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)

Amino acid starvation causes an adaptive increase in the initial rate of transport of selected neutral amino acids in an established line of rat hepatoma cells in tissue culture. After a lag of 30 min, the initial rate of transport of alpha-aminoisobutyric acid (AIB) increases to a maximum after 4 to 6 h starvation of 2 to 3 times that seen in control cells. The increased rate of transport is accompanied by an increase in the Vmax and a modest decrease in the Km for this transport system, and is reversed by readdition of amino acids. The enhancement is specific for amino acids transported by the A or alanine-preferring system (AIB, glycine, proline); uptake of amino acids transported by the L or leucine-preferring system (threonine, phenylalanine, tyrosine, leucine) or the Ly+ system for dibasci amino acids (lysine) is decreased under these conditions. Amino acids which compete with AIB for transport also prevent the starvation-induced increase in AIB transport; amino acids which do not compete fail to prevent the enhancement. Paradoxically threonine, phenylalanine, tryptophan, and tyrosine, which do not compete with AIB for transport, block the enhancement of transport upon amino acid starvation. The starvation-induced enhancement of amino acid transport does not appear to be the result of a release from transinhibition. After 30 min of amino acid starvation, AIB transport is either unchanged or slightly decreased even though amino acid pools are already depleted. Furthermore, loading cells with high concentrations of a single amino acid following a period of amino acid starvation fails to prevent the enhancement of AIB transport, whereas incubation of the cells with the single amino acid for the entire duration of amino acid starvation prevents the enhancement; intracellular amino acid pools are similar under both conditions. The enhancement of amino acid transport requires concomitant RNA and protein synthesis, consistent with the view that the adaptive increase reflects an increased amount of a rate-limiting protein involved in the transport process. Dexamethasone, which dramatically inhibits AIB transport in cells incubated in amino acid-containing medium, both blocks the starvation-induced increase in AIB transport, and causes a time-dependent decrease in transport velocity in cells whose transport has previously been enhanced by starvation.
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PMID:Derepression of amino acid transport by amino acid starvation in rat hepatoma cells. 1 7

Five monkeys were treated ip with N-nitrosodiethylamine (DENA), and one was treated with 1-nitrosopiperidine (PIP), starting within 2 months of birth, until hepatocellular carcinoma (HCC) developed. All animals except the PIP-treated monkey had much elevated serum alpha-fetoprotein (AFP) values. Fresh, minced, biopsy-derived tumor was cultured with L-[14C]leucine and L-[14C]lysine. Synthesis of AFP was determined by radioimmunoassay and by specifically precipitable [14C]AFP. Good agreement between these two parameters was obtained for the 4 DENA-induced tumors synthesizing AFP in culture. Tumor from 1 DENA-treated monkey did not synthesize AFP. In addition, neither normal liver nor tumor from the PIP-treated monkey showed AFP synthesis. Rates of synthesis were 0.37-5.50 ng AFP/mg tumor/day, or 0.0012-0.0183 pg AFP/cell/day (if one assumes 3.0 X 10(5) cells/mg tissue) over 48 or 72 hours. Different nodules from the same animal had similar rates of synthesis. For tumors that synthesized AFP in culture, a positive correlation was generally found between rate of synthesis and serum AFP level. The rate of in vitro AFP synthesis observed was lower than that of immunoglobulin synthesis in human myeloma or of AFP synthesis in a rat HCC, but it was close to the estimated rate of AFP synthesis in a monkey HCC line in long-term culture.
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PMID:In vitro alpha-fetoprotein synthesis by monkey hepatocellular carcinoma. 7 69

1. A serine protease of hepatoma 8999, isolated in the mitochondrial fraction, was purified and crystallized. The purified enzyme was apparently homogeneous on ultracentrifugal analysis and polyacrylamide disc gel electrophoresis. The ratio of absorbance at 280 nm and 260 nm, A280/A260, was 1.90 and its absorption coefficient, A280 1% was 10.5 cm-1 estimated from dry weight measurements. Its S20, w value was 2.23 S and its molecular weight was estimated to be 24000 +/- 1000. The enzyme contained twice as much lysine, arginine and histidine as chymotrypsinogen did, but had a very similar amino acid composition to serine protease from skeletal muscle. Its isoelectric point was pH 10.6. 2. The substrate specificity of the enzyme was the same as that of chymotrypsin A. Its Km and kcat values for N-acetyl-L-tyrosine ethyl ester, N-acetyl-L-phenylalanine ethyl ester and N-acetyl-L-tryptophan ethyl ester were 0.35 mM and 10.69 s-1, 0.38 mM and 10.7 s-1, and 0.11 mM and 11.8 s-1, respectively. Its activity was completely inhibited by phenylmethylsulfonyl fluoride and partially inhibited with tosylphenylalanine chloromethyl ketone. 3. The enzyme was shown to be located in different granules from the intracellular particules (light and heavy mitochondrial fraction) by sucrose density gradient centrifugation, and it was stained in mast cells of the hepatoma 8999 by the immunofluorescent technique. 4. Serine protease is present in different amounts in various organs of rat and the enzyme from hepatoma 8999 gave a single band that fused completely with those of the enzymes from skeletal muscle, heart, liver and kidney, respectively, on Ouchterlony double-diffusion analysis using antiserum to the crystalline enzyme of hepatoma 8999, but the enzyme from small intestine did not react with the antiserum.
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PMID:Purification, characterization and localization of serine protease of Morris hepatoma 8999. 11 11

Proteinase associated with chromatin isolated from liver and hepatoma of rat is stimulated by salt, and, of the histone fractions, lysine-rich (F1) histone is preferentially degraded by this enzyme at an ionic strength comparable with that found in the nucleus. However, there appears to be no strict relationship between the activity of the proteinase and growth rates of hepatomas. Chromatin isolated from a fast-growing tumour, Ehrlich ascites carcinoma, shows no apparent proteinase activity in the presence of salt.
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PMID:Lack of relationship between activity of chromatin-bound proteinase and cell growth rates. 16 17

The heat denaturation and renaturation curves of rat liver and ascites hepatoma (AH 108A) chromatins were measured. In these renaturation curves, there are small sigmoidal regions. These sigmoidal regions remained in redenaturation curves and were largely stable to DNAase I digestion. When the chromatins were treated stepwise with NaClO4 and lysine-rich histones were removed, the sigmoidal regions in the renaturation curves disappeared. These results suggested that the sigmoidal regions reflected the interaction of DNA and lysine-rich histones.
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PMID:Interaction of lysine-rich histone and DNA in chromatin structure. 16 42

Antibodies to chromatin proteins of Novikoff hepatoma cells formed precipitin bands in the double-diffusion immunoprecipitation assay with chromatin proteins of Novikoff hepatoma, Walker 256 carcinosarcoma, and 18-day fetal rat liver. The antigen used for preparation of antiserum was the chromatin proteins initially extracted with 3 M NaCl-7 M urea and soluble after dialysis to 0.14 M NaCl-0.35 M urea. The chromatin proteins used for analytical studies were extracted with 0.6 M NaCl containing 0.01 M Tris-HCl (pH 8) and 100 muM phenylmethylsulfonyl fluoride. Corresponding chromatin proteins of normal and 18-hr regenerating rat liver, heart, and kidney did not form precipitin bands. The antigen was purified from the chrmatin of Novikoff hepatoma cells by exclusion chromatography on Sephadex G-150 and preparative nondenaturing polyacrylamide gel electrophoresis. Its migration on denaturing sodium dodecyl sulfate-polyacrylamide gels corresponded to a molecular weight of 26,000. Amino acid analysis showed that the ratio of acidic to basic amino acids was 1.4 to 1.0. Evidence for its homogeneity included its migration as a single protein spot on two-dimensional polyacrylamide gel electrophoresis and its single lysine amino-terminal amino acid. This protein is a glycoprotein, as shown by the presence of 15 moles of galactosamine per mole of antigen. These studies demonstrate the presence of a fetal glycoprotein in the chromatin of two tumors that may have an important role in determining their gene products.
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PMID:A fetal protein in chromatin of Novikoff hepatoma and Walker 256 carcinosarcoma tumors that is absent from normal and regenerating rat liver. 18 70

1. The chemical composition of chromatins obtained from Buffalo rat liver and Morris hepatoma strain 5123 was investigated. 2. The presence of an additional subfraction within the very lysine-rich histone (fl) was states in both kinds of tissues. It amounted to about 8% and 5% of fl in rat liver and Morris hepatoma, respectively. 3. Nuclear phosphoproteins (phenol-soluble) from normal and tumour tissues in polyacrylamide gel in SDS showed some qualitative differences in the range of molecular weights of about 40 000 - 70 000 and over 100 000 daltons.
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PMID:Studies on histones and nuclear phosphoproteins of rat liver and Morris hepatoma. 18 36

The nonhistone chromatin protein, C-14, was extracted from chromatin of Novikoff hepatoma ascites cells and isolated in high purity as shown by its migration as a single dense spot on two-dimensional polyacrylamide gels. Its mobility on sodium dodecyl sulfate gels is consistent with a molecular weight of approximately 70 000. The amino acid composition shows that protein C-14 has an acidic:basic amino acid ratio of 1.8. Its amino terminal amino acid is lysine. Protein C-14 stimulated the incorporation of [3H]UMP into RNA by approximately 30% when added to naked DNA and homologous RNA polymerase I. A 30% stimulation of [3H]UMP incorporation into RNA was also found when protein C-14 was added to an E. coli RNA polymerase system containing either E. coli or Novikoff hepatoma DNA.
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PMID:Isolation and characterization of nonhistone chromosomal protein C-14 which stimulates RNA synthesis. 19 58

Protein 64/7.2 (molecular weight/isoelectric point) is present in the cytosol of several hepatomas including the Novikoff hepatoma and Morris hepatomas 9618A, 7794A, and 3924A, but it is not present in liver or 18-hr regenerating liver. Quantitatively, its concentration was highest in Novikoff hepatoma (150 microgram/g tissue) and Morris hepatoma 3924A (550 microgram/g tissue), which are rapid-growing tumors, less in Morris hepatoma 7794A (72 microgram/g tissue), which is of intermediate growth rate, and least in the slow-growing Morris hepatoma 9618A (25 microgram/g tissue). Protein 64/7.2 was isolated from Novikoff hepatoma ascites cells in high purity as shown by its migration as a single band on one-dimensional acid-urea-polyacrylamide gels and a single spot on two-dimensional isoelectric focusing sodium dodecyl sulfate-polyacrylamide gels. Its amino acid composition has an acidic to basic amino acid ratio of 1.6. Its amino-terminal amino acid is lysine, and its carboxyl-terminal amino acid is glycine. Interestingly, the amino acid composition is strikingly similar to that of the phosphorylated Novikoff hepatoma chromatin Protein Cg', partially characterized in our laboratory.
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PMID:Isolation and characterization of a cytosol protein (64/7.2) present in large amounts in rapidly growing hepatomas. 20 17

The nature of nuclear proteins that are soluble in 8 M urea-50 mM phosphate, pH 7.6, was compared in rat liver and Morris hepatomas, Isoelectric focusing, using carrier ampholytes for a pH gradient of 3.5 to 10, indicated that with increasing growth rate of the hepatomas there was a progressive tendency for a decrease in nonhistone nuclear proteins with isoelectric points in the range 7.5 to 8.9 and an increase in the range 5.1 to 6.7. Studies on the influence of time on the pH gradient revealed that a nonuniform drift provided a better resolution of the pH range 7.5 to 8.9 at 7 hr than at 24 hr, while the latter time for electrofocusing gave an improved resolution of the pH range 5.1 to 6.7 Polyarcylamide gel electrophoresis in a urea-acetic acid system showed that 8 M urea-50 mM phosphate; pH 7.6 extracted a small part of the histones from nuclei of both liver and hepatomas. There was less extraction of histones from the hepatoma nuclei, especially in two rapidly growing hepatomas with the most notable difference being seen in the lysine-rich H1 histone. The results suggested that in addition to qualitative or quantitative changes in nonhistone nuclear proteins in liver cancer there are alterations in the binding of histones to chromatin.
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PMID:Nuclear protein changes in rat hepatomas correlating with growth rate. 23 25


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