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)

A non-histone protein was obtained by extraction of nuclei derived from rat liver or thymus or ascites-hepatoma cells with 5% (w/v) HClO(4). Separation from histone F1 was achieved by chromatography on DEAE-cellulose. The purified component P1 was characterized and the formation of complexes with histone F1 and polylysine was studied.
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PMID:The characterization of a non-histone protein isolated from histone F1 preparations. 435 16

Rates of histone acetylation and deacetylation in nuclei from fetal, adult, and two kinds of neoplastic rat hepatocytes were examined. Histone acetylation in isolated nuclei was measured in the presence of 6 mM sodium n-butyrate, a potent inhibitor of deacetylase, and in the absence of the inhibitor. The deacetylase activity was estimated from the difference between the rates with or without the inhibitor. Both histone acetylation and deacetylation in nuclei from hepatoma cells (AH 66 cells) occurred two times faster than those of nuclei from fetal and adult livers regardless of alpha-fetoprotein production. This increased acetylation and deacetylation in hepatoma cells may be ascribed to either the increased activities of the enzymes or the increased accessibility of histone to the enzymes in the chromatin. Autoradiographic analysis of acetylated histones showed that all of the internal histones of the nucleosomes were acetylated and that apparent difference was found in the pattern of acetylated fractions between hepatoma nuclei and normal liver cell nuclei.
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PMID:Increased histone acetylation and deacetylation in rat ascites hepatoma cells. 616 24

We have found that butyrate selectively inhibits hormonal induction of a few specific proteins and messenger RNAs in hepatoma cells. The fatty acid salt reversibly abolishes induction of tyrosine aminotransferase by dexamethasone and dibutyryl cyclic AMP in HTC cells by inhibiting the production of tyrosine aminotransferase messenger RNA. Half-maximal inhibition of enzyme induction occurred in 0.9 mM butyrate. This effect is highly specific, since 4 h after the addition of butyrate to induced HTC cells, the relative abundance of only five messenger RNA species out of several hundred observable on two-dimensional gels of translational products is changed. Upon removal of the butyrate from cell cultures pretreated with dexamethasone, tyrosine aminotransferase activity begins to increase more rapidly than if dexamethasone is added to control cultures, indicating that part of the induction process occurs in the presence of butyrate. A dose-dependent reduction of fast histone acetylation by butyrate was demonstrated by treating cells with butyrate followed by a short pulse with [3H]acetate and chase in a high concentration of butyrate. The butyrate concentration test range over which rapid histone acetylation is inhibited is similar to that which inhibits enzyme induction to the same extent. In contrast, the slow form of histone acetylation is unaffected in the concentration range examined. The induction of tyrosine aminotransferase by dexamethasone is delayed in hypoacetylated cells. This lag is consistent with the time required to initiate the recovery of the fast form of histone acetylation after its transient disappearance (Covault, J., Perry, M., and Chalkley, R. (1982) J. Biol. Chem. 257, 13433-13440). We conclude that sodium butyrate interferes with the ability of dexamethasone and dibutyryl cyclic AMP to increase production of several specific species of messenger RNA in hepatoma cells. This effect correlates well with its ability to reduce rapid acetylation of histones in HTC cells; we discuss potential roles of rapid histone acetylation in modulating hormonal stimulation of transcription.
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PMID:Inhibition by sodium butyrate of enzyme induction by glucocorticoids and dibutyryl cyclic AMP. A role for the rapid form of histone acetylation. 619 55

Protamine sulfate reversibly inhibits serum-induced mitogenic stimulation of several nontransformed and neoplastic cell types in vitro. Fifty percent inhibition was induced by approximately 120-150 micrograms protamine sulfate/ml. Cells were affected directly, and inhibition depended on the duration of cell exposure. Heparin, chondroitin sulfate, heparan sulfate, and dextran sulfate neutralized protamine sulfate effects during the early stages of treatment. Nontransformed cells [bovine aortic endothelial cells, adult human gingival fibroblasts (strains 423 and 1101), fetal rat skin (strain 921-K) and muscle fibroblasts] required longer exposure to induce inhibition than did neoplastic cells [rat 3-methylcholanthrene-induced fibrosarcoma cell lines (MCA-6 and MCA-9), a macrophage-like cell line (NCTC-3749), Walker 256 rat carcinoma cells (ATCC-CCL-38), rat Morris hepatoma cells (ATCC-CCL-144), murine melanoma cells (B16), and rat bladder squamous cell carcinoma cells (804-G)]. Other polycationic compounds, including histone type VIII-S, poly-L-lysine, poly-L-arginine, and protamine (free base), were also effective inhibitors, whereas the basic proteins cytochrome c and lysozyme had no effect. Poly-L-histidine, poly-L-glutamic acid, poly-L-aspartic acid, and dextran blue also had no inhibitory effect.
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PMID:Protamine sulfate inhibition of serum-induced mitogenic responses: differential effects on normal and neoplastic cells. 621 Mar 90

Mononucleosomes obtained from cultured mouse hepatoma cells were incubated with RNA polymerase II from wheat germ. No free DNA was liberated as available templates under the experimental condition employed. Size analysis of the transcripts showed that the polymerase initiated transcription from either terminus and read through the DNA template of mononucleosomes. Sucrose density gradient centrifugation of the reaction mixture resolved mononucleosome-polymerase complexes from free materials. The complexes were characterized by the enrichment of DNA fragments containing the nucleosome linker region, the presence of H1 histone, and the increased susceptibility to DNase I. Both the complexes formed in the presence and absence of precursor nucleotides were susceptible. These suggest that RNA polymerase II prefers to bind to the linker region, and the polymerase-bound nucleosomes are structurally altered. The data were discussed in context with possible mechanisms of transcription of the nucleosome structure.
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PMID:Formation of transcribing mononucleosome-eukaryotic RNA polymerase II complexes in vitro as a simple model of active chromatin. 623 May 98

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

In this study, we have density-labeled newly replicated DNA in hepatoma tissue culture cells and separated the newly replicated nucleoprotein from bulk material using density gradient centrifugation. These experiments indicate that only newly synthesized histones H3 and H4 deposit specifically on newly replicated DNA. Histones H2A and H2B show a partial preference and histone H1 shows no preference for deposition on new DNA. These experiments also indicate that for a whole cell cycle, the non-H1 histones remain associated with the same DNA upon which they were initially deposited. However, when that region is replicated during the next cell cycle, the histones distribute equally to both daughter strands. An increase or decrease in the level of histone modification (acetylation) induced by sodium butyrate treatment does not alter the in vivo stability of the histone-DNA interactions. Experiments which involved labeling SV40 minichromosomes with [3H]lysine confirm our observations that only newly synthesized histone H3 and H4 are selectively depend on replicated DNA.
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PMID:A reevaluation of new histone deposition on replicating chromatin. 626 16

The phosphorylation of electrophoretically homogeneous preparations of the five major subcomponents of that thymus H1 histone by growth-associated histone kinase isolated from Ehrlich ascites tumor or Novikoff hepatoma cell chromatin results in the introduction of three to six phosphates/molecule into different subcomponents. Fully phosphorylated preparations of subcomponents 1 through 4 consist of H1 molecules containing a uniform number of phosphate groups, and run as single bands in long acid-urea gels. Fully phosphorylated preparations of subcomponent 5 consist of a mixture of molecules containing five and six phosphate groups. Phosphorylation of subcomponents 2, 4, and 5 occurs in both the NH2- and carboxyl-terminal regions of the molecules. Phosphorylation of subcomponents 1 and 3 occurs only in the carboxyl-terminal region. The central globular region of the histones is not phosphorylated. The major sites of phosphorylation in rat H1 histone subcomponents are similar to, but not entirely identical with, the major sites of phosphorylation previously characterized in total calf thymus H1, as determined by comparison of phosphopeptide maps. Highly phosphorylated rat H1 molecules, similar in phosphate content to those found in mitotic cells, have distinct chromatographic properties, compared to lightly phosphorylated molecules of the type found in interphase cells. This change in chromatographic properties appears to depend on the number of phosphate groups present in the histone rather than on the presence of phosphate in any specific sites.
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PMID:Characterization of highly phosphorylated subcomponents of rat thymus H1 histone. 629 83

Endogenous phosphorylation reaction of the cytosol fraction of AH-66 hepatoma ascites cells in vitro was compared with that of normal rat liver. Cytosolic proteins with molecular weights of 125,000, 98,000, and 40,000 of AH-66 cells were heavily phosphorylated in a cyclic adenosine 3':5'-monophosphate-independent manner, but no counterpart was detected in normal liver cytosol. In order to examine whether these phosphoproteins were specifically present in AH-66 cytosol, cyclic adenosine 3':5'-monophosphate-independent protein kinases which phosphorylate these phosphoproteins were partially purified from AH-66 and liver cytosol by successive chromatography. Both kinase preparations were essentially free of endogenous protein substrates and catalyzed the phosphorylation of exogenous substrates, such as casein and phosvitin, but not histone and protamine. Both kinases markedly catalyzed the phosphorylation of the Mr 125,000, 98,000, and 40,000 proteins in AH-66 cytosol. The Mr 125,000, 98,000 and 40,000 proteins in liver cytosol were less intensely phosphorylated by the addition of the kinase from AH-66 cytosol. From these results, we conclude that these phosphoproteins are present in both AH-66 cytosol and liver cytosol but are highly concentrated in AH-66 cytosol.
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PMID:Characterization of protein phosphorylation of the cytosol of AH-66 hepatoma ascites cells. 630 94

From rat-liver and ascites-hepatoma chromatins, NaCl-soluble fractions were prepared. The 0.35 M NaCl-soluble fraction from the hepatoma (AH) chromatin contained much non-histone protein of high-molecular weight, compared with the fraction from the rat-liver (RL) chromatin. The 0.35 M NaCl-insoluble, but 2 M NaCl/5 M urea-soluble fraction was composed mainly of 5 classes of histones. These histones were quantitatively not different between AH and RL chromatins. However, H1 histone was rather protease-resistant in AH chromatin, but not in RL chromatin. The proteolytic capacity was also lower in AH chromatin. In addition, in the micrococcal-nuclease digest of AH nuclei, the oligonucleosomes were considerably retained even by long-time digestion, but not in that of RL nuclei.
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PMID:Resistance of H1 histone to proteolytic attack in chromatin from rat-ascites hepatoma. 636 Mar 39


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