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)

The mutation of R273-->H in the p53 core domain (p53-CD) is one of the most common mutations found in human cancers. Although the 273H p53-CD retains the wild-type conformation and stability, it lacks sequence-specific DNA binding, a transactivation function and growth suppression. However, mutating T284-->R in the 273H p53-CD restores the DNA binding affinity, and transactivation and tumour suppressor functions. Since X-ray/NMR structures of DNA-free or DNA-bound mutant p53-CD molecules are unavailable, the factors governing the loss and rescue of sequence-specific DNA binding in the 273H and 273H+284R p53-CD, respectively, are unclear. Hence, we have carried out molecular dynamics (MD) simulations of the wild-type, single mutant and double mutant p53-CD, free and DNA bound, in the presence of explicit water molecules. Based on the MD structures, the DNA-binding free energy of each p53 molecule has been computed and decomposed into component energies and contributions from the interface residues. The wild-type and mutant p53-CD MD structures were found to be consistent with the antibody-binding, X-ray and NMR data. The predicted DNA binding affinity and specificity of both mutant p53-CDs were also in accord with experimental data. The non-detectable DNA binding of the 273H p53-CD is due mainly to the disruption of a hydrogen-bonding network involving R273, D281 and R280, leading to a loss of major groove binding by R280 and K120. The restoration of DNA binding affinity and specificity of the 273H+284R p53-CD is due mainly to the introduction of another DNA-binding site at position 284, leading to a recovery of major groove binding by R280 and K120. The important role of water molecules and the DNA major groove conformation as well as implications for structure-based linker rescue of the 273H p53-CD DNA-binding affinity are discussed.
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PMID:Factors governing loss and rescue of DNA binding upon single and double mutations in the p53 core domain. 1191 17

Terminal epithelial cell differentiation is a crucial step in development. In the kidney, failure of terminal differentiation causes dysplasia, cystogenesis, and cancer. The present study provides multiple lines of evidence implicating the tumor suppressor protein p53 in terminal differentiation of the renal epithelium. In the developing kidney, p53 is highly enriched in epithelial cells expressing renal function genes (RFGs), such as receptors for vasoactive hormones, the sodium pump, and epithelial sodium and water channels. In comparison, proliferating renal progenitors express little if any p53 or RFGs. p53 binds to and transactivates the promoters of RFGs. In contrast, expression of a dominant negative mutant form of p53 inhibits endogenous RFG expression. Moreover, binding of endogenous p53 to the promoters of RFGs coincides with the differentiation process and is attenuated once renal epithelial cells are fully differentiated. Finally, p53-null pups exhibit a previously unrecognized aberrant renal phenotype and spatial disorganization of RFGs. Interestingly, the p53-related protein p73 is unable to functionally compensate for the loss of p53 and fails to efficiently activate RFG transcription. We conclude that p53 promotes the biochemical and morphological differentiation of the renal epithelium. Aberrations in p53-mediated terminal differentiation may therefore play a role in the pathogenesis of nephron dysgenesis and dysfunction.
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PMID:A role for p53 in terminal epithelial cell differentiation. 1195 39

The effect of high molecular weight water-soluble chitosan (WSC) on serum starvation-induced apoptosis in human astrocytes (CCF-STTG1 Cells) was investigated. WSC, having an average molecular weight of 300 kDa and a degree of deacetylation over 90%, can be produced using a simple multi-step membrane separation process. Serum starvation led to growth arrest, rounding up of cells and appearance of p53 bands. Prolonged (48 h) incubation in serum starved medium led to cell detachment and death. WSC significantly protected the serum starvation-induced cellular rounding up and protected the serum starvation-induced cell death as tested by flow cytometry. WSC also protected serum starvation-induced p53 activation as determined by Western blot. These results suggest that WSC may prevent serum starvation-induced apoptosis of CCF-STTG1 cells via p53 inactivation.
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PMID:High molecular weight water-soluble chitosan protects against apoptosis induced by serum starvation in human astrocytes. 1198 7

Microcirculation plays a crucial role in mucosal physiological function as well as repair of gastric mucosal damage. Endothelial cell damage is known to disturb microcirculation and suppress angiogenesis. Therefore, the direct effect of Helicobacter pylori on endothelial cells in vitro was investigated with H. pylori water extract. The effect of H. pylori water extract on cell proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs) was evaluated. The ratio of BrdU-positive HUVECs in both cagA/vacA-positive and -negative H. pylori water extract-treated groups was significantly lower at 24 h than that in the control group, but Escherichia coli water extract did not affect the proliferation of these endothelial cells. Apoptosis was induced by H. pylori water extracts after incubation for 24 h in a cagA/vacA-independent manner. In the mitochondrial permeability transition assay, tetramethylrhodamine methyl ester was accumulated in mitochondria of HUVECs. Western blot analysis showed no difference in the level of total p53 protein in H. pylori water extract-treated and non-treated cells, but the level of phosphorylated p53 protein was increased in the treated cells at 15 and 60 min after addition of the extract. Reverse transcription (RT)-PCR products for p21 and Bax were elevated in the H. pylori water extract-treated cells. p21 levels began to increase 0.5-1 h after addition of the extract, whereas Bax increased in the period 0.5-2 h. H. pylori induced a disturbance of cell proliferation and apoptosis in the vascular endothelial cells which may contribute to gastric mucosal injury and to delayed healing of gastric lesions.
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PMID:Inhibition of cell proliferation and induction of apoptosis by Helicobacter pylori through increased phosphorylated p53, p21 and Bax expression in endothelial cells. 1199 Apr 90

Cholestatic liver injury is caused by hepatocellular apoptosis induced by toxic bile salts. We have studied the effects of a traditional Chinese herbal medicine, Salvia miltiorrhiza, on apoptotic cell death in bile duct-ligated (BDL) rats. We also attempted to clarify the molecular mechanisms of the hepatoprotective effects of S. miltiorrhiza in this animal model. A water extract of S. miltiorrhiza (Sm-X; 200 mg/kg; po) was administered to BDL rats for 10 days. Rats were euthanized and apoptosis was detected in liver tissue by TUNEL staining. Western blot analysis and immunostaining for alpha-smooth muscle actin (alpha-SMA), Bax, Bcl-2, and p53 were performed. Results show that the treatment of BDL rats with Sm-X significantly improved the liver function parameters, although the expression of alpha-SMA, a marker of hepatic stellate cell activation, was not affected. Treatment with Sm-X significantly reduced the number of apoptotic cells. A time-dependent decrease in Bax protein level and an increase in Bcl-2 protein level were observed in BDL rats treated with Sm-X. Immunohistochemical analysis demonstrated that p53 was strongly positive in hepatocyte nuclei of BDL rats but that treatment with Sm-X induced a cytoplasmic sequestration of p53. Taken together, hepatoprotective effects of Sm-X partially ascribe to the antiapoptotic property in hepatocytes. Treatment of Sm-X-induced cytoplasmic sequestration of p53, downregulation of Bax, and upregulation of Bcl-2 protein. This study identifies and delineates signaling factors involved in the antiapoptotic properties of Sm-X and suggests a potential application of S. miltiorrhiza in the clinical management of hepatic disease induced by toxic bile salts following biliary obstruction.
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PMID:Salvia miltiorrhiza inhibits biliary obstruction-induced hepatocyte apoptosis by cytoplasmic sequestration of p53. 1212 60

Human papillomaviruses (HPVs) are major pathogens associated with the development of cancer of the uterine cervix, the most common malignant tumour of women worldwide. Reliable diagnosis of HPV infection, particularly the 'high-risk' types (16/18), may facilitate early identification of 'high-risk' populations for developing cervical cancer and may augment the sensitivity and specificity of primary cervical cancer screening programmes by complementing the conventional Pap test. A simple paper smear method has been developed for dry collection, transport and storage of cervical smears/scrapes at room temperature for subsequent detection of HPV DNA by PCR assay. Imprint biopsies, blood and fine-needle aspirates were also collected by this method. The cervical scrapes or other body fluids were smeared (within 0.5-1 cm diameter) and dried on to sterile small slides made of Whatman 3MM filter paper, and stored individually at room temperature or at 4 degrees C. A small piece (2-3 mm) of the paper smear was punched or cut out with a sterile surgical blade, boiled in an eppendorf tube containing 50 microl of distilled water for 5 min and used directly for PCR amplification. The quality and quantity of DNA derived from paper smears and the results of PCR amplifications for HPV type 16, BRCA1 and p53 genes were identical to those obtained from the same samples following collection in PBS, storage (-70 degrees C) and phenol-chloroform-based DNA extraction. DNA was stable in the paper smears for up to a year, whether stored at room temperature or at 4 degrees C. This method is simple, rapid and cost-effective, and can be effectively employed for large-scale population screening, especially for regions where the specimens are to be transported from distant places to the laboratory.
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PMID:A simple 'paper smear' method for dry collection, transport and storage of cervical cytological specimens for rapid screening of HPV infection by PCR. 1820 98

We have evaluated morphologic alterations and epithelial cell apoptosis and proliferation of colonic mucosa in the acute and chronic phases of DSS-induced colitis. Colitis was induced in Sprague-Dawley rats by 7 days of 4% DSS oral administration followed by 7 days of tap water for one, two, and three cycles. Control rats receved tap water only. Morphological changes in colonic mucosa were evaluated and scored by light and scanning electron microscopy. Apoptosis was studied by TUNEL assay and cell proliferation by Ki-67 immunoreaction. The expression of both proapoptotic (Fas, FasL, Bax, p53) and antiapoptotic (Bc12) cellular proteins was determined by immunohistochemistry. Morphologic assessment showed the most severe colonic epithelial lesions and inflammation in the distal colon with a trend to increasing severity from the first to the third DSS cycle. In DSS rats, the epithelial apoptotic index increased 20-fold after the first cycle and 120-fold after the second and third cycles compared with the controls; in the same way, the expression index of proapoptotic proteins (Fas, FasL, Bax, p53) dramatically increased. The proliferative index increased about 40 to 60-fold compared to controls, with no difference among the three DSS cycles. In conclusion, DSS-induced colitis in rats, which has many structural and ultrastructural features similar to those seen in human ulcerative colitis, is a suitable model for studying increased epithelial apoptosis and proliferation. Further studies employing this model will permitt two hypotheses to be tested. (1) Increased apoptosis may lead to a breakdown of the epithelial barrier function and facilitate the mucosal invasion of intraluminal microorganisms and/or antigens. (2) Abnormal and persistent epithelial hyperproliferation could be causally related to the development of colorectal cancers in the setting of chronic colonic inflammation.
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PMID:Increased proliferation and apoptosis of colonic epithelial cells in dextran sulfate sodium-induced colitis in rats. 1214 99

Arsenic is a well-documented human carcinogen, and contamination with this heavy metal is of global concern, presenting a major issue in environmental health. However, the mechanism by which arsenic induces cancer is unknown, in large part due to the lack of an appropriate animal model. In the present set of experiments, we focused on dimethylarsinic acid (DMA), a major metabolite of arsenic in most mammals including humans. We provide, for the first time, the full data, including detailed pathology, of the carcinogenicity of DMA in male F344 rats in a 2-year bioassay, along with the first assessment of the genetic alteration patterns in the induced rat urinary bladder tumors. Additionally, to test the hypothesis that reactive oxygen species (ROS) may play a role in DMA carcinogenesis, 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in urinary bladder was examined. In experiment 1, a total of 144 male F344 rats at 10 weeks of age were randomly divided into four groups that received DMA at concentrations of 0, 12.5, 50 and 200 p.p.m. in the drinking water, respectively, for 104 weeks. From weeks 97-104, urinary bladder tumors were observed in 8 of 31 and 12 of 31 rats in groups treated with 50 and 200 p.p.m. DMA, respectively, and the preneoplastic lesion, papillary or nodular hyperplasias (PN hyperplasia), was noted in 12 and 14 rats, respectively. DMA treatment did not cause tumors in other organs and no urinary bladder tumors or preneoplastic lesions were evident in the 0 and 12.5 p.p.m.-treated groups. Urinary levels of arsenicals increased significantly in a dose-responsive manner except for arsenobetaine (AsBe). DMA and trimethylarsine oxide (TMAO) were the major compounds detected in the urine, with small amounts of monomethylarsonic acid (MMA) and tetramethylarsonium (TeMa) also detected. Significantly increased 5-bromo-2'-deoxyuridine (BrdU) labeling indices were observed in the morphologically normal epithelium of the groups treated with 50 and 200 p.p.m. DMA. Mutation analysis showed that DMA-induced rat urinary bladder tumors had a low rate of H-ras mutations (2 of 20, 10%). No alterations of the p53, K-ras or beta-catenin genes were detected. Only one TCC (6%) demonstrated nuclear accumulation of p53 protein by immunohistochemistry. In 16 of 18 (89%) of the TTCs and 3 of 4 (75%) of the papillomas, decreased p27(kip1) expression could be demonstrated. Cyclin D1 overexpression was observed in 26 of 47 (55%) PN hyperplasias, 3 of 4 (75%) papillomas, and 10 of 18 (56%) TCCs. As a molecular marker of oxidative stress, increased COX-2 expression was noted in 17 of 18 (94%) TCCs, 4 of 4 (100%) papillomas, and 39 of 47 (83%) PN hyperplasias. In experiment 2, 8-OHdG formation in urinary bladder was significantly increased after treatment with 200 p.p.m. DMA in the drinking water for 2 weeks compared with the controls. The studies demonstrated DMA to be a carcinogen for the rat urinary bladder and suggested that DMA exposure may be relevant to the carcinogenic risk of inorganic arsenic in humans. Diverse genetic alterations observed in DMA-induced urinary bladder tumors imply that multiple genes are involved in stages of DMA-induced tumor development. Furthermore, generation of ROS is likely to play an important role in the early stages of DMA carcinogenesis.
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PMID:Carcinogenicity of dimethylarsinic acid in male F344 rats and genetic alterations in induced urinary bladder tumors. 1215 59

Interest in exploiting traditional medicines for prevention or treatment of cancer is increasing. Extracts from the herb Tripterygium wilfordii hook F have been used in China for centuries to treat immune-related disorders. Recently it was reported that triptolide (PG490), a purified compound from Tripterygium, possessed antitumor properties and induced apoptosis by p53-independent mechanisms in a variety of malignant cell lines. This property of triptolide attracted our attention because we have found that primary cultures of human prostatic epithelial cells derived from normal tissues and adenocarcinomas are in general extremely resistant to apoptosis. Furthermore, the function of wild-type p53 is impaired in these cells such that drugs that require p53 activity to induce cell death are ineffective. Therefore, the properties of triptolide and the recent approval of its water-soluble form (PG490-88) for entry into Phase I clinical trials suggested that this drug was a promising candidate to test for antitumor activity against prostate cells. Experiments presented here demonstrated that triptolide had dose-dependent effects on both normal and cancer-derived primary cultures of human prostatic epithelial cells. Low concentrations of triptolide inhibited cell proliferation and induced a senescence-like phenotype. Higher concentrations of triptolide induced apoptosis that was unexpectedly associated with nuclear accumulation of p53. Paradoxically, levels of the p53 target genes, p21(WAF1/CIP1) and hdm-2, were reduced, as was bcl-2. Our preclinical studies suggest that triptolide might be an effective preventive as well as therapeutic agent against prostate cancer and that triptolide may activate a functional p53 pathway in prostate cells.
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PMID:Antiproliferative and proapoptotic activities of triptolide (PG490), a natural product entering clinical trials, on primary cultures of human prostatic epithelial cells. 1217 99

Mutations of the p53 tumor suppressor gene constitute one of the most frequent molecular changes in a wide variety of human cancers, including those in the esophagus. Mice deficient in p53 have recently attracted attention for their potential to identify chemical genotoxins. In this study we investigated the susceptibility of p53 nullizygous (-/-), heterozygous (+/-) and wild-type (+/+) mice to methyl-N-amylnitrosamine (MNAN), which specifically induces esophageal tumors in mice and rats. The p53 (+/-) and (+/+) mice were treated with 5 or 15 p.p.m. MNAN in their drinking water for 8 weeks then maintained without further treatment for an additional 7 or 17 weeks, being killed at experimental weeks 15 or 25. An additional group of p53 (-/-) mice were given 5 p.p.m. MNAN for 8 weeks and killed at week 15. At 15 weeks in the 5 p.p.m. groups, squamous cell carcinomas (SCCs) were observed in 10/12 (83.3%) p53 (-/-) and 1/15 (6.7%) p53 (+/-) mice, but in none of the p53 (+/+) mice. In the animals receiving 15 p.p.m., 2/14 (14.3%) p53 (+/-) and 1/11 (9.1%) p53 (+/+) mice developed SCCs. At 25 weeks, the incidence of SCCs was 7/16 (43.8%) and 8/14 (57.1%) in p53 (+/-) mice and 1/13 (7.7%) and 2/10 (20.0%) in p53 (+/+) mice at 5 and 15 p.p.m., respectively. Of the SCCs examined by PCR-single strand conformation polymorphism analysis, 61% (14/23) from p53 (+/-) and 50% (6/12) from p53 (+/+) mice demonstrated mutations in the p53 gene (exons 5-8). These results indicate the order of susceptibility to MNAN-induced esophageal tumorigenesis to be as follows: nullizygotes (-/-) > heterozygotes (+/-) > wild-type (+/+), and provide strong evidence of involvement of p53 mutations in the development of esophageal SCCs.
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PMID:Elevated susceptibility of the p53 knockout mouse esophagus to methyl-N-amylnitrosamine carcinogenesis. 1218 99


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