Forkhead box O and the control of cellular oxidative stress

NARCIS (Netherlands)

Essers, M.A.G.

2004-01-01

FOXO Forkhead transcription factors are a subfamily of the large superfamily of Forkhead transcription factors, which consists of over 100 different members, expressed in species ranging from yeast to humans. Members of this family of transcription factors have been demonstrated to play important

Resveratrol relieves Angiostrongylus cantonensis - Induced meningoencephalitis by activating sirtuin-1.

Science.gov (United States)

Chen, An-Chih; Shyu, Ling-Yuh; Hsin, Yue-Loong; Chen, Ke-Min; Lai, Shih-Chan

2017-09-01

Resveratrol, a natural herbal compound found in high levels in grapes and red wine, is frequently used as activator of sirtuin-1. This study investigated the potential function of sirtuin-1 in regulating angiostrongyliasis meningoencephalitis in resveratrol-treated mice. Mice were subjected to meningoencephalitis to study the protective effect of resveratrol against meningoencephalitis and investigate the effects of sirtuin-1 activation on brain. Results demonstrated that sirtuin-1 level decreased in mice with meningoencephalitis and significantly increased in resveratrol-treated mice. Moreover, resveratrol treatment significantly reduced eosinophil counts, p65, Interferon-γ, interleukin (IL)-5, IL-33, and tumor necrosis factor-α levels, matrix metalloproteinase-9 activity, claudin-5 degradation, and blood-brain barrier permeability. By contrast, the anti-inflammatory factor IL-10 was significantly increased in resveratrol-treated mice. Resveratrol treatment was partially beneficial in controlling the pathological processes of angiostrongyliasis meningoencephalitis. The results demonstrate the neuroprotective and anti-inflammatory effects of resveratrol against Angiostrongylus cantonensis-induced eosinophilic meningoencephalitis in mice. Treatment with sirtuin-1 agonist was given within a therapeutic window after A. cantonensis infection. Copyright © 2017 Elsevier B.V. All rights reserved.

HMGB1-mediated DNA bending: Distinct roles in increasing p53 binding to DNA and the transactivation of p53-responsive gene promoters.

Science.gov (United States)

Štros, Michal; Kučírek, Martin; Sani, Soodabeh Abbasi; Polanská, Eva

2018-03-01

HMGB1 is a chromatin-associated protein that has been implicated in many important biological processes such as transcription, recombination, DNA repair, and genome stability. These functions include the enhancement of binding of a number of transcription factors, including the tumor suppressor protein p53, to their specific DNA-binding sites. HMGB1 is composed of two highly conserved HMG boxes, linked to an intrinsically disordered acidic C-terminal tail. Previous reports have suggested that the ability of HMGB1 to bend DNA may explain the in vitro HMGB1-mediated increase in sequence-specific DNA binding by p53. The aim of this study was to reinvestigate the importance of HMGB1-induced DNA bending in relationship to the ability of the protein to promote the specific binding of p53 to short DNA duplexes in vitro, and to transactivate two major p53-regulated human genes: Mdm2 and p21/WAF1. Using a number of HMGB1 mutants, we report that the HMGB1-mediated increase in sequence-specific p53 binding to DNA duplexes in vitro depends very little on HMGB1-mediated DNA bending. The presence of the acidic C-terminal tail of HMGB1 and/or the oxidation of the protein can reduce the HMGB1-mediated p53 binding. Interestingly, the induction of transactivation of p53-responsive gene promoters by HMGB1 requires both the ability of the protein to bend DNA and the acidic C-terminal tail, and is promoter-specific. We propose that the efficient transactivation of p53-responsive gene promoters by HMGB1 depends on complex events, rather than solely on the promotion of p53 binding to its DNA cognate sites. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of cell density and HLA-DR incompatibility on T-cell proliferation and forkhead box P3 expression in human mixed lymphocyte reaction.

Science.gov (United States)

Song, E Y; Han, S; Yang, B; Morris, G P; Bui, J D

2015-04-01

The proliferation rates of human T cells in vitro are affected by some factors such as initial T-cell number, dose of stimulating cells, and duration of culture. The transcription factor forkhead box P3 (FoxP3) has been used to identify regulatory T cells in humans and is thought to correlate with tolerance to allogeneic organ transplant. Thus, it is important to optimize conditions to expand FoxP3 cell proliferation to improve engraftment of allogeneic organ transplants. We studied proliferative responses and FoxP3 expression in divided T cells with the use of flow cytometric analysis of Ki-67 in culture of different concentrations of responding cells (6 × 10(6), 4 × 10(6), 2 × 10(6), 1 × 10(6), and 0.5 × 10(6)cells/mL), different types of stimulating cells (lymphocytes and low density cells), and different numbers of HLA mismatches. The proportion of CD3(+) cells, CD4(+)CD25(+) cells, and CD4(+)CD25(+)FoxP3(+) cells among mononuclear cells were highest at initial cell concentration of 2 × 10(6) responder cells/mL with lymphocytes as stimulators at day-5 mixed lymphocyte reaction (MLR). They were highest at a concentration of 4 × 10(6) responder cells/mL with low density cells as stimulators. The recovery (%), proportion of CD3(+) cells, CD4(+)CD25(+) cells, and CD4(+)CD25(+)FoxP3(+) cells with 2 HLA-DR incompatibility were significantly higher than those of 1 HLA-DR incompatibility at day-5 MLR. Initial cell concentration and HLA-DR incompatibility can affect the generation of FoxP3+ T cells in human MLR. These factors could be considered for efficient generation of Tregs for clinical trials in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

A systematic review of p53 regulation of oxidative stress in skeletal muscle.

Science.gov (United States)

Beyfuss, Kaitlyn; Hood, David A

2018-12-01

transcription factor 4; ATM: ATM serine/threonine kinase; Bax: BCL2 associated X, apoptosis regulator; Bcl-2: B cell Leukemia/Lymphoma 2 apoptosis regulator; Bhlhe40: basic helix-loop-helix family member e40; BH3: Borane; Bim: bcl-2 interacting mediator of cell death; Bok: Bcl-2 related ovarian killer; COX-IV: cytochrome c oxidase IV; cGMP: Cyclic guanosine monophosphate; c-myc: proto-oncogene protein; Cpt1b: carnitine palmitoyltransferase 1B; Dr5: death receptor 5; eNOS: endothelial nitric oxide synthase; ERK: extracellular regulated MAP kinase; Fas: Fas Cell surface death receptor; FDXR: Ferredoxin Reductase; FOXO3a: forkhead box O3; Gadd45a: growth arrest and DNA damage-inducible 45 alpha; GLS2: glutaminase 2; GLUT 1 and 4: glucose transporter 1(endothelial) and 4 (skeletal muscle); GSH: Glutathione; Hes1: hes family bHLH transcription factor 1; Hey1: hes related family bHLH transcription factor with YRPW motif 1; HIFI-α: hypoxia-inducible factor 1, α-subunit; HK2: Hexokinase 2; HSP70: Heat Shock Protein 70; H 2 O 2 : Hydrogen Peroxide; Id2: inhibitor of DNA-binding 2; IGF-1-BP3: Insulin-like growth factor binding protein 3; IL-1β: Interleukin 1 beta; iNOS: inducible nitric oxide synthase; IRS-1: Insulin receptor substrate 1; JNK: c-Jun N-terminal kinases; LY-83583: 6-anilino-5,8-quinolinedione; inhibitor of soluble guanylate cyclase and of cGMP production; Mdm 2/ 4: Mouse double minute 2 homolog (mouse) Mdm4 (humans); mtDNA: mitochondrial DNA; MURF1: Muscle RING-finger protein-1; MyoD: Myogenic differentiation 1; MyoG: myogenin; Nanog: Nanog homeobox; NF-kB: Nuclear factor-κB; NO: nitric oxide; NoxA: phorbol-12-myristate-13-acetate-induced protein 1 (Pmaip1); NRF-1: nuclear respiratory factor 1; Nrf2: Nuclear factor erythroid 2-related factor 2; P21: Cdkn1a cyclin-dependent kinase inhibitor 1A (P21); P38 MAPK: mitogen-activated protein kinases; p53R2: p53 inducible ribonucleotide reductase gene; P66Shc: src homology 2 domain-containing transforming protein C1; PERP: p

Perturbations in the p53/miR-34a/SIRT1 pathway in the R6/2 Huntington's disease model

DEFF Research Database (Denmark)

Reynolds, Regina Hertfelder; Petersen, Maria Hvidberg; Willert, Cecilie Wennemoes

2018-01-01

The three factors, p53, the microRNA-34 family and Sirtuin 1 (SIRT1), interact in a positive feedback loop involved in cell cycle progression, cellular senescence and apoptosis. Each factor in this triad has roles in metabolic regulation, maintenance of mitochondrial function, and regulation...... of brain-derived neurotrophic factor (BDNF). Thus, this regulatory network holds potential importance for the pathophysiology of Huntington's disease (HD), an inherited neurodegenerative disorder in which both mitochondrial dysfunction and impaired neurotrophic signalling are observed. We investigated...

Associations between Forkhead Box O1 (FoxO1) Expression and Indicators of Hepatic Glucose Production in Transition Dairy Cows Supplemented with Dietary Nicotinic Acid.

Science.gov (United States)

Kinoshita, Asako; Locher, Lena; Tienken, Reka; Meyer, Ulrich; Dänicke, Sven; Rehage, Jürgen; Huber, Korinna

2016-01-01

Forkhead box protein O1 (FoxO1) is a transcription factor which promotes hepatic glucose production (HGP) by up-regulating the transcription of gluconeogenic enzymes in monogastric species. The activity of FoxO1 is inhibited by insulin-induced phosphorylation. The aims of the present study were to find associations between FoxO1 expression and variables associated with HGP as affected by feeding regimen in dairy cows during the transition period. Twenty one healthy German Holstein cows were allocated to four groups (LC-CON, HC-CON, LC-NA with 5 cows/group and HC-NA with 6 cows/group, respectively). Cows received 0 (LC-CON and HC-CON) or 24 (LC-NA and HC-NA) g/d nicotinic acid with high (HC) or low (LC) concentrate proportion from -42 days (-41.8 + 4.8; mean + standard deviation) relative to expected calving date (d-42) to d24. Liver biopsy was taken at d-42, 1, 21, and 100. The total protein expression of FoxO1 (tFoxO1) and the extent of phosphorylation of FoxO1 at serine 256 (pFoxO1) were analysed semiquantitatively by Western Blotting. The expression of hepatic mRNA of FoxO1 and seven genes associated with HGP was measured by real-time RT-PCR. Mixed model and Pearson's correlation were used for statistical evaluation with the level of significance at Pdairy cows in early lactation.

Tumor protein 53-induced nuclear protein 1 (TP53INP1 enhances p53 function and represses tumorigenesis

Directory of Open Access Journals (Sweden)

Jeyran eShahbazi

2013-05-01

Full Text Available Tumor protein 53-induced nuclear protein 1 (TP53INP1 is a stress-induced p53 target gene whose expression is modulated by transcription factors such as p53, p73 and E2F1. TP53INP1 gene encodes two isoforms of TP53INP1 proteins, TP53INP1α and TP53INP1β, both of which appear to be key elements in p53 function. When associated with homeodomain-interacting protein kinase-2 (HIPK2, TP53INP1 phosphorylates p53 protein at Serine 46, enhances p53 protein stability and its transcriptional activity, leading to transcriptional activation of p53 target genes such as p21, PIG-3 and MDM2, cell growth arrest and apoptosis upon DNA damage stress. The anti-proliferative and pro-apoptotic activities of TP53INP1 indicate that TP53INP1 has an important role in cellular homeostasis and DNA damage response. Deficiency in TP53INP1 expression results in increased tumorigenesis; while TP53INP1 expression is repressed during early stages of cancer by factors such as miR-155. This review aims to summarize the roles of TP53INP1 in blocking tumor progression through p53-dependant and p53-independent pathways, as well as the elements which repress TP53INP1 expression, hence highlighting its potential as a therapeutic target in cancer treatment.

Forkhead Box M1 Is Regulated by Heat Shock Factor 1 and Promotes Glioma Cells Survival under Heat Shock Stress*

Science.gov (United States)

Dai, Bingbing; Gong, Aihua; Jing, Zhitao; Aldape, Kenneth D.; Kang, Shin-Hyuk; Sawaya, Raymond; Huang, Suyun

2013-01-01

The forkhead box M1 (FoxM1) is a key transcription factor regulating multiple aspects of cell biology. Prior studies have shown that FoxM1 is overexpressed in a variety of human tumors, including brain tumor, and plays a critical role in cancer development and progression. In this study we found that FoxM1 was up-regulated by heat shock factor 1 (HSF1) under heat shock stress condition in multiple cell lines. Knockdown of HSF1 with HSF1 siRNA or inhibition of HSF1 with a HSF1 inhibitor abrogated heat shock-induced expression of FoxM1. Genetic deletion of HSF1 in mouse embryo fibroblast cells also abolished heat shock stress-induced FoxM1 expression. Moreover, we showed that HSF1 directly bound to FoxM1 promoter and increased FoxM1 promoter activity. Furthermore, we demonstrated that FoxM1 was required for the G2-M phase progression through regulating Cdc2, Cdc20, and Cdc25B under a mild heat shock stress but enhanced cell survival under lethal heat shock stress condition. Finally, in human glioblastoma specimens, FoxM1 overexpression correlated with elevated HSF1 expression. Our results indicate that FoxM1 is regulated by HSF1 and is critical for HSF1-mediated heat shock response. We demonstrated a novel mechanism of stress resistance controlled by HSF1 and a new HSF-FoxM1 connection that mediates cellular thermotolerance. PMID:23192351

Forkhead box K2 inhibits the proliferation, migration, and invasion of human glioma cells and predicts a favorable prognosis

Directory of Open Access Journals (Sweden)

Wang B

2018-02-01

Full Text Available Bo Wang,1–3,* XueBin Zhang,2–4,* Wei Wang,1–3 ZhiZhong Zhu,5 Fan Tang,2–4 Dong Wang,6–8 Xi Liu,9 Hao Zhuang,10 XiaoLing Yan2–4 1Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin, China; 2Tianjin Key Laboratory of Cerebral Vascular and Neurodegenerative Diseases, Tianjin, China; 3Tianjin Neurosurgical Institute, Tianjin, China; 4Department of Pathology, Tianjin Huanhu Hospital, Tianjin, China; 5Department of Rehabilitation, Tianjin Huanhu Hospital, Tianjin, China; 6Department of Neurosurgery, Tianjin Medical University, General Hospital, Tianjin, China; 7Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China; 8Tianjin Neurological Institute, Tianjin, China; 9Department of Gastroenterology, Tianjin NanKai Hospital, Tianjin, China; 10Department of Hepatic Biliary Pancreatic Surgery, Cancer Hospital Affiliated to Zhengzhou University, Zhengzhou, China *These authors contributed equally to this work Purpose: Forkhead box K2 (FOXK2 is a member of the forkhead box family of transcription factors. Recently, researchers discovered that overexpression of FOXK2 inhibits the proliferation and metastasis of breast cancer, non-small cell lung cancer, and colorectal cancer, and is related to the clinical prognosis. However, in hepatocellular carcinoma, FOXK2 results in the opposite phenotypes. Currently, the contribution of FOXK2 to glioma pathogenesis is not clear. Patients and methods: We evaluated the expression of FOXK2 in 151 glioma patients using immunohistochemistry assays. The associations among the expression of FOXK2, clinicopathological parameters, and the prognosis of glioma patients were statistically analyzed. We downregulated and upregulated the level of FOXK2 in glioma cells by transfections with small interfering RNA and plasmids. Then, we investigated the effects on tumor cell behavior in vitro by Cell Counting Kit-8 assays, colony-formation assay, transwell assay, and the

Antitumor effects of a sirtuin inhibitor, tenovin-6, against gastric cancer cells via death receptor 5 up-regulation.

Directory of Open Access Journals (Sweden)

Sachiko Hirai

Full Text Available Up-regulated sirtuin 1 (SIRT1, an NAD+-dependent class III histone deacetylase, deacetylates p53 and inhibits its transcriptional activity, leading to cell survival. SIRT1 overexpression has been reported to predict poor survival in some malignancies, including gastric cancer. However, the antitumor effect of SIRT1 inhibition remains elusive in gastric cancer. Here, we investigated the antitumor mechanisms of a sirtuin inhibitor, tenovin-6, in seven human gastric cancer cell lines (four cell lines with wild-type TP53, two with mutant-type TP53, and one with null TP53. Interestingly, tenovin-6 induced apoptosis in all cell lines, not only those with wild-type TP53, but also mutant-type and null versions, accompanied by up-regulation of death receptor 5 (DR5. In the KatoIII cell line (TP53-null, DR5 silencing markedly attenuated tenovin-6-induced apoptosis, suggesting that the pivotal mechanism behind its antitumor effects is based on activation of the death receptor signal pathway. Although endoplasmic reticulum stress caused by sirtuin inhibitors was reported to induce DR5 up-regulation in other cancer cell lines, we could not find marked activation of its related molecules, such as ATF6, PERK, and CHOP, in gastric cancer cells treated with tenovin-6. Tenovin-6 in combination with docetaxel or SN-38 exerted a slight to moderate synergistic cytotoxicity against gastric cancer cells. In conclusion, tenovin-6 has potent antitumor activity against human gastric cancer cells via DR5 up-regulation. Our results should be helpful for the future clinical development of sirtuin inhibitors.

Associations between Forkhead Box O1 (FoxO1 Expression and Indicators of Hepatic Glucose Production in Transition Dairy Cows Supplemented with Dietary Nicotinic Acid.

Directory of Open Access Journals (Sweden)

Asako Kinoshita

Full Text Available Forkhead box protein O1 (FoxO1 is a transcription factor which promotes hepatic glucose production (HGP by up-regulating the transcription of gluconeogenic enzymes in monogastric species. The activity of FoxO1 is inhibited by insulin-induced phosphorylation. The aims of the present study were to find associations between FoxO1 expression and variables associated with HGP as affected by feeding regimen in dairy cows during the transition period. Twenty one healthy German Holstein cows were allocated to four groups (LC-CON, HC-CON, LC-NA with 5 cows/group and HC-NA with 6 cows/group, respectively. Cows received 0 (LC-CON and HC-CON or 24 (LC-NA and HC-NA g/d nicotinic acid with high (HC or low (LC concentrate proportion from -42 days (-41.8 + 4.8; mean + standard deviation relative to expected calving date (d-42 to d24. Liver biopsy was taken at d-42, 1, 21, and 100. The total protein expression of FoxO1 (tFoxO1 and the extent of phosphorylation of FoxO1 at serine 256 (pFoxO1 were analysed semiquantitatively by Western Blotting. The expression of hepatic mRNA of FoxO1 and seven genes associated with HGP was measured by real-time RT-PCR. Mixed model and Pearson's correlation were used for statistical evaluation with the level of significance at P<0.05. No dietary effect was observed either on feed intake, energy balance, or on the concentration of blood metabolites. Neither time nor diet affected the expression of FoxO1 total protein and mRNA. A NA × concentrate interaction was found in pFoxO1. However, no corresponding dietary effect was found in the mRNA expression of investigated genes. Different patterns of correlations between FoxO1-related variables and investigated indicators for HGP were found at d21 and 100. The results indicated that the regulation of HGP did not take place on the levels of mRNA and protein expression and the phosphorylation of FoxO1 in dairy cows in early lactation.

Infection with E1B-mutant adenovirus stabilizes p53 but blocks p53 acetylation and activity through E1A

DEFF Research Database (Denmark)

Savelyeva, I.; Dobbelstein, M.

2011-01-01

to the suppression of p21 transcription. Depending on the E1A conserved region 3, E1B-defective adenovirus impaired the ability of the transcription factor Sp1 to bind the p21 promoter. Moreover, the amino terminal region of E1A, binding the acetyl transferases p300 and CREB-binding protein, blocked p53 K382...... accumulation of p53, without obvious defects in p53 localization, phosphorylation, conformation and oligomerization. Nonetheless, p53 completely failed to induce its target genes in this scenario, for example, p21/CDKN1A, Mdm2 and PUMA. Two regions of the E1A gene products independently contributed...... acetylation in infected cells. Mutating either of these E1A regions, in addition to E1B, partially restored p21 mRNA levels. Our findings argue that adenovirus attenuates p53-mediated p21 induction, through at least two E1B-independent mechanisms. Other virus species and cancer cells may employ analogous...

Effect of pH on the Structure and DNA Binding of the FOXP2 Forkhead Domain.

Science.gov (United States)

Blane, Ashleigh; Fanucchi, Sylvia

2015-06-30

Forkhead box P2 (FOXP2) is a transcription factor expressed in cardiovascular, intestinal, and neural tissues during embryonic development and is implicated in language development. FOXP2 like other FOX proteins contains a DNA binding domain known as the forkhead domain (FHD). The FHD interacts with DNA by inserting helix 3 into the major groove. One of these DNA-protein interactions is a direct hydrogen bond that is formed with His554. FOXP2 is localized in the nuclear compartment that has a pH of 7.5. Histidine contains an imidazole side chain in which the amino group typically has a pKa of ~6.5. It seems possible that pH fluctuations around 6.5 may result in changes in the protonation state of His554 and thus the ability of the FOXP2 FHD to bind DNA. To investigate the effect of pH on the FHD, both the structure and the binding affinity were studied in the pH range of 5-9. This was done in the presence and absence of DNA. The structure was assessed using size exclusion chromatography, far-UV circular dichroism, and intrinsic and extrinsic fluorescence. The results indicated that while pH did not affect the secondary structure in the presence or absence of DNA, the tertiary structure was pH sensitive and the protein was less compact at low pH. Furthermore, the presence of DNA caused the protein to become more compact at low pH and also had the potential to increase the dimerization propensity. Fluorescence anisotropy was used to investigate the effect of pH on the FOXP2 FHD DNA binding affinity. It was found that pH had a direct effect on binding affinity. This was attributed to the altered hydrogen bonding patterns upon protonation or deprotonation of His554. These results could implicate pH as a means of regulating transcription by the FOXP2 FHD, which may also have repercussions for the behavior of this protein in cancer cells.

Forkhead box O transcription factors as possible mediators in the development of major depression.

Science.gov (United States)

Wang, Haitao; Quirion, Rémi; Little, Peter J; Cheng, Yufang; Feng, Zhong-Ping; Sun, Hong-Shuo; Xu, Jiangping; Zheng, Wenhua

2015-12-01

Forkhead box O (FoxO) transcription factors play important roles in cellular physiology and biology. Recent findings indicate that FoxOs are also involved in the development of major depressive disorder. Alterations in the upstream molecules of FoxOs, such as brain derived neurotrophic factor or protein kinase B, have been linked to depression. Antidepressants, such as imipramine and venlafaxine, modify the FoxOs phosphorylation. Furthermore, FoxOs could be regulated by serotonin and norepinephrine receptor signaling as well as the hypothalamic-pituitary-adrenal axis, all of which are involved in the pathogenesis of depression. FoxOs also regulate neuronal morphology, synaptogenesis and adult hippocampal neurogenesis, which are viewed as candidate mechanisms for the etiology of depression. In this review, we emphasize the possible roles of FoxOs during the development of depression and make some strategic recommendations for future research. We propose that FoxOs and its signaling pathways may constitute potential therapeutic targets in the treatment of depression. Copyright © 2015 Elsevier Ltd. All rights reserved.

Forkhead box K2 inhibits the proliferation, migration, and invasion of human glioma cells and predicts a favorable prognosis.

Science.gov (United States)

Wang, Bo; Zhang, XueBin; Wang, Wei; Zhu, ZhiZhong; Tang, Fan; Wang, Dong; Liu, Xi; Zhuang, Hao; Yan, XiaoLing

2018-01-01

Forkhead box K2 (FOXK2) is a member of the forkhead box family of transcription factors. Recently, researchers discovered that overexpression of FOXK2 inhibits the proliferation and metastasis of breast cancer, non-small cell lung cancer, and colorectal cancer, and is related to the clinical prognosis. However, in hepatocellular carcinoma, FOXK2 results in the opposite phenotypes. Currently, the contribution of FOXK2 to glioma pathogenesis is not clear. We evaluated the expression of FOXK2 in 151 glioma patients using immunohistochemistry assays. The associations among the expression of FOXK2, clinicopathological parameters, and the prognosis of glioma patients were statistically analyzed. We downregulated and upregulated the level of FOXK2 in glioma cells by transfections with small interfering RNA and plasmids. Then, we investigated the effects on tumor cell behavior in vitro by Cell Counting Kit-8 assays, colony-formation assay, transwell assay, and the epithelial-to-mesenchymal transition (EMT) biomarker levels. The clinical data showed that expression of FOXK2 gradually decreased with increasing World Health Organization (WHO) grades and a low level of FOXK2 indicates a poor prognosis. FOXK2 expression is negatively correlated with Ki67 expression and the WHO degree but is not correlated with other clinicopathological parameters, including sex, age, Karnofsky Performance Status, tumor diameter, O -6-methylguanine-DNA methyltransferase, and glutathione S -transferase pi. FOXK2 knockdown enhances glioma cell proliferation, migration, invasion, and EMT process, and, in contrast, FOXK2 overexpression inhibits glioma cell proliferation, migration, invasion, and the EMT process. Expression of FOXK2 gradually decreases with increasing WHO grades. FOXK2 inhibits tumor proliferation, migration, and invasion. FOXK2 is a critical mediator of the EMT process.

Endogenous Nampt upregulation is associated with diabetic nephropathy inflammatory-fibrosis through the NF-κB p65 and Sirt1 pathway; NMN alleviates diabetic nephropathy inflammatory-fibrosis by inhibiting endogenous Nampt.

Science.gov (United States)

Chen, Ye; Liang, Yuzhen; Hu, Tingting; Wei, Riming; Cai, Congjie; Wang, Ping; Wang, Lingyu; Qiao, Wei; Feng, Leping

2017-11-01

Nicotinamide phosphoribosyltransferase (Nampt) is a key enzyme in the nicotinamide adenine dinucleotide (NAD + ) biosynthetic pathway. Exogenous extra cellular Nampt has been reported to increase the synthesis of pro-fibrotic molecules in various types of renal cells. However, the role of endogenous Namptenzymatic activity in diabetic renal cells, particularly those associated with inflammation and fibrosis through the nuclear factor (NF)-κB p65 and sirtuin 1 (Sirt1) pathway is still unknown. In the present study, a possible mechanism by which endogenous Nampt upregulation affects the expression of pro-inflammatory and pro-fibrotic cytokines in vivo and in vitro , is reported. The present results demonstrate that the expression of vimentin and fibronectin was directly implicated in endogenous Nampt upregulation. The expression levels of Poly(ADP-ribose) polymerase-1, NF-κB p65, forkhead box protein O1 and B-cell lymphoma 2-like protein 4 were also significantly increased at 96 h compared with control group (Pendogenous Nampt upregulation. Furthermore, the expression level of Sirt1 was significantly reduced (Pendogenous Nampt upregulation may be critical in the treatment of DN pro-inflammatory fibrosis and NMN is likely to be a potential pharmacological agent for the treatment of resistant DN nephritic fibrosis.

The effect of Ramadan fasting on sirtuin and visfatin levels.

Science.gov (United States)

Engin-Ustun, Yaprak; Caglayan, Emel Kiyak; Kara, Mustafa; Gocmen, Ayse Yesim; Polat, M Fevzi; Aktulay, Ayla

2016-03-01

Our aim was to determine how Ramadan fasting effects serum Human NAD-dependent deacetylase sirtuin 1 (SIRT1/SIR2L1) and visfatin levels during pregnancy. Thirty-six patients were included in this case-control study. The patient group consisted of 18 pregnant women who were Ramadan fasting. Another healthy 18 pregnant women with matching pregnancy weeks and ages formed the control group. Blood samples were obtained from the patients for biochemical analyses and serum adipokine level measurements. The mean sirtuin and visfatin levels in fasting pregnant women were 2.87 ± 0.95 and 60.18 ± 19.49 ng/mL, respectively, while the mean serum sirtuin and visfatin levels in the control group was determined to be 4.28 ± 1.45 and 23.26 ± 6.18 ng/mL, respectively. A statistically significant difference was determined between the groups ( p = 0.002, p = 0.0001). A correlation analysis provided a negative correlation between number of fasting days and sirtuin levels ( r = 0.45, p = 0.005) and a positive correlation with visfatin levels ( r = 0.73, p = 0.0001). As a result, while the serum sirtuin 1 level of pregnant women decreased due to fasting in Ramadan, we determined that their visfatin levels increased and this increase was in correlation with the days of fasting.

Sirtuin 1 independent effects of resveratrol in INS-1E β-cells

DEFF Research Database (Denmark)

Erdogan, Cihan Süleyman; Mørup-Lendal, Mathias; Dalgaard, Louise Torp

2017-01-01

Resveratrol (Resv), a natural polyphenol, is suggested to have various health benefits including improved insulin sensitivity. Resv activates Sirtuin (Sirt1) in several species and tissues. Sirt1 is a protein deacetylase with an important role in ageing, metabolism and β-cell function. In insulin......Resveratrol (Resv), a natural polyphenol, is suggested to have various health benefits including improved insulin sensitivity. Resv activates Sirtuin (Sirt1) in several species and tissues. Sirt1 is a protein deacetylase with an important role in ageing, metabolism and β-cell function...... effects of Resv with respect to mTOR cascade activity. Sirt1-knockdown (KD) had a significant increase in cell size compared to negative-control (NEG CTR) cells. Resveratrol treatment increased cell size in both cell types in a dose-dependent manner at 24 h (Resv conc: 15-60 μM), and decreased the cell...... not affect the mTOR cascade activities as measured by Western blotting for total and phosphorylated Akt and mTOR. Rapamycin decreased the mTORC1 activity, while increasing the pAkt levels. Resveratrol did not interfere with the mTOR activity or with Sirt1 expression. Altogether, this work indicates that Sirt...

The Effect of Aerobic Training on Metabolic Parameters and Serum Level of Sirtuin1 in Women with Type 2 Diabetes

Directory of Open Access Journals (Sweden)

Abbas Saremi

2016-12-01

Full Text Available Abstract Background: Sirtuin-1 regulates important cellular processes, including apoptosis, cellular senescence, and metabolism. Therefore, sirtuin-1 may be a novel therapeutic target for type 2 diabetes. The aim of this study was to investigate the effect of 8 weeks aerobic training on sirtuin-1 level and cardiometabolic parameters in women with type 2 diabetes. Materials and Methods: In this semi-experimental study with pretest – posttest design, twenty diabetic women (aged 43.92±5.2 y were randomly assigned to aerobic training or non-exercising control groups. Aerobic training program was performed 50-60 min/d, 3d/wk, for 2 months. Serum levels of sirtuin-1, body composition and metabolic parameters were assessed before and after the training period. Data were analyzed by paired T test. Results: Adiposity indices, total cholesterol, triglyceride, LDL- cholesterol,blood glucose and insulin resistance index were significantly reduced in the intervention group compared to the control (p<0.05. Also, sirtuin-1 level was increased in the intervention group compared to the control (p<0.05. Conclusion: These findings show that aerobic exercise is associated with an improvement in siruin-1 levels and metabolic indices in women with type 2 diabetes.

Expression of Egr1 and p53 in human carotid plaques and apoptosis induced by 7-oxysterol or p53.

Science.gov (United States)

Miah, Sayem; Zadeh, Shahram Nour Mohammad; Yuan, Xi-Ming; Li, Wei

2013-07-01

Egr-1 and p53 are involved in pathology of both atherosclerosis and cancer. However, it is unknown whether p53 and Egr1 are interactively involved in apoptosis in atherosclerosis. We found that in human carotid plaques, the expression of p53 was inversely correlated with Egr1. In U937 cells, 7β-hydroxycholesterol and 7-ketocholesterol induced production of reactive oxygen species (ROS), transient up-regulation of Egr1 followed by late induction of p53 and apoptosis. Cells with nuclear fragmentation induced by 7-oxysterol or p53 showed increased levels of p53, but decreased levels of Egr1. In conclusion, ROS induced by 7-oxysterols may function as an early initiator of Egr1 expression. The late induced p53 by 7-oxysterols contributes to apoptotic cell death and is linked to the reduction of Egr1 levels, which resembles the differential expression of p53 and Egr1 in human atheroma progression. Copyright © 2012 Elsevier GmbH. All rights reserved.

Roles of Forkhead-box Transcription Factors in Controlling Development, Pathogenicity, and Stress Response in Magnaporthe oryzae

Directory of Open Access Journals (Sweden)

Jaejin Park

2014-06-01

Full Text Available Although multiple transcription factors (TFs have been characterized via mutagenesis to understand their roles in controlling pathogenicity and infection-related development in Magnaporthe oryzae, the causal agent of rice blast, if and how forkhead-box (FOX TFs contribute to these processes remain to be characterized. Four putative FOX TF genes were identified in the genome of M. oryzae, and phylogenetic analysis suggested that two of them (MoFKH1 and MoHCM1 correspond to Ascomycota-specific members of the FOX TF family while the others (MoFOX1 and MoFOX2 are Pezizomycotina-specific members. Deletion of MoFKH1 (ΔMofkh1 resulted in reduced mycelial growth and conidial germination, abnormal septation and stress response, and reduced virulence. Similarly, ΔMohcm1 exhibited reduced mycelial growth and conidial germination. Conidia of ΔMofkh1 and ΔMohcm1 were more sensitive to one or both of the cell cycle inhibitors hydroxyurea and benomyl, suggesting their role in cell cycle control. On the other hand, loss of MoFOX1 (ΔMofox1 did not show any noticeable changes in development, pathogenicity, and stress response. Deletion of MoFOX2 was not successful even after repeated attempts. Taken together, these results suggested that MoFKH1 and Mo-HCM1 are important in fungal development and that MoFKH1 is further implicated in pathogenicity and stress response in M. oryzae.

Sirtuins & disease: the road ahead

Directory of Open Access Journals (Sweden)

Vincenzo eCarafa

2012-01-01

Full Text Available Sirtuins represent a promising new class of conserved histone deacetylases, originally identified in yeast. The activity of the sirtuin (SirT family – made up of seven members (SirT1-7 – is NAD+ dependent. Sirtuins target a wide range of cellular proteins in nucleus, cytoplasm and mitochondria for post-translational modification by acetylation (SirT1, 2, 3 and 5 or ADP ribosylation (SirT4 and 6. Sirtuins regulate responses to stress and ensure that damaged DNA is not propagated, thus contrasting the accumulation of mutations. To date, sirtuins have emerged as potential therapeutic targets for treatment of human pathologies such as metabolic, cardiovascular and neurodegenerative diseases, and cancer. SirT1 is the founding member of this class of enzymes and is currently the best known of the group. SirT1 acts in various cellular processes, deacetylating both chromatin and non-histone proteins, and its role in cancer and aging has been extensively studied. SirT1 may play a critical role in tumor initiation and progression as well as drug resistance by blocking senescence and apoptosis, and by promoting cell growth and angiogenesis. Recently, growing interest in sirtuin modulation has led to the discovery and characterization of small molecules able to modify sirtuin activity. The present review highlights SirT mechanism(s of action and deregulation in cancer, focusing on the therapeutic potential of SirT modulators both in cancer prevention and treatment.

The antagonism between MCT-1 and p53 affects the tumorigenic outcomes

Directory of Open Access Journals (Sweden)

Lin Tai-Du

2010-12-01

Full Text Available Abstract Background MCT-1 oncoprotein accelerates p53 protein degradation via a proteosome pathway. Synergistic promotion of the xenograft tumorigenicity has been demonstrated in circumstance of p53 loss alongside MCT-1 overexpression. However, the molecular regulation between MCT-1 and p53 in tumor development remains ambiguous. We speculate that MCT-1 may counteract p53 through the diverse mechanisms that determine the tumorigenic outcomes. Results MCT-1 has now identified as a novel target gene of p53 transcriptional regulation. MCT-1 promoter region contains the response elements reactive with wild-type p53 but not mutant p53. Functional p53 suppresses MCT-1 promoter activity and MCT-1 mRNA stability. In a negative feedback regulation, constitutively expressed MCT-1 decreases p53 promoter function and p53 mRNA stability. The apoptotic events are also significantly prevented by oncogenic MCT-1 in a p53-dependent or a p53-independent fashion, according to the genotoxic mechanism. Moreover, oncogenic MCT-1 promotes the tumorigenicity in mice xenografts of p53-null and p53-positive lung cancer cells. In support of the tumor growth are irrepressible by p53 reactivation in vivo, the inhibitors of p53 (MDM2, Pirh2, and Cop1 are constantly stimulated by MCT-1 oncoprotein. Conclusions The oppositions between MCT-1 and p53 are firstly confirmed at multistage processes that include transcription control, mRNA metabolism, and protein expression. MCT-1 oncogenicity can overcome p53 function that persistently advances the tumor development.

The solution structure of the forkhead box-O DNA binding domain of Brugia malayi DAF-16a.

Science.gov (United States)

Casper, Sarah K; Schoeller, Scott J; Zgoba, Danielle M; Phillips, Andrew J; Morien, Thomas J; Chaffee, Gary R; Sackett, Peter C; Peterson, Francis C; Crossgrove, Kirsten; Veldkamp, Christopher T

2014-12-01

Brugia malayi is a parasitic nematode that causes lymphatic filariasis in humans. Here the solution structure of the forkhead DNA binding domain of Brugia malayi DAF-16a, a putative ortholog of Caenorhabditis elegans DAF-16, is reported. It is believed to be the first structure of a forkhead or winged helix domain from an invertebrate. C. elegans DAF-16 is involved in the insulin/IGF-I signaling pathway and helps control metabolism, longevity, and development. Conservation of sequence and structure with human FOXO proteins suggests that B. malayi DAF-16a is a member of the FOXO family of forkhead proteins. © 2014 Wiley Periodicals, Inc.

HEXIM1, a New Player in the p53 Pathway

Energy Technology Data Exchange (ETDEWEB)

Lew, Qiao Jing; Chu, Kai Ling; Chia, Yi Ling; Cheong, Nge [Expression Engineering Group, Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way, #06-01, Singapore 138668 (Singapore); Chao, Sheng-Hao, E-mail: jimmy_chao@bti.a-star.edu.sg [Expression Engineering Group, Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way, #06-01, Singapore 138668 (Singapore); Department of Microbiology, National University of Singapore, Singapore 117597 (Singapore)

2013-07-04

Hexamethylene bisacetamide-inducible protein 1 (HEXIM1) is best known as the inhibitor of positive transcription elongation factor b (P-TEFb), which controls transcription elongation of RNA polymerase II and Tat transactivation of human immunodeficiency virus. Besides P-TEFb, several proteins have been identified as HEXIM1 binding proteins. It is noteworthy that more than half of the HEXIM1 binding partners are involved in cancers. P53 and two key regulators of the p53 pathway, nucleophosmin (NPM) and human double minute-2 protein (HDM2), are among the factors identified. This review will focus on the functional importance of the interactions between HEXIM1 and p53/NPM/HDM2. NPM and the cytoplasmic mutant of NPM, NPMc+, were found to regulate P-TEFb activity and RNA polymerase II transcription through the interaction with HEXIM1. Importantly, more than one-third of acute myeloid leukemia (AML) patients carry NPMc+, suggesting the involvement of HEXIM1 in tumorigenesis of AML. HDM2 was found to ubiquitinate HEXIM1. The HDM2-mediated ubiquitination of HEXIM1 did not lead to protein degradation of HEXIM1 but enhanced its inhibitory activity on P-TEFb. Recently, HEXIM1 was identified as a novel positive regulator of p53. HEXIM1 prevented p53 ubiquitination by competing with HDM2 in binding to p53. Taken together, the new evidence suggests a role of HEXIM1 in regulating the p53 pathway and tumorigenesis.

Mir-34a mimics are potential therapeutic agents for p53-mutated and chemo-resistant brain tumour cells.

Directory of Open Access Journals (Sweden)

Yuen Ngan Fan

Full Text Available Chemotherapeutic drug resistance and relapse remains a major challenge for paediatric (medulloblastoma and adult (glioblastoma brain tumour treatment. Medulloblastoma tumours and cell lines with mutations in the p53 signalling pathway have been shown to be specifically insensitive to DNA damaging agents. The aim of this study was to investigate the potential of triggering cell death in p53 mutated medulloblastoma cells by a direct activation of pro-death signalling downstream of p53 activation. Since non-coding microRNAs (miRNAs have the ability to fine tune the expression of a variety of target genes, orchestrating multiple downstream effects, we hypothesised that triggering the expression of a p53 target miRNA could induce cell death in chemo-resistant cells. Treatment with etoposide, increased miR-34a levels in a p53-dependent fashion and the level of miR-34a transcription was correlated with the cell sensitivity to etoposide. miR-34a activity was validated by measuring the expression levels of one of its well described target: the NADH dependent sirtuin1 (SIRT1. Whilst drugs directly targeting SIRT1, were potent to trigger cell death at high concentrations only, introduction of synthetic miR-34a mimics was able to induce cell death in p53 mutated medulloblastoma and glioblastoma cell lines. Our results show that the need of a functional p53 signaling pathway can be bypassed by direct activation of miR-34a in brain tumour cells.

Forkhead box O3 plays a role in skeletal muscle atrophy through expression of E3 ubiquitin ligases MuRF-1 and atrogin-1 in Cushing's syndrome.

Science.gov (United States)

Kang, Seol-Hee; Lee, Hae-Ahm; Kim, Mina; Lee, Eunjo; Sohn, Uy Dong; Kim, Inkyeom

2017-06-01

Cushing's syndrome is caused by overproduction of the adrenocorticotropic hormone (ACTH), which stimulates the adrenal grand to make cortisol. Skeletal muscle wasting occurs in pathophysiological response to Cushing's syndrome. The forkhead box (FOX) protein family has been implicated as a key regulator of muscle loss under conditions such as diabetes and sepsis. However, the mechanistic role of the FOXO family in ACTH-induced muscle atrophy is not understood. We hypothesized that FOXO3a plays a role in muscle atrophy through expression of the E3 ubiquitin ligases, muscle RING finger protein-1 (MuRF-1), and atrogin-1 in Cushing's syndrome. For establishment of a Cushing's syndrome animal model, Sprague-Dawley rats were implanted with osmotic minipumps containing ACTH (40 ng·kg -1 ·day -1 ). ACTH infusion significantly reduced muscle weight. In ACTH-infused rats, MuRF-1, atrogin-1, and FOXO3a were upregulated and the FOXO3a promoter was targeted by the glucocorticoid receptor (GR). Transcriptional activity and expression of FOXO3a were significantly decreased by the GR antagonist RU486. Treatment with RU486 reduced MuRF-1 and atrogin-1 expression in accordance with reduced enrichment of FOXO3a and Pol II on the promoters. Knockdown of FOXO3a prevented dexamethasone-induced MuRF-1 and atrogin-1 expression. These results indicate that FOXO3a plays a role in muscle atrophy through expression of MuRF-1 and atrogin-1 in Cushing's syndrome. Copyright © 2017 the American Physiological Society.

Impact of Alu repeats on the evolution of human p53 binding sites

Directory of Open Access Journals (Sweden)

Sirotin Michael V

2011-01-01

Full Text Available Abstract Background The p53 tumor suppressor protein is involved in a complicated regulatory network, mediating expression of ~1000 human genes. Recent studies have shown that many p53 in vivo binding sites (BSs reside in transposable repeats. The relationship between these BSs and functional p53 response elements (REs remains unknown, however. We sought to understand whether the p53 REs also reside in transposable elements and particularly in the most-abundant Alu repeats. Results We have analyzed ~160 functional p53 REs identified so far and found that 24 of them occur in repeats. More than half of these repeat-associated REs reside in Alu elements. In addition, using a position weight matrix approach, we found ~400,000 potential p53 BSs in Alu elements genome-wide. Importantly, these putative BSs are located in the same regions of Alu repeats as the functional p53 REs - namely, in the vicinity of Boxes A/A' and B of the internal RNA polymerase III promoter. Earlier nucleosome-mapping experiments showed that the Boxes A/A' and B have a different chromatin environment, which is critical for the binding of p53 to DNA. Here, we compare the Alu-residing p53 sites with the corresponding Alu consensus sequences and conclude that the p53 sites likely evolved through two different mechanisms - the sites overlapping with the Boxes A/A' were generated by CG → TG mutations; the other sites apparently pre-existed in the progenitors of several Alu subfamilies, such as AluJo and AluSq. The binding affinity of p53 to the Alu-residing sites generally correlates with the age of Alu subfamilies, so that the strongest sites are embedded in the 'relatively young' Alu repeats. Conclusions The primate-specific Alu repeats play an important role in shaping the p53 regulatory network in the context of chromatin. One of the selective factors responsible for the frequent occurrence of Alu repeats in introns may be related to the p53-mediated regulation of Alu

A fasting inducible switch modulates gluconeogenesis via activator/coactivator exchange

DEFF Research Database (Denmark)

Liu, Yi; Dentin, Renaud; Chen, Danica

2008-01-01

During early fasting, increases in skeletal muscle proteolysis liberate free amino acids for hepatic gluconeogenesis in response to pancreatic glucagon. Hepatic glucose output diminishes during the late protein-sparing phase of fasting, when ketone body production by the liver supplies compensatory...... expression through the dephosphorylation and nuclear shuttling of forkhead box O1 (FOXO1). Here we show that a fasting-inducible switch, consisting of the histone acetyltransferase p300 and the nutrient-sensing deacetylase sirtuin 1 (SIRT1), maintains energy balance in mice through the sequential induction...... of CRTC2 and FOXO1. After glucagon induction, CRTC2 stimulated gluconeogenic gene expression by an association with p300, which we show here is also activated by dephosphorylation at Ser 89 during fasting. In turn, p300 increased hepatic CRTC2 activity by acetylating it at Lys 628, a site that also...

Both p53-PUMA/NOXA-Bax-mitochondrion and p53-p21cip1 pathways are involved in the CDglyTK-mediated tumor cell suppression

International Nuclear Information System (INIS)

Yu, Zhendong; Wang, Hao; Zhang, Libin; Tang, Aifa; Zhai, Qinna; Wen, Jianxiang; Yao, Li; Li, Pengfei

2009-01-01

CDglyTK fusion suicide gene has been well characterized to effectively kill tumor cells. However, the exact mechanism and downstream target genes are not fully understood. In our study, we found that CDglyTK/prodrug treatment works more efficiently in p53 wild-type (HONE1) cells than in p53 mutant (CNE1) cells. We then used adenovirus-mediated gene delivery system to either knockdown or overexpress p53 and its target genes in these cells. Consistent results showed that both p53-PUMA/NOXA/Bcl2-Bax and p53-p21 pathways contribute to the CDglyTK induced tumor cell suppression. Our work for the first time addressed the role of p53 related genes in the CDglyTK/prodrug system.

Both p53-PUMA/NOXA-Bax-mitochondrion and p53-p21cip1 pathways are involved in the CDglyTK-mediated tumor cell suppression

Energy Technology Data Exchange (ETDEWEB)

Yu, Zhendong, E-mail: zdyu@hotmail.com [Department of Clinical laboratory, Peking University Shenzhen Hospital, Guangdong (China); Wang, Hao [Department of pathology, The Chinese University of Hong Kong, Hong Kong (China); Zhang, Libin; Tang, Aifa; Zhai, Qinna; Wen, Jianxiang; Yao, Li [Department of Clinical laboratory, Peking University Shenzhen Hospital, Guangdong (China); Li, Pengfei, E-mail: lipengfei@cuhk.edu.hk [Department of pathology, The Chinese University of Hong Kong, Hong Kong (China)

2009-09-04

CDglyTK fusion suicide gene has been well characterized to effectively kill tumor cells. However, the exact mechanism and downstream target genes are not fully understood. In our study, we found that CDglyTK/prodrug treatment works more efficiently in p53 wild-type (HONE1) cells than in p53 mutant (CNE1) cells. We then used adenovirus-mediated gene delivery system to either knockdown or overexpress p53 and its target genes in these cells. Consistent results showed that both p53-PUMA/NOXA/Bcl2-Bax and p53-p21 pathways contribute to the CDglyTK induced tumor cell suppression. Our work for the first time addressed the role of p53 related genes in the CDglyTK/prodrug system.

Increased podocyte Sirtuin-1 function attenuates diabetic kidney injury.

Science.gov (United States)

Hong, Quan; Zhang, Lu; Das, Bhaskar; Li, Zhengzhe; Liu, Bohan; Cai, Guangyan; Chen, Xiangmei; Chuang, Peter Y; He, John Cijiang; Lee, Kyung

2018-06-01

Podocyte injury and loss contribute to the progression of glomerular diseases, including diabetic kidney disease. We previously found that the glomerular expression of Sirtuin-1 (SIRT1) is reduced in human diabetic glomeruli and that the podocyte-specific loss of SIRT1 aggravated albuminuria and worsened kidney disease progression in diabetic mice. SIRT1 encodes an NAD-dependent deacetylase that modifies the activity of key transcriptional regulators affected in diabetic kidneys, including NF-κB, STAT3, p53, FOXO4, and PGC1-α. However, whether the increased glomerular SIRT1 activity is sufficient to ameliorate the pathogenesis of diabetic kidney disease has not been explored. We addressed this by inducible podocyte-specific SIRT1 overexpression in diabetic OVE26 mice. The induction of SIRT1 overexpression in podocytes for six weeks in OVE26 mice with established albuminuria attenuated the progression of diabetic glomerulopathy. To further validate the therapeutic potential of increased SIRT1 activity against diabetic kidney disease, we developed a new, potent and selective SIRT1 agonist, BF175. In cultured podocytes BF175 increased SIRT1-mediated activation of PGC1-α and protected against high glucose-mediated mitochondrial injury. In vivo, administration of BF175 for six weeks in OVE26 mice resulted in a marked reduction in albuminuria and in glomerular injury in a manner similar to podocyte-specific SIRT1 overexpression. Both podocyte-specific SIRT1 overexpression and BT175 treatment attenuated diabetes-induced podocyte loss and reduced oxidative stress in glomeruli of OVE26 mice. Thus, increased SIRT1 activity protects against diabetes-induced podocyte injury and effectively mitigates the progression of diabetic kidney disease. Published by Elsevier Inc.

Alterations of sirtuins in mitochondrial cytochrome c-oxidase deficiency.

Directory of Open Access Journals (Sweden)

Arne Björn Potthast

Full Text Available Sirtuins are NAD+ dependent deacetylases, which regulate mitochondrial energy metabolism as well as cellular response to stress. The NAD/NADH-system plays a crucial role in oxidative phosphorylation linking sirtuins and the mitochondrial respiratory chain. Furthermore, sirtuins are able to directly deacetylate and activate different complexes of the respiratory chain. This prompted us to analyse sirtuin levels in skin fibroblasts from patients with cytochrome c-oxidase (COX deficiency and to test the impact of different pharmaceutical activators of sirtuins (SRT1720, paeonol to modulate sirtuins and possibly respiratory chain enzymes in patient cells in vitro.We assayed intracellular levels of sirtuin 1 and the mitochondrial sirtuins SIRT3 and SIRT4 in human fibroblasts from patients with COX- deficiency. Furthermore, sirtuins were measured after inhibiting complex IV in healthy control fibroblasts by cyanide and after incubation with activators SRT1720 and paeonol. To determine the effect of sirtuin inhibition at the cellular level we measured total cellular acetylation (control and patient cells, with and without treatment by Western blot.We observed a significant decrease in cellular levels of all three sirtuins at the activity, protein and transcriptional level (by 15% to 50% in COX-deficient cells. Additionally, the intracellular concentration of NAD+ was reduced in patient cells. We mimicked the biochemical phenotype of COX- deficiency by incubating healthy fibroblasts with cyanide and observed reduced sirtuin levels. A pharmacological activation of sirtuins resulted in normalized sirtuin levels in patient cells. Hyper acetylation was also reversible after treatment with sirtuin activators. Pharmacological modulation of sirtuins resulted in altered respiratory chain complex activities.We found inhibition of situins 1, 3 and 4 at activity, protein and transcriptional levels in fibroblasts from patient with COX-deficiency. Pharmacological

Sirtuin 6 protects the heart from hypoxic damage

International Nuclear Information System (INIS)

Maksin-Matveev, Anna; Kanfi, Yariv; Hochhauser, Edith; Isak, Ahuva; Cohen, Haim Y.; Shainberg, Asher

2015-01-01

Sirtuin 6 (SIRT6) is a protein associated with prolonged life expectancy. We investigated whether life extension is associated with cardioprotection against hypoxia. The proposed study is to develop approaches to reduce hypoxic damage through the use of the sirtuin pathway and to elucidate the mechanism involved. For that purpose we subjected cardiomyocytes from transgenic mice (TG) with over-expression of SIRT6, to hypoxic stress in cell cultures. We hypothesized that cardiomyocytes from transgenic mice subjected to prolonged hypoxia may release survival factors or fewer damage markers to protect them from hypoxic stress compared with wild type (WT) mice. Lactate dehydrogenase (LDH) and creatine kinase (CK) released to the medium and propidium iodide (PI) binding, were markedly decreased following hypoxia in TG cardiomyocytes. The protective mechanism of SIRT6 over-expression includes the activation of pAMPKα pathway, the increased protein level of B-cell lymphoma 2 (Bcl2), the inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), the decrease of reactive oxygen species (ROS) and the reduction in the protein level of phospho-protein kinase B (pAkt) during hypoxia. Together, all these processes impede the necrosis/apoptosis pathways leading to the improved survival of cardiomyocytes following hypoxia, which might explain life extension. - Highlights: • Sirtuin 6 is a protein associated with prolonged life expectancy. • Over-expression of sirtuin 6 protects cardiocytes from hypoxia and oxidative stress. • Over-expression of sirtuin 6 activates the pAMPKα pathway and the Bcl2 expression. • Over-expression of sirtuin 6 decreases ROS formation and pAkt level during hypoxia. • These pathways protect cardiocytes from hypoxia and might explain lifespan extension

Sirtuin 6 protects the heart from hypoxic damage

Energy Technology Data Exchange (ETDEWEB)

Maksin-Matveev, Anna; Kanfi, Yariv [The Mina and Everard Goodman, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900 (Israel); Hochhauser, Edith [The Laboratory of the Department of Cardiothoracic Surgery, Felsenstein Medical Research Center, Rabin Medical Center, Petach Tikva (Israel); Isak, Ahuva; Cohen, Haim Y. [The Mina and Everard Goodman, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900 (Israel); Shainberg, Asher, E-mail: asher.shainberg@gmail.com [The Mina and Everard Goodman, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900 (Israel)

2015-01-01

Sirtuin 6 (SIRT6) is a protein associated with prolonged life expectancy. We investigated whether life extension is associated with cardioprotection against hypoxia. The proposed study is to develop approaches to reduce hypoxic damage through the use of the sirtuin pathway and to elucidate the mechanism involved. For that purpose we subjected cardiomyocytes from transgenic mice (TG) with over-expression of SIRT6, to hypoxic stress in cell cultures. We hypothesized that cardiomyocytes from transgenic mice subjected to prolonged hypoxia may release survival factors or fewer damage markers to protect them from hypoxic stress compared with wild type (WT) mice. Lactate dehydrogenase (LDH) and creatine kinase (CK) released to the medium and propidium iodide (PI) binding, were markedly decreased following hypoxia in TG cardiomyocytes. The protective mechanism of SIRT6 over-expression includes the activation of pAMPKα pathway, the increased protein level of B-cell lymphoma 2 (Bcl2), the inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB), the decrease of reactive oxygen species (ROS) and the reduction in the protein level of phospho-protein kinase B (pAkt) during hypoxia. Together, all these processes impede the necrosis/apoptosis pathways leading to the improved survival of cardiomyocytes following hypoxia, which might explain life extension. - Highlights: • Sirtuin 6 is a protein associated with prolonged life expectancy. • Over-expression of sirtuin 6 protects cardiocytes from hypoxia and oxidative stress. • Over-expression of sirtuin 6 activates the pAMPKα pathway and the Bcl2 expression. • Over-expression of sirtuin 6 decreases ROS formation and pAkt level during hypoxia. • These pathways protect cardiocytes from hypoxia and might explain lifespan extension.

Sirtuin1 single nucleotide polymorphism (A2191G is a diagnostic marker for vibration-induced white finger disease

Directory of Open Access Journals (Sweden)

Voelter-Mahlknecht Susanne

2012-10-01

Full Text Available Abstract Background Vibration-induced white finger disease (VWF, also known as hand-arm vibration syndrome, is a secondary form of Raynaud’s disease, affecting the blood vessels and nerves. So far, little is known about the pathogenesisof the disease. VWF is associated with an episodic reduction in peripheral blood flow. Sirtuin 1, a class III histone deacetylase, has been described to regulate the endothelium dependent vasodilation by targeting endothelial nitric oxide synthase. We assessed Sirt1single nucleotide polymorphisms in patients with VWF to further elucidate the role of sirtuin 1 in the pathogenesis of VWF. Methods Peripheral blood samples were obtained from 74 patients with VWF (male 93.2%, female 6.8%, median age 53 years and from 317 healthy volunteers (gender equally distributed, below 30 years of age. Genomic DNA was extracted from peripheral blood mononuclear cells and screened for potential Sirt1single nucleotide polymorphisms. Four putative genetic polymorphisms out of 113 within the Sirt1 genomic region (NCBI Gene Reference: NM_012238.3 were assessed. Allelic discrimination was performed by TaqMan-polymerasechainreaction-based allele-specific genotyping single nucleotide polymorphism assays. Results Sirt1single nucleotide polymorphism A2191G (Assay C_25611590_10, rs35224060 was identified within Sirt1 exon 9 (amino acid position 731, Ile → Val, with differing allelic frequencies in the VWF population (A/A: 70.5%, A/G: 29.5%, G/G: 0% and the control population (A/A: 99.7%, A/G: 0.3%, G/G: 0.5%, with significance levels of P U test (two-tailed P t-test and Chi-square test with Yates correction (all two-tailed: P Conclusion We identified theSirt1A2191Gsingle nucleotide polymorphism as a diagnostic marker for VWF.

Distinct HIC1-SIRT1-p53 Loop Deregulation in Lung Squamous Carcinoma and Adenocarcinoma Patients

Directory of Open Access Journals (Sweden)

Ruo-Chia Tseng

2009-08-01

Full Text Available A HIC1-SIRT1-p53 circular loop in which hypermethylation in cancer 1 (HIC1 represses the transcription of SIRT1 that deacetylates and inactivates p53 thus leading to HIC1 inactivation has been identified in cell and animal models. However, the alteration and prognostic effects of HIC1-SIRT1-p53 circular loop have never been demonstrated in human cancer patients. We examine the HIC1-SIRT1-p53 alterations in 118 lung cancer patients to define their etiological roles in tumorigenesis. We found that patients with lung squamous cell carcinoma with low p53 acetylation and SIRT1 expression mostly showed low HIC1 expression, confirming deregulation of HIC1-SIRT1-p53 circular loop in the clinical model. Interestingly, the expression of deleted in breast cancer 1 (DBC1, which blocks the interaction between SIRT1 deacetylase and p53, led to acetylated p53 in patients with lung adenocarcinoma. However, epigenetic alteration of HIC1 promoter by posttranslational modifications of histones and promoter hypermethylation favoring the compacted chromatin production attenuated the transcriptional induction by acetylated p53. Importantly, lung cancer patients with altered HIC1-SIRT1-p53 circular regulation showed poor prognosis. Our data show the first valid clinical evidence of the deregulation of HIC1-SIRT1-p53 loop in lung tumorigenesis and prognosis. Distinct status of p53 acetylation/deacetylation and HIC1 alteration mechanism result from different SIRT1-DBC1 control and epigenetic alteration in lung squamous cell carcinoma and lung adenocarcinoma.

The combination of blueberry juice and probiotics reduces apoptosis of alcoholic fatty liver of mice by affecting SIRT1 pathway

Directory of Open Access Journals (Sweden)

Zhu J

2016-05-01

Full Text Available Juanjuan Zhu,1,2,* Tingting Ren,3,* Mingyu Zhou,2 Mingliang Cheng2 1First Hospital Affiliated to Suzhou University, Suzhou, 2Department of Infectious Diseases, 3Biochemistry Department, Affiliated Hospital of Guiyang Medical College, Guiyang, People’s Republic of China *These authors contributed equally to this work Purpose: To explore the effects of the combination of blueberry juice and probiotics on the apoptosis of alcoholic fatty liver disease (AFLD.Methods: Healthy C57BL/6J mice were used in the control group (CG. AFLD mice models were established with Lieber–DeCarli ethanol diet and evenly assigned to six groups with ­different treatments: MG (model, SI (SIRT1 [sirtuin type 1] small interfering RNA [siRNA], BJ (blueberry juice, BJSI (blueberry juice and SIRT1 siRNA, BJP (blueberry juice and probiotics, and BJPSI (blueberry juice, probiotics, and SIRT1 siRNA. Hepatic tissue was observed using hematoxylin and eosin (HE and Oil Red O (ORO staining. Biochemical indexes of the blood serum were analyzed. The levels of SIRT1, caspase-3, forkhead box protein O1 (FOXO1, FasL (tumor necrosis factor ligand superfamily member 6, BAX, and Bcl-2 were measured by reverse transcription-polymerase chain reaction and Western blotting.Results: HE and ORO staining showed that the hepatocytes were heavily destroyed with large lipid droplets in MG and SI groups, while the severity was reduced in the CG, BJ, and BJP groups (P<0.05. The levels of superoxide dismutase (SOD, reduced glutathione (GSH, and high-density lipoprotein-cholesterol (HDL-C were increased in BJ and BJP groups when compared with the model group (P<0.05. In contrast, the levels of aspartate aminotransferase (AST and alanine aminotransferase (ALT, total triglycerides (TGs, total cholesterol, low-density lipoprotein-cholesterol (LDL-C, and malondialdehyde (MDA were lower in BJ and BJP groups than in the model group (P<0.05. The level of SIRT1 was increased, while the levels of FOXO1

p21(Waf1/Cip1) expression and the p53/MDM2 feedback loop in gastric carcinogenesis

NARCIS (Netherlands)

Craanen, M. E.; Blok, P.; Offerhaus, G. J.; Meijer, G. A.; Dekker, W.; Kuipers, E. J.; Meuwissen, S. G.

1999-01-01

Data are non-existent regarding coincidental alterations in the expression of p53 and its downstream target genes MDM2 and p21(Waf1/Cip1) in gastric carcinogenesis. An immunohistochemical study was therefore performed to examine the interrelationships of p53, MDM2, and p21(Waf1/Cip1) expression in a

SIAH1-induced p34SEI-1 polyubiquitination/degradation mediates p53 preferential vitamin C cytotoxicity.

Science.gov (United States)

Lee, Soonduck; Kim, Jinsun; Jung, Samil; Li, Chengping; Yang, Young; Kim, Keun Il; Lim, Jong-Seok; Kim, Yonghwan; Cheon, Choong-Il; Lee, Myeong-Sok

2015-03-01

Vitamin C is considered as an important anticancer therapeutic agent although this view is debatable. In this study, we introduce a physiological mechanism demonstrating how vitamin C exerts anticancer activity that induces cell cycle arrest and apoptosis. Our previous and current data reveal that p53 tumor suppressor is the prerequisite factor for stronger anticancer effects of vitamin C. In addition, vitamin C-mediated cancer cell cytotoxicity appears to be achieved at least partly through the downregulation of the p34SEI-1 oncoprotein. Our previous study showed that p34SEI-1 increases the survival of various types of cancer cells by inhibiting their apoptosis. Present data suggest that vitamin C treatment decreases the p34SEI-1 expression at the protein level and therefore alleviates its anti-apoptotic activity. Of note, SIAH1, E3 ubiquitin ligase, appears to be responsible for the p34SEI-1 polyubiquitination and its subsequent degradation, which is dependent on p53. In summary, vitamin C increases cancer cell death by inducing SIAH1-mediated polyubiquitination/degradation of the p34SEI-1 oncoprotein in a p53-dependent manner.

Chk1 inhibition activates p53 through p38 MAPK in tetraploid cancer cells.

Science.gov (United States)

Vitale, Ilio; Senovilla, Laura; Galluzzi, Lorenzo; Criollo, Alfredo; Vivet, Sonia; Castedo, Maria; Kroemer, Guido

2008-07-01

We have previously shown that tetraploid cancer cells succumb through a p53-dependent apoptotic pathway when checkpoint kinase 1 (Chk1) is depleted by small interfering RNAs (siRNAs) or inhibited with 7-hydroxystaurosporine (UCN-01). Here, we demonstrate that Chk1 inhibition results in the activating phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK). Depletion of p38 MAPK by transfection with a siRNA targeting the alpha isoform of p38 MAPK (p38alpha MAPK) abolishes the phosphorylation of p53 on serines 15 and 46 that is induced by Chk1 knockdown. The siRNA-mediated downregulation and pharmacological inhibition of p38alpha MAPK (with SB 203580) also reduces cell death induced by Chk1 knockdown or UCN-01. These results underscore the role of p38 MAPK as a pro-apoptotic kinase in the p53-dependant pathway for the therapeutic elimination of polyploidy cells.

Pax3 stimulates p53 ubiquitination and degradation independent of transcription.

Directory of Open Access Journals (Sweden)

Xiao Dan Wang

Full Text Available Pax3 is a developmental transcription factor that is required for neural tube and neural crest development. We previously showed that inactivating the p53 tumor suppressor protein prevents neural tube and cardiac neural crest defects in Pax3-mutant mouse embryos. This demonstrates that Pax3 regulates these processes by blocking p53 function. Here we investigated the mechanism by which Pax3 blocks p53 function.We employed murine embryonic stem cell (ESC-derived neuronal precursors as a cell culture model of embryonic neuroepithelium or neural crest. Pax3 reduced p53 protein stability, but had no effect on p53 mRNA levels or the rate of p53 synthesis. Full length Pax3 as well as fragments that contained either the DNA-binding paired box or the homeodomain, expressed as GST or FLAG fusion proteins, physically associated with p53 and Mdm2 both in vitro and in vivo. In contrast, Splotch Pax3, which causes neural tube and neural crest defects in homozygous embryos, bound weakly, or not at all, to p53 or Mdm2. The paired domain and homeodomain each stimulated Mdm2-mediated ubiquitination of p53 and p53 degradation in the absence of the Pax3 transcription regulatory domains, whereas Splotch Pax3 did not stimulate p53 ubiquitination or degradation.Pax3 inactivates p53 function by stimulating its ubiquitination and degradation. This process utilizes the Pax3 paired domain and homeodomain but is independent of DNA-binding and transcription regulation. Because inactivating p53 is the only required Pax3 function during neural tube closure and cardiac neural crest development, and inactivating p53 does not require Pax3-dependent transcription regulation, this indicates that Pax3 is not required to function as a transcription factor during neural tube closure and cardiac neural crest development. These findings further suggest novel explanations for PAX3 functions in human diseases, such as in neural crest-derived cancers and Waardenburg syndrome types 1 and 3.

The role of Forkhead-box Class O (FoxO) transcription factors in cancer: A target for the management of cancer

International Nuclear Information System (INIS)

Reagan-Shaw, Shannon; Ahmad, Nihal

2007-01-01

Human Forkhead-Box Class O (FoxO) transcription factors are primarily regulated through the phosphoinositide-3-kinase (PI3k)-Akt pathway via phosphorylation and nuclear exclusion. Acetylation and ubiquitination represent another level of regulation for FoxO proteins and FoxO-regulated gene expression. FoxO factors can act as tumor suppressors; however, the loss of FoxO function leads to increased cellular survival and a predisposition to neoplasia, especially of epithelial cancers. Based on the critical role of FoxO signaling, this family of transcription factors appears to be a promising target for future drug discovery for epithelial cancers. This review describes mechanism of the regulation of FoxO proteins and their role in epithelial cancers. Based on the current knowledge and studies in the past decade, we suggest that the development of novel agents which specifically activate FoxO members could be useful in the prevention as well as treatment of cancer in general and epithelial cancers in particular

FOXP1 forkhead transcription factor is associated with the pathogenesis of endometrial cancer

Directory of Open Access Journals (Sweden)

Makito Mizunuma

2016-05-01

Full Text Available Endometrial cancers are mostly estrogen-dependent. FOXP1 is a P subfamily of forkhead box (FOX, and known as an estrogen-responsive transcription factor. The aims of this study were to examine histological location of FOXP1 in normal and malignant endometrium, and to investigate a possible association between FOXP1 and other factors considered to be involved in pathogenesis of endometrial cancer. The levels of FOXP1, estrogen receptor (ERα, and ERβ expression were examined immunohistochemically in normal and malignant endometrium obtained from 75 women (8 normal, 8 atypical endometrial hyperplasia, and 59 endometrial cancers from grade 1 to 3. The effects of estrogen on ERα, FOXP1, KRAS, and PTEN expression were analyzed in telomerase-immortalized human endometrial stromal cells (T HESCs by Western blotting. Western blotting was also used to examine the effect of FOXP1 plasmid DNA or siRNA transfection on KRAS and PTEN expression in Ishikawa cells (well differentiated endometrioid adenocarcinoma, HEC-50B cells (poorly differentiated endometrioid adenocarcinoma, and T HESCs, respectively. FOXP1 was expressed in normal and malignant endometrium, but the rate of expression was different depending upon menstrual cycle and pathological grade of malignancy. FOXP1 expression in nucleus and cytoplasm of grade 3 endometrioid cancers was significantly lower than that of grade 1 and 2 ones. Estradiol increased levels of FOXP1 and KRAS expression in a dose- and time-dependent manner in T HESCs cells, and FOXP1 transfection or knockdown led to increase or decrease of KRAS expression but not PTEN. KRAS expression level was significantly related to FOXP1 and ERα levels in cancer tissues. Estradiol did not affect KRAS expression in T HESCs cells transfected with FOXP1 siRNA. These results suggest that FOXP1 is involved in estrogen dependent endometrial cancers through KRAS pathway.

Expression and Effects of High-Mobility Group Box 1 in Cervical Cancer

Directory of Open Access Journals (Sweden)

Xiaoao Pang

2014-05-01

Full Text Available We investigated the significance of high- mobility group box1 (HMGB1 and T-cell-mediated immunity and prognostic value in cervical cancer. HMGB1, forkhead/winged helix transcription factor p3 (Foxp3, IL-2, and IL-10 protein expression was analyzed in 100 cervical tissue samples including cervical cancer, cervical intraepithelial neoplasia (CIN, and healthy control samples using immunohistochemistry. Serum squamous cell carcinoma antigen (SCC-Ag was immunoradiometrically measured in 32 serum samples from 37 cases of squamous cervical cancer. HMGB1 and SCC-Ag were then correlated to clinicopathological characteristics. HMGB1 expression tends to increase as cervical cancer progresses and it was found to be significantly correlated to FIGO stage and lymph node metastasis. These findings suggest that HMGB1 may be a useful prognostic indicator of cervical carcinoma. In addition, there were significant positive relationships between HMGB1 and FOXP3 or IL-10 expression (both p < 0.05. In contrast, HMGB1 and IL-2 expression was negatively correlated (p < 0.05. HMGB1 expression may activate Tregs or facilitate Th2 polarization to promote immune evasion of cervical cancer. Elevated HMGB1 protein in cervical carcinoma samples was associated with a high recurrence of HPV infection in univariate analysis (p < 0.05. HMGB1 expression and levels of SCC-Ag were directly correlated in SCC (p < 0.05. Thus, HMGB1 may be a useful biomarker for patient prognosis and cervical cancer prediction and treatment.

OTUD5 regulates p53 stability by deubiquitinating p53.

Directory of Open Access Journals (Sweden)

Judong Luo

Full Text Available The p53 tumour suppressor protein is a transcription factor that prevents oncogenic progression by activating the expression of apoptosis and cell-cycle arrest genes in stressed cells. The stability of p53 is tightly regulated by ubiquitin-dependent degradation, driven mainly by its negative regulators ubiquitin ligase MDM2.In this study, we have identified OTUD5 as a DUB that interacts with and deubiquitinates p53. OTUD5 forms a direct complex with p53 and controls level of ubiquitination. The function of OTUD5 is required to allow the rapid activation of p53-dependent transcription and a p53-dependent apoptosis in response to DNA damage stress.As a novel deubiquitinating enzyme for p53, OTUD5 is required for the stabilization and the activation of a p53 response.

Forkhead box A1 (FOXA1) is a key mediator of insulin-like growth factor I (IGF-I) activity.

Science.gov (United States)

Potter, Adam S; Casa, Angelo J; Lee, Adrian V

2012-01-01

The insulin-like growth factor receptor (IGF-IR) has been implicated in a number of human tumors, including breast cancer. Data from human breast tumors has demonstrated that IGF-IR is over-expressed and hyper-phosphorylated. Additionally, microarray analysis has shown that IGF-I treatment of MCF7 cells leads to a gene signature comprised of induced and repressed genes, which correlated with luminal B tumors. FOXA1, a forkhead family transcription factor, has been shown to be crucial for mammary ductal morphogenesis, similar to IGF-IR, and expressed at high levels in luminal subtype B breast tumors. Here, we investigated the relationship between FOXA1 and IGF-I action in breast cancer cells. We show that genes regulated by IGF-I are enriched for FOXA1 binding sites, and knock down of FOXA1 blocked the ability of IGF-I to regulate gene expression. IGF-I treatment of MCF7 cells increased the half-life of FOXA1 protein and this increase in half-life appeared to be dependent on canonical IGF-I signal transduction through both MAPK and AKT pathways. Finally, knock down of FOXA1 led to a decreased ability of IGF-I to induce proliferation and protect against apoptosis. Together, these results demonstrate that IGF-I can increase the stability of FOXA1 protein expression and place it as a critical mediator of IGF-I regulation of gene expression and IGF-I-mediated biological responses. Copyright © 2011 Wiley Periodicals, Inc.

Could Sirtuin Activities Modify ALS Onset and Progression?

Science.gov (United States)

Tang, Bor Luen

2017-10-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a complex etiology. Sirtuins have been implicated as disease-modifying factors in several neurological disorders, and in the past decade, attempts have been made to check if manipulating Sirtuin activities and levels could confer benefit in terms of neuroprotection and survival in ALS models. The efforts have largely focused on mutant SOD1, and while limited in scope, the results were largely positive. Here, the body of work linking Sirtuins with ALS is reviewed, with discussions on how Sirtuins and their activities may impact on the major etiological mechanisms of ALS. Moving forward, it is important that the potentially beneficial effect of Sirtuins in ALS disease onset and progression are assessed in ALS models with TDP-43, FUS, and C9orf72 mutations.

Fenofibrate inhibits atrial metabolic remodelling in atrial fibrillation through PPAR-α/sirtuin 1/PGC-1α pathway.

Science.gov (United States)

Liu, Guang-Zhong; Hou, Ting-Ting; Yuan, Yue; Hang, Peng-Zhou; Zhao, Jing-Jing; Sun, Li; Zhao, Guan-Qi; Zhao, Jing; Dong, Jing-Mei; Wang, Xiao-Bing; Shi, Hang; Liu, Yong-Wu; Zhou, Jing-Hua; Dong, Zeng-Xiang; Liu, Yang; Zhan, Cheng-Chuang; Li, Yue; Li, Wei-Min

2016-03-01

Atrial metabolic remodelling is critical for the process of atrial fibrillation (AF). The PPAR-α/sirtuin 1 /PPAR co-activator α (PGC-1α) pathway plays an important role in maintaining energy metabolism. However, the effect of the PPAR-α agonist fenofibrate on AF is unclear. Therefore, the aim of this study was to determine the effect of fenofibrate on atrial metabolic remodelling in AF and explore its possible mechanisms of action. The expression of metabolic proteins was examined in the left atria of AF patients. Thirty-two rabbits were divided into sham, AF (pacing with 600 beats·min(-1) for 1 week), fenofibrate treated (pretreated with fenofibrate before pacing) and fenofibrate alone treated (for 2 weeks) groups. HL-1 cells were subjected to rapid pacing in the presence or absence of fenofibrate, the PPAR-α antagonist GW6471 or sirtuin 1-specific inhibitor EX527. Metabolic factors, circulating biochemical metabolites, atrial electrophysiology, adenine nucleotide levels and accumulation of glycogen and lipid droplets were assessed. The PPAR-α/sirtuin 1/PGC-1α pathway was significantly inhibited in AF patients and in the rabbit/HL-1 cell models, resulting in a reduction of key downstream metabolic factors; this effect was significantly restored by fenofibrate. Fenofibrate prevented the alterations in circulating biochemical metabolites, reduced the level of adenine nucleotides and accumulation of glycogen and lipid droplets, reversed the shortened atrial effective refractory period and increased risk of AF. Fenofibrate inhibited atrial metabolic remodelling in AF by regulating the PPAR-α/sirtuin 1/PGC-1α pathway. The present study may provide a novel therapeutic strategy for AF. © 2016 The British Pharmacological Society.

RNA content in the nucleolus alters p53 acetylation via MYBBP1A

Science.gov (United States)

Kuroda, Takao; Murayama, Akiko; Katagiri, Naohiro; Ohta, Yu-mi; Fujita, Etsuko; Masumoto, Hiroshi; Ema, Masatsugu; Takahashi, Satoru; Kimura, Keiji; Yanagisawa, Junn

2011-01-01

A number of external and internal insults disrupt nucleolar structure, and the resulting nucleolar stress stabilizes and activates p53. We show here that nucleolar disruption induces acetylation and accumulation of p53 without phosphorylation. We identified three nucleolar proteins, MYBBP1A, RPL5, and RPL11, involved in p53 acetylation and accumulation. MYBBP1A was tethered to the nucleolus through nucleolar RNA. When rRNA transcription was suppressed by nucleolar stress, MYBBP1A translocated to the nucleoplasm and facilitated p53–p300 interaction to enhance p53 acetylation. We also found that RPL5 and RPL11 were required for rRNA export from the nucleolus. Depletion of RPL5 or RPL11 blocked rRNA export and counteracted reduction of nucleolar RNA levels caused by inhibition of rRNA transcription. As a result, RPL5 or RPL11 depletion inhibited MYBBP1A translocation and p53 activation. Our observations indicated that a dynamic equilibrium between RNA generation and export regulated nucleolar RNA content. Perturbation of this balance by nucleolar stress altered the nucleolar RNA content and modulated p53 activity. PMID:21297583

Deficiency of G1 regulators P53, P21Cip1 and/or pRb decreases hepatocyte sensitivity to TGFβ cell cycle arrest

Directory of Open Access Journals (Sweden)

Harrison David J

2007-11-01

Full Text Available Abstract Background TGFβ is critical to control hepatocyte proliferation by inducing G1-growth arrest through multiple pathways leading to inhibition of E2F transcription activity. The retinoblastoma protein pRb is a key controller of E2F activity and G1/S transition which can be inhibited in viral hepatitis. It is not known whether the impairment of pRb would alter the growth inhibitory potential of TGFβ in disease. We asked how Rb-deficiency would affect responses to TGFβ-induced cell cycle arrest. Results Primary hepatocytes isolated from Rb-floxed mice were infected with an adenovirus expressing CRE-recombinase to delete the Rb gene. In control cells treatment with TGFβ prevented cells to enter S phase via decreased cMYC activity, activation of P16INK4A and P21Cip and reduction of E2F activity. In Rb-null hepatocytes, cMYC activity decreased slightly but P16INK4A was not activated and the great majority of cells continued cycling. Rb is therefore central to TGFβ-induced cell cycle arrest in hepatocytes. However some Rb-null hepatocytes remained sensitive to TGFβ-induced cell cycle arrest. As these hepatocytes expressed very high levels of P21Cip1 and P53 we investigated whether these proteins regulate pRb-independent signaling to cell cycle arrest by evaluating the consequences of disruption of p53 and p21Cip1. Hepatocytes deficient in p53 or p21Cip1 showed diminished growth inhibition by TGFβ. Double deficiency had a similar impact showing that in cells containing functional pRb; P21Cip and P53 work through the same pathway to regulate G1/S in response to TGFβ. In Rb-deficient cells however, p53 but not p21Cip deficiency had an additive effect highlighting a pRb-independent-P53-dependent effector pathway of inhibition of E2F activity. Conclusion The present results show that otherwise genetically normal hepatocytes with disabled p53, p21Cip1 or Rb genes respond less well to the antiproliferative effects of TGFβ. As the function of

ER, p53 and MIB-1 are significantly associated with malignant phyllodes tumor

Directory of Open Access Journals (Sweden)

Nurhayati H Munawer

2012-12-01

Full Text Available Background: Phyllodes tumors (PT are rare. We evaluated the expression status of ER, Bcl2, p53, and MIB-1 protein in these tumors. Methods: One hundred and ninety-three tumors were examined using immunohistochemistry on tissue microarray. Results: ERβ (p <0.001, and p53 (p=0.006 in the stromal component were associated with tumor size. p53 expression was significantly associated with both epithelial and stro­mal components of malignant PTs (p<0.05. In PT, the decreased expressions of p53 and MIB-1 were significantly different with positive Bcl2 protein expression in epi­thelial component (p=0.000. Besides, MIB-1 was also found to be associated with ERα and ERβ in stromal component (p=0.000. Conclusion: The expression of p53 with tumor size and histological grade in PTs may increase risk for malignancy.

Down-regulation of Wild-type p53-induced Phosphatase 1 (Wip1) Plays a Critical Role in Regulating Several p53-dependent Functions in Premature Senescent Tumor Cells*

Science.gov (United States)

Crescenzi, Elvira; Raia, Zelinda; Pacifico, Francesco; Mellone, Stefano; Moscato, Fortunato; Palumbo, Giuseppe; Leonardi, Antonio

2013-01-01

Premature or drug-induced senescence is a major cellular response to chemotherapy in solid tumors. The senescent phenotype develops slowly and is associated with chronic DNA damage response. We found that expression of wild-type p53-induced phosphatase 1 (Wip1) is markedly down-regulated during persistent DNA damage and after drug release during the acquisition of the senescent phenotype in carcinoma cells. We demonstrate that down-regulation of Wip1 is required for maintenance of permanent G2 arrest. In fact, we show that forced expression of Wip1 in premature senescent tumor cells induces inappropriate re-initiation of mitosis, uncontrolled polyploid progression, and cell death by mitotic failure. Most of the effects of Wip1 may be attributed to its ability to dephosphorylate p53 at Ser15 and to inhibit DNA damage response. However, we also uncover a regulatory pathway whereby suppression of p53 Ser15 phosphorylation is associated with enhanced phosphorylation at Ser46, increased p53 protein levels, and induction of Noxa expression. On the whole, our data indicate that down-regulation of Wip1 expression during premature senescence plays a pivotal role in regulating several p53-dependent aspects of the senescent phenotype. PMID:23612976

Tumor Suppressor p53 Stimulates the Expression of Epstein-Barr Virus Latent Membrane Protein 1.

Science.gov (United States)

Wang, Qianli; Lingel, Amy; Geiser, Vicki; Kwapnoski, Zachary; Zhang, Luwen

2017-10-15

Epstein-Barr virus (EBV) is associated with multiple human malignancies. EBV latent membrane protein 1 (LMP1) is required for the efficient transformation of primary B lymphocytes in vitro and possibly in vivo The tumor suppressor p53 plays a seminal role in cancer development. In some EBV-associated cancers, p53 tends to be wild type and overly expressed; however, the effects of p53 on LMP1 expression is not clear. We find LMP1 expression to be associated with p53 expression in EBV-transformed cells under physiological and DNA damaging conditions. DNA damage stimulates LMP1 expression, and p53 is required for the stimulation. Ectopic p53 stimulates endogenous LMP1 expression. Moreover, endogenous LMP1 blocks DNA damage-mediated apoptosis. Regarding the mechanism of p53-mediated LMP1 expression, we find that interferon regulatory factor 5 (IRF5), a direct target of p53, is associated with both p53 and LMP1. IRF5 binds to and activates a LMP1 promoter reporter construct. Ectopic IRF5 increases the expression of LMP1, while knockdown of IRF5 leads to reduction of LMP1. Furthermore, LMP1 blocks IRF5-mediated apoptosis in EBV-infected cells. All of the data suggest that cellular p53 stimulates viral LMP1 expression, and IRF5 may be one of the factors for p53-mediated LMP1 stimulation. LMP1 may subsequently block DNA damage- and IRF5-mediated apoptosis for the benefits of EBV. The mutual regulation between p53 and LMP1 may play an important role in EBV infection and latency and its related cancers. IMPORTANCE The tumor suppressor p53 is a critical cellular protein in response to various stresses and dictates cells for various responses, including apoptosis. This work suggests that an Epstein-Bar virus (EBV) principal viral oncogene is activated by cellular p53. The viral oncogene blocks p53-mediated adverse effects during viral infection and transformation. Therefore, the induction of the viral oncogene by p53 provides a means for the virus to cope with infection and

Sirtuin 1 Agonist Minimizes Injury and Improves the Immune Response Following Traumatic Shock.

Science.gov (United States)

Luciano, Jason A; Kautza, Benjamin; Darwiche, Sophie; Martinez, Silvia; Stratimirovic, Sladjana; Waltz, Paul; Sperry, Jason; Rosengart, Matthew; Shiva, Sruti; Zuckerbraun, Brian S

2015-08-01

Survival from traumatic injury requires a coordinated and controlled inflammatory and immune response. Mitochondrial and metabolic responses to stress have been shown to play a role in these inflammatory and immune responses. We hypothesized that increases in mitochondrial biogenesis via a sirtuin 1 agonist would decrease tissue injury and partially ameliorate the immunosuppression seen following trauma. C57Bl/6 mice were subjected to a multiple trauma model. Mice were pretreated with either 100 mg/kg per day of the sirtuin 1 agonist, Srt1720, via oral gavage for 2 days prior to trauma and extended until the day the animals were killed, or they were pretreated with peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) siRNA via hydrodynamic tail vein injection 48 h prior to trauma. Markers for mitochondrial function and biogenesis were measured in addition to splenocyte proliferative capacity and bacterial clearance. Srt1720 was noted to improve mitochondrial biogenesis, mitochondrial function, and complex IV activity following traumatic injury (P hepatic injury with significant reductions in serum alanine aminotransferase levels seen in mice treated with srt1720. Splenocyte proliferative capacity and intraperitoneal bacterial clearance were evaluated as markers for overall immune function following trauma-hemorrhage. Treatment with Srt1720 minimized the trauma-induced decreases in splenocyte proliferation (P clearance. The PGC1α signaling pathway is an important regulator of mitochondrial function and biogenesis, which can potentially be harnessed to protect against hepatic injury and minimize the immunosuppression that is seen following trauma-hemorrhage.

53BP1 and USP28 mediate p53-dependent cell cycle arrest in response to centrosome loss and prolonged mitosis.

Science.gov (United States)

Fong, Chii Shyang; Mazo, Gregory; Das, Tuhin; Goodman, Joshua; Kim, Minhee; O'Rourke, Brian P; Izquierdo, Denisse; Tsou, Meng-Fu Bryan

2016-07-02

Mitosis occurs efficiently, but when it is disturbed or delayed, p53-dependent cell death or senescence is often triggered after mitotic exit. To characterize this process, we conducted CRISPR-mediated loss-of-function screens using a cell-based assay in which mitosis is consistently disturbed by centrosome loss. We identified 53BP1 and USP28 as essential components acting upstream of p53, evoking p21-dependent cell cycle arrest in response not only to centrosome loss, but also to other distinct defects causing prolonged mitosis. Intriguingly, 53BP1 mediates p53 activation independently of its DNA repair activity, but requiring its interacting protein USP28 that can directly deubiquitinate p53 in vitro and ectopically stabilize p53 in vivo. Moreover, 53BP1 can transduce prolonged mitosis to cell cycle arrest independently of the spindle assembly checkpoint (SAC), suggesting that while SAC protects mitotic accuracy by slowing down mitosis, 53BP1 and USP28 function in parallel to select against disturbed or delayed mitosis, promoting mitotic efficiency.

Sirtuin 1 gene rs2273773 C>T single nucleotide polymorphism and ...

African Journals Online (AJOL)

Aida Abdeen Mahmoud

2015-12-24

Dec 24, 2015 ... Abstract Background: Sirtuin-1 (SIRT-1), a protein has been found to protect the cells against oxidative stress ... rs2273773 C > T SNP and serum markers of protein oxida- tion (protein ..... tance and pulmonary dynamic compliance. Treatment ... [4] Autiero I, Costantini S, Colonna G. Human sirt-1: molecular.

The sirtuins: Markers of metabolic health.

Science.gov (United States)

Covington, Jeffrey D; Bajpeyi, Sudip

2016-01-01

The sirtuins represent a class of proteins first discovered orthologus to the yeast silent information regulator 2 protein that have been retained in mammalian species. Currently, seven sirtuins have been identified in humans, and their functions currently surpass their originally identified role as histone deacetylase and chromatin silencers to encompass nutrient sensing and metabolic function. All seven sirtuins require NAD(+) in order to carry out their enzymatic activity, and thus become activated in conditions of nutrient depletion, starvation, and cellular stress. Caloric restriction and increased physical activity have been postulated, though perhaps controversially, to mediate sirtuin function. Here, we review the current literature surrounding the functions of the seven human sirtuins, mediators of their function, and the roles they play in metabolic health related to dietary and physical activity interventions. Despite the controversy surrounding sirtuin function with regard to longevity, we have aimed to show that regardless of its effects on aging, sirtuin function is pivotal to pathways involving metabolic health, and should therefore be investigated with regard to improving metabolic diseases such as obesity and type 2 diabetes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MG132 plus apoptosis antigen-1 (APO-1) antibody cooperate to restore p53 activity inducing autophagy and p53-dependent apoptosis in HPV16 E6-expressing keratinocytes.

Science.gov (United States)

Lagunas-Martínez, Alfredo; García-Villa, Enrique; Arellano-Gaytán, Magaly; Contreras-Ochoa, Carla O; Dimas-González, Jisela; López-Arellano, María E; Madrid-Marina, Vicente; Gariglio, Patricio

2017-01-01

The E6 oncoprotein can interfere with the ability of infected cells to undergo programmed cell death through the proteolytic degradation of proapoptotic proteins such as p53, employing the proteasome pathway. Therefore, inactivation of the proteasome through MG132 should restore the activity of several proapoptotic proteins. We investigated whether in HPV16 E6-expressing keratinocytes (KE6 cells), the restoration of p53 levels mediated by MG132 and/or activation of the CD95 pathway through apoptosis antigen-1 (APO-1) antibody are responsible for the induction of apoptosis. We found that KE6 cells underwent apoptosis mainly after incubation for 24 h with MG132 alone or APO-1 plus MG132. Both treatments activated the extrinsic and intrinsic apoptosis pathways. Autophagy was also activated, principally by APO-1 plus MG132. Inhibition of E6-mediated p53 proteasomal degradation by MG132 resulted in the elevation of p53 protein levels and its phosphorylation in Ser46 and Ser20; the p53 protein was localized mainly at nucleus after treatment with MG132 or APO-1 plus MG132. In addition, induction of its transcriptional target genes such as p21, Bax and TP53INP was observed 3 and 6 h after treatment. Also, LC3 mRNA was induced after 3 and 6 h, which correlates with lipidation of LC3B protein and induction of autophagy. Finally, using pifithrin alpha we observed a decrease in apoptosis induced by MG132, and by APO-1 plus MG132, suggesting that restoration of APO-1 sensitivity occurs in part through an increase in both the levels and the activity of p53. The use of small molecules to inhibit the proteasome pathway might permit the activation of cell death, providing new opportunities for CC treatment.

Sirtuin 1 gene rs2273773 C >T single nucleotide polymorphism and ...

African Journals Online (AJOL)

Background: Sirtuin-1 (SIRT-1), a protein has been found to protect the cells against oxidative stress due to its deacetylase activity. In this investigation, we aimed to study SIRT-1 gene rs2273773 C >T single nucleotide polymorphism and markers of serum protein oxidation (protein carbonyl and sulfhydryl groups) in ...

Polycomb Group Protein PHF1 Regulates p53-dependent Cell Growth Arrest and Apoptosis*

Science.gov (United States)

Yang, Yang; Wang, Chenji; Zhang, Pingzhao; Gao, Kun; Wang, Dejie; Yu, Hongxiu; Zhang, Ting; Jiang, Sirui; Hexige, Saiyin; Hong, Zehui; Yasui, Akira; Liu, Jun O.; Huang, Haojie; Yu, Long

2013-01-01

Polycomb group protein PHF1 is well known as a component of a novel EED-EZH2·Polycomb repressive complex 2 complex and plays important roles in H3K27 methylation and Hox gene silencing. PHF1 is also involved in the response to DNA double-strand breaks in human cells, promotes nonhomologous end-joining processes through interaction with Ku70/Ku80. Here, we identified another function of PHF1 as a potential p53 pathway activator in a pathway screen using luminescence reporter assay. Subsequent studies showed PHF1 directly interacts with p53 proteins both in vivo and in vitro and co-localized in nucleus. PHF1 binds to the C-terminal regulatory domain of p53. Overexpression of PHF1 elevated p53 protein level and prolonged its turnover. Knockdown of PHF1 reduced p53 protein level and its target gene expression both in normal state and DNA damage response. Mechanically, PHF1 protects p53 proteins from MDM2-mediated ubiquitination and degradation. Furthermore, we showed that PHF1 regulates cell growth arrest and etoposide-induced apoptosis in a p53-dependent manner. Finally, PHF1 expression was significantly down-regulated in human breast cancer samples. Taken together, we establish PHF1 as a novel positive regulator of the p53 pathway. These data shed light on the potential roles of PHF1 in tumorigenesis and/or tumor progression. PMID:23150668

The anti-Müllerian hormone (AMH) induces forkhead box L2 (FOXL2) expression in primary culture of human granulosa cells in vitro.

Science.gov (United States)

Sacchi, Sandro; Marinaro, Federica; Xella, Susanna; Marsella, Tiziana; Tagliasacchi, Daniela; La Marca, Antonio

2017-09-01

Anti-Müllerian hormone (AMH) and forkhead box L2 (FOXL2) are two pivotal genes expressed in human granulosa cells (hGCs) where both genes share similar inhibitory functions on activation and follicular growth in order to preserve the ovarian follicle reserve. Furthermore, AMH and FOXL2 contribute to inhibit steroidogenesis, decreasing or preventing the activation of gonadotrophin-dependent aromatase CYP19A1 cytochrome P450 family 19 subfamily A member 1 (CYP19A1). The purpose of this study is to evaluate the role of AMH in regulating the expression of FOXL2. Primary cultures of hGCs were treated with increasing concentrations of recombinant human AMH (rhAMH; range 10-100 ng/ml) for 3 h. Negative controls were performed using corresponding amounts of AMH vehicle. Total RNA or proteins were purified and quantified by spectrophotometry. FOXL2 and CYP19A1 gene expression, normalized by reference gene ribosomal protein S7 (RpS7), was evaluated by RT-qPCR. Each reaction was repeated in triplicate. Statistical analysis was performed. Extracted proteins were analyzed by immunoblot using anti-FOXL2 and anti-β-actin as primary antibodies. rhAMH treatments tested did not modulate the basal expression of aromatase CYP19A1 gene. rhAMH (50 ng/ml) was able to increase FOXL2 gene expression and its intracellular content. This study demonstrated the existence of an AMH-FOXL2 relationship in hGCs. AMH is capable of increasing both gene and protein expression of FOXL2. Because FOXL2 induces AMH transcription, these ovarian factors could be finely regulated by a positive feedback loop mechanism to preserve the ovarian follicle reserve.

Radiotherapy modulates expression of EGFR, ERCC1 and p53 in cervical cancer

Energy Technology Data Exchange (ETDEWEB)

Almeida, V.H. de; Melo, A.C. de; Nogueira-Rodrigues, A.; Pimenta-Inada, H.K.; Alves, F.G.; Moralez, G.; Thiago, L.S.; Ferreira, C.G.; Sternberg, C., E-mail: diretoriaexecutiva@sboc.org.br [Instituto Nacional de Câncer (INCA), Rio de Janeiro, RJ (Brazil); Meira, D.D. [Universidade Federal do Espírito Santo (UFES), Vitória, ES (Brazil); Pires, A.C. [Fonte Medicina Diagnóstica, Niterói, RJ (Brazil)

2018-02-01

Cervical cancer is a public health problem and the molecular mechanisms underlying radioresistance are still poorly understood. Here, we evaluated the modulation of key molecules involved in cell proliferation, cell cycle and DNA repair in cervical cancer cell lines (CASKI and C33A) and in malignant tissues biopsied from 10 patients before and after radiotherapy. The expression patterns of epidermal growth factor receptor (EGFR), excision repair cross-complementation group 1 (ERCC1) and p53 were evaluated in cancer cell lines by quantitative PCR and western blotting, and in human malignant tissues by immunohistochemistry. The mutation status of TP53 gene was evaluated by direct sequencing. Among cell lines, absent or weak modulations of EGFR, ERCC1 and p53 were observed after exposure to 1.8 Gy. Conversely, increased expressions of p53 (5/10 patients; P=0.0239), ERCC1 (5/10 patients; P=0.0294) and EGFR (4/10 patients; P=0.1773) were observed in malignant tissues after radiotherapy with the same radiation dose. TP53 mutations were found only in one patient. Here we show that a single dose of radiotherapy induced EGFR, ERCC1 and p53 expression in malignant tissues from cervical cancer patients but not in cancer cell lines, highlighting the gap between in vitro and in vivo experimental models. Studies on larger patient cohorts are needed to allow an interpretation that an up regulation of p53, EGFR and ERCC1 may be part of a radioresistance mechanism. (author)

P-Glycoprotein/MDR1 regulates pokemon gene transcription through p53 expression in human breast cancer cells.

Science.gov (United States)

He, Shengnan; Liu, Feng; Xie, Zhenhua; Zu, Xuyu; Xu, Wei; Jiang, Yuyang

2010-08-27

P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy.

Identification of two novel functional p53 responsive elements in the herpes simplex virus-1 genome.

Science.gov (United States)

Hsieh, Jui-Cheng; Kuta, Ryan; Armour, Courtney R; Boehmer, Paul E

2014-07-01

Analysis of the herpes simplex virus-1 (HSV-1) genome reveals two candidate p53 responsive elements (p53RE), located in proximity to the replication origins oriL and oriS, referred to as p53RE-L and p53RE-S, respectively. The sequences of p53RE-L and p53RE-S conform to the p53 consensus site and are present in HSV-1 strains KOS, 17, and F. p53 binds to both elements in vitro and in virus-infected cells. Both p53RE-L and p53RE-S are capable of conferring p53-dependent transcriptional activation onto a heterologous reporter gene. Importantly, expression of the essential immediate early viral transactivator ICP4 and the essential DNA replication protein ICP8, that are adjacent to p53RE-S and p53RE-L, are repressed in a p53-dependent manner. Taken together, this study identifies two novel functional p53RE in the HSV-1 genome and suggests a complex mechanism of viral gene regulation by p53 which may determine progression of the lytic viral replication cycle or the establishment of latency. Copyright © 2014 Elsevier Inc. All rights reserved.

Arecoline-induced growth arrest and p21WAF1 expression are dependent on p53 in rat hepatocytes

International Nuclear Information System (INIS)

Chou, W.-W.; Guh, J.-Y.; Tsai, J.-F.; Hwang, C.-C.; Chen, H.-C.; Huang, J.-S.; Yang, Y.-L.; Hung, W.-C.; Chuang, L.-Y.

2008-01-01

Betel-quid use is associated with the risk of liver cirrhosis and hepatocellular carcinoma and arecoline, the major alkaloid of betel-quid, is hepatotoxic in mice. Therefore, we studied the cytotoxic and genotoxic effects of arecoline in normal rat hepatocytes (Clone-9 cells). Arecoline dose-dependently (0.1-1 mM) decreased cell cycle-dependent proliferation while inducing DNA damage at 24 h. Moreover, arecoline (1 mM)-induced apoptosis and necrosis at 24 h. Arecoline dose-dependently (0.1-0.5 mM) increased transforming growth factor-β (TGF-β) mRNA, gene transcription and bioactivity and neutralizing TGF-β antibody attenuated arecoline (0.5 mM)-inhibited cell proliferation at 24 h. Arecoline (0.5 mM) also increased p21 WAF1 protein expression and p21 WAF1 gene transcription. Moreover, arecoline (0.5 mM) time-dependently (8-24 h) increased p53 serine 15 phosphorylation. Pifithrin-α (p53 inhibitor) and the loss of the two p53-binding elements in the p21 WAF1 gene promoter attenuated arecoline-induced p21 WAF1 gene transcription at 24 h. Pifithrin-α also attenuated arecoline (0.5 mM)-inhibited cell proliferation at 24 h. We concluded that arecoline induces cytotoxicity, DNA damage, G 0 /G 1 cell cycle arrest, TGF-β1, p21 WAF1 and activates p53 in Clone-9 cells. Moreover, arecoline-induced p21 WAF1 is dependent on p53 while arecoline-inhibited growth is dependent on both TGF-β and p53

Activation of SAT1 engages polyamine metabolism with p53-mediated ferroptotic responses.

Science.gov (United States)

Ou, Yang; Wang, Shang-Jui; Li, Dawei; Chu, Bo; Gu, Wei

2016-11-01

Although p53-mediated cell-cycle arrest, senescence, and apoptosis remain critical barriers to cancer development, the emerging role of p53 in cell metabolism, oxidative responses, and ferroptotic cell death has been a topic of great interest. Nevertheless, it is unclear how p53 orchestrates its activities in multiple metabolic pathways into tumor suppressive effects. Here, we identified the SAT1 (spermidine/spermine N 1 -acetyltransferase 1) gene as a transcription target of p53. SAT1 is a rate-limiting enzyme in polyamine catabolism critically involved in the conversion of spermidine and spermine back to putrescine. Surprisingly, we found that activation of SAT1 expression induces lipid peroxidation and sensitizes cells to undergo ferroptosis upon reactive oxygen species (ROS)-induced stress, which also leads to suppression of tumor growth in xenograft tumor models. Notably, SAT1 expression is down-regulated in human tumors, and CRISPR-cas9-mediated knockout of SAT1 expression partially abrogates p53-mediated ferroptosis. Moreover, SAT1 induction is correlated with the expression levels of arachidonate 15-lipoxygenase (ALOX15), and SAT1-induced ferroptosis is significantly abrogated in the presence of PD146176, a specific inhibitor of ALOX15. Thus, our findings uncover a metabolic target of p53 involved in ferroptotic cell death and provide insight into the regulation of polyamine metabolism and ferroptosis-mediated tumor suppression.

Sirtuin inhibition attenuates the production of inflammatory cytokines in lipopolysaccharide-stimulated macrophages

International Nuclear Information System (INIS)

Fernandes, Cláudia A.; Fievez, Laurence; Neyrinck, Audrey M.; Delzenne, Nathalie M.; Bureau, Fabrice; Vanbever, Rita

2012-01-01

Highlights: ► Lipopolysaccharide-stimulated macrophages were treated with cambinol and sirtinol. ► Cambinol and sirtinol decreased lipopolysaccharide-induced cytokines. ► Cambinol decreased NF-κB activity but had no impact on p38 MAPK activation. ► Sirtuins are an interesting target for the treatment of inflammatory diseases. -- Abstract: In several inflammatory conditions such as rheumatoid arthritis or sepsis, the regulatory mechanisms of inflammation are inefficient and the excessive inflammatory response leads to damage to the host. Sirtuins are class III histone deacetylases that modulate the activity of several transcription factors that are implicated in immune responses. In this study, we evaluated the impact of sirtuin inhibition on the activation of lipopolysaccharide (LPS)-stimulated J774 macrophages by assessing the production of inflammatory cytokines. The pharmacologic inhibition of sirtuins decreased the production of tumour necrosis factor-alpha (TNF-α) interleukin 6 (IL-6) and Rantes. The reduction of cytokine production was associated with decreased nuclear factor kappa B (NF-κB) activity and inhibitor kappa B alpha (IκBα) phosphorylation while no impact was observed on the phosphorylation status of p38 mitogen-activated kinase (p38 MAPK). This work shows that sirtuin pharmacologic inhibitors are a promising tool for the treatment of inflammatory conditions.

Baculovirus p35 gene is oppositely regulated by P53 and AP-1 like factors in Spodoptera frugiperda

International Nuclear Information System (INIS)

Mohareer, Krishnaveni; Sahdev, Sudhir; Hasnain, Seyed E.

2011-01-01

Highlights: ► Baculovirus p35 is regulated by both viral and host factors. ► Baculovirus p35 is negatively regulated by SfP53-like factor. ► Baculovirus p35 is positively regulated by SfAP-1-like factor. -- Abstract: Baculovirus p35 belongs to the early class of genes of AcMNPV and requires viral factors like Immediate Early protein-1 for its transcription. To investigate the role of host factors in regulating p35 gene expression, the putative transcription factor binding sites were examined in silico and the role of these factors in influencing the transcription of p35 gene was assessed. We focused our studies on AP-1 and P53-like factors, which are activated under oxidative stress conditions. The AP-1 motif is located at −1401 while P53 motif is at −1912 relative to p35 translation start site. The predicted AP-1 and P53 elements formed specific complexes with Spodoptera frugiperda nuclear extracts. Both AP-1 and P53 motif binding proteins were down regulated as a function of AcMNPV infection in Spodoptera cells. To address the question whether during an oxidative outburst, the p35 transcription is enhanced; we investigated the role of these oxidative stress induced host transcription factors in influencing p35 gene transcription. Reporter assays revealed that AP-1 element enhances the transcription of p35 by a factor of two. Interestingly, P53 element appears to repress the transcription of p35 gene.

Baculovirus p35 gene is oppositely regulated by P53 and AP-1 like factors in Spodoptera frugiperda

Energy Technology Data Exchange (ETDEWEB)

Mohareer, Krishnaveni [Laboratory of Molecular and Cell Biology, Center for DNA Fingerprinting and Diagnostics, Hyderabad 500001 (India); Institute of Life Sciences, University of Hyderabad Campus, Prof. C.R. Rao Road, Gachibowli, Hyderabad 500046 (India); Sahdev, Sudhir [Laboratory of Molecular and Cell Biology, Center for DNA Fingerprinting and Diagnostics, Hyderabad 500001 (India); Ranbaxy Pharmaceuticals, Gurgaon, New Delhi (India); Hasnain, Seyed E., E-mail: seh@bioschool.iitd.ac.in [Institute of Life Sciences, University of Hyderabad Campus, Prof. C.R. Rao Road, Gachibowli, Hyderabad 500046 (India); Kusuma School of Biological Sciences, IIT Delhi, New Delhi 110016 (India); ILBS, Vasant Kunj, New Delhi (India); King Saud University, Riyadh, KSA (Saudi Arabia)

2011-11-04

Highlights: Black-Right-Pointing-Pointer Baculovirus p35 is regulated by both viral and host factors. Black-Right-Pointing-Pointer Baculovirus p35 is negatively regulated by SfP53-like factor. Black-Right-Pointing-Pointer Baculovirus p35 is positively regulated by SfAP-1-like factor. -- Abstract: Baculovirus p35 belongs to the early class of genes of AcMNPV and requires viral factors like Immediate Early protein-1 for its transcription. To investigate the role of host factors in regulating p35 gene expression, the putative transcription factor binding sites were examined in silico and the role of these factors in influencing the transcription of p35 gene was assessed. We focused our studies on AP-1 and P53-like factors, which are activated under oxidative stress conditions. The AP-1 motif is located at -1401 while P53 motif is at -1912 relative to p35 translation start site. The predicted AP-1 and P53 elements formed specific complexes with Spodoptera frugiperda nuclear extracts. Both AP-1 and P53 motif binding proteins were down regulated as a function of AcMNPV infection in Spodoptera cells. To address the question whether during an oxidative outburst, the p35 transcription is enhanced; we investigated the role of these oxidative stress induced host transcription factors in influencing p35 gene transcription. Reporter assays revealed that AP-1 element enhances the transcription of p35 by a factor of two. Interestingly, P53 element appears to repress the transcription of p35 gene.

Expression of Sirtuins in the Retinal Neurons of Mice, Rats, and Humans

Directory of Open Access Journals (Sweden)

Hongdou Luo

2017-11-01

Full Text Available Sirtuins are a class of histone deacetylases (HDACs that have been shown to regulate a range of pathophysiological processes such as cellular aging, inflammation, metabolism, and cell proliferation. There are seven mammalian Sirtuins (SIRT1-7 that play important roles in stress response, aging, and neurodegenerative diseases. However, the location and function of Sirtuins in neurons are not well defined. This study assessed the retinal expression of Sirtuins in mice, rats, and humans and measured the expression of Sirtuins in aged and injured retinas. Expression of all 7 Sirtuins was confirmed by Western blot and Real-Time PCR analysis in all three species. SIRT1 is highly expressed in mouse, rat, and human retinas, whereas SIRT2-7 expression was relatively lower in human retinas. Immunofluorescence was also used to examine the expression and localization of Sirtuins in rat retinal neurons. Importantly, we demonstrate a marked reduction of SIRT1 expression in aged retinal neurons as well as retinas injured by acute ischemia-reperfusion. On the other hand, none of the other Sirtuins exhibit any significant age-related changes in expression except for SIRT5, which was significantly higher in the retinas of adults compared to both young and aged rats. Our work presents the first composite analysis of Sirtuins in the retinal neurons of mice, rats, and humans, and suggests that increasing the expression and activity of SIRT1 may be beneficial for the treatment of glaucoma and other age-related eye dysfunction.

Che-1 gene silencing induces osteosarcoma cell apoptosis by inhibiting mutant p53 expression

Energy Technology Data Exchange (ETDEWEB)

Liu, Ming; Wang, Dan, E-mail: danwangwdd@163.com; Li, Ning

2016-04-22

The transcriptional cofactor Che-1 is an RNA polymerase II (Pol II) which is involved in tumorigenesis, such as breast cancer and multiple myeloma. Che-1 can also regulate mutant p53 expression, which plays roles in many types of cancer. In this study, we aimed to investigate the effects and specific mechanism of Che-1 in the regulation of osteosarcoma (OS) cell growth. We found that Che-1 is highly expressed in several kinds of OS cells compared with osteoblast hFOB1.19 cells. MTT and flow cytometry assays showed that Che-1 depletion by siRNA markedly suppressed MG-63 and U2OS cell proliferation and promoted apoptosis. The chromatin immunoprecipitation (ChIP) assay verified the presence of Che-1 on the p53 promoter in MG-63 and U2OS cells carrying mutant p53. Further studies showed that Che-1 depletion inhibited mutant p53 expression. Notably, our study showed that the loss of Che-1 inhibits proliferation and promotes apoptosis in MG-63 cells by decreasing the level of mutant p53. Therefore, these findings open the possibility that silencing of Che-1 will have therapeutic benefit in OS. - Highlights: • Che-1 is highly expressed in several kinds of OS cells. • Che-1 depletion suppressed MG-63 and U2OS cell growth. • Che-1 is existed in the p53 promoter in MG-63 and U2OS cells. • Che-1 depletion inhibited mutant p53 expression. • Che-1 depletion inhibits cell growth by decreasing the level of mutant p53.

P-Glycoprotein/MDR1 Regulates Pokemon Gene Transcription Through p53 Expression in Human Breast Cancer Cells

Directory of Open Access Journals (Sweden)

Wei Xu

2010-08-01

Full Text Available P-glycoprotein (Pgp, encoded by the multidrug resistance 1 (MDR1 gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy.

Forkhead-Box-P3 Gene Transfer in Human CD4+ T Conventional Cells for the Generation of Stable and Efficient Regulatory T Cells, Suitable for Immune Modulatory Therapy

Directory of Open Access Journals (Sweden)

Laura Passerini

2017-10-01

Full Text Available The development of novel approaches to control immune responses to self- and allogenic tissues/organs represents an ambitious goal for the management of autoimmune diseases and in transplantation. Regulatory T cells (Tregs are recognized as key players in the maintenance of peripheral tolerance in physiological and pathological conditions, and Treg-based cell therapies to restore tolerance in T cell-mediated disorders have been designed. However, several hurdles, including insufficient number of Tregs, their stability, and their antigen specificity, have challenged Tregs clinical applicability. In the past decade, the ability to engineer T cells has proven a powerful tool to redirect specificity and function of different cell types for specific therapeutic purposes. By using lentivirus-mediated gene transfer of the thymic-derived Treg transcription factor forkhead-box-P3 (FOXP3 in conventional CD4+ T cells, we converted effector T cells into Treg-like cells, endowed with potent in vitro and in vivo suppressive activity. The resulting CD4FOXP3 T-cell population displays stable phenotype and suppressive function. We showed that this strategy restores Treg function in T lymphocytes from patients carrying mutations in FOXP3 [immune-dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX], in whom CD4FOXP3 T cell could be used as therapeutics to control autoimmunity. Here, we will discuss the potential advantages of using CD4FOXP3 T cells for in vivo application in inflammatory diseases, where tissue inflammation may undermine the function of natural Tregs. These findings pave the way for the use of engineered Tregs not only in IPEX syndrome but also in autoimmune disorders of different origin and in the context of stem cell and organ transplantation.

The Forkhead Transcription Factor FOXP2 Is Required for Regulation of p21WAF1/CIP1 in 143B Osteosarcoma Cell Growth Arrest.

Science.gov (United States)

Gascoyne, Duncan M; Spearman, Hayley; Lyne, Linden; Puliyadi, Rathi; Perez-Alcantara, Marta; Coulton, Les; Fisher, Simon E; Croucher, Peter I; Banham, Alison H

2015-01-01

Mutations of the forkhead transcription factor FOXP2 gene have been implicated in inherited speech-and-language disorders, and specific Foxp2 expression patterns in neuronal populations and neuronal phenotypes arising from Foxp2 disruption have been described. However, molecular functions of FOXP2 are not completely understood. Here we report a requirement for FOXP2 in growth arrest of the osteosarcoma cell line 143B. We observed endogenous expression of this transcription factor both transiently in normally developing murine osteoblasts and constitutively in human SAOS-2 osteosarcoma cells blocked in early osteoblast development. Critically, we demonstrate that in 143B osteosarcoma cells with minimal endogenous expression, FOXP2 induced by growth arrest is required for up-regulation of p21WAF1/CIP1. Upon growth factor withdrawal, FOXP2 induction occurs rapidly and precedes p21WAF1/CIP1 activation. Additionally, FOXP2 expression could be induced by MAPK pathway inhibition in growth-arrested 143B cells, but not in traditional cell line models of osteoblast differentiation (MG-63, C2C12, MC3T3-E1). Our data are consistent with a model in which transient upregulation of Foxp2 in pre-osteoblast mesenchymal cells regulates a p21-dependent growth arrest checkpoint, which may have implications for normal mesenchymal and osteosarcoma biology.

p53 functional impairment and high p21waf1/cip1 expression in human T-cell lymphotropic/leukemia virus type I-transformed T cells.

Science.gov (United States)

Cereseto, A; Diella, F; Mulloy, J C; Cara, A; Michieli, P; Grassmann, R; Franchini, G; Klotman, M E

1996-09-01

Human T-cell lymphotropic/leukemia virus type I (HTLV-I) is associated with T-cell transformation both in vivo and in vitro. Although some of the mechanisms responsible for transformation remain unknown, increasing evidence supports a direct role of viral as well as dysregulated cellular proteins in transformation. We investigated the potential role of the tumor suppressor gene p53 and of the p53-regulated gene, p21waf1/cip1 (wild-type p53 activated fragment 1/cycling dependent kinases [cdks] interacting protein 1), in HTLV-I-infected T cells. We have found that the majority of HTLV-I-infected T cells have the wild-type p53 gene. However, its function in HTLV-I-transformed cells appears to be impaired, as shown by the lack of appropriate p53-mediated responses to ionizing radiation (IR). Interestingly, the expression of the p53 inducible gene, p21waf1/cip1, is elevated at the messenger ribonucleic acid and protein levels in all HTLV-I-infected T-cell lines examined as well as in Taxl-1, a human T-cell line stably expressing Tax. Additionally, Tax induces upregulation of a p21waf1/cip1 promoter-driven luciferase gene in p53 null cells, and increases p21waf1/cip1 expression in Jurkat T cells. These findings suggest that the Tax protein is at least partially responsible for the p53-independent expression of p21waf1/cip1 in HTLV-I-infected cells. Dysregulation of p53 and p21waf1/cip1 proteins regulating cell-cycle progression, may represent an important step in HTLV-I-induced T-cell transformation.

hSSB1 regulates both the stability and the transcriptional activity of p53

OpenAIRE

Xu, Shuangbing; Wu, Yuanzhong; Chen, Qiong; Cao, Jingying; Hu, Kaishun; Tang, Jianjun; Sang, Yi; Lai, Fenju; Wang, Li; Zhang, Ruhua; Li, Sheng-Ping; Zeng, Yi-Xin; Yin, Yuxin; Kang, Tiebang

2012-01-01

The tumor suppressor p53 is essential for several cellular processes that are involved in the response to diverse genotoxic stress, including cell cycle arrest, DNA repair, apoptosis and senescence. Studies of the regulation of p53 have mostly focused on its stability and transactivation; however, new regulatory molecules for p53 have also been frequently identified. Here, we report that human ssDNA binding protein SSB1 (hSSB1), a novel DNA damage-associated protein, can interact with p53 and...

Identification of Transmembrane Protease Serine 2 and Forkhead Box A1 As the Potential Bisphenol A Responsive Genes in the Neonatal Male Rat Brain

Directory of Open Access Journals (Sweden)

Takayoshi Ubuka

2018-03-01

Full Text Available Perinatal exposure of Bisphenol A (BPA to rodents modifies their behavior in later life. To understand how BPA modifies their neurodevelopmental process, we first searched for BPA responsive genes from androgen and estrogen receptor signaling target genes by polymerase chain reaction array in the neonatal male rat brain. We used a transgenic strain of Wistar rats carrying enhanced green fluorescent protein tagged to gonadotropin-inhibitory hormone (GnIH promoter to investigate the possible interaction of BPA responsive genes and GnIH neurons. We found upregulation of transmembrane protease serine 2 (Tmprss2, an androgen receptor signaling target gene, and downregulation of Forkhead box A1 (Foxa1, an ER signaling target gene, in the medial amygdala of male rats that were subcutaneously administered with BPA from day 1 to 3. Tmprss2-immunoreactive (ir cells were distributed in the olfactory bulb, cerebral cortex, hippocampus, amygdala, and hypothalamus in 3 days old but not in 1-month-old male rats. Density of Tmprss2-ir cells in the medial amygdala was increased by daily administration of BPA from day 1 to 3. Tmprss2 immunoreactivity was observed in 26.5% of GnIH neurons clustered from the ventral region of the ventromedial hypothalamic nucleus to the dorsal region of the arcuate nucleus of 3-day-old male rat hypothalamus. However, Tmprss2 mRNA expression significantly decreased in the amygdala and hypothalamus of 1-month-old male rats. Foxa1 mRNA expression was higher in the hypothalamus than the amygdala in 3 days old male rats. Intense Foxa1-ir cells were only found in the peduncular part of lateral hypothalamus of 3-day-old male rats. Density of Foxa1-ir cells in the hypothalamus was decreased by daily administration of BPA from day 1 to 3. Foxa1 mRNA expression in the hypothalamus also significantly decreased at 1 month. These results suggest that BPA disturbs the neurodevelopmental process and behavior of rats later in their life by

Sirtuin 1 stimulates the proliferation and the expression of glycolysis genes in pancreatic neoplastic lesions.

Science.gov (United States)

Pinho, Andreia V; Mawson, Amanda; Gill, Anthony; Arshi, Mehreen; Warmerdam, Max; Giry-Laterriere, Marc; Eling, Nils; Lie, Triyana; Kuster, Evelyne; Camargo, Simone; Biankin, Andrew V; Wu, Jianmin; Rooman, Ilse

2016-11-15

Metabolic reprogramming is a feature of neoplasia and tumor growth. Sirtuin 1 (SIRT1) is a lysine deacetylase of multiple targets including metabolic regulators such as p53. SIRT1 regulates metaplasia in the pancreas. Nevertheless, it is unclear if SIRT1 affects the development of neoplastic lesions and whether metabolic gene expression is altered.To assess neoplastic lesion development, mice with a pancreas-specific loss of Sirt1 (Pdx1-Cre;Sirt1-lox) were bred into a KrasG12D mutant background (KC) that predisposes to the development of pancreatic intra-epithelial neoplasia (PanIN) and ductal adenocarcinoma (PDAC). Similar grade PanIN lesions developed in KC and KC;Sirt1-lox mice but specifically early mucinous PanINs occupied 40% less area in the KC;Sirt1-lox line, attributed to reduced proliferation. This was accompanied by reduced expression of proteins in the glycolysis pathway, such as GLUT1 and GAPDH.The stimulatory effect of SIRT1 on proliferation and glycolysis gene expression was confirmed in a human PDAC cell line. In resected PDAC samples, higher proliferation and expression of glycolysis genes correlated with poor patient survival. SIRT1 expression per se was not prognostic but low expression of Cell Cycle and Apoptosis Regulator 2 (CCAR2), a reported SIRT1 inhibitor, corresponded to poor patient survival.These findings open perspectives for novel targeted therapies in pancreatic cancer.

Sirtuin 1 stimulates the proliferation and the expression of glycolysis genes in pancreatic neoplastic lesions

Science.gov (United States)

Pinho, Andreia V.; Mawson, Amanda; Gill, Anthony; Arshi, Mehreen; Warmerdam, Max; Giry-Laterriere, Marc; Eling, Nils; Lie, Triyana; Kuster, Evelyne; Camargo, Simone; Biankin, Andrew V.; Wu, Jianmin; Rooman, Ilse

2016-01-01

Metabolic reprogramming is a feature of neoplasia and tumor growth. Sirtuin 1 (SIRT1) is a lysine deacetylase of multiple targets including metabolic regulators such as p53. SIRT1 regulates metaplasia in the pancreas. Nevertheless, it is unclear if SIRT1 affects the development of neoplastic lesions and whether metabolic gene expression is altered. To assess neoplastic lesion development, mice with a pancreas-specific loss of Sirt1 (Pdx1-Cre;Sirt1-lox) were bred into a KrasG12D mutant background (KC) that predisposes to the development of pancreatic intra-epithelial neoplasia (PanIN) and ductal adenocarcinoma (PDAC). Similar grade PanIN lesions developed in KC and KC;Sirt1-lox mice but specifically early mucinous PanINs occupied 40% less area in the KC;Sirt1-lox line, attributed to reduced proliferation. This was accompanied by reduced expression of proteins in the glycolysis pathway, such as GLUT1 and GAPDH. The stimulatory effect of SIRT1 on proliferation and glycolysis gene expression was confirmed in a human PDAC cell line. In resected PDAC samples, higher proliferation and expression of glycolysis genes correlated with poor patient survival. SIRT1 expression per se was not prognostic but low expression of Cell Cycle and Apoptosis Regulator 2 (CCAR2), a reported SIRT1 inhibitor, corresponded to poor patient survival. These findings open perspectives for novel targeted therapies in pancreatic cancer. PMID:27494892

Sirtuin inhibition attenuates the production of inflammatory cytokines in lipopolysaccharide-stimulated macrophages

Energy Technology Data Exchange (ETDEWEB)

Fernandes, Claudia A. [Universite catholique de Louvain, Louvain Drug Research Institute (LDRI), Pharmaceutics and Drug Delivery Research Group, Brussels B-1200 (Belgium); Fievez, Laurence [University of Liege, GIGA-Research, Laboratory of Cellular and Molecular Immunology, Liege B-4000 (Belgium); Neyrinck, Audrey M.; Delzenne, Nathalie M. [Universite catholique de Louvain, LDRI, Metabolism and Nutrition Research Group, Brussels B-1200 (Belgium); Bureau, Fabrice [University of Liege, GIGA-Research, Laboratory of Cellular and Molecular Immunology, Liege B-4000 (Belgium); Vanbever, Rita, E-mail: rita.vanbever@uclouvain.be [Universite catholique de Louvain, Louvain Drug Research Institute (LDRI), Pharmaceutics and Drug Delivery Research Group, Brussels B-1200 (Belgium)

2012-04-20

Highlights: Black-Right-Pointing-Pointer Lipopolysaccharide-stimulated macrophages were treated with cambinol and sirtinol. Black-Right-Pointing-Pointer Cambinol and sirtinol decreased lipopolysaccharide-induced cytokines. Black-Right-Pointing-Pointer Cambinol decreased NF-{kappa}B activity but had no impact on p38 MAPK activation. Black-Right-Pointing-Pointer Sirtuins are an interesting target for the treatment of inflammatory diseases. -- Abstract: In several inflammatory conditions such as rheumatoid arthritis or sepsis, the regulatory mechanisms of inflammation are inefficient and the excessive inflammatory response leads to damage to the host. Sirtuins are class III histone deacetylases that modulate the activity of several transcription factors that are implicated in immune responses. In this study, we evaluated the impact of sirtuin inhibition on the activation of lipopolysaccharide (LPS)-stimulated J774 macrophages by assessing the production of inflammatory cytokines. The pharmacologic inhibition of sirtuins decreased the production of tumour necrosis factor-alpha (TNF-{alpha}) interleukin 6 (IL-6) and Rantes. The reduction of cytokine production was associated with decreased nuclear factor kappa B (NF-{kappa}B) activity and inhibitor kappa B alpha (I{kappa}B{alpha}) phosphorylation while no impact was observed on the phosphorylation status of p38 mitogen-activated kinase (p38 MAPK). This work shows that sirtuin pharmacologic inhibitors are a promising tool for the treatment of inflammatory conditions.

Nuclear inclusion bodies of mutant and wild-type p53 in cancer: a hallmark of p53 inactivation and proteostasis remodelling by p53 aggregation.

Science.gov (United States)

De Smet, Frederik; Saiz Rubio, Mirian; Hompes, Daphne; Naus, Evelyne; De Baets, Greet; Langenberg, Tobias; Hipp, Mark S; Houben, Bert; Claes, Filip; Charbonneau, Sarah; Delgado Blanco, Javier; Plaisance, Stephane; Ramkissoon, Shakti; Ramkissoon, Lori; Simons, Colinda; van den Brandt, Piet; Weijenberg, Matty; Van England, Manon; Lambrechts, Sandrina; Amant, Frederic; D'Hoore, André; Ligon, Keith L; Sagaert, Xavier; Schymkowitz, Joost; Rousseau, Frederic

2017-05-01

Although p53 protein aggregates have been observed in cancer cell lines and tumour tissue, their impact in cancer remains largely unknown. Here, we extensively screened for p53 aggregation phenotypes in tumour biopsies, and identified nuclear inclusion bodies (nIBs) of transcriptionally inactive mutant or wild-type p53 as the most frequent aggregation-like phenotype across six different cancer types. p53-positive nIBs co-stained with nuclear aggregation markers, and shared molecular hallmarks of nIBs commonly found in neurodegenerative disorders. In cell culture, tumour-associated stress was a strong inducer of p53 aggregation and nIB formation. This was most prominent for mutant p53, but could also be observed in wild-type p53 cell lines, for which nIB formation correlated with the loss of p53's transcriptional activity. Importantly, protein aggregation also fuelled the dysregulation of the proteostasis network in the tumour cell by inducing a hyperactivated, oncogenic heat-shock response, to which tumours are commonly addicted, and by overloading the proteasomal degradation system, an observation that was most pronounced for structurally destabilized mutant p53. Patients showing tumours with p53-positive nIBs suffered from a poor clinical outcome, similar to those with loss of p53 expression, and tumour biopsies showed a differential proteostatic expression profile associated with p53-positive nIBs. p53-positive nIBs therefore highlight a malignant state of the tumour that results from the interplay between (1) the functional inactivation of p53 through mutation and/or aggregation, and (2) microenvironmental stress, a combination that catalyses proteostatic dysregulation. This study highlights several unexpected clinical, biological and therapeutically unexplored parallels between cancer and neurodegeneration. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2016 Pathological Society of Great

E2F-1-Induced p53-independent apoptosis in transgenic mice

DEFF Research Database (Denmark)

Holmberg, Christian Henrik; Helin, K.; Sehested, M.

1998-01-01

The E2F transcription factors are key targets for the retinoblastoma protein, pRB. By inactivation of E2Fs, pRB prevents progression to the S phase. To test proliferative functions of E2F, we generated transgenic mice expressing human E2F-1 and/or human DP-1. When the hydroxymethyl glutaryl...... involving increased apoptosis in the germinal epithelium. This effect was potentiated by simultaneous overexpression of DP-1. Testicular atrophy as a result of overexpression of E2F-1 and DP-1 is independent of functional p53, since p53-nullizygous transgenic mice overexpressing E2F-1 and DP-1 also suffered...

Heat shock factor-1 modulates p53 activity in the transcriptional response to DNA damage

Science.gov (United States)

Logan, Ian R.; McNeill, Hesta V.; Cook, Susan; Lu, Xiaohong; Meek, David W.; Fuller-Pace, Frances V.; Lunec, John; Robson, Craig N.

2009-01-01

Here we define an important role for heat shock factor 1 (HSF1) in the cellular response to genotoxic agents. We demonstrate for the first time that HSF1 can complex with nuclear p53 and that both proteins are co-operatively recruited to p53-responsive genes such as p21. Analysis of natural and synthetic cis elements demonstrates that HSF1 can enhance p53-mediated transcription, whilst depletion of HSF1 reduces the expression of p53-responsive transcripts. We find that HSF1 is required for optimal p21 expression and p53-mediated cell-cycle arrest in response to genotoxins while loss of HSF1 attenuates apoptosis in response to these agents. To explain these novel properties of HSF1 we show that HSF1 can complex with DNA damage kinases ATR and Chk1 to effect p53 phosphorylation in response to DNA damage. Our data reveal HSF1 as a key transcriptional regulator in response to genotoxic compounds widely used in the clinical setting, and suggest that HSF1 will contribute to the efficacy of these agents. PMID:19295133

Forkhead box C2 promoter variant c.-512C>T is associated with increased susceptibility to chronic venous diseases.

Directory of Open Access Journals (Sweden)

Sumi Surendran

Full Text Available Chronic venous disease (CVD is one of the most prevalent yet underrated disorders worldwide. High heritability estimates of CVD indicate prominent genetic components in its etiology and pathology. Mutations in human forkhead box C2 (FoxC2 gene are strongly associated with valve failure in saphenous and deep veins of lower extremities. We explored the association of genetic variants of FoxC2 as well as FoxC2 mRNA and protein expression levels with CVD of lower limbs. We systematically sequenced the single coding exon, 5' and 3' flanking regions of FoxC2 gene in 754 study subjects which includes 382 patients with CVD and 372 healthy subjects. Four novel and three reported polymorphisms were identified in our cohort. Three variants in 5' flanking region and one in 3' flanking region of FoxC2 gene were significantly associated with CVD risk. FoxC2 mRNA in vein tissues from 22 patients was 4±1.42 fold increased compared to saphenous veins from 20 normal subjects (pT (rs34221221: C>T variant which is located in the FoxC2 putative promoter region was further analyzed. Functional analysis of c.-512C>T revealed increased mRNA and protein expression in patients with homozygous TT genotype compared to heterozygous CT and wild CC genotypes. Luciferase assay indicated higher transcriptional activity of mutant compared to wild genotype of this variant. These findings suggested that c.-512C>T variant of FoxC2 was strongly associated with susceptibility to CVD and also that this variant resulted in FoxC2 overexpression. To obtain a mechanistic insight into the role of upregulated FoxC2 in varicosities, we overexpressed FoxC2 in venous endothelial cells and observed elevated expression of arterial markers Dll4 and Hey2 and downregulation of venous marker COUP-TFII. Our study indicates altered FoxC2-Notch signaling in saphenous vein wall remodeling in patients with varicose veins.

Resveratrol attenuates CoCl2-induced cochlear hair cell damage through upregulation of Sirtuin1 and NF-κB deacetylation.

Directory of Open Access Journals (Sweden)

Ping Wang

Full Text Available The goals of this study were to investigate the effects of hypoxia on cochlear hair cell damage, and to explore the role of sirtuin1 in hypoxia-induced hair cell damage. Cochlear organotypic cultures from postnatal day 4 rats were used in this study. Hypoxia was induced by treating cochlear explants with CoCl2. Cochlear cultures were treated with CoCl2 alone or in combination with the sirtuin1 activator resveratrol and the sirtuin1 inhibitor sirtinol. Hair cell damage was identified by phalloidin staining and imaged using scanning electron microscopy. RT-PCR and Western blot analyses were used to detect the expression of sirtuin1 and acetylated nuclear factor-κB (NF-κB. Low concentrations of CoCl2 (100-200 μM did not cause an obvious change in the number and morphology of hair cells, whereas higher concentrations of CoCl2 (300-400 μM induced swelling of hair cells, accompanied by cell loss. Increased sirtuin1 expression was induced by CoCl2 at 100 to 200 μM, but not at 400 μM. NF-κB acetylation was significantly increased in explants treated with 400 μM CoCl2. Pretreatment with resveratrol prevented CoCl2-induced hair cell loss and acetylation of NF-κB. The protective effect of resveratrol was significantly reduced by sirtinol. CoCl2 induces hair cell damage in organotypic cochleae cultures. Resveratrol attenuates CoCl2-induced cochlear hair cell damage possibly via activation of sirtuin1, which deacetylates NF-κB.

INGN 201: Ad-p53, Ad5CMV-p53, Adenoviral p53, INGN 101, p53 gene therapy--Introgen, RPR/INGN 201.

Science.gov (United States)

2003-01-01

monotherapy or in combination with one or more chemotherapeutic drugs, radiation therapies, or other agents that have a damaging effect on the DNA or survival of (i.e. 2-methoxyestradiol, patent No. 6,410,029) cancer cells. In July 2002, the US Patent and Trademark Office issued to The Board of Regents of The University of Texas System US patent No. 6,410,010. The patent broadly covers all adenoviral p53 compositions (including ADVEXIN), therapeutic and otherwise, that express adequate p53 in amounts sufficient to suppress the growth of or kill cancer cells in patients. The patent also covers adenoviral p53 that incorporates a specific type of promoter that helps cells to express the p53 tumour suppressor gene. Introgen is the exclusive licensee of this composition of matter patent covering ADVEXIN. In December 2002, Aventis Pharmaceuticals was issued US patent No. 6,262,032 B1 entitled "Method of Destroying Hyperproliferative Cells by Combining p53 and Taxoid Treatment". Introgen has an exclusive license to this patent and is using this type of combination therapy in its breast cancer trial. Introgen expects to realise $US 2.5-3 million from sales of INGN 201.

CK1α ablation in keratinocytes induces p53-dependent, sunburn-protective skin hyperpigmentation.

Science.gov (United States)

Chang, Chung-Hsing; Kuo, Che-Jung; Ito, Takamichi; Su, Yu-Ya; Jiang, Si-Tse; Chiu, Min-Hsi; Lin, Yi-Hsiung; Nist, Andrea; Mernberger, Marco; Stiewe, Thorsten; Ito, Shosuke; Wakamatsu, Kazumasa; Hsueh, Yi-An; Shieh, Sheau-Yann; Snir-Alkalay, Irit; Ben-Neriah, Yinon

2017-09-19

Casein kinase 1α (CK1α), a component of the β-catenin destruction complex, is a critical regulator of Wnt signaling; its ablation induces both Wnt and p53 activation. To characterize the role of CK1α (encoded by Csnk1a1 ) in skin physiology, we crossed mice harboring floxed Csnk1a1 with mice expressing K14-Cre-ER T2 to generate mice in which tamoxifen induces the deletion of Csnk1a1 exclusively in keratinocytes [single-knockout (SKO) mice]. As expected, CK1α loss was accompanied by β-catenin and p53 stabilization, with the preferential induction of p53 target genes, but phenotypically most striking was hyperpigmentation of the skin, importantly without tumorigenesis, for at least 9 mo after Csnk1a1 ablation. The number of epidermal melanocytes and eumelanin levels were dramatically increased in SKO mice. To clarify the putative role of p53 in epidermal hyperpigmentation, we established K14-Cre-ER T2 CK1α/p53 double-knockout (DKO) mice and found that coablation failed to induce epidermal hyperpigmentation, demonstrating that it was p53-dependent. Transcriptome analysis of the epidermis revealed p53-dependent up-regulation of Kit ligand (KitL). SKO mice treated with ACK2 (a Kit-neutralizing antibody) or imatinib (a Kit inhibitor) abrogated the CK1α ablation-induced hyperpigmentation, demonstrating that it requires the KitL/Kit pathway. Pro-opiomelanocortin (POMC), a precursor of α-melanocyte-stimulating hormone (α-MSH), was not activated in the CK1α ablation-induced hyperpigmentation, which is in contrast to the mechanism of p53-dependent UV tanning. Nevertheless, acute sunburn effects were successfully prevented in the hyperpigmented skin of SKO mice. CK1α inhibition induces skin-protective eumelanin but no carcinogenic pheomelanin and may therefore constitute an effective strategy for safely increasing eumelanin via UV-independent pathways, protecting against acute sunburn.

Apaf-1 is a transcriptional target for E2F and p53

DEFF Research Database (Denmark)

Moroni, M C; Hickman, E S; Lazzerini Denchi, E

2001-01-01

between the deregulation of the pRB pathway and apoptosis. Furthermore, because the pRB pathway is functionally inactivated in most cancers, the identification of Apaf-1 as a transcriptional target for E2F might explain the increased sensitivity of tumour cells to chemotherapy. We also show that......, independently of the pRB pathway, Apaf-1 is a direct transcriptional target of p53, suggesting that p53 might sensitize cells to apoptosis by increasing Apaf-1 levels....

Loss of p53 promotes anaplasia and local invasion in ret/PTC1-induced thyroid carcinomas.

Science.gov (United States)

La Perle, K M; Jhiang, S M; Capen, C C

2000-08-01

Papillary thyroid carcinomas in humans are associated with the ret/PTC oncogene and, following loss of p53 function, may progress to anaplastic carcinomas. Mice with thyroid-targeted expression of ret/PTC1 developed papillary thyroid carcinomas that were minimally invasive and did not metastasize. These mice were crossed with p53-/- mice to investigate whether loss of p53 would promote anaplasia and metastasis of ret/PTC1-induced thyroid tumors. The majority of p53-/- mice died or were euthanized by 17 weeks of age due to the development of thymic lymphomas, soft tissue sarcomas, and testicular teratomas. All ret/PTC1 mice developed thyroid carcinomas, but tumors in p53-/- mice were more anaplastic, larger in diameter, more invasive, and had a higher mitotic index than tumors in p53+/+ and p53+/- mice. Thyroid tumors did not metastasize in any of the experimental p53+/+ and p53+/- mice anaplasia and invasiveness of thyroid carcinomas.

Gain-of-function mutant p53 activates small GTPase Rac1 through SUMOylation to promote tumor progression.

Science.gov (United States)

Yue, Xuetian; Zhang, Cen; Zhao, Yuhan; Liu, Juan; Lin, Alan W; Tan, Victor M; Drake, Justin M; Liu, Lianxin; Boateng, Michael N; Li, Jun; Feng, Zhaohui; Hu, Wenwei

2017-08-15

Tumor suppressor p53 is frequently mutated in human cancer. Mutant p53 often promotes tumor progression through gain-of-function (GOF) mechanisms. However, the mechanisms underlying mutant p53 GOF are not well understood. In this study, we found that mutant p53 activates small GTPase Rac1 as a critical mechanism for mutant p53 GOF to promote tumor progression. Mechanistically, mutant p53 interacts with Rac1 and inhibits its interaction with SUMO-specific protease 1 (SENP1), which in turn inhibits SENP1-mediated de-SUMOylation of Rac1 to activate Rac1. Targeting Rac1 signaling by RNAi, expression of the dominant-negative Rac1 (Rac1 DN), or the specific Rac1 inhibitor NSC23766 greatly inhibits mutant p53 GOF in promoting tumor growth and metastasis. Furthermore, mutant p53 expression is associated with enhanced Rac1 activity in clinical tumor samples. These results uncover a new mechanism for Rac1 activation in tumors and, most importantly, reveal that activation of Rac1 is an unidentified and critical mechanism for mutant p53 GOF in tumorigenesis, which could be targeted for therapy in tumors containing mutant p53. © 2017 Yue et al.; Published by Cold Spring Harbor Laboratory Press.

Inability of p53-reactivating compounds Nutlin-3 and RITA to overcome p53 resistance in tumor cells deficient in p53Ser46 phosphorylation.

Science.gov (United States)

Ma, Teng; Yamada, Shumpei; Ichwan, Solachuddin J A; Iseki, Sachiko; Ohtani, Kiyoshi; Otsu, Megumi; Ikeda, Masa-Aki

2012-01-20

The p53 tumor suppressor protein plays key roles in protecting cells from tumorigenesis. Phosphorylation of p53 at Ser46 (p53Ser46) is considered to be a crucial modification regulating p53-mediated apoptosis. Because the activity of p53 is impaired in most human cancers, restoration of wild-type p53 (wt-p53) function by its gene transfer or by p53-reactivating small molecules has been extensively investigated. The p53-reactivating compounds Nutlin-3 and RITA activate p53 in the absence of genotoxic stress by antagonizing the action of its negative regulator Mdm2. Although controversial, Nutlin-3 was shown to induce p53-mediated apoptosis in a manner independent of p53 phosphorylation. Recently, RITA was shown to induce apoptosis by promoting p53Ser46 phosphorylation. Here we examined whether Nutlin-3 or RITA can overcome resistance to p53-mediated apoptosis in p53-resistant tumor cell lines lacking the ability to phosphorylate p53Ser46. We show that Nutlin-3 did not rescue the apoptotic defect of a Ser46 phosphorylation-defective p53 mutant in p53-sensitive tumor cells, and that RITA neither restored p53Ser46 phosphorylation nor induced apoptosis in p53Ser46 phosphorylation-deficient cells retaining wt-p53. Furthermore, treatment with Nutlin-3 or RITA together with adenoviral p53 gene transfer also failed to induce apoptosis in p53Ser46 phosphorylation-deficient cells either expressing or lacking wt-p53. These results indicate that neither Nutlin-3 nor RITA in able to induce p53-mediated apoptosis in the absence of p53Ser46 phosphorylation. Thus, the dysregulation of this phosphorylation in tumor cells may be a critical factor that limits the efficacy of these p53-based cancer therapies. Copyright © 2011 Elsevier Inc. All rights reserved.

Fluoxetine protects against IL-1β-induced neuronal apoptosis via downregulation of p53.

Science.gov (United States)

Shan, Han; Bian, Yaqi; Shu, Zhaoma; Zhang, Linxia; Zhu, Jialei; Ding, Jianhua; Lu, Ming; Xiao, Ming; Hu, Gang

2016-08-01

Fluoxetine, a selective serotonin reuptake inhibitor, exerts neuroprotective effects in a variety of neurological diseases including stroke, but the underlying mechanism remains obscure. In the present study, we addressed the molecular events in fluoxetine against ischemia/reperfusion-induced acute neuronal injury and inflammation-induced neuronal apoptosis. We showed that treatment of fluoxetine (40 mg/kg, i.p.) with twice injections at 1 h and 12 h after transient middle cerebral artery occlusion (tMCAO) respectively alleviated neurological deficits and neuronal apoptosis in a mouse ischemic stroke model, accompanied by inhibiting interleukin-1β (IL-1β), Bax and p53 expression and upregulating anti-apoptotic protein Bcl-2 level. We next mimicked neuroinflammation in ischemic stroke with IL-1β in primary cultured cortical neurons and found that pretreatment with fluoxetine (1 μM) prevented IL-1β-induced neuronal apoptosis and upregulation of p53 expression. Furthermore, we demonstrated that p53 overexpression in N2a cell line abolished the anti-apoptotic effect of fluoxetine, indicating that p53 downregulation is required for the protective role of fluoxetine in IL-1β-induced neuronal apoptosis. Fluoxetine downregulating p53 expression could be mimicked by SB203580, a specific inhibitor of p38, but blocked by anisomycin, a p38 activator. Collectively, our findings have revealed that fluoxetine protects against IL-1β-induced neuronal apoptosis via p38-p53 dependent pathway, which give us an insight into the potential of fluoxetine in terms of opening up novel therapeutic avenues for neurological diseases including stroke. Copyright © 2016 Elsevier Ltd. All rights reserved.

p53 inhibits autophagy by interacting with the human ortholog of yeast Atg17, RB1CC1/FIP200.

Science.gov (United States)

Morselli, Eugenia; Shen, Shensi; Ruckenstuhl, Christoph; Bauer, Maria Anna; Mariño, Guillermo; Galluzzi, Lorenzo; Criollo, Alfredo; Michaud, Mickael; Maiuri, Maria Chiara; Chano, Tokuhiro; Madeo, Frank; Kroemer, Guido

2011-08-15

The tumor suppressor protein p53 tonically suppresses autophagy when it is present in the cytoplasm. This effect is phylogenetically conserved from mammals to nematodes, and human p53 can inhibit autophagy in yeast, as we show here. Bioinformatic investigations of the p53 interactome in relationship to the autophagy-relevant protein network underscored the possible relevance of a direct molecular interaction between p53 and the mammalian ortholog of the essential yeast autophagy protein Atg17, namely RB1-inducible coiled-coil protein 1 (RB1CC1), also called FAK family kinase-interacting protein of 200 KDa (FIP200). Mutational analyses revealed that a single point mutation in p53 (K382R) abolished its capacity to inhibit autophagy upon transfection into p53-deficient human colon cancer or yeast cells. In conditions in which wild-type p53 co-immunoprecipitated with RB1CC1/FIP200, p53 (K382R) failed to do so, underscoring the importance of the physical interaction between these proteins for the control of autophagy. In conclusion, p53 regulates autophagy through a direct molecular interaction with RB1CC1/FIP200, a protein that is essential for the very apical step of autophagy initiation.

Low p53 Binding Protein 1 (53BP1) Expression Is Associated With Increased Local Recurrence in Breast Cancer Patients Treated With Breast-Conserving Surgery and Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Neboori, Hanmanth J.R. [Department of Radiation Oncology, Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); Haffty, Bruce G., E-mail: hafftybg@umdnj.edu [Department of Radiation Oncology, The Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); Wu Hao [Department of Radiation Oncology, Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); Yang Qifeng [Department of Breast Surgery, Qilu Hospital, Shandong University, Ji' nan (China); Aly, Amal [Division of Medical Oncology, The Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); Goyal, Sharad; Schiff, Devora [Department of Radiation Oncology, Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); Moran, Meena S. [Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT (United States); Golhar, Ryan [Department of Radiation Oncology, Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); Chen Chunxia; Moore, Dirk [Department of Biostatistics, The Cancer Institute of New Jersey and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States); and others

2012-08-01

Purpose: To investigate whether the expression of p53 binding protein 1 (53BP1) has prognostic significance in a cohort of early-stage breast cancer patients treated with breast-conserving surgery and radiotherapy (BCS+RT). Methods and Materials: A tissue microarray of early-stage breast cancer treated with BCS+RT from a cohort of 514 women was assayed for 53BP1, estrogen receptor, progesterone receptor, and HER2 expression by immunohistochemistry. Through log-rank tests and univariate and multivariate models, the staining profile of each tumor was correlated with clinical endpoints, including ipsilateral breast recurrence-free survival (IBRFS), distant metastasis-free survival (DMFS), cause-specific survival (CSS), recurrence-free survival (RFS), and overall survival (OS). Results: Of the 477 (93%) evaluable tumors, 63 (13%) were scored as low. Low expression of 53BP1 was associated with worse outcomes for all endpoints studied, including 10-year IBRFS (76.8% vs. 90.5%; P=.01), OS (66.4% vs. 81.7%; P=.02), CSS (66.0% vs. 87.4%; P<.01), DMFS (55.9% vs. 87.0%; P<.01), and RFS (45.2% vs. 80.6%; P<.01). Multivariate analysis incorporating various clinico-pathologic markers and 53BP1 expression found that 53BP1 expression was again an independent predictor of all endpoints (IBRFS: P=.0254; OS: P=.0094; CSS: P=.0033; DMFS: P=.0006; RFS: P=.0002). Low 53BP1 expression was also found to correlate with triple-negative (TN) phenotype (P<.01). Furthermore, in subset analysis of all TN breast cancer, negative 53BP1 expression trended for lower IBRFS (72.3% vs. 93.9%; P=.0361) and was significant for worse DMFS (48.2% vs. 86.8%; P=.0035) and RFS (37.8% vs. 83.7%; P=.0014). Conclusion: Our data indicate that low 53BP1 expression is an independent prognostic indicator for local relapse among other endpoints in early-stage breast cancer and TN breast cancer patients treated with BCS+RT. These results should be verified in larger cohorts of patients to validate their clinical

Low p53 Binding Protein 1 (53BP1) Expression Is Associated With Increased Local Recurrence in Breast Cancer Patients Treated With Breast-Conserving Surgery and Radiotherapy

International Nuclear Information System (INIS)

Neboori, Hanmanth J.R.; Haffty, Bruce G.; Wu Hao; Yang Qifeng; Aly, Amal; Goyal, Sharad; Schiff, Devora; Moran, Meena S.; Golhar, Ryan; Chen Chunxia; Moore, Dirk

2012-01-01

Purpose: To investigate whether the expression of p53 binding protein 1 (53BP1) has prognostic significance in a cohort of early-stage breast cancer patients treated with breast-conserving surgery and radiotherapy (BCS+RT). Methods and Materials: A tissue microarray of early-stage breast cancer treated with BCS+RT from a cohort of 514 women was assayed for 53BP1, estrogen receptor, progesterone receptor, and HER2 expression by immunohistochemistry. Through log–rank tests and univariate and multivariate models, the staining profile of each tumor was correlated with clinical endpoints, including ipsilateral breast recurrence–free survival (IBRFS), distant metastasis–free survival (DMFS), cause-specific survival (CSS), recurrence-free survival (RFS), and overall survival (OS). Results: Of the 477 (93%) evaluable tumors, 63 (13%) were scored as low. Low expression of 53BP1 was associated with worse outcomes for all endpoints studied, including 10-year IBRFS (76.8% vs. 90.5%; P=.01), OS (66.4% vs. 81.7%; P=.02), CSS (66.0% vs. 87.4%; P<.01), DMFS (55.9% vs. 87.0%; P<.01), and RFS (45.2% vs. 80.6%; P<.01). Multivariate analysis incorporating various clinico-pathologic markers and 53BP1 expression found that 53BP1 expression was again an independent predictor of all endpoints (IBRFS: P=.0254; OS: P=.0094; CSS: P=.0033; DMFS: P=.0006; RFS: P=.0002). Low 53BP1 expression was also found to correlate with triple-negative (TN) phenotype (P<.01). Furthermore, in subset analysis of all TN breast cancer, negative 53BP1 expression trended for lower IBRFS (72.3% vs. 93.9%; P=.0361) and was significant for worse DMFS (48.2% vs. 86.8%; P=.0035) and RFS (37.8% vs. 83.7%; P=.0014). Conclusion: Our data indicate that low 53BP1 expression is an independent prognostic indicator for local relapse among other endpoints in early-stage breast cancer and TN breast cancer patients treated with BCS+RT. These results should be verified in larger cohorts of patients to validate their

DRAGO (KIAA0247), a new DNA damage-responsive, p53-inducible gene that cooperates with p53 as oncosuppressor. [Corrected].

Science.gov (United States)

Polato, Federica; Rusconi, Paolo; Zangrossi, Stefano; Morelli, Federica; Boeri, Mattia; Musi, Alberto; Marchini, Sergio; Castiglioni, Vittoria; Scanziani, Eugenio; Torri, Valter; Broggini, Massimo

2014-04-01

p53 influences genomic stability, apoptosis, autophagy, response to stress, and DNA damage. New p53-target genes could elucidate mechanisms through which p53 controls cell integrity and response to damage. DRAGO (drug-activated gene overexpressed, KIAA0247) was characterized by bioinformatics methods as well as by real-time polymerase chain reaction, chromatin immunoprecipitation and luciferase assays, time-lapse microscopy, and cell viability assays. Transgenic mice (94 p53(-/-) and 107 p53(+/-) mice on a C57BL/6J background) were used to assess DRAGO activity in vivo. Survival analyses were performed using Kaplan-Meier curves and the Mantel-Haenszel test. All statistical tests were two-sided. We identified DRAGO as a new p53-responsive gene induced upon treatment with DNA-damaging agents. DRAGO is highly conserved, and its ectopic overexpression resulted in growth suppression and cell death. DRAGO(-/-) mice are viable without macroscopic alterations. However, in p53(-/-) or p53(+/-) mice, the deletion of both DRAGO alleles statistically significantly accelerated tumor development and shortened lifespan compared with p53(-/-) or p53(+/-) mice bearing wild-type DRAGO alleles (p53(-/-), DRAGO(-/-) mice: hazard ratio [HR] = 3.25, 95% confidence interval [CI] = 1.7 to 6.1, P < .001; p53(+/-), DRAGO(-/-) mice: HR = 2.35, 95% CI = 1.3 to 4.0, P < .001; both groups compared with DRAGO(+/+) counterparts). DRAGO mRNA levels were statistically significantly reduced in advanced-stage, compared with early-stage, ovarian tumors, but no mutations were found in several human tumors. We show that DRAGO expression is regulated both at transcriptional-through p53 (and p73) and methylation-dependent control-and post-transcriptional levels by miRNAs. DRAGO represents a new p53-dependent gene highly regulated in human cells and whose expression cooperates with p53 in tumor suppressor functions.

RITA (Reactivating p53 and Inducing Tumor Apoptosis) is efficient against TP53abnormal myeloma cells independently of the p53 pathway.

Science.gov (United States)

Surget, Sylvanie; Descamps, Géraldine; Brosseau, Carole; Normant, Vincent; Maïga, Sophie; Gomez-Bougie, Patricia; Gouy-Colin, Nadège; Godon, Catherine; Béné, Marie C; Moreau, Philippe; Le Gouill, Steven; Amiot, Martine; Pellat-Deceunynck, Catherine

2014-06-14

The aim of this study was to evaluate the efficacy of the p53-reactivating drugs RITA and nutlin3a in killing myeloma cells. A large cohort of myeloma cell lines (n = 32) and primary cells (n = 21) was used for this study. This cohort contained cell lines with various TP53 statuses and primary cells with various incidences of deletion of chromosome 17. Apoptosis was evaluated using flow cytometry with Apo2.7 staining of the cell lines or via the loss of the myeloma-specific marker CD138 in primary cells. Apoptosis was further confirmed by the appearance of a subG1 peak and the activation of caspases 3 and 9. Activation of the p53 pathway was monitored using immunoblotting via the expression of the p53 target genes p21, Noxa, Bax and DR5. The involvement of p53 was further studied in 4 different p53-silenced cell lines. Both drugs induced the apoptosis of myeloma cells. The apoptosis that was induced by RITA was not related to the TP53 status of the cell lines or the del17p status of the primary samples (p = 0.52 and p = 0.80, respectively), and RITA did not commonly increase the expression level of p53 or p53 targets (Noxa, p21, Bax or DR5) in sensitive cells. Moreover, silencing of p53 in two TP53(mutated) cell lines failed to inhibit apoptosis that was induced by RITA, which confirmed that RITA-induced apoptosis in myeloma cells was p53 independent. In contrast, apoptosis induced by nutlin3a was directly linked to the TP53 status of the cell lines and primary samples (p RITA, in contrast to nutlin3a, effectively induced apoptosis in a subset of MM cells independently of p53. The findings and could be of interest for patients with a 17p deletion, who are resistant to current therapies.

Autonomous feedback loop of RUNX1-p53-CBFB in acute myeloid leukemia cells.

Science.gov (United States)

Morita, Ken; Noura, Mina; Tokushige, Chieko; Maeda, Shintaro; Kiyose, Hiroki; Kashiwazaki, Gengo; Taniguchi, Junichi; Bando, Toshikazu; Yoshida, Kenichi; Ozaki, Toshifumi; Matsuo, Hidemasa; Ogawa, Seishi; Liu, Pu Paul; Nakahata, Tatsutoshi; Sugiyama, Hiroshi; Adachi, Souichi; Kamikubo, Yasuhiko

2017-11-30

Although runt-related transcription factor 1 (RUNX1) and its associating core binding factor-β (CBFB) play pivotal roles in leukemogenesis, and inhibition of RUNX1 has now been widely recognized as a novel strategy for anti-leukemic therapies, it has been elusive how leukemic cells could acquire the serious resistance against RUNX1-inhibition therapies and also whether CBFB could participate in this process. Here, we show evidence that p53 (TP53) and CBFB are sequentially up-regulated in response to RUNX1 depletion, and their mutual interaction causes the physiological resistance against chemotherapy for acute myeloid leukemia (AML) cells. Mechanistically, p53 induced by RUNX1 gene silencing directly binds to CBFB promoter and stimulates its transcription as well as its translation, which in turn acts as a platform for the stabilization of RUNX1, thereby creating a compensative RUNX1-p53-CBFB feedback loop. Indeed, AML cells derived from relapsed cases exhibited higher CBFB expression levels compared to those from primary AML cells at diagnosis, and these CBFB expressions were positively correlated to those of p53. Our present results underscore the importance of RUNX1-p53-CBFB regulatory loop in the development and/or maintenance of AML cells, which could be targeted at any sides of this triangle in strategizing anti-leukemia therapies.

Forkhead box protein A2, a pioneer factor for hepatogenesis, is involved in the expression of hepatic phenotype of alpha-fetoprotein-producing adenocarcinoma.

Science.gov (United States)

Yamamura, Nobuhisa; Fugo, Kazunori; Kishimoto, Takashi

2017-09-01

Alpha-fetoprotein (AFP)-producing adenocarcinoma is a high-malignant variant of adenocarcinoma with a hepatic or fetal-intestinal phenotype. The number of cases of AFP-producing adenocarcinomas is increasing, but the molecular mechanism underlying the aberrant production of AFP is unclear. Here we sought to assess the role of Forkhead box A (FoxA)2, which is a pioneer transcription factor in the differentiation of hepatoblasts. FoxA2 expression was investigated in five cases of AFP-producing gastric adenocarcinomas by immunohistochemistry, and all cases showed FoxA2 expression. Chromatin immunoprecipitation revealed the DNA binding of FoxA2 on the regulatory element of AFP gene in AFP-producing adenocarcinoma cells. The inhibition of FoxA2 expression with siRNA reduced the mRNA expression of liver-specific proteins, including AFP, albumin, and transferrin. The inhibition of FoxA2 also reduced the expressions of liver-enriched nuclear factors, i.e., hepatocyte nuclear factor (HNF) 4α and HNF6, although the expressions of HNF1α and HNF1β were not affected. The same effect as FoxA2 knockdown in AFP producing adenocarcinoma cells was also observed in hepatocellular carcinoma cells. Our results suggest that FoxA2 plays a key role in the expression of hepatic phenotype of AFP-producing adenocarcinomas. Copyright © 2017 Elsevier GmbH. All rights reserved.

PRAP1 is a novel executor of p53-dependent mechanisms in cell survival after DNA damage.

Science.gov (United States)

Huang, B H; Zhuo, J L; Leung, C H W; Lu, G D; Liu, J J; Yap, C T; Hooi, S C

2012-12-13

p53 has a crucial role in governing cellular mechanisms in response to a broad range of genotoxic stresses. During DNA damage, p53 can either promote cell survival by activating senescence or cell-cycle arrest and DNA repair to maintain genomic integrity for cell survival or direct cells to undergo apoptosis to eliminate extensively damaged cells. The ability of p53 to execute these two opposing cell fates depends on distinct signaling pathways downstream of p53. In this study, we showed that under DNA damage conditions induced by chemotherapeutic drugs, gamma irradiation and hydrogen peroxide, p53 upregulates a novel protein, proline-rich acidic protein 1 (PRAP1). We identified functional p53-response elements within intron 1 of PRAP1 gene and showed that these regions interact directly with p53 using ChIP assays, indicating that PRAP1 is a novel p53 target gene. The induction of PRAP1 expression by p53 may promote resistance of cancer cells to chemotherapeutic drugs such as 5-fluorouracil (5-FU), as knockdown of PRAP1 increases apoptosis in cancer cells after 5-FU treatment. PRAP1 appears to protect cells from apoptosis by inducing cell-cycle arrest, suggesting that the induction of PRAP1 expression by p53 in response to DNA-damaging agents contributes to cancer cell survival. Our findings provide a greater insight into the mechanisms underlying the pro-survival role of p53 in response to cytotoxic treatments.

Expression of p53 and p21 in primary glioblastomas

International Nuclear Information System (INIS)

Gross, M.W.; Nashwan, K.; Engenhart-Cabillic, R.; Kraus, A.; Mennel, H.D.; Schlegel, J.

2005-01-01

Background and purpose: primary glioblastomas (GBMs) are highly radioresistant, and in contrast to secondary GBMs, they bear wild-type (wt) p53 protein, which is stabilized in a proportion of these tumors. Therefore, it was investigated in vivo whether p53 expression has prognostic value in patients undergoing radiochemotherapy. Additionally, the authors tried to identify, in vitro, subgroups of primary GBM with different susceptibilities to irradiation, on the basis of their p53 and p21 responses to ionizing radiation. Material and methods: tumor tissue samples from 31 patients suffering from primary GBM undergoing a combined radiochemotherapy with topotecan were investigated. The percentage of cells expressing p53 protein was determined immunohistochemically. Additionally, primary cultures from eleven primary GBMs were established and investigated. p53 and p21 expressions were evaluated before irradiation with 10 Gy and at 2 and 8 h after irradiation. p53 protein expression was measured by western analysis and p21 mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR). Results: the percentage of p53-positive cells within the tumor specimens obtained from the 31 patients ranged from 0% to 28%, the median value being 4.3%. No significant correlation with disease-free survival or overall survival was found. In vitro, p53 protein was detected in seven of eleven cultures from primary GBM. After irradiation a decrease in p53 protein expression was seen in six of the seven p53-positive cultures. Half of the cultures (two of four) without basal p53 expression showed an increase in p53 expression after irradiation. Basal overexpression of p21 was detected in six of the eleven cultures; in four out of six irradiation led to a decrease in p21 expression. In all cell lines (five of eleven) initially showing absent p21 expression, irradiation induced p21 expression. Despite these responses, G1 arrest was not detectable in any of the GBM cultures

Mutant p53 perturbs DNA replication checkpoint control through TopBP1 and Treslin.

Science.gov (United States)

Liu, Kang; Lin, Fang-Tsyr; Graves, Joshua D; Lee, Yu-Ju; Lin, Weei-Chin

2017-05-09

Accumulating evidence supports the gain-of-function of mutant forms of p53 (mutp53s). However, whether mutp53 directly perturbs the DNA replication checkpoint remains unclear. Previously, we have demonstrated that TopBP1 forms a complex with mutp53s and mediates their gain-of-function through NF-Y and p63/p73. Akt phosphorylates TopBP1 and induces its oligomerization, which inhibits its ATR-activating function. Here we show that various contact and conformational mutp53s bypass Akt to induce TopBP1 oligomerization and attenuate ATR checkpoint response during replication stress. The effect on ATR response caused by mutp53 can be exploited in a synthetic lethality strategy, as depletion of another ATR activator, DNA2, in mutp53-R273H-expressing cancer cells renders cells hypersensitive to cisplatin. Expression of mutp53-R273H also makes cancer cells more sensitive to DNA2 depletion or DNA2 inhibitors. In addition to ATR-activating function during replication stress, TopBP1 interacts with Treslin in a Cdk-dependent manner to initiate DNA replication during normal growth. We find that mutp53 also interferes with TopBP1 replication function. Several contact, but not conformational, mutp53s enhance the interaction between TopBP1 and Treslin and promote DNA replication despite the presence of a Cdk2 inhibitor. Together, these data uncover two distinct mechanisms by which mutp53 enhances DNA replication: ( i ) Both contact and conformational mutp53s can bind TopBP1 and attenuate the checkpoint response to replication stress, and ( ii ) during normal growth, contact (but not conformational) mutp53s can override the Cdk2 requirement to promote replication by facilitating the TopBP1/Treslin interaction.

Two sequence motifs from HIF-1α bind to the DNA-binding site of p53

OpenAIRE

Hansson, Lars O.; Friedler, Assaf; Freund, Stefan; Rüdiger, Stefan; Fersht, Alan R.

2002-01-01

There is evidence that hypoxia-inducible factor-1α (HIF-1α) interacts with the tumor suppressor p53. To characterize the putative interaction, we mapped the binding of the core domain of p53 (p53c) to an array of immobilized HIF-1α-derived peptides and found two peptide-sequence motifs that bound to p53c with micromolar affinity in solution. One sequence was adjacent to and the other coincided with the two proline residues of the oxygen-dependent degradation domain (P402 and P564) that act as...

Investigating the Sensitivity of NAD+-dependent Sirtuin Deacylation Activities to NADH

DEFF Research Database (Denmark)

Madsen, Andreas Stahl; Andersen, Christian; Daoud, Mohammad Mahdi

2016-01-01

Protein lysine posttranslational modification by an increasing number of different acyl groups is becoming appreciated as a regulatory mechanism in cellular biology. Sirtuins are class III histone deacylases that use NAD+ as a co-substrate during amide bond hydrolysis. Several studies have...... described the sirtuins as sensors of the NAD+/NADH ratio, but it has not been formally tested for all the mammalian sirtuins in vitro. To address this problem, we first synthesized a wide variety of peptide-based probes, which were used to identify the range of hydrolytic activities of human sirtuins...... to be prone to hydrolytic cleavage by SIRT1-3 and SIRT6, supporting recent findings. We then tested the ability of NADH, ADP-ribose, and nicotinamide to inhibit these NAD+-dependent deacylase activities of the sirtuins. In the commonly used 7-amino-4-methylcoumarin-coupled fluorescence-based assay...

Correlation between expression of p53, p21/WAF1, and MDM2 proteins and their prognostic significance in primary hepatocellular carcinoma

Directory of Open Access Journals (Sweden)

Fu Jia

2009-12-01

Full Text Available Abstract Background Tumor Protein p53 (p53, cyclin-dependent kinase inhibitor 1A (p21/WAF1, and murine double minute 2 (MDM2 participate in the regulation of cell growth. Altered expression of these gene products has been found in malignant tumors and has been associated with poor prognosis. Our aim was to investigate the expression of the 3 proteins in hepatocellular carcinoma (HCC and their prognostic significance. Methods We examined p53, p21/WAF1, and MDM2 expression in 181 pairs of HCC tissues and the adjacent hepatic tissues by performing immunohistochemistry and examined the expression of the 3 proteins in 7 pairs of HCC tissues and the adjacent hepatic tissues by using western blot analysis. Results The expression of p53, p21/WAF1, and MDM2 in the HCC tissues was significantly higher than those in the adjacent hepatic tissues (P P = 0.008. A statistical correlation was observed between expression of p53 and p21/WAF1 (R = 0.380, P = 0.000, p53 and MDM2 (R = 0.299, P = 0.000, p21/WAF1 and MDM2 (R = 0.285, P = 0.000 in 181 liver tissues adjacent to the tumor. Patients with a low pathologic grade HCC (I+II had a higher tendency to express p53 on tumor cells than the patients with high pathologic grade HCC (III+IV (P = 0.007. Survival analysis showed that positive p21/WAF1 expression or/and negative MDM2 expression in HCC was a predictor of better survival of patients after tumor resection (P Conclusions The proteins p53, p21/WAF1, and MDM2 were overexpressed in all the HCC cases in this study, and p53 and p21/WAF1 overexpression were positively correlated. The expression of p21/WAF1 and MDM2 can be considered as 2 useful indicators for predicting the prognosis of HCC.

12038_2016_9616_Supplementary 1..4

Indian Academy of Sciences (India)

homeostasis, autoimmunity, responses to infection, cancers and inflammation. ... CD40+CD4+T cells involved in type-I diabetes through binding of Gal-9 with CD40. ... ForssmanGlycosphingolipid; FOXP3: Forkhead Box P3; GLUT 2: Glucose.

Inhibition of p53 acetylation by INHAT subunit SET/TAF-Iβ represses p53 activity.

Science.gov (United States)

Kim, Ji-Young; Lee, Kyu-Sun; Seol, Jin-Ee; Yu, Kweon; Chakravarti, Debabrata; Seo, Sang-Beom

2012-01-01

The tumor suppressor p53 responds to a wide variety of cellular stress signals. Among potential regulatory pathways, post-translational modifications such as acetylation by CBP/p300 and PCAF have been suggested for modulation of p53 activity. However, exactly how p53 acetylation is modulated remains poorly understood. Here, we found that SET/TAF-Iβ inhibited p300- and PCAF-mediated p53 acetylation in an INHAT (inhibitor of histone acetyltransferase) domain-dependent manner. SET/TAF-Iβ interacted with p53 and repressed transcription of p53 target genes. Consequently, SET/TAF-Iβ blocked both p53-mediated cell cycle arrest and apoptosis in response to cellular stress. Using different apoptosis analyses, including FACS, TUNEL and BrdU incorporation assays, we also found that SET/TAF-Iβ induced cellular proliferation via inhibition of p53 acetylation. Furthermore, we observed that apoptotic Drosophila eye phenotype induced by either dp53 overexpression or UV irradiation was rescued by expression of dSet. Inhibition of dp53 acetylation by dSet was observed in both cases. Our findings provide new insights into the regulation of stress-induced p53 activation by HAT-inhibiting histone chaperone SET/TAF-Iβ.

Sirtuin-1 regulates acinar-to-ductal metaplasia and supports cancer cell viability in pancreatic cancer.

Science.gov (United States)

Wauters, Elke; Sanchez-Arévalo Lobo, Victor J; Pinho, Andreia V; Mawson, Amanda; Herranz, Daniel; Wu, Jianmin; Cowley, Mark J; Colvin, Emily K; Njicop, Erna Ngwayi; Sutherland, Rob L; Liu, Tao; Serrano, Manuel; Bouwens, Luc; Real, Francisco X; Biankin, Andrew V; Rooman, Ilse

2013-04-01

The exocrine pancreas can undergo acinar-to-ductal metaplasia (ADM), as in the case of pancreatitis where precursor lesions of pancreatic ductal adenocarcinoma (PDAC) can arise. The NAD(+)-dependent protein deacetylase Sirtuin-1 (Sirt1) has been implicated in carcinogenesis with dual roles depending on its subcellular localization. In this study, we examined the expression and the role of Sirt1 in different stages of pancreatic carcinogenesis, i.e. ADM models and established PDAC. In addition, we analyzed the expression of KIAA1967, a key mediator of Sirt1 function, along with potential Sirt1 downstream targets. Sirt1 was co-expressed with KIAA1967 in the nuclei of normal pancreatic acinar cells. In ADM, Sirt1 underwent a transient nuclear-to-cytoplasmic shuttling. Experiments where during ADM, we enforced repression of Sirt1 shuttling, inhibition of Sirt1 activity or modulation of its expression, all underscore that the temporary decrease of nuclear and increase of cytoplasmic Sirt1 stimulate ADM. Our results further underscore that important transcriptional regulators of acinar differentiation, that is, Pancreatic transcription factor-1a and β-catenin can be deacetylated by Sirt1. Inhibition of Sirt1 is effective in suppression of ADM and in reducing cell viability in established PDAC tumors. KIAA1967 expression is differentially downregulated in PDAC and impacts on the sensitivity of PDAC cells to the Sirt1/2 inhibitor Tenovin-6. In PDAC, acetylation of β-catenin is not affected, unlike p53, a well-characterized Sirt1-regulated protein in tumor cells. Our results reveal that Sirt1 is an important regulator and potential therapeutic target in pancreatic carcinogenesis. ©2012 AACR.

Metformin and Resveratrol Inhibited High Glucose-Induced Metabolic Memory of Endothelial Senescence through SIRT1/p300/p53/p21 Pathway.

Science.gov (United States)

Zhang, Erli; Guo, Qianyun; Gao, Haiyang; Xu, Ruixia; Teng, Siyong; Wu, Yongjian

2015-01-01

Endothelial senescence plays crucial roles in diabetic vascular complication. Recent evidence indicated that transient hyperglycaemia could potentiate persistent diabetic vascular complications, a phenomenon known as "metabolic memory." Although SIRT1 has been demonstrated to mediate high glucose-induced endothelial senescence, whether and how "metabolic memory" would affect endothelial senescence through SIRT1 signaling remains largely unknown. In this study, we investigated the involvement of SIRT1 axis as well as the protective effects of resveratrol (RSV) and metformin (MET), two potent SIRT1 activators, during the occurrence of "metabolic memory" of cellular senescence (senescent "memory"). Human umbilical vascular endothelial cells (HUVECs) were cultured in either normal glucose (NG)/high glucose (HG) media for 6 days, or 3 days of HG followed by 3 days of NG (HN), with or without RSV or MET treatment. It was shown that HN incubation triggered persistent downregulation of deacetylase SIRT1 and upregulation of acetyltransferase p300, leading to sustained hyperacetylation (at K382) and activation of p53, and subsequent p53/p21-mediated senescent "memory." In contrast, senescent "memory" was abrogated by overexpression of SIRT1 or knockdown of p300. Interestingly, we found that SIRT1 and p300 could regulate each other in response to HN stimulation, suggesting that a delicate balance between acetyltransferases and deacetylases may be particularly important for sustained acetylation and activation of non-histone proteins (such as p53), and eventually the occurrence of "metabolic memory." Furthermore, we found that RSV or MET treatment prevented senescent "memory" by modulating SIRT1/p300/p53/p21 pathway. Notably, early and continuous treatment of MET, but not RSV, was particularly important for preventing senescent "memory." In conclusion, short-term high glucose stimulation could induce sustained endothelial senescence via SIRT1/p300/p53/p21 pathway. RVS or MET

Human NTH1 physically interacts with p53 and proliferating cell nuclear antigen

International Nuclear Information System (INIS)

Oyama, Masaki; Wakasugi, Mitsuo; Hama, Takashi; Hashidume, Hatsuho; Iwakami, Yasutaka; Imai, Rika; Hoshino, Sanae; Morioka, Hiroshi; Ishigaki, Yasuhito; Nikaido, Osamu; Matsunaga, Tsukasa

2004-01-01

Thymine glycol (Tg) is one of predominant oxidative DNA lesions caused by ionizing radiation and other oxidative stresses. Human NTH1 is a bifunctional enzyme with DNA glycosylase and AP lyase activities and removes Tg as the first step of base excision repair (BER). We have searched for the factors interacting with NTH1 by using a pull-down assay and found that GST-NTH1 fusion protein precipitates proliferating cell nuclear antigen (PCNA) and p53 as well as XPG from human cell-free extracts. GST-NTH1 also bound to recombinant FLAG-tagged XPG, PCNA, and (His) 6 -tagged p53 proteins, indicating direct protein-protein interaction between those proteins. Furthermore, His-p53 and FLAG-XPG, but not PCNA, stimulated the Tg DNA glycosylase/AP lyase activity of GST-NTH1 or NTH1. These results provide an insight into the positive regulation of BER reaction and also suggest a possible linkage between BER of Tg and other cellular mechanisms

Sirtuins and renal diseases: relationship with aging and diabetic nephropathy.

Science.gov (United States)

Kitada, Munehiro; Kume, Shinji; Takeda-Watanabe, Ai; Kanasaki, Keizo; Koya, Daisuke

2013-02-01

Sirtuins are members of the Sir2 (silent information regulator 2) family, a group of class III deacetylases. Mammals have seven different sirtuins, SIRT1-SIRT7. Among them, SIRT1, SIRT3 and SIRT6 are induced by calorie restriction conditions and are considered anti-aging molecules. SIRT1 has been the most extensively studied. SIRT1 deacetylates target proteins using the coenzyme NAD+ and is therefore linked to cellular energy metabolism and the redox state through multiple signalling and survival pathways. SIRT1 deficiency under various stress conditions, such as metabolic or oxidative stress or hypoxia, is implicated in the pathophysiologies of age-related diseases including diabetes, cardiovascular diseases, neurodegenerative disorders and renal diseases. In the kidneys, SIRT1 may inhibit renal cell apoptosis, inflammation and fibrosis, and may regulate lipid metabolism, autophagy, blood pressure and sodium balance. Therefore the activation of SIRT1 in the kidney may be a new therapeutic target to increase resistance to many causal factors in the development of renal diseases, including diabetic nephropathy. In addition, SIRT3 and SIRT6 are implicated in age-related disorders or longevity. In the present review, we discuss the protective functions of sirtuins and the association of sirtuins with the pathophysiology of renal diseases, including diabetic nephropathy.

Arecoline-induced phosphorylated p53 and p21(WAF1) protein expression is dependent on ATM/ATR and phosphatidylinositol-3-kinase in clone-9 cells.

Science.gov (United States)

Chou, Wen-Wen; Guh, Jinn-Yuh; Tsai, Jung-Fa; Hwang, Chi-Ching; Chiou, Shean-Jaw; Chuang, Lea-Yea

2009-06-01

Betel-quid use is associated with liver cancer whereas its constituent arecoline is cytotoxic, genotoxic, and induces p53-dependent p21(WAF1) protein expression in Clone-9 cells (rat hepatocytes). The ataxia telangiectasia mutated (ATM)/rad3-related (ATR)-p53-p21(WAF1) and the phosphatidylinositol-3-kinase (PI3K)-mammalian target of rapamycin (mTOR) pathways are involved in the DNA damage response and the pathogenesis of cancers. Thus, we studied the role of ATM/ATR and PI3K in arecoline-induced p53 and p21(WAF1) protein expression in Clone-9 cells. We found that arecoline (0.5 mM) activated the ATM/ATR kinase at 30 min. The arecoline-activated ATM/ATR substrate contained p-p53Ser15. Moreover, arecoline only increased the levels of the p-p53Ser6, p-p53Ser15, and p-p53Ser392 phosphorylated p53 isoforms among the known isoforms. ATM shRNA attenuated arecoline-induced p-p53Ser15 and p21(WAF1) at 24 h. Arecoline (0.5 mM) increased phosphorylation levels of p-AktSer473 and p-mTORSer2448 at 30-60 min. Dominant-negative PI3K plasmids attenuated arecoline-induced p21(WAF1), but not p-p53Ser15, at 24 h. Rapamycin attenuated arecoline-induced phosphrylated p-p53Ser15, but not p21(WAF1), at 24 h. ATM shRNA, but not dominant-negative PI3K plasmids, attenuated arecoline-induced p21(WAF1) gene transcription. We conclude that arecoline activates the ATM/ATR-p53-p21(WAF1) and the PI3K/Akt-mTOR-p53 pathways in Clone-9 cells. Arecoline-induced phosphorylated p-p53Ser15 expression is dependent on ATM whereas arecoline-induced p21(WAF1) protein expression is dependent on ATM and PI3K. Moreover, p21(WAF1) gene is transcriptionally induced by arecoline-activated ATM. (c) 2009 Wiley-Liss, Inc.

The Contribution of Transactivation Subdomains 1 and 2 to p53-Induced Gene Expression Is Heterogeneous But Not Subdomain-Specific

Directory of Open Access Journals (Sweden)

Jennifer M. Smith

2007-12-01

Full Text Available Two adjacent regions within the transactivation domain of p53 are sufficient to support sequence-specific transactivation when fused to a heterologous DNA binding domain. It has been hypothesized that these two subdomains of p53 may contribute to the expression of distinct p53-responsive genes. Here we have used oligonucleotide microarrays to identify transcripts induced by variants of p53 with point mutations within subdomains 1, 2, or 1 and 2 (QS1, QS2, QS1/QS2, respectively. The expression of 254 transcripts was increased in response to wild-type p53 expression but most of these transcripts were poorly induced by these variants of p53. Strikingly, a number of known p53regulated transcripts including TNFRSF10B, BAX, BTG2, POLH were increased to wild-type levels by p53QS1 and p53QS2 but not p53QS1/QS2, indicating that either sub domain 1 or 2 is sufficient for p53-dependent expression of a small subset of p53-responsive genes. Unexpectedly, there was no evidence for p53QS1- or p53QS2-specific gene expression. Taken together, we found heterogeneity in the requirement for transactivation subdomains 1 and 2 of p53 without any subdomain-specific contribution to p53-induced gene expression.

Synergistic interactions between HDAC and sirtuin inhibitors in human leukemia cells.

Directory of Open Access Journals (Sweden)

Michele Cea

Full Text Available Aberrant histone deacetylase (HDAC activity is frequent in human leukemias. However, while classical, NAD(+-independent HDACs are an established therapeutic target, the relevance of NAD(+-dependent HDACs (sirtuins in leukemia treatment remains unclear. Here, we assessed the antileukemic activity of sirtuin inhibitors and of the NAD(+-lowering drug FK866, alone and in combination with traditional HDAC inhibitors. Primary leukemia cells, leukemia cell lines, healthy leukocytes and hematopoietic progenitors were treated with sirtuin inhibitors (sirtinol, cambinol, EX527 and with FK866, with or without addition of the HDAC inhibitors valproic acid, sodium butyrate, and vorinostat. Cell death was quantified by propidium iodide cell staining and subsequent flow-cytometry. Apoptosis induction was monitored by cell staining with FITC-Annexin-V/propidium iodide or with TMRE followed by flow-cytometric analysis, and by measuring caspase3/7 activity. Intracellular Bax was detected by flow-cytometry and western blotting. Cellular NAD(+ levels were measured by enzymatic cycling assays. Bax was overexpressed by retroviral transduction. Bax and SIRT1 were silenced by RNA-interference. Sirtuin inhibitors and FK866 synergistically enhanced HDAC inhibitor activity in leukemia cells, but not in healthy leukocytes and hematopoietic progenitors. In leukemia cells, HDAC inhibitors were found to induce upregulation of Bax, a pro-apoptotic Bcl2 family-member whose translocation to mitochondria is normally prevented by SIRT1. As a result, leukemia cells become sensitized to sirtuin inhibitor-induced apoptosis. In conclusion, NAD(+-independent HDACs and sirtuins cooperate in leukemia cells to avoid apoptosis. Combining sirtuin with HDAC inhibitors results in synergistic antileukemic activity that could be therapeutically exploited.

p53 Protein interacts specifically with the meiosis-specific mammalian RecA-like protein DMC1 in meiosis.

Science.gov (United States)

Habu, Toshiyuki; Wakabayashi, Nobunao; Yoshida, Kayo; Yomogida, Kenntaro; Nishimune, Yoshitake; Morita, Takashi

2004-06-01

The tumor suppressor protein p53 is specifically expressed during meiosis in spermatocytes. Subsets of p53 knockout mice exhibit testicular giant cell degenerative syndrome, which suggests p53 may be associated with meiotic cell cycle and/or DNA metabolism. Here, we show that p53 binds to the mouse meiosis-specific RecA-like protein Mus musculus DMC1 (MmDMC1). The C-terminal domain (amino acid 234-340) of MmDMC1 binds to DNA-binding domain of p53 protein. p53 might be involved in homologous recombination and/or checkpoint function by directly binding to DMC1 protein to repress genomic instability in meiotic germ cells.

Targeting the p53 Pathway in Ewing Sarcoma

Science.gov (United States)

Neilsen, Paul M.; Pishas, Kathleen I.; Callen, David F.; Thomas, David M.

2011-01-01

The p53 tumour suppressor plays a pivotal role in the prevention of oncogenic transformation. Cancers frequently evade the potent antitumour surveillance mechanisms of p53 through mutation of the TP53 gene, with approximately 50% of all human malignancies expressing dysfunctional, mutated p53 proteins. Interestingly, genetic lesions in the TP53 gene are only observed in 10% of Ewing Sarcomas, with the majority of these sarcomas expressing a functional wild-type p53. In addition, the p53 downstream signaling pathways and DNA-damage cell cycle checkpoints remain functionally intact in these sarcomas. This paper summarizes recent insights into the functional capabilities and regulation of p53 in Ewing Sarcoma, with a particular focus on the cross-talk between p53 and the EWS-FLI1 gene rearrangement frequently associated with this disease. The development of several activators of p53 is discussed, with recent evidence demonstrating the potential of small molecule p53 activators as a promising systemic therapeutic approach for the treatment of Ewing Sarcomas with wild-type p53. PMID:21197471

Biologic effect of exogenous wild p53 combined with irradiation on human melanoma cell lines with different p53 status

International Nuclear Information System (INIS)

Min Fengling; Zhang Hong; Li Wenjian; Liu Bing; Zhou Qingming; Duan Xin; Gao Qingxiang

2007-01-01

Objective: To investigate the effect of low dose irradiation on gene transfer efficiency and the effect of adenoviral-mediated exogenous P53 overexpression on apoptosis and radiosensitivity of radioresistant human melanoma cell lines A375(wild type p53)and WM983a(mutant type p53). Methods: Control vector, a replication deficient recombinant adenoviral vector containing a CMV promoter and green fluorescent protein (AdCMV-GFP), was used to transfect A375 cells and WM983a cells preirradiated with or without 1 Gy X-ray. The transduction efficiency of GFP gene was determined with fluorescence microscope directly. These two types of cells irradiated by 1 Gy X-ray were transfected with a replication deficient recombinant adenoviral vector carrying human wild p53 (AdCMV-p53), and mRNA level was detected by RT-PCR. The cell cycle delay and the expression of exogenous P53 were detected using flow cytometry (FCM) at different times after transfection. Tunel technique was used to detect cell apoptosis. The radiosensivity of A375 and WM983a cells after p53 transduction was analyzed by colony formation. Results: It is found that 1 Gy irradiation increased the gene transfection efficiency of A375 and WM983a cells. The expression of exogenous P53 was found to range from 60% to 80% among transfected cells during the first three days after transduction and then declined continuously down to the control level on day 10. G 1 cell cycle arrest was also observed after p53 gene transduction. WM983a cells transfected with p53 showed higher sensitivity to X-ray-induced cell killing than A375 cells. Conclusions: It is indicated that low dose of ionizing radiation can improve gene transfection efficiency of A375 and WM983a cells mediated by adenovirus vector. Althrough the overexpresion of exogenous p53 may not inhibit cell growth and induce apoptosis of melanoma cell line A375 and WM983a irt vitro, the two cell lines are much more sensitive to cell death induced by irradiation. It is

Andrographolide induces vascular smooth muscle cell apoptosis through a SHP-1-PP2A-p38MAPK-p53 cascade.

Science.gov (United States)

Chen, Yu-Ying; Hsieh, Cheng-Ying; Jayakumar, Thanasekaran; Lin, Kuan-Hung; Chou, Duen-Suey; Lu, Wan-Jung; Hsu, Ming-Jen; Sheu, Joen-Rong

2014-07-10

The abnormal growth of vascular smooth muscle cells (VSMCs) is considered a critical pathogenic process in inflammatory vascular diseases. We have previously demonstrated that protein phosphatase 2 A (PP2A)-mediated NF-κB dephosphorylation contributes to the anti-inflammatory properties of andrographolide, a novel NF-κB inhibitor. In this study, we investigated whether andrographolide causes apoptosis, and characterized its apoptotic mechanisms in rat VSMCs. Andrographolide activated the p38 mitogen-activated protein kinase (p38MAPK), leading to p53 phosphorylation. Phosphorylated p53 subsequently transactivated the expression of Bax, a pro-apoptotic protein. Transfection with pp2a small interfering RNA (siRNA) suppressed andrographolide-induced p38MAPK activation, p53 phosphorylation, and caspase 3 activation. Andrographolide also activated the Src homology 1 domain-containing protein tyrosine phosphatase (SHP-1), and induced PP2A dephosphorylation, both of which were inhibited by the SHP-1 inhibitor sodium stibogluconate (SSG) or shp-1 siRNA. SSG or shp-1 siRNA prevented andrographolide-induced apoptosis. These results suggest that andrographolide activates the PP2A-p38MAPK-p53-Bax cascade, causing mitochondrial dysfunction and VSMC death through an SHP-1-dependent mechanism.

Loss of p53 enhances the function of the endoplasmic reticulum through activation of the IRE1α/XBP1 pathway

Science.gov (United States)

Kodama, Rika; Byun, Sanguine; Yoon, Kyoung Wan; Hiraki, Masatsugu; Mandinova, Anna; Lee, Sam W.

2015-01-01

Altered regulation of ER stress response has been implicated in a variety of human diseases, such as cancer and metabolic diseases. Excessive ER function contributes to malignant phenotypes, such as chemoresistance and metastasis. Here we report that the tumor suppressor p53 regulates ER function in response to stress. We found that loss of p53 function activates the IRE1α/XBP1 pathway to enhance protein folding and secretion through upregulation of IRE1α and subsequent activation of its target XBP1. We also show that wild-type p53 interacts with synoviolin (SYVN1)/HRD1/DER3, a transmembrane E3 ubiquitin ligase localized to ER during ER stress and removes unfolded proteins by reversing transport to the cytosol from the ER, and its interaction stimulates IRE1α degradation. Moreover, IRE1α inhibitor suppressed protein secretion, induced cell death in p53-deficient cells, and strongly suppressed the formation of tumors by p53-deficient human tumor cells in vivo compared with those that expressed wild-type p53. Therefore, our data imply that the IRE1α/XBP1 pathway serves as a target for therapy of chemoresistant tumors that express mutant p53. PMID:26254280

Heart Rate and Liking During "Kinect Boxing" Versus "Wii Boxing": The Potential for Enjoyable Vigorous Physical Activity Videogames.

Science.gov (United States)

Sanders, Gabriel J; Peacock, Corey A; Barkley, Jacob E; Gish, Brian; Brock, Scott; Volpenhein, Josh

2015-08-01

Nintendo(®) (Kyoto, Japan) "Wii™ Sports Boxing" ("Wii Boxing") and Xbox(®) (Microsoft, Redmond, WA) "Kinect(®) Sports Boxing" ("Kinect Boxing") are both boxing simulation videogames that are available for two different active videogame (AVG) systems. Although these AVGs are similar, the style of gameplay required is different (i.e., upper body only versus total body movements) and may alter physical activity intensity and one's preference for playing one game over the other. AVGs that elicit the greatest physiologic challenge and are preferred by users should be identified in an effort to enhance the efficacy of physical activity interventions and programs that include AVGs. The mean heart rate (HRmean) and peak heart rate (HRpeak) for 27 adults (22.7±4.2 years old) were recorded during four 10-minute conditions: seated rest, treadmill walking at 3 miles/hour, "Wii Boxing," and "Kinect Boxing." Upon completion of all four conditions, participants indicated which condition they preferred, and HRmean and HRpeak were calculated as a percentage of age-predicted maximum heart rate to classify physical activity intensity for the three activity conditions (treadmill, "Wii Boxing," and "Kinect Boxing"). "Kinect Boxing" significantly (P<0.001) increased percentage HRmean (64.1±1.6 percent of age-predicted maximum) and percentage HRpeak (76.5±1.9 percent) above all other conditions: Wii HRmean, 53.0±1.2 percent; Wii HRpeak, 61.8±1.5 percent; treadmill HRmean, 52.4±1.2 percent; treadmill HRpeak, 55.2±2.2 percent. Percentage HRpeak for "Kinect Boxing" was great enough to be considered a vigorous-intensity physical activity. There was no difference (P=0.55) in percentage HRmean between "Wii Boxing" and treadmill walking. Participants also preferred "Kinect Boxing" (P<0.001; n=26) to all other conditions ("Wii Boxing," n=1; treadmill n=0). "Kinect Boxing" was the most preferred and the only condition that was physiologically challenging enough to be classified as a

Bcl-2 protein expression is associated with p27 and p53 protein expressions and MIB-1 counts in breast cancer

International Nuclear Information System (INIS)

Tsutsui, Shinichi; Yasuda, Kazuhiro; Suzuki, Kosuke; Takeuchi, Hideya; Nishizaki, Takashi; Higashi, Hidefumi; Era, Shoichi

2006-01-01

Recent experimental studies have shown that Bcl-2, which has been established as a key player in the control of apoptosis, plays a role in regulating the cell cycle and proliferation. The aim of this study was to investigate the relationship between Bcl-2 and p27 protein expression, p53 protein expression and the proliferation activity as defined by the MIB-1 counts. The prognostic implication of Bcl-2 protein expression in relation to p27 and p53 protein expressions and MIB-1 counts for breast cancer was also evaluated. The immunohistochemical expression of Bcl-2 protein was evaluated in a series of 249 invasive ductal carcinomas of the breast, in which p27 and p53 protein expressions and MIB-1 counts had been determined previously. The Bcl-2 protein expression was found to be decreased in 105 (42%) cases. A decreased Bcl-2 protein expression was significantly correlated with a nuclear grade of III, a negative estrogen receptor, a decreased p27 protein expression, a positive p53 protein expression, positive MIB-1 counts and a positive HER2 protein expression. The incidence of a nuclear grade of III and positive MIB-1 counts increased as the number of abnormal findings of Bcl-2, p27 and p53 protein expressions increased. A univariate analysis indicated a decreased Bcl-2 protein expression to be significantly (p = 0.0089) associated with a worse disease free survival (DFS), while a multivariate analysis indicated the lymph node status and MIB-1 counts to be independently significant prognostic factors for the DFS. The Bcl-2 protein expression has a close correlation with p27 and p53 protein expressions and the proliferation activity determined by MIB-1 counts in invasive ductal carcinoma of the breast. The prognostic value of Bcl-2 as well as p27 and p53 protein expressions was dependent on the proliferation activity in breast cancer

Bcl-2 protein expression is associated with p27 and p53 protein expressions and MIB-1 counts in breast cancer

Directory of Open Access Journals (Sweden)

Nishizaki Takashi

2006-07-01

Full Text Available Abstract Background Recent experimental studies have shown that Bcl-2, which has been established as a key player in the control of apoptosis, plays a role in regulating the cell cycle and proliferation. The aim of this study was to investigate the relationship between Bcl-2 and p27 protein expression, p53 protein expression and the proliferation activity as defined by the MIB-1 counts. The prognostic implication of Bcl-2 protein expression in relation to p27 and p53 protein expressions and MIB-1 counts for breast cancer was also evaluated. Methods The immunohistochemical expression of Bcl-2 protein was evaluated in a series of 249 invasive ductal carcinomas of the breast, in which p27 and p53 protein expressions and MIB-1 counts had been determined previously. Results The Bcl-2 protein expression was found to be decreased in 105 (42% cases. A decreased Bcl-2 protein expression was significantly correlated with a nuclear grade of III, a negative estrogen receptor, a decreased p27 protein expression, a positive p53 protein expression, positive MIB-1 counts and a positive HER2 protein expression. The incidence of a nuclear grade of III and positive MIB-1 counts increased as the number of abnormal findings of Bcl-2, p27 and p53 protein expressions increased. A univariate analysis indicated a decreased Bcl-2 protein expression to be significantly (p = 0.0089 associated with a worse disease free survival (DFS, while a multivariate analysis indicated the lymph node status and MIB-1 counts to be independently significant prognostic factors for the DFS. Conclusion The Bcl-2 protein expression has a close correlation with p27 and p53 protein expressions and the proliferation activity determined by MIB-1 counts in invasive ductal carcinoma of the breast. The prognostic value of Bcl-2 as well as p27 and p53 protein expressions was dependent on the proliferation activity in breast cancer.

TGFbeta induces apoptosis and EMT in primary mouse hepatocytes independently of p53, p21Cip1 or Rb status

International Nuclear Information System (INIS)

Sheahan, Sharon; Bellamy, Christopher O; Harland, Stephen N; Harrison, David J; Prost, Sandrine

2008-01-01

TGFβ has pleiotropic effects that range from regulation of proliferation and apoptosis to morphological changes and epithelial-mesenchymal transition (EMT). Some evidence suggests that these effects may be interconnected. We have recently reported that P53, P21 Cip1 and pRB, three critical regulators of the G1/S transition are variably involved in TGFβ-induced cell cycle arrest in hepatocytes. As these proteins are also involved in the regulation of apoptosis in many circumstances, we investigated their contribution to other relevant TGFβ-induced effects, namely apoptosis and EMT, and examined how the various processes were interrelated. Primary mouse hepatocytes deficient in p53, p21 and/or Rb, singly or in combination were treated with TGFβ for 24 to 96 hours. Apoptosis was quantified according to morphology and by immunostaining for cleaved-capsase 3. Epithelial and mesenchymal marker expression was studied using immunocytochemistry and real time PCR. We found that TGFβ similarly induced morphological changes regardless of genotype and independently of proliferation index or sensitivity to inhibition of proliferation by TGFβ. Morphological changes were accompanied by decrease in E-cadherin and increased Snail expression but the mesenchymal markers (N-cadherin, SMAα and Vimentin) studied remained unchanged. TGFβ induced high levels of apoptosis in p53-/-, Rb-/-, p21 cip1 -/- and control hepatocytes although with slight differences in kinetics. This was unrelated to proliferation or changes in morphology and loss of cell-cell adhesion. However, hepatocytes deficient in both p53 and p21 cip1 were less sensitive to TGFβ-induced apoptosis. Although p53, p21 Cip1 and pRb are well known regulators of both proliferation and apoptosis in response to a multitude of stresses, we conclude that they are critical for TGFβ-driven inhibition of hepatocytes proliferation, but only slightly modulate TGFβ-induced apoptosis. This effect may depend on other parameters

1 RESEARCH ARTICLE

Indian Academy of Sciences (India)

HP

Study of Association of Forkhead Box P3 (FOXP3) Gene Polymorphisms with Unexplained Recurrent ... Purpose: Recurrent spontaneous abortions (RSA) is defined as 3 or more ... and no abortion were included as case and control groups respectively. ... Human FOXP3 gene (Gene ID: 50943, MIM number: 300292) is a ...

A High-Throughput Cell-Based Screen Identified a 2-[(E)-2-Phenylvinyl]-8-Quinolinol Core Structure That Activates p53.

Science.gov (United States)

Bechill, John; Zhong, Rong; Zhang, Chen; Solomaha, Elena; Spiotto, Michael T

2016-01-01

p53 function is frequently inhibited in cancer either through mutations or by increased degradation via MDM2 and/or E6AP E3-ubiquitin ligases. Most agents that restore p53 expression act by binding MDM2 or E6AP to prevent p53 degradation. However, fewer compounds directly bind to and activate p53. Here, we identified compounds that shared a core structure that bound p53, caused nuclear localization of p53 and caused cell death. To identify these compounds, we developed a novel cell-based screen to redirect p53 degradation to the Skip-Cullin-F-box (SCF) ubiquitin ligase complex in cells expressing high levels of p53. In a multiplexed assay, we coupled p53 targeted degradation with Rb1 targeted degradation in order to identify compounds that prevented p53 degradation while not inhibiting degradation through the SCF complex or other proteolytic machinery. High-throughput screening identified several leads that shared a common 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that stabilized p53. Surface plasmon resonance analysis indicated that these compounds bound p53 with a KD of 200 ± 52 nM. Furthermore, these compounds increased p53 nuclear localization and transcription of the p53 target genes PUMA, BAX, p21 and FAS in cancer cells. Although p53-null cells had a 2.5±0.5-fold greater viability compared to p53 wild type cells after treatment with core compounds, loss of p53 did not completely rescue cell viability suggesting that compounds may target both p53-dependent and p53-independent pathways to inhibit cell proliferation. Thus, we present a novel, cell-based high-throughput screen to identify a 2-[(E)-2-phenylvinyl]-8-quinolinol core structure that bound to p53 and increased p53 activity in cancer cells. These compounds may serve as anti-neoplastic agents in part by targeting p53 as well as other potential pathways.

Enhancement of radiosensitivity of recombinant Ad-p53 gene on human lung adenocarcinoma cell with different p53 status

International Nuclear Information System (INIS)

Pang Dequan; Wang Peiguo; Wang Ping; Zhang Weiming

2008-01-01

Objective: To investigate the enhancement of radiosensitivity of recombinant Ad-p53 gene on human lung adenocarcinoma cell lines(A549 and GLC-82) with different p53 status in vitro. Methods: Two human lung adenocarcinoma cell lines of A549 and GLC-82 were examined on their difference in p53 status with immunohistochemistry stain and PCR-SSCP technique. Expand Ad-wtp53 was transfected into tumor cells. Clonogenic assays were performed to evaluate the inhibition effect on cell growth and the degree of sensitization to irradiation. Apoptosis and cell cycle changes were determined using the flow cytometry assay. Results: The A549 cell line presented positive P53 expression while GLC-82 negative. GLC-82 bore mutant p53 on the exon 7. The wtp53 gene could be efficiently expressed in the two cell lines and greatly inhibit the cell growth. Its efficiency didn't depend on the intrinsic p53 genetic status. After irradiation, its function of inducing G 1 arrest and apoptosis on GLC-82 cell line was much stronger than the A549 cell line. In both the A549 and GLC-82 cell lines, the combination of Ad-p53 plus radiation resulted in more apoptosis than the others. There was no significant difference between two groups. Conclusions: Ad-p53 can depress the tumor growth and enhance the radiosensitivity of human lung adenocarcinoma cells. And this effect is independent of endogenous p53 status. (authors)

p53 Aggregates penetrate cells and induce the co-aggregation of intracellular p53.

Directory of Open Access Journals (Sweden)

Karolyn J Forget

Full Text Available Prion diseases are unique pathologies in which the infectious particles are prions, a protein aggregate. The prion protein has many particular features, such as spontaneous aggregation, conformation transmission to other native PrP proteins and transmission from an individual to another. Protein aggregation is now frequently associated to many human diseases, for example Alzheimer's disease, Parkinson's disease or type 2 diabetes. A few proteins associated to these conformational diseases are part of a new category of proteins, called prionoids: proteins that share some, but not all, of the characteristics associated with prions. The p53 protein, a transcription factor that plays a major role in cancer, has recently been suggested to be a possible prionoid. The protein has been shown to accumulate in multiple cancer cell types, and its aggregation has also been reproduced in vitro by many independent groups. These observations suggest a role for p53 aggregates in cancer development. This study aims to test the «prion-like» features of p53. Our results show in vitro aggregation of the full length and N-terminally truncated protein (p53C, and penetration of these aggregates into cells. According to our findings, the aggregates enter cells using macropinocytosis, a non-specific pathway of entry. Lastly, we also show that once internalized by the cell, p53C aggregates can co-aggregate with endogenous p53 protein. Together, these findings suggest prion-like characteristics for p53 protein, based on the fact that p53 can spontaneously aggregate, these aggregates can penetrate cells and co-aggregate with cellular p53.

Gain-of-function mutant p53 but not p53 deletion promotes head and neck cancer progression in response to oncogenic K-ras

Science.gov (United States)

Acin, Sergio; Li, Zhongyou; Mejia, Olga; Roop, Dennis R; El-Naggar, Adel K; Caulin, Carlos

2015-01-01

Mutations in p53 occur in over 50% of the human head and neck squamous cell carcinomas (SCCHN). The majority of these mutations result in the expression of mutant forms of p53, rather than deletions in the p53 gene. Some p53 mutants are associated with poor prognosis in SCCHN patients. However, the molecular mechanisms that determine the poor outcome of cancers carrying p53 mutations are unknown. Here, we generated a mouse model for SCCHN and found that activation of the endogenous p53 gain-of-function mutation p53R172H, but not deletion of p53, cooperates with oncogenic K-ras during SCCHN initiation, accelerates oral tumour growth, and promotes progression to carcinoma. Mechanistically, expression profiling of the tumours that developed in these mice and studies using cell lines derived from these tumours determined that mutant p53 induces the expression of genes involved in mitosis, including cyclin B1 and cyclin A, and accelerates entry in mitosis. Additionally, we discovered that this oncogenic function of mutant p53 was dependent on K-ras because the expression of cyclin B1 and cyclin A decreased, and entry in mitosis was delayed, after suppressing K-ras expression in oral tumour cells that express p53R172H. The presence of double-strand breaks in the tumours suggests that oncogene-dependent DNA damage resulting from K-ras activation promotes the oncogenic function of mutant p53. Accordingly, DNA damage induced by doxorubicin also induced increased expression of cyclin B1 and cyclin A in cells that express p53R172H. These findings represent strong in vivo evidence for an oncogenic function of endogenous p53 gain-of-function mutations in SCCHN and provide a mechanistic explanation for the genetic interaction between oncogenic K-ras and mutant p53. PMID:21952947

Glycerol restores the p53 function in human lingual cancer cells bearing mutant p53

International Nuclear Information System (INIS)

Ota, Ichiro; Yane, Katsunari; Yuki, Kazue; Kanata, Hirokazu; Hosoi, Hiroshi; Miyahara, Hiroshi

2001-01-01

Mutations in p53, tumor suppressor gene, have recently been shown to have an impact on the clinical course of several human tumors, including head and neck cancers. The genetic status of the p53 gene has been focused on as the most important candidate among various cancer-related genes for prognosis-predictive assays of cancer therapy. We examined the restoration of radiation- or cisplatin (CDDP)-induced p53-dependent apoptosis in human lingual cancer cells. The results suggest that glycerol is effective in inducing a conformational change of p53 and restoring normal function of mutant p53, leading to enhanced radiosensitivity or chemosensitivity through the induction of apoptosis. We have also represented the same results in vivo as in vitro. Thus, this novel tool for enhancement of radiosensitivity or chemosensitivity in cancer cells bearing m p53 may be applicable for p53-targeted cancer therapy. (author)

p53 Acetylation: Regulation and Consequences

International Nuclear Information System (INIS)

Reed, Sara M.; Quelle, Dawn E.

2014-01-01

Post-translational modifications of p53 are critical in modulating its tumor suppressive functions. Ubiquitylation, for example, plays a major role in dictating p53 stability, subcellular localization and transcriptional vs. non-transcriptional activities. Less is known about p53 acetylation. It has been shown to govern p53 transcriptional activity, selection of growth inhibitory vs. apoptotic gene targets, and biological outcomes in response to diverse cellular insults. Yet recent in vivo evidence from mouse models questions the importance of p53 acetylation (at least at certain sites) as well as canonical p53 functions (cell cycle arrest, senescence and apoptosis) to tumor suppression. This review discusses the cumulative findings regarding p53 acetylation, with a focus on the acetyltransferases that modify p53 and the mechanisms regulating their activity. We also evaluate what is known regarding the influence of other post-translational modifications of p53 on its acetylation, and conclude with the current outlook on how p53 acetylation affects tumor suppression. Due to redundancies in p53 control and growing understanding that individual modifications largely fine-tune p53 activity rather than switch it on or off, many questions still remain about the physiological importance of p53 acetylation to its role in preventing cancer

p53 Acetylation: Regulation and Consequences

Energy Technology Data Exchange (ETDEWEB)

Reed, Sara M. [Department of Pharmacology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Medical Scientist Training Program, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Quelle, Dawn E., E-mail: dawn-quelle@uiowa.edu [Department of Pharmacology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Medical Scientist Training Program, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States); Department of Pathology, The University of Iowa Carver College of Medicine, Iowa City, IA 52242 (United States)

2014-12-23

Post-translational modifications of p53 are critical in modulating its tumor suppressive functions. Ubiquitylation, for example, plays a major role in dictating p53 stability, subcellular localization and transcriptional vs. non-transcriptional activities. Less is known about p53 acetylation. It has been shown to govern p53 transcriptional activity, selection of growth inhibitory vs. apoptotic gene targets, and biological outcomes in response to diverse cellular insults. Yet recent in vivo evidence from mouse models questions the importance of p53 acetylation (at least at certain sites) as well as canonical p53 functions (cell cycle arrest, senescence and apoptosis) to tumor suppression. This review discusses the cumulative findings regarding p53 acetylation, with a focus on the acetyltransferases that modify p53 and the mechanisms regulating their activity. We also evaluate what is known regarding the influence of other post-translational modifications of p53 on its acetylation, and conclude with the current outlook on how p53 acetylation affects tumor suppression. Due to redundancies in p53 control and growing understanding that individual modifications largely fine-tune p53 activity rather than switch it on or off, many questions still remain about the physiological importance of p53 acetylation to its role in preventing cancer.

Tobacco, alcohol, and p53 overexpression in early colorectal neoplasia

International Nuclear Information System (INIS)

Terry, Mary Beth; Neugut, Alfred I; Mansukhani, Mahesh; Waye, Jerome; Harpaz, Noam; Hibshoosh, Hanina

2003-01-01

The p53 tumor suppressor gene is commonly mutated in colorectal cancer. While the effect of p53 mutations on colorectal cancer prognosis has been heavily studied, less is known about how epidemiologic risk factors relate to p53 status, particularly in early colorectal neoplasia prior to clinically invasive colorectal cancer (including adenomas, carcinoma in situ (CIS), and intramucosal carcinoma). We examined p53 status, as measured by protein overexpression, in 157 cases with early colorectal neoplasia selected from three New York City colonoscopy clinics. After collecting paraffin-embedded tissue blocks, immunohistochemistry was performed using an anti-p53 monoclonal mouse IgG 2 a [BP53-12-1] antibody. We analyzed whether p53 status was different for risk factors for colorectal neoplasia relative to a polyp-free control group (n = 508). p53 overexpression was found in 10.3%, 21.7%, and 34.9%, of adenomatous polyps, CIS, and intramucosal cases, respectively. Over 90% of the tumors with p53 overexpression were located in the distal colon and rectum. Heavy cigarette smoking (30+ years) was associated with cases not overexpressing p53 (OR = 1.8, 95% CI = 1.1–2.9) but not with those cases overexpressing p53 (OR = 1.0, 95% CI = 0.4–2.6). Heavy beer consumption (8+ bottles per week) was associated with cases overexpressing p53 (OR = 4.0, 95% CI = 1.3–12.0) but not with cases without p53 overexpression (OR = 1.6, 95% CI = 0.7–3.7). Our findings that p53 overexpression in early colorectal neoplasia may be positively associated with alcohol intake and inversely associated with cigarette smoking are consistent with those of several studies of p53 expression and invasive cancer, and suggest that there may be relationships of smoking and alcohol with p53 early in the adenoma to carcinoma sequence

ER, p53 and MIB-1 are significantly associated with malignant phyllodes tumor.

Science.gov (United States)

Munawer, Nurhayati H; Md Zin, Reena; Md Ali, Siti-Aishah; Muhammad, Rohaizak; Ali, Jasmi; Das, Srijit

2012-01-01

Fibroadenomas (FA) are common while phyllodes tumors (PT) are rare and both tumors are composed of epithelial and stromal components. We evaluated the expression status of ER, Bc12, p53, and MIB-1 protein in these tumors. One hundred and ninety-three tumors comprising of 117 FAs and 76 PTs were examined using immunohistochemistry on tissue microarray. The mean age of patients with FA was 28.5 years while the mean ages of patients with benign, borderline and malignant PTs were 41.7, 48.6 and 42.1 years, respectively. Also all types of PTs were large (>Scm). ER showed a strong nuclear staining in the epithelial component of all tumors while ER/3 immunoreactivity was detected in both the epithelial and stromal components ofF A and PT. ER/β (pcomponent were associated with tumor size. p53 expression was significantly associated with both the epithelial and stromal components of malignant PTs (pcomponent (p=0.000). In addition, MIB-1 was also found to be associated with ER and ER/3 in the stromal component (p=0.000). The expression of p53 with tumor size and histological grade in PT may increase the risk for malignancy.

Urodele p53 tolerates amino acid changes found in p53 variants linked to human cancer

Directory of Open Access Journals (Sweden)

Villiard Éric

2007-09-01

Full Text Available Abstract Background Urodele amphibians like the axolotl are unique among vertebrates in their ability to regenerate and their resistance to develop cancers. It is unknown whether these traits are linked at the molecular level. Results Blocking p53 signaling in axolotls using the p53 inhibitor, pifithrin-α, inhibited limb regeneration and the expression of p53 target genes such as Mdm2 and Gadd45, suggesting a link between tumor suppression and regeneration. To understand this relationship we cloned the p53 gene from axolotl. When comparing its sequence with p53 from other organisms, and more specifically human we observed multiple amino acids changes found in human tumors. Phylogenetic analysis of p53 protein sequences from various species is in general agreement with standard vertebrate phylogeny; however, both mice-like rodents and teleost fishes are fast evolving. This leads to long branch attraction resulting in an artefactual basal emergence of these groups in the phylogenetic tree. It is tempting to assume a correlation between certain life style traits (e.g. lifespan and the evolutionary rate of the corresponding p53 sequences. Functional assays of the axolotl p53 in human or axolotl cells using p53 promoter reporters demonstrated a temperature sensitivity (ts, which was further confirmed by performing colony assays at 37°C. In addition, axolotl p53 was capable of efficient transactivation at the Hmd2 promoter but has moderate activity at the p21 promoter. Endogenous axolotl p53 was activated following UV irradiation (100 j/m2 or treatment with an alkylating agent as measured using serine 15 phosphorylation and the expression of the endogenous p53 target Gadd45. Conclusion Urodele p53 may play a role in regeneration and has evolved to contain multiple amino acid changes predicted to render the human protein defective in tumor suppression. Some of these mutations were probably selected to maintain p53 activity at low temperature. However

Overexpression of 15-lipoxygenase-1 induces growth arrest through phosphorylation of p53 in human colorectal cancer cells.

Science.gov (United States)

Kim, Jong-Sik; Baek, Seung Joon; Bottone, Frank G; Sali, Tina; Eling, Thomas E

2005-09-01

To investigate the function of 15-lipoxygenase-1 (15-LOX-1) in human colorectal cancer, we overexpressed 15-LOX-1 in HCT-116 human colorectal cancer cells. Clones expressing the highest levels of 15-LOX-1 displayed reduced viability compared with the HCT-116-Vector control cells. Further, by cell cycle gene array analyses, the cyclin-dependent kinase inhibitor p21WAF1/CIP1 and MDM2 genes were up-regulated in 15-LOX-1-overexpressing cells. The induction of p21(WAF1/CIP1) and MDM2 were linked to activation of p53 by 15-LOX-1, as there was a dramatic induction of phosphorylated p53 (Ser15) in 15-LOX-1-overesxpressing cells. However, the 15-LOX-1 metabolites 13(S)-hydroxyoctadecadienoic acid and 15(S)-hydroxyeicosatetraenoic acid failed to induce phosphorylation of p53 at Ser15, and the 15-LOX-1 inhibitor PD146176 did not inhibit the phosphorylation of p53 at Ser15 in 15-LOX-1-overexpressing cells. Nonetheless, the growth-inhibitory effects of 15-LOX-1 were p53 dependent, as 15-LOX-1 overexpression had no effect on cell growth in p53 (-/-) HCT-116 cells. Finally, treatment of HCT-116-15-LOX-1 cells with different kinase inhibitors suggested that the effects of 15-LOX-1 on p53 phosphorylation and activation were due to effects on DNA-dependent protein kinase. Collectively, these findings suggest a new mechanism to explain the biological activity of 15-LOX-1, where 15-LOX plays a stoichiometric role in activating a DNA-dependent protein kinase-dependent pathway that leads to p53-dependent growth arrest.

Synergistic effect of p53 on TSA-induced stanniocalcin 1 expression in human nasopharyngeal carcinoma cells, CNE2.

Science.gov (United States)

Ching, L Y; Yeung, Bonnie H Y; Wong, Chris K C

2012-06-01

Human stanniocalcin 1 (STC1) has recently been identified as a putative protein factor involved in cellular apoptosis. The use of histone deacetylase inhibitor (i.e. trichostatin A (TSA)) and doxorubicin (Dox) is one of the common treatment methods to induce apoptosis in human cancer cells. A study on TSA and Dox-mediated apoptosis may shed light on the regulation and function of STC1 in cancer treatment. In this study, TSA and Dox cotreatment in human nasopharyngeal carcinoma cells (CNE2) elicited synergistic effects on STC1 gene expression and cellular apoptosis. An activation of p53 (TP53) transcriptional activity in Dox- or Dox+TSA-treated cells was revealed by the increased expression levels of p53 mRNA/protein as well as p53-driven luciferase activities. To elucidate the possible involvement of p53 in STC1 gene transcription, a vector expressing wild-type or dominant negative (DN) p53 was transiently transfected into the cells. Both STC1 promoter luciferase constructs and chromatin immunoprecipitation assays did not support the direct role of p53 in STC1 gene transactivation. However, the synergistic effects of p53 on the induction of NF-κB phosphorylation and the recruitment of acetylated histone H3 in STC1 promoter were observed in TSA-cotreated cells. The overexpression of exogenous STC1 sensitized apoptosis in Dox-treated cells. Taken together, this study provides data to show the cross talk of NF-κB, p53, and histone protein in the regulation of STC1 expression and function.

Exercise Activates p53 and Negatively Regulates IGF-1 Pathway in Epidermis within a Skin Cancer Model.

Science.gov (United States)

Yu, Miao; King, Brenee; Ewert, Emily; Su, Xiaoyu; Mardiyati, Nur; Zhao, Zhihui; Wang, Weiqun

2016-01-01

Exercise has been previously reported to lower cancer risk through reducing circulating IGF-1 and IGF-1-dependent signaling in a mouse skin cancer model. This study aims to investigate the underlying mechanisms by which exercise may down-regulate the IGF-1 pathway via p53 and p53-related regulators in the skin epidermis. Female SENCAR mice were pair-fed an AIN-93 diet with or without 10-week treadmill exercise at 20 m/min, 60 min/day and 5 days/week. Animals were topically treated with TPA 2 hours before sacrifice and the target proteins in the epidermis were analyzed by both immunohistochemistry and Western blot. Under TPA or vehicle treatment, MDM2 expression was significantly reduced in exercised mice when compared with sedentary control. Meanwhile, p53 was significantly elevated. In addition, p53-transcriptioned proteins, i.e., p21, IGFBP-3, and PTEN, increased in response to exercise. There was a synergy effect between exercise and TPA on the decreased MDM2 and increased p53, but not p53-transcripted proteins. Taken together, exercise appeared to activate p53, resulting in enhanced expression of p21, IGFBP-3, and PTEN that might induce a negative regulation of IGF-1 pathway and thus contribute to the observed cancer prevention by exercise in this skin cancer model.

MDM2 SNP309 promoter polymorphism and p53 mutations in urinary bladder carcinoma stage T1

Directory of Open Access Journals (Sweden)

Olsson Hans

2013-01-01

Full Text Available Abstract Background Urinary bladder carcinoma stage T1 is an unpredictable disease that in some cases has a good prognosis with only local or no recurrence, but in others can appear as a more aggressive tumor with progression to more advanced stages. The aim here was to investigate stage T1 tumors regarding MDM2 promoter SNP309 polymorphism, mutations in the p53 gene, and expression of p53 and p16 measured by immunohistochemistry, and subsequently relate these changes to tumor recurrence and progression. We examined a cohort of patients with primary stage T1 urothelial carcinoma of the bladder and their tumors. Methods After re-evaluation of the original slides and exclusions, the study population comprised 141 patients, all with primary stage T1 urothelial carcinoma of the bladder. The hospital records were screened for clinical parameters and information concerning presence of histologically proven recurrence and progression. The paraffin-embedded tumor material was evaluated by immunohistochemistry. Any mutations found in the p53 gene were studied by single-strand conformation analysis and Sanger sequencing. The MDM2 SNP309 polymorphism was investigated by pyrosequencing. Multivariate analyses concerning association with prognosis were performed, and Kaplan-Meier analysis was conducted for a combination of changes and time to progression. Results Of the 141 patients, 82 had at least one MDM2 SNP309 G allele, and 53 had a mutation in the p53 gene, but neither of those anomalies was associated with a worse prognosis. A mutation in the p53 gene was associated with immunohistochemically visualized p53 protein expression at a cut-off value of 50%. In the group with p53 mutation Kaplan-Meier analysis showed higher rate of progression and shorter time to progression in patients with immunohistochemically abnormal p16 expression compared to them with normal p16 expression (p = 0.038. Conclusions MDM2 SNP309 promoter polymorphism and mutations in

p53-dependent and p53-independent anticancer activity of a new indole derivative in human osteosarcoma cells

Energy Technology Data Exchange (ETDEWEB)

Cappadone, C., E-mail: concettina.cappadone@unibo.it [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Stefanelli, C. [Department for Life Quality Studies, University of Bologna, Rimini Campus, Rimini (Italy); Malucelli, E. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Zini, M. [Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna (Italy); Onofrillo, C. [Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna (Italy); Locatelli, A.; Rambaldi, M.; Sargenti, A. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Merolle, L. [ELETTRA–Sincrotrone Trieste S.C.p.A., Trieste (Italy); Farruggia, G. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); National Institute of Biostructures and Biosystems, Roma (Italy); Graziadio, A. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); Montanaro, L. [Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna (Italy); Iotti, S. [Department of Pharmacy and Biotechnology, University of Bologna, Bologna (Italy); National Institute of Biostructures and Biosystems, Roma (Italy)

2015-11-13

Osteosarcoma (OS) is the most common primary malignant tumor of bone, occurring most frequently in children and adolescents. The mechanism of formation and development of OS have been studied for a long time. Tumor suppressor pathway governed by p53 gene are known to be involved in the pathogenesis of osteosarcoma. Moreover, loss of wild-type p53 activity is thought to be a major predictor of failure to respond to chemotherapy in various human cancers. In previous studies, we described the activity of a new indole derivative, NSC743420, belonging to the tubulin inhibitors family, capable to induce apoptosis and arrest of the cell cycle in the G2/M phase of various cancer cell lines. However, this molecule has never been tested on OS cell line. Here we address the activity of NSC743420 by examine whether differences in the p53 status could influence its effects on cell proliferation and death of OS cells. In particular, we compared the effect of the tested molecule on p53-wild type and p53-silenced U2OS cells, and on SaOS2 cell line, which is null for p53. Our results demonstrated that NSC743420 reduces OS cell proliferation by p53-dependent and p53-independent mechanisms. In particular, the molecule induces proliferative arrest that culminate to apoptosis in SaOS2 p53-null cells, while it brings a cytostatic and differentiating effect in U2OS cells, characterized by the cell cycle arrest in G0/G1 phase and increased alkaline phosphatase activity. - Highlights: • The indole derivative NSC743420 induces antitumor effects on osteosarcoma cells. • p53 status could drive the activity of antitumor agents on osteosarcoma cells. • NSC743420 induces cytostatic and differentiating effects on U2OS cells. • NSC743420 causes apoptosis on p53-null SaOS2 cells.

p53-dependent and p53-independent anticancer activity of a new indole derivative in human osteosarcoma cells

International Nuclear Information System (INIS)

Cappadone, C.; Stefanelli, C.; Malucelli, E.; Zini, M.; Onofrillo, C.; Locatelli, A.; Rambaldi, M.; Sargenti, A.; Merolle, L.; Farruggia, G.; Graziadio, A.; Montanaro, L.; Iotti, S.

2015-01-01

Osteosarcoma (OS) is the most common primary malignant tumor of bone, occurring most frequently in children and adolescents. The mechanism of formation and development of OS have been studied for a long time. Tumor suppressor pathway governed by p53 gene are known to be involved in the pathogenesis of osteosarcoma. Moreover, loss of wild-type p53 activity is thought to be a major predictor of failure to respond to chemotherapy in various human cancers. In previous studies, we described the activity of a new indole derivative, NSC743420, belonging to the tubulin inhibitors family, capable to induce apoptosis and arrest of the cell cycle in the G2/M phase of various cancer cell lines. However, this molecule has never been tested on OS cell line. Here we address the activity of NSC743420 by examine whether differences in the p53 status could influence its effects on cell proliferation and death of OS cells. In particular, we compared the effect of the tested molecule on p53-wild type and p53-silenced U2OS cells, and on SaOS2 cell line, which is null for p53. Our results demonstrated that NSC743420 reduces OS cell proliferation by p53-dependent and p53-independent mechanisms. In particular, the molecule induces proliferative arrest that culminate to apoptosis in SaOS2 p53-null cells, while it brings a cytostatic and differentiating effect in U2OS cells, characterized by the cell cycle arrest in G0/G1 phase and increased alkaline phosphatase activity. - Highlights: • The indole derivative NSC743420 induces antitumor effects on osteosarcoma cells. • p53 status could drive the activity of antitumor agents on osteosarcoma cells. • NSC743420 induces cytostatic and differentiating effects on U2OS cells. • NSC743420 causes apoptosis on p53-null SaOS2 cells.

Differential sensitivity of p53+ and p53- cells to caffeine-induced radiosensitization and override of G2 delay

International Nuclear Information System (INIS)

Powell, S.N.; DeFrank, J.S.; Connell, P.; Eogan, M.; Preffer, F.; Dombkowski, D.; Tang, W.; Friend, S.H.

1995-01-01

Purpose: Most drug discovery efforts have focused on finding new DNA damaging agents to kill tumor cells preferentially. An alternative approach is to find ways to increase tumor specific killing by modifying tumor specific responses to that damage. We asked whether cells lacking the G1/S arrest in response to X-rays are more sensitive to X-ray damage when treated with agents that override G2/M arrest. Materials and Methods: Mouse embryonic fibroblasts genetically matched to be (+/+) or (-/-) p53 and rat embryonic fibroblasts (REF) made (+) or (-) for wild-type p53 function by transfection were irradiated with and without caffeine, a known checkpoint inhibitor. Caffeine treatment was maintained for 24 hours from 1 hour prior to irradiation. Cell survival following ionizing radiation was measured by clonogenic assay. For cell-cycle analysis, cells were in exponential asynchronous growth at the time of irradiation. The proportion of cells in G1, S and G2/M phases of the cell cycle were recorded immediately before and following irradiation and subsequently at 3,6,9,12,24 and 48 hours following irradiation. Results: Caffeine was found to cause radiosensitzation at low dose (0.5mM) in (-/-) cells but not in (+/+) cells. The sensitization enhancement ratio (SER) was 1.45 at 0.1 survival and 1.56 at 0.01 survival. At this dose of caffeine, this SER reflected therapeutic gain as there was no detectable effect on (+/+) cells. At 1mM caffeine, sensitization of (-/-) cells was 1.77, but (+/+) cells now also showed sensitization (SER=1.25). In (-/-) cells at 0.1mM caffeine the SER was 1.5 at 0.01 survival. The transfected REF cells (functionally null for p53) also exhibited caffeine-induced radiosensitization at both 0.5 and 2mM caffeine with a SER 1.45 for 2mM at 0.1 survival. No significant sensitization could be demonstrated for REF cells at the same doses of caffeine. The REF cells, with wild-type p53, transfected with pCMVneo alone showed no change in radiosensitivity or

PcFKH1, a novel regulatory factor from the forkhead family, controls the biosynthesis of penicillin in Penicillium chrysogenum.

Science.gov (United States)

Domínguez-Santos, Rebeca; García-Estrada, Carlos; Kosalková, Katarina; Prieto, Carlos; Santamarta, Irene; Martín, Juan-Francisco

2015-08-01

Penicillin biosynthesis in Penicillium chrysogenum (re-identified as Penicillium rubens) is a good example of a biological process subjected to complex global regulatory networks and serves as a model to study fungal secondary metabolism. The winged-helix family of transcription factors recently described, which includes the forkhead type of proteins, is a key type of regulatory proteins involved in this process. In yeasts and humans, forkhead transcription factors are involved in different processes (cell cycle regulation, cell death control, pre-mRNA processing and morphogenesis); one member of this family of proteins has been identified in the P. chrysogenum genome (Pc18g00430). In this work, we have characterized this novel transcription factor (named PcFKH1) by generating knock-down mutants and overexpression strains. Results clearly indicate that PcFKH1 positively controls antibiotic biosynthesis through the specific interaction with the promoter region of the penDE gene, thus regulating penDE mRNA levels. PcFKH1 also binds to the pcbC promoter, but with low affinity. In addition, it also controls other ancillary genes of the penicillin biosynthetic process, such as phlA (encoding phenylacetyl CoA ligase) and ppt (encoding phosphopantetheinyl transferase). PcFKH1 also plays a role in conidiation and spore pigmentation, but it does not seem to be involved in hyphal morphology or cell division in the improved laboratory reference strain Wisconsin 54-1255. A genome-wide analysis of processes putatively coregulated by PcFKH1 and PcRFX1 (another winged-helix transcription factor) in P. chrysogenum provided evidence of the global effect of these transcription factors in P. chrysogenum metabolism. Copyright © 2015 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

MSN2 and MSN4 link calorie restriction and TOR to sirtuin-mediated lifespan extension in Saccharomyces cerevisiae.

Directory of Open Access Journals (Sweden)

Oliver Medvedik

2007-10-01

Full Text Available Calorie restriction (CR robustly extends the lifespan of numerous species. In the yeast Saccharomyces cerevisiae, CR has been proposed to extend lifespan by boosting the activity of sirtuin deacetylases, thereby suppressing the formation of toxic repetitive ribosomal DNA (rDNA circles. An alternative theory is that CR works by suppressing the TOR (target of rapamycin signaling pathway, which extends lifespan via mechanisms that are unknown but thought to be independent of sirtuins. Here we show that TOR inhibition extends lifespan by the same mechanism as CR: by increasing Sir2p activity and stabilizing the rDNA locus. Further, we show that rDNA stabilization and lifespan extension by both CR and TOR signaling is due to the relocalization of the transcription factors Msn2p and Msn4p from the cytoplasm to the nucleus, where they increase expression of the nicotinamidase gene PNC1. These findings suggest that TOR and sirtuins may be part of the same longevity pathway in higher organisms, and that they may promote genomic stability during aging.

The nucleolar SUMO-specific protease SMT3IP1/SENP3 attenuates Mdm2-mediated p53 ubiquitination and degradation

Energy Technology Data Exchange (ETDEWEB)

Nishida, Tamotsu, E-mail: nishida@gene.mie-u.ac.jp [Department of Human Functional Genomics, Life Science Research Center, Mie University, 1577 Kurima-machiya, Tsu 514-8507 (Japan); Yamada, Yoshiji [Department of Human Functional Genomics, Life Science Research Center, Mie University, 1577 Kurima-machiya, Tsu 514-8507 (Japan)

2011-03-11

Research highlights: {yields} SMT3IP1 interacts with p53 and Mdm2, and desumoylates both proteins. {yields} SMT3IP1 competes with p53 for binding to the central acidic domain of Mdm2. {yields} SMT3IP1 binding to Mdm2 inhibits Mdm2-mediated p53 ubiquitination and degradation. {yields} We postulate that SMT3IP1 acts as a new regulator of the p53-Mdm2 pathway. -- Abstract: SUMO (small ubiquitin-like modifier) modification plays multiple roles in several cellular processes. Sumoylation is reversibly regulated by SUMO-specific proteases. SUMO-specific proteases have recently been implicated in cell proliferation and early embryogenesis, but the underlying mechanisms remain unknown. Here, we show that a nucleolar SUMO-specific protease, SMT3IP1/SENP3, controls the p53-Mdm2 pathway. We found that SMT3IP1 interacts with p53 and Mdm2, and desumoylates both proteins. Overexpression of SMT3IP1 in cells resulted in the accumulation of Mdm2 in the nucleolus and increased stability of the p53 protein. In addition, SMT3IP1 bound to the acidic domain of Mdm2, which also mediates the p53 interaction, and competed with p53 for binding. Increasing expression of SMT3IP1 suppressed Mdm2-mediated p53 ubiquitination and subsequent proteasomal degradation. Interestingly, the desumoylation activity of SMT3IP1 was not necessary for p53 stabilization. These results suggest that SMT3IP1 is a new regulator of the p53-Mdm2 pathway.

The nucleolar SUMO-specific protease SMT3IP1/SENP3 attenuates Mdm2-mediated p53 ubiquitination and degradation

International Nuclear Information System (INIS)

Nishida, Tamotsu; Yamada, Yoshiji

2011-01-01

Research highlights: → SMT3IP1 interacts with p53 and Mdm2, and desumoylates both proteins. → SMT3IP1 competes with p53 for binding to the central acidic domain of Mdm2. → SMT3IP1 binding to Mdm2 inhibits Mdm2-mediated p53 ubiquitination and degradation. → We postulate that SMT3IP1 acts as a new regulator of the p53-Mdm2 pathway. -- Abstract: SUMO (small ubiquitin-like modifier) modification plays multiple roles in several cellular processes. Sumoylation is reversibly regulated by SUMO-specific proteases. SUMO-specific proteases have recently been implicated in cell proliferation and early embryogenesis, but the underlying mechanisms remain unknown. Here, we show that a nucleolar SUMO-specific protease, SMT3IP1/SENP3, controls the p53-Mdm2 pathway. We found that SMT3IP1 interacts with p53 and Mdm2, and desumoylates both proteins. Overexpression of SMT3IP1 in cells resulted in the accumulation of Mdm2 in the nucleolus and increased stability of the p53 protein. In addition, SMT3IP1 bound to the acidic domain of Mdm2, which also mediates the p53 interaction, and competed with p53 for binding. Increasing expression of SMT3IP1 suppressed Mdm2-mediated p53 ubiquitination and subsequent proteasomal degradation. Interestingly, the desumoylation activity of SMT3IP1 was not necessary for p53 stabilization. These results suggest that SMT3IP1 is a new regulator of the p53-Mdm2 pathway.

Aggregation-primed molten globule conformers of the p53 core domain provide potential tools for studying p53C aggregation in cancer.

Science.gov (United States)

Pedrote, Murilo M; de Oliveira, Guilherme A P; Felix, Adriani L; Mota, Michelle F; Marques, Mayra de A; Soares, Iaci N; Iqbal, Anwar; Norberto, Douglas R; Gomes, Andre M O; Gratton, Enrico; Cino, Elio A; Silva, Jerson L

2018-05-31

The functionality of the tumor suppressor p53 is altered in more than 50% of human cancers, and many individuals with cancer exhibit amyloid-like buildups of aggregated p53. An understanding of what triggers the pathogenic amyloid conversion of p53 is required for the further development of cancer therapies. Here, perturbation of the p53 core domain (p53C) with sub-denaturing concentrations of guanidine hydrochloride and high hydrostatic pressure revealed native-like molten globule (MG) states, a subset of which were highly prone to amyloidogenic aggregation. We found that MG conformers of p53C, likely representing population-weighted averages of multiple states, have different volumetric properties, as determined by pressure perturbation and size-exclusion chromatography. We also found that they bind the fluorescent dye 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) and have a native-like tertiary structure that occludes the single Trp residue in p53. Fluorescence experiments revealed conformational changes of the single Trp and Tyr residues before p53 unfolding and the presence of MG conformers, some of which were highly prone to aggregation. P53C exhibited marginal unfolding cooperativity, which could be modulated from unfolding to aggregation pathways with chemical or physical forces. We conclude that trapping amyloid precursor states in solution is a promising approach for understanding p53 aggregation in cancer. Our findings support the use of single-Trp fluorescence as a probe for evaluating p53 stability, effects of mutations, and the efficacy of therapeutics designed to stabilize p53. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Tumor hypoxia, p53, and prognosis in cervical cancers

International Nuclear Information System (INIS)

Haensgen, Gabriele; Krause, Ulf; Becker, Axel; Stadler, Peter; Lautenschlaeger, Christine; Wohlrab, Wolfgang; Rath, Friedrich W.; Molls, Michael; Dunst, Juergen

2001-01-01

=0.01). Sixty of the 70 tumors showed positive immunohistologic staining for p53 protein (transformed p53=tp53), and 10/70 were negative (wild-type p53=wtp53); p53 expression had no significant impact on survival (50% for tp53 vs. 79% for wtp53, p=0.11). FIGO stage and anemia had no impact on p53 expression. Forty-nine of 70 tumors were hypoxic (HF5+), and 21 showed no hypoxia (HF5-). Hypoxic carcinomas were more frequently positive for p53 as compared to nonhypoxic tumors (27% vs. 13%, p=0.011) and showed a trend toward a lower survival (48% vs. 70%, p = 0.07). In a further multivariate analysis, the impact of a combination of p53 expression and hypoxia on survival was examined. After adjusting for FIGO stage and pretreatment anemia, patients with wtp53 tumors had the best prognosis (3-year survival 79%) followed by tp53-HF5(-) patients (57%), and the most unfavorable prognosis was observed for tp53-HF5(+) patients (47%). The DNA index was higher in tp53 carcinomas compared to wtp53 tumors, 1.97±0.4 vs. 1.67±0.1, p=0.05. The highest DNA index was found in hypoxic tumors with transformed p53 (2.2±3.1). Conclusions: Advanced stage and pretreatment hemoglobin level are independent prognostic factors in cervical carcinomas. The immunohistologic detection of (a functionally inactive) p53 and the presence of hypoxia had no prognostic impact, if analyzed as single parameters. However, the combination of both parameters was able to discriminate different prognostic subgroups. Moreover, hypoxic cancers were more often immunohistologically positive for tp53 protein and had a higher DNA index with the highest DNA index in tumors with both hypoxia and tp53 protein expression. These findings in summary support the theory that the tumor's microenvironment may influence the biologic behavior via hypoxia

Synergistic induction of profibrotic PAI-1 by TGF-β and radiation depends on p53

International Nuclear Information System (INIS)

Niemantsverdriet, Maarten; Jong, Edwin de; Langendijk, Johannes A.; Kampinga, Harm H.; Coppes, Robert P.

2010-01-01

Radiation-induced fibrosis is a severe side effect of radiotherapy. TGF-β and radiation synergistically induce expression of the profibrotic PAI-1 gene and this cooperation potentially involves p53. Here, we demonstrate that p53 is both indispensable and sufficient for the radiation effect inducing synergistic activation of PAI-1 by radiation and TGF-β.

Identification and analysis of evolutionary selection pressures acting at the molecular level in five forkhead subfamilies.

Science.gov (United States)

Fetterman, Christina D; Rannala, Bruce; Walter, Michael A

2008-09-24

Members of the forkhead gene family act as transcription regulators in biological processes including development and metabolism. The evolution of forkhead genes has not been widely examined and selection pressures at the molecular level influencing subfamily evolution and differentiation have not been explored. Here, in silico methods were used to examine selection pressures acting on the coding sequence of five multi-species FOX protein subfamily clusters; FoxA, FoxD, FoxI, FoxO and FoxP. Application of site models, which estimate overall selection pressures on individual codons throughout the phylogeny, showed that the amino acid changes observed were either neutral or under negative selection. Branch-site models, which allow estimated selection pressures along specified lineages to vary as compared to the remaining phylogeny, identified positive selection along branches leading to the FoxA3 and Protostomia clades in the FoxA cluster and the branch leading to the FoxO3 clade in the FoxO cluster. Residues that may differentiate paralogs were identified in the FoxA and FoxO clusters and residues that differentiate orthologs were identified in the FoxA cluster. Neutral amino acid changes were identified in the forkhead domain of the FoxA, FoxD and FoxP clusters while positive selection was identified in the forkhead domain of the Protostomia lineage of the FoxA cluster. A series of residues under strong negative selection adjacent to the N- and C-termini of the forkhead domain were identified in all clusters analyzed suggesting a new method for refinement of domain boundaries. Extrapolation of domains among cluster members in conjunction with selection pressure information allowed prediction of residue function in the FoxA, FoxO and FoxP clusters and exclusion of known domain function in residues of the FoxA and FoxI clusters. Consideration of selection pressures observed in conjunction with known functional information allowed prediction of residue function and

S-phase checkpoint elements of the E2F-1 family increase radiosensitivity in fibrosarcoma cells lacking p53

International Nuclear Information System (INIS)

Bodis, Stephan; Pruschy, Martin; Wirbelauer, Christiane; Glanzmann, Christoph; Krek, Wilhelm

1997-01-01

Purpose: Correct advance of cells through the S-phase of the mammalian cell cycle depends on the timely controlled activity of the E2F-1 transcription factor by cyclin A-cdk2. We are studying the reproductive integrity and radiosensitation of isogenic mouse fibrosarcoma cells, differing only in their p53 status, after expression of E2F-1 wildtype (wt) and specific E2F-1 mutants (mt) lacking the cyclin-A-binding domain. In this tumor model system only p53 wild-type expressing tumor cells are sensitive to ionizing radiation in vitro and in vivo. Material and Methods: Either wild-type p53 or genetically engineered p53 'null' mouse embryo fibroblasts were transfected with the oncogenes E1A and ras. These otherwise isogenic fibrosarcoma cells, with a malignant phenotype and tumorigenic in nude mice, were transfected with retroviruses containing either E2F-1 wild-type or specific E2F-1 mutants lacking the cyclin-A binding domain. Reproductive integrity after E2F-1 transfection with or without ionizing radiation (RT) was tested using the clonogenic assay. Tumor cell morphology of treated cells is analyzed for cell death mechanism. Results: E2F-1 wild-type expression in fibrosarcoma cells induced a clear p53 dependent cell death. While clonogenic survival of p53 'null' tumor cells was only slightly reduced with the expression of E2F-1 wild type (survival fraction of 0.5), the clonogenic survival of p53 wild-type fibrosarcoma tumor cells was reduced by at least one logarithm (survival fraction of 0.05). However, expression of the specific E2F-1 mutant lacking the cyclin-A binding domain reduced clonogenic survival in both the p53 'null' and the p53 wild-type fibrosarcoma cells by at least 2 logarithms (survival fraction 0.01 for p53 'null' and 0.002 for p53 wild-type). The mean values of the survival fractions after 2 and 5 Gy radiation alone in p53 'null' fibrosarcoma cells (SF 2 and SF 5) were SF 2 0.7, SF 5 = 0.15, respectively. The combination of ionizing RT in the p53

Analysis of p53- immunoreactivity in astrocytic brain tumors

Directory of Open Access Journals (Sweden)

Shinkarenko T.V.

2016-12-01

Full Text Available P53 is an antioncogene with the frequently occured mutations in human tumor cells, leading to corresponding protein overexpression which can be detected by immunohistochemistry. Researches dedicated to the investigation of possibilities of using this technique gave controversial results. The authors investigated features of p53 protein expression in astrocytic brain tumors with different degrees of malignancy. Analyzed the relationship of the expression level of p53 by tumor cells with clinical parameters and Ki-67 proliferation index (PI as well. Tissues were collected from 52 cases with diagnosed astrocytic brain tumors. The sections were immunohistochemically stained with p53 and Ki-67. For each marker, 1000 tumor cells were counted and the ratio of positive tumor cells was calculated using software package ImageJ 1,47v. In normal brain tissue p53- expression was not identified. p53-immunoreactive tumor cells were detected in 25% (1/4 pilocytic astrocytomas, 33.3% (2/6 of diffuse astrocytomas, 53.8% (7/13 anaplastic astrocytomas, 58.6% (17/29 glioblastomas. A high proportion of p53-immunoreactive cells (> 30% was observed only in glioblastomas. The level of p53-imunoreactivity was not related to the age, gender and Grade WHO (p> 0,05. Spearman correlation coefficient between the relative quantity of ki-67- and p53-immunoreactive nuclei showed weak direct correlation (0.023, but the one was not statistically significant (p> 0,05. The level of p53-imunoreactivity is not dependent from age and sex of patients, Grade (WHO and proliferative activity (p>0,05 but the high level of p53-immunoreactive cells (>30% is found in glioblastoma specimens only, that may be due to the accumulation of mutations in DNA of tumor cells. There is insignificant weak relationship between relative quantities of ki-67- and p53-immunoreactive tumor cells (p>0,05.

The p53-dependent radioadaptive response

Science.gov (United States)

Ohnishi, Takeo

We already reported that conditioning exposures at low doses, or at low dose-rates, lowered radiation-induced p53-dependent apoptosis in cultured cells in vitro and in the spleens of mice in vivo. In this study, the aim was to characterize the p53-dependent radioadaptive response at the molecular level. We used wild-type (wt) p53 and mutated (m) p53 containing cells derived from the human lung cancer H1299 cell line, which is p53-null. Cellular radiation sensitivities were determined with a colony-forming assay. The accumulation of p53, Hdm2, and iNOS was analyzed with Western blotting. The quantification of chromosomal aberrations was estimated by scoring dicentrics per cell. In wtp53 cells, it was demonstrated that the lack of p53 accumulation was coupled with the activation of Hdm2 after low dose irradiation (0.02 Gy). Although NO radicals were only minimally induced in wtp53 cells irradiated with a challenging irradiation (6 Gy) alone, NO radicals were seen to increase about 2-4 fold after challenging irradiation following a priming irradiation (0.02 Gy). Under similar irradiation conditions with a priming and challenging irradiation in wtp53 cells, induction of radioresistance and a depression of chromosomal aberrations were observed only in the absence of Pifithrin-α (a p53 inhibitor), RITA or Nutlin-3 (p53-Hdm2 interaction inhibitors), aminoguanidine (an iNOS inhibitor) and c-PTIO (an NO radical scavenger). On the other hand, in p53 dysfunctional cells, a radioadaptive response was not observed in the presence or absence of those inhibitors. Moreover, radioresistance developed when wtp53 cells were treated with ISDN (an NO generating agent) alone. These findings suggest that NO radicals are an initiator of the radioadaptive response acting through the activation of Hdm2 and the depression of p53 accumulations.

The adenovirus oncoprotein E1a stimulates binding of transcription factor ETF to transcriptionally activate the p53 gene.

Science.gov (United States)

Hale, T K; Braithwaite, A W

1999-08-20

Expression of the tumor suppressor protein p53 plays an important role in regulating the cellular response to DNA damage. During adenovirus infection, levels of p53 protein also increase. It has been shown that this increase is due not only to increased stability of the p53 protein but to the transcriptional activation of the p53 gene during infection. We demonstrate here that the E1a proteins of adenovirus are responsible for activating the mouse p53 gene and that both major E1a proteins, 243R and 289R, are required for complete activation. E1a brings about the binding of two cellular transcription factors to the mouse p53 promoter. One of these, ETF, binds to three upstream sites in the p53 promoter and one downstream site, whereas E2F binds to one upstream site in the presence of E1a. Our studies indicate that E2F binding is not essential for activation of the p53 promoter but that ETF is. Our data indicate the ETF site located downstream of the start site of transcription is the key site in conferring E1a responsiveness on the p53 promoter.

Fox (forkhead) genes are involved in the dorso-ventral patterning of the Xenopus mesoderm.

Science.gov (United States)

El-Hodiri, H; Bhatia-Dey, N; Kenyon, K; Ault, K; Dirksen, M; Jamrich, M

2001-01-01

Fox (forkhead/winged helix) genes encode a family of transcription factors that are involved in embryonic pattern formation, regulation of tissue specific gene expression and tumorigenesis. Several of them are transcribed during Xenopus embryogenesis and are important for the patterning of ectoderm, mesoderm and endoderm. We have isolated three forkhead genes that are activated during gastrulation and play an important role in the dorso-ventral patterning of the mesoderm. XFKH1 (FoxA4b), the first vertebrate forkhead gene to be implicated in embryonic pattern formation, is expressed in the Spemann-Mangold organizer region and later in the embryonic notochord. XFKH7, the Xenopus orthologue of the murine Mfh1(Foxc2), is expressed in the presomitic mesoderm, but not in the notochord or lateral plate mesoderm. Finally, XFD-13'(FoxF1b)1 is expressed in the lateral plate mesoderm, but not in the notochord or presomitic mesoderm. Expression pattern and functional experiments indicate that these three forkhead genes are involved in the dorso-ventral patterning of the mesoderm.

RITA can induce cell death in p53-defective cells independently of p53 function via activation of JNK/SAPK and p38.

Science.gov (United States)

Weilbacher, A; Gutekunst, M; Oren, M; Aulitzky, W E; van der Kuip, H

2014-07-10

Significant advances have been made in the development of small molecules blocking the p53/MDM2 interaction. The Mdm2 inhibitor Nutlin-3 is restricted to tumors carrying wtp53. In contrast, RITA, a compound that binds p53, has recently been shown also to restore transcriptional functions of mtp53. As more than 50% of solid tumors carry p53 mutations, RITA promises to be a more effective therapeutic strategy than Nutlin-3. We investigated effects of RITA on apoptosis, cell cycle and induction of 45 p53 target genes in a panel of 14 cell lines from different tumor entities with different p53 status as well as primary lymphocytes and fibroblasts. Nine cell strains expressed wtp53, four harbored mtp53, and three were characterized by the loss of p53 protein. A significant induction of cell death upon RITA was observed in 7 of 16 cell lines. The nonmalignant cells in our panel were substantially less sensitive. We found that in contrast to Nultin-3, RITA is capable to induce cell death not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells. Importantly, whereas p53 has a central role for RITA-mediated effects in wtp53 cells, neither p53 nor p63 or p73 were essential for the RITA response in mtp53 or p53-null cells in our panel demonstrating that besides the known p53-dependent action of RITA in wtp53 cells, RITA can induce cell death also independently of p53 in cells harboring defective p53. We identified an important role of both p38 and JNK/SAPK for sensitivity to RITA in these cells leading to a typical caspase- and BAX/BAK-dependent mitochondrial apoptosis. In conclusion, our data demonstrate that RITA can induce apoptosis through p38 and JNK/SAPK not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells, making RITA an interesting tumor-selective drug.

Regulation of p53 tetramerization and nuclear export by ARC.

Science.gov (United States)

Foo, Roger S-Y; Nam, Young-Jae; Ostreicher, Marc Jason; Metzl, Mark D; Whelan, Russell S; Peng, Chang-Fu; Ashton, Anthony W; Fu, Weimin; Mani, Kartik; Chin, Suet-Feung; Provenzano, Elena; Ellis, Ian; Figg, Nichola; Pinder, Sarah; Bennett, Martin R; Caldas, Carlos; Kitsis, Richard N

2007-12-26

Inactivation of the transcription factor p53 is central to carcinogenesis. Yet only approximately one-half of cancers have p53 loss-of-function mutations. Here, we demonstrate a mechanism for p53 inactivation by apoptosis repressor with caspase recruitment domain (ARC), a protein induced in multiple cancer cells. The direct binding in the nucleus of ARC to the p53 tetramerization domain inhibits p53 tetramerization. This exposes a nuclear export signal in p53, triggering Crm1-dependent relocation of p53 to the cytoplasm. Knockdown of endogenous ARC in breast cancer cells results in spontaneous tetramerization of endogenous p53, accumulation of p53 in the nucleus, and activation of endogenous p53 target genes. In primary human breast cancers with nuclear ARC, p53 is almost always WT. Conversely, nearly all breast cancers with mutant p53 lack nuclear ARC. We conclude that nuclear ARC is induced in cancer cells and negatively regulates p53.

Molecular evolutionary patterns of NAD+/Sirtuin aging signaling pathway across taxa.

Directory of Open Access Journals (Sweden)

Uma Gaur

Full Text Available A deeper understanding of the conserved molecular mechanisms in different taxa have been made possible only because of the evolutionary conservation of crucial signaling pathways. In the present study, we explored the molecular evolutionary pattern of selection signatures in 51 species for 10 genes which are important components of NAD+/Sirtuin pathway and have already been directly linked to lifespan extension in worms and mice. Selection pressure analysis using PAML program revealed that MRPS5 and PPARGC1A were under significant constraints because of their functional significance. FOXO3a also displayed strong purifying selection. All three sirtuins, which were SIRT1, SIRT2 and SIRT6, displayed a great degree of conservation between taxa, which is consistent with the previous report. A significant evolutionary constraint is seen on the anti-oxidant gene, SOD3. As expected, TP53 gene was under significant selection pressure in mammals, owing to its major role in tumor progression. Poly-ADP-ribose polymerase (PARP genes displayed the most sites under positive selection. Further 3D structural analysis of PARP1 and PARP2 protein revealed that some of these positively selected sites caused a change in the electrostatic potential of the protein structure, which may allow a change in its interaction with other proteins and molecules ultimately leading to difference in the function. Although the functional significance of the positively selected sites could not be established in the variants databases, yet it will be interesting to see if these sites actually affect the function of PARP1 and PARP2.

Clinical significance of altered nm23-H1, EGFR, RB and p53 expression in bilharzial bladder cancer

International Nuclear Information System (INIS)

Khaled, Hussein M; Bahnassy, Abeer A; Raafat, Amira A; Zekri, Abdel-Rahman N; Madboul, Maha S; Mokhtar, Nadia M

2009-01-01

Clinical characterization of bladder carcinomas is still inadequate using the standard clinico-pathological prognostic markers. We assessed the correlation between nm23-H1, Rb, EGFR and p53 in relation to the clinical outcome of patients with muscle invasive bilharzial bladder cancer (MI-BBC). nm23-H1, Rb, EGFR and p53 expression was assessed in 59 MI-BBC patients using immunohistochemistry and reverse transcription (RT-PCR) and was correlated to the standard clinico-pathological prognostic factors, patient's outcome and the overall survival (OS) rate. Overexpression of EGFR and p53 proteins was detected in 66.1% and 35.6%; respectively. Loss of nm23-H1and Rb proteins was detected in 42.4% and 57.6%; respectively. Increased EGFR and loss of nm23-H1 RNA were detected in 61.5% and 36.5%; respectively. There was a statistically significant correlation between p53 and EGFR overexpression (p < 0.0001), nm23 loss (protein and RNA), lymph node status (p < 0.0001); between the incidence of local recurrence and EGFR RNA overexpression (p= 0.003) as well as between the incidence of metastasis and altered Rb expression (p = 0.026), p53 overexpression (p < 0.0001) and mutation (p = 0.04). Advanced disease stage correlated significantly with increased EGFR (protein and RNA) (p = 0.003 & 0.01), reduced nm23-H1 RNA (p = 0.02), altered Rb (p = 0.023), and p53 overexpression (p = 0.004). OS rates correlated significantly, in univariate analysis, with p53 overexpression (p = 0.011), increased EGFR (protein and RNA, p = 0.034&0.031), nm23-H1 RNA loss (p = 0.021) and aberrations of ≥ 2 genes. However, multivariate analysis showed that only high EGFR overexpression, metastatic recurrence, high tumor grade and the combination of ≥ 2 affected markers were independent prognostic factors. nm23-H1, EGFR and p53 could be used as prognostic biomarkers in MI-BBC patients. In addition to the standard pathological prognostic factors, a combination of these markers (≥ 2) has

S100A4 interacts with p53 in the nucleus and promotes p53 degradation.

Science.gov (United States)

Orre, L M; Panizza, E; Kaminskyy, V O; Vernet, E; Gräslund, T; Zhivotovsky, B; Lehtiö, J

2013-12-05

S100A4 is a small calcium-binding protein that is commonly overexpressed in a range of different tumor types, and it is widely accepted that S100A4 has an important role in the process of cancer metastasis. In vitro binding assays has shown that S100A4 interacts with the tumor suppressor protein p53, indicating that S100A4 may have additional roles in tumor development. In the present study, we show that endogenous S100A4 and p53 interact in complex samples, and that the interaction increases after inhibition of MDM2-dependent p53 degradation using Nutlin-3A. Further, using proximity ligation assay, we show that the interaction takes place in the cell nucleus. S100A4 knockdown experiments in two p53 wild-type cell lines, A549 and HeLa, resulted in stabilization of p53 protein, indicating that S100A4 is promoting p53 degradation. Finally, we demonstrate that S100A4 knockdown leads to p53-dependent cell cycle arrest and increased cisplatin-induced apoptosis. Thus, our data add a new layer to the oncogenic properties of S100A4 through its inhibition of p53-dependent processes.

Depigmenting Effect of Resveratrol Is Dependent on FOXO3a Activation without SIRT1 Activation.

Science.gov (United States)

Kwon, Soon-Hyo; Choi, Hye-Ryung; Kang, Youn-A; Park, Kyoung-Chan

2017-06-07

Resveratrol exhibits not only anti-melanogenic property by inhibiting microphthalmia-associated transcription factor (MITF), but also anti-aging property by activating sirtuin-1 (SIRT1). In this study, the relationship between depigmenting effect of resveratrol and SIRT1/forkhead box O (FOXO) 3a activation and was investigated. Resveratrol suppressed melanogenesis by the downregulation of MITF and tyrosinase via ERK pathway. Results showed that the expression of both SIRT1 and FOXO3a were increased. It is reported that SIRT1 is critical regulator of FOXO-mediated transcription in response to oxidative stress. However in our study, FOXO3a activation appeared earlier than that of SIRT1. Furthermore, the effect of resveratrol on the levels of MITF and tyrosinase was suppressed when melanocytes were pre-treated with SP600125 (JNK inhibitor). However, pre-treatment with SIRT1 inhibitor (EX527, or sirtinol) did not affect the levels of MITF and tyrosinase. Therefore, resveratrol inhibits melanogenesis through the activation of FOXO3a but not by the activation of SIRT1. Although SIRT1 activation by resveratrol is a well-known mechanism of resveratrol-induced antiaging effects, our study showed that not SIRT1 but FOXO3a activation is involved in depigmenting effects of resveratrol.

Ser46 phosphorylation and prolyl-isomerase Pin1-mediated isomerization of p53 are key events in p53-dependent apoptosis induced by mutant huntingtin.

Science.gov (United States)

Grison, Alice; Mantovani, Fiamma; Comel, Anna; Agostoni, Elena; Gustincich, Stefano; Persichetti, Francesca; Del Sal, Giannino

2011-11-01

Huntington disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in the gene coding for huntingtin protein. Several mechanisms have been proposed by which mutant huntingtin (mHtt) may trigger striatal neurodegeneration, including mitochondrial dysfunction, oxidative stress, and apoptosis. Furthermore, mHtt induces DNA damage and activates a stress response. In this context, p53 plays a crucial role in mediating mHtt toxic effects. Here we have dissected the pathway of p53 activation by mHtt in human neuronal cells and in HD mice, with the aim of highlighting critical nodes that may be pharmacologically manipulated for therapeutic intervention. We demonstrate that expression of mHtt causes increased phosphorylation of p53 on Ser46, leading to its interaction with phosphorylation-dependent prolyl isomerase Pin1 and consequent dissociation from the apoptosis inhibitor iASPP, thereby inducing the expression of apoptotic target genes. Inhibition of Ser46 phosphorylation by targeting homeodomain-interacting protein kinase 2 (HIPK2), PKCδ, or ataxia telangiectasia mutated kinase, as well as inhibition of the prolyl isomerase Pin1, prevents mHtt-dependent apoptosis of neuronal cells. These results provide a rationale for the use of small-molecule inhibitors of stress-responsive protein kinases and Pin1 as a potential therapeutic strategy for HD treatment.

Effect of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on the growth and radiotherapeutic sensitivity of human lymphoma cell lines

International Nuclear Information System (INIS)

Yu Zeyang; Fan Wo; Li Dongqing; Zhu Ran; Wang Yongqing; Wu Jinchang

2008-01-01

Objective: To explore the inhibitory effect and radiation sensitization of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on human lymphoma cell lines. Methods: Human lymphoma cell lines Raji and Daudi were treated with rAd-p53, radiation therapy and combined treatment, respectively. The cell growth inhibition was assessed by MTT. The p53 protein expression was detected by Western blotting, and p53 mRNA was detected by BT-PCB. Results: The MTT results showed that the inhibitory effect and radiosensitivity enhancement of rAd-p53 on human lymphoma cell lines were not obvious [Raji: (27.5±4.1)%; Daudi: (28.1±1.6)%]. The results of Western blotting and BT-PCB showed that extrinsic p53 protein and p53 mRNA were expressed to some degree, but not at high-level. In addition, the results didn't demonstrate obvious radiosensitivity enhancement. Conclusions: The role of inhibition and radiosensitivity enhancement of rAd-p53 was not significant on human lymphoma cell lines. (authors)

Immunohistochemical study of p53, pRb, p16 in esophageal cancer

International Nuclear Information System (INIS)

Zo, Jae Ill; Zo, Kyung Ja; Park, Jong Ho; Kim, Mi Hee

1998-01-01

To confirm the expression of molecular genetic alterations of p53, pRb, p16 in esophageal cancer and to investigate the expression of p53, pRb, p16 in esophageal cancer according to the pathologic steps of carcinogenesis, immuno-histochemistry was performed in 15 resected esophageal cancer specimens with multiple separated lesions after pathologic mapping. The accumulation of mutant p53 was observed in 60 % of dysplasia and 47 % of invasive cancer, while pRb was not detected in 91 % of dysplasia and 72.7 % of invasive cancer. But p16 was not observed in 0 % in dysplasia and 7 % of invasive cancer. But p16 was not observed in 0 % in dysplasia and 28.6 % in invasive cancer. There was no simultaneous negative pRb and p16 expression. There was no relations between p53 and p16, pRb. As a results, the expression of p53, pRb, p16 was co-related well with molecular genetic changes and inactivation of p53, pRb, p16 was co-related well with molecular genetic changes and inactivation of p53 and pRb was common and early event in esophageal carcinogenesis in Korea, but inactivation of p16 was a infrequent change. (author). 17 refs., 2 tabs., 7 figs

Regulation of GAD65 expression by SMAR1 and p53 upon Streptozotocin treatment

Directory of Open Access Journals (Sweden)

Singh Sandeep

2012-09-01

Full Text Available Abstract Background GAD65 (Glutamic acid decarboxylase 65 KDa isoform is one of the most important auto-antigens involved in Type 1 diabetes induction. Although it serves as one of the first injury markers of β-islets, the mechanisms governing GAD65 expression remain poorly understood. Since the regulation of GAD65 is crucial for the proper functioning of insulin secreting cells, we investigated the stress induced regulation of GAD65 transcription. Results The present study shows that SMAR1 regulates GAD65 expression at the transcription level. Using a novel protein-DNA pull-down assay, we show that SMAR1 binding is very specific to GAD65 promoter but not to the other isoform, GAD67. We show that Streptozotocin (STZ mediated DNA damage leads to upregulation of SMAR1 and p53 expression, resulting in elevated levels of GAD65, in both cell lines as well as mouse β-islets. SMAR1 and p53 act synergistically to up-regulate GAD65 expression upon STZ treatment. Conclusion We propose a novel mechanism of GAD65 regulation by synergistic activities of SMAR1 and p53.

FGF1 protects neuroblastoma SH-SY5Y cells from p53-dependent apoptosis through an intracrine pathway regulated by FGF1 phosphorylation

Science.gov (United States)

Pirou, Caroline; Montazer-Torbati, Fatemeh; Jah, Nadège; Delmas, Elisabeth; Lasbleiz, Christelle; Mignotte, Bernard; Renaud, Flore

2017-01-01

Neuroblastoma, a sympathetic nervous system tumor, accounts for 15% of cancer deaths in children. In contrast to most human tumors, p53 is rarely mutated in human primary neuroblastoma, suggesting impaired p53 activation in neuroblastoma. Various studies have shown correlations between fgf1 expression levels and both prognosis severity and tumor chemoresistance. As we previously showed that fibroblast growth factor 1 (FGF1) inhibited p53-dependent apoptosis in neuron-like PC12 cells, we initiated the study of the interaction between the FGF1 and p53 pathways in neuroblastoma. We focused on the activity of either extracellular FGF1 by adding recombinant rFGF1 in media, or of intracellular FGF1 by overexpression in human SH-SY5Y and mouse N2a neuroblastoma cell lines. In both cell lines, the genotoxic drug etoposide induced a classical mitochondrial p53-dependent apoptosis. FGF1 was able to inhibit p53-dependent apoptosis upstream of mitochondrial events in SH-SY5Y cells by both extracellular and intracellular pathways. Both rFGF1 addition and etoposide treatment increased fgf1 expression in SH-SY5Y cells. Conversely, rFGF1 or overexpressed FGF1 had no effect on p53-dependent apoptosis and fgf1 expression in neuroblastoma N2a cells. Using different FGF1 mutants (that is, FGF1K132E, FGF1S130A and FGF1S130D), we further showed that the C-terminal domain and phosphorylation of FGF1 regulate its intracrine anti-apoptotic activity in neuroblastoma SH-SY5Y cells. This study provides the first evidence for a role of an intracrine growth factor pathway on p53-dependent apoptosis in neuroblastoma, and could lead to the identification of key regulators involved in neuroblastoma tumor progression and chemoresistance. PMID:29048426

Identification and analysis of evolutionary selection pressures acting at the molecular level in five forkhead subfamilies

Directory of Open Access Journals (Sweden)

Rannala Bruce

2008-09-01

Full Text Available Abstract Background Members of the forkhead gene family act as transcription regulators in biological processes including development and metabolism. The evolution of forkhead genes has not been widely examined and selection pressures at the molecular level influencing subfamily evolution and differentiation have not been explored. Here, in silico methods were used to examine selection pressures acting on the coding sequence of five multi-species FOX protein subfamily clusters; FoxA, FoxD, FoxI, FoxO and FoxP. Results Application of site models, which estimate overall selection pressures on individual codons throughout the phylogeny, showed that the amino acid changes observed were either neutral or under negative selection. Branch-site models, which allow estimated selection pressures along specified lineages to vary as compared to the remaining phylogeny, identified positive selection along branches leading to the FoxA3 and Protostomia clades in the FoxA cluster and the branch leading to the FoxO3 clade in the FoxO cluster. Residues that may differentiate paralogs were identified in the FoxA and FoxO clusters and residues that differentiate orthologs were identified in the FoxA cluster. Neutral amino acid changes were identified in the forkhead domain of the FoxA, FoxD and FoxP clusters while positive selection was identified in the forkhead domain of the Protostomia lineage of the FoxA cluster. A series of residues under strong negative selection adjacent to the N- and C-termini of the forkhead domain were identified in all clusters analyzed suggesting a new method for refinement of domain boundaries. Extrapolation of domains among cluster members in conjunction with selection pressure information allowed prediction of residue function in the FoxA, FoxO and FoxP clusters and exclusion of known domain function in residues of the FoxA and FoxI clusters. Conclusion Consideration of selection pressures observed in conjunction with known

Effect of p53 activation on cell growth, thymidine kinase-1 activity, and 3'-deoxy-3'fluorothymidine uptake

International Nuclear Information System (INIS)

Schwartz, Jeffrey L.; Tamura, Yasuko; Jordan, Robert; Grierson, John R.; Krohn, Kenneth A.

2004-01-01

The use of thymidine (TdR) and thymidine analogs such as 3'-deoxy-3'-fluorothymidine (FLT) as positron emission tomography (PET)-based tracers of tumor proliferation rate is based on the hypothesis that measurement of uptake of these nucleosides, a function primarily of thymidine kinase-1 (TK 1 ) activity, provides an accurate measure of cell proliferation in tumors. Tumor growth is influenced by many factors including the oxygen concentration within tumors and whether tumor cells have been exposed to cytotoxic therapies. The p53 gene plays an important role in regulating growth under both of these conditions. The goal of this study was to investigate the influence of p53 activation on cell growth, TK 1 activity, and FLT uptake. To accomplish this, TK 1 activity, S phase fraction, and the uptake of FLT were determined in plateau-phase and exponentially growing cultures of an isogenic pair of human tumor cell lines in which p53 expression was normal or inactivated by human papilloma virus type 16 E6 expression. Ionizing radiation exposure was used to stimulate p53 activity and to induce alterations in cell cycle progression. We found that exposure of cells to ionizing radiation induced dose-dependent changes in cell cycle progression in both cell lines. The relationship between S phase percentage, TK 1 activity, and FLT uptake were essentially unchanged in the p53-normal cell line. In contrast, TK 1 activity and FLT uptake remained high in the p53-deficient variant even when S phase percentage was low due to a p53-dependent G2 arrest. We conclude that a functional p53 response is required to maintain the normal relationship between TK1 activity and S phase percentage following radiation exposure

Sirtuin 1 (SIRT1 activation mediates sildenafil induced delayed cardioprotection against ischemia-reperfusion injury in mice.

Directory of Open Access Journals (Sweden)

Mona Shalwala

Full Text Available BACKGROUND: It has been well documented that phosphodiesterase-5 inhibitor, sildenafil (SIL protects against myocardial ischemia/reperfusion (I-R injury. SIRT1 is part of the class III Sirtuin family of histone deacetylases that deacetylates proteins involved in cellular stress response including those related to I-R injury. OBJECTIVE/HYPOTHESIS: We tested the hypothesis that SIL-induced cardioprotection may be mediated through activation of SIRT1. METHODS: Adult male ICR mice were treated with SIL (0.7 mg/kg, i.p., Resveratrol (RSV, 5 mg/kg, a putative activator of SIRT1 used as the positive control, or saline (0.2 mL. The hearts were harvested 24 hours later and homogenized for SIRT1 activity analysis. RESULTS: Both SIL- and RSV-treated mice had increased cardiac SIRT1 activity (P<0.001 as compared to the saline-treated controls 24 hours after drug treatment. In isolated ventricular cardiomyocytes, pretreatment with SIL (1 µM or RSV (1 µM for one hour in vitro also upregulated SIRT1 activity (P<0.05. We further examined the causative relationship between SIRT1 activation and SIL-induced late cardioprotection. Pretreatment with SIL (or RSV 24 hours prior to 30 min ischemia and 24 hours of reperfusion significantly reduced infarct size, which was associated with a significant increase in SIRT1 activity (P<0.05. Moreover, sirtinol (a SIRT1 inhibitor, 5 mg/kg, i.p. given 30 min before I-R blunted the infarct-limiting effect of SIL and RSV (P<0.001. CONCLUSION: Our study shows that activation of SIRT1 following SIL treatment plays an essential role in mediating the SIL-induced cardioprotection against I-R injury. This newly identified SIRT1-activating property of SIL may have enormous therapeutic implications.

p18(Hamlet) mediates different p53-dependent responses to DNA-damage inducing agents.

Science.gov (United States)

Lafarga, Vanesa; Cuadrado, Ana; Nebreda, Angel R

2007-10-01

Cells organize appropriate responses to environmental cues by activating specific signaling networks. Two proteins that play key roles in coordinating stress responses are the kinase p38alpha (MAPK14) and the transcription factor p53 (TP53). Depending on the nature and the extent of the stress-induced damage, cells may respond by arresting the cell cycle or by undergoing cell death, and these responses are usually associated with the phosphorylation of particular substrates by p38alpha as well as the activation of specific target genes by p53. We recently characterized a new p38alpha substrate, named p18(Hamlet) (ZNHIT1), which mediates p53-dependent responses to different genotoxic stresses. Thus, cisplatin or UV light induce stabilization of the p18(Hamlet) protein, which then enhances the ability of p53 to bind to and activate the promoters of pro-apoptotic genes such as NOXA and PUMA leading to apoptosis induction. In a similar way, we report here that p18(Hamlet) can also mediate the cell cycle arrest induced in response to gamma-irradiation, by participating in the p53-dependent upregulation of the cell cycle inhibitor p21(Cip1) (CDKN1A).

Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents.

Science.gov (United States)

Michaelis, M; Rothweiler, F; Agha, B; Barth, S; Voges, Y; Löschmann, N; von Deimling, A; Breitling, R; Doerr, H Wilhelm; Rödel, F; Speidel, D; Cinatl, J

2012-04-05

Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3, also disrupts the p53/Mdm2 interaction. All of the 11 UKF-NB-3 sub-lines adapted to RITA that we established retained functional wild-type p53 although RITA induced a substantial p53 response. Moreover, all RITA-adapted cell lines remained sensitive to nutlin-3, whereas only five out of 10 nutlin-3-adapted cell lines retained their sensitivity to RITA. In addition, repeated adaptation of the RITA-adapted sub-line UKF-NB-3(r)RITA(10 μM) to nutlin-3 resulted in p53 mutations. The RITA-adapted UKF-NB-3 sub-lines displayed no or less pronounced resistance to vincristine, cisplatin, and irradiation than nutlin-3-adapted UKF-NB-3 sub-lines. Furthermore, adaptation to RITA was associated with fewer changes at the expression level of antiapoptotic factors than observed with adaptation to nutlin-3. Transcriptomic analyses indicated the RITA-adapted sub-lines to be more similar at the gene expression level to the parental UKF-NB-3 cells than nutlin-3-adapted UKF-NB-3 sub-lines, which correlates with the observed chemotherapy and irradiation sensitivity phenotypes. In conclusion, RITA-adapted cells retain functional p53, remain sensitive to nutlin-3, and display a less pronounced resistance phenotype than nutlin-3-adapted cells.

p53 Over-expression and p53 mutations in colon carcinomas: Relation to dietary risk factors

NARCIS (Netherlands)

Voskuil, D.W.; Kampman, E.; Kraats, A.A. van; Balder, H.F.; Muijen, G.N.P. van; Goldbohm, R.A.; Veer, P. van 't

1999-01-01

Epidemiological studies have suggested that dietary factors may differently affect p53-dependent and p53-independent pathways to colon cancer. Results of such studies may depend on the method used to assess p53 status. This case-control study of 185 colon-cancer cases and 259 controls examines this

Regulation of autophagy by cytoplasmic p53.

Science.gov (United States)

Tasdemir, Ezgi; Maiuri, M Chiara; Galluzzi, Lorenzo; Vitale, Ilio; Djavaheri-Mergny, Mojgan; D'Amelio, Marcello; Criollo, Alfredo; Morselli, Eugenia; Zhu, Changlian; Harper, Francis; Nannmark, Ulf; Samara, Chrysanthi; Pinton, Paolo; Vicencio, José Miguel; Carnuccio, Rosa; Moll, Ute M; Madeo, Frank; Paterlini-Brechot, Patrizia; Rizzuto, Rosario; Szabadkai, Gyorgy; Pierron, Gérard; Blomgren, Klas; Tavernarakis, Nektarios; Codogno, Patrice; Cecconi, Francesco; Kroemer, Guido

2008-06-01

Multiple cellular stressors, including activation of the tumour suppressor p53, can stimulate autophagy. Here we show that deletion, depletion or inhibition of p53 can induce autophagy in human, mouse and nematode cells subjected to knockout, knockdown or pharmacological inhibition of p53. Enhanced autophagy improved the survival of p53-deficient cancer cells under conditions of hypoxia and nutrient depletion, allowing them to maintain high ATP levels. Inhibition of p53 led to autophagy in enucleated cells, and cytoplasmic, not nuclear, p53 was able to repress the enhanced autophagy of p53(-/-) cells. Many different inducers of autophagy (for example, starvation, rapamycin and toxins affecting the endoplasmic reticulum) stimulated proteasome-mediated degradation of p53 through a pathway relying on the E3 ubiquitin ligase HDM2. Inhibition of p53 degradation prevented the activation of autophagy in several cell lines, in response to several distinct stimuli. These results provide evidence of a key signalling pathway that links autophagy to the cancer-associated dysregulation of p53.

SV40 large T-p53 complex: evidence for the presence of two immunologically distinct forms of p53

International Nuclear Information System (INIS)

Milner, J.; Gamble, J.

1985-01-01

The transforming protein of SV40 is the large T antigen. Large T binds a cellular protein, p53, which is potentially oncogenic by virtue of its functional involvement in the control of cell proliferation. This raises the possibility that p53 may mediate, in part, the transforming function of SV40 large T. Two immunologically distinct forms of p53 have been identified in normal cells: the forms are cell-cycle dependent, one being restricted to nondividing cells (p53-Go) and the second to dividing cells (p53-G divided by). The authors have now dissociated and probed the multimeric complex of SV40 large T-p53 for the presence of immunologically distinct forms of p53. Here they present evidence for the presence of p53-Go and p53-G divided by complexed with SV40 large T

Sirt1 overexpression suppresses fluoride-induced p53 acetylation to alleviate fluoride toxicity in ameloblasts responsible for enamel formation.

Science.gov (United States)

Suzuki, Maiko; Ikeda, Atsushi; Bartlett, John D

2018-03-01

Low-dose fluoride is an effective caries prophylactic, but high-dose fluoride is an environmental health hazard that causes skeletal and dental fluorosis. Treatments to prevent fluorosis and the molecular pathways responsive to fluoride exposure remain to be elucidated. Previously we showed that fluoride activates SIRT1 as an adaptive response to protect cells. Here, we demonstrate that fluoride induced p53 acetylation (Ac-p53) [Lys379], which is a SIRT1 deacetylation target, in ameloblast-derived LS8 cells in vitro and in enamel organ in vivo. Here we assessed SIRT1 function on fluoride-induced Ac-p53 formation using CRISPR/Cas9-mediated Sirt1 knockout (LS8 Sirt/KO ) cells or CRISPR/dCas9/SAM-mediated Sirt1 overexpressing (LS8 Sirt1/over ) cells. NaF (5 mM) induced Ac-p53 formation and increased cell cycle arrest via Cdkn1a/p21 expression in Wild-type (WT) cells. However, fluoride-induced Ac-p53 was suppressed by the SIRT1 activator resveratrol (50 µM). Without fluoride, Ac-p53 persisted in LS8 Sirt/KO cells, whereas it decreased in LS8 Sirt1/over . Fluoride-induced Ac-p53 formation was also suppressed in LS8 Sirt1/over cells. Compared to WT cells, fluoride-induced Cdkn1a/p21 expression was elevated in LS8 Sirt/KO and these cells were more susceptible to fluoride-induced growth inhibition. In contrast, LS8 Sirt1/over cells were significantly more resistant. In addition, fluoride-induced cytochrome-c release and caspase-3 activation were suppressed in LS8 Sirt1/over cells. Fluoride induced expression of the DNA double strand break marker γH2AX in WT cells and this was augmented in LS8 Sirt1/KO cells, but was attenuated in LS8 Sirt1/over cells. Our results suggest that SIRT1 deacetylates Ac-p53 to mitigate fluoride-induced cell growth inhibition, mitochondrial damage, DNA damage and apoptosis. This is the first report implicating Ac-p53 in fluoride toxicity.

Targeting p53 by small molecules in hematological malignancies

OpenAIRE

Saha, Manujendra N; Qiu, Lugui; Chang, Hong

2013-01-01

p53 is a powerful tumor suppressor and is an attractive cancer therapeutic target. A breakthrough in cancer research came from the discovery of the drugs which are capable of reactivating p53 function. Most anti-cancer agents, from traditional chemo- and radiation therapies to more recently developed non-peptide small molecules exert their effects by enhancing the anti-proliferative activities of p53. Small molecules such as nutlin, RITA, and PRIMA-1 that can activate p53 have shown their ant...

Interactions between the otitis media gene, Fbxo11, and p53 in the mouse embryonic lung.

Science.gov (United States)

Tateossian, Hilda; Morse, Susan; Simon, Michelle M; Dean, Charlotte H; Brown, Steve D M

2015-12-01

Otitis media with effusion (OME) is the most common cause of hearing loss in children, and tympanostomy (ear tube insertion) to alleviate the condition remains the commonest surgical intervention in children in the developed world. Chronic and recurrent forms of otitis media (OM) are known to have a very substantial genetic component; however, until recently, little was known of the underlying genes involved. The Jeff mouse mutant carries a mutation in the Fbxo11 gene, a member of the F-box family, and develops deafness due to a chronic proliferative OM. We previously reported that Fbxo11 is involved in the regulation of transforming growth factor beta (TGF-β) signalling by regulating the levels of phospho-Smad2 in the epithelial cells of palatal shelves, eyelids and airways of the lungs. It has been proposed that FBXO11 regulates the cell's response to TGF-β through the ubiquitination of CDT2. Additional substrates for FBXO11 have been identified, including p53. Here, we have studied both the genetic and biochemical interactions between FBXO11 and p53 in order to better understand the function of FBXO11 in epithelial development and its potential role in OM. In mice, we show that p53 (also known as Tp53) homozygous mutants and double heterozygous mutants (Jf/+ p53/+) exhibit similar epithelial developmental defects to Fbxo11 homozygotes. FBXO11 and p53 interact in the embryonic lung, and mutation in Fbxo11 prevents the interaction with p53. Both p53 and double mutants show raised levels of pSMAD2, recapitulating that seen in Fbxo11 homozygotes. Overall, our results support the conclusion that FBXO11 regulates the TGF-β pathway in the embryonic lung via cross-talk with p53. © 2015. Published by The Company of Biologists Ltd.

DNA double strand break repair is enhanced by P53 following induction by DNA damage and is dependent on the C-terminal domain of P53

International Nuclear Information System (INIS)

Wei Tang; Powell, Simon N.

1996-01-01

Purpose: The tumor suppressor gene p53 can mediate cell cycle arrest or apoptosis in response to DNA damage. Accumulating evidence suggests that it may also directly or indirectly influence the DNA repair machinery. In the present study, we investigated whether p53, induced by DNA damage, could enhance the rejoining of double-strand DNA breaks. Materials and Methods: DNA double-strand breaks (dsb) were made by restriction enzyme digestion of a plasmid, between a promoter and a 'reporter' gene: luciferase (LUC) or chloramphenicol acetyl-transferase (CAT). Linear or circular plasmid DNA (LUC or CAT) was co-transfected with circular β-Gal plasmid (to normalize for uptake) into mouse embryonic fibroblasts genetically matched to be (+/+) or (-/-) for p53. Their ability to rejoin linearized plasmid was measured by the luciferase or CAT activity detected in rescued plasmids. The activity detected in cells transfected with linear plasmid was scored relative to the activity detected in cells transfected with circular plasmid. Results: Ionizing radiation (IR, 2 Gy) enhanced the dsb repair activity in wild type p53 cells; however, p53 null cells lose this effect, indicating that the enhancement of dsb repair was p53-dependent. REF cells with dominant-negative mutant p53 showed a similar induction compared with the parental REF cells with wild-type p53. This ala-143 mutant p53 prevents cell cycle arrest and transactivation of p21 WAF1/cip1) following IR, indicating that the p53-dependent enhancement of DNA repair is distinct from transactivation. Immortalized murine embryonic fibroblasts, 10(1)VasK1 cells, which express p53 cDNA encoding a temperature-sensitive mutant in the DNA sequence specific binding domain (ala135 to val135) with an alternatively spliced C-terminal domain (ASp53: amino-acids 360-381) and, 10(1)Val5 cells, which express the normal spliced p53 (NSp53) with the same temperature-sensitive mutant were compared. It was found that 10(1)VasK1 cells showed no DNA

Restoration of mp53 to wtp53 by chemical chaperones restores p53-dependent apoptosis after radiotherapy

International Nuclear Information System (INIS)

Ohnishi, T.; Asakawa, I.; Tamamoto, T.; Takahashi, A.; Ohnishi, K.

2003-01-01

The mutations of many kinds of cancer related genes have been investigated for the predictive assay against cancer therapy by the application of molecular biology. A tumor suppressor gene product of wtp53 plays important roles in cancer suppression through the induction of cell growth arrest, DNA repair or apoptosis. The p53 exerts its function by induction of downstream genes and/or interaction to various proteins. Mutations in the p53 gene (mp53) cause conformational alterations in the p53 protein, the majority of which can no longer induce expression of the downstream genes. The genetic status of p53 gene has been focused as the most important candidate among them for cancer therapy. The gene therapy of p53 has been already applied. We reported that the transfection of mp53 gene increased the radio-, thermo- and chemo-resistance, and depressed apoptosis introduced with them through bax-induction and proteolysis of PARP and caspase-3. From these results, we propose that the gene therapy of wtp53 to p53-deleted cancer cells may be very useful for cancer therapy by the combination with radiotherapy. Even in the case of mp53 cancer cells, we succeeded the restoration of mp53 to wtp53 by glycerol or C-terminal peptide of p53 as chemical chaperones. These experimental progresses might support effective cancer therapy against individual patients bearing with different p53 gene status by the use of the most suitable treatment to them in the near future

p53-competent cells and p53-deficient cells display different susceptibility to oxygen functionalized graphene cytotoxicity and genotoxicity.

Science.gov (United States)

Petibone, Dayton M; Mustafa, Thikra; Bourdo, Shawn E; Lafont, Andersen; Ding, Wei; Karmakar, Alokita; Nima, Zeid A; Watanabe, Fumiya; Casciano, Daniel; Morris, Suzanne M; Dobrovolsky, Vasily N; Biris, Alexandru S

2017-11-01

Due to the distinctive physical, electrical, and chemical properties of graphene nanomaterials, numerous efforts pursuing graphene-based biomedical and industrial applications are underway. Oxidation of pristine graphene surfaces mitigates its otherwise hydrophobic characteristic thereby improving its biocompatibility and functionality. Yet, the potential widespread use of oxidized graphene derivatives raises concern about adverse impacts on human health. The p53 tumor suppressor protein maintains cellular and genetic stability after toxic exposures. Here, we show that p53 functional status correlates with oxygen functionalized graphene (f-G) cytotoxicity and genotoxicity in vitro. The f-G exposed p53-competent cells, but not p53-deficient cells, initiated G 0 /G 1 phase cell cycle arrest, suppressed reactive oxygen species, and entered apoptosis. There was p53-dependent f-G genotoxicity evident as increased structural chromosome damage, but not increased gene mutation or chromatin loss. In conclusion, the cytotoxic and genotoxic potential for f-G in exposed cells was dependent on the p53 functional status. These findings have broad implications for the safe and effective implementation of oxidized graphene derivatives into biomedical and industrial applications. Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA. Published 2017. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

P53 family members modulate the expression of PRODH, but not PRODH2, via intronic p53 response elements.

Directory of Open Access Journals (Sweden)

Ivan Raimondi

Full Text Available The tumor suppressor p53 was previously shown to markedly up-regulate the expression of the PRODH gene, encoding the proline dehydrogenase (PRODH enzyme, which catalyzes the first step in proline degradation. Also PRODH2, which degrades 4-hydroxy-L-proline, a product of protein (e.g. collagen catabolism, was recently described as a p53 target. Here, we confirmed p53-dependent induction of endogenous PRODH in response to genotoxic damage in cell lines of different histological origin. We established that over-expression of TAp73β or TAp63β is sufficient to induce PRODH expression in p53-null cells and that PRODH expression parallels the modulation of endogenous p73 by genotoxic drugs in several cell lines. The p53, p63, and p73-dependent transcriptional activation was linked to specific intronic response elements (REs, among those predicted by bioinformatics tools and experimentally validated by a yeast-based transactivation assay. p53 occupancy measurements were validated in HCT116 and MCF7 human cell lines. Conversely, PRODH2 was not responsive to p63 nor p73 and, at best, could be considered a weak p53 target. In fact, minimal levels of PRODH2 transcript induction by genotoxic stress was observed exclusively in one of four p53 wild-type cell lines tested. Consistently, all predicted p53 REs in PRODH2 were poor matches to the p53 RE consensus and showed very weak responsiveness, only to p53, in the functional assay. Taken together, our results highlight that PRODH, but not PRODH2, expression is under the control of p53 family members, specifically p53 and p73. This supports a deeper link between proteins of the p53-family and metabolic pathways, as PRODH modulates the balance of proline and glutamate levels and those of their derivative alpha-keto-glutarate (α-KG under normal and pathological (tumor conditions.

Apoptosis in spermatogonia irradiated P53 null mice

International Nuclear Information System (INIS)

Streit-Bianchi, M.; Hendry, J.H.; Roberts, S.A.; Morris, J.D.; Durgaryan, A.A.

2007-01-01

Complete text of publication follows. The exposure of germ cells to ionizing radiations is of concern both from high-dose therapeutic exposures and from low doses causing deleterious trans-generational mutations. P53 protein plays an important role in cellular damage and is expressed in the testis normally during meiosis, its expression being localised to the preleptotene and early/mid pachytene spermatocytes. P53 null mice, heterozygotes possessing a 129 Sv/C57BL6 genetic background and B6D2F1 mice have been irradiated to 1 and 2 Gy single doses. Fractionated exposures of 1+1 Gy at 4 hours interval were also carried out. Apoptosis induction, spermatogonia and spermatocytes survival were assessed by microscope analysis of histological samples at 4 to 96 hours after irradiation in time-course experiments. The same end-points were also assessed at 72 and 96 hours after irradiation to single doses in the region between 20cGy to 2Gy. A dose dependent level of p53 expression was observed at 4 hours after irradiation to 1 and 2 Gy which returned to normal level by 24 hours. Our data support a two process mode of apoptosis with a first wave around 12 hours followed by a second wave at 2-3 days. The first wave apoptosis is substantially reduced in p53 null mice whereas the second wave is reduced in B6D2F1 mice. The initial increase in apoptosis was delayed in some stages of the of germ cells development which were identified by the spermatids shape. Clear correlation exists between apoptosis and survival assessed in stage XI-XII Tubules 72 hours after irradiation. The data are in agreement with other data in literature indicating that irradiated spermatogonia die through apoptosis. The lack of apoptosis observed in p53 null mice results in a very high survival rate of daughter cells assessed later. Theses spermatocytes and the following progenitor cells are likely to carry mutations as most will not die in the smaller second wave of apoptosis observed 3 days after

3-MCPD 1-Palmitate Induced Tubular Cell Apoptosis In Vivo via JNK/p53 Pathways

Science.gov (United States)

Liu, Man; Huang, Guoren; Wang, Thomas T.Y.; Sun, Xiangjun; Yu, Liangli (Lucy)

2016-01-01

Fatty acid esters of 3-chloro-1, 2-propanediol (3-MCPD esters) are a group of processing induced food contaminants with nephrotoxicity but the molecular mechanism(s) remains unclear. This study investigated whether and how the JNK/p53 pathway may play a role in the nephrotoxic effect of 3-MCPD esters using 3-MCPD 1-palmitate (MPE) as a probe compound in Sprague Dawley rats. Microarray analysis of the kidney from the Sprague Dawley rats treated with MPE, using Gene Ontology categories and KEGG pathways, revealed that MPE altered mRNA expressions of the genes involved in the mitogen-activated protein kinase (JNK and ERK), p53, and apoptotic signal transduction pathways. The changes in the mRNA expressions were confirmed by qRT-PCR and Western blot analyses and were consistent with the induction of tubular cell apoptosis as determined by histopathological, TUNEL, and immunohistochemistry analyses in the kidneys of the Sprague Dawley rats. Additionally, p53 knockout attenuated the apoptosis, and the apoptosis-related protein bax expression and cleaved caspase-3 activation induced by MPE in the p53 knockout C57BL/6 mice, whereas JNK inhibitor SP600125 but not ERK inhibitor U0126 inhibited MPE-induced apoptosis, supporting the conclusion that JNK/p53 might play a critical role in the tubular cell apoptosis induced by MPE and other 3-MCPD fatty acid esters. PMID:27008853

Gene expression and apoptosis induction in p53-heterozygous irradiated mice

International Nuclear Information System (INIS)

Di Masi, Alessandra; Antoccia, Antonio; Dimauro, Ivan; Argentino-Storino, Alberta; Mosiello, Alberto; Mango, Ruggiero; Novelli, Giuseppe; Tanzarella, Caterina

2006-01-01

The role of the p53-genetic background in the expression of genes involved in either cell cycle checkpoint activation or apoptosis was evaluated in p53+/+ and p53+/- mouse strains at both basal levels and after DNA-induced damage. The spleen, colon, kidneys, lungs and liver of both strains were harvested from untreated animals and from mice exposed to 7.5 Gy of X-rays and sacrificed after 5 h. No significant differences were observed in the basal levels of p53 protein, CDKN1A and bax mRNA and spontaneous apoptosis, neither among the different organs within the same strain, nor between the same organ in the p53+/+ and p53+/- strains. After X-ray exposure, p53-dependent regulation was strikingly tissue-specific. In wild-type irradiated mice, p53 protein level increased after radiation treatment in all the organs analysed, whereas both CDKN1A and bax genes transcription increased in the spleen, colon and lungs, as assessed by means of quantitative RT-PCR. In p53+/- irradiated mice, on the contrary, a significant p53 induction was detected only in the spleen, while CDKN1A and bax genes levels increased in the spleen, colon and lungs, revealing the existence of different mechanisms of gene regulation in different organs. Apoptosis induction was observed in the spleen and colon of both strains, even if to lower extent in p53+/- mice compared to p53+/+ animals. In conclusion, in the spleen and colon, target gene transcription and apoptosis may be related to p53 genotype after DNA damage-induction. Moreover, our findings highlight the selectivity of p53 in transactivation following DNA damage in vivo, resulting in tissue-specific responses

Gene expression and apoptosis induction in p53-heterozygous irradiated mice

Energy Technology Data Exchange (ETDEWEB)

Di Masi, Alessandra [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy); Antoccia, Antonio [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy); Dimauro, Ivan [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy); Argentino-Storino, Alberta [Research Toxicology Centre S.p.A., Via Tito Speri, 18, 00040 Pomezia (RM) (Italy); Mosiello, Alberto [Research Toxicology Centre S.p.A., Via Tito Speri, 18, 00040 Pomezia (RM) (Italy); Mango, Ruggiero [Centre of Excellence for Genomic Risk Assessment in Multifactorial and Complex Diseases, School of Medicine, University of Rome ' Tor Vergata' , Rome (Italy); Novelli, Giuseppe [Centre of Excellence for Genomic Risk Assessment in Multifactorial and Complex Diseases, School of Medicine, University of Rome ' Tor Vergata' , Rome (Italy); Tanzarella, Caterina [Department of Biology, University of Rome ' Roma Tre' , Viale G. Marconi, 446, 00146 Rome (Italy)]. E-mail: tanzarel@uniroma3.it

2006-02-22

The role of the p53-genetic background in the expression of genes involved in either cell cycle checkpoint activation or apoptosis was evaluated in p53+/+ and p53+/- mouse strains at both basal levels and after DNA-induced damage. The spleen, colon, kidneys, lungs and liver of both strains were harvested from untreated animals and from mice exposed to 7.5 Gy of X-rays and sacrificed after 5 h. No significant differences were observed in the basal levels of p53 protein, CDKN1A and bax mRNA and spontaneous apoptosis, neither among the different organs within the same strain, nor between the same organ in the p53+/+ and p53+/- strains. After X-ray exposure, p53-dependent regulation was strikingly tissue-specific. In wild-type irradiated mice, p53 protein level increased after radiation treatment in all the organs analysed, whereas both CDKN1A and bax genes transcription increased in the spleen, colon and lungs, as assessed by means of quantitative RT-PCR. In p53+/- irradiated mice, on the contrary, a significant p53 induction was detected only in the spleen, while CDKN1A and bax genes levels increased in the spleen, colon and lungs, revealing the existence of different mechanisms of gene regulation in different organs. Apoptosis induction was observed in the spleen and colon of both strains, even if to lower extent in p53+/- mice compared to p53+/+ animals. In conclusion, in the spleen and colon, target gene transcription and apoptosis may be related to p53 genotype after DNA damage-induction. Moreover, our findings highlight the selectivity of p53 in transactivation following DNA damage in vivo, resulting in tissue-specific responses.

NF-kappaB and p53 are the dominant apoptosis-inducing transcription factors elicited by the HIV-1 envelope.

Science.gov (United States)

Perfettini, Jean-Luc; Roumier, Thomas; Castedo, Maria; Larochette, Nathanael; Boya, Patricia; Raynal, Brigitte; Lazar, Vladimir; Ciccosanti, Fabiola; Nardacci, Roberta; Penninger, Josef; Piacentini, Mauro; Kroemer, Guido

2004-03-01

The coculture of cells expressing the HIV-1 envelope glycoprotein complex (Env) with cells expressing CD4 results into cell fusion, deregulated mitosis, and subsequent cell death. Here, we show that NF-kappaB, p53, and AP1 are activated in Env-elicited apoptosis. The nuclear factor kappaB (NF-kappaB) super repressor had an antimitotic and antiapoptotic effect and prevented the Env-elicited phosphorylation of p53 on serine 15 and 46, as well as the activation of AP1. Transfection with dominant-negative p53 abolished apoptosis and AP1 activation. Signs of NF-kappaB and p53 activation were also detected in lymph node biopsies from HIV-1-infected individuals. Microarrays revealed that most (85%) of the transcriptional effects of HIV-1 Env were blocked by the p53 inhibitor pifithrin-alpha. Macroarrays led to the identification of several Env-elicited, p53-dependent proapoptotic transcripts, in particular Puma, a proapoptotic "BH3-only" protein from the Bcl-2 family known to activate Bax/Bak. Down modulation of Puma by antisense oligonucleotides, as well as RNA interference of Bax and Bak, prevented Env-induced apoptosis. HIV-1-infected primary lymphoblasts up-regulated Puma in vitro. Moreover, circulating CD4+ lymphocytes from untreated, HIV-1-infected donors contained enhanced amounts of Puma protein, and these elevated Puma levels dropped upon antiretroviral therapy. Altogether, these data indicate that NF-kappaB and p53 cooperate as the dominant proapoptotic transcription factors participating in HIV-1 infection.

p53 expression in biopsies from children with Langerhans cell histiocytosis

DEFF Research Database (Denmark)

Bank, Micha I; Lundegaard, Pia Rengtved; Carstensen, Henrik

2002-01-01

based on CD1a positivity. The slides were stained with p53 antibody and semiquantitatively evaluated using a grading system from 1 to 5 as an estimate for 0% to 20%, 20% to 40%, 40% to 60%, 60% to 80%, and 80% to 100% p53-positive for pathologic Langerhans cells (pLC), respectively. RESULTS: The p53...... protein was expressed in various degrees in pLC in all lesions. The degree of p53 expression could not be correlated to either clinical manifestation or outcome. CONCLUSIONS: An increased expression of p53 in pLC indicates an altered DNA repair control with or without abnormal control of apoptosis....

Sirtuins: Molecular Traffic Lights in the Crossroad of Oxidative Stress, Chromatin Remodeling, and Transcription

Directory of Open Access Journals (Sweden)

Ramkumar Rajendran

2011-01-01

Full Text Available Transcription is regulated by acetylation/deacetylation reactions of histone and nonhistone proteins mediated by enzymes called KATs and HDACs, respectively. As a major mechanism of transcriptional regulation, protein acetylation is a key controller of physiological processes such as cell cycle, DNA damage response, metabolism, apoptosis, and autophagy. The deacetylase activity of class III histone deacetylases or sirtuins depends on the presence of NAD+ (nicotinamide adenine dinucleotide, and therefore, their function is closely linked to cellular energy consumption. This activity of sirtuins connects the modulation of chromatin dynamics and transcriptional regulation under oxidative stress to cellular lifespan, glucose homeostasis, inflammation, and multiple aging-related diseases including cancer. Here we provide an overview of the recent developments in relation to the diverse biological activities associated with sirtuin enzymes and stress responsive transcription factors, DNA damage, and oxidative stress and relate the involvement of sirtuins in the regulation of these processes to oncogenesis. Since the majority of the molecular mechanisms implicated in these pathways have been described for Sirt1, this sirtuin family member is more extensively presented in this paper.

Screening of medicinal plant phytochemicals as natural antagonists of p53-MDM2 interaction to reactivate p53 functioning.

Science.gov (United States)

Riaz, Muhammad; Ashfaq, Usman A; Qasim, Muhammad; Yasmeen, Erum; Ul Qamar, Muhammad T; Anwar, Farooq

2017-10-01

In most types of cancer, overexpression of murine double minute 2 (MDM2) often leads to inactivation of p53. The crystal structure of MDM2, with a 109-residue amino-terminal domain, reveals that MDM2 has a core hydrophobic region to which p53 binds as an amphipathic α helix. The interface depends on the steric complementarity between MDM2 and the hydrophobic region of p53. Especially, on p53's triad, amino acids Phe19, Trp23 and Leu26 bind to the MDM2 core. Results from studies suggest that the structural motif of both p53 and MDM2 can be attributed to similarities in the amphipathic α helix. Thus, in the current investigation it is hypothesized that the similarity in the structural motif might be the cause of p53 inactivation by MDM2. Hence, molecular docking and phytochemical screening approaches are appraised to inhibit the hydrophobic cleft of MDM2 and to stop p53-MDM2 interaction, resulting in reactivation of p53 activity. For this purpose, a library of 2295 phytochemicals were screened against p53-MDM2 to find potential candidates. Of these, four phytochemicals including epigallocatechin gallate, alvaradoin M, alvaradoin E and nordihydroguaiaretic acid were found to be potential inhibitors of p53-MDM2 interaction. The screened phytochemicals, derived from natural extracts, may have negligible side effects and can be explored as potent antagonists of p53-MDM2 interactions, resulting in reactivation of the normal transcription of p53.

Resveratrol Protects against TNF-α-Induced Injury in Human Umbilical Endothelial Cells through Promoting Sirtuin-1-Induced Repression of NF-KB and p38 MAPK

Science.gov (United States)

Huang, Shujie; Zhu, Pengli

2016-01-01

Inflammation and reactive oxygen species (ROS) play important roles in the pathogenesis of atherosclerosis. Resveratrol has been shown to possess anti-inflammatory and antioxidative stress activities, but the underlying mechanisms are not fully understood. In the present study, we investigated the molecular basis associated with the protective effects of resveratrol on tumor necrosis factor-alpha (TNF-α)-induced injury in human umbilical endothelial cells (HUVECs) using a variety of approaches including a cell viability assay, reverse transcription and quantitative polymerase chain reaction, western blot, and immunofluorescence staining. We showed that TNF-α induced CD40 expression and ROS production in cultured HUVECs, which were attenuated by resveratrol treatment. Also, resveratrol increased the expression of sirtuin 1 (SIRT1); and repression of SIRT1 by small-interfering RNA (siRNA) and the SIRT1 inhibitor Ex527 reduced the inhibitory effects of resveratrol on CD40 expression and ROS generation. In addition, resveratrol downregulated the levels of p65 and phospho-p38 MAPK, but this inhibitory effect was attenuated by the suppression of SIRT1 activity. Moreover, the p38 MAPK inhibitor SD203580 and the nuclear factor (NF)-κB inhibitor pyrrolidine dithiocarbamate (PDTC) achieved similar repressive effects as resveratrol on TNF-α-induced ROS generation and CD40 expression. Thus, our study provides a mechanistic link between resveratrol and the activation of SIRT1, the latter of which is involved in resveratrol-mediated repression of the p38 MAPK/NF-κB pathway and ROS production in TNF-α-treated HUVECs. PMID:26799794

p53-dependent inhibition of TrxR1 contributes to the tumor-specific induction of apoptosis by RITA.

Science.gov (United States)

Hedström, Elisabeth; Eriksson, Sofi; Zawacka-Pankau, Joanna; Arnér, Elias S J; Selivanova, Galina

2009-11-01

Thioredoxin reductase 1 (TrxR1) is a key regulator in many redox-dependent cellular pathways, and is often overexpressed in cancer. Several studies have identified TrxR1 as a potentially important target for anticancer therapy. The low molecular weight compound RITA (NSC 652287) binds p53 and induces p53-dependent apoptosis. Here we found that RITA also targets TrxR1 by non-covalent binding, followed by inhibition of its activity in vitro and by inhibition of TrxR activity in cancer cells. Interestingly, a novel approximately 130 kDa form of TrxR1, presumably representing a stable covalently linked dimer, and an increased generation of reactive oxygen species (ROS) were induced by RITA in cancer cells in a p53-dependent manner. Similarly, the gold-based TrxR inhibitor auranofin induced apoptosis related to oxidative stress, but independently of p53 and without apparent induction of the approximately 130 kDa form of TrxR1. In contrast to the effects observed in cancer cells, RITA did not inhibit TrxR or ROS formation in normal fibroblasts (NHDF). The inhibition of TrxR1 can sensitize tumor cells to agents that induce oxidative stress and may directly trigger cell death. Thus, our results suggest that a unique p53-dependent effect of RITA on TrxR1 in cancer cells might synergize with p53-dependent induction of pro-apoptotic genes and oxidative stress, thereby leading to a robust induction of cancer cell death, without affecting non-transformed cells.

Interplay between PTB and miR-1285 at the p53 3'UTR modulates the levels of p53 and its isoform Δ40p53α.

Science.gov (United States)

Katoch, Aanchal; George, Biju; Iyyappan, Amrutha; Khan, Debjit; Das, Saumitra

2017-09-29

p53 and its translational isoform Δ40p53 are involved in many important cellular functions like cell cycle, cell proliferation, differentiation and metabolism. Expression of both the isoforms can be regulated at different steps. In this study, we explored the role of 3'UTR in regulating the expression of these two translational isoforms. We report that the trans acting factor, Polypyrimidine Tract Binding protein (PTB), also interacts specifically with 3'UTR of p53 mRNA and positively regulates expression of p53 isoforms. Our results suggest that there is interplay between miRNAs and PTB at the 3'UTR under normal and stress conditions like DNA damage. Interestingly, PTB showed some overlapping binding regions in the p53 3'UTR with miR-1285. In fact, knockdown of miR-1285 as well as expression of p53 3'UTR with mutated miR-1285 binding sites resulted in enhanced association of PTB with the 3'UTR, which provides mechanistic insights of this interplay. Taken together, the results provide a plausible molecular basis of how the interplay between miRNAs and the PTB protein at the 3'UTR can play pivotal role in fine tuning the expression of the two p53 isoforms. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Sirtuins: Novel targets for metabolic disease in drug development

International Nuclear Information System (INIS)

Jiang Weijian

2008-01-01

Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases such as type 2 diabetes. SIRT1, an NAD + -dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produces beneficial effects on glucose homeostasis and insulin sensitivity. Activation of SIRT1 leads to enhanced activity of multiple proteins, including peroxisome proliferator-activated receptor coactivator-1α (PGC-1α) and FOXO which helps to mediate some of the in vitro and in vivo effects of sirtuins. Resveratrol, a polyphenolic SIRT1 activator, mimics the effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance. In this review, we summarize recent research advances in unveiling the molecular mechanisms that underpin sirtuin as therapeutic candidates and discuss the possibility of using resveratrol as potential drug for treatment of diabetes

Role of Tumor Suppressor P53 in Megakaryopoiesis and Platelet Function

Science.gov (United States)

Apostolidis, Pani A.; Woulfe, Donna S.; Chavez, Massiel; Miller, William M.; Papoutsakis, Eleftherios T.

2011-01-01

The pathobiological role of p53 has been widely studied, however its role in normophysiology is relatively unexplored. We previously showed that p53 knock-down increased ploidy in megakaryocytic cultures. This study aims to examine the effect of p53 loss on in vivo megakaryopoiesis, platelet production and function, and to investigate the basis for greater ploidy in p53−/− megakaryocytic cultures. Here, we used flow cytometry to analyze ploidy, DNA synthesis and apoptosis in murine cultured and bone marrow megakaryocytes following thrombopoietin administration and to analyze fibrinogen binding to platelets in vitro. Culture of p53−/− marrow cells for 6 days with thrombopoietin gave rise to 1.7-fold more megakaryocytes, 26.1±3.6% of which reached ploidy classes ≥64N compared to 8.2±0.9% of p53+/+ megakaryocytes. This was due to 30% greater DNA synthesis in p53−/− megakaryocytes and 31% greater apoptosis in p53+/+ megakaryocytes by day 4 of culture. Although the bone marrow and spleen steady-state megakaryocytic content and ploidy were similar in p53+/+ and p53−/− mice, thrombopoietin administration resulted in increased megakaryocytic polyploidization in p53−/− mice. Although their platelet counts were normal, p53−/− mice exhibited significantly longer bleeding times and p53−/− platelets were less sensitive than p53+/+ platelets to agonist-induced fibrinogen binding and P-selectin secretion. In summary, our in vivo and ex-vivo studies indicate that p53 loss leads to increased polyploidization during megakaryopoiesis. Our findings also suggest for the first time a direct link between p53 loss and the development of fully functional platelets resulting in hemostatic deficiencies. PMID:22024107

p53 and PTEN/MMAC1/TEP1 gene therapy of human prostate PC-3 carcinoma xenograft, using transferrin-facilitated lipofection gene delivery strategy.

Science.gov (United States)

Seki, Masafumi; Iwakawa, Jun; Cheng, Helen; Cheng, Pi-Wan

2002-04-10

We previously reported that supplementation of a cationic liposome with transferrin (Tf) greatly enhanced lipofection efficiency (P.-W. Cheng, Hum. Gene Ther. 1996;7:275-282). In this study, we examined the efficacy of p53 and PTEN tumor suppressor gene therapy in a mouse xenograft model of human prostate PC-3 carcinoma cells, using a vector consisting of dimyristoyloxypropyl-3-dimethylhydroxyethyl ammonium bromide (DMRIE)-cholesterol (DC) and Tf. When the volume of the tumors grown subcutaneously in athymic nude mice reached 50-60 mm(3), three intratumoral injections of the following four formulations were performed during week 1 and then during week 3: (1) saline, (2) DC + Tf + pCMVlacZ, (3) DC + Tf + pCMVPTEN, and (4) DC + Tf + pCMVp53 (standard formulation). There was no significant difference in tumor volume and survival between group 1 and group 2 animals. As compared with group 1 controls, group 3 animals had slower tumor growth during the first 3 weeks but thereafter their tumor growth rate was similar to that of the controls. By day 2 posttreatment, group 4 animals had significantly lower tumor volume relative to initial tumor volume as well as controls at the comparable time point. Also, animals treated with p53 survived longer. Treatment with DC, Tf, pCMVp53, DC + pCMVp53, or Tf + pCMVp53 had no effect on tumor volume or survival. Expression of p53 protein and apoptosis were detected in tumors treated with the standard formulation, thus associating p53 protein expression and apoptosis with efficacy. However, p53 protein was expressed in only a fraction of the tumor cells, suggesting a role for bystander effects in the efficacy of p53 gene therapy. We conclude that intratumoral gene delivery by a nonviral vector consisting of a cationic liposome and Tf can achieve efficacious p53 gene therapy of prostate cancer.

The novel fusion proteins, GnRH-p53 and GnRHIII-p53, expression and their anti-tumor effect.

Directory of Open Access Journals (Sweden)

Peiyuan Jia

Full Text Available p53, one of the most well studied tumor suppressor factor, is responsible to a variety of damage owing to the induction of apoptosis and cell cycle arrest in the tumor cells. More than 50% of human tumors contain mutation or deletion of p53. Gonadotrophin-releasing hormone (GnRH, as the ligand of Gonadotrophin-releasing hormone receptor (GnRH-R, was used to deliver p53 into tumor cells. The p53 fusion proteins GnRH-p53 and GnRH iii-p53 were expressed and their targeted anti-tumor effects were determined. GnRH mediates its fusion proteins transformation into cancer cells. The intracellular delivery of p53 fusion proteins exerted the inhibition of the growth of H1299 cells in vitro and the reduction of tumor volume in vivo. Their anti-tumor effect was functioned by the apoptosis and cell cycle arrest induced by p53. Hence, the fusion protein could be a novel protein drug for anti-tumor therapy.

Abrogation of Wip1 expression by RITA-activated p53 potentiates apoptosis induction via activation of ATM and inhibition of HdmX

Science.gov (United States)

Spinnler, C; Hedström, E; Li, H; de Lange, J; Nikulenkov, F; Teunisse, A F A S; Verlaan-de Vries, M; Grinkevich, V; Jochemsen, A G; Selivanova, G

2011-01-01

Inactivation of the p53 tumour suppressor, either by mutation or by overexpression of its inhibitors Hdm2 and HdmX is the most frequent event in cancer. Reactivation of p53 by targeting Hdm2 and HdmX is therefore a promising strategy for therapy. However, Hdm2 inhibitors do not prevent inhibition of p53 by HdmX, which impedes p53-mediated apoptosis. Here, we show that p53 reactivation by the small molecule RITA leads to efficient HdmX degradation in tumour cell lines of different origin and in xenograft tumours in vivo. Notably, HdmX degradation occurs selectively in cancer cells, but not in non-transformed cells. We identified the inhibition of the wild-type p53-induced phosphatase 1 (Wip1) as the major mechanism important for full engagement of p53 activity accomplished by restoration of the ataxia telangiectasia mutated (ATM) kinase-signalling cascade, which leads to HdmX degradation. In contrast to previously reported transactivation of Wip1 by p53, we observed p53-dependent repression of Wip1 expression, which disrupts the negative feedback loop conferred by Wip1. Our study reveals that the depletion of both HdmX and Wip1 potentiates cell death due to sustained activation of p53. Thus, RITA is an example of a p53-reactivating drug that not only blocks Hdm2, but also inhibits two important negative regulators of p53 – HdmX and Wip1, leading to efficient elimination of tumour cells. PMID:21546907

Abrogation of Wip1 expression by RITA-activated p53 potentiates apoptosis induction via activation of ATM and inhibition of HdmX.

Science.gov (United States)

Spinnler, C; Hedström, E; Li, H; de Lange, J; Nikulenkov, F; Teunisse, A F A S; Verlaan-de Vries, M; Grinkevich, V; Jochemsen, A G; Selivanova, G

2011-11-01

Inactivation of the p53 tumour suppressor, either by mutation or by overexpression of its inhibitors Hdm2 and HdmX is the most frequent event in cancer. Reactivation of p53 by targeting Hdm2 and HdmX is therefore a promising strategy for therapy. However, Hdm2 inhibitors do not prevent inhibition of p53 by HdmX, which impedes p53-mediated apoptosis. Here, we show that p53 reactivation by the small molecule RITA leads to efficient HdmX degradation in tumour cell lines of different origin and in xenograft tumours in vivo. Notably, HdmX degradation occurs selectively in cancer cells, but not in non-transformed cells. We identified the inhibition of the wild-type p53-induced phosphatase 1 (Wip1) as the major mechanism important for full engagement of p53 activity accomplished by restoration of the ataxia telangiectasia mutated (ATM) kinase-signalling cascade, which leads to HdmX degradation. In contrast to previously reported transactivation of Wip1 by p53, we observed p53-dependent repression of Wip1 expression, which disrupts the negative feedback loop conferred by Wip1. Our study reveals that the depletion of both HdmX and Wip1 potentiates cell death due to sustained activation of p53. Thus, RITA is an example of a p53-reactivating drug that not only blocks Hdm2, but also inhibits two important negative regulators of p53 - HdmX and Wip1, leading to efficient elimination of tumour cells.

p53 mutations promote proteasomal activity.

Science.gov (United States)

Oren, Moshe; Kotler, Eran

2016-07-27

p53 mutations occur very frequently in human cancer. Besides abrogating the tumour suppressive functions of wild-type p53, many of those mutations also acquire oncogenic gain-of-function activities. Augmentation of proteasome activity is now reported as a common gain-of-function mechanism shared by different p53 mutants, which promotes cancer resistance to proteasome inhibitors.

Evidence for the interaction of the regulatory protein Ki-1/57 with p53 and its interacting proteins

International Nuclear Information System (INIS)

Nery, Flavia C.; Rui, Edmilson; Kuniyoshi, Tais M.; Kobarg, Joerg

2006-01-01

Ki-1/57 is a cytoplasmic and nuclear phospho-protein of 57 kDa and interacts with the adaptor protein RACK1, the transcription factor MEF2C, and the chromatin remodeling factor CHD3, suggesting that it might be involved in the regulation of transcription. Here, we describe yeast two-hybrid studies that identified a total of 11 proteins interacting with Ki-1/57, all of which interact or are functionally associated with p53 or other members of the p53 family of proteins. We further found that Ki-1/57 is able to interact with p53 itself in the yeast two-hybrid system when the interaction was tested directly. This interaction could be confirmed by pull down assays with purified proteins in vitro and by reciprocal co-immunoprecipitation assays from the human Hodgkin analogous lymphoma cell line L540. Furthermore, we found that the phosphorylation of p53 by PKC abolishes its interaction with Ki-1/57 in vitro

Air pollution by c-PAHs and plasma levels of p53 and p21WAF1 proteins

Czech Academy of Sciences Publication Activity Database

Rössner ml., Pavel; Binková, Blanka; Milcová, Alena; Solanský, I.; Židzik, J.; Lyubomirova, K.; Farmer, P. B.; Šrám, Radim

2007-01-01

Roč. 620, - (2007), s. 34-40 ISSN 0027-5107 R&D Projects: GA MŽP SI/340/2/00; GA MŽP SL/740/5/03 Grant - others:EU(GB) 2000 -00091 Institutional research plan: CEZ:AV0Z50390512 Source of funding: R - rámcový projekt EK Keywords : air pollution * p53 and p21WAF1 plasma levels Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 4.159, year: 2007

The expanding universe of p53 targets.

Science.gov (United States)

Menendez, Daniel; Inga, Alberto; Resnick, Michael A

2009-10-01

The p53 tumour suppressor is modified through mutation or changes in expression in most cancers, leading to the altered regulation of hundreds of genes that are directly influenced by this sequence-specific transcription factor. Central to the p53 master regulatory network are the target response element (RE) sequences. The extent of p53 transactivation and transcriptional repression is influenced by many factors, including p53 levels, cofactors and the specific RE sequences, all of which contribute to the role that p53 has in the aetiology of cancer. This Review describes the identification and functionality of REs and highlights the inclusion of non-canonical REs that expand the universe of genes and regulation mechanisms in the p53 tumour suppressor network.

Clinical and pathological associations with p53 tumour-suppressor gene mutations and expression of p21WAF1/Cip1 in colorectal carcinoma

NARCIS (Netherlands)

Slebos, R. J.; Baas, I. O.; Clement, M.; Polak, M.; Mulder, J. W.; van den Berg, F. M.; Hamilton, S. R.; Offerhaus, G. J.

1996-01-01

Inactivation of the p53 tumour-suppressor gene is common in a wide variety of human neoplasms. In the majority of cases, single point mutations in the protein-encoding sequence of p53 lead to positive immunohistochemistry (IHC) for the p53 protein, and are accompanied by loss of the wild-type

Interplay between PTB and miR-1285 at the p53 3′UTR modulates the levels of p53 and its isoform Δ40p53α

Science.gov (United States)

Katoch, Aanchal; George, Biju; Iyyappan, Amrutha; Khan, Debjit

2017-01-01

Abstract p53 and its translational isoform Δ40p53 are involved in many important cellular functions like cell cycle, cell proliferation, differentiation and metabolism. Expression of both the isoforms can be regulated at different steps. In this study, we explored the role of 3′UTR in regulating the expression of these two translational isoforms. We report that the trans acting factor, Polypyrimidine Tract Binding protein (PTB), also interacts specifically with 3′UTR of p53 mRNA and positively regulates expression of p53 isoforms. Our results suggest that there is interplay between miRNAs and PTB at the 3′UTR under normal and stress conditions like DNA damage. Interestingly, PTB showed some overlapping binding regions in the p53 3′UTR with miR-1285. In fact, knockdown of miR-1285 as well as expression of p53 3′UTR with mutated miR-1285 binding sites resulted in enhanced association of PTB with the 3′UTR, which provides mechanistic insights of this interplay. Taken together, the results provide a plausible molecular basis of how the interplay between miRNAs and the PTB protein at the 3′UTR can play pivotal role in fine tuning the expression of the two p53 isoforms. PMID:28973454

Impact of the Ki-67 labeling index and p53 expression status on disease-free survival in pT1 urothelial carcinoma of the bladder.

Science.gov (United States)

Vetterlein, Malte W; Roschinski, Julia; Gild, Philipp; Marks, Phillip; Soave, Armin; Doh, Ousman; Isbarn, Hendrik; Höppner, Wolfgang; Wagner, Walter; Shariat, Shahrokh F; Brausi, Maurizio; Büscheck, Franziska; Sauter, Guido; Fisch, Margit; Rink, Michael

2017-12-01

The identification of protein biomarkers to guide treatment decisions regarding adjuvant therapies for high-risk non-muscle-invasive bladder cancer (NMIBC) has been of increasing interest. Evidence of the impact of tumor suppressor gene product p53 and cell proliferation marker Ki-67 on oncologic outcomes in bladder cancer patients at highest risk of recurrence and progression is partially contradictory. We sought to mirror contemporary expression patterns of p53 and Ki-67 in a select cohort of patients with pT1 bladder cancer. Patients from four Northern German institutions with a primary diagnosis of pT1 bladder cancer between 2009 and 2016 and complete data regarding p53 or Ki-67 expression status were included for final analyses. Baseline patient characteristics (age, gender, age-adjusted Charlson comorbidity index) and tumor characteristics [diagnostic sequence, tumor focality, concomitant carcinoma in situ, 1973 World Health Organization (WHO) grading, lymphovascular invasion, adjuvant instillation therapy] were abstracted by retrospective chart review. Immunohistochemistry for detection of p53 and Ki-67 expression was performed according to standardized protocols. Microscopic analyses were performed by central pathologic review. First, we compared patients with positive vs. negative p53 expression and Ki-67 labeling index [>40% vs. ≤40%; cutoffs based on best discriminative ability in univariable Cox regression analysis with disease-free survival (DFS) as endpoint] with regard to baseline and tumor characteristics. Second, we evaluated the effect of biomarker positivity on DFS by plotting univariable Kaplan-Meier curves and performing uni- and multivariable Cox regression analyses. Of 102 patients with complete information on p53 status, 44 (43.1%) were p53 positive, and they more often harbored concomitant carcinoma in situ (50.0% vs. 27.6%; P=0.032) and 1973 WHO grade 3 (97.7% vs. 69.0%; P=0.001) compared to their p53 negative counterparts. Of 79

miR-217 regulates ethanol-induced hepatic inflammation by disrupting sirtuin 1-lipin-1 signaling.

Science.gov (United States)

Yin, Huquan; Liang, Xiaomei; Jogasuria, Alvin; Davidson, Nicholas O; You, Min

2015-05-01

Ethanol-mediated injury, combined with gut-derived lipopolysaccharide (LPS), provokes generation of proinflammatory cytokines in Kupffer cells, causing hepatic inflammation. Among the mediators of these effects, miR-217 aggravates ethanol-induced steatosis in hepatocytes. However, the role of miR-217 in ethanol-induced liver inflammation process is unknown. Here, we examined the role of miR-217 in the responses to ethanol, LPS, or a combination of ethanol and LPS in RAW 264.7 macrophages and in primary Kupffer cells. In macrophages, ethanol substantially exacerbated LPS-mediated induction of miR-217 and production of proinflammatory cytokines compared with LPS or ethanol alone. Consistently, ethanol administration to mice led to increases in miR-217 abundance and increased production of inflammatory cytokines in isolated primary Kupffer cells exposed to the combination of ethanol and LPS. miR-217 promoted combined ethanol and LPS-mediated inhibition of sirtuin 1 expression and activity in macrophages. Moreover, miR-217-mediated sirtuin 1 inhibition was accompanied by increased activities of two vital inflammatory regulators, NF-κB and the nuclear factor of activated T cells c4. Finally, adenovirus-mediated overexpression of miR-217 led to steatosis and inflammation in mice. These findings suggest that miR-217 is a pivotal regulator involved in ethanol-induced hepatic inflammation. Strategies to inhibit hepatic miR-217 could be a viable approach in attenuating alcoholic hepatitis. Copyright © 2015 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

p53 tumor suppressor gene: significance in neoplasia - a review

International Nuclear Information System (INIS)

Alam, J.M.

2000-01-01

p53 is a tumor suppressor gene located on chromosome 17p13.1. Its function includes cell cycle control and apoptosis. Loss of p53 function, either due to decreased level or genetic transformation, is associated with loss of cell cycle control, decrease, apoptosis and genomic modification, such mutation of p53 gene is now assessed and the indicator of neoplasia of cancer of several organs and cell types, p53 has demonstrated to have critical role in defining various progressive stages of neoplasia, therapeutic strategies and clinical application. The present review briefly describes function of p53 in addition to its diagnostic and prognostic significance in detecting several types of neoplasia. (author)

Human neuroblastoma cells with acquired resistance to the p53 activator RITA retain functional p53 and sensitivity to other p53 activating agents

NARCIS (Netherlands)

Michaelis, M.; Rothweiler, F.; Agha, B.; Barth, S.; Voges, Y.; Loeschmann, N.; von Deimling, A.; Breitling, R.; Doerr, H. Wilhelm; Roedel, F.; Speidel, D.; Cinatl, J.; Cinatl Jr., J.; Stephanou, A.

Adaptation of wild-type p53 expressing UKF-NB-3 cancer cells to the murine double minute 2 inhibitor nutlin-3 causes de novo p53 mutations at high frequency (13/20) and multi-drug resistance. Here, we show that the same cells respond very differently when adapted to RITA, a drug that, like nutlin-3,

PRIMA-1Met/APR-246 induces apoptosis and tumor growth delay in small cell lung cancer expressing mutant p53

DEFF Research Database (Denmark)

Zandi, Roza; Selivanova, Galina; Christensen, Camilla Laulund

2011-01-01

Small cell lung cancer (SCLC) is a highly malignant disease with poor prognosis, necessitating the need to develop new and efficient treatment modalities. PRIMA-1(Met) (p53-dependent reactivation of massive apoptosis), also known as APR-246, is a small molecule, which restores tumor suppressor...... function to mutant p53 and induces cancer cell death in various cancer types. Since p53 is mutated in more than 90% of SCLC, we investigated the ability of PRIMA-1(Met) to induce apoptosis and inhibit tumor growth in SCLC with different p53 mutations....

Forkhead Box Protein C2 Promotes Epithelial-Mesenchymal Transition, Migration and Invasion in Cisplatin-Resistant Human Ovarian Cancer Cell Line (SKOV3/CDDP

Directory of Open Access Journals (Sweden)

Chanjuan Li

2016-08-01

Full Text Available Background/Aims: Forkhead Box Protein C2 (FOXC2 has been reported to be overexpressed in a variety of human cancers. However, it is unclear whether FOXC2 regulates epithelial-mesenchymal transition (EMT in CDDP-resistant ovarian cancer cells. The aim of this study is to investigate the effects of FOXC2 on EMT and invasive characteristics of CDDP-resistant ovarian cancer cells and the underlying molecular mechanism. Methods: MTT, Western blot, scratch wound healing, matrigel transwell invasion, attachment and detachment assays were performed to detect half maximal inhibitory concentration (IC50 of CDDP, expression of EMT-related proteins and invasive characteristics in CDDP-resistant ovarian cancer cell line (SKOV3/CDDP and its parental cell line (SKOV3. Small hairpin RNA (shRNA was used to knockdown FOXC2 and analyze the effect of FOXC2 knockdown on EMT and invasive characteristics of SKOV3/CDDP cells. Also, the effect of FOXC2 upregulation on EMT and invasive characteristics of SKOV3 cells was analyzed. Furthermore, the molecular mechanism underlying FOXC2-regulating EMT in ovarian cancer cells was determined. Results: Compared with parental SKOV3 cell line, SKOV3/CDDP showed higher IC50 of CDDP (43.26μM (PConclusions: Taken together, these data demonstrate that FOXC2 may be a promoter of EMT phenotype in CDDP-resistant ovarian cancer cells and a potential therapeutic target for the treatment of advanced ovarian cancer.

Roles of p53, MYC and HIF-1 in regulating glycolysis - the seventh hallmark of cancer.

Science.gov (United States)

Yeung, S J; Pan, J; Lee, M-H

2008-12-01

Despite diversity in genetic events in oncogenesis, cancer cells exhibit a common set of functional characteristics. Otto Warburg discovered that cancer cells have consistently higher rates of glycolysis than normal cells. The underlying mechanisms leading to the Warburg phenomenon include mitochondrial changes, upregulation of rate-limiting enzymes/proteins in glycolysis and intracellular pH regulation, hypoxia-induced switch to anaerobic metabolism, and metabolic reprogramming after loss of p53 function. The regulation of energy metabolism can be traced to a "triad" of transcription factors: c-MYC, HIF-1 and p53. Oncogenetic changes involve a nonrandom set of gene deletions, amplifications and mutations, and many oncogenes and tumor suppressor genes cluster along the signaling pathways that regulate c-MYC, HIF-1 and p53. Glycolysis in cancer cells has clinical implications in cancer diagnosis, treatment and interaction with diabetes mellitus. Many drugs targeting energy metabolism are in development. Future advances in technology may bring about transcriptome and metabolome-guided chemotherapy.

Actinomycin D synergistically enhances the cytotoxicity of CDDP on KB cells by activating P53 via decreasing P53-MDM2 complex.

Science.gov (United States)

Wang, Lin; Pang, Xiao-Cong; Yu, Zi-Ru; Yang, Sheng-Qian; Liu, Ai-Lin; Wang, Jin-Hua; Du, Guan-Hua

2017-06-01

The aim of this study is to investigate the synergism of low dose of actinomycin D (LDActD) to the cytotoxicity of cisplatin (CDDP) on KB cells. The role of P53 reactivation by LDActD in the synergism and its mechanism were further studied. Cell viability was determined by MTT assay. Apoptosis was determined by AnnexinV-FITC/PI staining. Mitochondrial membrane potential (MMP) was detected by JC-1 staining. Expression of proteins was detected by Western blotting (WB) and/or immunofluorescence (IF). Molecular docking of actinomycin D (ACTD) to Mouse double minute 2 homolog (MDM2) and Mouse double minute 2 homolog X (MDMX). MDMX was analyzed by Discovery Studio. The content of P53-MDM2 complex was detected by ELISA assay. The cytotoxicity of CDDP was increased by the combination of LDActD in kinds of cancer cells. Molecular docking showed strong interaction between ACTD and MDM2/MDMX. Meanwhile, LDActD significantly decreased P53-MDM2 complex. Significant increase of the apoptotic activity by the combination therapy in KB cells is P53 upregulated modulator of apoptosis (PUMA) dependent. In addition to the decrease in MMP, LDActD increased P53 regulated protein and decreased BCL-XL in KB cells. LDActD efficiently enhanced the cytotoxicity of CDDP in cancer cells and induced P53-PUMA-dependent and mitochondria-mediated apoptosis in KB cells. The reactivation of P53 was probably achieved by disturbing the interaction of P53 and MDM2/MDMX.

RITA enhances irradiation-induced apoptosis in p53-defective cervical cancer cells via upregulation of IRE1α/XBP1 signaling.

Science.gov (United States)

Zhu, Hong; Abulimiti, Muyasha; Liu, Huan; Su, Xiang-Jiang; Liu, Cai-Hong; Pei, Hai-Ping

2015-09-01

Radiation therapy is the most widely used treatment for patients with cervical cancer. Recent studies have shown that endoplasmic reticulum (ER) stress induces apoptosis and sensitizes tumor cells to radiotherapy, which reportedly induces ER stress in cells. Classical key tumor suppressor p53 is involved in the response to a variety of cellular stresses, including those incurred by ionizing irradiation. A recent study demonstrated that small-molecule RITA (reactivation of p53 and induction of tumor cell apoptosis) increased the radiosensitivity of tumor cells expressing mutant p53 (mtp53). In the present study, we explored the effects and the underlying mechanisms of RITA in regards to the radiosensitivity and ER stress in mtp53-expressing human cervix cancer cells. Treatment with 1 µM of RITA for 24 h before irradiation markedly decreased survival and increased apoptosis in C-33A and HT-3 cells; the effects were not significantly altered by knockdown of p53. In the irradiated C-33A and HT-3 cells, RITA significantly increased the expression of IRE1α, the spliced XBP1 mRNA level, as well as apoptosis; the effects were abolished by knockdown of IRE1α. Transcriptional pulse-chase assays revealed that RITA significantly increased the stability of IRE1α mRNA in the irradiated C-33A and HT-3 cells. In contrast, the same RITA treatment did not show any significant effect on sham-irradiated cells. In conclusion, the present study provides initial evidence that RITA upregulates the expression level of IRE1α by increasing the stability of IRE1α mRNA in irradiated mtp53-expressing cervical cancer cells; the effect leads to enhanced IRE1α/XBP1 ER stress signaling and increased apoptosis in the cells. The present study offers novel insight into the pharmacological potential of RITA in the radiotherapy for cervical cancer.

The Polerovirus F box protein P0 targets ARGONAUTE1 to suppress RNA silencing.

Science.gov (United States)

Bortolamiol, Diane; Pazhouhandeh, Maghsoud; Marrocco, Katia; Genschik, Pascal; Ziegler-Graff, Véronique

2007-09-18

Plants employ post-transcriptional gene silencing (PTGS) as an antiviral defense response. In this mechanism, viral-derived small RNAs are incorporated into the RNA-induced silencing complex (RISC) to guide degradation of the corresponding viral RNAs. ARGONAUTE1 (AGO1) is a key component of RISC: it carries the RNA slicer activity. As a counter-defense, viruses have evolved various proteins that suppress PTGS. Recently, we showed that the Polerovirus P0 protein carries an F box motif required to form an SCF-like complex, which is also essential for P0's silencing suppressor function. Here, we investigate the molecular mechanism by which P0 impairs PTGS. First we show that P0's expression does not affect the biogenesis of primary siRNAs in an inverted repeat-PTGS assay, but it does affect their activity. Moreover, P0's expression in transformed Arabidopsis plants leads to various developmental abnormalities reminiscent of mutants affected in miRNA pathways, which is accompanied by enhanced levels of several miRNA-target transcripts, suggesting that P0 acts at the level of RISC. Interestingly, ectopic expression of P0 triggered AGO1 protein decay in planta. Finally, we provide evidence that P0 physically interacts with AGO1. Based on these results, we propose that P0 hijacks the host SCF machinery to modulate gene silencing by destabilizing AGO1.

A dual role of p53 in the control of autophagy.

Science.gov (United States)

Tasdemir, Ezgi; Chiara Maiuri, M; Morselli, Eugenia; Criollo, Alfredo; D'Amelio, Marcello; Djavaheri-Mergny, Mojgan; Cecconi, Francesco; Tavernarakis, Nektarios; Kroemer, Guido

2008-08-01

Genotoxic stress can induce autophagy in a p53-dependent fashion and p53 can transactivate autophagy-inducing genes. We have observed recently that inactivation of p53 by deletion, depletion or inhibition can trigger autophagy. Thus, human and mouse cells subjected to knockout, knockdown or pharmacological inhibition of p53 manifest signs of autophagy such as depletion of p62/SQSTM1, LC3 lipidation, redistribution of GFP-LC3 in cytoplasmic puncta, and accumulation of autophagosomes and autolysosomes, both in vitro and in vivo. Inhibition of p53 causes autophagy in enucleated cells, indicating that the cytoplasmic, non-nuclear pool of p53 can regulate autophagy. Accordingly, retransfection of p53(-/-) cells with wild-type p53 as well as a p53 mutant that is excluded from the nucleus (due to the deletion of the nuclear localization sequence) can inhibit autophagy, whereas retransfection with a nucleus-restricted p53 mutant (in which the nuclear localization sequence has been deleted) does not inhibit autophagy. Several distinct autophagy inducers (e.g., starvation, rapamycin, lithium, tunicamycin and thapsigargin) stimulate the rapid degradation of p53. In these conditions, inhibition of the p53-specific E3 ubiquitin ligase HDM2 can avoid p53 depletion and simultaneously prevent the activation of autophagy. Moreover, a p53 mutant that lacks the HDM2 ubiquitinylation site and hence is more stable than wild-type p53 is particularly efficient in suppressing autophagy. In conclusion, p53 plays a dual role in the control of autophagy. On the one hand, nuclear p53 can induce autophagy through transcriptional effects. On the other hand, cytoplasmic p53 may act as a master repressor of autophagy.

Effect of p53 activation on cell growth, thymidine kinase-1 activity, and 3'-deoxy-3'fluorothymidine uptake

Energy Technology Data Exchange (ETDEWEB)

Schwartz, Jeffrey L. E-mail: jschwart@u.washington.edu; Tamura, Yasuko; Jordan, Robert; Grierson, John R.; Krohn, Kenneth A

2004-05-01

The use of thymidine (TdR) and thymidine analogs such as 3'-deoxy-3'-fluorothymidine (FLT) as positron emission tomography (PET)-based tracers of tumor proliferation rate is based on the hypothesis that measurement of uptake of these nucleosides, a function primarily of thymidine kinase-1 (TK{sub 1}) activity, provides an accurate measure of cell proliferation in tumors. Tumor growth is influenced by many factors including the oxygen concentration within tumors and whether tumor cells have been exposed to cytotoxic therapies. The p53 gene plays an important role in regulating growth under both of these conditions. The goal of this study was to investigate the influence of p53 activation on cell growth, TK{sub 1} activity, and FLT uptake. To accomplish this, TK{sub 1} activity, S phase fraction, and the uptake of FLT were determined in plateau-phase and exponentially growing cultures of an isogenic pair of human tumor cell lines in which p53 expression was normal or inactivated by human papilloma virus type 16 E6 expression. Ionizing radiation exposure was used to stimulate p53 activity and to induce alterations in cell cycle progression. We found that exposure of cells to ionizing radiation induced dose-dependent changes in cell cycle progression in both cell lines. The relationship between S phase percentage, TK{sub 1} activity, and FLT uptake were essentially unchanged in the p53-normal cell line. In contrast, TK{sub 1} activity and FLT uptake remained high in the p53-deficient variant even when S phase percentage was low due to a p53-dependent G2 arrest. We conclude that a functional p53 response is required to maintain the normal relationship between TK1 activity and S phase percentage following radiation exposure.

p63 expression confers significantly better survival outcomes in high-risk diffuse large B-cell lymphoma and demonstrates p53-like and p53-independent tumor suppressor function

DEFF Research Database (Denmark)

Xu-Monette, Zijun Y; Zhang, Shanxiang; Li, Xin

2016-01-01

with a pan-p63-monoclonal antibody and correlated it with other clinicopathologic factors and clinical outcomes. p63 expression was observed in 42.5% of DLBCL, did not correlate with p53 levels, but correlated with p21, MDM2, p16INK4A, Ki-67, Bcl-6, IRF4/MUM-1 and CD30 expression, REL gains, and BCL6...... was likely due to the association of p63 expression with high-risk IPI, and potential presence of ∆Np63 isoform in TP63 rearranged patients (a mere speculation). Gene expression profiling suggested that p63 has both overlapping and distinct functions compared with p53, and that p63 and mutated p53 antagonize...

BRCA1 Expression is an Important Biomarker for Chemosensitivity: Suppression of BRCA1 Increases the Apoptosis via Up-regulation of p53 and p21 During Cisplatin Treatment in Ovarian Cancer Cells

Directory of Open Access Journals (Sweden)

Ikuo Konishi

2006-01-01

Full Text Available BRCA1 is a tumor suppressor which plays a crucial role in the repair of DNA double-strand breaks, and its abnormality is responsible for hereditary ovarian cancer syndrome. It has recently been reported that reduced expression of BRCA1 is also common in sporadic ovarian carcinoma via its promoter hypermethylation, and that ovarian carcinoma patients negative for BRCA1 expression showed favorable prognosis. To address if BRCA1 expression plays a role in the chemotherapeutic response, we analyzed the effect of BRCA1 suppression on the sensitivity to cisplatin and paclitaxel in ovarian cancer cells. Specific siRNA for BRCA1 gene was transfected into 3 ovarian cancer cell lines with various p53 status. Reduced expression of BRCA1 by transfection of BRCA1-siRNA resulted in a 5.3-fold increase in sensitivity to cisplatin in p53-wild A2780 cells, but not in p53-mutated A2780/CDDP and p53-deleted SKOV3 cells. Regarding the sensitivity to paclitaxel, BRCA1 suppression caused no significant changes in all the 3 cell lines. For ionizing radiation sensitivity, BRCA1 suppression also showed a significant higher sensitivity in A2780 cells. Growth curve and cell cycle analyses showed no signifi cant differences between BRCA1-siRNA-transfected A2780 cells and control cells. However, cisplatin treatment under suppression of BRCA1 showed a significantly increased apoptosis along with up-regulation of p53 and p21 in A2780 cells. Accordingly, reduced expression of BRCA1 enhances the cisplatin sensitivity and apoptosis via up-regulation of p53 and p21, but does not affect the paclitaxel sensitivity. Expression of BRCA1 might be an important biomarker for cisplatin resistance in ovarian carcinoma.

Mutant Mice Lacking the p53 C-Terminal Domain Model Telomere Syndromes

Directory of Open Access Journals (Sweden)

Iva Simeonova

2013-06-01

Full Text Available Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53Δ31, a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis, hallmarks of syndromes caused by short telomeres. Indeed, p53Δ31/Δ31 mice had short telomeres and other phenotypic traits associated with the telomere disease dyskeratosis congenita and its severe variant the Hoyeraal-Hreidarsson syndrome. Heterozygous p53+/Δ31 mice were only mildly affected, but decreased levels of Mdm4, a negative regulator of p53, led to a dramatic aggravation of their symptoms. Importantly, several genes involved in telomere metabolism were downregulated in p53Δ31/Δ31 cells, including Dyskerin, Rtel1, and Tinf2, which are mutated in dyskeratosis congenita, and Terf1, which is implicated in aplastic anemia. Together, these data reveal that a truncating mutation can activate p53 and that p53 plays a major role in the regulation of telomere metabolism.