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)

Four different human tumor cell lines of glial origin have been exposed to a human T lymphotropic retrovirus (HTLV-I). All these cell lines were positive for the glial marker glial fibrillary acidic protein (GFAP). The presence of virus RNA was demonstrated by in situ hybridization using an HTLV-I, SStI-SStI viral insert as probe. Virus expression has been monitored through an indirect immunofluorescence assay using a monoclonal antibody against virus core protein p19. All the four glioma cell lines tested became positive for p19 after 2 weeks of co-cultivation and showed a clear alteration of GFAP expression.
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PMID:Effect of human T lymphotropic retrovirus-I exposure on cultured human glioma cell lines. 188 42

We investigated the production of granulocyte-macrophage colony stimulating factor (GM-CSF) by human T-lymphotropic virus type I (HTLV-I)-infected human glioma cells (KG-1-C and T98G). When glioma cells were co-cultured with HTLV-I-producing T cell lines (HCT-1 and MT-2), GM-CSF was detected in the culture supernatant. GM-CSF was produced in all the co-cultures even after several passages. In co-cultures of KG-1-C and HCT-1 cells with Millicell, the amount of GM-CSF produced in the supernatant was almost as low as in the culture of HCT-1 alone. Moreover, for co-cultures of KG-1-C and HCT-1 or MT-2 cells, the production of GM-CSF was significantly suppressed in the presence of IgG from patients with HAM. Double-label immunostaining showed that GM-CSF-producing glioma cells always were stained by a monoclonal antibody against HTLV-I p19, indicating that HTLV-I infection of glioma cells caused GM-CSF production. These data suggest that human glial cells infected with HTLV-I gain the ability to produce cytokines.
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PMID:Production of granulocyte-macrophage colony stimulating factor by human T-lymphotropic virus type I-infected human glioma cells. 815 17

Tumors of glial origin such as glioblastoma multiforme (GBM) comprise the majority of human brain tumors. Patients with GBM have a very poor survival rate, with an average life expectancy of <1 year. We asked whether we could identify a survival pathway in high-grade glioma and oligodendroglioma cells that when suppressed, would induce apoptosis of these tumor cells but not of normal human adult astrocytes. To identify these pathways, we selectively suppressed the activity of a number of proteins (Ras, Rac1, Akt1, RhoA, c-jun, and MEK1/2) hypothesized to play roles in cell survival. We found that suppression of Rac1, a small GTP-binding protein, inhibited survival and produced apoptosis in three human glioma cell lines (U87, U343, and U373). Serum induced the activity of Rac1 and the activity or phosphorylation state of p21-activated kinase 1 and c-Jun NH(2)-terminal kinase (JNK), two intracellular targets of Rac1. Suppression of Rac1 also induced apoptosis in 19 of 21 short-term cultures of human primary cells from grades II and III oligodendroglioma and grade IV glioblastoma that varied in p53, epidermal growth factor receptor, epidermal growth factor receptor vIII, MDM2, and p16/p19 mutational or amplification status. In contrast, inhibition of Rac1 activity did not induce apoptosis of normal primary human adult astrocytes. In both established glioma cell lines and primary glioma cells, apoptosis induced by the inhibition of Rac was partially rescued by activated mitogen-activated protein kinase kinase 1, an activator of JNK, suggesting that JNK functions downstream of Rac1 in glioma cells. These results indicate that Rac1 regulates a major survival pathway in most glioma cells, and that suppression of Rac1 activity stimulates the death of virtually all glioma cells, regardless of their mutational status. Agents that suppress Rac1 activity may therefore be useful therapeutic treatments for malignant gliomas.
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PMID:Suppression of Rac activity induces apoptosis of human glioma cells but not normal human astrocytes. 1192 35

Ink4a/Arf inactivation and epidermal growth factor receptor (EGFR) activation are signature lesions in high-grade gliomas. How these mutations mediate the biological features of these tumors is poorly understood. Here, we demonstrate that combined loss of p16(INK4a) and p19(ARF), but not of p53, p16(INK4a), or p19(ARF), enables astrocyte dedifferentiation in response to EGFR activation. Moreover, transduction of Ink4a/Arf(-/-) neural stem cells (NSCs) or astrocytes with constitutively active EGFR induces a common high-grade glioma phenotype. These findings identify NSCs and astrocytes as equally permissive compartments for gliomagenesis and provide evidence that p16(INK4a) and p19(ARF) synergize to maintain terminal astrocyte differentiation. These data support the view that dysregulation of specific genetic pathways, rather than cell-of-origin, dictates the emergence and phenotype of high-grade gliomas.
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PMID:Epidermal growth factor receptor and Ink4a/Arf: convergent mechanisms governing terminal differentiation and transformation along the neural stem cell to astrocyte axis. 1208 63

Amplification of the epidermal growth factor receptor (EGFR) or expression of its constitutively activated mutant, DeltaEGFR(2-7), in association with the inactivation of the INK4a/Arf gene locus is a frequent alteration in human glioblastoma. The notion of a cooperative effect between these two alterations has been demonstrated in respective mouse brain tumor models including our own. Here, we investigated underlying molecular mechanisms in early passage cortical astrocytes deficient for p16(INK4a)/p19(Arf) or p53, respectively, with or without ectopic expression of DeltaEGFR(2-7). Targeting these cells with the specific EGFR inhibitor tyrphostin AG1478 revealed that phosphorylation of ERK was only abrogated in the presence of an intact INK4a/Arf gene locus. The sensitivity to inhibit ERK phosphorylation was independent of ectopic expression of DeltaEGFR(2-7) and independent of the TP53 status. This resistance to downregulate the MAPK pathway in the absence of INK4a/Arf was confirmed in cell lines derived from our mouse glioma models with the respective initial genetic alterations. Thus, deletion of INK4a/Arf appears to keep ERK in its active, phosphorylated state insensitive to an upstream inhibitor specifically targeting EGFR/DeltaEGFR(2-7). This resistance may contribute to the cooperative tumorigenic effect selected for in human glioblastoma that may be of crucial clinical relevance for treatments specifically targeting EGFR/DeltaEGFR(2-7) in glioblastoma patients.
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PMID:INK4a/Arf is required for suppression of EGFR/DeltaEGFR(2-7)-dependent ERK activation in mouse astrocytes and glioma. 1527 38

SOX5 is a member of the high-mobility group superfamily of architectural non-histone proteins involved in gene regulation and maintenance of chromatin structure in a wide variety of developmental processes. Sox5 was identified as a brain tumor locus in a retroviral insertional mutagenesis screen of platelet-derived growth factor B (PDGFB)-induced mouse gliomas. Here we have investigated the role of Sox5 in PDGFB-induced gliomagenesis in mice. We show that Sox5 can suppress PDGFB-induced glioma development predominantly upon Ink4a-loss. In human glioma cell lines and tissues, we found very low levels of SOX5 compared with normal brain. Overexpression of Sox5 in human glioma cells led to a reduction in clone formation and inhibition of proliferation. Combined expression of Sox5 and PDGFB in primary brain cell cultures caused decreased proliferation and an increased number of senescent cells in the Ink4a-/- cells only. Protein analyses showed a reduction in the amount and activation of Akt and increased levels of p27(Kip1) upon Sox5 expression that was dominant to PDGFB signaling and specific to Ink4a-/- cells. Upon inhibition of p27(Kip1), the effects of Sox5 on proliferation and senescence could be reversed. Our data suggest a novel pathway, where Sox5 may suppress the oncogenic effects of PDGFB signaling during glioma development by regulating p27(Kip1) in a p19(Arf)-dependent manner, leading to acute cellular senescence.
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PMID:Sox5 can suppress platelet-derived growth factor B-induced glioma development in Ink4a-deficient mice through induction of acute cellular senescence. 1921 70

Glioblastoma (GBM) is the most aggressive and destructive form of brain cancer. Animal models that can unravel the mechanisms underlying its progression are needed to develop rational and effective molecular therapeutic approaches. In this study, we report the development of mouse models for spontaneous gliomas representing distinct progressive stages of disease that are governed by defined genetic alterations. Neural stem/progenitor cell (NPC)-specific constitutive Ras activation in vivo plus p53 deficiency led to development of primarily anaplastic astrocytoma (grade III), whereas combined loss of p53 plus p16(Ink4a)/p19(Arf) led to development of GBM (grade IV) at 100% penetrance within 6 weeks. These glioma models showed enhanced stem cell properties (stemness) accompanied by malignant progression. Notably, we determined that, in our models and in human specimens, downregulation of the homeodomain transcription factor NKX2.2, which is essential for oligodendroglial differentiation, was correlated with increased tumor malignancy. NKX2.2 overexpression by GBM-derived glioma-initiating cells (GIC) induced oligodendroglial differentiation and suppressed self-renewal capacity. By contrast, Nkx2.2 downregulation in mouse NPCs accelerated GBM formation. Importantly, the inhibitory effects of NXK2.2 on GIC self-renewal were conserved in human cells. Thus, our mouse models offer pathobiologically significant advantages to investigate the nature of brain tumors, with improved opportunities to develop novel mechanism-based therapeutic approaches.
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PMID:NKX2.2 suppresses self-renewal of glioma-initiating cells. 2116 5

Glioblastomas frequently harbour genetic lesions that stimulate the activity of mammalian target of rapamycin complex 1 (mTORC1). Loss of heterozygosity of tuberous sclerosis complex 1 (TSC1) or TSC2, which together form a critical negative regulator of mTORC1, is also seen in glioblastoma; however, it is not known how loss of the TSC complex affects the development of malignant gliomas. Here we investigated the role of Tsc1 in gliomagenesis in mice. Tsc1 deficiency up-regulated mTORC1 activity and suppressed the proliferation of neural stem/progenitor cells (NSPCs) in a serial neurosphere-forming assay, suggesting that Tsc1-deficient NSPCs have defective self-renewal activity. The neurosphere-forming capacity of Tsc1-deficient NSPCs was restored by p16(Ink4a)p19(Arf) deficiency. Combined Tsc1 and p16(Ink4a)p19(Arf) deficiency in NSPCs did not cause gliomagenesis in vivo. However, in a glioma model driven by an active mutant of epidermal growth factor receptor (EGFR), EGFRvIII, loss of Tsc1 resulted in an earlier onset of glioma development. The mTORC1 hyperactivation by Tsc1 deletion accelerated malignant phenotypes, including increased tumour mass and enhanced microvascular formation, leading to intracranial haemorrhage. These data demonstrate that, although mTORC1 hyperactivation itself may not be sufficient for gliomagenesis, it is a potent modifier of glioma development when combined with oncogenic signals.
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PMID:Loss of Tsc1 accelerates malignant gliomagenesis when combined with oncogenic signals. 2436 78

Stem cells, believed to be the cellular origin of glioma, are able to generate gliomas, according to experimental studies. Here we investigated the potential and circumstances of more differentiated cells to generate glioma development. We and others have shown that oligodendrocyte precursor cells (OPCs) can also be the cell of origin for experimental oligodendroglial tumors. However, the question of whether OPCs have the capacity to initiate astrocytic gliomas remains unanswered. Astrocytic and oligodendroglial tumors represent the two most common groups of glioma and have been considered as distinct disease groups with putatively different origins. Here we show that mouse OPCs can give rise to both types of glioma given the right circumstances. We analyzed tumors induced by K-RAS and AKT and compared them to oligodendroglial platelet-derived growth factor B-induced tumors in Ctv-a mice with targeted deletions of Cdkn2a (p16(Ink4a-/-), p19(Arf-/-), Cdkn2a(-/-)). Our results showed that glioma can originate from OPCs through overexpression of K-RAS and AKT when combined with p19(Arf) loss, and these tumors displayed an astrocytic histology and high expression of astrocytic markers. We argue that OPCs have the potential to develop both astrocytic and oligodendroglial tumors given loss of p19(Arf), and that oncogenic signaling is dominant to cell of origin in determining glioma phenotype. Our mouse data are supported by the fact that human astrocytoma and oligodendroglioma display a high degree of overlap in global gene expression with no clear distinctions between the two diagnoses.
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PMID:Oncogenic signaling is dominant to cell of origin and dictates astrocytic or oligodendroglial tumor development from oligodendrocyte precursor cells. 2535 17