Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations of the TP53 tumor suppressor gene have been associated with poor survival in some series of diffuse large B-cell lymphoma (DLBCL) but not in other studies. The purpose of this study was to identify the frequency of TP53 alterations (mutations or deletions), characterize the gene expression of mutant/deleted cases, and determine the effects of mutations on survival. In a series of DLBCL that had previous gene expression profiling, we identified 24 mutations in 113 cases (21%). There was no difference in the frequency of mutations in the molecular subgroups of DLBCL. Twelve (50%) of the 24 cases had mutations localized to the DNA-binding codons in the core domain of TP53. The presence of any TP53 mutation correlated with poor overall survival (OS; P = .044), but DNA-binding mutations were the most significant predictor of poor OS (P < .001). Multivariate analysis confirmed that the International Prognostic Index, tumor size, and TP53 DNA-binding mutations were independent predictors of OS. Gene expression analysis showed that TRAILreceptor-2 (DR5) was the most differentially underexpressed gene in the TP53 mutated cases. Investigation is warranted into targeted therapy toward TRAIL receptor-2, to potentially bypass the adverse effect of mutated TP53 in DLBCL.
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PMID:Mutations in the DNA-binding codons of TP53, which are associated with decreased expression of TRAILreceptor-2, predict for poor survival in diffuse large B-cell lymphoma. 1788 37

We investigated the effect of a novel histone deacetylase inhibitor, A-423378.0, on the colon carcinoma cell line HCT116 and genetically modified derivatives lacking either p21(cip1/waf1) or p53. HCT116 cell lines were incubated with A-423378.0 at different concentrations for 3-120 h. Cell viability, proliferation and apoptosis rates were determined and verified by western blot, detection of mitochondrial membrane potential breakdown DeltaPsi(m), activation of caspases-3, -8 and cytokeratin 18 cleavage. A subcutaneous xenograft model was established in NMRI mice with daily intraperitoneal injections of 10 mg/kg for 14 days. All three HCT116 cell lines responded to A-423378.0 treatment in a dose- and time-dependent manner via induction of apoptosis as measured by breakdown of DeltaPsi(m) and BrdU incorporation. We identified that A-423378.0 induced the expression of TRAIL and TRAIL receptor, especially TRAIL-R2/hDR5, which was up-regulated in HCT116 cells after treatment with A-423378.0. In vivo, a growth inhibitory effect was observed with HDAC-I treatment, which was paralleled by a down-regulation of PCNA and a concomitant induction of apoptosis. Treatment of wild-type or knock-out HCT116 cells with A-423378.0 exerts potent anti-proliferative and pro-apoptotic effects in vitro and in vivo. A-423378.0 was able to induce apoptosis in both p21(WAF1) and p53 deficient tumour cells, which appeared to be mediated by the intrinsic cell death pathway. Interestingly, the effects of A-423378.0 on the extrinsic cell death pathway through activation of TRAIL and its signalling pathway indicate that A-423378.0 may be a potent new therapeutic compound for the treatment of advanced colorectal cancer.
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PMID:Differential response of p53 and p21 on HDAC inhibitor-mediated apoptosis in HCT116 colon cancer cells in vitro and in vivo. 1798 66

Glutathione (GSH) depletion is widely used to sensitize cells to anticancer treatment inducing the progression of programmed cell death and overcoming chemoresistance. It has been reported that neuroblastoma cells with MYCN amplification are unable to start TRAIL-dependent death and MYCN, in concert with cytotoxic drugs, efficiently induces the mitochondrial pathway of apoptosis through oxidative mechanisms. In this study, we show that GSH loss induced by L-buthionine-S,R-sulfoximine (BSO), an inhibitor of GSH biosynthesis, leads to overproduction of reactive oxygen species (ROS) and triggers apoptosis of MYCN-amplified neuroblastoma cells. BSO susceptibility of SK-N-BE-2C, a representative example of MYCN-amplified cells, has been attributed to stimulation of total SOD activity in the absence of changes in the level and the activity of catalase. Therefore, the unbalanced intracellular redox milieu has been demonstrated to be critical for the progression of neuroblastoma cell death that was efficiently prevented by antioxidants and rottlerin. These results describe a novel pathway of apoptosis dependent on ROS formation and PKC-delta activation and independent of p53, bcl-2, and bax levels; the selective redox modulation of PKC-delta might be suggested as a potential strategy for sensitizing MYCN-amplified cells to therapeutic approaches.
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PMID:Mechanisms of BSO (L-buthionine-S,R-sulfoximine)-induced cytotoxic effects in neuroblastoma. 1799 46

Survivin, a member of the inhibitor of apoptosis protein family, is involved in both, inhibition of apoptosis and regulation of cell division. Because of the tumor-specific expression of survivin, the reduction of its expression is an important therapeutic option in the treatment of malignant diseases. Thus, we analyzed the transcriptional regulation of survivin in order to establish survivin as a target gene for new therapeutic approaches. Here, we describe a novel regulatory region within the survivin promoter. After treatment with phorbol 12-myristate-13-acetate, the early growth response (Egr)-1 transcription factor binds to the sequence 5'GAGGGGGCG 3' within the human survivin promoter in vitro and in entire cells. In reporter-gene assays and overexpression experiments, survivin is downregulated following exogenous expression of wildtype Egr-1. Using p53 wildtype and mutated cell lines, we show that Egr-1 negatively regulates survivin expression and sensitizes cell lines to TRAIL-induced apoptosis.
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PMID:Transcriptional regulation of human survivin by early growth response (Egr)-1 transcription factor. 1802 54

Smac/DIABLO is a recently identified protein released from mitochondria in response to apoptotic stimuli and promotes apoptosis by antagonizing inhibitor of apoptosis proteins (IAPs). In this study, we observed depressed Smac/DIABLO and increased XIAP expression in ovarian epithelial tissues ordered by normal, benign and malignant epithelia. In epithelial ovarian cancer (EOC), the expression of Smac/DIABLO decreased with the malignancy. Smac/DIABLO expression showed no correlation with TRAIL sensitivity, while lower Smac/DIABLO expression and decreased release of Smac/DIABLO from mitochondria upon apoptosis stimuli were observed in paclitaxel-resistant A2780/pac cells as compared to the sensitive controls. Ectopic Smac/DIABLO alone inhibited cell growth, arrested cells in G0/G1 phase, and sensitized drug-resistant EOC cells to TRAIL or paclitaxel-induced apoptosis. Increased apoptosis was associated with the down-regulation of XIAP, FLIP, and up-regulation of Smac/DIABLO, cytochrome c, p53, along with increased activity of caspase-3. Thus, over-expression of Smac/DIABLO is a promising strategy for drug-resistant ovarian cancer treatment.
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PMID:Transfection of Smac/DIABLO sensitizes drug-resistant tumor cells to TRAIL or paclitaxel-induced apoptosis in vitro. 1802 93

Human granulosa tumor cell (GCT) lines (KGN and COV434) were utilized to establish the combinatorial effects of TRAIL treatment and a proteasome inhibitor on cell viability, in vitro. TRAIL induced a slight, but consistent, decrease in viability for both cell lines, and pharmacologic inhibition of proteasome activity, using Z-LLF-CHO (Z-LLF), synergistically enhanced TRAIL-induced loss of viability. This enhanced sensitization was associated with the up-regulation of a TRAIL receptor, DR5, and pro-apoptotic Bax. Targeted reduction of p53 expression revealed that the ability of Z-LLF to enhance DR5 and Bax expression occurs independent of p53 activity. These studies underscore the potential to develop targeted treatments for GCTs using established cell lines.
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PMID:Inhibition of proteasome activity sensitizes human granulosa tumor cells to TRAIL-induced cell death. 1803 28

Cancers of the lung and pleura remain a major cause of cancer deaths, both in men and women, with strong causal relationships between cigarette smoking and asbestos fibres, and deaths from lung cancer and mesothelioma, respectively. The poor survival rates for small cell lung cancer and mesotheliomas argue powerfully for greater understanding of mechanisms of carcinogenesis, genetic abnormalities and the role of tumour suppressor genes and proteins in carcinomas of the lung and pleura. Despite progress in the development of newer cytotoxic drugs, lung cancer remains a lethal disease. Chemotherapy and radiotherapy produce only a modest improvement in survival of patients with advanced disease. Increased knowledge of molecular mechanisms of lung cancer and apoptosis are providing opportunities for treating lung cancer with new classes of molecularly targeted drugs. These novel therapies should target the abnormalities in lung cancer by maximizing the effects of anti-tumour molecules, with minimal side effects on normal tissues. Of the several molecular targets, those receiving attention are p53 gene replacement, Bcl-2 downregulation, apoptosis by induced by TNF, the FAS/CD95 receptor system and TRAIL, and inhibition of NF-kappaB. Although several studies have shown benefits, there is a need for well planned clinical trials of drugs that target the apoptotic cascade. Stem cell therapy and gene replacement offer the prospect of novel approaches that are likely in the near future to play a definitive role in the treatment of advanced lung cancer. Furthermore, with their apparent minimal toxicity to normal tissues, the newer molecular targets represent attractive investigational directions for innovative cancer therapies.
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PMID:Molecular genetics and mechanisms of apoptosis in carcinomas of the lung and pleura: therapeutic targets. 1803 30

We have compared the cytotoxic/cytostatic responses of the SKW6.4 lymphoblastoid B-cells to the alkylating agent chlorambucil, the purine analog fludarabine, the non-genotoxic activator of the p53 pathway, Nutlin-3, used alone or in association with the death-inducing ligand recombinant TRAIL. Exposure to chlorambucil, fludarabine, and Nutlin-3 induced p53 accumulation and variably affected cell cycle progression in SKW6.4 lymphoblastoid cells. In particular, chlorambucil induced cell cycle accumulation at the G2/M checkpoint; Nutlin-3 induced early cell cycle arrest at the G1/S checkpoint, while fludarabine showed an intermediate behavior. On the other hand, recombinant TRAIL alone did not affect cell cycle progression but induced a rapid increase of apoptosis. Analysis of the gene expression profile of the p53-transcriptional targets showed distinct features between chlorambucil, Nutlin-3 and fludarabine, which likely account for their differential effect on cell cycle in SKW6.4 cells. In particular, chlorambucil upregulated the steady-state mRNA expression of SFN/14-3-3sigma, a gene involved in G2/M cell cycle arrest. Of note, all agonists upregulated TRAIL-R2 expression in SKW6.4 cells both at the mRNA and protein levels. Consistently, pretreatment with chlorambucil, fludarabine and Nutlin-3 enhanced SKW6.4 sensitivity to TRAIL-mediated apoptosis.
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PMID:Differential effects of chemotherapeutic drugs versus the MDM-2 antagonist nutlin-3 on cell cycle progression and induction of apoptosis in SKW6.4 lymphoblastoid B-cells. 1809 40

Murine macrophage death upon infection with Listeria monocytogenes was previously shown to be increased by beta interferon, produced by the infected cells. We saw that interferon-upregulated caspase activation or other interferon-inducible, death-associated proteins, including TRAIL, protein kinase R, and p53, were not necessary for cell death. Macrophage death was reduced when inducible nitric oxide synthase (iNOS) was inhibited during infection, and iNOS-deficient macrophages were less susceptible to death upon infection than wild-type cells. The production of nitric oxide correlated with increased death, while no role was seen for iNOS in control of Listeria numbers during infection of resting macrophages. This indicates that the induction of iNOS by beta interferon in cells infected with L. monocytogenes contributes to cell death. Based on morphology, the maintenance of mitochondrial membrane potential, and a lack of dependence on caspase 1, we characterize the type of cell death occurring and show that infected macrophages die by interferon-upregulated necrosis.
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PMID:Stimulation of inducible nitric oxide synthase expression by beta interferon increases necrotic death of macrophages upon Listeria monocytogenes infection. 1826 32

Protein kinase C epsilon (PKC epsilon ) acts as an antiapoptotic protein and inhibits tumor necrosis factor-alpha (TNF)-related apoptosis-inducing ligand (TRAIL)-induced apoptosis in MCF-7 breast cancer cells. Members of the TNF receptor superfamily trigger apoptosis independent of the tumor suppressor protein p53, which primarily affects DNA damage-induced apoptosis. We have previously shown that PKC epsilon acts upstream of Akt to inhibit receptor-initiated cell death. Since Akt can regulate p53, we have examined the involvement of p53 in PKC epsilon-mediated TRAIL resistance. Overexpression of PKC epsilon in MCF-7 cells (MCF-7/PKC epsilon ) caused a decrease in p53 and an increase in human homolog of murine double minute 2 (Hdm2) and phospho-Hdm2. Depletion of p53 by siRNA attenuated, whereas depletion of Hdm2 enhanced TRAIL-mediated apoptosis. Knockdown of Akt decreased Hdm2 phosphorylation, increased p53 level and potentiated TRAIL-induced cell death. Depletion of epsilon from MCF-7 cells caused an increase in p53, whereas knockdown of p53 caused a decrease in Bid mRNA. Depletion of Akt from MCF-7/PKC epsilon cells resulted in an increase in p53 and Bid. These results suggest that PKC epsilon mediates TRAIL resistance by Akt-mediated phosphorylation of Hdm2 resulting in suppression of p53 expression and downregulation of Bid in MCF-7 breast cancer cells.
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PMID:Protein kinase C epsilon confers resistance of MCF-7 cells to TRAIL by Akt-dependent activation of Hdm2 and downregulation of p53. 1831 51


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