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)

Effects of hyperthermia on the cell kinetics of glioblastoma cells were investigated using flow cytometry. Pulse-labeling with 5-bromodeoxyuridine (BUdR) and chasing of the labeled cells revealed temporary accumulation of the labeled cells in G2M phase and a reduction of DNA synthesis. The level of cyclin B rises rapidly in G2 phase and falls at the end of mitosis in normal cycling cells. Cyclin B binds to p34cdc2, resulting in histone kinase activity which is necessary for the initiation of mitosis. The amount of p34cdc2 remains constant throughout the cell cycle. The level of cyclin B was measured using an anti-cyclin B antibody and flow cytometry in order to investigate the cause of the G2 accumulation induced by hyperthermia. A low level of cyclin B, in comparison with that of normal cycling cells, persisted for more than 3 h after hyperthermia. These results indicate that the temporary accumulation of cells in G2M phase after hyperthermia may be caused, at least in part, by an insufficient level of cyclin B.
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PMID:Effect of hyperthermia on cyclin B expression in a human glioblastoma cell line. 854 68

The relationship between chromatin structure and endonuclease sensitivity was investigated. The cells used in this study were a) human myelogenous leukemic cell lines (HL-60, ML-I, U-937, THP-I) (Group I), which produced internucleosomal DNA cleavage, and b) human T-cell leukemia (MOLT-4), erythroleukemia (K562), glioblastoma (T98G, U87MG) and glioma (KG-1-C) cell lines (Group II), which produced no internucleosomal DNA cleavage, upon treatment with various apoptosis-inducing agents. When the nuclei, isolated from these cells were digested with micrococcal nuclease, chromatin DNA was cleaved into oligonucleosomal units. Although sensitivity to micrococcal nuclease considerably differed from cell to cell, Group I cells were generally more sensitive to micrococcal nuclease digestion than Group II cells. Similar sensitivity to DNase I was observed in both groups of cells. Acid-urea polyacrylamide gel electrophoresis of histone fractions from control and apoptosing HL-60 cells (induced either by hydrogen peroxide or UV irradiation) revealed no significant change in the relative composition of five major histones, indicating the absence of selective degradation of histone HI, but rather the nonspecific degradation of many nuclear proteins. These data suggest a difference in a chromatin structure between Group I and II cells, which might result in the selective production of internucleosomal DNA cleavage only in Group I cells.
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PMID:Chromatin structure and endonuclease sensitivity in human leukemic cell lines. 870 41

Glioblastoma is a life-threatening tumor in the human brain despite the fact that radio-chemotherapy inducing DNA damage has been improved in the last decade. Various studies focusing on the enhancement of the susceptibility of glioblastoma cells to DNA damage have been reported, which are aimed at more efficient treatment for the tumor. In this study, we show that radioresistant T98G glioblastoma cells can develop sensitivity to DNA damage induced by irradiation and etoposide as a result of the introduction of a DNA repair-associated histone, H2AX. Interestingly, when H2AX-transformed T98G cells were irradiated, Brca1 and Nbs1 were readily recruited in DNA double-strand break (DSB) foci and showed the G2/M-phase arrest of the cell cycle. Moreover, up-regulation of Brca1 was observed in H2AX-T98G cells after exposure to irradiation. Together with the evidence that H2AX transfection does not affect growth activities of non-tumor cells under genotoxic stimuli, this suggests that H2AX gene transfer would provide a new modality for radio-chemotherapy for glioblastomas, probably through overcoming the instability of the genome, and that Brca1 and Nbs1 might be crucial in this methodology.
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PMID:Histone H2AX sensitizes glioma cells to genotoxic stimuli by recruiting DNA double-strand break repair proteins. 1285 79

We investigated the effects of FK228 on cell proliferation and apoptosis against human glioblastoma (GM) T98G, U251MG, and U87MG cells. Upon exposure to FK228, cell proliferation was inhibited, and apoptosis detected by the cleavage of CPP32 was induced. FK228 increased the expression levels of p21 (WAF-1) and of pro-apoptotic Bad protein in all GM cells. Furthermore, FK228 treatment also reduced the anti-apoptotic protein Bcl-xL in all GM cells and anti-apoptotic Bcl-2 in U87MG cells, thereby shifting the cellular equilibrium from life to death. An increased accumulation of histone H4 was detected in the p21 (WAF-1) promoter and the structural gene (exon 2) and the Bad structural gene (exon 2 and 3) upon treatment with FK228, as assessed by chromatin immunoprecipitation (ChIP) assay. Thus, the results indicated that an increased expression of p21 (WAF1) and Bad due to FK228 is regulated, at least in part, by the degree of acetylation of the gene-associated histone. We also found that FK228 inhibits cellular invasiveness and decreases MMP-2 activity. In addition, the growth of transplanted human GM m-3 cells into the subcutaneous tissue of hereditary athymic mice was significantly inhibited, and apoptosis was induced with FK228 treatment. The results suggested that FK228 might be useful in the treatment of human GM, although further studies will be needed.
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PMID:Histone deacetylase inhibitor, FK228, induces apoptosis and suppresses cell proliferation of human glioblastoma cells in vitro and in vivo. 1502 82

High mobility group I-C (HMGI-C) protein is a non-histone DNA-binding factor that organizes active chromatin. This protein is expressed during the limited phase of embryonic development and may regulate the expression of genes critical for embryonic cell growth and differentiation. As embryonic mechanisms are also known to play a role in the development of some neoplasms, we investigated human brain tumors for the expression of HMGI-C to determine its role in the differentiation of glial cell tumors. Immunohistochemical analysis revealed HMGI-C in all of the low-grade astrocytomas, in 2 of 3 anaplastic astrocytomas (grade 3), but in only one of 8 glioblastomas. The results were confirmed at the mRNA level by nested reverse-transcription polymerase chain reaction analyses. Loss of HMGI-C was also demonstrated in a case of glioblastoma transformed from the low-grade astrocytoma strongly expressing HMGI-C protein. These results suggest that HMGI-C may be involved in the differentiation of glial tumor cells, and that loss of HMGI-C expression may contribute to the transformation of low-grade astrocytoma into glioblastoma.
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PMID:High mobility group I-C protein in astrocytoma and glioblastoma. 1549 74

We studied the relationship between proliferative activity and radiation-induced DNA damage in human malignant gliomas in vitro. Nine human glioblastoma established cell lines were gamma-irradiated (60Co) over a dose range of 0-10 Gy. H2B and H4 histone mRNA level was assessed with quantitative RT-PCR technique (TaqMan) and histone labeling index (HLI) with in situ hybridization to define proliferation rate, while cytochalasin-block micronucleus assay was performed to measure cytogenetic damage. Micronucleus frequency correlated with H2B mRNA level (Spearman's R up to 0.82 at 8 Gy), HLI, nuclear division index (NDI) and percentage of binucleated cells (%BNC). There was a high correlation between H2B mRNA level and NDI (R = 0.80) as well as %BNC and HLI (R = 0.72). Histone H2B and H4 mRNA level (not significant), HLI, NDI, and %BNC (significant) were higher in cell lines sensitive to DNA damage. Proliferative activity correlates with radiation-induced DNA damage in human glioma cell lines. Histone H2B mRNA level and HLI may be a useful molecular predictor of the tumour response to radiation treatment in gliomas of the same histological grade, however the risk of potentially more rapid tumour-cell repopulation must be considered. Presumed protective activity of histones against radiation-induced DNA damage was not confirmed at the transcript level.
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PMID:Cell proliferative activity estimated by histone H2B mRNA level correlates with cytogenetic damage induced by radiation in human glioblastoma cell lines. 1573 11

Despite advances in understanding the role of histone deacetylases (HDACs) in tumorigenesis, the mechanism by which HDAC inhibitors mediate antineoplastic effects remains elusive. Modifications of the histone code alone are not sufficient to account for the antitumor effect of HDAC inhibitors. The present study demonstrates a novel histone acetylation-independent mechanism by which HDAC inhibitors cause Akt dephosphorylation in U87MG glioblastoma and PC-3 prostate cancer cells by disrupting HDAC-protein phosphatase 1 (PP1) complexes. Of four HDAC inhibitors examined, trichostatin A (TSA) and HDAC42 exhibit the highest activity in down-regulating phospho-Akt, followed by suberoylanilide hydroxamic acid, whereas MS-275 shows only a marginal effect at 5 microm. This differential potency parallels the respective activities in inducing tubulin acetylation, a non-histone substrate for HDAC6. Evidence indicates that this Akt dephosphorylation is not mediated through deactivation of upstream kinases or activation of downstream phosphatases. However, the effect of TSA on phospho-Akt can be rescued by PP1 inhibition but not that of protein phosphatase 2A. Immunochemical analyses reveal that TSA blocks specific interactions of PP1 with HDACs 1 and 6, resulting in increased PP1-Akt association. Moreover, we used isozyme-specific small interfering RNAs to confirm the role of HDACs 1 and 6 as key mediators in facilitating Akt dephosphorylation. The selective action of HDAC inhibitors on HDAC-PP1 complexes represents the first example of modulating specific PP1 interactions by small molecule agents. From a clinical perspective, identification of this PP1-facilitated dephosphorylation mechanism underscores the potential use of HDAC inhibitors in lowering the apoptosis threshold for other therapeutic agents through Akt down-regulation.
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PMID:Histone acetylation-independent effect of histone deacetylase inhibitors on Akt through the reshuffling of protein phosphatase 1 complexes. 1618 12

Acyloxyalkyl ester prodrugs of histone deacetylase inhibitors, a family of anti-cancer agents, are metabolized intracellularly to acids and aldehyde(s). The purpose of this study was to assess the in vitro and in vivo anticancer activity, selectivity and oral bioavailability of these prodrugs. The prodrugs exhibited a hierarchal potency of AN-193 > or = AN-7 > AN-1 and AN-9 >> AN-10 against murine lung carcinoma (3LLD122) and human breast carcinoma (MCF-7) cell lines. AN-9, and to even greater extent AN-7, displayed preferential cytotoxicity against leukemic and glioblastoma cells compared to their normal cellular counterparts-normal mononuclear and astrocytes cells, respectively. In vivo, anti-metastatic activity was evaluated in a metastatic model of lung cancer in which Lewis lung carcinoma (3LLD122) cells are injected intravenously into C57/BL mice and produce lung nodules. The prodrugs administered orally demonstrated a significant inhibition of lung-lesion formation and their hierarchal potency concurred with that observed in vitro, with the exception of AN-193 that was the least active compound. Escalating doses of AN-7 (5-100 mg/kg), administered by oral or intraperitoneal routes and displayed equivalent anti-metastatic activities, confirmed the good oral bioavailability of AN-7. Consistent with these findings, a time course study of histone acetylation in subcutaneously implanted 3LL122 tumors showed 2-4 fold increases in histone acetylation within 0.5 h of intravenous, intraperitoneal, or oral administration of AN-7 (100 mg/kg). Relative contributions of the prodrug metabolites to the anti-neoplastic activity and the best candidate for clinical studies are discussed.
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PMID:The selectivty and anti-metastatic activity of oral bioavailable butyric acid prodrugs. 1650 48

The product of the MYC oncogene is widely deregulated in cancer and functions as a regulator of gene transcription. Despite an extensive profile of regulated genes, the transcriptional targets of c-Myc essential for transformation remain unclear. In this study, we show that c-Myc significantly induces the expression of the H19 noncoding RNA in diverse cell types, including breast epithelial, glioblastoma, and fibroblast cells. c-Myc binds to evolutionarily conserved E-boxes near the imprinting control region to facilitate histone acetylation and transcriptional initiation of the H19 promoter. In addition, c-Myc down-regulates the expression of insulin-like growth factor 2 (IGF2), the reciprocally imprinted gene at the H19/IGF2 locus. We show that c-Myc regulates these two genes independently and does not affect H19 imprinting. Indeed, allele-specific chromatin immunoprecipitation and expression analyses indicate that c-Myc binds and drives the expression of only the maternal H19 allele. The role of H19 in transformation is addressed using a knockdown approach and shows that down-regulation of H19 significantly decreases breast and lung cancer cell clonogenicity and anchorage-independent growth. In addition, c-Myc and H19 expression shows strong association in primary breast and lung carcinomas. This work indicates that c-Myc induction of the H19 gene product holds an important role in transformation.
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PMID:The c-Myc oncogene directly induces the H19 noncoding RNA by allele-specific binding to potentiate tumorigenesis. 1670 59

In order to enhance the cytotoxicity of radiation, camptothecin (CPT), an inhibitor of DNA topoisomerase I, was added to the cultured glioma cell lines before irradiation (IR). Radiation responses of five glioblastoma cell lines (U87-MG, U373-MG, GHE, GaMG and SNB-19) treated with CPT were analyzed in terms of cell and colony counts, cell cycle progression, expression of histone gamma H2AX, DNA repair protein Rad50, survivin, cleaved caspase 3, p53 and of topoisomerase I. CPT enhanced the radiotoxicity in U87-MG and SNB-19 cell lines if cell and colony counts were used as the end-points. In contrast, pre-treatment with CPT of U373-MG, GHE and GaMG cell lines did not enhance cytotoxicity of IR in terms of cell and colony counts but accelerated DNA damage repair assessed by Rad50 foci. CPT treated glioma cells revealed at least two subpopulations with respect to the expression of histone gamma H2AX, a marker of DNA double-strand breaks. The cell lines tested also differed in the expression of survivin, cleaved caspase 3, p53 and of topoisomerase I. The failure of CPT to enhance the radiotoxicity of glioma U373-MG, GHE and GaMG cell lines in terms of cell and colony counts was found to correlate with accelerated DNA damage repair, and with low expression of topoisomerase I, a target of CPT.
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PMID:Differential response of human glioblastoma cell lines to combined camptothecin and ionizing radiation treatment. 1861 57


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