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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Experimental evidence for the presence and biosynthesis of subviral, leukemogenic particles in the isolated mitochondria of spleen cells of mice infected with Rauscher murine leukemia (RML) virus is presented. These subviral particles sediment at a density of 1.27-1.29 g/ml and induce splenomegaly and RML three weeks after i.v. or i.p. administration to white mice. Virosomes have been labelled with [32P]phosphate in the isolated mitochondria from RML spleen cells and high molecular weight (70S) [32P]RNA has been isolated from these subviral, leukemogenic particles. Rauscher virus group specific antigens were detected by immunodiffusion in the inner membrane and matrix fraction of the mitochondria of RML spleen cells. These results together with our earlier findings strongly suggest that mitochondria of the transformed cells participate in the biosynthesis of RNA tumor viruses. Possible mechanism of the penetration of viral genetic information of RNA tumor viruses into mitochondria of tumor cells in vivo is discussed.
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PMID:Biosynthesis of subviral oncogenic particles (virosomes) in mitochondria of Rous sarcoma and Rauscher murine leukemia cells. 19 96

The action of free fatty acids on glycolytic enzymes was compared in normal and neoplastic tissues. Preincubation of tissue supernatant fractions with octanoate or laurate caused an inhibition of the activities of hexokinase and phosphofructokinase. An inhibition was also observed of lactate production with either glucose or glucose 6-phosphate as substrate. A similar degree of inhibition was observed for actions on normal liver and kidney, on the 7800 and 3924-A hepatomas and on the MK-3 renal cortical tumor. The possible relationship between the inhibition of glycolytic enzymes by fatty acids and anti-tumor activity previously observed with these compounds was noted.
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PMID:Inhibition of glycolytic enzymes of rat liver and hepatomas by free fatty acids. 19 94

Second-passage Japanese quail embryo cell cultures, normal or quantitatively transformed by Rous sarcoma virus, were investigated for phospholipid composition and metabolism. Cells cultivated at low and high population density as well as in the presence or absence of serum, have been compared by chemical analysis and in pulse-chase experiments. No differences in the lipid compositions between the normal and the tumor cells or between cells under different culture conditions were detected. In no case was the metabolism of phosphatidylserine or sphingomyelin affected by culture conditions. The metabolism of the choline and ethanolamine glycerophospholipids, however, differed according to culture conditions, whether cells were normal or transformed. Significantly, in normal cells, the breakdown of [32P]phosphate-labeled phosphatidylinositol was slowed when cell growth was restricted, i.e., at high population density or in medium without serum. This effect was not observed in tumor cells under such culture conditions, and cells were not growth inhibited. Hence, release of [32P]phosphate from phosphatidylinositol is the only parameter in the metabolism of phospholipids observed to correlate with growth.
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PMID:Changes in phosphatidylinositol metabolism correlated to growth state of normal and Rous sarcoma virus-transformed Japanese quail cells. 19 14

Previous studies with isolated adrenocortical carcinoma 494 cells from this laboratory have indicated that the lack of cyclic adenosine 3':5'-monophosphate (cyclic AMP) control in steroidogenesis in the tumor may be due to the defective cyclic AMP-dependent protein kinase enzyme system. This paper describes the partial purification of such an enzyme. Purification was achieved by precipitation of the tumor homogenate with 30 and 45% ammonium sulfate, adsorption on 3% calcium phosphate gel, and chromatography on DEAE-cellulose. Four major protein peaks were isolated. Peak 2 showed cyclic AMP-binding activity and was investigated further for its kinetic properties. In contrast to the cyclic AMP-dependent protein kinase enzyme found in the normal adrenal gland, the enzyme specifically bound cyclic AMP but failed to phosphorylate exogenous histone. It is postulated that lack of the cyclic nucleotide-dependent kinase activity of the protein kinase enzyme may be responsible for the loss of cyclic AMP-regulated corticosterone synthesis in adrenocortical carcinoma cell. It is further shown that the tumor cyclic AMP-binding enzyme undergoes endogenous phosphorylation, which indicates that it has kinase activity but it is independent of cyclic AMP.
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PMID:Partial purification and characterization of the defective cyclic adenosine 3':5'-monophosphate binding protein kinase from adrenocortical carcinoma. 19 24

A tumorigenic anchorage-dependent cell line (H-91) was established in culture from an azo-dye-induced rat ascites hepatoma. When grown in a glucose-containing medium the cells exhibit high rates of lactic acid production characteristic of rapidly growing tumor cells. However, when glucose is replaced with galactose the cells grow equally well but exhibit only moderately elevated rates of lactic acid production. The molecular basis for this observation cannot be attributed to differences in permeability because initial rates of glucose and galactose entry into hepatoma cells are identical. Rather, the activity of hexokinase (ATP:D-hexose 6-phosphotransferase, EC 2.7.1.1) is found to be high in hepatoma cells, about 20-fold higher than that of control and regenerating rat liver. Moreover, tumor hexokinase activity is not inhibited by low concentrations (<0.6 mM) of the reaction product glucose 6-phosphate. Additionally, 50% of the hexokinase activity of hepatoma cells is found associated with the mitochondrial fraction. This fraction is 3-fold enriched in hexokinase activity relative to the homogenate and 4-fold enriched relative to the nuclear and postmitochondrial fractions. Tumor mitochondrial hexokinase appears to be coupled directly to oxidative phosphorylation, because addition of glucose to respiring hepatoma mitochondria (after a burst of ATP synthesis) results in stimulation of respiration. In contrast, glucose has no effect on the respiration of mitochondria from control and regenerating liver. These results suggest that the high glycolytic capacity of H-91 hepatoma cells is due, at least in part, to an elevated form of hexokinase concentrated in the mitochondrial fraction of the cell.
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PMID:High aerobic glycolysis of rat hepatoma cells in culture: role of mitochondrial hexokinase. 19 1

In experiments in vitro on ascites tumor cells of Ehrlich carcinoma and Zajdela hepatoma the author studied the effect of 2,4-dinitrophenol (an agent dissociating respiration from phosphorylation) on respiration, glycolysis, resynthesis of ATP and synthesis of basic fractions of cytoplasmic RNA by the incorporation of labeled 3N-uridine precursor. It was shown that under optimum conditions of tumor cell incubation (phosphate-rich Igle medium) in the presence of 6.10(-4) M DNP a sharp activation of anaerobic glycosis is observed as well as increased O2 absorption and high level of ATP. Blocked phosphorylation associated with respiration renders no appreciable effect on the biosynthesis of basic fractions (4 S, 18 S, 28 S) of cytoplasmic RNA.
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PMID:[RNA biosynthesis in the ascitic cells of Ehrlich's carcinoma and Zajdela's hepatoma under conditions of blocked oxidative phosphorylation]. 19 51

In two media (krebsringer phosphate and phosphate-enriched Eagle medium) the indices of energetic metabolism (respiration, glycolysis. ATP content) were determined and the metabolism of macromolecular compounds (c-RNA) of Ehrlich carcinoma ascitic cells was investigated. The results of studies of ascites tumor cells metabolism have indicated considerable advantages of phosphate-enriched Eagle medium over krebs ringer phosphate buffer.
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PMID:[Advantages of the Eagle medium over saline solutions in the studies of the metabolic parameters of tumor cells in vitro]. 20 8

Myoinositol and its phosphorylated derivatives have been quantitatively determined in normal and Rous-sarcoma-virus-transformed quail cells under various growth conditions using [2-(3)H]myoinositol at isotope equilibrium conditions. The following amounts were determined (nmol/mumol phospholipid, as a unit of cell mass): exponentially growing normal and tumor cells contained 25--40 nmol free inositol, 0.40--0.45 nmol myoinositol 1-phosphate, 0.30--0.50 nmol glycerylphosphoinositol, and 0.03--0.04 nmol myoinositol cyclic 1 : 2-phosphate. At high cell populations in the absence of serum, conditions which result in cessation of growth by normal but not by tumor cells, changed levels were found for glycerylphosphoinositol and free inositol. In tumor cells the levels of these two compounds increased to 0.64 nmol and 64 nmol, respectively. In normal cells glycerylphosphoinositol increased to 0.95 nmol and free inositol showed highly elevated levels of 144 nmol. At short pulses the specific activities of inositol 1-phosphate and inositol cyclic 1 : 2-phosphate were found to be higher than that of phosphatidylinositol. This was not the case for glycerylphosphoinositol.
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PMID:Quantitative determination of myoinositol, inositol 1-phosphate, inositol cyclic 1 : 2-phosphate and glycerylphosphoinositol in normal and Rous-sarcoma-virus-transformed quail fibroblasts under different growth conditions. 20 62

Carcinoembryonic antigen (CEA) was isolated from a human tumor with 0.02 M sodium phosphate containing 0.14 M NaCl (pH 7.0) (saline) and further studied after treatment with perchloric acid or 8 M urea. Preparations CEA obtained from saline homogenates and both methods of treatment were characterized by isoelectric focusing and gel filtration. Perchloric acid treatment resulted in an approximate 10-fold decrease in protein and a significant loss of CEA as compared to the saline- and urea-treated material. Isoelectric focusing revealed that the resultant CEA subpopulations were dependent upon the method of isolation. Urea- and saline-treated material showed complex isoelectric patterns that were quantitatively dissimilar. Perchloric acid-treated material showed a comparatively simple isoelectric pattern that was not significantly affected by electrofocusing in the presence of urea. Gel filtration on ACA 34 of the CEA obtained from each method of isolation resulted in two peaks of activity. The first peak corresponded to the void volume of the column, and the second peak coeluted with commercially available purified 125I-labeled CEA. Centrifugation of the peaks obtained resulted in a significantly greater loss of CEA from the void peak of each isolation procedure. The amount of CEA lost from the void peaks following centrifugation differed with each method of isolation and suggested the presence of aggregates.
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PMID:A comparison of methods for the isolation of carcinoembryonic antigen. 20 87

Four cases of non-calcifying soft tissue malignant fibrous histiocytoma are presented which showed concentration of 99mTc-methylene diphosphonate. Angiography was performed in one of the patients and it featured hypervascularity, tumor staining and early draining veins indicative of arteriovenous shunting. As with other extraskeletal non-calcifying entities which exhibit enhanced uptake of 99mTc-phosphate complex, the mechanism of concentration is largely conjectural. Malignant fibrous histiocytoma can be added to the expanding list of conditions which may portray in avidity for 99mTc-phosphate complex.
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PMID:99MTc-metyhlene diphosphonate concentration in soft tissue malignant fibrous histiocytoma. 20 81


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