Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0345904 (liver cancer)
 15,188 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The p53 tumor suppressor gene has proven to be one of the genes most often mutated in human cancers. It involves mainly point mutations leading to amino acid substitutions in the central region of the protein which impairs normal functions. Analysis of the mutational events that target the p53 gene has revealed evidence for both exogenous and endogenous mutational mechanisms. For example, the p53 mutational spectrum reveals evidence for a direct causal effect of ultraviolet radiation in skin cancer, of aflatoxin B1 in liver cancer, and of tobacco smoke in lung cancer. This novel field, molecular epidemiology of human cancer risk, has added a new dimension to classical associative epidemiology by providing a direct link between human cancer and carcinogen exposure. For such analysis, we devised a generic software called UMD (Universal Mutation Database). It was developed as a generic software to create locus-specific databases (LSDBs) with the 4(th) Dimension(R) package from ACI. This software includes an optimized structure to assist and secure data entry and to allow the input of various clinical data.
 ...
PMID:p53 website and analysis of p53 gene mutations in human cancer: forging a link between epidemiology and carcinogenesis. 1061 30

The intronless N-myc2 gene was originally identified as the major target of hepatitis virus insertion in woodchuck liver tumors. Here we report that transgenic mice carrying the N-myc2 gene controlled by woodchuck hepatitis virus (WHV) regulatory sequences are highly predisposed to liver cancer. In a WHV/N-myc2 transgenic line, hepatocellular carcinomas or adenomas arose in over 70% of mice, despite barely detectable expression of the methylated transgene in liver cells. Furthermore, a transgenic founder carrying unmethylated transgene sequences succumbed to a large liver tumor by the age of two months, demonstrating the high oncogenicity of the woodchuck N-myc2 retroposon. Stabilizing mutations or deletions of beta-catenin were found in 25% of liver tumors and correlated with reduced tumor latency (P<0.05), confirming the important role of beta-catenin activation in Myc-induced tumorigenesis. The ability of the tumor suppressor gene p53 to cooperate with N-myc2 in liver cell transformation was tested by introducing a p53-null allele into WHV/N-myc2 transgenic mice. The loss of one p53 allele in transgenic animals markedly accelerated the onset of liver cancer (P=0.0001), and most tumors of WHV/N-myc2 p53+/Delta mice harbored either a deletion of the wt p53 allele or a beta-catenin mutation. These findings provide direct evidence that activation of N-myc2 and reduction of p53 levels act synergistically during multistage carcinogenesis in vivo and suggest that different genetic pathways may underlie liver carcinogenesis initiated by a myc transgene. Oncogene (2000).
 ...
PMID:Hepatocellular carcinoma in WHV/N-myc2 transgenic mice: oncogenic mutations of beta-catenin and synergistic effect of p53 null alleles. 1085 Oct 67

Fibrolamellar hepatocellular carcinoma (FHCC) is a unique histologic variant of HCC that occurs in a younger subset of patients than classical HCC, and is associated with a better prognosis. Wilms tumor (WT) is a malignant embryonal neoplasm of the kidney and is one of the most common solid tumors of childhood, occurring at an estimated frequency of 1 in 8000 to 10,000 births. Although second malignant neoplasms (SMNs) following therapy for WTs have been reported in the liver, the coexistence of HCC and WT is extremely rare. We present the first report of a synchronous anaplastic WT and FHCC in a previously healthy 4-year-old girl. Despite the presence of focal immunohistochemical positivity for p53 in the WT, molecular analysis failed to reveal a germline or somatic p53 mutation, and was inconclusive in establishing a clonal relation between the two tumors.
 ...
PMID:Synchronous wilms tumor and fibrolamellar hepatocellular carcinoma: report of a case. 1089 Sep 35

Relationship between p53 protein overexpression and clinicopathological findings and the proliferative activity was studied in 50 cases of hepatocellular carcinoma (34 biopsy and 16 surgically resected cases) using immunohistochemistry. Overexpression of p53 was observed in 26.5% of biopsy cases and 31. 3% of surgically resected cases. Investigation of the relationship between the p53-positive rate and the clinical stage of HCC showed that it was significantly higher in Stage IV (the most advanced cancer; 54.5%) than in Stage I/II/III (13.0%) (p<0.05). Examination of the relationship between the p53-positive rate and tumor differentiation in the biopsy cases showed that p53 was positive in 9.1% of well differentiated carcinomas, 21.4% of moderately differentiated carcinomas, and 55.6% of poorly differentiated carcinomas, indicating that p53 positivity increased as tumors became less differentiated. The p53-positive rate of poorly differentiated carcinoma (55.6%) was significantly higher than that of well and moderately differentiated carcinoma (16.0%) (p<0.05). In the surgically resected cases, p53 overexpression tended to be more frequent in the less differentiated parts of each tumor nodule. In cases with nodule in nodule pattern of HCC, the p53-positive rate was different among nodules with the same level of differentiation. Examination of tumor cell proliferative activity using the proliferating cell nuclear antigen L.I. showed that this indicator was significantly higher in the p53-positive tumors than in the p53-negative tumors (52.7+/-32.4% vs. 32.4+/-15.3%: p<0.05). These results suggest that p53 overexpression may be involved in determining the dedifferentiation and the proliferative activity of HCC. Examination of the surgically resected cases confirmed that p53 overexpression became heterogeneous during the multistep carcinogenesis and growth process of HCC, which is considered to develop from a single cell. This finding suggests that p53 overexpression may be involved in tumor progression.
 ...
PMID:Relationship between p53 overexpression and the proliferative activity in hepatocellular carcinoma. 1089 56

Vinyl chloride (VC) is both a known carcinogen and a regulated chemical, and its production capacity has almost doubled over the last 20 years, currently 27 million tons/year worldwide. According to recent reports it is still a cause for concern. VC has been found as a degradation product of chloroethylene solvents (perchloroethylene and trichloroethylene) and in landfill gas and groundwater at concentrations up to 200 mg/m(3) and 10 mg/L, respectively. Worldwide occupational exposure to VC still seems to be high in some countries (e.g., averages of approximately 1,300 mg/m(3) until 1987 in one factory), and exposure may also be high in others where VC is not regulated. By combining the most relevant epidemiologic studies from several countries, we observed a 5-fold excess of liver cancer, primarily because of a 45-fold excess risk from angiosarcoma of the liver (ASL). The number of ASL cases reported up to the end of 1998 was 197 worldwide. The average latency for ASL is 22 years. Some studies show a small excess risk for hepatocellular carcinoma, and others suggest a possible risk of brain tumors among highly exposed workers. Lung cancer, lymphomas, or leukemia do not seem to be related to VC exposure according to recent results. The mutation spectra observed in rat and human liver tumors (ASL and/or hepatocellular carcinoma) that are associated with exposure to VC are clearly distinct from those observed in sporadic liver tumors or hepatic tumors that are associated with other exposures. In rats, the substitution mutations found at A:T base pairs in the ras and p53 genes are consistent with the promutagenic properties of the DNA adduct 1,N(6)-ethenoadenine formed from VC metabolites. Risk assessments derived from animal studies seem to overestimate the actual risk of cancer when comparing estimated and reported cases of ASL.
 ...
PMID:Vinyl chloride: still a cause for concern. 1090 93

Hemochromatosis and Wilson disease (WD), characterized by the excess hepatic deposition of iron and copper, respectively, produce oxidative stress and increase the risk of liver cancer. Because the frequency of p53 mutated alleles in nontumorous human tissue may be a biomarker of oxyradical damage and identify individuals at increased cancer risk, we have determined the frequency of p53 mutated alleles in nontumorous liver tissue from WD and hemochromatosis patients. When compared with the liver samples from normal controls, higher frequencies of G:C to T:A transversions at codon 249 (P < 0.001) and C:G to A:T transversions and C:G to T:A transitions at codon 250 (P < 0.001 and P < 0.005) were found in liver tissue from WD cases, and a higher frequency of G:C to T:A transversions at codon 249 (P < 0.05) also was found in liver tissue from hemochromatosis cases. Sixty percent of the WD and 28% of hemochromatosis cases also showed a higher expression of inducible nitric oxide synthase in the liver, which suggests nitric oxide as a source of increased oxidative stress. A high level of etheno-DNA adducts, formed from oxyradical-induced lipid peroxidation, in liver from WD and hemochromatosis patients has been reported previously. Therefore, we exposed a wild-type p53 TK-6 lymphoblastoid cell line to 4-hydroxynonenal, an unsaturated aldehyde involved in lipid peroxidation, and observed an increase in G to T transversions at p53 codon 249 (AGG to AGT). These results are consistent with the hypothesis that the generation of oxygen/nitrogen species and unsaturated aldehydes from iron and copper overload in hemochromatosis and WD causes mutations in the p53 tumor suppressor gene.
 ...
PMID:Increased p53 mutation load in nontumorous human liver of wilson disease and hemochromatosis: oxyradical overload diseases. 1105 Jan 62

Hepatitis B virus X (HBx) protein implicated in the development of liver cancer may inhibit the function of p53 tumor suppressor protein through cytoplasmic retention of p53 protein. Here, we attempt to investigate whether the functional inhibition of p53 protein by HBx protein is reversible. First, we provide the evidence for the association of endogenous p53 protein with HBx by co-immunoprecipitation in stable Chang cells that express HBx protein in an inducible manner (ChangX-34). By immunofluorescence microscopy, the major location of p53 protein of ChangX-34 cells was confirmed at the nuclear periphery as well as in the cytoplasm where HBx protein is mainly expressed. Surprisingly, anticancer drug, adriamycin induces the nuclear translocation of p53 protein sequestered in the cytoplasm. This change is accompanied by the restoration of p53 activity, which results in increased transcriptional activity at the p53-responsive DNA elements as well as increase of p21WAF1 mRNA expression. Further, we observed the induction of cell death and G1 arrest in these cells upon adriamycin treatment regardless of HBx expression. Together, we demonstrate that functional inhibition of p53 protein through its cytoplasmic retention by HBx protein is reversible. These results may be extended into other tumors of which p53 activity is modulated by viral oncoproteins.
 ...
PMID:Chemotherapeutic drug, adriamycin, restores the function of p53 protein in hepatitis B virus X (HBx) protein-expressing liver cells. 1106 53

Hepatocellular carcinoma (HCC) is the most common type of liver cancer, the major risk factors being hepatitis B and C viruses and aflatoxins; other factors such as alcohol are also of importance in some populations. Aflatoxin exposure biomarkers include urinary aflatoxin metabolites and aflatoxin-albumin adducts in peripheral blood. These biomarkers are well validated and have been applied in studies of many populations worldwide. They are proving to be valuable end-points in intervention studies, including chemoprevention studies. The biomarkers permit assessment of primary prevention measures to reduce aflatoxin intake. In addition, the determination of individual urinary aflatoxin metabolite profiles means that the effectiveness of chemopreventive agents designed to modulate aflatoxin metabolism can also be evaluated. Both aflatoxin-albumin adducts and urinary aflatoxin metabolites have been associated with increased HCC risk in prospective studies, indicating the predictive value of these biomarkers at the group level. However, given the multifactorial and multistep nature of HCC, it is unlikely that these exposure biomarkers will be predictive at the individual level or be of value as surrogate end-points in longer-term intervention trials aimed at reducing disease incidence. Aflatoxin-related mutations at codon 249 of the p53 gene in plasma may be more relevant in this regard but their application requires further understanding of the temporal appearance of this biomarker in relation to the natural history of the disease.
 ...
PMID:Exposure biomarkers in chemoprevention studies of liver cancer. 1122 Jun 64

A rat cell line-nominated CC-62 derived from a combined hepatocellular and cholangiocellular carcinoma obtained by administration of 2-acetylaminofluorene to male Wistar rats, has been established. Using light and electron microscopy it was determined that morphologically the tumor consisted of a mixed population of hepatocytes and cholangiolar neoplastic cells, intermingled with small, undifferentiated oval-like cells. The CC-62 line has been maintained through 90 passages in culture adopting a paving stone arrangement. Doubling time at the 12th passage was 23 h. Immunostaining with a panel of antisera was performed to identify the cytological profiles of the cell line. There was no k-ras or p53 expression by immunohistochemistry, and molecular biology failed to detect mutations. Molecular analysis by reverse transcriptase-polymerase chain reaction revealed transcripts for c-met but no expression of HGF messenger ribonucleic acid. Three cell lines cloned from CC-62 showed the same immunohistochemical and molecular pattern as the parental line. Cytogenetic analysis revealed a chromosome number ranging from 74 to 82 with a modal number of 79 but no clonal structural abnormalities were found. Deoxyribonucleic acid ploidy analysis showed an aneuploid peak. CC-62 caused tumors 1 mo after subcutaneous transplantation into nude mice, with morphological patterns of mucosecretory solid and spindle-shaped carcinoma. This cell line is the first established from a primary rat combined hepatocellular and cholangiocellular neoplasm. The resulting cells expressed biological and morphological markers of hepatocytes and cholangiolar cells. Therefore this cell line may contribute to a better understanding of the histogenesis of liver cancer.
 ...
PMID:Characterization of a new rat cell line established from 2'AAF-induced combined hepatocellular cholangiocellular carcinoma. 1124 1

To observe the influence of fungus polysaccharides compounds (FPC) in inducing human liver cancer cell Bel-7402 apoptosis in cell cultivating in vitro, the authors analyzed tumor inhibitive gene P53 expression in Bel-7402 apoptosis by applying double immuno-marker. The result showed that the multilevel of FPC could all apparently induce Bel-7402 apoptosis. With the enhancement of FPC concentration, the authors observed chromatin condensation in some phases companying with the characteristic apoptosis. In the meantime, it could also greatly reduce the G1 and S, with obviously dose-response relationship. The percentage of cell apoptosis increased with the enhancing of concentration. In the high-level group the authors found typical DNA ladder eletrophoresis stripe. The result showed that the mechanism of the FPC antineoplastic effect had an intimate relation with its induction to apoptosis and that the result of FPC inducing tumor cell apoptosis had the character of P53 independence.
 ...
PMID:[Study of fungus polysaccharides compounds (FPC) in inducing the apoptosis of liver cancer cell Bel-7402]. 1125 62


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>