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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Astrocytomas, including glioblastoma multiforme, represent the most frequent and deadly primary neoplasms of the human nervous system. Despite a number of previous cytogenetic and oncogene studies primarily focusing on malignant astrocytomas, the primary mechanism of tumor initiation has remained obscure. The loss or inactivation of "tumor suppressor" genes are thought to play a fundamental role in the development of many human cancers. Thus, we have analyzed astrocytomas of various histological malignancy grades with polymorphic DNA markers to search for specific chromosomal deletions potentially pointing to loci containing tumor suppressor genes. Loss of constitutional heterozygosity indicating chromosomal loss or deletions was most frequently seen for markers on the short arm of chromosome 17 in 50% of the informative tumors (5 of 10 informative cases) and, to a lesser extent, for markers on chromosomes 1 and 10. Deletions on chromosome 17p were seen in both low-grade and high-grade malignant astrocytomas, suggesting that this chromosome may contain a tumor suppressor gene associated with the early events in tumorigenesis. The common region of deletions on the short arm of chromosome 17 is, therefore, clearly distinct from the gene causing von Recklinghausen neurofibromatosis (NF1), a tumor syndrome associated with glial tumors that maps to the long arm of chromosome 17. The search for progressively smaller deletions on chromosome 17p in astrocytomas may be the way to clone and characterize this locus, thus leading to insights into normal and abnormal growth and differentiation of glial cells.
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PMID:Loss of distinct regions on the short arm of chromosome 17 associated with tumorigenesis of human astrocytomas. 257 Nov 51

Comparative genomic hybridization (CGH) is a recent molecular cytogenetic method that detects and localizes gains or losses in DNA copy number across the entire tumor genome. We used CGH to examine 9 glioma cell lines and 20 primary and 10 recurrent glioblastoma tumors. More than 25% of the primary tumors had gains on chromosome 7; they also had frequent losses on 9p, 10, 13 and Y. The losses on chromosome 13 included several interstitial deletions, with a common area of loss of 13q21. The recurrent tumors not only had gains on chromosome 7 and losses on 9p, 10, 13 and Y but also frequent losses on 6 and 14. One recurrent tumor had a deletion of 10q22-26. Cell lines showed gains of 5p, 7 and Xp; frequent amplifications at 8q22-24.2, 7q21-32 and 3q26.2-29 and frequent losses on 4, 10, 13, 14 and Y. Because primary and recurrent tumors and cell lines showed abnormalities of DNA copy number on chromosomes 7, 10, 13 and Y, these regions may play a fundamental role in tumor initiation and/or progression. The propensity for losses on chromosomes 6 and 14 to occur in recurrent tumors suggests that these aberrations play a role in tumor recurrence, the development of resistance to therapy or both. Analysis of common areas of loss and gain in these tumors and cell lines provides a basis for future attempts to more finely map these genetic changes.
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PMID:Chromosomal abnormalities in glioblastoma multiforme tumors and glioma cell lines detected by comparative genomic hybridization. 789 51

The identification and characterization of genes either induced or repressed in human brain tumors are important in understanding the mechanism of tumor initiation and progression, stages of malignancy, in developing new approaches to the diagnosis and treatment of tumors. In this paper, differential hybridization of arrayed human fetal brain and postnatal brain and postnatal brain cDNA libraries revealed differences in the rate of hybridization signals with total cDNA probes of the human brain and glioblastoma multiforme for more than 150 cDNA clones. Sixteen nucleotide sequences with changed contents in tumors were identified by repeated differential hybridization of the cDNA clones selected by primary screening with the same total cDNA probes of the human brain and glioblastoma multiforme and by Northern-hybridization of RNA samples from the human and glial tumors. The results of an analysis of the increased expression of the gene encoding apolipoprotein E. DNA-binding protein B, mitochondrial (16S and 12S) and cytoplasmic 28S rRNAs, Alu-containing transcripts, inactivation of cullin 1 gene and potential tumor suppressor gene TSC-22 are described.
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PMID:[Role gene expression changes in development of human brain gliomas]. 1221 8

Resveratrol (Res) has been reported to inhibit tumor initiation, promotion, and progression in a variety of cell culture systems depending on the specific cell type and cellular environment. In the present study, we determined the effect of Res on the cell growth and apoptosis of rat glioma C6 cell line as well as mouse fibroblast 3T3 cell line, in vitro. Concurrently, we investigated whether caspase-3 is involved in the Res-induced apoptosis of rat glioma cells. Exposure to Res exhibits a significant anti-proliferative effect and induces an increase in the population of apoptotic cells on C6 cells in a concentration- and time-dependent manner, but not for normal 3T3 fibroblast cells, as measured by methyl thiazolyl tetrazolium assay and flow cytometer. Distinguished increase of C6 cells in S phase is observed after the treatment of Res as compared to insignificant change in cell cycle distribution of 3T3 cells. TdT-mediated dUTP nick end labeling fluorescence staining, HE staining, and scanning electron microscope revealed abnormal morphology and ultrastructure in C6 cells treated with Res. Our data showed that Res can increase the expression and induced the activation of caspase-3 in rat glioma C6 cells. These results suggest that Res has significant apoptosis-inducing effect on C6 glioma cells other than normal fibroblast 3T3 cells in vitro and caspase-3 may act as a potential mediator in the process.
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PMID:Resveratrol inhibits cell growth and induces apoptosis of rat C6 glioma cells. 1703 60

Mounting evidence suggests that gliomas are comprised of differentiated tumor cells and brain tumor stem cells (BTSCs). BTSCs account for a fraction of total tumor cells, yet are apparently the sole cells capable of tumor initiation and tumor renewal. BTSCs have been identified as the CD133-positive fraction of human glioma, whereas their CD133-negative daughter cells have limited proliferative ability and are not tumorogenic. It is well established that the bulk tumor mass escapes immune surveillance by multiple mechanisms, yet little is known about the immunogenicity of the CD133-positive fraction of the tumor mass. We investigated the immunogenicity of CD133-positive cells in two human astrocytoma and two glioblastoma multiforme samples. Flow cytometry analyses revealed that the majority of CD133-positive cells do not express detectable MHC I or natural killer (NK) cell activating ligands, which may render them resistant to adaptive and innate immune surveillance. Incubating CD133-positive cells in interferon gamma (INF-gamma) significantly increased the percentage of CD133-positive cells that expressed MHC I and NK cell ligands. Furthermore, pretreatment of CD133-positive cells with INF-gamma rendered them sensitive to NK cell-mediated lysis in vitro. There were no consistent differences in immunogenicity between the CD133-positive and CD133-negative cells in these experiments. We conclude that CD133-posistive and CD133-negative glioma cells may be similarly resistant to immune surveillance, but that INF-gamma may partially restore their immunogenicity and potentiate their lysis by NK cells.
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PMID:Expression of MHC I and NK ligands on human CD133+ glioma cells: possible targets of immunotherapy. 1707 37

The concept of brain tumor stem cells is gaining increased recognition in neuro-oncology. Until recently, the paradigm of a tumor-initiating stem cell was confined to hematopoietic malignancies where the hierarchical lineages of stem progenitor cells are well established. The demonstration of persistent stem cells and cycling progenitors in the adult brain, coupled with the expansion of the cancer stem cell concept to solid tumors, has led to the exploration of "stemness" within gliomas. Emerging data are highly suggestive of the subsistence of transformed multipotential cells within a glioma, with a subfraction of cells exhibiting increased efficiency at tumor initiation. However, data in support of true glioma stem cells are inconclusive to date, particularly with respect to functional characterization of these cells. Ongoing work aims at the identification of unique pathways governing self-renewal of these putative stem cells and at their validation as ultimate therapeutic targets.
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PMID:Brain tumor stem cells. 1748 87

The cancer stem cell (CSC) hypothesis is predicated on the idea that not all cells have equal proliferative potential and that, in brain tumors, the cells with the greatest ability to proliferate and contribute to tumorigenesis have phenotypic and functional properties similar to normal neural stem cells (NSCs). Over the past few years, multiple investigators have shown that CSCs isolated from human brain tumors (glioma and medulloblastoma) undergo self-renewal and multilineage cell differentiation, similar to normal NSCs. In addition, CSCs from these tumors, when implanted into rodent brains, generate tumors histologically identical to the parental tumors, suggesting that progenitor/stem cells can fully recapitulate the neoplastic phenotype in vivo. While these seminal studies clearly highlight the central role of stem cells in brain tumors, they also evoke important questions regarding the importance of these unique cells to tumor initiation, maintenance and treatment.
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PMID:Cancer stem cells and brain tumors: uprooting the bad seeds. 1802 Sep 26

Malignant gliomas have retained their dismal prognosis despite aggressive multimodal conventional therapeutic approaches, illustrating the need for novel therapeutic strategies. Recent advances in the cellular and molecular biology of gliomas have enhanced our understanding of the role of receptor tyrosine kinases (RTK) and RTK-mediated signal transduction pathways in tumor initiation, maintenance, angiogenesis, and vascular proliferation. Special attention has been focused on targets such as epidermal growth factor receptors (EGFR), platelet-derived growth factor receptors (PDGFR), vascular endothelial growth factor receptors (VEGFR), and on pathways such as the Ras/Raf/mitogen-activated protein (MAP)-kinase and phosphatidylinositol-3 kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathways. Novel targeted drugs known as small molecule inhibitors have been shown to modify the activity of these receptors and signaling pathways. Thus far, however, small molecule RTK inhibitor development has concentrated on a few RTK only, and drug activity has been comprehensively evaluated only in a limited number of different malignancies. One of the limiting factors for novel drug design and development is the incomplete knowledge of RTK functions in malignant glioma. This review summarizes current basic and clinical knowledge on the role of RTK in malignant glioma and on their importance as targets for new forms of therapy.
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PMID:Receptor tyrosine kinases as therapeutic targets in malignant glioma. 1847 93

Malignant gliomas are the most common primary brain tumor in adults, but the prognosis for patients with these tumors remains poor despite advances in diagnosis and standard therapies such as surgery, radiation therapy, and chemotherapy. Progress in the treatment of gliomas now depends to a great extent on an increased understanding of the biology of these tumors. Recent insights into the biology of gliomas include the finding that tyrosine kinase receptors and signal transduction pathways play a role in tumor initiation and maintenance. Deregulation of phosphatidylinositol 3-kinase (PI3K) signaling pathways resulting from genetic alterations in the PTEN tumor suppressor gene on 10q23 at the level of LOH, mutation and methylation have been identified in at least 60% of glioblastoma. Loss of PTEN function by mutation or LOH correlates with poor survival in anaplastic astrocytoma and glioblastoma, suggesting that PTEN plays a role in patient outcome. Interestingly, amplification of Epidermal growth factor receptor (EGFR) in the background of heterozygous PTEN knockout mice develop invasive glioma very similar to human glioblastoma, demonstrating the importance of PTEN in glioma progression and providing a model system to evaluate the efficacy of targeting PTEN in glioblastoma.
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PMID:PTEN signaling pathways in glioblastoma. 1883 94

The recent identification of cancer stem cells (CSCs) in multiple human cancers provides a new inroad to understanding tumorigenesis at the cellular level. CSCs are defined by their characteristics of self-renewal, multipotentiality, and tumor initiation upon transplantation. By testing for these defining characteristics, we provide evidence for the existence of CSCs in a transgenic mouse model of glioma, S100beta-verbB;Trp53. In this glioma model, CSCs are enriched in the side population (SP) cells. These SP cells have enhanced tumor-initiating capacity, self-renewal, and multipotentiality compared with non-SP cells from the same tumors. Furthermore, gene expression analysis comparing fluorescence-activated cell sorting-sorted cancer SP cells to non-SP cancer cells and normal neural SP cells identified 45 candidate genes that are differentially expressed in glioma stem cells. We validated the expression of two genes from this list (S100a4 and S100a6) in primary mouse gliomas and human glioma samples. Analyses of xenografted human glioblastoma multiforme cell lines and primary human glioma tissues show that S100A4 and S100A6 are expressed in a small subset of cancer cells and that their abundance is positively correlated to tumor grade. In conclusion, this study shows that CSCs exist in a mouse glioma model, suggesting that this model can be used to study the molecular and cellular characteristics of CSCs in vivo and to further test the CSC hypothesis.
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PMID:Cancer stem cells are enriched in the side population cells in a mouse model of glioma. 1907 70


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