Cytochrome c is involved in Fas-mediated apoptosis of prostatic carcinoma cell lines.
We have shown previously that the pathways leading to Fas-mediated apoptosis in prostatic carcinoma cell lines are intact, because apoptosis can be triggered either by Fas ligation alone in the Fas-sensitive cell lines PC3 and ALVA31 or by rendering the Fas-resistant cell lines DU145 and JCA1 Fas-sensitive by combined treatment with anti-Fas monoclonal antibody and cycloheximide (O. W. Rokhlin et al., Cancer Res., 57: 1758-1768, 1997). In this study, we demonstrate that two of the early events after Fas ligation are the release of cytochrome c from the mitochondria and activation of caspase-9. We also found that Bid is processed after Fas ligation and thus might activate the mitochondria-dependent apoptotic cascade. In a cell-free system, cytochrome c induced caspase-3-like activity in cytoplasmic extracts from all four cell lines studied, although differences in the level of enzymatic activity were observed. Western blot analysis revealed that caspase-7 is activated by cytochrome c at the same level in all extracts, whereas expression and activation of caspase-3 varied considerably. Cytochrome c-activated extracts displayed different abilities in the induction of apoptotic features in isolated nuclei such as morphological changes and DNA fragmentation. However, differences in nuclear apoptotic activity induced by cytochrome c did not correlate with the level of caspase-3 like activity in the different extracts. These results suggest that the mitochondrial pathway is involved in Fas-mediated apoptosis in prostatic carcinoma cell lines and that, in addition to caspase-7 and caspase-3, there are other factors that confer nuclear apoptotic activity.
Gewies
A
A
Department of Pathology, University of Iowa, Iowa City 52242, USA.
Rokhlin
O W
OW
Cohen
M B
MB
D000911:Antibodies, Monoclonal / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D003593:Cytoplasm / Q000187:drug effects / Q000201:enzymology; D053938:DNA Fragmentation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008297:Male; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D003574:Cytochrome c Group; D019014:fas Receptor; D003513:Cycloheximide; D020169:Caspases