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)

Phosphoprotein phosphatase which dephosphorylates 32P-labeled nucleolar protein substrates was found in nucleoli of Novikoff hepatoma ascites cells and normal rat liver. The activity was extracted in high yield from nucleoli with 0.01 M Bis/Tris (pH 7.0). Low ionic strength was also required for activity: the activity was only 50% of maximum in 0.075 M NaCl. Activity was affected differently by various divalent cations: MgCl2 had little effect: CaCl2, MnCl2 and CoCl2 above 4 mM inhibited the activity 30--60%; ZnCl2 above 2 mM completely destroyed the activity. EDTA had no effect, indicating that divalent cations are probably not required. The enzyme activity was enhanced 20% by 5--8 mM dithiothreitol and was inhibited 60% by 7--10 mM N-ethylmaleimide indicating a requirement for free sulfhydryl groups. The Km of the extracted enzyme for 32P-labeled nucleolar protein was 0.6 mg/ml. The phosphatase was capable of dephosporylating the major phosphorylated nucleolar proteins C23-24 and B23-24 and also histone H1. The enzyme was purified more than 200-fold on hydroxyapatite followed by DEAE-Sephadex, which resolved the activity into three major components. The activity of enzyme extracted from Novikoff hepatoma nucleoli was approximately 2.5 times greater than from normal liver nucleoli.
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PMID:Nucleolar phosphoprotein phosphatase from Novikoff hepatoma and rat liver: characterization and partial purification. 21 Aug 25

We developed a sensitive fluorometric assay to study in vitro fusion between early endosomes isolated from the human hepatoma, Hep G2. Biochemical characterization of this assay showed that fusion between endosomal vesicles was dependent on physiologic temperature, cytosol, and ATP. Fusion was inhibited by pretreatment of vesicles and cytosol with either 1 mM N-ethylmaleimide or 20 microM GTP gamma S. Neither 3 mM ethylene glycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid nor 1 mM CaCl2 significantly affected fusion. In addition, ATP gamma S neither inhibited fusion at 50 microM nor supported fusion at 5 mM. To further our understanding of the factors regulating fusion, inhibitors of endoprotease activity and phosphotyrosine phosphatase activity were assayed for their effect on fusion. The dipeptide inhibitor of endoprotease activity, Cbz-gly-phe-amide, inhibited fusion 70% at 3 mM whereas a dipeptide analogue, Cbz-gly-gly-amide, was without effect. Furthermore, orthovanadate, an inhibitor of phosphotyrosine phosphatase activity, stimulated fusion twofold at 0.5 mM. These results suggest that both tyrosine dephosphorylation and endoprotease activity contribute to the regulation of endosome fusion.
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PMID:Reconstitution of human hepatoma endosome-endosome fusion in vitro: potential roles for an endoprotease and a phosphoprotein phosphatase. 165 9

The DNA endonuclease (Aendo) and DNA topoisomerase (Atopo) activities in liver nucleus extracts of normal rats, in DENA-induced hepatomas and in liver tissues around tumours were investigated. The profile of nuclear endonucleases measured in the presence of 2 mM CaCl2 + 5 mM MgCl2, or 5 mM MnCl2, or 5 mM MgCl2, or 2 mM CaCl2 (pH 7.4), or I mM EDTA (pH 5.0) was different in normal and tumour tissues. Mn2+-dependent endonuclease was the main endonuclease in the tumour tissue, whereas Ca2+, Mg2+-dependent endonuclease was the main one in the normal liver and in the tissue around the tumour. An increase in the Mn2+-dependent endonuclease activity correlated with a decrease in the hepatoma differentiation level. Atopo of types I and II increased in the tissue around the tumour. Aendo and Atopo of cellular nuclei decreased in animals given DENA without the liver tumour.
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PMID:[The activity of nuclear endonucleases and topoisomerases in the liver of rats and in diethylnitrosamine-induced tumors]. 254 92

The target antigens for the complement-dependent cytotoxic antibodies in D23 tumour-bearer serum from rats carrying the chemically induced D23 hepatoma were extractable from extranuclear membranes of tumours with chloroform/methanol. The antigenic activity, measured by inhibition of D23 TBS cytotoxicity against D23 cells, was recovered in the phospholipid-containing fraction after silica gel chromatography. Preparative thin-layer chromatography (in chloroform/methanol/0.25% CaCl2) revealed that the antigenic activity migrated similarly to phosphatidylethanolamine and cardiolipin, although these phospholipids did not cause the inhibition seen with the antigenic fractions. Phospholipase A2 digestion of the phospholipid fraction did not affect the antigenic activity nor did it after the mobility of the antigen when analysed with thin-layer chromatography. From these results it was concluded that the antigen extracted from D23 hepatoma may be of phospholipid nature, although its molecular identity remains to be established.
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PMID:The lipid nature of a tumour-associated autoantigen from a chemically induced rat hepatoma. 617 53

pppA2'p5'A2'p5'A(2'-5'P3A3) activates macrophages and increases the phagocytosis of macrophages from different species including human beings. This indicates that the activation of macrophages may be a general action of 2'-5'P3A3. This discovery broadens the effect of 2'-5'P3A3 beyond the antiviral field. alpha-Feto-protein (AFP) inhibits the phagocytosis of macrophages and may be involved in the development of hepatoma. Data presented here show that 2'-5'P3A3 can antagonize this suppressive effect of AFP. Methods used so far for introducing 2'-5'P3A3 into the cells were made with the aid of CaCl2, etc. under conditions which may not be the same as those used clinically. It was found that 2'-5'P3A3 can develop its biological effect without the aid of CaCl2, etc.
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PMID:Mechanism of interferon action. Activation of macrophages and antagonism to alpha-feto-protein by pppA2'p5'A2'p5'A. 619 51

Poly(adenylic acid)-containing rat liver polysomal messenger ribonucleoprotein particles (pmRNP) were isolated and found to contain protein kinase activity. The association of the enzyme(s) with the particles was confirmed by experiments showing that the protein kinase activity comigrated with the pmRNP on metrizamide gradients and bound to oligo-(dT)-cellulose columns only under conditions where the pmRNP bound. The following properties were determined for the pmRNP-associated kinase(s). Casein and phosvitin were preferred substrates over histone and protamine. The optimal MgCl2 and KCl concentrations were found to be 12.5 and 50 mM, respectively. MnCl2 and CaCl2 could not replace MgCl2 and were inhibitory at low concentrations. The optimum pH range was 7.7--9.0, and the enzyme activity was cAMP independent. A molecular weight of 55 000--60 000 was determined for the kinase(s) by sucrose gradient analysis. The enzyme(s) was capable of phosphorylating proteins endogenous to the pmRNP. Membrane-bound pmRNP contained much less kinase activity than free pmRNP while pmRNP from hepatoma 7777 contained an elevated level of the enzyme(s). The relationship between the protein kinase activity and one of the pmRNP proteins of molecular weight 66 000 is discussed.
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PMID:Characterization of protein kinase activity associated with rat liver polysomal messenger ribonucleoprotein particles. 625 May 53

A 17-year-old male with previously undiagnosed congenital Factor IX deficiency (13%) presented with gastrointestinal bleeding and a hepatic mass. Prolonged thrombin and Reptilase times, which partially corrected with CaCl2 and a discrepancy between thrombin-clottable and immunoreactive plasma fibrinogen, suggested a dysfibrinogenemia. Laparotomy disclosed metastatic hepatoma. Adequate hemostasis was obtained with clotting factor replacement, but wound healing was delayed. Patient fibrinogen purified with 2.1 M glycine migrated normally on immunoelectrophoresis and 7.5% polyacrylamide-SDS gel electrophoresis. However, fibrin monomers prepared from purified patient fibrinogen displayed impaired aggregation at high and low ionic strengths when compared with fibrin monomers from normal and control Factor IX deficient subjects. Aggregation of normal monomers was delayed when mixed 1:1 with patient monomers. Fibrinopeptide release was normal, and total sialic acid content was similar to that of normal and control fibrinogens. Chemotherapy, consisting of 5-FU given via intra-arterial hepatic infusion, was accompanied by significant transient clinical improvement which coincided with correction of thrombin clotting times and fibrin monomer aggregation. Reappearance of fibrinogen dysfunction occurred with clinical deterioration prior to death from metastatic hepatoma and sepsis. This case is the first to corroborate the postulated tumor marker role of dysfibrinogenemia in a patient with hepatoma by documenting a direct relationship with response to chemotherapy.
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PMID:Acquired dysfibrinogenemia in a hemophiliac with hepatoma: resolution of fibrinogen dysfunction following chemotherapy. 626 56

1. The activities of cyclic cytidine 3',5'-monophosphate (cCMP) phosphodiesterase in normal rat liver and host liver (bearing hepatoma 5123 t.c.(h)) were compared with those of three Morris hepatomas of varying growth rates. 2. The results show that the order of enzyme activity was as follows: normal liver = host liver greater than 7794A (slow growth rate) greater than 5123 t.c.(h) (intermediate growth rate) greater than 7800 (fast growth rate). 3. The enzyme had a pH optimal value of about 7.0 and an apparent Km for cCMP about 2.8 mM; its activity was slightly affected by the presence of calmodulin (100 micrograms/ml) and/or CaCl2 (100 microM), but showed variable responses to other cations (La3+, Mg2+, Mn2+, Zn2+, Fe2+, Na+ and K+).
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PMID:Decreased activities of cyclic cytidine 3',5'-monophosphate phosphodiesterase in Morris hepatomas having varying growth rates. 630 41

We have separated and characterized a Ca2+- and calmodulin-insensitive cyclic nucleotide phosphodiesterase from rat liver supernatant as well as an analogous enzyme from HTC hepatoma cells. Chromatography of rat liver supernatant on DEAE-cellulose in the presence and subsequently in the absence of 0.1 mM-CaCl2 resulted in the separation of two distinct phosphodiesterase activities, both of which preferentially hydrolysed cyclic GMP rather than cyclic AMP. One enzyme, E-Ib, was activated in the presence of Ca2+ and calmodulin, and the other, E-Ia, was not. The E-Ia enzyme, which did not bind to calmodulin-Sepharose, had Mr 325 000 and displayed anomalous kinetic behaviour [Km (cyclic GMP) 1.2 microM; Km (cyclic AMP) 15.4 microM]. The E-Ib enzyme, which bound to calmodulin-Sepharose in the presence of Ca2+, had Mr 150 000 and exhibited Michaelis-Menten kinetics for hydrolysis of cyclic GMP [Km (basal) 6.5 microM; Km (activated) 12.0 microM]. E-Ia activity was diminished by incubation with alpha-chymotrypsin and was unaffected by the action of a rat kidney lysosomal proteinase. Partial hydrolysis of E-Ib enzyme by alpha-chymotrypsin or the kidney proteinase resulted in irreversible activation of the enzyme. The E-I enzyme isolated from HTC hepatoma cells was similar to the rat liver E-Ia enzyme in many respects. Its apparent Mr was 325 000. Its activity was unaffected by calmodulin in the presence of Ca2+ or by incubation with the kidney proteinase, and was decreased by digestion with alpha-chymotrypsin. Unlike the liver E-Ia enzyme, however, the hepatoma enzyme exhibited normal kinetic behaviour, with Km (cyclic GMP) 3.2 microM. Although HTC cells contain two other phosphodiesterases analogous to those in rat liver and a calmodulin-like activator of phosphodiesterase, no calmodulin-sensitive phosphodiesterase was detected.
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PMID:Ca2+-independent cyclic GMP phosphodiesterases from rat liver and HTC hepatoma cells. 631 Nov 63

A Golgi-rich fraction has been isolated from rat ascites hepatoma AH-130 cells. Unlike the usual procedure for isolating Golgi complexes from liver and other tissues, a hypotonic solution including 2 mM CaCl2 was used as the homogenization medium for the ascites hepatoma cells, followed by a combination of differential and discontinuous sucrose gradient centrifugations. Electron microscopic observation revealed that the isolated fraction consisted of cisternae, vesicles and tubular elements which were similar to those structures described previously for the Golgi fraction isolated from rat liver. Galactosyl- and sialyl-transferases were concentrated about 55- and 75-fold, respectively, in this fraction compared with the homogenate, indicating that these enzymes are useful markers for the Golgi complex of rat ascites hepatoma AH-130 cells, as they are for those of other normal tissues. The preparation was virtually free of cytochrome oxidase, but contained minor amounts of acid phosphatase, alkaline phosphatase and phosphodiesterase I activities. Electrophoretic analysis on sodium dodecylsulfate-polyacrylamide gels showed that the hepatoma Golgi membranes were resolved into at least 23 protein bands, which were apparently different from the electrophoretic profile of the plasma membrane isolated from the same hepatoma cells.
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PMID:Isolation and characterization of the Golgi complex from rat ascites hepatoma AH-130 cells. 714 13


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