Ceramide induces caspase-dependent and -independent apoptosis in A-431 cells.
We investigated the ceramide-induced apoptosis and potential mechanism in A-431 cells. Ceramide treatment causes the round up and the death of A-431 cells that is associated with p38 activation and can be observed in 10 h. Short-time ceramide treatment-induced cell death is not associated with the typical apoptotic phenotypes, such as the translocation of phosphatidylserine (PS) from inner layer to outer layer of the plasma membrane, loss of mitochondrial membrane potential, DNA fragmentation, caspase activation, and PARP or PKC-delta degradation. SB202190, a specific inhibitor of p38 mitogen-activated protein (MAP) kinase, but not caspase inhibitor, blocks the cell death induced by short-time ceramide treatment (within 12 h). Whereas neither inhibition of p38 MAP kinase nor inhibition of caspases blocks cell death induced by prolonged ceramide treatment. Moreover, incubation of cells with ceramide for a long time (over 12 h) results in the reduction of proportion of S phase accompanied with typical apoptotic cell death phenotypes that are different from the cell death induced by short-time ceramide treatment. Our data demonstrated that ceramide-induced apoptotic cell death involves both caspase-dependent and caspase-independent signaling pathways. The caspase-independent cell death that occurred in relatively early stage of ceramide treatment is mediated via p38 MAP kinase, which can progress into a stage that is associated with changes of cell cycle events and involves both caspase-dependent and -independent mechanisms.
Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Sheng
S
Zhao
Ya-Nan
YN
Yang
Jian-Guo
JG
Song
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D020169:Caspases / Q000187:drug effects / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D002518:Ceramides / Q000494:pharmacology*; D053938:DNA Fragmentation; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors; D048051:p38 Mitogen-Activated Protein Kinases
D002518:Ceramides; D004791:Enzyme Inhibitors; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases