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)

In some cases, evidence exists that exogenous carcinogenic exposures contribute to the mutation spectrum of the TP53 gene (p53) in human cancers. Although the clearest examples come from dietary and environmental sources, only a restricted number of papers have concentrated specifically on TP53 mutations in tumors from workers exposed to occupational carcinogens. In populations exposed to dietary aflatoxin B1 with liver cancer (AFB1) and ultraviolet (UV)-radiation with skin cancer, a single specific-looking TP53 mutation has been described in some of the tumors. Whether these fingerprints in the TP53 gene can be used to reveal an occupational etiology remains to be shown. In other cases, although differences in the TP53 mutation spectrum exist, they are more diffuse and difficult to interpret at this point. For instance, cigarette smoking seems to induce long-lasting molecular footprints in TP53. However, their use to rule out other occupational exposures as etiological factors in occupational cancers is still very questionable, especially due to the putative synergistic effects of cigarette smoke with other carcinogens. Although interesting implications of possible typical mutation spectra among cancers with other occupational etiologies exist, the data are scanty and await further development of TP53 mutation databases.
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PMID:TP53 mutations in workers exposed to occupational carcinogens. 1261 9

Despite high rates of loss of heterozygosity affecting various chromosomes, the number of tumor suppressor genes (TSGs) found to be consistently involved in primary liver cancer is low. In the past decade, characterization of homozygous deletions (HDs) in tumors has become instrumental to identify new TSGs or to reveal the influence of a particular TSG on the development of a specific tumor type. We performed a detailed HD profiling at 238 critical loci on a collection of 57 hepatobiliary tumor cell lines (hepatocellular, cholangiocellular, and bile duct carcinomas, hepatoblastomas, and immortalized hepatocytes). We identified HDs at 9 independent loci, the analysis of which was extended to 17 additional hepatobiliary tumor cell lines. In total, 34 homozygous losses involving 9 distinct genes were detected in the 74 cell lines analyzed. Besides expected deletions at the p16-INK4A/p14-ARF, FHIT, AXIN1, and p53 genes, we detected HDs at the PTEN, NF2, STK11, BAX, and LRPDIT genes that were formerly not known to be implicated in human liver tumorigenesis. In conclusion, our data suggest that these genes may represent novel liver tumor suppressive targets. Additional tumorigenic pathways should be carefully considered in hepatocarcinogenesis.
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PMID:Homozygous deletion scanning in hepatobiliary tumor cell lines reveals alternative pathways for liver carcinogenesis. 1266 63

Codon 72 exon 4 polymorphism of the p53 gene has been implicated in cancer risk and it has been suggested that it may have an impact on the clinical outcome of the disease. Our objective was to evaluate the association between p53 polymorphism at codon 72 and hepatocellular carcinoma. The p53 codon 72 genotype was examined in 97 biopsy samples from 67 Basque patients histologically diagnosed with hepatocellular carcinoma. Blood samples collected from 111 Basque residents were examined as a control group. The polymorphism was examined by both single strand conformation polymorphism analysis and allele specific polymerase chain reaction. Fisher's exact test was used to evaluate the data. The results showed that there were no statistically significant differences in the frequency of codon 72 polymorphism genotype between patients with liver cancer and healthy controls. We found a frequent loss of proline allele in hepatitis C virus (HCV)-positive carriers. In conclusion, the lack of a significant relationship between this polymorphism and risk of hepatocellular carcinoma suggests that it does not predispose towards hepatocarcinogenesis in this population. We suggest that the frequent loss of the proline allele in HCV-associated carcinogenesis of the liver plays some role in hepatocarcinogenesis.
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PMID:Frequent loss of p53 codon 72 Pro variant in hepatitis C virus-positive carriers with hepatocellular carcinoma. 1270 78

Epidemiological data collected after the atomic-bomb blasts of Hiroshima and Nagasaki have established a link between radiation exposure and human cancer development and are the major source of information for current radiation-induced cancer risk assessment. To determine the mechanistic basis for radiation carcinogenesis, retrospective molecular analyses of archival hepatocellular carcinoma tissues from the atomic-bomb survivors were conducted. The tumor suppressor genes p53 and M6P/IGF2r were examined. HCC cases had either p53 mutations or M6P/IGF2r mutations, but rarely both. Moreover, the frequency of cases with M6P/ IGF2r mutations actually decreased with dose, while those for p53 increased. This implies two independent selection processes leading to liver cancer and that in radiation-induced HCC tumors the spectrum of molecular changes is different from that in "background" tumors.
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PMID:Tracking the errant cell after the atomic bombings: what went wrong? 1285 74

A specific missense mutation in the p53 tumor gene at codon 249 has been reported in over 50% of hepatocellular carcinoma (HCC) tumors and in paired blood samples from areas of high dietary exposure to aflatoxin B1, including Qidong, People's Republic of China. Using a combination of pre-digestion with HaeIII, PCR and mass spectrometry, the temporality of this mutation in plasma before and after the clinical diagnosis of HCC was examined. Sixteen liver cancer cases, diagnosed between 1997 and 2001, were selected from a prospective cohort of 1638 high-risk individuals in Qidong on the basis of available annual plasma samples spanning the years before and after diagnosis. The codon 249 mutation was detected in plasma samples obtained after diagnosis in seven of the 15 cases (46.7%) with PCR amplifiable DNA, which is in accord with the reported prevalence of this mutation in HCC. The persistent detection of this mutation in plasma collected annually following diagnosis was statistically significant (P = 0.024, two-tailed) in repetitive samples following diagnosis. Moreover, the mutation was detected in the plasma of four of eight cases positive at the time of diagnosis at least 1 year and in one case 5 years prior to diagnosis. Tracking of the marker in pre-diagnostic samples was borderline statistically significant (P = 0.066). None of the 18 healthy US control plasma samples had any detectable mutations. We have therefore found that pre-diagnosis biomarkers of specific p53 mutations can be measured in plasma and this suggests a paradigm for developing these markers for use in prevention and intervention trials.
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PMID:Prospective detection of codon 249 mutations in plasma of hepatocellular carcinoma patients. 1286 16

Heterocyclic amines are potent mutagens and carcinogens formed in cooked protein rich foods. In this study, we screened liver tumors induced by 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) in CDF1 mice for beta-catenin and APC mutations and other genetic alterations shown to occur in human hepatocellular carcinomas (HCC), including mutations in the p53 and H-ras genes, c-myc amplification and E-cadherin promoter methylation. SSCP followed by direct DNA sequencing revealed mutations in exon 2 of the beta-catenin gene in 2 of 16 liver tumors (12.5%). Promoter methylation of the E-cadherin gene was detected in one liver tumor induced by MeIQ. There were no mutations in the mutation cluster region of the APC gene, in exons 5-8 of the p53 gene, or in codons 12, 13 and 61 of the H-ras gene, nor c-myc amplification in any of liver tumors induced by MeIQ. These data indicate that except for the occasional disruption of the Wnt pathway through beta-catenin mutations, the genetic pathways involved in the development of HCC differ significantly between human liver cancer and tumors induced in mice by MeIQ, but do not rule out the possibility that heterocyclic amines constitute a carcinogenic risk factor in humans.
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PMID:Beta-catenin mutations in liver tumors induced by 2-amino-3,4-dimethylimidazo[4,5-f]quinoline in CDF1 mice. 1289 27

Telomere maintenance and telomerase reactivation are near universal features of human hepatocellular carcinoma (HCC), yet the shorter telomeres and highly abnormal cytogenetic profiles of HCC suggest that telomere erosion and dysfunction may be operative during the formative stages of tumorigenesis. Previous studies have established that the cancer-enhancing or suppressing impact of telomere dysfunction is highly dependent on several parameters including cell type, tumor stage, and p53 status. Here, to understand better the pathogenetic role of telomere dysfunction in the initiation and progression in human HCC, we have used three mechanistically distinct liver cancer-prone model systems (urokinase plasminogen activator transgenic mice, carbon tetrachloride exposure, and diethylnistrosamine treatment) in the context of successive generations of telomerase-deficient mice null for the telomerase RNA component, mTERC. Across all of the HCC model systems, telomere dysfunction suppressed both the incidence and growth of HCC lesions, a trend that mirrored the level of intratumoral proliferative arrest and apoptosis. On the histological level, telomere dysfunction was associated with a significant increase in the number of early stage neoplastic lesions and a reciprocal decline in the occurrence of high-grade malignancies. These genetic data in the mouse indicate that telomere dysfunction exerts an opposing role in the initiation versus progression of HCC and provide a framework for understanding the intimate link among chronic liver disease, chromosomal instability, and increased HCC in humans.
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PMID:Differential impact of telomere dysfunction on initiation and progression of hepatocellular carcinoma. 1294 29

The effect of different regimes of lysine-pre treatment on mutation at the 3rd nucleotide base of codon 249 which is located at the 7th exon of p53 gene of Chang-liver cells (CCIL13) exposed to aflatoxin B1 (AFB1) has been investigated. There is an indication of inhibition of 1 ug/ml AFB1--induced mutation by pretreatment of cells for 72 hr with 5-molar fold lysine equivalent of 1 ug/ml AFB1 1 u/g ml AFB1 was the does at which there was 50% survival among the cells of CC13 in cytotoxicity studies. The results suggest chemo prevention of AFB1 induced mutation at codon 249 locus of Exon 7 in CCL13's p53 gene and by implication, maybe, AFB1-induced primary liver cancer.
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PMID:P53 gene of chang-liver cells (Atcc-Ccl13) exposed to aflatoxin B1 (Afb): the effect of lysine on mutation at codon 249 of exon 7. 1295 91

The tumor suppressor gene p53 is commonly mutated with high frequencies at certain hot spots in human cancers. In liver cancers there is an especially high frequency of mutations at codon 249. To study the impact of carcinogen targeting and the role of cytosine methylation on the mutation spectrum, a common liver cancer carcinogen aflatoxin B1 (AFB1), was studied using the p53 cDNA template to examine mutation induction. Subsequent mutations were detected with a yeast p53 functional assay and identified by DNA sequencing. The results indicated that cytosine methylation enhances AFB1-induced guanine mutations at CpG sites. However, no mutations were detected at codon 249.
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PMID:In vitro aflatoxin B1-induced p53 mutations. 1296 17

The liver fluke infection-associated intrahepatic cholangiocarcinoma (ICC) is a major liver cancer in Northeast Thailand. The molecular basis of this ICC is poorly understood. To address possible roles of the DNA mismatch repair (MMR) system in ICC carcinogenesis, a fluorescence-labeling PCR/laser scanning technique with high sensitivity was employed to analyze genomic instability in the nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) in 24 fresh and 13 formalin-fixed, paraffin-embedded tissues of ICC and their corresponding normal parts. Microsatellite instability (MSI) was assessed in nDNA, using 12 highly polymorphic loci including 5 Bethesda markers. These loci were mainly related to major MMR genes, hMSH2 and hMLH1. Also 3 (C)n and/or (C)n(A)n repeat instability at 1 noncoding region in the displacement-loop (D-loop) and 2 coding sequences in NADH dehydrogenase subunit 1 and subunit 5 gene in mtDNA were analyzed. MSI was only detected in 1 (2.7%), 6 (16.7%), 1 (2.9%), 1 (2.9%) or 2 (6.3%) out of 37, 36, 35, 35 or 32 cases at BAT-25, D2S123, D3S1611, D11S904 or D17S250, respectively. LOH was found at D3S1298, D3S1561, D5S346 and TP53 in 4 (18.2%) out of 22, 2 (18.2%) out of 11, 6 (33.3%) out of 18 and 3 (12.5%) out of 24 informative cases, respectively. In mtDNA, none except a single case out of the 37 (2.7%) exhibited repeat sequence instability in the D-loop. We conclude that the liver fluke infection-associated ICC in Thailand is classified as low frequency MSI or microsatellite stable type and that DNA MMR system, through hMSH2 and hMLH1 gene mutations, does not play a major role in its carcinogenesis.
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PMID:Infrequent microsatellite instability in liver fluke infection-associated intrahepatic cholangiocarcinomas from Thailand. 1450 36


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