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)

Pilocytic astrocytoma (PA) is the most common glioma of childhood. Despite their relatively high incidence, the molecular mechanisms responsible for tumorigenesis and growth of PA are poorly understood. Previous in vitro studies in our laboratory showed that despite the absence of ErbB1, PA was sensitive to ErbB1 tyrosine kinase inhibitor gefitinib. To identify alternative targets of gefitinib in PA, we studied other members of the ErbB receptor tyrosine kinase family that have been identified in brain tumors. Using gene expression microarray and Western blot analyses, we found that ErbB3 is highly overexpressed in PA compared with other pediatric brain tumors (glioblastoma, ependymoma, medulloblastoma, atypical teratoid/rhabdoid tumor, and choroid plexus papilloma). Developmental biology studies have identified Sox10 as a regulator of ErbB3 expression during development of the neural crest. Investigation of Sox10 in PA revealed that it is highly overexpressed relative to other pediatric brain tumors, lending support to the theory that Sox10-regulated overexpression of ErbB3 may be driving growth in PA. Sox10-regulated ErbB3 overexpression is a novel insight into the biology of PA, suggests possible recapitulation of developmental pathways in tumorigenesis, and presents possible targets for therapeutic intervention that might be used for hypothalamic variants not amenable to surgical cure.
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PMID:Paired overexpression of ErbB3 and Sox10 in pilocytic astrocytoma. 1689 10

The abnormal function of tyrosine kinase receptors is a hallmark of malignant gliomas. Tie2 receptor tyrosine kinase is a specific endothelial cell receptor whose function is positively regulated by angiopoietin 1 (Ang1). Recently, Tie2 has also been found in the nonvascular compartment of several tumors, including leukemia as well as breast, gastric, and thyroid cancers. There is, however, little information on the function of the Ang1/Tie2 pathway in the non-stromal cells within human tumors. We found that surgical glioblastoma specimens contained a subpopulation of Tie2+/CD31- and Tie2+/GFAP+ cells, suggesting that Tie2 is indeed expressed outside the vascular compartment of gliomas. Furthermore, analysis of a tissue array consisting of 116 human glioma samples showed that Tie2 expression in the neoplastic glial cells was significantly associated with progression from a lower to higher grade. Importantly, Ang1 stimulation of Tie2+ glioma cells resulted in increased adherence of the cells to collagen I and IV, suggesting that Tie2 regulates glioma cell adhesion to the extracellular matrix. Conversely, the down-regulation of Tie2 levels by small interference RNA or the addition of soluble Tie2 abrogated the Ang1-mediated effect on cell adhesion. In studying the expression of cell adhesion molecules, we found that Tie2 activation was related to the up-regulation of integrin beta1 levels and the formation of focal adhesions. These results, together with the reported fact that malignant gliomas express high levels of Ang1, suggest the existence of an autocrine loop in malignant gliomas and that a Tie2-dependent pathway modulates cell-to-extracellular matrix adhesion, providing new insights into the highly infiltrative phenotype of human gliomas.
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PMID:Expression of the receptor tyrosine kinase Tie2 in neoplastic glial cells is associated with integrin beta1-dependent adhesion to the extracellular matrix. 1718 82

Glioblastomas are highly lethal cancers that resist current therapies. Novel therapies under development target molecular mechanisms that promote glioblastoma growth. In glioblastoma patient specimens, the non-receptor tyrosine kinase focal adhesion kinase (FAK) is overexpressed. Upon growth factor receptor stimulation or integrin engagement, FAK is activated by phosphorylation on critical tyrosine residues. Activated FAK initiates a signal transduction cascade which promotes glioma growth and invasion by increasing cellular adhesion, migration, invasion, and proliferation. We find that human glioma cell lines express different levels of total FAK protein and activating phosphorylation of tyrosine residues Tyr397, Tyr861, and Tyr925. As all glioma cell lines examined expressed phosphorylated FAK, we examined the efficacy of a novel low-molecular weight inhibitor of FAK, TAE226, against human glioma cell lines. TAE226 inhibited the phosphorylation of FAK as well as the downstream effectors AKT, extracellular signal-related kinase, and S6 ribosomal protein in multiple glioma cell lines. TAE226 induced a concentration-dependent decrease in cellular proliferation with an associated G(2) cell cycle arrest in every cell line and an increase in apoptosis in a cell-line-specific manner. TAE226 also decreased glioma cell adhesion, migration, and invasion through an artificial extracellular matrix. Together, these data demonstrate the potential benefit of TAE226 for glioma therapy.
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PMID:A novel low-molecular weight inhibitor of focal adhesion kinase, TAE226, inhibits glioma growth. 1721 39

Leucine-rich repeat C4 (LRRC4) has been shown to inhibit glioma cell proliferation, however, little is known about the mechanism(s) underlying the action of LRRC4. Here, we show that two glioblstoma U251 cell clones stably expressing LRRC4 were established. LRRC4 expression significantly inhibited the expression of some cytokines and their receptors determined by microarray and Western blot assays, and dramatically reduced cytokine-induced AP-1, NF-kB, and CyclinD1 activation in glioma cells. Furthermore, LRRC4 expression in glioma cells significantly downregulated spontaneous and cytokine-induced expression of K-RAS and phosphorylation of c-Raf, ERK, AKT, NF-kBp65, p70S6K, and PKC, suggesting that LRRC4 inhibited receptor tyrosine kinase (RTK) signaling pathways. Moreover, treatment with bFGF, IGF1, or IGF2 stimulated LRRC4(-/-), but not the LRRC4(+), glioma cell proliferation, indicating that LRRC4 mitigated cytokine-stimulated proliferation in glioma cells. In addition, treatment of LRRC4(-/-) glioma cells with EGF, IGF2, or PDGF promoted long distance mobilization, but induced little migration in LRRC4(+) glioma cells, suggesting that LRRC4 retarded cytokine-promoted glioma cell migration in vitro. Finally, human vessel endothelial cells (ECV304) treated with VEGF grew, aligned and formed hollow tube-like structures in vitro. In contrast, LRRC4(+) ECV304 treated with VEGF failed to form vessel-tube structures. Collectively, LRRC4 expression inhibited the expression of some growth factors, cytokines and their receptors, and the capacity of glioma cells responding to cytokine stimulation, leading to inhibition of glioma cell proliferation. Conceivably, induction of LRRC4 expression may provide new intervention for human glioma in the clinic.
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PMID:LRRC4 inhibits glioblastoma cell proliferation, migration, and angiogenesis by downregulating pleiotropic cytokine expression and responses. 1754 39

Gliomas are the most common and devastating primary brain tumours. Despite therapeutic advances, the majority of gliomas do not respond either to chemo or radiotherapy. KIT, a class III receptor tyrosine kinase (RTK), is frequently involved in tumourigenic processes. Currently, KIT constitutes an attractive therapeutic target. In the present study we assessed the frequency of KIT overexpression in gliomas and investigated the genetic mechanisms underlying KIT overexpression. KIT (CD117) immunohistochemistry was performed in a series of 179 gliomas of various grades. KIT activating gene mutations (exons 9, 11, 13 and 17) and gene amplification analysis, as defined by chromogenic in situ hybridization (CISH) and quantitative real-time PCR (qRT-PCR) were performed in CD117 positive cases. Tumour cell immunopositivity was detected in 15.6% (28/179) of cases, namely in 25% (1/4) of pilocytic astrocytomas, 25% (5/20) of diffuse astrocytomas, 20% (1/5) of anaplastic astrocytomas, 19.5% (15/77) of glioblastomas and one third (3/9) of anaplastic oligoastrocytomas. Only 5.7% (2/35) of anaplastic oligodendrogliomas showed CD117 immunoreactivity. No association was found between tumour CD117 overexpression and patient survival. In addition, we also observed CD117 overexpression in endothelial cells, which varied from 0-22.2% of cases, being more frequent in high-grade lesions. No KIT activating mutations were identified. Interestingly, CISH and/or qRT-PCR analysis revealed the presence of KIT gene amplification in 6 glioblastomas and 2 anaplastic oligoastrocytomas, corresponding to 33% (8/24) of CD117 positive cases. In conclusion, our results demonstrate that KIT gene amplification rather than gene mutation is a common genetic mechanism underlying KIT expression in subset of malignant gliomas. Further studies are warranted to determine whether glioma patients exhibiting KIT overexpression and KIT gene amplification may benefit from therapy with anti-KIT RTK inhibitors.
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PMID:Molecular alterations of KIT oncogene in gliomas. 1772 62

Targeted therapies that inhibit receptor tyrosine kinases (RTKs) and the downstream phosphatidylinositol 3-kinase (PI3K) signaling pathway have shown promising anticancer activity, but their efficacy in the brain tumor glioblastoma multiforme (GBM) and other solid tumors has been modest. We hypothesized that multiple RTKs are coactivated in these tumors and that redundant inputs drive and maintain downstream signaling, thereby limiting the efficacy of therapies targeting single RTKs. Tumor cell lines, xenotransplants, and primary tumors indeed show multiple concomitantly activated RTKs. Combinations of RTK inhibitors and/or RNA interference, but not single agents, decreased signaling, cell survival, and anchorage-independent growth even in glioma cells deficient in PTEN, a frequently inactivated inhibitor of PI3K. Thus, effective GBM therapy may require combined regimens targeting multiple RTKs.
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PMID:Coactivation of receptor tyrosine kinases affects the response of tumor cells to targeted therapies. 1787 11

Glioblastoma multiforme (GBM) is the most aggressive form of brain tumor characterized by excessive angiogenesis. The dismal prognosis of patients with GBM warrants the development of new targeting therapies based on novel molecular markers. The EphA2 receptor tyrosine kinase plays a pivotal role in tumor angiogenesis and an increased expression in glioma patients has recently been reported. In this study, we investigated the expression of EphA2 in human normal brain, primary and recurrent GBM and correlated it with clinical pathological parameters and patient's outcome. In addition, intratumor microvascular density was quantified by immunostaining for the endothelial cell marker, von Willebrand factor. A different intensity of the membranous and cytoplastic expression of EphA2 was observed in the 40 primary and recurrent samples of GBM analyzed but not in the normal brain. A high level expression of EphA2 was demonstrated in 24 (60%) of the primary and recurrent GBM analyzed. The increased expression of the EphA2 protein was significantly associated with the adverse outcome of GBM patients (p<0.01 for overall survival). The data presented in this study define the expression pattern of EphA2 in both primary and recurrent glioblastoma and suggest an important role of EphA2 in the pathogenesis of GBM. The EphA2 may be used as a surrogate marker to screen patients for tyrosine kinase inhibitor therapy.
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PMID:Increased expression of EphA2 correlates with adverse outcome in primary and recurrent glioblastoma multiforme patients. 1809 89

The mechanisms and biological implications of coordinated receptor tyrosine kinase coactivation remain poorly appreciated. Epidermal growth factor receptor (EGFR) and c-Met are frequently coexpressed in cancers, including those associated with hepatocyte growth factor (HGF) overexpression, such as malignant astrocytoma. In a previous analysis of the HGF-induced transcriptome, we found that two EGFR agonists, transforming growth factor-alpha and heparin-binding epidermal growth factor-like growth factor (HB-EGF), are prominently up-regulated by HGF in human glioma cells. We now report that stimulating human glioblastoma cells with recombinant HGF induces biologically relevant EGFR activation. EGFR phosphorylation at Tyr(845) and Tyr(1068) increased 6 to 24 h after cell stimulation with HGF and temporally coincided with the induction of transforming growth factor-alpha (~5-fold) and HB-EGF (~23-fold) expression. Tyr(845) and Tyr(1068) phosphorylation, in response to HGF, was inhibited by cycloheximide and actinomycin D, consistent with a requirement for DNA transcription and RNA translation. Specifically, blocking HB-EGF binding to EGFR with the antagonist CRM197 inhibited HGF-induced EGFR phosphorylation by 60% to 80% and inhibited HGF-induced S-G(2)-M transition. CRM197 also inhibited HGF-induced anchorage-dependent cell proliferation but had no effect on HGF-mediated cytoprotection. These findings establish that EGFR can be activated with functional consequences by HGF as a result of EGFR ligand expression. This transcription-dependent cross-talk between the HGF receptor c-Met and EGFR expands our understanding of receptor tyrosine kinase signaling networks and may have considerable consequences for oncogenic mechanisms and cancer therapeutics.
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PMID:Transcription-dependent epidermal growth factor receptor activation by hepatocyte growth factor. 1823 69

We found previously that EphB6, a member of the erythropoietin-producing hepatocyte (Eph) receptor tyrosine kinase family, was preferentially expressed in malignant gliomas. In the present study, RT-PCR revealed a putative secretory variant form of human EphB6 that was expressed in the majority of glioma cell lines, though not in normal tissues. The variant has a unique 54 amino acid sequence that is not found in the normal EphB6. Therefore, we attempted to determine the antigenic peptides unique to the variant for immunotherapy. The two variant-derived peptides had the ability to bind to HLA-A2402 molecules and each of them could induce cytotoxic T-lymphocytes (CTLs) in vitro in peripheral blood mononuclear cells of HLA-A24(+) glioma patients. Furthermore, the cytotoxicity was mediated by peptide-specific CD8(+) T cells in an HLA-A24 restricted manner. Taken together, the two peptides derived from the variant of EphB6 might be appropriate targets for peptide-based specific immunotherapy to HLA-A24(+) patients with malignant glioma.
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PMID:Identification of EphB6 variant-derived epitope peptides recognized by cytotoxic T-lymphocytes from HLA-A24+ malignant glioma patients. 1842 88

We recently cloned a variant form of erythropoietin-producing hepatocyte (Eph)B6, a member of the Eph receptor tyrosine kinase family. In the present study, we examined the expression of the EphB6 variant (EphB6v) in a panel of brain tumor cell lines and glioblastoma tissues and we found that EphB6v was preferentially expressed in malignant brain tumors, such as glioblastomas and anaplastic astrocytomas. The EphB6v has a unique 54 amino acid sequence at the C-terminal that is not found in normal EphB6. Therefore, we attempted to identify antigenic peptides unique to EphB6v for immunotherapy. The two EphB6v-derived peptides exhibited the ability to bind to human leukocyte antigen (HLA)-A0201 molecules, and each of them was able to induce cytotoxic T lymphocytes in vitro in the peripheral blood mononuclear cells of HLA-A2(+) glioma patients. The cytotoxicity was mediated by peptide-specific CD8(+) T cells in an HLA-A2-restricted manner. The expression of EphB6v was also observed in different types of cancer (e.g. lung, colon, stomach, liver and pancreatic) cells. Taken together, the two peptides derived from EphB6v might be appropriate targets for peptide-based specific immunotherapy for HLA-A2(+) patients with various cancers.
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PMID:Erythropoietin-producing hepatocyte B6 variant-derived peptides with the ability to induce glioma-reactive cytotoxic T lymphocytes in human leukocyte antigen-A2+ glioma patients. 1875 80


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