title: Suppression of centrosome amplification after DNA damage depends on p27 accumulation.
abstract: The centrosome plays a fundamental role in cell division, cell polarity, and cell cycle progression. Centrosome duplication is mainly controlled by cyclin-dependent kinase 2 (CDK2)/cyclin E and cyclin A complexes, which are inhibited by the CDK inhibitors p21Cip1 and p27Kip1. It is thought that abnormal activation of CDK2 induces centrosome amplification that is frequently observed in a wide range of aggressive tumors. We previously reported that overexpression of the oncogene MYCN leads to centrosome amplification after DNA damage in neuroblastoma cells. We here show that centrosome amplification after gamma-irradiation was caused by suppression of p27 expression in MYCN-overexpressing cells. We further show that p27-/- and p27+/- mouse embryonic fibroblasts and p27-silenced human cells exhibited a significant increase in centrosome amplification after DNA damage. Moreover, abnormal mitotic cells with amplified centrosomes were frequently observed in p27-silenced cells. In response to DNA damage, the level of p27 gradually increased in normal cells independently of the ataxia telangiectasia mutated/p53 pathway, whereas Skp2, an F-box protein component of an SCF ubiquitin ligase complex that targets p27, was reduced. Additionally, p27 levels in MYCN-overexpressing cells were restored by treatment with Skp2 small interfering RNA, indicating that down-regulation of p27 by MYCN was due to high expression of Skp2. These results suggest that the accumulation of p27 after DNA damage is required for suppression of centrosome amplification, thereby preventing chromosomal instability.
authors.affiliation: Nagahama Institute of Bio-Science and Technology, Shiga, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Sugihara
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanai
authors.forename: Soichiro
authors.initials: S
authors.lastname: Saito
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nitta
authors.forename: Hideo
authors.initials: H
authors.lastname: Toyoshima
authors.forename: Keiko
authors.initials: K
authors.lastname: Nakayama
authors.forename: Keiichi I
authors.initials: KI
authors.lastname: Nakayama
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukasawa
authors.forename: Manfred
authors.initials: M
authors.lastname: Schwab
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saya
authors.forename: Masanao
authors.initials: M
authors.lastname: Miwa
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D018385:Centrosome / Q000502:physiology* / Q000528:radiation effects; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D005720:Gamma Rays; D006801:Humans; D008938:Mitosis / Q000502:physiology / Q000528:radiation effects; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D015513:Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D044786:S-Phase Kinase-Associated Proteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D034741:RNA, Small Interfering; D044786:S-Phase Kinase-Associated Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases