Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidermal growth factor and its receptor (EGFR) constitute an important and well-characterized mitogenic system in various ectodermal tissues including glial cells. Over-expression of the EGFR due to gene amplification has been reported in primary brain tumours of glial origin. Using a monoclonal antibody to the EGFR and immunohistochemical analysis, we examined the expression and distribution of EGFR in 103 astrocytic tumours. In addition, selected tumours were studied by Western blotting using a polyclonal antibody to EGFR and by Southern blot analysis. Glioblastomas (WHO grade IV) showed EGFR expression in 37% of cases, whereas pilocytic (WHO grade I), low-grade (WHO grade II) or anaplastic astrocytoma (WHO grade III) were invariably EGFR negative. Generally, there was a close correlation between the presence of EGFR gene amplification and over-expression of receptor protein. Different patterns of immunoreactive cells and significant intratumour heterogeneity of EGFR expression were observed in glioblastomas. The specific association of EGFR over-expression with glioblastoma may provide a useful diagnostic tool for distinguishing anaplastic astrocytoma (WHO grade III) and glioblastoma multiforme (WHO grade IV).
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PMID:Expression of the epidermal growth factor receptor in astrocytic tumours is specifically associated with glioblastoma multiforme. 131 48

Epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) are potent mitogens for normal cells of ectodermal and mesodermal origin. Evidence is accumulating that suggests that EGF, TGF alpha and their common receptor (EGF/TGF alpha-R) influence development and functioning of tissues of the central nervous system (CNS). To further investigate the possible roles of EGF, TGF alpha and their receptor in autocrine/paracrine regulation of tumor growth in the CNS, a series of tumors of the CNS were analyzed for the presence of specific, high affinity EGF/TGF alpha receptors and for the presence of immunoreactive TGF alpha protein. Binding of 125I-EGF to crude membranes from a pool of meningiomas was competed for equally well by low concentrations of unlabeled EGF or TGF alpha, but not by high concentrations of other protein hormones, demonstrating the high degree of specificity of the EGF/TGF alpha receptor. Specific binding of 125I-EGF was dependent upon time and temperature, with maximum specific binding achieved after two hours at 22 degrees C. Scatchard analysis of six tumors of the CNS large enough to permit titration analysis generated linear plots with an average kilodalton of 1.1 +/- 0.1 nanometer (+/- standard error of the mean), suggesting the presence of a single class of EGF/TGF alpha-R with high affinity. EGF also stimulated phosphorylation of a 170 kilodalton protein in membrane fraction of a meningioma, demonstrating that the EGF/TGF alpha-R in this tumor retained EGF-stimulated kinase autophosphorylating activity. Membranes for 17 additional smaller tumors of the CNS were analyzed for specific binding of 125I-EGF by single, high concentration method, and all 17 tumors were found to contain specific binding of 125I-EGF. The average level of 125I-EGF for all 23 tumors of the CNS was 46 +/- 27 femtomoles per milligram protein with a range of 1 femtomoles per milligram for both a pituitary adenoma and meningioma to 638 femtomoles per milligram for a glioblastoma. A series of 13 tumors of the CNS were analyzed for EGF alpha with use of a specific radioimmunoassay. TGF alpha immunoreactive protein was detected in all four malignant tumors of the CNS assayed at an average level of 2.6 +/- 1.1 nanograms per milligram soluble protein, whereas TGF alpha immunoreactive protein was detected in only two of nine benign tumors of the CNS. These results add support to the hypothesis that TGF alpha and its receptor may act by autocrine/paracrine mechanisms to influence growth of tumors of the CNS in vivo.
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PMID:Detection of epidermal growth factor and transforming growth factor alpha protein in meningiomas and other tumors of the central nervous system in human beings. 821 1

Epidermal growth factor (EGF) and platelet-derived growth (PDGF) are suggested to be involved in the proliferation of human gliomas. We examined the effects of these growth factors on two human malignant glioma cell lines. Treatment of the A172 glioblastoma and the Hs683 glioma cell line with EGF and PDGF resulted in the tyrosine autophosphorylation, and hence activation, of the respective growth factor receptors. In addition, both cell lines responded to EGF and PDGF with increased deoxyribonucleic acid (DNA) synthesis. Because the intrinsic protein tyrosine kinase activity of this class of growth factor receptors is indispensable for their functioning, we tested the effects of specific protein tyrosine kinase inhibitors on growth factor-induced DNA synthesis and glioma cell proliferation. Genistein inhibited both EGF- and PDGF-stimulated autophosphorylation of the receptors and induction of DNA synthesis. However, genistein seemed to be cytotoxic to the cells. The tyrphostins RG 50875 and RG 13022 dose-dependently inhibited DNA synthesis induced by EGF, PDGF, and serum. RG 13022 completely blocked the EGF- and PDGF-induced DNA synthesis at a concentration of 50 mumol/L. The tyrphostins showed no selectivity in blocking either EGF or PDGF signaling. With concentrations up to mumol/L, no cytotoxic side effects of the tyrphostins were observed. Both tyrphostins also inhibit serum-driven cell growth in a dose-dependent manner. These results support the hypothesis that activated protein tyrosine kinase receptors are involved in the proliferation of A172 and Hs683 glioma cells. Selective inhibitors of protein tyrosine kinases, therefore, might have the potential to contribute to the treatment of growth factor-dependent gliomas.
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PMID:Inhibitors of protein tyrosine phosphorylation reduce the proliferation of two human glioma cell lines. 874 58

The tumor suppressor PTEN dephosphorylates focal adhesion kinase (FAK) and inhibits integrin-mediated cell spreading and cell migration. We demonstrate here that expression of PTEN selectively inhibits activation of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway. PTEN expression in glioblastoma cells lacking the protein resulted in inhibition of integrin-mediated MAP kinase activation. Epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)- induced MAPK activation were also blocked. To determine the specific point of inhibition in the Ras/Raf/ MEK/ERK pathway, we examined these components after stimulation by fibronectin or growth factors. Shc phosphorylation and Ras activity were inhibited by expression of PTEN, whereas EGF receptor autophosphorylation was unaffected. The ability of cells to spread at normal rates was partially rescued by coexpression of constitutively activated MEK1, a downstream component of the pathway. In addition, focal contact formation was enhanced as indicated by paxillin staining. The phosphatase domain of PTEN was essential for all of these functions, because PTEN with an inactive phosphatase domain did not suppress MAP kinase or Ras activity. In contrast to its effects on ERK, PTEN expression did not affect c-Jun NH2-terminal kinase (JNK) or PDGF-stimulated Akt. Our data suggest that a general function of PTEN is to down-regulate FAK and Shc phosphorylation, Ras activity, downstream MAP kinase activation, and associated focal contact formation and cell spreading.
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PMID:Tumor suppressor PTEN inhibits integrin- and growth factor-mediated mitogen-activated protein (MAP) kinase signaling pathways. 983 64

Epidermal growth factor (EGF) receptor-mediated cell migration plays a vital role in invasion of many tumor types. EGF receptor ligands increase invasiveness in vivo, but it remains unclear how consequent effects on intrinsic cell motility behavior versus effects on extrinsic matrix properties integrate to result in net increase of translational speed and/or directional persistence of migration in a 3D environment. Understanding this convolution is important for therapeutic targeting of tumor invasion, as key regulatory pathways for intrinsic versus extrinsic effects may not be coincident. Accordingly, we have undertaken a quantitative single-cell imaging study of glioblastoma cell movement in 3D matrices and on 2D substrata across a range of collagen densities with systematic variation of protease-mediated matrix degradation. In 3D, EGF induced a mild increase in cell speed and a strong increase in directional persistence, the latter depending heavily on matrix density and EGF-stimulated protease activity. In contrast, in 2D, EGF induced a similarly mild increase in speed but conversely a decrease in directional persistence (both independent of protease activity). Thus, the EGF-enhanced 3D tumor cell migration results only partially from cell-intrinsic effects, with override of cell-intrinsic persistence decrease by protease-mediated cell-extrinsic reduction of matrix steric hindrance.
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PMID:Epidermal growth factor-induced enhancement of glioblastoma cell migration in 3D arises from an intrinsic increase in speed but an extrinsic matrix- and proteolysis-dependent increase in persistence. 1863 79

Tumor cell invasion into the surrounding brain tissue is mainly responsible for the failure of radical surgical resection and successful treatment, with tumor recurrence as microdisseminated disease. Epidermal growth factor receptors (EGFRs), integrins and their ligands in the extracellular matrix (ECM) predominantly participate in the invasion process, including the cell adhesion to the surrounding microenvironment and cell migration. The extent of infiltration of the surrounding brain tissue by malignant tumors strongly depends on the tumor cell type. Malignant gliomas show much more intensive peritumoral invasion than do metastatic tumors. In this study, the mRNA expression of 29 invasion-related molecules (18 cell membrane receptors or receptor subunits (EGFRs and integrins) and 11 ECM components: collagens, laminins and fibronectin) was investigated by quantitative reverse transcriptase-polymerase chain reaction. Fresh frozen human tissue samples from glioblastoma (GBM) and intracerebral bronchial adenocarcinoma metastases (five pieces from each) were evaluated. Significant differences were established in six of the 29 molecules (ErbB1, 2, 3, integrins alpha3, 7 and beta1). To confirm our results at the protein level, immunohistochemical analysis of nine molecules was performed. The staining intensity differed definitely in the case of ErbB1, 2 and integrins alpha3 and beta1. Determining the differences in invasion-related molecules in tumors of different origin can help identify the exact molecular mechanisms that facilitate peritumoral infiltration by glioblastoma cells. These results should allow the selection of target molecules for potential chemotherapeutic agents directed against highly invasive malignant gliomas.
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PMID:[Expression pattern of invasion-related molecules in brain tumors of different origin]. 1979 89

Epidermal growth factor module-containing mucin-like hormone receptor-3 (EMR-3) is a G-protein coupled receptor with unknown ligand and cellular function. Upregulation of EMR-3 in glioblastoma (GBM) multiforme is associated with poor survival. We investigated the expression patterns and functional significance of EMR-3 in GBM using immunohistochemistry, western blot, reverse transcription PCR, and small interfering RNA knockdown in proliferation and invasion assays. EMR-3 is variably expressed in primary human GBM tissues and cell lines. Knocking down EMR-3 has no impact on cellular proliferation, but decreases cellular invasion by greater than 3-fold. EMR-3 is a potential mediator of cellular invasion in GBM. Given the poor survival associated with high levels of EMR-3 expression in glioma patients, our results provide impetus to explore EMR-3 as a potential therapeutic target.
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PMID:EMR-3: a potential mediator of invasive phenotypic variation in glioblastoma and novel therapeutic target. 2082 26

Epidermal growth factor (EGF) module-containing mucin-like receptor 2 (EMR2) is a member of the seven span transmembrane (TM7) adhesion G-protein coupled receptor subclass. It is abundantly expressed in immune cells of myeloid origin and appears to mediate cellular adhesion, migration, and signaling. Based on an analysis showing earlier mortality among glioblastoma patients whose tumors highly express EMR2, we studied its expression patterns in glioblastoma and potential to mediate cellular proliferation and invasion. We performed univariate analysis of overall survival in GBM patients expressing low, moderate, and high amounts of EMR2 based on publicly available microarray data in the Cancer Genome Atlas (TCGA). Using RT-PCR and western blotting, we studied mRNA and protein expression patterns of EMR2, respectively. We then employed siRNA knockdown of EMR2 in two human glioblastoma cell lines expressing high levels of EMR2 to assess functional effects on cellular proliferation and invasion, in vitro. Kaplan-Meier analysis of TCGA survival data for GBM demonstrated that EMR2 levels are inversely correlated with overall time until mortality (log rank, P < 0.01). EMR2 mRNA and protein is variably expressed in primary glioblastoma samples and human glioblastoma cell lines. When comparing cells transfected with siRNA targeting EMR2 to those transfected with a negative, scramble control, there was no difference in proliferation over 72 h in the SF767 and G55 glioblastoma cell lines. However, EMR2 knockout cells demonstrated an almost 3-fold reduction in migration compared to their negative controls (P < 0.05) in the SF767 cell line, and an almost 2-fold reduction (P < 0.05) in migration in the G55 cell line. We provide evidence that EMR2 is expressed in glioblastoma and has significant functional consequences on cellular invasion, but not proliferation. In light of its ability to promote adhesion and migration in immune cells, our data suggest that EMR2 may mediate similar phenomena in glioblastoma. The invasive phenotype conferred by EMR2 correlates with clinical data demonstrating poor survival in glioblastoma patients who express high levels of EMR2 in their tumor.
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PMID:Epidermal growth factor module-containing mucin-like receptor 2 is a newly identified adhesion G protein-coupled receptor associated with poor overall survival and an invasive phenotype in glioblastoma. 2150 28

Epidermal growth factor (EGF) and its receptor (EGFR) have been shown to play a significant role in the pathogenesis of glioblastoma. In our study, the EGFR was stimulated with EGF in human U138 glioblastoma cells. We show that the activated mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinases (ERK) 1/2 pathway phosphorylated the E twenty-six (ETS)-like transcription factor 1 (Elk-1) mainly at serine 383 residue. Mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, UO126 and ERK inhibitor II, FR180204 blocked the Elk-1 phosphorylation and activation. The phosphatidylinositide-3-OH kinase (PI3K)/Akt pathway was also involved in the Elk-1 activation. Activation of the Elk-1 led to an increased survival and a proliferative response with the EGF stimulation in the U138 glioblastoma cells. Knocking-down the Elk-1 using an RNA interference technique caused a decrease in survival of the unstimulated U138 glioblastoma cells and also decreased the proliferative response to the EGF stimulation. The Elk-1 transcription factor was important for the survival and proliferation of U138 glioblastoma cells upon the stimulation of EGFR with EGF. The MAPK/ERK1/2 and PI3K/Akt pathways regulated this response via activation of the Elk-1 transcription factor. The Elk-1 may be one of the convergence points for pathways located downstream of EGFR in glioblastoma cells. Utilization of the Elk-1 as a therapeutic target may lead to a novel strategy in treatment of glioblastoma.
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PMID:Both mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinases (ERK) 1/2 and phosphatidylinositide-3-OH kinase (PI3K)/Akt pathways regulate activation of E-twenty-six (ETS)-like transcription factor 1 (Elk-1) in U138 glioblastoma cells. 2208 29

Glioblastoma (GB) is a highly invasive and lethal brain tumor due to its universal recurrence. Although it has been suggested that the electroneutral Na(+)-K(+)-Cl(-) cotransporter 1 (NKCC1) can play a role in glioma cell migration, the precise mechanism by which this ion transporter contributes to GB aggressiveness remains poorly understood. Here, we focused on the role of NKCC1 in the invasion of human primary glioma cells in vitro and in vivo. NKCC1 expression levels were significantly higher in GB and anaplastic astrocytoma tissues than in grade II glioma and normal cortex. Pharmacological inhibition and shRNA-mediated knockdown of NKCC1 expression led to decreased cell migration and invasion in vitro and in vivo. Surprisingly, knockdown of NKCC1 in glioma cells resulted in the formation of significantly larger focal adhesions and cell traction forces that were approximately 40% lower than control cells. Epidermal growth factor (EGF), which promotes migration of glioma cells, increased the phosphorylation of NKCC1 through a PI3K-dependant mechanism. This finding is potentially related to WNK kinases. Taken together, our findings suggest that NKCC1 modulates migration of glioma cells by two distinct mechanisms: (1) through the regulation of focal adhesion dynamics and cell contractility and (2) through regulation of cell volume through ion transport. Due to the ubiquitous expression of NKCC1 in mammalian tissues, its regulation by WNK kinases may serve as new therapeutic targets for GB aggressiveness and can be exploited by other highly invasive neoplasms.
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PMID:Regulation of brain tumor dispersal by NKCC1 through a novel role in focal adhesion regulation. 2257 May 91


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