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

The early events in neoplastic transformation can be understood only by comparison of the neoplastic cell with its nontransformed counterpart. The most common central nervous system gliomas traditionally are thought to arise from mature astrocytes and oligodendrocytes. We examined the possibility that gliomas arise from a population of glia that has properties of oligodendrocyte progenitors. These glial cells express the NG2 chondroitin sulfate proteoglycan and the alpha receptor of platelet-derived growth factor in vivo. We identified NG2 and the alpha receptor of platelet-derived growth factor expression in tissue from seven of seven oligodendrogliomas, three of three pilocytic astrocytomas, and one of five glioblastoma multiforme. These data provide evidence that glial tumors arise from glial progenitor cells. Molecules expressed by these progenitor cells should be considered as targets for novel therapeutics.
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PMID:Expression of oligodendrocyte progenitor cell antigens by gliomas: implications for the histogenesis of brain tumors. 1046 13

The composition and the content of gangliosides changes during physiological growth and differentiation as well as in neoplastic cell transformation. In order to determine if ganglioside profiles correlate with brain tumour malignancy, the ganglioside distribution was determined in 31 gliomas of astrocytic origin and in non-tumour tissue by a recently developed microbore high performance liquid chromatography (HPLC) method. Glioma malignancy was graded according to the grading system proposed by the World Health Organization (WHO) in 1993. In general, an increase of GD3 and a decrease of normal brain gangliosides correlated with a higher grade of malignancy. Pilocytic astrocytomas Grade I had a distinctive ganglioside profile, histologically as well as biochemically. Although they are low-grade gliomas, the pilocytic astrocytomas exhibited a GD3 content comparable to anaplastic gliomas and could only be biochemically distinguished from other tumour grades by relatively high type "b" ganglioside levels. Thus, ganglioside composition not only reflects anaplasia but can also be used to indicate biological characteristics of tumours of different histogenetic origin.
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PMID:Ganglioside profiles in human gliomas: quantification by microbore high performance liquid chromatography and correlation to histomorphology and grading. 1067 6

Insulin-like growth factor I (IGF-I), has a role in cellular differentiation and is also expressed in neoplastic transformation of glioma cells. We recently demonstrated inhibition in expression of cellular IGF-I after transfection with vectors that incodes a segment of the human IGF-I RNA in antisense orientation. The transfected cells expressed increased levels of both MHC-I and B7 molecules. In this paper we show that IGF-I antisense transfected cells also become apoptotic. Moreover, the phenomenon of programmed cell death is related to the phenomenon that results in increased expression of MHC-I and B7 molecules. Co-transfection of rat glioma cells with the vector expressing IGF-I antisense RNA and with vectors encoding the expression of MHC-I and B7 antisense cDNA suppressed the expression of both of these molecules and was associated with a decrease in apoptosis.
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PMID:Expression of insulin-like growth factor-I in rat glioma cells is associated with change in both immunogenicity and apoptosis. 1068 4

The nevus sebaceus syndrome (NSS) is a neurocutaneous disorder characterized by unilateral hyperplasia of skin appendages and skeletal hemihypertrophy, hemimegalencephaly, or hemiatrophy along with disabling seizures. Despite the proneness of the dermal stigmata to eventually undergo neoplastic transformation, the malformative lesions of the central nervous system rarely evolve into frank tumors. We present the case of a 10-year-old girl with left-sided sebaceus nevi, ipsilateral enlargement of the skull, and a desmoplastic neuroepithelial tumor (DNET) in the right fronto-parietal area of the brain. The tumor was removed by surgery. Histologically, it corresponded to a mitotically active small-cell anaplastic astrocytoma with genuine desmoplasia. Investigative methods included immunohistochemical positivity for glial fibrillary acidic protein, lack of expression of neuronal markers, and ultrastructural documentation of sheaths of basal lamina and collagen around tumor cells. A survey of the literature of brain tumors associated with NSS revealed two cases of histologically verified pilocytic astrocytomas, and one each of a choroid plexus papilloma, a mixed glioma, and a meningioma, as well as a subependymal giant cell astrocytoma--the latter possibly in an overlap syndrome of NSS and tuberous sclerosis. We hypothesize that the tumor described herein, one involving both atypical differentiation and enhanced growth potential, is paradigmatic of neuropathological events to be expected in the NSS.
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PMID:Desmoplastic neuroepithelial tumor of infancy in the nevus sebaceus syndrome: report of a unique constellation and review of the literature. 1135 15

Neural precursor cells (NPCs) populate the embryonic ventricular zone and persist in the subependymal zone of the adult brain. We hypothesized that hereditary and/or acquired mutations in apoptosis-associated genes, such as p53 and caspases, may protect NPCs from DNA damage-induced death and predispose them to subsequent neoplastic transformation. To test this hypothesis, we exposed NPCs from wild-type and targeted gene-disrupted mouse embryos (p53, caspase-9, caspase-3, and bax mutants) to ethyl-nitrosourea (ENU), a known DNA mutagen and neural carcinogen, and measured NPC viability. We found that ENU produced caspase-3 activation and apoptotic NPC death 6-24 h after administration both in vivo and in vitro. This effect was critically dependent on p53 and caspase-9 expression. The long-term effect of intrauterine ENU exposure was examined in control and p53-deficient mice. High grade glial tumors were found in 60% of p53(-/-) young adult mice exposed to ENU on gestational day 12.5 but not in p53(+/-) or p53(+/+) littermates or in untreated p53-deficient mice. All the tumors were located supratentorially and possessed strong immunoreactivity for glial fibrillary acidic protein and the anti-apoptotic molecule Bcl-X(L). These results suggest that intrauterine exposure of NPCs to certain DNA damaging agents may synergistically interact with specific genetic abnormalities (e.g. p53 deficiency) to produce glial neoplasms in the adult brain.
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PMID:Neural precursor cell apoptosis and glial tumorigenesis following transplacental ethyl-nitrosourea exposure. 1178 43

Steroid receptors play an important role in homeostasis and in proliferation of neoplastic cells as well. Biological effect of steroid hormone on tissues depends on intracellular concentration of its receptor. The binding hormone with its receptor activates adequate genes in cellular nuclei and cell proliferation. The mutation of genes codifying of receptor protein may cause its structural modification or changes in its activity and lead to neoplastic transformation. The aim of our work was the estimation of progesterone receptors (PR) concentration in cerebral neoplasma and correlation with histopathological type and grade of malignancy of cerebral tumours. We examined 89 patients, among them 28 with meningioma, 43 with glioma and 18 with metastatic tumour. The concentration of PR was evaluated using radioreceptor assay. Our results show statistically significant correlation between expression of PR and type and malignancy of neoplastic tumours. It was especially seen in meningioma and the highest concentration of PR were in I grade tumours.
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PMID:[Correlation of expression of progesterone receptors with histopathological type and grade of malignancy of cerebral neoplasms]. 1193 70

Ceramide represents an important sphingoid mediator involved in the signaling pathways that control cell proliferation, differentiation, and death. To determine whether ceramide levels correlate with the malignant progression of human astrocytomas, we investigated these levels in surgical specimens of glial tumors of low-grade and high-grade malignancy. Tumor samples obtained from 52 patients who underwent therapeutic removal of primary brain tumors were used. The tumors were classified according to standard morphologic criteria and were grouped into tumors of low-grade and high-grade malignancy. Sections of normal brain tissue adjacent to the tumor were also analyzed in 11 of the 52 patients. After extraction and partial purification, ceramide was measured by quantitative derivatization to ceramide-1-phosphate using diacylglycerol kinase and [gamma-(32)P]ATP. Ceramide levels were significantly lower in the combined high-grade tumors compared with low-grade tumors and in both tumor groups compared with peritumoral tissue. The results indicate an inverse correlation between the amount of ceramide and tumor malignancy as assessed by both the histological grading and ganglioside pattern. Moreover, overall survival analysis of 38 patients indicates that ceramide levels are significantly associated with patient survival. The present findings indicate that ceramide is inversely associated with malignant progression of human astrocytomas and poor prognosis. The downregulation of ceramide levels in human astrocytomas emerges as a novel alteration that may contribute to glial neoplastic transformation. The low ceramide levels in high-grade tumors may provide an advantage for their rapid growth and apoptotic resistant features. This study appears to support the rationale for the potential benefits of a ceramide-based chemotherapy.
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PMID:Ceramide levels are inversely associated with malignant progression of human glial tumors. 1211 62

Malignant astrocytomas are common human primary brain tumors that result from neoplastic transformation of astroglia or their progenitors. Here we show that deregulation of the c-Myc pathway in developing astroglia predisposes mice to malignant astrocytomas within 2-3 weeks of age. The genetically engineered murine (GEM) gliomas harbor a molecular signature resembling that of human primary glioblastoma multiforme, including up-regulation of epidermal growth factor receptor and Mdm2. The GEM gliomas seem to originate in an abnormal population of glial fibrillary acidic protein-expressing cells in the ventricular zone and, analogous to human glioblastomas, exhibit molecular and morphological heterogeneity. Levels of connexin 43 in the majority of the tumors are unaltered from normal tissue, indicating that GEM tumors have retained the capacity to establish syncytial networks. In line with this, individual glioma foci are composed of a mixture of actively proliferating cells expressing c-Myc and proliferating cell nuclear antigen and less dividing bystander cells that express glial fibrillary acidic protein and the broad complex tramtrack bric-a-brac/poxvirus and zinc finger domain protein HOF. A subset of the transgenic mice harbored, in addition to brain tumors, vestigial cerebellums in which granule cell migration and radial Bergman glial cell differentiation were disturbed. These observations argue for a window of vulnerability during astrocyte development where c-Myc overexpression is sufficient to trigger the neoplastic process, presumably by inducing the sustained growth of early astroglial cells. This is in contrast to most other transgenic studies in which c-Myc overexpression requires co-operating transgenes for rapid tumor induction.
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PMID:Astroglial c-Myc overexpression predisposes mice to primary malignant gliomas. 1250 Dec 51

The mechanisms of carcinogenesis in nervous tissues are not well understood. It is now established that adenosine 3,',5'-cyclic monophosphate (cAMP)-pathway plays a crucial role in initiating differentiation in transformed and embryonic cells of neuronal and glial origin. Therefore, we propose that defects in the cAMP-pathway may initiate the first phase of carcinogenesis (immortalization). Subsequent genetic abnormalities in oncogenes, anti-oncogenes or other cellular genes individually or in combination may lead to transformation (cancer phenotype). This hypothesis is derived from the fact that an elevation of the cAMP level in murine NB cells induces terminal differentiation in many of these cells in spite of the fact that they are highly aneuploid. Additional changes in cAMP-regulated genes responsible for initiating differentiation may make these cells resistant to cAMP or may make the cAMP-effect on differentiation reversible. Indeed, cAMP-resistant cells exist in NB cell populations, and the cAMP-effect on differentiation is reversible in glioma cells. Identification of genes that initiate, promote and maintain terminal differentiation and those which prevent differentiation following elevation of cAMP in NB cells may increase our understanding of the mechanisms of carcinogenesis. This review illustrates the following: (a) historical background leading to the discovery of cAMP as an inducer of differentiation in nerve cells; (b) identification of potential sites in cAMP-pathway that may play a crucial role in initiating the first phase of carcinogenesis (immortalization) and potential gene targets in immortalized cells whose alterations may cause neoplastic transformation of nerve cells. It is interesting to note that the cAMP pathway remains responsive to an elevated cAMP level in inducing differentiation in NB cells in spite of chromosomal anomalies and genetic changes associated with the maintenance of a cancer phenotype.
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PMID:Defects in cAMP-pathway may initiate carcinogenesis in dividing nerve cells: a review. 1457 64

Children affected with the inherited tumor predisposition syndrome, neurofibromatosis 1 (NF1), are prone to the development of low-grade astrocytic optic pathway tumors (optic pathway glioma [OPG]). Previously, we developed a model of NF1-associated astrocytoma (GFAPCre; Nf1(flox/mut) mice) in which mice develop optic nerve and chiasm glioma. To define the molecular pathogenesis of OPG, we used this mouse model to study the natural history of OPG formation using immunohistological and radiographic approaches. We observed that whereas astrocyte hyperplasia is present in the optic nerves associated with gross optic nerve thickening at 3 weeks of age, overt neoplastic changes were not seen until 2 months of age. Astrocyte proliferation was maximal between 3 weeks and 2 months of age, suggesting that the most rapid period of growth occurs early. Mouse OPG tumors were detected by magnetic resonance imaging at 2 months of age and exhibited contrast enhancement, as seen in human OPG. In addition, the mouse OPG tumors exhibited expression of proteins associated with astroglial progenitors, including nestin and brain lipid binding protein. Last, we observed neovascularization and microglial cell infiltration by 3 weeks of age before overt neoplastic transformation, suggesting that these cellular changes participate in the early stages of tumor formation.
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PMID:Natural history of neurofibromatosis 1-associated optic nerve glioma in mice. 1562 33


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