title: NADPH oxidase is involved in protein kinase CKII down-regulation-mediated senescence through elevation of the level of reactive oxygen species in human colon cancer cells.
abstract: We have shown that protein kinase CKII (CKII) inhibition induces senescence through the p53-dependent pathway in HCT116 cells. Here we examined the molecular mechanism through which CKII inhibition activates p53 in HCT116 cells. CKII inhibition by treatment with CKII inhibitor or CKIIalpha small-interfering RNA (siRNA) increased intracellular hydrogen peroxide and superoxide anion levels. These effects were significantly blocked by pretreatment of cells with the antioxidant N-acetylcysteine. Additionally, NADPH oxidase (NOX) inhibitor apocynin and p22(phox) siRNA significantly reduced p53 expression and suppressed the appearance of senescence markers. CKII inhibition did not affect mitochondrial superoxide generation. These data demonstrate that CKII inhibition induces superoxide anion generation via NOX activation, and subsequent superoxide-dependent activation of p53 acts as a mediator of senescence in HCT116 cells after down-regulation of CKII.
authors.affiliation: School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Seon Min
authors.initials: SM
authors.lastname: Jeon
authors.forename: Sung-Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Taeg Kyu
authors.initials: TK
authors.lastname: Kwon
authors.forename: Kyung-Jin
authors.initials: KJ
authors.lastname: Kim
authors.forename: Young-Seuk
authors.initials: YS
authors.lastname: Bae
mesh_terms: D000098:Acetophenones; D000111:Acetylcysteine / Q000378:metabolism; D000375:Aging / Q000187:drug effects / Q000235:genetics; D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism*; D016922:Cellular Senescence / Q000235:genetics / Q000502:physiology; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D016158:Genes, p53 / Q000187:drug effects; D045325:HCT116 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D000098:Acetophenones; D000975:Antioxidants; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D013481:Superoxides; C056165:acetovanillone; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D047390:Casein Kinase II; D000111:Acetylcysteine