Granulocytic differentiation of HL-60 cells results in spontaneous apoptosis mediated by increased caspase expression.
HL-60 cells differentiating into neutrophil-like cells die an apoptotic death in vitro. Susceptibility to apoptosis is associated with decreased Bcl-2 protein and mRNA expression; however, the effect of differentiation on the expression of pro-apoptotic caspases is unknown. Spontaneous apoptosis occurred 6 days after retinoic acid treatment. Western blotting showed loss of Bcl-2 by day 7, and new expression of ICE (caspase 1) and CPP32 (caspase 3) protein by day 2. Northern analysis demonstrated loss of Bcl-2 mRNA and increases in ICE mRNA by day 2; CPP32 mRNA was unchanged. Differential Bcl-2 and ICE mRNA expression was also found when granulocytic differentiation was stimulated by DMSO. Differentiated HL-60 cell lysates exhibited functional ICE proteolytic activity. De novo caspase expression was responsible for the development of spontaneous apoptosis, since specific inhibitors of ICE (YVAD-CMK) and CPP32 (DEVD-CHO), inhibited retinoic acid induced spontaneous apoptosis. Functional maturation and susceptibility to apoptosis are both inducible and linked in this granulocyte precursor cell line.
Watson
R W
RW
Department of Surgery, Toronto Hospital, University of Toronto, ON, Canada.
Rotstein
O D
OD
Parodo
J
J
Bitar
R
R
Hackam
D
D
Marshall
J C
JC
D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D020170:Caspase 1; D002454:Cell Differentiation / Q000187:drug effects; D003546:Cysteine Endopeptidases / Q000096:biosynthesis* / Q000187:drug effects / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D006098:Granulocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D018922:HL-60 Cells; D006801:Humans; D009504:Neutrophils / Q000201:enzymology / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D015398:Signal Transduction; D014212:Tretinoin / Q000494:pharmacology; D019014:fas Receptor / Q000502:physiology
D015853:Cysteine Proteinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D019014:fas Receptor; D014212:Tretinoin; D003546:Cysteine Endopeptidases; D020170:Caspase 1