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 new line of tissue culture cells derived from a slow-growing hepatoma 8999 was established and named 8999C. The isolation method, growth pattern, and morphology of the 8999C cells are described. Several hepatic enzyme activities in 8999C cells were compared to those in the original hepatoma 8999. The ornithine aminotransferase (EC 2.6.1.13), tyrosine aminotransferase (EC 2.6.1.5), and arginase (EC 3.5.3.1) activities in the 8999C cells were one-third, one-tenth, and one-hundredth of those of the respective activities in the original hepatoma 8999, and mitochondrial serine protease, which has much higher activity in hepatoma 8999 than in normal liver cells, was not detected in 8999C cells. Tyrosine aminotransferase in 8999C cells was induced by dexamethasone but not by N6,O2'-dibutyryladenosine 3',5'-cyclic monophosphate or insulin. Unlike in hepatoma 8999, glucocorticoid did not induce arginase in 8999C cells.
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PMID:Establishment of a clonal strain of hepatoma cells derived from Morris hepatoma 8999. 2 74

Considerable thymidine kinase and pyrroline-5-carboxylate reductase activities were found in the plasma of rats bearing a transplanted lymphoma; neither activity was detected in plasma of hosts carrying hepatic, renal, mammary, or submaxillary gland tumors. All host livers exhibited signs of biochemical immaturity as indicated by the appropriate increases or decreases in the concentrations of the nine enzymes measured. The extent and time schedule of the changes in host liver varied with the enzyme and with the tumor that caused them. The hepatic concentrations of ornithine aminotransferase, arginase, pyrroline-5-carboxylate reductase, and glucokinase (all diminished), and of peptidyl proline hydroxylase and hexokinase (increased) were sensitive indicators of tumor growth in general. The concentration of ornithine aminotransferase decreased before the tumors became palpable. At more advanced stages, the high hepatic thymidine kinase activity distinguished the presence of hepatoma and lymphoma from those of all other equally fast-growing tumors. However, only in lymphoma-bearing rats did a fivefold elevation of hepatic thymidine kinase occur as early as 4 days after implantation. Additional observations on the lymphoma itself, on blood cells, and on the involuting thymus of normal rats indicate that the striking systemic effects of this tumor cannot be explained by a release of enzymes from the thymus or by the increased number of lymphoma cells present in blood or liver.
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PMID:The effect of lymphoma and other neoplasms on hepatic and plasma enzymes of the host rat. 18 34

Further biochemical characterization of the Albert hepatoma has been performed. The following results were obtained: In spite of often repeated transplantations and a medium growth rate, the Albert hepatoma does still contain organ-characteristic enzymes. We have found significant activities of glucokinase, glucose-6-phosphatase and arginase, and considerable amounts of noradrenaline and glycogen. In addition, it is capable to respond to humoral stimuli, that is, it differs from most of the other hepatocellular malignomas also in this regard.
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PMID:Activities of organ characteristic enzymes and noradrenaline and glycogen contents in the Albert hepatoma of C57BL mice. 22 50

The nature of soluble factors from liver and hepatomas which inhibit [3H]thymidine incorporation into DNA was studied in Novikoff hepatoma cells. The decreased activity in hepatoma preparations was due to loss of a high-molecular-weight heat-labile factor. Although this factor cochromatographed with arginase activity on Sephadex G-150, it does not appear to result from this activity as judged by the failure of arginine to prevent the inhibitory effect on [3H]thymidine incorporation. Both liver and hepatomas contained a heat-stable factor with inhibitory activity. Studies with ethanol-soluble material suggested that the action was not solely attributable to the presence of unlabeled thymidine, since the apparent molecular weight was too high and since the factor(s) inhibited [3H]leucine incorporation into protein in addition to inhibiting [3H]thymidine incorporation in DNA.
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PMID:Soluble factors from liver and hepatomas which inhibit [3H]thymidine incorporation into DNA of Novikoff hepatoma cells. 42 2

A previous study in rats showed that even though probucol substantially lowers high density lipoprotein (HDL) levels, near-normal mass transport of HDL cholesterol esters (CE) to the liver is maintained by the induction of "selective" (direct) uptake of HDL CE. The present study describes a parallel result in cultured Hep G2 human hepatoma cells. Cells were preincubated in the presence or absence of probucol before measuring the uptake of doubly labeled HDL3 in the absence of probucol. Preincubation with probucol decreased the uptake of HDL3 particles (iodine-125-labeled N-methyltyramine cellobiose-apolipoprotein [125I-NMTC-apo] A-I uptake) but increased the uptake of [3H]cholesteryl oleyl ether in excess of 125I-NMTC-apo A-I (i.e., selective uptake) in a dose-dependent fashion. The reversibly cell-associated pool of CE tracer, a precursor for selective uptake, enlarged on probucol treatment, but the increase was not in proportion to the increase in selective uptake. HDL3 particle uptake decreased on probucol treatment. The decrease was evident after less than 20 minutes of probucol exposure and was maximal after 6 hours; in contrast, HDL3 CE selective uptake increased only after greater than 13 hours and had not reached a plateau after 20 hours. Thus, effects on particle uptake and selective uptake were dissociated in time.
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PMID:Probucol increases the selective uptake of HDL cholesterol esters by Hep G2 human hepatoma cells. 131 37

In mammals, the apolipoprotein (apo) A-I gene is expressed predominantly in liver and intestine, while in avian species it is expressed in all tissues. Although liver and intestine are the major sites of chicken apoA-I mRNA synthesis, there are appreciable amounts of apoA-I mRNA in kidney, ovary/testes, brain, lung, skeletal, and heart muscle. In this study, the nucleotide sequences of the chicken apoA-I gene and its 5' flanking region, as well as the sequences involved in the expression of this gene, have been determined. The gene spans 1.5 kilobases and contains 4 exons and 3 introns, closely resembling the mammalian apoA-I gene. To determine the sequences involved in the expression of the chicken apoA-I gene, plasmid constructs containing serial deletions of the 5' flanking region of the chicken apoA-I gene fused to the bacterial chloramphenicol acetyltransferase (CAT) gene were transfected in human hepatoma (HepG2), colon carcinoma (Caco2), epithelial (Hela), mouse embryonal fibroblast (NIH3T3) cells, and quail myoblasts (QMLA29). The shortest deletion construct, containing 60 bp of the 5' upstream region, was sufficient for maximal transcriptional activity in all cell lines tested. This region contains a short sequence (nucleotides -60 to -54) that is highly conserved in birds and mammals, and an Sp1 binding site. Although the sequence between nucleotides -232 and -101 of the 5' region of the chicken apoA-I gene is partially homologous to the hepatic cell-specific enhancer of the mammalian apoA-I gene (located between nucleotides -222 and -110 upstream of the human apoA-I gene transcription start site), this chicken sequence is transcriptionally inactive in HepG2 cells. These results suggest that differences in the cis-acting regulatory elements of the apoA-I gene play a fundamental role in determining the differences in the tissue-specific expression of this gene in avian and mammalian species.
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PMID:Evolutionary distinct mechanisms regulate apolipoprotein A-I gene expression: differences between avian and mammalian apoA-I gene transcription control regions. 151 10

Addition of sodium butyrate to the culture medium of the human hepatoma cell line Hep G2 resulted in a time- and dose-dependent increase in the secretion of apolipoprotein A-I (apo A-I) and apolipoprotein B100 (apo B100). After a 24 h preincubation period, a 2.4- and 2.2-fold increase in the secretion of apo A-I and apo B100 respectively was obtained during the next 24 h in the presence of 2 mM-sodium butyrate. Secretion of albumin, fibrinogen or [35S]methionine-labelled newly synthesized proteins was unaffected or only marginally affected, indicating that the effect of butyrate on apo A-I and apo B100 is not part of a general effect on protein synthesis and secretion. In structure-function studies, butyrate was found to be the most potent inducer among various straight-chain carboxylic acids. Hydroxylated, aminated and otherwise modified butyrate derivatives were inactive. The enhanced accumulation of apo A-I and apo B100 in the culture medium could not be explained by changes in the uptake and degradation of the synthesized apolipoproteins or by alterations in the secretion of possible intracellular pools. In addition, [35S]methionine incorporation studies indicated that synthesis and/or secretion of newly synthesized apo A-I and apo B100 is enhanced in the presence of butyrate. The apo A-I mRNA level was increased 2.3-fold upon treatment with 2 mM-butyrate for 48 h, suggesting regulation at (post-)transcriptional level. In contrast, no change in the level of apo B100 mRNA in butyrate-treated cells was observed, indicating regulation at translational or co- or post-translational level. We propose that the effect of butyrate on the secretion of apo A-I and apo B100 by Hep G2 results from two different regulatory mechanisms.
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PMID:Butyrate stimulates the secretion of apolipoprotein (apo) A-I and apo B100 by the human hepatoma cell line Hep G2. Induction of apo A-I mRNA with no change of apo B100 mRNA. 165 87

Interactions of lipoproteins containing apolipoprotein (apo) A-I with or without apoA-II with human hepatoma cell line HepG2 were studied to investigate the ligand specificity for high density lipoprotein receptor on human hepatic cells and their metabolism. The two types of lipoproteins were isolated by immunoaffinity chromatography, in which apoE-containing lipoproteins were removed. Specific binding kinetics at 0 degrees C were observed for the apoA-I-containing lipoproteins with or without apoA-II (Kd = 18 or 20 micrograms protein/ml, Bmax = 110 or 120 ng/mg cell protein, respectively). The binding of these lipoproteins to HepG2 cells was competitively inhibited by excess unlabeled apoA-I-containing lipoproteins or apoA-I-phospholipid complexes, but not by apoA-II.phospholipid complexes. Interactions of these lipoproteins with HepG2 cells at 37 degrees C were further examined. These results suggested that HepG2 cells have a specific binding site for apoA-I-containing lipoproteins, and that apoA-I might be a crucial component in the binding of these lipoproteins to human hepatic cells.
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PMID:A specific binding site for lipoproteins containing apolipoprotein A-I on human hepatoma cell line HepG2. 166 78

Cytosolic extracts prepared from perfused whole liver or purified hepatocytes of C57BL/6 mice inhibited interleukin-2--and concanavalin A--induced spleen cell proliferation in vitro. In contrast, cytosolic extracts from purified nonparenchymal liver cells had no effect. Arginase and very-low-density lipoprotein were previously identified as two immuninhibitory substances present in liver cytosolic extracts. We demonstrated, however, that inhibitory activity remained after removal of very-low-density lipoprotein and arginase from liver cytosolic extract by repeated ultracentrifugation and gel filtration chromatography, respectively, suggesting the presence of another inhibitor. Further purification by anion-exchange chromatography and chromatofocusing led to the isolation of a novel liver-derived immunohibitory factor. This liver-derived immunoinhibitory factor is sensitive to pronase digestion and heat and acid treatment; it has an estimated isoelectric point of 8.25. The Mr of liver-derived immunoinhibitory factor is 28 kD as estimated from its migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which is identical under both reducing and nonreducing conditions, indicating a monomeric nature of this protein. Amino acid composition analysis discloses that liver-derived immunoinhibitory factor is relatively rich in glycine and proline residues. Interleukin-2--induced spleen cell proliferation in vitro is inhibited by ths liver-derived immunoinhibitory factor, with a 50% inhibitory dose of 1.4 nmol/L. Furthermore, the biological activity of the liver-derived immunoinhibitory factor is not confined to mouse spleen cells, since the growth of B16 mouse melanoma and H35 rat hepatoma cells is also inhibited. A comparison with other liver-derived immunoinhibitors reported previously supports our claim that the liver-derived immunoinhibitory factor is a novel inhibitory protein.
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PMID:Isolation and characterization of a novel liver-derived immunoinhibitory factor. 193 91

A solution hybridization/RNase protection assay with riboprobes was developed to quantitate apolipoprotein mRNA concentrations. Previously, radiolabeled DNA probes have been used in solution hybridization/S1 nuclease protection assays for this purpose. The new assay requires less time for probe preparation and hybridization compared to previous assays. In addition, the vector used for riboprobe preparation can also be used to conveniently produce cRNA required to generate the standard curve to quantitate absolute apolipoprotein mRNA levels. The solution hybridization RNase protection assay was used to quantitate apoB, A-I, and E mRNA levels in four human hepatoma cell lines, HepG2, Hep3B, WRL-68, SK-Hep2. HepG2 and Hep3B, but not WRL-68 and SK-Hep2 cells had concentrations of all three apolipoprotein mRNAs comparable to liver in vivo. These data suggest that HepG2 and Hep3B are suitable models to study liver specific apolipoprotein gene expression.
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PMID:A solution hybridization/RNase protection assay with riboprobes to determine absolute levels of apoB, A-I, and E mRNA in human hepatoma cell lines. 216 16


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