title: Genome wide expression analysis of radiation-induced DNA damage responses in isogenic HCT116 p53+/+ and HCT116 p53-/- colorectal carcinoma cell lines.
abstract: OBJECTIVE
  To study the kinetics of gene expression alterations following radiation exposure of isogenic HCT116 p53 +/+ and HCT116 p53-/- cell lines.
  
  
  METHODS
  Cells were exposed to 5 Gy of irradiation (Cs-137) and genome-wide temporal expression analysis using Illumina bead chip arrays was performed. Signalling pathways were explored using Metacore (Genego). Biological responses including cell cycle checkpoint activation, centrosome amplification and senescence induction were analyzed.
  
  
  RESULTS
  Significant differences in the radiation response were observed between the p53+/+ and the p53-/- cell lines. In p53+/+ cells concurrent G1- and G2-arrests were activated followed by senescence induction. Increased expression of genes associated with senescence, senescence associated secretory phenotype (SASP) and repression of genes essential for G2-M transition were detected. P53-/- cells arrested mainly in G2 followed by centrosome amplification, mitotic slippage and a subsequent increase of polyploid cells. Furthermore, changes in expression correlated well with these signs of mitotic catastrophe.
  
  
  CONCLUSIONS
  The presence or absence of p53 triggers different signalling cascades with different endpoints. Elucidating these differences is important as it enables improvement of radiation treatment and could be used to develop new combination treatments with specific inhibitors of key regulators of these cell death modalities.
authors.affiliation: Department of Clinical Microbiology, Immunology, Umeå University , Umeå , Sweden.
authors.forename: Theres
authors.initials: T
authors.lastname: Lindgren
authors.forename: Torgny
authors.initials: T
authors.lastname: Stigbrand
authors.forename: Aino
authors.initials: A
authors.lastname: Råberg
authors.forename: Katrine
authors.initials: K
authors.lastname: Riklund
authors.forename: Lennart
authors.initials: L
authors.lastname: Johansson
authors.forename: David
authors.initials: D
authors.lastname: Eriksson
mesh_terms: D059447:Cell Cycle Checkpoints / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D016922:Cellular Senescence / Q000528:radiation effects; D018385:Centrosome / Q000528:radiation effects; D015179:Colorectal Neoplasms / Q000473:pathology*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D020869:Gene Expression Profiling; D023281:Genomics; D045325:HCT116 Cells; D006801:Humans; D007700:Kinetics; D008938:Mitosis / Q000528:radiation effects; D010641:Phenotype; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency* / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53
keywords: Radiation; cell cycle checkpoint; gene expression; mitotic catastrophe; p53; senescence