Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

YKL-40 is a 40 kDa secreted glycoprotein belonging to the family of 'mammalian chitinase-like proteins', but without chitinase activity. YKL-40 has a proliferative effect on fibroblasts, chondrocytes and synoviocytes, and chemotactic effect on endothelium and vascular smooth muscle cells. Elevated YKL-40 levels are found in serum of patients with diseases characterized by inflammation, fibrosis and tissue remodeling. Several studies have reported that high serum YKL-40 levels in patients with cancer are associated with poor prognosis. YKL-40 expression is strongly elevated in serum and biopsy material from glioblastomas patients. We investigated the expression of YKL-40 in three human malignant glioma cell lines exposed to different types of stress. Whereas a polymerase chain reaction transcript was detectable in all three cell lines, only U87 produced measurable amounts of YKL-40 protein. In U87, hypoxia and ionizing radiation induced a significant increase in YKL-40 after 24-48 h. The hypoxic induction of YKL-40 was independent of HIF1. Etoposide, ceramide, serum depletion and confluence all led to elevated YKL-40. Inhibition of p53 augmented the YKL-40 expression indicating that YKL-40 is attenuated by p53. In contrast, both basic fibroblast growth factor and tumor necrosing factor-alpha repressed YKL-40. These are the first data on regulation of YKL-40 in cancer cells. Diverse types of stress resulted in YKL-40 elevation, which strongly supports an involvement of YKL-40 in the malignant phenotype as a cellular survival factor in an adverse microenvironment.
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PMID:Regulation of YKL-40 expression during genotoxic or microenvironmental stress in human glioblastoma cells. 1577 22

Wild-type p53 accumulates in the nucleus following stress. Current models suggest this nuclear accumulation involves phosphorylation at p53 N-terminal sites, and inhibition of murine double minute (MDM)2-dependent nuclear export. We monitored the effects of stress on MDM2-dependent nuclear export of wild-type p53 and a mutant lacking N-terminal phosphorylation sites. Etoposide and ionizing radiation inhibited nuclear export of wild-type p53 and the phosphor-mutant to comparable extents, indicating nuclear export inhibition does not require N-terminal phosphorylation. Cytoplasmic p53 accumulated in the nucleus of transfected cells treated with the nuclear export-inhibitor leptomycin B (LMB). Interestingly, LMB caused less p53 nuclear accumulation than stress treatment, suggesting stress-induced nuclear accumulation of p53 does not result solely from inhibited nuclear export.
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PMID:Control of p53 nuclear accumulation in stressed cells. 1611 32

Protein kinase C (PKC) delta is an essential regulator of mitochondrial dependent apoptosis in epithelial cells. We have used the PKCdelta(-/-) mouse to ask if loss of PKCdelta protects salivary glands against gamma-irradiation-induced apoptosis in vivo and to explore the mechanism underlying protection from apoptosis. We show that gamma-irradiation in vivo results in a robust induction of apoptosis in the parotid glands of wild type mice, whereas apoptosis is suppressed by greater than 60% in the parotid glands of PKCdelta(-/-) mice. Primary parotid cells from PKCdelta(-/-) mice are defective in mitochondrial dependent apoptosis as indicated by suppression of etoposide-induced cytochrome c release, poly(ADP-ribose) polymerase cleavage, and caspase-3 activation. Notably, apoptotic responsiveness can be restored by re-introduction of PKCdelta by adenoviral transduction. Etoposide and gamma-irradiation-induced activation of p53 is similar in primary parotid cells and parotid glands from PKCdelta(+/+) and PKCdelta(-/-) mice, indicating that PKCdelta functions downstream of the DNA damage response. In contrast, activation of the c-Jun amino-terminal kinase is reduced in primary parotid cells from PKCdelta(-/-) cells and in parotid C5 cells, which express a dominant inhibitory mutant of PKCdelta. Similarly, c-Jun amino-terminal kinase activation is suppressed in vivo in gamma-irradiated parotid glands from PKCdelta(-/-) mice. These studies indicate an essential role for PKCdelta downstream of the p53 response and upstream of the c-Jun amino-terminal kinase activation in DNA damage-induced apoptosis in vivo and in vitro.
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PMID:Suppression of apoptosis in the protein kinase Cdelta null mouse in vivo. 1645 85

Deficient mismatch repair (MMR) is identified as a mutation of one of four major MMR genes and(or) microsatellite instability. These genomic changes are used as markers of MMR status of the heredity nonpolyposis colorectal cancer (HNPCC) spectrum tumors--familial and sporadic tumors of colon and extracolonic cancers fulfilling Amsterdam clinical criteria II. MMR-deficiency results in mutator phenotype and resistance to geno- and cytotoxicity of alkylating agents. The main cytotoxic damage to DNA in response to chemical methylation is O6-methylguanine (O6-mG). The secondary DNA strand breaks, which are formed during the MMR functioning, are proposed to be required for methylation induced cytotoxicity. We have assumed that the secondary double stand breaks (DSB) upon DNA methylation are able to represent functional efficiency of MMR in cells. The purpose of the paper was to test this assumption on human tumor cells differing in MMR-status and pulse-treated with methylnitrosourea (MNU). We used 3 cell lines: HeLa (MMR-competent endometrial tumor cells), HCT116 (MMR-deficient colorectal carcinoma cells), and Colo320 (sigmoid intestine tumor cells with uncharacterized MMR status). DSBs were evaluated with neutral comet assay. Cytotoxicity/viability was evaluated with MTT-asay and apoptotic index (frequency of morphologically determined apoptotic cells). We show that 1) cytotoxic effect of MNU (250 microM) on HeLa cells was exhibited 3 days after pulse-treatment of cells with MNU; 2) DSBs occurred 48 h after the drug treatment but prior to the onset of apoptosis of HeLa cells; 3) MMR-deficient HCT116 cells were resistant to the drug: no decreased viability, DSBs and apoptosis were observed during 3 days after cell treatment. Both cell lines exhibited high sensitivity to etoposide, classical inductor of unrepairable DSBs and p53. Etoposide has been found to induce DSBs in 6-12 h, which was followed by apoptosis (in 24 h). Colo320 cells exhibited intermediate position between HeLa and HCT116 cell lines in regard to sensitivity to MNU according to MTT-assay and the number of secondary DSBs formed in MNU-treated cells. Nevertheless, in contrast to HeLa cells, these breaks did not induce apoptosis in Colo320 cells. Our data confirm the assumption about case/effect relationship between secondary DNA double strand breaks, induced by monofunctional methylating agent MNU, and functioning of MMR in human tumor cells.
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PMID:[Comparison of geno- and cytotoxicity of methylnitrosourea on MMR-proficient and MMR-deficient human tumor cell lines]. 1656 31

The human telomerase reverse transcriptase (hTERT) promoter can selectively drive transgene expression in many telomerase-positive human cancer cells. Here we evaluated combination therapy of adenoviral vector Ad-hTERT-CD encoding E. coli cytosine deaminase (CD) driven by the hTERT promoter and low-dose etoposide (0.1 microg/mL) for treating bladder cancer. Ad-hTERT-CD conferred sensitivity to 5-fluorocytosine (5-FC) in bladder cancer cells, which could be enhanced by etoposide treatment, but not in normal cells. Such effect was correlated with up-regulation of hypoxia-inducible factor (HIF)-1alpha expression. By contrast, etoposide activated p53 and down-regulated hTERT promoter activity in normal cells. Etoposide also increased adenoviral infection via enhancement of coxsackie-adenovirus receptor expression on bladder cancer and normal cells. Combination index analysis revealed that combined therapy of Ad-hTERT-CD (10(9) plaque-forming units)/5-FC (200 mg/kg) with etoposide (2 mg/kg) synergistically suppressed tumor growth and prolonged survival in mice bearing syngeneic MBT-2 bladder tumors. This combination therapy regimen induced complete tumor regression and generated antitumor immunity in 75% of tumor-bearing mice. Furthermore, increased infiltrating CD4(+) and CD8(+) T cells and necrosis within tumors were found in mice receiving combination therapy of Ad-hTERT-CD and etoposide compared with those treated with either treatment alone. Thus, the potential high therapeutic index of the combination therapy may be an appealing therapeutic intervention for bladder cancer. Furthermore, because a majority of human tumors exhibit high telomerase activity, adenovirus-mediated CD gene therapy driven by the hTERT promoter in combination with low-dose etoposide may be applicable to a broad spectrum of cancers.
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PMID:Low-dose etoposide enhances telomerase-dependent adenovirus-mediated cytosine deaminase gene therapy through augmentation of adenoviral infection and transgene expression in a syngeneic bladder tumor model. 1704 58

Tumor suppressor p53 protein mediates checkpoint controls and the apoptotic program that are critical for maintaining genomic integrity and preventing tumorigenesis. Forced-induction of MCT-1 decreased p53 expression before and after genomic insults. While inhibiting protein synthesis, the levels of ubiquinated-p53 and the phospho-MDMA2 were significantly increased in ectopic MCT-1 cells. Abrogation of the proteosome degradation process attenuated p53 destabilization and p21 down-regulation by MCT-1. Concomitantly, MCT-1 overexpression enhanced the phosphorylation status of MAPK (ERK1/ERK2). While MCT-1 gene knockdown or MEK/ERK pathway inhibition dramatically reduced MAPK phosphorylation, the genotoxin-induced p53 and p21 production were noticeably elevated. Upon Etoposide treatment, ectopic MCT-1 cells relaxed S-phase and G2/M checkpoints followed by G1 phase progressing. Moreover, cells inducing with MCT-1 abridged accumulations of G2/M populations in the response to gamma-irradiation. The polyploidy (DNA content>4N) populations were increased in association with p53 loss in MCT-1 oncogenic cells. Alkaline comet assay validated that ectopic MCT-1 cells were less susceptibility to the genotoxicity. Furthermore, the allocation of nuclear MCT-1 induced by the genotoxic stress was moderately coincided with gamma-H2AX appearances. Throughout damage-repairing process, ectopic MCT-1 cells displayed many larger chromosomes and multiple chromosomal fusions compared to the controls that showed increase in chromosomal breaks/gaps and minute chromosomal fragments. Spectral karyotyping analysis precisely identified the acquisition of a single extra copy of chromosome 14 together with a complex genome organizations in ectopic MCT-1 cells, including extra copies of chromosome segments that had been translocated to derivative chromosomes 6 [der(6)] and 9 [der(9)]. In conclusion, MCT-1 deregulates p53-p21 network and impairs the damage checkpoints those are robustly connected to oncogenic chromosomal abnormalities.
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PMID:MCT-1 oncogene downregulates p53 and destabilizes genome structure in the response to DNA double-strand damage. 1741 11

Etoposide is a potent inducer of mitotic catastrophe; a type of cell death resulting from aberrant mitosis. It is important in p53 negative cells where p53 dependent apoptosis and events at the G1 and G2 cell cycle checkpoints are compromised. Passenger proteins regulate many aspects of mitosis and siRNA interference or direct inhibition of Aurora B kinase results in mitotic catastrophe. However, there is little available data of clinical relevance in leukaemia models. Here, in p53 negative K562 myeloid leukemia cells, etoposide-induced mitotic catastrophe is shown to be time and/or concentration dependent. Survivin and Aurora remained bound to chromosomes. Survivin and Aurora were also associated with Cdk1 and were shown to form complexes, which in pull down experiments, included INCENP. There was no evidence of Aurora B kinase suppression. These data suggests etoposide will complement Aurora B kinase inhibitors currently in clinical trials for cancer.
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PMID:Cell death in leukemia: passenger protein regulation by topoisomerase inhibitors. 1768 Dec 74

We have established several glioma-relevant oncogene-engineered cancer cells to reevaluate the oncogene-selective cytotoxicity of previously well-characterized anticancer drugs, such as etoposide, doxorubicin, staurosporine, and carmustine. Among several glioma-relevant oncogenes (activated epidermal growth factor receptor, Ras, and Akt, as well as Bcl-2 and p53DD used in the present study), the activated epidermal growth factor receptor, Ras, and Akt exerted oncogenic transformation of Ink4a/Arf(-/-) murine astrocyte cells. We identified that etoposide, a topoisomerase II inhibitor, caused selective killing of myristylated Akt (Akt-myr)-transduced Ink4a/Arf(-/-) astrocytes and U87MG cells in a dose- and time-dependent manner. Etoposide-selective cytotoxicity in the Akt-myr-transduced cells was shown to be caused by nonapoptotic cell death and occurred in a p53-independent manner. Etoposide caused severe reactive oxygen species (ROS) accumulation preferentially in the Akt-myr-transduced cells, and elevated ROS rendered these cells highly sensitive to cell death. The etoposide-selective cell death of Akt-myr-transduced cells was attenuated by pepstatin A, a lysosomal protease inhibitor. In the present study, we show that etoposide might possess a novel therapeutic activity for oncogenic Akt-transduced cancer cells to kill preferentially through ROS-mediated damage.
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PMID:Selective cell death of oncogenic Akt-transduced brain cancer cells by etoposide through reactive oxygen species mediated damage. 1769 15

Interferonalpha (IFNalpha) induces cell cycle arrest and triggers apoptosis and chemosensitivity. But the mechanism of IFNalpha in regulating chemosensitivity has not been fully understood. To study whether IFNalpha affected chemosensitivity of osteosarcoma cells, we treated p53-wild U2OS cells and p53-mutant MG63 cells with IFNalpha and etoposide, alone or in combination, and then examined growth inhibition, cell cycle arrest and apoptosis. IFNalpha enhanced etoposide-induced growth inhibition and apoptosis in p53-wild U2OS cells but not p53-mutant MG63 cells in a dose- and time-dependent manner. Etoposide-induced G2/M phase arrest was also enhanced by IFNalpha. The enhanced apoptosis was associated with the accumulation of transcriptionally active p53 accompanied with increased Bax and Mdm2, as well as decreased Bcl-2. IFNalpha also activated caspases-3, -8 and -9 protein kinases and PARP cleavage in response to etoposide in U2OS cells. Moreover, the combination-induced cytotoxicity and PARP cleavage were significantly reduced by caspase pan inhibitor and p53 siRNA. Thus we conclude that IFNalpha enhances etoposide-induced apoptosis in human osteosarcoma U2OS cells by a p53-dependent and caspase-activation pathway. The proper combination of IFNalpha and conventional chemotherapeutic agents may be a rational strategy for the treatment of human osteosarcoma with functional p53.
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PMID:Interferonalpha enhances etoposide-induced apoptosis in human osteosarcoma U2OS cells by a p53-dependent pathway. 1819 51

Cytotoxic action (tumor cell killing) and carcinogenic side effect (therapy-related secondary leukemia) of etoposide are closely related to its ability in stabilizing topoisomerase II cleavable complex (TOP2cc), a unique form of protein-linked DNA break. How cells process and detect TOP2-concealed DNA damage for the activation of downstream cellular responses remains unclear. Here, we showed proteasomal degradation of both TOP2 isozymes in a transcription-dependent manner upon etoposide treatment. Downregulation of TOP2 was preferentially associated with proteasomal removal of TOP2 in TOP2cc rather than proteolysis of free TOP2. Interestingly, blockage of TOP2 downregulation in TOP2cc also caused reduction in etoposide-induced activation of DNA damage molecules, an observation suggesting that the processing pathways of TOP2cc are involved in activation of etoposide-induced cellular responses. In this regard, we observed two TOP2cc processing pathways, replication- and transcription-initiated processing (RIP and TIP) with proteasome involved in the latter. Importantly, two processing pathways contributed to differential activation of various DNA damage signaling and downstream cellular responses. Etoposide-induced phosphorylation of p53 relied mainly on RIP, whereas activation of Chk1, Chk2 depended largely on TIP. Both RIP and TIP played roles in activating non-homologous end joining pathway, while only RIP modulated etoposide-induced cell killing in a p53-dependent manner. Collectively, our results are consistent with the notion that protein-linked DNA breakage (e.g., TOP2cc) requires processing pathways for initiating downstream DNA damage detection, repair as well as cell death programs.
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PMID:Cellular processing pathways contribute to the activation of etoposide-induced DNA damage responses. 1820 27


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