title: Efficient immortalization of primary human cells by p16INK4a-specific short hairpin RNA or Bmi-1, combined with introduction of hTERT.
abstract: Activation of telomerase is sufficient for immortalization of some types of human cells but additional factors may also be essential. It has been proposed that stress imposed by inadequate culture conditions induces senescence due to accumulation of p16(INK4a). Here, we present evidence that many human cell types undergo senescence by activation of the p16(INK4a)/Rb pathway, and that introduction of Bmi-1 can inhibit p16(INK4a) expression and extend the life span of human epithelial cells derived from skin, mammary gland and lung. Introduction of p16(INK4a)-specific short hairpin RNA, as well as Bmi-1, suppressed p16(INK4a) expression in human mammary epithelial cells without promoter methylation, and extended their life span. Subsequent introduction of hTERT, the telomerase catalytic subunit, into cells with low p16(INK4a) levels resulted in efficient immortalization of three cell types without crisis or growth arrest. The majority of the human mammary epithelial cells thus immortalized showed almost normal ploidy as judged by G-banding and spectral karyotyping analysis. Our data suggest that inhibition of p16(INK4a) and introduction of hTERT can immortalize many human cell types with little chromosomal instability.
authors.affiliation: Virology Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuoku 104-0045, Tokyo, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Haga
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Ohno
authors.forename: Takashi
authors.initials: T
authors.lastname: Yugawa
authors.forename: Mako
authors.initials: M
authors.lastname: Narisawa-Saito
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Fujita
authors.forename: Michiie
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Denise A
authors.initials: DA
authors.lastname: Galloway
authors.forename: Tohru
authors.initials: T
authors.lastname: Kiyono
mesh_terms: D002384:Catalysis; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics* / Q000378:metabolism*; D019175:DNA Methylation; D015536:Down-Regulation; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007621:Karyotyping; D015603:Keratinocytes / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D011401:Promoter Regions, Genetic / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism*; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C069077:BMI1 protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1; D019098:Telomerase