Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the glycosyl-phosphatidylinositol-anchored molecule-like protein (GML) gene, a p53 target, correlates with the sensitivity of some cancer cell lines to anticancer drugs and ionizing radiation. To investigate the function of GML further, we introduced the GML cDNA into various cancer cell lines under control of the tetracycline-regulated system. When we introduced GML into human glioblastoma cell line T98G, which lacks wild-type p53 and expresses no endogenous GML, we observed significant growth suppression accompanied by G2/M arrest in two independent, stable cell lines. We confirmed induction of apoptosis by fluorescence-activated cell sorting (FACS) analysis and nuclear staining. Our results indicated that GML could induce apoptosis of T98G without functional p53, and implied that GML plays a crucial role in the apoptotic pathway in some cancer cells.
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PMID:Induction of apoptosis in T98G glioblastoma cells by transfection of GML, a p53 target gene. 1052 72

The PTEN tumor suppressor protein inhibits phosphatidylinositol 3-kinase (PI3K)/Akt signaling that promotes translocation of Mdm2 into the nucleus. When restricted to the cytoplasm, Mdm2 is degraded. The ability of PTEN to inhibit the nuclear entry of Mdm2 increases the cellular content and transactivation of the p53 tumor suppressor protein. Retroviral transduction of PTEN into U87MG (PTEN null) glioblastoma cells increases p53 activity and expression of p53 target genes and induces cell cycle arrest. U87MG/PTEN glioblastoma cells are more sensitive than U87MG/PTEN null cells to death induced by etoposide, a chemotherapeutic agent that induces DNA damage. Previously, tumor suppressor proteins have been supposed to act individually to suppress cancers. Our results establish a direct connection between the activities of two major tumor suppressors and show that they act together to respond to stresses and malignancies. PTEN protects p53 from survival signals, permitting p53 to function as a guardian of the genome. By virtue of its capacity to protect p53, PTEN can sensitize tumor cells to chemotherapy that relies on p53 activity. p53 induces PTEN gene expression, and here it is shown that PTEN protects p53, indicating that a positive feedback loop may amplify the cellular response to stress, damage, and cancer.
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PMID:PTEN protects p53 from Mdm2 and sensitizes cancer cells to chemotherapy. 1172 85

To search for p53 target genes throughout the human genome, we applied a cDNA microarray system using adenovirus-mediated transfer of p53 into p53-deficient U373MG (glioblastoma) cells. In this manner, we detected dozens of genes that appeared to be regulated by wild-type p53. We describe here characterization of one such gene, termed CABC1 [chaperone-activity of bc1 complex in Schizosaccharomyces pombe (ABC1)-like], which encodes a 647-amino acid peptide with significant sequence similarity to activity of bc1 complex (ABC1) in Arabidopsis thaliana and S. pombe. The CABC1 product was located in mitochondria, and colony-formation assays with cancer cell lines indicated its ability to suppress cell growth. Inhibition of CABC1 expression by transfection with antisense oligonucleotide significantly reduced the apoptotic response induced by wild-type p53. These results suggest that CABC1 may play an important role in mediating p53-inducible apoptosis through the mitochondrial pathway.
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PMID:Isolation of a novel gene, CABC1, encoding a mitochondrial protein that is highly homologous to yeast activity of bc1 complex. 1188 84

Human astrocytic brain tumors select for mutations in the p53 tumor suppressor gene early in malignant progression. p53 is activated upon various kinds of cellular stress leading to apoptosis or cell cycle arrest, but is also implicated in complex biological processes such as inhibition of angiogenesis and metastasis. In an effort to shed light on consequences mediated by p53 inactivation in gliomas, we established the Tet-On system for p53 in the LN-Z308 glioblastoma cell line. The macrophage inhibitory cytokine-1 (MIC-1) gene was identified as a most prominent p53 target gene upon gene expression profiling. Oxygen deprivation, an important cellular stress, revealed MIC-1 as an anoxia responsive gene in glioblastoma cell lines. MIC-1 up-regulation by anoxia is mediated through an alternative, p53 and hypoxia inducible factor 1 (HIF-1) independent pathway. Furthermore, ectopic expression of MIC-1 in LN-Z308 cell line completely abolished its inherent tumorigenicity in nude mice, while proliferation in vitro was not affected. In the present experimental model MIC-1 may exert its anti-tumorigenic properties via a paracrine mechanism mediated by host cells in vivo. Taken together, these data suggest that MIC-1 is an important downstream mediator of p53 function, while acting itself as an intercessor of cellular stress signaling and exerting anti-tumorigenic activities.
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PMID:Anoxia induces macrophage inhibitory cytokine-1 (MIC-1) in glioblastoma cells independently of p53 and HIF-1. 1208 8

STK17A is a relatively uncharacterized member of the death-associated protein family of serine/threonine kinases which have previously been associated with cell death and apoptosis. Our prior work established that STK17A is a novel p53 target gene that is induced by a variety of DNA damaging agents in a p53-dependent manner. In this study we have uncovered an additional, unanticipated role for STK17A as a candidate promoter of cell proliferation and survival in glioblastoma (GBM). Unexpectedly, it was found that STK17A is highly overexpressed in a grade-dependent manner in gliomas compared to normal brain and other cancer cell types with the highest level of expression in GBM. Knockdown of STK17A in GBM cells results in a dramatic alteration in cell shape that is associated with decreased proliferation, clonogenicity, migration, invasion and anchorage independent colony formation. STK17A knockdown also sensitizes GBM cells to genotoxic stress. STK17A overexpression is associated with a significant survival disadvantage among patients with glioma which is independent of age, molecular phenotype, IDH1 mutation, PTEN loss, and alterations in the p53 pathway and partially independent of grade. In summary, we demonstrate that STK17A provides a proliferative and survival advantage to GBM cells and is a potential target to be exploited therapeutically in patients with glioma.
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PMID:Serine/threonine kinase 17A is a novel candidate for therapeutic targeting in glioblastoma. 2431 60

Chemotherapeutic drug resistance and relapse remains a major challenge for paediatric (medulloblastoma) and adult (glioblastoma) brain tumour treatment. Medulloblastoma tumours and cell lines with mutations in the p53 signalling pathway have been shown to be specifically insensitive to DNA damaging agents. The aim of this study was to investigate the potential of triggering cell death in p53 mutated medulloblastoma cells by a direct activation of pro-death signalling downstream of p53 activation. Since non-coding microRNAs (miRNAs) have the ability to fine tune the expression of a variety of target genes, orchestrating multiple downstream effects, we hypothesised that triggering the expression of a p53 target miRNA could induce cell death in chemo-resistant cells. Treatment with etoposide, increased miR-34a levels in a p53-dependent fashion and the level of miR-34a transcription was correlated with the cell sensitivity to etoposide. miR-34a activity was validated by measuring the expression levels of one of its well described target: the NADH dependent sirtuin1 (SIRT1). Whilst drugs directly targeting SIRT1, were potent to trigger cell death at high concentrations only, introduction of synthetic miR-34a mimics was able to induce cell death in p53 mutated medulloblastoma and glioblastoma cell lines. Our results show that the need of a functional p53 signaling pathway can be bypassed by direct activation of miR-34a in brain tumour cells.
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PMID:Mir-34a mimics are potential therapeutic agents for p53-mutated and chemo-resistant brain tumour cells. 2525 Aug 18

Glioblastoma multiforme (GBM) is an aggressive brain tumour with high resistance to radio- and chemotherapy. As such, increasing attention has focused on developing new therapeutic strategies to improve treatment responses. Recently, attention has been shifted to natural compounds that are able to halt tumour development. Among them, carnosol (CAR), a phenolic diterpene present in rosemary, has become a promising molecule that is able to prevent certain types of solid cancer. However, no data are available on the effects of CAR in GBM. Here, CAR activity decreased the proliferation of different human glioblastoma cell lines, particularly cells that express wild type p53. The p53 pathway is involved in the control of apoptosis and is often impaired in GBM. Notably, CAR, through the dissociation of p53 from its endogenous inhibitor MDM2, was able to increase the intracellular p53 levels in GBM cells. Accordingly, functional reactivation of p53 was demonstrated by the stimulation of p53 target genes' transcription, the induction of apoptosis and cell cycle blockade. Most importantly, CAR produced synergistic effects with temozolomide (TMZ) and reduced the restoration of the tumour cells' proliferation after drug removal. Thus, for the first time, these data highlighted the potential use of the diterpene in the sensitization of GBM cells to chemotherapy through a direct re-activation of p53 pathway. Furthermore, progress has been made in delineating the biochemical mechanisms underlying the pro-apoptotic effects of this molecule.
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PMID:New insights into the anticancer activity of carnosol: p53 reactivation in the U87MG human glioblastoma cell line. 2693 86

OBJECTIVE Glioblastoma multiforme (GBM) is an aggressive brain cancer with median survival of less than 2 years with current treatment. Glioblastomas exhibit extensive intratumoral and interpatient heterogeneity, suggesting that successful therapies should produce broad anticancer activities. Therefore, the natural nontoxic pleiotropic agent, resveratrol, was studied for antitumorigenic effects against GBM. METHODS Resveratrol's effects on cell proliferation, sphere-forming ability, and invasion were tested using multiple patient-derived GBM stem-like cell (GSC) lines and established U87 glioma cells, and changes in oncogenic AKT and tumor suppressive p53 were analyzed. Resveratrol was also tested in vivo against U87 glioma flank xenografts in mice by using multiple delivery methods, including direct tumor injection. Finally, resveratrol was delivered directly to brain tissue to determine toxicity and achievable drug concentrations in the brain parenchyma. RESULTS Resveratrol significantly inhibited proliferation in U87 glioma and multiple patient-derived GSC lines, demonstrating similar inhibitory concentrations across these phenotypically heterogeneous lines. Resveratrol also inhibited the sphere-forming ability suggesting anti-stem cell effects. Additionally, resveratrol blocked U87 glioma and GSC invasion in an in vitro Matrigel Transwell assay at doses similar to those mediating antiproliferative effects. In U87 glioma cells and GSCs, resveratrol reduced AKT phosphorylation and induced p53 expression and activation that led to transcription of downstream p53 target genes. Resveratrol administration via oral gavage or ad libitum in the water supply significantly suppressed GBM xenograft growth; intratumoral or peritumoral resveratrol injection further suppressed growth and approximated tumor regression. Intracranial resveratrol injection resulted in 100-fold higher local drug concentration compared with intravenous delivery, and with no apparent toxicity. CONCLUSIONS Resveratrol potently inhibited GBM and GSC growth and infiltration, acting partially via AKT deactivation and p53 induction, and suppressed glioblastoma growth in vivo. The ability of resveratrol to modulate AKT and p53, as well as reportedly many other antitumorigenic pathways, is attractive for therapy against a genetically heterogeneous tumor such as GBM. Although resveratrol exhibits low bioavailability when administered orally or intravenously, novel delivery methods such as direct injection (i.e., convection-enhanced delivery) could potentially be used to achieve and maintain therapeutic doses in the brain. Resveratrol's nontoxic nature and broad anti-GBM effects make it a compelling candidate to supplement current GBM therapies.
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PMID:Resveratrol targeting of AKT and p53 in glioblastoma and glioblastoma stem-like cells to suppress growth and infiltration. 2741 30

Glioblastoma (GBM) is the most common malignant brain tumor and is associated with a poor prognosis, with most patients living less than a year after diagnosis. Given that GBM nearly always recurs after conventional treatments, there is an urgent need to identify novel molecular targets. Hairless (HR) is a nuclear factor enriched in the skin and has been previously implicated in hair cycling. HR is also highly expressed in the brain, but its significance is unknown. We found that human hairless gene (HR) expression is significantly decreased in all GBM subtypes compared with normal brain tissue and is predictive of prognosis, which suggests that loss of HR expression can contribute to GBM pathogenesis. HR was recently discovered to bind to and regulate p53 responsive elements, and thus we hypothesized that HR may have a tumor suppressive function in GBM by modulating p53 target gene expression. We found that HR indeed regulates p53 target genes, including those implicated in cell cycle progression and apoptosis in the GBM-derived U87 cell line, and restoring HR expression triggered G2/M arrest and apoptosis. An analysis of sequenced genomes from patients with GBM revealed 10 HR somatic mutations in patients with glioma, two of which are located in the histone demethylase domain of HR. These two mutations, P996S and K1004N, were reconstructed and found to have impaired p53 transactivating properties. Collectively, the results of our study suggest that HR has tumor suppressive functions in GBM, which may be clinically relevant and a potential avenue for therapeutic intervention.
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PMID:Hairless regulates p53 target genes to exert tumor suppressive functions in glioblastoma. 3019 1