Identification of p21 as a target of cycloheximide-mediated facilitation of CD95-mediated apoptosis in human malignant glioma cells.

Abstract

Human glioma cell lines differ in their requirement for the inhibition of protein synthesis to activate the CD95-dependent killing pathway. CD95 ligand (CD95L) induced mitochondrial cytochrome c release and processing of caspases 3, 7, 8 and 9 in LN-18 cells in the absence of an inhibitor of protein synthesis, cycloheximide (CHX). These biochemical changes were observed in LN-229 cells only in the presence of CHX. The viral caspase inhibitor, cytokine response modifier (crm)-A, inhibited mitochondrial cytochrome c release, caspase processing and cell death under all conditions. Ectopic expression of BCL-X(L) prevented processing of caspase 8 in LN-18 cells but not in LN-229 cells. Thus, caspase 8 activation is amplified through the release of cytochrome c in LN-18 cells but occurs mainly at the receptor in LN-229 cells. In contrast to BCL-2, BCL-X(L), X-linked inhibitor-of-apoptosis protein (XIAP) and FLICE-inhibitory protein (FLIP), the levels of the cyclin-dependent kinase (CDK) inhibitor, p21Waf/Cip1, rapidly decreased in response to CHX. P21 antisense oligonucleotides promoted caspase activation and mitochondrial cytochrome c release and induced strong sensitization to CD95-mediated apoptosis. These data place potentiating effects of CHX (i) to the activation of caspase 8 at the receptor in LN-229 cells as well as (ii) to a down-stream target at least in LN-18 cells, but probably both cell lines, that may be identical with p21Waf/Cip1.

• Authors: T Glaser, B Wagenknecht, M Weller
• Journal: Oncogene (Oncogene) Vol. 20 Issue 35 Pg. 4757-67 (Aug 09 2001) ISSN: 0950-9232 [Print] England
• PMID: 11521188 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• BH3 Interacting Domain Death Agonist Protein
• Bcl2l1 protein, mouse
• Bid protein, mouse
• CASP8 and FADD-Like Apoptosis Regulating Protein
• CFLAR protein, human
• Carrier Proteins
• Cdkn1a protein, mouse
• Cflar protein, mouse
• Cyclin-Dependent Kinase Inhibitor p21
• Cyclins
• Cytochrome c Group
• Intracellular Signaling Peptides and Proteins
• Protein Synthesis Inhibitors
• Proto-Oncogene Proteins c-bcl-2
• bcl-X Protein
• fas Receptor
• Cycloheximide

Topics

• Animals
• Apoptosis
• BH3 Interacting Domain Death Agonist Protein
• CASP8 and FADD-Like Apoptosis Regulating Protein
• Carrier Proteins (metabolism, physiology)
• Cyclin-Dependent Kinase Inhibitor p21
• Cyclins (physiology)
• Cycloheximide (pharmacology)
• Cytochrome c Group (metabolism)
• Glioma (pathology)
• Intracellular Signaling Peptides and Proteins
• Mice
• Protein Synthesis Inhibitors (pharmacology)
• Proto-Oncogene Proteins c-bcl-2 (physiology)
• Tumor Cells, Cultured
• bcl-X Protein
• fas Receptor (physiology)