title: Overexpression of telomerase confers a survival advantage through suppression of TRF1 gene expression while maintaining differentiation characteristics in K562 cells.
abstract: Leukemic stem cells that expressed endogenous telomerase activity were induced to show overexpression of exogenous hTERT and were analyzed for biological changes in order to assess the possible influence of telomerase gene therapy on the transplantation of normal hematopoietic stem cells. Introduction of hTERT into K562, a telomerase-positive immortal cell line, resulted in a 2.5-fold elevation of telomerase activity and the lengthening of telomeres by 6 kb to 23 kb. Real-time fluorescent PCR, which could perform quantitative analysis of transcripts, revealed a 175-fold increase in hTERT expression, suggesting the posttranscriptional regulation of telomerase. Ectopic expression of hTERT in K562 cells showed a survival advantage during culture in the absence of serum. Expression of mRNA for the telomeric-repeat binding factor 1 (TRF1) and caspase-3 activity were both decreased in hTERT-transfected K562 cells. Transduced cells retained their usual phenotypic characteristics, differentiation ability, and signal transduction response to TPA. These data suggest that ectopic expression of hTERT by normal hematopoietic stem cells may confer a survival advantage without changing their innate biological characteristics.
authors.affiliation: Medical Research Institute and Department of Hematology, Tokyo Women's Medical University, Japan. yamadao@lab.twmu.ac.jp
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamada
authors.forename: Masaharu
authors.initials: M
authors.lastname: Akiyama
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Kawauchi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Adachi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Yamada
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Kanda
authors.forename: Eizo
authors.initials: E
authors.lastname: Aikawa
mesh_terms: D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D002470:Cell Survival / Q000235:genetics; D016922:Cellular Senescence / Q000235:genetics; D004268:DNA-Binding Proteins; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020014:K562 Cells; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013489:Suppression, Genetic / Q000235:genetics; D019098:Telomerase / Q000235:genetics* / Q000627:therapeutic use; D016615:Telomere / Q000235:genetics*; D035321:Telomeric Repeat Binding Protein 1 / Q000235:genetics*; D014161:Transduction, Genetic / Q000379:methods; D015854:Up-Regulation / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D011725:Pyridines; D012333:RNA, Messenger; D035321:Telomeric Repeat Binding Protein 1; C431843:tris(2-pyridylmethyl)amine; D019098:Telomerase; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases