Characterization of Apt- cell lines exhibiting cross-resistance to glucocorticoid- and Fas-mediated apoptosis

David J. Askew, Unsal Kuscuoglu, Thomas Brunner, Douglas R. Green, Roger L. Miesfeld

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10 Scopus citations

Abstract

Apoptosis induction by staurosporine, ceramide, and Fas stimulation was investigated in the mouse thymoma cell line W7.2 and a panel of dexamethasone (dex)-resistant W7.2 mutant cell lines, Apt3.8, Apt4.8 and Apt5.8, and a Bcl-2 transfected W7.2 cell line (Wbcl2). While W7.2 cells were found to be sensitive to these apoptosis inducers, the Apt- mutants and Wbcl2 cells were shown to be resistant to some or all of the treatments. Specifically, all three Apt- mutants and Wbcl2 cells were found to be resistant to ceramide and Fas-mediated apoptosis, whereas, Apt4.8 and Apt5.8 were sensitive to staurosporine-induced apoptosis under conditions in which Apt3.8 and Wbcl2 cells were resistant. Measurements of caspase activity and cytochrome c release in cytosolic extracts of dex and staurosporine-treated cells indicated that the recessive Apt- mutations effect steps upstream of mitochondrial dysfunction. Steady-state RNA levels of apoptosis-associated gene transcripts showed that the observed differential resistance of the Apt- cell lines could not be explained by altered expression of numerous Bcl-2 or Fas related genes. Transient transfection of human Fas gene coding sequences into the Apt- mutants and Wbcl2 cells did not induce apoptosis, even though these same cell lines were sensitive to ectopic expression of the FADD and caspase 8 genes. Taken together, these data provide genetic evidence for the existence of shared components in the dex- and Fas-mediated apoptotic pathways in W7.2 cells.

Original languageEnglish (US)
Pages (from-to)796-804
Number of pages9
JournalCell Death and Differentiation
Volume6
Issue number8
DOIs
StatePublished - Aug 1999

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Keywords

  • Apoptosis
  • Bcl-2
  • Fas
  • Glucocorticoids
  • Staurosporine
  • Thymocytes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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