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)

Overexpressed epidermal growth receptor factor receptors (EGFRs) are thought to contribute to the malignant phenotype of human glioblastomas (GBMs), but the mechanism is not well understood. We found that SKMG-3 cells, a rare GBM cell line that maintains EGFR gene amplification in vitro, produced high levels of EGFR protein. The cells also expressed the related receptors HER2/neu and HER4, but not HER3. Immunoblots and tryptic phosphopeptide maps showed that the SKMG-3 EGFRs were intact and functional and that a subset of these receptors were spontaneously autophosphorylated. EGF treatment stimulated phosphorylation of the EGFRs as well as the downstream effectors Erk, AKT1, stat3 and c-Cbl. Under minimal growth conditions, the unstimulated SKMG-3 cells contained constitutively phosphorylated Erk and AKTI but no detectable stat3 DNA-binding complexes. The EGFR kinase inhibitor PD158780 reduced the constitutive phosphorylation of the receptor and Erk but not that of AKT1. In contrast, inhibition of phosphatidylinositol-3-kinase (PI3K) blocked the constitutive phosphorylation of Erk and AKT-1 but not the EGFR. We conclude that the SKMG-3 cells represent the subset of GBMs with amplified EGFR genes that overexpress intact receptors. The results also suggest that in some GBMs, signals from overexpressed EGFRs contribute to the constitutive phosphorylation of Erk, but these signals may not required for the constitutive activation of PI3K or AKT1.
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PMID:Spontaneous activation and signaling by overexpressed epidermal growth factor receptors in glioblastoma cells. 1253 15

Primarily involved in cell proliferation and differentiation processes, the plasma membrane-bound ErbB tyrosine kinase receptor family is formed by four members: erbB1/EGFR, erbB2/HER2/Neu, erbB3/HER3 and erbB4/HER4. Calmodulin (CaM) is a Ca2+-binding protein involved in the regulation of multiple intracellular processes that binds directly to EGFR in the presence of Ca2+, inhibiting its tyrosine kinase activity. Two main regions in the receptor have been implicated in this relationship: the calmodulin-binding domain (CaM-BD) and the calmodulin-like domain (CaM-LD); their sequences are highly conserved in other members of this family of receptors. The presence of mutations, amplification and/or overexpression and genomic rearrangement of these domains was investigated for all four erbB family genes in a series of 89 glial tumors, including 44 WHO grade IV glioblastomas, 21 WHO grade III anaplastic astrocytomas, and 24 WHO grade II astrocytomas. Gene alterations were only found in the regions of interest in EGFR. One glioblastoma showed an in frame tandem duplication of the intracellular region including CaM-LD (exons 18-25). CaM-BD gene overdose was evidenced in 18 tumors that showed EGFR amplification in other domains. Over-expression of CaM-BD and CaM-LD was detected in 6 and 17 cases, respectively, of the 19 tumors in which this study was performed. The other three genes coding for the ErbB receptors did not present point mutations, or rearrangements, and only a very low amplification rate was found for erbB2 (1 case) and erbB3 (4 cases). No overexpression of erbB2, erbB3 or erbB4 was detected. These findings suggest that EGFR is the main erbB gene family member non-randomly involved in malignant glioma development, and that the two domains under study, due to their high conservation and wide separation in the EGFR sequence, are good marker regions for evaluating EGFR/erbB1 gene amplification, as well as for analysing the presence of transcripts corresponding to truncated cytosolic forms of the receptor in these tumors.
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PMID:Molecular analysis of the erbB gene family calmodulin-binding and calmodulin-like domains in astrocytic gliomas. 1549 43

Receptor tyrosine kinases of the EGFR family transmit extracellular signals that control diverse cellular functions such as proliferation, differentiation and survival. Signaling function of a member of this family, HER3, is believed to be impaired due to deviations in its kinase consensus motifs. Here we address the functional role and signaling mechanisms of HER3. HER3 preferentially forms heterodimers with HER2 inducing the most potent mitogenic signal among EGFR family members. Our data show that in a glioma-derived cell line the cytoplasmic tyrosine kinase PYK2 is constitutively associated with HER3 and that stimulation with Heregulin results in PYK2 tyrosine phosphorylation. HER3, but not HER2, mediates the phosphorylation of the C-terminal region of PYK2 to promote a mitogenic response through activation of the MAPK pathway. A central role of PYK2 in signaling downstream of HER3 is substantiated by the demonstration that expression of a dominant-negative PYK2-KM construct abrogates the Heregulin-induced MAPK activity and inhibits the invasive potential of glioma cells. These results suggest a novel Heregulin/HER3-stimulated signaling pathway in glioblastoma-derived cell lines that involves phosphorylation of PYK2 and mediates invasiveness of glioma cells.
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PMID:Tyrosine phosphorylation of PYK2 mediates heregulin-induced glioma invasion: novel heregulin/HER3-stimulated signaling pathway in glioma. 1549 13

High-grade gliomas, including glioblastoma, are among the most malignant and treatment-refractory human neoplasms. The tumors show high levels of resistance to conventional therapies (i.e. surgery, irradiation, and chemotherapy), and despite treatment advances patient outcome remains poor. New therapeutic options are needed. An especially interesting idea is the rational development of new therapies targeting molecules in cancer specific signaling pathways, thereby ideally increasing treatment efficacy and minimizing toxicity. Clearly, rational design requires thorough understanding of the molecular pathogenesis and resistance mechanisms. One highly promising approach is the targeted inhibition of ErbB growth factor receptors, which are recognized as key signaling pathways in many types of human tumors, including high-grade glioma. The ErbB receptor family of tyrosine kinases comprises four members: epidermal growth factor receptor (EGFR/ErbB1/HER1), ErbB2 (HER2/neu), ErbB3 (HER3) and ErbB4 (HER4). Physiologically, signaling is induced by ligand initiated receptor homo- or heterodimerization, activating intracellular downstream signaling pathways and leading to increased cell proliferation, anti-apoptosis and migration. A truncated, constitutively activated mutant EGFR (EGFRvIII) is associated with poor survival in GBM. Thus, to date anti-ErbB approaches are mainly focused on EGFR. The two major classes of anti-ErbB therapeutics are monoclonal antibodies (e.g. cetuximab, panitumumab) and small molecule Tyrosine kinase inhibitors (TKI, e.g. gefitinib, erlotinib, lapatinib). Some compounds entered clinical trials already, but clinical efficacy needs to be enhanced. Here we review current therapeutic advances targeting ErbB receptors in high-grade gliomas, and give a concise overview on current understanding of ErbB biology in gliomas, paving the way to novel rational therapeutic development.
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PMID:Targeting ErbB receptors in high-grade glioma. 2182 13

The epidermal growth factor receptor (EGFR) is a member of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases and is involved in cell growth and differentiation. EGFR homodimers or heterodimers with other HER members, such as HER2 and HER3, activate downstream signaling cascades in many cancers. In this study, we developed novel anti-EGFR monoclonal antibodies (mAbs) and characterized their efficacy in flow cytometry, Western blot, and immunohistochemical analyses. First, we expressed the full-length or ectodomain of EGFR in LN229 glioblastoma cells and then immunized mice with LN229/EGFR or ectodomain of EGFR, and performed the first screening using enzyme-linked immunosorbent assays. Subsequently, we selected mAbs according to their efficacy in flow cytometry (second screening), Western blot (third screening), and immunohistochemical (fourth screening) analyses. Among 100 mAbs, only one clone EMab-51 (IgG1, kappa) reacted with EGFR in Western blot analysis. Finally, immunohistochemical analyses with EMab-51 showed sensitive and specific reactions against oral cancer cells, warranting the use of EMab-51 to detect EGFR in pathological analyses of EGFR-expressing cancers.
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PMID:Development of EMab-51, a Sensitive and Specific Anti-Epidermal Growth Factor Receptor Monoclonal Antibody in Flow Cytometry, Western Blot, and Immunohistochemistry. 2889 52

This study presents a unique series of malignant supratentorial gliomas in children previously cured from non-CNS primary cancer. On neuroimaging these tumors were not specific, so the patients were suspected of cerebral recurrence of their primary neoplasm: leukemia in four children and sarcoma in one child. Histologically, the group contained four glioblastomas and one anaplastic astrocytoma. Three patients underwent neurosurgical resection, while the other two underwent stereotactic diagnostic biopsy only. Despite combined oncological treatment, four children died during 20 months, and only one glioblastoma patient continued to live for another twelve years. Microscopically, the neoplasms consisted of small cells with some morphologic features of astrocytic lineage, having scanty or prominent processes. Microvascular proliferation and focal or diffuse necrosis were encountered in four cases. The GFAP reactivity in neoplastic cells was low or nil, together with the expression of Olig2, vimentin, and nestin. In two cases a subpopulation of synaptophysin-positive cells was present. Molecular immunohistochemical profiling revealed the expression of phosphorylated forms of PI3Kp110 and AKT, in parallel to a strong PTEN and p53 positivity. The tumors were of IDH1R132H-wild type and immunoreactive for ATRX, HER3, and EGFR. Secondary malignant gliomas in pediatric cancer survivors pose a diagnostic challenge. The present study shows that these tumors are of IDH wild type, PI3K/AKT-activated, having no PTEN and EGFR mutations. Therefore, the biopsy of brain tumors in such patients is crucial both for accurate diagnosis and material preservation for molecular typing.
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PMID:Malignant Gliomas as Second Neoplasms in Pediatric Cancer Survivors: Neuropathological Study. 2980 74

The epidermal growth factor receptor (EGFR) is a member of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases; it is a transmembrane receptor involved in cell growth and differentiation. EGFR homodimers or heterodimers in combination with other HER members, such as HER2 and HER3, activate downstream signaling cascades in many types of cancer, including oral squamous cell carcinoma (OSCC). The present study produced novel anti-EGFR monoclonal antibodies (mAbs) possessing antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), and investigated antitumor activity. Mice were immunized with an EGFR-overexpressed glioblastoma cell line, LN229 (LN229/EGFR), after which ELISA was performed using recombinant EGFR. mAbs were subsequently selected according to their efficacy for LN229/EGFR, as determined via flow cytometry. After determining the subclass of mAbs, the EMab-17 (IgG2a, kappa) clone exhibited ADCC and CDC activities against two OSCC cell lines, HSC-2 and SAS. Furthermore, EMab-17 exerted antitumor activities against mouse xenograft models using HSC-2 and SAS, indicating that EMab-17 may be used in an antibody-based therapy for EGFR-expressing OSCC.
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PMID:A novel anti-EGFR monoclonal antibody (EMab-17) exerts antitumor activity against oral squamous cell carcinomas via antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity. 3221 34