Caspase I-related protease inhibition retards the execution of okadaic acid- and camptothecin-induced apoptosis and PAI-2 cleavage, but not commitment to cell death in HL-60 cells.
We have previously reported that the putative cytoprotective protease inhibitor, plasminogen activator inhibitor type 2 (PAI-2), is specifically cleaved during okadaic acid-induced apoptosis in a myeloid leukaemic cell line (Br J Cancer (1994) 70: 834-840). HL-60 cells exposed to okadaic acid and camptothecin underwent morphological and biochemical changes typical of apoptosis, including internucleosomal DNA fragmentation and PAI-2 cleavage. Significant endogenous PAI-2 cleavage was observed 9 h after exposure to okadaic acid; thus correlating with other signs of macromolecular degradation, like internucleosomal DNA fragmentation. In camptothecin-treated cells, PAI-2 cleavage was an early event, detectable after 2 h of treatment, and preceding internucleosomal DNA fragmentation. The caspase I selective protease inhibitor, YVAD-cmk, inhibited internucleosomal DNA fragmentation and PAI-2 cleavage of okadaic acid and camptothecin-induced apoptotic cells. YVAD-cmk rather sensitively and non-toxically inhibited camptothecin-induced morphology, but not okadaic acid-induced morphology. In in vitro experiments recombinant PAI-2 was not found to be a substrate for caspase I. The results suggest that caspase I selective protease inhibition could antagonize parameters coupled to the execution phase of okadaic acid- and camptothecin-induced apoptosis, but not the commitment to cell death.
Jensen
P H
PH
Department of Medical Biochemistry, Aarhus University, Aarhus C, Denmark.
Fladmark
K E
KE
Gjertsen
B T
BT
Vintermyr
O K
OK
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002166:Camptothecin / Q000494:pharmacology*; D020170:Caspase 1 / Q000378:metabolism*; D016923:Cell Death; D018922:HL-60 Cells; D006801:Humans; D019319:Okadaic Acid / Q000494:pharmacology*; D010641:Phenotype; D017396:Plasminogen Activator Inhibitor 2 / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology*
D000590:Amino Acid Chloromethyl Ketones; C098738:N-acetyl-tyrosyl-valyl-alanyl-aspartyl chloromethyl ketone; D017396:Plasminogen Activator Inhibitor 2; D011480:Protease Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019319:Okadaic Acid; D020170:Caspase 1; D002166:Camptothecin