title: Identification and functional characterization of the candidate tumor suppressor gene TRIT1 in human lung cancer.
abstract: tRNA-isopentenyltransferase (tRNA-IPT) catalyses the addition of N6-isopentenyladenosine (i6A) on residue 37 of tRNA molecules that bind codons starting with uridine. Post-transcriptional modifications of tRNA molecules have been demonstrated to be essential in maintaining the correct reading frame of the translational machinery, thus improving fidelity and efficiency of protein synthesis. We show here that the human tRNA-isopentenyltransferase (TRIT1) gene encodes a complex pattern of mRNA variants through alternative splicing in both normal and tumor lung tissue and that the nonsense suppressor activity of tRNA-IPT is maintained only in the full-length mRNA isoform, as revealed by gene complementation in yeast. Expression of the full-length transcript was down-regulated 6-14-fold in lung adenocarcinomas as compared to normal lung tissue. A549 lung cancer cells transfected to express the functional TRIT1 gene formed significantly smaller colonies with reduced scattering on the edges and had only limited ability to induce tumors in nude mice. Our findings raise the possibility of TRIT1 as a candidate lung tumor suppressor.
authors.affiliation: Department of Experimental Oncology and Laboratories, Istituto Nazionale Tumori, Via G. Venezian 1, 20133 Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Spinola
authors.forename: Antonella
authors.initials: A
authors.lastname: Galvan
authors.forename: Carmen
authors.initials: C
authors.lastname: Pignatiello
authors.forename: Barbara
authors.initials: B
authors.lastname: Conti
authors.forename: Ugo
authors.initials: U
authors.lastname: Pastorino
authors.forename: Bjorn
authors.initials: B
authors.lastname: Nicander
authors.forename: Rita
authors.initials: R
authors.lastname: Paroni
authors.forename: Tommaso A
authors.initials: TA
authors.lastname: Dragani
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D019881:Aminoacyltransferases / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D015723:Gene Library; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D019656:Loss of Heterozygosity; D008175:Lung Neoplasms / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D012343:RNA, Transfer / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D012343:RNA, Transfer; D019881:Aminoacyltransferases; C019675:tRNA-protein transferase, amino acyl