Gemcitabine-mediated apoptosis is associated with increased CD95 surface expression but is not inhibited by DN-FADD in Colo357 pancreatic cancer cells.
This study investigates the role of caspase-8 and DN-FADD, an inhibitor of CD95-dependent caspase-8 activation, in gemcitabine-induced apoptosis of Colo357 pancreatic cancer cells. Gemcitabine-mediated apoptosis was monitored by the kinetics of caspase-8 activation and cytochrome c release. Gemcitabine treatment of Colo357 cells increased CD95 surface expression, raising the possibility of the involvement of CD95 in gemcitabine-mediated caspase-8 activation. However, ectopic expression of DN-FADD and treatment of cells with the antagonistic anti-CD95 antibody ZB4 both failed to suppress gemcitabine-induced apoptosis but substantially inhibited CD95-mediated apoptosis. DN-FADD, which surprisingly accumulated in nuclei of Colo357 cells, was unable to block caspase-8 activation mediated by either gemcitabine or CD95. These observations argue against a role of CD95 in gemcitabine-induced caspase-8 activation and reveal that the anti-apoptotic function of DN-FADD differs from caspase-8 inhibition in Colo357 cells.
Christgen
Matthias
M
Clinic for General and Thoracic Surgery, Molecular Oncology Research Group, University of Kiel, Arnold-Heller-Str. 7, 24105 Kiel, Germany.
Schniewind
Bodo
B
Jueschke
Astrid
A
Ungefroren
Hendrik
H
Kalthoff
Holger
H
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D053200:Fas-Associated Death Domain Protein; D005434:Flow Cytometry; D005799:Genes, Dominant; D006801:Humans; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D012190:Retroviridae / Q000235:genetics; D012264:Ribonucleotide Reductases / Q000037:antagonists & inhibitors; D014162:Transfection; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism*; D000093542:Gemcitabine
D048868:Adaptor Proteins, Signal Transducing; D000964:Antimetabolites, Antineoplastic; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D019014:fas Receptor; D003841:Deoxycytidine; D012264:Ribonucleotide Reductases; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases; D000093542:Gemcitabine