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)

Recent studies have shown the antiapoptotic activity of clusterin against a wide variety of stimuli; however, the functional role of clusterin in Fas-mediated apoptosis has not been well characterized. We transfected the clusterin cDNA into human renal-cell carcinoma (RCC) ACHN cells that scarcely express clusterin protein in order to examine whether overexpression of clusterin inhibits the Fas-mediated signal pathway for apoptotic cell death. No significant difference was observed in the in vitro cell growth rates between the clusterin-transfected cell line (ACHN/CL) and the vector-only-transfected control cell line (ACHN/C), whereas the colony-forming efficiency in soft agar of ACHN/CL was significantly higher than that of ACHAN/C. The anti-Fas monoclonal antibody CH11 induced apoptosis in ACHAN/C cells in a dose-dependent manner; however, the growth-inhibitory effect of CH11 on ACHN/CL cells was markedly suppressed, with corresponding increases in p53 expression and decrease in the fraction of cells in the sub-G(1) phase of the cell cycle. Furthermore, the cytotoxic effect of CH11 on ACHN/CL cells was augmented by treatment with interferon-gamma, but a corresponding effect on ACHN/C cells was not observed. These findings suggest that overexpression of clusterin may contribute to a phenotype resistant to Fas-mediated apoptosis, and that if interferon-gamma treatment is added according to the clusterin expression level, Fas-mediated therapy could be a novel approach to RCC.
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PMID:Acquisition of resistance to Fas-mediated apoptosis by overexpression of clusterin in human renal-cell carcinoma cells. 1169 May 57

Interferon-gamma induces an irreversible growth arrest and squamous differentiation in normal human epidermal keratinocytes. We present for the first time a careful biochemical analysis of the cell-cycle-related events that occur during interferon-gamma treatment of normal human epidermal keratinocytes. The interferon-gamma-induced irreversible growth arrest state is characterized by inhibition of cyclin-dependent kinases, prevention of Rb and p130 (Rb2) phosphorylation, and increases in p27(Kip1), p16(Ink4a), and p130 proteins, together with a transient increase in p21(Waf1/Cip1). Cells derived from squamous cell carcinomas are less responsive to interferon-gamma and do not terminally differentiate. We exploited these differences in response to interferon-gamma in order to identify the particular molecular defects in cell cycle control that promote carcinogenesis in squamous epithelia. In several squamous cell carcinoma cell lines as well as in interferon-gamma-insensitive HaCaT cells, interferon gamma was unable to significantly induce levels of p130 and/or p16 protein. In addition, p21 association with cdk2 complexes was undetectable in either the absence or the presence of interferon-gamma and, unlike normal human epidermal keratinocytes, p27 association with cdk2 did not increase with interferon-gamma treatment. These multiple defects appear to be intrinsic to the mechanisms of cell cycle regulation rather than due to defects in the interferon-gamma signaling pathway, as induction of several interferon-gamma-responsive genes including Stat 1, IRF-1, and p21 itself was normal. Interestingly, exogenous expression of p21 protein in the squamous cell carcinoma cell lines by adenovirus carrying wildtype p53 or p21 cDNA cooperated with interferon-gamma to produce a greater inhibition of growth than either agent alone, even though p21 protein could barely be detected in cdk2 complexes. We conclude that squamous cell carcinoma cells have intrinsic defects in their ability to regulate cdk-cki complexes in response to differentiation signals.
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PMID:Decreased growth inhibitory responses of squamous carcinoma cells to interferon-gamma involve failure to recruit cki proteins into cdk2 complexes. 1171 Sep 44

Many viruses are known to disarm or suppress the cell death machinery of infected cells. Apoptotic cell death can be activated by aggregation of the CD95 cell surface death receptor in sensitive cells, and in most insensitive cells treated with sensitizing agents such as interferon-gamma or inhibitors of protein synthesis. We show that, subsequent to sequestration and inactivation of the p53 tumour suppressor protein, SV40 abrogates p53-dependent, DNA damage-inducible up-regulation of CD95 surface expression. Loss of surface up-regulation of CD95 after sub-lethal mitomycin C treatment resulted in an impaired enhancement of both caspase-8 cleavage and apoptotic cell death following CD95 aggregation. We conclude that infection of human cells with SV40 virus strongly inhibits DNA damage-induced enhancement of CD95-mediated apoptosis.
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PMID:Simian virus-40 infection inhibits DNA damage-induced enhancement of CD95 expression and function. 1180 62

Excess nitric oxide (NO) induces apoptosis in some cell types including macrophages; however, the cascade of NO-mediated apoptosis is not fully understood. We investigated the initial steps of NO-mediated apoptosis in mouse macrophage-like RAW 264.7 cells. When cells were treated with bacterial lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma), NO-mediated apoptosis occurred. Under these conditions, p53 accumulation was not observed, indicating that DNA damage is not the main trigger of NO-mediated apoptosis. On the other hand, mRNA and protein for CHOP, a transcription factor known to be induced by endoplasmic reticulum (ER) stress, were induced. The CHOP induction by LPS/IFN-gamma treatment preceded cytochrome c release from mitochondria. In addition, p90ATF6, an ER membrane-bound transcription factor involved in ER stress response, was cleaved to its active soluble form p50ATF6, which was transported to nucleus and bound to the ER stress response element of the CHOP gene. In the luciferase reporter assay, both the CHOP-binding element of the Rous sarcoma virus long terminal repeat and ER stress response element of the CHOP gene were activated by LPS/IFN-gamma treatment. When RAW 264.7 cells or COS-7 cells were transfected with expression plasmids for CHOP, p90ATF6, or p50ATF6, cell death was observed. In addition, apoptosis induced by p50ATF6 was prevented by a CHOP dominant negative form as well as by an ATF6 dominant negative form, and LPS/IFN-gamma-induced apoptosis was prevented by the CHOP dominant negative form. Peritoneal macrophages from CHOP knockout mice showed resistance to NO-induced apoptosis. These results indicate that the ER stress pathway involving ATF6 and CHOP plays a key role in NO-mediated apoptosis in macrophages.
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PMID:Nitric oxide-induced apoptosis in RAW 264.7 macrophages is mediated by endoplasmic reticulum stress pathway involving ATF6 and CHOP. 1180 88

The human wild-type (wt) p53.264-272 peptide is a universal tumor antigen and recognized by HLA-A*0201 (A2.1)-restricted CTL. Generation of this epitope by constitutive 20S proteasomes is prevented by a p53 R to H hotspot mutation at the C-terminal flanking residue 273. We report on the impact of the interferon-gamma (IFN-gamma)-inducible proteasomal activator PA28 (11S regulator) and the immunoproteasome on the in vitro and cellular processing of wt and mutant (mut) p53 substrates. We found that production of the antigenic 264-272 peptide from wt p53 by constitutive as well as immunoproteasomes is accelerated and amplified by the PA28 activator. PA28 and (immuno)proteasomes were not capable to reconvert the resistance of epitope release from mut p53. Maximum and accelerated antigen production in vitro and on the cellular level required the IFN-gamma-inducible interaction of immunoproteasomes and PA28. We conclude that efficient processing of p53.264272 from wt p53 is governed by the proteasome/PA28 complex. These studies have important implications for p53-specific cancer immunotherapy and demonstrate that the effects of the immunoproteasome and PA28 are influenced by the individual epitope and its flanking sequence context.
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PMID:The effect of the interferon-gamma-inducible processing machinery on the generation of a naturally tumor-associated human cytotoxic T lymphocyte epitope within a wild-type and mutant p53 sequence context. 1198 24

The production of nitric oxide (NO) is an essential determinant in auto- and paracrine signaling. NO is generated under inflammatory conditions and may serve as a cytotoxic molecule to produce cell demise along an apoptotic or necrotic pathway. NO also gained attention as a regulator of immune function and a death inhibitor. Cytotoxicity because of substantial NO-formation is established to initiate apoptosis, characterized by upregulation of the tumor suppressor p53, changes in the expression of pro- and antiapoptotic Bcl-2 family members, cytochrome c relocation, activation of caspases, and DNA fragmentation. However, NO-toxicity is not a constant value and NO may protect several cell types from entering programmed cell death. Preactivation of macrophages with a nontoxic dose of S-nitrosoglutathione (200 microM) or lipopolysaccharide/interferon-gamma/N(G)-monomethyl-L-arginine for 15 hours attenuated death in response to various agonists, suppressed p53 accumulation, and abrogated caspase activation. Prestimulation of macrophages with cytokines or low-level NO activated the transcription factor NF-kappaB as well as AP-1 and promoted immediate early gene expression of cyclooxygenase-2 (COX-2). NF-kappaB activation comprised p50/p65-heterodimer formation, IkappaB degradation, and activation of a luciferase reporter construct, that contained four copies of the NF-kappaB-site derived from the murine COX-2 promoter. A NF-kappaB decoy approach (oligonucleotides directed against NF-kappaB) or transfection of a dominant-negative c-Jun mutant (TAM67) abrogated not only the COX-2 expression but also the inducible protection. Blocking NO- or cytokine-mediated inducible protection at the level of NF-kappaB and/or AP-1 restored the occurrence of apoptotic features. Our experiments underscore the role of COX-2 in attenuating natural occurring cell death (i.e., apoptosis).
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PMID:The role of nitric oxide and cyclooxygenase-2 in attenuating apoptosis. 1208 96

This study examined the role of nitric oxide (NO) in cytokine-induced apoptosis in adult cardiac fibroblasts (CFbs). In cultured adult rat CFbs, IL-1beta (5 ng/ml), but not interferon-gamma (10 ng/ml) or tumor necrosis factor-alpha (10 ng/ml), induced inducible NO synthase (iNOS) expression and NO production that was associated with an increase in caspase-3 activity and apoptotic cell death. Apoptotic frequency was reduced by the iNOS inhibitor S-methylisothiourea (3 x 10(-5) M). Apoptosis in response to IL-1beta was attenuated by the caspase-3 inhibitor [Z-Asp-Glu-Val-Asp-fluoromethyl ketone (Z-DVED-FMK)] but not by inhibition of guanylyl cyclase with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). IL-1beta-induced CFb apoptosis was associated with an increase in p53 and Bax protein expression with no changes in Bcl-2 or Bcl-x(L). Nuclear condensation and fragmentation occurred when isolated nuclei were exposed to an NO donor [Z-1[N-(2-aminoethyl)-N-(2-ammonoethyl)amino]diazen-1-ium-1,2-dioate (DETA-NONOate) 10(-5) M], an effect that was not blocked by the peroxynitrite scavenger Mn(III)tetrakis(4-benzoic acid) porphyrin chloride. Moreover, Mn(III)tetrakis(4-benzoic acid) porphyrin chloride attenuated but did not eliminate IL-1beta-induced CFb apoptosis, indicating that the proapoptotic effect of NO can occur independently of its conversion to peroxynitrite. Our results demonstrate that IL-1beta-induced iNOS expression can trigger NO-dependent apoptosis in adult CFbs, which appears to result from DNA damage and may be mediated by a p53-dependent apoptotic pathway.
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PMID:Mechanisms of cytokine induced NO-mediated cardiac fibroblast apoptosis. 1238 74

ONYX-015 is an adenovirus that selectively replicates in p53 dysfunctional or mutated malignant cells. We performed a pilot trial to determine the safety and feasibility of treatment with ONYX-015 delivered intravenously in patients with advanced malignancy. One cohort of five patients received ONYX-015 once a week for 6 weeks at a dose of 2 x 10(12) particles per infusion in combination with weekly infusions of irinotecan (CPT11, 125 mg per week) and 5-fluorouracil (5FU, 500 mg per week). A second cohort of five patients received the combination of ONYX-015 at a dose of 2 x 10(11) particles per week for 6 weeks in combination with interleukin 2 (IL 2, 1.1 x 10(6) units daily via subcutaneous injection for 5 days each week for 4 weeks). Toxicity attributable to ONYX-015 was limited to transient fever. All patients demonstrated elevations in neutralizing antibody titers within 4 weeks of the infusion of ONYX-015. Serum levels of IL-6, IL-10, tumor necrosis factor-alpha, and interferon-gamma increased within 6 hours of viral infusion, suggesting immune activation. This response was more pronounced in the cohort of patients who received 2 x 10(12) particles per infusion. Two patients demonstrated uptake of viral particles in malignant tissue by quantitative PCR. Electron microscopy confirmed selective cytoplasmic viral particles within malignant cells but not within adjacent normal tissue in a third patient. In conclusion ONYX-015 can be administered safely in combination with CPT11, 5FU or low-dose IL 2 and is able to access malignant tissue following intravenous infusion. Further investigation of ONYX-015, possibly with agents that may modulate replication activity, or duration of virus survival, is indicated.
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PMID:Pilot trial of intravenous infusion of a replication-selective adenovirus (ONYX-015) in combination with chemotherapy or IL-2 treatment in refractory cancer patients. 1271 4

H. pylori infection of the gastric mucosa is associated with increased epithelial cell apoptosis. In vitro, interferon-gamma and TNF-alpha have been shown to increase the sensitivity of cells to apoptosis induced by H. pylori. The p53 tumor suppressor gene is frequently mutated in many cancers, including gastric cancer. Since p53 protein can induce apoptosis, we sought to determine whether or not p53 increases the ability of gastric epithelial cells to undergo apoptosis in response to H. pylori-induced cell injury. Human gastric epithelial cell lines, AGS (p53 wild-type) cells and AGS cells infected with HPV E6 gene (AGS-E6) to inactivate p53 were exposed to H. pylori. The p53, p21, and p14ARF proteins were measured in gastric epithelial cells by immunoelectrophoresis. Gastric epithelial cell apoptosis was measured by DNA end-labeling assay (TUNEL) and subG0 cell fractions using flow cytometry, and by agarose gel electrophoresis of DNA. Exposure to H. pylori increased the levels of p53, p21, and p14ARF proteins two fold in AGS cells. Gastric AGS cells with fragmented DNA increased from 1.1% to 68% in after exposure to H. pylori for 24 hr. However, AGS-E6 cells were relatively resistant to apoptosis induced by H. pylori (only 15% of cells underwent apoptosis). In additional experiments, mouse embryonic fibroblasts (MEFs) were used to further investigate the role of ARF in stabilizing p53 after exposure to H. pylori. Wild-type and p19ARF-/- MEFs were exposed to H. pylori and evaluated for activation of p53, p19ARF, and apoptosis. As with AGS cells, H. pylori stimulated a 2-fold increase in p53 and p19ARF in wild-type MEFs; however, there was no increase in p53 in ARF-null MEFs. H. pylori easily stimulated apoptosis in wild-type MEFs, although, the absence of p19ARF significantly reduced the ability of H. pylori to induce apoptosis in these cells. Activation of ARF by H. pylori is important in stabilizing p53 resulting in increased apoptosis. Thus, inactivation of either ARF or p53 in gastric cells may reduce their ability to undergo apoptosis in response to injury induced by H. pylori.
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PMID:p53 and p14 increase sensitivity of gastric cells to H. pylori-induced apoptosis. 1287 Jul 84

In sarcoid granulomas, apoptotic events are reduced, which explains their characteristic long-lasting inflammation. We have described that interferon-gamma (IFN-gamma) inhibits apoptosis in macrophages through the expression of p21(Waf1). Here, we explore the molecular mechanisms involved in the inhibition of apoptosis in sarcoid granulomas. We analyzed skin biopsies from 19 sarcoidosis patients and 16 controls. Total RNA was subjected to semiquantitative reverse transcriptase-polymerase chain reaction analysis. There was no difference found in the expression of proapoptotic (Bax and Bcl-X(s)) or antiapoptotic (Bcl-2 and Bcl-X(L)) genes nor in the expression of the tumor suppressor gene p53. Furthermore, the expression of IFN-gamma and the cdk inhibitors p21(Waf1) and p27(Kip1) were analyzed. IFN-gamma was detected in 37% of the sarcoidosis patients, and controls were negative (P<0.02). In addition, a higher proportion of patients expressing p21(Waf1) (58%) versus controls (12%) was found (P<0.005). There was a significant correlation between the expression of IFN-gamma and p21(Waf1) (r=0.69) and between p21(Waf1) and fibronectin (r=0.65). Finally, using immunohistochemistry, high p21(Waf1) reactivity was observed inside the granuloma. We conclude that the high levels of p21(Waf1) in sarcoidosis may explain the absence of apoptosis in the granuloma and the persistence of inflammation.
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PMID:High expression of p21 Waf1 in sarcoid granulomas: a putative role for long-lasting inflammation. 1288 47


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