Search results for "p53"

Predicting death in patients with mutated TP53 head and neck squamous cell carcinoma

2020

Nuclear Translocation of Nuclear Transcription Factor-κB by α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid Receptors Leads to Transcription of …

2003

We describe a new molecular mechanism of cell death by excitotoxicity mediated through nuclear transcription factor κB (NFκB) in rat embryonic cultures of dopaminergic neurons. Treatment of mesencephalic cultures with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) resulted in a number of changes that occurred selectively in dopaminergic neurons, including persistent elevation in intracellular Ca2+ monitored with Fura-2, and a significant increase in intramitochondrial oxidation of dihydrorhodamine 123, probably associated with transient increase of mitochondrial permeability, cytochrome c release, nuclear translocation of NFκB, and transcriptional activation of the oncogenep53.…

Cell fate regulation upon DNA damage : p53 Serine 46 kinases pave the cell death road

2019

Mild and massive DNA damage are differentially integrated into the cellular signaling networks and, in consequence, provoke different cell fate decisions. After mild damage, the tumor suppressor p53 directs the cellular response to cell cycle arrest, DNA repair, and cell survival, whereas upon severe damage, p53 drives the cell death response. One posttranslational modification of p53, phosphorylation at Serine 46, selectively occurs after severe DNA damage and is envisioned as a marker of the cell death response. However, the molecular mechanism of action of the p53 Ser46 phospho-isomer, the molecular timing of this phosphorylation event, and its activating effects on apoptosis and ferropt…

DNA damage-induced cell death by apoptosis

2006

Following the induction of DNA damage, a prominent route of cell inactivation is apoptosis. During the last ten years, specific DNA lesions that trigger apoptosis have been identified. These include O6-methylguanine, base N-alkylations, bulky DNA adducts, DNA cross-links and DNA double-strand breaks (DSBs). Repair of these lesions are important in preventing apoptosis. An exception is O6-methylguanine-thymine lesions, which require mismatch repair for triggering apoptosis. Apoptosis induced by many chemical genotoxins is the consequence of blockage of DNA replication, which leads to collapse of replication forks and DSB formation. These DSBs are thought to be crucial downstream apoptosis-tr…

Effect of ultraviolet light, methyl methanesulfonate and ionizing radiation on the genotoxic response and apoptosis of mouse fibroblasts lacking c-Fo…

2001

c-Fos and p53 are DNA damage-inducible proteins that are involved in gene regulation, cell cycle checkpoint control and cell proliferation following exposure to genotoxic agents. To investigate comparatively the role of c-Fos and p53 in the maintenance of genomic stability and the induction of apoptosis, we generated mouse fibroblast cell lines from knockout mice deficient for either c-fos (fos -/-) or p53 (p53-/-) or for both gene products (fosp53-/-). The sensitivity of these established cell lines was compared with the corresponding wild-type cells as to the cytotoxic, clastogenic and apoptosis-inducing effects of ultraviolet (UV-C) light and methyl methanesulfonate (MMS). Additionally, …

MYC and EGR1 synergize to trigger tumor cell death by controlling NOXA and BIM transcription upon treatment with the proteasome inhibitor bortezomib

2014

The c-MYC (MYC afterward) oncogene is well known for driving numerous oncogenic programs. However, MYC can also induce apoptosis and this function of MYC warrants further clarification. We report here that a clinically relevant proteasome inhibitor significantly increases MYC protein levels and that endogenous MYC is necessary for the induction of apoptosis. This kind of MYC-induced cell death is mediated by enhanced expression of the pro-apoptotic BCL2 family members NOXA and BIM. Quantitative promoter-scanning chromatin immunoprecipitations (qChIP) further revealed binding of MYC to the promoters of NOXA and BIM upon proteasome inhibition, correlating with increased transcription. Both pr…

The apoptotic effects and synergistic interaction of sodium butyrate and MG132 in human retinoblastoma Y79 cells

1999

This study deals with the apoptotic effect exerted on human retinoblastoma Y79 cells by both sodium butyrate and an inhibitor of 26S proteasome [z-Leu-Leu-Leu-CHO (MG132)] and their synergistic effect. Exposure to sodium butyrate (1-4 mM) induced an accumulation of cells in the G2-M phase that was already visible after 24 h of treatment, when morphological and biochemical signs of apoptosis appeared only in a small number of cells (5-10%). Thereafter, the apoptotic effects increased progressively with slow kinetics, reaching a maximum after 72 h of exposure, when they concerned a large fraction of cells (>75% with 4 mM sodium butyrate). Sodium butyrate stimulated the conversion of procaspas…

Molecular dynamics studies on Mdm2 complexes: An analysis of the inhibitor influence

2012

p53 is a powerful anti-tumoral molecule frequently inactivated by mutations or deletions in cancer. However, half of all human tumors expresses wild-type p53, and its activation, by antagonizing its negative regulator Mdm2, might offer a new strategy for therapeutic protocol. In this work, we present a molecular dynamics study on Mdm2 structure bound to two different known inhibitors with the aim to investigate the structural transitions between apo-Mdm2 and Mdm2-inhibitor complexes. We tried to gain information about conformational changes binding a benzodiazepine derivative inhibitor with respect the known nutlin and the apo form. The conformational changes alter the size of the cleft and…

The Ability of Variant Peptides to Reverse the Nonresponsiveness of T Lymphocytes to the Wild-Type Sequence p53264–272 Epitope

2002

Abstract Recently, we observed that CTL specific for the wild-type (wt) sequence p53264–272 peptide could only be expanded ex vivo from PBMC of a subset of the HLA-A2.1+ normal donors or cancer patients tested. Surprisingly, the tumors of the responsive patients expressed normal levels of wt p53 and could be considered unlikely to present this epitope. In contrast, tumors of nonresponsive patients accumulated mutant p53 and were more likely to present this epitope. We sought to increase the responsive rate to the wt p53264–272 peptide of PBMC obtained from normal donors and patients by identifying more immunogenic variants of this peptide. Two such variants were generated by amino acid exch…

Parthenolide sensitizes hepatocellular carcinoma cells to trail by inducing the expression of death receptors through inhibition of STAT3 activation

2011

This article shows that HepG2, Hep3B, and SK-Hep1 cells, three lines of human hepatocellular carcinoma (HCC) cells, are resistant to apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Parthenolide, a sesquiterpene lactone found in European feverfew, has been shown to exert both anti-inflammatory and anti-cancer activities. This article demonstrates that co-treatment with parthenolide and TRAIL-induced apoptosis with synergistic interactions in the three lines of HCC cells. In order to explain these effects we ascertained that parthenolide increased either at protein or mRNA level the total content of death receptors TRAIL-R1 and -R2 as well as their surfac…