Distinct stress and cell destruction pathways are engaged by TNF and ceramide during apoptosis of MCF-7 cells.
Ceramide has been proposed to be an important signaling intermediate in tumor necrosis factor (TNF)-induced apoptosis in human MCF-7 breast adenocarcinoma cells. We compared cell death and signal transduction pathways induced by TNF and ceramide in TNF-sensitive, parental MCF-7 cells to those in TNF-resistant, MCF-7 cells (3E9). TNF caused proteolysis of the caspase substrate, polyADP-ribose polymerase (PARP) in parental cells, but not in 3E9 cells. Both apoptosis and PARP cleavage were strongly prevented by co-incubation with caspase inhibitors. In contrast, ceramide-induced cell death was neither affected by TNF resistance nor was it associated with PARP cleavage, and death could not be prevented by co-incubation with caspase inhibitors in either cell line. TNF was able to activate JNK/SAPK approximately 30-fold and approximately 5-fold in parental MCF-7 and 3E9 cells, respectively; in contrast, cell-permeable ceramide only weakly stimulated JNK/SAPK activity in either cell type. Although JNK was activated by TNF, pharmacological blockade of the JNK pathway did not inhibit TNF- or ceramide-mediated cell death. Using mass spectroscopic analysis for ceramide, no increase, rather, a decrease in total ceramide content in TNF-treated parental cells was observed. These results suggest that the cell death signaling and execution pathways utilized by ceramide are distinct from those activated by TNF in MCF-7 cells.
Donato
Nicholas J
NJ
Department of Bioimmunotherapy, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Klostergaard
Jim
J
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism* / Q000633:toxicity; D003603:Cytotoxins / Q000378:metabolism / Q000633:toxicity; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013312:Stress, Physiological / Q000201:enzymology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000633:toxicity
D061945:Caspase Inhibitors; D002518:Ceramides; D003603:Cytotoxins; D004791:Enzyme Inhibitors; D014409:Tumor Necrosis Factor-alpha; D011065:Poly(ADP-ribose) Polymerases; D048031:JNK Mitogen-Activated Protein Kinases; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D020169:Caspases