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)

It has been well established that patients with malignant glioblastomas exhibit T cell anergy. In this report, we further investigate the nature of this T cell anergy. The results demonstrate that tumor size but not location correlates with decreased mitogen or anti-CD3 mAb responsiveness of T cells obtained from patients. Stimulation of the TCR/CD3 complex on these patients' T cells revealed defects in early transmembrane signaling. Both PHA and anti-CD3 mAb activated PBL and T cells obtained from patients exhibited a marked decrease in the tyrosine phosphorylation of a number of proteins. In particular, decreased phosphorylation of pp100 and phospholipase Cgamma1 (PLCgamma1) was observed. In addition, PLCgamma1 and p56(lck) protein levels were dramatically reduced in T cells obtained from patients harboring a glioma. In contrast, the protein levels of p59(fyn) were normal or only slightly reduced in T cells obtained from patients with gliomas. Quantitation of free intracellular calcium concentrations ([Ca2+]i) after mitogen (PHA) stimulation or ionomycin treatment of T cells obtained from patients revealed that they mobilize less calcium than do T cells obtained from normal subjects. Stimulation of T cells obtained from patients with PMA and ionomycin, which should bypass the requirement for PLCgamma1 activation as well as directly activate the p21(ras) signaling pathway, did not restore the proliferative capacity of these T cells to normal levels. These results indicate that the anergy observed in T cells obtained from these patients is a consequence of one or more defects in the early transmembrane signaling events associated with TCR/CD3 stimulation.
 ...
PMID:T cell receptor-mediated signaling is defective in T cells obtained from patients with primary intracranial tumors. 937 40

A series of opioid ligands utilizing the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) fluorophores 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene++ +-3-propionic acid or 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza- s-indacene-3-propionic acid were synthesized and characterized for their ability to act as a suitable fluorescent label for the mu opioid receptor. All compounds displaced the mu opioid receptor binding of [3H]Tyr-D-Ala-Gly-(Me)Phe-Gly-ol in monkey brain membranes with high affinity. The binding of fluorescent ligands to delta and kappa receptors was highly variable. 5,7-Dimethyl-BODIPY naltrexamine, "6-BNX," displayed subnanomolar affinities for the mu and kappa opioid receptors (Ki 0.07 and 0.43 nM, respectively) and nanomolar affinity at the delta (Ki 1.4 nM) receptor. Using fluorescence spectroscopy, the binding of 6-BNX in membranes from C6 glioma cells transfected with the cloned mu opioid receptor was investigated. In these membranes containing a high receptor density (10-80 pmol/mg protein), 6-BNX labeling was saturable, mu opioid specific, stereoselective (as determined with the isomers dextrorphan and levorphanol), and more than 90% specific. The results describe a series of newly developed fluorescent ligands for the mu opioid receptor and the use of one of these ligands as a label for the cloned mu receptor. These ligands provide a new approach for studying the structural and biophysical nature of opioid receptors.
 ...
PMID:Synthesis and characterization of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-labeled fluorescent ligands for the mu opioid receptor. 939 74

Using double immunofluorescence staining and quantitative confocal laser scan microscopy, we show that the intensity of hepatocyte growth factor/scatter factor (HGF/SF) and Met staining in human primary brain tumors increases with the grade of malignancy and is prevalent in both the infiltrating tumor cells and endothelial hyperplastic areas. HGF/SF and Met also are expressed in vitro in glioblastoma multiforme cell lines as well as in normal human astrocyte (NHA) cells. Moreover, HGF/SF stimulates tyrosine phosphorylation of Met in both glioma cell lines and NHA cells, but only the glioma cell lines proliferate and become motile and invasive in response to HGF/SF, whereas the NHA cells are nonresponsive. These results implicate autocrine/paracrine Met-HGF/SF signaling in glioma tumorigenesis and suggest that HGF/SF signaling through Met is negatively regulated in NHA cells.
 ...
PMID:Met and hepatocyte growth factor/scatter factor expression in human gliomas. 939 65

The ability of the delta opioid agonist DPDPE ([D-Pen2, D-Pen4]enkephalin) to stimulate binding of the GTP analog guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) to pertussis toxin-sensitive G proteins has been characterized in membranes from NG108-15 mouse neuroblastoma X rat glioma cells. The presence of GDP, or its hydrolysis-resistant analog GDPbetaS, and Mg++ ions was essential to observe agonist-mediated stimulation of [35S]GTPgammaS binding, although the guanine dinucleotides alone had complex inhibitory and stimulatory effects on [35S]GTPgammaS binding. The relative ability of the delta antagonists benzylidenenaltrexone and naltriben to inhibit DPDPE-stimulated [35S]GTPgammaS binding suggested the opioid receptor involved was of the delta-2 subtype. Ligand binding assays demonstrated biphasic binding of these antagonists to this single receptor type. [35S]GTPgammaS binding was also stimulated by [D-Ser2,Leu5,Thr6]enkephalin > deltorphin II = DPDPE = etorphine > levallorphan = diprenorphine = nalorphine = naltrindole. The delta antagonists benzylidenenaltrexone, TIPP (Tyr-Tic-Phe-Phe) and naltriben had no effect, but ICI 174864 (N, N-diallyl-Tyr-Aib-Phe-Leu-OH) acted as an inverse agonist and inhibited [35S]GTPgammaS binding. Pertussis toxin pretreatment blocked agonist stimulation of [35S]GTPgammaS binding and also reduced basal binding, thus confirming the presence of constitutively active delta receptors. Replacement of Na+ in the assay buffer with K+ afforded an increased level of basal [35S]GTPgammaS binding and an apparent increase in both the inverse agonist activity of ICI 174864 and the agonist activity of the partial agonist diprenorphine relative to the full agonist [D-Ser2, Leu5,Thr6]enkephalin. The stimulation of [35S]GTPgammaS binding to NG108-15 cell membranes allows a functional measure of delta opioid activity that can provide systems of differing relative efficacy.
 ...
PMID:Delta opioid modulation of the binding of guanosine-5'-O-(3-[35S]thio)triphosphate to NG108-15 cell membranes: characterization of agonist and inverse agonist effects. 940 3

In the present investigation, we have transfected a human malignant glioma cell line, U-1242 MG, and derived clones that produce transforming growth factor alpha (TGF-alpha) in an inducible manner using the tetracycline suppressible vector system. TGF-alpha expression was confirmed by Northern analysis, by ELISA, and by immunoprecipitation of metabolically labeled cells. The functional activity of the induced protein was proven by the finding of epidermal growth factor receptor (EGFR) tyrosine phosphorylation on induction of TGF-alpha. A clear effect on cell motility, i.e., cell scattering and an increased phagokinetic track area of individual glioma cells, was demonstrated. The fact that the EGFR tyrosine kinase activation was independent of cell density suggests that autocrine activation of the EGFR kinase occurred at the single-cell level. These findings are of interest, because increased cell motility is most likely a requirement for glioma cell invasion in vivo. The results imply that as a result of coexpression of EGFR and its ligand, individual glioma cells are capable of acting as independent autocrine locomotory units.
 ...
PMID:Cell scattering and migration induced by autocrine transforming growth factor alpha in human glioma cells in vitro. 940 73

Malignant gliomas infiltrate the brain preferentially along myelinated fiber tracts. Central nervous system (CNS) myelin, however, contains inhibitory proteins that block axon regeneration, neurite outgrowth, and cell spreading of astrocytes and fibroblasts. We tested 5 human brain tumor cell lines, 1 rat brain tumor cell line, and 29 short-term cultured specimens from human brain tumors for their ability to spread and migrate on a CNS myelin substrate. Low-grade and pilocytic astrocytoma, ependymoma, medulloblastoma, and meningioma cell lines as well as primary cultures were strongly sensitive to the inhibitory proteins present in the CNS myelin. In contrast, glioblastomas, anaplastic astrocytomas, and oligodendrogliomas were able to spread and migrate on CNS myelin-coated culture dishes, demonstrating that within the gliomas, the ability to overcome the inhibitory effects of the CNS myelin is correlated with the grade of malignancy of the original tumor. Cell spreading of glioblastomas and anaplastic astrocytomas specifically on a CNS myelin substrate was strongly inhibited by the metalloprotease blocker O-phenanthroline and the peptide derivative carbobenzoxy-Phe-Ala-Phe-Tyr-amide, whereas blockers for serine, aspartyl, and cysteine proteases had no effect. Enzymatic peptide degradation assays revealed the presence of a phosphoramidon-sensitive and thiorphan-insensitive metalloproteolytic activity in the plasma membranes of high-grade glioma cells. These results suggest a crucial involvement of a membrane-bound metalloendoprotease in the process of invasive migration of malignant gliomas along CNS white matter fiber tracts.
 ...
PMID:Spreading and migration of human glioma and rat C6 cells on central nervous system myelin in vitro is correlated with tumor malignancy and involves a metalloproteolytic activity. 942 71

A cholinergic neuroblastoma x glioma hybrid cell line NG108-15 is able to form functional synapses, and contains both AChR-aggregating and AChR-inducing activities when cocultured with myotubes. Several lines of evidence indicate that the AChR-inducing activity of NG108-15 cells is derived from neuregulin. The conditioned medium of cultured NG108-15 cells induced the expression of AChR alpha-subunit as well as the tyrosine phosphorylation of erbB-3 receptor. NG108-15 cells expressed neuregulin with a protein of approximately 100 kDa in size and transcripts of approximately 6.8 kbp, approximately 2.6 kbp and approximately 1.8 kbp; mRNAs encoding beta1 and alpha2 isoforms of neuregulin were revealed. NG108-15 cells were induced to differentiate by chemicals, and the chemical-induced differentiation of NG108-15 cells increased the level of neuregulin mRNA expression approximately 3-fold while the expression of a housekeeping gene remained relatively unchanged. The activity of neuregulin in the conditioned medium of NG108-15 cells was reduced by treating the medium with heparin and anti-neuregulin antibody. In addition, NG108-15 cells were transfected with antisense neuregulin cDNA and its expression of neuregulin was reduced, while its neuregulin-induced tyrosine phosphorylation activity was markedly decreased. This is the first direct demonstration that the NG108-15 cell-induced AChR upregulation on cultured myotubes is mediated by neuron-derived neuregulin.
 ...
PMID:NG108-15 cells express neuregulin that induces AChR alpha-subunit synthesis in cultured myotubes. 942 27

The activation of autocrine loops involving proto-oncogene related receptor tyrosine kinases has led to the analysis of a large number of growth factor systems in human glioma specimens and cell lines. The ErbB-2 system, also called HER-2 or neu, is analogous to the epidermal growth factor receptor system (EGF-R, ErbB-1). Neuregulins consist of a large family of proteins arising from alternative mRNA splicing of a single gene located at 8p22-p11. Activation of ErbB-2 by neuregulins occurs in heterodimeric complexes with ErbB-3 and ErbB-4. A panel of human glioma cell lines, which had previously been analyzed for ErbB-2 expression, was examined for ErbB-3 and ErbB-4 expression. Coordinate expression of ErbB-2, -3 or -4 was not observed in these cell lines. Despite the presence of a complete system capable of signaling in about half the cell lines, no constitutive activation of ErbB-2, -3 or -4 was observed, and autophosphorylation of ErbB-2 in response to heregulin was observed only in one cell line from the panel, NCE-G84. Moreover, the addition of recombinant heregulin or antibodies capable of disrupting ErbB-2/ErbB-3 complexes had no effect on cell proliferation. We conclude that the role of neuregulins and its receptors in the control of glioma cell proliferation may be limited or may be context dependent on in situ conditions which are lost in vitro. Alternatively, neuregulins may be involved in cell differentiation or survival in the central nervous system. Data supporting these conclusions are described in more detail herein.
 ...
PMID:Heregulins and the ErbB-2/3/4 receptors in gliomas. 944 30

Several distinct intracellular pathways have been recently shown to be activated during CD95/Fas/APO-1-mediated apoptosis. Here, we demonstrate that CD95 ligation induces a rapid and transient tyrosine phosphorylation and activation of phosphoinositide-3-kinase (PI-3-K) in Jurkat T lymphocytes or CD95-sensitive glioma cells. Experiments using p56lck-deficient or p56lck-reconstituted Jurkat clones and the tyrosine kinase inhibitor herbimycin A revealed that tyrosine phosphorylation and activation of PI-3-K by CD95 depends on expression of Src-like tyrosine kinases, in particular p56lck. PI-3-K stimulation seems to be critical for CD95 receptor signalling since, first, inhibition of PI-3-K prevents CD95-mediated apoptosis and, second, CD95 receptor ligation fails to induce tyrosine phosphorylation or activation of PI-3-K in CD95-resistant glioma cells. Thus, PI-3-K activation may be an early signalling event during CD95-induced apoptosis, and failure to stimulate PI-3-K may predict tumor cell resistance to CD95-triggered apoptosis.
 ...
PMID:Cellular stimulation via CD95 involves activation of phospho-inositide-3-kinase. 944 3

Annexin II is a calcium and phospholipid binding protein and a substrate for protein-tyrosine kinases. Increased levels of annexin II are observed in various cancer cells and tissues, and the molecule has been proposed as a marker of malignancy in vivo. Annexin II was expressed in four glioma cell lines (D-54MG, D-37MG, U251MG and GaMG), as determined by Western blot analyses, immunofluorescence staining and flow cytometric measurements. In addition, annexin II expression was also found in cryostat sections obtained from 15 consecutive brain tumor biopsies: Ten were histologically classified as glioblastomas, one as an astrocytoma, two as meningiomas and two as brain metastases. Cultured spheroids from the glioma cell lines and from three of the glioblastoma biopsies showed lower levels of annexin II, than found in the monolayers of the cell lines and in the freshly cut biopsies. The annexin II expression of the cell lines were not found to be related to their proliferative, migratory or invasive properties. These findings indicate that although annexin II may serve as a marker of malignancy in vivo, its expression can be reduced in vitro, and appear unrelated to malignant features of glioma cell lines.
 ...
PMID:Expression of annexin II in glioma cell lines and in brain tumor biopsies. 954 53


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>