title: Double targeting of Survivin and XIAP radiosensitizes 3D grown human colorectal tumor cells and decreases migration.
abstract: OBJECTIVE
  In the present study, we aimed to investigate the effect of single and double knockdown of the inhibitor of apoptosis proteins (IAP) Survivin and X-linked IAP (XIAP) on three-dimensional (3D) clonogenic survival, migration capacity and underlying signaling pathways.
  
  
  METHODS
  Colorectal cancer cell lines (HCT-15, SW48, SW480, SW620) were subjected to siRNA-mediated single or Survivin/XIAP double knockdown followed by 3D colony forming assays, cell cycle analysis, Caspase activity assays, migration assays, matrigel transmigration assays and Western blotting (Survivin, XIAP, Focal adhesion kinase (FAK), p-FAK Y397, Akt1, p-Akt1 S473, Extracellular signal-regulated kinase (ERK1/2), p-ERK1/2 T202/Y204, Glycogen synthase kinase (GSK)3β, p-GSK3β S9, nuclear factor (NF)-κB p65).
  
  
  RESULTS
  While basal cell survival was altered cell line-dependently, Survivin or XIAP single and Survivin/XIAP double knockdown enhanced cellular radiosensitivity of all tested cancer cell lines grown in 3D. Particularly double knockdown conditions revealed accumulation of cells in G2/M, increased subG1 fraction, elevated Caspase 3/7 activity, and reduced migration. Intracellular signaling showed dephosphorylation of FAK and Akt1 upon Survivin and/or Survivin/XIAP silencing.
  
  
  CONCLUSIONS
  Our results strengthen the notion of Survivin and XIAP to act as radiation resistance factors and further indicate that these apoptosis-regulating proteins are also functioning in cell cycling and cell migration.
authors.affiliation: Department of Radiotherapy and Oncology, University of Frankfurt, Germany. stephanie.hehlgans@kgu.de
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hehlgans
authors.forename: Chrysi
authors.initials: C
authors.lastname: Petraki
authors.forename: Sebastian
authors.initials: S
authors.lastname: Reichert
authors.forename: Nils
authors.initials: N
authors.lastname: Cordes
authors.forename: Claus
authors.initials: C
authors.lastname: Rödel
authors.forename: Franz
authors.initials: F
authors.lastname: Rödel
mesh_terms: D002453:Cell Cycle; D045744:Cell Line, Tumor; D002465:Cell Movement; D015179:Colorectal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011836:Radiation Tolerance; D000077022:Survivin; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000037:antagonists & inhibitors* / Q000502:physiology
chemical_list: C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D000077022:Survivin; D051636:X-Linked Inhibitor of Apoptosis Protein; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051057:Proto-Oncogene Proteins c-akt
keywords: Colorectal cancer; Invasion; Ionizing radiation; Migration; Survivin; Three-dimensional cell culture; XIAP