Cell cycle dependency of caspase activation in Fas-induced apoptosis in leukemia cells.
The relationship between apoptosis and the cell cycle remains unclear. In the present study we have investigated the relationship between cell cycle progression and the activation of caspases (caspase-3 and caspase-8) in Fas (CD95)-mediated apoptosis in asynchronously growing leukemia cells. We found that cells expressing the active form of caspase-3 were cyclin A/B1 and Ki-67 negative but cyclin E positive, whereas expression of the active form of caspase-8 was detected in cyclin A/B1/E-negative and Ki-67-negative cells. In addition, both the activation of caspases and Fas-mediated apoptosis were completely abolished when leukemia cells were arrested in early G1 phase. Using post-sorting western blot analysis, we demonstrated that caspase-3 and caspase-8 were activated in p27-negative cells. These results suggest that caspase-3 would be activated in cells entering into late G1 or early S phase, and caspase-8 would be activated in middle or late G1 phase. The speed of cell cycle progression from G1 to S phase might be influential in the speed of caspase activation and induction of Fas-mediated apoptosis.
Li
Yufeng
Y
Department of Pediatrics and Developmental Science, Mie University Graduate School of Medicine, Edobashi 2-174, Tsu, Mie 514-8507, Japan.
Dida
Francis
F
Iwao
Atsushi
A
Deguchi
Takao
T
Azuma
Eiichi
E
Komada
Yoshihiro
Y
D017209:Apoptosis; D053148:Caspase 3 / Q000096:biosynthesis; D053181:Caspase 8 / Q000096:biosynthesis; D020169:Caspases / Q000096:biosynthesis*; D002453:Cell Cycle; D016213:Cyclins / Q000378:metabolism; D004789:Enzyme Activation; D016193:G1 Phase; D006801:Humans; D007938:Leukemia / Q000201:enzymology* / Q000473:pathology*; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000494:pharmacology*
D016213:Cyclins; D019014:fas Receptor; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases