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Sample records for antigen pcna p53

  1. Prognostic significance of proliferation associated antigens (PCNA, Ki-67) and p53-expression in inoperable head and neck cancer after accelerated split-course radiation therapy

    International Nuclear Information System (INIS)

    Purpose: To determine whether the immunohistochemical (IHC) expression of proliferation associated antigens (Proliferating Cell Nuclear Antigen [PCNA], Ki-67) and the nuclear p53 reactivity are predictive for overall-survival (OS) and relapse-free-survival (RFS) in patients (pts) with inoperable squamous cell carcinoma of the head and neck region (SCC H and N) after accelerated split-course radiation therapy (RT) with and without chemotherapy (ChT). Materials and Methods: Between 10/89 and 9/93, 87 pts with biopsy proven SCC H and N (80 male, 7 female, median age 52 years [range, 23-65 years]) were randomly allocated to RT alone or simultaneous RT/ChT as part of a multicenter trial. All pts had inoperable lesions in AJCC (1988) stage III (7 pts, 8%) and IV (80 pts, 92%). Primaries were located in the oral cavity (19 pts, 22%), oropharynx (38 pts, 44%) and hypopharynx (30 pts, 34%). RT consisted of 3 cycles of accelerated fractionation (180 cGy bid, total dose 7020 cGy/51 days). Scheduled split between cycles was 10 days. ChT consisted of cis-DDP, 60 mg/m2, 5-FU, 350 mg/m2, Leucovorin (LV) 50 mg/m2 iv bolus on day 2 and 5-FU, 350 mg/m2/24 h and LV 100 mg/m2/24 h ci on days 3-5. ChT was repeated on days 22 and 44. Routinely processed paraffin embedded sections were IHC-stained using the monoclonal antibodies PC 10, MIB1 and DO7 for detection of PCNA, Ki-67 antigen and p53 oncoprotein. Percentage of positive nuclei per 1000 tumor cells were given as Labeling Index (LI). In addition, tumor volume (TV) and percentage of necrosis were measured using CT-data. Median follow-up was 3.5 years (range 1.5-5 years). Results: OS and RFS were 39% and 44% after 3 years, respectively. In univariate analysis TV (>125 ml: 5% OS vs. ≤125 ml: 54% OS, p55years: 66% OS vs. ≤55years: 23% OS, p=.0025), PCNA-LI (LI>20%: 50% OS vs. LI≤20%: 31% OS, p=.0146),MIB1-LI (LI>20%: 55% OS vs. LI≤20%: 23% OS, p=.0344) and additional ChT (RT/ChT: 41% OS vs. RT: 27% OS, p=.0258) had a

  2. The response of proliferating cell nuclear antigen (PCNA) to ionizing radiation in human lymphoblastoid cell lines with different p53 status

    International Nuclear Information System (INIS)

    Purpose/Objective: PCNA is a 36kD auxiliary protein for DNA polymerase δ involved in DNA replication and nucleotide excision repair. There are two intranuclear fractions: a detergent-extractable, soluble fraction (SOL) and a tightly DNA bound fraction (BF). To function, PCNA monomers form a trimeric sliding clamp, which is loaded onto DNA. To better understand the role of the p53/p21 pathway in the regulation of PCNA after radiation in vivo, we studied three closely related human lymphoblastoid cell lines, WTK1 (p53mt), TK6 (p53wt) and TK6E6, a HPV16E6 transfected line, that differ in p53 status, radiosensitivity and susceptibility to radiation-induced apoptosis. Materials and Methods: The total cellular PCNA content was divided into the two intranuclear fractions with detergent pretreatment (EDTA 2% containing 2.5 μl/ml Triton-X 100, 5 μl/ml BSA, 15 min, on ice). Time-dependent changes in PCNA monomer and trimer levels were measured after irradiation (0 - 4 Gy) in the different nuclear fractions (BF, SOL) by western blot analysis after protein cross-linking (glutaraldehyde 0.02%, 10 min, room temperature) as an assay for PCNA dependent repair activity. The results were compared to those with human diploid fibroblasts (GM6419) studied under different growth conditions (log-phase, density inhibition) yielding differing p21 levels. Residual damage was assessed by the micronucleus assay. Micronuclei were counted in binucleate cells only, and at least two slides per data point (at least 500 binucleate cells were scored per slide) were examined under the fluorescence microscope. Results: There was no change in total cellular PCNA protein levels up to 48h after irradiation, consistent with predominantly post-translational regulation. Changes in intranuclear distribution and complex formation were observed in a p53/p21 dependent manner. After irradiation, there was an increase in BF PCNA levels up to 2 - 3 times baseline level with a maximum at 30 - 60 min, which could

  3. Analysis of p53 expression and proliferative assessment using PCNA in localized prostate carcinoma

    Directory of Open Access Journals (Sweden)

    Leite K.R.M.

    1999-01-01

    Full Text Available The surgical specimens from 51 men submitted to radical prostatectomy for localized prostate cancer were examined by immunohistochemistry using proliferation cell nuclear antigen (PCNA monoclonal antibody to evaluate the proliferative index (PI. The relationship between PI, biological variables and p53 protein expression was evaluated by immunohistochemistry. PI was low in invasive localized prostate carcinoma (mean, 12.4% and the incidence of PCNA-positive cells was significantly higher in tumors with p53 expression (P = 0.0226. There was no statistical difference in PCNA values when biological parameters such as Gleason score, tumor volume, extraprostatic involvement, seminal vesicle infiltration or lymph node metastasis were considered. We conclude that proliferative activity is usually low in prostate carcinoma but is correlated with p53 immune staining, indicating that p53 is important in cell cycle control in this neoplasm.

  4. EXPRESSION OF P53 PROTEIN AND PROLIFERATING CELL NUCLEAR ANTIGEN IN HUMAN GESTATION TROPHOBLASTIC DISEASE

    Institute of Scientific and Technical Information of China (English)

    黄铁军; 王志忠; 方光光; 刘志恒

    2004-01-01

    Objective: To study the relationship between p53 protein, proliferating cell nuclear antigen (PCNA) expression and benign or malignant gestational trophoblastic disease (MGTD). Methods: The histotomic sections of 48 patients with gestational trophoblastic disease and 24 patients of normal chorionic villi were stained using immunohistochemistry. The monoclonal antibodies were used to determine p53 protein and PCNA. Results: The frequency of p53 and PCNA positive expression were significantly different among the chorionic villi of normal pregnancy, hydratidiform mole (HM) and MGTD. But neither p53 nor PCNA has any relation with the clinical staging or metastasis of MGTD. Conclusion: Both P53 and PCNA are valuable in diagnosis of human gestational trophoblastic disease.

  5. Of humans and canines: Immunohistochemical analysis of PCNA, Bcl-2, p53, cytokeratin and ER in mammary tumours.

    Science.gov (United States)

    Kumaraguruparan, R; Prathiba, D; Nagini, S

    2006-10-01

    Mammary tumours are the most common neoplasms in humans and canines. Human and canine mammary tumours share several important epidemiological, clinicopathological and biochemical features. Development of mammary tumours involves accumulation of mutant cells caused by excessive proliferation and insufficient apoptosis or dysregulation of cellular differentiation. The present study was therefore designed to investigate the expression of proliferation, differentiation, and apoptosis associated proteins together with expression of estrogen receptors (ER) in both human and canine mammary tumours. Thirty breast cancer patients categorized as pre- and postmenopausal, and 30 mammary gland tumours obtained from bitches were included in this study. The expression of proliferating cell nuclear antigen (PCNA), Bcl-2, p53, cytokeratin and ER in tumour tissues and adjacent tissues were investigated using immunohistochemical staining. While the expression of PCNA, Bcl-2, p53 and ER was significantly increased, expression of cytokeratin was significantly lower in both human as well as canine mammary tumours compared to corresponding adjacent tissues. The magnitude of the changes was however more pronounced in premenopausal patients compared to postmenopausal patients. The changes in proliferation, apoptosis and differentiation associated proteins in human and canine mammary tumours validate use of the canine model to understand the molecular mechanisms of mammary carcinogenesis. PMID:16740286

  6. Proliferating cell nuclear antigen, p53 and micro vessel density: Grade II vs. Grade III astrocytoma

    Directory of Open Access Journals (Sweden)

    Malhan Priya

    2010-01-01

    Full Text Available Histological classification and grading are prime procedures in the management of patients with astrocytoma, providing vital data for therapeutic decision making and prognostication. However, it has limitations in assessing biological tumor behavior. This can be overcome by using newer immunohistochemical techniques. This study was carried out to compare proliferative indices using proliferating cell nuclear antigen (PCNA, extent of p53 expression and micro vessel morphometric parameters in patients with low grade and anaplastic astrocytoma. Twenty-five patients, each of grade II and grade III astrocytoma were evaluated using monoclonal antibodies to PCNA, p53 protein and factor VIII related antigen. PCNA, p53-labeling indices were calculated along with micro vessel morphometric analysis using Biovis Image plus Software. Patients with grade III astrocytoma had higher PCNA and p53 labeling indices as compared with grade II astrocytoma (29.14 plus/minus 9.87% vs. 16.84 plus/minus 6.57%, p 0.001; 18.18 plus/minus 6.14% vs. 6.14 plus/minus 7.23%, p 0.001, respectively. Micro vessel percentage area of patients with grade III astrocytoma was also (4.26 plus/minus 3.70 vs. 1.05 plus/minus 0.56, p 0.001, higher along with other micro vessel morphometric parameters. Discordance between histology and one or more IHC parameters was seen in 5/25 (20% of patients with grade III astrocytoma and 9/25 (36% of patients with grade II disease. PCNA and p53 labeling indices were positively correlated with Pearson′s correlation, p less than 0.001 for both. Increased proliferative fraction, genetic alterations and neovascularization mark biological aggressiveness in astrocytoma. Immunohistochemical evaluation scores over meet the challenge of accurate prognostication of this potentially fatal malignancy.

  7. Expression of nitric oxide synthase in human gastric carcinoma and its relation to p53, PCNA

    Institute of Scientific and Technical Information of China (English)

    Yong-Zhong Wang; You-Qing Cao; Jian-Nong Wu; Miao Chen; Xiao-Ying Cha

    2005-01-01

    AIM: To investigate the expression of NOS in gastric carcinoma, and to explore the relationship between the expression of nitric oxide synthases (NOS) and p53, PCNA,pathological features and clinical staging of gastric cancer.METHODS: The activity of NOS protein was investigated in 85 samples of human gastric carcinoma and 25 samples of normal gastric mucosal tissue by biochemical assay. We then examined the expression of NOS, p53, PCNA in 85 samples of human gastric cancer was examined by immunohistochemistry, and NOS mRNA expression in 85 gastric cancer tissue specimens by in situ hybridization.RESULTS: Biochemical assay showed that the activity of NOS was significantly higher in gastric carcinoma than in normal gastric mucosal tissues (t = 0.4161, P<0.01).Immunohistochemistry revealed that endothelial nitric oxide synthase (eNOS) expressed in all samples of normal gastric mucosa, but only 6 cases of 85 gastric cancer specimens showed weak positive immunohistochemical reactions to eNOS (20%). Inducible nitric oxide synthase (iNOS) was expressed strongly in human gastric carcinoma (81.2%). In situ hybridization analysis showed that iNOS mRNA expression was significantly stronger than eNOS mRNA expression in gastric cancer tissue (x2 = 10.23, P<0.01). The expression of iNOS in gastric cancer was associated with differentiation, clinical stages or lymph node metastases (r= 0.3426, P<0.05). However,iNOS expression did not correlate with histological classifications and morphological types. The expression of iNOS was significantly correlated with p53 or PCNA expression (r = 0.3612, P<0.05). The expression of neuronal nitric oxide synthase (nNOS) was not examined by immunohistochemistry and in situ hybridization in gastric cancer specimens and normal gastric mucosa.CONCLUSION: In human gastric cancer, there is an enhanced expression of iNOS, but not of eNOS. NOS promotes the proliferation of tumor cells and plays an important role in gastric cancer spread

  8. Human NTH1 physically interacts with p53 and proliferating cell nuclear antigen

    International Nuclear Information System (INIS)

    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

  9. PCNA and p53 expression in oral leukoplakia with different degrees of keratinization Expressão do PCNA e p53 em leucoplasias de mucosa jugal com diferentes graus de queratinização

    Directory of Open Access Journals (Sweden)

    Melaine de Almeida Lawall

    2006-08-01

    Full Text Available Leukoplakias are oral lesions that may have many clinical and histological aspects and they are usually associated with malignancy when dysplastic alterations are shown. However, these transformations may occur in non-dysplastic lesions that show harmless clinical aspect. For this reason, the proposal was to study the p53 and PCNA immunohistochemical expression in non-dysplastic leukoplakias, trying to correlate the results only with the epithelial keratinization degree. For this, 24 leukoplakias degrees I, II and III of Grinspan were used, all of them located in oral mucosa. Most of the leukoplakias showed p53 and PCNA expression in their different keratinization degrees. The p53 marking was confined to the basal and parabasal layers, while the PCNA marking occurred in practically all epithelial layers. The expression pattern of these markers was histologically and statistically similar between the lesions with these keratinization variations. It was evident that non-dysplastic epithelium of leukoplakias showed submicroscopical signs of alterations that lead to malignant transformation, and that the keratinization degree did not correlate to a greater risk of this event.As leucoplasias são lesões orais que podem apresentar vários aspectos clínicos e histológicos e são associadas à malignidade geralmente quando apresentam alterações displásicas. Contudo, essas transformações podem ocorrer em lesões sem displasia que apresentam aspecto clínico inocente. Por esse motivo nossa proposta foi estudar a expressão imuno-histoquímica do p53 e PCNA em leucoplasias sem displasias, buscando correlacionar os resultados apenas com o grau de queratinização epitelial. Para isso foram utilizadas as leucoplasias Grau I, II e III de Grinspan, num total de 24 lesões, todas localizadas em mucosa jugal. A maior parte das leucoplasias, em seus diferentes graus de queratinização, apresentou expressão de p53 e PCNA. A marcação do p53 restringiu

  10. Expressions of PCNA, p53, p21WAF-1 and cell proliferation in fetal esophageal epithelia: Comparative study with adult esophagea lesions from subjects at high-incidence area for esophageal cancer in Henan, North China

    Institute of Scientific and Technical Information of China (English)

    Ying Xing; Yu Ning; Li-Qiang Ru; Li-Dong Wang

    2003-01-01

    AIM: To characterize the expression of p53, p21WAF-1 and proliferation-cell-nuclear-antigen (PCNA) in fetal esophageal epithelia and to determine the role of these genes in proliferation of fetal and adult esophageal epithelial cells.METHODS: Immunohistochemical avdin-biotin peroxidase complex (ABC) method was applied to 31 cases of fetal esophageal specimens and 194 cases of adult esophageal specimens to detect the expression of p53, p21WAF-1 and PCNA in fetal and adult esophageal epithelia.RESULTS: Both the PCNA positive immunostaining cell number and PCNA positive immunostaining rate in fetal esophageal epithelia (506±239) were significantly higher than those in adults,including normal epithelia (200±113) and epithelia with basal cell hyperplasia (BCH) (286±150) (P<0.05, ttest). However,the number of PCNA positive immunostaining cells in adult esophageal dysplasia (719±389) and squamous cell carcinoma (SCC) (1261±545) was apparently higher than that in fetal esophageal epithelia (506±239) (P<0.05, ttest). The positive immunostaining rate of P53 was 10 % (3/3L) in fetal esophageal epithelia, which was significantly lower than that in adult normal esophageal epithelia (50 %), adult epithelia with basal cell hyperplasia (62 %), dysplasia (73 %) and squamous cell carcinoma (86 %) (P<0.05, Fisher′s exact test). No p21WAF-1positive immunostaining cells were observed in fetal esophageal epithelia. However, p21WAF-1 positive immunostaining cells were observed in adult esophagus with 39 % (11/28) in normal, 38% (14/37) in BCH, 27 % (3/11) in DYS and 14 % (1/7) in SCC.CONCLUSION: PCNA could act as an indicator accurately reflecting the high proliferation status of fetal esophageal epithelium. p53 may play an important role in growth and differentiation of fetal esophageal epithelium. p21WAF-1 may have no physiological function in development of fetal esophageal epithelium.

  11. Construction of a triple modified p53 containing DNA vaccine to enhance processing and presentation of the p53 antigen

    NARCIS (Netherlands)

    Hospers, Geke A. P.; Meijer, Coby; Dam, Wendy A.; Roossink, Frank; Mulder, Nanno H.

    2009-01-01

    More effective and less toxic treatments are urgently needed in the treatment of patients with cancer. The turnout suppressor protein p53 is a tumour-associated antigen that could serve that purpose when applied in an immunologic approval to cancer. It is mutated in similar to 50% of the tumours res

  12. Molecular markers of cancer in cartilaginous fish: immunocytochemical study of PCNA, p-53, myc and ras expression in neoplastic and hyperplastic tissues from free ranging blue sharks, Prionace glauca (L.).

    Science.gov (United States)

    Borucinska, J D; Schmidt, B; Tolisano, J; Woodward, D

    2008-02-01

    Archival formalin-fixed tissues from wild-caught adult blue sharks, Prionace glauca (L.), were used for immunocytochemical detection of proliferating cell nuclear antigen (PCNA), two oncoproteins from the oncogenes c-myc and pan-ras, and a protein product from the tumour suppressor gene p-53. All sharks were caught during summer months between 2000 and 2006 by recreational fishermen off the USA coast in the northwestern Atlantic. The sharks were necropsied on landing and selected organ samples were collected into elasmobranch formalin and processed for paraffin embedding and light microscopy. Paraffin-embedded sections from collected tissue were both stained with haematoxylin and eosin and processed by immunocytochemical techniques using antibodies raised against the PCNA, p-ras, c-myc and p-53 proteins. The lesions examined in this study included two well differentiated adenomatous gastric polyps, a testicular capsular mesothelioma, a gingival fibropapilloma with elements of ameloblastoma, three liver tumours, two pericardial fibropapillomas and six cases of proliferative serositis (pericarditis and peritonitis). Normal and hyperplastic tissues from blue sharks, and human neoplastic tissues served as negative and positive controls, respectively. We detected upregulation of PCNA in many neoplastic, one dysplastic and in some hyperplastic lesions, and positive p-ras and c-myc signals in some of the neoplastic lesions. None of the examined tissues showed positive p-53 signalling. This is the first literature report on immunocytochemical detection of molecular markers of cancer in sharks and in fish of the class Chondrichthyes. PMID:18234018

  13. Intestinal Dysplasia Induced by Simian Virus 40 T Antigen Is Independent of p53

    Science.gov (United States)

    Markovics, Jennifer A.; Carroll, Patrick A.; Robles, M. Teresa Sáenz; Pope, Hannah; Coopersmith, Craig M.; Pipas, James M.

    2005-01-01

    Transgenic mice expressing simian virus 40 large T antigen in enterocytes develop intestinal hyperplasia that progresses to dysplasia with age. Hyperplasia is dependent on T antigen binding to the retinoblastoma (pRb) family of tumor suppressor proteins. Mice expressing a truncated T antigen that inactivates the pRb-family, but is defective for binding p53, exhibit hyperplasia but do not progress to dysplasia. We hypothesized that the inhibition of the pRb family leads to entry of enterocytes into the cell cycle, resulting in hyperplasia, while inactivation of p53 is required for progression to dysplasia. Therefore, we examined T antigen/p53 complexes from the intestines of transgenic mice. We found that T antigen did not induce p53 stabilization, and we could not detect T antigen/p53 complexes in villus enterocytes. In contrast, T antigen expression led to a large increase in the levels of the cyclin-dependent kinase inhibitor p21. Furthermore, mice in which pRb was inactivated by a truncated T antigen in a p53 null background exhibited intestinal hyperplasia but no progression to dysplasia. These data indicate that loss of p53 function does not play a role in T antigen-induced dysplasia in the intestine. Rather, some unknown function of T antigen is essential for progression beyond hyperplasia. PMID:15919904

  14. Expression and its significance of PCNA, p53, P-gp in cervical carcinoma before and after neoadjuvant chemotherapy%NACT前后宫颈癌组织中PCNA、p53、P-gp的表达变化及意义

    Institute of Scientific and Technical Information of China (English)

    战姝妍; 姚军

    2011-01-01

    Objective To explore the expression of proliferating cell nuclear antigen (PCNA), tumor suppressor gene p53 and P-glycoprotein (P-gp) in cervical cancer before and after neoadjuvant chemotherapy, and investigate its relationship with the effect of chemotherapy. Methods 60 patients with locally advanced cervical cancer were treated with neoadjuvant chemotherapy (NACT). Expression of PCNA, p53, P-gp in cervical cancer before and after chemotherapy were detected by immunohistochemical staining. Results Positive rate of PCNA, p53 and P-gp in cervical cancer before chemotherapy were 86.7% , 60.0% , 56.7% , respectively, after chemotherapy there that 93.3% , 83.3% , 83.3%. Expression of p53, P-pg in cervical cancer before NACT compared with after NACT, all P<0.05. Efficient of NACT in patients with p53, P-pg expression negative before NACT compared to positive, all P <0.05. Conclusions Significantly difference are found in expression levels of p53, P-gp in cervical cancer before and after NACT. Expression levels of p53, P-gp cancer chemotherapy can be used as a predictor of sensitivity.%目的 探讨宫颈癌新辅助化疗(NACT)前后增殖细胞核抗原(PCNA)、抑癌基因p53和P-糖蛋白(P-gp)在宫颈癌组织中的表达变化及其与化疗疗效的关系.方法 对60例局部晚期宫颈癌患者行NACT,采用免疫组化法检测化疗前后宫颈癌组织中的PCNA、p53、P-gp.结果 化疗前宫颈鳞癌组织中PCNA、p53和P-gp阳性表达率分别为86.7%、60.0%、56.7%;化疗后分别为93.3%、83.3%、83.3%,化疗前后p53、P-gp阳性率相比,P均<0.05.NACT前宫颈癌组织p53、P-gp表达阴性者NACT有效率与p53、P-gp表达阳性者相比,P均<0.05.结论 NACT前后宫颈癌组织中p53、P-gp的表达水平有显著差异,p53、P-gp的表达水平可作为宫颈癌化疗疗效敏感性的预测指标.

  15. p53 targets simian virus 40 large T antigen for acetylation by CBP.

    Science.gov (United States)

    Poulin, Danielle L; Kung, Andrew L; DeCaprio, James A

    2004-08-01

    Simian virus 40 (SV40) large T antigen (T Ag) interacts with the tumor suppressor p53 and the transcriptional coactivators CBP and p300. Binding of these cellular proteins in a ternary complex has been implicated in T Ag-mediated transformation. It has been suggested that the ability of CBP/p300 to modulate p53 function underlies p53's regulation of cell proliferation and tumorigenesis. In this study, we provide further evidence that CBP activity may be mediated through its synergistic action with p53. We demonstrate that SV40 T Ag is acetylated in vivo in a p53-dependent manner and T Ag acetylation is largely mediated by CBP. The acetylation of T Ag is dependent on its interaction with p53 and on p53's interaction with CBP. We have mapped the site of acetylation on T Ag to the C-terminal lysine residue 697. This acetylation site is conserved between the T antigens of the human polyomaviruses JC and BK, which are also known to interact with p53. We show that both JC and BK T antigens are also acetylated at corresponding sites in vivo. While other proteins are known to be acetylated by CBP/p300, none are known to depend on p53 for acetylation. T Ag acetylation may provide a regulatory mechanism for T Ag binding to a cellular factor or play a role in another aspect of T Ag function. PMID:15254196

  16. p53 Targets Simian Virus 40 Large T Antigen for Acetylation by CBP

    OpenAIRE

    Poulin, Danielle L.; Kung, Andrew L.; DeCaprio, James A.

    2004-01-01

    Simian virus 40 (SV40) large T antigen (T Ag) interacts with the tumor suppressor p53 and the transcriptional coactivators CBP and p300. Binding of these cellular proteins in a ternary complex has been implicated in T Ag-mediated transformation. It has been suggested that the ability of CBP/p300 to modulate p53 function underlies p53's regulation of cell proliferation and tumorigenesis. In this study, we provide further evidence that CBP activity may be mediated through its synergistic action...

  17. 星形细胞瘤中P53、VEGF及PCNA表达的相关性及其与预后的关系%Expressions of P53, vascular endothelial growth factor and proliferating cell number antigen in astrocytomas and prognosis of these patients

    Institute of Scientific and Technical Information of China (English)

    廖志东; 朱文标; 谢寿城; 黄艳芳; 郑少秋

    2014-01-01

    目的 研究星形细胞瘤中P53、血管内皮因子(VEGF)及增殖细胞核抗原(PCNA)表达的相关性及其与预后的关系.方法 免疫组化染色SP法检测梅州市人民医院自2002年5月至2010年5月首次手术切除的126例不同级别原发性星形细胞瘤标本P53、VEGF及PCNA的表达,分析其相关性及其预后意义.结果 P53、VEGF及PCNA在不同级别的星形细胞瘤中表达不同,随着级别的提高而表达强度增加,差异有统计学意义(P<0.05);P53与PCNA、P53与VEGF之间表达呈正相关关系(r=0.608,P=0.000; r=0.432,P=0.001).相同级别星形细胞瘤中,P53阳性表达患者预后较差,生存率比较差异有统计学意义(P<0.05),VEGF及PCNA与预后无关.结论 星形细胞瘤级别提高,P53、VEGF及PCNA的表达强度增加;P53可作为判断肿瘤预后的指标之一.%Objective To study the expressions of P53,vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA) in astrocytomas and their relationships with prognosis of these patients.Methods Immunohistochemical SP method was employed to detect the P53,VEGF and PCNA expression in 126 cases of human brain astrocytomas of different grades,collected in our hospital from May 2002 to May 2010; their correlations and their significance in the prognosis in these patients were analyzed.Results P53,VEGF,and PCNA expressed differently in astrocytomas of different grades,enjoying a positive relation with grades (P<0.05); positive correlations of between P53 expression and both VEGF and PCNA expressions (r=0.608,P=0.000; r=0.432,P=0.001).In patients with the same grade of astrocytoma,those having positive P53 expression enjoyed poorer prognosis and lower survival rate with significant difference (P<0.05); while VEGF and PCNA expressions had no correlation with the progonosis.Conclusion The expressions of PCNA,VEGF and P53 are closely associated with grade of the astrocytomas,and only P53 expression is an indicator of

  18. Antigen-specific immunotherapy in ovarian cancer and p53 as tumor antigen

    NARCIS (Netherlands)

    Vermeij, Renee; Leffers, Ninke; Melief, Cornelis J.; Daemen, Toos; Nijman, Hans W.

    2012-01-01

    This review discusses the results of different immunization strategies, identifies possible drawbacks in study design and provides potential solutions for augmentation of clinical efficacy. A potential target for cancer immunotherapy is p53, as approximately 50% of ovarian cancer cells carry p53 mut

  19. Epstein-Barr virus nuclear antigen 3C targets p53 and modulates its transcriptional and apoptotic activities

    International Nuclear Information System (INIS)

    The p53 tumor suppressor gene is one of the most commonly mutated genes in human cancers and the corresponding encoded protein induces apoptosis or cell-cycle arrest at the G1/S checkpoint in response to DNA damage. To date, previous studies have shown that antigens encoded by human tumor viruses such as SV40 large T antigen, adenovirus E1A and HPV E6 interact with p53 and disrupt its functional activity. In a similar fashion, we now show that EBNA3C, one of the EBV latent antigens essential for the B-cell immortalization in vitro, interacts directly with p53. Additionally, we mapped the interaction of EBNA3C with p53 to the C-terminal DNA-binding and the tetramerization domain of p53, and the region of EBNA3C responsible for binding to p53 was mapped to the N-terminal domain of EBNA3C (residues 130-190), previously shown to interact with a number of important cell-cycle components, specifically SCFSkp2, cyclin A, and cMyc. Furthermore, we demonstrate that EBNA3C substantially represses the transcriptional activity of p53 in luciferase based reporter assays, and rescues apoptosis induced by ectopic p53 expression in SAOS-2 (p53-/-) cells. Interestingly, we also show that the DNA-binding ability of p53 is diminished in the presence of EBNA3C. Thus, the interaction between the p53 and EBNA3C provides new insights into the mechanism(s) by which the EBNA3C oncoprotein can alter cellular gene expression in EBV associated human cancers.

  20. Immunologic aspect of ovarian cancer and p53 as tumor antigen

    Directory of Open Access Journals (Sweden)

    van der Burg SH

    2005-09-01

    Full Text Available Abstract Ovarian cancer represents the fifth leading cause of death from all cancers for women. During the last decades overall survival has improved due to the use of new chemotherapy schedules. Still, the majority of patients die of this disease. Research reveals that ovarian cancer patients exhibit significant immune responses against their tumor. In this review the knowledge obtained thus far on the interaction of ovarian cancer tumor cells and the immune system is discussed. Furthermore the role of p53 as tumor antigen and its potential role as target antigen in ovarian cancer is summarized. Based on the increased knowledge on the role of the immune system in ovarian cancer major improvements are to be expected of immunotherapy based treatment of this disease.

  1. p53、PCNA表达与膀胱移行细胞癌预后的关系%Relationship between p53,PCNA expression and prognosis in transitional cell carcinoma of bladder

    Institute of Scientific and Technical Information of China (English)

    才胜勇; 黄翼然

    2000-01-01

    目的 探讨p53及PCNA表达与膀胱移行细胞癌(TCC)预后的关系.方法 LSAB法检测49例TCC及8例正常膀胱粘膜组织中p53、PCNA表达,分析p53与PCNA表达在TCC中的预后价值.结果 p53在正常膀胱粘膜组织中均为阴性表达,在TCC组织中表达阳性率为40.8%(20/49),两者比较差异有显著性(P<0.05).p53在T1及T2~4期肿瘤组织中表达阳性率分别为31.4%,64.3%,两者比较差异有显著性(P<0.05);在Ⅰ、Ⅱ、Ⅲ级TCC组织中阳性率分别为13.3%、50.0%、60.0%,组间差异有高度显著性(P<0.01).p53与PCNA表达呈正相关(P<0.05).p53阳性表达TCC的复发率、恶性进展率均高于p53阴性表达的TCC(P<0.05).结论 在TCC中p53表达可作为肿瘤高侵袭力的指标,p53与PCNA正相关,p53阳性表达的TCC预后差.

  2. Wild-type, but not mutant, human p53 proteins inhibit the replication activities of simian virus 40 large tumor antigen.

    OpenAIRE

    Friedman, P N; Kern, S. E.; Vogelstein, B; Prives, C

    1990-01-01

    Murine p53 blocks many of the replication activities of simian virus 40 (SV40) large tumor antigen (T antigen) in vitro. As murine cells do not replicate SV40 DNA, it was of interest to determine how p53 from permissive human cells functions. Recombinant baculoviruses encoding either the wild-type form of human p53 or a mutant p53 cloned from a human tumor cell line were constructed, and p53 proteins were purified from infected insect cells. Surprisingly, we found that wild-type human p53 was...

  3. Urinary bladder lesions after the chernobyl accident. Immunohistochemical assessment of p53, proliferating cell nuclear antigen, cyclin D1 and p21WAF1/Cip1

    International Nuclear Information System (INIS)

    During the 11-year period subsequent to the Chernobyl accident, the incidence of urinary bladder cancer in Ukraine has increased from 26.2 to 36.1 per 100,000 population. Cesium-137 (137Cs) accounts for 80-90% of the incorporated radioactivity in this population, which has been exposed to long-term, low-dose ionizing radiation, and 80% of the more labile pool of cesium is excreted via the urine. The present study was performed to evaluate the histopathological features and the immunohistochemical status of p53, p21WAF1/Cip1, cyclin D1 and PCNA (proliferating cell nuclear antigen) in urinary bladder mucosa of 55 males (49-92 years old) with benign prostatic hyperplasia who underwent surgery in Kiev, Ukraine, in 1995 and 1996. Group I (28 patients) inhabiting radiocontaminated areas of the country, group II (17 patients) from Kiev city with less radiocontamination and a control group III (10 patients) living in so-called ''clean'' areas of Ukraine were compared. In groups I and II, an increase in multiple areas of moderate or severe dysplasia or carcinoma in situ was seen in 42 (93%) of 45 cases. In addition, two small transitional cell carcinomas were found in one patient in each of groups I and II. Nuclear accumulation of p53, PCNA, cyclin D1, and to a lesser extent p21WAF1/Cip1, was significantly increased in both groups I and II as compared with the control group III, indicating possible transformation events or enhancement of repair activities, that may precede the defect in the regulatory pathway itself, at least in the G1 phase of the cell cycle. Our results suggest that early malignant transformation is taking place in the bladder urothelium of people in the radiocontaminated areas of Ukraine and that this could possibly lead sometime in the future to an increased incidence of urinary bladder cancer. (author)

  4. Stoichiometric complex formation by proliferating cell nuclear antigen (PCNA) and its interacting protein: purification and crystallization of the DNA polymerase and PCNA monomer mutant complex from Pyrococcus furiosus

    International Nuclear Information System (INIS)

    A stable stoichiometric complex of archaeal DNA polymerase with proliferating cell nuclear antigen (PCNA) was formed using a PCNA monomer mutant and the complex was successfully crystallized. Replicative DNA polymerase interacts with processivity factors, the β-subunit of DNA polymerase III or proliferating cell nuclear antigen (PCNA), in order to function with a long template DNA. The archaeal replicative DNA polymerase from Pyrococcus furiosus interacts with PCNA via its PCNA-interacting protein (PIP) motif at the C-terminus. The PCNA homotrimeric ring contains one PIP interacting site on each monomer and since the ring can accommodate up to three molecules simultaneously, formation of a stable stoichiometric complex of PCNA with its interacting protein has been difficult to control in vitro. A stable complex of the DNA polymerase with PCNA, using a PCNA monomer mutant, has been purified and crystallized. The best ordered crystal diffracted to 3.0 Å resolution using synchrotron radiation. The crystals belong to space group P21212, with unit-cell parameters a = 225.3, b = 123.3, c = 91.3 Å

  5. Proliferating cell nuclear antigen (Pcna) as a direct downstream target gene of Hoxc8

    Energy Technology Data Exchange (ETDEWEB)

    Min, Hyehyun; Lee, Ji-Yeon; Bok, Jinwoong; Chung, Hyun Joo [Department of Anatomy, Embryology Laboratory, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Kim, Myoung Hee, E-mail: mhkim1@yuhs.ac [Department of Anatomy, Embryology Laboratory, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of)

    2010-02-19

    Hoxc8 is a member of Hox family transcription factors that play crucial roles in spatiotemporal body patterning during embryogenesis. Hox proteins contain a conserved 61 amino acid homeodomain, which is responsible for recognition and binding of the proteins onto Hox-specific DNA binding motifs and regulates expression of their target genes. Previously, using proteome analysis, we identified Proliferating cell nuclear antigen (Pcna) as one of the putative target genes of Hoxc8. Here, we asked whether Hoxc8 regulates Pcna expression by directly binding to the regulatory sequence of Pcna. In mouse embryos at embryonic day 11.5, the expression pattern of Pcna was similar to that of Hoxc8 along the anteroposterior body axis. Moreover, Pcna transcript levels as well as cell proliferation rate were increased by overexpression of Hoxc8 in C3H10T1/2 mouse embryonic fibroblast cells. Characterization of 2.3 kb genomic sequence upstream of Pcna coding region revealed that the upstream sequence contains several Hox core binding sequences and one Hox-Pbx binding sequence. Direct binding of Hoxc8 proteins to the Pcna regulatory sequence was verified by chromatin immunoprecipitation assay. Taken together, our data suggest that Pcna is a direct downstream target of Hoxc8.

  6. Architecture of the DNA polymerase B-proliferating cell nuclear antigen (PCNA)-DNA ternary complex

    OpenAIRE

    Mayanagi, Kouta; Kiyonari, Shinichi; Nishida, Hirokazu; Saito, Mihoko; Kohda, Daisuke; Ishino, Yoshizumi; Shirai, Tsuyoshi; Morikawa, Kosuke

    2011-01-01

    DNA replication in archaea and eukaryotes is executed by family B DNA polymerases, which exhibit full activity when complexed with the DNA clamp, proliferating cell nuclear antigen (PCNA). This replication enzyme consists of the polymerase and exonuclease moieties responsible for DNA synthesis and editing (proofreading), respectively. Because of the editing activity, this enzyme ensures the high fidelity of DNA replication. However, it remains unclear how the PCNA-complexed enzyme temporally ...

  7. Targeting cytosolic proliferating cell nuclear antigen (PCNA in neutrophil-dominated inflammation

    Directory of Open Access Journals (Sweden)

    Alessia eDe Chiara

    2012-10-01

    Full Text Available New therapeutic approaches that can accelerate neutrophil apoptosis under inflammatory conditions to enhance the resolution of inflammation are now under study. Neutrophils are deprived of proliferative capacity and have a tightly controlled lifespan to avoid their persistence at the site of injury. We have recently described that the proliferating cell nuclear antigen (PCNA, a nuclear factor involved in DNA replication and repair of proliferating cells is a key regulator of neutrophil survival. In this review, we will try to put into perspective the physiologic relevance of PCNA in neutrophils. We will discuss key issues such as molecular structure, post-translational modifications, based on our knowledge of nuclear PCNA, assuming that similar principles governing its function are conserved between nuclear and cytosolic PCNA. The example of cystic fibrosis that features one of the most intense neutrophil-dominated pulmonary inflammation will be discussed. We believe that through an intimate comprehension of the cytosolic PCNA scaffold based on nuclear PCNA knowledge, novel pathways regulating neutrophil survival can be unraveled and innovative agents can be developed to dampen inflammation where it proves detrimental.

  8. Survival of ovarian cancer patients overexpressing the tumour antigen p53 is diminished in case of MHC class I down-regulation

    NARCIS (Netherlands)

    Leffers, Ninke; Lambeck, Annechien J. A.; de Graeff, Pauline; Bijlsma, Astrid Y.; Daemen, Toos; van der Zee, Ate G. J.; Nijman, Hans W.

    2008-01-01

    Objectives. The adaptive immune system seems to play an essential role in the natural course of ovarian cancer. Aim of this study was to establish whether disease-specific survival for patients expressing the tumour antigen p53 is influenced by MHC class I expression or the presence of p53 autoantib

  9. Simulated Microgravity Promotes Cell Apoptosis Through Suppressing Uev1A/TICAM/TRAF/NF-κB-Regulated Anti-Apoptosis and p53/PCNA- and ATM/ATR-Chk1/2-Controlled DNA-Damage Response Pathways.

    Science.gov (United States)

    Zhao, Tuo; Tang, Xin; Umeshappa, Channakeshava Sokke; Ma, Hong; Gao, Haijun; Deng, Yulin; Freywald, Andrew; Xiang, Jim

    2016-09-01

    Microgravity has been known to induce cell death. However, its underlying mechanism is less studied. In this study, BL6-10 melanoma cells were cultured in flasks under simulated microgravity (SMG). We examined cell apoptosis, and assessed expression of genes associated with apoptosis and genes regulating apoptosis in cells under SMG. We demonstrate that SMG induces cell morphological changes and microtubule alterations by confocal microscopy, and enhances apoptosis by flow cytometry, which was associated with up- and down-regulation of pro-apoptotic and anti-apoptotic genes, respectively. Moreover, up- and down-regulation of pro-apoptotic (Caspases 3, 7, 8) and anti-apoptotic (Bcl2 and Bnip3) molecules was confirmed by Western blotting analysis. Western blot analysis also indicates that SMG causes inhibition of an apoptosis suppressor, pNF-κB-p65, which is complemented by the predominant localization of NF-κB-p65 in the cytoplasm. SMG also reduces expression of molecules regulating the NF-κB pathway including Uev1A, TICAM, TRAF2, and TRAF6. Interestingly, 10 DNA repair genes are down-regulated in cells exposed to SMG, among which down-regulation of Parp, Ercc8, Rad23, Rad51, and Ku70 was confirmed by Western blotting analysis. In addition, we demonstrate a significant inhibition of molecules involved in the DNA-damage response, such as p53, PCNA, ATM/ATR, and Chk1/2. Taken together, our work reveals that SMG promotes the apoptotic response through a combined modulation of the Uev1A/TICAM/TRAF/NF-κB-regulated apoptosis and the p53/PCNA- and ATM/ATR-Chk1/2-controlled DNA-damage response pathways. Thus, our investigation provides novel information, which may help us to determine the cause of negative alterations in human physiology occurring at spaceflight environment. J. Cell. Biochem. 117: 2138-2148, 2016. © 2016 Wiley Periodicals, Inc. PMID:26887372

  10. Expression of p21waf1, p53 and proliferating cell nuclear antigen in lung cancer%p21waf1和p53及增殖细胞核抗原在肺癌组织中的表达

    Institute of Scientific and Technical Information of China (English)

    丁续红; 吴小军; 田素梅; 杨炯; 李清泉

    2005-01-01

    蛋白作用不协调.%BACKGROUND: The different level of proteins regulating cell cycle and theircorrelation is the main criteria to differentiate the benign and malignant cellular proliferation.OBJECTIVE: To investigate the expression status of p21waf1 and p53 in lung cancer as well as proliferating cell nuclear antigen (PCNA)DESIGN:A case-control study.SETTING: Department of Respiratory Medicine, Renmin Hospital ,Wuhan UniversityPAITICIPANTS:This case-control study involved 135 patients who underwent lobectomy or fiberoptic bronchoscopy for primary lung cancer or benign chronic pulmonary diseases at Renmin Hospital of Wuhan University from October 1996 through May 1999. They were divided into two groups: lung cancer group (76 patients, including 56 men and 20 women,aged 18-74 years of age) and chronic pulmonary diseases group (59 cases,including 42 men and 17 women, aged 16-70 years of age).METHODS: Phosphate buffer solution replaced the first antibody as the negative control. Immunohistochemistry was performed using a modified streptavidin-biotinylated peroxidase technique according to the manufacturer's recommendations (Maxim Corporation). For p21waf1 staining, we used hydrated autoclaving as a pretreatment. Antigen retrieval was performed in a standard microwave unit for p53 staining. PCNA staining did not need The ratio of the positive cells indicated by yellowish brown nucleus due to staining was counted for 5 successive high-fold microscopic fields: when it was≥ 10%, it was taken as positive; when it was <10%, it was regarded as high-fold microscopic fields for the percentage of the positive cells indicated by yellowish brown nucleus due to staining in each field, and the average value of the five fields was taken as labeling index (LI) for proliferated nuclear antigens.MAIN OUTCOME MEASURES: The expression leyels of p21waf1, p53and PCNA in lung cancer.cancer were 75% (57/76) and 47%(36/76) respectively. The labeling index of PCNA in lung cancer group was significantly higher than that of

  11. Wild-Type p53 Enhances Efficiency of Simian Virus 40 Large-T-Antigen-Induced Cellular Transformation▿

    OpenAIRE

    Hermannstädter, Andrea; Ziegler, Christine; Kühl, Marion; Deppert, Wolfgang; Tolstonog, Genrich V.

    2009-01-01

    Abortive infection of BALB/c mouse embryo fibroblasts differing in p53 gene status (p53+/+ versus p53−/−) with simian virus 40 (SV40) revealed a quantitatively and qualitatively decreased transformation efficiency in p53−/− cells compared to p53+/+ cells, suggesting a supportive effect of wild-type (wt) p53 in the SV40 transformation process. SV40 transformation efficiency also was low in immortalized p53−/− BALB/c 10-1 cells but could be restored to approximately the level in immortalized p5...

  12. Influence of radiotherapy on expression of the proliferating cell nuclear antigen (PCNA) and c-fos in human cervical cancer

    International Nuclear Information System (INIS)

    Objective: To investigate changes of proliferating cell nuclear antigen (PCNA) expression in human cervical cancer following irradiation. Methods: Immunohistochemical staining for PCNA was performed in frozen sections of formalin-fixed cervical cancer biopsy tissues. Results: The majority of the cancer cells showed PCNA-immunoreactivity before irradiation. Following irradiation (30-40 Gy/15-20 f) PCNA-immuno-positive staining was hardly detectable in most of the cancer cells. The PCNA-immunoreactivity, however, increased after radiotherapy, and moderate or heavy immuno-positive staining for PCNA was seen in irradiated mesenchymal tissue cells. On the other hand, after irradiation Fos-immunoreactivity decreased remarkably, and Fos-immuno-positive staining was hardly detectable in most of cancer cells. No obvious change in Fos-immuno-reactivity, however, was seen in mesenchymal connective tissue following irradiation. Conclusion: Irradiation inhibits PCNA and c-fos expression in cervical cancer cells whereas it induces the expression of PCNA in mesenchymal tissue cells. The present results suggest that expression of PCNA and c-fos may be regarded as a molecular marker for evaluating the cancer cell proliferation and mesenchymal tissue repair during radiotherapy of human cervical cancer

  13. pRB-Dependent, J Domain-Independent Function of Simian Virus 40 Large T Antigen in Override of p53 Growth Suppression

    OpenAIRE

    Gjoerup, Ole; Chao, Herta; DeCaprio, James A.; Roberts, Thomas M.

    2000-01-01

    Simian virus 40 (SV40) large T antigen (LT) can immortalize and transform many cell types. These activities are attributed in large part to the binding and functional inactivation by LT of two major tumor suppressors: p53 and the retinoblastoma protein, pRB. Most effects of LT on pRB have been shown to additionally require an intact J domain, which mediates binding to Hsc70. We show here that the J domain is not required for p53 override in full-length LT. Although LT binds p53, it was shown ...

  14. Effects of p53 overexpression on neoplastic cell pro-liferation and apoptosis in thymic carcinoma

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To investigate p53 overexpression and its correlation with neoplastic cell proliferation and apoptosis in 20 thymic carcinomas. Methods: 20 surgical samples of thymic carcinoma were collected randomly during the past 15 years in the Guangzhou area. Immunohistochemical staining was performed using LSAB method with anti-p53 monoclonal antibody (DO-7) and proliferating cell nuclear antigen (clone PC 10) as primary antibodies. The p53 index was indicated by the number of p53 positive cells among 100 carcinoma cells. More than 25 percentage of p53 positive cells found in tissue sections was recognized as p53 overexpression. Carcinoma cell proliferation activity was assayed by PCNA index (PI), and apoptosis degree was evaluated by TUNEL (TdT-mediated dUTP-X nick end labeling) index (TI) using Boehringer Mannheim In Situ Death Detection Kit. Results: P53 positive cells could be found in vast majority of thymic carcinomas (19/20) and the overexpression rate reached 35% (7/20). The median PI (40%) of 7 cases with p53 overexpression was higher than that (31%) of 13 cases without p53 overexpression, but there was no statistical significance that existed between these two data (P>0.05). The median TI (0.5/HPF) of 7 p53 overexpression cases was much lower than that (4.5/HPF) of 13 non-overexpression cases, and there was a significant difference statistically (P<0.05). Conclusion: p53 expression was a frequent finding in thymic carcinoma cells, and the p53 overexpression which might represent p53 inactivation or gene mutation was often involved in thymic carcino-genesis. The median PCNA index of p53 overexpression group was higher than that of non-overexpression group though there existed no statistical difference. This indicates that the inhibiting function of p53 on cell proliferation seemed lost in p53 overexpressed thymic carcinomas. It is worthy to be specially mentioned that the inducing function of p53 on cell apoptosis was markedly lost in p53 overexpressed thymic

  15. Immunohistochemical study of p53 overexpression in radiation-induced colon cancers

    International Nuclear Information System (INIS)

    The expressions of p53 and proliferating cell nuclear antigen (PCNA) were studied immunohistochemically from paraffin sections of 7 cases (9 lesions) of radiation-induced colon cancer and 42 cases of spontaneous colon cancer. Age distribution of radiation-induced and spontaneous colon cancer were 68.1 years (range, 56 to 77 years) and 67.4 years (range, 31 to 85 years), respectively. Among the radiation-induced colon cancers, there were 3 lesions of mucinous carcinoma (33%), a much higher than found for spontaneous mucinous cancer. Immunohistochemically, p53 protein expression was detected in 7/9 (78%) of radiation-induced cancers and in 23/42 (55%) of spontaneous colon cancers. χ2 analysis found no significant differences between radiation-induced and spontaneous colon cancers in age distribution or p53-positive staining for frequency, histopathology, or Dukes'' classification. In radiation colitis around the cancers including aberrant crypts, spotted p53 staining and abnormal and scattered PCNA-positive staining were observed. In histologically normal cells, p53 staining was almost absent and PCNA-positive staining was regularly observed in the lower half of the crypt. In radiation colitis including aberrant glands, cellular proliferation increased and spotted p53 expression was observed. This study suggests that radiation colitis and aberrant glands might possess malignant potential and deeply associate with carcinogenesis of radiation-induced colon cancer. (author)

  16. Adsorption according to the Langmuir-Freundlich model is the detection mechanism of the antigen p53 for early diagnosis of cancer.

    Science.gov (United States)

    Soares, Juliana Coatrini; Soares, Andrey Coatrini; Pereira, Paulo Augusto Raymundo; Rodrigues, Valquiria da Cruz; Shimizu, Flavio Makoto; Melendez, Matias Eliseo; Scapulatempo Neto, Cristovam; Carvalho, André Lopes; Leite, Fábio L; Machado, Sergio A S; Oliveira, Osvaldo N

    2016-03-16

    Biosensors for early detection of cancer biomarkers normally depend on specific interactions between such biomarkers and immobilized biomolecules in the sensing units. Though these interactions are expected to yield specific, irreversible adsorption, the underlying mechanism appears not to have been studied in detail. In this paper, we show that adsorption explained with the Langmuir-Freundlich model is responsible for detection of the antigen p53 associated with various types of cancers. Irreversible adsorption was proven between anti-p53 antibodies immobilized on the biosensors and the antigen p53, with the adequacy of the Langmuir-Freundlich model being confirmed with three independent experimental methods, viz. polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), nanogravimetry using a quartz crystal microbalance and electrochemical impedance spectroscopy. The method based on this irreversible adsorption was sufficiently sensitive (limit of detection of 1.4 pg mL(-1)) for early diagnosis of Hodgkin lymphoma, pancreatic and colon carcinomas, and bladder, ovarian and lung cancers, and could distinguish between MCF7 cells containing the antigen p53 from Saos-2 cells that do not contain it. PMID:26932233

  17. p53 isoforms change p53 paradigm

    OpenAIRE

    Bourdon, JC

    2014-01-01

    Although p53 defines cellular responses to cancer treatment it is not clear how p53 can be used to control cell fate outcome. Data demonstrate that so-called p53 does not exist as a single protein, but is in fact a group of p53 protein isoforms whose expression can be manipulated to control the cellular response to treatment.

  18. Phosphorylation at tyrosine 114 of Proliferating Cell Nuclear Antigen (PCNA) is required for adipogenesis in response to high fat diet

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Yuan-Hung; Ho, Po-Chun; Chen, Min-Shan; Hugo, Eric; Ben-Jonathan, Nira [Department of Cancer Biology, University of Cincinnati College of Medicine, 3125 Eden Avenue, Cincinnati, OH 45267-0521 (United States); Department of Environmental Health, University of Cincinnati College of Medicine, 3223 Eden Avenue, Kettering Laboratory, Cincinnati, OH 45267-0056 (United States); Wang, Shao-Chun, E-mail: shao-chun.wang@uc.edu [Department of Cancer Biology, University of Cincinnati College of Medicine, 3125 Eden Avenue, Cincinnati, OH 45267-0521 (United States); Department of Environmental Health, University of Cincinnati College of Medicine, 3223 Eden Avenue, Kettering Laboratory, Cincinnati, OH 45267-0056 (United States)

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer Proliferating Cell Nuclear Antigen (PCNA) is phosphorylated at Y114. Black-Right-Pointing-Pointer Phospho-Y114 of PCNA is not required for cell proliferation for normal growth. Black-Right-Pointing-Pointer MCE during adipogenesis is abolished in the lack of the phosphorylation. Black-Right-Pointing-Pointer Homozygous Y114F mice are resistant to high fat diet induced obesity. Black-Right-Pointing-Pointer Our results shed light on the interface between proliferation and differentiation. -- Abstract: Clonal proliferation is an obligatory component of adipogenesis. Although several cell cycle regulators are known to participate in the transition between pre-adipocyte proliferation and terminal adipocyte differentiation, how the core DNA synthesis machinery is coordinately regulated in adipogenesis remains elusive. PCNA (Proliferating Cell Nuclear Antigen) is an indispensable component for DNA synthesis during proliferation. Here we show that PCNA is subject to phosphorylation at the highly conserved tyrosine residue 114 (Y114). Replacing the Y114 residue with phenylalanine (Y114F), which is structurally similar to tyrosine but cannot be phosphorylated, does not affect normal animal development. However, when challenged with high fat diet, mice carrying homozygous Y114F alleles (PCNA{sup F/F}) are resistant to adipose tissue enlargement in comparison to wild-type (WT) mice. Mouse embryonic fibroblasts (MEFs) harboring WT or Y114F mutant PCNA proliferate at similar rates. However, when subjected to adipogenesis induction in culture, PCNA{sup F/F} MEFs are not able to re-enter the cell cycle and fail to form mature adipocytes, while WT MEFs undergo mitotic clonal expansion in response to the adipogenic stimulation, accompanied by enhanced Y114 phosphorylation of PCNA, and differentiate to mature adipocytes. Consistent with the function of Y114 phosphorylation in clonal proliferation in adipogenesis, fat tissues isolated from WT

  19. EC5S ubiquitin complex is recruited by KSHV latent antigen LANA for degradation of the VHL and p53 tumor suppressors.

    Directory of Open Access Journals (Sweden)

    Qi-Liang Cai

    2006-10-01

    Full Text Available Cellular protein degradation pathways can be utilized by viruses to establish an environment that favors their propagation. Here we report that the Kaposi's sarcoma-associated herpesvirus (KSHV-encoded latency-associated nuclear antigen (LANA directly functions as a component of the EC5S ubiquitin complex targeting the tumor suppressors von Hippel-Lindau (VHL and p53 for degradation. We have characterized a suppressor of cytokine signaling box-like motif within LANA composed of an Elongin B and C box and a Cullin box, which is spatially located at its amino and carboxyl termini. This motif is necessary for LANA interaction with the Cul5-Elongin BC complex, to promote polyubiquitylation of cellular substrates VHL and p53 in vitro via its amino- and carboxyl-terminal binding domain, respectively. In transfected cells as well as KSHV-infected B lymphoma cells, LANA expression stimulates degradation of VHL and p53. Additionally, specific RNA interference-mediated LANA knockdown stabilized VHL and p53 in primary effusion lymphoma cells. Thus, manipulation of tumor suppressors by LANA potentially provides a favorable environment for progression of KSHV-infected tumor cells.

  20. Proliferating cell nuclear antigen (PCNA interactions in solution studied by NMR.

    Directory of Open Access Journals (Sweden)

    Alfredo De Biasio

    Full Text Available PCNA is an essential factor for DNA replication and repair. It forms a ring shaped structure of 86 kDa by the symmetric association of three identical protomers. The ring encircles the DNA and acts as a docking platform for other proteins, most of them containing the PCNA Interaction Protein sequence (PIP-box. We have used NMR to characterize the interactions of PCNA with several other proteins and fragments in solution. The binding of the PIP-box peptide of the cell cycle inhibitor p21 to PCNA is consistent with the crystal structure of the complex. A shorter p21 peptide binds with reduced affinity but retains most of the molecular recognition determinants. However the binding of the corresponding peptide of the tumor suppressor ING1 is extremely weak, indicating that slight deviations from the consensus PIP-box sequence dramatically reduce the affinity for PCNA, in contrast with a proposed less stringent PIP-box sequence requirement. We could not detect any binding between PCNA and the MCL-1 or the CDK2 protein, reported to interact with PCNA in biochemical assays. This suggests that they do not bind directly to PCNA, or they do but very weakly, with additional unidentified factors stabilizing the interactions in the cell. Backbone dynamics measurements show three PCNA regions with high relative flexibility, including the interdomain connector loop (IDCL and the C-terminus, both of them involved in the interaction with the PIP-box. Our work provides the basis for high resolution studies of direct ligand binding to PCNA in solution.

  1. Phosphorylation at tyrosine 114 of Proliferating Cell Nuclear Antigen (PCNA) is required for adipogenesis in response to high fat diet

    International Nuclear Information System (INIS)

    Highlights: ► Proliferating Cell Nuclear Antigen (PCNA) is phosphorylated at Y114. ► Phospho-Y114 of PCNA is not required for cell proliferation for normal growth. ► MCE during adipogenesis is abolished in the lack of the phosphorylation. ► Homozygous Y114F mice are resistant to high fat diet induced obesity. ► Our results shed light on the interface between proliferation and differentiation. -- Abstract: Clonal proliferation is an obligatory component of adipogenesis. Although several cell cycle regulators are known to participate in the transition between pre-adipocyte proliferation and terminal adipocyte differentiation, how the core DNA synthesis machinery is coordinately regulated in adipogenesis remains elusive. PCNA (Proliferating Cell Nuclear Antigen) is an indispensable component for DNA synthesis during proliferation. Here we show that PCNA is subject to phosphorylation at the highly conserved tyrosine residue 114 (Y114). Replacing the Y114 residue with phenylalanine (Y114F), which is structurally similar to tyrosine but cannot be phosphorylated, does not affect normal animal development. However, when challenged with high fat diet, mice carrying homozygous Y114F alleles (PCNAF/F) are resistant to adipose tissue enlargement in comparison to wild-type (WT) mice. Mouse embryonic fibroblasts (MEFs) harboring WT or Y114F mutant PCNA proliferate at similar rates. However, when subjected to adipogenesis induction in culture, PCNAF/F MEFs are not able to re-enter the cell cycle and fail to form mature adipocytes, while WT MEFs undergo mitotic clonal expansion in response to the adipogenic stimulation, accompanied by enhanced Y114 phosphorylation of PCNA, and differentiate to mature adipocytes. Consistent with the function of Y114 phosphorylation in clonal proliferation in adipogenesis, fat tissues isolated from WT mice contain significantly more adipocytes than those isolated from PCNAF/F mice. This study identifies a critical role for PCNA in adipose

  2. JC Virus T-Antigen in Colorectal Cancer Is Associated with p53 Expression and Chromosomal Instability, Independent of CpG Island Methylator Phenotype

    Directory of Open Access Journals (Sweden)

    Katsuhiko Nosho

    2009-01-01

    Full Text Available JC virus has a transforming gene encoding JC virus T-antigen (JCVT. JCVT may inactivate wild-type p53, cause chromosomal instability (CIN, and stabilize β-catenin. A link between JCVT and CpG island methylator phenotype (CIMP has been suggested. However, no large-scale study has examined the relations of JCVT with molecular alterations, clinical outcome, or prognosis in colon cancer. We detected JCVT expression (by immunohistochemistry in 271 (35% of 766 colorectal cancers. We quantified DNA methylation in eight CIMP-specific promoters (CACNA1G, CDKN2A, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1 and eight other loci (CHFR, HIC1, IGFBP3, MGMT, MINT1, MINT31, p14, WRN by MethyLight. We examined loss of heterozygosity in 2p, 5q, 17q, and 18q. JCVT was significantly associated with p53 expression (P < .0001, p21 loss (P < .0001, CIN (≥2 chromosomal segments with LOH; P < .0001, nuclear β-catenin (P = .006, LINE-1 hypomethylation (P = .002, and inversely with CIMP-high (P = .0005 and microsatellite instability (MSI (P < .0001, but not with PIK3CA mutation. In multivariate logistic regression analysis, the associations of JCVT with p53 [adjusted odds ratio (OR, 8.45; P < .0001], CIN (adjusted OR, 2.53; P = .003, cyclin D1 (adjusted OR, 1.57; P = .02, LINE-1 hypomethylation (adjusted OR, 1.97 for a 30% decline as a unit; P = .03, BRAF mutation (adjusted OR, 2.20; P = .04, and family history of colorectal cancer (adjusted OR, 0.64; P = .04 remained statistically significant. However, JCVT was no longer significantly associated with CIMP, MSI, β-catenin, or cyclooxygenase-2 expression in multivariate analysis. JCVT was unrelated with patient survival. In conclusion, JCVT expression in colorectal cancer is independently associated with p53 expression and CIN, which may lead to uncontrolled cell proliferation.

  3. Proliferating cell nuclear antigen (PCNA) activity in hepatocellular carcinoma, benign peri-neoplastic and normal liver.

    Science.gov (United States)

    Mun, Kein-Seong; Cheah, Phaik-Leng; Baharudin, Nurul Bahiyah; Looi, Lai-Meng

    2006-12-01

    Hepatocellular carcinoma (HCC) is among the ten most common cancers in Malaysian males. As cellular proliferation is an important feature of malignant transformation, we studied the proliferation pattern of normal and benign perineoplastic liver versus hepatocellular carcinoma in an attempt to further understand the tumour transformation process. 39 HCC (21 with accompanying and 18 without cirrhosis) histologically diagnosed at the Department of Pathology, University of Malaya Medical Centre between January 1992 and December 2003 were immunohistochemically studied using a monoclonal antibody to PCNA (Clone PC10: Dako). 20 livers from cases who had succumbed to traumatic injuries served as normal liver controls (NL). PCNA labeling index (PCNA-LI) was determined by counting the number of immunopositive cells in 1000 contiguous HCC, benign cirrhotic perineoplastic liver (BLC), benign perineoplastic non-cirrhotic (BLNC) and NL cells and conversion to a percentage. The PCNA-LI was also expressed as Ojanguren et al's grades. PCNA was expressed in 10% NL, 38.9% BLNC, 76.2% BLC and 71.8% HCC with BLNC, BLC and HCC showing significantly increased (p cells being immunopositive) immunoreactivity on Ojanguren et al's grading system and only HCC demonstrated immunoreactivity which ranged up to grade 3 (75% of cells). From this study, there appears to be a generally increasing trend of proliferative activity from NL to BLNC to BLC and HCC. Nonetheless, BLNC and BLC, like NL, retained low PCNA-LI and only HCC had a significantly increased PCNA-LI compared with the benign categories. This is probably related to the malignant nature of HCC and may reflect the uncontrolled proliferation of the neoplastic hepatocytes. PMID:18376794

  4. Readers of PCNA modifications.

    Science.gov (United States)

    Ulrich, Helle D; Takahashi, Tomio

    2013-08-01

    The eukaryotic sliding clamp, proliferating cell nuclear antigen (PCNA), acts as a central coordinator of DNA transactions by providing a multivalent interaction surface for factors involved in DNA replication, repair, chromatin dynamics and cell cycle regulation. Posttranslational modifications (PTMs), such as mono- and polyubiquitylation, sumoylation, phosphorylation and acetylation, further expand the repertoire of PCNA's binding partners. These modifications affect PCNA's activity in the bypass of lesions during DNA replication, the regulation of alternative damage processing pathways such as homologous recombination and DNA interstrand cross-link repair, or impact on the stability of PCNA itself. In this review, we summarise our current knowledge about how the PTMs are "read" by downstream effector proteins that mediate the appropriate action. Given the variety of interaction partners responding to PCNA's modified forms, the ensemble of PCNA modifications serves as an instructive model for the study of biological signalling through PTMs in general. PMID:23580141

  5. Study on expression of p53、 bcl-2、 bax and PCNA in retinoblastoma%视网膜母细胞瘤p53、bcl-2、bax及增殖细胞核抗原的表达意义

    Institute of Scientific and Technical Information of China (English)

    李琳; 雷霍; 杨慧

    2002-01-01

    目的了解视网膜母细胞瘤(retinoblastoma,Rb)p53、bcl-2、bax和增殖细胞核抗原表达与Rb及其分化程度的关系.方法用免疫组化检测21例Rb和6例正常视网膜常规石蜡标本进行p53、bcl-2、bax和PCNA表达.结果bc1-2、bax和PCNA在Rb中的表达较高,与正常视网膜相比有显著性差异,分化性Rb组织bcl-2阳性表达率较高,与未分化型Rb组织相比有显著性差异.p53、bcl-2、bax在Rb中的表达与PCNA的表达有显著相关性.结论 Rb的发生与多个细胞凋亡调控基因异常有关,测定和分析Rb的bcl-2、PCNA、bax和表达,对于Rb的诊断和分化程度有重要意义.

  6. Sequence analysis of secretory antigen P53 and immunological identification of the recombinant product of Trichinella spiralis%旋毛形线虫分泌抗原P53的序列分析及重组表达产物的免疫学鉴定

    Institute of Scientific and Technical Information of China (English)

    徐鸿绪; 武伟华; 毛玉玲; 梁健; 谌嘉嘉; 胡旭初

    2010-01-01

    Objective To analyze the immunological characteristics of Trichinella spiralis secretory antigen P53 and to evaluate its value in diagnosis of trichinellosis. Methods An open read frame of secretory antigen P53 was cloned from Trichinella spiralis by reverse transcriptasepolymerase chain reaction (RT-PCR) and then sequenced. Bioinformatics analysis was performed to search for its homologues in other helminths and predict its potential linear B cell epitopes and T cell epitopes. The sequence coding mature peptide was inserted into prokaryotic expression vector pET28a(+) and the purified recombinant product was identified by Western blot using serum samples of patients infected with Trichinella spiralis or other helminth. Results Bioinformaties analysis results showed that there was no P53 homologue in other helminths, which indicated that there were many linear B cell epitopes and T cell epitopes in TsP53. The recombinant P53 antigen only reacted with the serum samples of patients infected with Trichinella spiralis without any cross-reaction with the serum of patients infected with other helminths. Conclusion P53 has strong immunogenicity and immunoreactivity, which may be a promising candidate for developing Trichinella spiralis specific diagnostic method.%目的 分析旋毛形线虫分泌抗原P53的免疫学特性,评价其免疫诊断价值.方法 克隆并测序分析旋毛形线虫P53的编码区序列,应用生物信息学分析其与其他蠕虫同源蛋白的相似性以及潜在的线性B细胞和T细胞表位;并将成熟肽编码区克隆至pET28a(+)原核表达质粒中,纯化的重组蛋白用旋毛形线虫感染血清和其他寄生蠕虫感染血清经Western印迹法鉴定其免疫反应性.结果 生物信息学分析未发现其他寄生蠕虫的P53同源基因,表明TsP53具有多个T细胞和B细胞识别表位,Western印迹法显示TsP53抗原只与旋毛形线虫感染血清反应,与其他几种蠕虫感染血清无反应.结论 P53具有

  7. Effect of interventional treatment with p53 on the invasion and metastasis of VX2 liver tumor in experimental rabbits

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of interventional treatment with p53 on the invasion and metastasis of VX2 liver tumor in experimental rabbits. Methods: VX2 carcinoma cells were surgically implanted into the left hepatic lobe in 48 New Zealand white rabbits, and the rabbit hepatic carcinoma models were thus established. The rabbits were randomly divided into 4 groups with 12 rabbits in each group. After hepatic arterial catheterization was completed physiological saline (control group), Lipiodol (Group A), Ad-p53 (Group B) and Lipiodol+Ad-p53 (Group C) were respectively infused into the rabbits of four groups via common hepatic artery. One week after the procedure the rabbits were sacrificed and the livers were removed for the determination of matrix metalloprotein-2 (MMP-2), proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) of the tumor with immunohistochemistry technique. Results: The tumor growth in study groups (group A, B and C) was markedly suppressed, which was significantly different in comparison with that in control group (P 0.05). The positive rates of MMP-2, PCNA and VEGF in group B and C were significantly lower than those in control group (P < 0.05). The positive rates of MMP-2, PCNA and VEGF of the rabbits with metastasis were markedly higher than those without metastasis(P < 0.05). MMP-2 bore a certain relationship with VEGF and PCNA (P < 0.05). Conclusion: The increase of the positive rates of MMP-2, PCNA and VEGF indicates that the tumor possesses higher possibility for developing metastasis, proliferation and vascular formation. The interventional treatment with Adp53 or Lipiodol+Ad-p53 can inhibit the growth, metastasis and vascular formation of VX2 liver tumor in experimental rabbits. (J Intervent Radiol, 2010, 19 : 800-804) (authors)

  8. Proliferating cell nuclear antigen (PCNA) allows the automatic identification of follicles in microscopic images of human ovarian tissue

    CERN Document Server

    Kelsey, Thomas W; Castillo, Luis; Wallace, W Hamish B; Gonzálvez, Francisco Cóppola; 10.2147/PLMI.S11116

    2010-01-01

    Human ovarian reserve is defined by the population of nongrowing follicles (NGFs) in the ovary. Direct estimation of ovarian reserve involves the identification of NGFs in prepared ovarian tissue. Previous studies involving human tissue have used hematoxylin and eosin (HE) stain, with NGF populations estimated by human examination either of tissue under a microscope, or of images taken of this tissue. In this study we replaced HE with proliferating cell nuclear antigen (PCNA), and automated the identification and enumeration of NGFs that appear in the resulting microscopic images. We compared the automated estimates to those obtained by human experts, with the "gold standard" taken to be the average of the conservative and liberal estimates by three human experts. The automated estimates were within 10% of the "gold standard", for images at both 100x and 200x magnifications. Automated analysis took longer than human analysis for several hundred images, not allowing for breaks from analysis needed by humans. O...

  9. Pro-recombination Role of Srs2 Protein Requires SUMO (Small Ubiquitin-like Modifier) but Is Independent of PCNA (Proliferating Cell Nuclear Antigen) Interaction

    DEFF Research Database (Denmark)

    Kolesar, Peter; Altmannova, Veronika; Silva, Sonia;

    2016-01-01

    -interacting motif (SIM) of Srs2 is important for the interaction with several recombination factors. Lack of SIM, but not proliferating cell nuclear antigen (PCNA)-interacting motif (PIM), leads to increased cell death under circumstances requiring homologous recombination for DNA repair. Simultaneous mutation of...

  10. Characterization of highly frequent epitope-specific CD45RA+/CCR7+/- T lymphocyte responses against p53-binding domains of the human polyomavirus BK large tumor antigen in HLA-A*0201+ BKV-seropositive donors

    Directory of Open Access Journals (Sweden)

    Zajac Paul

    2006-11-01

    Full Text Available Abstract Human polyomavirus BK (BKV has been implicated in oncogenic transformation. Its ability to replicate is determined by the binding of its large tumor antigen (LTag to products of tumor-suppressor genes regulating cell cycle, as specifically p53. We investigated CD8+ T immune responses to BKV LTag portions involved in p53 binding in HLA-A*0201+ BKV LTag experienced individuals. Peptides selected from either p53-binding region (LTag351–450 and LTag533–626 by current algorithms and capacity to bind HLA-A*0201 molecule were used to stimulate CD8+ T responses, as assessed by IFN-γ gene expression ex vivo and detected by cytotoxicity assays following in vitro culture. We observed epitope-specific immune responses in all HLA-A*0201+ BKV LTag experienced individuals tested. At least one epitope, LTag579–587; LLLIWFRPV, was naturally processed in non professional antigen presenting cells and induced cytotoxic responses with CTL precursor frequencies in the order of 1/20'000. Antigen specific CD8+ T cells were only detectable in the CD45RA+ subset, in both CCR7+ and CCR7- subpopulations. These data indicate that widespread cellular immune responses against epitopes within BKV LTag-p53 binding regions exist and question their roles in immunosurveillance against tumors possibly associated with BKV infection.

  11. Transcriptional upregulation of restin by p53

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Restin, belonging to the melanoma-associated antigen superfamily, was firstly cloned from the differentiated HL-60 cells when induced by all-trans retinoic acid ( ATRA ) in our lab. Our previous results showed that restin might be correlated to cell cycle arrest. Due to the importance of p53 in the regulation of cell growth and the relationship between p53 and ATRA, we tried to test the relationship between p53 and restin. Firstly, transfection results showed that p53 was able to upregulate the expression of restin at the transcriptional level when p53 was transfected into eukaryotic cells. Secondly, the bioinformatics analysis revealed that the upstream sequence (about 2 kb) from the first ATG of the ORF of restin gene contained a p53 binding site. In order to confirm that p53 was involved in the transcriptional regulation of restin, we cloned the upstream sequence of restin and constructed the promoter luciferase reporter system. From the luciferase activity, we demonstrated that the promoter of restin gene could be induced by ATRA. Then, another two luciferase reporter plasmids driven by the reporter of restin with no (RP?p53-luc) or mutant (mRP-luc) p53 binding site were constructed to see the regulation of restin by p53. Results showed that the transcriptional upregulation of restin gene was not due to the putative p53 binding site on the upstream of restin gene. We proposed that p53 upregulated restin transcription through an indirect way rather than direct interaction with the cis-activating element of the restin promoter.

  12. Transcriptional upregulation of restin by p53

    Institute of Scientific and Technical Information of China (English)

    WANG RuiHua; LU Fan; FU HaiYan; WU YouSheng; YANG GuoDong; ZHAO WenMing; Zhao ZhongLiang

    2007-01-01

    Restin, belonging to the melanoma-associated antigen superfamily, was firstly cloned from the differentiated HL-60 cells when induced by all-trans retinoic acid ( ATRA ) in our lab. Our previous results showed that restin might be correlated to cell cycle arrest. Due to the importance of p53 in the regulation of cell growth and the relationship between p53 and ATRA, we tried to test the relationship between p53 and restin. Firstly, transfection results showed that p53 was able to upregulate the expression of restin at the transcriptional level when p53 was transfected into eukaryotic cells. Secondly, the bioinformatics analysis revealed that the upstream sequence (about 2 kb) from the first ATG of the ORF of restin gene contained a p53 binding site. In order to confirm that p53 was involved in the transcriptional regulation of restin, we cloned the upstream sequence of restin and constructed the promoter luciferase reporter system. From the luciferase activity, we demonstrated that the promoter of restin gene could be induced by ATRA. Then, another two luciferase reporter plasmids driven by the reporter of restin with no (RP△p53-luc) or mutant (mRP-luc) p53 binding site were constructed to see the regulation of restin by p53. Results showed that the transcriptional upregulation of restin gene was not due to the putative p53 binding site on the upstream of restin gene. We proposed that p53 upregulated restin transcription through an indirect way rather than direct interaction with the cis-activating element of the restin promoter.

  13. Wild-type alternatively spliced p53: binding to DNA and interaction with the major p53 protein in vitro and in cells.

    OpenAIRE

    Wu, Y.; Liu, Y; Lee, L.(Department of Physics, Yale University, New Haven, CT, USA); Miner, Z; Kulesz-Martin, M

    1994-01-01

    A p53 variant protein (p53as) generated from alternatively spliced p53 RNA is expressed in normal and malignant mouse cells and tissues, and p53as antigen activity is preferentially associated with the G2 phase of the cell cycle, suggesting that p53as and p53 protein may have distinct properties. Using p53as and p53 proteins translated in vitro, we now provide evidence that p53as protein has efficient sequence-specific DNA-binding ability. DNA binding by p53 protein is inefficient in comparis...

  14. Microbial Regulation of p53 Tumor Suppressor.

    Science.gov (United States)

    Zaika, Alexander I; Wei, Jinxiong; Noto, Jennifer M; Peek, Richard M

    2015-09-01

    p53 tumor suppressor has been identified as a protein interacting with the large T antigen produced by simian vacuolating virus 40 (SV40). Subsequent research on p53 inhibition by SV40 and other tumor viruses has not only helped to gain a better understanding of viral biology, but also shaped our knowledge of human tumorigenesis. Recent studies have found, however, that inhibition of p53 is not strictly in the realm of viruses. Some bacterial pathogens also actively inhibit p53 protein and induce its degradation, resulting in alteration of cellular stress responses. This phenomenon was initially characterized in gastric epithelial cells infected with Helicobacter pylori, a bacterial pathogen that commonly infects the human stomach and is strongly linked to gastric cancer. Besides H. pylori, a number of other bacterial species were recently discovered to inhibit p53. These findings provide novel insights into host-bacteria interactions and tumorigenesis associated with bacterial infections. PMID:26379246

  15. Microbial Regulation of p53 Tumor Suppressor.

    Directory of Open Access Journals (Sweden)

    Alexander I Zaika

    2015-09-01

    Full Text Available p53 tumor suppressor has been identified as a protein interacting with the large T antigen produced by simian vacuolating virus 40 (SV40. Subsequent research on p53 inhibition by SV40 and other tumor viruses has not only helped to gain a better understanding of viral biology, but also shaped our knowledge of human tumorigenesis. Recent studies have found, however, that inhibition of p53 is not strictly in the realm of viruses. Some bacterial pathogens also actively inhibit p53 protein and induce its degradation, resulting in alteration of cellular stress responses. This phenomenon was initially characterized in gastric epithelial cells infected with Helicobacter pylori, a bacterial pathogen that commonly infects the human stomach and is strongly linked to gastric cancer. Besides H. pylori, a number of other bacterial species were recently discovered to inhibit p53. These findings provide novel insights into host-bacteria interactions and tumorigenesis associated with bacterial infections.

  16. Quiescence does not affect p53 and stress response by irradiation in human lung fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jiawen [Molecular Radiobiology Laboratory, Division of Cellular and Molecular Research (Singapore); Itahana, Koji, E-mail: koji.itahana@duke-nus.edu.sg [Cancer and Stem Cell Biology Program, Duke-NUS Graduate Medical School (Singapore); Baskar, Rajamanickam, E-mail: r.baskar@nccs.com.sg [Molecular Radiobiology Laboratory, Division of Cellular and Molecular Research (Singapore); Department of Radiation Oncology, National Cancer Centre (Singapore)

    2015-02-27

    Cells in many organs exist in both proliferating and quiescent states. Proliferating cells are more radio-sensitive, DNA damage pathways including p53 pathway are activated to undergo either G{sub 1}/S or G{sub 2}/M arrest to avoid entering S and M phase with DNA damage. On the other hand, quiescent cells are already arrested in G{sub 0}, therefore there may be fundamental difference of irradiation response between proliferating and quiescent cells, and this difference may affect their radiosensitivity. To understand these differences, proliferating and quiescent human normal lung fibroblasts were exposed to 0.10–1 Gy of γ-radiation. The response of key proteins involved in the cell cycle, cell death, and metabolism as well as histone H2AX phosphorylation were examined. Interestingly, p53 and p53 phosphorylation (Ser-15), as well as the cyclin-dependent kinase inhibitors p21 and p27, were induced similarly in both proliferating and quiescent cells after irradiation. Furthermore, the p53 protein half-life, and expression of cyclin A, cyclin E, proliferating cell nuclear antigen (PCNA), Bax, or cytochrome c expression as well as histone H2AX phosphorylation were comparable after irradiation in both phases of cells. The effect of radioprotection by a glycogen synthase kinase 3β inhibitor on p53 pathway was also similar between proliferating and quiescent cells. Our results showed that quiescence does not affect irradiation response of key proteins involved in stress and DNA damage at least in normal fibroblasts, providing a better understanding of the radiation response in quiescent cells, which is crucial for tissue repair and regeneration. - Highlights: • p53 response by irradiation was similar between proliferating and quiescent cells. • Quiescent cells showed similar profiles of cell cycle proteins after irradiation. • Radioprotection of GSK-3β inhibitor caused similar effects between these cells. • Quiescence did not affect p53 response despite its

  17. Quiescence does not affect p53 and stress response by irradiation in human lung fibroblasts

    International Nuclear Information System (INIS)

    Cells in many organs exist in both proliferating and quiescent states. Proliferating cells are more radio-sensitive, DNA damage pathways including p53 pathway are activated to undergo either G1/S or G2/M arrest to avoid entering S and M phase with DNA damage. On the other hand, quiescent cells are already arrested in G0, therefore there may be fundamental difference of irradiation response between proliferating and quiescent cells, and this difference may affect their radiosensitivity. To understand these differences, proliferating and quiescent human normal lung fibroblasts were exposed to 0.10–1 Gy of γ-radiation. The response of key proteins involved in the cell cycle, cell death, and metabolism as well as histone H2AX phosphorylation were examined. Interestingly, p53 and p53 phosphorylation (Ser-15), as well as the cyclin-dependent kinase inhibitors p21 and p27, were induced similarly in both proliferating and quiescent cells after irradiation. Furthermore, the p53 protein half-life, and expression of cyclin A, cyclin E, proliferating cell nuclear antigen (PCNA), Bax, or cytochrome c expression as well as histone H2AX phosphorylation were comparable after irradiation in both phases of cells. The effect of radioprotection by a glycogen synthase kinase 3β inhibitor on p53 pathway was also similar between proliferating and quiescent cells. Our results showed that quiescence does not affect irradiation response of key proteins involved in stress and DNA damage at least in normal fibroblasts, providing a better understanding of the radiation response in quiescent cells, which is crucial for tissue repair and regeneration. - Highlights: • p53 response by irradiation was similar between proliferating and quiescent cells. • Quiescent cells showed similar profiles of cell cycle proteins after irradiation. • Radioprotection of GSK-3β inhibitor caused similar effects between these cells. • Quiescence did not affect p53 response despite its known role in radio-resistance

  18. Expression of p53 protein, Jaagsiekte sheep retrovirus matrix protein, and surfactant protein in the lungs of sheep with pulmonary adenomatosis.

    Science.gov (United States)

    İlhan, Fatma; Vural, Sevil A; Yıldırım, Serkan; Sözdutmaz, İbrahim; Alcigir, Mehmet E

    2016-05-01

    Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring cancer in sheep that is caused by the Jaagsiekte sheep retrovirus (JSRV). Because the pathologic and epidemiologic features of OPA are similar to those of bronchoalveolar carcinoma in humans, OPA is considered a useful animal model for pulmonary carcinogenesis. In this study, 3,512 lungs from various breeds of sheep were collected and macroscopically examined. OPA was identified in 30 sheep, and samples of these animals were further examined by histologic, immunohistochemical (p53 protein, surfactant protein A [SP-A], proliferating cell nuclear antigen [PCNA], JSRV matrix protein [MA]), and PCR methods. Papillary or acinar adenocarcinomas were detected microscopically in the affected areas. Immunoreactivity for p53 PAb240 was detected in 13 sheep, whereas p53 DO-1 was not detected in any of the OPA animals. PCNA immunoreactivity was recorded in 27 animals. SP-A and JSRV MA protein was immunopositive in all 30. JSRV proviral DNA was detected by PCR analysis in all of the lung samples collected from OPA animals. In addition, the pulmonary SP-A levels were increased in tumor cells. The results of this study suggest that PCNA and p53 protein expression may be useful indicators in monitoring malignancy of pulmonary tumors. PMID:27016721

  19. EXPRESSIONS OF P53, PROLIFERATING CELL NUCLEAR ANITIGEN, BCL-2 PROTEIN AND THEIR SIGNIFICANCE IN SALIVARY ADENOID CYSTIC CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To study the effects of P53, PCNA, Bcl-2 protein and their relationship in salivary adenoid cystic carcinoma(SACC). Methods These proteins were examined by immunohistochemistry. Results Overexpressions of P53 and PCNA were revealed in ACC samples, they were higher than those in (polymorphous adenomas) PA, but expression of Bcl-2 protein was not different between ACC and PA. In 3 subtypes of ACC, expressions of 3 proteins were different. Conclusion Mutations of P53, Bcl-2 may be involed in the occurrence of SACC, expression of PCNA and mutation of P53 may coexist in the development of the SACC.

  20. OTUD5 regulates p53 stability by deubiquitinating p53.

    Directory of Open Access Journals (Sweden)

    Judong Luo

    Full Text Available BACKGROUND: 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. PRINCIPAL FINDINGS: 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. CONCLUSIONS: As a novel deubiquitinating enzyme for p53, OTUD5 is required for the stabilization and the activation of a p53 response.

  1. PCNA immunostaining in breast cancer.

    Science.gov (United States)

    Cummings, M C; Furnival, C M; Parsons, P G; Townsend, E

    1993-08-01

    Expression of proliferating cell nuclear antigen (PCNA) has been shown to be of prognostic value in patients with certain types of cancer. The aim of this study was to determine if the abundance of PCNA is inversely correlated with survival of patients with breast cancer. Paraffin blocks were available from 68 patients, all of whom had been followed clinically for at least 5 years. Sections from 20 patients showed no reactivity to PCNA and were excluded from the study because it was not possible to distinguish between true negatives and false negatives (those due to poor fixation of the original specimens). The PCNA index (the number of stained cancer cells as a percentage of the total number of cancer cells present) was calculated for the remaining 48 patients. Results were analysed by Wilcoxon's rank sum test (two tailed) and Pearson's correlation coefficient. There was no statistical difference between the PCNA indices of those patients dead from their disease within 5 years of diagnosis compared with those alive and without signs of breast cancer at 5 years. There was also no correlation between PCNA index and size of the cancer, involvement of axillary lymph nodes, time to recurrence or time to death. There was, however, a significant correlation between PCNA index and histological grade (P = 0.029). It appears that PCNA staining of stored paraffin sections is of little prognostic value in patients with breast cancer. PMID:8101708

  2. Physical and functional association of the cbl protooncogen product with an src-family protein tyrosine kinase, p53/56lyn, in the B cell antigen receptor-mediated signaling.

    Science.gov (United States)

    Tezuka, T; Umemori, H; Fusaki, N; Yagi, T; Takata, M; Kurosaki, T; Yamamoto, T

    1996-02-01

    To identify novel signal transducers involved in signaling mediated by the Src-family protein tyrosine kinases (PTKs), we used a yeast two-hybrid system with a probe corresponding to the regulatory region of p56lyn, a member of Src-family PTKs. One of the isolated clones contained the COOH-terminal 470 amino acid residues of p120c-cbl, the product of the cellular homologue of the v-cbl retroviral oncogene. p120c-cbl is a cytoplasmic protein with nuclear protein-like motifs. Here we show in vivo association of p120c-cbl with p53/56lyn. After stimulation of the B cell antigen receptor (BCR), p120c-cbl was rapidly tyrosine phosphorylated. Studies with lyn- or syk-negative chicken B cells demonstrated that p53/56lyn, but not p72syk, was crucial for tyrosine phosphorylation of p120c-cbl upon stimulation of the BCR. We also show the importance of p59fyn in tyrosine phosphorylation of p120c-cbl in the T-cell receptor-mediated signaling using fyn-overexpressing T cell hybridomas and splenic T cells from fyn-deficient mice. These results suggest that p120c-cbl is an important substrate of Src-family PTKs in the intracellular signaling mediated by the antigen receptors PMID:8627181

  3. THE SIGNIFICANCE OF P53 FUNCTION AND EXPRESSION TOGETHER WITH PCAN EXPRESSION IN ENDOMETRIAL CARCINOMA%抑癌基因P53联合增殖细胞核抗原在子宫内膜癌表达的意义

    Institute of Scientific and Technical Information of China (English)

    尧良清; 梁立治; 黄欣

    2003-01-01

    目的探讨抑癌基因P53联合增殖细胞核抗原(PCNA)表达在子宫内膜癌的发生发展机制及生物行为的分子学意义.方法应用Western Blot法和LSAB法联合测定32例子宫内膜癌不同分期、分级和病理类型间P53的功能、表达及PCNA表达.结果子宫内膜癌组P53功能异常和过度表达分别为28.1%、15.6%,显著高于对照组8.8%、0%(P<0.05);在腺癌组中,100%低分化、13.3%中分化和0%高分化者P53功能异常,三者间有极显著性差异(二者P<0.01);在早期组中,100%浆液性癌的P53过度表达显著高于腺癌4.3%(P<0.01);3例正常子宫内膜P53功能异常;31.3%子宫内膜癌高表达PCNA显著高于对照组2.9%(P<0.01).结论子宫内膜癌的发生发展是一个多因素、多步骤过程,抑癌基因P53异常在乳头状浆液性癌恶变过程中发生早且起着中心作用,在腺癌中可增加肿瘤的恶性程度;量化PCNA可反映子宫内膜癌细胞增殖活性.%Objective:To probe the molecular significance of tumor suppressor gene p53 expression together with proliferating cell nuclear antigen (PCNA) expression in the genesis and development of endometrial carcinoma (EC).Methods:There were 32 patients with EC in study group,Western blot method and LSAB was designed to detect function and expression of p53 together with PCNA expression in different pathological types, stages and grades in EC.Results:28.1% and 15.6% of EC have p53 abnormal function and overexpression which were significantly higher than those in the normal endometrium that were 8.8% and 0%(P<0.05); 85.7% of low differentiated EC had p53 abnormal function, and was significantly higher than the 13.3% of moderate differential EC (P<0.01) and the 10% of high differential EC (P<0.01); 100% of papillary serous carcinoma (UPSC) and 4.3% of endometrioid carcinoma (UEC) had the overexpression of p53 at the early stage(P<0.01),there were significant difference between them. 3 cases with normal

  4. Epstein-Barr Virus Nuclear Antigen 3C Augments Mdm2-Mediated p53 Ubiquitination and Degradation by Deubiquitinating Mdm2▿

    OpenAIRE

    Saha, Abhik; Murakami, Masanao; Kumar, Pankaj; Bajaj, Bharat; Sims, Karen; Erle S Robertson

    2009-01-01

    Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) is one of the essential latent antigens for primary B-cell transformation. Previous studies established that EBNA3C facilitates degradation of several vital cell cycle regulators, including the retinoblastoma (pRb) and p27KIP proteins, by recruitment of the SCFSkp2 E3 ubiquitin ligase complex. EBNA3C was also shown to be ubiquitinated at its N-terminal residues. Furthermore, EBNA3C can bind to and be degraded in vitro by purified 20S protea...

  5. P53 Mdm2 Inhibitors

    NARCIS (Netherlands)

    Khoury, Kareem; Doemling, Alex

    2012-01-01

    The protein-protein interaction (PPI) between p53 and its negative regulator MDM2 comprises one of the most important and intensely studied PPI's involved in preventing the initiation of cancer. The interaction between p53 and MDM2 is conformation-based and is tightly regulated on multiple levels. D

  6. p53 in stem cells

    Institute of Scientific and Technical Information of China (English)

    Valeriya; Solozobova; Christine; Blattner

    2011-01-01

    p53 is well known as a "guardian of the genome" for differentiated cells,in which it induces cell cycle arrest and cell death after DNA damage and thus contributes to the maintenance of genomic stability.In addition to this tumor suppressor function for differentiated cells,p53 also plays an important role in stem cells.In this cell type,p53 not only ensures genomic integrity after genotoxic insults but also controls their proliferation and differentiation.Additionally,p53 provides an effective barrier for the generation of pluripotent stem celllike cells from terminally differentiated cells.In this review,we summarize our current knowledge about p53 activities in embryonic,adult and induced pluripotent stem cells.

  7. Necdin, a p53-target gene, is an inhibitor of p53-mediated growth arrest.

    Directory of Open Access Journals (Sweden)

    Julie Lafontaine

    Full Text Available In vitro, cellular immortalization and transformation define a model for multistep carcinogenesis and current ongoing challenges include the identification of specific molecular events associated with steps along this oncogenic pathway. Here, using NIH3T3 cells, we identified transcriptionally related events associated with the expression of Polyomavirus Large-T antigen (PyLT, a potent viral oncogene. We propose that a subset of these alterations in gene expression may be related to the early events that contribute to carcinogenesis. The proposed tumor suppressor Necdin, known to be regulated by p53, was within a group of genes that was consistently upregulated in the presence of PyLT. While Necdin is induced following p53 activation with different genotoxic stresses, Necdin induction by PyLT did not involve p53 activation or the Rb-binding site of PyLT. Necdin depletion by shRNA conferred a proliferative advantage to NIH3T3 and PyLT-expressing NIH3T3 (NIHLT cells. In contrast, our results demonstrate that although overexpression of Necdin induced a growth arrest in NIH3T3 and NIHLT cells, a growing population rapidly emerged from these arrested cells. This population no longer showed significant proliferation defects despite high Necdin expression. Moreover, we established that Necdin is a negative regulator of p53-mediated growth arrest induced by nutlin-3, suggesting that Necdin upregulation could contribute to the bypass of a p53-response in p53 wild type tumors. To support this, we characterized Necdin expression in low malignant potential ovarian cancer (LMP where p53 mutations rarely occur. Elevated levels of Necdin expression were observed in LMP when compared to aggressive serous ovarian cancers. We propose that in some contexts, the constitutive expression of Necdin could contribute to cancer promotion by delaying appropriate p53 responses and potentially promote genomic instability.

  8. p53 protein alterations in adult astrocytic tumors and oligodendrogliomas

    Directory of Open Access Journals (Sweden)

    Nayak Anupma

    2004-04-01

    Full Text Available BACKGROUND: p53 is a tumor suppressor gene implicated in the genesis of a variety of malignancies including brain tumors. Overexpression of the p53 protein is often used as a surrogate indicator of alterations in the p53 gene. AIMS: In this study, data is presented on p53 protein expression in adult cases (>15 years of age of astrocytic (n=152 and oligodendroglial (n=28 tumors of all grades. Of the astrocytic tumors, 86% were supratentorial in location while remaining 14% were located infratentorially - 8 in the the cerebellum and 13 in the brainstem. All the oligodendrogliomas were supratentorial. MATERIALS AND METHODS: p53 protein expression was evaluated on formalin-fixed paraffin-embedded sections using streptavidin biotin immunoperoxidase technique after high temperature antigen retrieval. RESULTS: Overall 52% of supratentorial astrocytic tumors showed p53 immunopositivity with no correlation to the histological grade. Thus, 58.8% of diffuse astrocytomas (WHO Grade II, 53.8% of anaplastic astrocytomas (WHO Grade III and 50% of glioblastomas (WHO Grade IV were p53 protein positive. In contrast, all the infratentorial tumors were p53 negative except for one brainstem glioblastoma. Similarly, pilocytic astrocytomas were uniformly p53 negative irrespective of the location. Among oligodendroglial tumors, the overall frequency of p53 immunopositivity was lower (only 28%, though a trend of positive correlation with the tumor grade was noted - 25% in Grade II and 31.5% in grade III (anaplastic oligodendroglioma. Interestingly, p53 labeling index (p53 LI did not correlate with the histopathological grade in both astrocytic and oligodendroglial tumors. CONCLUSIONS: Thus, this study gives an insight into the genetic and hence biological heterogeneity of gliomas, not only between astrocytic tumors vs. oligodendrogliomas but also within astrocytic tumors with regard to their grade and location. With p53 gene therapy trials in progress, this will

  9. Proliferating cell nuclear antigen (PCNA) interacts with a meiosis-specific RecA homologues, Lim15/Dmc1, but does not stimulate its strand transfer activity

    International Nuclear Information System (INIS)

    PCNA is a multi-functional protein that is involved in various nuclear events. Here we show that PCNA participates in events occurring during early meiotic prophase. Analysis of protein-protein interactions using surface plasmon resonance indicates that Coprinus cinereus PCNA (CoPCNA) specifically interacts with a meiotic specific RecA-like factor, C. cinereus Lim15/Dmc1 (CoLim15) in vitro. The binding efficiency increases with addition of Mg2+ ions, while ATP inhibits the interaction. Co-immunoprecipitation experiments indicate that the CoLim15 protein interacts with the CoPCNA protein in vitro and in the cell extracts. Despite the interaction between these two factors, no enhancement of CoLim15-dependent strand transfer activity by CoPCNA was found in vitro. We propose that the interaction between Lim15/Dmc1 and PCNA mediates the recombination-associated DNA synthesis during meiosis

  10. Stability of p53 homologs.

    Directory of Open Access Journals (Sweden)

    Tobias Brandt

    Full Text Available Most proteins have not evolved for maximal thermal stability. Some are only marginally stable, as for example, the DNA-binding domains of p53 and its homologs, whose kinetic and thermodynamic stabilities are strongly correlated. Here, we applied high-throughput methods using a real-time PCR thermocycler to study the stability of several full-length orthologs and paralogs of the p53 family of transcription factors, which have diverse functions, ranging from tumour suppression to control of developmental processes. From isothermal denaturation fluorimetry and differential scanning fluorimetry, we found that full-length proteins showed the same correlation between kinetic and thermodynamic stability as their isolated DNA-binding domains. The stabilities of the full-length p53 orthologs were marginal and correlated with the temperature of their organism, paralleling the stability of the isolated DNA-binding domains. Additionally, the paralogs p63 and p73 were significantly more stable and long-lived than p53. The short half-life of p53 orthologs and the greater persistence of the paralogs may be biologically relevant.

  11. Influenza A Viruses Control Expression of Proviral Human p53 Isoforms p53β and Δ133p53α

    OpenAIRE

    Terrier, Olivier; Marcel, Virginie; Cartet, Gaëlle; Lane, David P; Lina, Bruno; Rosa-Calatrava, Manuel; Bourdon, Jean-Christophe

    2012-01-01

    Previous studies have described the role of p53 isoforms, including p53β and Δ133p53α, in the modulation of the activity of full-length p53, which regulates cell fate. In the context of influenza virus infection, an interplay between influenza viruses and p53 has been described, with p53 being involved in the antiviral response. However, the role of physiological p53 isoforms has never been explored in this context. Here, we demonstrate that p53 isoforms play a role in influenza A virus infec...

  12. The p53 pathway in breast cancer

    OpenAIRE

    Gasco, Milena; Shami, Shukri; Crook, Tim

    2002-01-01

    p53 mutation remains the most common genetic change identified in human neoplasia. In breast cancer, p53 mutation is associated with more aggressive disease and worse overall survival. The frequency of mutation in p53 is, however, lower in breast cancer than in other solid tumours. Changes, both genetic and epigenetic, have been identified in regulators of p53 activity and in some downstream transcriptional targets of p53 in breast cancers that express wild-type p53. Molecular pathological an...

  13. p53 isoform Δ113p53 is a p53 target gene that antagonizes p53 apoptotic activity via BclxL activation in zebrafish

    OpenAIRE

    Chen, Jun; Ng, Sok Meng; Chang, Changqing; Zhang, Zhenhai; Bourdon, Jean-Christophe; Lane, David P; Peng, Jinrong

    2009-01-01

    p53 is a well-known tumor suppressor and is also involved in processes of organismal aging and developmental control. A recent exciting development in the p53 field is the discovery of various p53 isoforms. One p53 isoform is human Δ133p53 and its zebrafish counterpart Δ113p53. These N-terminal-truncated p53 isoforms are initiated from an alternative p53 promoter, but their expression regulation and physiological significance at the organismal level are not well understood. We show here that ...

  14. Tight coevolution of proliferating cell nuclear antigen (PCNA)-partner interaction networks in fungi leads to interspecies network incompatibility.

    OpenAIRE

    Zamir, L.; Zaretsky, M.; Fridman, Y; Ner-Gaon, H.; Rubin, E; Aharoni, A.

    2012-01-01

    The structure and connectivity of protein-protein interaction (PPI) networks are maintained throughout evolution by coordinated changes (coevolution) of network proteins. Despite extensive research, relatively little is known regarding the molecular basis and functional implications of the coevolution of PPI networks. Here, we used proliferating cell nuclear antigen, a hub protein that mediates DNA replication and repair in eukaryotes, as a model system to study the coevolution of PPI network...

  15. p53 and its isoforms in cancer

    OpenAIRE

    Bourdon, J-C

    2007-01-01

    p53, p63 and p73 are members of the p53 gene family involved in development, differentiation and response to cellular stress. p53 gene is a transcription factor essential for the prevention of cancer formation. The p53 pathway is ubiquitously lost in human cancer either by p53 gene mutation (60% of cancers) or by lost of cell signalling upstream and downstream of p53 in the remaining cancers expressing WTp53 gene. As p53 pathway inactivation is a common denominator to all cancers, the underst...

  16. Metastatic prolactinoma: case report with immunohistochemical assessment for p53 and Ki-67 antigens Prolactinoma metastático: relato de caso com avaliação imuno-histoquímica para os antígenos p53 e Ki-67

    Directory of Open Access Journals (Sweden)

    Paulo S. Crusius

    2005-09-01

    Full Text Available Pituitary carcinomas are rare neoplasms characterized by craniospinal and/or systemic metastases originated from the pituitary. Their histopathology is frequently indistinguishable from that of benign adenomas. The development of markers that better reflect their behavior is desirable. We present the case of a 47 year-old man with a prolactin-secreting macroadenoma who was submitted to surgeries, cranial radiation therapy, and bromocriptine treatment, but evolved to a fatal outcome after the disclosure of intracranial metastases. Tumor samples underwent p53 and Ki-67 immunohistochemical assessment. p53 was absent in all samples, a rare finding among pituitary carcinomas. Ki-67 proliferative index was 2.80% in the original tumor, 4.40% in the relapse, and 4.45% in the metastasis. The figure in the relapse is higher than the expected for a noninvasive adenoma. In conclusion, p53 staining is not positive in all pituitary carcinomas. A high Ki-67 proliferative index in a pituitary adenoma might indicate a more aggressive behavior.Carcinomas pituitários são neoplasias raras caracterizadas pela presença de metástases cranio-espinhais e/ou sistêmicas originadas da hipófise. Sua histopatologia é freqüentemente indistinguível daquela dos adenomas benignos. O desenvolvimento de marcadores que melhor reflitam o seu comportamento é desejável. Apresentamos o caso de um homem de 47 anos com um macroadenoma secretor de prolactina que foi submetido a procedimentos cirúrgicos, radioterapia e tratamento com bromocriptina, mas que evoluiu para o óbito após o descobrimento de metástases intracranianas. Amostras do tumor foram submetidas à análise imuno-histoquímica para os antígenos p53 e Ki-67. A coloração para p53 foi negativa em todas as amostras, um achado raro entre os carcinomas pituitários. O índice proliferativo Ki-67 foi 2,80% no tumor original, 4,40% na recidiva e 4,45% na metástase. O valor obtido na recidiva é maior que o

  17. Xenogeneic human p53 DNA vaccination by electroporation breaks immune tolerance to control murine tumors expressing mouse p53.

    Directory of Open Access Journals (Sweden)

    Ruey-Shyang Soong

    Full Text Available The pivotal role of p53 as a tumor suppressor protein is illustrated by the fact that this protein is found mutated in more than 50% of human cancers. In most cases, mutations in p53 greatly increase the otherwise short half-life of this protein in normal tissue and cause it to accumulate in the cytoplasm of tumors. The overexpression of mutated p53 in tumor cells makes p53 a potentially desirable target for the development of cancer immunotherapy. However, p53 protein represents an endogenous tumor-associated antigen (TAA. Immunization against a self-antigen is challenging because an antigen-specific immune response likely generates only low affinity antigen-specific CD8(+ T-cells. This represents a bottleneck of tumor immunotherapy when targeting endogenous TAAs expressed by tumors. The objective of the current study is to develop a safe cancer immunotherapy using a naked DNA vaccine. The vaccine employs a xenogeneic p53 gene to break immune tolerance resulting in a potent therapeutic antitumor effect against tumors expressing mutated p53. Our study assessed the therapeutic antitumor effect after immunization with DNA encoding human p53 (hp53 or mouse p53 (mp53. Mice immunized with xenogeneic full length hp53 DNA plasmid intramuscularly followed by electroporation were protected against challenge with murine colon cancer MC38 while those immunized with mp53 DNA were not. In a therapeutic model, established MC38 tumors were also well controlled by treatment with hp53 DNA therapy in tumor bearing mice compared to mp53 DNA. Mice vaccinated with hp53 DNA plasmid also exhibited an increase in mp53-specific CD8(+ T-cell precursors compared to vaccination with mp53 DNA. Antibody depletion experiments also demonstrated that CD8(+ T-cells play crucial roles in the antitumor effects. This study showed intramuscular vaccination with xenogeneic p53 DNA vaccine followed by electroporation is capable of inducing potent antitumor effects against tumors

  18. Acetylation Is Indispensable for p53 Activation

    OpenAIRE

    Tang, Yi; Zhao, Wenhui; Chen, Yue; Zhao, Yingming; Gu, Wei

    2008-01-01

    The activation of the tumor suppressor p53 facilitates the cellular response to genotoxic stress; however, the p53 response can only be executed if its interaction with its inhibitor Mdm2 is abolished. There have been conflicting reports on the question of whether p53 posttranslational modifications, such as phosphorylation or acetylation, are essential or only play a subtle, fine-tuning role in the p53 response. Thus, it remains unclear whether p53 modification is absolutely required for its...

  19. Regulation of Mutant p53 Protein Expression

    OpenAIRE

    Vijayakumaran, Reshma; Tan, Kah Hin; Miranda, Panimaya Jeffreena; Haupt, Sue; Haupt, Ygal

    2015-01-01

    For several decades, p53 has been detected in cancer biopsies by virtue of its high protein expression level which is considered indicative of mutation. Surprisingly, however, mouse genetic studies revealed that mutant p53 is inherently labile, similar to its wild type (wt) counterpart. Consistently, in response to stress conditions, both wt and mutant p53 accumulate in cells. While wt p53 returns to basal level following recovery from stress, mutant p53 remains stable. In part, this can be e...

  20. Arginine methylation regulates the p53 response

    DEFF Research Database (Denmark)

    Jansson, Martin; Durant, Stephen T; Cho, Er-Chieh;

    2008-01-01

    Activation of the p53 tumour suppressor protein in response to DNA damage leads to apoptosis or cell-cycle arrest. Enzymatic modifications are widely believed to affect and regulate p53 activity. We describe here a level of post-translational control that has an important functional consequence on...... of p53. Furthermore, PRMT5 depletion triggers p53-dependent apoptosis. Thus, methylation on arginine residues is an underlying mechanism of control during the p53 response....

  1. p53 isoforms, Δ133p53 and p53β, are endogenous regulators of replicative cellular senescence

    OpenAIRE

    Fujita, Kaori; Mondal, Abdul M.; Horikawa, Izumi; Nguyen, Giang H.; Kumamoto, Kensuke; Sohn, Jane J.; Bowman, Elise D.; Mathe, Ewy A.; Schetter, Aaron J.; Pine, Sharon R.; Ji, Helen; Vojtesek, Borivoj; Bourdon, Jean-Christophe; Lane, David P; Harris, Curtis C.

    2009-01-01

    The finite proliferative potential of normal human cells leads to replicative cellular senescence, which is a critical barrier to tumour progression in vivo1–3. We show that human p53 isoforms (Δ133p53 and p53β)4 constitute an endogenous regulatory mechanism for p53-mediated replicative senescence. Induced p53β and diminished Δ133p53 were associated with replicative senescence, but not oncogene-induced senescence, in normal human fibroblasts. The replicatively senescent fibroblasts also expre...

  2. Radiation-induced p53 protein response in the A549 cell line is culture growth-phase dependent

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, N.F.; Gurule, D.M.; Carpenter, T.R.

    1995-12-01

    One role of the p53 tumor suppressor protein has been recently revealed. Kastan, M.B. reported that p53 protein accumulates in cells exposed to ionizing radiation. The accumulation of p53 protein is in response to DNA damage, most importantly double-strand breaks, that results from exposure to ionizing radiation. The rise in cellular p53 levels is necessary for an arrest in the G{sub 1} phase of the cell cycle to provide additional time for DNA repair. The p53 response has also been demonstrated to enhance PCNA-dependent repair. p53 is thus an important regulator of the cellular response to DNA-damaging radiation. From this data, it can be concluded that the magnitude of the p53 response is not dependent on the phase of culture growth.

  3. Radiation-induced p53 protein response in the A549 cell line is culture growth-phase dependent

    International Nuclear Information System (INIS)

    One role of the p53 tumor suppressor protein has been recently revealed. Kastan, M.B. reported that p53 protein accumulates in cells exposed to ionizing radiation. The accumulation of p53 protein is in response to DNA damage, most importantly double-strand breaks, that results from exposure to ionizing radiation. The rise in cellular p53 levels is necessary for an arrest in the G1 phase of the cell cycle to provide additional time for DNA repair. The p53 response has also been demonstrated to enhance PCNA-dependent repair. p53 is thus an important regulator of the cellular response to DNA-damaging radiation. From this data, it can be concluded that the magnitude of the p53 response is not dependent on the phase of culture growth

  4. Human papillomavirus and p53 protein immunoreactivity in condylomata acuminatum and squamous cell carcinoma of penis

    Institute of Scientific and Technical Information of China (English)

    Xin-Hua ZHANG; Gui-Qin SUN; Yu YANG; Tai-He ZHANG

    2001-01-01

    To determine the immunoreactive pattem of human papillomavirus (HPV) antigen and p53 protein in condylomata acuminatum (CA) and squamous cell carcinoma (SCC) of penis. Methods: Immunohistochemistry for HPV and p53 were performed in 40 specimens of formalin fixed, paraffin embedded tissues using a polyclonal (rabbit) antibody against HPV and a monoclonal (mouse) antibody against human p53 protein. Twenty one cases of CA and nineteen cases of SCC were examined. Results: HPV antigen was detected in all 21 CA and 2 penile SCC. p53 protein overexpression was observed in 12 of 19 (63%) SCC in which 6 cases were strong positive. Five of 21 CA (24%)showed low-grade p53 protein overexpression. Conclusion: CA is related to HPV infection and some cases show p53 protein low-grade overexpression. In contrast, p53 protein overexpression is common in penile SCC, which is seldom related to HPV infection.

  5. 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.

  6. p53 Acetylation: Regulation and Consequences

    International Nuclear Information System (INIS)

    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

  7. p53 Acetylation: Regulation and Consequences

    Directory of Open Access Journals (Sweden)

    Sara M. Reed

    2014-12-01

    Full Text Available 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.

  8. p53 gene mutations, p53 protein accumulation and compartmentalization in colorectal adenocarcinoma.

    OpenAIRE

    Bosari, S.; Viale, G.; Roncalli, M; Graziani, D.; Borsani, G; Lee, A. K.; Coggi, G.

    1995-01-01

    p53 accumulation may occur in the nucleus and/or cytoplasm of neoplastic cells. Cytoplasmic accumulation has been reported to be an unfavorable, but not established, prognostic indicator in colorectal cancer. Different types of p53 intracellular compartmentalization could depend either on p53 gene mutations or on the interaction with p53 protein ligands. The purposes of our study were (1) to assess whether the different patterns of p53 accumulation are selectively associated with p53 mutation...

  9. p53 Acetylation: Regulation and Consequences

    OpenAIRE

    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 ev...

  10. Non-p53 p53RE binding protein, a human transcription factor functionally analogous to P53

    OpenAIRE

    Zeng, Xiaoya; Levine, Arnold J.; Lu, Hua

    1998-01-01

    The transactivation activity of the p53 tumor suppressor protein is critical for regulating cell growth and apoptosis. We describe the identification of a transcription factor that is functionally similar to p53 and contains the same DNA binding and transcription activities specific for the p53 responsive DNA element (p53RE). This protein was highly purified through chromatography from HeLa cell extracts. The purified protein was able to bind specifically to the p53RE derived from a p21waf1 p...

  11. Constant rate of p53 tetramerization in response to DNA damage controls the p53 response

    OpenAIRE

    Gaglia, Giorgio; Lahav, Galit

    2014-01-01

    The dynamics of the tumor suppressor protein p53 have been previously investigated in single cells using fluorescently tagged p53. Such approach reports on the total abundance of p53 but does not provide a measure for functional p53. We used fluorescent protein-fragment complementation assay (PCA) to quantify in single cells the dynamics of p53 tetramers, the functional units of p53. We found that while total p53 increases proportionally to the input strength, p53 tetramers are formed in cell...

  12. P53-specific T cell responses in patients with malignant and benign ovarian tumors : Implications for p53 based immunotherapy

    NARCIS (Netherlands)

    Lambeck, Annechien; Leffers, Ninke; Hoogeboom, Baukje-Nynke; Sluiter, Wim; Hamming, Ineke; Klip, Harry; ten Hoor, Klaske; Esajas, Martha; van Oven, Magda; Drijfhout, Jan-Wouter; Platteel, Inge; Offringa, Rienk; Hollema, Harry; Melief, Kees; van der Burg, Sjoerd; van der Zee, Ate; Daemen, Toos; Nijman, Hans

    2007-01-01

    Despite intensive treatment, 70% of the ovarian cancer patients will develop recurrent disease, emphasizing the need for new approaches such as immunotherapy. A promising antigenic target for immunotherapy in ovarian cancer is the frequently overexpressed p53 protein. The aim of the study was to eva

  13. A role for PCNA ubiquitination in immunoglobulin hypermutation.

    Directory of Open Access Journals (Sweden)

    Hiroshi Arakawa

    2006-11-01

    Full Text Available Proliferating cell nuclear antigen (PCNA is a DNA polymerase cofactor and regulator of replication-linked functions. Upon DNA damage, yeast and vertebrate PCNA is modified at the conserved lysine K164 by ubiquitin, which mediates error-prone replication across lesions via translesion polymerases. We investigated the role of PCNA ubiquitination in variants of the DT40 B cell line that are mutant in K164 of PCNA or in Rad18, which is involved in PCNA ubiquitination. Remarkably, the PCNA(K164R mutation not only renders cells sensitive to DNA-damaging agents, but also strongly reduces activation induced deaminase-dependent single-nucleotide substitutions in the immunoglobulin light-chain locus. This is the first evidence, to our knowledge, that vertebrates exploit the PCNA-ubiquitin pathway for immunoglobulin hypermutation, most likely through the recruitment of error-prone DNA polymerases.

  14. Allele Specific p53 Mutant Reactivation

    OpenAIRE

    Yu, Xin; Vazquez, Alexei; Levine, Arnold J.; Carpizo, Darren R.

    2012-01-01

    Rescuing the function of mutant p53 protein is an attractive cancer therapeutic strategy. Using the NCI anticancer drug screen data, we identified two compounds from the thiosemicarbazone family that manifest increased growth inhibitory activity in mutant p53 cells, particularly for the p53R175 mutant. Mechanistic studies reveal that NSC319726 restores WT structure and function to the p53R175 mutant. This compound kills p53R172H knock-in mice with extensive apoptosis and inhibits xenograft tu...

  15. Gadd45a, a p53- and BRCA1-regulated stress protein, in cellular response to DNA damage

    International Nuclear Information System (INIS)

    Mammalian cells exhibit complex, but intricate cellular responses to genotoxic stress, including cell cycle checkpoints, DNA repair and apoptosis. Inactivation of these important biological events may result in genomic instability and cell transformation, as well as alterations of therapeutic sensitivity. Gadd45a, a p53- and BRCA1-regulated stress-inducible gene, has been characterized as one of the important players that participate in cellular response to a variety of DNA damage agents. Interestingly, the signaling machinery that regulates Gadd45a induction by genotoxic stress involves both p53-dependent and -independent pathways; the later may employ BRCA1-related or MAP kinase-mediated signals. Gadd45a protein has been reported to interact with multiple important cellular proteins, including Cdc2 protein kinase, proliferating cell nuclear antigen (PCNA), p21Waf1/Cip1 protein, core histone protein and MTK/MEKK4, an up-stream activator of the JNK/SAPK pathway, indicating that Gadd45a may play important roles in the control of cell cycle checkpoint, DNA repair process, and signaling transduction. The importance of Gadd45a in maintaining genomic integrity is well manifested by the demonstration that disruption of endogenous Gadd45a in mice results in genomic instability and increased carcinogenesis. Therefore, Gadd45a appears to be an important component in the cellular defense network that is required for maintenance of genomic stability

  16. PCNA Damage Caused by Anti-Neoplastic Drugs

    OpenAIRE

    Bae, Soo In; Zhao,Ran; Snapka, Robert M.

    2008-01-01

    Structurally diverse chemotherapeutic and chemopreventive drugs, including camptothecin, doxorubicin, sanguinarine, and others, were found to cause covalent crosslinking of proliferating cell nuclear antigen (PCNA) trimers in mammalian cells exposed to fluorescent light. This PCNA damage was caused by both nuclear and cytoplasmically localizing drugs. For some drugs, the PCNA crosslinking was evident even with very brief exposures to laboratory room lighting. In the absence of drugs, there wa...

  17. Updates on p53: modulation of p53 degradation as a therapeutic approach

    OpenAIRE

    Dey, A; Verma, C S; LANE, D. P.

    2008-01-01

    The p53 pathway is aberrant in most human tumours with over 50% expressing mutant p53 proteins. The pathway is critically controlled by protein degradation. Here, we discuss the latest developments in the search for small molecules that can modulate p53 pathway protein stability and restore p53 activity for cancer therapy.

  18. Cellular functions of p53 and p53 gene family members p63 and p73

    Directory of Open Access Journals (Sweden)

    Nadir Koçak

    2011-12-01

    Full Text Available p53 is a transcription factor that regulates multiple cellular processes that are also important in cellular fates such as cell cycle arrest or programmed cell death. Induction of growth arrest or cell death by p53 prevents the replication of damaged DNA and proliferation of genetically abnormal cells. Therefore, inactivation of p53 by mutation or deletion is also important in ensuring the cellular homeostasis. However, studies showed that p53 deficient mice and cells such as Saos-2 cells are maintaining their life. This situation suggests that p53-related proteins might compensate the functions of p53 in p53 deficient organisms. The identification of two p53-related proteins, p63 and p73 revealed the transcription of p53 responsive genes in p53 deficient organisms. Both p63 and p73 proteins have high homology with the p53 protein and share some of the functions of p53. In contrast to p53, p63 and p73 rarely mutated in human cancers. Here we studied to summarize the current information about the p53 and other p53-related proteins, p63 and p73 that are included into the p53 gene family.

  19. The relationship between sirtuin 1 (SIRT1 expression and tumor size, Proliferating Cell Nuclear Antigen (PCNA expression and histological grading in rat breast carcinoma induced by dimethylbenz(anthracene (DMBA

    Directory of Open Access Journals (Sweden)

    Novrita Padauleng Dewajani Purnomosari, Sri Herwiyanti Harjadi, Irianiwati, Sitarina Widyarini

    2014-08-01

    Full Text Available Controversy regarding the role of SIRT1 in pathology of cancers exists and is still under debate.SIRT1 could act as either a tumor supressor or tumor promotor. This study was conducted toevaluate the relationship between SIRT1 expression and tumor size, Proliferating Cell NuclearAntigen (PCNA expression and histological grading in rat breast carcinoma induced bydimethylbenz(áanthracene (DMBA. Thirty female Sprague Dawley rats were randomly allocatedinto three groups with 10 rats in each group. Group 1 as negative control was just fed thestandard food. Group 2 as vehicle control was fed the standard food and corn oil. Group 3 asinduction group was fed the standard food and induced with DMBA at dose of 20 mg/kg bodyweight (BW in corn oil twice a week for five weeks. All rats were palpated weekly to determinethe appearance, size and location of tumors. Sixteen weeks after DMBA induction rats weresacrified and histological preparations of the breast carcinoma tissue were then processed forSIRT1 and PCNA expression examination as well as histological grading. The result showed thatSIRT1 expression was significantly higher in breast carcinoma tissue compared to normal gland(26.12 vs 0.05; p = 0.004. SIRT1-positive was observed mostly in poor histological gradecarcinomas (56.2%, and it was not observed in good histological grade carcinomas. However,there was no significantly difference between SIRT1 and histological grading (p = 0.097; r =0.285. A significant correlation between SIRT1 expression and the tumor size (p =0.009; r=0.877, as well as PCNA expression (p =0.000; r =0.790 was observed. In conclusion, thereis relationship between SIRT1 expression and tumor size as well as PCNA expression in rat breastcarcinoma induced by DMBA.

  20. Tumor suppressor p53: analysis of wild-type and mutant p53 complexes.

    OpenAIRE

    Milner, J; Medcalf, E A; Cook, A. C.

    1991-01-01

    It has been suggested that the dominant effect of mutant p53 on tumor progression may reflect the mutant protein binding to wild-type p53, with inactivation of suppressor function. To date, evidence for wild-type/mutant p53 complexes involves p53 from different species. To investigate wild-type/mutant p53 complexes in relation to natural tumor progression, we sought to identify intraspecific complexes, using murine p53. The mutant phenotype p53-246(0) was used because this phenotype is immuno...

  1. DNA-mediated oxidation of p53.

    Science.gov (United States)

    Schaefer, Kathryn N; Barton, Jacqueline K

    2014-06-01

    Transcription factor p53 is the most commonly altered gene in human cancer. As a redox-active protein in direct contact with DNA, p53 can directly sense oxidative stress through DNA-mediated charge transport. Electron hole transport occurs over long distances through the π-stacked bases and leads to the oxidative dissociation of p53. The extent of protein dissociation depends upon the redox potential of the DNA in direct contact with each p53 monomer. The DNA sequence dependence of p53 oxidative dissociation was examined by electrophoretic mobility shift assays using oligonucleotides containing both synthetic and human p53 consensus sequences with an appended photooxidant, anthraquinone. Greater p53 dissociation is observed from sequences containing low-redox potential purine regions, particularly guanine triplets. Using denaturing polyacrylamide gel electrophoresis of irradiated anthraquinone-modified DNA, the DNA damage sites corresponding to sites of preferred electron hole localization were determined. The resulting DNA damage preferentially localizes to guanine doublets and triplets. Oxidative DNA damage is inhibited in the presence of p53, but only at sites in direct contact with p53. From these data, predictions about the sensitivity of human p53-binding sites to oxidative stress as well as possible biological implications have been made. On the basis of our data, the guanine pattern within the purine region of each p53-binding site determines the response of p53 to DNA oxidation, yielding for some sequences the oxidative dissociation of p53 from a distance and thereby providing another potential role for DNA charge transport chemistry within the cell. PMID:24853816

  2. Regulation of PCNA-protein interactions for genome stability

    DEFF Research Database (Denmark)

    Mailand, Niels; Gibbs-Seymour, Ian; Bekker-Jensen, Simon

    2013-01-01

    Proliferating cell nuclear antigen (PCNA) has a central role in promoting faithful DNA replication, providing a molecular platform that facilitates the myriad protein-protein and protein-DNA interactions that occur at the replication fork. Numerous PCNA-associated proteins compete for binding to ...

  3. ROS and p53: versatile partnership

    OpenAIRE

    Liu, Bin; Chen, Yumin; St. Clair, Daret K.

    2008-01-01

    The tumor suppressor protein p53 is a redox active transcription factor that organizes and directs cellular responses in the face of a variety of stresses that lead to genomic instability. One of the most important questions in the study of p53 is how selective transactivation of certain p53 target genes is achieved. Reactive oxygen species (ROS), generated by cells as products or byproducts, can function either as signaling molecules or as cellular toxicants. Cellular generation of ROS is ce...

  4. Regulation of p53 in response to ionizing radiation in ataxia telangiectasia fibroblasts

    International Nuclear Information System (INIS)

    Purpose: An analysis of the structure and expression of p53 in fibroblasts from patients with ataxia telangiectasia (AT) is presented. Methods and Materials: p53 status in primary and SV40 T antigen-transformed AT cell lines was analyzed using immunocytochemistry and by sequencing with the dideoxynucleotide termination method. The expression of p53 transcript was measured by Northern analysis. The kinetics of p53 protein expression and DNA-binding activity were measured at various intervals following irradiation. Results: No mutation of p53 sequences was found in AT cells. Decreased levels of p53 mRNA and protein were observed in AT5BIVA cells compared to other SV40 T antigen-immortalized fibroblasts. Furthermore, DNA-binds binding analysis shows that a fraction of p53 in the nuclear extracts from AT5BIVA is regulated and binds to specific DNA sequence following irradiation. Conclusion: These data provide evidence for a heterogeneity of the p53 function in SV40-transformed AT cells. It also supports the hypothesis that a regulatory mechanism of p53 activity remains in T antigen-expressing cells in response to ionizing radiation damage

  5. HCV NS5A abrogates p53 protein function by interfering with p53-DNA binding

    Institute of Scientific and Technical Information of China (English)

    Guo-Zhong Gong; Yong-Fang Jiang; Yan He; Li-Ying Lai; Ying-Hua Zhu; Xian-Shi Su

    2004-01-01

    AIM: To evaluate the inhibition effect of HCV NS5A on p53 transactivation on p21 promoter and explore its possible mechanism for influencing p53 function.METHODS: p53 function of transactivation on p21 promoter was studied with a luciferase reporter system in which the luciferase gene is driven by p21 promoter, and the p53-DNA binding ability was observed with the use of electrophoretic mobility-shift assay (EMSA). Lipofectin mediated p53 or HCV NS5A expression vectors were used to transfect hepatoma cell lines to observe whether HCV NS5A could abrogate the binding ability of p53 to its specific DNA sequence and p53 transactivation on p21 promoter.Western blot experiment was used for detection of HCV NS5A and p53 proteins expression.RESULTS: Relative luciferase activity driven by p21 promoter increased significantly in the presence of endogenous p53 protein. Compared to the control group, exogenous p53 protein also stimulated p21 promoter driven luciferase gene expression in a dose-dependent way. HCV NS5A protein gradually inhibited both endogenous and exogenous p53 transactivation on p21 promoter with increase of the dose of HCV NS5A expression plasmid. By the experiment of EMSA, we could find p53 binding to its specific DNA sequence and, when co-transfected with increased dose of HCV NS5A expression vector, the p53 binding affinity to its DNA gradually decreased and finally disappeared. Between the Huh 7 cells transfected with p53 expression vector alone or co-transfected with HCV NS5A expression vector, there was no difference in the p53 protein expression.CONCLUSION: HCV NS5A inhibits p53 transactivation on p21 promoter through abrogating p53 binding affinity to its specific DNA sequence. It does not affect p53 protein expression.

  6. 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.

  7. Dominant effects of Δ40p53 on p53 function and melanoma cell fate

    OpenAIRE

    Takahashi, Rie; Markovic, Svetomir; Scrable, Heidi

    2013-01-01

    The p53 gene encodes 12 distinct isoforms some of which can alter p53 activity in the absence of genomic alteration. Endogenous p53 isoforms have been identified in cancers; however, the function of these isoforms remains unclear. In melanoma, the frequency of p53 mutations is relatively low compared to other cancers suggesting that these isoforms may play a larger role in regulating p53 activity. We hypothesized that p53 function and therefore cell fate might be altered by the presence of Δ4...

  8. p53: The Janus of autophagy?

    OpenAIRE

    Levine, Beth; Abrams, John

    2008-01-01

    The autophagy pathway functions in adaptation to nutrient stress and tumour suppression. The p53 tumour suppressor, previously thought to positively regulate autophagy, may also inhibit it. This dual interplay between p53 and autophagy regulation is enigmatic, but may underlie key aspects of metabolism and cancer biology.

  9. p53 mutant breast cancer patients expressing p53γ have as good a prognosis as wild-type p53 breast cancer patients

    OpenAIRE

    Bourdon, Jean-Christophe; Khoury, Marie,; Diot, Alexandra; Baker, Lee; Fernandes, Kenneth; Aoubala, Mustapha; Quinlan, Philip; Purdie, Colin; Jordan, Lee; Prats, Anne-Catherine; Lane, David; Thompson, Alastair

    2011-01-01

    International audience INTRODUCTION: Normal function of the p53 network is lost in most cancers, often through p53 mutation. The clinical impact of p53 mutations in breast cancer remains uncertain, especially where p53 isoforms may modify the effects of these p53 mutations. METHODS: Expression of p53β and p53γ isoforms, the isoforms identified in normal breast tissue, was detected by reverse transcription polymerase chain reaction from a cohort of 127 primary breast tumours. Expression of ...

  10. Cellular functions of p53 and p53 gene family members p63 and p73

    OpenAIRE

    Nadir Koçak; İbrahim Halil Yıldırım; Seval Cing Yıldırım

    2011-01-01

    p53 is a transcription factor that regulates multiple cellular processes that are also important in cellular fates such as cell cycle arrest or programmed cell death. Induction of growth arrest or cell death by p53 prevents the replication of damaged DNA and proliferation of genetically abnormal cells. Therefore, inactivation of p53 by mutation or deletion is also important in ensuring the cellular homeostasis. However, studies showed that p53 deficient mice and cells such as Saos-2 cells are...

  11. The heme–p53 interaction: Linking iron metabolism to p53 signaling and tumorigenesis

    OpenAIRE

    Shen, Jia; Sheng, Xiangpeng; Chang, ZeNan; Wu, Qian; Xie, Dong; Wang, Fudi; HU, Ronggui

    2014-01-01

    Recently, we reported that heme binds to tumor suppressor p53 protein (TP53, best known as p53) and promotes its nuclear export and cytosolic degradation, whereas iron chelation stabilizes p53 protein and suppresses tumors in a p53-dependent manner. This not only provides mechanistic insights into tumorigenesis associated with iron excess, but also helps guide the administration of chemotherapy based on iron deprivation in the clinic.

  12. Wildtype p53-specific Antibody and T-Cell Responses in Cancer Patients

    DEFF Research Database (Denmark)

    Pedersen, Anders Elm; Stryhn, Anette; Justesen, Sune;

    2011-01-01

    Mutation in the p53 gene based on single amino acid substitutions is a frequent event in human cancer. Accumulated mutant p53 protein is released to antigen presenting cells of the immune system and anti-p53 immune responses even against wt p53 is induced and observed in a number of human cancer...... patients. Detection of antibodies against wt p53 protein has been used as a diagnostic and prognostic marker and discovery of new T-cell epitopes has enabled design of cancer vaccination protocols with promising results. Here, we identified wt p53-specific antibodies in various cancer patients and...... identified a broad range of responses against wt p53 protein and 15-mer peptides using a novel print array technology. Likewise, using bioinformatic tools in silico, we identified CD8 T-cell specificity or reactivity against HLA-A*02:01 binding peptides wt p53(65-73), wt p53(187-197), and wt p53(264-272) in...

  13. Tumor suppressor p53 response is blunted

    International Nuclear Information System (INIS)

    The biological effect of low-dose radiation has been a focus of research interest in recent years because this area has important implications for radiation protection at doses of 0-1 Gy. At present, there is a lack of substantial evidence to indicate harmful effects of these low doses, in contrast, epidemiological data regarding the cancer incidence from areas with high background radiation levels seem to favor a beneficial effect of chronic low-dose radiation. To strengthen these aspects of radiation science, more molecular evidence on the cellular response to low doses is required. In the field of tumor biology, p53 may be one of the best studied molecules. Besides its function as a potent tumor suppressor, p53 is also found to govern G1 and/or G2/M checkpoint response in cells under stressful conditions. One of the mediators of p53 is waf1, an inhibitor of cyclin-dependent kinase. By inducing cell cycle arrest or apoptosis and probably DNA repair, activation of the p53-dependent signal transduction pathway minimizes the inheritance of damaged genetic information thereby maintaining genomic stability. Recently, we and other investigators found that the agents that evoke the p53 pathway are not limited to DNA-damaging agents but also include non-DNA-damaging stressors. Therefore, p53 may also be viewed as a major player in maintaining cellular homeostasis. Acute low dose irradiation (0.1-1 Gy, 1.33 Gy/min) of a human glioblastoma cell line, A-172 (wp53) induced a dose-dependent monophasic accumulation of p53 and wild-type p53 activated factor-1, WAF1. Different from this, chronic γ-irradiation (0.001 Gy/min) produced a clear biphasic response of p53 accumulation with the first peak at 1.5 h (0.09 Gy) and the second peak at 10 h (0.54 Gy). Significantly when the cells were pre-irradiated with chronic γ-irradiation for 24 h (1.44 Gy) or 50 h (3 Gy), they could no longer response to the second acute challenging irradiation to produce a dose-dependent response of

  14. Immune response to p53 is dependent upon p53/HSP70 complexes in breast cancers.

    OpenAIRE

    Davidoff, A.M.; Iglehart, J D; Marks, J R

    1992-01-01

    Overexpression of the p53 protein, resulting from gene mutations that increase protein stability, has been detected in greater than 25% of primary human breast cancers. In addition, approximately 10% of breast cancer patients have circulating antibodies to the p53 protein. In this study, the anti-p53 humoral response is correlated with the presence and type of mutant p53 protein expressed in the tumor. In a series of 60 breast cancer patients, 0 of 30 tumors with normal, low-level p53 express...

  15. Global genomic profiling reveals an extensive p53-regulated autophagy program contributing to key p53 responses

    OpenAIRE

    Kenzelmann Broz, Daniela; Spano Mello, Stephano; Bieging, Kathryn T.; Jiang, Dadi; Rachel L Dusek; Brady, Colleen A.; Sidow, Arend; Attardi, Laura D.

    2013-01-01

    To gain new insights into p53 biology, Kenzelmann Broz et al. used high-throughput sequencing to analyze global p53 transcriptional networks in primary mouse embryo fibroblasts in response to DNA damage. This approach identified autophagy genes as direct p53 target genes. p53-induced autophagy was important for both p53-dependent apoptosis and transformation suppression by p53. These data highlight an intimate connection between p53 and autophagy and suggest that autophagy contributes to p53-...

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

    International Nuclear Information System (INIS)

    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)

  17. Hormonal control of p53 and chemoprevention

    International Nuclear Information System (INIS)

    Improvements in the detection and treatment of breast cancer have dramatically altered its clinical course and outcome. However, prevention of breast cancer remains an elusive goal. Parity, age of menarche, and age at menopause are major risk factors drawing attention to the important role of the endocrine system in determining the risk of breast cancer, while heritable breast cancer susceptibility syndromes have implicated tumor suppressor genes as important targets. Recent work demonstrating hormonal modulation of the p53 tumor suppressor pathway draws together these established determinants of risk to provide a model of developmental susceptibility to breast cancer. In this model, the mammary epithelium is rendered susceptible due to impaired p53 activity during specific periods of mammary gland development, but specific endocrine stimuli serve to activate p53 function and to mitigate this risk. The results focus attention on p53 as a molecular target for therapies to reduce the risk of breast cancer

  18. Regulation and spatial organization of PCNA in Trypanosoma brucei

    International Nuclear Information System (INIS)

    Highlights: ► Characterization of the proliferating cell nuclear antigen in Trypanosoma brucei (TbPCNA). ► TbPCNA is a suitable marker to detect replication in T. brucei. ► TbPCNA distribution and regulation is different compared to closely related parasites T. cruzi and Leishmania donovani. -- Abstract: As in most eukaryotic cells, replication is regulated by a conserved group of proteins in the early-diverged parasite Trypanosoma brucei. Only a few components of the replication machinery have been described in this parasite and regulation, sub-nuclear localization and timing of replication are not well understood. We characterized the proliferating cell nuclear antigen in T. brucei (TbPCNA) to establish a spatial and temporal marker for replication. Interestingly, PCNA distribution and regulation is different compared to the closely related parasites Trypanosoma cruzi and Leishmania donovani. TbPCNA foci are clearly detectable during S phase of the cell cycle but in contrast to T. cruzi they are not preferentially located at the nuclear periphery. Furthermore, PCNA seems to be degraded when cells enter G2 phase in T. brucei suggesting different modes of replication regulation or functions of PCNA in these closely related eukaryotes.

  19. Regulation and spatial organization of PCNA in Trypanosoma brucei

    Energy Technology Data Exchange (ETDEWEB)

    Kaufmann, Doris; Gassen, Alwine [University of Munich (LMU), Department Biology I, Genetics, Grosshaderner Str. 2-4, 82152 Martinsried (Germany); Maiser, Andreas; Leonhardt, Heinrich [University of Munich (LMU), Department Biology II, Grosshaderner Str. 2-4, 82152 Martinsried (Germany); Janzen, Christian J., E-mail: christian.janzen@uni-wuerzburg.de [University of Munich (LMU), Department Biology I, Genetics, Grosshaderner Str. 2-4, 82152 Martinsried (Germany)

    2012-03-23

    Highlights: Black-Right-Pointing-Pointer Characterization of the proliferating cell nuclear antigen in Trypanosoma brucei (TbPCNA). Black-Right-Pointing-Pointer TbPCNA is a suitable marker to detect replication in T. brucei. Black-Right-Pointing-Pointer TbPCNA distribution and regulation is different compared to closely related parasites T. cruzi and Leishmania donovani. -- Abstract: As in most eukaryotic cells, replication is regulated by a conserved group of proteins in the early-diverged parasite Trypanosoma brucei. Only a few components of the replication machinery have been described in this parasite and regulation, sub-nuclear localization and timing of replication are not well understood. We characterized the proliferating cell nuclear antigen in T. brucei (TbPCNA) to establish a spatial and temporal marker for replication. Interestingly, PCNA distribution and regulation is different compared to the closely related parasites Trypanosoma cruzi and Leishmania donovani. TbPCNA foci are clearly detectable during S phase of the cell cycle but in contrast to T. cruzi they are not preferentially located at the nuclear periphery. Furthermore, PCNA seems to be degraded when cells enter G2 phase in T. brucei suggesting different modes of replication regulation or functions of PCNA in these closely related eukaryotes.

  20. Inhibition of NAMPT pathway by FK866 activates the function of p53 in HEK293T cells

    International Nuclear Information System (INIS)

    Highlights: ► In 293T cells, p53 is considered to be inactive due to its interaction with the large T-antigen. ► Acetylation of p53 at lysine 382 is important for its functional activation. ► First evidence to document the presence of a functional p53 in 293T cells. ► Inhibition of NAMPT/SIRT pathway by FK866 in 293T cells increases the functional activity of p53. ► This activation of p53 involves reversible acetylation of p53 at lysine 382. -- Abstract: Inactivation of p53 protein by endogenous and exogenous carcinogens is involved in the pathogenesis of different human malignancies. In cancer associated with SV-40 DNA tumor virus, p53 is considered to be non-functional mainly due to its interaction with the large T-antigen. Using the 293T cell line (HEK293 cells transformed with large T antigen) as a model, we provide evidence that p53 is one of the critical downstream targets involved in FK866-mediated killing of 293T cells. A reduced rate of apoptosis and an increased number of cells in S-phase was accompanied after knockdown of p53 in these cells. Inhibition of NAMPT by FK866, or inhibition of SIRT by nicotinamide decreased proliferation and triggered death of 293T cells involving the p53 acetylation pathway. Additionally, knockdown of p53 attenuated the effect of FK866 on cell proliferation, apoptosis, and cell cycle arrest. The data presented here shed light on two important facts: (1) that p53 in 293T cells is active in the presence of FK866, an inhibitor of NAMPT pathway; (2) the apoptosis induced by FK866 in 293T cells is associated with increased acetylation of p53 at Lys382, which is required for the functional activity of p53.

  1. Correlation of p53 gene mutation and expression of P53 protein in cholangiocarcinoma

    Institute of Scientific and Technical Information of China (English)

    Xiao-Fang Liu; Hao Zhang; Shi-Guang Zhu; Xian-Ting Zhou; Hai-Long Su; Zheng Xu; Shao-Jun Li

    2006-01-01

    AIM: To characterize the tumor suppressor gene p53 mutations and study the correlation of p53 gene mutation and the expression of P53 protein in cholangiocarcinoma.METHODS: A total of 36 unselected, frozen samples of cholangiocarcinoma were collected. p53 gene status(exon 5-8) and P53 protein were examined by automated sequencing and immunohistochemical staining, combined with the clinical parameters of patients.RESULTS: p53 gene mutations were found in 22 of 36 (61.1%) patients. Nineteen of 36 (52.8%) patients were positive for P53 protein expression. There were significant differences in extent of differentiation and invasion between the positive and negative expression of P53 protein. However, there were no significant differences in pathologic parameters between the mutations and non-mutations.CONCLUSION: The alterations of the p53 gene evaluated by DNA sequence analysis is relatively accurate. Expression of P53 protein could not act as an independent index to estimate the prognosis of cholangiocarcinoma.

  2. Expression of p53 in endometrial polyps with special reference to the p53 signature.

    Science.gov (United States)

    Sho, Tomoko; Hachisuga, Toru; Kawagoe, Toshinori; Urabe, Rie; Kurita, Tomoko; Kagami, Seiji; Shimajiri, Shohei; Fujino, Yoshihisa

    2016-07-01

    We herein examined the significance of the p53 expression in endometrial polyps (EMPs). A total of 133 EMPs, including 62 premenopausal and 71 postmenopausal women with EMP, were immunohistochemically studied for the expression of estrogen receptor (ER)-alpha, Ki-67 and p53. Apoptotic cells were identified using a TUNEL assay. A DNA sequence analysis of TP53 exons 5 to 9 was performed. Among the premenopausal EMPs, a multivariate analysis showed the labeling index (LI) for Ki-67 to correlate significantly with that for p53 (PEMPs, the LI for Ki-67 correlated significantly with that for apoptosis (PEMPs (mean age: 70.2 years). The median Ki-67 index for the p53S was 7%, with no significant difference from that of the glands of the postmenopausal EMPs without the p53S (P=0.058). The median apoptotic index for the p53S was 0%, which was significantly lower than that of the postmenopausal EMPs without the p53S (P=0.002). Two of four p53Ss showed TP53 mutations according to the DNA sequence analysis. The presence of the p53S is not rare in postmenopausal EMPs with an advanced age. Among postmenopausal EMPs, the LI of Ki-67 significantly correlates with that of apoptosis. However, such a positive correlation between the LI of Ki-67 and apoptosis is not observed in p53S. PMID:26727623

  3. Effects of Δ40p53, an isoform of p53 lacking the N-terminus, on transactivation capacity of the tumor suppressor protein p53

    International Nuclear Information System (INIS)

    The p53 protein is expressed as multiple isoforms that differ in their N- and C-terminus due to alternative splicing, promoter or codon initiation usage. Δ40p53 lacks the first 39 residues containing the main transcriptional activation domain, resulting from initiation of translation at AUG +40 in fully spliced p53 mRNA or in a specific variant mRNA retaining intron 2. Overexpression of Δ40p53 antagonizes wild-type p53 in vitro. However, animal models of Δ40p53 in mouse or Zebrafish have shown complex phenotypes suggestive of p53-dependent growth suppressive effects. We have co-transfected expression vectors for p53 and Δ40p53 in p53-null cell lines Saos-2 and H1299 to show that Δ40p53 forms mixed oligomers with p53 that bind to DNA and modulate the transcription of a generic p53-dependent reporter gene. In H1299 cells, co-expression of the two proteins induced a decrease in transcription with amplitude that depended upon the predicted composition of the hetero-tetramer. In Saos-2, a paradoxical effect was observed, with a small increase in activity for hetero-tetramers predicted to contain 1 or 2 monomers of Δ40p53 and a decrease at higher Δ40p53/p53 ratios. In this cell line, co-transfection of Δ40p53 prevented Hdm2-mediated degradation of p53. Δ40p53 modulates transcriptional activity by interfering with the binding of Hdm2 to hetero-tetramers containing both Δ40p53 and p53. These results provide a basis for growth suppressive effects in animal models co-expressing roughly similar levels of p53 and Δ40p53

  4. The tumor suppressor p53 regulates its own transcription.

    OpenAIRE

    Deffie, A; H. Wu; Reinke, V.; Lozano, G.

    1993-01-01

    The ability of p53 to suppress transformation correlates with its ability to activate transcription. To identify targets of p53 transactivation, we examined the p53 promoter itself. Northern (RNA) analysis and transient transfection experiments showed that p53 transcriptionally regulated itself. A functionally inactive mutant p53 could not regulate the p53 promoter. Deletion analysis of the p53 promoter delineated sequences between +22 and +67 as being critical for regulation. Electrophoretic...

  5. p53-directed translational control can shape and expand the universe of p53 target genes.

    Science.gov (United States)

    Zaccara, S; Tebaldi, T; Pederiva, C; Ciribilli, Y; Bisio, A; Inga, A

    2014-10-01

    The increasing number of genome-wide transcriptome analyses focusing on p53-induced cellular responses in many cellular contexts keeps adding to the already numerous p53-regulated transcriptional networks. To investigate post-transcriptional controls as an additional dimension of p53-directed gene expression responses, we performed a translatome analysis through polysomal profiling on MCF7 cells upon 16 hours of doxorubicin or nutlin-3a treatment. The comparison between the transcriptome and the translatome revealed a considerable level of uncoupling, characterized by genes whose transcription variations did not correlate with translation variations. Interestingly, uncoupled genes were associated with apoptosis, DNA and RNA metabolism and cell cycle functions, suggesting that post-transcriptional control can modulate classical p53-regulated responses. Furthermore, even for well-established p53 targets that were differentially expressed both at the transcriptional and translational levels, quantitative differences between the transcriptome, subpolysomal and polysomal RNAs were evident. As we searched mechanisms underlying gene expression uncoupling, we identified the p53-dependent modulation of six RNA-binding proteins, where hnRNPD (AUF1) and CPEB4 are direct p53 transcriptional targets, whereas SRSF1, DDX17, YBX1 and TARDBP are indirect targets (genes modulated preferentially in the subpolysomal or polysomal mRNA level) modulated at the translational level in a p53-dependent manner. In particular, YBX1 translation appeared to be reduced by p53 via two different mechanisms, one related to mTOR inhibition and the other to miR-34a expression. Overall, we established p53 as a master regulator of translational control and identified new p53-regulated genes affecting translation that can contribute to p53-dependent cellular responses. PMID:24926617

  6. p53-directed translational control can shape and expand the universe of p53 target genes

    OpenAIRE

    Zaccara, S; Tebaldi, T; Pederiva, C; Ciribilli, Y; Bisio, A.; Inga, A

    2014-01-01

    The increasing number of genome-wide transcriptome analyses focusing on p53-induced cellular responses in many cellular contexts keeps adding to the already numerous p53-regulated transcriptional networks. To investigate post-transcriptional controls as an additional dimension of p53-directed gene expression responses, we performed a translatome analysis through polysomal profiling on MCF7 cells upon 16 hours of doxorubicin or nutlin-3a treatment. The comparison between the transcriptome and ...

  7. Suppression of glucosylceramide synthase restores p53-dependent apoptosis in mutant p53 cancer cells

    OpenAIRE

    Liu, Yong-Yu; Patwardhan, Gauri A.; Bhinge, Kaustubh; Gupta, Vineet; Gu, Xin; Jazwinski, S. Michal

    2011-01-01

    Tumor suppressor p53 plays an essential role in protecting cells from malignant transformation by inducing cell cycle arrest and apoptosis. Mutant p53 that is detected in over 50% cases of cancers not only loses its role in suppressing of tumor but also gains oncogenic function. Strategies to convert mutant p53 into wild-type of p53 have been suggested for cancer prevention and treatment, but they face a variety of challenges. Here we report an alternate approach that involves suppression of ...

  8. Viral Oncoproteins Discriminate between p53 and the p53 Homolog p73

    OpenAIRE

    Marin, Maria Carmen; Jost, Christine A.; Irwin, Meredith S; DeCaprio, James A.; Caput, Daniel; William G Kaelin

    1998-01-01

    p73 is a recently identified member of the p53 family. Previously it was shown that p73 can, when overproduced in p53-defective tumor cells, activate p53-responsive promoters and induce apoptosis. In this report we describe the generation of anti-p73 monoclonal antibodies and confirm that two previously described p73 isoforms are produced in mammalian cells. Furthermore, we show that these two isoforms can bind to canonical p53 DNA-binding sites in electrophoretic mobility shift assays. Despi...

  9. 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

  10. p53 regulation and activity in mouse embryonic stem cells

    OpenAIRE

    Solozobova, Valeriya

    2010-01-01

    P53 is a tumour development p53. The aim of this work was to study the regulation of p53 in embryonic stem cells and its activation in response to DNA damage. p53 was found that p53 becomes transcriptionally active in ES cells after DNA damage. Embryonic stem cells contain a relatively high amount of p53 protein and p53 RNA. After differentiation p53 level is rapidly downregulated. The high abundance of p53 in undifferentiated ES cells is a result of enhanced translation.

  11. Molecular mechanism of p53-mediatedtumor suppressionin p53-WT breast cancerusing ChIP-seq data%基于乳腺癌ChIP-seq数据的p53抑癌机制研究

    Institute of Scientific and Technical Information of China (English)

    王立山; 祝鹏飞; 祁福娟; 曹鑫恺; 孔艳; 臧卫东

    2014-01-01

    To unveilthe molecular mechanism of p53-mediated tumor suppression in p53-WT breast cancervia analyzing ChIP-seq (chromatin immunoprecipitation-sequencing) data by bioinformatics methods. ChIP-Seq dataset GSE47041 was downloaded from Gene Expression Omnibus, which includes three groups of samples:untreatedMCF-7 cells (NS_input), MCF-7 cells treated with a Mdm2 antagonist Nutlin-3a ( S_input ) , Nutlin-3a-treated MCF-7 cells plus p53 antibody treatment (S_p53).The obtained DNA fragments were sequenced using the Illumina HiSeq 2000 platform. Sequence alignment was performed with reference to hg19 using Bowtie; peak calling was performed using MACS; a self-programmed software was used to detect p53 target genes. A total of 50 p53 target genes were predicted. Among them, eight (CDKN1A, BBC3, BAX, DDB2, MDM2, CCNG1,XPC and PCNA) were enriched in p53 signaling transduction pathway and nucleotide excision repairing pathways respectively. A protein-protein interaction network consisting of 19 target genes was obtained;PCNA, MDM2, REV3L, CDKN1A and BAX were the top five genes with the highest degrees of connection. The methods recruited to investigate the molecular mechanism underlying p53-mediated tumor suppression in p53-WT MCF-7 breast cancer cells based on ChIP-seq data are proven feasible and reliable.%采用生物信息学方法分析野生型p53乳腺癌MCF7细胞的ChIP-seq(染色质免疫共沉淀-测序)数据,以揭示p53的抑癌分子机制。从NCBI下载的编号为GSE47041的ChIP-seq数据来源于三组试验,分别为:未经处理的乳腺癌MCF7细胞对照( NS_input),Nutlin-3a(一种MDM2拮抗剂)处理的MCF7细胞对照( S_input)和Nutlin-3a刺激MCF7细胞后加入p53抗体的实验组( S_p53)。 ChIP 获得的DNA数据的测序平台为Illumina HiSeq 2000。利用Bowtie参照人基因组hg19进行序列比对;利用MACS进行峰信号检测,并利用自定义软件筛选p53可能的靶基因;利用DAVID在线工具对靶基因进行通路富

  12. 基于乳腺癌ChIP-seq数据的p53抑癌机制研究%Molecular mechanism of p53-mediatedtumor suppressionin p53-WT breast cancerusing ChIP-seq data

    Institute of Scientific and Technical Information of China (English)

    王立山; 祝鹏飞; 祁福娟; 曹鑫恺; 孔艳; 臧卫东

    2014-01-01

    To unveilthe molecular mechanism of p53-mediated tumor suppression in p53-WT breast cancervia analyzing ChIP-seq (chromatin immunoprecipitation-sequencing) data by bioinformatics methods. ChIP-Seq dataset GSE47041 was downloaded from Gene Expression Omnibus, which includes three groups of samples:untreatedMCF-7 cells (NS_input), MCF-7 cells treated with a Mdm2 antagonist Nutlin-3a ( S_input ) , Nutlin-3a-treated MCF-7 cells plus p53 antibody treatment (S_p53).The obtained DNA fragments were sequenced using the Illumina HiSeq 2000 platform. Sequence alignment was performed with reference to hg19 using Bowtie; peak calling was performed using MACS; a self-programmed software was used to detect p53 target genes. A total of 50 p53 target genes were predicted. Among them, eight (CDKN1A, BBC3, BAX, DDB2, MDM2, CCNG1,XPC and PCNA) were enriched in p53 signaling transduction pathway and nucleotide excision repairing pathways respectively. A protein-protein interaction network consisting of 19 target genes was obtained;PCNA, MDM2, REV3L, CDKN1A and BAX were the top five genes with the highest degrees of connection. The methods recruited to investigate the molecular mechanism underlying p53-mediated tumor suppression in p53-WT MCF-7 breast cancer cells based on ChIP-seq data are proven feasible and reliable.%采用生物信息学方法分析野生型p53乳腺癌MCF7细胞的ChIP-seq(染色质免疫共沉淀-测序)数据,以揭示p53的抑癌分子机制。从NCBI下载的编号为GSE47041的ChIP-seq数据来源于三组试验,分别为:未经处理的乳腺癌MCF7细胞对照( NS_input),Nutlin-3a(一种MDM2拮抗剂)处理的MCF7细胞对照( S_input)和Nutlin-3a刺激MCF7细胞后加入p53抗体的实验组( S_p53)。 ChIP 获得的DNA数据的测序平台为Illumina HiSeq 2000。利用Bowtie参照人基因组hg19进行序列比对;利用MACS进行峰信号检测,并利用自定义软件筛选p53可能的靶基因;利用DAVID在线工具对靶基因进行通路富

  13. Δ122p53, a mouse model of Δ133p53α, enhances the tumor-suppressor activities of an attenuated p53 mutant

    OpenAIRE

    Slatter, T L; Hung, N. Van; Bowie, S; Campbell, H.; Rubio, C; Speidel, D; Wilson, M.; Baird, M.; Royds, J. A.; Braithwaite, A W

    2015-01-01

    Growing evidence suggests the Δ133p53α isoform may function as an oncogene. It is overexpressed in many tumors, stimulates pathways involved in tumor progression, and inhibits some activities of wild-type p53, including transactivation and apoptosis. We hypothesized that Δ133p53α would have an even more profound effect on p53 variants with weaker tumor-suppressor capability. We tested this using a mouse model heterozygous for a Δ133p53α-like isoform (Δ122p53) and a p53 mutant with weak tumor-...

  14. Aging-Associated Truncated Form of p53 Interacts with Wild-Type p53 and Alters p53 Stability, Localization, and Activity

    OpenAIRE

    Moore, Lynette; Lu, Xiongbin; Ghebranious, Nader; Tyner, Stuart; Donehower, Lawrence A.

    2007-01-01

    Evidence has accumulated that p53, a prototypical tumor suppressor, may also influence aspects of organismal aging. We have previously described a p53 mutant mouse model, the p53+/m mouse, which is cancer resistant yet exhibits reduced longevity and premature aging phenotypes. p53+/m mice express one full length p53 allele and one truncated p53 allele that is translated into a C-terminal fragment of p53 termed the M protein. The augmented cancer resistance and premature aging phenotypes in th...

  15. p53 Gene and Tumorigenesis%p53基因与肿瘤形成

    Institute of Scientific and Technical Information of China (English)

    韩涛; 杨德吉

    2008-01-01

    肿瘤抑制基因的研究已经成为继癌基因之后肿瘤遗传学、分子生物学领域的前沿和热点,尤其是抑癌基因p53越来越被人们重视.研究表明正常的p53,又称野生型p53,在细胞损伤后的修复过程中发挥重要作用.正常p53的功能像"分子警察"一样监视着基因组DNA的完整性.在细胞发生DNA损伤时,p53蛋白能使细胞分裂终止在G1/S期,以使细胞有足够的时间修复损伤,恢复正常状态.若不能修复,野生型p53还能启动细胞的凋亡过程从而引发细胞的程序性死亡,阻止具有癌变倾向的突变细胞产生.而突变型p53基因会导致肿瘤的发生,大多数肿瘤与p53的突变有关.文章着重阐述了p53的表达与突变、p53的稳定调节及p53的转录调控等.

  16. Acquisition of p53 mutations in response to the non-genotoxic p53 activator Nutlin-3

    OpenAIRE

    Aziz, Moammir H.; Shen, Hong; Carl G Maki

    2011-01-01

    Wild-type p53 is a stress-responsive tumor suppressor and potent growth inhibitor. Genotoxic stresses (e.g. ionizing and UV radiation or chemotherapeutic drug treatment) can activate p53, but also induce mutations in the P53 gene and thus select for p53-mutated cells. Nutlin-3a (Nutlin) is pre-clinical drug that activates p53 in a non-genotoxic fashion. Nutlin occupies the p53-binding pocket of MDM2, activating p53 by blocking the p53-MDM2 interaction. Because Nutlin neither binds p53 directl...

  17. Human Monocyte-derived Dendritic Cells Pulsed with Wild-field name="type" p53 Protein Efficiently Induce Cytotoxic T-lymphocytes against p53 overexpressing Human Cancer Cells

    OpenAIRE

    德永, 尚之

    2005-01-01

    PURPOSE: Dendritic cells are the most potent antigen-presenting cells for initiating cellular immune responses. Dendritic cells are attractive immunoregulatory cells for cancer immunotherapy, and their efficacy has been investigated in clinical trials. The tumor suppressor gene p53 is pivotal in the regulation of apoptosis, and p53-based immunization is an attractive approach to cancer immunotherapy because of the accumulation of p53 protein in malignant but not in normal cells. It has been s...

  18. Anal cancer in Chinese: human papillomavirus infection and altered expression of p53

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    AIM To detect the presence of HPV DNA and study the alteration of p53 expression in anal cancers in Chinese.METHODS HPV DNA was amplified by PCR. The amplified HPV DNA was classified by DBH. HPV antigen and p53 expression were respectively detected by immunohistochemistry.RESULTS HPV DNA was amplified only in one case of squamous cell carcinoma of the 72 Chinese anal cancers and further classified as HPV type 16. Others were all HPV negative. HPV antigen and p53 expression were also detected in this case. Positive stainings with anti-p53 antibody were seen in 61.2% anal cancers. There were no statistically significant differences between anal squamous cell carcinomas and adenocarcinomas and between anal adenocarcinomas and rectal adenocarcinomas. p53 protein expression was observed in the basal cells of squamous epithelium of condyloma acuminatum and morphologically normal squamous epithelium in 2 cases invaded by anal adenocarcinoma.CONCLUSION HPV infection was not associated with these cases of anal cancer. p53 alteration was a common event. Positive p53 immunostaining can not be regarded as a marker for differentiating benign from malignant lesions.

  19. Regulation of p53 tetramerization and nuclear export by ARC

    OpenAIRE

    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.

    2007-01-01

    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 reloca...

  20. Mutant p53: Multiple Mechanisms Define Biologic Activity in Cancer

    OpenAIRE

    Kim, Michael Paul; Zhang, Yun; Lozano, Guillermina

    2015-01-01

    The functional importance of p53 as a tumor suppressor gene is evident through its pervasiveness in cancer biology. The p53 gene is the most commonly altered gene in human cancer; however, not all genetic alterations are biologically equivalent. The majority of alterations involve p53 missense mutations that result in the production of mutant p53 proteins. Such mutant p53 proteins lack normal p53 function and may concomitantly gain novel functions, often with deleterious effects. Here, we rev...

  1. Autoantibody recognition mechanisms of p53 epitopes

    Science.gov (United States)

    Phillips, J. C.

    2016-06-01

    There is an urgent need for economical blood based, noninvasive molecular biomarkers to assist in the detection and diagnosis of cancers in a cost-effective manner at an early stage, when curative interventions are still possible. Serum autoantibodies are attractive biomarkers for early cancer detection, but their development has been hindered by the punctuated genetic nature of the ten million known cancer mutations. A landmark study of 50,000 patients (Pedersen et al., 2013) showed that a few p53 15-mer epitopes are much more sensitive colon cancer biomarkers than p53, which in turn is a more sensitive cancer biomarker than any other protein. The function of p53 as a nearly universal "tumor suppressor" is well established, because of its strong immunogenicity in terms of not only antibody recruitment, but also stimulation of autoantibodies. Here we examine dimensionally compressed bioinformatic fractal scaling analysis for identifying the few sensitive epitopes from the p53 amino acid sequence, and show how it could be used for early cancer detection (ECD). We trim 15-mers to 7-mers, and identify specific 7-mers from other species that could be more sensitive to aggressive human cancers, such as liver cancer. Our results could provide a roadmap for ECD.

  2. Molecular mechanisms of growth suppression by pharmacologically activated p53

    OpenAIRE

    Hedström, Elisabeth

    2009-01-01

    The tumor suppressor p53 is a transcription factor that is crucial for protecting cells from cancer development. The importance of p53 tumor suppression function is highlighted by the fact that the p53 pathway is inactivated in most, if not all cancers. Mutation of the p53 gene occurs in about 50% of all tumors, whereas in the tumors which retain wild-type p53, the function of p53 is abolished due to deregulation of the p53 pathway. Due to the potency of p53 in suppressing t...

  3. Structure of p15PAF-PCNA complex and implications for clamp sliding during DNA replication and repair

    DEFF Research Database (Denmark)

    De Biasio, Alfredo; de Opakua, Alain Ibáñez; Mortuza, Gulnahar B;

    2015-01-01

    The intrinsically disordered protein p15(PAF) regulates DNA replication and repair by binding to the proliferating cell nuclear antigen (PCNA) sliding clamp. We present the structure of the human p15(PAF)-PCNA complex. Crystallography and NMR show the central PCNA-interacting protein motif (PIP...

  4. The p53 Isoform Δ133p53β Promotes Cancer Stem Cell Potential

    Directory of Open Access Journals (Sweden)

    Nikola Arsic

    2015-04-01

    Full Text Available Cancer stem cells (CSC are responsible for cancer chemoresistance and metastasis formation. Here we report that Δ133p53β, a TP53 splice variant, enhanced cancer cell stemness in MCF-7 breast cancer cells, while its depletion reduced it. Δ133p53β stimulated the expression of the key pluripotency factors SOX2, OCT3/4, and NANOG. Similarly, in highly metastatic breast cancer cells, aggressiveness was coupled with enhanced CSC potential and Δ133p53β expression. Like in MCF-7 cells, SOX2, OCT3/4, and NANOG expression were positively regulated by Δ133p53β in these cells. Finally, treatment of MCF-7 cells with etoposide, a cytotoxic anti-cancer drug, increased CSC formation and SOX2, OCT3/4, and NANOG expression via Δ133p53, thus potentially increasing the risk of cancer recurrence. Our findings show that Δ133p53β supports CSC potential. Moreover, they indicate that the TP53 gene, which is considered a major tumor suppressor gene, also acts as an oncogene via the Δ133p53β isoform.

  5. Mutant p53: multiple mechanisms define biologic activity in cancer

    Directory of Open Access Journals (Sweden)

    Michael Paul Kim

    2015-11-01

    Full Text Available The functional importance of p53 as a tumor suppressor gene is evident through its pervasiveness in cancer biology. The p53 gene is the most commonly altered gene in human cancer; however, not all genetic alterations are biologically equivalent. The majority of p53 alterations involve missense mutations that result in the production of mutant p53 proteins. Such mutant p53 proteins lack normal p53 function and may acquire novel functions, often with deleterious effects. Here, we review characterized mechanisms of mutant p53 gain of function in multiple model systems. In addition, we review mutant p53 addiction as emerging evidence suggests that tumors may depend on sustained mutant p53 activity for continued growth. We also discuss the role of p53 in stromal elements and their contribution to tumor initiation and progression. Lastly, current genetic mouse models of mutant p53 are reviewed and their limitations discussed.

  6. Phosphorylation of Thr18 and Ser20 of p53 in Ad-p53 – induced apoptosis

    OpenAIRE

    Nakamizo, Akira; Amano, Toshiyuko; Zhang, Wei; Zhang, Xin-qiao; Ramdas, Latha; Liu, Ta-Jen; Bekele, B. Nebiyou; Shono, Tadahisa; Sasaki, Tomio; Benedict, William F.; Sawaya, Raymond; Lang, Frederick F.

    2008-01-01

    The p53 protein plays a critical role in inducing cell cycle arrest or apoptosis. Because p53 is inactivated in human gliomas, restoring p53 function is a major focus of glioma therapy. The most clinically tested strategy for replacing p53 has been adenoviral-mediated p53 gene therapy (Ad-p53). In addition to their therapeutic implications, investigations into Ad-p53 provide model systems for understanding p53’s ability to induce cell cycle arrest versus apoptosis, particularly because wild-t...

  7. Comparison of Nuclear Accumulation of p53 Protein with Mutations in the p53 Gene of Human Breast Cancer Tissues

    Institute of Scientific and Technical Information of China (English)

    王萱仪; 查小明; 武正炎; 范萍

    2001-01-01

    Objective The objective was to compare nuclear accumulation of p53 protein with mutations in the p53 gene on the tissues of human breast cancer. Methods Fifty-four invasive ductal carcinomas of breast were analyzed by the method of polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) silver stain and strep-avidin-biotin-peroxidase complex (SABC) immunohistochemistry. Results A statistically significant association between the presence of p53 gene mutation and nuclear accumulation of p53 protein was found (P<0.01). 22 tumors that demonstrated p53 gene mutations showed nuclear accumulation of p53 protein, while only 9 (28%) showed nuclear accumulation of p53 protein in 32 tumors without p53 gene mutations. Both p53 mutation protein and p53 gene mutations were prevalent in steroid and progesterone receptors negative tumors (P<0.05). A statistically significant association was found between the nuclear accumulation of p53 protein and lymph node invasion (P<0.05), and between p53 gene mutations and lymph node invasion (P<0.05). p53 abnormalities might be associated with an aggressive phenotype in breast cancer. Conclusion The immunohistochemical detection of nuclear p53 protein accumulation is highly associated with p53 gene mutations in breast cancer tissues, and that this method is useful for rapid screening of p53 abnormalities. However, in order to avoid false positive reaction, the p53 gene mutations should be determined in cases slightly positive for p53 nuclear protein.

  8. 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.

  9. Effects of Δ40p53, an isoform of p53 lacking the N-terminus, on transactivation capacity of the tumor suppressor protein p53

    OpenAIRE

    Hafsi, Hind; Santos-Silva, Daniela; Courtois-Cox, Stéphanie; Hainaut, Pierre

    2013-01-01

    Background The p53 protein is expressed as multiple isoforms that differ in their N- and C-terminus due to alternative splicing, promoter or codon initiation usage. Δ40p53 lacks the first 39 residues containing the main transcriptional activation domain, resulting from initiation of translation at AUG +40 in fully spliced p53 mRNA or in a specific variant mRNA retaining intron 2. Overexpression of Δ40p53 antagonizes wild-type p53 in vitro. However, animal models of Δ40p53 in mouse or Zebrafis...

  10. INGN 201: Ad-p53, Ad5CMV-p53, adenoviral p53, p53 gene therapy--introgen, RPR/INGN 201.

    Science.gov (United States)

    2007-01-01

    Introgen and its wholly owned European subsidiary Gendux AB are developing an adenoviral p53 gene therapy as a treatment for cancer in the US and Europe, respectively. Phase III trials in patients with head and neck cancer are ongoing, and a number of clinical trials in other cancer indications have been completed. INGN 201 is being reviewed by the EMEA for approval in Li-Fraumeni syndrome (LFS) under the provisions of exceptional circumstance; the therapy is available on a compassionate use basis to eligible LFS cancer patients under a protocol authorised by the US FDA. The p53 tumour suppressor gene is deleted or mutated in many tumour cells and is one of the most frequently mutated genes in human tumours. The p53 protein is one of the most intricate elements in the apoptotic signalling cascade, and a mutation in the gene encoding it is believed to result in a decreased ability of a cell to apoptose. Thus replacing this gene via adenovirally-mediated p53 gene therapy is hoped to result in increased apoptosis where it is administered.INGN 201 is available for licensing, although Introgen favours retaining partial or full rights to the therapy in the US. Introgen entered into a license agreement with The University of Texas System and MD Anderson Cancer Center in 1994. The technologies licenced include p53 and fus1 (INGN 401). The collaboration has yielded exclusive patent and licensing rights to numerous technologies. Introgen entered into a collaboration with Rhône-Poulenc Rorer Pharmaceuticals (now sanofi-aventis) to develop therapeutics based on p53 inhibition in October 1994. However, in June 2001 this relationship was restructured and Introgen assumed responsibility for the worldwide development of all p53 products including INGN 201, and acquired all marketing and commercialisation rights with respect to those products. Introgen initiated two phase III trials in head and neck cancer (in June 2000 and May 2001) at about 80 sites in the US, Canada and Europe

  11. Dynamics of plant DNA replication based on PCNA visualization.

    Science.gov (United States)

    Yokoyama, Ryohei; Hirakawa, Takeshi; Hayashi, Seri; Sakamoto, Takuya; Matsunaga, Sachihiro

    2016-01-01

    DNA replication is an essential process for the copying of genomic information in living organisms. Imaging of DNA replication in tissues and organs is mainly performed using fixed cells after incorporation of thymidine analogs. To establish a useful marker line to measure the duration of DNA replication and analyze the dynamics of DNA replication, we focused on the proliferating cell nuclear antigen (PCNA), which functions as a DNA sliding clamp for replicative DNA polymerases and is an essential component of replisomes. In this study we produced an Arabidopsis thaliana line expressing PCNA1 fused with the green fluorescent protein under the control of its own promoter (pAtPCNA1::AtPCNA1-EGFP). The duration of the S phase measured using the expression line was consistent with that measured after incorporation of a thymidine analog. Live cell imaging revealed that three distinct nuclear localization patterns (whole, dotted, and speckled) were sequentially observable. These whole, dotted, and speckled patterns of subnuclear AtPCNA1 signals were indicative of the G1 or G2 phase, early S phase and late S phase, respectively. The results indicate that the pAtPCNA1::AtPCNA1-EGFP line is a useful marker line for visualization of S-phase progression in live plant organs. PMID:27417498

  12. Role of p53 in Cell Death and Human Cancers

    OpenAIRE

    Toshinori Ozaki; Akira Nakagawara

    2011-01-01

    p53 is a nuclear transcription factor with a pro-apoptotic function. Since over 50% of human cancers carry loss of function mutations in p53 gene, p53 has been considered to be one of the classical type tumor suppressors. Mutant p53 acts as the dominant-negative inhibitor toward wild-type p53. Indeed, mutant p53 has an oncogenic potential. In some cases, malignant cancer cells bearing p53 mutations display a chemo-resistant phenotype. In response to a variety of cellular stresses such as DNA ...

  13. Prognostic implications of p53 protein, epidermal growth factor receptor, and Ki-67 labelling in brain tumours.

    OpenAIRE

    Jaros, E.; Perry, R H; Adam, L.; Kelly, P J; Crawford, P. J.; Kalbag, R M; Mendelow, A D; Sengupta, R P; Pearson, A D

    1992-01-01

    The expression of p53 protein, epidermal growth factor receptor (EGFR), and Ki-67 nuclear antigen was examined by immunohistochemistry in biopsies of 16 types of human brain tumours, including 43 astrocytomas. P53 protein, almost certainly its mutant form, was expressed in seven of the 16, and EGFR in 11 of the 16 types of tumours. In astrocytomas both the proportion of tumours which expressed p53 or EGFR increased with grade of malignancy as did the mean Ki-67 labelling index (LI): p53-0% in...

  14. Targeting of p300/CREB Binding Protein Coactivators by Simian Virus 40 Is Mediated through p53

    OpenAIRE

    Borger, Darrell R.; DeCaprio, James A.

    2006-01-01

    The primary transforming functions of simian virus 40 large T antigen (SV40 LT) are conferred primarily through the binding and inactivation of p53 and the retinoblastoma family members. Normal p53 function requires an association with the CREB binding protein (CBP)/p300 coactivators, and a ternary complex containing SV40 LT, p53, and CBP/p300 has been identified previously. In this report, we have evaluated a secondary function of p53 bound to the SV40 LT complex in mediating the binding of ...

  15. P53 FUSION PROTEIN EXPRESSION IN PROKARYOTE AND PREPARATION OF MONOCLONAL ANTIBODY TO P53

    Institute of Scientific and Technical Information of China (English)

    Liu Caiyun; Shou Chengchao; Sun Sulian; ZhangLei; Zeng Li

    1998-01-01

    Objective: Conventional immunohistochemistry (IHC) is available to assess P53 mutations, and expensive imported anti-P53 monoclonal antibody has been used in China, it is necessary to study a new monoclonal antibody.Methods: The P53 DNA fragment enconding N-terminal 180 amiao acide was obtained by PCR and was cloned into PGEX-2T plasmid expressing glutathione S-transferase (GST). The P53-GST fusion protein expressed by JM109was used for immunizing BALB/C mice. We have raised one hybridoma strain secreting McAb to human P53(named M126). Results: The IHC analysis of 52paraffin-embedded sections from human breast cancer with M126 and PAB1801 (Zymed Co.) has showed that the positive immunoreactions were 25 cases (48%) and 22cases (42.3%) respectively. The staining of M126 was stronger and preferable to PAB1801. Conclusion: M126can be instead of PAB1801 for studying immunohistochemical analysis on P53 Protein.

  16. Interfacial behavior of wild type and mutant p53 proteins

    Czech Academy of Sciences Publication Activity Database

    Paleček, Emil; Havran, Luděk; Dorčák, Vlastimil; Billová, Sabina; Brázdová, Marie; Masařík, Michal; Vacek, Jan; Fojta, Miroslav

    Ein Gedi, 2005. s. 15. [2nd International Workshop on Mutant p53: The p53 Regulatory Network and Functional Consequences of p53 Mutations. 17.11.2005-21.11.2005, Ein Gedi] R&D Projects: GA AV ČR(CZ) IAA500040513 Institutional research plan: CEZ:AV0Z50040507 Keywords : electrochemistry of protein p53 * protein p53 mutants Subject RIV: BO - Biophysics

  17. Controlling the Mdm2-Mdmx-p53 Circuit

    OpenAIRE

    Waning, David L.; Lehman, Jason A.; Batuello, Christopher N.; Mayo, Lindsey D.

    2010-01-01

    The p53 tumor suppressor is a key protein in maintaining the integrity of the genome by inducing either cell cycle arrest or apoptosis following cellular stress signals. Two human family members, Mdm2 and Mdmx, are primarily responsible for inactivating p53 transcription and targeting p53 protein for ubiquitin-mediated degradation. In response to genotoxic stress, post-translational modifications to p53, Mdm2 and Mdmx stabilize and activate p53. The role that phosphorylation of these molecule...

  18. Ferroptosis: A missing puzzle piece in the p53 blueprint?

    Science.gov (United States)

    Wang, Shang-Jui; Ou, Yang; Jiang, Le; Gu, Wei

    2016-05-01

    Recent evidence indicates that canonical functions of p53 (i.e., apoptosis and growth arrest) are dispensable for p53-mediated tumor suppression. We have uncovered a novel function of p53 that contributes to tumor suppression through regulation of cystine metabolism, reactive oxygen species responses, and ferroptosis. The p53-mediated ferroptotic response via SLC7A11 denotes an extra layer of defense against tumorigenesis in conjunction with other p53 functions. PMID:27314071

  19. The p53 target Wig-1 regulates p53 mRNA stability through an AU-rich element

    DEFF Research Database (Denmark)

    Vilborg, Anna; Glahder, Jacob-Andreas Harald; Wilhelm, Margareta T;

    2009-01-01

    The p53 target gene Wig-1 encodes a double-stranded-RNA-binding zinc finger protein. We show here that Wig-1 binds to p53 mRNA and stabilizes it through an AU-rich element (ARE) in the 3' UTR of the p53 mRNA. This effect is mirrored by enhanced p53 protein levels in both unstressed cells and cells...... exposed to p53-activating stress agents. Thus, the p53 target Wig-1 is a previously undescribed ARE-regulating protein that acts as a positive feedback regulator of p53, with implications both for the steady-state levels of p53 and for the p53 stress response. Our data reveal a previously undescribed link...... between the tumor suppressor p53 and posttranscriptional gene regulation via AREs in mRNA....

  20. Cancer-derived p53 mutants suppress p53-target gene expression—potential mechanism for gain of function of mutant p53

    OpenAIRE

    Vikhanskaya, Faina; Lee, Ming Kei; Mazzoletti, Marco; Broggini, Massimo; Sabapathy, Kanaga

    2007-01-01

    Tumour-derived p53 mutants are thought to have acquired ‘gain-of-function’ properties that contribute to oncogenicity. We have tested the hypothesis that p53 mutants suppress p53-target gene expression, leading to enhanced cellular growth. Silencing of mutant p53 expression in several human cell lines was found to lead to the upregulation of wild-type p53-target genes such as p21, gadd45, PERP and PTEN. The expression of these genes was also suppressed in H1299-based isogenic cell lines expre...

  1. Retention of wild-type p53 in tumors from p53 heterozygous mice: reduction of p53 dosage can promote cancer formation.

    OpenAIRE

    Venkatachalam, S; Shi, Y P; Jones, S N; Vogel, H.; Bradley, A.; Pinkel, D; Donehower, L A

    1998-01-01

    Tumor suppressor genes are generally viewed as being recessive at the cellular level, so that mutation or loss of both tumor suppressor alleles is a prerequisite for tumor formation. The tumor suppressor gene, p53, is mutated in approximately 50% of human sporadic cancers and in an inherited cancer predisposition (Li-Fraumeni syndrome). We have analyzed the status of the wild-type p53 allele in tumors taken from p53-deficient heterozygous (p53+/-) mice. These mice inherit a single null p53 al...

  2. Effects of p53 mutants derived from lung carcinomas on the p53-responsive element (p53RE) of the MDM2 gene

    OpenAIRE

    Gorgoulis, V. G.; Zacharatos, P. V.; Manolis, E.; Ikonomopoulos, J. A.; Damalas, A.; Lamprinopoulos, C.; Rassidakis, G Z; Zoumpourlis, Vassilis; Kotsinas, A.; Rassidakis, A. N.; Halazonetis, T. D.; KITTAS, C.

    2008-01-01

    The present study represents a continuation of previous works in which we observed that lung carcinomas co-expressing MDM2 protein and p53 mutants (mt p53) exhibited more aggressive behaviour. In the above studies, we suggested a 'gain of function' mechanism of mt p53 proteins based on the fact that the MDM2 gene possesses a p53-responsive element (MDM2-p53RE). In this study, to prove our hypothesis, we selected 12 cases from a series of 51 bronchogenic carcinomas. In these 12 cases, we exami...

  3. Small-molecule modulators of p53 family signaling and antitumor effects in p53-deficient human colon tumor xenografts

    OpenAIRE

    Wang, Wenge; Kim, Seok-Hyun; El-Deiry, Wafik S

    2006-01-01

    p53 deficiency is common in almost all human tumors and contributes to an aggressive chemo- or radiotherapy-resistant phenotype, therefore providing a target for drug development. Molecular targeting to restore wild-type p53 activity has been attempted in drug development and has led to the identification of CP-31398, PRIMA1, and the Nutlins. However, strategies targeting p53-activated transcriptional responses or p53 family member expression in p53-deficient tumors have yet to be explored. H...

  4. Soft-shell clam (Mya arenaria) p53: A structural and functional comparison to human p53

    OpenAIRE

    Holbrook, Lauren A.C.; Butler, Rondi A.; Cashon, Robert E.; Van Beneden, Rebecca J.

    2008-01-01

    The tumor suppressor p53 regulates genes involved in progression through the cell cycle, DNA repair, senescence or apoptosis in response to cell stress. Dysregulation of p53 can result in uncontrolled cellular proliferation. Invertebrate homologues to human p53 (Hsp53) have been identified, including a putative p53 gene (Map53) from the soft-shell clam (Mya arenaria). Predicted sequences for human and clam p53 proteins exhibit conservation in key domains. In light of this similarity, and the ...

  5. Iron Metabolism Regulates p53 Signaling through Direct Heme-p53 Interaction and Modulation of p53 Localization, Stability, and Function

    Directory of Open Access Journals (Sweden)

    Jia Shen

    2014-04-01

    Full Text Available Iron excess is closely associated with tumorigenesis in multiple types of human cancers, with underlying mechanisms yet unclear. Recently, iron deprivation has emerged as a major strategy for chemotherapy, but it exerts tumor suppression only on select human malignancies. Here, we report that the tumor suppressor protein p53 is downregulated during iron excess. Strikingly, the iron polyporphyrin heme binds to p53 protein, interferes with p53-DNA interactions, and triggers both nuclear export and cytosolic degradation of p53. Moreover, in a tumorigenicity assay, iron deprivation suppressed wild-type p53-dependent tumor growth, suggesting that upregulation of wild-type p53 signaling underlies the selective efficacy of iron deprivation. Our findings thus identify a direct link between iron/heme homeostasis and the regulation of p53 signaling, which not only provides mechanistic insights into iron-excess-associated tumorigenesis but may also help predict and improve outcomes in iron-deprivation-based chemotherapy.

  6. Expression of Androgen Receptor Is Negatively Regulated By p53

    Directory of Open Access Journals (Sweden)

    Fatouma Alimirah

    2007-12-01

    Full Text Available Increased expression of androgen receptor (AR in prostate cancer (PC is associated with transition to androgen independence. Because the progression of PC to advanced stages is often associated with the loss of p53 function, we tested whether the p53 could regulate the expression of AR gene. Here we report that p53 negatively regulates the expression of AR in prostate epithelial cells (PrECs. We found that in LNCaP human prostate cancer cells that express the wild-type p53 and AR and in human normal PrECs, the activation of p53 by genotoxic stress or by inhibition of p53 nuclear export downregulated the expression of AR. Furthermore, forced expression of p53 in LNCaP cells decreased the expression of AR. Conversely, knockdown of p53 expression in LNCaP cells increased the AR expression. Consistent with the negative regulation of AR expression by p53, the p53-null HCT116 cells expressed higher levels of AR compared with the isogenic HCT116 cells that express the wildtype p53. Moreover, we noted that in etoposide treated LNCaP cells p53 bound to the promoter region of the AR gene, which contains a potential p53 DNA-binding consensus sequence, in chromatin immunoprecipitation assays. Together, our observations provide support for the idea that the loss of p53 function in prostate cancer cells contributes to increased expression of AR.

  7. Addition of TAT protein transduction domain and GrpE to human p53 provides soluble fusion proteins that can be transduced into dendritic cells and elicit p53-specific T-cell responses in HLA-A*0201 transgenic mice

    DEFF Research Database (Denmark)

    Justesen, S; Buus, S; Claesson, M H;

    2007-01-01

    The protein p53 has been shown to be an efficient tumour antigen in both murine and human cancer vaccine studies and cancer vaccines targeting p53 based on major histocompatibility complex (MHC) class I binding p53-derived peptides that induce cytotoxic T lymphocytes (CTLs) without p53-specific CD4......(+) T-cell help have been tested by several research groups including ours. To obtain such CD4(+) T-cell help and cover a broader repertoire of MHC haplotypes we have previously attempted to produce recombinant human p53 for vaccination purposes. However, attempts to refold a hexahis-tagged p53 protein...... in our laboratory were unsuccessful. Here, we show that fusion of an 11-amino-acid region of the human immunodeficiency virus TAT protein transduction domain (PTD) to human p53 increases the solubility of the otherwise insoluble p53 protein and this rTAT-p53 protein can be transduced into human...

  8. Analysis of p53 mutants for transcriptional activity.

    OpenAIRE

    Raycroft, L.; Schmidt, J. R.; Yoas, K; Hao, M M; Lozano, G.

    1991-01-01

    The wild-type p53 protein functions to suppress transformation, but numerous mutant p53 proteins are transformation competent. To examine the role of p53 as a transcription factor, we made fusion proteins containing human or mouse p53 sequences fused to the DNA binding domain of a known transcription factor, GAL4. Human and mouse wild-type p53/GAL4 specifically transactivated expression of a chloramphenicol acetyltransferase reporter in HeLa, CHO, and NIH 3T3 cells. Several mutant p53 protein...

  9. SCH529074, a Small Molecule Activator of Mutant p53, Which Binds p53 DNA Binding Domain (DBD), Restores Growth-suppressive Function to Mutant p53 and Interrupts HDM2-mediated Ubiquitination of Wild Type p53

    OpenAIRE

    Demma, Mark; Maxwell, Eugene; Ramos, Robert; Liang, Lianzhu; Li, Cheng; Hesk, David; Rossman, Randall; Mallams, Alan; Doll, Ronald; Liu, Ming; Seidel-Dugan, Cynthia; Bishop, W. Robert; Dasmahapatra, Bimalendu

    2010-01-01

    Abrogation of p53 function occurs in almost all human cancers, with more than 50% of cancers harboring inactivating mutations in p53 itself. Mutation of p53 is indicative of highly aggressive cancers and poor prognosis. The vast majority of mutations in p53 occur in its core DNA binding domain (DBD) and result in inactivation of p53 by reducing its thermodynamic stability at physiological temperature. Here, we report a small molecule, SCH529074, that binds specifically to the p53 DBD in a sat...

  10. Activation and activities of the p53 tumour suppressor protein

    OpenAIRE

    Bálint, É; Vousden, K H

    2001-01-01

    The p53 tumour suppressor protein inhibits malignant progression by mediating cell cycle arrest, apoptosis or repair following cellular stress. One of the major regulators of p53 function is the MDM2 protein, and multiple forms of cellular stress activate p53 by inhibiting the MDM2-mediated degradation of p53. Mutations in p53, or disruption of the pathways that allow activation of p53, seem to be a general feature of all cancers. Here we review recent advances in our understanding of the pat...

  11. P53 autoantibodies in 1006 patients followed up for breast cancer

    International Nuclear Information System (INIS)

    to p53 would reflect tumour behaviour. However, we found that the presence or absence of p53 autoantibodies was not predictive of presence or absence of recurrent disease. There was an equivalent incidence of active disease at the time of sampling in both the autoantibody-negative and autoantibody-positive groups, these being 25.2 and 28.7%, respectively. Thus, humoral immune activity against p53 appeared to be relatively restricted to a subgroup of patients in whom, once an autoantibody response had been generated, antibody was likely to persist regardless of tumour behaviour. Conversely, where no detectable p53 autoantibody was present at the time of primary diagnosis, these patients remained similarly negative for antibody, irrespective of subsequent disease activity (Table 3). In contrast to shed markers that correlate with tumour mass, such as CA15.3 for cancer of the breast, any tumour-related immune response will be subject to complex regulation. Autoantibody responses to p53 will require appropriate primary immunization; initial low-dose antigen exposure may induce immune tolerance and lack of response. Higher antigen doses may activate either antibody-mediated immunity, or cellular immunity. In breast cancer patients, our results suggest that, once an active humoral response against p53 is established, then this remains active. This persistent humoral reaction may be driven by persistent antigenic stimulation by p53 protein derived from overexpression of p53 at distant metastatic sites; alternatively, irradiated normal tissue may be a source of continued antigenic stimulation, because a long-term side effect of radiation therapy is an increased expression of p53 in normal breast tissue that persists for several years [12]. Since the great majority of our total patient cohort had received radiotherapy, humoral immunity to p53 associated with primary disease might persist, even in those patients who enter remission, due to tumour-independent antigenic

  12. 乳癌病人血清p53抗体与组织p53的比较%The relationship between serum p53Abs and tissue p53

    Institute of Scientific and Technical Information of China (English)

    郭美琴; 郭铁柱; 丰美芳

    2002-01-01

    目的比较乳癌病人血清p53抗体和组织p53表达之间的关系.方法 68例乳癌病人血清p53抗体用酶联免疫法(ELISA)检测,组织p53蛋白用免疫组织化学法检测.结果 68例乳癌病人血清p53抗体阳性19例,阳性率28%,组织p53阳性27例,阳性率40%,组织p53阳性同时血清p53抗体阳性者14例,组织p53阳性而血清p53抗体阴性者13例,组织p53阴性但血清p53抗体阳性者5例.结论组织和血清之间具有密切相关性,但非完全一致,p53抗体的检测更是一个预测乳癌复发或高危险性的指标.

  13. Expression of TP53 isoforms p53β or p53γ enhances chemosensitivity in TP53(null) cell lines.

    Science.gov (United States)

    Silden, Elisabeth; Hjelle, Sigrun M; Wergeland, Line; Sulen, André; Andresen, Vibeke; Bourdon, Jean-Christophe; Micklem, David R; McCormack, Emmet; Gjertsen, Bjørn Tore

    2013-01-01

    The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53(null) background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate with increased response to camptothecin and doxorubicin chemotherapy. Decreased DNA synthesis and clonogenicity in p53β and p53γ congenic H1299 was accompanied by increased p21((CIP1/WAF1)), Bax and Mdm2 proteins. Chemotherapy induced p53 isoform degradation, most prominent for p53γ. The proteasome inhibitor bortezomib substantially increased basal p53γ protein level, while the level of p53β protein was unaffected. Treatment with dicoumarol, a putative blocker of the proteasome-related NAD(P)H quinone oxidoreductase NQO1, effectively attenuated basal p53γ protein level in spite of bortezomib treatment. Although in vitro proliferation and clonogenicity assays indicated a weak suppressive effect by p53β and p53γ expression, studies of in vivo subcutaneous H1299 tumor growth demonstrated a significantly increased growth by expression of either p53 isoforms. This study suggests that p53β and p53γ share functionality in chemosensitizing and tumor growth enhancement but comprise distinct regulation at the protein level. PMID:23409163

  14. Expression of TP53 isoforms p53β or p53γ enhances chemosensitivity in TP53(null cell lines.

    Directory of Open Access Journals (Sweden)

    Elisabeth Silden

    Full Text Available The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53(null background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate with increased response to camptothecin and doxorubicin chemotherapy. Decreased DNA synthesis and clonogenicity in p53β and p53γ congenic H1299 was accompanied by increased p21((CIP1/WAF1, Bax and Mdm2 proteins. Chemotherapy induced p53 isoform degradation, most prominent for p53γ. The proteasome inhibitor bortezomib substantially increased basal p53γ protein level, while the level of p53β protein was unaffected. Treatment with dicoumarol, a putative blocker of the proteasome-related NAD(PH quinone oxidoreductase NQO1, effectively attenuated basal p53γ protein level in spite of bortezomib treatment. Although in vitro proliferation and clonogenicity assays indicated a weak suppressive effect by p53β and p53γ expression, studies of in vivo subcutaneous H1299 tumor growth demonstrated a significantly increased growth by expression of either p53 isoforms. This study suggests that p53β and p53γ share functionality in chemosensitizing and tumor growth enhancement but comprise distinct regulation at the protein level.

  15. Orphan Nuclear Receptor PNR/NR2E3 Stimulates p53 Functions by Enhancing p53 Acetylation

    OpenAIRE

    WEN, ZHI; Pyeon, Dohun; Wang, Yidan; Lambert, Paul; Xu, Wei; Ahlquist, Paul

    2012-01-01

    Since inactivation of tumor suppressor p53 functions is one of the most common features of human cancer cells, restoring p53 expression and activity is an important focus in cancer therapy. Here we report identification of photoreceptor-specific nuclear receptor (PNR)/NR2E3 as a positive regulator of p53 in a high-throughput genetic screen. In HeLa cells, PNR stimulated p53-responsive promoters in a p53-dependent fashion and induced apoptosis in several cell types. PNR also increased p53 prot...

  16. Expression of TP53 Isoforms p53β or p53γ Enhances Chemosensitivity in TP53null Cell Lines

    OpenAIRE

    Elisabeth Silden; Hjelle, Sigrun M; Line Wergeland; André Sulen; Vibeke Andresen; Jean-Christophe Bourdon; Micklem, David R; Emmet McCormack; Bjørn Tore Gjertsen

    2013-01-01

    The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53(null) background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate wi...

  17. Adenovirus Ad-p53AIP1-mediated gene therapy and its regulation of p53-MDM2 interactions

    OpenAIRE

    Jiang, Yunbo; Chen, Huihua; JIA, HAIQUAN; XU, YUANJI; Liu, Gang; Wang, Yan; Yang, Xiaohe; Yinglin LU

    2010-01-01

    We generated replication-defective adenovirus Ad-p53AIP1 and studied its anti-tumor efficacy both in vitro and in vivo. We demonstrated that Ad-p53AIP1 infection elicited high levels of p53AIP1 expression in cancer cells. We also found that Ad-p53AIP1 expression induced marked apoptosis and cell cycle arrest in HepG2 cells. Moreover, Ad-p53AIP1 infection significantly inhibited the tumorigenesis of 4T1 mouse mammary cancer cells in vivo. In particular, we discovered that p53AIP1 overexpressio...

  18. Quaternary structure of the specific p53–DNA complex reveals the mechanism of p53 mutant dominance

    OpenAIRE

    Aramayo, Ricardo; Sherman, Michael B.; Brownless, Kathryne; Lurz, Rudi; Okorokov, Andrei L.; Orlova, Elena V

    2011-01-01

    The p53 tumour suppressor is a transcriptional activator that controls cell fate in response to various stresses. p53 can initiate cell cycle arrest, senescence and/or apoptosis via transactivation of p53 target genes, thus preventing cancer onset. Mutations that impair p53 usually occur in the core domain and negate the p53 sequence-specific DNA binding. Moreover, these mutations exhibit a dominant negative effect on the remaining wild-type p53. Here, we report the cryo electron microscopy s...

  19. Expression of TP53 Isoforms p53β or p53γ Enhances Chemosensitivity in TP53null Cell Lines

    OpenAIRE

    Silden, Elisabeth; Hjelle, Sigrun M; Wergeland, Line; Sulen, André; Andresen, Vibeke; Bourdon, Jean-Christophe; Micklem, David R.; McCormack, Emmet; Gjertsen, Bjørn Tore

    2013-01-01

    The carboxy-terminal truncated p53 alternative spliced isoforms, p53β and p53γ, are expressed at disparate levels in cancer and are suggested to influence treatment response and therapy outcome. However, their functional role in cancer remains to be elucidated. We investigated their individual functionality in the p53null background of cell lines H1299 and SAOS-2 by stable retroviral transduction or transient transfection. Expression status of p53β and p53γ protein was found to correlate with...

  20. The Many Roles of PCNA in Eukaryotic DNA Replication.

    Science.gov (United States)

    Boehm, E M; Gildenberg, M S; Washington, M T

    2016-01-01

    Proliferating cell nuclear antigen (PCNA) plays critical roles in many aspects of DNA replication and replication-associated processes, including translesion synthesis, error-free damage bypass, break-induced replication, mismatch repair, and chromatin assembly. Since its discovery, our view of PCNA has evolved from a replication accessory factor to the hub protein in a large protein-protein interaction network that organizes and orchestrates many of the key events at the replication fork. We begin this review article with an overview of the structure and function of PCNA. We discuss the ways its many interacting partners bind and how these interactions are regulated by posttranslational modifications such as ubiquitylation and sumoylation. We then explore the many roles of PCNA in normal DNA replication and in replication-coupled DNA damage tolerance and repair processes. We conclude by considering how PCNA can interact physically with so many binding partners to carry out its numerous roles. We propose that there is a large, dynamic network of linked PCNA molecules at and around the replication fork. This network would serve to increase the local concentration of all the proteins necessary for DNA replication and replication-associated processes and to regulate their various activities. PMID:27241932

  1. Restriction of human herpesvirus 6B replication by p53

    DEFF Research Database (Denmark)

    Øster, Bodil; Kofod-Olsen, Emil; Bundgaard, Bettina;

    2008-01-01

    Human herpesvirus 6B (HHV-6B) induces significant accumulation of p53 in both the nucleus and cytoplasm during infection. Activation of p53 by DNA damage is known to induce either growth arrest or apoptosis; nevertheless, HHV-6B-infected cells are arrested in their cell cycle independently of p53......, and only a minor fraction of the infected cells undergoes apoptosis. Using pifithrin-alpha, a p53 inhibitor, and p53-null cells, this study showed that infected epithelial cells accumulated viral transcripts and proteins to a significantly higher degree in the absence of active p53. Moreover, HHV-6B......-induced cytopathic effects were greatly enhanced in the absence of p53. This suggests that, in epithelial cells, some of the functions of p53 leading to cell-cycle arrest and apoptosis are restrained by HHV-6B infection, whereas other cellular defences, causing inhibition of virus transcription, are partially...

  2. Mutations in p53, p53 protein overexpression and breast cancer survival

    Czech Academy of Sciences Publication Activity Database

    Rössner ml., Pavel; Gammon, M. D.; Zhang, Y.J.; Terry, M. B.; Hibshoosh, H.; Memeo, L.; Mansukhani, M.; Long, CH.M.; Gabrowski, G.; Agrawal, M.; Kalra, T.S.; Teitelbaum, S. L.; Neugut, A. I.; Santella, R. M.

    2009-01-01

    Roč. 13, č. 9B (2009), s. 3847-3857. ISSN 1582-1838 Institutional research plan: CEZ:AV0Z50390512 Keywords : Breast cancer * p53 mutations * Survival Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 5.228, year: 2009

  3. Targeting Oncogenic Mutant p53 for Cancer Therapy

    OpenAIRE

    Parrales, Alejandro; Iwakuma, Tomoo

    2015-01-01

    Among genetic alterations in human cancers, mutations in the tumor suppressor p53 gene are the most common, occurring in over 50% of human cancers. The majority of p53 mutations are missense mutations and result in the accumulation of dysfunctional p53 protein in tumors. These mutants frequently have oncogenic gain-of-function activities and exacerbate malignant properties of cancer cells, such as metastasis and drug resistance. Increasing evidence reveals that stabilization of mutant p53 in ...

  4. Modulation of p53's transcriptional function by small molecules

    OpenAIRE

    Nikulenkov, Fedor

    2011-01-01

    p53 tumour suppressor is a transcriptional factor which induces apoptosis or growth arrest in response to stress thus eliminating damaged cells. p53 function is frequently abrogated in tumours either via inactivation mutations in the TP53 gene or by elevated activity of p53 negative regulators HDM2 and HDMX. Therefore application of small molecules that reactivate p53 function is a promising strategy for anti-cancer therapy. In addition, small molecules can serve as valuable research tool to ...

  5. Targeting p53 and its domains for cancer gene therapy

    OpenAIRE

    Karina Julia Matissek

    2014-01-01

    The tumor suppressor p53 is one of the most frequently mutated proteins in human cancer and has been extensively targeted for cancer therapy. This resulted in wild type p53 gene therapeutic approval for the treatment of head and neck cancer in China. p53 mainly functions as a transcription factor and stimulates a variety of genes involved in the intrinsic and extrinsic apoptotic pathway by binding to p53 responsive elements as a t...

  6. G-actin guides p53 nuclear transport: potential contribution of monomeric actin in altered localization of mutant p53

    Science.gov (United States)

    Saha, Taniya; Guha, Deblina; Manna, Argha; Panda, Abir Kumar; Bhat, Jyotsna; Chatterjee, Subhrangsu; Sa, Gaurisankar

    2016-01-01

    p53 preserves genomic integrity by restricting anomaly at the gene level. Till date, limited information is available for cytosol to nuclear shuttling of p53; except microtubule-based trafficking route, which utilizes minus-end directed motor dynein. The present study suggests that monomeric actin (G-actin) guides p53 traffic towards the nucleus. Histidine-tag pull-down assay using purified p53(1–393)-His and G-actin confirms direct physical association between p53 and monomeric G-actin. Co-immunoprecipitation data supports the same. Confocal imaging explores intense perinuclear colocalization between p53 and G-actin. To address atomistic details of the complex, constraint-based docked model of p53:G-actin complex was generated based on crystal structures. MD simulation reveals that p53 DNA-binding domain arrests very well the G-actin protein. Docking benchmark studies have been carried out for a known crystal structure, 1YCS (complex between p53DBD and BP2), which validates the docking protocol we adopted. Co-immunoprecipitation study using “hot-spot” p53 mutants suggested reduced G-actin association with cancer-associated p53 conformational mutants (R175H and R249S). Considering these findings, we hypothesized that point mutation in p53 structure, which diminishes p53:G-actin complexation results in mutant p53 altered subcellular localization. Our model suggests p53Arg249 form polar-contact with Arg357 of G-actin, which upon mutation, destabilizes p53:G-actin interaction and results in cytoplasmic retention of p53R249S. PMID:27601274

  7. G-actin guides p53 nuclear transport: potential contribution of monomeric actin in altered localization of mutant p53.

    Science.gov (United States)

    Saha, Taniya; Guha, Deblina; Manna, Argha; Panda, Abir Kumar; Bhat, Jyotsna; Chatterjee, Subhrangsu; Sa, Gaurisankar

    2016-01-01

    p53 preserves genomic integrity by restricting anomaly at the gene level. Till date, limited information is available for cytosol to nuclear shuttling of p53; except microtubule-based trafficking route, which utilizes minus-end directed motor dynein. The present study suggests that monomeric actin (G-actin) guides p53 traffic towards the nucleus. Histidine-tag pull-down assay using purified p53(1-393)-His and G-actin confirms direct physical association between p53 and monomeric G-actin. Co-immunoprecipitation data supports the same. Confocal imaging explores intense perinuclear colocalization between p53 and G-actin. To address atomistic details of the complex, constraint-based docked model of p53:G-actin complex was generated based on crystal structures. MD simulation reveals that p53 DNA-binding domain arrests very well the G-actin protein. Docking benchmark studies have been carried out for a known crystal structure, 1YCS (complex between p53DBD and BP2), which validates the docking protocol we adopted. Co-immunoprecipitation study using "hot-spot" p53 mutants suggested reduced G-actin association with cancer-associated p53 conformational mutants (R175H and R249S). Considering these findings, we hypothesized that point mutation in p53 structure, which diminishes p53:G-actin complexation results in mutant p53 altered subcellular localization. Our model suggests p53Arg249 form polar-contact with Arg357 of G-actin, which upon mutation, destabilizes p53:G-actin interaction and results in cytoplasmic retention of p53R249S. PMID:27601274

  8. Gene expression profiles after ionizing radiation in three closely related human lymphoblastoid cell lines with different p53 status

    International Nuclear Information System (INIS)

    Full text: The p53 protein has been implicated in multiple cellular responses related to DNA damage, including apoptosis, cell cycle control, as well as DNA replication, transcription, and repair. Alterations in any of these processes could be related to increased genomic instability. Our previous study indicated that the lack of wild-type p53 does not lead to increased mutability. To investigate further how p53 is involved in regulating mutational processes, we used 8K cDNA microarrays to compare the patterns of gene expression among three closely related human cell lines with different p53 status including TK6 (wild-type p53), NH32 (p53-null), and WTK1 (mutant p53). Total RNA samples were collected at different time points (1, 3, 6, 9, and 24h) after 10Gy gamma-radiation. After template-based clustering analysis of the gene expression over the time course, our preliminary results showed that 464 genes are either up- or down-regulated by 2 fold following 10Gy radiation treatment. In addition, cluster analyses of gene expression profiles among these three cell lines revealed distinct patterns. In TK6, 175 genes were being up-regulated, while 36 genes showed down-regulation. In contrast, WTK1 showed 75 genes being up-regulated and 12 genes being down-regulated. In NH32, only 54 genes showed up-regulation. Furthermore, we found several genes associated with DNA repair such as DDB2, p53R2, XPC, PCNA, BTG2 and MSH2 were highly induced in TK6 compared to WTK1 and NH32. These TK6 up-regulated genes were confirmed by using real-time RT-PCR and are being further investigated at the protein level by Western blots

  9. P53 MUTATIONS IN HUMAN LUNG-TUMORS

    NARCIS (Netherlands)

    MILLER, CW; ASLO, A; KOK, K; YOKOTA, J; BUYS, CHCM; TERADA, M; KOEFFLER, HP; Simon, K.

    1992-01-01

    Mutation of one p53 allele and loss of the normal p53 allele [loss of heterozygosity (LOH)] occur in many tumors including lung cancers. These alterations apparently contribute to development of cancer by interfering with the tumor suppressor activity of p53. We directly sequenced amplified DNA in t

  10. p53 specific (auto)immunity in mice

    NARCIS (Netherlands)

    Lauwen, Marjolein Monique

    2008-01-01

    Self-tolerance to p53 is a major potential limitation for the activation of the endogenous T-cell repertoire. So far, p53 specific CD8+ and CD4+ T-cell immunity has been described in cancer patients and healthy individuals. However, the restrictions of tolerance on the recruitment of p53 specific T

  11. Mutual interactions between P53 and growth factors in cancer

    NARCIS (Netherlands)

    Asschert, JGW; Vellenga, E; De Jong, S; De Vries, EGE

    1998-01-01

    The function of p53 armour suppressor protein is determined by various intrinsic properties of the protein. The effect of p53 DNA-binding, and platein-protein interactions are determined by the conformation of the protein. Thus p53 fulfils its role in cell cycle control and the onset of apoptotic ce

  12. Identification of p53-target genes in Danio rerio

    Science.gov (United States)

    Mandriani, Barbara; Castellana, Stefano; Rinaldi, Carmela; Manzoni, Marta; Venuto, Santina; Rodriguez-Aznar, Eva; Galceran, Juan; Nieto, M. Angela; Borsani, Giuseppe; Monti, Eugenio; Mazza, Tommaso; Merla, Giuseppe; Micale, Lucia

    2016-01-01

    To orchestrate the genomic response to cellular stress signals, p53 recognizes and binds to DNA containing specific and well-characterized p53-responsive elements (REs). Differences in RE sequences can strongly affect the p53 transactivation capacity and occur even between closely related species. Therefore, the identification and characterization of a species-specific p53 Binding sistes (BS) consensus sequence and of the associated target genes may help to provide new insights into the evolution of the p53 regulatory networks across different species. Although p53 functions were studied in a wide range of species, little is known about the p53-mediated transcriptional signature in Danio rerio. Here, we designed and biochemically validated a computational approach to identify novel p53 target genes in Danio rerio genome. Screening all the Danio rerio genome by pattern-matching-based analysis, we found p53 RE-like patterns proximal to 979 annotated Danio rerio genes. Prioritization analysis identified a subset of 134 candidate pattern-related genes, 31 of which have been investigated in further biochemical assays. Our study identified runx1, axin1, traf4a, hspa8, col4a5, necab2, and dnajc9 genes as novel direct p53 targets and 12 additional p53-controlled genes in Danio rerio genome. The proposed combinatorial approach resulted to be highly sensitive and robust for identifying new p53 target genes also in additional animal species. PMID:27581768

  13. Role of p53 in Cell Death and Human Cancers

    International Nuclear Information System (INIS)

    p53 is a nuclear transcription factor with a pro-apoptotic function. Since over 50% of human cancers carry loss of function mutations in p53 gene, p53 has been considered to be one of the classical type tumor suppressors. Mutant p53 acts as the dominant-negative inhibitor toward wild-type p53. Indeed, mutant p53 has an oncogenic potential. In some cases, malignant cancer cells bearing p53 mutations display a chemo-resistant phenotype. In response to a variety of cellular stresses such as DNA damage, p53 is induced to accumulate in cell nucleus to exert its pro-apoptotic function. Activated p53 promotes cell cycle arrest to allow DNA repair and/or apoptosis to prevent the propagation of cells with serious DNA damage through the transactivation of its target genes implicated in the induction of cell cycle arrest and/or apoptosis. Thus, the DNA-binding activity of p53 is tightly linked to its tumor suppressive function. In the present review article, we describe the regulatory mechanisms of p53 and also p53-mediated therapeutic strategies to cure malignant cancers

  14. Overexpression of DRAM enhances p53-dependent apoptosis

    International Nuclear Information System (INIS)

    Tumor suppressor p53-dependent apoptosis is thought to be one of the most important tumor-suppressive mechanisms in human tumorigenesis. Till date, “super p53” mutants exhibiting more potent ability to induce apoptosis than wild-type p53 have been reported. These super p53s may provide a clue for development of novel therapeutic targets. However, the major mechanism underlying the super p53-dependent apoptosis remains unclear. To identify critical gene(s) in this mechanism, we performed a comprehensive and comparative expression analysis in p53-null Saos-2 cells with conditional expression of wild-type p53 and S121F, which was previously reported as a super p53 mutant. We identified damage-regulated autophagy modulator (DRAM) as one of the genes that were more upregulated by S121F than wild-type p53. Although knockdown of DRAM was not sufficient for reducing the ability of S121F to induce apoptosis, DRAM overexpression enhanced the ability in a wild-type p53-dependent manner. Here, we show that DRAM is an important gene for the enhancement of p53-dependent apoptosis. Additional analysis of the mechanism of super p53-dependent apoptosis may lead to the identification of novel drug targets for cancer therapy

  15. p53 mutations increase resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Mouse and human tumors of diverse origin frequently have somatically acquired mutations or rearrangements of the p53 gene, or they have lost one or both copies of the gene. Although wild-type p53 protein is believed to function as a tumor-suppressor gene, it is as yet unclear how p53 mutations lead to neoplastic development. Wild-type p53 has been postulated to play a role in DNA repair, suggesting that expression of mutant forms of p53 might alter cellular resistance to the DNA damage caused by γ radiation. Moreover, p53 is thought to function as a cell cycle checkpoint after irradiation, also suggesting that mutant p53 might change the cellular proliferative response to radiation. The authors have used transgenic mice expressing one of two mutant alleles of p53 to test this prediction. Their results show that expression of both mutant variants of the mouse p53 gene significantly increases the cellular resistance of a variety of hematopoietic cell lineages to γ radiation. These observations provide direct evidence that p53 mutations affect the cellular response to DNA damage, either by increasing DNA repair processes or, possibly, by increasing cellular tolerance to DNA damage. The association of p53 mutations with increased radioresistance suggests possible mechanisms through which alterations in the p53 gene might lead to oncogenic transformation. 53 refs., 5 figs

  16. Identification of p53-target genes in Danio rerio.

    Science.gov (United States)

    Mandriani, Barbara; Castellana, Stefano; Rinaldi, Carmela; Manzoni, Marta; Venuto, Santina; Rodriguez-Aznar, Eva; Galceran, Juan; Nieto, M Angela; Borsani, Giuseppe; Monti, Eugenio; Mazza, Tommaso; Merla, Giuseppe; Micale, Lucia

    2016-01-01

    To orchestrate the genomic response to cellular stress signals, p53 recognizes and binds to DNA containing specific and well-characterized p53-responsive elements (REs). Differences in RE sequences can strongly affect the p53 transactivation capacity and occur even between closely related species. Therefore, the identification and characterization of a species-specific p53 Binding sistes (BS) consensus sequence and of the associated target genes may help to provide new insights into the evolution of the p53 regulatory networks across different species. Although p53 functions were studied in a wide range of species, little is known about the p53-mediated transcriptional signature in Danio rerio. Here, we designed and biochemically validated a computational approach to identify novel p53 target genes in Danio rerio genome. Screening all the Danio rerio genome by pattern-matching-based analysis, we found p53 RE-like patterns proximal to 979 annotated Danio rerio genes. Prioritization analysis identified a subset of 134 candidate pattern-related genes, 31 of which have been investigated in further biochemical assays. Our study identified runx1, axin1, traf4a, hspa8, col4a5, necab2, and dnajc9 genes as novel direct p53 targets and 12 additional p53-controlled genes in Danio rerio genome. The proposed combinatorial approach resulted to be highly sensitive and robust for identifying new p53 target genes also in additional animal species. PMID:27581768

  17. Orderly progression through S-phase requires dynamic ubiquitylation and deubiquitylation of PCNA.

    Science.gov (United States)

    Álvarez, Vanesa; Viñas, Laura; Gallego-Sánchez, Alfonso; Andrés, Sonia; Sacristán, María P; Bueno, Avelino

    2016-01-01

    Proliferating-cell nuclear antigen (PCNA) is a DNA sliding clamp with an essential function in DNA replication and a key role in tolerance to DNA damage by ensuring the bypass of lesions. In eukaryotes, DNA damage tolerance is regulated by ubiquitylation of lysine 164 of PCNA through a well-known control mechanism; however, the regulation of PCNA deubiquitylation remains poorly understood. Our work is a systematic and functional study on PCNA deubiquitylating enzymes (DUBs) in Schizosaccharomyces pombe. Our study reveals that the deubiquitylation of PCNA in fission yeast cells is a complex process that requires several ubiquitin proteases dedicated to the deubiquitylation of a specific subnuclear fraction of mono- and di-ubiquitylated PCNA or a particular type of poly-ubiquitylated PCNA and that there is little redundancy among these enzymes. To understand how DUB activity regulates the oscillatory pattern of ubiquitylated PCNA in fission yeast, we assembled multiple DUB mutants and found that a quadruple mutation of ubp2(+), ubp12(+), ubp15(+), and ubp16(+) leads to the stable accumulation of mono-, di-, and poly-ubiquitylated forms of PCNA, increases S-phase duration, and sensitizes cells to DNA damage. Our data suggest that the dynamic ubiquitylation and deubiquitylation of PCNA occurs during S-phase to ensure processive DNA replication. PMID:27151298

  18. Targeting of p300/CREB binding protein coactivators by simian virus 40 is mediated through p53.

    Science.gov (United States)

    Borger, Darrell R; DeCaprio, James A

    2006-05-01

    The primary transforming functions of simian virus 40 large T antigen (SV40 LT) are conferred primarily through the binding and inactivation of p53 and the retinoblastoma family members. Normal p53 function requires an association with the CREB binding protein (CBP)/p300 coactivators, and a ternary complex containing SV40 LT, p53, and CBP/p300 has been identified previously. In this report, we have evaluated a secondary function of p53 bound to the SV40 LT complex in mediating the binding of human CBP/p300. We demonstrate that p53 associated with SV40 LT was posttranslationally modified in a manner consistent with the binding of CBP/p300. Furthermore, expression of SV40 LT induced the proportion of p53 phosphorylated on S15. An essential function for p53 in bridging the interaction between SV40 LT and CBP/p300 was identified through the reconstitution of the SV40 LT-CBP/p300 complex upon p53 reexpression in p53-null cells. In addition, the SV40 LT-CBP/p300 complex was disrupted through RNA interference-mediated depletion of endogenous p53. We also demonstrate that SV40 LT was acetylated in a p300- and p53-dependent manner, at least in part through the CH3 domain of p300. Therefore, the binding of p53 serves to modify SV40 LT by targeting CBP and p300 binding to direct the acetylation of SV40 LT. PMID:16611888

  19. Resistance of mitochondrial p53 to dominant inhibition

    Directory of Open Access Journals (Sweden)

    Mestres Pedro

    2008-06-01

    Full Text Available Abstract Background Mutation of a tumor suppressor allele leaves the second as backup. Not necessarily so with p53. This homo-tetrameric transcription factor can become contaminated with mutant p53 through hetero-tetramerization. In addition, it can be out-competed by the binding to p53 DNA recognition motifs of transactivation-incompetent isoforms (ΔN and ΔTA-isoforms of the p53/p63/p73 family of proteins. Countermeasures against such dominant-negative or dominant-inhibitory action might include the evolutionary gain of novel, transactivation-independent tumor suppressor functions by the wild-type monomer. Results Here we have studied, mostly in human HCT116 colon adenocarcinoma cells with an intact p53 pathway, the effects of dominant-inhibitory p53 mutants and of Δex2/3p73, a tumor-associated ΔTA-competitor of wild-type p53, on the nuclear transactivation-dependent and extra-nuclear transactivation-independent functions of wild-type p53. We report that mutant p53 and Δex2/3p73, expressed from a single gene copy per cell, interfere with the stress-induced expression of p53-responsive genes but leave the extra-nuclear apoptosis by mitochondrial p53 largely unaffected, although both wild-type and mutant p53 associate with the mitochondria. In accord with these observations, we present evidence that in contrast to nuclear p53 the vast majority of mitochondrial p53, be it wild-type or mutant, is consisting of monomeric protein. Conclusion The extra-nuclear p53-dependent apoptosis may constitute a fail-safe mechanism against dominant inhibition.

  20. Cellular adaptation to hypoxia and p53 transcription regulation

    Institute of Scientific and Technical Information of China (English)

    Yang ZHAO; Xue-qun CHEN; Ji-zeng DU

    2009-01-01

    Tumor suppressor p53 is the most frequently mutated gene in human tumors. Meanwhile, under stress conditions, p53 also acts as a transcription factor, regulating the expression of a series of target genes to maintain the integrity of genome. The target genes of p53 can be classified into genes regulating cell cycle arrest, genes involved in apoptosis, and genes inhibiting angiogenesis. p53 protein contains a transactivation domain, a sequence-specific DNA binding domain, a tetramerization domain, a non-specific DNA binding domain that recognizes damaged DNA, and a later identified proline-rich domain. Under stress, p53 proteins accumulate and are activated through two mechanisms. One, involving ataxia telangiectasia-mutated protein (ATM), is that the interaction between p53 and its down-regulation factor murine double minute 2 (MDM2) decreases, leading to p53 phosphorylation on Ser15, as determined by the post-translational mechanism; the other holds that p53 increases and is activated through the binding of ribosomal protein L26 (RPL26) or nucleolin to p53 mRNA 5' untranslated region (UTR), regulating p53 translation. Under hypoxia, p53 decreases transactivation and increases transrepression. The mutations outside the DNA binding domain of p53 also contribute to tumor progress, so further studies on p53 should also be focused on this direction. The subterranean blind mole rat Spalax in Israel is a good model for hypoxia-adaptation. The p53 of Spalax mutated in residue 172 and residue 207 from arginine to lysine, conferring it the ability to survive hypoxic conditions. This model indicates that p53 acts as a master gene of diversity formation during evolution.

  1. p53CP, a putative p53 competing protein that specifically binds to the consensus p53 DNA binding sites: A third member of the p53 family?

    OpenAIRE

    Bian, Junhui; Sun, Yi

    1997-01-01

    p53 tumor suppressor protein negatively regulates cell growth, mainly through the transactivation of its downstream target genes. As a sequence-specific DNA binding transcription factor, p53 specifically binds to a 20-bp consensus motif 5′-PuPuPuC(A/T) (T/A)GPyPyPyPuPuPuC(A/T)(T/A)GPyPyPy-3′. We have now identified, partially purified, and characterized an additional ≈40-kDa nuclear protein, p53CP (p53 competing protein), that specifically binds to the consensus p53 binding sites found in sev...

  2. Targeting p53 Null Neuroblastomas through RLIP76**

    OpenAIRE

    Singhal, Jyotsana; Yadav, Sushma; Nagaprashantha, Lokesh Dalasanur; Vatsyayan, Rit; SINGHAL, SHARAD S.; Awasthi, Sanjay

    2011-01-01

    The search for p53-independent mechanism of cancer cell killing is highly relevant to pediatric neuroblastomas, where successful therapy is limited by its transformation into p53 mutant and a highly drug-resistant neoplasm. Our studies on the drug-resistant p53 mutant as compared with drug-resistant p53 wild-type neuroblastoma revealed a novel mechanism for resistance to apoptosis: a direct role of p53 in regulating the cellular concentration of pro-apoptotic alkenals by functioning as a spec...

  3. [Bcl-2 inhibits p53-induced apoptosis after genotoxic damage by inhibitors of nuclear import of p53].

    Science.gov (United States)

    Beham, A; Schumacher, G; McDonnell, T J; Marin, M C; Jauch, K W

    1998-01-01

    The tumor suppressor gene p53 in overexpressed in 50% of colorectal carcinomas and is an interesting target for gene therapeutic approaches. Furthermore the protooncogen bcl-2 is known to inhibit p53 induced apoptosis and is expressed in some colorectal carcinomas. In this study mechanism of bcl-2 cell death inhibition after p53 induction were evaluated. The human colon carcinoma cell line RKO posses wild-type p53 and also expresses bcl-2 protein. RKO cells were treated with liposomal bcl-2 antisense oligonucleotides (AS), control oligonucleotides (CO) and empty liposomes (EL) resulting in decreased bcl-2 expression. After induction of p53 with gamma-irradiation p53 protein expression was induced in AS, CO and EL pretreated cells. Microscopy and immunoblotting was used to characterize subcellular localization of p53 protein. Further p53 subcellular localisation was examined after p53 transfer of wt p53 cDNA in three bcl-2 expressing cell lines. Most of the p53 protein remained localized in the cytosol and apoptosis was decreased in bcl-2 expressing cells assessed by flow cytometric analysis (Ao). Our data suggests that bcl-2 is able to modulate transmembrane trafficking of p53. This resulted in inhibition of cell death implicating that bcl-2 function is involved in regulation of transmembrane gradients. PMID:14518224

  4. Tumor suppressor p53 meets microRNAs

    Institute of Scientific and Technical Information of China (English)

    Zhaohui Feng; Cen Zhang; Rui Wu; Wenwei Hu

    2011-01-01

    Tumor suppressor p53 plays a central role in tumor prevention. As a transcription factor, p53 mainly exerts its function through transcription regulation of its target genes to initiate various cellular responses. To maintain its proper function, p53 is tightly regulated by a wide variety of regulators in cells. Thus, p53, its regulators and regulated genes form a complex p53 network which is composed of hundreds of genes and their products. microRNAs (miRNAs) are a class of endogenously expressed, small non-coding RNA molecules which play a key role in regulation of gene expression at the post-transcriptional level. Recent studies have demonstrated that miRNAs interact with p53 and its network at multiple levels. p53 regulates the transcription expression and the maturation of a group of miRNAs. On the other hand, miRNAs can regulate the activity and function of p53 through direct repression of p53 or its regulators in cells. These findings have demonstrated that miRNAs are important components in the p53 network, and also added another layer of complexity to the p53 network.

  5. A novel p53-binding domain in CUL7.

    Science.gov (United States)

    Kasper, Jocelyn S; Arai, Takehiro; DeCaprio, James A

    2006-09-15

    CUL7 is a member of the cullin RING ligase family and forms an SCF-like complex with SKP1 and FBXW8. CUL7 is required for normal mouse embryonic development and cellular proliferation, and is highly homologous to PARC, a p53-associated, parkin-like cytoplasmic protein. We determined that CUL7, in a manner similar to PARC, can bind directly to p53 but does not affect p53 expression. We identified a discrete, co-linear domain in CUL7 that is conserved in PARC and HERC2, and is necessary and sufficient for p53-binding. The presence of p53 stabilized expression of this domain and we demonstrate that this p53-binding domain of CUL7 contributes to the cytoplasmic localization of CUL7. The results support the model that p53 plays a role in regulation of CUL7 activity. PMID:16875676

  6. The p53-MDM2 network: from oscillations to apoptosis

    Indian Academy of Sciences (India)

    Indrani Bose; Bhaswar Ghosh

    2007-08-01

    The p53 protein is well-known for its tumour suppressor function. The p53-MDM2 negative feedback loop constitutes the core module of a network of regulatory interactions activated under cellular stress. In normal cells, the level of p53 proteins is kept low by MDM2, i.e. MDM2 negatively regulates the activity of p53. In the case of DNA damage, the p53-mediated pathways are activated leading to cell cycle arrest and repair of the DNA. If repair is not possible due to excessive damage, the p53-mediated apoptotic pathway is activated bringing about cell death. In this paper, we give an overview of our studies on the p53-MDM2 module and the associated pathways from a systems biology perspective. We discuss a number of key predictions, related to some specific aspects of cell cycle arrest and cell death, which could be tested in experiments.

  7. 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.

    2012-01-01

    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,

  8. A naturally occurring 4-bp deletion in the intron 4 of p53 creates a spectrum of novel p53 isoforms with anti-apoptosis function

    OpenAIRE

    Hui SHI; Tao, Ting; Huang, Delai; Ou, Zhao; Chen, Jun; Peng, Jinrong

    2014-01-01

    p53 functions as a tumor suppressor by transcriptionally regulating the expression of genes involved in controlling cell proliferation or apoptosis. p53 and its isoform Δ133p53/Δ113p53 form a negative regulation loop in that p53 activates the expression of Δ133p53/Δ113p53 while Δ133p53/Δ113p53 specifically antagonizes p53 apoptotic activity. This pathway is especially important to safeguard the process of embryogenesis because sudden activation of p53 by DNA damage signals or developmental st...

  9. Loss of p53-regulatory protein IFI16 induces NBS1 leading to activation of p53-mediated checkpoint by phosphorylation of p53 SER37.

    Science.gov (United States)

    Tawara, Hideyuki; Fujiuchi, Nobuko; Sironi, Juan; Martin, Sarah; Aglipay, Jason; Ouchi, Mutsuko; Taga, Makoto; Chen, Phang-Lang; Ouchi, Toru

    2008-01-01

    Our previous results that IFI16 is involved in p53 transcription activity under conditions of ionizing radiation (IR), and that the protein is frequently lost in human breast cancer cell lines and breast adenocarcinoma tissues suggesting that IFI16 plays a crucial role in controlling cell growth. Here, we show that loss of IFI16 by RNA interference in cell culture causes elevated phosphorylation of p53 Ser37 and accumulated NBS1 (nibrin) and p21WAF1, leading to growth retardation. Consistent with these observations, doxycyclin-induced NBS1 caused accumulation of p21WAF1 and increased phosphorylation of p53 Ser37, leading to cell cycle arrest in G1 phase. Wortmannin treatment was found to decrease p53 Ser37 phosphorylation in NBS-induced cells. These results suggest that loss of IFI16 activates p53 checkpoint through NBS1-DNA-PKcs pathway. PMID:17981542

  10. p53 facilitates pRb cleavage in IL-3-deprived cells: novel pro-apoptotic activity of p53.

    OpenAIRE

    Gottlieb, E; Oren, M.

    1998-01-01

    In the interleukin-3 (IL-3)-dependent lymphoid cell line DA-1, functional p53 is required for efficient apoptosis in response to IL-3 withdrawal. Activation of p53 in these cells, by either DNA damage or p53 overexpression, results in a vital growth arrest in the presence of IL-3 and in accelerated apoptosis in its absence. Thus, IL-3 can control the choice between p53-dependent cell-cycle arrest and apoptosis. Here we report that the cross-talk between p53 and IL-3 involves joint control of ...

  11. Role of p53 isoforms and aggregations in cancer.

    Science.gov (United States)

    Kim, SeJin; An, Seong Soo A

    2016-06-01

    p53 is a master regulatory protein that is involved in diverse cellular metabolic processes such as apoptosis, DNA repair, and cell cycle arrest. The protective function of p53 (in its homotetrameric form) as a tumor suppressor is lost in more than 50% of human cancers.Despite considerable experimental evidence suggesting the presence of multiple p53 states, it has been difficult to correlate the status of p53 with cancer response to treatments and clinical outcomes, which suggest the importance of complex but essential p53 regulatory pathways.Recent studies have indicated that the expression pattern of p53 isoforms may play a crucial role in regulating normal and cancer cell fates in response to diverse stresses. The human TP53 gene encodes at least 12 p53 isoforms, which are produced in normal tissue through alternative initiation of translation, usage of alternative promoters, and alternative splicing. Furthermore, some researchers have suggested that the formation of mutant p53 aggregates may be associated with cancer pathogenesis due to loss-of function (LoF), dominant-negative (DN), and gain-of function (GoF) effects.As different isoforms or the aggregation state of p53 may influence tumorigenesis, this review aims to examine the correlation of p53 isoforms and aggregation with cancer. PMID:27368003

  12. Mitofusin-2 is a novel direct target of p53

    International Nuclear Information System (INIS)

    Research highlights: → Mfn2 is a novel target gene of p53. → Mfn2 mRNA and protein levels can be up-regulated in a p53-dependent manner. → Mfn2 promoter activity can be elevated by the p53 protein. → P53 protein binds the Mfn2 promoter directly both in vitro and in vivo. -- Abstract: The tumor suppressor p53 modulates transcription of a number of target genes involved in cell cycle arrest, apoptosis, DNA repair, and other important cellular responses. Mitofusin-2 (Mfn2) is a novel suppressor of cell proliferation that may also exert apoptotic effects via the mitochondrial apoptotic pathway. Through bioinformatics analysis, we identified a p53 binding site in the Mfn2 promoter. Consistent with this, we showed that the p53 protein binds the Mfn2 promoter directly both in vitro and in vivo. Additionally, we found that Mfn2 mRNA and protein levels are up-regulated in a p53-dependent manner. Furthermore, luciferase assays revealed that the activity of the wild-type Mfn2 promoter, but not a mutated version of the promoter, was up-regulated by p53. These results indicate that Mfn2 is a novel p53-inducible target gene, which provides insight into the regulation of Mfn2 and its associated activities in the inhibition of cell proliferation, promotion of apoptosis, and modulation of tumor suppression.

  13. P53 family and cellular stress responses in cancer

    Directory of Open Access Journals (Sweden)

    Johanna ePflaum

    2014-10-01

    Full Text Available p53 is an important tumor suppressor gene, which is stimulated by cellular stress like ionizing radiation, hypoxia, carcinogens and oxidative stress. Upon activation p53 leads to cell cycle arrest and promotes DNA repair or induces apoptosis via several pathways. p63 and p73 are structural homologs of p53 that can act similarly to the protein but also hold functions distinct from p53. Today more than forty different isoforms of the p53 family members are known. They result from transcription via different promoters and alternative splicing. Some isoforms have carcinogenic properties and mediate resistance to chemotherapy. Therefore, expression patterns of the p53 family genes can offer prognostic information in several malignant tumors. Furthermore, the p53 family constitutes a potential target for cancer therapy. Small molecules (e.g. Nutlins, RITA, PRIMA-1, and MIRA-1 among others have been objects of intense research interest in recent years. They restore pro-apoptotic wild-type p53 function and were shown to break chemotherapeutic resistance. Due to p53 family interactions small molecules also influence p63 and p73 activity. Thus, the members of the p53 family are key players in the cellular stress response in cancer and are expected to grow in importance as therapeutic targets.

  14. Mitofusin-2 is a novel direct target of p53

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weilin; Cheng, Xiaofei; Lu, Jianju; Wei, Jianfeng [Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Key Lab of Organ Transplantation, Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China); Fu, Guanghou [Department of Urology, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou (China); Zhu, Feng; Jia, Changku; Zhou, Lin; Xie, Haiyang [Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Key Lab of Organ Transplantation, Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China); Zheng, Shusen, E-mail: shusenzheng@zju.edu.cn [Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, Key Lab of Organ Transplantation, Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003 (China)

    2010-10-01

    Research highlights: {yields} Mfn2 is a novel target gene of p53. {yields} Mfn2 mRNA and protein levels can be up-regulated in a p53-dependent manner. {yields} Mfn2 promoter activity can be elevated by the p53 protein. {yields} P53 protein binds the Mfn2 promoter directly both in vitro and in vivo. -- Abstract: The tumor suppressor p53 modulates transcription of a number of target genes involved in cell cycle arrest, apoptosis, DNA repair, and other important cellular responses. Mitofusin-2 (Mfn2) is a novel suppressor of cell proliferation that may also exert apoptotic effects via the mitochondrial apoptotic pathway. Through bioinformatics analysis, we identified a p53 binding site in the Mfn2 promoter. Consistent with this, we showed that the p53 protein binds the Mfn2 promoter directly both in vitro and in vivo. Additionally, we found that Mfn2 mRNA and protein levels are up-regulated in a p53-dependent manner. Furthermore, luciferase assays revealed that the activity of the wild-type Mfn2 promoter, but not a mutated version of the promoter, was up-regulated by p53. These results indicate that Mfn2 is a novel p53-inducible target gene, which provides insight into the regulation of Mfn2 and its associated activities in the inhibition of cell proliferation, promotion of apoptosis, and modulation of tumor suppression.

  15. 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.

  16. Immunohistochemical Determination of p53 Protein Overexpression for Predicting p53 Gene Mutations in Hepatocellular Carcinoma: A Meta-Analysis

    Science.gov (United States)

    Deng, Miao; Liu, Dechun; Ma, Qingyong; Feng, Xiaoshan

    2016-01-01

    Background Whether increased expression of the tumor suppressor protein p53 indicates a p53 gene mutation in hepatocellular carcinoma (HCC) remains unclear. We conducted a meta-analysis to determine whether p53 protein overexpression detected by immunohistochemistry (IHC) offers a diagnostic prediction for p53 gene mutations in HCC patients. Methods Systematic literature searches were conducted with an end date of December 2015. A meta-analysis was performed to estimate the diagnostic accuracy of IHC-determined p53 protein overexpression in the prediction of p53 gene mutations in HCC. Sensitivity, subgroup, and publication bias analyses were also conducted. Results Thirty-six studies were included in the meta-analysis. The results showed that the overall sensitivity and specificity for IHC-determined p53 overexpression in the diagnostic prediction of p53 mutations in HCC were 0.83 (95% CI: 0.80–0.86) and 0.74 (95% CI: 0.71–0.76), respectively. The summary positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 2.65 (95% CI: 2.21–3.18) and 0.36 (95% CI: 0.26–0.50), respectively. The diagnostic odds ratio (DOR) of IHC-determined p53 overexpression in predicting p53 mutations ranged from 0.56 to 105.00 (pooled, 9.77; 95% CI: 6.35–15.02), with significant heterogeneity between the included studies (I2 = 40.7%, P = 0.0067). Moreover, subgroup and sensitivity analyses did not alter the results of the meta-analysis. However, potential publication bias was present in the current meta-analysis. Conclusion The upregulation of the tumor suppressor protein p53 was indeed linked to p53 gene mutations. IHC determination of p53 overexpression can predict p53 gene mutations in HCC patients. PMID:27428001

  17. p53 levels, cell cycle kinetics and radiosensitivity in two SV40 transformed Wi38VA13 fibroblast strains

    International Nuclear Information System (INIS)

    Background: The tumor suppressor protein p53 which can mediate an ionizing radiation-induced G1 arrest in mammalian cells, forms complexes with SV40 large T antigen (l-T-Ag). We have analyzed the p53 levels, the capability to undergo a G1 arrest and the radiosensitivity of two SV40 transformed fibroblast strains differing in their large T antigen expression. Material and Methods: One of the two strains (VA13F) is the commercially available form of Wi38VA13, the other (VA13E) arose spontaneously from the original one in our laboratory. Their p53 levels were measured by means of flow cytometry (FCM) and Western blot (WB) with two p53 antibodies (Ab-3, clone PAb240; Ab-6, clone DO-1; both Oncogene Science). Cell cycle distributions were determined flow cytometrically after BrdU labeling at regular time intervals after exposure to 250 kV X-rays. Radiosensitivity was assessed in a clonogenicity assay. Results: The p53 levels of the two strains corresponded to their large T antigen expression, presumably due to complex formation between the two proteins. The strain with a high p53 level did not show a G1 arrest and had a relatively high radiosensitivity, whereas the strain with a low p53 level showed a significant G1 arrest and a lower radiosensitivity. Conclusion: These results suggest that 1. complex formation between the large T antigen and p53 reduces the latter's functionality; 2. in these two strains the G1 arrest is one of the factors determining radiosensitivity. (orig.)

  18. Computational protein design suggests that human PCNA-partner interactions are not optimized for affinity.

    Science.gov (United States)

    Fridman, Yearit; Gur, Eyal; Fleishman, Sarel J; Aharoni, Amir

    2013-02-01

    Increasing the affinity of binding proteins is invaluable for basic and applied biological research. Currently, directed protein evolution experiments are the main approach for generating such proteins through the construction and screening of large mutant libraries. Proliferating cell nuclear antigen (PCNA) is an essential hub protein that interacts with many different partners to tightly regulate DNA replication and repair in all eukaryotes. Here, we used computational design to generate human PCNA mutants with enhanced affinity for several different partners. We identified double mutations in PCNA, outside the main partner binding site, that were predicted to increase PCNA-partner binding affinities compared to the wild-type protein by forming additional hydrophobic interactions with conserved residues in the PCNA partners. Affinity increases were experimentally validated with four different PCNA partners, demonstrating that computational design can reveal unexpected regions where affinity enhancements in natural systems are possible. The designed PCNA mutants can be used as a valuable tool for further examination of the regulation of PCNA-partner interactions during DNA replication and repair both in vitro and in vivo. More broadly, the ability to engineer affinity increases toward several PCNA partners suggests that interaction affinity is not an evolutionarily optimized trait of this system. PMID:23011891

  19. Estimation of growth rate of Skeletonema costatum based on relative expression amount of PCNA gene

    Institute of Scientific and Technical Information of China (English)

    HE Shanying; YU Zhigang

    2008-01-01

    Partial sequence of Skeletonema costatum proliferating cell nuclear antigen (PCNA) gene was obtained by reverse transcriptase PCR(RT-PCR) and 3' rapid amplification of cDNA ends (3'-RACE) techniques.Based on the obtained PCNA and cytochrome b gene(Cyt b gene) sequences,a real-time fluorescent quantitative PCR (FQ-PCR) method was developed to detect the expres-sion S.costatum PCNA gene,and this method was applied to study the relationship between the growth rate of S.costatum and the average expression amount of PCNA gene in a single cell.The expression amount of PCNA gene had large variation in cells col-lected at different culture phases,and the trend was well consistent with the growth rate,which suggested that the expression amount of PCNA gene correlated well with the cell division,and the PCNA could be a promising indicator for the S.costatum cell proliferation.Furthermore,using the PCNA gene as the objective gene and the Cyt b gene as the house-keeping gene,a new method for estimating the in situ growth rate of S.costatum was established by analysis of the relative expression quantity (REQ) of the PCNA gene.

  20. A PCNA-derived cell permeable peptide selectively inhibits neuroblastoma cell growth.

    Directory of Open Access Journals (Sweden)

    Long Gu

    Full Text Available Proliferating cell nuclear antigen (PCNA, through its interaction with various proteins involved in DNA synthesis, cell cycle regulation, and DNA repair, plays a central role in maintaining genome stability. We previously reported a novel cancer associated PCNA isoform (dubbed caPCNA, which was significantly expressed in a broad range of cancer cells and tumor tissues, but not in non-malignant cells. We found that the caPCNA-specific antigenic site lies between L126 and Y133, a region within the interconnector domain of PCNA that is known to be a major binding site for many of PCNA's interacting proteins. We hypothesized that therapeutic agents targeting protein-protein interactions mediated through this region may confer differential toxicity to normal and malignant cells. To test this hypothesis, we designed a cell permeable peptide containing the PCNA L126-Y133 sequence. Here, we report that this peptide selectively kills human neuroblastoma cells, especially those with MYCN gene amplification, with much less toxicity to non-malignant human cells. Mechanistically, the peptide is able to block PCNA interactions in cancer cells. It interferes with DNA synthesis and homologous recombination-mediated double-stranded DNA break repair, resulting in S-phase arrest, accumulation of DNA damage, and enhanced sensitivity to cisplatin. These results demonstrate conceptually the utility of this peptide for treating neuroblastomas, particularly, the unfavorable MYCN-amplified tumors.

  1. Mutant p53 in cell adhesion and motility.

    Science.gov (United States)

    Yeudall, W Andrew; Wrighton, Katharine H; Deb, Sumitra

    2013-01-01

    Pro-oncogenic properties of mutant p53 were investigated with the aid of migration assays, adhesion assays, and soft agar growth assays using cells stably expressing gain-of-function p53 mutants. To determine cell migration, "wound-healing" (scratch) assays and haptotactic (chamber) assays were used. H1299 cells expressing mutant p53 were found to migrate more rapidly than cells transfected with empty vector alone. Results from both types of migration assay were broadly similar. Migratory ability differed for different p53 mutants, suggesting allele-specific effects. Cells expressing p53 mutants also showed enhanced adhesion to extracellular matrix compare to controls. Furthermore, stable transfection of mutant p53-H179L into NIH3T3 fibroblasts was sufficient to allow anchorage-independent growth in soft agar. PMID:23150443

  2. New microRNAS regulating the P53 signaling pathway

    OpenAIRE

    Bisso, Andrea

    2010-01-01

    A vast body of evidence from clinical and basic research studies has demonstrated that the p53 pathway acts as an essential barrier in preventing cancer onset and development. ------------------------ A vast body of evidence from clinical and basic research studies has demonstrated that the p53 pathway acts as an essential barrier in preventing cancer onset and development. p53 receives and integrates a wide variety of cytotoxic and genotoxic stress signals from upstream sensors transla...

  3. p53 isoforms regulate astrocyte-mediated neuroprotection and neurodegeneration.

    Science.gov (United States)

    Turnquist, C; Horikawa, I; Foran, E; Major, E O; Vojtesek, B; Lane, D P; Lu, X; Harris, B T; Harris, C C

    2016-09-01

    Bidirectional interactions between astrocytes and neurons have physiological roles in the central nervous system and an altered state or dysfunction of such interactions may be associated with neurodegenerative diseases, such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). Astrocytes exert structural, metabolic and functional effects on neurons, which can be either neurotoxic or neuroprotective. Their neurotoxic effect is mediated via the senescence-associated secretory phenotype (SASP) involving pro-inflammatory cytokines (e.g., IL-6), while their neuroprotective effect is attributed to neurotrophic growth factors (e.g., NGF). We here demonstrate that the p53 isoforms Δ133p53 and p53β are expressed in astrocytes and regulate their toxic and protective effects on neurons. Primary human astrocytes undergoing cellular senescence upon serial passaging in vitro showed diminished expression of Δ133p53 and increased p53β, which were attributed to the autophagic degradation and the SRSF3-mediated alternative RNA splicing, respectively. Early-passage astrocytes with Δ133p53 knockdown or p53β overexpression were induced to show SASP and to exert neurotoxicity in co-culture with neurons. Restored expression of Δ133p53 in near-senescent, otherwise neurotoxic astrocytes conferred them with neuroprotective activity through repression of SASP and induction of neurotrophic growth factors. Brain tissues from AD and ALS patients possessed increased numbers of senescent astrocytes and, like senescent astrocytes in vitro, showed decreased Δ133p53 and increased p53β expression, supporting that our in vitro findings recapitulate in vivo pathology of these neurodegenerative diseases. Our finding that Δ133p53 enhances the neuroprotective function of aged and senescent astrocytes suggests that the p53 isoforms and their regulatory mechanisms are potential targets for therapeutic intervention in neurodegenerative diseases. PMID:27104929

  4. Targeting oncogenic mutant p53 for cancer therapy

    OpenAIRE

    Tomoo eIwakuma; Alejandro eParrales

    2015-01-01

    Among genetic alterations in human cancers, mutations in the tumor suppressor p53 gene are the most common, occurring in over 50% of human cancers. The majority of p53 mutations are missense mutations and result in the accumulation of dysfunctional p53 protein in tumors. These mutants frequently have oncogenic gain-of-function (GOF) activities and exacerbate malignant properties of cancer cells, such as metastasis and drug resistance. Increasing evidence reveals that stabilization of mutant p...

  5. Regulation of MCP-1 chemokine transcription by p53

    Directory of Open Access Journals (Sweden)

    Wasylyk Bohdan

    2010-04-01

    Full Text Available Abstract Background Our previous studies showed that the expression of the monocyte-chemoattractant protein (MCP-1, a chemokine, which triggers the infiltration and activation of cells of the monocyte-macrophage lineage, is abrogated in human papillomavirus (HPV-positive premalignant and malignant cells. In silico analysis of the MCP-1 upstream region proposed a putative p53 binding side about 2.5 kb upstream of the transcriptional start. The aim of this study is to monitor a physiological role of p53 in this process. Results The proposed p53 binding side could be confirmed in vitro by electrophoretic-mobility-shift assays and in vivo by chromatin immunoprecipitation. Moreover, the availability of p53 is apparently important for chemokine regulation, since TNF-α can induce MCP-1 only in human keratinocytes expressing the viral oncoprotein E7, but not in HPV16 E6 positive cells, where p53 becomes degraded. A general physiological role of p53 in MCP-1 regulation was further substantiated in HPV-negative cells harboring a temperature-sensitive mutant of p53 and in Li-Fraumeni cells, carrying a germ-line mutation of p53. In both cases, non-functional p53 leads to diminished MCP-1 transcription upon TNF-α treatment. In addition, siRNA directed against p53 decreased MCP-1 transcription after TNF-α addition, directly confirming a crosstalk between p53 and MCP-1. Conclusion These data support the concept that p53 inactivation during carcinogenesis also affects immune surveillance by interfering with chemokine expression and in turn communication with cells of the immunological compartment.

  6. Influence of p53-regulated energy metabolism in radiation effects

    International Nuclear Information System (INIS)

    p53 is a hot spot in the studies of tumor etiology and radiobiology, but the function of p53-regulated energy metabolism in radiation biological effects still remains many uncertainties. The in-depth study of p53-regulated energy metabolism is of great significance to investigate the tumor radiotherapy efficacy, radiation damage, carcinogenesis and even molecular epidemiology. The current research progress at this point was stated in this article. (authors)

  7. Resistance of mitochondrial p53 to dominant inhibition

    OpenAIRE

    Mestres Pedro; Armbruester Vivienne; Mueller Daniel; Schmitt Katrin; Heyne Kristina; Roemer Klaus

    2008-01-01

    Abstract Background Mutation of a tumor suppressor allele leaves the second as backup. Not necessarily so with p53. This homo-tetrameric transcription factor can become contaminated with mutant p53 through hetero-tetramerization. In addition, it can be out-competed by the binding to p53 DNA recognition motifs of transactivation-incompetent isoforms (ΔN and ΔTA-isoforms) of the p53/p63/p73 family of proteins. Countermeasures against such dominant-negative or dominant-inhibitory action might in...

  8. MEKK1/JNK signaling stabilizes and activates p53

    OpenAIRE

    Fuchs, Serge Y.; Adler, Victor; Pincus, Matthew R.; Ronai, Ze’ev

    1998-01-01

    Activation of the tumor suppressor p53 by stress and damage stimuli often correlates with induction of stress kinases, Jun-NH2 kinase (JNK). As JNK association with p53 plays an important role in p53 stability, in the present study we have elucidated the relationship between the JNK-signaling pathway and p53 stability and activity. Expression of a constitutively active form of JNKK upstream kinase, mitogen-activated protein kinase kinase kinase (ΔMEKK1), increased the level of the exogenously...

  9. p53-Dependent transcriptional responses to interleukin-3 signaling.

    Directory of Open Access Journals (Sweden)

    Anissa M Jabbour

    Full Text Available p53 is critical in the normal response to a variety of cellular stresses including DNA damage and loss of p53 function is a common feature of many cancers. In hematological malignancies, p53 deletion is less common than in solid malignancies but is associated with poor prognosis and resistance to chemotherapy. Compared to their wild-type (WT counterparts, hematopoietic progenitor cells lacking p53 have a greater propensity to survive cytokine loss, in part, due to the failure to transcribe Puma, a proapoptotic Bcl-2 family member. Using expression arrays, we have further characterized the differences that distinguish p53(-/- cells from WT myeloid cells in the presence of Interleukin-3 (IL-3 to determine if such differences contribute to the increased clonogenicity and survival responses observed in p53(-/- cells. We show that p53(-/- cells have a deregulated intracellular signaling environment and display a more rapid and sustained response to IL-3. This was accompanied by an increase in active ERK1/2 and a dependence on an intact MAP kinase signaling pathway. Contrastingly, we find that p53(-/- cells are independent on AKT for their survival. Thus, loss of p53 in myeloid cells results in an altered transcriptional and kinase signaling environment that favors enhanced cytokine signaling.

  10. p53: Biology and role for cellular radiosensitivity

    International Nuclear Information System (INIS)

    Purpose: p53 is the most commonly mutated gene in human tumors with large impact on cellular biology and response to radiation. Many excellent reviews are available on various aspects but for several years none about the role of p53 for radiosensitivity. The latter is the aim of the present paper. Methods: Review of the literature. Results: p53 is a regulator of apoptosis mainly in hematopoetic tissue. In normal tissue and solid tumors presumably other functions have more impact on the cellular response. p53 controls cell-cycle progression after irradiation and also DNA-repair, namely homologous and non-homologous recombination. Mutations of p53 alter these functions which may be responsible for an enhanced cellular and tumor radioresistance. At present only few reports were able to show that under tightly controlled conditions loss of p53 wild-type function leads to enhanced radioresistance. A general proof is still lacking. Conclusion: The emerging picture in the year 2000 shows p53 as a central protein in a multi-enzyme multi-function network which is far from being fully understood. Although p53 appears to be a major regulator it is certainly not the unreplacable component the loss of which uniformly determines radioresistance. Only further understanding of modifiers and cooperators in the cell and in the specific tissue context will elucidate p53's role for radiosensitivity and radiotherapy. (orig.)

  11. p53 Antibody and Malignant Tumor%p53抗体与恶性肿瘤

    Institute of Scientific and Technical Information of China (English)

    曾常茜; 王振明

    2002-01-01

    p53基因是人类肿瘤中突变频率最高的抑癌基因,几乎发生于所有的恶性肿瘤.突变基因编码的p53蛋白释放入血,可诱发机体自身免疫应答,产生p53自身抗体.在肿瘤病人和高危人群中检测血清p53抗体可以反映早期p53基因突变,作为一种新的肿瘤生物学指标,p53抗体有望在恶性肿瘤的早期诊断、治疗、预后、监测、复发等方面发挥重要作用.

  12. The Proteasome Activator PA28γ, a Negative Regulator of p53, Is Transcriptionally Up-Regulated by p53

    Directory of Open Access Journals (Sweden)

    Zhen-Xing Wan

    2014-02-01

    Full Text Available PA28γ (also called REGγ, 11Sγ or PSME3 negatively regulates p53 activity by promoting its nuclear export and/or degradation. Here, using the RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE method, we identified the transcription start site of the PA28γ gene. Assessment with the luciferase assay demonstrated that the sequence −193 to +16 is the basal promoter. Three p53 binding sites were found within the PA28γ promoter utilizing a bioinformatics approach and were confirmed by chromatin immunoprecipitation and biotinylated DNA affinity precipitation experiments. The p53 protein promotes PA28γ transcription, and p53-stimulated transcription of PA28γ can be inhibited by PA28γ itself. Our results suggest that PA28γ and p53 form a negative feedback loop, which maintains the balance of p53 and PA28γ in cells.

  13. Induction of wild-type p53 activity in human cancer cells by ribozymes that repair mutant p53 transcripts

    OpenAIRE

    Watanabe, Takashi; Sullenger, Bruce A

    2000-01-01

    Several groups have attempted to develop gene therapy strategies to treat cancer via introduction of the wild-type (wt) p53 cDNA into cancer cells. Unfortunately, these approaches do not result in regulated expression of the p53 gene and do not reduce expression of the mutant p53 that is overexpressed in cancerous cells. These shortcomings may greatly limit the utility of this gene replacement approach. We describe an alternative strategy with trans-splicing ribozymes that can simultaneously ...

  14. Modeling the basal dynamics of p53 system.

    Directory of Open Access Journals (Sweden)

    Tingzhe Sun

    Full Text Available BACKGROUND: The tumor suppressor p53 has become one of most investigated genes. Once activated by stress, p53 leads to cellular responses such as cell cycle arrest and apoptosis. METHODOLOGY/PRINCIPAL FINDINGS: Most previous models have ignored the basal dynamics of p53 under nonstressed conditions. To explore the basal dynamics of p53, we constructed a stochastic delay model by incorporating two negative feedback loops. We found that protein distribution of p53 under nonstressed condition is highly skewed with a fraction of cells showing high p53 levels comparable to those observed under stressed conditions. Under nonstressed conditions, asynchronous and spontaneous p53 pulses are triggered by basal DNA double strand breaks produced during normal cell cycle progression. The first peaking times show a predominant G1 distribution while the second ones are more widely distributed. The spontaneous pulses are triggered by an excitable mechanism. Once initiated, the amplitude and duration of pulses remain unchanged. Furthermore, the spontaneous pulses are filtered by ataxia telangiectasia mutated protein mediated posttranslational modifications and do not result in substantial p21 transcription. If challenged by externally severe DNA damage, cells generate synchronous p53 pulses and induce significantly high levels of p21. The high expression of p21 can also be partially induced by lowering the deacetylation rate. CONCLUSIONS: Our results demonstrated that the dynamics of p53 under nonstressed conditions is initiated by an excitable mechanism and cells become fully responsive only when cells are confronted with severe damage. These findings advance our understanding of the mechanism of p53 pulses and unlock many opportunities to p53-based therapy.

  15. P53 Gene Mutation and Expression of MDM2, P53, P16 Protein and their Relationship in Human Glioma

    Institute of Scientific and Technical Information of China (English)

    CUI Wen; WU Renliang; CAO Huiling; GAO Jifa; WANG Xu; REN Qiwei

    2005-01-01

    To investigate the effect of P53 protein accumulation and p53 gene mutation in the pathogenesis of glioma and to study the role of MDM2, P53 and P16 protein in glioma formation and progression and their relationship with each other, LSAB immunohistochemical staining method and non-isotopic PCR-SSCP techniques were used to detect the expression of MDM2, P53 and P16 pro tein and p53 gene mutation in 48 cases of gliomas. The results showed that the positive expression rate of MDM2, P53 and the negative rate of P16 was 22.9 %, 41.7 % and 60.4 %, respectively.The latter two in high grade (grade Ⅲ , Ⅳ) gliomas had a significantly higher rate than in the low grade (grade Ⅱ ) gliomas. Moreover, the co-expression of MDM2 and P53 protein was confirmed in only 1 of 48 cases. No significant difference was found in the rate of the expression of MDM2 between high grade and low grade gliomas (P>0.1) . PCR SSCP results showed that mutation of 5-8 exons of p53 gene was detected in 17 out of 48 cases (35.42 %) . Mutation was detected in 16of 20 cases of positive p53 expression, and another one was detected in 28 cases of negative expression cases. The correlation between p53 mutation and p53 immunopositivity was observed in 89.6% of the cases. P53 gene mutation and the level of MDM2, P53 and P16 protein were not related to age, gender of the patients, tumor location and size. It is concluded that the mutation of p53 and deletion of p16 might play important roles in the tumorigenesis of gliomas and it was significantly associated with the grade of tumor differentiation. P53 protein accumulation can indirectly reflect p53 mutation. MDM2 amplification and overexpression might be an early event in the growth of human gliomas.

  16. Dmp1 physically interacts with p53 and positively regulates p53’s stability, nuclear localization, and function

    OpenAIRE

    Frazier, Donna P.; Kendig, Robert D.; Kai, Fumitake; Maglic, Dejan; Sugiyama, Takayuki; Rachel L. Morgan; Fry, Elizabeth A.; Lagedrost, Sarah J.; Sui, Guangchao; Inoue, Kazushi

    2012-01-01

    The transcription factor Dmp1 is a Ras/HER2-activated haplo-insufficient tumor suppressor that activates the Arf/p53 pathway of cell cycle arrest. Recent evidence suggests that Dmp1 may activate p53 independently of Arf in certain cell types. Here we report findings supporting this concept with the definition an Arf-independent function for Dmp1 in tumor suppression. We found that Dmp1 and p53 can interact directly in mammalian cells via the carboxyl-terminus of p53 and the DNA-binding domain...

  17. Exploring a minimal two-component p53 model

    International Nuclear Information System (INIS)

    The tumor suppressor p53 coordinates many attributes of cellular processes via interlocked feedback loops. To understand the biological implications of feedback loops in a p53 system, a two-component model which encompasses essential feedback loops was constructed and further explored. Diverse bifurcation properties, such as bistability and oscillation, emerge by manipulating the feedback strength. The p53-mediated MDM2 induction dictates the bifurcation patterns. We first identified irradiation dichotomy in p53 models and further proposed that bistability and oscillation can behave in a coordinated manner. Further sensitivity analysis revealed that p53 basal production and MDM2-mediated p53 degradation, which are central to cellular control, are most sensitive processes. Also, we identified that the much more significant variations in amplitude of p53 pulses observed in experiments can be derived from overall amplitude parameter sensitivity. The combined approach with bifurcation analysis, stochastic simulation and sampling-based sensitivity analysis not only gives crucial insights into the dynamics of the p53 system, but also creates a fertile ground for understanding the regulatory patterns of other biological networks

  18. COX-2 and p53 in human sinonasal cancer

    DEFF Research Database (Denmark)

    Holmila, Reetta; Cyr, Diane; Luce, Danièle;

    2008-01-01

    to development of cancer. Many signals that activate COX-2 also induce tumor suppressor p53, a transcription factor central in cellular stress response. We investigated COX-2 and p53 expressions by immunohistochemistry in 50 SNCs (23 adenocarcinomas, and 27 squamous cell carcinomas (SCC); 48 analyzed...... for COX-2; 41 for p53). Occupational histories and smoking habits were available for majority of the cases. Most of the adenocarcinoma cases with exposure history data had been exposed to wood dust at work in the past (88%, 14/16). For smokers, 63% (12/19) presented with SSC, whereas 64% (7/11) of...... between the exposures and p53 accumulation were found; however, the p53 accumulation pattern (p = 0.062 for wood dust exposure) resembled that of COX-2 expression. In summary, our findings show increased COX-2 expression in SNC adenocarcinoma with wood dust exposure, suggesting a role for inflammatory...

  19. pCLPG: a p53-driven retroviral system

    International Nuclear Information System (INIS)

    We have modified the pCL retroviral system by the insertion of a p53-responsive element, called PG, in the U3 region of the 3'-LTR, either in addition to or in place of the native negative control region/enhancer sequence. We show here that either endogenous or exogenous wild-type p53 may be used to drive expression from the pCLPG system in transduced cells. Upon genotoxic induction of endogenous p53, pCLPG expression surpassed that of the parental, nonmodified virus, specifically when the native promoter was removed and substituted by the p53-responsive element. We propose that the novel pCLPG system will prove to be a valuable tool whether used as a reporter system of p53 function or as an in vitro and in vivo gene transfer vehicle

  20. p53 in the DNA-Damage-Repair Process.

    Science.gov (United States)

    Williams, Ashley B; Schumacher, Björn

    2016-01-01

    The cells in the human body are continuously challenged by a variety of genotoxic attacks. Erroneous repair of the DNA can lead to mutations and chromosomal aberrations that can alter the functions of tumor suppressor genes or oncogenes, thus causing cancer development. As a central tumor suppressor, p53 guards the genome by orchestrating a variety of DNA-damage-response (DDR) mechanisms. Already early in metazoan evolution, p53 started controlling the apoptotic demise of genomically compromised cells. p53 plays a prominent role as a facilitator of DNA repair by halting the cell cycle to allow time for the repair machineries to restore genome stability. In addition, p53 took on diverse roles to also directly impact the activity of various DNA-repair systems. It thus appears as if p53 is multitasking in providing protection from cancer development by maintaining genome stability. PMID:27048304

  1. Mitochondrial dysfunction impairs tumor suppressor p53 expression/function.

    Science.gov (United States)

    Compton, Shannon; Kim, Chul; Griner, Nicholas B; Potluri, Prasanth; Scheffler, Immo E; Sen, Sabyasachi; Jerry, D Joseph; Schneider, Sallie; Yadava, Nagendra

    2011-06-10

    Recently, mitochondria have been suggested to act in tumor suppression. However, the underlying mechanisms by which mitochondria suppress tumorigenesis are far from being clear. In this study, we have investigated the link between mitochondrial dysfunction and the tumor suppressor protein p53 using a set of respiration-deficient (Res(-)) mammalian cell mutants with impaired assembly of the oxidative phosphorylation machinery. Our data suggest that normal mitochondrial function is required for γ-irradiation (γIR)-induced cell death, which is mainly a p53-dependent process. The Res(-) cells are protected against γIR-induced cell death due to impaired p53 expression/function. We find that the loss of complex I biogenesis in the absence of the MWFE subunit reduces the steady-state level of the p53 protein, although there is no effect on the p53 protein level in the absence of the ESSS subunit that is also essential for complex I assembly. The p53 protein level was also reduced to undetectable levels in Res(-) cells with severely impaired mitochondrial protein synthesis. This suggests that p53 protein expression is differentially regulated depending upon the type of electron transport chain/respiratory chain deficiency. Moreover, irrespective of the differences in the p53 protein expression profile, γIR-induced p53 activity is compromised in all Res(-) cells. Using two different conditional systems for complex I assembly, we also show that the effect of mitochondrial dysfunction on p53 expression/function is a reversible phenomenon. We believe that these findings will have major implications in the understanding of cancer development and therapy. PMID:21502317

  2. p53 regulates the transcription of its Delta133p53 isoform through specific response elements contained within the TP53 P2 internal promoter.

    Science.gov (United States)

    Marcel, V; Vijayakumar, V; Fernández-Cuesta, L; Hafsi, H; Sagne, C; Hautefeuille, A; Olivier, M; Hainaut, P

    2010-05-01

    The tumor suppressor p53 protein is activated by genotoxic stress and regulates genes involved in senescence, apoptosis and cell-cycle arrest. Nine p53 isoforms have been described that may modulate suppressive functions of the canonical p53 protein. Among them, Delta133p53 lacks the 132 proximal residues and has been shown to modulate p53-induced apoptosis and cell-cycle arrest. Delta133p53 is expressed from a specific mRNA, p53I4, driven by an alternative promoter P2 located between intron 1 and exon 5 of TP53 gene. Here, we report that the P2 promoter is regulated in a p53-dependent manner. Delta133p53 expression is increased in response to DNA damage by doxorubicin in p53 wild-type cell lines, but not in p53-mutated cells. Chromatin immunoprecipitation and luciferase assays using P2 promoter deletion constructs indicate that p53 binds functional response elements located within the P2 promoter. We also show that Delta133p53 does not bind specifically to p53 consensus DNA sequence in vitro, but competes with wild-type p53 in specific DNA-binding assays. Finally, we report that Delta133p53 counteracts p53-dependent growth suppression in clonogenic assays. These observations indicate that Delta133p53 is a novel target of p53 that may participate in a negative feedback loop controlling p53 function. PMID:20190805

  3. The BAH domain of BAF180 is required for PCNA ubiquitination

    Energy Technology Data Exchange (ETDEWEB)

    Niimi, Atsuko [Department of Genome Dynamics, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Hopkins, Suzanna R; Downs, Jessica A [Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ (United Kingdom); Masutani, Chikahide, E-mail: masutani@riem.nagoya-u.ac.jp [Department of Genome Dynamics, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan)

    2015-09-15

    Highlights: • The expression of BAF180 promotes UV-induced PCNA ubiquitination during S phase. • The BAH domains of BAF180 alone are sufficient to promote PCNA ubiquitination. • The BAH domains are not assembled into the PBAF in the absence of the C-terminus. - Abstract: Monoubiquitination of proliferating cell nuclear antigen (PCNA) is a critical regulator of post replication repair (PRR). The depletion of BAF180, a unique subunit of the PBAF chromatin remodeling complex in human cells results in reduced PCNA ubiquitination leading to less efficient fork progression following DNA damage, but little is known about the mechanism. Here, we report that the expression of exogenous BAF180 in cells promotes PCNA ubiquitination during S-phase after UV irradiation and it persists for many hours. No correlation was observed between the protein level of ubiquitin-specific protease 1 (USP1) and ubiquitinated PCNA in BAF180 expressing cells. Analysis of cells expressing BAF180 deletion mutants showed that the bromo-adjacent homology (BAH) domains are responsible for this effect. Surprisingly, a deletion construct encoding only the BAH domain region is able to increase the level of ubiquitinated PCNA, even though it is unable to be assembled into the PBAF complex. These results suggest that the ATPase-dependent chromatin remodeling activity of PBAF is not necessary, but instead the BAH domains are sufficient to promote PCNA ubiquitination.

  4. PCNA interacts with Indian mung bean yellow mosaic virus rep and downregulates Rep activity.

    Science.gov (United States)

    Bagewadi, Basavaraj; Chen, Shoajiang; Lal, Sunil K; Choudhury, Nirupam Roy; Mukherjee, Sunil K

    2004-11-01

    Proliferative cell nuclear antigen (PCNA), a conserved plant protein as well as an important replication factor, is induced in response to geminivirus infection in the resting cells of the phloem tissues. The biochemical role of PCNA in rolling circle replication (RCR) of geminivirus DNA has not been explored in detail. The initiation of RCR of the bipartite genome of a geminivirus, Indian mung bean yellow mosaic virus (IMYMV), is mainly controlled by viral protein Rep (or AL1 or AC1). The role of host PCNA in RCR of IMYMV was revealed by studying the physical and functional interactions between recombinant PCNA and recombinant IMYMV Rep. Pea nuclear PCNA as well as recombinant pea PCNA showed binding to recombinant Rep in experiments involving both affinity chromatography and yeast two-hybrid approaches. The contacting amino acid residues of PCNA seemed to be present throughout a wide region of the trimeric protein, while those of Rep appeared to be localized only in the middle part of the protein. The site-specific nicking-closing activity and the ATPase function of IMYMV Rep were impaired by PCNA. These observations lead to interesting speculations about the control of viral RCR and dynamic profiles of protein-protein interactions at the RCR origin of the geminiviruses. PMID:15479830

  5. p53-Dependent G1 arrest and p53-independent apoptosis influence the radio biologic response of glioblastoma

    International Nuclear Information System (INIS)

    Purpose: Loss of the p53 tumor suppressor gene has been associated with tumor progression, disease relapse, poor response to antineoplastic therapy, and poor prognosis in many malignancies. We have investigated the contribution of p53-mediated radiation-induced apoptosis and G1 arrest to the well described radiation resistance of glioblastoma multiforme (GM) cells. Methods and Materials: Radiation survival in vitro was quantitated using linear quadratic and repair-saturation mathematical models. Isogenic derivatives of glioblastoma cells differing only in their p53 status were generated using a retroviral vector expressing a dominant negative mutant of p53. Radiation-induced apoptosis was assayed by Flourescence-activated cell sorter (FACS) analysis, terminal deoxynucleotide transferase labeling technique, and chromatin morphology. Cells were synchronized in early G1 phase and mitotic and labeling indices were measured. Results: Radiation-induced apoptosis of GM cells was independent of functional wild-type p53 (wt p53). Decreased susceptibility to radiation-induced apoptosis was associated with lower α values characterizing the shoulder of the clonogenic radiation survival curve. Using isogenic GM cells differing only in their p53 activity, we found that a p53-mediated function, radiation-induced G1 arrest, could also influence the value of α and clonogenic radiation resistance. Inactivation of wt p53 function by a dominant negative mutant of p53 resulted in a significantly diminished α value with no alteration in cellular susceptibility to radiation-induced apoptosis. The clonal derivative U87-LUX.8 expressing a functional wt p53 had an α (Gy-1) value of 0.609, whereas the isogenic clonal derivative U87-175.4 lacking wt p53 function had an α (Gy-1) value of 0.175. Conclusion: We conclude that two distinct cellular responses to radiation, p53-independent apoptosis and p53-dependent G1-arrest, influence radiobiological parameters that characterize the

  6. Fuzzy tandem repeats containing p53 response elements may define species-specific p53 target genes.

    Directory of Open Access Journals (Sweden)

    Iva Simeonova

    2012-06-01

    Full Text Available Evolutionary forces that shape regulatory networks remain poorly understood. In mammals, the Rb pathway is a classic example of species-specific gene regulation, as a germline mutation in one Rb allele promotes retinoblastoma in humans, but not in mice. Here we show that p53 transactivates the Retinoblastoma-like 2 (Rbl2 gene to produce p130 in murine, but not human, cells. We found intronic fuzzy tandem repeats containing perfect p53 response elements to be important for this regulation. We next identified two other murine genes regulated by p53 via fuzzy tandem repeats: Ncoa1 and Klhl26. The repeats are poorly conserved in evolution, and the p53-dependent regulation of the murine genes is lost in humans. Our results indicate a role for the rapid evolution of tandem repeats in shaping differences in p53 regulatory networks between mammalian species.

  7. Energetic Landscape of MDM2-p53 Interactions by Computational Mutagenesis of the MDM2-p53 Interaction.

    Science.gov (United States)

    Thayer, Kelly M; Beyer, George A

    2016-01-01

    The ubiquitin ligase MDM2, a principle regulator of the tumor suppressor p53, plays an integral role in regulating cellular levels of p53 and thus a prominent role in current cancer research. Computational analysis used MUMBO to rotamerize the MDM2-p53 crystal structure 1YCR to obtain an exhaustive search of point mutations, resulting in the calculation of the ΔΔG comprehensive energy landscape for the p53-bound regulator. The results herein have revealed a set of residues R65-E69 on MDM2 proximal to the p53 hydrophobic binding pocket that exhibited an energetic profile deviating significantly from similar residues elsewhere in the protein. In light of the continued search for novel competitive inhibitors for MDM2, we discuss possible implications of our findings on the drug discovery field. PMID:26992014

  8. p53: Biology and role for cellular radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Dahm-Daphi, J. [Hamburg Univ. (Germany). Abt. fuer Strahlentherapie und Onkologie

    2000-06-01

    Purpose: p53 is the most commonly mutated gene in human tumors with large impact on cellular biology and response to radiation. Many excellent reviews are available on various aspects but for several years none about the role of p53 for radiosensitivity. The latter is the aim of the present paper. Methods: Review of the literature. Results: p53 is a regulator of apoptosis mainly in hematopoetic tissue. In normal tissue and solid tumors presumably other functions have more impact on the cellular response. p53 controls cell-cycle progression after irradiation and also DNA-repair, namely homologous and non-homologous recombination. Mutations of p53 alter these functions which may be responsible for an enhanced cellular and tumor radioresistance. At present only few reports were able to show that under tightly controlled conditions loss of p53 wild-type function leads to enhanced radioresistance. A general proof is still lacking. Conclusion: The emerging picture in the year 2000 shows p53 as a central protein in a multi-enzyme multi-function network which is far from being fully understood. Although p53 appears to be a major regulator it is certainly not the unreplacable component the loss of which uniformly determines radioresistance. Only further understanding of modifiers and cooperators in the cell and in the specific tissue context will elucidate p53's role for radiosensitivity and radiotherapy. (orig.) [German] Hintergrund: p53 ist das am haeufigsten mutierte Gen in menschlichen Tumoren mit grossem Einfluss auf die zellulaere Biologie und Strahlenantwort. Viele ausgezeichnete Uebersichten sind verfuegbar, aber seit Jahren keine, die die Rolle von p53 fuer die Strahlenempfindlichkeit beleuchtet. Dies ist das Ziel der vorliegenden Arbeit. Methode: Literaturuebersicht. Ergebnis: p53 ist ein Regulator der Apoptose in haematopoetischen Gewerben. Im uebrigen Normalgewebe und in soliden Tumoren haben andere Funktionen groessere Bedeutung fuer die Zellantwort. Nach

  9. Cisplatinum and Taxol Induce Different Patterns of p53 Phosphorylation

    Directory of Open Access Journals (Sweden)

    Giovanna Damia

    2001-01-01

    Full Text Available Posttranslational modifications of p53 induced by two widely used anticancer agents, cisplatinum (DDP and taxol were investigated in two human cancer cell lines. Although both drugs were able to induce phosphorylation at serine 20 (Ser20, only DDP treatment induced p53 phosphorylation at serine 15 (Ser15. Moreover, both drug treatments were able to increase p53 levels and consequently the transcription of waf1 and mdm-2 genes, although DDP treatment resulted in a stronger inducer of both genes. Using two ataxia telangiectasia mutated (ATM cell lines, the role of ATM in druginduced p53 phosphorylations was investigated. No differences in drug-induced p53 phosphorylation could be observed, indicating that ATM is not the kinase involved in these phosphorylation events. In addition, inhibition of DNA-dependent protein kinase activity by wortmannin did not abolish p53 phosphorylation at Ser15 and Ser20, again indicating that DNA-PK is unlikely to be the kinase involved. After both taxol and DDP treatments, an activation of hCHK2 was found and this is likely to be responsible for phosphorylation at Ser20. In contrast, only DDP was able to activate ATR, which is the candidate kinase for phosphorylation of Ser15 by this drug. This data clearly suggests that differential mechanisms are involved in phosphorylation and activation of p53 depending on the drug type.

  10. 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.

  11. Molecular cloning and sequencing of Trichinella spiralis PCNA antigen%旋毛虫成虫cDNA文库的建立及PCNA基因克隆和序列分析

    Institute of Scientific and Technical Information of China (English)

    李丽娜; 赵蕾; 许士奇; 王丽娜; 赵香菊; 陈晓宁

    2013-01-01

    目的 建立旋毛虫成虫cDNA文库,对旋毛虫增殖细胞核抗原PCNA基因进行克隆和测序分析. 方法 收集纯净的旋毛虫成虫,提取RNA,构建cDNA文库.根据GenBank中登录的PCNA基因的序列设计并合成引物,用PCR方法从旋毛虫成虫基因库筛选PCNA基因;将PCR产物与pUM T载体连接,转化到感受态细胞DH5α,进行测序和同源性比较. 结果 成功构建旋毛虫成虫cDNA文库,克隆PCNA基因序列与GenBank登录的PCNA基因同源性为94%. 结论 成功构建了旋毛虫成虫cDNA文库;成功克隆了PCNA基因.%Objectives To construct a cDNA library of Trichinella spiralis and clone and sequence T. spiralis PCNA. Methods Adult T. spiralis worms were collected, their RNA was extracted, and a cDNA library was constructed. Primers were designed and synthesized in accordance with the PCNA gene sequence in GenBank. Polymerase chain reaction (PCR) was used to screen genes of adult T. spiralis worms for the PCNA gene. PCR products were ligated to pUM-T and transformed into DH5α competent cells, and sequences and homology were compared. Results A cDNA library of the adult T. spiralis worm was successfully constructed and the PCNA sequence was cloned; its identity with the sequence in GenBank was 94%. Conclusion A cDNA library of the adult T. spiralis worm was successfully and the PCNA gene was successfully cloned.

  12. p53-dependent apoptosis suppresses radiation-induced teratogenesis

    International Nuclear Information System (INIS)

    About half of human conceptions are estimated not to be implanted in the uterus, resulting in unrecognizable spontaneous abortions. Experimental studies with mice have established that irradiation during the preimplantation period of the embryo induces a high incidence of prenatal deaths but virtually no malformations. This suggests that some mechanism is screening out the damaged fetuses. In order to elucidate the mechanisms of tissue repair of radiation-induced teratogenic injury, we compared the incidences of radiation-induced malformations and abortions in p53 null (p53-/-) and wild-type (p53+/+) mice. After X-irradiation with 2 Gy on day 9.5 of gestation, p53-/- mice showed a 70% incidence of anomalies and a 7% incidence of deaths, whereas p53+/+ mice had a 20% incidence of anomalies and a 60% incidence of deaths. Similar results were obtained after irradiation on day 3.5 of gestation. This reciprocal relationship of radiosensitivity to anomalies and to embryonic or fetal lethality supports the notion that the p53 gene protects embryos and fetuses against the teratogenic effects of radiation by eliminating cells that have been badly damaged. In fact, after X-irradiation, the frequency of dying cells by apoptosis was greatly increased in tissues of the p53+/+ fetuses but not at all in those of the p53-/- fetuses. Mammals are protected from radiation-induced injury by two mechanisms, p53-dependent apoptotic tissue repair in addition to well known DNA repair. Therefore, there are threshold doses below which there is no induction of teratogenic and carcinogenic effects after exposure to low-level radiation. (author)

  13. POSTRANSLATIONAL MODIFICATIONS OF P53: UPSTREAM SIGNALING PATHWAYS.

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON,C.W.APPELLA,E.

    2003-10-23

    The p53 tumor suppressor is a tetrameric transcription factor that is posttranslational modified at >20 different sites by phosphorylation, acetylation, or sumoylation in response to various cellular stress conditions. Specific posttranslational modifications, or groups of modifications, that result from the activation of different stress-induced signaling pathways are thought to modulate p53 activity to regulate cell fate by inducing cell cycle arrest, apoptosis, or cellular senescence. Here we review recent progress in characterizing the upstream signaling pathways whose activation in response to various genotoxic and non-genotoxic stresses result in p53 posttranslational modifications.

  14. Distinct pattern of p53 mutations in bladder cancer

    DEFF Research Database (Denmark)

    Spruck, C H; Rideout, W M; Olumi, A F;

    1993-01-01

    A distinct mutational spectrum for the p53 tumor suppressor gene in bladder carcinomas was established in patients with known exposures to cigarette smoke. Single-strand conformational polymorphism analysis of exons 5 through 8 of the p53 gene showed inactivating mutations in 16 of 40 (40%) bladder....... The results suggest that, although cigarette smoke exposure may not significantly alter the kinds of mutations sustained in the p53 gene, it may act to increase the extent of DNA damage per mutagenic event....

  15. Stochastic modeling of p53-regulated apoptosis upon radiation damage

    CERN Document Server

    Bhatt, Divesh; Bahar, Ivet

    2011-01-01

    We develop and study the evolution of a model of radiation induced apoptosis in cells using stochastic simulations, and identified key protein targets for effective mitigation of radiation damage. We identified several key proteins associated with cellular apoptosis using an extensive literature survey. In particular, we focus on the p53 transcription dependent and p53 transcription independent pathways for mitochondrial apoptosis. Our model reproduces known p53 oscillations following radiation damage. The key, experimentally testable hypotheses that we generate are - inhibition of PUMA is an effective strategy for mitigation of radiation damage if the treatment is administered immediately, at later stages following radiation damage, inhibition of tBid is more effective.

  16. Structure of p15PAF-PCNA complex and implications for clamp sliding during DNA replication and repair

    Science.gov (United States)

    de Biasio, Alfredo; de Opakua, Alain Ibáñez; Mortuza, Gulnahar B.; Molina, Rafael; Cordeiro, Tiago N.; Castillo, Francisco; Villate, Maider; Merino, Nekane; Delgado, Sandra; Gil-Cartón, David; Luque, Irene; Diercks, Tammo; Bernadó, Pau; Montoya, Guillermo; Blanco, Francisco J.

    2015-03-01

    The intrinsically disordered protein p15PAF regulates DNA replication and repair by binding to the proliferating cell nuclear antigen (PCNA) sliding clamp. We present the structure of the human p15PAF-PCNA complex. Crystallography and NMR show the central PCNA-interacting protein motif (PIP-box) of p15PAF tightly bound to the front-face of PCNA. In contrast to other PCNA-interacting proteins, p15PAF also contacts the inside of, and passes through, the PCNA ring. The disordered p15PAF termini emerge at opposite faces of the ring, but remain protected from 20S proteasomal degradation. Both free and PCNA-bound p15PAF binds DNA mainly through its histone-like N-terminal tail, while PCNA does not, and a model of the ternary complex with DNA inside the PCNA ring is consistent with electron micrographs. We propose that p15PAF acts as a flexible drag that regulates PCNA sliding along the DNA and facilitates the switch from replicative to translesion synthesis polymerase binding.

  17. PCNA Interacts with Indian Mung Bean Yellow Mosaic Virus Rep and Downregulates Rep Activity

    OpenAIRE

    Bagewadi, Basavaraj; Chen, Shoajiang; Sunil K. Lal; Choudhury, Nirupam Roy; Mukherjee, Sunil K

    2004-01-01

    Proliferative cell nuclear antigen (PCNA), a conserved plant protein as well as an important replication factor, is induced in response to geminivirus infection in the resting cells of the phloem tissues. The biochemical role of PCNA in rolling circle replication (RCR) of geminivirus DNA has not been explored in detail. The initiation of RCR of the bipartite genome of a geminivirus, Indian mung bean yellow mosaic virus (IMYMV), is mainly controlled by viral protein Rep (or AL1 or AC1). The ro...

  18. 口腔扁平上皮癌の浸潤先進部におけるp53及びその関連蛋白の発現に関する免疫組織化学的研究 特にp53陽性細胞率検索の意義について

    OpenAIRE

    加藤, 広禄

    2003-01-01

    口腔扁平上皮癌の浸潤先進部におけるP53蛋白,p21蛋白,増殖細胞核抗原(PCNA)の発現を検討するために,治験前生検組織66症例を用いて免疫組織化学的検討を行った.P53蛋白陽性細胞率(LI),PCNA-LI,p21-LIと原発部位,T分類,N分類,Stage分類との間に有意差は認められなかった.P53-LIとPCNA-LIは浸潤様式が高度になるにつれて増加していたが,p21-LIは減少していた.さらに,浸潤様式4D型のP53-LIは,各浸潤様式のP53-LIとの間に有意差が認められた.各蛋白の相関関係においては,P53-LIが高値の症例ではPCNA-LIも高値を示し,統計学的に相関が認められた.また,P53-LIが高値の症例ではp21-LIは低値を示した.所属リンパ節転移に転移を認めた症例では,P53-LIが有意に高値を示していた.P53-LIが25%以下の症例の5年生存率は,P53-LIが25%以上の症例と比べ,有意に高かった.P53は,口腔扁平上皮癌の増殖と浸潤に重要な役割を果たしていることが示唆された...

  19. Un targeted and delayed mutation in F1 mice born to irradiated spermatozoa and the p53 dependent genomic cross-talk

    International Nuclear Information System (INIS)

    The mutation frequency at the maternally derived allele of a minisatellite and the pink-eyed unstable locus was found to increase in F1 mice by irradiation to spermatozoa. This suggests the presence of a cross-talk between paternally derived damaged genome and maternally derived undamaged genome. Indeed, fertilization by irradiated spermatozoa was found to suppress DNA synthesis both in sperm pronucleus and female pronucleus, confirming the genomic cross-talk. This cross-talk was found to be dependent on functional p53, indicating a novel p53 dependent S checkpoint. The p53 dependent S checkpoint operates also in mouse fibroblasts only at low doses of radiation and the role of p53 was to assist ATM dependent phosphorylation of PCNA which then suppressed DNA replication fork progression. p53 dependent genomic cross-talk is likely to play a role in un targeted and delayed mutation since somatic reversion in F1 mice of the maternally derived pink-eyed unstable allele was not elevated by sperm irradiation when mice were of the p53-/- genotype

  20. The emerging role of p53 in exercise metabolism.

    Science.gov (United States)

    Bartlett, Jonathan D; Close, Graeme L; Drust, Barry; Morton, James P

    2014-03-01

    The major tumour suppressor protein, p53, is one of the most well-studied proteins in cell biology. Often referred to as the Guardian of the Genome, the list of known functions of p53 include regulatory roles in cell cycle arrest, apoptosis, angiogenesis, DNA repair and cell senescence. More recently, p53 has been implicated as a key molecular player regulating substrate metabolism and exercise-induced mitochondrial biogenesis in skeletal muscle. In this context, the study of p53 therefore has obvious implications for both human health and performance, given that impaired mitochondrial content and function is associated with the pathology of many metabolic disorders such as ageing, type 2 diabetes, obesity and cancer, as well as reduced exercise performance. Studies on p53 knockout (KO) mice collectively demonstrate that ablation of p53 content reduces intermyofibrillar (IMF) and subsarcolemmal (SS) mitochondrial yield, reduces cytochrome c oxidase (COX) activity and peroxisome proliferator-activated receptor gamma co-activator 1-α protein content whilst also reducing mitochondrial respiration and increasing reactive oxygen species production during state 3 respiration in IMF mitochondria. Additionally, p53 KO mice exhibit marked reductions in exercise capacity (in the magnitude of 50 %) during fatiguing swimming, treadmill running and electrical stimulation protocols. p53 may regulate contractile-induced increases in mitochondrial content via modulating mitochondrial transcription factor A (Tfam) content and/or activity, given that p53 KO mice display reduced skeletal muscle mitochondrial DNA, Tfam messenger RNA and protein levels. Furthermore, upon muscle contraction, p53 is phosphorylated on serine 15 and subsequently translocates to the mitochondria where it forms a complex with Tfam to modulate expression of mitochondrial-encoded subunits of the COX complex. In human skeletal muscle, the exercise-induced phosphorylation of p53(Ser15) is enhanced in conditions

  1. Resuscitation of wild-type p53 expression by disrupting ceramide glycosylation: a novel approach to target mutant p53 tumors

    OpenAIRE

    Liu, Yong-Yu

    2011-01-01

    Mutant p53 is frequently detected in cancers lose of its ability in tumor suppression and gain of function in promoting tumor progression. Restoration of p53 functions by replacement of wild-type p53 and inhibition of its degradation or increment of its transcriptional activity has been applied in prevention and treatment of cancers. Recent evidence indicates that disrupting ceramide glycosylation can resuscitate wild-type p53 expression and p53-dependent apoptosis in mutant p53 tumors. Actin...

  2. Dual Roles of MDM2 in the Regulation of p53: Ubiquitination Dependent and Ubiquitination Independent Mechanisms of MDM2 Repression of p53 Activity

    OpenAIRE

    Shi, Dingding; Gu, Wei

    2012-01-01

    MDM2 oncogenic protein is the principal cellular antagonist of the p53 tumor suppresser gene. p53 activity needs exquisite control to elicit appropriate responses to differential cellular stress conditions. p53 becomes stabilized and active upon various types of stresses. However, too much p53 is not beneficial to cells and causes lethality. At the steady state, p53 activity needs to be leashed for cell survival. Early studies suggested that the MDM2 oncoprotein negatively regulates p53 activ...

  3. p53-dependent delayed effects of radiation vary according to time of irradiation of p53+/- mice

    International Nuclear Information System (INIS)

    We previously reported that in p53 +/- mice that had been given a whole-body dose of 3 Gy at 8 weeks of age, p53-dependent delayed effects of radiation, as manifested in T-cell receptor (TCR) variant fractions (VF) instability in mouse splenocytes, were biphasic, namely, induction of TCR-VF mutation reappeared at 44 weeks. The manifestation of the delayed effects and the measures of biological markers varied according to the timing of irradiation. We also reported that the decrease in function of the p53 gene was related to the effects of a delayed mutation. In the present study, we investigated the functions and mutations of the p53 gene in old age for p53 +/- mice following irradiation at various ages. p53 +/- mice were given a whole-body dose of 3 Gy at 8, 28 or 40 weeks of age. There were significant differences for all variables tested at 8 weeks of age. This was similarly the case for mice irradiated at 28 weeks of age, in which there were also significant differences in TCR VF and the percentage of apoptosis. In mice irradiated at 40 weeks of age, there were significant differences for all considered variables except for the p53 allele. We demonstrated that the different patterns of delayed mutation of the p53 gene at 56 weeks of age depended on the age at which mice had undergone 3-Gy whole-body irradiation. Our conclusions are limited to variation in p53-dependent delayed effects according to the time of irradiation. (author)

  4. Dynamics of Delayed p53 Mutations in Mice Given Whole-Body Irradiation at 8 Weeks

    International Nuclear Information System (INIS)

    Purpose: Ionizing irradiation might induce delayed genotoxic effects in a p53-dependent manner. However, a few reports have shown a p53 mutation as a delayed effect of radiation. In this study, we investigated the p53 gene mutation by the translocation frequency in chromosome 11, loss of p53 alleles, p53 gene methylation, p53 nucleotide sequence, and p53 protein expression/phosphorylation in p53+/+ and p53+/- mice after irradiation at a young age. Methods and Materials: p53+/+ and p53+/- mice were exposed to 3 Gy of whole-body irradiation at 8 weeks of age. Chromosome instability was evaluated by fluorescence in situ hybridization analysis. p53 allele loss was evaluated by polymerase chain reaction, and p53 methylation was evaluated by methylation-specific polymerase chain reaction. p53 sequence analysis was performed. p53 protein expression was evaluated by Western blotting. Results: The translocation frequency in chromosome 11 showed a delayed increase after irradiation. In old irradiated mice, the number of mice that showed p53 allele loss and p53 methylation increased compared to these numbers in old non-irradiated mice. In two old irradiated p53+/- mice, the p53 sequence showed heteromutation. In old irradiated mice, the p53 and phospho-p53 protein expressions decreased compared to old non-irradiated mice. Conclusion: We concluded that irradiation at a young age induced delayed p53 mutations and p53 protein suppression.

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

    International Nuclear Information System (INIS)

    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. G1 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

  6. Mechanisms of p53-mediated mitochondrial membrane permeabilization

    Institute of Scientific and Technical Information of China (English)

    Eugenia Morselli; Lorenzo Galluzzi; Guido Kroemer

    2008-01-01

    @@ The p53 protein is mutated or inactivated in more than 50% of human cancers, underscoring its cardinal importance as an oncosuppressor, p53 is expressed in all nucleated cells and can be activated by a plethora of post-transcriptional modifications (in particular by the phosphorylation of critical serine residues), as well as by the inhibition of its degradation (mainly mediated by the E3 ubiquitin ligase MDM2).

  7. Targeting p53 for Novel Anticancer Therapy1

    OpenAIRE

    Wang, Zhen; Sun, Yi

    2010-01-01

    Carcinogenesis is a multistage process, involving oncogene activation and tumor suppressor gene inactivation as well as complex interactions between tumor and host tissues, leading ultimately to an aggressive metastatic phenotype. Among many genetic lesions, mutational inactivation of p53 tumor suppressor, the “guardian of the genome,” is the most frequent event found in 50% of human cancers. p53 plays a critical role in tumor suppression mainly by inducing growth arrest, apoptosis, and senes...

  8. p53 aerobics: the major tumor suppressor fuels your workout.

    Science.gov (United States)

    Kruse, Jan-Philipp; Gu, Wei

    2006-07-01

    In addition to its role as the central regulator of the cellular stress response, p53 can regulate aerobic respiration via the novel transcriptional target SCO2, a critical regulator of the cytochrome c oxidase complex (Matoba et al., 2006). Loss of p53 results in decreased oxygen consumption and aerobic respiration and promotes a switch to glycolysis, thereby reducing endurance during physical exercise. PMID:16814724

  9. UHRF2, another E3 ubiquitin ligase for p53

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Lu; Wang, Xiaohui; Jin, Fangmin; Yang, Yan; Qian, Guanhua [Department of Cell Biology and Medical Genetics, Chongqing Medical University, Chongqing (China); Duan, Changzhu, E-mail: duanchzhu@cqmu.edu.cn [Key Laboratory of Clinical Laboratory Diagnostics of Ministry of Education, Faculty of Laboratory Medicine, Chongqing Medical University, Chongqing (China); Department of Cell Biology and Medical Genetics, Chongqing Medical University, Chongqing (China)

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer UHRF2 associates with p53 in vivo and in vitro. Black-Right-Pointing-Pointer UHRF2 interacts with p53 through its SRA/YDG domain. Black-Right-Pointing-Pointer UHRF2 ubiquitinates p53 in vivo and in vitro. -- Abstract: UHRF2, ubiquitin-like with PHD and ring finger domains 2, is a nuclear E3 ubiquitin ligase, which is involved in cell cycle and epigenetic regulation. UHRF2 interacts with multiple cell cycle proteins, including cyclins (A2, B1, D1, and E1), CDK2, and pRb; moreover, UHRF2 could ubiquitinate cyclin D1 and cyclin E1. Also, UHRF2 has been shown to be implicated in epigenetic regulation by associating with DNMTs, G9a, HDAC1, H3K9me2/3 and hemi-methylated DNA. We found that UHRF2 associates with tumor suppressor protein p53, and p53 is ubiquitinated by UHRF2 in vivo and in vitro. Given that both UHRF2 and p53 are involved in cell cycle regulation, this study may suggest a novel signaling pathway on cell proliferation.

  10. Expression of p53 protein in pituitary adenomas

    Directory of Open Access Journals (Sweden)

    Oliveira M.C.

    2002-01-01

    Full Text Available Inactivating mutations of TP53, a tumor suppressor gene, are associated with abnormal cell proliferation. Although p53 expression is common in many human malignancies, p53 protein has seldom been evaluated in pituitary tumors. When detected, the percentage of p53-positive cells is low, and, in general, it is exclusive for invasive lesions. The aim of the present study was to use immunohistochemistry to determine the presence of p53 protein in pituitary adenomas from tumor samples of 163 surgeries performed in 148 patients (40% male, 60% female. In 35% of the cases the adenoma was nonfunctional, while in the others it was associated with PRL, GH and/or ACTH endocrine hypersecretion syndrome. Macroadenomas were observed in 83.2% of the cases with available neuroimage evaluation, of which 28% invaded the cavernous, sphenoid and/or ethmoidal sinus, bone, third ventricle or subfrontal lobe. p53 protein was detected in 2/148 patients (1.3%. Immunohistochemistry was positive for PRL and GH in these cases. Due to the high percentage of invasive pituitary adenomas found in our study, the low frequency of p53 detection suggests that it is inadequate as a routine marker for aggressiveness and as a predictive factor of tumor behavior.

  11. Estradiol induces functional inactivation of p53 by intracellular redistribution.

    Science.gov (United States)

    Molinari, A M; Bontempo, P; Schiavone, E M; Tortora, V; Verdicchio, M A; Napolitano, M; Nola, E; Moncharmont, B; Medici, N; Nigro, V; Armetta, I; Abbondanza, C; Puca, G A

    2000-05-15

    Estrogen treatment of MCF-7 cells grown in serum-free medium induced a modification of the intracellular distribution of p53 protein. Western blot analysis and immunofluorescence staining showed that p53 was localized in the nucleus of untreated cell and that after 48 h of hormone treatment, it was mostly localized in the cytoplasm. This effect was blocked by the antiestrogen ICI182,780. Intracellular redistribution of p53 was correlated to a reduced expression of the WAF1/CIP1 gene product and to the presence of degradation fragments of p53 in the cytosol. Estradiol treatment prevented the growth inhibition induced by oligonucleotide transfection, simulating DNA damage. This observation indicated that the wild-type p53 gene product present in the MCF-7 cell could be inactivated by estradiol through nuclear exclusion to permit the cyclin-dependent phosphorylation events leading to the G1-S transition. In addition, the estradiol-induced inactivation of p53 could be involved in the tumorigenesis of estrogen-dependent neoplasm. PMID:10825127

  12. EXPRESSION OF SV40 Tag AND FORMATION Tag-p53 AND Tag-Rb COMPLEXES IN CHINESE BRAIN TUMORS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective: To investigate the expression of SV40 Tag andformation of Tag-p53 and Tag-Rb complexes in Chinese brain tumors. Methods: SV40 large tumor antigen (Tag) were investigated by immunoprecipitation, silver staining and Western blot in 65 cases of Chinese brain tumors and 8 cases of normal brain tissues. Tag-p53 and Tag-Rb complexes were screened by the same way in 20 and 15 Tag positive tumor tissues respectively. Results: Tag was found in all of 8 ependymomas and 2 choroid plexus papillomas, 90% (9/10) of pituitary adenomas, 73% (11/15) of astrocytomas, 70% (7/10) of meningiomas, 50% (4/8) of glioblastoma multiform, 33% (2/6) of medulloblastomas, 5 oligodendrogliomas, 1 pineocytoma and 8 normal brain tissues were negative for Tag. Tag-p53 complex was detected in all of 20 Tag positive tumors as well as Tag-Rb complex in all of 15 Tag positive tumors. Conclusion: SV40 Tag is not only expressed in human brain tumors, but also it can form specific complexes with tumor suppressors p53 and Rb. SV40 is correlated to human brain tumorigenesis. The inactivation of p53 and Rb due to the formation of Tag-p53 and Tag-Rb complexes is possibly an important mechanism in the etiopathogenesis of human brain tumors.

  13. Study of p53 protein expression levels from irradiated peripheral blood lymphocytes for biodosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcanti, M.B.; Fernandes, T.S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Amaral, A. [Universite Paris XII (UPXII) (France); Melo, J.A. [Centro de Radioterapia de Pernambuco (CERAPE), PE (Brazil); Neves, M.A.B.; Machado, C.G.F, E-mail: maribrayner@yahoo.com.br [Fundacao de Hematologia e Hemoterapia de Pernambuco, PE (Brazil)

    2005-07-01

    Biodosimetry can be defined as the investigation of radioinduced biological effects in order to correlate them with the absorbed dose. Scoring of unstable chromosomal aberrations and micronuclei, from in vitro irradiated peripheral blood lymphocytes, is commonly used for biodosimetry based on cytogenetic analysis. However, this method of analysis is time-consuming, which may represent a pitfall when fast investigation of a possible exposure to ionizing radiation (IR) is needed. The interaction of IR with the living cell can cause injuries in the DNA molecules. However, normal cells possess mechanisms of repair that are capable to correct those damages. During the repair process of the DNA various proteins are expressed. Among these proteins, p53 plays an important role. This protein is a transcription factor that helps in the maintenance of the genomic integrity. p53 protein is found into the cytoplasm in reduced concentrations and has a short average life. However, expression of p53 protein can be induced by DNA harmful radioinduced, which increases the concentration and the average life of this protein, making possible its detection. Thus, the correlation between the increasing of p53 expression and the irradiation may constitute a fast and reliable method of individual monitoring in cases of accidental or suspected exposures to IR. In this context, the objective of this research was to evaluate the p53 protein expression levels from lymphocytes of the human peripheral blood after in vitro irradiation. For this, samples of peripheral blood from healthy individuals were irradiated with known doses. Lymphocytes were separated on ficoll gradient by centrifugation and re-suspended at 1x 10{sub 6}/mL in RPMI medium enriched with fetal calf serum. Hence, lymphocytes were incubated in 5% CO{sub 2} at 37 deg C prior to the methodology of flow cytometry, using intranuclear antigens for the quantification of p53. In this report, the methodology performed and the results

  14. DNA damage induces phosphorylation of the amino terminus of p53

    OpenAIRE

    Siliciano, Janet D.; Canman, Christine E.; Taya, Yoichi; Sakaguchi, Kazuyasu; Appella, Ettore; Kastan, Michael B.

    1997-01-01

    Data are presented demonstrating that DNA damage leads to specific post-translational modifications of p53 protein. Using two-dimensional peptide mapping of in vivo radiolabeled p53 tryptic phosphopeptides, recombinant truncated p53 protein, and synthetic p53 tryptic peptides, a unique p53 phosphopeptide was identified after exposure of ML-1 cells to ionizing irradiation. This peptide represents the first 24 amino acids of p53 and contains three phosphorylated serine residues. A specific p53 ...

  15. Association of p53 codon 72 polymorphism with liver metastases of colorectal cancers positive for p53 overexpression

    Institute of Scientific and Technical Information of China (English)

    Zhong-zheng ZHU; Bing LIU; Ai-zhong WANG; Hang-ruo JIA; Xia-xiang JIN; Xiang-lei HE; Li-fang HOU; Guan-shan ZHU

    2008-01-01

    Objective: To evaluate the association between p53 codon 72 polymorphism (R72P) and the risk of colorectal liver metastases. Methods: The p53 R72P genotype was identified by polymerase chain reaction-restriction fi'agment length poly-morphism (PCR-RFLP) method in 78 consecutive colorectal cancer patients with liver metastases and 214 age- and sex-matched cases with nonmetastatic colorectai cancer. Results: The R allele of the p53 R72P polymorphism was more frequently found in metastatic cases than in nonmetastatic cases (P=0.075). Carriers of the 72R allele had a 2.25-fold (95% CI (confidence inter-val)=1.05~4.83) increased risk of liver metastases. On the stratification analysis, 72R-carrying genotype conferred a 3.46-fold (95% CI=1.02~11.72) and a 1.05-fold (95% CI=0.36~3.08) increased risk of liver metastases for p53 overexpression-positive and negative colorectal cancers, respectively. Conclusion: These results demonstrate for the first time that the 72R allele of the p53 polymorphism has an increased risk for liver metastases in colorectal cancers positive for p53 overexpression.

  16. A surrogate p53 reporter in Drosophila reveals the interaction of eIF4E and p53

    International Nuclear Information System (INIS)

    eIF4E promotes translation upon binding the mRNA 5'cap and it is required for cell proliferation. p53 is a proapoptotic protein which is activated in response to DNA damage. There is evidence that suggests that eIF4E and p53 are connected in a mechanism that regulates their function. We propose a model for that such a mechanism to explain the equilibrium between apoptosis and cell proliferation. Our data shows a correlation between the overexpression of eIF4E and the suppression of apoptosis triggered by the overexpression of p53 in Drosophila imaginal discs. We also studied a reporter transgene which expresses GFP in response to p53 activation by gamma radiation. We could confirm that this p53 surrogate works in imaginal discs as well as in embryos. This provided us a tool to quantify the effect on the GFP signal by overexpression of eIF4E to confirm how these two proteins could interact in vivo. Our results suggest that p53 and eIF4E are indeed in an equilibrium that decides if a cell shall proliferate or die. (authors)

  17. miR-605 joins p53 network to form a p53:miR-605:Mdm2 positive feedback loop in response to stress

    OpenAIRE

    Xiao, Jiening; Lin, Huixian; Luo, Xiaobin; Luo, Xiaoyan; Wang, Zhiguo

    2011-01-01

    Mdm2, a transcriptional target of p53, promotes p53 degradation in a well-established negative feedback loop. Here, microRNA miR-605 is found to break this loop: being induced by p53 in response to stress, and downregulating Mdm2 to promote robust p53 expression.

  18. Modulation of p53β and p53γ expression by regulating the alternative splicing of TP53 gene modifies cellular response.

    Science.gov (United States)

    Marcel, V; Fernandes, K; Terrier, O; Lane, D P; Bourdon, J-C

    2014-09-01

    In addition to the tumor suppressor p53 protein, also termed p53α, the TP53 gene produces p53β and p53γ through alternative splicing of exons 9β and 9γ located within TP53 intron 9. Here we report that both TG003, a specific inhibitor of Cdc2-like kinases (Clk) that regulates the alternative splicing pre-mRNA pathway, and knockdown of SFRS1 increase expression of endogenous p53β and p53γ at mRNA and protein levels. Development of a TP53 intron 9 minigene shows that TG003 treatment and knockdown of SFRS1 promote inclusion of TP53 exons 9β/9γ. In a series of 85 primary breast tumors, a significant association was observed between expression of SFRS1 and α variant, supporting our experimental data. Using siRNA specifically targeting exons 9β/9γ, we demonstrate that cell growth can be driven by modulating p53β and p53γ expression in an opposite manner, depending on the cellular context. In MCF7 cells, p53β and p53γ promote apoptosis, thus inhibiting cell growth. By transient transfection, we show that p53β enhanced p53α transcriptional activity on the p21 and Bax promoters, while p53γ increased p53α transcriptional activity on the Bax promoter only. Moreover, p53β and p53γ co-immunoprecipitate with p53α only in the presence of p53-responsive promoter. Interestingly, although p53β and p53γ promote apoptosis in MCF7 cells, p53β and p53γ maintain cell growth in response to TG003 in a p53α-dependent manner. The dual activities of p53β and p53γ isoforms observed in non-treated and TG003-treated cells may result from the impact of TG003 on both expression and activities of p53 isoforms. Overall, our data suggest that p53β and p53γ regulate cellular response to modulation of alternative splicing pre-mRNA pathway by a small drug inhibitor. The development of novel drugs targeting alternative splicing process could be used as a novel therapeutic approach in human cancers. PMID:24926616

  19. Restoring expression of wild-type p53 suppresses tumor growth but does not cause tumor regression in mice with a p53 missense mutation

    OpenAIRE

    Wang, Yongxing; Suh, Young-Ah; Fuller, Maren Y.; Jackson, James G.; Xiong, Shunbin; Terzian, Tamara; Quintás-Cardama, Alfonso; Bankson, James A.; El-Naggar, Adel K; Lozano, Guillermina

    2011-01-01

    The transcription factor p53 is a tumor suppressor. As such, the P53 gene is frequently altered in human cancers. However, over 80% of the P53 mutations found in human cancers are missense mutations that lead to expression of mutant proteins that not only lack p53 transcriptional activity but exhibit new functions as well. Recent studies show that restoration of p53 expression leads to tumor regression in mice carrying p53 deletions. However, the therapeutic efficacy of restoring p53 expressi...

  20. Small-Molecule Inhibitors of the MDM2-p53 Protein-Protein Interaction to Reactivate p53 Function: A Novel Approach for Cancer Therapy

    OpenAIRE

    Shangary, Sanjeev; Wang, Shaomeng

    2009-01-01

    Tumor suppressor p53 is an attractive cancer therapeutic target because it can be functionally activated to eradicate tumors. Direct gene alterations in p53 or interaction between p53 and MDM2 proteins are two alternative mechanisms for the inactivation of p53 function. Designing small molecules to block the MDM2-p53 interaction and reactivate the p53 function is a promising therapeutic strategy for the treatment of cancers retaining wild-type p53. This review will highlight recent advances i...

  1. Suppression of Id2, a member of the inhibitor of differentiation family and a target of mutant p53, is required for mutant p53 gain of function

    OpenAIRE

    Yan, Wensheng; Liu, Gang; Scoumanne, Ariane; Chen, Xinbin

    2008-01-01

    Over-expression of mutant p53 is a common theme in human tumors, suggesting a tumor-promoting gain of function for mutant p53. To elucidate whether and how mutant p53 acquires its gain of function, mutant p53 is inducibly knocked down in SW480 colon cancer cell line, which contains mutant p53(R273H/P309S), and MIA-PaCa-2 pancreatic cancer cell line, which contains mutant p53(R248W). We found that knockdown of mutant p53 markedly inhibits cell proliferation. In addition, knockdown of mutant p5...

  2. EXPRESSION OF p16 AND p53 IN GASTRIC CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Objective:To investigate the clinical significance of p53 and p16 expression in gastric carcinoma with special reference to the prognosis.Methods:One hundred and fifty-two patients with gastric carcinoma undergoing operation in our hospital between 1991 and 1998 were evaluated for expression of p53 and p16 in formalin-fixed and paraffin-embedded tumor tissue utilizing Avidin-Biotin immunohistochemistry techniques. Statistical correlations with stage, histological type, differentiation degree, location, size, and overall survival were done. The Cox proportional hazard model was also performed to evaluate which factors had an independent prognostic value.Results:In 152 cases of resected gastric cancer, 110 (72.4%) were p16 positive and 49 (32.2%) showed p53 overexpression. Differences were observed in the frequency of p16 positivity with respect to age, gender and tumor size. The frequency of p53 positivity cells in well-differentiated tumors was significantly higher than that in poorly differentiated tumors (41.9% vs. 25.6%; P= 0.034). In a multivariate analysis, tumor TNM stage, perioperation chemotherapy and the expression of p16 were independent prognostic factors in gastric cancer.Conclusions:The results of the current study suggest that expression of p16 may be a useful prognostic factor for patients with gastric carcinoma, but the expression of p53 as detected by immunohistochemistry were of no value in predicting the prognosis of patients with gastric carcinoma independently.

  3. Sequence-dependent sliding kinetics of p53

    Science.gov (United States)

    Leith, Jason; Tafvizi, Anahita; Huang, Fang; Uspal, William; Doyle, Patrick; Fersht, Alan; Mirny, Leonid; van Oijen, Antoine

    2012-02-01

    Theoretical work has long proposed that one-dimensional sliding along DNA while simultaneously reading its sequence can accelerate transcription factors' (TFs) search for their target sites. More recently, functional sliding has been shown to require TFs to possess at least two DNA-binding modes. The tumor suppressor p53 has been directly observed to slide on DNA, and structural and single-molecule studies have provided evidence for a two-mode model for the protein. If the model is in fact applicable to p53, then the requirement that TFs read while they slide implies that p53's mobility on DNA should be affected by non-cognate sites and thus that its diffusivity should be generally sequence-dependent. Here we confirm this prediction with single-molecule microscopy measurements of p53's local diffusivity on non-cognate DNA. We show how a two-mode model accurately predicts the variation in local diffusivity while a single-mode model does not. Our work provides evidence that p53's sliding is indeed functional and suggests that the timing and efficiency of its activating and repressing transcription can depend on its non-cognate binding properties and its ability to change between multiple modes of binding, in addition to the much better-studied effects of cognate-site binding.

  4. p53 Prevents Entry into Mitosis with Uncapped Telomeres

    Science.gov (United States)

    Thanasoula, Maria; Escandell, Jose Miguel; Martinez, Paula; Badie, Sophie; Muñoz, Purificacion; Blasco, María A.; Tarsounas, Madalena

    2016-01-01

    Summary Telomeres are protected by capping structures consisting of core protein complexes that bind with sequence specificity to telomeric DNA (reviewed in [1]). In their absence, telomeres trigger a DNA damage response, materialized in accumulation at the telomere of damage response proteins, e.g., phosphorylated histone H2AX (γH2AX), into telomere-dysfunction-induced foci [2, 3]. Telomere uncapping occurs transiently in every cell cycle in G2 [4], following DNA replication, but little is known about how protective structures are reassembled or whether this process is controlled by the cell-cycle surveillance machinery. Here, we report that telomere capping is monitored at the G2/M transition by the p53/p21 damage response pathway. Unlike their wild-type counterparts, human and mouse cells lacking p53 or p21 progress into mitosis prematurely with persisting uncapped telomeres. Furthermore, artificially uncapped telomeres delay mitotic entry in a p53- and p21-dependent manner. Uncapped telomeres that persist in mitotic p53-deficient cells are shorter than average and religate to generate end-to-end fusions. These results suggest that a p53-dependent pathway monitors telomere capping after DNA replication and delays G2/M progression in the presence of unprotected telomeres. This mechanism maintains a cell-cycle stage conducive for capping reactions and prevents progression into stages during which uncapped telomeres are prone to deleterious end fusions. PMID:20226664

  5. 胃癌患者血清P53蛋白与抗体检测的比较%Detection of serum P53 protein and P53 antibody in patients with gastric carcinoma*

    Institute of Scientific and Technical Information of China (English)

    刘辉琦; 刘慧; 刘杰; 王生兰

    2011-01-01

    目的 比较胃癌患者血清P53蛋白与抗体检测的敏感性.方法 采用间接ELISA法检测胃癌患者血清P53抗体,夹心ELISA法检测胃癌患者血清P53蛋白.结果 胃癌患者血清P53蛋白阳性率为14.0%,抗体阳性率为32.0%,二者差异有统计学意义(P<0.05).结论 胃癌患者血清P53抗体的检测比P53蛋白的检测更敏感.%Objective To compare the detection sensitivity of serum P53 protein and P53 antibody in patients with gastric carci noma. Methods Indirect ELISA was adopted to detect serum P53 antibody,and double antibodies sandwich ELISA technique was used to measure serum P53 protein. Results The positive rates of serum P53 protein and P53 antibody were 14.0% and 32.0% re spectively,which were with significant difference. Conclusion P53 antibody detection could be more sensitive than P53 protein in patients with gastric carcinoma.

  6. Mdm2’s Dilemma: To Degrade or To Translate p53?

    OpenAIRE

    Hamard, Pierre-Jacques; Manfredi, James J

    2012-01-01

    In this issue of Cancer Cell, Gajjar et al. provide insight into how Mdm2 can both inhibit and enhance p53 activity. In the basal setting, Mdm2 binds p53 and promotes p53 degradation. Under stress conditions, ATM-dependent phosphorylation of Mdm2 results in its recruitment to p53 mRNA, thereby stimulating p53 translation.

  7. TRAIP is a PCNA-binding ubiquitin ligase that protects genome stability after replication stress

    DEFF Research Database (Denmark)

    Hoffmann, Saskia; Smedegaard, Stine; Nakamura, Kyosuke;

    2016-01-01

    Cellular genomes are highly vulnerable to perturbations to chromosomal DNA replication. Proliferating cell nuclear antigen (PCNA), the processivity factor for DNA replication, plays a central role as a platform for recruitment of genome surveillance and DNA repair factors to replication forks......, allowing cells to mitigate the threats to genome stability posed by replication stress. We identify the E3 ubiquitin ligase TRAIP as a new factor at active and stressed replication forks that directly interacts with PCNA via a conserved PCNA-interacting peptide (PIP) box motif. We show that TRAIP promotes...... chromosomal instability and decreased cell survival after replication stress. These findings establish TRAIP as a PCNA-binding ubiquitin ligase with an important role in protecting genome integrity after obstacles to DNA replication....

  8. L-GILZ binds p53 and MDM2 and suppresses tumor growth through p53 activation in human cancer cells

    OpenAIRE

    Ayroldi, E; Petrillo, M G; Bastianelli, A; Marchetti, M C; Ronchetti, S; Nocentini, G; Ricciotti, L; Cannarile, L; Riccardi, C

    2014-01-01

    The transcription factor p53 regulates the expression of genes crucial for biological processes such as cell proliferation, metabolism, cell repair, senescence and apoptosis. Activation of p53 also suppresses neoplastic transformations, thereby inhibiting the growth of mutated and/or damaged cells. p53-binding proteins, such as mouse double minute 2 homolog (MDM2), inhibit p53 activation and thus regulate p53-mediated stress responses. Here, we found that long glucocorticoid-induced leucine z...

  9. p53-Dependent suppression of genome instability in germ cells

    Energy Technology Data Exchange (ETDEWEB)

    Otozai, Shinji [Department of Otorhinolaryngology and Head and Neck Surgery, Osaka University School of Medicine, Osaka 565-0871 (Japan); Ishikawa-Fujiwara, Tomoko [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Oda, Shoji [Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562 (Japan); Kamei, Yasuhiro [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ryo, Haruko [Nomura Project, National Institute of Biomedical Innovation, Osaka 565-0085 (Japan); Sato, Ayuko [Department of Pathology, Hyogo College of Medicine, Hyogo 663-8501 (Japan); Nomura, Taisei [Nomura Project, National Institute of Biomedical Innovation, Osaka 565-0085 (Japan); Mitani, Hiroshi [Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562 (Japan); Tsujimura, Tohru [Department of Pathology, Hyogo College of Medicine, Hyogo 663-8501 (Japan); Inohara, Hidenori [Department of Otorhinolaryngology and Head and Neck Surgery, Osaka University School of Medicine, Osaka 565-0871 (Japan); Todo, Takeshi, E-mail: todo@radbio.med.osaka-u.ac.jp [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-02-15

    Highlights: • Radiation-induced microsatellite instability (MSI) was investigated in medaka fish. • msh2{sup −/−} fish had a high frequency of spontaneous MSI. • p53{sup −/−} fish had a high frequency of radiation-induced MSI. • p53 and msh2 suppress MSI by different pathways: mismatch removal and apoptosis. - Abstract: Radiation increases mutation frequencies at tandem repeat loci. Germline mutations in γ-ray-irradiated medaka fish (Oryzias latipes) were studied, focusing on the microsatellite loci. Mismatch-repair genes suppress microsatellite mutation by directly removing altered sequences at the nucleotide level, whereas the p53 gene suppresses genetic alterations by eliminating damaged cells. The contribution of these two defense mechanisms to radiation-induced microsatellite instability was addressed. The spontaneous mutation frequency was significantly higher in msh2{sup −/−} males than in wild-type fish, whereas there was no difference in the frequency of radiation-induced mutations between msh2{sup −/−} and wild-type fish. By contrast, irradiated p53{sup −/−} fish exhibited markedly increased mutation frequencies, whereas their spontaneous mutation frequency was the same as that of wild-type fish. In the spermatogonia of the testis, radiation induced a high level of apoptosis both in wild-type and msh2{sup −/−} fish, but negligible levels in p53{sup −/−} fish. The results demonstrate that the msh2 and p53 genes protect genome integrity against spontaneous and radiation-induced mutation by two different pathways: direct removal of mismatches and elimination of damaged cells.

  10. p53-Dependent suppression of genome instability in germ cells

    International Nuclear Information System (INIS)

    Highlights: • Radiation-induced microsatellite instability (MSI) was investigated in medaka fish. • msh2−/− fish had a high frequency of spontaneous MSI. • p53−/− fish had a high frequency of radiation-induced MSI. • p53 and msh2 suppress MSI by different pathways: mismatch removal and apoptosis. - Abstract: Radiation increases mutation frequencies at tandem repeat loci. Germline mutations in γ-ray-irradiated medaka fish (Oryzias latipes) were studied, focusing on the microsatellite loci. Mismatch-repair genes suppress microsatellite mutation by directly removing altered sequences at the nucleotide level, whereas the p53 gene suppresses genetic alterations by eliminating damaged cells. The contribution of these two defense mechanisms to radiation-induced microsatellite instability was addressed. The spontaneous mutation frequency was significantly higher in msh2−/− males than in wild-type fish, whereas there was no difference in the frequency of radiation-induced mutations between msh2−/− and wild-type fish. By contrast, irradiated p53−/− fish exhibited markedly increased mutation frequencies, whereas their spontaneous mutation frequency was the same as that of wild-type fish. In the spermatogonia of the testis, radiation induced a high level of apoptosis both in wild-type and msh2−/− fish, but negligible levels in p53−/− fish. The results demonstrate that the msh2 and p53 genes protect genome integrity against spontaneous and radiation-induced mutation by two different pathways: direct removal of mismatches and elimination of damaged cells

  11. p53 Family: Role of Protein Isoforms in Human Cancer

    Directory of Open Access Journals (Sweden)

    Jinxiong Wei

    2012-01-01

    Full Text Available TP53, TP63, and TP73 genes comprise the p53 family. Each gene produces protein isoforms through multiple mechanisms including extensive alternative mRNA splicing. Accumulating evidence shows that these isoforms play a critical role in the regulation of many biological processes in normal cells. Their abnormal expression contributes to tumorigenesis and has a profound effect on tumor response to curative therapy. This paper is an overview of isoform diversity in the p53 family and its role in cancer.

  12. Tumor hypoxia, p53, and prognosis in cervical cancers

    International Nuclear Information System (INIS)

    Background: The p53 protein is involved in the regulation of initiation of apoptosis. In vitro, p53-deficient cells do not respond to hypoxia with apoptosis as do p53-normal cells, and this may lead to a relative growth advantage of cells without a functioning p53 under hypoxia. On the basis of this hypothesis, a selection of cells with a functionally inactive p53 may occur in hypoxic tumors. The development of uterine cervical carcinomas is closely associated with infections of human papilloma viruses, which may cause a degradation of the tumor suppressor gene p53, resulting in a restriction of apoptosis. Thus, cervical cancers have often a functionally inactive p53. The purpose of our clinical study was therefore to investigate the association between p53, hypoxia, and prognosis in cervical cancers in which the oxygenation status can be determined by clinical methods. Material and Methods: Seventy patients with locally advanced squamous cell cervical cancer Stages IIB (n=14), IIIB (n=49), and IVA (n=7) were investigated in the period from 1996 through 1999. All were treated with definitive radiotherapy with curative intent by a combination of external radiotherapy plus high-dose-rate afterloading. Before therapy, tumor oxygenation was measured with a needle probe polarographically using the Eppendorf histograph. Hypoxic tumors were defined as those with pO2 measurements below 5 mm Hg (HF5). Pretreatment biopsies were taken and analyzed immunohistologically for p53 protein expression with the DO-7 antibody. The DNA index was measured by flow cytometry. The statistical data analysis was done with SPSS 9.0 for Windows. Results: The 3-year overall survival was 55% for the whole group of patients. Clinical prognostic factors in a multivariate analysis were pretreatment hemoglobin level (3-year survival 62% for patients with a pretreatment hemoglobin ≥11 g/dl vs. 27% for hemoglobin <11 g/dl, p=0.006) and FIGO stage (Stage IIB: 65%; Stage IIIB: 60%; Stage IVA: 29%, p

  13. Accumulation of p21 proteins at DNA damage sites independent of p53 and core NHEJ factors following irradiation

    International Nuclear Information System (INIS)

    Highlights: → p21 accumulated rapidly at laser-irradiated sites via its C-terminal region. → p21 colocalized with the DSB marker γ-H2AX and the DSB sensor Ku80. → Accumulation of p21 is dependent on PCNA, but not p53 and the NHEJ core factors. → Accumulation activity of p21 was conserved among human and animal cells. → p21 is a useful tool as a detection marker of DNA damaged sites. -- Abstract: The cyclin-dependent kinase (CDK) inhibitor p21 plays key roles in p53-dependent DNA-damage responses, i.e., cell cycle checkpoints, senescence, or apoptosis. p21 might also play a role in DNA repair. p21 foci arise at heavy-ion-irradiated DNA-double-strand break (DSB) sites, which are mainly repaired by nonhomologous DNA-end-joining (NHEJ). However, no mechanisms of p21 accumulation at double-strand break (DSB) sites have been clarified in detail. Recent works indicate that Ku70 and Ku80 are essential for the accumulation of other NHEJ core factors, e.g., DNA-PKcs, XRCC4 and XLF, and other DNA damage response factors, e.g., BRCA1. Here, we show that p21 foci arise at laser-irradiated sites in cells from various tissues from various species. The accumulation of EGFP-p21 was detected in not only normal cells, but also transformed or cancer cells. Our results also showed that EGFP-p21 accumulated rapidly at irradiated sites, and colocalized with the DSB marker γ-H2AX and with the DSB sensor protein Ku80. On the other hand, the accumulation occurred in Ku70-, Ku80-, or DNA-PKcs-deficient cell lines and in human papillomavirus 18-positive cells, whereas the p21 mutant without the PCNA-binding region (EGFP-p21(1-146)) failed to accumulate at the irradiated sites. These findings suggest that the accumulation of p21, but not functional p53 and the NHEJ core factors, is dependent on PCNA. These findings also suggest that the accumulation activity of p21 at DNA damaged sites is conserved among human and animal cells, and p21 is a useful tool as a detection marker of DNA

  14. Accumulation of p21 proteins at DNA damage sites independent of p53 and core NHEJ factors following irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Manabu, E-mail: m_koike@nirs.go.jp [DNA Repair Gene Res., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yutoku, Yasutomo [DNA Repair Gene Res., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Graduate School of Science, Chiba University, Chiba 263-8522 (Japan); Koike, Aki [DNA Repair Gene Res., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2011-08-19

    Highlights: {yields} p21 accumulated rapidly at laser-irradiated sites via its C-terminal region. {yields} p21 colocalized with the DSB marker {gamma}-H2AX and the DSB sensor Ku80. {yields} Accumulation of p21 is dependent on PCNA, but not p53 and the NHEJ core factors. {yields} Accumulation activity of p21 was conserved among human and animal cells. {yields} p21 is a useful tool as a detection marker of DNA damaged sites. -- Abstract: The cyclin-dependent kinase (CDK) inhibitor p21 plays key roles in p53-dependent DNA-damage responses, i.e., cell cycle checkpoints, senescence, or apoptosis. p21 might also play a role in DNA repair. p21 foci arise at heavy-ion-irradiated DNA-double-strand break (DSB) sites, which are mainly repaired by nonhomologous DNA-end-joining (NHEJ). However, no mechanisms of p21 accumulation at double-strand break (DSB) sites have been clarified in detail. Recent works indicate that Ku70 and Ku80 are essential for the accumulation of other NHEJ core factors, e.g., DNA-PKcs, XRCC4 and XLF, and other DNA damage response factors, e.g., BRCA1. Here, we show that p21 foci arise at laser-irradiated sites in cells from various tissues from various species. The accumulation of EGFP-p21 was detected in not only normal cells, but also transformed or cancer cells. Our results also showed that EGFP-p21 accumulated rapidly at irradiated sites, and colocalized with the DSB marker {gamma}-H2AX and with the DSB sensor protein Ku80. On the other hand, the accumulation occurred in Ku70-, Ku80-, or DNA-PKcs-deficient cell lines and in human papillomavirus 18-positive cells, whereas the p21 mutant without the PCNA-binding region (EGFP-p21(1-146)) failed to accumulate at the irradiated sites. These findings suggest that the accumulation of p21, but not functional p53 and the NHEJ core factors, is dependent on PCNA. These findings also suggest that the accumulation activity of p21 at DNA damaged sites is conserved among human and animal cells, and p21 is a useful

  15. Graphene-based immunosensor for electrochemical quantification of phosphorylated p53 (S15)

    International Nuclear Information System (INIS)

    Graphical abstract: A new graphene-based immunosensor for electrochemical quantification of phosphorylated p53 on serine 15 (phospho-p5315) was proposed. This easily fabricated immunosensor provides a potential tool for analysis of other biomarkers. Highlights: → A new graphene-based immunosensor for electrochemical quantification of phosphorylated p53 on serine 15 (phospho-p5315) was proposed. → Graphene served as sensor platform greatly increased detection sensitivity. → This easily fabricated immunosensor provides a potential tool for analysis of other biomarkers. - Abstract: We reported a graphene-based immunosensor for electrochemical quantification of phosphorylated p53 on serine 15 (phospho-p5315), a potential biomarker of gamma-radiation exposure. The principle is based on sandwich immunoassay and the resulting immunocomplex is formed among phospho-p53 capture antibody, phospho-p5315 antigen, biotinylated phospho-p5315 detection antibody and horseradish peroxidase (HRP)-labeled streptavidin. The introduced HRP results in an electrocatalytic response to reduction of hydrogen peroxide in the presence of thionine. Graphene served as sensor platform not only promotes electron transfer, but also increases the surface area to introduce a large amount of capture antibody, thus increasing the detection sensitivity. The experimental conditions including blocking agent, immunoreaction time and substrate concentration have been optimized. Under the optimum conditions, the increase of response current is proportional to the phospho-p5315 concentration in the range of 0.2-10 ng mL-1, with the detection limit of 0.1 ng mL-1. The developed immunosensor exhibits acceptable stability and reproducibility and the assay results for phospho-p5315 are in good correlation with the known values. This easily fabricated immunosensor provides a new promising tool for analysis of phospho-p5315 and other phosphorylated proteins.

  16. Transfection of p53-knockout mouse fibroblasts with wild-type p53 increases the thermo sensitivity and stimulates apoptosis induced by heat stress

    International Nuclear Information System (INIS)

    Purpose: The relationship between p53 functions and cellular thermo sensitivity was evaluated using murine fibroblasts transfected with either wild-type p53 or mutated p53, or those with a null p53 genotype. Methods and Materials: Cellular thermo sensitivity was determined using the clonogenic assay. Cell cycle distribution was assayed by determining DNA content using flow cytometry. Apoptosis was analyzed by detection of both apoptotic bodies and DNA fragmentation. Results: Stable transfectant with either wild-type p53 or mutated p53 was established. The transfectants with wild-type p53 were more thermo sensitive than either those with a null p53 or with mutated p53. Although heat-induced G1 cell cycle arrest was substantially observed in all transfectants, wild-type p53 enhanced and prolonged the G1 arrest; furthermore, wild-type p53 stimulated the induction of apoptosis by heat stress, whereas mutated p53 delayed it extremely. Conclusion: The p53 gene is a factor for determining cellular thermo sensitivity and wild-type p53 contributes to thermo sensitization resulting in enhancement of heat-induced apoptosis

  17. Transfection of p53-knockout mouse fibroblasts with wild-type p53 increases the thermo sensitivity and stimulates apoptosis induced by heat stress

    International Nuclear Information System (INIS)

    Purpose: The relationship between the p53 functions and cellular thermo sensitivity was evaluated using murine fibroblasts transfected with either wild-type p53 or mutated p53, or those with a null p53 genotype. Methods and Materials: Cellular thermo sensitivity was determined using the clonogenic assay. Cell cycle distribution was assayed by determining DNA content using flow cytometer. Apoptosis was analyzed by detection of both apoptotic bodies and DNA fragmentation. Results: Stable transfectant with either wild-type p53 or mutated p53 was established. The transfectants with wild-type p53 were more thermo sensitive than either those with a null p53 or with mutated p53. Although heat-induced G1 cell cycle arrest was substantially observed in all transfectants, wild-type p53 enhanced and prolonged the G1 arrest. Furthermore, wild-type p53 stimulated the induction of apoptosis by heat stress, whereas mutated p53 delayed it extremely. Conclusion: The p53 gene is at least a factor for determining cellular thermo sensitivity and wild-type p53 contributes to thermo sensitization resulting in enhancement of heat-induced apoptosis

  18. Structures of oncogenic, suppressor and rescued p53 core-domain variants: mechanisms of mutant p53 rescue

    Energy Technology Data Exchange (ETDEWEB)

    Wallentine, Brad D.; Wang, Ying; Tretyachenko-Ladokhina, Vira; Tan, Martha; Senear, Donald F. [University of California, Irvine, Irvine, CA 92697 (United States); Luecke, Hartmut, E-mail: hudel@uci.edu [University of California, Irvine, Irvine, CA 92697 (United States); University of California, Irvine, Irvine, CA 92697 (United States); University of California, Irvine, Irvine, CA 92697 (United States); University of California, Irvine, Irvine, CA 92697 (United States); Universidad del Pais Vasco, 48940 Leioa (Spain)

    2013-10-01

    X-ray crystallographic structures of four p53 core-domain variants were determined in order to gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53. To gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53, X-ray crystallographic structures of four p53 core-domain variants were determined. These include an oncogenic mutant, V157F, two single-site suppressor mutants, N235K and N239Y, and the rescued cancer mutant V157F/N235K/N239Y. The V157F mutation substitutes a smaller hydrophobic valine with a larger hydrophobic phenylalanine within strand S4 of the hydrophobic core. The structure of this cancer mutant shows no gross structural changes in the overall fold of the p53 core domain, only minor rearrangements of side chains within the hydrophobic core of the protein. Based on biochemical analysis, these small local perturbations induce instability in the protein, increasing the free energy by 3.6 kcal mol{sup −1} (15.1 kJ mol{sup −1}). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the

  19. Structures of oncogenic, suppressor and rescued p53 core-domain variants: mechanisms of mutant p53 rescue

    International Nuclear Information System (INIS)

    X-ray crystallographic structures of four p53 core-domain variants were determined in order to gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53. To gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53, X-ray crystallographic structures of four p53 core-domain variants were determined. These include an oncogenic mutant, V157F, two single-site suppressor mutants, N235K and N239Y, and the rescued cancer mutant V157F/N235K/N239Y. The V157F mutation substitutes a smaller hydrophobic valine with a larger hydrophobic phenylalanine within strand S4 of the hydrophobic core. The structure of this cancer mutant shows no gross structural changes in the overall fold of the p53 core domain, only minor rearrangements of side chains within the hydrophobic core of the protein. Based on biochemical analysis, these small local perturbations induce instability in the protein, increasing the free energy by 3.6 kcal mol−1 (15.1 kJ mol−1). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the β-sandwich scaffold. On the

  20. Translational approaches targeting the p53 pathway for anti-cancer therapy

    OpenAIRE

    Essmann, Frank; Schulze-Osthoff, Klaus

    2012-01-01

    The p53 tumour suppressor blocks cancer development by triggering apoptosis or cellular senescence in response to oncogenic stress or DNA damage. Consequently, the p53 signalling pathway is virtually always inactivated in human cancer cells. This unifying feature has commenced tremendous efforts to develop p53-based anti-cancer therapies. Different strategies exist that are adapted to the mechanisms of p53 inactivation. In p53-mutated tumours, delivery of wild-type p53 by adenovirus-based gen...

  1. The P53 Codon 72 SNP and Lung Cancer

    Czech Academy of Sciences Publication Activity Database

    Biroš, Erik; Biroš, I.; Kohout, A.; Kalina, I.; Bogyiova, E.; Stubna, J.

    Ghent: organising comittee, 2001. s. -. [Annual Meeting of the European Environmental Mutagen Society /31./. 01.09.2001-05.09.2001, Ghent] Institutional research plan: CEZ:AV0Z5039906 Keywords : p53 gene expression * lung cancer Subject RIV: DN - Health Impact of the Environment Quality

  2. NRF2 and p53: Januses in cancer?

    Science.gov (United States)

    Rotblat, Barak; Melino, Gerry; Knight, Richard A.

    2012-01-01

    The transcription factor nuclear factor (erythroid-derived 2)-like 2, also known as NFE2L2 or NRF2, is a master regulator of the anti-oxidative stress response and positively controls the expression of a battery of anti-oxidative stress response proteins and enzymes implicated in detoxification and glutathione generation. Although its detoxifying activity is important in cancer prevention, it has recently been shown that cancer cells also exploit its protective functions to thrive and resist chemotherapy. NRF2 was also shown to the pentose phosphate pathway and glutaminolysis, which promotes purine synthesis for supporting rapid proliferation and glutathione for providing anti-oxidative stress protection. Evidence obtained from cancer patients and cell lines suggest that NRF2 is highly active in a variety of human cancers and is associated with aggressiveness. p53 is a tumor suppressor that also promotes an anti-oxidative stress metabolic program and glutaminolysis. Here we will discuss the similarities between NRF2 and p53 and review evidence that p53 might be exploited by cancer cells to gain protection against oxidative stress, as is the case for NRF2. We discuss findings of co-regulation between these transcription factors and propose possible therapeutic strategies that can be used for treatment of cancers that harbor WT p53 and express high levels of NRF2. PMID:23174755

  3. Immunohistochemical detection of P53 and Mdm2 in vitiligo

    Directory of Open Access Journals (Sweden)

    Ola A Bakry

    2012-01-01

    Full Text Available Background: Vitiligo is a common depigmented skin disorder that is caused by selective destruction of melanocytes. It is generally accepted that the main function of melanin resides in the protection of skin cells against the deleterious effect of ultraviolet rays (UVRs. Association of vitiligo and skin cancer has been a subject of controversy. Occurrence of skin cancer in long-lasting vitiligo is rare despite multiple evidences of DNA damage in vitiliginous skin. Aim: To detect the expression of P53 and Mdm2 proteins in both depigmented and normally pigmented skin of vitiligo patients and to compare it to control subjects suffering from nonmelanoma skin cancer (NMSC. Materials and Methods: Thirty-four patients with vitiligo and 30 age and sex-matched patients with nodulo-ulcerative basal cell carcinoma (BCC as a control group were selected. Both patients and control subjects had outdoor occupations. Skin biopsies were taken from each case and control subjects. Histopathological examination of Hematoxylin and eosin-stained sections was done. Expression of P53 and Mdm2 proteins were examined immunohistochemically. Results: Both P53 and Mdm2 were strongly expressed in depigmented as well as normally pigmented skin of vitiligo patients. This expression involved the epidermis, skin adnexa and blood vessels with significant differences between cases and controls. Conclusions: The overexpression of P53 and Mdm2 proteins in both normally pigmented and depigmented skin of patients with vitiligo could contribute to the decreased occurrence of actinic damage and NMSC in these patients.

  4. A role for p53 in selenium-induced senescence

    Science.gov (United States)

    The tumor suppressor p53 and the ataxia-telangiectasia mutated (ATM) kinase play important roles in the senescence response to oncogene activation and DNA damage. We have previously shown that selenium-containing compounds can activate an ATM-dependent senescence response in MRC-5 normal fibroblasts...

  5. Functional repair of p53 mutation in colorectal cancer cells using trans-splicing

    OpenAIRE

    He, Xingxing; Liao, Jiazhi; Liu, Fang; Yan, Junwei; Yan, Jingjun; Shang, Haitao; Dou, Qian; CHANG Ying; Lin, Jusheng; Song, Yuhu

    2014-01-01

    Mutation in the p53 gene is arguably the most frequent type of gene-specific alterations in human cancers. Current p53-based gene therapy contains the administration of wt-p53 or the suppression of mutant p53 expression in p53-defective cancer cells. We hypothesized that trans-splicing could be exploited as a tool for the correction of mutant p53 transcripts in p53-mutated human colorectal cancer (CRC) cells. In this study, the plasmids encoding p53 pre-trans-splicing molecules (PTM) were tra...

  6. Re-Engineered p53 Chimera with Enhanced Homo-Oligomerization That Maintains Tumor Suppressor Activity

    OpenAIRE

    Okal, Abood; Cornillie, Sean; Matissek, Stephan J.; Matissek, Karina J.; Cheatham, Thomas E.; Lim, Carol S

    2014-01-01

    The use of the tumor suppressor p53 for gene therapy of cancer is limited by the dominant negative inactivating effect of mutant endogenous p53 in cancer cells. We have shown previously that swapping the tetramerization domain (TD) of p53 with the coiled-coil (CC) from Bcr allows for our chimeric p53 (p53-CC) to evade hetero-oligomerization with endogenous mutant p53. This enhances the utility of this construct, p53-CC, for cancer gene therapy. Because domain swapping to create p53-CC could r...

  7. Pla2g16 phospholipase mediates gain-of-function activities of mutant p53.

    Science.gov (United States)

    Xiong, Shunbin; Tu, Huolin; Kollareddy, Madhusudhan; Pant, Vinod; Li, Qin; Zhang, Yun; Jackson, James G; Suh, Young-Ah; Elizondo-Fraire, Ana C; Yang, Peirong; Chau, Gilda; Tashakori, Mehrnoosh; Wasylishen, Amanda R; Ju, Zhenlin; Solomon, Hilla; Rotter, Varda; Liu, Bin; El-Naggar, Adel K; Donehower, Lawrence A; Martinez, Luis Alfonso; Lozano, Guillermina

    2014-07-29

    p53(R172H/+) mice inherit a p53 mutation found in Li-Fraumeni syndrome and develop metastatic tumors at much higher frequency than p53(+/-) mice. To explore the mutant p53 metastatic phenotype, we used expression arrays to compare primary osteosarcomas from p53(R172H/+) mice with metastasis to osteosarcomas from p53(+/-) mice lacking metastasis. For this study, 213 genes were differentially expressed with a P value ETS2 suppressed mutant p53 induction of Pla2g16. Thus, our study identifies a phospholipase as a transcriptional target of mutant p53 that is required for metastasis. PMID:25024203

  8. Modulation of p53β and p53γ expression by regulating the alternative splicing of TP53 gene modifies cellular response

    OpenAIRE

    Marcel, V; Fernandes, K; Terrier, O; LANE, D. P.; Bourdon, J-C

    2014-01-01

    In addition to the tumor suppressor p53 protein, also termed p53α, the TP53 gene produces p53β and p53γ through alternative splicing of exons 9β and 9γ located within TP53 intron 9. Here we report that both TG003, a specific inhibitor of Cdc2-like kinases (Clk) that regulates the alternative splicing pre-mRNA pathway, and knockdown of SFRS1 increase expression of endogenous p53β and p53γ at mRNA and protein levels. Development of a TP53 intron 9 minigene shows that TG003 treatment and knockdo...

  9. Phosphorylation at Ser-15 and Ser-392 in mutant p53 molecules from human tumors is altered compared to wild-type p53.

    OpenAIRE

    Ullrich, S J; K. Sakaguchi; Lees-Miller, S P; Fiscella, M.; Mercer, W E; Anderson, C W; Appella, E

    1993-01-01

    The product of the p53 gene suppresses cell growth and plays a critical role in suppressing development of human tumors. p53 protein binds DNA, activates transcription, and can be phosphorylated at N- and C-terminal sites. Previously, wild-type p53 was shown to be hyperphosphorylated compared to mutant p53 during p53-mediated growth arrest in vivo. Here we show that Ser-15 and Ser-9 in the N-terminal transactivation domain of wild-type human p53 are phosphorylated in vivo in cells derived fro...

  10. Differential regulation of the REGγ–proteasome pathway by p53/TGF-β signalling and mutant p53 in cancer cells

    OpenAIRE

    Ali, Amjad; Wang, Zhuo; Fu, Junjiang; Lei, Ji; Liu, Jiang; Lei, Li; Wang,; Chen, Jiwu; Caulin, Carlos; Jeffrey, N. Myers; Zhang, Pei; Xiao, Jianru; Zhang, Bianhong; Li, Xiaotao

    2013-01-01

    Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer cells. Here we show that p53/TGF-β signalling inhibits the REGγ–20S proteasome pathway by repressing REGγ expression. Smad3 and p53 interact on the REGγ promoter via the p53RE/SBE region. Conversely, mutant p53 binds to the REGγ promoter and recruits p300. Importantly, mutant p53 prevents Smad3/...

  11. Depression of p53-independent Akt survival signals after high-LET radiation in mutated p53 cells

    Science.gov (United States)

    Ohnishi, Takeo; Takahashi, Akihisa; Nakagawa, Yosuke

    Although mutations and deletions in the p53 tumor suppressor gene lead to resistance to low linear energy transfer (LET) radiation, high-LET radiation efficiently induces cell lethality and apoptosis regardless of the p53 gene status. Recently, it has been suggested that the induction of p53-independent apoptosis takes place through the activation of Caspase-9 which results in the cleavage of Caspase-3 and poly (ADP-ribose) polymerase (PARP). This study was designed to examine if high-LET radiation depresses the activities of serine/threonine protein kinase B (PKB, also known as Akt) and Akt-related proteins. Human gingival cancer cells (Ca9-22 cells) harboring a mutated p53 (mp53) gene were irradiated with 2 Gy of X-rays or Fe-ion beams. The cellular contents of Akt-related proteins participating in cell survival signals were analyzed with Western blotting analysis 1 h, 2 h, 3 h and 6 h after irradiation. Cell cycle distributions after irradiation were assayed with flow cytometric analysis.Akt-related protein levels were decreased when cells were irradiated with high-LET radiation. High-LET radiation increased G _{2}/M phase arrests and suppressed the progression of the cell cycle much more efficiently when compared to low-LET radiation. These results suggest that high-LET radiation enhances apoptosis through the activation of Caspase-3 and Caspase-9, and depresses cell growth by suppressing Akt-related signals, even in the mp53 cells.

  12. 扁平苔癣皮损区c-myc PCNA VEGF的表达研究%Expression study of c-myc, proliferating cell nuclear antigen and vascular endothelial growth factor in lichen planus

    Institute of Scientific and Technical Information of China (English)

    化红霞; 王香弟

    2006-01-01

    目的 探讨原癌基因c-myc、增殖细胞核抗原(PCNA)、血管内皮细胞生长因子(VEGF)在扁平苔癣发病中的作用.方法 采用免疫组织化学方法,检测了60例扁平苔癣皮损区及60名健康志愿者的表皮中c-myc、PCNA、VEGF的表达及分布特点.结果 扁平苔癣皮损区c-myc、PCNA、VEGF表达均较正常表皮中的表达明显增强,分布于除角质层以外的表皮各层,而正常表皮表达阴性或仅在基底层有弱阳性表达.结论 c-myc、PCNA在扁平苔癣皮损中过度表达,提示其与扁平苔癣的表皮细胞过度增殖、分化异常有关;VEGF过度表达,提示VEGF与扁平苔癣的真皮浅层淋巴细胞浸润有关.

  13. Paracrine Apoptotic Effect of p53 Mediated by Tumor Suppressor Par-4

    Directory of Open Access Journals (Sweden)

    Ravshan Burikhanov

    2014-01-01

    Full Text Available The guardian of the genome, p53, is often mutated in cancer and may contribute to therapeutic resistance. Given that p53 is intact and functional in normal tissues, we harnessed its potential to inhibit the growth of p53-deficient cancer cells. Specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. This paracrine effect was mediated by p53-dependent secretion of the tumor suppressor Par-4. Accordingly, the activation of p53 in normal mice, but not p53−/− or Par-4−/− mice, caused systemic elevation of Par-4, which induced apoptosis of p53-deficient tumor cells. Mechanistically, p53 induced Par-4 secretion by suppressing the expression of its binding partner, UACA, which sequesters Par-4. Thus, normal cells can be empowered by p53 activation to induce Par-4 secretion for the inhibition of therapy-resistant tumors.

  14. Identification of two novel functional p53 responsive elements in the Herpes Simplex Virus-1 genome

    OpenAIRE

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

    2014-01-01

    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 activatio...

  15. PCNA-dependent accumulation of CDKN1A into nuclear foci after ionizing irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wiese, Claudia [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rudolph, Jeanette Heede [GSI-Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany); Jakob, Burkhard [GSI-Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany); Fink, Daniela [GSI-Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany); Tobias, Frank [GSI-Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany); Blattner, Christine [Karlsruhe Inst. of Technology (KIT) (Germany). Inst. of Toxicology and Genetics; Taucher-Scholz, Gisela [GSI-Helmholtz Centre for Heavy Ion Research, Darmstadt (Germany)

    2012-03-26

    The cyclin-dependent kinase inhibitor CDKN1A/p21 confers cell-cycle arrest in response to DNA damage and inhibits DNA replication through its direct interaction with the proliferating cell nuclear antigen (PCNA) and cyclin/cyclin-dependent kinase complexes. Previously, we reported that in response to densely ionizing radiation CDKN1A rapidly is recruited to the sites of particle traversal, and that CDKN1A foci formation in response to heavy ions is independent of its transactivation by TP53. In this paper, we show that exposure of normal human fibroblasts to X-rays or to H2O2 also induces nuclear accumulations of CDKN1A. We find that CDKN1A foci formation in response to radiation damage is dependent on its dephosphorylation and on its direct physical interaction with PCNA. Live cell imaging analyses of ectopically expressed EGFP-CDKN1A and dsRed-PCNA show rapid recruitment of both proteins into foci after radiation damage. Detailed dynamic measurements reveal a slightly delayed recruitment of CDKN1A compared to PCNA, which is best described by bi-exponential curve fitting, taking the preceding binding of PCNA to DNA into account. Finally, we propose a regulatory role for CDKN1A in mediating PCNA function after radiation damage, and provide evidence that this role is distinct from its involvement in nucleotide excision repair and unrelated to double-strand break repair.

  16. Antigen

    Science.gov (United States)

    An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune ... and is trying to fight it off. An antigen may be a substance from the environment, such ...

  17. Recombinant production, crystallization and preliminary X-ray analysis of PCNA from the psychrophilic archaeon Methanococcoides burtonii DSM 6242

    International Nuclear Information System (INIS)

    The proliferating cell nuclear antigen (PCNA) from the eurypsychrophilic archaeon M. burtonii DSM 6242 has been cloned, overproduced, purified and crystallized. Crystals were deemed to be suitable for X-ray analysis and structure determination to 2.40 Å resolution. Proliferating cell nuclear antigen (PCNA) is a DNA-clamping protein that is responsible for increasing the processivity of the replicative polymerases during DNA replication and repair. The PCNA from the eurypsychrophilic archaeon Methanococcoides burtonii DSM 6242 (MbPCNA) has been targeted for protein structural studies. A recombinant expression system has been created that overproduces MbPCNA with an N-terminal hexahistidine affinity tag in Escherichia coli. As a result, recombinant MbPCNA with a molecular mass of 28.3 kDa has been purified to at least 95% homogeneity and crystallized by vapor-diffusion equilibration. Preliminary X-ray analysis revealed a trigonal hexagonal R3 space group, with unit-cell parameters a = b = 102.5, c = 97.5 Å. A single MbPCNA crystal was subjected to complete diffraction data-set collection using synchrotron radiation and reflections were measured to 2.40 Å resolution. The diffraction data were of suitable quality for indexing and scaling and an unrefined molecular-replacement solution has been obtained

  18. Targeting the EGFR/PCNA signaling suppresses tumor growth of triple-negative breast cancer cells with cell-penetrating PCNA peptides.

    Directory of Open Access Journals (Sweden)

    Yung-Luen Yu

    Full Text Available Tyrosine 211 (Y211 phosphorylation of proliferation cell nuclear antigen (PCNA coincides with pronounced cancer cell proliferation and correlates with poor survival of breast cancer patients. In epidermal growth factor receptor (EGFR tyrosine kinase inhibitor (TKI-resistant cells, both nuclear EGFR (nEGFR expression and PCNA Y211 phosphorylation are increased. Moreover, the resistance to EGFR TKI is a major clinical problem in treating EGFR-overexpressing triple-negative breast cancer (TNBC. Thus, effective treatment to combat resistance is urgently needed. Here, we show that treatment of cell-penetrating PCNA peptide (CPPP inhibits growth and induces apoptosis of human TNBC cells. The Y211F CPPP specifically targets EGFR and competes directly for PCNA tyrosine Y211 phosphorylation and prevents nEGFR from binding PCNA in vivo; it also suppresses tumor growth by sensitizing EGFR TKI resistant cells, which have enhanced nEGFR function and abrogated classical EGFR membrane signaling. Furthermore, we identify an active motif of CPPP, RFLNFF (RF6 CPPP, which is necessary and sufficient to inhibit TKI-resistant TNBC cell growth of orthotopic implanted tumor in mice. Finally, the activity of its synthetic retro-inverted derivative, D-RF6 CPPP, on an equimolar basis, is more potent than RF6 CPPP. Our study reveals a drug candidate with translational potential for the future development of safe and effective therapeutic for EGFR TKI resistance in TNBC.

  19. Disruption of focal adhesion kinase and p53 interaction with small molecule compound R2 reactivated p53 and blocked tumor growth

    International Nuclear Information System (INIS)

    Focal Adhesion Kinase (FAK) is a 125 kDa non-receptor kinase that plays a major role in cancer cell survival and metastasis. We performed computer modeling of the p53 peptide containing the site of interaction with FAK, predicted the peptide structure and docked it into the three-dimensional structure of the N-terminal domain of FAK involved in the complex with p53. We screened small molecule compounds that targeted the site of the FAK-p53 interaction and identified compounds (called Roslins, or R compounds) docked in silico to this site. By different assays in isogenic HCT116p53+/+ and HCT116 p53-/- cells we identified a small molecule compound called Roslin 2 (R2) that bound FAK, disrupted the binding of FAK and p53 and decreased cancer cell viability and clonogenicity in a p53-dependent manner. In addition, dual-luciferase assays demonstrated that the R2 compound increased p53 transcriptional activity that was inhibited by FAK using p21, Mdm-2, and Bax-promoter targets. R2 also caused increased expression of p53 targets: p21, Mdm-2 and Bax proteins. Furthermore, R2 significantly decreased tumor growth, disrupted the complex of FAK and p53, and up-regulated p21 in HCT116 p53+/+ but not in HCT116 p53-/- xenografts in vivo. In addition, R2 sensitized HCT116p53+/+ cells to doxorubicin and 5-fluorouracil. Thus, disruption of the FAK and p53 interaction with a novel small molecule reactivated p53 in cancer cells in vitro and in vivo and can be effectively used for development of FAK-p53 targeted cancer therapy approaches

  20. Low doses of arsenic, via perturbing p53, promotes tumorigenesis.

    Science.gov (United States)

    Ganapathy, Suthakar; Li, Ping; Fagman, Johan; Yu, Tianqi; Lafontant, Jean; Zhang, Guojun; Chen, Changyan

    2016-09-01

    In drinking water and in workplace or living environments, low doses of arsenic can exist and operate as a potent carcinogen. Due to insufficient understanding and information on the pervasiveness of environmental exposures to arsenic, there is an urgent need to elucidate the underlying molecular mechanisms of arsenic regarding its carcinogenic effect on human health. In this study, we demonstrate that low doses of arsenic exposure mitigate or mask p53 function and further perturb intracellular redox state, which triggers persistent endoplasmic reticulum (ER) stress and activates UPR (unfolded protein response), leading to transformation or tumorigenesis. Thus, the results suggest that low doses of arsenic exposure, through attenuating p53-regulated tumor suppressive function, change the state of intracellular redox and create a microenvironment for tumorigenesis. Our study also provides the information for designing more effective strategies to prevent or treat human cancers initiated by arsenic exposure. PMID:27425828

  1. Estrogen receptor prevents p53-dependent apoptosis in breast cancer

    OpenAIRE

    Bailey, Shannon T.; Shin, Hyunjin; Westerling, Thomas; Liu, Xiaole Shirley; Brown, Myles

    2012-01-01

    More than two-thirds of breast cancers express the estrogen receptor (ER) and depend on estrogen for growth and survival. Therapies targeting ER function, including aromatase inhibitors that block the production of estrogens and ER antagonists that alter ER transcriptional activity, play a central role in the treatment of ER+ breast cancers of all stages. In contrast to ER− breast cancers, which frequently harbor mutations in the p53 tumor suppressor, ER+ breast cancers are predominantly wild...

  2. Biological activity and safety of adenoviral vector-expressed wild-type p53 after intratumoral injection in melanoma and breast cancer patients with p53-overexpressing tumors

    NARCIS (Netherlands)

    Dummer, R; Bergh, J; Karlsson, Y; Horovitz, JA; Mulder, NH; Huinin, DT; Burg, G; Hofbauer, G; Osanto, S

    2000-01-01

    p53 mutations are common genetic alterations in human cancer. Gene transfer of a wild-type (wt) p53 gene reverses the loss of normal p53 function in vitro and in vivo. A phase I dose escalation study of single intratumoral (i.t.) injection of a replication-defective adenoviral expression vector cont

  3. Electrophoretic detection of protein p53 in human leukocytes

    International Nuclear Information System (INIS)

    The authors have found an acid-soluble protein with mol. wt. of about 53 kD in peripheral blood leukocytes of persons with Down's syndrome. It was present in different quantities in all 20 patients tested, but was virtually not discovered in 12 healthy blood donors. This paper determines the possible identity of this protein with protein p53 from mouse ascites carcinoma by comparing their electrophoretic mobilities, because the accuracy of electrophoretic determination of the molecular weight of proteins is not sufficient to identify them. The paper also describes experiments to detect a protein with electrophoretic mobility identical with that of a protein in the leukocytes of patients with Down's syndrome in leukocytes of patients with leukemia. To discover if protein p53 is involved in cell proliferation, the protein composition of leukocytes from healthy blood donors, cultured in the presence and absence of phytohemagglutinin (PHA), was compared. Increased incorporation of H 3-thymidine by leukocytes of patients with Down's syndrome is explained by the presence of a population of immature leukocytes actively synthesizing DNA in the peripheral blood of these patients, and this can also explain the presence of protein p53 in the leukocytes of these patients

  4. p53 gene in treatment of hepatic carcinoma:Status quo

    Institute of Scientific and Technical Information of China (English)

    Yong-Song Guan; Zi La; Lin Yang; Qing He; Ping Li

    2007-01-01

    Hepatocellular carcinoma(HCC)is one of the 10 most common cancers worldwide.There is no ideal treatment for HCC yet and many researchers are trying to improve the effects of treatment by changing therapeutic strategies.As the majority of human cancers seem to exhibit either abnormal p53 gene or disrupted p53 gene activation pathways,intervention to restore wild-type p53 (wt-p53)activities is an attractive anti-cancer therapy including HCC.Abnormalities of p53 are also considered a predisposition factor for hepatocarcinogenesis.p53 is frequently mutated in HCC.Most HCCs have defects in the p53-mediated apoptotic pathway although they carry wt-p53.High expression of p53 in vivo may exert therapeutic effects on HCC in two aspects:(1)High expression of exogenous p53 protein induces apoptosis of tumor cells by inhibiting proliferation of cells through several biologic pathways and(2)Exogenous p53 renders HCC more sensitive to some chemotherapeutic agents.Several approaches have been designed for the treatment of HCC via the p53 pathway by restoring the tumor suppression function from inactivation,rescuing the mutated p53 gene from instability,or delivering therapeutic exogenous p53.Products with p53 status as the target have been studied extensively in vitro and in vivo.This review elaborates some therapeutic mechanisms and advances in using recombinant human adenovirus p53 and oncolytic virus products for the treatment of HCC.

  5. Release of targeted p53 from the mitochondrion as an early signal during mitochondrial dysfunction

    Science.gov (United States)

    Increased accumulation of p53 tumor suppressor protein is an early response to low-level stressors. To investigate the fate of mitochondrial-sequestered p53, mouse embryonic fibroblast cells (MEFs) on a p53-deficient genetic background were transfected with p53-EGFP fusion protei...

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

    NARCIS (Netherlands)

    Simeonova, I.; Jaber, S.; Draskovic, I.; Bardot, B.; Fang, M.; Bouarich-Bourimi, R.; Lejour, V.; Charbonnier, L.; Soudais, C.; Bourdon, J.C.; Huerre, M.; Londono-Vallejo, A.; Toledo, F.

    2013-01-01

    Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53(Delta31), a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis,

  7. A SENSITIVE IMMUNOFLUORESCENCE ASSAY FOR DETECTION OF P53 PROTEIN ACCUMULATION IN SPUTUM

    Science.gov (United States)

    p53 mutations are common genetic alterations in lung cancers and usually result in p53 protein accumulation in tumor cells. Sputum is noninvasive to collect and ideal for screening p53 abnormalities. This study was to determine the feasibility of detecting p53 protein accumulatio...

  8. Analysis of the role of PCNA-DNA contacts during clamp loading

    Directory of Open Access Journals (Sweden)

    Goedken Eric R

    2010-01-01

    Full Text Available Abstract Background Sliding clamps, such as Proliferating Cell Nuclear Antigen (PCNA in eukaryotes, are ring-shaped protein complexes that encircle DNA and enable highly processive DNA replication by serving as docking sites for DNA polymerases. In an ATP-dependent reaction, clamp loader complexes, such as the Replication Factor-C (RFC complex in eukaryotes, open the clamp and load it around primer-template DNA. Results We built a model of RFC bound to PCNA and DNA based on existing crystal structures of clamp loaders. This model suggests that DNA would enter the clamp at an angle during clamp loading, thereby interacting with positively charged residues in the center of PCNA. We show that simultaneous mutation of Lys 20, Lys 77, Arg 80, and Arg 149, which interact with DNA in the RFC-PCNA-DNA model, compromises the ability of yeast PCNA to stimulate the DNA-dependent ATPase activity of RFC when the DNA is long enough to extend through the clamp. Fluorescence anisotropy binding experiments show that the inability of the mutant clamp proteins to stimulate RFC ATPase activity is likely caused by reduction in the affinity of the RFC-PCNA complex for DNA. We obtained several crystal forms of yeast PCNA-DNA complexes, measuring X-ray diffraction data to 3.0 Å resolution for one such complex. The resulting electron density maps show that DNA is bound in a tilted orientation relative to PCNA, but makes different contacts than those implicated in clamp loading. Because of apparent partial disorder in the DNA, we restricted refinement of the DNA to a rigid body model. This result contrasts with previous analysis of a bacterial clamp bound to DNA, where the DNA was well resolved. Conclusion Mutational analysis of PCNA suggests that positively charged residues in the center of the clamp create a binding surface that makes contact with DNA. Disruption of this positive surface, which had not previously been implicated in clamp loading function, reduces RFC

  9. Ser18 and 23 phosphorylation is required for p53-dependent apoptosis and tumor suppression

    OpenAIRE

    Chao, Connie; Herr, Deron; Chun, Jerold; Xu, Yang

    2006-01-01

    Mouse p53 is phosphorylated at Ser18 and Ser23 after DNA damage. To determine whether these two phosphorylation events have synergistic functions in activating p53 responses, we simultaneously introduced Ser18/23 to Ala mutations into the endogenous p53 locus in mice. While partial defects in apoptosis are observed in p53S18A and p53S23A thymocytes exposed to IR, p53-dependent apoptosis is essentially abolished in p53S18/23A thymocytes, indicating that these two events have critical and syner...

  10. Evidence for allosteric variants of wild-type p53, a tumour suppressor protein.

    OpenAIRE

    Cook, A; Milner, J

    1990-01-01

    A tumour suppressor function for p53 is indicated in human lung cancer and in carcinoma of the colorectum. Loss of suppressor function, by mutation of the p53 gene, is associated with activation of p53 as an oncogene. The suppressor (wild type) and oncogenic (mutant) forms of the murine p53 protein are distinguishable at the molecular level by reactivity with anti-p53 monoclonal antibodies. For example, activated mutant p53 fails to react with PAb246 (p53-246 degrees). We now demonstrate that...

  11. p53-Induced Growth Arrest Is Regulated by the Mitochondrial SirT3 Deacetylase

    OpenAIRE

    SiDe Li; Michaela Banck; Shiraz Mujtaba; Ming-Ming Zhou; Mary M Sugrue; Walsh, Martin J

    2010-01-01

    A hallmark of p53 function is to regulate a transcriptional program in response to extracellular and intracellular stress that directs cell cycle arrest, apoptosis, and cellular senescence. Independent of the role of p53 in the nucleus, some of the anti-proliferative functions of p53 reside within the mitochondria [1]. p53 can arrest cell growth in response to mitochondrial p53 in an EJ bladder carcinoma cell environment that is naïve of p53 function until induced to express p53 [2]. TP53 can...

  12. Paracrine Apoptotic Effect of p53 Mediated by Tumor Suppressor Par-4

    OpenAIRE

    Ravshan Burikhanov; Tripti Shrestha-Bhattarai; Nikhil Hebbar; Shirley Qiu; Yanming Zhao; Gerard P. Zambetti; Vivek M. Rangnekar

    2014-01-01

    The guardian of the genome, p53, is often mutated in cancer and may contribute to therapeutic resistance. Given that p53 is intact and functional in normal tissues, we harnessed its potential to inhibit the growth of p53-deficient cancer cells. Specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. This paracrine effect was mediated by p53-dependent secretion of the tumor suppressor Par-4. Accordingly, the activation of p53 in normal mice...

  13. In vivo analysis of p53 tumor suppressor function using genetically engineered mouse models

    OpenAIRE

    Brož, Daniela Kenzelmann; Attardi, Laura D.

    2010-01-01

    p53 is a crucial tumor suppressor, as evidenced by the high propensity for p53 mutation during human cancer development. Already more than a decade ago, p53 knockout mice confirmed that p53 is critical for preventing tumorigenesis. More recently, a host of p53 knock-in mouse strains has been generated, with the aim of either more precisely modeling p53 mutations in human cancer or better understanding p53's regulation and downstream activities. In the first category, several mouse strains exp...

  14. A common Gain of function of p53 cancer mutants in inducing genetic instability

    OpenAIRE

    Liu, Dong-Ping; Song, Hoseok; Xu, Yang

    2009-01-01

    The critical tumor suppressor p53 is mutated in over half of all human cancers. The majority of p53 cancer mutations are missense mutations, which can be classified into contact mutations that directly disrupt the DNA-binding motif of p53 but have modest impact on p53 conformation and structural mutations that greatly disrupt p53 conformation. Many p53 cancer mutants, including the hotspot mutations (R175H, R248W and R273H), not only lose p53-dependent tumor suppressor activities, but also ac...

  15. Insights into p53 transcriptional function via genome-wide chromatin occupancy and gene expression analysis

    OpenAIRE

    F Nikulenkov; Spinnler, C; Li, H.; Tonelli, C; Shi, Y; Turunen, M.; Kivioja, T; Ignatiev, I.; Kel, A; Taipale, J; Selivanova, G

    2012-01-01

    The tumor-suppressor p53 can induce various biological responses. Yet, it is not clear whether it is p53 in vivo promoter selectivity that triggers different transcription programs leading to different outcomes. Our analysis of genome-wide chromatin occupancy by p53 using chromatin immunoprecipitation (ChIP)-seq revealed ‘p53 default program', that is, the pattern of major p53-bound sites that is similar upon p53 activation by nutlin3a, reactivation of p53 and induction of tumor cell apoptosi...

  16. Mutant p53 accumulates in cycling and proliferating cells in the normal tissues of p53 R172H mutant mice.

    Science.gov (United States)

    Goh, Amanda M; Xue, Yuezhen; Leushacke, Marc; Li, Ling; Wong, Julin S; Chiam, Poh Cheang; Rahmat, Siti Aishah Binte; Mann, Michael B; Mann, Karen M; Barker, Nick; Lozano, Guillermina; Terzian, Tamara; Lane, David P

    2015-07-20

    The tumour suppressor p53 is regulated primarily at the protein level. In normal tissues its levels are maintained at a very low level by the action of specific E3 ligases and the ubiquitin proteosome pathway. The mutant p53 protein contributes to transformation, metastasis and drug resistance. High levels of mutant p53 can be found in tumours and the accumulation of mutant p53 has previously been reported in pathologically normal cells in human skin. We show for the first time that similarly elevated levels of mutant p53 can be detected in apparently normal cells in a mutant p53 knock-in mouse model. In fact, in the small intestine, mutant p53 spontaneously accumulates in a manner dependent on gene dosage and cell type. Mutant p53 protein is regulated similarly to wild type p53, which can accumulate rapidly after induction by ionising radiation or Mdm2 inhibitors, however, the clearance of mutant p53 protein is much slower than wild type p53. The accumulation of the protein in the murine small intestine is limited to the cycling, crypt base columnar cells and proliferative zone and is lost as the cells differentiate and exit the cell cycle. Loss of Mdm2 results in even higher levels of p53 expression but p53 is still restricted to proliferating cells in the small intestine. Therefore, the small intestine of these p53 mutant mice is an experimental system in which we can dissect the molecular pathways leading to p53 accumulation, which has important implications for cancer prevention and therapy. PMID:26255629

  17. Adenovirus-mediated p53 and ING4 gene co-transfer elicits synergistic antitumor effects through enhancement of p53 acetylation in breast cancer.

    Science.gov (United States)

    Wu, Jie; Zhu, Yanbo; Xu, Chun; Xu, Hong; Zhou, Xiumin; Yang, Jicheng; Xie, Yufeng; Tao, Min

    2016-01-01

    Multigene-based combination therapy may be an effective practice in cancer gene therapy. Substantial studies have demonstrated that tumor suppressor p53 acetylation is indispensable for p53 activation. Inhibitor of growth 4 (ING4), as a novel tumor suppressor, is capable of remarkably enhancing p53 acetylation and its transcriptional activity. Hence, we assumed that combined treatment of p53 and ING4 double tumor suppressors would exhibit enhanced antitumor effects. The combined therapeutic efficacy of p53 and ING4 for human cancers has not been previously reported. We thus generated multiple promoter expression cassette-based recombinant adenovirus-co-expressing ING4 and p53 double tumor suppressor genes (AdVING4/p53), evaluated the combined effects of AdVING4/p53 on breast cancer using the MDA-MB-231 (mutant p53) human breast cancer cell line, and also elucidated its underlying molecular mechanisms. We demonstrated that AdVING4/p53-mediated p53 and ING4 co-expression induced synergistic growth inhibition and apoptosis as well as enhanced effects on upregulation of acetylated p53, P21, Bax, PUMA, Noxa, cleaved caspase-9, cleaved caspase-3 and cleaved PARP, and downregulation of Bcl-2, CD31 and microvessel density (MVD) in MDA-MB-231 breast cancer in vitro and/or in vivo subcutaneous (s.c.) xenografted tumors. The synergistic antitumor activity elicited by AdVING4/p53 was closely associated with the enhanced activation of the intrinsic apoptotic pathway and synergistic inhibition of tumor angiogenesis, very possibly via ING4-mediated enhancement of p53 acetylation and activity. Thus, our results indicate that cancer gene therapy combining two or more tumor suppressors such as p53 and ING4 may constitute a novel and effective therapeutic modality for human breast cancer and other cancers. PMID:26530780

  18. Suicide genes or p53 gene and p53 target genes as targets for cancer gene therapy by ionizing radiation

    International Nuclear Information System (INIS)

    Radiotherapy has some disadvantages due to the severe side-effect on the normal tissues at a curative dose of ionizing radiation (IR). Similarly, as a new developing approach, gene therapy also has some disadvantages, such as lack of specificity for tumors, limited expression of therapeutic gene, potential biological risk. To certain extent, above problems would be solved by the suicide genes or p53 gene and its target genes therapies targeted by ionizing radiation. This strategy not only makes up the disadvantage from radiotherapy or gene therapy alone, but also promotes success rate on the base of lower dose. By present, there have been several vectors measuring up to be reaching clinical trials. This review focused on the development of the cancer gene therapy through suicide genes or p53 and its target genes mediated by IR. (authors)

  19. Structural insights into the transcription-independent apoptotic pathway of p53

    OpenAIRE

    Chi, Seung-Wook

    2014-01-01

    Reactivating the p53 pathway in tumors is an important strategy for anticancer therapy. In response to diverse cellular stresses, the tumor suppressor p53 mediates apoptosis in a transcriptionindependent and transcription-dependent manner. Although extensive studies have focused on the transcription-dependent apoptotic pathway of p53, the transcription-independent apoptotic pathway of p53 has only recently been discovered. Molecular interactions between p53 and Bcl-2 family proteins in the mi...

  20. MSL2 Promotes Mdm2-independent Cytoplasmic Localization of p53*

    OpenAIRE

    Kruse, Jan-Philipp; Gu, Wei

    2009-01-01

    Although it was originally thought of as a passive way to block the nuclear function of p53, accumulating evidence suggests that cytoplasmic localization of p53 plays an active role in p53-mediated functions such as apoptosis and autophagy. Previous studies by us and others demonstrated that Mdm2-mediated p53 ubiquitination induces both degradation and cytoplasmic localization. Here we describe MSL2, a novel E3 ligase for p53 that promotes ubiquitin-dependent cytoplasm...

  1. Posttranscriptional Regulation of p53 and Its Targets by RNA-Binding Proteins

    OpenAIRE

    Zhang, Jin; Chen, Xinbin

    2008-01-01

    p53 tumor suppressor plays a pivotal role in maintaining genomic integrity and preventing cancer development. The importance of p53 in tumor suppression is illustrated by the observation that about 50% human tumor cells have a dysfunctional p53 pathway. Although it has been well accepted that the activity of p53 is mainly controlled through post-translational modifications, recent studies have revealed that posttranscriptional regulations of p53 by various RNA-binding proteins also play a cru...

  2. Regulation of p53 Localization and Activity by Ubc13▿ †

    OpenAIRE

    Laine, Aaron; Topisirovic, Ivan; Zhai, Dayong; John C Reed; Borden, Katherine L. B.; Ronai, Ze'ev

    2006-01-01

    The abundance and activity of p53 are regulated largely by ubiquitin ligases. Here we demonstrate a previously undisclosed regulation of p53 localization and activity by Ubc13, an E2 ubiquitin-conjugating enzyme. While increasing p53 stability, Ubc13 decreases p53 transcriptional activity and increases its localization to the cytoplasm, changes that require its ubiquitin-conjugating activity. Ubc13 elicits K63-dependent ubiquitination of p53, which attenuates Hdm2-induced polyubiquitination o...

  3. Tumor suppressor p53 and its gain-of-function mutants in cancer

    OpenAIRE

    Liu, Juan; Zhang, Cen; Feng, Zhaohui

    2013-01-01

    Tumor suppressor p53 plays a pivotal role in tumor suppression. p53 is the most frequently mutated gene in cancer. As a transcription factor, p53 mainly exerts its role in tumor suppression through transcriptional regulation of its downstream target genes. Thus, p53 and its target genes form a complex p53 signaling pathway to regulate a wide variety of biological processes to prevent tumorigenesis. Recent studies have revealed that in addition to apoptosis, cell cycle arrest and senescence, p...

  4. Classical and novel roles of p53 and prospects for anticancer therapy

    OpenAIRE

    Fuster, José J.; Sanz-González, Silvia M.; Moll, Ute M.; Andrés, Vicente

    2007-01-01

    The tumor suppressor p53 is a transcription factor that is frequently inactivated in human tumors. Therefore,restoring its function has been considered an attractive approach to restrain cancer. Typically, p53-dependent growth arrest, senescence and apoptosis of tumor cells have been attributed to transcriptional activity of nuclear p53. Notably, wild-type p53 gain-of-function enhances cancer resistance in the mouse, but it also accelerates aging in some models, possibly due to altered p53...

  5. Gene expression profiles resulting from stable loss of p53 mirrors its role in tissue differentiation.

    Directory of Open Access Journals (Sweden)

    Oliver Couture

    Full Text Available The tumor suppressor gene p53 is involved in a variety of cellular activities such as cellular stress responses, cell cycle regulation and differentiation. In our previous studies we have shown p53's transcription activating role to be important in osteoblast differentiation. There is still a debate in the literature as to whether p53 inhibits or promotes differentiation. We have found p53 heterozygous mice to show a p53 dependency on some bone marker gene expression that is absent in knockout mice. Mice heterozygous for p53 also show a higher incidence of osteosarcomas than p53 knockout mice. This suggests that p53 is able to modify the environment within osteoblasts. In this study we compare changes in gene expression resulting after either a transient or stable reduction in p53. Accordingly we reduced p53 levels transiently and stably in C2C12 cells, which are capable of both myoblast and osteoblast differentiation, and compared the changes in gene expression of candidate genes regulated by the p53 pathway. Using a PCR array to assay for p53 target genes, we have found different expression profiles when comparing stable versus transient knockdown of p53. As expected, several genes with profound changes after transient p53 loss were related to apoptosis and cell cycle regulation. In contrast, stable p53 loss produced a greater change in MyoD and other transcription factors with tissue specific roles, suggesting that long term loss of p53 affects tissue homeostasis to a greater degree than changes resulting from acute loss of p53. These differences in gene expression were validated by measuring promoter activity of different pathway specific genes involved in differentiation. These studies suggest that an important role for p53 is context dependent, with a stable reduction in p53 expression affecting normal tissue physiology more than acute loss of p53.

  6. A nanobody modulates the p53 transcriptional program without perturbing its functional architecture

    OpenAIRE

    Bethuyne, Jonas; De Gieter, Steven; Zwaenepoel, Olivier; Garcia-Pino, Abel; Durinck, Kaat; Verhelle, Adriaan; Hassanzadeh-Ghassabeh, Gholamreza; Speleman, Franki; Loris, Remy; Gettemans, Jan

    2014-01-01

    The p53 transcription factor plays an important role in genome integrity. To perform this task, p53 regulates the transcription of genes promoting various cellular outcomes including cell cycle arrest, apoptosis or senescence. The precise regulation of this activity remains elusive as numerous mechanisms, e.g. posttranslational modifications of p53 and (non-)covalent p53 binding partners, influence the p53 transcriptional program. We developed a novel, non-invasive tool to manipulate endogeno...

  7. Transcriptional Regulation of Breast Cancer Resistance Protein (BCRP) by p53 in p53-null Saos-2 cells%p53对乳腺癌耐药蛋白基因的转录调控

    Institute of Scientific and Technical Information of China (English)

    吴新刚; 彭姝彬; 闾四平; 张年凤; 邹进

    2012-01-01

    Breast cancer resistance protein (BCRP) is a member of the ATP-binding cassette (ABC) transporter superfamily. BCRP confers drug resistance in cancer by transporting chemotherapeutic agents such as mitoxantrone, topotecan, and methotrexate. Although a recent study demonstrated that wild type p53 (wt-p53) may suppress BCRP expression through the nuclear factor-KB (NF-kB) pathway in breast cancer cell line MCF-7, which expresses wt-p53 at low level, the detailed molecular mechanisms of transcriptional regulation on BCRP remain unclear. Here, we set out to reveal the exogenous p53's role on the expression of BCRP. In the human osteosarcoma cell line Saos-2, a p53-null cell line, transient transfection assays showed that the BCRP expression was activated by wt-p53 but not p53 mutants, p53R175H and p53R248W. We further co-transfected the p53 expression plasmid with BCRP luciferasepromoter reporter construct into the Saos-2 cell, and the results revealed that wt-p53 may facilitate the BCRP promoter activity. However, we did not find any p53 binding site by applying Matlnspector. Strikingly, NF-kB activity inhibition downplayed the activation effect of BCRP promoter activity by wt-p53. These results suggested that transcriptional activation of BCRP by wt-p53 is NF-kB- dependent.%乳腺癌耐药蛋白(breast cancer resistance protein,BCRP)是ATP结合盒转运蛋白超家族成员之一,其通过主动外排化疗药物如米托蒽醌、托泊替康和甲氨蝶呤,进而介导肿瘤化疗耐受.最近有研究发现,在野生型p53 (wild type p53,wt-p53)低表达的乳腺癌细胞系MCF-7中,外源性wt-p53通过抑制核转录因子-κB (nuclear factor-κB,NF-κB)的活性进而抑制BCRP的表达,但其详细的分子机制有待进一步阐明.本研究选用p53缺失的骨肉瘤细胞系Saos-2,通过瞬时转染技术发现,wt-p53可以激活BCRP的表达,而突变型p53的激活作用消失;报告基因试验显示,wt-p53可以上调BCRP启动子活性;通过生

  8. High-level expression of wild-type p53 in melanoma cells is frequently associated with inactivity in p53 reporter gene assays.

    Directory of Open Access Journals (Sweden)

    Roland Houben

    Full Text Available BACKGROUND: Inactivation of the p53 pathway that controls cell cycle progression, apoptosis and senescence, has been proposed to occur in virtually all human tumors and p53 is the protein most frequently mutated in human cancer. However, the mutational status of p53 in melanoma is still controversial; to clarify this notion we analysed the largest series of melanoma samples reported to date. METHODOLOGY/PRINCIPAL FINDINGS: Immunohistochemical analysis of more than 180 melanoma specimens demonstrated that high levels of p53 are expressed in the vast majority of cases. Subsequent sequencing of the p53 exons 5-8, however, revealed only in one case the presence of a mutation. Nevertheless, by means of two different p53 reporter constructs we demonstrate transcriptional inactivity of wild type p53 in 6 out of 10 melanoma cell lines; the 4 other p53 wild type melanoma cell lines exhibit p53 reporter gene activity, which can be blocked by shRNA knock down of p53. CONCLUSIONS/SIGNIFICANCE: In melanomas expressing high levels of wild type p53 this tumor suppressor is frequently inactivated at transcriptional level.

  9. The role of p53 tumor suppressor gene in the suppression of teratogenesis. Mechanism of suppression in the embryonic stage by p53-dependent apoptosis

    International Nuclear Information System (INIS)

    This review described the relationships between radiation-induced teratogenesis in the embryonic stage and p53-dependent apoptosis together with recent authors' findings. The p53 tumor suppressor gene in the embryonic and fetal stages: Thymocytes deficient of p53 gene are markedly resistant to radiation. While the survival rate of wild type cells decreased at 1 Gy irradiation, that of the deficient cells hardly changed even at 20 Gy. Starting from these facts, the role of p53 gene in the teratogenesis has been investigated with use of radiation-irradiated wild type and p53-deficient knock-out mice and of mdm2/p53 double knock-out mice. Types of malformation yielded were described. The relationships between radiation-induced teratogenesis and p53 in mouse fetus: Authors performed the following experiment in the p53 knock-out mice to elucidate how p53 participated in the radiation-induced teratogenesis: X-ray at 1 and 2 Gy (250 kVp, 12 mA, 0.5 mm Cu + 1.0 mm Al) was irradiated to the recipient mice at 3.5 days (early nidation) or 9.5 days (organogenesis) of gestation. Malformation in the alive and dead fetuses was observed at 18.5 days and classified according to the p53 genotype. The teratogenesis due to chemicals and radiation in p53 gene deficient mice was discussed. (K.H.)

  10. Escape from p53-mediated tumor surveillance in neuroblastoma: switching off the p14(ARF)-MDM2-p53 axis.

    Science.gov (United States)

    Van Maerken, T; Vandesompele, J; Rihani, A; De Paepe, A; Speleman, F

    2009-12-01

    A primary failsafe program against unrestrained proliferation and oncogenesis is provided by the p53 tumor suppressor protein, inactivation of which is considered as a hallmark of cancer. Intriguingly, mutations of the TP53 gene are rarely encountered in neuroblastoma tumors, suggesting that alternative p53-inactivating lesions account for escape from p53 control in this childhood malignancy. Several recent studies have shed light on the mechanisms by which neuroblastoma cells circumvent the p53-driven antitumor barrier. We review here these mechanisms for evasion of p53-mediated growth control and conclude that deregulation of the p14(ARF)-MDM2-p53 axis seems to be the principal mode of p53 inactivation in neuroblastoma, opening new perspectives for targeted therapeutic intervention. PMID:19779493

  11. p53 alteration in morphologically normal/benign breast tissue in patients with triple-negative high-grade breast carcinomas: breast p53 signature?

    Science.gov (United States)

    Wang, Xi; Stolla, Moritz; Ring, Brian Z; Yang, Qi; Laughlin, Todd S; Rothberg, Paul G; Skinner, Kristin; Hicks, David G

    2016-09-01

    p53 alterations have been identified in approximately 23% of breast carcinomas, particularly in hormone receptor-negative high-grade carcinomas. It is considered to be an early event in breast carcinogenesis. Nevertheless, the putative precursor lesion of high-grade breast carcinoma remains elusive. Breast excision specimens from 93 triple-negative high-grade invasive ductal carcinomas, 48 estrogen receptor (ER)-positive/progesterone receptor-positive/Her2-negative non-high-grade invasive ductal carcinomas, and 50 mammoplasty breasts were selected. At least 2 tissue blocks with tumor and adjacent benign tissue were sectioned and subjected to immunohistochemistry staining for p53. TP53 gene sequencing was performed on select tumors. Further immunohistochemistry staining for ER and Ki-67 was performed on consecutive sections of tissue with p53-positive normal/benign cells. Of the 93 high-grade carcinomas, 51 (55%) were positive for p53 alteration, whereas only 3 (6.25%) of the 48 non-high-grade carcinomas were p53 altered. Focal p53 positivity in adjacent normal/benign breast tissue was identified in 19 cases, and 18 of them also had p53 alteration in their carcinomas. Only 1 case had focal p53 staining in normal/benign tissue, but the tumor was negative for p53 alteration. No p53 staining positivity was identified in the mammoplasty specimens. The p53-stained normal/benign cells were ER negative and did not show an increase in the Ki-67 labeling index. These findings indicate that the p53 staining positivity in normal/benign breast tissue is not a random event. It could be considered as the "p53 signature" in breast and serve as an indicator for future potential risk of p53-positive high-grade breast carcinoma. PMID:27246177

  12. The effect of adenovirus expressing wild-type p53 on 5-fiuorouracil chemosensitivity is related to p53 status in pancreatic cancer cell lines

    Institute of Scientific and Technical Information of China (English)

    Sven Eisold; Michael Linnebacher; Eduard Ryschich; Dalibor Antolovic; Ulf Hinz; Ernst Klar; Jan Schmidt

    2004-01-01

    AIM: There are conflicting data about p53 function on cellular sensitivity to the cytotoxic action of 5-fluorouracil (5-FU).Therefore the objective of this study was to determine the combined effects of adenovirus-mediated wild-type (wt) p53gene transfer and 5-FU chemotherapy on pancreatic cancer cells with different p53 gene status.METHODS: Human pancreatic cancer cell lines Capan-1p53mut,Capan-2p53wt, FAMPACp53mut, PANC1p53mut, and rat pancreatic cancer cell lines ASp53wt and DSL6Ap53null were used for in vitro studies. Following infection with different ratios of Adp53-particles (MOI) in combination with 5-FU, proliferation of tumor cells and apoptosis were quantified by cell proliferation assay (WST-1) and FACS (PI-staining). In addition, DSL6A syngeneic pancreatic tumor cells were inoculated subcutaneously in to Lewis rats for in vivo studies.Tumor size, apoptosis (TUNEL) and survival were determined.RESULTS: Ad-p53 gene transfer combined with 5-FU significantly inhibited tumor cell proliferation and substantially enhanced apoptosis in all four cell lines with an alteration in the p53 gene compared to those two cell lines containing wt-p53. In vivo experiments showed the most effective tumor regression in animals treated with Ad-p53 plus 5-FU. Both in vitro and in vivo analyses revealed that a sublethal dose of Ad-p53 augmented the apoptotic response induced by 5-FU.CONCLUSION: Our results suggest that Ad-p53 may synergistically enhance 5-FU-chemosensitivity most strikingly in pancreatic cancer cells lacking p53 function. These findings illustrate that the anticancer efficacy of this combination treatment is dependent on the p53 gene status of the target tumor cells.

  13. 结肠癌组织中P53基因及其产物变化的研究%Mutation of P53 Gene and Expression of P53 Protein in Colon Cancer

    Institute of Scientific and Technical Information of China (English)

    张玉敏; 尹德霞; 朱桂钱

    2001-01-01

    目的 探索P53基因突变在结肠癌发生过程中的作用.方法应用多聚酶链反应-单纯构象多态分析及免疫组化ABC法研究结肠癌组织中的P53基因及其产物蛋白质的变化.结果结肠癌中有45%发生P53基因突变,52.50% P53蛋白阳性;所获数据经χ2检验.结论对P53基因突变和P53蛋白的检测可作为判断结肠癌生物学行为的重要标志.

  14. Effect of p53 genotype on gene expression profiles in murine liver

    International Nuclear Information System (INIS)

    The tumor suppressor protein p53 is a key regulatory element in the cell and is regarded as the 'guardian of the genome'. Much of the present knowledge of p53 function has come from studies of transgenic mice in which the p53 gene has undergone a targeted deletion. In order to provide additional insight into the impact on the cellular regulatory networks associated with the loss of this gene, microarray technology was utilized to assess gene expression in tissues from both the p53-/- and p53+/- mice. Six male mice from each genotype (p53+/+, p53+/-, and p53-/-) were humanely killed and the tissues processed for microarray analysis. The initial studies have been performed in the liver for which the Dunnett test revealed 1406 genes to be differentially expressed between p53+/+ and p53+/- or between p53+/+ and p53-/- at the level of p ≤ 0.05. Both genes with increased expression and decreased expression were identified in p53+/- and in p53-/- mice. Most notable in the gene list derived from the p53+/- mice was the significant reduction in p53 mRNA. In the p53-/- mice, not only was there reduced expression of the p53 genes on the array, but genes associated with DNA repair, apoptosis, and cell proliferation were differentially expressed, as expected. However, altered expression was noted for many genes in the Cdc42-GTPase pathways that influence cell proliferation. This may indicate that alternate pathways are brought into play in the unperturbed liver when loss or reduction in p53 levels occurs

  15. DNA damage induces p53-dependent BRCA1 nuclear export

    International Nuclear Information System (INIS)

    Full text: Carriers of BRCA1 mutations have an 85% risk of developing breast cancer by age 70. This risk is about 20-fold higher than the general population. BRCA1 functions in multiple DNA damage response pathways, and its functions are regulated by a variety of mechanisms including transcription control, phosphorylation, and protein-protein interactions. Given the critical role of BRCA1 in nucleus, its sub-cellular localization could be an important mechanism in regulating its function. Recent studies showed that BRCA1 is a nuclear-cytoplasmic shuttle protein. It is imported to the nucleus through a nuclear localization signal (NLS)-mediated importing receptor pathway, and exported to cytoplasm via a nuclear export signal (NES)-facilitated CRM1 pathway. However, little is known on how BRCA1 shuttling between the nucleus and cytoplasm is controlled, what cellular process(s) or environmental insult(s) triggers cell to import BRCA1 protein to nucleus and verse visa. In view of the fact that BRCA1 plays critical roles in several DNA damage response pathways, we hypothesized that ionizing radiation-induced DNA damage may affect BRCA1 shuttling. We found that ionizing radiation-induced DNA damage promotes BRCA1 nuclear export in human breast cancer cells through a CRM1-dependent mechanism. We further found that DNA damage-induced BRCA1 nuclear export is dependent on wild-type p53 function. These results suggest that p53-dependent BRCA1 nucleus export might be an alternative mechanism for BRCA1 functional regulation in cellular response to DNA damage. Interruption of BRCA1 shuttling in breast cancer cells that do not have functional p53 may compromise the precise regulation of BRCA1 function timely and spatially, resulting in aberrant DNA repair and increased genetic instability in surviving cells

  16. Rb and p53 gene deletions in lung adenocarcinomas from irradiated and control mice

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Woloschak, G.E. [Argonne National Lab., IL (United States). Center for Mechanistic Biology and Biotechnology

    1997-08-01

    This study was conducted on mouse lung adenocarcinoma tissues that were formalin-treated and paraffin-embedded 25 years ago to investigate the large gene deletions of mRb and p53 in B6CF{sub 1} male mice. A total of 80 lung tissue samples from irradiated mice and 40 lung samples from nonirradiated controls were randomly selected and examined in the mRb portion of this study. The results showed a significant (P < 0.05) higher percentage of mRb deletions in lung adenocarcinomas from mice exposed to 60 once-weekly {gamma}-ray doses than those from mice receiving 24 once-weekly {gamma}-ray doses at low doses and low dose rates; however, the percentage was not significantly different (P > 0.05) from that for spontaneous lung adenocarcinomas or lung adenocarcinomas from mice exposed to single-dose {gamma} irradiation at a similar total dose. mRb fragments 3 (71%) and 5 (67%), the parts of the gene that encoded the pocket binding region of Rb protein to adenovirus E1A and SV40 T-antigen, were the most frequently deleted fragments. p53 gene deletion analysis was carried out on normal lungs and lung adenocarcinomas that were initially found to bear mRb deletions. Exons 1,4,5,6, and 9 were chosen to be analyzed.

  17. Rb and p53 gene deletions in lung adenocarcinomas from irradiated and control mice

    International Nuclear Information System (INIS)

    This study was conducted on mouse lung adenocarcinoma tissues that were formalin-treated and paraffin-embedded 25 years ago to investigate the large gene deletions of mRb and p53 in B6CF1 male mice. A total of 80 lung tissue samples from irradiated mice and 40 lung samples from nonirradiated controls were randomly selected and examined in the mRb portion of this study. The results showed a significant (P 0.05) from that for spontaneous lung adenocarcinomas or lung adenocarcinomas from mice exposed to single-dose γ irradiation at a similar total dose. mRb fragments 3 (71%) and 5 (67%), the parts of the gene that encoded the pocket binding region of Rb protein to adenovirus E1A and SV40 T-antigen, were the most frequently deleted fragments. p53 gene deletion analysis was carried out on normal lungs and lung adenocarcinomas that were initially found to bear mRb deletions. Exons 1,4,5,6, and 9 were chosen to be analyzed

  18. Research advances on the p53 gene network%p53基因调控网络研究进展

    Institute of Scientific and Technical Information of China (English)

    舒坤贤; 王光利; 邬力祥

    2008-01-01

    肿瘤抑制基因p53表达的p53蛋白是一个通用转录因子,与其上、下游功能相关基因组成了一个复杂的基因调控网络,在这个基因网络中p53基因起着关键作用;DNA损伤、缺氧、原癌基因的激活等均能刺激p53基因表达;p53表达升高后,可通过p53-MDM2反馈环路与泛素系统等对p53表达水平进行精确调节;p53通过调控多种下游/靶基因表达完成多种生物学功能,主要包括阻滞细胞周期、促进细胞凋亡、维持基因组稳定性等;认识p53基因调控网络的功能有助于理解p53及其下游/靶基因间的具体作用机制.

  19. DEC1, a Basic Helix-Loop-Helix Transcription Factor and a Novel Target Gene of the p53 Family, Mediates p53-dependent Premature Senescence*

    Science.gov (United States)

    Qian, Yingjuan; Zhang, Jin; Yan, Bingfang; Chen, Xinbin

    2014-01-01

    Cellular senescence plays an important role in tumor suppression. p53 tumor suppressor has been reported to be crucial in cellular senescence. However, the underlying mechanism is poorly understood. In this regard, a cDNA microarray assay was performed to identify p53 targets involved in senescence. Among the many candidates is DEC1, a basic helix-loop-helix transcription factor that has been recently shown to be up-regulated in K-ras-induced premature senescence. However, it is not clear whether DEC1 is capable of inducing senescence. Here, we found that DEC1 is a novel target gene of the p53 family and mediates p53-dependent premature senescence. Specifically, we showed that DEC1 is induced by the p53 family and DNA damage in a p53-dependent manner. We also found that the p53 family proteins bind to, and activate, the promoter of the DEC1 gene. In addition, we showed that overexpression of DEC1 induces G1 arrest and promotes senescence. Moreover, we found that targeting endogenous DEC1 attenuates p53-mediated premature senescence in response to DNA damage. Furthermore, overexpression of DEC1 induces cellular senescence in p53-knockdown cells, albeit to a lesser extent. Finally, we showed that DEC1-induced senescence is p21-independent. Taken together, our data provided strong evidence that DEC1 is one of the effectors downstream of p53 to promote premature senescence. PMID:18025081

  20. Clinicopathological Significance of E-cadherin and PCNA Expression in Hunman Non-small Cell Lung Cancer

    Institute of Scientific and Technical Information of China (English)

    Jianwei Ma; Kai Fan; Yanli Zhang; Dawei Song; Jianmei Ma

    2008-01-01

    OBJECTIVE This study was designed to assess E-cadherin(E-cad) and proliferating cell nuclear antigen (PCNA) expression as well as their clinicopathological significance in hunman non-small cell lung cancers (NSCLCs). Possible molecular mechanisms of differentiation and metastasis of NSCLCs are discussed.METHODS Immunohistochemical and immunofluorescence double staining were performed to examine the expression of E-cad and PCNA in 68 primary NSCLCs cases.RESULTS The E-cad expression in squamous cell carcinomas and adenocarcinomas showed no significant difference. E-cad expression had a positive correlation with the histological-differentiated grade. A significant difference of Ecad expression was found between metastatic and non-metastatic groups. PCNA expression in squamous cell carcinomas and adenocarcinomas showed no significant difference. The PCNA expression had a reverse correlation with the histological-differentiated grade. A significant difference of PCNA expression was found between metastatic and non- metastatic groups. The E-cad and PCNA expression presented a reverse correlation.CONCLUSION E-cad expression is not associated with the histological type of NSCLC, but is associated with differentiation and metastasis of the cancer. Down-regulation of E-cad expression affects the proliferation of cancer cells. Conjoint analysis of E-cad and PCNA expression is a good way to evaluate tumor biological behavior.

  1. Inhibition of p53 transcriptional activity by human cytomegalovirus UL44.

    Science.gov (United States)

    Kwon, Yejin; Kim, Mi-Na; Young Choi, Eun; Heon Kim, Jung; Hwang, Eung-Soo; Cha, Chang-Yong

    2012-05-01

    Human cytomegalovirus (HCMV) stimulates cellular synthesis of DNA and proteins and induces transition of the cell cycle from G(1) to S and G(2) /M phase, in spite of increased amounts of p53 in the infected cells. The immediate early protein IE2-86  kDa (IE86) tethers a transcriptional repression domain to p53; however, its repression of p53 function is not enough to abrogate the G(1) checkpoint function of p53. Other HCMV proteins that suppress the activity of p53 were investigated in this study. Of the HCMV proteins that bind to p53 when assessed by immunoprecipitation and immunoblot analysis, HCMV UL44 was chosen as a candidate protein. It was found that reporter gene containing p53 consensus sequence was activated by transfection with wild type p53, but when plasmids of p53 with IE86 or UL44 were co-transfected, p53 transcriptional activity was decreased to 3-7% of the p53 control in a dose-dependent manner. When the deletion mutant of UL44 was co-transected with p53, the carboxyl one-third portion of UL44 had little effect on inhibition of p53 transcriptional activity. The amount of mRNA p21 was measured in H1299 by real time PCR after transfection of the combination of p53 and UL44 vectors and it was found that p21 transcription by p53 was inhibited dose-dependently by UL44. Increased G0/G1 and decreased S phases in p53 wild type-transfected H1299 cells were recovered to the level of p53 mutant type-transfected ones by the additional transfection of UL44 in a dose-dependent manner. In conclusion, the transcriptional activity of p53 is suppressed by UL44 as well as by IE86. PMID:22376288

  2. p53 modulates the AMPK inhibitor compound C induced apoptosis in human skin cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shi-Wei [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Wu, Chun-Ying [Division of Gastroenterology and Hepatology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Wang, Yen-Ting [Department of Medical Research and Education, Cheng Hsin General Hospital, Taipei, Taiwan (China); Kao, Jun-Kai [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Department of Pediatrics, Children' s Hospital, Changhua Christian Hospital, Changhua, Taiwan (China); Lin, Chi-Chen; Chang, Chia-Che; Mu, Szu-Wei; Chen, Yu-Yu [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Chiu, Husan-Wen [Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan (China); Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan (China); Chang, Chuan-Hsun [Department of Surgical Oncology, Cheng Hsin General Hospital, Taipei, Taiwan (China); Department of Nutrition Therapy, Cheng Hsin General Hospital, Taipei, Taiwan (China); School of Nutrition and Health Sciences, Taipei Medical University, Taipei, Taiwan (China); Liang, Shu-Mei [Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan (China); Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan (China); Chen, Yi-Ju [Department of Dermatology, Taichung Veterans General Hospital, Taichung, Taiwan (China); Huang, Jau-Ling [Department of Bioscience Technology, Chang Jung Christian University, Tainan, Taiwan (China); Shieh, Jeng-Jer, E-mail: shiehjj@vghtc.gov.tw [Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan (China); Department of Education and Research, Taichung Veterans General Hospital, Taichung, Taiwan (China)

    2013-02-15

    Compound C, a well-known inhibitor of the intracellular energy sensor AMP-activated protein kinase (AMPK), has been reported to cause apoptotic cell death in myeloma, breast cancer cells and glioma cells. In this study, we have demonstrated that compound C not only induced autophagy in all tested skin cancer cell lines but also caused more apoptosis in p53 wildtype skin cancer cells than in p53-mutant skin cancer cells. Compound C can induce upregulation, phosphorylation and nuclear translocalization of the p53 protein and upregulate expression of p53 target genes in wildtype p53-expressing skin basal cell carcinoma (BCC) cells. The changes of p53 status were dependent on DNA damage which was caused by compound C induced reactive oxygen species (ROS) generation and associated with activated ataxia-telangiectasia mutated (ATM) protein. Using the wildtype p53-expressing BCC cells versus stable p53-knockdown BCC sublines, we present evidence that p53-knockdown cancer cells were much less sensitive to compound C treatment with significant G2/M cell cycle arrest and attenuated the compound C-induced apoptosis but not autophagy. The compound C induced G2/M arrest in p53-knockdown BCC cells was associated with the sustained inactive Tyr15 phosphor-Cdc2 expression. Overall, our results established that compound C-induced apoptosis in skin cancer cells was dependent on the cell's p53 status. - Highlights: ► Compound C caused more apoptosis in p53 wildtype than p53-mutant skin cancer cells. ► Compound C can upregulate p53 expression and induce p53 activation. ► Compound C induced p53 effects were dependent on ROS induced DNA damage pathway. ► p53-knockdown attenuated compound C-induced apoptosis but not autophagy. ► Compound C-induced apoptosis in skin cancer cells was dependent on p53 status.

  3. 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.

  4. p53 modulates the AMPK inhibitor compound C induced apoptosis in human skin cancer cells

    International Nuclear Information System (INIS)

    Compound C, a well-known inhibitor of the intracellular energy sensor AMP-activated protein kinase (AMPK), has been reported to cause apoptotic cell death in myeloma, breast cancer cells and glioma cells. In this study, we have demonstrated that compound C not only induced autophagy in all tested skin cancer cell lines but also caused more apoptosis in p53 wildtype skin cancer cells than in p53-mutant skin cancer cells. Compound C can induce upregulation, phosphorylation and nuclear translocalization of the p53 protein and upregulate expression of p53 target genes in wildtype p53-expressing skin basal cell carcinoma (BCC) cells. The changes of p53 status were dependent on DNA damage which was caused by compound C induced reactive oxygen species (ROS) generation and associated with activated ataxia-telangiectasia mutated (ATM) protein. Using the wildtype p53-expressing BCC cells versus stable p53-knockdown BCC sublines, we present evidence that p53-knockdown cancer cells were much less sensitive to compound C treatment with significant G2/M cell cycle arrest and attenuated the compound C-induced apoptosis but not autophagy. The compound C induced G2/M arrest in p53-knockdown BCC cells was associated with the sustained inactive Tyr15 phosphor-Cdc2 expression. Overall, our results established that compound C-induced apoptosis in skin cancer cells was dependent on the cell's p53 status. - Highlights: ► Compound C caused more apoptosis in p53 wildtype than p53-mutant skin cancer cells. ► Compound C can upregulate p53 expression and induce p53 activation. ► Compound C induced p53 effects were dependent on ROS induced DNA damage pathway. ► p53-knockdown attenuated compound C-induced apoptosis but not autophagy. ► Compound C-induced apoptosis in skin cancer cells was dependent on p53 status

  5. Shifting p53-induced senescence to cell death by TIS21(/BTG2/Pc3) gene through posttranslational modification of p53 protein.

    Science.gov (United States)

    Choi, Ok Ran; Ryu, Min Sook; Lim, In Kyoung

    2016-09-01

    Cellular senescence and apoptosis can be regulated by p53 activity, although the underlying mechanism of the switch between the two events remains largely unknown. Cells exposed to cancer chemotherapy can escape to senescence phenotype rather than undergoing apoptosis. By employing adenoviral transduction of p53 or TIS21 genes, we observed shifting of p53 induced-senescence to apoptosis in EJ bladder cancer cells, which express H-RasV12 and mutant p53; transduction of p53 increased H-RasV12 expression along with senescence phenotypes, whereas coexpression with TIS21 (p53+TIS21) induced cell death rather than senescence. The TIS21-mediated switch of senescence to apoptosis was accompanied by nuclear translocation of p53 protein and its modifications on Ser-15 and Ser-46 phosphorylation and acetylations on Lys-120, -320, -373 and -382 residues. Mechanistically, TIS21(/BTG2) regulated posttranslational modification of p53 via enhancing miR34a and Bax expressions as opposed to inhibiting SIRT1 and Bcl2 expression. At the same time, TIS21 increased APAF-1 and p53AIP1 expressions, but inhibited the interaction of p53 with iASPP. In vitro tumorigenicity was significantly reduced in the p53+TIS21 expresser through inhibiting micro-colony proliferation by TIS21. Effect of TIS21 on the regulation of p53 activity was confirmed by knockdown of TIS21 expression by RNA interference. Therefore, we suggest TIS21 expression as an endogenous cell death inducer at the downstream of p53 gene, which might be useful for intractable cancer chemotherapy. PMID:27208501

  6. Mutant p53 and ETS2, a Tale of Reciprocity.

    Science.gov (United States)

    Martinez, Luis Alfonso

    2016-01-01

    TP53 is one of the most frequently inactivated tumor suppressor genes in human cancer. However, unlike other tumor suppressor genes whose expression is lost, TP53 is usually inactivated as a result of a single nucleotide change within the coding region. Typically, these single nucleotide mutations result in a codon change that creates an amino acid substitution. Thus, unlike other tumor suppressor genes whose expression is lost due to genetic or epigenetic changes, the p53 gene primarily suffers missense mutations, and therefore, the cells retain and express a mutant form of the p53 protein (mtp53). It is now well established that mtp53 contributes to tumor development through its gain-of-function (GOF) activities. These GOF activities can arise from novel protein-protein interactions that can either disable other tumor suppressors (e.g., p63 and p73) or enable oncogenes such as ETS2, an ETS family member. In this review, I will focus on the identification of the mtp53/ETS2 complex and outline the diverse activities that this transcriptional regulatory complex controls to promote cancer. PMID:26925389

  7. Construction and application of mouse PLJM1-p53-GFP plasmid%p53基因真核表达质粒PLJM1-p53-GFP构建及其应用

    Institute of Scientific and Technical Information of China (English)

    朱伟东; 辛婧; 周苏明; 沈捷; 杜新丽; 张日华; 刘云

    2012-01-01

    Objective:To construct PLJM1-p53-GFP plasmid of mouse p53 gene and study the role of p53 in the prostate cancer cells PC3. Methods:The open reading frame (ORF) of mouse p53 gene was amplified from mouse 3T3-L1 cells by RT-PCR,and inserted into the PLJM1-NRG1-GFP vector. The recombinant plasmid was transformed into DH5a competent E. coli. The positive clones were screened by PCR and the inserts were confirmed by DNA sequencing. The PLJM1-p53-GFP plasmid was transfected into the prostate cancer cells PC3. QPCR was used to detect the efficiency of the transfection. The invasive activity and proliferation of PC3 cells were measured after transfecting the PLJM1-p53-GFP plasmid. Results:DNA sequencing demonstrated that the recombinant plasmid PLJMl-p53-GFP was constructed successfully. The invasive activity and proliferation of PC3 cells were obviously decreased after transfection of the PLJM1-p53-GFP plasmid. Conclusion: The plasmid of PLJM1-p53-GFP of mouse p53 gene was successfully constructed. It can be used in the functional research for cancer.%目的:构建小鼠p53基因真核表达质粒PLJM1-p53-GFP,研究其对前列腺癌细胞株PC3侵袭、增殖能力的影响.方法:从小鼠3T3-L1细胞提取总RNA,经RT-PCR获得cDNA,扩增p53基因,经酶切纯化后的产物与双酶切后的PLJM1-NRG1-GFP慢病毒载体连接,得到PLJM1-p53-GFP慢病毒载体并转化感受态细菌DH5α,通过PCR筛选阳性克隆,抽提质粒并测序鉴定.将PLJM1-p53-GFP质粒瞬时转染到PC3细胞中,提取RNA,定量PCR鉴定p53高表达水平,采用细胞侵袭实验观察高表达p53的前列腺癌细胞株PC3的侵袭能力,采用流式细胞及划痕试验研究p53对前列腺癌细胞株PC3增殖活性的影响.结果:测序证实,目的基因p53插入完全正确且无任何突变;高表达p53的PC3细胞的侵袭能力、增殖能力明显下降.结论:成功构建小鼠p53基因真核表达质粒PLJM1-p53-GFP,为深入研究肿瘤等相关疾病提供了有效的工具.

  8. The p53 tumour suppressor protein is phosphorylated at serine 389 by casein kinase II.

    OpenAIRE

    Meek, D W; Simon , S; Kikkawa, U; Eckhart, W

    1990-01-01

    The entire coding sequence of wild-type mouse p53 was expressed in Escherichia coli under control of the PL promoter of bacteriophage lambda. The bacterial p53 protein had identical mobility to p53 from SV3T3 cells on SDS polyacrylamide gels and was recognized in bacterial lysates by three p53-specific monoclonal antibodies, including PAb246 which is specific for wild-type mouse p53. Immunoprecipitates of the bacterial p53 were phosphorylated by a highly purified preparation of rat casein kin...

  9. The “Two faces” of Tumor Suppressor p53-revisited

    OpenAIRE

    Smith, Martin L.; Kumar, M.A. Suresh

    2010-01-01

    About 15 years ago, several groups including ours had used matched pairs of cell lines carrying wild type or mutant p53 genes to ascertain a role for p53 in cell survival. These were isogenic cell lines differing only by p53 status. The trend at that time was to support p53-mediated apoptosis. Accordingly, p53-wildtype cells were sensitive to DNA damage compared to p53-mutant cells which were thought to evade apoptosis. However, this finding was not universal. In particular, after UV-radiatio...

  10. Abrogation of the Transactivation Activity of p53 by BCCIP Down-regulation*

    OpenAIRE

    Meng, Xiangbing; Yue, Jingyin; Liu, Zhihe; Shen, Zhiyuan

    2006-01-01

    The tumor suppression function of p53 is mostly conferred by its transactivation activity, which is inactivated by p53 mutations in ~50% of human cancers. In cancers harboring wild type p53, the p53 transactivation activity may be compromised by other mechanisms. Identifying the mechanisms by which wild type p53 transactivation activity can be abrogated may provide insights into the molecular etiology of cancers harboring wild type p53. In this report, we show that BCCIP, a BRCA2 and CDKN1A-i...

  11. Illuminating p53 function in cancer with genetically engineered mouse models

    OpenAIRE

    Garcia, Patty B.; Attardi, Laura D.

    2014-01-01

    The key role of the p53 protein in tumor suppression is highlighted by its frequent mutation in human cancers and by the completely penetrant cancer predisposition of p53 null mice. Beyond providing definitive evidence for the critical function of p53 in tumor suppression, genetically engineered mouse models have offered numerous additional insights into p53 function. p53 knock-in mice expressing tumor-derived p53 mutants have revealed that these mutants display gain-of-function activities th...

  12. Negative Regulation-Resistant p53 Variant Enhances Oncolytic Adenoviral Gene Therapy

    OpenAIRE

    Koo, Taeyoung; Choi, Il-Kyu; Kim, Minjung; Lee, Jung-Sun; Oh, Eonju; Kim, Jungho; Yun, Chae-Ok

    2012-01-01

    Intact p53 function is essential for responsiveness to cancer therapy. However, p53 activity is attenuated by the proto-oncoprotein Mdm2, the adenovirus protein E1B 55kD, and the p53 C-terminal domain. To confer resistance to Mdm2, E1B 55kD, and C-terminal negative regulation, we generated a p53 variant (p53VPΔ30) by deleting the N-terminal and C-terminal regions of wild-type p53 and inserting the transcriptional activation domain of herpes simplex virus VP16 protein. The oncolytic adenovirus...

  13. Tumor protein translationally controlled 1 is a p53 target gene that promotes cell survival

    OpenAIRE

    Chen, Weimin; Wang, Huihui; Tao, Shasha; Zheng, Yi; Wu, Wei; Lian, Fangru; Jaramillo, Melba; Fang, Deyu; Zhang, Donna D.

    2013-01-01

    Tumor suppressor p53 maintains genome stability by differentially activating target genes that control diverse cellular responses, such as the antioxidant response, cell cycle arrest and apoptosis. Despite the fact that many p53 downstream genes have been well characterized, novel p53 target genes are continuously being identified. Here, we report that Tpt1 is a direct target gene of p53. We found that p53 upregulates the transcription of Tpt1 and identified a p53-responsive element in the pr...

  14. p53 binding to human genome: crowd control navigation in chromatin context

    OpenAIRE

    Botcheva, Krassimira

    2014-01-01

    p53 is the most studied human protein because of its role in maintaining genomic stability. Binding to genomic targets is essential for transcription-dependent p53 tumor suppression, but how p53 selects targets remains unclear. Here, the impact of chromatin context on p53 genome-wide binding and targets selection is discussed. It is proposed that p53 genomic binding serves not only to regulate transcription, but to sense epigenomic changes threatening the genomic integrity. The problem of p53...

  15. CLCA2, a target of the p53 family, negatively regulates cancer cell migration and invasion

    OpenAIRE

    Sasaki, Yasushi; Koyama, Ryota; Maruyama, Reo; Hirano, Takehiro; Tamura, Miyuki; Sugisaka, Jun; Suzuki, Hiromu; Idogawa, Masashi; Shinomura, Yasuhisa; Tokino, Takashi

    2012-01-01

    The tumor suppressor p53 transcriptionally regulates a number of genes that are involved in cell-cycle inhibition, apoptosis and the maintenance of genetic stability. Recent studies suggest that p53 also contributes to the regulation of cell migration and invasion. Here, we show that human chloride channel accessory-2 (CLCA2) is a target gene of the p53 family (p53, p73 and p63). CLCA2 is induced by DNA damage in a p53-dependent manner. The p53 family proteins activate the CLCA2 promoter by b...

  16. p53 inactivation by point mutations and splice site mutations in human and mouse tumors

    OpenAIRE

    Magnússon, Kristinn P.

    1998-01-01

    The p53 tumor suppressor gene is frequently mutated in human tumors. p53 induces cell cycle arrest and/or apoptosis in response to cellular stress, such as DNA damage, hypoxia and certain activated oncogenes like c-myc. The status of p53 in Burkitt's Iymphoma (BL) cell lines was investigated. The majority of BL lines expressed mutated p53 protein. Functional reconstitution with exogenous wild type (wt) p53 induced apoptosis in a BL line that carried a mutated p53 gene. T...

  17. Regulation of Plasminogen Activator Inhibitor-1 Expression by Tumor Suppressor Protein p53*

    OpenAIRE

    Shetty, Sreerama; Shetty, Praveenkumar; Idell, Steven; Velusamy, Thirunavukkarasu; Bhandary, Yashodhar P.; Shetty, Rashmi S.

    2008-01-01

    H1299 lung carcinoma cells lacking p53 (p53-/-) express minimal amounts of plasminogen activator inhibitor-1 (PAI-1) protein as well as mRNA. p53-/- cells express highly unstable PAI-1 mRNA. Transfection of p53 in p53-/- cells enhanced PAI-1 expression and stabilized PAI-1 mRNA. On the contrary, inhibition of p53 expression by RNA silencing in non-malignant human lung epithelial (Beas2B) cells decreased basal as well as urokinase-type plasminogen activator-induced PAI-...

  18. MdmX Protects p53 from Mdm2-Mediated Degradation

    OpenAIRE

    Jackson, Mark W.; Berberich, Steven J.

    2000-01-01

    The p53 tumor suppressor protein is stabilized in response to cellular stress, resulting in activation of genes responsible for either cell cycle arrest or apoptosis. The cellular pathway for releasing normal cells from p53-dependent cell cycle arrest involves the Mdm2 protein. Recently, a p53-binding protein with homology to Mdm2 was identified and called MdmX. Like Mdm2, MdmX is able to bind p53 and inhibit p53 transactivation; however, the ability of MdmX to degrade p53 has yet to be exami...

  19. Co-mutation of p53, K-ras genes and accumulation of p53 protein and its correlation to clinicopathological features in rectal cancer

    Institute of Scientific and Technical Information of China (English)

    Zhi-Zhong Pan; De-Sen Wan; Gong Chen; Li-Ren Li; Zhen-Hai Lu; Bi-Jun Huang

    2004-01-01

    AIM: To determine the accuracy of p53 gene mutations predicted by overexpression of p53 protein immunohistochemically,and to investigate the co-mutation of p53 and K-rasgenes in rectal cancer and its effect on promoting malignant biologic behaviors of tumors.METHODS: Ninety-seven specimens of rectal cancer were surgically resected in our hospital from August 1996 to October 1997. The hot mutation areas of p53 gene (in exons 5-8) and K-ras gene (in codon 5/12 and 13) were detected with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), and overexpression of p53 protein was detected with immunohistochemistry (IHC) in the 97 specimens of rectal cancer. Correlation between gene mutations and tumor clinicopathologic factors was studied, and survival analysis was penfomed as well.RESULTS: There were 36 cases of p53 gene mutations in 61 p53 protein positive cases, and 21 cases of p53 gene non-mutation in 36 p53 protein negative cases respectively.The coincidence rate of p53 gene mutation by IHC method with PCR-SSCP method was 58.8% (57/97). The mutation rate of p53 gene was 52.6% (51/97), while K-ras gene mutation was observed in codons 12 and 13 in 61 cases with a mutation rate of 62.9% (61/97). Single gene mutation of p53 or K-raswas found in 32 cases. Both p53 and K-ras gene mutation were found in 48 cases. Statistical analysis showed that p53 and K-rasgene mutations were not related to the clinicopathologic factors, including tumor size, gross tumor type, histological classification, differentiation, invasion to intestinal veins, lymphatics and nerves, invasive depth to wall, lymph node metastasis, and Dukes' stages (P>0.05).The survival in patients with no gene mutation, single gene mutation and both gene mutations were similar (P>0.05).CONCLUSION: IHC has a certain false positive and false negative rate in detecting p53 gene mutations. Malignant biological behaviours of rectal cancer are not enhanced by p53 and K-rasgene mutations. Co

  20. Recognition of SUMO-modified PCNA requires tandem receptor motifs in Srs2

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Anthony A.; Mohideen, Firaz; Lima, Christopher D. (SKI)

    2013-04-08

    Ubiquitin (Ub) and ubiquitin-like (Ubl) modifiers such as SUMO (also known as Smt3 in Saccharomyces cerevisiae) mediate signal transduction through post-translational modification of substrate proteins in pathways that control differentiation, apoptosis and the cell cycle, and responses to stress such as the DNA damage response. In yeast, the proliferating cell nuclear antigen PCNA (also known as Pol30) is modified by ubiquitin in response to DNA damage and by SUMO during S phase. Whereas Ub-PCNA can signal for recruitment of translesion DNA polymerases, SUMO-PCNA signals for recruitment of the anti-recombinogenic DNA helicase Srs2. It remains unclear how receptors such as Srs2 specifically recognize substrates after conjugation to Ub and Ubls. Here we show, through structural, biochemical and functional studies, that the Srs2 carboxy-terminal domain harbors tandem receptor motifs that interact independently with PCNA and SUMO and that both motifs are required to recognize SUMO-PCNA specifically. The mechanism presented is pertinent to understanding how other receptors specifically recognize Ub- and Ubl-modified substrates to facilitate signal transduction.

  1. 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.

  2. Research progress on the structure and function of the P53 gene%P53基因与肿瘤的研究进展

    Institute of Scientific and Technical Information of China (English)

    田云鹏

    2013-01-01

    编码P53蛋白的P53基因是最重要的肿瘤抑制基因之一.人类的大多数肿瘤都存在着P53途径的失活.变异的P53不仅不具备肿瘤抑制子的功能,还可能发挥促进肿瘤发生、发展的作用.P53的基本功能是对细胞应激的应答.因此,我们就P53基因的结构和功能做一综述.

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

    International Nuclear Information System (INIS)

    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.

  4. STAT5A is regulated by DNA damage via the tumor suppressor p53.

    Science.gov (United States)

    Mukhopadhyay, Utpal K; Cass, Jamaica; Raptis, Leda; Craig, Andrew W; Bourdeau, Véronique; Varma, Sonal; SenGupta, Sandip; Elliott, Bruce E; Ferbeyre, Gerardo

    2016-06-01

    Here we report that the STAT5A transcription factor is a direct p53 transcriptional target gene. STAT5A is well expressed in p53 wild type cells but not in p53-null cells. Inhibition of p53 reduces STAT5A expression. DNA damaging agents such as doxorubicin also induced STAT5A expression in a p53 dependent manner. Two p53 binding sites were mapped in the STAT5A gene and named PBS1 and PBS2; these sites were sufficient to confer p53 responsiveness in a luciferase reporter gene. Chromatin immunoprecipitation experiments revealed that PBS2 has constitutive p53 bound to it, while p53 binding to PBS1 required DNA damage. In normal human breast lobules, weak p53 staining correlated with regions of intense STAT5A staining. Interestingly, in a cohort of triple negative breast tumor tissues there was little correlation between regions of p53 and STAT5A staining, likely reflecting a high frequency of p53 mutations that stabilize the protein in these tumors. We thus reveal an unexpected connection between cytokine signaling and p53. PMID:26876578

  5. Knockdown of p53 suppresses Nanog expression in embryonic stem cells

    International Nuclear Information System (INIS)

    Highlights: •We investigate the role of p53 in ESCs in the absence of DNA damage. •p53 knockdown suppresses ESC proliferation. •p53 knockdown downregulates Nanog expression. •p53 is essential for mouse ESC self-renewal. -- Abstract: Mouse embryonic stem cells (ESCs) express high levels of cytoplasmic p53. Exposure of mouse ESCs to DNA damage leads to activation of p53, inducing Nanog suppression. In contrast to earlier studies, we recently reported that chemical inhibition of p53 suppresses ESC proliferation. Here, we confirm that p53 signaling is involved in the maintenance of mouse ESC self-renewal. RNA interference-mediated knockdown of p53 induced downregulation of p21 and defects in ESC proliferation. Furthermore, p53 knockdown resulted in a significant downregulation in Nanog expression at 24 and 48 h post-transfection. p53 knockdown also caused a reduction in Oct4 expression at 48 h post-transfection. Conversely, exposure of ESCs to DNA damage caused a higher reduction of Nanog expression in control siRNA-treated cells than in p53 siRNA-treated cells. These data show that in the absence of DNA damage, p53 is required for the maintenance of mouse ESC self-renewal by regulating Nanog expression

  6. Knockdown of p53 suppresses Nanog expression in embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Abdelalim, Essam Mohamed, E-mail: emohamed@qf.org.qa [Qatar Biomedical Research Institute, Qatar Foundation, Doha 5825 (Qatar); Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan); Department of Cytology and Histology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia (Egypt); Tooyama, Ikuo [Molecular Neuroscience Research Center, Shiga University of Medical Science, Setatsukinowa-cho, Otsu, Shiga 520-2192 (Japan)

    2014-01-10

    Highlights: •We investigate the role of p53 in ESCs in the absence of DNA damage. •p53 knockdown suppresses ESC proliferation. •p53 knockdown downregulates Nanog expression. •p53 is essential for mouse ESC self-renewal. -- Abstract: Mouse embryonic stem cells (ESCs) express high levels of cytoplasmic p53. Exposure of mouse ESCs to DNA damage leads to activation of p53, inducing Nanog suppression. In contrast to earlier studies, we recently reported that chemical inhibition of p53 suppresses ESC proliferation. Here, we confirm that p53 signaling is involved in the maintenance of mouse ESC self-renewal. RNA interference-mediated knockdown of p53 induced downregulation of p21 and defects in ESC proliferation. Furthermore, p53 knockdown resulted in a significant downregulation in Nanog expression at 24 and 48 h post-transfection. p53 knockdown also caused a reduction in Oct4 expression at 48 h post-transfection. Conversely, exposure of ESCs to DNA damage caused a higher reduction of Nanog expression in control siRNA-treated cells than in p53 siRNA-treated cells. These data show that in the absence of DNA damage, p53 is required for the maintenance of mouse ESC self-renewal by regulating Nanog expression.

  7. Gene expression profiling analysis reveals arsenic-induced cell cycle arrest and apoptosis in p53-proficient and p53-deficient cells through differential gene pathways

    International Nuclear Information System (INIS)

    Arsenic (As) is a well-known environmental toxicant and carcinogen as well as an effective chemotherapeutic agent. The underlying mechanism of this dual capability, however, is not fully understood. Tumor suppressor gene p53, a pivotal cell cycle checkpoint signaling protein, has been hypothesized to play a possible role in mediating As-induced toxicity and therapeutic efficiency. In this study, we found that arsenite (As3+) induced apoptosis and cell cycle arrest in a dose-dependent manner in both p53+/+ and p53-/- mouse embryonic fibroblasts (MEFs). There was, however, a distinction between genotypes in the apoptotic response, with a more prominent induction of caspase-3 in the p53-/- cells than in the p53+/+ cells. To examine this difference further, a systems-based genomic analysis was conducted comparing the critical molecular mechanisms between the p53 genotypes in response to As3+. A significant alteration in the Nrf2-mediated oxidative stress response pathway was found in both genotypes. In p53+/+ MEFs, As3+ induced p53-dependent gene expression alterations in DNA damage and cell cycle regulation genes. However, in the p53-/- MEFs, As3+ induced a significant up-regulation of pro-apoptotic genes (Noxa) and down-regulation of genes in immune modulation. Our findings demonstrate that As-induced cell death occurs through a p53-independent pathway in p53 deficient cells while apoptosis induction occurs through p53-dependent pathway in normal tissue. This difference in the mechanism of apoptotic responses between the genotypes provides important information regarding the apparent dichotomy of arsenic's dual mechanisms, and potentially leads to further advancement of its utility as a chemotherapeutic agent

  8. Effects of long term exposure to the mycotoxin fumonisin B1 in p53 heterozygous and p53 homozygous transgenic mice.

    Science.gov (United States)

    Bondy, Genevieve; Mehta, Rekha; Caldwell, Don; Coady, Laurie; Armstrong, Cheryl; Savard, Marc; Miller, J David; Chomyshyn, Emily; Bronson, Roni; Zitomer, Nicholas; Riley, Ronald T

    2012-10-01

    The fungal toxin fumonisin B1 (FB1) is a potential human carcinogen based on evidence of renal carcinogenicity in rats and hepatocarcinogenicity in mice. The toxicity and carcinogenicity of FB1 is linked to ceramide synthase inhibition. Based on this mechanism of action and on lack of evidence of genotoxicity, FB1 is considered a non-genotoxic carcinogen. The p53 heterozygous (p53+/-) mouse is a cancer-prone model used for carcinogenesis. The effects of chronic dietary FB1 exposure were characterized in p53+/- mice to confirm non-genotoxicity using a model which is more sensitive to genotoxic than non-genotoxic carcinogens and to clarify the relationship between p53 expression, altered sphingolipid metabolism, and FB1-induced carcinogenesis. Responses to FB1 were similar in p53+/- and p53+/+ mice after 26 weeks exposure to 0, 5, 50 or 150 mg FB1/kg diet, supporting a non-genotoxic mechanism of action. Hepatic adenomas and cholangiomas were observed in mice exposed to 150 mg/kg FB1. For a 10% increase in hepatic megalocytosis, the estimated 95% lower confidence limit of the benchmark dose (BMDL10) ranged from 0.15 and 1.11 mg FB1/kg bw/day. Based on similar responses in p53+/- and p53+/+ mice, p53 and related pathways play a secondary role in responses to FB1 toxicity and carcinogenesis. PMID:22841953

  9. Modulation of p53 activity by IκBα: Evidence suggesting a common phylogeny between NF-κB and p53 transcription factors

    Directory of Open Access Journals (Sweden)

    Gelfand Erwin W

    2005-06-01

    Full Text Available Abstract Background In this work we present evidence that the p53 tumor suppressor protein and NF-κB transcription factors could be related through common descent from a family of ancestral transcription factors regulating cellular proliferation and apoptosis. P53 is a homotetrameric transcription factor known to interact with the ankyrin protein 53BP2 (a fragment of the ASPP2 protein. NF-κB is also regulated by ankyrin proteins, the prototype of which is the IκB family. The DNA binding sequences of the two transcription factors are similar, sharing 8 out of 10 nucleotides. Interactions between the two proteins, both direct and indirect, have been noted previously and the two proteins play central roles in the control of proliferation and apoptosis. Results Using previously published structure data, we noted a significant degree of structural alignment between p53 and NF-κB p65. We also determined that IκBα and p53 bind in vitro through a specific interaction in part involving the DNA binding region of p53, or a region proximal to it, and the amino terminus of IκBα independently or cooperatively with the ankyrin 3 domain of IκBα In cotransfection experiments, κBα could significantly inhibit the transcriptional activity of p53. Inhibition of p53-mediated transcription was increased by deletion of the ankyrin 2, 4, or 5 domains of IκBα Co-precipitation experiments using the stably transfected ankyrin 5 deletion mutant of κBα and endogenous wild-type p53 further support the hypothesis that p53 and IκBα can physically interact in vivo. Conclusion The aggregate results obtained using bacterially produced IκBα and p53 as well as reticulocyte lysate produced proteins suggest a correlation between in vitro co-precipitation in at least one of the systems and in vivo p53 inhibitory activity. These observations argue for a mechanism involving direct binding of IκBα to p53 in the inhibition of p53 transcriptional activity, analogous to

  10. Exclusive Association of p53 Mutation with Super-High Methylation of Tumor Suppressor Genes in the p53 Pathway in a Unique Gastric Cancer Phenotype

    OpenAIRE

    Mina Waraya; Keishi Yamashita; Akira Ema; Natsuya Katada; Shiro Kikuchi; Masahiko Watanabe

    2015-01-01

    Background A comprehensive search for DNA methylated genes identified candidate tumor suppressor genes that have been proven to be involved in the apoptotic process of the p53 pathway. In this study, we investigated p53 mutation in relation to such epigenetic alteration in primary gastric cancer. Methods The methylation profiles of the 3 genes: PGP9.5, NMDAR2B, and CCNA1, which are involved in the p53 tumor suppressor pathway in combination with p53 mutation were examined in 163 primary gastr...

  11. Gain of Cellular Adaptation Due to Prolonged p53 Impairment Leads to Functional Switchover from p53 to p73 during DNA Damage in Acute Myeloid Leukemia Cells*

    OpenAIRE

    Chakraborty, Juni; Banerjee, Shuvomoy; Ray, Pallab; Hossain, Dewan Md Sakib; Bhattacharyya, Sankar; Adhikary, Arghya; Chattopadhyay, Sreya; Das, Tanya; Sa, Gaurisankar

    2010-01-01

    Tumor suppressor p53 plays the central role in regulating apoptosis in response to genotoxic stress. From an evolutionary perspective, the activity of p53 has to be backed up by other protein(s) in case of any functional impairment of this protein, to trigger DNA damage-induced apoptosis in cancer cells. We adopted multiple experimental approaches to demonstrate that in p53-impaired cancer cells, DNA damage caused accumulation of p53 paralogue p73 via Chk-1 that strongly impacted Bax expressi...

  12. p53 polymorphisms associated with mutations in and loss of heterozygosity of the p53 gene in male oral squamous cell carcinomas in Taiwan

    OpenAIRE

    Hsieh, L-L; Huang, T-H; Chen, I-H; Liao, C-T; Wang, H-M; Lai, C-H; Liou, S-H; Chang, J T-C; Cheng, A-J

    2004-01-01

    The present study was designed to examine whether different p53 haplotypes of exon 4–intron 3–intron 6 affect the frequency of mutations and loss of heterozygosity (LOH) of the p53 gene in male oral squamous cell carcinomas (OSCCs) in Taiwan. We found that individuals without two Pro-W-G alleles had significantly higher frequency of p53 mutations than those with two Pro-W-G alleles (odds ratio (OR)=1.98; 95% confidence interval (CI), 1.10–3.56). Out of the 172 p53 gene exon 4 informative male...

  13. Mutant p53 accumulates in cycling and proliferating cells in the normal tissues of p53 R172H mutant mice

    OpenAIRE

    Goh, Amanda M.; Xue, Yuezhen; Leushacke, Marc; LI, LING; Wong, Julin S.; Chiam, Poh Cheang; Rahmat, Siti Aishah Binte; Mann, Michael B.; Mann, Karen M.; Barker, Nick; Lozano, Guillermina; Terzian, Tamara; Lane, David P

    2015-01-01

    The tumour suppressor p53 is regulated primarily at the protein level. In normal tissues its levels are maintained at a very low level by the action of specific E3 ligases and the ubiquitin proteosome pathway. The mutant p53 protein contributes to transformation, metastasis and drug resistance. High levels of mutant p53 can be found in tumours and the accumulation of mutant p53 has previously been reported in pathologically normal cells in human skin. We show for the first time that similarly...

  14. Studies on The Interactions Between NIRF and P53%NIRF对P53蛋白泛素化作用的研究

    Institute of Scientific and Technical Information of China (English)

    段昌柱; 蒲淑萍; TSUTOMU; MORI; HIDEO; KOCHI; 邱宗荫

    2006-01-01

    HEK293和HeLa细胞分别被Np95/ICBP90-like RING finger protein(NIRF)和P53转染后,细胞上清和免疫沉淀产物用SDS-聚丙烯酰胺凝胶电泳免疫印迹法分析;细菌合成GST-P53后,用GST pull-down技术检测NIRF与P53相互作用;在GST-P53、E1、E2和NIRF体外泛素化反应系统中,检测NIRF对P53的体外泛素化.结果表明:NIRF能与P53相互作用,NIRF不仅能与P53特异性结合,而且还会将P53泛素化,这种相互作用在细胞内和细胞外均能发生.推测NIRF可能是P53的一个新的负调节蛋白.

  15. Radiosensitivity in lung cancer with focus on p53

    CERN Document Server

    Bergqvist, M

    2002-01-01

    In Sweden approximately 2800 new lung cancer patients are diagnosed every year. Radiotherapy is used with curative intention in certain groups of patients. The aim of this thesis is to study the basis of differences in radioresistance and the possibility to predict response to radiotherapy. In the first study we investigated, using the comet assay, four lung cancer cell lines with different sensitivity towards radiation. A clear dose-response relationship for radiation-induced DNA single strand and double strand breaks were found. All cell lines showed a remarkably efficient repair of both the DNA single strand and double strand breaks one hour after irradiation. However, further studies in one radioresistant and one radiosensitive cell line demonstrated that repair during the first 15 min had the best accordance with radiosensitivity measured as surviving fraction. In the second and third study, sequencing studies of the p53 gene were performed on cell lines as well as on tumour material. Cell lines that wer...

  16. Regulation of p53 in NIH3T3 mouse fibroblasts following hyperosmotic stress

    DEFF Research Database (Denmark)

    Lambert, Ian Henry; Enghoff, Maria Stine; Brandi, Marie-Luise;

    2015-01-01

    The aim of this project was to analyze the regulation of p53 expression in NIH3T3 fibroblasts under the influence of increasing hyperosmotic stress. Expression of p53 showed a biphasic response pattern in NIH3T3 cells under increasing osmotic stress (337 mOsm to 737 mOsm) with a maximum at 587 m......Osm. Under isotonic conditions p53 expression increased after addition of the proteasome inhibitor MG132 indicating that cellular p53 levels in unperturbed cells is kept low by proteasomal degradation. However, under hypertonic conditions p53 synthesis as well as p53 degradation were significantly reduced...... and it is demonstrated that the increase in p53 expression observed when tonicity is increased from 337 to 587 mOsm reflects that degradation is more inhibited than synthesis, whereas the decrease in p53 expression at higher tonicities reflects that synthesis is more inhibited than degradation. The...

  17. Nerve growth factor receptor negates the tumor suppressor p53 as a feedback regulator

    Science.gov (United States)

    Zhou, Xiang; Hao, Qian; Liao, Peng; Luo, Shiwen; Zhang, Minhong; Hu, Guohui; Liu, Hongbing; Zhang, Yiwei; Cao, Bo; Baddoo, Melody; Flemington, Erik K; Zeng, Shelya X; Lu, Hua

    2016-01-01

    Cancer develops and progresses often by inactivating p53. Here, we unveil nerve growth factor receptor (NGFR, p75NTR or CD271) as a novel p53 inactivator. p53 activates NGFR transcription, whereas NGFR inactivates p53 by promoting its MDM2-mediated ubiquitin-dependent proteolysis and by directly binding to its central DNA binding domain and preventing its DNA-binding activity. Inversely, NGFR ablation activates p53, consequently inducing apoptosis, attenuating survival, and reducing clonogenic capability of cancer cells, as well as sensitizing human cancer cells to chemotherapeutic agents that induce p53 and suppressing mouse xenograft tumor growth. NGFR is highly expressed in human glioblastomas, and its gene is often amplified in breast cancers with wild type p53. Altogether, our results demonstrate that cancers hijack NGFR as an oncogenic inhibitor of p53. DOI: http://dx.doi.org/10.7554/eLife.15099.001 PMID:27282385

  18. Reactivating mutant p53 using small molecules as zinc metallochaperones: awakening a sleeping giant in cancer

    Science.gov (United States)

    Blanden, Adam R.; Yu, Xin; Loh, Stewart N.; Levine, Arnold J.; Carpizo, Darren R.

    2016-01-01

    Tumor protein p53 (TP53) is the most commonly mutated gene in human cancer. The majority of mutations are missense, and generate a defective protein that is druggable. Yet, for decades, the small-molecule restoration of wild-type (WT) p53 function in mutant p53 tumors (so-called p53 mutant ‘reactivation’) has been elusive to researchers. The p53 protein requires the binding of a single zinc ion for proper folding, and impairing zinc binding is a major mechanism for loss of function in missense mutant p53. Here, we describe recent work defining a new class of drugs termed zinc metallochaperones that restore WT p53 structure and function by restoring Zn2+ to Zn2+-deficient mutant p53. PMID:26205328

  19. Mitochondrial localization of the low level p53 protein in proliferative cells

    International Nuclear Information System (INIS)

    p53 protein plays a central role in suppressing tumorigenesis by inducing cell cycle arrest or apoptosis through transcription-dependent and -independent mechanisms. Emerging publications suggest that following stress, a fraction of p53 translocates to mitochondria to induce cytochrome c release and apoptosis. However, the localization of p53 under unstressed conditions remains largely unexplored. Here we show that p53 is localized at mitochondria in absence of apoptotic stimuli, when cells are proliferating, localization observed in various cell types (rodent and human). This is also supported by acellular assays in which p53 bind strongly to mitochondria isolated from rat liver. Furthermore, the mitochondria subfractionation study and the alkaline treatment of the mitochondrial p53 revealed that the majority of mitochondrial p53 is present in the membranous compartments. Finally, we identified VDAC, a protein of the mitochondrial outer-membrane, as a putative partner of p53 in unstressed/proliferative cells.

  20. Loss of p19(Arf facilitates the angiogenic switch and tumor initiation in a multi-stage cancer model via p53-dependent and independent mechanisms.

    Directory of Open Access Journals (Sweden)

    Danielle B Ulanet

    Full Text Available The Arf tumor suppressor acts as a sensor of oncogenic signals, countering aberrant proliferation in large part via activation of the p53 transcriptional program, though a number of p53-independent functions have been described. Mounting evidence suggests that, in addition to promoting tumorigenesis via disruptions in the homeostatic balance between cell proliferation and apoptosis of overt cancer cells, genetic alterations leading to tumor suppressor loss of function or oncogene gain of function can also incite tumor development via effects on the tumor microenvironment. In a transgenic mouse model of multi-stage pancreatic neuroendocrine carcinogenesis (PNET driven by inhibition of the canonical p53 and Rb tumor suppressors with SV40 large T-antigen (Tag, stochastic progression to tumors is limited in part by a requirement for initiation of an angiogenic switch. Despite inhibition of p53 by Tag in this mouse PNET model, concomitant disruption of Arf via genetic knockout resulted in a significantly accelerated pathway to tumor formation that was surprisingly not driven by alterations in tumor cell proliferation or apoptosis, but rather via earlier activation of the angiogenic switch. In the setting of a constitutional p53 gene knockout, loss of Arf also accelerated tumor development, albeit to a lesser degree. These findings demonstrate that Arf loss of function can promote tumorigenesis via facilitating angiogenesis, at least in part, through p53-independent mechanisms.

  1. Relation between p53 (exon 7) mutation and p53 overexpression in human cervical cancers%宫颈癌p53外显子7突变与p53蛋白高表达的关系

    Institute of Scientific and Technical Information of China (English)

    张娜; 李惠芳; 常艳丽; 梁莎

    2001-01-01

    目的探讨宫颈癌p53外显子7突变与p53蛋白高表达的关系。方法采用免疫组织化学、聚合酶链反应(PCR)、限制性酶解片段长度多态性(RFLP)分析等方法对49例宫颈癌组织石蜡包埋标本中p53外显子7的突变与p53蛋白表达进行了检测。结果 p53外显子7的突变率8.2%(4/49)显著低于p53蛋白阳性率49.0%(24/49)(χ2=18.05,P<0.001);p53外显子7突变不一定p53蛋白阳性。结论 p53外显子7突变可能是部分宫颈癌变的一个重要因素;大部分宫颈癌可能主要由于高危人乳头状瘤病毒(HPV)感染后,通过E6/p53蛋白复合物的形成使p53蛋白失活所致。%Objective To investigate the relation between p53 (exon 7) mutations and p53 overexpression in human cervical cancer.Methods p53 (exon 7) mutation and p53 overexpression were examined by immunohistochemistry,polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis in 49 cases of cervical cancers on their paraffin-embedded tissue specimens.Results There was significant difference between p53 (exon 7) mutation 4/49 (8.2%) and p53 overexpression 24/49 (49.0%) in cervical cancer (χ2=18.05,P<0.001);not all cases of p53 mutation had p53 protein positive.Conclusion The p53 (exon 7) mutation is an important factor in part of cervical cancers,but anomalous structure and inactivation of p53 proteins caused by E6/p53 protein complex formed in high risk HPV infection are the significant cause of the greater part of cervical cancers.

  2. The role and prognostic significance of p53 mutation in colorectal carcinomas

    Institute of Scientific and Technical Information of China (English)

    Chen Yang Ji; DR Smith; HS Goh

    2000-01-01

    AIM To study the prognostic significance of the p53 cDNA mutation and mutant p53 protein in colorectaladenocarcinomas.METHODS p53 cDNA mutaiton was detected with RT-PCR-SSCP, and mutant p53 protein overexpressionwas detected by PAb 240 monoclonal antibody in 100 cases of colorectal adenocarcinomas. The follow-upsurvey of all patients were done within the five years after operation, and comparing with p53 cDNAmutation and mutant p53 protein overexpression for the prognostic significance of colorectaladenocarcinomas. The data is treated with SPSS computer program, Kaplan-Meier Survival Plots werecalculated and analyzed by Log-rank analysis.RESULTS Fifty-one cases of p53 eDNA mutations (51%) were found with RT-PCR-SSCP and 76 cases ofmutant p53 protein overexpression (76%) found with PAb 240 monoclonal antibody immunohistochemistrystaining in 100 cases of colorectal adenocarcinomas. There are no relationship with Dukes stage in thestatistics in p53 eDNA mutation (mutation: Dukes A 9%, B 10%, C 20%, D 12%; No mutation: A 13%, B12%, C 12%, D 12%) and mutant p53 protein overexpression (positive: Dukes A 17%, B 6%, C 27%, D16%; negative: A 5%, B 6%, C 5%, D 8%) (P<0.05). Moreover, the data show p53 cDNA mutation isassociated with mutant p53 protein overexpression (both positive 49%, single positive 29%, both negative22%) (P<0.01), p53 eDNA mutation can provide prognostic information (p53 eDNA mutation positive:alive 35, dead 16; negative: alive 42, dead 7) (P<0.05), and mutant p53 protein overexpression isambiguous and does not assess prognosis (p53 protein overexpression positive: alive 58, dead 18; negative:alive 19, dead 5) (P = 0.72) with Kaplan-Meier Survival Plots and Log-rank analysis.CONCLUSION p53 eDNA mutation is associated with mutant p53 protein overexpression (p53 eDNAmutation and mutant p53 protein overexpression both positive 49%, single positive 29%, both negative 22%)(P<0.01) and p53 eDNA mutation can provide poor prognostic information, and is the

  3. Human papillomavirus 18 E6 inhibits phosphorylation of p53 expressed in HeLa cells

    Directory of Open Access Journals (Sweden)

    Ajay Amrendra K

    2012-01-01

    Full Text Available Abstract Background In HPV infected cells p53 function is abrogated by E6 and even ectopically expressed p53 is unable to perform tumor suppressor functions. In addition to facilitating its degradation, E6 may also inhibit p53 transactivity, though the mechanisms are still poorly understood. It has been reported that inhibition of p300, an acetyltransferase responsible for p53 acetylation is inactivated by E6. Activation of overexpressed p53 to cause cell growth inhibition is facilitated by its phosphorylation. Previously, we reported that non-genotoxically overexpressed p53 in HeLa cells needs to be phosphorylated to perform its cell growth inhibitory functions. Since over expressed p53 by itself was not activated, we hypothesized an inhibitory role for E6. Results Majority of reports proposes E6 mediated degradation of p53 as a possible reason for its inactivation. However, results presented here for the first time demonstrate that overexpressed p53 is not directly associated with E6 and therefore free, yet it is not functionally active in HPV positive cells. Also, the stability of overexpressed p53 does not seem to be an issue because inhibition of proteasomal degradation did not increase the half-life of overexpressed p53, which is more than endogenous p53. However, inhibition of proteasomal degradation prevents the degradation of endogenous p53. These findings suggest that overexpressed p53 and endogenous p53 are differentially subjected to proteasomal degradation and the reasons for this discrepancy remain unclear. Our studies demonstrate that p53 over expression has no effect on anchorage independent cell-growth and E6 nullifies its cell growth inhibitory effect. E6 overexpression abrogates OA induced p53 occupancy on the p21 promoter and cell death as well. E6 did not decrease p53 protein but phospho-p53 level was significantly reduced. Conclusion We report for the first time that E6 de-activates p53 by inhibiting its phosphorylation

  4. Def defines a conserved nucleolar pathway that leads p53 to proteasome-independent degradation

    OpenAIRE

    Tao, Ting; Hui SHI; Guan, Yihong; Huang, Delai; Chen, Ye; Lane, David P; Chen, Jun; Peng, Jinrong

    2013-01-01

    p53 protein turnover through the ubiquitination pathway is a vital mechanism in the regulation of its transcriptional activity; however, little is known about p53 turnover through proteasome-independent pathway(s). The digestive organ expansion factor (Def) protein is essential for the development of digestive organs. In zebrafish, loss of function of def selectively upregulates the expression of p53 response genes, which raises a question as to what is the relationship between Def and p53. W...

  5. Clinical Significance of Mutant P53 Protein Expression in Lung Adenocarcinoma

    OpenAIRE

    Chun’an BIAN; Li, Zhongyou; Youtao XU; Wang, Jie; Xu, Lin; Shen, Hongbing

    2015-01-01

    Background and objective P53 is a tumor protein that acts as a tumor suppressor. The mutation of P53 may cause loss of tumor suppressor functions and gain of functions favoring cellular proliferation and apoptosis inhibition. The clinical implications of the tumor protein P53 gene (TP53) mutation in lung adenocarcinoma are indefinite. The aim of this study is to explore the clinical significance of the mutant P53 protein expression in lung adenocarcinoma tissues. Methods The clinicopathologic...

  6. New tricks of an old molecule: lifespan regulation by p53

    OpenAIRE

    Bauer, Johannes H.; HELFAND, STEPHEN L.

    2006-01-01

    As guardian of the genome the tumor suppressor p53 controls a crucial point in protection from cellular damage and response to stressors. Activation of p53 can have beneficial (DNA repair) or detrimental (apoptosis) consequences for individual cells. In either case activation of p53 is thought to safeguard the organism at large from the deleterious effects of various stresses. Recent data suggest that the function of p53 might also play a role in the regulation of organismal lifespan. Increas...

  7. p53 Mutations and Protein Overexpression in Primary Colorectal Cancer and its Liver Metastasis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To compare p53 status in primary and hepatic metastatic colorectal cancer in 34 patients. Methods: p53 gene status (exons 5- 9) was examined by PCR, denaturing gradient gel electrophoresis (DGGE) and automated sequencing. P53 protein was detected by immunohistochemistry using monoclonal antibody DO-7. Results: p53 mutations were found in exons 5 through 9 in 21 of 34 patients (61.8%). Among them, 5 patients had mutation in liver metastasis but not in their primary tumors while in the other patients the same mutations were found in both primary and metastatic colorectal cancers. In no patients was p53 mutation exclusively found in the primary colorectal tumors. Moreover, additional mutation was detected in the metastatic lesions in two cases. Of the 37 mutations within the exons examined, 73% was missense mutation and 16% was nonsense mutation. There were 4 microinsertions. P53 protein was overexpressed in both primary and metastatic colorectal cancers with p53 gene mutations. The presence of p53 mutation significantly correlated with p53 protein accumulation (r=0.96, p< 0.001). However, in 4 patients with p53 nonsense mutation, immunohistochemical staining was negative. In three patients who showed no p53 mutation of the primary tumor, p53 protein was consistently overexpressed. Conclusion: In colorectal cancers, p53 gene mutation usually appears first in the primary tumor and maintains as such but is more prominent when metastasized to the liver. However, p53 gene mutation may occur only after being metastasized.Although p53 gene mutation and p53 protein overexpression correlate with each other, either parameter examined alone may lead to false positive or negative results.

  8. Expression of p53 and CD44 in Canine Breast Tumor

    Institute of Scientific and Technical Information of China (English)

    LIU Yun; CUI Wen; CHENG Xi; FENG Xinchang

    2008-01-01

    The p53 and CD44 expression of 10 cases in canine breast tumor were examined utilizing immunohistochemical assay with rabbit anti-mouse polyclonal antibodies against p53 or CD44,respectively.The p53 expression was significantly higher in malignant than in benign breast tumor.The expression of CD44 was not significantly different in malignant breast cancer and benign breast tumor.This suggests that p53 can be used as an indicator for animal prognosis.

  9. Interaction of hepatitis B virus with tumor suppressor gene p53: its significance and biological function

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The mechanism of the interaction of hepatitis B virus (HBV) with tumor suppressor p53 and its role in the hepatocarcinogenesis have been studied by PCR-directed sequencing, gel shift assays and in situ ultraviolet cross-linking assay. The biological function of the interaction of HBV with p53 gene was investigated by co-transfection of chloramphenicol acetyltransferase (CAT) reporter gene, p53 and HBV DNA, and quantitative PCR. Among the 16 primary hepatocellular carcinoma (PHC) samples, 13 were HBV-DNA positive,10 HBxAg positive and 9 p53 protein positive. The p53 gene point mutation was found in 5 samples, one of which had a G to T substitution located at codon 249. After analyzing the HBV genome by a computer program, a p53 response element binding sequence was found in HBV genome at upstream of enhancer I, from 1047 to 1059 nucleotides. This sequence could specifically bind to p53 protein, increase p53 protein accumulation in the PHC cells and stimulate the transactivating activity of p53 and HBV replication .The results also revealed that HBxAg could combine with p53 protein to form a complex in the cells and enhance CAT expression. Immunocytochemical staining showed that p53 protein complex was located in the cytoplasm and the process of p53 entry to nuclei was, in part, blocked. From our results, we conclude that the mutation of p53 gene at codon 249 is infrequent in HBV-associated PHC, the DNA-protein binding between HBV and p53, and the protein-protein binding between HBxAg and p53 might lead to the reduction or inactivation of p53 protein, which in turn resulting in HBV-associated hepatocarcinogenesis.

  10. p53 immunoreaction in endoscopic biopsy specimens of colorectal cancer, and its prognostic significance.

    OpenAIRE

    A. Yamaguchi; Nakagawara, G.; Kurosaka, Y.; Nishimura, G.; Yonemura, Y.; Miyazaki, I.

    1993-01-01

    The expression of p53 protein was immunohistochemically studied in formalin-fixed paraffin-embedded biopsy specimens of 203 colorectal carcinomas by use of a monoclonal antibody specific for the p53 protein. PAb1801. p53 protein expression with its reactivity localised in nuclei was found in 121 (59.6%) of the cancers. There was no correlation of p53 immunoreactivity with histological classification, wall invasion, lymphatic invasion, venous invasion, lymph node metastases, or peritoneal meta...

  11. p53 increases MHC class I expression by upregulating the endoplasmic reticulum aminopeptidase ERAP1

    OpenAIRE

    Wang, Bei; Niu, Dandan; Lai, Liyun; Ren, Ee Chee

    2013-01-01

    The p53 tumour suppressor has an important role in cancer cells. Here we show that p53 regulates expression of major histocompatibility complex I on the cell surface. We show that the tumour cell line HCT116, which lacks p53 exhibits significantly lower major histocompatibility complex I expression than its wild-type counterpart. Using a combination of chromatin immunoprecipitation sequencing and gene expression analysis, we demonstrate that p53 upregulates expression of endoplasmic reticulum...

  12. Nuclear accumulation and activation of p53 in embryonic stem cells after DNA damage

    OpenAIRE

    Rolletschek Alexandra; Solozobova Valeriya; Blattner Christine

    2009-01-01

    Abstract Background P53 is a key tumor suppressor protein. In response to DNA damage, p53 accumulates to high levels in differentiated cells and activates target genes that initiate cell cycle arrest and apoptosis. Since stem cells provide the proliferative cell pool within organisms, an efficient DNA damage response is crucial. Results In proliferating embryonic stem cells, p53 is localized predominantly in the cytoplasm. DNA damage-induced nuclear accumulation of p53 in embryonic stem cells...

  13. Conformational stabile p53 mutants retain specific DNA binding capacity but lost transactivation function

    Czech Academy of Sciences Publication Activity Database

    Brázda, Václav; Brázdová Jagelská, Eva; Fojta, Miroslav

    Akko, 2009. s. 45. [International p53 Marathon , 4th International Workshop on Mutant p53 „In vivo effects of mutant p53: experimental data, animal models, clinical consequences“. 17.03.2009-29.03.2009, Akko] R&D Projects: GA ČR(CZ) GP301/07/P160 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : p53 mutants * conformation of the mutant * MAbs Subject RIV: BO - Biophysics

  14. Translational regulation of p53 as a potential tumor therapy target

    NARCIS (Netherlands)

    B. Schumacher (Björn); A. Gartner (Anton)

    2006-01-01

    textabstractThe tumor suppressor p53 is a central player in apoptosis induction in response to oncogenic stimuli and DNA damage. As activation of p53 has been suggested as a prime strategy for future tumor therapy, inhibition of negative regulators of p53 activity would be a similarly desirable stra

  15. Dysfunctional p53 deletion mutants in cell lines derived from Hodgkin's lymphoma

    DEFF Research Database (Denmark)

    Feuerborn, Alexander; Moritz, Constanze; von Bonin, Frederike;

    2006-01-01

    transcriptional activity of p53. Transcriptional inactivity was also found for p53 in L428 cells. This study characterizes mutations in TP53 transcripts within cHL cell lines with associated functional defects in the resulting p53 proteins and therefore reintroduces the concept that mutations of TP53 might be...

  16. Out of the jaws of death: PRMT5 steers p53

    OpenAIRE

    Berger, Shelley L.

    2008-01-01

    The tumour suppressor p53 triggers either cell-cycle arrest or apoptosis. Now, arginine methylation joins a panoply of other post-translational modifications that regulate p53. PRMT5 mediates p53 methylation, which disposes the cell to arrest rather than death.

  17. A mathematical model of a P53 oscillation network triggered by DNA damage

    International Nuclear Information System (INIS)

    Taking the interaction between a DNA damage repair module, an ATM module, and a P53–MDM2 oscillation module into account, this paper presents a mathematical model of a P53 oscillation network triggered by a DNA damage signal in individual cells. The effects of the DNA damage signal and the delay time of P53-induced MDM2 expression on the behaviours of the P53 oscillation network are studied. In the oscillatory state of the P53–MDM2 oscillator, it is found that the pulse number of P53–P oscillation increases with the increase of the initial DNA damage signal, whereas the amplitude and the period of P53–P oscillation are fixed for different initial DNA damage signals, and the period numbers of P53–P oscillations decrease with the increase of time delay of MDM2 expression induced by P53. These theoretical predictions are consistent with previous experimental results. The combined negative feedback of P53–MDM2 with the time delay of P53-induced MDM2 expression causes oscillation behaviour in the P53 network. (general)

  18. Loss of p53 Ser18 and Atm results in embryonic lethality without cooperation in tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Heather L Armata

    Full Text Available Phosphorylation at murine Serine 18 (human Serine 15 is a critical regulatory process for the tumor suppressor function of p53. p53Ser18 residue is a substrate for ataxia-telangiectasia mutated (ATM and ATM-related (ATR protein kinases. Studies of mice with a germ-line mutation that replaces Ser18 with Ala (p53(S18A mice have demonstrated that loss of phosphorylation of p53Ser18 leads to the development of tumors, including lymphomas, fibrosarcomas, leukemia and leiomyosarcomas. The predominant lymphoma is B-cell lymphoma, which is in contrast to the lymphomas observed in Atm(-/- animals. This observation and the fact that multiple kinases phosphorylate p53Ser18 suggest Atm-independent tumor suppressive functions of p53Ser18. Therefore, in order to examine p53Ser18 function in relationship to ATM, we analyzed the lifespan and tumorigenesis of mice with combined mutations in p53Ser18 and Atm. Surprisingly, we observed no cooperation in survival and tumorigenesis in compound p53(S18A and Atm(-/- animals. However, we observed embryonic lethality in the compound mutant animals. In addition, the homozygous p53Ser18 mutant allele impacted the weight of Atm(-/- animals. These studies examine the genetic interaction of p53Ser18 and Atm in vivo. Furthermore, these studies demonstrate a role of p53Ser18 in regulating embryonic survival and motor coordination.

  19. Defective accumulation of p53 protein in x-irradiated human tumor cells with low proteasome activity

    International Nuclear Information System (INIS)

    Full text: We established p53-inducible clones, 99-p53 His, by transfecting an ecdyson-inducible vector containing the wild type p53 gene into p53-null H1299, a human non-small cell lung carcinoma cell line. In contrast to normal human diploid cells, in which p53 is accumulated after X-irradiation, the level of p53 protein did not change following 4 Gy of X-rays. We found that phosphorylation of p53 at Ser15 and Ser20 was induced similarly between 99-p53 His cells and normal human cells. However, p53 was more resistant to degradation in 99-p53 His cells, and its level did not change after treatment with cycloheximide, a protein synthesis inhibitor, while p53 protein in normal human cells was degraded rapidly. Furthermore, proteasome inhibitors, ALLN, MG115, and MG132 accumulated p53 protein significantly in normal human cells, but there was no accumulation of p53 protein in 99-p53 His cells. These results indicate that DNA damage signaling through ATM is functional in 99-p53 His cells, but they have defect in p53 degradation pathway. Thus, low proteasome activity in 99-p53 His cells could be a reason for the defective accumulation of p53 protein following X-irradiation. Present study shows that proteasome activity is an important determinant of p53 stability, when the wild-type p53 gene is expressed in p53-null cancer cells

  20. Developmental abnormalities induced by X-irradiation in P53 deficient or heterozygous mice

    International Nuclear Information System (INIS)

    Full text: In order to assess the influence of a p53 mutation on radiation-induced developmental effects, males heterozygous for the p53 mutation (mimicking the human Li-Fraumeni syndrome) were crossed with C57BL females. Their heterozygous p53+/- progeny was mated with each other, in order to obtain p53+/- (50%), p53-/- (25 %) and p53+/+ (25 %) embryos. Pregnant females were X-irradiated with 0.5 Gy on days 1 (pre-implantation period), 8 or 11 (organogenesis period) of gestation. Dissection of the pregnant females occurred on day 19 of gestation. P53 genotype was determined by PCR from small pieces of soft foetal tissues. In non-irradiated animals, slightly less p53-/- foetuses were found upon dissection than expected, probably reflecting a predominant elimination of these embryos during gestation. Exencephaly was the only external malformation found in foetuses from non-irradiated females, affecting as much as 5 of the 91 living foetuses of this series. Four of those were p53-/- and one was p53+/-. In animals irradiated on day 1 of pregnancy, prenatal mortality was increased, predominantly affecting the p53-/- embryos. Among the 100 living foetuses obtained in this series, 2 showed exencephaly, both of them being p53-/-. This lower frequency of malformed foetuses compared to non-irradiated animals could be due to an increased elimination of p53-/- foetuses or embryos after irradiation. The proportion of living p53-/- foetuses that were obtained after irradiation on day 8 was also lower than expected, and elimination preferentially affected female foetuses. Malformations were twice as frequent as in the non-irradiated group, and predominantly affected female foetuses (73%). Abnormal foetuses were either p53-/- (6/94) or p53+/- (5/94). Interestingly, in addition to exencephaly, other various external malformations were found in this group, including cephalic oedema, gastroschisis, polydactyly and cleft palate. In foetuses irradiated on day 11 of their development

  1. Molecular structure and biological function of proliferating cell nuclear antigen

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Proliferating cell nuclear antigen (PCNA) is the core component of replication complex in eukaryote.As a processive factor of DNA polymerase delta, PCNA coordinates the replication process by interacting with various replication proteins. PCNA appears to play an essential role in many cell events, such as DNA damage repair, cell cycle regulation, and apoptosis, through the coordination or organization of different partners. PCNA is an essential factor in cell proliferation, and has clinical significance in tumor research. In this article we review the functional structure of PCNA, which acts as a function switch in different cell events.

  2. 在应答DNA损伤时P53的翻译后修饰

    Institute of Scientific and Technical Information of China (English)

    郝春燕; 苏海翔

    2001-01-01

    肿瘤抑制基因p53在肿瘤发生中发挥着重要作用,翻译后修饰是调节P53蛋白水平及活性的主要方式之一.癌基因mdm2编码的Mdm2蛋白是p53的负性调节因子,它可通过调节p53的稳定性来调节P53蛋白的水平.在应答DNA损伤时,P53的翻译后修饰可抑制P53和Mdm2的相互作用,使其半衰期延长,P53水平升高.P53N-末端具有多个可磷酸化的位点,这些位点的磷酸化可抑制P53与Mdm2的相互作用,使P53水平和转录活性升高.而P53 C-末端位点的磷酸化可激活P53与特异序列DNA结合的潜能;且C-末端某些位点的乙酰化亦可激活P53与DNA结合的潜能,进而调节P53的水平及活性.

  3. 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.

  4. Genome-scale functional analysis of the human genes modulating p53 activity by regulating MDM2 expression in a p53-independent manner.

    Science.gov (United States)

    Kim, Dong Min; Choi, Seung-Hyun; Yeom, Young Il; Min, Sang-Hyun; Kim, Il-Chul

    2016-09-16

    MDM2, a critical negative regulator of p53, is often overexpressed in leukemia, but few p53 mutations are found, suggesting that p53-independent MDM2 expression occurs due to alterations in MDM2 upstream regulators. In this study, a high MDM2 transcription level was observed (41.17%) regardless of p53 expression in patient with acute myeloid leukemia (AML). Therefore, we performed genome-scale functional screening of the human genes modulating MDM2 expression in a p53-independent manner. We searched co-expression profiles of genes showing a positive or negative pattern with MDM2 expression in a DNA microarray database, selected1089 links, and composed a screening library of 368 genes. Using MDM2 P1 and P2 promoter-reporter systems, we screened clones regulating MDM2 transcriptions in a p53-independent manner by overexpression. Nine clones from the screening library showed enhanced MDM2 promoter activity and MDM2 expression in p53-deficient HCT116 cells. Among them, six clones, including NTRK2, GNA15, SFRS2, EIF5A, ELAVL1, and YWHAB mediated MAPK signaling for expressing MDM2. These results indicate that p53-independent upregulation of MDM2 by increasing selected clones may lead to oncogenesis in AML and that MDM2-modulating genes are novel potential targets for AML treatment. PMID:27524244

  5. Structural Basis of Competitive Recognition of p53 and MDM2 by HAUSP/USP7: Implications for the Regulation of the p53-MDM2 Pathway.

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Herpesvirus-associated ubiquitin-specific protease (HAUSP, also known as USP7, a deubiquitylating enzyme of the ubiquitin-specific processing protease family, specifically deubiquitylates both p53 and MDM2, hence playing an important yet enigmatic role in the p53-MDM2 pathway. Here we demonstrate that both p53 and MDM2 specifically recognize the N-terminal tumor necrosis factor-receptor associated factor (TRAF-like domain of HAUSP in a mutually exclusive manner. HAUSP preferentially forms a stable HAUSP-MDM2 complex even in the presence of excess p53. The HAUSP-binding elements were mapped to a peptide fragment in the carboxy-terminus of p53 and to a short-peptide region preceding the acidic domain of MDM2. The crystal structures of the HAUSP TRAF-like domain in complex with p53 and MDM2 peptides, determined at 2.3-A and 1.7-A resolutions, respectively, reveal that the MDM2 peptide recognizes the same surface groove in HAUSP as that recognized by p53 but mediates more extensive interactions. Structural comparison led to the identification of a consensus peptide-recognition sequence by HAUSP. These results, together with the structure of a combined substrate-binding-and-deubiquitylation domain of HAUSP, provide important insights into regulation of the p53-MDM2 pathway by HAUSP.

  6. Aspirin acetylates wild type and mutant p53 in colon cancer cells: identification of aspirin acetylated sites on recombinant p53.

    Science.gov (United States)

    Ai, Guoqiang; Dachineni, Rakesh; Kumar, D Ramesh; Marimuthu, Srinivasan; Alfonso, Lloyd F; Bhat, G Jayarama

    2016-05-01

    Aspirin's ability to inhibit cell proliferation and induce apoptosis in cancer cell lines is considered to be an important mechanism for its anti-cancer effects. We previously demonstrated that aspirin acetylated the tumor suppressor protein p53 at lysine 382 in MDA-MB-231 human breast cancer cells. Here, we extended these observations to human colon cancer cells, HCT 116 harboring wild type p53, and HT-29 containing mutant p53. We demonstrate that aspirin induced acetylation of p53 in both cell lines in a concentration-dependent manner. Aspirin-acetylated p53 was localized to the nucleus. In both cell lines, aspirin induced p21(CIP1). Aspirin also acetylated recombinant p53 (rp53) in vitro suggesting that it occurs through a non-enzymatic chemical reaction. Mass spectrometry analysis and immunoblotting identified 10 acetylated lysines on rp53, and molecular modeling showed that all lysines targeted by aspirin are surface exposed. Five of these lysines are localized to the DNA-binding domain, four to the nuclear localization signal domain, and one to the C-terminal regulatory domain. Our results suggest that aspirin's anti-cancer effect may involve acetylation and activation of wild type and mutant p53 and induction of target gene expression. This is the first report attempting to characterize p53 acetylation sites targeted by aspirin. PMID:26596838

  7. Exit from Arsenite-Induced Mitotic Arrest Is p53 Dependent

    OpenAIRE

    McNeely, Samuel C.; Xu, Xiaogiang; Taylor, B. Frazier; Zacharias, Wolfgang; McCabe, Michael J.; States, J.Christopher

    2006-01-01

    Background Arsenic is both a human carcinogen and a chemotherapeutic agent, but the mechanism of neither arsenic-induced carcinogenesis nor tumor selective cytotoxicity is clear. Using a model cell line in which p53 expression is regulated exogenously in a tetracycline-off system (TR9-7 cells), our laboratory has shown that arsenite disrupts mitosis and that p53-deficient cells [p53(−)], in contrast to p53-expressing cells [p53(+)], display greater sensitivity to arsenite-induced mitotic arre...

  8. Autoimmunity against p53 predicts invasive cancer with poor survival in patients with an ovarian mass

    OpenAIRE

    Vogl, F D; M. Frey; Kreienberg, R; Runnebaum, I B

    2000-01-01

    Serum autoantibodies against the p53 protein (p53 AAb) were analysed with a newly developed enzyme-linked immunosorbent assay (ELISA) based on highly purified and renatured p53. In a hospital-based cohort study, preoperative sera from 113 patients with ovarian cancer, 15 patients with borderline tumours and 117 patients with benign tumours of the ovaries were studied. The prevalence of p53 AAb in patients with invasive cancer was 19% (21/113). No p53 AAb were found in patients with borderline...

  9. Analysis of P53 Mutation and Invasion Front Grading in Oral Squamous Cell Carcinomas

    Institute of Scientific and Technical Information of China (English)

    唐三保; 徐东选; 周彬

    2010-01-01

    We examined P53 mutation and invasion front grading (IFG) in 30 cases of oral squamous cell carcinomas (OSCCs). The association of P53 mutation and IFG scores with clinicopa-thological parameters was evaluated. P53 mutation existed in exon 5-8 in 15 out of the 30 OSCCs (50%). The incidence of P53 mutation was not associated with age, gender, N value and TNM stage. However, there was a significant correlation between P53 mutation and T value (P=0.046). There were no statistically significant correlations amo...

  10. Crystal Structure of a p53 Core Tetramer Bound to DNA

    OpenAIRE

    Malecka, Kimberly A.; Ho, William C.; Marmorstein, Ronen

    2008-01-01

    The tumor suppressor p53 regulates downstream genes in response to many cellular stresses and is frequently mutated in human cancers. Here, we report the use of a crosslinking strategy to trap a tetrameric p53 DNA binding domain (p53DBD) bound to DNA and the X-ray crystal structure of the protein/DNA complex. The structure reveals that two p53DBD dimers bind to B form DNA with no relative twist and that a p53 tetramer can bind to DNA without introducing significant DNA bending. The numerous d...

  11. Identification of p53 and Its Isoforms in Human Breast Carcinoma Cells

    OpenAIRE

    Zorka Milićević; Vladan Bajić; Lada Živković; Jelena Kasapović; Uroš Andjelković; Biljana Spremo-Potparević

    2014-01-01

    In breast carcinoma, disruption of the p53 pathway is one of the most common genetic alterations. The observation that the p53 can express multiple protein isoforms adds a novel level of complexity to the outcome of p53 mutations. p53 expression was analysed by Western immunoblotting and immunohistochemistry using monoclonal antibodies DO-7, Pab240, and polyclonal antiserum CM-1. The more frequently p53-positive nuclear staining has been found in the invasive breast tumors. One of the most in...

  12. The role of tumor suppressor p53 in the antioxidant defense and metabolism

    OpenAIRE

    Budanov, Andrei V.

    2014-01-01

    Tumor suppressor p53 is inactivated in most cancers and the critical role of p53 in the suppression of carcinogenesis has been confirmed in many mouse models. The protein product of the tumor suppressor p53 gene works as a transcriptional regulator, activating expression of numerous genes involved in cell death, cell cycle arrest, senescence, DNA-repair and many other processes. In spite of the multiple efforts to characterize the functions of p53, the mechanisms of tumor suppression by p53 a...

  13. Functions of TAp63 and p53 in restraining the development of metastatic cancer

    OpenAIRE

    Tan, Eh; Morton, JP; Timpson, P; TUCCI P; Melino, G.; Flores, ER; Sansom, OJ; Vousden, KH; Muller, PAJ

    2013-01-01

    Many tumours harbour mutations in the p53 tumour-suppressor gene that result in the expression of a mutant p53 protein. This mutant p53 protein has, in most cases, lost wild-type transcriptional activity and can also acquire novel functions in promoting invasion and metastasis. One of the mechanisms underlying these novel functions involves the ability of the mutant p53 to interfere with other transcription factors, including the p53 family protein TAp63. To investigate whether simultaneous d...

  14. Allele specific gain-of-function activity of p53 mutants in lung cancer cells

    OpenAIRE

    Vaughan, Catherine A.; Frum, Rebecca; Pearsall, Isabella; Singh, Shilpa; Windle, Brad; Yeudall, Andrew; Deb, Swati P.; Deb, Sumitra

    2012-01-01

    p53 mutations are mostly single amino acid changes resulting in expression of a stable mutant protein with “gain of function” (GOF) activity having a dominant oncogenic role rather than simple loss of function of wild-type p53. Knock-down of mutant p53 in human lung cancer cell lines with different endogenous p53 mutants results in loss of GOF activity as shown by lowering of cell growth rate. Two lung cancer cell lines, ABC1 and H1437 carrying endogenous mutants p53–P278S and –R267P, both sh...

  15. Coordination of the Nuclear and Cytoplasmic Activities of p53 in Response to DNA Damage

    OpenAIRE

    Pu, Tian; Zhang, Xiao-Peng; Liu, Feng; Wang, Wei

    2010-01-01

    The tumor suppressor p53 plays a key role in the cellular response to various stresses. Most previous studies have focused on either the nuclear or cytoplasmic proapoptotic functions of p53, ignoring the combination of both functions. To explore how the two functions of p53 are coordinated in the DNA damage response via computer simulation, we construct a model for the p53 network comprising coupled positive and negative feedback loops involving p53, Mdm2, and Akt, as well as PUMA and Bax. In...

  16. The novel partnership of L-GILZ and p53: a new affair in cancer?

    OpenAIRE

    Ayroldi, Emira; Marchetti, Cristina; Riccardi, Carlo

    2014-01-01

    A recent report from our laboratory reveals how long glucocorticoid-induced leucine zipper (L-Gilz) protein binds to p53 and mouse double minute 2 homolog (Mdm2), thus dissociating the p53/Mdm2 complex and activating p53 with subsequent activation of downstream genes p21 and p53 upregulated modulator of apoptosis (Puma). p53 activation appears to be the mechanism by which both basal and glucocorticoid (GC)-induced L-Gilz inhibits proliferation and induces antioncogenic activity in human cancer.

  17. EFFECTIVE NEW CANCER THERAPIES WHICH ARE INDEPENDENT OF P53 GENE STATUS

    OpenAIRE

    Takahashi, Akihisa; Ohnishi, Ken; Kondo, Natsuko; Mori, Eiichiro; Noda, Taichi; Ohnishi, Takeo

    2010-01-01

    The gene product of the tumor suppressor gene p53 is known to play an important role in cancer therapy. The p53 molecule induces cell-cycle arrest, apoptosis and DNA repair after cells are subjected to cancer therapies involving ionizing radiation, hyperthermia and anti-cancer drugs. Patients with cancers bearing mutated (m) p53 or deleted p53 gene often have a poorer prognosis than those with cancers bearing wild-type (wt) p53 gene. We reported that efficient cell lethality by ionizing radia...

  18. Cloning and sequencing of a DNA fragment encoding N37 apoptotic peptide derived from p53

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Objective It was reported that p53 apoptotic peptide (N37) could inhibit p73 gene through being bound with iASPP,which could induce tumor cell apoptosis. To further explore the function of N37,we constructed the cloning plasmid of DNA fragment encoding p53 (N37) apoptotic peptide by using DNA synthesis and molecular biology methods. Methods According to human p53 sequence from the GenBank database,the primer of p53(N37) gene was designed using Primer V7.0 software. The DNA fragment encoding p53 (N37) apopto...

  19. G9a and Glp Methylate Lysine 373 in the Tumor Suppressor p53*

    OpenAIRE

    Huang, Jing; Dorsey, Jean; Chuikov, Sergei; Xinyue ZHANG; Jenuwein, Thomas; Reinberg, Danny; Berger, Shelley L.

    2010-01-01

    The tumor suppressor p53 is regulated by numerous post-translational modifications. Lysine methylation has recently emerged as a key post-translational modification that alters the activity of p53. Here, we describe a novel lysine methylation site in p53 that is carried out by two homologous histone methyltransferases, G9a and Glp. G9a and Glp specifically methylate p53 at Lys373, resulting mainly in dimethylation. During DNA damage, the overall level of p53 modified at Lys373me2 does not inc...

  20. Urokinase Expression by Tumor Suppressor Protein p53: A Novel Role in mRNA Turnover

    OpenAIRE

    Shetty, Praveenkumar; Velusamy, Thirunavukkarasu; Bhandary, Yashodhar P.; Shetty, Rashmi S.; Liu, Ming-Cheh; Shetty, Sreerama

    2008-01-01

    Lung carcinoma (H1299) cells deficient in p53 (p53−/−) express large amounts of urokinase-type plasminogen activator (uPA) protein and uPA mRNA, and exhibit slower degradation of uPA mRNA than that of p53-expressing nonmalignant Beas2B human airway epithelial cells. Expression of p53 protein in H1299 cells, upon transfection with p53 cDNA, suppressed basal as well as uPA-induced expression of uPA protein in both conditioned media and cell lysates, and decreased the level of steady-state uPA m...

  1. Substrate Phosphorylation and Feedback Regulation in JFK-promoted p53 Destabilization*

    OpenAIRE

    Sun, Luyang; Shi, Lei; Wang, Feng; Huangyang, Peiwei; Si, Wenzhe; Yang, Jie; Yao, Zhi; Shang, Yongfeng

    2010-01-01

    The p53 tumor suppressor plays a central role in integrating cellular responses to various stresses. Tight regulation of p53 is thus essential for the maintenance of genome integrity and normal cell proliferation. Previously, we reported that JFK, the only Kelch domain-containing F-box protein in human, promotes ubiquitination and degradation of p53 and that unlike the other E3 ligases for p53, all of which possess an intrinsic ubiquitin ligase activity, JFK destabilizes p53 through the assem...

  2. The structure of p53 tumour suppressor protein reveals the basis for its functional plasticity

    OpenAIRE

    Okorokov, A L; Sherman, M. B.; Plisson, C.; Grinkevich, V; Sigmundsson, K.; Selivanova, G; Milner, J.; E V Orlova

    2006-01-01

    p53 major tumour suppressor protein has presented a challenge for structural biology for two decades. The intact and complete p53 molecule has eluded previous attempts to obtain its structure, largely due to the intrinsic flexibility of the protein. Using ATP-stabilised p53, we have employed cryoelectron microscopy and single particle analysis to solve the first three-dimensional structure of the full-length p53 tetramer (resolution 13.7 A). The p53 molecule is a D2 tetramer, resembling a hol...

  3. Study of the Relations of P53 Expression to the Colorectal Carcinoma%P53表达与大肠癌的关系

    Institute of Scientific and Technical Information of China (English)

    粟连秀

    2001-01-01

    目的:研究大肠癌中P53的表达与浸润转移的关系.方法:应用S-P免疫组织化学方法检测大肠癌中P53的表达.结果:大肠癌中P53的阳性率为51.2%.大肠癌中P53过表达与浸润程度(P<0.01)和淋巴结转移(P<0.05)有关.结论:P53过表达在大肠癌的浸润转移过程中起着重要作用.

  4. N-methylpurine DNA glycosylase inhibits p53-mediated cell cycle arrest and coordinates with p53 to determine sensitivity to alkylating agents

    Institute of Scientific and Technical Information of China (English)

    Shanshan Song; Guichun Xing; Lin Yuan; Jian Wang; Shan Wang; Yuxin Yin; Chunyan Tian; Fuchu He; Lingqiang Zhang

    2012-01-01

    Alkylating agents induce genome-wide base damage,which is repaired mainly by N-methylpurine DNA glycosylase (MPG).An elevated expression of MPG in certain types of tumor cells confers higher sensitivity to alkylation agents because MPG-induced apurinic/apyrimidic (AP) sites trigger more strand breaks.However,the determinant of drug sensitivity or insensitivity still remains unclear.Here,we report that the p53 status coordinates with MPG to play a pivotal role in such process.MPG expression is positive in breast,lung and colon cancers (38.7%,43.4% and 25.3%,respectively) but negative in all adjacent normal tissues.MPG directly binds to the tumor suppressor p53 and represses p53 activity in unstressed cells.The overexpression of MPG reduced,whereas depletion of MPG increased,the expression levels of pro-arrest gene downstream of p53 including p21,14-3-3σ and Gadd45 but not pro-apoptotic ones.The N-terminal region of MPG was specifically required for the interaction with the DNA binding domain of p53.Upon DNA alkylation stress,in p53 wild-type tumor cells,p53 dissociated from MPG and induced cell growth arrest.Then,AP sites were repaired efficiently,which led to insensitivity to alkylating agents.By contrast,in p53-mutated cells,the AP sites were repaired with low efficacy.To our knowledge,this is the first direct evidence to show that a DNA repair enzyme functions as a selective regulator of p53,and these findings provide new insights into the functional linkage between MPG and p53 in cancer therapy.

  5. Modeling the role of p53 pulses in DNA damage- induced cell death decision

    Directory of Open Access Journals (Sweden)

    Cui Jun

    2009-06-01

    Full Text Available Abstract Background The tumor suppressor p53 plays pivotal roles in tumorigenesis suppression. Although oscillations of p53 have been extensively studied, the mechanism of p53 pulses and their physiological roles in DNA damage response remain unclear. Results To address these questions we presented an integrated model in which Ataxia-Telangiectasia Mutated (ATM activation and p53 oscillation were incorporated with downstream apoptotic events, particularly the interplays between Bcl-2 family proteins. We first reproduced digital oscillation of p53 as the response of normal cells to DNA damage. Subsequent modeling in mutant cells showed that high basal DNA damage is a plausible cause for sustained p53 pulses observed in tumor cells. Further computational analyses indicated that p53-dependent PUMA accumulation and the PUMA-controlled Bax activation switch might play pivotal roles to count p53 pulses and thus decide the cell fate. Conclusion The high levels of basal DNA damage are responsible for generating sustained pulses of p53 in the tumor cells. Meanwhile, the Bax activation switch can count p53 pulses through PUMA accumulation and transfer it into death signal. Our modeling provides a plausible mechanism about how cells generate and orchestrate p53 pulses to tip the balance between survival and death.

  6. Nuclear accumulation and activation of p53 in embryonic stem cells after DNA damage

    Directory of Open Access Journals (Sweden)

    Rolletschek Alexandra

    2009-06-01

    Full Text Available Abstract Background P53 is a key tumor suppressor protein. In response to DNA damage, p53 accumulates to high levels in differentiated cells and activates target genes that initiate cell cycle arrest and apoptosis. Since stem cells provide the proliferative cell pool within organisms, an efficient DNA damage response is crucial. Results In proliferating embryonic stem cells, p53 is localized predominantly in the cytoplasm. DNA damage-induced nuclear accumulation of p53 in embryonic stem cells activates transcription of the target genes mdm2, p21, puma and noxa. We observed bi-phasic kinetics for nuclear accumulation of p53 after ionizing radiation. During the first wave of nuclear accumulation, p53 levels were increased and the p53 target genes mdm2, p21 and puma were transcribed. Transcription of noxa correlated with the second wave of nuclear accumulation. Transcriptional activation of p53 target genes resulted in an increased amount of proteins with the exception of p21. While p21 transcripts were efficiently translated in 3T3 cells, we failed to see an increase in p21 protein levels after IR in embryonal stem cells. Conclusion In embryonic stem cells where (anti-proliferative p53 activity is not necessary, or even unfavorable, p53 is retained in the cytoplasm and prevented from activating its target genes. However, if its activity is beneficial or required, p53 is allowed to accumulate in the nucleus and activates its target genes, even in embryonic stem cells.

  7. Contribution of caspase-3 differs by p53 status in apoptosis induced by X-irradiation

    International Nuclear Information System (INIS)

    We investigated the effect of p53 status on involvement of caspase-3 activation in cell death induced by X-irradiation, using rat embryonic fibroblasts (REFs) transduced with a temperature-sensitive mutant (mt) p53 gene. Cells with wild-type (wt) p53 showed greater resistance to X-irradiation than cells with mt p53. In cells with wt p53, X-irradiation-induced apoptosis was not inhibited by the caspase-3 inhibitor acetyl-L-aspartyl-L-methionyl-L-glutaminyl-L-aspartyl-aldehyde (Ac-DMQD-CHO) and caspase-3 activity was not elevated following X-irradiation, although induction of p53 and p21/WAF-1 protein was observed. In contrast, irradiated cells with mt p53 showed 89% inhibition of cell death with Ac-DMQD-CHO and 98% inhibition with the antioxidant N-acetyl-L-cysteine (NAC). In cells with mt p53, caspase-3 activity was increased approximately 5 times beyond baseline activity at 24 h after irradiation. This increase was almost completely inhibited by NAC. However, inhibition of caspase-3 by Ac-DMQD-CHO failed to decrease production of reactive oxygen species by cells with mt p53. Differential involvement of caspase-3 is a reason for differences in sensitivity to X-irradiation in cells with different p53 status. Caspase-3 activation appears to occur downstream from generation of reactive oxygen species occurring independently of wt p53 during X-irradiation-induced cell death. (author)

  8. Regulation of myo-inositol biosynthesis by p53-ISYNA1 pathway.

    Science.gov (United States)

    Koguchi, Tomoyuki; Tanikawa, Chizu; Mori, Jinichi; Kojima, Yoshiyuki; Matsuda, Koichi

    2016-06-01

    In response to various cellular stresses, p53 exerts its tumor suppressive effects such as apoptosis, cell cycle arrest, and senescence through the induction of its target genes. Recently, p53 was shown to control cellular homeostasis by regulating energy metabolism, glycolysis, antioxidant effect, and autophagy. However, its function in inositol synthesis was not reported. Through a microarray screening, we found that five genes related with myo-inositol metabolism were induced by p53. DNA damage enhanced intracellular myo-inositol content in HCT116 p53+/+ cells, but not in HCT116 p53-/- cells. We also indicated that inositol 3-phosphate synthase (ISYNA1) which encodes an enzyme essential for myo-inositol biosynthesis as a direct target of p53. Activated p53 regulated ISYNA1 expression through p53 response element in the seventh exon. Ectopic ISYNA1 expression increased myo-inositol levels in the cells and suppressed tumor cell growth. Knockdown of ISYNA1 caused resistance to adriamycin treatment, demonstrating the role of ISYNA1 in p53-mediated growth suppression. Furthermore, ISYNA1 expression was significantly associated with p53 mutation in bladder, breast cancer, head and neck squamous cell carcinoma, lung squamous cell carcinoma, and pancreatic adenocarcinoma. Our findings revealed a novel role of p53 in myo-inositol biosynthesis which could be a potential therapeutic target. PMID:27035231

  9. The role of p53 molecule in radiation and hyperthermic therapies

    International Nuclear Information System (INIS)

    In recent years, cancer-related genes have been analyzed at the molecular level as predictive indicators for cancer therapy. Among those genes, the tumor suppressor gene p53 is worthy of notice in cancer therapy, because the p53 molecule prevents the malignant degeneration of non-cancer cells by regulating cell-cycle arrest, apoptosis, and DNA repair. An abnormality of the p53 gene introduces a genetic instability and increases the incidence of carcinogenesis and teratogenesis. Therefore, p53 is called a guardian of the genome. Mutations of p53 are observed at a high frequency in human tumors, and are recognized in about half of all malignant tumors in human head and neck cancers. We previously reported that radio- and heat-sensitivities of human cultured tongue squamous cell carcinoma cells are p53-dependent, and are closely correlated with the induction of apoptosis. In a human cell culture system, the interactive hyperthermic enhancement of radiosensitivity was observed in wild-type p53 cells, but not in mutated p53 cells. In a transplanted tumor system, the combination therapies of radiation and hyperthermia induced efficient tumor growth depression and apoptosis in the wild-type p53 tumors. In this review, we discuss the p53 activation signaling pathways through the modification of p53 molecules, such as phosphorylation after radiation and hyperthermia treatments. (author)

  10. High-LET radiation enhanced apoptosis but not necrosis regardless of p53 status

    International Nuclear Information System (INIS)

    Purpose: We analyzed the death pattern of human lung cancer cells harboring different p53 statuses after irradiation with different levels of linear energy transfer (LET). Methods and materials: We used three kinds of human lung cancer cell lines with identical genotypes, except for the p53 gene. These cells were exposed to X-rays or accelerated carbon-ion beams. The cellular sensitivities were determined by a colony-forming assay. The detection and quantification of cell death (apoptosis and necrosis) were evaluated and compared by acridine orange/ethidium bromide double staining for fluorescence microscopy. Results: We found that (1) there was no significant difference in cellular sensitivity to LET radiation >70 KeV/μm, although wild-type p53 cell sensitivity to X-rays was higher than that of mutated p53 or p53-null cells; (2) low-LET radiation effectively induced apoptosis in wild-type p53 cells as compared with mutated p53 and p53-null cells; and (3) high-LET radiation induced p53-independent apoptosis. Conclusions: Our findings suggest that high-LET radiotherapy is expected to be a valid application for patients carrying mutated p53 cancer cells. We proposed that the elucidation of the p53-independent apoptosis-related genes might provide new insights into radiotherapy for cancer

  11. Using targeted transgenic reporter mice to study promoter-specific p53 transcriptional activity

    Science.gov (United States)

    Goh, Amanda M.; Lim, Chin Yan; Chiam, Poh Cheang; Mann, Michael B.; Mann, Karen M.; Menendez, Sergio; Lane, David P.

    2012-01-01

    The p53 transcription factor modulates gene expression programs that induce cell cycle arrest, senescence, or apoptosis, thereby preventing tumorigenesis. However, the mechanisms by which these fates are selected are unclear. Our objective is to understand p53 target gene selection and, thus, enable its optimal manipulation for cancer therapy. We have generated targeted transgenic reporter mice in which EGFP expression is driven by p53 transcriptional activity at a response element from either the p21 or Puma promoter, which induces cell cycle arrest/senescence and apoptosis, respectively. We demonstrate that we could monitor p53 activity in vitro and in vivo and detect variations in p53 activity depending on the response element, tissue type, and stimulus, thereby validating our reporter system and illustrating its utility for preclinical drug studies. Our results also show that the sequence of the p53 response element itself is sufficient to strongly influence p53 target gene selection. Finally, we use our reporter system to provide evidence for p53 transcriptional activity during early embryogenesis, showing that p53 is active as early as embryonic day 3.5 and that p53 activity becomes restricted to embryonic tissue by embryonic day 6.5. The data from this study demonstrate that these reporter mice could serve as powerful tools to answer questions related to basic biology of the p53 pathway, as well as cancer therapy and drug discovery. PMID:22307631

  12. A Comprehensive and High Resolution Genome-wide Response of p53 to Stress

    Science.gov (United States)

    Chang, Gue Su; Chen, Xiangyun Amy; Park, Bongsoo; Rhee, Ho Sung; Li, Pingxin; Han, Kang Hoo; Mishra, Tejaswini; Chan-Salis, Ka Yim; Li, Yunfei; Hardison, Ross C.; Wang, Yanming; Pugh, B. Franklin

    2014-01-01

    SUMMARY Tumor-suppressor p53 regulates transcription of stress response genes. Many p53 targets remain undiscovered due to uncertainty as to where p53 binds in the genome, and that few genes reside near p53-bound recognition elements (REs). Using ChIP-exo, we associated p53 with 2,183 unsplit REs. REs were positionally constrained with other REs and other regulatory elements, which may reflect structurally organized p53 interactions. Surprisingly, stress resulted in increased occupancy of TFIIB and RNA polymerase (Pol) II near REs, which was reduced when p53 was present. A subset associated with antisense RNA near stress-response genes. The combination of high-confidence locations for p53/REs, TFIIB/Pol II, and their changes in response to stress allowed us to identify 151 high-confidence p53-regulated genes, substantially increasing the number of p53 targets. These genes comprised a large portion of a pre-defined DNA-damage stress-response network. Thus, p53 plays a comprehensive role in regulating the stress-response network, including regulating noncoding transcription. PMID:25043190

  13. A Comprehensive and High-Resolution Genome-wide Response of p53 to Stress

    Directory of Open Access Journals (Sweden)

    Gue Su Chang

    2014-07-01

    Full Text Available Tumor suppressor p53 regulates transcription of stress-response genes. Many p53 targets remain undiscovered because of uncertainty as to where p53 binds in the genome and the fact that few genes reside near p53-bound recognition elements (REs. Using chromatin immunoprecipitation followed by exonuclease treatment (ChIP-exo, we associated p53 with 2,183 unsplit REs. REs were positionally constrained with other REs and other regulatory elements, which may reflect structurally organized p53 interactions. Surprisingly, stress resulted in increased occupancy of transcription factor IIB (TFIIB and RNA polymerase (Pol II near REs, which was reduced when p53 was present. A subset associated with antisense RNA near stress-response genes. The combination of high-confidence locations for p53/REs, TFIIB/Pol II, and their changes in response to stress allowed us to identify 151 high-confidence p53-regulated genes, substantially increasing the number of p53 targets. These genes composed a large portion of a predefined DNA-damage stress-response network. Thus, p53 plays a comprehensive role in regulating the stress-response network, including regulating noncoding transcription.

  14. Inhibition of Endothelial p53 Improves Metabolic Abnormalities Related to Dietary Obesity

    Directory of Open Access Journals (Sweden)

    Masataka Yokoyama

    2014-06-01

    Full Text Available Accumulating evidence has suggested a role for p53 activation in various age-associated conditions. Here, we identified a crucial role of endothelial p53 activation in the regulation of glucose homeostasis. Endothelial expression of p53 was markedly upregulated when mice were fed a high-calorie diet. Disruption of endothelial p53 activation improved dietary inactivation of endothelial nitric oxide synthase that upregulated the expression of peroxisome proliferator-activated receptor-γ coactivator-1α in skeletal muscle, thereby increasing mitochondrial biogenesis and oxygen consumption. Mice with endothelial cell-specific p53 deficiency fed a high-calorie diet showed improvement of insulin sensitivity and less fat accumulation, compared with control littermates. Conversely, upregulation of endothelial p53 caused metabolic abnormalities. These results indicate that inhibition of endothelial p53 could be a novel therapeutic target to block the vicious cycle of cardiovascular and metabolic abnormalities associated with obesity.

  15. 血清p53抗体与肿瘤

    Institute of Scientific and Technical Information of China (English)

    徐晓云; 李彬; 王凤安

    2005-01-01

    肿瘤抑制基因p53基因的突变是恶性肿瘤中最常见的基因突变。血清p53抗体是机体对突变型p53蛋白产生免疫应答的产物。Crawford首先在乳腺癌患者的血清中发现p53抗体,随后,相继在肺癌、大肠癌、食管癌、肝癌、膀胱癌、卵巢癌等患者血清中检测到p53抗体。研究进一步发现,p53抗体生物学意义与p53基因相同,

  16. 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

    single-system lesions only without relapse, whereas others develop fatal multiorgan disease. The expression of p53 tumor suppressor gene product detected immunohistochemically can be used as a guideline to alterations in DNA repair control and apoptosis. The authors have chosen to analyze p53 expression...... diagnosis of LCH 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...

  17. [p53 activation by PI-3K family kinases after DNA double-strand breaks].

    Science.gov (United States)

    Pernin, D; Uhrhammer, N; Verrelle, P; Bignon, Y J; Bay, J O

    2000-09-01

    p53 plays a central role in the cellular response to DNA double-strand breaks (DSBs), and to DNA damage in general. The protein kinases ATM, ATR and DNA-PK detect DSBs and transmit this information to p53 by phosphorylation. This phosphorylation dissociates p53 from its negative regulator, mdm2. p53 then undergoes further modification and activates transcription of the genes responsible for cell cycle arrest. In certain circumstances, p53 also activates transcription of the genes responsible for apoptosis. The dysfunction of this cascade of events is oncogenic, with P53 itself being the most commonly mutated gene in malignant cells, although mutations in both the DNA damage sensors and cell cycle checkpoint and apoptosis effectors are frequent. A more complete understanding of p53 and the proteins it interacts with may allow the development of new cancer treatments. PMID:11038413

  18. Association of p53 protein expression with clinical outcome in advanced supraglottic cancer

    International Nuclear Information System (INIS)

    To determine the incidence and prognostic effect of p53 expression in patients with advanced supraglottic cancer. Twenty-one cases of total 48 advanced supraglottic cancer patients who received postoperative adjuvant radiation therapy were evaluated by immunohistochemical staining employing p53 monoclonal antibody. Three out of six stage III patients and four out of fifteen stage IV patients showed p53 expression without statistically significant difference (p=0.608). Five year survival rates are 93% in p53 negative, 86% in p53 positive patients and there was no significant difference(p=0.776). p53 expression does not show statistically significant correlation with primary tumor status(p=0.877), lymph node status(p=0.874) and age(p=0.64). There was no statistically significant correlation between traditionally known risk factors and p53 expression

  19. Crosstalk between tumor suppressors p53 and PKCδ: Execution of the intrinsic apoptotic pathways.

    Science.gov (United States)

    Dashzeveg, Nurmaa; Yoshida, Kiyotsugu

    2016-07-28

    p53 and PKCδ are tumor suppressors that execute apoptotic mechanisms in response to various cellular stresses. p53 is a transcription factor that is frequently mutated in human cancers; it regulates apoptosis in transcription-dependent and -independent ways in response to genotoxic stresses. PKCδ is a serine/threonine protein kinase and mutated in human cancers. Available evidence shows that PKCδ activates p53 by direct and/or indirect mechanisms. Moreover, PKCδ is also implicated in the transcriptional regulation of p53 in response to DNA damage. Recent findings demonstrated that p53, in turn, binds onto the PKCδ promoter and induces its expression upon DNA damage to facilitate apoptosis. Both p53 and PKCδ are associated with the apoptotic mechanisms in the mitochondria by regulating Bcl-2 family proteins to provide mitochondrial outer membrane permeabilization. This review discusses the crosstalk between p53 and PKCδ in the context of apoptotic cell death and cancer therapy. PMID:27130668

  20. p53-Dependent Nestin Regulation Links Tumor Suppression to Cellular Plasticity in Liver Cancer

    DEFF Research Database (Denmark)

    Tschaharganeh, Darjus F; Xue, Wen; Calvisi, Diego F;

    2014-01-01

    The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the expansion of malignant cells, and as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor-cell-associated protei...... by p53 restricts cellular plasticity and tumorigenesis in liver cancer.......The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the expansion of malignant cells, and as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor-cell-associated protein...

  1. P53 and p73 differ in their ability to inhibit glucocorticoid receptor (GR transcriptional activity

    Directory of Open Access Journals (Sweden)

    Nie Linghu

    2006-12-01

    Full Text Available Abstract Background p53 is a tumor suppressor and potent inhibitor of cell growth. P73 is highly similar to p53 at both the amino acid sequence and structural levels. Given their similarities, it is important to determine whether p53 and p73 function in similar or distinct pathways. There is abundant evidence for negative cross-talk between glucocorticoid receptor (GR and p53. Neither physical nor functional interactions between GR and p73 have been reported. In this study, we examined the ability of p53 and p73 to interact with and inhibit GR transcriptional activity. Results We show that both p53 and p73 can bind GR, and that p53 and p73-mediated transcriptional activity is inhibited by GR co-expression. Wild-type p53 efficiently inhibited GR transcriptional activity in cells expressing both proteins. Surprisingly, however, p73 was either unable to efficiently inhibit GR, or increased GR activity slightly. To examine the basis for this difference, a series of p53:p73 chimeric proteins were generated in which corresponding regions of either protein have been swapped. Replacing N- and C-terminal sequences in p53 with the corresponding sequences from p73 prevented it from inhibiting GR. In contrast, replacing p73 N- and C-terminal sequences with the corresponding sequences from p53 allowed it to efficiently inhibit GR. Differences in GR inhibition were not related to differences in transcriptional activity of the p53:p73 chimeras or their ability to bind GR. Conclusion Our results indicate that both N- and C-terminal regions of p53 and p73 contribute to their regulation of GR. The differential ability of p53 and p73 to inhibit GR is due, in part, to differences in their N-terminal and C-terminal sequences.

  2. P53 overexpression and outcome of radiation therapy in head and neck cancers

    International Nuclear Information System (INIS)

    Experimental studies have implicated the wild type p53 in cellular response to radiation. Whether altered p53 function can lead to changes in clinical radiocurability remains an area of ongoing study. This study was performed to investigate whether any correlation between change of p53 and outcome of curative radiation therapy in patients with head and neck cancers. Immunohistochemical analysis with a mouse monoclonal antibody (D0-7) specific for human p53 was used to detect to overexpression of protein in formalin fixed, paraffin-embedded tumor sample from 55 head and neck cancer patients treated with curative radiation therapy (median dose of 7020 cGy) from February 1988 to March 1996 at St. Mary's Hospital. Overexpression of p53 was correlated with locoregional control and survival using Kaplan-Meier method. A Cox regression multivariate analysis was performed that included all clinical variables and status of p53 expression. Thirty-seven (67.2%) patients showed overexpression of p53 by immunohistochemical staining in their tumor. One hundred percent of oral cavity, 76% of laryngeal, 66.7% of oropharyngeal, 66.7% of hypopharyngeal cancer showed p53 overexpression (p=0.05). The status of p53 had significant relationship with stage of disease (p=0.03) and history of smoking (p=0.001). The overexpression of p53 was not predictive of response rate to radiation therapy. The locoregional control was not significantly affected by p53 status. Overexpression of p53 didn't have any prognostic implication for disease free survival and overall survival. Primary site and stage of disease were significant prognostic factors for survival. The p53 overexpression as detected by immunohistochemical staining had significant correlation with stage, primary site of disease and smoking habit of patients. The p53 overexpression didn't have any predictive value for outcome of curative radiation therapy in a group of head and neck cancers

  3. Structural Determinant for Switching between the Polymerase and Exonuclease Modes in the PCNA-Replicative DNA Polymerase Complex

    Science.gov (United States)

    Nishida, Hirokazu; Mayanagi, Kouta; Ishino, Yoshizumi; Morikawa, Kosuke

    Proliferating cell nuclear antigen (PCNA) is responsible for the processivity of DNA polymerase. We determined the crystal structure of Pyrococcus furiosus DNA polymerase (PfuPol) complexed with a cognate monomeric PCNA, which allowed us to construct a convincing model of the polymerase-PCNA ring interaction. Electron microscopy analyses confirmed that this complex structure exists among the multiple functional configurations in solution. Together with data from mutational analyses, this structural study indicated that the novel interaction between a stretched loop of PCNA and the PfuPol Thumb domain is quite important, in addition to the authentic PCNA-polymerase recognition site (PIP box). A comparison of the present structures with the previously reported structures of polymerases complexed with DNA suggested that the second interaction site plays a crucial role in switching between the polymerase and exonuclease modes, by stabilizing only the polymerase mode. This proposed mechanism of fidelity control of replicative DNA polymerases was supported by experiments, in which a mutation within the second interaction site caused an enhancement in the exonuclease activity in the presence of PCNA.

  4. Depressive Effect of the Antisense Oligonucleotides of C-myc and PCNA on the Proliferation of VSMC

    Institute of Scientific and Technical Information of China (English)

    Qingxian Li; Yanfu Wang; Yuhua Liao; Huiling Zhang; Yanying Jiang

    2007-01-01

    To study the depressive effect of the antisense oligonuceotides (ASODN) of c-myc and proliferating cell nuclear antigen (PCNA) on the proliferation of VSMC.Methods Taking the VSMC obtained from rat aorta thoracalis cultured 4 ~ 8 generation as research object.The objects were divided into three groups to carry out control study:control group,PCNA ASODN group and c-myc ASODN group.The ASODNs' working concentration all were 1:50.The depressive effect of ASODN on VSMC proliferation was investigated by cell counting,MTT and 3H-TdR incorporation assay;PCNA and c-myc expression were detected by immunohistochemical method after transferring PCNA successfully;the corresponding gene was inhibited obviously;compared with control group ( P < 0.05 ).Conclusions PCNA and c-myc might play a considerable role in the VSMC proliferation process.The corresponding gene could be depressed successfully after transferring PCNA and c-myc ASODN into VSMC,and then the proliferation of VSMC was slowed down.This study presented a beneficial proposal and theoretical fundament for atherosclerotic treatment.

  5. Involvement of proliferating cell nuclear antigen (cyclin) in DNA replication in living cells.

    OpenAIRE

    Zuber, M; Tan, E M; Ryoji, M

    1989-01-01

    Proliferating cell nuclear antigen (PCNA) (also called cyclin) is known to stimulate the activity of DNA polymerase delta but not the other DNA polymerases in vitro. We injected a human autoimmune antibody against PCNA into unfertilized eggs of Xenopus laevis and examined the effects of this antibody on the replication of injected plasmid DNA as well as egg chromosomes. The anti-PCNA antibody inhibited plasmid replication by up to 67%, demonstrating that PCNA is involved in plasmid replicatio...

  6. Adenoviral-mediated p53 transgene expression sensitizes both wild-type and null p53 prostate cancer cells in vitro to radiation

    International Nuclear Information System (INIS)

    Purpose/Objective: The effect of adenoviral-mediated p53 transgene expression on the radiation response of two human prostate cancer cell lines, the p53wild-type LNCaP and p53null PC3 lines, was examined. The objective was to determine if this vector sensitizes cells to radiation independently of their p53 status. Methods and Materials: A recombinant adenovirus-5 vector (RPR/INGN 201, Introgen Therapeutics, Houston, TX) containing a CMV promoter and wild-type p53-cDNA (Ad5-p53) was used to facilitate p53 transgene expression. A multiplicity of infection (MOI) of 10-40 viral particles per cell was used, based on Ad5/CMV/lacz infection and staining for the β-galactosidase reporter gene product. Clonogenic assays were performed to evaluate the degree of sensitization to radiation of viral-transduced cells compared with irradiated nontransduced controls. The relative efficacy of these treatments to induce apoptotic cell death was determined using the TUNEL assay. Results: The delivery of Ad5-p53 (10 MOI) reduced control plating efficiency from 36.5% to 0.86% in the LNCaP cell line and from 75.1% to 4.1% in the PC3 cell line. After correcting for the effect of Ad5-p53 on plating efficiency, the surviving fraction after 2 Gy (SF2) of gamma-irradiation was reduced over 2.5-fold, from 0.187 to 0.072, with transgene p53 expression in the LNCaP cell line. Surviving fraction after 4 Gy (SF4) was reduced over 4.5-fold, from 0.014 to 0.003, after Ad5-p53 treatment. In the PC3 cell line, Ad5-p53 (40 MOI) reduced SF2 over 1.9-fold from 0.708 to 0.367, and SF4 over 6-fold from 0.335 to 0.056. In both the LNCaP and PC3 cell lines, the combination of Ad5-p53 plus radiation (2 Gy) resulted in supra-additive apoptosis (∼20% for LNCaP and ∼15% for PC3 at 50 MOI), above that seen from the addition of the controls; control vector Ad5-pA plus RT (0.15% for LNCaP and 1.44% for PC3), Ad5-p53 alone (28.6% for LNCaP and 21.7% for PC3), RT alone (0% for LNCaP and 0.23% for PC3), or Ad5-p

  7. Interaction Between P53 and TRF1、TRF2 and Analysis of Binding Domain of P53 in vitro%P53与TRF1、TRF2的体外结合及P53结合功能区的分析

    Institute of Scientific and Technical Information of China (English)

    李玲; 张波; 邹万忠; 郑杰; 刘俊平

    2005-01-01

    通过分析端粒结合蛋白TRF1、TRF2与P53的体外结合,探讨P53-端粒途径调节细胞生命活动的分子机制.GST和4种人P53-GST融合蛋白经大肠杆菌表达、谷胱甘肽-SepharoseTM4B纯化后,进行SDS-PAGE和考马斯亮篮染色.人P53包括野生型(1~393)、C端缺失体P53 N5(2~293)、N端缺失体P53 2C(95~393)、单个氨基酸突变体P53 R175H(175 R→H).各纯化蛋白的分子量与预计的完全一致,且纯化率达90%以上.将纯化的GST和P53-GST融合蛋白与人乳腺癌细胞MCF-7细胞蛋白进行体外结合反应,Western印迹检测反应物中P53和TRF1、TRF2的结合.野生型P53P53-R175H均能沉淀MCF-7中的TRF1、TRF2,且结合力相似,而单独的GST则无沉淀TRF1、TRF2的作用.与野生型P53P53 R175H相比,P53 2C与TRF1、TRF2的结合力明显增加,P53 N5与TRF1、TRF2的结合力大大减弱.表明P53和TRF1、TRF2可以进行直接而特异的体外结合,且它们的结合为P53 C端(293~393)结构域依赖性.P53和TRF1、TRF2这种结构域依赖性的结合可能与端粒动态变化所诱导的细胞活动有关.

  8. p53 inactivation upregulates p73 expression through E2F-1 mediated transcription.

    Directory of Open Access Journals (Sweden)

    Chaitali Tophkhane

    Full Text Available While p73 overexpression has been associated with increased apoptosis in cancer tissues, p73 overexpressing tumors appear to be of high grade malignancy. Why this putative tumor suppressor is overexpressed in cancer cells and what the function of overexpressed p73 is in breast cancers are critical questions to be addressed. By investigating the effect of p53 inactivation on p73 expression, we found that both protein and mRNA levels of TAp73 were increased in MCF-7/p53siRNA cells, MCF-7/p53mt135 cells and HCT-116/p53-/- cells, as compared to wild type control, suggesting that p53 inactivation by various forms upregulates p73. We showed that p53 knockdown induced p73 was mainly regulated at the transcriptional level. However, although p53 has a putative binding site in the TAp73 promoter, deletion of this binding site did not affect p53 knockdown mediated activation of TAp73 promoter. Chromatin immuno-precipitation (ChIP data demonstrated that loss of p53 results in enhanced occupancy of E2F-1 in the TAp73 promoter. The responsive sequence of p53 inactivation mediated p73 upregulation was mapped to the proximal promoter region of the TAp73 gene. To test the role of E2F-1 in p53 inactivation mediated regulation of p73 transcription, we found that p53 knockdown enhanced E2F-1 dependent p73 transcription, and mutations in E2F-1 binding sites in the TAp73 promoter abrogated p53 knockdown mediated activation of TAp73 promoter. Moreover, we demonstrated that p21 is a mediator of p53-E2F crosstalk in the regulation of p73 transcription. We concluded that p53 knockdown/inactivation may upregulate TAp73 expression through E2F-1 mediated transcriptional regulation. p53 inactivation mediated upregulation of p73 suggests an intrinsic rescuing mechanism in response to p53 mutation/inactivation. These findings support further analysis of the correlation between p53 status and p73 expression and its prognostic/predictive significance in human cancers.

  9. Studies on the Utility of Sequential Staining Technique using PCNA and AgNORs for Assessing the Degree of Malignancy of Gastric Carcinoma

    OpenAIRE

    Matsuo, Toshikazu

    1993-01-01

    In thirty cases of resected primary gastric carcinoma, the relative utility of argyrophilic nucleolar organizer regions (AgNORs) staining (single staining) and sequential staining technique using proliferating cell nuclear antigen (PCNA) and AgNORs was studied. The mean number of AgNORs in PCNA-positive cells was significantly larger than that in AgNORs single stained cells. For above two groups, correrating mean number of AgNORs with clinicopathological factors revealed a significant differe...

  10. Aggregation tendencies in the p53 family are modulated by backbone hydrogen bonds.

    Science.gov (United States)

    Cino, Elio A; Soares, Iaci N; Pedrote, Murilo M; de Oliveira, Guilherme A P; Silva, Jerson L

    2016-01-01

    The p53 family of proteins is comprised of p53, p63 and p73. Because the p53 DNA binding domain (DBD) is naturally unstable and possesses an amyloidogenic sequence, it is prone to form amyloid fibrils, causing loss of functions. To develop p53 therapies, it is necessary to understand the molecular basis of p53 instability and aggregation. Light scattering, thioflavin T (ThT) and high hydrostatic pressure (HHP) assays showed that p53 DBD aggregates faster and to a greater extent than p63 and p73 DBDs, and was more susceptible to denaturation. The aggregation tendencies of p53, p63, and p73 DBDs were strongly correlated with their thermal stabilities. Molecular Dynamics (MD) simulations indicated specific regions of structural heterogeneity unique to p53, which may be promoted by elevated incidence of exposed backbone hydrogen bonds (BHBs). The results indicate regions of structural vulnerability in the p53 DBD, suggesting new targetable sites for modulating p53 stability and aggregation, a potential approach to cancer therapy. PMID:27600721

  11. A Novel Method for Detecting p53 Autoantibodies with Recombinant Human p53 Protein Linked Nano Magnetic Ball%纳米磁球偶联重组p53蛋白检测p53自身抗体的新颖方法

    Institute of Scientific and Technical Information of China (English)

    王国玉; 倪晶

    2013-01-01

    目的:采用磁检测方法检测血清p53抗体浓度.方法:制备含有抗人p53抗体的试纸条,固定纳米磁球捕获的血清p53抗体,然后滴加到试纸条上,通过磁检测试纸条的磁信号,分析p53抗体的含量.结果:偶联重组p53蛋白的纳米磁球能有效富集患者血清p53抗体,p53抗体与偶联有纳米磁球的重组p53结合后,通过磁检测p53抗体的最低浓度可达pmol.结论:偶联重组p53蛋白的纳米磁球,可提高p53自身抗体的检测便捷性和灵敏性.

  12. Cancer therapeutic approach based on conformational stabilization of mutant p53 protein by small peptides

    Science.gov (United States)

    Tal, Perry; Eizenberger, Shay; Cohen, Elad; Goldfinger, Naomi; Pietrokovski, Shmuel; Oren, Moshe; Rotter, Varda

    2016-01-01

    The p53 tumor suppressor serves as a major barrier against malignant transformation. Over 50% of tumors inactivate p53 by point mutations in its DNA binding domain. Most mutations destabilize p53 protein folding, causing its partial denaturation at physiological temperature. Thus a high proportion of human tumors overexpress a potential potent tumor suppressor in a non-functional, misfolded form. The equilibrium between the properly folded and misfolded states of p53 may be affected by molecules that interact with p53, stabilizing its native folding and restoring wild type p53 activity to cancer cells. To select for mutant p53 (mutp53) reactivating peptides, we adopted the phage display technology, allowing interactions between mutp53 and random peptide libraries presented on phages and enriching for phage that favor the correctly folded p53 conformation. We obtained a large database of potential reactivating peptides. Lead peptides were synthesized and analyzed for their ability to restore proper p53 folding and activity. Remarkably, many enriched peptides corresponded to known p53-binding proteins, including RAD9. Importantly, lead peptides elicited dramatic regression of aggressive tumors in mouse xenograft models. Such peptides might serve as novel agents for human cancer therapy. PMID:26943582