title: Apoptotic signalling in HeLa Hep2 cells following 5 Gy of cobalt-60 gamma radiation.
abstract: BACKGROUND
  The apoptotic signalling pathways involved in the delayed type of apoptosis occurring in HeLa Hep2 cells following radiation were investigated.
  
  
  METHODS
  HeLa Hep2 cells were exposed to 5 Gy of cobalt-60 radiation. The activation of caspase-2, caspase-8, caspase-9 and effector caspase-3 was investigated by caspase assay plates and Western blots. Cleavage of poly (ADP-ribose) polymerase (PARP) was analysed on Western blots. HeLa Hep2 cells were irradiated with or without preincubation with inhibitors of protein synthesis (cycloheximide, CHX) and caspases, followed by TUNEL staining and caspase assay plate evaluation.
  
  
  RESULTS
  Initiator caspases-2, -8, -9, and effector caspase-3, were found to be activated and PARP cleaved following irradiation. CHX completely inhibited the caspase activation and the associated apoptosis. Pretreatment with caspase-2 inhibitor indicated that caspase-2 was involved in the execution of the apoptosis.
  
  
  CONCLUSIONS
  Activation of the apoptotic signalling pathways following irradiation of HeLa Hep2 cells includes components from the intrinsic as well as the extrinsic pathways and seems to require de novo protein synthesis.
authors.affiliation: Department of Immunology, Umeå University, SE-90185 Umeå, Sweden. david.eriksson@climi.umu.se
authors.forename: David
authors.initials: D
authors.lastname: Eriksson
authors.forename: Per-Olov
authors.initials: PO
authors.lastname: Löfroth
authors.forename: Lennart
authors.initials: L
authors.lastname: Johansson
authors.forename: Katrine
authors.initials: K
authors.lastname: Riklund
authors.forename: Torgny
authors.initials: T
authors.lastname: Stigbrand
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology / Q000473:pathology* / Q000532:radiotherapy; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D053143:Caspase 2 / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D003037:Cobalt Radioisotopes; D004789:Enzyme Activation / Q000528:radiation effects; D005260:Female; D005720:Gamma Rays; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D015398:Signal Transduction / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000201:enzymology / Q000473:pathology* / Q000532:radiotherapy
chemical_list: D061945:Caspase Inhibitors; D003037:Cobalt Radioisotopes; D007527:Isoenzymes; D011065:Poly(ADP-ribose) Polymerases; D053143:Caspase 2; D020169:Caspases