Acetaminophen induces a caspase-dependent and Bcl-XL sensitive apoptosis in human hepatoma cells and lymphocytes.
Acetaminophen is a widely used analgesic and antipyretic drug that exhibits toxicity at high doses to the liver and kidneys. This toxicity has been attributed to cytochrome P-450-generated metabolites which covalently modify target proteins. Recently, acetaminophen, in its unmetabolized form, has been shown to affect a variety of cells and tissues, for instance, testicular and lymphoid tissues and lymphocyte cell lines. The effects on cell viability of acetaminophen at a concentration comparable to that achieved in plasma during acetaminophen toxicity have now been examined with a hepatoma cell line SK-Hep1, primary human peripheral blood lymphocytes and human Jurkat T cells. Acetaminophen reduced cell viability in a time-dependent manner. Staining of cells with annexin-V also revealed that acetaminophen induced, after 8 hr of treatment, a loss of the asymmetry of membrane phospholipids, which is an early event associated with apoptosis. Acetaminophen triggered the release of cytochrome c from mitochondria into the cytosol, activation of caspase-3, 8, and 9, cleavage of poly(ADP-ribose) polymerase, and degradation of lamin B1 and DNA. Whereas cleavage of DNA into internucleosomal fragments was apparent in acetaminophen treated SK-Hep1 and primary lymphocytes, DNA was only degraded to 50-kb fragments in treated Jurkat cells. Overexpression of the antiapoptotic protein Bcl-XL prevented these various apoptotic events induced by acetaminophen in Jurkat cells. Caspase-8 activation was a postmictochondrial event and occurred in a Fas-independent manner. These results demonstrate that acetaminophen induces caspases-dependent apoptosis with mitochondria as a primary target. These results also reiterate the potential role of apoptosis in acetaminophen hepatic and extrahepatic toxicity.
Boulares
A Hamid
AH
Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC 20007, USA.
Zoltoski
Anna J
AJ
Stoica
Bogdan A
BA
Cuvillier
Olivier
O
Smulson
Mark E
ME
D000082:Acetaminophen / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D018712:Analgesics, Non-Narcotic; D000082:Acetaminophen; D020169:Caspases