Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously a new glucocorticoid receptor (Peak C), which eluted with 0.12 to 0.14 M NaCl from DEAE-cellulose column, was identified in addition to another receptor (Peak B), a classic type of glucocorticoid receptor, which eluted with 0.05 to 0.08 M NaCl. Peak C appeared after stress or injection of a high dose (20 micrograms/100 g body weight) of dexamethasone into rats. Peak C was also detected in the liver of rats bearing various tumors, but it was not found in malignant tumors (Yoshida sarcoma and Yoshida ascites hepatoma AH 130), a less malignant Yoshida ascites hepatoma (LY-5), or in minimal deviation-type hepatomas (Morris hepatomas 7316A and 7794A). The absence of Peak C in these tumors coincided with the inability of the glucocorticoid to induce tryptophan oxygenase in these tumors and in the liver of rats during early postnatal development. Peak B was consistently observed in various hepatomas and immature rat liver with capability to induce tyrosine aminotransferase. Thus Peak C appeared to be a highly differentiated type of glucocorticoid receptor mediating specific hormone actions and to be present in mature liver cells, but not in immature liver or tumor cells, even of the minimal deviation type.
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PMID:A new glucocorticoid receptor detected in host rat liver but not in various hepatomas. 288 83

Uridine phosphorylase activity was detected in sonic extracts of six different mammalian cell lines and, in conjunction with uridine kinase, provides a route for the conversion of uracil to UMP via uridine. Uracil phosphoribosyl transferase activity was not detected in any of eight different mammalian cell lines. Uridine phosphorylase was purified 5,330-fold from Novikoff rat hepatoma cells by ammonium sulfate precipitation, DEAE-Sephadex chromatography, hydroxyapatite chromatography, and Sephadex G-200 fractionation. The molecular weight of the enzyme by gel filtration was approximately 45,000. The kinetics of the purified enzyme were analyzed with respect to all four substrates at saturating cosubstrate concentration, yielding the parameters KmUra = 360 microM, KmRib-1-P = 88 microM, KmUrd = 16 micron, and KmPi = 130 microM. However, in intact cells the phosphorolysis of uridine proceeded with an apparent Km of 231 microM. Novikoff cells treated with 0.5 mM inosine exhibited an increase in uracil uptake rate which was proportional to an observed increase in intracellular ribose-1-phosphate. Nevertheless, in cells whose de novo synthesis of pyrimidines was blocked by pyrazofurin or N-(phosphonacetyl)-L-aspartate ("PALA"), the uptake of uracil was insufficient to support proliferation, even when enhanced by inosine. These observations are consistent with the kinetic characteristics of the enzyme and provide evidence that the intracellular level of ribose-1-phosphate plays a rate-limiting role in the uptake of uracil mediated by uridine phosphorylase.
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PMID:Uridine phosphorylase from Novikoff rat hepatoma cells: purification, kinetic properties, and its role in uracil anabolism. 298 97

Poly(A) polymerases were purified from the cytosol fraction of rat liver and Morris hepatoma 3924A and compared to previously purified nuclear poly(A) polymerases. Chromatographic fractionation of the hepatoma cytosol on a DEAE-Sephadex column yielded approximately 5 times as much poly(A) polymerase as was obtained from fractionation of the liver cytosol. Hepatoma cytosol contained a single poly(A) polymerase species [48 kilodaltons (kDa)] which was indistinguishable from the hepatoma nuclear enzyme (48 kDa) on the basis of CNBr cleavage maps. Liver cytosol contained two poly(A) polymerase species (40 and 48 kDa). The CNBr cleavage patterns of these two enzymes were distinct from each other. However, the cleavage pattern of the 40-kDa enzyme was similar to that of the major liver nuclear poly(A) polymerase (36 kDa), and approximately three-fourths of the peptide fragments derived from the 48-kDa species were identical with those from the hepatoma enzymes (48 kDa). NI-type protein kinases from liver or hepatoma stimulated hepatoma nuclear and cytosolic poly(A) polymerases 4-6-fold. In contrast, the liver cytosolic 40- and 48-kDa poly(A) polymerases were stimulated only slightly or inhibited by similar units of the protein kinases. Antibodies produced in rabbits against purified hepatoma nuclear poly(A) polymerase reacted equally well with hepatoma nuclear and cytosolic enzyme but only 80% as well with the liver cytosolic 48-kDa poly(A) polymerase and not at all with liver cytosolic 40-kDa or nuclear 36-kDa enzymes. Anti-poly(A) polymerase antibodies present in the serum of a hepatoma-bearing rat reacted with hepatoma nuclear and cytosolic poly(A) polymerases to the same extent but only 40% as well with the liver cytosolic 48-kDa enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of cytosolic and nuclear poly(A) polymerases from rat liver and a hepatoma: structural and immunological properties and response to NI-type protein kinases. 300 Apr 24

Seryl/threonyl-protein kinases in cytosolic and particulate fractions from rat liver and AH-13, a rat ascites hepatoma, have been studied by chromatographing these fractions on DEAE-cellulose and assaying the eluates with casein, phosvitin, histone and protamine as substrates. Liver cytosolic fraction contains a group of well-characterized seryl/threonyl-protein kinases, namely, casein kinases I and II and histone kinases I and II. Liver particulate fraction, on the other hand, is almost totally devoid of casein kinase I and histone kinase I but contains an additional peak of casein kinase tentatively designated casein kinase III. In AH-13, cytosolic casein kinase I is markedly increased and particulate-associated casein kinases II and III are moderately increased as compared with liver. Moreover, it was found that in AH-13, the histone kinase I level is high in the particulate fraction but markedly decreased in the cytosolic fraction. It is suggested that particulate-associated histone kinase I may be of cytosolic origin.
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PMID:Casein and histone kinases of a rat ascites hepatoma as compared with those of rat liver. 300 7

Monguine, a thermostable toxic protein was extracted from the seeds of Croton mongue (Euphorbiaceae) and purified by ion-exchange chromatography on DEAE-cellulose and gel filtration on Sephadex G-25 and G-15. Polyacrylamide gel electrophoresis of purified monguine in the presence of sodium dodecyl sulfate and after treatment with 2-mercaptoethanol showed one band corresponding to a molecular weight of 9000. The same molecular weight was determined by analytical centrifugation. Amino acid analysis revealed a high content in both aspartic and glutamic acids (or the corresponding amides). The LD50 (24 h) is 12 mg/kg of mouse body weight. Monguine inhibits protein synthesis in hepatoma tissue culture cells and globin synthesis in a rabbit reticulocyte lysate.
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PMID:Purification and characterization of a toxin inhibiting protein synthesis from Croton mongue, a Madagascar Euphorbiaceae. 309 7

Using the particulate fraction of tissue homogenate, plasma membrane-associated sialidase was assayed at pH 4.5 with bovine brain mixed gangliosides as the substrate. The activity was lower in rat hepatoma induced by 3'-methyl-4-dimethylaminoazobenzene (MeDAB) and transplantable AH-109A rat hepatoma than in normal rat liver. The enzyme was almost quantitatively solubilized from liver particulate fraction by using 0.5% (w/v) sodium deoxycholate plus 0.2% (w/v) Triton X-100. When chromatographed on DEAE-cellulose, the solubilized activity emerged as a single peak. The enzyme thus obtained was maximally active at pH 4.5, and readily hydrolyzed mixed gangliosides but was less active toward 4-methylumbelliferyl-alpha-N-acetylneuraminic acid, 3'-sialyllactose and fetuin. The corresponding enzyme from MeDAB-induced hepatoma was indistinguishable from the liver enzyme in terms of ease of solubilization, pH-activity relationship, chromatographic behavior and substrate preference. It therefore appears that the plasma membrane-associated sialidase of hepatomas differs from that of liver only in the tissue level of activity.
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PMID:Membrane-associated sialidase of rat liver and its decrease in hepatomas. 312 7

A method is described for introducing and expressing cloned genes in isolated hepatocytes. Primary rat hepatocytes isolated by collagenase perfusion were transfected in suspension with plasmid pSV2CAT by electroporation. Forty-eight hours later, soluble extracts from transfected hepatocytes showed chloramphenicol acetyltransferase activity comparable to that obtained in rat hepatoma cell line H4AzC2 by calcium phosphate or DEAE-dextran transfection. The latter two methods could not be used successfully for primary hepatocytes because of cytotoxicity of these reagents. This indicates that electroporation is a useful method to obtain transient expression of foreign genes in primary epithelial cells, such as rat hepatocytes, which are difficult to maintain in cell culture.
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PMID:Use of electroporation to introduce biologically active foreign genes into primary rat hepatocytes. 346 23

We have attempted to purify endogenous substrate proteins for casein kinases I and II from the cytosol of AH-66 hepatoma cells. Utilizing the fact that only a few substrates are concentrated in the fraction eluted from DEAE-cellulose between 0.3 and 0.6 M NaCl, two substrates were purified from this fraction by DEAE-cellulose chromatography, hydroxyapatite chromatography, and HPLC on a DEAE-5PW column. The purified substrate proteins had molecular masses of 30.5 kDa and 31 kDa. The 31-kDa protein substrate was markedly phosphorylated by casein kinase II, but only slightly by casein kinase I. The radioactive phosphate incorporated into 31-kDa substrate by casein kinase II was 0.2 mol/mol of the protein and phosphorylation occurred on both threonine and serine residues. The 30.5 kDa protein was only slightly phosphorylated by casein kinase II, but not at all by casein kinase I.
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PMID:Purification of substrate proteins of casein kinases from the cytosol fraction of AH-66 hepatoma cells. 347 93

Nuclear extract from Morris hepatoma 3924A was fractionated by DEAE-Sephadex chromatography. The fraction eluting with 300 mM (NH4)2SO4 (DE-C) was used for transcribing cloned mouse metallothionein-I (MT-I) gene in a run-off assay. This fraction contained the majority of RNA polymerase II as well as the transcription factor(s). Accuracy of MT-I DNA transcription was confirmed by S1 nuclease mapping. Low concentrations (1 microgram/ml) of alpha-amanitin inhibited the reaction, indicating that RNA polymerase II directed the transcription. Unfractionated nuclear extracts from the hepatoma or a rat mammary adenocarcinoma as well as whole cell extract obtained from the mammary tumor also transcribed MT-I gene. The extent of transcriptional activity was in the following order: hepatoma nuclear fraction DE-C greater than whole cell extract derived from rat mammary adenocarcinoma cells greater than nuclear extract derived from rat hepatoma or rat mammary adenocarcinoma cells. These studies have demonstrated that a fractionated nuclear extract obtained from a tissue supports efficient and accurate RNA polymerase II-mediated transcription of MT-I DNA.
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PMID:Accurate transcription of mouse metallothionein-I gene in a fractionated nuclear extract from a rat hepatoma. 355

A growth factor has been isolated from HTC-SR rat hepatoma tissue culture cells which specifically stimulates DNA synthesis and cell proliferation of the HTC cells that produce it. The factor can be isolated from HTC cell conditioned medium or from an HTC cell extract. This autocrine factor has been purified 640-fold from a postmicrosomal supernatant by successive steps, involving ethanol precipitation, heating at 80 degrees C for 10 min, chromatography on a DEAE Bio-Gel A column, and chromatography on a heparin-sepharose affinity column. The major peak of activity eluted from the heparin column migrates as a single band on SDS-PAGE with an apparent Mr of 60,000. The factor is resistant to acid, heat, and neuraminidase but sensitive to trypsin, papain, and protease. The autocrine nature of the factor is indicated by the finding that several other types of cells do not respond with increased DNA synthesis. Mouse L-cells, BHK cells, Novikoff hepatoma cells, hepatocytes in primary culture, and an epithelial-like rat liver-derived cell line (Clone 9) were tested, and none of the cells could be stimulated. Small amounts of the factor could be extracted from the Clone 9 cells, however. This material had the same physical and purification properties as the factor extracted from HTC cells, but it did not stimulate DNA synthesis in Clone 9 cells, only in HTC cells. Addition of the factor resulted in an almost immediate stimulation of DNA synthesis in a proliferating HTC cell population. When the factor was added together with [3H]thymidine for 2 h, a significant stimulation of DNA synthesis was observed, provided the addition was made between 18 and 48 h after the cells had been plated. Autoradiographic studies indicated that the factor both accelerates DNA synthesis in cells already making DNA and increases the number of cells entering the S period. The stimulation of DNA synthesis was completely inhibited by 10 mM hydroxyurea, whether the factor was present for 2, 24, or 48 h in the culture. A significant increase in cell number due to addition of the factor was also observed. This accelerated proliferation was detectable only after the cells had been in culture for at least 48 h with the factor present.
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PMID:Isolation of an autocrine growth factor from hepatoma HTC-SR cells. 358 47


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