title: Survivin safeguards chromosome numbers and protects from aneuploidy independently from p53.
abstract: BACKGROUND
  Survivin, a member of the inhibitor of apoptosis (IAP) gene family, has a dual role in mitosis and in apoptosis. It is abundantly expressed in every human tumor, compared with normal tissues. During mitosis Survivin assembles with the chromosomal passenger complex and regulates chromosomal segregation. Here, we aim to explore whether interference with the mitotic function of Survivin is linked to p53-mediated G1 cell cycle arrest and affects chromosomal stability.
  
  
  METHODS
  In this study, we used HCT116, SBC-2, and U87-MG and generated corresponding isogenic p53-deficient cells. Retroviral vectors were used to stably knockdown Survivin. The resulting phenotype, in particular the mechanisms of cell cycle arrest and of initiation of aneuploidy, were investigated by Western Blot analysis, confocal laser scan microscopy, proliferation assays, spectral karyotyping and RNAi.
  
  
  RESULTS
  In all cell lines Survivin-RNAi did not induce instant apoptosis but caused polyplodization irrespective of p53 status. Strikingly, polyploidization after knockdown of Survivin resulted in merotelic kinetochore spindle assemblies, γH2AX-foci, and DNA damage response (DDR), which was accompanied by a transient p53-mediated G1-arrest. That p53 wild type cells specifically arrest due to DNA damage was shown by simultaneous inhibition of ATM and DNA-PK, which abolished induction of p21waf/cip. Cytogenetic analysis revealed chromosomal aberrations indicative for DNA double strand break repair by the mechanism of non-homologous end joining (NHEJ), only in Survivin-depleted cells.
  
  
  CONCLUSIONS
  Our findings suggest that Survivin plays an essential role in proper amphitelic kinetochore-spindle assembly and that constraining Survivin's mitotic function results in polyploidy and aneuploidy which cannot be controlled by p53. Therefore, Survivin critically safeguards chromosomal stability independently from p53.
authors.forename: Ralf
authors.initials: R
authors.lastname: Wiedemuth
authors.forename: Barbara
authors.initials: B
authors.lastname: Klink
authors.forename: Katrin
authors.initials: K
authors.lastname: Töpfer
authors.forename: Evelin
authors.initials: E
authors.lastname: Schröck
authors.forename: Gabriele
authors.initials: G
authors.lastname: Schackert
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tatsuka
authors.affiliation: Department of Neurosurgery, Section Experimental Neurosurgery/Tumor Immunology, University Hospital Carl Gustav Carus, TU Dresden, Fetscherstr, 74, 01307 Dresden, Germany. Achim.Temme@uniklinikum-dresden.de.
authors.forename: Achim
authors.initials: A
authors.lastname: Temme
mesh_terms: D000782:Aneuploidy; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D020090:Chromosome Segregation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D042822:Genomic Instability; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics* / Q000378:metabolism; D007621:Karyotyping; D018386:Kinetochores / Q000378:metabolism / Q000648:ultrastructure; D008938:Mitosis; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011123:Polyploidy; D008941:Spindle Apparatus / Q000378:metabolism / Q000648:ultrastructure; D000077022:Survivin; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: C107489:BIRC5 protein, human; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C468783:H2AX protein, human; D006657:Histones; D051034:Inhibitor of Apoptosis Proteins; D009687:Nuclear Proteins; D000077022:Survivin; D016159:Tumor Suppressor Protein p53; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human