title: Cellular thioredoxin reductase activity is regulated by selenium.
abstract: Selenium (Se) is an essential trace element and has been reported to decrease the incidence of some human cancers. We have investigated the effects of Se on thioredoxin reductase, a selenocysteine containing flavoenzyme, in HT-29 human colon cancer cells grown in serum-free medium. Sodium selenite and other Se containing compounds produced a time and concentration dependent increase in intracellular thioredoxin reductase activity and protein levels. Selenite was the most active of the Se compounds examined: 1 microM selenite produced a 28-fold increase in thioredoxin reductase activity by 1 day and 10 microM selenite over a 60-fold increase by 5 days. The activity of a related non-selenocysteine containing flavoenzyme glutathione reductase was not increased by selenite. Selenite, but not the other Se containing compounds inhibited cell growth at concentrations above 2 microM. The results show that Se can produce large increases in cell thioredoxin reductase activity.
authors.affiliation: Arizona Cancer Center, University of Arizona Health Sciences Center, Tucson 85724-5024, USA.
authors.forename: M
authors.initials: M
authors.lastname: Berggren
authors.forename: A
authors.initials: A
authors.lastname: Gallegos
authors.forename: J
authors.initials: J
authors.lastname: Gasdaska
authors.forename: G
authors.initials: G
authors.lastname: Powis
mesh_terms: D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects; D003110:Colonic Neoplasms / Q000201:enzymology; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D016566:Organoselenium Compounds / Q000378:metabolism; D012643:Selenium / Q000502:physiology*; D017279:Selenocysteine / Q000031:analogs & derivatives; D012645:Selenomethionine / Q000378:metabolism; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000201:enzymology
chemical_list: D016566:Organoselenium Compounds; D017279:Selenocysteine; D012645:Selenomethionine; D013880:Thioredoxin-Disulfide Reductase; D012643:Selenium; D003545:Cysteine; C002979:selenomethylselenocysteine