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)

Cowden disease is an autosomal dominant inherited cancer syndrome characterized by the occurrence of multiple hamartomas, tumors or hyperplastic lesions that may develop in any organ. The disease is related to germline mutation of the PTEN gene, a recently cloned tumor suppressor gene involved in the pathogenesis of sporadic glioblastoma and endometrial carcinoma. It has been shown that the PTEN gene product was a phosphatase able for dephosphorylating a lipid substrate: the phosphatidylinositol (3,4,5)-triphosphate (PIP3). So PTEN appears to negatively control the PI3K-AKT signaling pathway implicated in regulation of cell growth and survival.
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PMID:[Cowden disease and the PTEN gene: a successfully clinical and biological combined approach]. 1179 8

New therapeutic strategies are needed to improve survival in glioblastoma (GBM) the most malignant astrocytic tumor. We evaluated: a) the genetic status of 22 GBMs by comparative genomic hybridization (CGH); b) the specific role of mutation and/or homozygous deletion of PTEN in the genesis of GBM; and c) the possible therapeutic role of PTEN against GBM, in vitro. CGH demonstrated that the most frequent region of gain was at chromosome 7p, whereas the most frequent losses occurred at chromosomes 10q and 13q. Losses at chromosome 10 were found in 36% of patients, and PTEN was mutated in 27% of the 22 GBMs, including 4 point mutations and 2 homozygous deletions. The possible therapeutic role of PTEN in GBM was also studied in a system based on retroviral infection of the GBM cell line A172, homozygously deleted at the PTEN locus. A172 growth and proliferation rate were reduced by 50% after PTEN transduction. Moreover, we showed that inhibition of cell growth occurred through the PI3K/Akt/p27 pathway. Our findings suggest that PTEN participates in the genesis of GBM, and might be further studied as a candidate therapeutic agent in other testing systems.
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PMID:Genetic profile, PTEN mutation and therapeutic role of PTEN in glioblastomas. 1237 Jul 66

Major advances in molecular biology, cellular biology and genomics have substantially improved our understanding of cancer. Now, these advances are being translated into therapy. Targeted therapy directed at specific molecular alterations is already creating a shift in the treatment of cancer patients. Glioblastoma (GBM), the most common brain cancer of adults, is highly suited for this new approach. GBMs commonly overexpress the oncogenes EGFR and PDGFR, and contain mutations and deletions of tumor suppressor genes PTEN and TP53. Some of these alterations lead to activation of the P13K/Akt and Ras/MAPK pathways, which provide targets for therapy. In this paper, we review the ways in which molecular therapies are being applied to GBM patients, and describe the tools of these approaches: pathway inhibitors, monoclonal antibodies and oncolytic viruses. We describe strategies to: i) target EGFR, its ligand-independent variant EGFRvIII, and PDGFR on the cell surface, ii) inhibit constitutively activate RAS/MAPK and PI3K/Akt signaling pathways, iii) target TP53 mutant tumors, and iv) block GBM angiogenesis and invasion. These new approaches are likely to revolutionize the treatment of GBM patients. They will also present new challenges and opportunities for neuropathology.
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PMID:Targeted molecular therapy of GBM. 1258 May 45

The granulin-epithelin precursor, progranulin, PC-cell-derived growth factor or acrogranin, is a high molecular weight secreted mitogen. It is abundantly expressed in rapidly cycling epithelial cells, in the immune system and in neurons, such as cerebellar Purkinje cells. Progranulin contributes to tumorigenesis in diverse cancers, including breast cancer, clear cell renal carcinoma, invasive ovarian carcinoma and glioblastoma. It regulates the rate of epithelial cell division in responsive epithelial cells, and confers an invasive phenotype on these cells. It is involved in the wound response. During embryogenesis, progranulin accelerates blastocyst formation, and is a growth factor for trophectodermal cells. In the neonate, progranulin, regulates the hormone-dependent virilization of the hypothalamus. It activates phosphorylation of Shc, and p44/42 MAPK (mitogen activated protein kinase) in the ERK (extracellular regulated kinase) signaling pathway; PI3K (phosophatidyl inositol-3-kinase), AKT/protein kinase B, and p70S6kinase in the phosophatidyl inositol-3-kinase pathway; and focal adhesion kinase in the adhesion/motility pathway. The signaling properties of progranulin are apparently similar to those of classic growth factors, but the functional properties of progranulin distinguish it from these molecules. Deleting the insulin-like growth factor I receptor from murine embryonic fibroblasts blocks proliferation in response to all classic growth factors, such as epidermal growth factor, or platelet-derived growth factor, whereas progranulin retains mitotic activity on these cells. The defined biological actions of progranulin probably represent a small fraction of its overall functions. Transcriptome analyses show that the progranulin gene is induced in numerous situations that vary from obesity to the transcriptional response of cells to antineoplastic drugs. Here, the biological roles of progranulin will be reviewed, with an emphasis on cancer and cell proliferation.
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PMID:Progranulin (granulin-epithelin precursor, PC-cell derived growth factor, acrogranin) in proliferation and tumorigenesis. 1297 94

With tendency to invade rapidly in the brain, malignant gliomas are very resistant to conventional therapies including radiation and chemotherapy. Recent advances in genetic and molecular techniques have made it possible to define characteristic molecular profiles of malignant gliomas. Based on the list of the molecules closely related to glioblastoma tissues, we reviewed strategies targeting them. Target molecules extensively studied include EGFR, PTEN, telomerase and signal pathway modulators for Ras/Raf/MAPK and PI3K/Akt/mTOR pathways. Therapies targeting specific molecules may result in killing tumor cells effectively while keeping normal cells intact.
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PMID:Molecular targeting for malignant gliomas (Review). 1506 31

FoxO Forkhead transcription factors are shown here to act as signal transducers at the confluence of Smad, PI3K, and FoxG1 pathways. Smad proteins activated by TGF-beta form a complex with FoxO proteins to turn on the growth inhibitory gene p21Cip1. This process is negatively controlled by the PI3K pathway, a known inhibitor of FoxO localization in the nucleus, and by the telencephalic development factor FoxG1, which we show binds to FoxO-Smad complexes and blocks p21Cip1 expression. We suggest that the activity of this network confers resistance to TGF-beta-mediated cytostasis during the development of the telencephalic neuroepithelium and in glioblastoma brain tumor cells.
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PMID:Integration of Smad and forkhead pathways in the control of neuroepithelial and glioblastoma cell proliferation. 1508 59

Resistance to chemotherapy is a common feature of malignant gliomas. This resistance is mediated by receptor tyrosine kinase (RTK)-regulated signaling. p21-Ras protein is pivotal in the propagation of the signal originated from many RTKs. Our aim was to investigate whether inhibition of Ras pathway affects the response to cisplatin in malignant gliomas. We found an enhanced sensitivity to cisplatin of two glioblastoma cell lines expressing dominant negative Ras. Moreover, DN-Ras expressing cells, implanted in nude mice, resulted in being extremely sensitive to cisplatin. The growth of all the tumors was significantly inhibited by combining DN-Ras adenovirus infection with cisplatin treatment. The majority of glioma cells expressing DN-Ras underwent apoptosis in response to cisplatin. In vivo, DN-Ras alone did not influence the growth of tumors, suggesting that the effects of Ras-inhibition observed in vitro could not be extrapolated in vivo. The survival signal pathway transduced by Ras was essentially mediated by inhibition of caspase-9 cleavage via PI3K/Akt.
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PMID:Ras inhibition amplifies cisplatin sensitivity of human glioblastoma. 1521 56

Genetic alterations of PI3K (phosphoinositide 3-kinase) subunits have been documented in a number of tumor types, with increased PI3K activity linked to gene amplification and mutation of catalytic subunits, as well as mutations of regulatory subunits. Among high grade gliomas, activation of the PI3K-AKT signaling pathway through loss of PTEN function is common. We therefore investigated whether genetic alteration of class IA PI3Ks might provide a mechanism for deregulation of this pathway in glioblastomas. We studied a series of glioblastomas with FISH to assess copy number of catalytic subunits (PIK3CA and PIK3CD) and with PCR-SSCP to screen for somatic mutations of conserved regions of both catalytic and regulatory subunits. FISH revealed frequent balanced copy number increases of both PIK3CA and PIK3CD, and one case showed an extra copy limited to PIK3CA. One glioblastoma exhibited a 9-bp deletion that encompassed the exon-intron junction of exon 12 of PIK3R1, documenting for the first time a mutation within a PI3K regulatory subunit in human glioblastoma. This deletion would be predicted to yield a truncated protein that lacks the inhibitory domain, resulting in increased PI3K activity. Furthermore, the case with selected PIK3CA copy number gain and the case with a truncating PIK3R1 mutation both featured AKT activation without PTEN mutation. These results suggest that genetic alterations of class IA PI3K subunit genes can occasionally play a role in human glioblastoma by activating the PI3K-AKT signaling pathway independently of PTEN mutation.
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PMID:Genetic alterations of phosphoinositide 3-kinase subunit genes in human glioblastomas. 1560 84

Glioblastoma multiforme WHO grade IV is the most common and malignant variant of astrocytic tumors. Loss of heterozygosity of chromosome 10 and mutations in the tumor suppressor gene PTEN on 10q are molecular hallmarks of glioblastomas. Recently, mutations were identified in PIK3CA, encoding a protein that antagonizes the function of PTEN protein in the PI3K/Akt pathway. To address the question whether an exclusive mutation pattern can be observed in PIK3CA and PTEN, we determined the frequency of mutations in both genes. All coding exons were examined by single strand confirmation polymorphism and direct sequencing. Additionally, we analyzed chromosome 10 for loss of heterozygosity and evaluated the mutational status of TP53. In 70 glioblastomas, 5 (7%) PIK3CA mutations and 10 (14%) PTEN mutations were found. All mutations in PIK3CA located to exons 1, 9 and 20, thereby supporting the concept of mutational hot spot regions. In all but one glioblastoma, mutations were seen either in PIK3CA or in PTEN. In conclusion, the frequency of PIK3CA mutations in glioblastomas appears to be much lower than initially reported.
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PMID:PIK3CA mutations in glioblastoma multiforme. 1592 53

The PTEN tumor suppressor is a central negative regulator of the PI3K/AKT signaling cascade that influences multiple cellular functions including cell growth, survival, proliferation and migration in a context-dependent manner. Dysregulation of this signaling pathway contributes to many cancers in man. PTEN is the most commonly altered component of the PI3K pathway in human malignancies. Mutations occur in both heritable and sporadic settings, with high frequency in sporadic glioblastoma, prostate and endometrial cancer. Data from human tumors and animal models support the concept that the effects of PTEN inactivation are tissue-specific. Elucidation of the mechanisms regulating activation of unique downstream effectors that mediate distinct outcomes of PTEN loss will augment our understanding of tumorigenesis and ultimately lead to novel therapeutic options.
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PMID:PTEN function in normal and neoplastic growth. 1641 71


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