title: Increased expression of queuosine synthesizing enzyme, tRNA-guanine transglycosylase, and queuosine levels in tRNA of leukemic cells.
abstract: Queuosine is a modified nucleoside located at the first position of the tRNA anticodon, which is synthesized by tRNA-guanine transglycosylase (TGT). Although the levels of queuosine in cancer cells have been reported to be lower than those in normal cells, the expression levels of TGT remain to be determined. We determined the expression levels of a subunit of TGT (TGT60KD). Contrary of our expectations, the results revealed higher levels of expression of TGT60KD than that in normal cells, and the level of queuosine in the tRNA fraction corresponded with that of TGT60KD expression. These results suggest the possibilities that the expression levels of TGT60KD regulate TGT activity and the levels of queuosine, and that TGT60KD plays significant roles in carcinogenesis. To our knowledge, this is a first report of increased expression levels of TGT60KD in human cancer cells.
authors.affiliation: Department of Pharmaceutical Sciences, Tohoku University Hospital, Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. ishiwata@mail.cc.tohoku.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Ishiwata
authors.forename: J
authors.initials: J
authors.lastname: Katayama
authors.forename: H
authors.initials: H
authors.lastname: Shindo
authors.forename: Y
authors.initials: Y
authors.lastname: Ozawa
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Mizugaki
mesh_terms: D006801:Humans; D007938:Leukemia / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D009704:Nucleoside Q / Q000172:deficiency / Q000378:metabolism*; D010430:Pentosyltransferases / Q000096:biosynthesis*; D014407:Tumor Cells, Cultured
chemical_list: D009704:Nucleoside Q; D010430:Pentosyltransferases; C020837:queuine tRNA-ribosyltransferase