Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The glycerol portion of lipids may be derived biosynthetically by reduction of dihydroxyacetone phosphate to glycerolphosphate, and then be acylated with fatty acids or, alternatively, dihydroxyacetone phosphate may first be acylated and then reduced to 1-acyl sn glcerol-3-phosphate. Since the former pathway utilizes NADH for reduction of the C-2 carbonyl, while the latter requires NADPH, we were able to compare the relative participation of the two pathways for phospholipid synthesis by measuring the incorporation of radioactivity from tritiumlabeled NADH and NADPH into C-2 of lipid glycerol. The acyl-dihydroxyacetone phosphate pathway plays a significant role in glycerolipid synthesis in mouse liver homogenates and a clearly dominant one in Ehrlich ascites tumor cell homogenates. This finding is related to a reported lack of glycerol-3-phosphate dehydrogenase in tumor cells and to their high glycerol ether lipid content.
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PMID:The acyl dihydroxyacetone phosphate pathway for glycerolipid biosynthesis in mouse liver and Ehrlich ascites tumor cells. 527 94

The enzyme pattern of 13 cases of malignant fibrous histiocytoma (MFH) and 11 cases of myxofibrosarcoma (MFS), a malignant myxomatous soft tissue tumor of fibroblastic histiocytic origin, has been studied. 6 of the 13 MFHs were analyzed enzyme histochemically at the light microscopic level and 7 on the ultrastructural level; of the 11 MFSs 9 were analyzed enzyme histochemically at the light microscopic level and 2 on the ultrastructural level. Differences were observed in the subjectively estimated enzyme activity between low grade MFS and high grade MFS and MFH, and also between histiocyte-like and fibroblast-like tumor cells. Generally a strong reaction of oxidoreductase enzymes (NADH2-diaphorase, NADPH2-diaphorase, glucose-6-phosphate dehydrogenase) and hydrolytic enzymes (acid phosphatase and leucine aminopeptidase) was found in the high grade tumors and was usually higher in the histiocyte-like than in the fibroblast-like cells. Ultrastructurally acid phosphatase occurred predominantly in primary and secondary lysosomes and Golgi zones of the histiocyte-like cells. A strong reaction of alkaline phosphatase was found light microscopically in 2 of 5 MFHs and 5 of 9 MFSs. Ultrastructurally alkaline phosphatase was located along the cytoplasmic membrane of predominantly fibroblast-like cells in 3 of 7 MFHs and 1 of 2 MFSs. The results agree with the concept of two main cell types in MFH and MFS, fibroblasts and histiocytes.
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PMID:Enzyme histochemistry of malignant fibroblastic histiocytic tumors. A light and electron microscopic analysis. 608 56

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) influences neither the State 3 nor the State 4 respiration in rat liver mitochondria. The respiratory control and ADP/O ratio were also unaffected by TPA. The oligomycin-sensitive ATPase activity in submitochondrial particles remained unaltered upon TPA addition, whereas the NADH oxidase activity was slightly inhibited at a very high concentration of TPA (15% decrease at 17 microM TPA). The activity of the superoxide dismutase located to the mitochondria was insensitive to the tumor promoter, and no change in the rate of H2O2 production was found on TPA treatment in vitro. Thus, the mitochondrion is not a likely candidate for the site of action of the tumor promoter.
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PMID:Oxygen uptake, ATPase activity, and superoxide dismutase activity in isolated rat liver mitochondria are not influenced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. 622 26

As has been previously reported an increased intensity of light-induced green fluorescence is observed for some tumor cells. The present paper deals with the cause of this phenomenon, employing for this hepatoma cells of line HTC acted upon with 2,4-DNP, amytal and malonate. It has been shown that the light-induced increase in green fluorescence in cells is due to the oxidation of NADH-dehydrogenase, a mitochondrial flavine-containing enzyme, occurring at the time of fluorescence induction. The increased intensity of green fluorescence of flavoproteins in tumor cells is associated with an infringement in oxidation of NAD-dependent substrates in these, and with the activation of the reverse electron transport in the oxidative chain. The exciding light activates NADH-dehydrogenase and accelerates the translocation of reduced equivalents from this enzyme, which results in its oxidation, and thus--in the observed effect of increased intensity of green fluorescence.
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PMID:[Inhibitory analysis of the functions of the oxidative metabolic systems of tumor cells in tissue culture]. 647 74

The stereospecificity of octopine dehydrogenase from crown gall tumor and of octopine dehydrogenase from scallops (Pecten maximum) with respect to the oxidation of C-4 of the dihydronicotinamide ring of NADH was investigated by determination of the distribution of radioactivity after oxidation of (4R)- and (4S)-[4-3H]NADH. Octopine dehydrogenase from crown gall tumor and from scallops stereospecifically removes the pro-S hydrogen atom of the dihydronicotinamide ring with transfer of label to the solvent and to the product octopine (N-2-(1-carboxyethyl)-L-arginine). Although to a lesser extent, the exchange of label from (4S)-[4-3H]NADH with solvent was found to occur when octopine dehydrogenase from either crown gall tumor or from scallops was incubated in the absence of other substrates. Possible mechanisms to explain this exchange are discussed.
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PMID:Octopine dehydrogenase from crown gall tumor and from Pecten maximus. Oxidation of (4R)- and (4S)-[4-3H]NADH. 709 44

It has been shown that in the absence of inhibitors of oxidative phosphorylation, changes in fluorescence of 3',3'-diethylthiodicarbocyanine iodide (dis-C2-/5/) in a cell suspension of Ehrlich's ascites carcinoma reflect those in the transmembrane mitochondrial potential. Addition of glucose to the cells in the presence of respiratory inhibitors similar to rotenon induces oscillations in the membrane mitochondrial potential due to H+-ATPase that uses glycolytic ATP. The described changes in energy metabolism parameters are determined by impairment of the interplay between glycolysis and oxidative phosphorylation. The low rate of cytoplasmic NADH oxidation by tumor cell mitochondria favors the latter's accumulation by the cytoplasm and glycolysis inhibition. Pyruvate has been shown to be responsible for NADH oxidation and to remove glycolysis inhibition.
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PMID:[Kinetics of oxygen consumption, luminescence of pyridine nucleotides and the cyanine dye 3',3'-diethylthiodicarbocyanine iodide after energizing Ehrlich ascites carcinoma cells with glucose]. 715 Jul 43

5'-AMP antigens were synthesized by conjugation of N6-carboxymethyl-5'-AMP (Cm65'-AMP) to native or methylated serum albumin. Injection of the antigens resulted in antibodies with high affinity and specificity for 5'-AMP in all animals, thus allowing discrimination against 3'(2')-AMP even when present at 10(4)-10(5) times higher concentrations. This specificity was comparable to that of anti 5'-AMP antibodies raised against Cm65'-AMP serum albumin antigens formed in situ from Cm6ADP-ribose serum albumin conjugates by intracellular or pericellular phosphodiesterases. The hapten in the Cm65'-AMP-methylated serum albumin conjugate appeared to be bound almost exclusively via the N6-position. Due to the free exposure of the 5'-phosphate group in this antigen, the resulting antibodies discriminated 5'-AMP derivatives substituted at the phosphate group more efficiently than derivatives with modifications in the adenine ring. It also led to the concomitant formation of adenosine-specific antibodies due presumably to dephosphorylation of the antigen by phosphatases present in the recipient animals. The conjugates formed from Cm65'-AMP and native serum albumin, which appeared to be linked to a large extent via carboxyl groups of the protein and hydroxyl groups of the ribose, recognized modifications in the adenine ring much better than substitutions at the phosphate group. However, in spite of these relatively small differences in specificity, all three types of antibodies could be used successfully to quantitate by radioimmunoassay protein-bound ADP-ribose in adult rat liver and NAD+-NADH in Ehrlich ascites tumor cells as shown by the excellent agreement of the values obtained with the three antisera.
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PMID:Determination of 5-AMP in the presence of excess 3'(2')-AMP with the aid of antibodies raised against n6-carboxymethyl-5'-AMP conjugates. Use for the quantitation of pyridine nucleotides and of protein-bound ADP-ribose. 721 30

Enhanced lipid peroxidation potential was measured in Holtzman rat colon tumors induced by chronic subcutaneous injection of 1,2-dimethyl-hydrazine as compared with normal colonic tissue. The peroxidation potentials were determined in the mitochondrial cellular components by measuring the ferrous-ascorbate induced formation of malondialdehyde. The tumor mitochondria were found to peroxidize at a rate 8-10-fold higher than the comparable normal tissue components. In addition, we found that the mitochondria from the cancer cells exhibited reduced NADH-cytochrome c reductase activity. These observations suggest an involvement of non-enzymatic free radical flux in DMH-induced carcinogenesis, which may be the result of structurally altered mitochondrial membranes.
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PMID:Evidence for a defective mitochondrial membrane in 1,2-dimethylhydrazine-induced colon adenocarcinoma in rat: enhanced lipid peroxidation potential in vitro. 722 56

A NADH-ferricyanide reductase of the external surface of intact mouse ascites tumor cells grown in culture was shown. The oxidation/reduction reaction was due to enzymatic rather than inorganic iron catalysis as demonstrated by the kinetics and specificity of the reaction. Activities of three markers for cytoplasmic contents were lacking with the intact tumor cells. The dehydrogenase activity was inhibited by p-chloromercuribenzoate, bathophenanthroline sulfonate, and the anticancer drug adriamycin. Sodium azide and potassium cyanide inhibited partially. The response to inhibitors resembled that of isolated plasma membranes rather than that of mitochondria. Concurrent with these findings, neither superoxide dismutase nor rotenone affected the redox activity. The findings provide evidence for the operation of a plasma membrane redox system at the surface of intact, living cells.
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PMID:Evidence for a plasma membrane redox system on intact ascites tumor cells with different metastatic capacity. 747 Apr 94

Plasma membrane vesicles from HeLa S cells grown in culture bound with high affinity the antitumor sulfonylurea N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)urea (LY181984). Based on binding site protection experiments with the radiolabeled thiol reagent N-[14C]ethylmaleimide, a ca. 34 kDa binding protein was identified. By analogy with a 36 kDa NADH oxidase from plant plasma membranes where activity was blocked by a growth-inhibitory herbicidal sulfonylurea, the sulfonylurea-binding protein of the HeLa plasma membranes has now been identified as a comparable sulfonylurea-inhibited NADH oxidase activity. The drug inhibited half maximally at about 50 nM which corresponded closely to the Kd for binding of [3H]LY181984 of 25 nM. A closely related but growth-inactive sulfonylurea N-(4-methylphenylsulfonyl)-N'-(phenyl)urea (LY181985) inhibited the activity only weakly. The inhibition by LY181984 was analyzed kinetically and shown to be noncompetitive or uncompetitive depending on the concentration of NADH. With sealed right-side out plasma membrane vesicles, the NADH oxidase activity was about 90% inhibited by 1 microM LY181984. With frozen and thawed plasma membrane vesicles or with vesicles first solubilized with 1% Triton X-100, activity also was inhibited by LY181984 and not by LY181985 but the maximum inhibition at 10 microM LY181984 was about 50%. With plasma membranes from rat liver, neither LY181984 nor LY181985 affected the NADH oxidase even in the presence of detergent. Thus, selective inhibition or stimulation of the oxidation of NADH of tumor plasma membranes by the antitumor sulfonylurea LY181984 may be related to its antitumor activity.
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PMID:The antitumor sulfonylurea N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl) urea (LY181984) inhibits NADH oxidase activity of HeLa plasma membranes. 749 42


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