Crm-A, bcl-2 and NDGA inhibit CD95L-induced apoptosis of malignant glioma cells at the level of caspase 8 processing.
Susceptibility to CD95 (Fas/APO-1)-mediated apoptosis in human glioma cells depends on CD95 expression and unknown factors that regulate signal transduction. Thus, LN-18 cells are highly sensitive to CD95 ligand (CD95L) whereas LN-229 cells require coexposure to inhibitors of RNA or protein synthesis for induction of apoptosis. Here, we report that caspase 8 and 3 activation, poly(ADP-ribose)polymerase cleavage and apoptosis are inhibited by the lipoxygenase inhibitor, nordihydroguaretic acid (NDGA), or ectopic expression of crm-A or bcl-2. CD95L-induced glioma cell apoptosis does not involve ceramide generation. Apoptosis induced by exogenous ceramide resembles CD95-mediated apoptosis in that bcl-2 is protective but differs in that NDGA and crm-A have no effect and in that cycloheximide (CHX) inhibits rather than potentiates ceramide-induced cell death. We conclude that caspase 8 and caspase 3 activation, but not ceramide generation, are required for CD95 ligand-induced apoptosis of glioma cells and that bcl-2, crm-A and NDGA all act upstream of caspases to inhibit apoptosis.
Wagenknecht
B
B
Laboratory of Molecular Neuro-Oncology, Department of Neurology, University of Tübingen, School of Medicine, Tübingen, Germany.
Schulz
J B
JB
Gulbins
E
E
Weller
M
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival; D002518:Ceramides / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D053222:Fas Ligand Protein; D005910:Glioma / Q000201:enzymology* / Q000473:pathology*; D006801:Humans; D009637:Masoprocol / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D015843:Serpins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured; D014764:Viral Proteins; D019014:fas Receptor / Q000502:physiology
D002518:Ceramides; D015853:Cysteine Proteinase Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D015843:Serpins; D014764:Viral Proteins; D019014:fas Receptor; D009637:Masoprocol; C074641:interleukin-1beta-converting enzyme inhibitor; D003513:Cycloheximide; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases