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)

Transcription of hepatocyte-specific genes requires the interaction of their regulatory regions with several nuclear factors. Among them is the hepatocyte nuclear factor 3 (HNF3) family, composed of the HNF3 alpha, HNF3 beta, and HNF3 gamma proteins, which are expressed in the liver and have very similar fork head DNA binding domains. The regulatory regions of numerous hepatocyte-specific genes contain HNF3 binding sites. We examined the role of HNF3 proteins in the liver-specific phenotype by turning off the HNF3 activity in well-differentiated mhAT3F hepatoma cells. Cells were stably transfected with a vector allowing the synthesis of an HNF3 beta fragment consisting of the fork head DNA binding domain without the transactivating amino- and carboxy-terminal domains. The truncated protein was located in the nuclei of cultured hepatoma cells and competed with endogenous HNF3 proteins for binding to cognate DNA sites. Overproduction of this truncated protein, lacking any transactivating activity, induced a dramatic decrease in the expression of liver-specific genes, including those for albumin, transthyretin, transferrin, phosphoenolpyruvate carboxykinase, and aldolase B, whereas the expression of the L-type pyruvate kinase gene, containing no HNF3 binding sites, was unaltered. Neither were the concentrations of various liver-specific transcription factors (HNF3, HNF1, HNF4, and C/EBP alpha) affected. In partial revertants, with a lower ratio of truncated to full-length endogenous HNF3 proteins, previously extinguished genes were re-expressed. Thus, the transactivating domains of HNF3 proteins are needed for the proper expression of a set of liver-specific genes but not for expression of the genes encoding transcription factors found in differentiated hepatocytes.
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PMID:Overproduction of a truncated hepatocyte nuclear factor 3 protein inhibits expression of liver-specific genes in hepatoma cells. 756 96

Three distinct hepatocyte nuclear factor 3 (HNF-3) proteins (alpha, beta, and gamma) are known to regulate the transcription of numerous liver-specific genes. The HNF-3 proteins bind to DNA as monomers through a winged-helix motif, which is also utilized by a number of developmental regulators, including the Drosophila homeotic fork head (fkh) protein. We have previously characterized a strong-affinity HNF-3S site in the transthyretin (TTR) promoter region which is essential for expression in human hepatoma (HepG2) cells. In the current study, we identify an activating protein 1 (AP-1) site which partially overlaps the HNF-3S sequence in the TTR promoter. We show that in HepG2 cells the AP-1 sequence confers 12-O-tetradecanoylphorbol-13-acetate inducibility to the TTR promoter and contributes to normal TTR transcriptional activity. We also demonstrate that the HNF-3 proteins and AP-1 bind independently to the TTR AP-1-HNF-3 site, and cotransfection experiments suggest that they do not cooperate to activate an AP-1-HNF-3 reporter construct. In addition, 12-O-tetradecanoylphorbol-13-acetate exposure of HepG2 cells results in a reciprocal decrease in HNF-3 alpha and -3 gamma expression which may facilitate interaction of AP-1 with the TTR AP-1-HNF-3 site. In order to explore the role of HNF-3 in the liver, we have examined expression patterns of TTR and HNF-3 during the acute-phase response and liver regeneration. Partial hepatectomy produced minimal fluctuation in HNF-3 and TTR expression, suggesting that HNF-3 expression is not influenced by proliferative signals induced during liver regeneration. In acute-phase livers, we observed a dramatic reduction in HNF-3 alpha expression which correlates with a decrease in the expression of its target gene, the TTR gene. Furthermore, consistent with previous studies, the acute-phase livers are induced for c-jun but not c-fos expression. We propose that the reduction in TTR gene expression during the acute phase is likely due to lower HNF-3 alpha expression levels and that the induction of primarily c-jun homodimers, which are poor transcriptional activators, is insufficient to maintain normal TTR expression levels. We also discuss the role of reduced HNF-3 alpha expression in mediating decreased transcription of HNF-3 target genes which respond negatively to cytokine signalling.
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PMID:Decreased expression of hepatocyte nuclear factor 3 alpha during the acute-phase response influences transthyretin gene transcription. 786 29

The changes in serum prealbumin (transthyretin) and serum albumin in acute and chronic liver diseases were investigated. Albumin has long been used as a useful indicator of liver function but serum prealbumin has recently been noted for its clinical significance in acute liver diseases. Serum prealbumin concentrations and liver function tests (albumin, bilirubin, alanine aminotransferase) were determined on blood obtained from normal donors (n = 148) and from patients suffering from liver diseases (n = 78) such as acute viral hepatitis, chronic active hepatitis, cirrhosis and hepatoma. The mean serum prealbumin concentration in normal subjects was 29.6 +/- 4.82 mg/dl while the mean serum prealbumin concentration in patients with liver disease was greatly reduced (acute viral hepatitis = 15.3 +/- 7.4mg/dl; chronic active hepatitis = 10.2 +/- 6.6mg/dl; cirrhosis = 9.9 +/- 6.4mg/dl and hepatoma = 10.7 +/- 4.2). Albumin concentrations dropped slightly (13% compared to control) in acute viral hepatitis but dropped markedly (28% compared to control) in chronic liver diseases. The study suggests that serum prealbumin concentration might be a more sensitive indicator than albumin in assessing liver dysfunction in acute liver diseases.
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PMID:Prealbumin rather than albumin is a more sensitive indicator of acute liver disease. 806 77

We showed previously that the abundance of serum albumin mRNA is decreased in H4-II-E rat hepatoma cells limited for a single essential amino acid (phenylalanine, methionine, leucine, or tryptophan). To define the specificity of this phenomenon, we examined the effect of amino acid limitation on the abundance of mRNAs for 19 genes in the H4-II-E cells. These genes included six genes whose expression is either completely liver-specific or highly enriched in the liver compared with other tissues [albumin, transthyretin (TTR), transferrin, carbamyl phosphate synthetase-I, urate oxidase, class I alcohol dehydrogenase], as well as a number of ubiquitously expressed "housekeeping" genes. The results indicated that the 19 genes could be divided into three classes based on their response to amino acid limitation. Class I genes (the six liver-specific genes and alpha-tubulin) exhibit decreased expression in response to amino acid limitation. The expression of class II genes [beta 2-microglobulin, hypoxanthine-guanine phosphoribosyl transferase (HPRT), H-ferritin, ubiquitin (UbB), insulin-like growth factor binding protein-4, HNF-1 alpha] is not significantly affected by amino acid limitation. Class III genes [gadd153, beta-actin, ubiquitin (UbC), phosphoglycerate kinase-1, C/EBP alpha, C/EBP beta] exhibit increased expression in response to amino acid limitation. Thus, specific inductive as well as repressive effects on gene expression are quite common in amino acid-limited cells. The observation that all six genes whose expression is liver-specific exhibited decreased expression in amino acid-limited cells suggests a common mode of regulation of these genes by amino acid availability. The strong induction by amino acid limitation of the C/EBP inhibitor gadd153 is of interest in this regard, as increased levels of gadd153 could interfere with C/EBP, which is required for high expression of most liver-specific genes. To investigate further the molecular mechanism for the decrease in albumin mRNA abundance, albumin nuclear transcript levels were quantified in control and tryptophan-limited cells. Tryptophan limitation caused a decrease in albumin nuclear transcript abundance, and this decrease preceded the decrease in albumin mRNA, suggesting that the decrease in albumin mRNA was caused at least partly by a decrease in albumin gene transcription. Additional experiments with actinomycin D indicated that albumin mRNA was also destabilized in the tryptophan-limited cells. Thus, the overall results indicate that the decrease in albumin mRNA in the tryptophan-limited cells is caused by a specific decrease in albumin nuclear transcript abundance and destabilization of albumin mRNA.
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PMID:Effect of amino acid limitation on the expression of 19 genes in rat hepatoma cells. 818 73

Familial amyloidotic polyneuropathy (FAP) is a genetic disease characterized by systemic amyloid deposition particularly in the peripheral nervous system. These deposits are composed mainly of a mutant form of the serum protein transthyretin (TTR) having a methionine for valine substitution at position 30-TTR Met 30. The factors involved in the formation of these deposits are unknown. The existence of animal models for FAP should allow elucidation of these factors. As one approach to the development of animal models for amyloidogenesis in FAP, we have constructed recombinant retrovirus vectors, carrying the full length human cDNA for either TTR or TTR Met 30 under the control of the Moloney murine leukemia virus (MoMLV) LTR element. After transfection of the packaging cell line, psi 2, viral stocks were used to infect a rat hepatoma cell line, H56, mouse fibroblast cell line, NIH3T3, and mouse primary fibroblasts. H56 cells efficiently secreted both TTR and TTR Met 30 as assessed by immunoprecipitation and ELISA, whereas NIH3T3 fibroblasts appeared not to release these proteins under the conditions tested. Primary fibroblasts secreted the mutant protein as assessed by ELISA. These genetically modified cells can be grafted into animals for in vivo study of amyloidogenesis, as well as be used in culture to investigate factors that might regulate the rate of amyloid deposition.
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PMID:Retrovirus-mediated gene transfer of transthyretin and transthyretin-methionine 30: a potential tool for the study of amyloidogenesis. 826 24

The capacity of the liver-enriched transcription factor hepatocyte nuclear factor 4 (HNF4) to direct redifferentiation of dedifferentiated rat hepatoma cells was investigated by stable transfection of epitope-tagged HNF4 cDNA into H5 variant cells. HNF4-producing cells expressed the previously silent HNF1 gene and showed activation of some hepatic functions, including alpha1-antitrypsin, beta-fibrinogen, and transthyretin, but not of the endogenous HNF4 gene. Expression of the other hepatocyte-enriched transcription factors was not modified. Treatment of the HNF4tag-expressing cells with dexamethasone induced expression of the transgene by 10-fold, resulting in enhanced expression of target genes of both glucocorticoid hormones and HNF4. The set of activated hepatic genes was extended by treatment of cells with the demethylating agent 5-azacytidine followed by selection in dexamethasone-containing glucose-free medium. Some of the colonies that developed reexpressed the entire set of hepatic functions tested. Fusion of HNF4tag-producing H5 cells with well-differentiated Fao cells showed that only those hybrids which maintained expression of HNF4tag were protected from complete extinction, including that of the Fao HNF4 gene. Thus, H5 cells must produce an extinguisher of the HNF4 gene. In addition, this result implies that HNF4 itself, or its target HNF1, is a positive regulator of HNF4. In conclusion, HNF4tag expression overcomes repression of the hepatic phenotype of the H5 cell without abolishing its potential to extinguish an active genome. Taken together, these results predict that expression of HNF4 should be sufficient to establish heritable expression of many parameters of the hepatic differentiated state.
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PMID:Hepatocyte nuclear factor 4 expression overcomes repression of the hepatic phenotype in dedifferentiated hepatoma cells. 912 39

A series of substituted 4-phenyl-1,4-dihydropyridines 2a-m was tested for their inhibitory effects on L-triiodothyronine (L-T3) uptake by human HepG2 hepatoma cells. The most potent compounds were the nitro-substituted derivatives 2,6-dimethyl-4-(4'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-ethyl ester 5-methyl ester (2m) and the well-known calcium antagonists nitrendipine (2k) and nifedipine (2j) with an uptake inhibition between 80.5 and 85.8% at an application dose of 10(-5) M. On the basis of a theoretical conformational analysis (ab initio MO theory, molecular mechanics, molecular dynamics) of the dihydropyridine derivatives, a unifying stereochemical concept was derived postulating an angular arrangement of the two rings where the phenyl ring of the calcium antagonists, which corresponds to the outer phenyl ring of the thyroid hormones, is bisecting the dihydropyridine ring as a prerequisite for inhibitory potency. This model includes also inhibitors of the N-phenylanthranilic acid type. The interaction of the calcium antagonists with transthyretin (TTR) is discussed in relation to thyroid hormones. The influence of hydrophobicity was estimated by the experimental determination of the 1-octanol/water partition coefficients.
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PMID:Inhibition of thyroid hormone uptake by calcium antagonists of the dihydropyridine class. 915 74

Involvement of the contact system of coagulation in the pathogenesis of various inflammatory diseases is suggested by reduced plasma levels of factor XII (Hageman factor) and prekallikrein generally considered to result from activation of the contact system. However, in many of these diseases patients develop an acute-phase response and, therefore, an alternative explanation for the decreased levels of factor XII could be the downregulation of factor XII gene expression in the liver as described for negative acute-phase proteins. We report here that interleukin-6 (IL-6), the principal cytokine mediating the synthesis of most acute-phase proteins in the liver, downregulates the production of factor XII by the human hepatoma cell line HepG2 by up to 75%. The decrease in protein secretion correlated with an equivalent decrease of factor XII mRNA likely indicating a pretranslational control of factor XII gene expression by IL-6. Downregulation of factor XII production by IL-6 in vitro parallelled that of transthyretin, a known negative acute-phase protein. Moreover, we show that, in patients developing an acute-phase response after immunotherapy with IL-2, plasma levels of factor XII correlate (r = .76, P < .0001) with those of transthyretin. Taken together, these results suggest that factor XII behaves as a negative acute-phase protein.
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PMID:Interleukin-6 downregulates factor XII production by human hepatoma cell line (HepG2). 926 67

Patients with sepsis or after major surgery have decreased plasma levels of the anticoagulant protein antithrombin. In such patients elevated levels of interleukin-6 (IL-6) are present and this interleukin is known to induce positive and negative acute phase responses. To investigate the possibility that antithrombin acts as a negative acute phase response-protein we performed studies on the human hepatoma cell line HepG2 in vitro and baboons in vivo. HepG2 cells were treated with recombinant human IL-6, IL-1beta, or combinations of the latter two, and tested for production of antithrombin, fibrinogen and prealbumin (transthyretin). This treatment resulted in a dose dependent increase in fibrinogen concentration (with a maximum effect of 2.8-2.9-fold) and a dose dependent decrease in prealbumin (with a maximum effect of 0.6-0.7-fold) and antithrombin concentrations (with a maximum effect of 0.6-0.8-fold). Simultaneous treatment of the HepG2 cells with IL-6 (1,000 pg/ml or 2,500 pg/ml) and IL-1beta (25 pg/ml), provided more extensively decreased prealbumin (0.8 and 0.6-fold, respectively) and antithrombin concentration (0.7 and 0.6-fold, respectively) compared to the single interleukin treatment at these concentrations. Baboons treated with 2 microg IL-6 x kg body-weight(-1) x day(-1) showed increased plasma CRP levels (59-fold, p <0.05) and decreased prealbumin (0.9-fold, p <0.05) and antithrombin (0.8-fold, p <0.05) plasma levels, without evidence for coagulation activation. Our results indicate that antithrombin acts as a negative acute phase protein, which may contribute to the decreased antithrombin plasma levels observed after major surgery or in sepsis.
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PMID:Antithrombin acts as a negative acute phase protein as established with studies on HepG2 cells and in baboons. 930 58

Familiar Amyloid Polyneuropathy (FAP), an autosomal dominant inherited multisystemic disorder was first observed by Corino de Andrade, a Portuguese neurologist, in 1939. This disease of Portuguese origin was probably spread by fishermen, mainly to Sweden and Japan. It is characterized by a progressive peripheral polyneuropathy and autonomic neuropathy (erectile sexual disfunction, gastrointestinal disfunction, bladder dysfunction and cardio vascular disease) and malnutrition. There are neural and systemic amiloid deposits. Type I FAP, of Portuguese origin, is the most common variety. The amyloid protein is the variant transthyretin (TTR) in which methionine (MET) is a substitute for valine in position 30 (TTR MET 30). It is mainly produced by the liver (90%) and, in small amounts, by the choroidal plexus. Symptoms usually start in the 3rd and 4th decade of life and the patients usually die within 10-15 years. From the therapeutic options--plasmapheresis, immunoadsorption and liver transplantation; the latter seems to be the only one, which stops the production of TTR MET 30 in a permanent way, by means of the liver. The lack of any other effective therapy and the success of the first liver transplantation performed in Sweden arouse great hope. So far, around 300 patients have been transplanted all over the world. A hundred and thirty of them were transplanted in Portugal. A Kaplan Meier survival curve of the Portuguese patients shows a survival rate of 78% at 5 years. However, in spite of the progression of the disease being halted, the irreversibility of some neurological lesions seems to persist. This fact raises the problem of the timing of the transplantation. It seems that the patients should be transplanted as soon as the symptoms start, since mortality and severe morbidity seems to mainly involve those in whom symptomatic disease has lasted longer than six years. As the explanted liver is a morphologic normal liver, a sequential (domino) transplant has been carried out in 16 cases so far done--by one of the authors (ALF) on patients with either hepatocellular carcinoma or liver metastatic disease.
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PMID:Liver transplantation for familial amyloid polyneuropathy. 984 68


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