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)

Evidence is presented that the antitumor agent helenalin, a sesquiterpene lactone, suppresses anaerobic glycolytic enzymes of tumor cells at a number of sites and not exclusively at glycogen synthetase and phosphofructokinase, previously proposed sites for inhibition by alpha-methylene-gamma-lactones. Of the enzymes tested, the sulfhydryl-containing enzyme hexokinase was inhibited the maximum, i.e., 83%, by helenalin treatment, whereas phosphofructokinase and glycogen synthetase were suppressed approximately 45%. Another sulfhydryl-bearing enzyme, aldolase, was decreased approximately 43%. Phosphorylase a was inhibited 65%, glucose-6-phosphatase was inhibited 46%, and succinic dehydrogenase was inhibited 59% by helenalin treatment. Mitochondrial oxidative phosphorylation processes were also significantly depressed in the presence of helenalin in vitro with either succinate or alpha-ketoglutarate as substrates. Thus, a number of enzymes of anaerobic and aerobic carbohydrate metabolism of Ehrlich ascites cells appear to be inhibited by helenalin, which supposedly can alkylate functional groups, e.g., sulfhydryl groups of these enzymes, by a rapid Michael-type addition.
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PMID:Antitumor agents XXVII: Effects of helenalin on anaerobic and aerobic metabolism of Ehrlich ascites cells. 64 68

Under study was the dependence of mammary gland tumors growth on ovarian hormones level in C3H and DD mice. Tumors arising spontaneously were transplanted to 30--40 mice of the same strain, and tumors of the first passage were studied. The experiments were undertaken on ovariectomized and hormone-treated animals; the latter were given estradiol-benzoate and progesterone injections weekly during a month in the dosage of 5 mcg and 400 mcg per animal, respectively. Out of 6 tumors in C3H mice no one responded to ovariectomy or hormone administration by changes in the growth rate. Of 25 tumors in DD mice the transplants of one were found to respond to the ovarian hormones administration by a substantial increase of the growth rate. Only in these tumors a high level of estradiol receptors was noted. It was established that these tumors responded to the estradiol treatment by induction of the hexokinase and glucose-6-phosphatedehydrogenase activities. It is supposed that the changes in the enzymes activity under estradiol treatment in mammary gland tumors are indicative of their hormone-dependence.
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PMID:[Estradiol reception and enzyme induction in mouse mammary gland neoplasms]. 69 20

Hexokinase of the endometrium and gastric mucosa is represented by 5 isoenzymes. The "simplification" of HK isoenzyme spectrum is characteristic of cancer tissue. So, in gastric cancer there is a disappearance of the "slowest" isoenzyme, while in malignant endometrium the "fastest" one was absent. Hexokinase isoenzymes of the serum were identical to those in the tumors in question, that indicates the tumor origin of the body fluid hexokinase. The latter was not observed in normal body fluids. The isoenzymic composition of hexokinase in uterine fibromyoma did not differ from that in normal tissues. If hexokinase appeared in the serum of these patients, its isoenzymic composition was similar to that in the normal uterus. The study on the hexokinase isoenzyme composition may be a valuable adjunct in establishing the differential diagnosis between benign and malignant tumors.
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PMID:[Tumorous origin of the hexokinase in human biological fluids]. 71 18

The ratios of some key enzymatic activities of carbohydrate metabolism have been measured in human tumor cytosols. The activities of whole hexokinase (low Km, EC 2.7.1.1 and high Km, EC 2.7.1.2), 6-phosphogluconate dehydrogenase (EC 1.1.1.43), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and glucose-6-phosphate isomerase (EC 5.3.1.9) change according to a biochemical pattern coherent with cell growth requirements. 6-phosphogluconate dehydrogenase activity was in each sample tested higher than glucose-6-phosphate dehydrogenase activity; this indicates that 6-phosphogluconate, a powerful inhibitor of glucose-6-phosphate isomerase, is unlikely to accumulate and inhibit this enzyme and glucose-6-phosphate channelling into glycolysis.
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PMID:6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, glucose-6-phosphate isomerase, and hexokinase activity ratios in some human tumor cytosols. 74 21

The kinetic properties of hexokinase of L1210 ascites tumor cells propagated in DBA/2HaD mice are altered by treatment of the mice with the modified nucleoside N6-(delta2-isopentenyl)-adensone (IPA). Relative to animals not treated with IPA, ascites cell hexokinase showed an increased affinity for ATP and a decreased affinity for glucose as a result of IPA treatment. The heat stability of the enzyme was different in treated and untreated mice. It was concluded that IPA treatment may either produce changes in enzyme conformation which resulted in a change in control mechanisms or may induce the formation of a hexokinase isoenzyme.
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PMID:Effect of N6-(delta2-isopentenyl)adenosine treatment in vivo on hexokinase activity of mouse L 1210 cells. 105 42

In the hexokinase isoenzyme pattern on the cellulose acetate membrane electropherogram of the supernatant fraction of Ehrlich ascites tumor cells, a band was detected moving slower than of common Type I isoenzyme. This band was assumed to be due to the presence of a variant of the hexokinase isoenzymes in the cells, since such a band was not detected in the normal tissues, and a change in the intensity of the band in response to a sulfhydryl agent, etc., differed from that of the common Type I and II isoenzymes. The band was also found in AH-7974 and MH-134 ascites tumor cells, in spite of the difference in the species of the tumor-bearing animals and originating tissue.
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PMID:A variant of hexokinase isoenzymes detected in ascites tumor cells. 115 3

The mitochondrial-bound hexokinases (adenosine triphosphate:D-hexose 6-phosphotransferase) of mammary adenocarcinoma and of normal gland were compared in lactating C3H mice. Treatment of mitochondria isolated from both the normal and neoplastic tissue with 0.5 m NaCl or 0.1 mM glucose 0-phosphate effected the release of about 50% of the bound hexokinase. In the presence of magnesium ion, enzyme from either source attached to mitochondria from either tissue and in all combinations to the same extent. Identification of the isoenzyme complement in the mitochondrial extract by diethylaminoethylcellulose chromatography revealed only types I and II. In the tumor, the hexokinase activity in both the cytosol and the fraction solubilized from mitochondria was predominantly in the form of type I ( 60%). In contrast, the activity released from mitochondria isolated from normal gland was predominately type II, while the cytosol contained almost equivalent amounts of types I and II. While this difference does not explain differences in glucose utilization between the normal and neoplastic tissue, it may provide a means of distinguishing between the two.
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PMID:Identity, release, and binding of mitochondrial-bound hexokinases in mammary glands and adenocarcinomas of lactating mice. 116 11

In a model system consisting of highly coupled rat liver mitochondria respiring in the presence of substrate, pyruvate kinase, phosphoenolpyruvate, ATP, hexokinase and glucose, the increase in the mitochondrial concentration results in a progressive decrease in the activity of pyruvate kinase. These results are in accord with a role of pyruvate kinase as a determinant of glycolytic activity by competing with mitochondrial oxidative phosphorylation for the available ADP. The addition of adequate amounts of the amino acids, cysteine, alanine and phenylalanine, known as inhibitors of pyruvate kinase, to living Ehrlich ascites tumor cell suspensions results in a stimulation of the respiratory rate and in a decrease of the glycolytic rate of the cells. Concomitant with these changes, there is an accumulation of intracellular phosphoenolpyruvate and ADP, and a decrease in pyruvate and ATP. These results provide additional evidence for paying attention to pyruvate kinase as another key enzyme whose properties and activities may be major determinants for the control of glycolysis and the Crabtree and Pasteur effects of tumor cells.
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PMID:Stimulation of tumor-cell respiration by inhibitors of pyruvate kinase. 117 5

In sarcoma M-I the hexokinase activity was found to exceed three-fold the enzyme activity in muscular tissue. In the muscles and tumor intracellular distribution of hexokinase was essentially the same; the main part of the enzyme was localized in hyaloplasma. The mitochondrial hexokinase from sarcoma M-I was solubilized by considerably higher concentrations of KC1 (0.5 M), as compared with those required for the solubilization of the enzyme from muscular tissue (0.05 M). Studies of electrophoretic, kinetic properties and thermolability of the tumor enzyme demonstrated that only two hexokinase isoenzymes were found in sarcoma M-I hyaloplasm as compared with muscular tissue where isoenzymes I, II and IV were observed.
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PMID:[Subcellular localization, isoenzyme spectrum and properties of hexokinase from sarcoma M-1]. 121 75

The activity of 19 enzymes (hexokinase, glucoso-6-phosphatisomerase, alpha-glycerophosphate-, lactate-, succinate-, isocitrate-, malate-, glucoso-6-phosphate-, 6-phosphogluconate-, glutamate-, alcohol-, inosine-5'-phosphate-, guanosine-5'-monophosphate-dehydrogenase, cytochromoxidase NAD.N2- and NADP.N2-diaphorase, monoaminoxidase, alkaline and acid phosphatase) was studied comparatively in the mucosa of control rats and in tumors of the small intestine (27), and large intestine (176), induced in 41 rats percutaneously by 1,2-dimethylhydrazine. A decreased level of the enzymes of tissue respiration and Krebs cycle was found with a simultaneous increase in the activity of the enzymes of glycolysis and pentoso-monophosphate shunt. These data evidence variations in tumor metabolism consisting in oxidizing phosphorylation, being replaced by aerobic glycosis, and also reflecting an intensive proliferation of tumor cells.
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PMID:[An enzymohistochemical study of experimental tumors of the intestine]. 123 60


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