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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Low molecular weight nuclear RNAs (LMWN RNAs) of normal and neoplastic tissues: the rat liver and Zajdela hepatoma, mouse spleen and NK/Ly ascites tumor, as well as the cultures of normal chick embryo fibroblasts and of those transformed with Rous sarcoma virus were studied by electrophoresis in 8% and 15% polyacrylamide gels. As a result of the study no qualitative differences, i.e. differences in the number of LMWN RNA main fractions and their electrophoretic mobility were found. But there were revealed quantitative variations in the relative amount of definite fractions of these RNAs. An increase of the U3 RNA content in ascites tumors may be connected with an enhancement of the ribosomal RNA synthesis. Variations in the content of low molecular weight RNAs in oncogenic virus transformed cells may reflect an excessive synthesis of low molecular weight viral RNAs during the process of virus reproduction. The quantitative alterations observed seem to be of special value since LMWN RNAs are likely to perform regulatory functions.
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PMID:[A change in the relative concentration of individual fractions of low molecular weight nuclear RNA in tumor tissues]. 17 15

Immunization of CBAT6T6 mice with MC-29 hepatoma antigen did not change the take of Rous sarcoma virus, Schmidt-Ruppin strain [RSV(SR)] mouse tumors after sc transplantation. Immunization with MC-29 hepatoma antigen only slightly increased the average survival time of the mice and significantly decreased tumor growth only at the minimal lethal dose level. Immunization of mice with MC-29 hepatoma antigen and immunization with chicken Rous sarcoma gave similar results; both elicited much less transplantation resistance than immunization with irradiated RSV(SR) mouse tumor cells. The data indicate that there are common tumor-specific transplantation antigens of MC-29 hepatoma and Rouse sarcoma, but further in vitro experiments are needed to prove this.
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PMID:Comparative study of tumor-specific transplantation antigens of MC-29 chicken hepatoma and Rous sarcoma virus-induced sarcomas in mice. 22 8

Sodium cyanate, which in its tautomeric acidic form, isocyanic acid, acts as a protein carbamylating reagent, has been previously shown to inhibit selectively both DNA and protein synthesis in a variety of solid tumors. We have now compared its effects on protein synthesis in normal colonic epithelium and in colon tumors induced by the administration of 1,2-dimethylhydrazine to rats. The incorporation of 3H-amino acids into cytoplasmic and nuclear protein fractions was suppressed to a much greater extent in the tumor tissue than in colonic epithelial tissue surrounding the tumors of cyanate-treated rats. Despite its effect on tumor protein synthesis in whole animals, cyanate had little or no effect on cultured cells (HT-29) derived from a human adenocarcinoma of the colon, nor on other malignant cell lines such as HeLa S3 cells, chick fibroblasts transformed by the Rous sarcoma virus, mouse Ehrlich ascites tumor cells, or rat Novikoff hepatoma cells. However, the administration of cyanate i.p. does suppress amino acid incorporation by Novikoff hepatoma cells in the peritoneal cavity of rats. The implication that the mechanism of cyanate inhibition of protein synthesis in tumors may require its in vivo metabolism or utilization to produce a postsynthetic modification of circulatory factors is discussed.
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PMID:Selective inhibition with sodium cyanate of protein synthesis in colon cancer cells. 92 6

The transport and proteolytic processing of two individual gene isolates of the mouse mammary tumor virus (MMTV) glycoprotein were compared in transfected rat HTC hepatoma cells. Plasmids were constructed such that the MMTV glycoprotein genes were constitutively expressed from the promoter within the Rous Sarcoma Virus 5' Long Terminal Repeat in the absence of other MMTV proteins. An isolate of the GR strain MMTV glycoprotein was efficiently transported and processed resulting in the localization of MMTV glycoproteins at the cell surface and in the extracellular environment. Moreover, the kinetics of acquisition of endoglycosidase H resistant oligosaccharide side chains and the rate of endoproteolytic cleavage of the glycosylated polyprotein expressed in transfected cells were virtually identical to that observed in viral-infected rat hepatoma cells. In contrast, a natural variant of the C3H strain MMTV glycoprotein expressed in transfected cells was retained in an intracellular compartment by a heavy chain binding protein (BiP)-independent pathway in an endoglycosidase H sensitive and uncleaved form. This MMTV glycoprotein isolate was retained early in the exocytic pathway and displayed a half-life of approximately 45 min in transfected cells. Only a minor fraction of the expressed C3H variant glycoprotein was detected at the cell surface but was not externalized. Our results suggest that the variant C3H MMTV glycoprotein contains one or more mutations that preclude its efficient transport through the exocytic pathway.
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PMID:Differential transport and processing of variant mouse mammary tumor virus glycoproteins. 133 Nov 25

The angiotensinogen gene encodes the precursor protein for the potent vasoconstrictor angiotensin II. Although the gene is expressed in several tissues, the liver is the major source of circulating protein. In previous in-vivo studies we have found that a mini-gene containing 750 bp of 5'-flanking sequence is transcribed in a manner which largely parallels the expression of the endogenous gene. In this report, we characterized conserved elements in the promoter region, in order to determine their role in the transcription of the angiotensinogen gene. Constructs fused to the chloramphenicol acetyl transferase (CAT) reporter gene were transfected into hepatocarcinoma Hep G2 cells as well as into nonhepatic cell lines. We found that 5'-deletion mutant constructs, containing sequences from +25 to -90 bp and -321 to -750 bp, were each able to activate transcription. These constructs contain the TATA box and core promoter sequences, including an Sp1-binding site, and two glucocorticoid responsive elements respectively. In the non-hepatic cell lines, HeLa and Jeg-3, we found that the constructs were transcribed at a much lower rate when compared with the expression of a plasmid containing the Rous sarcoma virus long terminal repeat fused to the CAT gene. Constructs which included sequence 5' to -244 were oestrogen inducible. An element which is conserved between rodent and human angiotensinogen promoters is contained within a sequence which is oestrogen responsive, while another binds the liver-enriched transcriptional activator hepatocyte nuclear factor 1. However, the role of this transactivator in the transcription of angiotensinogen remains uncertain.
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PMID:The function of conserved elements in the promoter of the mouse angiotensinogen gene. 151 23

A mutational analysis was used to identify structural domains that are important for exocytic transport and proteolytic cleavage of the mouse mammary tumor virus (MMTV) glycoprotein, which is expressed as a multidomain polyprotein. Rat HTC hepatoma cells were transfected with the MMTV glycoprotein gene driven by the constitutive Rous sarcoma virus promoter, with mutant genes encoding a series of polypeptide truncations or with a defective MMTV provirus containing a premature termination codon in the viral glycoprotein gene. Efficient proteolytic maturation and transport of MMTV glycoproteins to the cell surface or extracellular environment required the presence of the transmembrane domain but not the cytoplasmic tail. Two stable truncations retaining the hydrophobic region of the ectodomain in the absence of the transmembrane domain and cytoplasmic tail (trgp67 and trgp58) remained in endoglycosidase H sensitive and uncleaved forms. One of these truncations, trgp58, appeared to be tightly associated with intracellular membranes and strongly bound by heavy chain binding protein, whereas the other truncation, trgp67, was a soluble component of the lumen and persists intracellularly by a heavy chain binding protein-independent pathway. The truncated MMTV glycoprotein additionally lacking the hydrophobic region of the ectodomain was efficiently secreted. Taken together, our results demonstrate that the hydrophobic transmembrane domain of the MMTV glycoprotein is required for proper transport and proteolytic processing, whereas, in the absence of the transmembrane domain, the presence of a hydrophobic region of the ectodomain correlated with retention at an early step in the exocytic pathway.
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PMID:Expression of mouse mammary tumor virus glycoprotein truncations defines roles for the transmembrane domain and ectodomain hydrophobic region in constitutive exocytic trafficking and proteolytic processing. 165 86

A full-length cDNA for the rat liver enzyme tyrosine aminotransferase has been used to construct mammalian expression vectors by recombinant DNA techniques. These vectors, which have employed either a simian virus 40 or a Rous sarcoma virus promoter, were transfected into a variety of nonhepatic mammalian cell lines in culture. Transient expression of tyrosine aminotransferase was readily observed after transfection into monkey COS cells and mouse L cells. Stable clones that express cloned tyrosine aminotransferase have been isolated from mouse L cells, hamster Wg1a fibroblasts, and Chinese hamster ovary (CHO) cells. A vector capable of expressing both tyrosine aminotransferase and dihydrofolate reductase was stimulated to undergo amplification by treatment with methotrexate in a CHO cell line deficient in the latter enzyme. Levels of tyrosine aminotransferase as much as 50-fold higher than typically seen in glucocorticoid-induced hepatoma cells were achieved in some CHO clones by this technique. The tyrosine aminotransferase produced at these highly amplified levels appeared structurally normal and had no major harmful effects on the cells.
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PMID:Expression and amplification of cloned rat liver tyrosine aminotransferase in nonhepatic cells. 196 11

The gene encoding the hepatitis delta virus (HDV) structural antigen (HD Ag) was inserted into a Rous sarcoma virus expression vector and the recombinant plasmid used to direct the synthesis of recombinant HD Ag (rHD Ag) in a continuous hepatoma cell line. A competitive radioimmunoassay for serum antibody to HDV using rHD Ag was developed and was found to be equally suitable for diagnostic purposes to a radioimmunoassay using infected liver-derived HD Ag. Similarly, rHD Ag was shown to be serologically equivalent to liver-derived HD Ag within the limit of the blocking titrations performed. The rHD Ag-positive cell line was also used in an indirect immunofluorescence assay to detect anti-HD. Similar titres of anti-HD were detected by both radioimmunoassay and immunofluorescence and identical samples were positive for anti-HD by either assay. In a sample of prison inmates with high prevalence of both HBV and HDV, anti-HD was confined almost exclusively to those with persistent HBV infection and not to those in whom HBV infection had cleared. The availability of rHD Ag will permit wider development of diagnostic anti-HD assays, and the use of two such assays is presented in this study.
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PMID:Use of recombinant hepatitis delta antigen in diagnostic assays for HDV antibody. 240 47

The immunoglobulin G (IgG) fraction obtained from the serum of a patient (B-10) with type B insulin resistance and acanthosis nigricans stimulated both glucose oxidation in rat adipocytes and autophosphorylation of tyrosine residues in the beta-subunit of insulin receptors in H-35 hepatoma cells. Partially purified insulin receptor from H-35 cells, when incubated with B-10 IgG, had increased tyrosine kinase activity for a synthetic peptide sequentially similar to the site of tyrosine phosphorylation in pp60v-arc (the gene product responsible for cellular transformation by the Rous sarcoma virus). In H-35 cells, both B-10 IgG and insulin stimulated tyrosine phosphorylation in an endogenous 185,000 mol wt protein. This phosphoprotein may be similar to the cellular substrate for insulin in hepatoma and other cultured cell lines demonstrated by others. These results suggest that antiinsulin receptor antibodies (B-10) may initiate their insulin-like effects via tyrosine phosphorylation of the insulin receptor, activation of its tyrosine kinase activity, and phosphorylation of a cellular protein substrate of 185,000 mol wt.
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PMID:Autoantibodies to the insulin receptor (B-10) can stimulate tyrosine phosphorylation of the beta-subunit of the insulin receptor and a 185,000 molecular weight protein in rat hepatoma cells. 246 44

Tumour and proliferative cells maintain a high glycolytic rate even under aerobic conditions. The discovery of fructose-2,6-bisphosphate, a potent stimulator of glycolysis, has prompted a re-investigation of this phenomenon. Rat hepatoma cells and fibroblasts stimulated by mitogens or transformed by the Rous sarcoma virus, were used as models. The results indicate that the stimulation of glycolysis induced by these agents can be explained by an increase in the concentration of fructose-2,6-bisphosphate and in the activity of the enzyme synthesizing it.
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PMID:[Fructose-2,6-diphosphate and glycolysis of tumor cells]. 256 67


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