Caspase-independent apoptosis is activated by diazepam-induced mitotic failure in HeLa cells, but not in human primary fibroblasts

I. Vitale, A. Antoccia, P. Crateri, S. Leone, G. Arancia, C. Tanzarella

Research output: Contribution to journalArticlepeer-review

Abstract

DZ, a benzodiazepine known to affect centrosome separation at prophase, leads to a higher degree of mitotic arrest in HeLa cells than in primary human fibroblasts. In fact, differently from fibroblasts, which undergo a transient block in prophase-to-prometaphase transition, a high proportion of tumor cells attempt to escape from the DZ-imposed mitotic block, fail to undergo complete mitosis and die by mitotic failure. DZ-treated samples showed certain biochemical hallmarks of apoptosis, such as induction of the proapototic Bax protein, mitochondrial alterations assessed by JC-1 staining and TEM analysis, PARP cleavage, and DNA fragmentation. However, in DZ-treated cells, we observed a very low or absent caspase activation as shown by immunofluorescence and immunoblot experiments with antibodies directed to activated caspases and by staining with the pancaspase inhibitor FITC-VAD-FMK. Experiments on mitochondrial depolymerization and apoptosis induction carried out in the presence of specific inhibitors of caspase-2 and caspase-3/7 indicated a caspase-independent apoptotic process induced by DZ. Accordingly, TEM analysis of treated cells revealed ultrastructural features resembling those reported for caspase-independent apoptosis. In conclusion, we hypothesize that HeLa cells override the prophase block imposed by DZ, producing a high rate of aberrant pro-metaphases, which, in turn, activates caspase-independent, apoptosis-like mitotic catastrophe.

Original languageEnglish
Pages (from-to)909-920
Number of pages12
JournalApoptosis
Volume10
Issue number4
DOIs
Publication statusPublished - Aug 2005

Keywords

  • Caspase-3
  • Caspase-9
  • Cell death
  • Centrosome
  • Diazepam
  • Mitotic catastrophe

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Cell Biology

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