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 variations of the main plasma inhibitors of coagulation were prospectively studied in 33 cirrhotic patients, of which 9 presented with hepatocellular carcinoma, 5 of those associated with portal vein thrombosis. The mean prothrombin index was 49 +/- 16 percent. All plasma values of inhibitors were diminished, but to varied degrees: the mean values were: protein C (PC): 33 +/- 15 percent, antithrombin III (AT III): 50 +/- 23 percent, total protein S (PST): 67 +/- 20 percent. The more severe the cirrhosis, the more decreased were the values of antithrombin II and protein C. According to Child classes A, B, and C, antithrombin III plasma values were 64 +/- 20, 50 +/- 21 and 26 +/- 11 percent and protein C values were 43 +/- 16, 32 +/- 8 and 19 +/- 9 percent, respectively. We were able to define expected plasma values of the plasma inhibitors as a function of coagulation factors during cirrhosis; AT III (percent) = 1.16 x factor II (percent) - 7.85; PC (percent) = 0.49 x AT III (percent) + 8.96; PC (percent) = 0.55 x factor II (percent) + 5.55; PST (percent) = 0.76 x factor II (percent) + 28.74. However those equations cannot be extrapolated to patients presenting with cirrhosis complicated with portal thrombosis.
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PMID:[Changes in levels of blood coagulation inhibitors in cirrhosis. Prospective study in 33 patients]. 131 44

A complementary DNA (cDNA) for rat hepatic aryl sulfotransferase IV (AST IV) was isolated, characterized, and used as a hybridization probe to evaluate the molecular basis for the differential expression of AST IV during 2-acetylaminofluorine (2AAF)-induced hepatocarcinogensis. The AST IV cDNA clone was obtained by immunochemical screening of a male Sprague-Dawley rat liver cDNA library. The AST IV cDNA was found to be 1.3 kilobases long and to encode a fusion protein which was reactive with an antibody to AST IV and enzymatically able to generate the sulfuric acid ester of N-hydroxy-2AAF. Sequence analysis of the AST IV cDNA showed it to be 1127 residues in length and to have essentially complete homology with PST-I cDNA, a previously reported (S. Ozawa, et al., Nucleic Acids Res., 18: 4001, 1990), 1028-base cDNA for an uncharacterized rat liver aryl sulfotransferase. Comparison of the PST-I/AST IV cDNA-deduced amino acid sequence with data from a partial (51%) amino acid sequence analysis of purified AST IV showed complete amino acid homology, confirming the identity of the cDNA and establishing that AST IV was an N-blocked, 291-amino acid protein with a molecular mass of 33,909 daltons. The AST IV cDNA sequence differed from the PST-I cDNA in two principal ways: the 5' end lacked 18 coding bases, and the 3' end contained a 190-base extention in the untranslated region, including a consensus sequence for signalling polyadenylation. Studies of AST IV gene transcript levels showed that the livers of rats fed 2AAF for 3 wk (early stage hepatocarcinogenesis) and hyperplastic nodules from the livers of rats fed 2AAF for 19 wk (intermediate stage hepatocarcinogenesis) displayed transcript levels similar to those of livers from normal rats. This contrasted with the 60 to 70% lower than normal capacity of the mRNA fractions to express AST IV observed during in vitro translation. These results indicated that modulation of AST IV expression at early and intermediate stages of hepatocarcinogenesis involved regulatory mechanisms at the translational level. In contrast, mRNA fractions isolated from some 2AAF-induced liver tumors or from known chemical carcinogen-derived rat hepatoma cell lines showed losses of both AST IV transcript level and in vitro translation capacity, suggesting that regulation at the transcriptional level may become important at late stages of 2AAF-induced hepatocarcinogenesis. These results indicated that the molecular mechanisms for the 2AAF-mediated down regulation of AST IV expression during 2AAF-induced hepatocarcinogenesis involved alterations in regulation at both translational and transcriptional levels.
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PMID:Characterization of a complementary DNA for rat liver aryl sulfotransferase IV and use in evaluating the hepatic gene transcript levels of rats at various stages of 2-acetylaminofluorene-induced hepatocarcinogenesis. 151 41

The secondary nitroalkanes, 2-nitropropane, 2-nitrobutane, 3-nitropentane, 2-nitroheptane, nitrocyclopentane and nitrocyclohexane, as well as the primary nitroalkanes, 1-nitropropane, 1-nitrobutane, 1-nitropentane and 1-nitroheptane, were examined for their ability to induce DNA repair in rat hepatocytes and to serve as substrates for activation by partially purified rat liver aryl sulfotransferase in vitro. All of the secondary, but none of the primary nitroalkanes examined, induced significant DNA repair in rat hepatocytes. Also, the nitronates of all of the secondary nitroalkanes, but none of the primary nitroalkanes, served as substrates for the aryl sulfotransferase-catalysed production of 8-aminoguanosine and 8-oxoguanosine from guanosine in vitro. In a carcinogenicity assay using male F344 rats, the secondary nitroalkanes, 2-nitrobutane and 3-nitropentane, produced a highly significant incidence of hepatocarcinoma with metastases to the lungs, whereas the primary nitroalkane, 1-nitrobutane, was not carcinogenic. While a low incidence of hepatocarcinoma was also produced by cyclopentanone oxime, the results were not statistically significant. Since the secondary nitroalkane, 2-nitropropane, in contrast to the primary nitroalkane, 1-nitropropane, was also previously shown to be hepatocarcinogenic in rats, it is probable that secondary nitroalkanes constitute a hitherto unrecognized class of chemical carcinogens.
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PMID:Secondary nitroalkanes: induction of DNA repair in rat hepatocytes, activation by aryl sulfotransferase and hepatocarcinogenicity of 2-nitrobutane and 3-nitropentane in male F344 rats. 776 4

A 1,179 bp and a 1,424 bp full-length aryl sulfotransferase cDNAs were isolated from a human brain cDNA library. Their coding domains are 93% identical, each encoding a cytosolic protein of 295 amino acids. Their deduced amino acid sequences of these cDNAs are also 93% identical. The 1179 bp brain cDNA has an identical coding domain to a previously reported human liver aryl sulfotransferase cDNA but it has a different 5' noncoding sequence. Northern blot analysis using a probe specific for the 1,424 bp cDNA identified a 1500 bp band in mRNA of human liver, colon, kidney and lung. In a human hepatocellular carcinoma the same band plus an extra larger band was also recognised. An intron of the gene encoding the 1424 bp cDNA was also identified.
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PMID:Identification of two human brain aryl sulfotransferase cDNAs. 836 92

2-Nitropropane (2-NP) is a well-known genotoxin and carcinogen in rat liver. Several metabolic pathways, particularly cytochrome P450-, peroxidase- and sulfotransferase-dependent ones, have been suggested to lead to the formation of DNA-reactive species from 2-NP. Because rat liver cells express most types of xenobiotic-metabolizing enzymes, the role of specific pathways in the metabolic activation of 2-NP is difficult to assess in these cells. We have therefore investigated the genotoxicity of 2-NP and its anionic form, propane 2-nitronate (P2N), in cultured ovine seminal vesicle (OSV) cells. OSV cells lack cytochrome P450-dependent monooxygenase activity, but express prostaglandin-H-synthase (PHS) and, as we found out, phenol sulfotransferase. The induction of DNA repair synthesis and specific DNA modifications served as indicators for the genotoxicity of 2-NP and P2N. Both forms strongly induced repair, P2N being more active than 2-NP. The secondary nitroalkanes nitrocyclopentane and nitrocyclohexane also induced repair, whereas 1-nitropropane and the reduction product of 2-NP, acetone oxime, did not. P2N also elicited the formation of the characteristic DNA modifications 'DX1' and 8-aminodeoxyguanosine and increased the level of 8-oxodeoxyguanosine residues in the DNA. Pretreatment of OSV cells with indomethacin, an inhibitor of PHS, affected neither the induction of repair nor the formation of the DNA modifications, and P2N was not a reducing substrate for the PHS-peroxidase activity. In contrast, the sulfotransferase inhibitor pentachlorophenol strongly reduced genotoxicity. The results show that cytochrome P450-dependent monooxygenases are not required for the metabolic conversion of secondary nitroalkanes or their nitronates into DNA-damaging products, nor is PHS involved in the metabolic activation. Instead, the data corroborate an essential role of sulfotransferase(s) in the genotoxicity and carcinogenicity of secondary nitroalkanes. Moreover, it is demonstrated for the first time that these compounds can be genotoxic in cells other than hepatocytes or hepatoma cells. This implies that in species other than the rat, organs other than the liver can be targets for the genotoxicity, and possibly carcinogenicity, of secondary nitroalkanes.
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PMID:Sulfotransferase-mediated genotoxicity of propane 2-nitronate in cultured ovine seminal vesicle cells. 960 60

Upon two-dimensional thin-layer separation, the sulfated L-3, 4-dihydroxyphenylalanine (L-DopaS) generated enzymatically was found to co-migrate with only one of the two ninhydrin-stained spots corresponding to the two sulfated forms (3-O-sulfate and 4-O-sulfate) of synthetic L-DopaS. To clarify precisely the identity of the enzymatically generated L-DopaS, the two sulfated forms of synthetic L-DopaS were separated and purified using high performance liquid chromatography. Purified L-Dopa 3-O-sulfate and L-Dopa 4-O-sulfate were identified by 1H-nuclear magnetic resonance (NMR) spectrometry and used as standards in the analysis of the L-DopaS generated during metabolic labeling of HepG2 human hepatoma cells or enzymatic assay using recombinant human monoamine (M)-form phenol sulfotransferase. The results obtained demonstrated unequivocally the generation of L-Dopa 3-O-sulfate, indicating the specificity of the M-form phenol sulfotransferase being for the meta-hydroxyl group of L-Dopa.
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PMID:Substrate specificity of human monoamine (M)-form phenol sulfotransferase: preparation and analysis of Dopa 3-O-sulfate and Dopa 4-O-sulfate. 975 14

The classifications of hepatocellular carcinoma (HCC) currently used are based on prognostic factors obtained from studies performed years ago when most tumors were diagnosed at advanced stages and the survival rates were substantially poor. Recent investigations have reviewed the survival of early tumors properly selected to receive radical therapies and the natural outcome of nonsurgical HCC patients. These data enable a new staging system to be proposed, the Barcelona Clinic Liver Cancer (BCLC) staging classification, that comprises four stages that select the best candidates for the best therapies currently available. Early stage (A) includes patients with asymptomatic early tumors suitable for radical therapies--resection, transplantation or percutaneous treatments. Intermediate stage (B) comprises patients with asymptomatic multinodular HCC. Advanced stage (C) includes patients with symptomatic tumors and/or an invasive tumoral pattern (vascular invasion/extrahepatic spread). Stage B and C patients may receive palliative treatments/new agents in the setting of phase II investigations or randomized controlled trials. End-stage disease (D) contain patients with extremely grim prognosis (Okuda stage III or PST 3-4) that should merely receive symptomatic treatment.
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PMID:Prognosis of hepatocellular carcinoma: the BCLC staging classification. 1051 12

To investigate whether sulfation, a major Phase II detoxification pathway in vivo, can be employed as a means for the inactivation/disposal of environmental estrogens, recombinant human cytosolic sulfotransferases were prepared and tested for enzymatic activities with bisphenol A, diethylstilbestrol, 4-octylphenol, p-nonylphenol, and 17alpha-ethynylestradiol as substrates. Of the seven recombinant enzymes examined, only SULT1C sulfotransferase #1 showed no activities toward the environmental estrogens tested. Among the other six sulfotransferases, the simple phenol (P)-form phenol sulfotransferase and estrogen sulfotransferase appeared to be considerably more active toward environmental estrogens than the other four sulfotransferases. Metabolic labeling experiments revealed the sulfation of environmental estrogens and the release of their sulfated derivatives by HepG2 human hepatoma cells. Moreover, sulfated environmental estrogens appeared to be incapable of penetrating through the HepG2 cell membrane.
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PMID:Sulfation of environmental estrogen-like chemicals by human cytosolic sulfotransferases. 1062 78

Since sulfation is the main metabolic pathway of troglitazone, accounting for about 70% of the metabolites detected in human plasma, we have aimed to identify human cytosolic sulfotransferases catalyzing the sulfation of troglitazone and to examine a possible role of the sulfation in the cytotoxicity observed in cell lines of human origin (HepG2 and Hep3B). Experiments using the recombinant sulfotransferases and human liver cytosols indicated that phenol sulfotransferase (ST1A3) and estrogen sulfotransferase (ST1E4) were the sulfotransferases most active toward troglitazone. Immunoblot analyses indicated that hepatic content of ST1A3 is about 13 times higher than that of ST1E4, suggesting that ST1A3 is mainly responsible for the sulfation of troglitazone in the liver. Lactate dehydrogenase (LDH) leakage was elicited by troglitazone in a concentration-dependent manner in the hepatoma cells. The troglitazone metabolites (the sulfate, glucuronide, and quinone forms) caused negligible LDH leakage. These findings suggest that accumulation of unmetabolized troglitazone causes the cytotoxicity in the hepatoma cells and may be responsible for toxicity in human liver.
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PMID:Phenol sulfotransferase, ST1A3, as the main enzyme catalyzing sulfation of troglitazone in human liver. 1212 14

Phenolic acids are antioxidant phenolic compounds, widespread in plant foods, which contribute significant biological and pharmacological properties; some have demonstrated a remarkable ability to alter sulfate conjugation. However, the modulation mechanisms of antioxidant phenolic acids on phenolsulfotransferase activity have not yet been described. In the present study, the human hepatoma cell line, HepG2, was used as a model to investigate the effect of antioxidant phenolic acids on enzymatic activity and expression of one of the major phase II sulfate conjugation enzymes, P-form phenolsulfotransferase (PST-P). The results showed that gallic acid, gentisic acid, p-hydroxybenzoic acid, and p-coumaric acid increased PST-P activity, in a dose-dependent manner. A maximum of 4- and 5-fold induction of PST-P activity was observed for both gallic acid and gentisic acid; however, they showed an adverse effect on cell growth at higher concentrations. A 2- or 2.5-fold increase of PST-P activity was found with either p-coumaric or p-hydroxybenzoic acid treatment, whereas no significant effect was found for ferulic acid treatment. PST-P induction, by gallic acid, was further confirmed, using reverse transcription PCR and Western blotting techniques to measure mRNA expression and protein translation. A significant correlation (r = 0.74, p < 0.01) between the expressions of PST-P mRNA and the corresponding PST-P activity was observed. Thus, gallic acid increased PST-P protein expression in HepG2 cells, in a dose- and time-dependent manner. The results demonstrated that certain antioxidant phenolic acids could induce PST-P activity in HepG2 cells, by promoting PST-P mRNA and protein expression, suggesting a novel mechanism by which phenolic acids may be implicated in phase II sulfate conjugation.
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PMID:Induction of phenolsulfotransferase expression by phenolic acids in human hepatoma HepG2 cells. 1594 13


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