title: Apoptosis is a mode of cell death in the polykaryon-forming unit assay.
abstract: In the polykaryon-forming unit (PFU) assay, which defines cell survival as the ability to form a cytochalasin-induced polykaryon of predetermined ploidy, the mode of PFU deletion is not known. Incubation of L5178Y-S PFU in cytochalasin resulted in polyploidy (> or =32C) and most polykaryons (>75%) ultimately underwent apoptosis, detected using chromatin condensation and externalised phosphatidylserine. However, large polykaryons carrying terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL)-labelled DNA strand breaks were not observed, presumably due to rapid loss of DNA. Gamma irradiation of PFU prior to cytochalasin exposure caused a reduction in the frequency of highly polyploid cells (>16C), consistent with either a supra-induction of apoptosis or a reduction in the ability of PFU to reach high ploidies. We conclude that L5178Y-S PFU are deleted by apoptosis.
authors.affiliation: Research Department, Velindre NHS Trust, Cardiff.
authors.forename: L
authors.initials: L
authors.lastname: Manti
authors.forename: I D
authors.initials: ID
authors.lastname: Bowen
authors.forename: M D
authors.initials: MD
authors.lastname: Mason
authors.forename: J B
authors.initials: JB
authors.lastname: Court
mesh_terms: D000818:Animals; D017302:Annexins / Q000378:metabolism; D017209:Apoptosis / Q000502:physiology*; D003571:Cytochalasin B / Q000494:pharmacology; D004247:DNA / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage; D005720:Gamma Rays; D015726:Giant Cells / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects / Q000648:ultrastructure; D020287:In Situ Nick-End Labeling; D007940:Leukemia L5178; D051379:Mice; D008854:Microscopy, Electron; D011123:Polyploidy; D014407:Tumor Cells, Cultured
chemical_list: D017302:Annexins; D003571:Cytochalasin B; D004247:DNA