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)

Plasma and 24-hour urinary cyclic AMP and cyclic GMP levels were determined by saturation analysis in specimens from normal subjects and from 101 patients with tumours of the gastrointestinal tract, breast, lung, bladder or prostate, or with cirrhosis of the liver. Relative to 46 control subjects, plasma cyclic GMP concentrations were significantly elevated in seven patients with gastric tumours, 20 patients with cancer of the breast, six patients with lung cancer, and 12 patients with cirrhosis of the liver. Urinary cyclic GMP/creatinine ratios were significantly increased in cirrhotic patients and in the lung and oesophageal cancer groups. In no cancer group were increases in plasma or urine cyclic GMP levels sufficiently consistent to be of value in the diagnosis of human malignant disease. Changes in extracellular fluid cyclic nucleotide levels in the cirrhotic group were very similar to those that have been reported for primary hepatoma patients.
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PMID:Plasma and urine cyclic nucleotide levels in malignant disease and cirrhosis of the liver. 23 Feb 5

When supernatants of thymic epithelial cell cultures (STEC) or thymosin fraction 5 were incubated with washed platelets (37 degrees C for 30 min), the levels of platelet guanosine 3',5'-cyclic monophosphate (cyclic GMP) were increased in a dose-dependent manner. In contrast the supernatants from Chang, HeLa, or HCC-M cell cultures did not significantly affect the levels of intracellular cyclic GMP. The increment of intracellular cyclic GMP levels following treatment with STEC increased with longer incubation times until a plateau was reached at 30 min. This activity of STEC was found in fractions with a molecular weight below 10,000 daltons. Contents of guanine and guanosine in STEC were lower than those observed in other culture supernatants. STEC did not affect guanylate cyclase activity in platelets, but significantly inhibited cyclic GMP phosphodiesterase activities in platelet soluble and membrane fractions. Thymosin fraction 5 inhibited the phosphodiesterase activity of the soluble but not the membrane fraction.
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PMID:In vitro effect of thymic epithelial culture supernate on cyclic GMP levels in rabbit platelets. 197 Jun 75

Post-transcriptional regulation of the asialoglyco-protein receptor (ASGR) in the HepG2 cell line can be mediated by the presence of biotin in the culture medium. To determine if the induction by biotin of intracellular cGMP affects ASGR expression, HepG2 were grown in biotin-depleted medium with the cell-permeant 8-bromo-cGMP (8-Br-cGMP). Both cell-surface and total ASGR binding of iodinated asialoorosomucoid (125I-ASOR) was increased from 30 to 95% of control levels by the addition of increasing concentrations of 8-Br-cGMP. The rate of ASGR-mediated endocytosis of 125I-ASOR also increased with increasing concentrations of 8-Br-cGMP. Estimates of the steady state levels of ASGR by transblot analysis utilizing both antisera to affinity-purified ASGR and to isoform-specific antibodies prepared against synthetic peptides confirmed that the increase in 125I-ASOR binding was due to an increase in ASGR expression. Metabolic labeling of biotin-deprived HepG2 with [35S] cysteine and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of immunoprecipitants revealed an increase of radiolabeled ASGR within 30 min of the addition of 8-Br-cGMP. Induction of cGMP by atrial natriuretic factor also increased the metabolic labeling of ASGR. ASGR expression in a second hepatocellular carcinoma cell line, HuH-7, responded in a similar fashion to the addition of 8-Br-cGMP. In contrast to 8-Br-cGMP, exposure to 8-bromo-cAMP results in a reduction of ASGR expression even in the presence of biotin-containing medium. The antagonistic roles of cGMP and cAMP suggest a balance between cyclic nucleotides is required for the maintenance of differentiated functions by the hepatocyte.
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PMID:Second messenger modulation of the asialoglycoprotein receptor. 215 66

A new polysaccharide compound (ACPS-R) has recently been isolated from the root of Actinidia Chinensis Planch. When given intraperitoneally to the transplantable tumor bearing mice at dose of 75-125 mg/kg, the tumor inhibition rate was more than 88.8% in Ehrilich ascitic cancer (EAC) or ascitic form of hepatoma (HepA) and more than 49.6% in solid hepatoma (HepS). The treatment effect of ACPS-R on EAC at dose of 15 mg/kg and 22.5 mg/kg, respectively. ACPS-R could also prolong the life of EAC-or P388-bearing mice, and increase the percentage of EAC-free mice. In addition, when ACPS-R was used in combination with 5-Fu, the antitumor effect was enhanced as compared with 5-Fu alone. A marked increase in cAMP levels and cAMP/cGMP ratio of spleen of EAC-bearing mice were observed after treatment of ACPS-R. The increase of both parameters nearly reached the normal levels of healthy mice. The increases of cAMP, cAMP/cGMP and tumor remission had statistical significance. It showed an intermediate inhibitory effect of ACPS-R on DNA synthesis by incorporating 3H-TdR into EAC cells. The results indicated that ACPS-R acts as a new antitumor polysaccharide, and the treatment effect of Actinidia root in folk medicine is probably related to ACPS-R.
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PMID:[Antitumor effect of actinidia chinensis polysaccharide on murine tumor]. 285 56

Homogeneous catalytic subunit from the cAMP-dependent protein kinase, when derivatized with a fluorophore, was used as a cytochemical probe to locate intracellular sites of the protein kinase regulatory subunit. After conjugation, the fluoresceinated catalytic subunit (F:C), derivatized to a stoichiometry of approximately 1 mol/mol, retained near full activity as judged by specific activity and by titration against either regulatory subunit or Inhibitor Protein of the protein kinase. With this molecular probe the dissociated regulatory subunit was localized by direct cytochemistry in Reuber H-35 hepatoma cells that had been exposed, while intact, for 0-120 min to 10(-4) M 8-Br-cAMP. After stimulation, cultures were fixed and washed and then incubated for 16 h with F:C. Following 8-Br-cAMP stimulation, extensive binding of the probe to both cytoplasmic and nucleolar sites was observed. This binding was diminished but not eliminated when 50 microM cAMP was present during the incubation of the fixed cells with F:C that was eliminated by a 40-fold molar excess of underivatized catalytic subunit but not by heat-denatured catalytic subunit, and was not reduced by a 20-fold molar excess of cGMP-dependent protein kinase, examined plus or minus cGMP. Collectively, the results allow the conclusion that the F:C probe binds free regulatory subunit. The time course of its change with 8-Br-cAMP (measured as the difference between binding in the presence or absence of cAMP during the postfixation treatment) mirrors that previously reported for changes in the catalytic subunit in these cells, also identified cytochemically (Byus, C. V., and Fletcher, W.H. (1982) J. Cell Biol. 93, 727-734). The binding of the F:C probe, detected when cAMP is present during postfixation treatment, may possibly represent binding to free Inhibitor Protein of the cAMP-dependent protein kinase. If so, it was at a level of approximately 20% of the maximal level of detectable regulatory subunit, and it also showed cytosolic and nucleolar localization.
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PMID:Cytochemical identification of the regulatory subunit of the cAMP-dependent protein kinase by use of fluorescently labeled catalytic subunit. Examination of protein kinase dissociation in hepatoma cells responding to 8-Br-cAMP stimulation. 300 8

Plasma-membrane-bound kinases of AS-30D ascites from transplantable rat hepatocarcinoma were shown to extensively catalyze the phosphorylation of plasma membrane proteins and membrane lipids, using [gamma-32P]ATP or [gamma-32P]GTP as a phosphate donor. In contrast, plasma membranes from normal adult rat liver or fast-growing regenerating liver (24 h after partial hepatectomy) produce significantly less activity for protein phosphorylation and little phosphorylation of the lipids. However, neonatal (24 h old) rat liver plasma membrane preparations show levels of phosphorylation of proteins and lipids intermediate between those in the tumor cell line and normal adult plasma membrane preparations. Phosphatidic acid was identified as one of the 32P-labelled lipids in the tumor plasma membrane chloroform-methanol (2:1, v/v) extract. Phosphorylation of protein was not affected by cAMP or cGMP. However, calcium ion (in the presence or absence of calmodulin) significantly modifies the 32P labelling of a series of proteins in normal tissue but has little effect with the neoplastic preparations. Some plasma membrane proteins were capable of nucleotide binding, instead or in addition to being phosphorylated. Finally, the presence of membrane-bound phosphoprotein phosphatase(s) was also demonstrated in all the preparations examined by means of chase experiments with nonlabelled ATP or GTP, and (or) by the use of the phosphoprotein phosphatase inhibitor, orthovanadate.
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PMID:Endogenous hyperphosphorylation in plasma membrane from an ascites hepatocarcinoma cell line. 337 Jan 39

Theophylline, a cyclic nucleotide phosphodiesterase inhibitor, increases the rate of tyrosine aminotransferase (TAT) degradation in rat hepatoma tissue culture (HTC) cells. Theophylline (0.1-10 mM) causes a two- to five-fold increase in intracellular cAMP concentration but a 30-60% decrease in cGMP concentration. The decrease in cGMP occurs at doses of theophylline which increase the rate of TAT degradation. When cGMP levels are increased by incubating the cells with either Mn2+, an activator of guanylate cyclase, or 8-bromo-cGMP, an analog of cGMP, the effect of theophylline is reversed and the rate of TAT degradation is slowed. Thus, the rate of TAT degradation is inversely related to the concentration of cGMP in HTC cells. This raises the possibility that a cGMP-dependent event is involved in the control of specific protein degradation.
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PMID:The involvement of cyclic GMP in tyrosine aminotransferase degradation in rat hepatoma tissue culture cells. 611 61

Tyrosine aminotransferase activity increased during conversion of serum depleted quiescent Reuber H35 rat hepatoma cells into the proliferative state. Increased activity coincides with the actual increase of cells into S phase. The rate of tyrosine aminotransferase synthesis along the cell cycle was studied. The rate of enzyme synthesis fluctuated through the cell cycle but could not explain the increase of specific activity. Apparently enzyme activity is predominantly regulated by a post-translational event. Intracellular levels of cyclic AMP and cyclic GMP were measured at various times of G1 and S phases. In the early part of the cell cycle tyrosine aminotransferase decreased while intracellular levels of cyclic AMP increased. At later stages cyclic AMP rises concurrently with increased rates of enzyme synthesis. Induction of tyrosine aminotransferase by N6,O2'-dibutyryladenosine 3', 5'-monophosphate (Bt2cAMP) was studied. Inducibility by Bt2cAMP fluctuated through the cell cycle. Alternation of positive and negative control of tyrosine aminotransferase synthesis was observed. In early serum induced cells, Bt2cAMP increased enzyme activity without any increased rate of enzyme synthesis, on the contrary, a decreased rate of synthesis was observed. The data support the view that alternation of positive and negative control of tyrosine aminotransferase synthesis and temporary post-translational control of enzyme activity determine the enzyme level during the transition of quiescent hepatoma cells into proliferation.
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PMID:Variations in some molecular events during the early phases of the Reuber H35 cell cycle. IV-regulation of tyrosine aminotransferase. 614 73

The studies described in this paper demonstrate rather conclusively the efficacy of the study of the regulation of gene expression in primary cultures of adult rat hepatocytes. The utilization of these cells in completely defined medium allows one to determine the exact environmental conditions for the regulation of the expression of specific genes. In the studies described in this work, we have demonstrated that the regulation of glucokinase involved three hormones, insulin, corticosteroids, and T3. In contrast, the regulation of an enzyme involved primarily in fatty acid metabolism, ATP-citrate lyase, required only insulin and T3 for its full expression. Cyclic GMP appeared to be involved in the regulation of glucokinase, but not ATP-citrate lyase, a fact that would be extremely difficult to demonstrate clearly in vivo. The regulation of the gluconeogenic enzyme, ornithine aminotransferase, in vitro involved only a single hormone, glucagon, the inhibition of induction by corticoid steroids demonstrable in vivo being absent in cell culture. However, the repressive effect of glucose on the induction of this enzyme was quite comparable to that seen in vivo and was not mediated through cyclic AMP or insulin, based on findings in cell culture. Thus, the requirements for and the mechanisms involved in enzyme induction and repression by hormones and glucose may be much more easily studied in primary cultures of rat hepatocytes than in vivo, or even in hepatoma cell lines, where relatively few genes are expressed as compared with adult liver. In addition to the regulation of enzyme levels, the characteristics of protein secretion may be investigated in primary cultures of rat hepatocytes and compared with the biochemical and physiological parameters in the whole organism. This was exemplified by the study of the synthesis and secretion of alpha 2u-globulin that was secreted into the culture medium in both glycosylated and nonglycosylated forms but was maintained in the circulation in vivo, principally as the glycosylated form. Furthermore, the function of glycosylation in this particular instance may be deduced from a combination of the in vivo and in vitro approaches. The advantages of the use of primary hepatocyte cultures for the study of the regulation of gene expression in mammalian tissue has only recently been explored. Future investigations of the regulation of a variety of enzymes in these cultures as well as a study of the regulation of the synthesis of their messenger RNA are now possible and should provide an exciting system in which to understand at a molecular level the regulation of the expression of a number of genes.
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PMID:Regulation of gene expression in primary cultures of adult rat hepatocytes on collagen gels. 616 26

To investigate the prediction that urinary cGMP (UcGMP) and cAMP (UcAMP) excretion is altered in a manner consistent with unregulated cell growth in hepatocellular carcinoma (HCC), we studied 31 patients with this disease, 25 without apparent disease, 16 with various hepatic diseases, and 16 with nonhepatic neoplasms. Results were expressed as UcGMP excretion per 100 ml glomerular filtration because reduced creatinine excretion in patients with muscle wasting or renal dysfunction may spuriously elevate UcGMP. UcGMP excretion was elevated in 80% of patients with HCC, 75% of patients with hepatic disease and 68% of patients with other neoplasms. Mean values for UcAMP excretion did not differ significantly from normal values. Plasma and ascitic fluid cGMP concentrations in HCC and hepatic diseases were raised. These results support the hypothesis of a shift in cyclic nucleotide metabolism toward cGMP in malignant diseases. However, UcGMP measurement does not detect progression of cirrhosis to HCC.
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PMID:Cyclic nucleotides in biological fluids in hepatocellular carcinoma. 625 69


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