Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human neuroblastoma SK-N-SH-SY5Y (5Y) and rat glioma (C6) cells were cultured with supplemental methionine, glycine, or serine for three to six days. Serine hydroxmethyltransferase (SHMT: L-serine: tetrahydrofolate 5, 10-hydroxymethyltransferase, EC 2.12.1) was assayed radiometrically in whole cell homogenates, crude supernatant fractions and crude particulate fractions. No significant changes in specific activity or cellular morphology were noted at methionine, glycine, or serine concentrations up to 16 mM. Serine concentrations of 20 and 40 mM led to significantly lower gliomal enzyme specific activities. This activity was unevenly distributed between soluble and particulate fractions, with 190 and 398 nmoles of HCHO formed per mg of protein per hour, respectively. Growth stage and time of incubation were major determinants of enzyme specific activity. C6 cells' specific activity rose slowly with increasing time in culture until cellular confluence. At this time there was a pronounced elevation in specific activity, occurring more rapidly in cells grown in 1.2 mM methionine. Intracellular amino acid analysis of C6 cells demonstrated a significant rise in methionine after four days in media containing 0.2 mM methionine. No appreciable diminution in the intracellular levels of glycine or serine occurred following incubation in excess methionine. It is concluded that SHMT-specific activity in C6 and 5Y cells is not regulated by glycine, serine, or methionine levels and that high concentrations of these amino acids (> 30 mM) are not detrimental to these cells derived from the CNS.
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PMID:Effect of methionine, glycine and serine on serine hydroxymethyltransferase activity in rat glioma and human neuroblastoma cells. 677 88

The activity of the enzymes 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase has been studied cytochemically in children's primary brain tumors. These enzymes play a significant role in purine biosynthesis. Thirty children, aged 1-12 years, were studied, 12 with medulloblastoma, 14 with glioma grade I-IV, and 4 with ependymoma. The activity of the enzymes was apparent as cytoplasmic granules that sometimes overlie the nucleus of the tumor cells. This coincidence showed that different types of brain tumors exhibit different degrees of enzymic activity, which in some cases correlated positively with the malignant potential of the tumor. Approximately one third of the cases were negative for any activity of these enzymes. The intensity of the staining of 5,10-methenyl tetrahydrofolate cyclohydrolase activity was actually higher than that of 5-formyl tetrahydrofolate cyctodehydrase. The clinical or prognostic significance of these findings remains to be clarified, but we believe that cylochemistry provides a sensitive technique for the detection, localization, and description of these enzymes in brain tumor cells. A clear understanding of the mode of action of these enzymes may contribute to devising novel therapeutic strategies.
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PMID:Activity of 5-formyl tetrahydrofolate cyclodehydrase and 5,10-methenyl tetrahydrofolate cyclohydrolase in primary brain tumors in children. 894 Jul 34

The uptake of 125-iodine labeled 3' iodofolic acid (I*F) and 3' iodo, 5 formyl tetrahydrofolic acid (I*FT) by the cells HeLa, ECV, L-41, human glioma, and rat glioma was studied. Human Embrionic Lung Fibroblasts (HELF) were taken for comparison as healthy cells. It was shown for *IF that its long-term uptake by cells L-41 and ECV is hundreds oftimes higher than those of HELF cells. The short-term uptake phase was studied for *IFT uptake. The dissociation constant was determined for a complex formed by *IFT and an acceptor in the HeLa cells, which is supposed to cause concentrative uptake of *IFT in cells. The dissociation constants of this acceptor complexes with folic acid, 3' iodofolic acid and 3',5'-diiodofolic acid were determined by competition with I*FT. The distribution ratio of *IF and *IFT in tissues of different organs of healthy mice and rats and rats with a sarcoma grafted on his thigh and glioma grafted into the brain was studied. As was shown there are large differences in the concentration of *IF and *IFT in the tumor and in the healthy tissue, *IF concentration in thigh muscle of healthy being 5 times lower than those in tumor grafted to the thigh, and *IFT concentration in healthy brain being 10 times lower than in brain tumor.
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PMID:[Absorption of iodofolic acids by the cells of malignant tumors]. 2354 77