title: gamma-Glutamyl transpeptidase overexpression increases metastatic growth of B16 melanoma cells in the mouse liver.
abstract: B16 melanoma (B16M) cells with high glutathione (GSH) content show rapid proliferation in vitro and high metastatic activity in the liver in vivo. gamma-Glutamyl transpeptidase (GGT)-mediated extracellular GSH cleavage and intracellular GSH synthesis were studied in vitro in B16M cells with high (F10) and low (F1) metastatic potential. GGT activity was modified by transfection with the human GGT gene (B16MF1/Tet-GGT cells) or by acivicin-induced inhibition. B16MF1/Tet-GGT and B16MF10 cells exhibited higher GSH content (35 +/- 6 and 40 +/- 5 nmol/10(6) cells, respectively) and GGT activity (89 +/- 9 and 37 +/- 7 mU/10(6) cells, respectively) as compared (P <.05) with B16MF1 cells (10 +/- 3 nmol GSH and 4 mU GGT/10(6) cells). Metastasis (number of foci/100 mm(3) of liver) increased in B16MF1 cells pretreated with GSH ester ( approximately 3-fold, P <.01), and decreased in B16MF1/Tet-GGT and B16MF10 cells pretreated with the GSH synthesis inhibitor L-buthionine (S,R)-sulphoximine ( approximately 5-fold and 2-fold, respectively, P <.01). Liver, kidney, brain, lung, and erythrocyte GSH content in B16MF1/Tet-GGT- or B16MF10-bearing mice decreased as compared with B16MF1- and non-tumor-bearing mice. Organic anion transporting polypeptide 1-independent sinusoidal GSH efflux from hepatocytes increased in B16MF1/Tet-GGT- or B16MF10-bearing mice ( approximately 2-fold, P <.01) as compared with non-tumor-bearing mice. Our results indicate that tumor GGT activity and an intertissue flow of GSH can regulate GSH content of melanoma cells and their metastatic growth in the liver.
authors.affiliation: Department of Physiology, University of Valencia, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Obrador
authors.forename: Julian
authors.initials: J
authors.lastname: Carretero
authors.forename: Angel
authors.initials: A
authors.lastname: Ortega
authors.forename: Ignacio
authors.initials: I
authors.lastname: Medina
authors.forename: Vicente
authors.initials: V
authors.lastname: Rodilla
authors.forename: José A
authors.initials: JA
authors.lastname: Pellicer
authors.forename: José M
authors.initials: JM
authors.lastname: Estrela
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002455:Cell Division; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism; D015870:Gene Expression; D005978:Glutathione / Q000037:antagonists & inhibitors / Q000378:metabolism; D022781:Hepatocytes / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000201:enzymology* / Q000473:pathology / Q000556:secondary*; D008168:Lung / Q000378:metabolism; D008297:Male; D008546:Melanoma, Experimental / Q000201:enzymology* / Q000473:pathology / Q000556:secondary; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D014162:Transfection; D014407:Tumor Cells, Cultured; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D007555:Isoxazoles; D019328:Buthionine Sulfoximine; D005723:gamma-Glutamyltransferase; D005978:Glutathione; C006303:acivicin