Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Despite the strikingly grave prognosis for older patients with glioblastomas, significant variability in patient outcome is experienced. To explore the potential for developing improved prognostic capabilities based on the elucidation of potential biological relationships, we did analyses of genes commonly mutated, amplified, or deleted in glioblastomas and DNA microarray gene expression data from tumors of glioblastoma patients of age >50 for whom survival is known. No prognostic significance was associated with genetic changes in epidermal growth factor receptor (amplified in 17 of 41 patients), TP53 (mutated in 11 of 41 patients), p16INK4A (deleted in 15 of 33 patients), or phosphatase and tensin homologue (mutated in 15 of 41 patients). Statistical analysis of the gene expression data in connection with survival involved exploration of regression models on small subsets of genes, based on computational search over multiple regression models with cross-validation to assess predictive validity. The analysis generated a set of regression models that, when weighted and combined according to posterior probabilities implied by the statistical analysis, identify patterns in expression of a small subset of genes that are associated with survival and have value in assessing survival risks. The dominant genes across such multiple regression models involve three key genes-SPARC (Osteonectin), Doublecortex, and Semaphorin3B-which play key roles in cellular migration processes. Additional analysis, based on statistical graphical association models constructed using similar computational analysis methods, reveals other genes which support the view that multiple mediators of tumor invasion may be important prognostic factor in glioblastomas in older patients.
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PMID:Gene expression profiling and genetic markers in glioblastoma survival. 1589 94

Both PTEN (encoding phosphate and tensin homologue) and p53 are known as cancer suppressor genes, and they are assumed that their gene mutations and loss of heterozygosity (LOH) occur frequently in various types of carcinoma. In the present study, we investigated both the p53 mutation and LOH of PTEN in 113 gastric cancer patients. We observed the LOH of PTEN in 11.1% of the patients with normal p53s and 46.2% of the patients with p53 gene mutations. The result that LOH of PTEN was frequently observed in the cases with p53 gene mutations and other data in this study suggested that both PTEN and p53 have complimentary roles in gastric carcinoma development.
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PMID:Genetic mutual relationship between PTEN and p53 in gastric cancer. 1605 Oct 30

PTEN (phosphatase and tensin homologue, deleted on chromosome 10) is a tumor suppressor with dual phosphatase activity and mutations of its gene, PTEN, have been associated with many sporadic cancers and heritable neoplasia syndromes, including Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome. However, accumulating evidence now shows that PTEN may have novel functions other than as a phosphatase. In the present study, we show that PTEN is able to autoregulate its expression through the stabilization of another tumor suppressor p53. We further show that PTEN enhances p53 transactivation, a relationship that requires the interaction between PTEN and p53 and is PTEN phosphatase independent. We show that cell lines from Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome patients with germ line PTEN promoter mutations in the vicinity of the p53-binding motifs have altered p53 regulation. This seems to be due to reduced PTEN stability and decreased PTEN-p53 interactions. Our data provide clues to better understand the regulation of PTEN expression and the possible mechanisms of the pathogenesis of the subset of Cowden syndrome individuals with germ line promoter variation and who lack mutations in the PTEN coding region and splice sites. Importantly, this mechanism also holds for those sporadic tumors that lack intragenic mutations but have hemizygous deletion of PTEN, which includes the promoter region as manifested by loss-of-heterozygosity of 10q markers. The importance of our observations is underlined by the broad spectrum of neoplasias that harbor somatic PTEN or p53 alterations, or both.
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PMID:PTEN autoregulates its expression by stabilization of p53 in a phosphatase-independent manner. 1642 3

The tumour-suppressor phosphatase with tensin homology (PTEN) is the most important negative regulator of the cell-survival signalling pathway initiated by phosphatidylinositol 3-kinase (PI3K). Although PTEN is mutated or deleted in many tumours, deregulation of the PI3K-PTEN network also occurs through other mechanisms. Crosstalk between the PI3K pathways and other tumorigenic signalling pathways, such as those that involve Ras, p53, TOR (target of rapamycin) or DJ1, can contribute to this deregulation. How does the PI3K pathway integrate signals from numerous sources, and how can this information be used in the rational design of cancer therapies?
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PMID:Beyond PTEN mutations: the PI3K pathway as an integrator of multiple inputs during tumorigenesis. 1645 12

There has been intense investigation regarding the interaction between the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and p53 tumor suppressors. p53 has been shown to up-regulate PTEN expression as a transcriptional activator. However, clinical observations by immunohistochemistry studies indicate that significant increases in p53 protein levels coexist with reduced or absent expression of PTEN protein in a variety of neoplasias. In this study, we propose a mechanism that begins to explain how p53 can both up-regulate and down-regulate PTEN. We have found that PTEN protein is down-regulated under proteasome dysfunction induced by proteasome inhibitor MG132 in both human lymphoblast cells and MCF7 cells. The reduction of PTEN is coincident with elevated p53 protein levels and the association between PTEN and p53 but independent of its phosphatase activities. Quantitative reverse transcription-PCR indicates that proteasome inhibition does not reduce PTEN message levels but affects PTEN protein stability. The p53 inhibitor, pifithrin-alpha, is able to attenuate the effect of proteasome inhibition. Using ectopic expression studies in p53-null mouse embryonic fibroblasts and p53/PTEN-null PC3 cells, we show that PTEN is more stable in p53-null cells compared with p53-expressing cells. Inhibition of caspases, the downstream targets of p53, particularly caspase-3, can partially restore the stability of PTEN. This study provides the first evidence that p53 is able to down-regulate PTEN protein stability in stressed cells. Our study sheds some light on the mechanisms that regulate PTEN protein stability, which is important to fully elucidate to comprehend the broad neoplastic manifestations of Cowden syndrome/Bannayan-Riley-Ruvalcaba and sporadic cancers.
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PMID:p53 down-regulates phosphatase and tensin homologue deleted on chromosome 10 protein stability partially through caspase-mediated degradation in cells with proteasome dysfunction. 1677 87

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was originally cloned as a tumor suppressor for brain tumors. Now it is known as a tumor suppressor for many tumor types. In this review, we ask the simple question: why is PTEN such a common and important tumor suppressor? The most obvious answer is that there are no other family members that can replace PTEN. As a result, several pathways critical for cell transformation are misregulated. The most important of these is the phosphoinositide 3-kinase (P13K) PI3K-Akt pathway, which has downstream effects on transcription, proliferation, cell survival, invasiveness, and angiogenesis. In addition, PTEN is linked via several mechanisms to the p53 tumor suppressor. Through p53 and additional mechanisms, loss of PTEN leads to genomic instability. Hence, PTEN is important because its loss misregulates multiple Akt-dependent and -independent pathways critical for the development of cancer.
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PMID:Why is PTEN an important tumor suppressor? 1797 52

To clarify the roles of FHIT (fragile histidine triad) and PTEN (phosphatase and tensin homology deleted from human chromosome 10) expression in the genesis and progression of gastric cancers, we examined expression of FHIT and PTEN on tissue microarray containing gastric normal mucosa (n=49), adenoma (n=49), noncancerous mucosa adjacent to carcinoma (n=84) and carcinoma (n=249) by immunohistochemistry. Their expression was compared with clinicopathologic parameters of tumors, including expression of p53 and cysteine protease protein 32 as well as survival time of patients with carcinoma. The results showed expression of FHIT and PTEN were lower in gastric carcinoma than those in normal mucosa, noncancerous mucosa adjacent to carcinoma and adenoma of the stomach (P<0.05). FHIT and PTEN expression showed a significantly negative association with depth of invasion, lymphatic invasion, and lymph node metastasis, liver metastasis, and Union Internationale Contre le Cancer staging of gastric carcinoma (P<0.05). Intestinal-type gastric carcinomas highly expressed FHIT and PTEN protein, compared with diffuse-type ones (P<0.05). Expression of FHIT and PTEN were positively related with expression of p53 and cysteine protease protein 32 in gastric carcinoma (P<0.05), as well as favorable prognosis of the patients with the tumors (P<0.05). There was positive relationship between FHIT and PTEN expression in gastric carcinoma (P<0.05). It was suggested that down-regulated expression of FHIT and PTEN contributed to gastric carcinogenesis possibly by involving in the imbalance between apoptosis and proliferation of cells. Their altered expression underlay the molecular basis of invasion, metastasis, differentiation of gastric carcinoma.
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PMID:Low expression of FHIT and PTEN correlates with malignancy of gastric carcinomas: tissue-array findings. 1809 87

The tumor suppressor gene PTEN (phosphatase and tensin homologue deleted on chromosome 10) is frequently mutated or deleted in various human cancers. PTEN localizes predominantly to the cytoplasm and functions as a lipid phosphatase, thereby negatively regulating the phosphatidylinositol 3-kinase-AKT signaling pathway. PTEN can also localize to the nucleus, where it binds and regulates p53 protein level and transcription activity. However, the precise function of nuclear PTEN and the factors that control PTEN nuclear localization are still largely unknown. In this study, we identified oxidative stress as one of the physiological stimuli that regulate the accumulation of nuclear PTEN. Specifically, oxidative stress inhibits PTEN nuclear export, a process depending on phosphorylation of its amino acid residue Ser-380. Nuclear PTEN, independent of its phosphatase activity, leads to p53-mediated G(1) growth arrest, cell death, and reduction of reactive oxygen species production. Using xenografts propagated from human prostate cancer cell lines, we reveal that nuclear PTEN is sufficient to reduce tumor progression in vivo in a p53-dependent manner. The data outlined in this study suggest a unique role of nuclear PTEN to arrest and protect cells upon oxidative damage and to regulate tumorigenesis. Since tumor cells are constantly exposed to oxidative stress, our study elucidates the cooperative roles of nuclear PTEN with p53 in tumor suppression.
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PMID:PTEN nuclear localization is regulated by oxidative stress and mediates p53-dependent tumor suppression. 1833 25

Abstract Internal mammary artery (IMA) coronary artery bypass grafts (CABG) are remarkably resistant to intimal hyperplasia (IH) as compared to saphenous vein (SV) grafts following aorto-coronary anastomosis. The reason behind this puzzling difference still remains an enigma. In this study, we examined the effects of IGF-1 stimulation on the PI3K-AKT/PKB pathway mediating proliferation of smooth muscle cells (SMCs) of IMA and SV origin and the specific contribution of phosphatase and tensin homologue (PTEN) in regulating the IGF-1-PI3K-AKT/PKB axis under these conditions. Mitogenic activation with IGF-1, time-dependently stimulated the phosphorylation of PI3K and AKT/PKB in the SV SMCs to a much greater extent than the IMA. Conversely, PTEN was found to be significantly more active in IMA SMCs. Transient overexpression of PTEN in SMCs of SV and IMA inhibited AKT/PKB activity and upstream of AKT/PKB, caused a reduction of IGF-1 receptors. Downstream, PTEN overexpression in SV SMCs induced the transactivation of tumour suppressor protein p53 by down-regulating the expression of its inhibitor MDM2. However, PTEN overexpression had no significant effect on MDM2 and p53 expression in IMA SMCs. PTEN overexpression inhibited IGF-1-induced SMC proliferation in both SV and IMA. PTEN suppression, induced by siRNA transfection of IMA SMCs diminished the negative regulation of PI3K-PKB signalling leading to greater proliferative response induced by IGF-1 stimulation. Thus, we show for the first time that early inactivation of PTEN in SV SMCs leads to temporally increased activity of the pro-hyperplasia PI3K-AKT/PKB pathway leading to IH-induced vein graft occlusion. Therefore, modulation of the PI3K-AKT/PKB pathway via PTEN might be a novel and effective strategy in combating SV graft failure following CABG.
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PMID:Temporal PTEN inactivation causes proliferation of saphenous vein smooth muscle cells of human CABG conduits. 1836 44

Glioblastoma multiforme (GBM) occurs rarely in children. Relatively few studies have been performed on molecular properties of pediatric GBMs. Our objective in this study was to evaluate the genetic alterations in pediatric GBM (age < or = 18 years) with special reference to p53, p16, and p27 protein expression, alterations of the epidermal growth factor receptor (EGFR), and deletion of the phosphate and tensin homolog gene (PTEN). Thirty cases of childhood GBMs reported between January 2002 and June 2007 were selected, and slides stained with hematoxylin and eosin were reviewed. Immunohistochemical staining was performed for EGFR, p53, p16, and p27, and tumor proliferation was assessed by calculating the MIB-1 labeling index (LI). Fluorescence in situ hybridization analysis was performed to evaluate for EGFR amplification and PTEN deletion. Histopathological features and MIB-1 LI were similar to adult GBMs. p53 protein expression was observed in 63%. Although EGFR protein overexpression was noted in 23% of cases, corresponding amplification of the EGFR gene was rare (5.5%). Deletion of the PTEN gene was also equally rare (5.5%). One case showed polysomy (chromosomal gains) of chromosomes 7 and 10. Loss of p16 and p27 immunoexpression was observed in 68% and 54% of cases, respectively. In pediatric de novo/primary GBMs, deletion of PTEN and EGFR amplification are rare, while p53 alterations are more frequent compared to primary adult GBMs. Frequency of loss of p16 and p27 immunoexpression is similar to their adult counterparts. This suggests that pediatric malignant gliomas are distinctly different from adult GBMs, highlighting the need for identification of molecular targets that may be adopted for future novel therapeutic strategies.
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PMID:Pediatric glioblastomas: a histopathological and molecular genetic study. 2038 21


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