Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The genetic components required for glucocorticoid induction of apoptosis were studied by using somatic cell hybridization. Intertypic whole-cell hybrids were generated by crossing the glucocorticoid-resistant rat liver cell line Fado-2 with the glucocorticoid-sensitive mouse thymoma cell line BW5147.3. Morphological and biochemical criteria were used to assess sensitivity or resistance to glucocorticoid-induced cell death. Both phenotypes were observed, and all of the hybrids retained a functional glucocorticoid receptor as judged by their abilities to induce the metallothionein gene in response to dexamethasone (Dex). Sensitivity to apoptosis did not correlate with morphological phenotype in that not all suspension cells were sensitive. The effect of glucocorticoids on the expression of apoptosis-linked genes was analyzed in a subset of Dex-sensitive and Dex-resistant hybrids. p53 and c-myc mRNAs were present in parental cells as well as sensitive and resistant hybrid cells, and their levels were not affected by glucocorticoid treatment. bcl-2 expression was restricted to the thymoma cell line and was also not affected by glucocorticoids. We did not detect any bcl-2 mRNA in the hepatoma cell line and the hybrids, suggesting that, as with most tissue-specific genes, bcl-2 is regulated in trans. Furthermore, while the majority of hybrids analyzed retained a full complement of mouse chromosomes, sensitive hybrids were missing some rat chromosomes (preferentially chromosomes 16 and 19), indicating that apoptosis is subject to trans repression. Resistant cells thus appear to repress the activity or synthesis of a nuclear factor that interacts with a glucocorticoid-dependent gene(s) to activate the cell death pathway.
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PMID:Evidence for trans regulation of apoptosis in intertypic somatic cell hybrids. 806 45

Mutations of the p53 gene are found in various human cancers. The frequency of its mutation is reported to increase during tumor progression in most tumors. In human gliomas, mutations of the p53 gene are found in about one-third of the malignant forms and in few of the benign ones, indicating their possible involvement in tumor progression. On the other hand, we have recently shown that basic fibroblast growth factor (basic FGF) plays a crucial role in tumor progression as an autocrine growth factor in tissues of human gliomas. Therefore, we hypothesized that p53 might regulate the promoter activity of the basic FGF gene, which has several GC boxes and no typical TATA box. In this study, cotransfection assays using human glioblastoma and hepatocellular carcinoma cells and establishment of stable cell lines expressing mutant-type p53 were performed. The basic FGF gene promoter was demonstrated to be regulated by p53 at the transcriptional level and its basal core promoter was found to be responsive to p53. Expression of endogenous basic FGF was also demonstrated to be activated by mutant type p53. Wild-type p53 repressed gene expression of the basic FGF and its mutant activated it in vitro, implying one of the possible pathways in tumor progression.
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PMID:Transcriptional regulation of basic fibroblast growth factor gene by p53 in human glioblastoma and hepatocellular carcinoma cells. 809 Jul 61

The mutational spectrum of the p53 gene was analyzed in 53 hepatocellular carcinomas. Somatic mutations of the p53 gene were detected in 17 cases (32%). Among these 17 mutations, 9 were missense mutations; the mutations in the other 8 cases were nonsense mutations, deletions, or mutations at the intron-exon junctions. These mutations were found in a wide region stretching from exon 4 to exon 10 without any single mutational hot spot. G:C to T:A transversions were predominant, suggesting the involvement of environmental mutagens in the mutagenesis of the p53 gene in a subset of the hepatocellular carcinoma cases. Mutations of the p53 gene occurred frequently in advanced tumors, although several tumors in the early stages also showed mutations. A deletion map of chromosome 17 was constructed by using 10 polymorphic probes and was compared with the p53 gene mutation in each case. Loss of heterozygosity (LOH) on chromosome 17p was observed in 49% of the cases (24 of 49), and two commonly deleted regions were detected (around the p53 locus and at 17p13.3 to the telomere). Sixteen of the 17 cases with p53 gene mutations showed LOH around the p53 locus, and mutations were rare in hepatocellular carcinomas without LOH. However, no mutations were detected in 8 cases with LOH on 17p, suggesting the possibility that an unidentified tumor suppressor gene(s) located on 17p may have also been involved in hepatocarcinogenesis.
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PMID:Role and mutational heterogeneity of the p53 gene in hepatocellular carcinoma. 809 50

Aberrations of the p53 gene were observed in high frequency in HCCs in China, Mozambique and Japan. Most of the mutations were G to T transversions in codon 249 of the p53 gene in HCCs in China and Mozambique, where aflatoxin B1 was a risk factor. These findings strongly suggest that aflatoxin B1 induced this type of mutations. On the other hand, in Japanese HCCs, no mutation was observed in codon 249, indicating a different cause of HCC development. Pathological analyses revealed that p53 mutations were detected only in advanced HCCs and not in early HCCs. In addition, aberrations of the RB gene were observed in only tumors carrying mutated p53 gene. These results indicate the involvement of at least two tumor suppressor genes in a late stage of hepatocarcinogenesis. Possible mechanisms of HCC formation are discussed.
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PMID:[Co-inactivation of the p53 and RB genes in human hepato cellular carcinoma]. 809 51

The relationship between p53 gene mutation and carcinogenesis and evolution of malignant tumor is a hot spot of current research in molecular pathology of tumors. The detection of p53 gene mutation usually needs complicated DNA blotting and sequencing technology. We used newly-developed PCR-RFLP technique to detect the point mutation of the 7th exon of p53 gene in fresh and paraffin embedded tissues of hepatocellular carcinoma in studying 40 cases. It was shown that the p53 gene mutation rate in hepatocellular carcinoma was 30%, and this mutation was correlated with the metastasis of hepatocellular carcinoma.
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PMID:[A molecular pathological study of p53 gene in hepatocellular carcinoma]. 810 Nov 39

To examine the significance of mutation of the p53 tumour suppressor gene in the development of human hepatocellular carcinoma in a high-prevalence area for hepatitis B viral infection but a low-exposure area for aflatoxin B1, the spectrum of p53 gene mutations was examined in 21 tumour samples from Hong Kong Chinese patients, all of whom were HBsAg positive. DNA sequencing covering exons 5 to 9 of the p53 gene and Hae III restriction enzyme digestion for preliminary assessment of mutation at codon 249 were performed. Immunohistochemical staining with anti-p53 monoclonal antibodies was done on both tumour and nontumour liver tissues. Six tumours (28.6%) showed a p53 mutation and all were point mutations. Of the six point mutations, two (9.5%) were at codon 249 and both were G to T transversions (AGG-->ATG and AGG-->AGT transversions). The remaining point mutations were transversions scattered at codon 172 (exon 5), 214 (exon 6), 273 (exon 8) and 330 (exon 9). Mutated p53 protein was detected in five of these six cases with demonstrable point mutations by DNA sequencing, in contrast to none detected in all of the 15 cases without demonstrable point mutations. The presence of p53 mutations, including those at codon 249, did not show a significant association with tumour size, sex, age, tumour invasiveness in terms of liver invasion, microsatellites and venous permeation, cirrhosis and encapsulation, but tumours with low cellular differentiation tended to have a higher incidence (71%) of point mutations than those with high cellular differentiation (8%). In conclusion, both the overall p53 mutation rate and that a codon 249 in HCC in Hong Kong Chinese are lower than those reported in tumours from China and sub-Saharan Africa. The low mutation rate at codon 249 is compatible with a low aflatoxin exposure. A special type of p53 mutation has not been found to be associated with hepatitis B viral infection. Mutations of p53 gene tends to occur in tumours with low cellular differentiation, suggesting a late occurrence in the event of tumour progression.
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PMID:p53 gene mutation spectrum in hepatocellular carcinomas in Hong Kong Chinese. 810 45

Chronic active hepatitis caused by infection with hepatitis B virus, a DNA virus, is a major risk factor for human hepatocellular carcinoma. Since the oncogenicity of several DNA viruses is dependent on the interaction of their viral oncoproteins with cellular tumor-suppressor gene products, we investigated the interaction between hepatitis B virus X protein (HBX) and human wild-type p53 protein. HBX complexes with the wild-type p53 protein and inhibits its sequence-specific DNA binding in vitro. HBX expression also inhibits p53-mediated transcriptional activation in vivo and the in vitro association of p53 and ERCC3, a general transcription factor involved in nucleotide excision repair. Therefore, HBX may affect a wide range of p53 functions and contribute to the molecular pathogenesis of human hepatocellular carcinoma.
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PMID:Hepatitis B virus X protein inhibits p53 sequence-specific DNA binding, transcriptional activity, and association with transcription factor ERCC3. 813 79

Large cell liver cell dysplasia (LCD), a suggested preneoplastic change progressing to hepatocellular carcinoma, has been reported associated with alpha-1-antitrypsin deficiency which in some countries has an increased frequency of hepatocellular carcinoma. We examined the nonneoplastic liver from 13 alpha-1-antitrypsin deficiency patients for LCD and, using a labeled streptavidin-biotin technique, for immunohistochemical markers: AAT (1/200), hepatitis B surface (HBsAg, prediluted) and core (HBcAg, 1/400) antigens, and monoclonal (1/20) and polyclonal (1/40) mutant p53, a tumor suppressor gene. There were eight males and five females ranging from 2 mo to 76 yr (mean 40 yr). Nine livers showed cirrhosis, one chronic persistent hepatitis, one portal fibrosis, and two cholestatic hepatitis (in the two infants). The nine cases with LCD included five males and four females of mean age 46 yr (range, 17-71), eight with cirrhosis and one with portal fibrosis. Only one liver with LCD and cirrhosis had HBcAg in cirrhotic and dysplastic cells. No patient had developed hepatocellular carcinoma. All 13 livers were immunonegative for HBsAg and mutant p53, and immunopositive for AAT present in normal, cirrhotic, and dysplastic liver cells. Thus, LCD was identified in 82% of adult alpha-1-antitrypsin deficiency livers (69% including infantile patients), 89% with cirrhosis, and none with malignancy. HB expression was rarely present; serology for HB and/or hepatitis C was positive in 46% adults. Immunoreactive AAT was present in dysplastic cells. p53 gene mutations do not appear to have a role in the pathogenesis of LCD in alpha-1-antitrypsin deficiency.
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PMID:Liver cell dysplasia in alpha-1-antitrypsin deficiency. 815 50

Mutations affecting the p53 gene abrogate its tumor suppressor activity. It is, however, unclear whether such mutations can generate mutant p53 proteins with an intrinsic transforming ability. More importantly, the mechanism(s) by which they exert such activity is unknown. We report here that p53-deficient hepatoma cells (Hep3B) transfected with mutant p53-249ser (codon 249 Arg-->Ser) acquire a new phenotype with an increased in vitro survival and mitotic activity. However, such a phenotypic change is not sufficient to cause a major shift in the poor tumorigenic potential of these cells. This is apparently due to transforming growth factor beta 1-mediated apoptotic death of Hep3B cells which is not affected by the expression of p53-249ser.
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PMID:Hepatocarcinoma-specific mutant p53-249ser induces mitotic activity but has no effect on transforming growth factor beta 1-mediated apoptosis. 817 5

Fifty-eight percent of hepatocellular carcinomas (HCCs) from Qidong, China, contain an AGG to AGT mutation at codon 249 of the p53 tumor suppressor gene, a mutation that is rarely seen in HCCs from Western countries. The population of Qidong is exposed to high levels of aflatoxin B1 (AFB1), a fungal toxin that has been shown to induce the same mutation in cultured human HCC cells. To investigate the role of AFB1 and of these p53 mutations in hepatocarcinogenesis, normal liver samples from the United States, Thailand, and Qidong (where AFB1 exposures are negligible, low and high, respectively) were examined for p53 mutations. The frequency of the AGG to AGT mutation at codon 249 paralleled the level of AFB1 exposure, which supports the hypothesis that this toxin has a causative--and probably early--role in hepatocarcinogenesis.
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PMID:Geographic variation of p53 mutational profile in nonmalignant human liver. 819 Dec 84


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