Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Inflammatory processes, aside from cholesterol, play a central role in atherogenesis. Human C-reactive protein (huCRP) signals systemic inflammation and independently predicts future cardiovascular risk. Cholesterol-lowering statins reduce atherosclerosis and plasma huCRP levels. Evidence is sought for a direct anti-inflammatory statin effect in vivo, independent of effects on plasma cholesterol and atherogenesis. The effect of atorvastatin and simvastatin on huCRP expression was studied in nonatherosclerotic huCRP transgenic mice and compared with another class of hypolipidemic drugs, peroxisome proliferator-activated receptor-alpha (PPARalpha) activators, notably fenofibrate and Wy14643. Like statins, PPARalpha activators combine antiatherosclerotic properties with huCRP-lowering effects. Dietary treatment with statins or PPARalpha activators decreased basal and interleukin-1beta (IL-1beta)-induced plasma huCRP levels independently of cholesterol lowering. These direct anti-inflammatory in vivo effects occurred at the transcriptional level and could be confirmed in cultured human liver slices and in human hepatoma cells transiently transfected with a huCRP promoter-driven luciferase reporter. A molecular rationale for the suppression of IL-1-induced huCRP transcription is provided by showing that statins and PPARalpha activators up-regulate IkappaBalpha protein expression. This results in a reduced nuclear translocation of p50-nuclear factor kappa B (NFkappaB) and thereby decreased amounts of nuclear p50-NFkappaB approximately CCAAT/enhancer binding protein beta (C/EBPbeta) complexes, which determine the huCRP transcription rate. Our results provide conclusive evidence for a direct suppressive effect of statins and PPARalpha activators on huCRP expression independent of cholesterol lowering and atherogenesis.
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PMID:Evidence for anti-inflammatory activity of statins and PPARalpha activators in human C-reactive protein transgenic mice in vivo and in cultured human hepatocytes in vitro. 1497 45

Retinoic acid-receptor-related orphan receptor (ROR) alpha is a nuclear receptor involved in many pathophysiological processes such as cerebellar ataxia, inflammation, atherosclerosis and angiogenesis. In the present study we first demonstrate that hypoxia increases the amount of Rora transcripts in a wide panel of cell lines derived from diverse tissues. In addition, we identified a functional promoter sequence upstream of the first exon of the human Rora gene, spanning -487 and -45 from the translation initiation site of RORalpha1. When cloned in a luciferase reporter vector, this sequence allowed the efficient transcription of the luciferase gene in several cell lines. Interestingly, the activity of the Rora promoter was enhanced by hypoxia in HepG2 human hepatoma cells, and this effect was dependent on an HRE (hypoxia response element) spanning from -229 to -225. Using electrophoretic-mobility-shift assays, we showed that HIF-1 (hypoxia-inducible factor 1), which plays a key role in the transcriptional response to hypoxia, bound to this HRE. Overexpression of HIF-1alpha increased the activity of the Rora promoter through the HRE. Overexpression of a dominant-negative form of HIF-1alpha producing transcriptionally inactive HIF-1alpha/HIF-1beta dimers abolished hypoxic activation of the Rora promoter. This indicated that HIF-1 is involved in the response of RORalpha to hypoxia. Taken together, our data reveal Rora as a new HIF-1 target gene. This illustrates, at the molecular level, the existence of cross-talk between signalling pathways mediated by HIF-1 and those mediated by nuclear receptors.
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PMID:The gene encoding human retinoic acid-receptor-related orphan receptor alpha is a target for hypoxia-inducible factor 1. 1527 Jul 19

The mechanisms by which saturated and polyunsaturated fatty acids may exert their effects on levels of blood cholesterol and human atherosclerosis have not been fully established. In this work, we studied the translational effects of myristic (14:0) and eicosapentaenoic (20:5) acids on 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase from Reuber H35 hepatoma cells. This enzyme is an intrinsic membrane, 96-kDa protein whose proteolysis releases an enzymatically active, 52- to 56-kDa, soluble fragment. We optimized an immunoblot procedure for quantifying small amounts of both the native and the soluble forms of HMG-CoA reductase from Reuber H35 hepatoma cells. We demonstrated that the upregulation of HMG-CoA reductase by a acid is due to an increase of the HMG-CoA reductase protein; therefore, protein synthesis would be required for the increase of HMG-CoA reductase activity caused by this fatty acid. In contrast, the downregulation of HMG-CoA reductase caused by eicosapentaenoic acid is not due to decreased protein synthesis, since similar levels of protein were found in the presence and absence of this fatty acid. Results obtained with cycloheximide as a protein-synthesis inhibitor confirm these findings.
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PMID:Differential translational effects of myristic acid and eicosapentaenoic acid on 3-hydroxy-3-methylglutaryl-CoA reductase from Reuber H35 hepatoma cells. 1533 32

Daesungki-Tang (DST), a drug preparation consisting of four herbs, that is, Rhei radix et rhizoma (RR; the roots of Rheum coreanum Nakai, Daehwang in Korean), Aurantiii frutus immaturus (AFI; immature fruits of Poncirus trifolita Rafin., Jisil in Korean), Magnoliae cortex (MC; the stem bark of Magnolia officinalis Rehd. Et Wils., Hubak in Korean), and Mirabilite (MS; Matrii sulfas, Mangcho in Korean), is a traditional Korean herbal medicine that is widely used in the treatment of cancer metastasis, gastrointestinal complaints, vascular disorders, and atherosclerosis-related disorders. In this study, water extracts of DST and each of the four ingredient herbs were prepared. The extracts were tested for cytotoxic activity on human hepatocellular carcinoma cells, Hep3B cells using the XTT assay method. The inhibitory effect of the extracts on the invasion of Hep3B cells was also tested using matrigel precoated transwell chambers. DST effectively inhibited the invasion of Hep3B cells, compared with the control groups in a dose-dependent manner. In addition, a gelatin zymography assay showed that DST decreased the gelatinolytic activity of matrix metalloproteinases-2 (MMP-2; IC50 = 87 microg/ml) and -9 (MMP-9; IC50 = 75 microg/ml) that are secreted from Hep3B cells, respectively. Among the four herbal ingredients of DST, only MC has been shown to significantly inhibit the invasion of Hep3B cells and MMP-2 and -9 activities. From these results, it can be concluded that DST has some potential for use as an antitumor agent.
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PMID:Inhibitory effect of Daesungki-Tang on the invasiveness potential of hepatocellular carcinoma through inhibition of matrix metalloproteinase-2 and -9 activities. 1545 2

Hepatic hydroxymethyl glutary coenzyme A HMG-CoA reductase inhibitors (statins) have various anti atherosclerosis pleiotropic effects that are independent of cholesterol reduction. Human serum paraoxonase 1 (PON1) is associated with high-density lipoprotein (HDL) and inhibits the oxidative modification of low-density lipoprotein (LDL). We investigated the effects of statins on PON1 gene transcription using a reporter gene assay. Promoter activity of the PON1 gene was estimated by measuring luciferase activity of plasmids with a PON1 promoter region transfected into human hepatoma HepG2 cells and human embryonic kidney (HEK) 293 cells. Pitavastatin, simvastatin, and atorvastatin each significantly increased PON1 promoter activity, and the transactivation by pitavastatin was abrogated by mevalonic acid and farnesyl pyrophosphate (FPP), however, not by geranylgeranyl pyrophosphate. Further, PON1 promoter activity was enhanced by farnesyl transferase inhibitor (FTI), but not by geranylgeranyl transferase inhibitor (GGTI). PON1 gene transcription has been reported to be dependent on Sp1 and the transactivation by pitavastatin was completely abrogated by mithramycin, an inhibitor of Sp1. Our results suggest that pitavastatin activates transcription of the PON1 gene through the FPP pathway, which may play an important role in the anti atherosclerotic effects of statins.
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PMID:Effect of pitavastatin on transactivation of human serum paraoxonase 1 gene. 1569 Mar 6

ApoC-I plays an important role in controlling plasma lipid metabolism, however little is known about factors regulating the hepatic synthesis and secretion of this apolipoprotein. In the present study, we have carried out experiments with human hepatoma (HepG2) cells, in order to determine the effect of different tissue culture conditions on cellular lipid levels and on the production of apoC-I (and apoE) at the protein and mRNA level. Cells incubated for 48 h with 10% human serum had significantly higher cellular triglyceride (22%, P<0.05) and cholesterol levels (19%, P<0.01), higher medium apoC-I and apoE levels (2.6- and 2.9-fold, respectively), but similar levels of apoC-I and apoE mRNA, compared to cells incubated with 10% human lipoprotein-deficient serum (LPDS). Serum containing only HDL, or containing HDL with LDL, also increased cellular lipids and increased secreted apoC-I and apoE levels without altering apoC-I and apoE mRNA levels. Incubation of cells with Intralipid triglyceride (625 microM), increased cellular triglyceride (2.8-fold, P<0.001), decreased cellular cholesterol (32%, P<0.01), decreased cellular and medium apoC-I (24 and 26%, P<0.01) and had no effect on apoC-I mRNA levels. Additional experiments in which cells were loaded with cholesterol (incubation with 10 microg/ml cholesterol plus 1 microg/ml 25-hydroxycholesterol) or depleted of cholesterol (statin treatment) confirmed that secretion of apoC-I by HepG2 cells was dependent on cellular cholesterol levels and independent of changes in apoC-I mRNA levels. These results demonstrate that cellular cholesterol rather than triglyceride levels play a role in controlling apoC-I production by HepG2 cells and that this regulation occurs at a post-transcriptional level.
Atherosclerosis 2005 Feb
PMID:Post-transcriptional regulation of apoC-I synthesis and secretion in human HepG2 cells. 1569 32

The basis for accelerated atherosclerosis in diabetes is unclear. Diabetes is associated with loss of heparan sulfate (HS) from the liver, which may impede lipoprotein clearance and thereby worsen atherosclerosis. To study hepatic HS loss in diabetes, we examined regulation of HS N-deacetylase/N-sulfotransferase-1 (NDST), a key enzyme in hepatic HS biosynthesis. Hepatic NDST mRNA, protein, and enzymatic activity were suppressed by >50% 2 weeks after induction of type 1 diabetes in rats. Treatment of diabetic rats with enalapril, an ACE inhibitor, had no effect on hyperglycemia or hepatic NDST mRNA levels, yet increased hepatic NDST protein and enzymatic activity. Similar results were obtained in diabetic animals treated with losartan, which blocks the type 1 receptor for angiotensin II (AngII). Consistent with these findings, diabetic livers exhibited increased ACE expression, and addition of AngII to cultured hepatoma cells reduced NDST activity and protein. We conclude that diabetes substantially suppresses hepatic NDST mRNA, protein, and enzymatic activity. AngII contributes to suppression of NDST protein and enzymatic activity, whereas mRNA suppression occurs independently. Suppression of hepatic NDST may contribute to diabetic dyslipidemia, and stimulation of NDST activity by AngII inhibitors may provide cardiovascular protection.
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PMID:Loss of heparan N-sulfotransferase in diabetic liver: role of angiotensin II. 1579 51

Hepatic steatosis is the hallmark of nonalcoholic fatty liver disease (NAFLD), which is the consequence of multiple metabolic derangements among which insulin resistance plays a pivotal role. Steatosis is, also, a feature of hepatitis C virus (HCV) infection. However, in chronic hepatitis C, the prevalence of steatosis is 2.5-fold more elevated than that expected by a chance concurrence with NAFLD, suggesting that HCV may be implied in the development of steatosis. As observed in NAFLD, in patients infected with HCV genotype 1 steatosis is associated with an increased body mass index. On the other hand, in patients infected with genotype 3 the extent of steatosis strictly correlates with the viral load indicating that steatosis is mainly "virus-related". Regardless of the "metabolic" or "viral" etiology, hepatic steatosis in HCV contributes to the progression of liver fibrosis, to the development of hepatocellular carcinoma and to an impaired response to interferon treatment. Features such as obesity, insulin resistance and type 2 diabetes mellitus are shared by NAFLD and HCV-associated steatosis. In addition, HCV infection, directly or through steatosis, favors the development of type 2 diabetes mellitus. Hyperlipidemia is an independent predictor of the development of NAFLD, but not of HCV-associated steatosis. Arterial hypertension is common in nonalcoholic steatohepatitis patients, and HCV infection has recently been acknowledged as an independent risk factor for atherosclerosis. The role of iron in the progression of both NAFLD and HCV-associated steatosis remains controversial while lipoperoxidation and oxidative stress are pathogenic mechanisms shared by both. Some metabolic risk factors may be shared by both HCV-associated steatosis and NAFLD although the disease progression and pathophysiological background may be different. Preliminary data suggest that the therapeutic options for NAFLD may also be useful to improve HCV-associated steatosis.
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PMID:[Hepatitis C virus-associated and metabolic steatosis. Different or overlapping diseases?]. 1585 90

Fibrinogen is a plasma protein synthesized by the liver. It is composed of three chains (alpha, beta, gamma). In addition to its main function as a coagulation factor, this acute phase protein is also a risk marker for atherosclerosis. Retinoic acid receptor-related orphan receptor (ROR)alpha is a nuclear receptor modulating physiopathological processes such as cerebellar ataxia, inflammation, atherosclerosis, and angiogenesis. In this study, we identified RORalpha as a regulator of fibrinogen-beta gene expression in human hepatoma cells and in mouse liver. A putative RORalpha response element (RORE) was identified in the human fibrinogen-beta promoter. EMSA showed that RORalpha binds specifically to this RORE, and cotransfection experiments in HepG2 hepatoma cells indicated that this RORE confers RORalpha-dependent transcriptional activation to both the human fibrinogen-beta and the thymidine kinase promoters. Stable transfection experiments in HepG2 and Hep3B hepatoma cells demonstrated that overexpression of RORalpha specifically increases endogenous fibrinogen-beta mRNA levels. Chromatin immunoprecipitation experiments revealed that the fibrinogen-beta RORE is occupied by RORalpha in HepG2 cells. Thus, the human fibrinogen-beta gene is a direct target for RORalpha. Furthermore, fibrinogen-beta mRNA levels in liver and plasma fibrinogen concentrations are specifically decreased in staggerer mice, which are homozygous for a deletion invalidating the Rora gene. Taken together, these data add further evidence for an important role of RORalpha in the control of liver gene expression with potential pathophysiological consequences on coagulation and cardiovascular risk.
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PMID:The gene encoding fibrinogen-beta is a target for retinoic acid receptor-related orphan receptor alpha. 1594 50

C-reactive protein (CRP) is made in liver and its serum concentration increases in inflammation. Measurement of serum CRP is recommended for use as an indicator of inflammation and predictor of atherosclerosis. Cholesterol-lowering drugs statins also lower CRP. To evaluate statin-mediated CRP reduction and to reassess clinical usefulness of CRP, we investigated regulation of CRP gene expression. Here, we show that pravastatin and simvastatin prevent the induction of CRP expression in human hepatoma Hep3B cells exposed to proinflammatory cytokines IL-6 and IL-1beta The nitric oxide (NO) donor, sodium nitroprusside, also prevented the induction of CRP expression while the CRP inducers IL-6 and IL-1beta were present with the cells. The effect of NO on CRP expression was at the level of transcription. These findings suggest that the decrease in CRP level in vivo after statin-treatment does not necessarily reflect absence of inflammation, and that NO-releasing drugs have the potential to reduce serum CRP levels. Thus, the measurement of serum CRP levels alone in individuals on statin/NO-therapy is not as useful as was imagined.
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PMID:Statins and nitric oxide reduce C-reactive protein production while inflammatory conditions persist. 1605 96


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