioma) and clone 16 (anaplastic neurinoma) implants. Significantly, NGF treatment was accompanied by adverse effects that were minimal and transient. Continued tumor growth (although greatly retarded) following NGF treatment is an aspect that requires further investigation. However, the results of this study suggest that NGF may prove useful, alone or in combination with other types of therapy, for the treatment of tumors of neurogenic origin.
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PMID:The use of nerve growth factor as a reverse transforming agent for the treatment of neurogenic tumors: in vivo results. 132 2

The synthesis of nerve growth factor (NGF) and nerve growth factor receptor (NGFR) were studied in a C6 glioma cell line by Northern blot hybridization. In response to a glutamate agonist N-methyl-D-aspartic acid (NMDA), NGF mRNA increased by up to 2-fold after 4-12 h of culture. The non-NMDA receptor agonists, quisqualate and kainate, did not induce any increase of NGF mRNA, and kainate actually produced a decrease. The increase in NGF mRNA in response to NMDA was dose-dependent at 1, 5 and 10 microM. NGF receptor (NGFR) mRNA showed changes in expression which were similar to those for NGF mRNA, but were less marked. The specific glutamate antagonist 2-aminophosphonovaleric acid (APV) blocked the increase of NGF mRNA produced by NMDA. In the absence of Ca2+, an increase of NGF mRNA was still observed but in the presence of 1 mM ethylglycol-bis-(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA), NGF mRNA production abolished. The mechanism producing an increase in NGF mRNA by NMDA may be mediated by cyclic AMP since intracellular cyclic AMP and NGF mRNA levels both increased following treatment with NMDA or dibutyryl cyclic AMP.
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PMID:Regulation of nerve growth factor and nerve growth factor receptor production by NMDA in C6 glioma cells. 135 54

Typical markers for neurons but not for astroglia have been identified in cells cultured from a sample of normal adult human temporal lobe, which was removed to gain access to a glioma. Cells were grown in medium containing growth factors, including fibroblast growth factor and nerve growth factor. The cells grew slowly (doubling time, 18 days) and have been carried as far as passage 8 over 10 months. Both immunoblotting and immunocytochemistry with redundant antibodies demonstrated the presence of neurofilaments (NF-H, NF-M, NF-L), but not glial fibrillary acidic protein (GFAP). Neuron-specific enolase (NSE) was also found. Morphologically, the cultures consisted of a pleimorphic population of cells with frequent long processes. Cells demonstrating neuronal rather than astroglial markers can be cultured from normal adult human brain.
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PMID:Presence of typical neuronal markers in serially cultured cells from adult human brain. 140 91

The neurotrophic proteins nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are related in their primary amino acid structures. In this study we investigated the extent to which the low-affinity NGF receptor (LNGFR) in C6 glioma cells can discriminate between the neurotrophins NGF and BDNF. LNGFR-immunoreactivity (IR) was studied in C6 cells treated for 16 hr with NGF (50 ng/ml) or BDNF (10 ng/ml), using immunogold labelling and electron microscopic morphometric analysis. The cells were exposed to the anti-NGFR antibody 192-IgG, followed by immunoglobulin conjugated with colloidal gold. Untreated C6 cells exhibited some surface gold label (positive LNGFR-IR). Cells treated with NGF or BDNF displayed significantly increased LNGFR-IR on all surfaces in terms of gold labeling, which was more pronounced in NGF-treated cells. LNGFR-IR was also localized in coated endocytotic vesicles, in smooth endoplasmic reticulum, and in secondary multivesicular lysosomes in neurotrophin-treated and untreated cells. The increase in LNGFR protein was further substantiated by a correspondingly higher content of LNGFR mRNA detected after 15 hr of either NGF or BDNF treatment. These results suggest that the LNGFR in glial cells can be upregulated by the structurally related neurotrophins NGF and BDNF.
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PMID:Nerve growth factor (NGF) receptors in a central nervous system glial cell line: upregulation by NGF and brain-derived neurotrophic factor. 145 86

Rat pheochromocytoma PC12 cells form tumors when placed into the brains of Sprague-Dawley rats under specific conditions. We now show that tumorigenic potential is regulated by the microenvironment of the developing cerebrum. PC12 cell aggregates were identified in the periventricular or intraventricular spaces within 24 h after injection of cell suspensions into rat brains. In fetal or young neonatal (1-4-day-old) recipient rat brains, these cell aggregates formed large masses within 21 days. The tumor incidence declined in recipient neonates between the ages of 5 and 8 days. In both cases, tumors spread throughout the ventricular system and subarachnoid and Virchow-Robin spaces as they grew. In contrast, tumors were not generated by injections into adult rat brains or by placement of PC12 cell pellets into preformed cavities. Despite the loss of tumorigenicity, surviving cells were present at the injection site. The presence of surviving cells and the ability of another rat cell line (the C6 rat glioma line) to form tumors in adult rat brains suggest that an immune response is not solely responsible for the lack of PC12 tumorigenicity in adult rat brains. We propose that developmentally increasing local concentrations of specific factors (e.g., nerve growth factor of fibroblast growth factor) may also contribute to the suppression of tumor formation in this system.
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PMID:Formation of PC12 tumors after transplantation into rat brains: dependence of time course on host age. 155 Nov 20

The proliferation of many nonglial tumors in vitro depends on the presence of nanomolar concentrations of one or more growth factors. To define the growth factor requirements of malignant glial tumors, the authors examined the response properties of four low-passage human malignant glioma lines to the following mitogens: epidermal growth factor (EGF), acidic and basic fibroblast growth factors (FGF's), insulin-like growth factor I (IGF-I), nerve growth factor (NGF), platelet-derived growth factor (PDGF), 12-O-tetradecanoyl-13-phorbol acetate (TPA), and serum. Each of the tumors showed increased deoxyribonucleic acid (DNA) synthesis (assessed by acid-precipitable [3H]-thymidine incorporation) in response to PDGF with a maximum effect at 50 ng/ml. Three tumors responded to EGF, three to IGF-I, two to acidic FGF, two to basic FGF, and two to TPA with maximum effects at 10, 50, 1, 1, and 10 ng/ml, respectively. None of the tumors responded to NGF. In the responsive tumors, optimum concentrations of EGF, IGF, TPA, acidic FGF, and basic FGF induced, at most, a two- to fourfold increase in [3H]-thymidine incorporation, which was only 30% to 50% of the response seen in 10% serum. In contrast, PDGF increased DNA synthesis eight- to 10-fold, equaling the effect of 10% serum. Measurements of cell proliferation also demonstrated a significant response to PDGF in each of the tumors. Appropriate concentrations of an anti-PDGF neutralizing antibody inhibited baseline DNA synthesis and proliferation in the absence of added growth factors, suggesting the possible role of PDGF in autocrine stimulation of these cells. However, this antibody produced only slight inhibition of serum-induced mitogenesis. Trapidil, an agent reported to inhibit the effects of PDGF, and polymyxin B, an inhibitor of protein kinase C, strongly inhibited baseline as well as PDGF- and serum-induced mitogenesis. It is concluded that, in the malignant gliomas studied, PDGF may be acting as a dominant mitogen to enhance DNA synthesis, and may function in autocrine stimulation. However, other factors contained in serum can also contribute to cell division.
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PMID:Response of low-passage human malignant gliomas in vitro to stimulation and selective inhibition of growth factor-mediated pathways. 164 72

Monoclonal antibody 217c was generated against an antigen expressed on the rat glial cell line, C6 glioma, 217c has been shown to recognize Schwann cells in mixed cultures as well as in tissue sections and has been used to identify Schwann cells independent of other markers, such as monoclonal antibody 192-IgG, which recognizes the rat low affinity nerve growth factor (NGF) receptor. Here we show that the antigen recognized by 217c is the rat low-affinity NGF receptor. This indicates that monoclonal antibodies 192-IgG and 217c are not independent markers and therefore that additional criteria need to be used for the identification of Schwann cells early in development.
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PMID:A Schwann cell antigen recognized by monoclonal antibody 217c is the rat low-affinity nerve growth factor receptor. 164 81


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