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 molecular pathology of human pancreatic cancer is poorly understood, particularly with regard to the role of known tumor-suppressor genes. We have examined the expression of the p53 and Rb-1 tumor-suppressor genes in seven human pancreatic carcinoma cell lines and 10 primary pancreatic carcinomas. Examination of the Rb-1 gene by Northern hybridization and immunoprecipitation analyses revealed the absence of Rb-1 protein expression in two cell lines. Moreover, regions of absent nuclear staining in two primary pancreatic carcinomas were detected by immunohistochemical analysis. Investigation of p53 by Southern, Northern, immunohistochemical and immunoprecipitation analyses revealed multiple abnormalities, including gross rearrangements in two cell lines, the absence of detectable p53 transcript in two cell lines and a truncated transcript in one line. Six cell lines overexpressed p53 protein, while one line revealed the absence of p53 product by immunohistochemical and immunoprecipitation analyses. Sequence analysis of exons 5-8 of the p53 gene confirmed these analyses, revealing missense mutations in all seven cell lines in codons 181, 220, 248, 249, 265, 272 and 273. Of 10 mutations identified, nine were transitions and 50% were in codon 273. Immunohistochemical analyses of frozen primary pancreatic carcinomas revealed positive nuclear staining for p53 in 40% of cases. Mutations were identified in codons 238 and 286 and in intron 9 in several representative specimens. Alterations in the p53 and Rb-1 genes may be important features in the development of human pancreatic cancer.
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PMID:Human pancreatic carcinomas and cell lines reveal frequent and multiple alterations in the p53 and Rb-1 tumor-suppressor genes. 163 Aug 14

There are abnormalities in the structure and/or function of several oncogenes and growth factors in human pancreatic cancer, notably the EGF receptor and its ligand TGF alpha, c-erb B-2 proto-oncogene, Ki-ras oncogene and the tumour suppressor gene p53. The temporal sequence of their activation and the nature of the aetiological agents responsible for their activation are not yet clear. In vitro pancreatic culture systems and transgenic animal experiments are needed to reconstruct and define those molecular events that are necessary and sufficient for the neoplastic phenotype.
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PMID:Growth factors and oncogenes in pancreatic cancer. 196 2

p53 and MTS1 are known to be mutationally inactivated in pancreatic adenocarcinoma. Other tumor suppressor genes are likely also to play a role. To define chromosomal arms which may harbor additional tumor suppressor genes, we performed an extensive allelotype on pancreatic cancer utilizing a xenograft enrichment technique. Eighty-eight percent (28/32) of primary tumors gave rise to xenografts. Eighteen cases were used in a PCR-based allelotype using 283 polymorphic markers, over 2800 informative assays, and an average coverage of 4.1 informative markers per chromosomal arm per case. Highly frequent allelic loss (> 60%) was seen at chromosomes 1p, 9p, 17p, and 18q. Moderately frequent allelic loss (40-60%) was seen at 3p, 6p, 6q, 8p, 10q, 12q, 13q, 18p, 21q, and 22q. The average fractional allelic loss was 0.36. Allelic and sequence stability was demonstrated among 64 parallel and second-passage xenografts derived from 12 cases of pancreatic adenocarcinoma with the ascertainment of over 3000 single alleles. The findings were confirmed in primary tumors. In only two instances were discrepancies revealed between the allelic loss data obtained from corresponding parallel xenografts, probably due to the xenografting of minor subpopulations, reflecting genetic heterogeneity of the primary tumor.
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PMID:Allelotype of pancreatic adenocarcinoma using xenograft enrichment. 755 47

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.
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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

The p53 tumor suppressor gene is mutated in the majority of pancreatic adenocarcinomas, and several studies have suggested that loss of p53 function may contribute to the aggressive clinical behavior of pancreas cancer. Although immunocytochemical accumulation of the p53 gene product has previously been assessed as a marker for p53 mutations in cancers of the pancreas and other organ systems, the relationship between p53 mutations and p53 protein accumulation is variable. The cyclin-dependent kinase inhibitor, p21 (also known as WAF1 and CIP1), is induced by wild-type but not mutant p53, and recent work has implicated p21 as a downstream mediator of the growth-suppressing and apoptosis-promoting functions of wild-type p53. In the present work, we sought to determine whether loss of p21 expression could more precisely identify those tumors with p53 mutations and/or loss, compared with immunocytochemical assessment of p53 protein accumulation. We evaluated p53 and p21 expression immunohistochemically in a series of 21 ductal adenocarcinomas of the pancreas with known p53 mutational status. Diffuse overexpression of p53 was found in 3 of 8 cases (38%) with wild-type p53 and 7 of 13 cases (54%) with p53 mutations with or without loss of heterozygosity at 17p. Surprisingly, expression of p21 correlated neither with p53 mutational status nor with p53 protein expression. In particular, strong p21 expression was seen even in carcinomas in which molecular analysis revealed a frameshift mutation in one allele of p53 and loss of the second. These data suggest that p21 expression in pancreatic adenocarcinoma may also be induced by a p53-independent pathway and that p21 expression, as assessed immunocytochemically, does not reflect the functional status of p53 in these carcinomas.
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PMID:p53-independent expression of the cyclin-dependent kinase inhibitor p21 in pancreatic carcinoma. 757 63

In our current understanding of pancreatic carcinoma, these neoplasms can arise either sporadically or in familial clusters. Extensive chromosome abnormalities are frequent, as is loss of heterozygosity at loci known to contain the tumor suppressor genes DCC, p53, and MTS1. Although the genetic examination of all pancreatic cancers is important, the examination of familial cases is especially useful in that these allow the identification of uniform genetic alterations that are inherited through the germ line. Much additional work needs to be done before the genetic basis of pancreatic cancer is completely understood. Although our knowledge is limited, it is clear that genetic analyses can be used to establish the prognosis for a patient with pancreatic cancer and, it is hoped, will someday be used in the management, treatment, and detection of pancreatic cancer.
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PMID:Familial pancreatic cancer and the genetics of pancreatic cancer. 766 Feb 49

Specific markers for pancreatic or biliary cancer have been developed in the past few years. Ca 19-9 has a good sensitivity but it is also increased in benign cholestasis. Mutations in the p53 gene are commonly reported in pancreatic cancer and can be detected by a serological analysis. The aim of this work was to find out the sensitivity and specificity of this new assay in diagnosing cancer of the pancreas or of the bile ducts. The presence of antibodies against p53 was determined by an enzyme linked immunosorbent assay (ELISA) in 29 patients with pancreatic cancer, 33 with biliary tract cancer, and 33 with benign biliary or pancreatic diseases as controls. p53 Antibodies were detected in eight of 29 patients with pancreatic cancer (28%), in five of 33 patients with biliary tract (15%), and in one patient (3%) with stones of the common bile duct. The sensitivity and the specificity for the diagnosis of malignant biliary or pancreatic diseases were 21% and 96% respectively. It is concluded that the presence of p53 antibodies in the serum of patients with pancreatic and biliary diseases is specific for malignancy and independent from the presence of cholestatic disease.
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PMID:Antibodies against p53 protein in serum of patients with benign or malignant pancreatic and biliary diseases. 769 9

Immunohistochemical analysis of the p53 tumor suppressor gene was performed in 69 human pancreatic ductal adenocarcinomas, using a highly specific anti-p53 antibody. Nuclear immunoreactivity was found in 40 tumors, yielding an overall frequency of 58%. Immunoblotting confirmed that nuclear immunoreactivity was associated with increased p53 protein levels. p53 mRNA levels were increased in 9 of 9 tested cancers, without evidence for gene amplification. Analysis of the immunostaining data by chi-square and log-rank indicated that the presence of nuclear immunoreactivity correlated with a more advanced clinical stage, and a statistically significant decrease in the post-operative survival period. In 12 cancers, metastatic tissue samples were also available for p53 analysis. Nuclear p53 immunostaining in the primary tumors was not always associated with p53 immunoreactivity in the metastatic samples, and metastases occurred in the absence of nuclear p53 immunoreactivity in the primary lesion. These findings suggest that increased p53 protein levels in human pancreatic cancer may be due not only to p53 mutations which attenuate the degradation of the protein but also to an increase in p53 mRNA levels leading to increased p53 synthesis, and that p53 nuclear immunoreactivity in these cancers implies enhanced tumor aggressiveness but is not essential for the development of metastases.
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PMID:p53 expression in human pancreatic cancer correlates with enhanced biological aggressiveness. 787 70

Antisense oligonucleotides targeting p53 have been hailed as a potentially new technique for treating patients with cancer, and there have been encouraging reports of good patient tolerance in vivo and of antiproliferative effects in vitro. However, evidence is lacking that these oligonucleotides are acting via an antisense interaction to modulate p53 expression. We examined a phosphorothioate antisense oligonucleotide, directed against exon 10 of the TP53 gene, and a chimaeric phosphorothioate-phosphodiester oligonucleotide directed against the p53 translation initiation codon. Both failed to specifically suppress p53 protein production in a cell-free assay system or to have any effect on mutant p53 expression by human pancreatic cancer cell lines. Antiproliferative effects were apparent, especially with the phosphorothioate antisense oligonucleotide, but this was independent of the p53 status of the cells (mutant, wild-type or absent) and also occurred with the control (sense and randomised) oligonucleotides. The most dramatic antiproliferative effects were seen with the 'control' phosphorothioate oligonucleotides. These findings suggest that the antiproliferative effects of some antisense oligonucleotides may be unrelated to expression of the gene they have been designed to target.
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PMID:Antisense oligonucleotides directed against p53 have antiproliferative effects unrelated to effects on p53 expression. 788 Jul 19

Genomic alterations in the p53 tumour-suppressor gene and overexpression of p53 protein, resulting from gene mutations, are frequently found in pancreatic cancer. In this study we analysed the sera of 160 patients with malignant and benign pancreatic diseases for the presence of circulating antibodies to the p53 protein. The analysis of the sera was performed using two different enzyme-linked immunosorbent assay (ELISA) systems. To further substantiate the results, all sera were analysed by the Western blot technique using a cell lysate of PancTu-1 cells (p53 mutation at codon 176) as antigen source. Additionally, all positive sera were analysed by the Western blot technique using recombinant p53 as the antigen source. Although the rate of p53 mutations in pancreatic tumours is of the same order as in other adenocarcinomas (> or = 50%), an antibody response was found in only 5/78 (6.4%) sera from patients with pancreatic cancer. Two out of 82 (2.4%) sera of patients with benign pancreatic diseases were clearly positive for p53 antibodies. One additional specimen was weakly positive, i.e. only in one ELISA and Western blot system.
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PMID:Detection of the anti-p53 antibody response in malignant and benign pancreatic disease. 794 80


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