title: In vitro effects of folic acid on gamma-glutamyltransferase and glutathione reductase activities in malignant lung and thymus tumors.
abstract: In vitro effects of folic acid (10(-5), 10(-4), and 10(-3)M) on activities of gamma-glutamyltransferase and glutathione reductase, the enzymes involved in glutathione metabolism, were studied in tissue samples obtained after surgical treatment of the lungs and thymus. Folic acid did not change gamma-glutamyltransferase activity in lung cancer tissue, but in thymoma tissue this substance in a concentration of 10(-3)M inhibited it by 16%. Folic acid had no effects on glutathione reductase activity in benign tumors and normal lung and thymus tissues, but increased this activity in thymoma and lung cancer tissues. Activation of glutathione reductase was probably related to binding of folic acid in the allosteric center of the enzyme, which probably induced conformational changes in the catalytic center, acceleration of electron transport from NADPH(2) to oxidized glutathione via flavin adenine nucleotide, and intense production of reduced glutathione.
authors.affiliation: A. V. Vishnevskii Institute of Surgery, Russian Academy of Medical Sciences, Moscow.
authors.forename: A A
authors.initials: AA
authors.lastname: Karelin
authors.forename: R N
authors.initials: RN
authors.lastname: Korotkina
authors.forename: G N
authors.initials: GN
authors.lastname: Matskevich
authors.forename: V V
authors.initials: VV
authors.lastname: Borisov
authors.forename: A A
authors.initials: AA
authors.lastname: Vishnevskii
authors.forename: L V
authors.initials: LV
authors.lastname: Polikarpova
authors.forename: A G
authors.initials: AG
authors.lastname: Kunitsyn
mesh_terms: D004305:Dose-Response Relationship, Drug; D005492:Folic Acid / Q000494:pharmacology*; D005980:Glutathione Reductase / Q000187:drug effects* / Q000378:metabolism; D006222:Hamartoma / Q000188:drug therapy / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D012016:Reference Values; D013945:Thymoma / Q000188:drug therapy / Q000201:enzymology; D013953:Thymus Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D014375:Tuberculoma / Q000188:drug therapy / Q000201:enzymology; D005723:gamma-Glutamyltransferase / Q000187:drug effects* / Q000378:metabolism
chemical_list: D005492:Folic Acid; D005980:Glutathione Reductase; D005723:gamma-Glutamyltransferase