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 synthetic dithiolethione Oltipraz has marked cancer chemopreventive and phase II enzyme inducing activity in various animal carcinogenesis models, but has not been examined in any animal models of ductal pancreatic cancer relevant to the human disease. The chemopreventive potential of Oltipraz on pancreatic tumor incidence and multiplicity was examined in the N-nitrosobis(2-oxopropyl)-amine (BOP)-induced ductal pancreatic adenocarcinoma model in Syrian hamsters. Animals were maintained on control semipurified diets or semipurified diets containing 300 and 600 mg/kg Oltipraz beginning 2 weeks prior to BOP initiation and throughout the 26 week study. Oltipraz at 300 mg/kg had no effect on the incidence or multiplicity of preneoplastic, neoplastic or metastatic lesions, while at 600 mg/kg dietary Oltipraz the incidence of pancreatic adenocarcinomas was reduced significantly (P < or = 0.05) compared to BOP-treated controls. Dietary Oltipraz at both doses had a significant influence on reducing mortality and morbidity in tumor-bearing animals with metastatic disease. At 26 weeks, total hepatic glutathione-S transferase (GST) activity and GST mu activity were elevated significantly in Oltipraz-treated animals, while total pancreatic GST activity was reduced, albeit not significantly. Serum lipase activity, a marker for pancreatic damage, exhibited a progressive decline in BOP-treated animals administered Oltipraz compared to BOP-treated controls at 12 weeks of the study; by week 26, lipase activity was comparable in all groups and reduced compared to activity at week 12. Positive nuclear immunostaining for the p53 tumor suppressor protein, a hallmark of human pancreatic cancer and a transient response to DNA damage, was observed in only a small percentage of BOP-induced pancreatic lesions and was not influenced Oltipraz administration. Further chemoprevention and pharmacologic studies of Oltipraz in relevant animal models of ductal pancreatic cancer could provide a foundation for future studies in human populations at potential risk for pancreatic cancer.
Carcinogenesis 1995 Sep
PMID:Chemopreventive activity of Oltipraz against N-nitrosobis(2-oxopropyl)amine (BOP)-induced ductal pancreatic carcinoma development and effects on survival of Syrian golden hamsters. 755 69

A restriction fragment length polymorphism in codon 72 of the p53 gene has been implicated in lung cancer risk, although the functional significance of the polymorphism has not been determined. This association was examined in 109 lung cancer cases (67 African-American and 42 Mexican-American) and 114 controls (74 African-American and 40 Mexican-American) identified from a molecular epidemiological study of lung cancer. The susceptible Pro/Pro genotype was associated with a 1.56-fold higher risk of lung cancer in African-Americans and a 1.95-fold in Mexican-Americans, although neither estimate was statistically significant. In fact, the prevalence of the Pro/Pro genotype was only 2.5% in Mexican-American controls, compared with 20.3% for African-American controls. Patients with the susceptible genotype appeared to have earlier age at diagnosis and lower mean cigarette pack-year exposures than did patients with the Arg/Arg or Arg/Pro genotypes. Risk estimates for the susceptible genotype were 11.29 (1.1, 111.3) for patients < 53 years of age and 14.1 (1.5, 130.6) for patients who reported < 30 pack-years of smoking. The Pro/Pro genotype was not associated with elevated risk in older patients, nor with heavier smokers. If Pro/Pro is a susceptible genotype, the lower prevalence evident in Mexican-Americans may partly explain their lower rates of lung cancer.
Carcinogenesis 1995 Sep
PMID:Higher lung cancer risk for younger African-Americans with the Pro/Pro p53 genotype. 755 76

An association between the BstU I 1-1 (Pro-Pro) genotype of the p53 codon 72 polymorphism and lung cancer has previously been reported by Kawajiri et al. A reanalysis of the data by Kawajiri et al. revealed no significant difference between patients and controls with respect to allele frequencies, and the increased frequency of BstU I 1-1 homozygotes was mostly ascribable to a deviation from the Hardy-Weinberg equilibrium. In an attempt to replicate the results by Kawajiri et al. we have studied three p53 polymorphisms (BstU I and Msp I RFLPs in exon 4 and intron 6 respectively and a 16 bp duplication in intron 3) and their haplotypes in Swedish lung cancer patients and controls. The results concerning the codon 72 polymorphism were largely negative. Thus there was no significant association between lung cancer and the BstU I 1-1 type, and only a marginal difference (P = 0.044) with respect to the BstU I allele frequency when lung cancer patients were compared with patients with chronic obstructive pulmonary disease (COPD). However, when the analysis was based on haplotype frequencies larger differences appeared and it was found that only BstU I 1 (pro) alleles linked to 16 bp 1 alleles were associated with lung cancer. Pro alleles linked to the 16 bp duplication appeared instead to confer some protection against cancer. Thus the codon 72 alleles need not be functionally involved in lung cancer, but may rather be markers in linkage disequilibrium with other cancer susceptibility sites on p53.
Carcinogenesis 1995 Sep
PMID:P53 polymorphisms and haplotypes in lung cancer. 755 81

Colorectal cancer affect the 15% of general population in developed countries. Cancer is a multistep process in which multiple genetic alterations must usually occur in several years. The premalignant step consists of one or multiple aberrant crypts due to hyperproliferation of cells and its shift from the deep third of the crypt to its surface. It has been suggested that abnormality in the APC gene is responsible for this. Furthermore, there exists DNA hypometilation, activation of the gene K-ras and ornithine decarboxylase activity. There is also a loss of MCC gene, that seems to interact with the APC gene. Entire alterations described make possible the Class I adenoma formation. This adenoma, needs the loss of the DCC gene (late stage in the carcinogenesis process), to become a Class II adenoma. The following alteration is deleted and mutation of the p53 gene. There is also an activation of the c-myc oncogene. These two genes are important mechanisms for the conversion of a benign adenoma to a malignant one, adenoma with in situ carcinoma or Class III adenoma. This type of adenoma becomes carcinoma and metastatic stage, throughout inactivation of several tumor suppressor genes. Besides the hereditary APC alteration and other acquired genetic changes as described above there are other associated genetics, antigenics, and enzymes that have an important role in the adenoma-carcinoma sequence. Several carcinogenic factors have been described which also contribute in the adenoma and carcinoma formation: ulcerative colitis, acromegaly, familial history of colonic neoplasia, certain professions, smoking and drinking, consumption of red or processed meat, etc.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Etiology of colorectal cancer]. 755 83

Hepatocellular carcinoma is one of the most common cancers worldwide. Epidemiologic studies shows a striking correlation between areas where this tumor is prevalent and where hepatitis virus B and C are endemic, contaminations of food with mycotoxin aflatoxin B1, excessive alcohol intake, prolonged cigarette smoking, sexual hormones. Combination of chemical, physical, and genetic insults to individual hepatocytes involve changes in the genome transformed or neoplastic cell, depending to both the activation of oncogenes (e.g., ras) and the inactivation of tumor supressor genes (e.g., p53). Advances in radiologic techniques such as ultrasonography, computed tomography, angiography and dosages of tumor markers like alpha-fetoprotein offers still the best for diagnosis and screening for hepatocellular carcinoma. Then the diagnosis has become possible during the early stages, characterized to be a very well-differentiated tumour that has returned its preexisting liver structure, with a certain proportion have a multicentric origin. Hepatocellular carcinoma carries an extremely poor prognosis, with a median survival between 2-4 weeks, for those without treatment. Surgical resection are the only curative modality for this disease. In these patients two main patterns of intrahepatic recurrence after hepatectomy are defined, and depends on the growth of residual satellite tumours or synchronous and metachronous multicentric carcinogenesis. This evolution is estimated to be nearly 50%, with 5-year survival rate of nearly 30%. The presence of cirrhosis, satellite nodules, venous invasion, the absence of capsule formation and positive surgical margin (< or = 5 mm) were associated with higher intrahepatic recurrence rates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Small hepatocellular carcinoma. New concepts on intrahepatic recurrence after hepatectomy in orthotopic liver transplantation]. 757 79

Mutant p53 tumour suppressor gene and c-erbB-2 proto-oncogene are involved in human carcinogenesis, and their protein product detection in human malignancies might influence the evolution of many neoplasms. Our aim was to estimate their association with histopathological and clinical parameters of prognostic value in colorectal cancer. An immunohistochemical assay was undertaken in formalin-fixed sections from tissue specimens of 60 colorectal carcinomas. Nuclear p53 expression was detected in 46.6%, while membranic c-erbB-2 positivity was noticed in 35% of the examined cases. P53 positivity rate significantly correlated with poor differentiation (p < 0.001), high mitotic activity (p < 0.0001), tumour stage (p < 0.001) and 5-year overall survival period (p < 0.01). C-erbB-2 positivity incidence significantly correlated with advanced Dukes' stage (p < 0.001) and high mitotic activity (p < 0.05). Significant association between p53 and c-erbB-2 immunostaining was observed (p < 0.05) and p53/c-erbB-2 co-expression was related to poor differentiation (p < 0.001), high mitotic activity (p < 0.001), advanced Dukes' stage (p < 0.001), tumour aneuploidy (p < 0.05) and worse overall survival (p < 0.05). P53 and c-erbB-2 immunohistochemical detection in combination with known prognostic indicators may be a useful future tool in determining colorectal cancer prognosis and subsequently in deciding on optimal postoperative treatments.
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PMID:Prognostic significance of p53 and c-erbB-2 immunohistochemical evaluation in colorectal adenocarcinoma. 757 15

Tumors are believed to arise as a result of an accumulation of mutations in critical genes involved in the control of cell proliferation. Thyroid neoplasms represent a good model for studying the role of these mutations in epithelial cell multistep carcinogenesis because they comprise a broad spectrum of lesions with different degrees of malignancy. Recent reports have described the involvement of specific genetic alterations in different types of thyroid neoplasms. Papillary carcinomas are characterized by the activation of the receptor tyrosine kinases RET and TRK-A proto-oncogenes. Ras point mutations are frequently observed in tumors with follicular histology and a high prevalence of p53 point mutations have been found in anaplastic carcinomas. A definition of molecular defects characterizing thyroid tumors will be helpful in establishing sensitive and specific detection strategies and, in addition, to define genetic and environmental factors important for their pathogenesis.
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PMID:Molecular defects in thyroid carcinomas: role of the RET oncogene in thyroid neoplastic transformation. 758 78

We have examined a series of 37 oropharyngeal squamous cell carcinomas for the presence of HPV 6/11, 16, and 18 DNA by polymerase chain reaction (PCR)/Southern blotting and for p53 alterations by immunohistochemistry and mutation screening with temperature gradient gel electrophoresis (TGGE). HPV sequences were found in a total of 26 of 37 cancers (70.3%), most frequently HPV 16 (20/37) followed by HPV 18 (11/37). Double infections with HPV 16 and 18 were present in 5 tumours. p53 accumulation was detectable immunohistochemically in 21 of 37 carcinomas (56.8%). There were remarkable differences in the distribution of immunoreactive tumour cells in relation to the tumour grade. A mutation screening for p53 by TGGE, directed to the amplified exons 5-8, revealed p53 mutations in 14 of 37 carcinomas (37.8%). Mutations in two different exons were present in 3 tumours, 11 tumours being hit once. Exon 7 was mutated in 6 carcinomas, exons 5 and 8 in 4 cases, and exon 6 in 3 cases. When grouping the tumours with p53 mutation according to their HPV state, HPV-positive cases showed slightly more mutations (11/26) than HPV-negative cases (3/11). Only 5 of 37 carcinomas (13.5%) contained neither HPV DNA nor p53 alterations. Our results indicate that high-risk HPV and p53 mutations frequently coexist in oropharyngeal carcinomas, in contrast to genital tumours, notably carcinomas of the cervix uteri. This may reflect different pathways in carcinogenesis in squamous cell epithelium from different sites.
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PMID:HPV DNA and p53 alterations in oropharyngeal carcinomas. 758 45

The tumor suppressor protein, p53, is proposed to have a critical role in maintaining the integrity of the genetic material. It has been established that p53 induces a cell cycle block in the G1 phase upon cellular DNA damage. Recent evidence also indicates the involvement of p53 directly and indirectly in nucleotide excision repair (NER). We have examined the role of p53 with respect to UV-induced mutagenesis. By gene transfer, we established a mouse fibroblast cell line overexpressing the val135 temperature-sensitive p53 allele. In this line, p53 activity can be modulated through temperature shift, as confirmed by Western blot and by cell cycle analysis. This cell line was also constructed to contain a recoverable lambda phage shuttle vector carrying the supF mutation reporter gene. Induction of p53 was found to enhance the clonogenic survival of the cells following UV-irradiation compared to the p53-deficient parental mouse cell line. The transfectant line also displayed a 4-fold reduction in the frequency of UV-induced mutations as measured in the chromosomally integrated supF reporter gene. Our results are consistent with a p53-induced cell cycle block at G1 allowing cells to repair chromosomal damage before DNA replication. However, our data may also reflect a more direct role of p53 in the repair of UV-induced lesions as suggested by studies showing that p53 can interact directly with repair factors.
Carcinogenesis 1995 Oct
PMID:Induction of p53 in mouse cells decreases mutagenesis by UV radiation. 758 25

To elucidate whether common genetic events in human urinary bladder carcinogenesis also occur in rodent models, we investigated the presence of p53, H- and K-ras mutations in 18 urinary bladder carcinomas induced by various concentrations of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in male NON/Shi mice. Histopathologically, all were invasive, 11 being squamous cell carcinomas (SCCs) and the remaining seven being transitional cell carcinomas (TCCs). Using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis followed by DNA sequencing, p53, H- and K-ras mutations were observed in 14 (78%; exons 5-7), two (11%; one each on exons 1 and 2) and one (5.6%; exon 1) animals respectively. The frequencies of mutations in p53 exons 5, 6 and 7 were 7 (39%), 4 (22%), and 9 (50%) respectively, and no mutation was found in exon 8. All mutations involved one base-pair substitution with or without amino acid changes and the types of base-pair substitution were random. No evident association was observed between mutation sites and the histological phenotypes. In conclusion, p53 mutations are frequent in BBN-induced mouse invasive urinary bladder tumors, at similar levels to those observed for human high-grade invasive carcinomas, and this plus their distribution suggests their possible participation in this model of urinary bladder carcinogenesis.
Carcinogenesis 1995 Oct
PMID:Frequent mutations of the p53 gene and infrequent H- and K-ras mutations in urinary bladder carcinomas of NON/Shi mice treated with N-butyl-N-(4-hydroxybutyl)nitrosamine. 758 36


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