title: Senescence-associated genes in normal human oral keratinocytes.
abstract: The current study was undertaken to identify senescence-associated (SA) genes in cultured normal human oral keratinocytes (NHOK). Primary NHOK were serially subcultured in vitro as dispersed cells in low (0.15 mM) Ca(2+) medium until senescence. The SA genes of NHOK were identified by comparing the expression levels of 3195 human genes between exponentially replicating and senescing cultures. Approximately 5% of the screened genes were upregulated in senescing NHOK by a factor greater than 3 compared with rapidly dividing NHOK culture. Among them, we identified discrete gene groups, i.e., cyclin-dependent kinase inhibitors, G-protein-coupled receptors, apolipoproteins, matrix metalloproteinases, and mitochondrial proteins. To validate the microarray results, we confirmed the enhanced expression of a few selected SA genes, i.e., gpr1, apo-D, apo-E, apo-L, mmp-1, mmp-3, cyb561, cyp1b1, and cyp4b1, by reverse transcription-PCR. These SA genes were upregulated in three independent cultures of NHOK at high population doubling (PD) levels compared with those of low PDs. The enhanced expression of these SA genes was also found in senescing NHOK maintained in 3T3 feeder cell system, as well as in the chemically defined medium containing low Ca(2+). These results indicate that the onset of senescence in NHOK is associated with altered expression of the SA genes, which represent discrete gene groups, independently of the donor variation or culture conditions.
authors.affiliation: School of Dentistry and Dental Research Institute, University of California, Los Angeles, CA 90095, USA.
authors.forename: Mo K
authors.initials: MK
authors.lastname: Kang
authors.forename: Ayako
authors.initials: A
authors.lastname: Kameta
authors.forename: Ki-Hyuk
authors.initials: KH
authors.lastname: Shin
authors.forename: Marcel A
authors.initials: MA
authors.lastname: Baluda
authors.forename: Hae-Ryun
authors.initials: HR
authors.lastname: Kim
authors.forename: No-Hee
authors.initials: NH
authors.lastname: Park
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001053:Apolipoproteins / Q000378:metabolism; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics*; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D007700:Kinetics; D020782:Matrix Metalloproteinases / Q000378:metabolism; D051379:Mice; D024101:Mitochondrial Proteins / Q000378:metabolism; D009061:Mouth Mucosa / Q000166:cytology; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001053:Apolipoproteins; D024101:Mitochondrial Proteins; D018809:Proliferating Cell Nuclear Antigen; D011956:Receptors, Cell Surface; D018844:Cyclin-Dependent Kinases; D001616:beta-Galactosidase; D020782:Matrix Metalloproteinases