title: Cooperative effect of p21Cip1/WAF-1 and 14-3-3sigma on cell cycle arrest and apoptosis induction by p14ARF.
abstract: P14(ARF) (p19(ARF) in the mouse) plays a central role in the regulation of cellular proliferation. Although the capacity of p14(ARF) to induce a cell cycle arrest in G1 phase depends on a functional p53/p21-signaling axis, the G2 arrest triggered by p14(ARF) is p53/p21-independent. Using isogeneic HCT116 cells either wild-type or homozygously deleted for p21, 14-3-3sigma or both, we further investigated the cooperative effect of p21 and 14-3-3sigma on cell cycle regulation and apoptosis induction by p14(ARF). In contrast to DNA damage, which induces mitotic catastrophe in 14-3-3sigma-deficient cells, we show here that the expression of p14(ARF) triggers apoptotic cell death, as evidenced by nuclear DNA fragmentation and induction of pan-caspase activities, irrespective of the presence or absence of 14-3-3sigma. The activation of the intrinsic mitochondrial apoptosis pathway by p14(ARF) was confirmed by cytochrome c release from mitochondria and induction of caspase-9- (LEHDase) and caspase-3/7-like (DEVDase) activities. Moreover, 14-3-3sigma/p21 double-deficient cells were exceedingly sensitive to apoptosis induction by p14(ARF) as compared to wild-type cells or cells lacking either gene alone. Notably, p14(ARF)-induced apoptosis was preceded by an arrest in the G2 phase of cell cycle, which coincided with downregulation of cdc2 (cdk1) protein expression and lack of its nuclear localization. This indicates that p14(ARF) impairs mitotic entry by targeting the distal DNA damage-signaling pathway and induces apoptotic cell death, rather than mitotic catastrophe, out of a transient G2 arrest. Furthermore, our data delineate that the disruption of G2/M cell cycle checkpoint control critically determines the sensitivity of the cell toward p14(ARF)-induced mitochondrial apoptosis.
authors.affiliation: Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Campus Berlin-Buch, Germany.
authors.forename: P G
authors.initials: PG
authors.lastname: Hemmati
authors.forename: G
authors.initials: G
authors.lastname: Normand
authors.forename: B
authors.initials: B
authors.lastname: Gillissen
authors.forename: J
authors.initials: J
authors.lastname: Wendt
authors.forename: B
authors.initials: B
authors.lastname: Dörken
authors.forename: P T
authors.initials: PT
authors.lastname: Daniel
mesh_terms: D048948:14-3-3 Proteins; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D016203:CDC2 Protein Kinase; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases; D045304:Cytochromes c / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000502:physiology; D053938:DNA Fragmentation; D005092:Exonucleases / Q000235:genetics / Q000378:metabolism*; D005095:Exoribonucleases; D016193:G1 Phase / Q000502:physiology*; D016195:G2 Phase / Q000502:physiology*; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; C493956:CDKN1A protein, human; D019926:Cyclin B; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009363:Neoplasm Proteins; C495901:TP53 protein, human; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; D045304:Cytochromes c; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; D018844:Cyclin-Dependent Kinases; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human; D020169:Caspases