4-hydroxynonenal induces a cellular redox status-related activation of thecaspase cascade for apoptotic cell death

4-Hydroxynonenal (HNE), a diffusible product of lipid peroxidation, has bee n suggested to be a key mediator of oxidative stress-induced cell death. In this study, we partially characterized the mechanism of HNE-mediated cytot oxicity, Incubation of human T lymphoma Jurkat cells with 20-50 mu M HNE le d to cell death accompanied by DNA fragmentation. Western blot analysis sho wed that HNE-treatment induced time- and dose-dependent activation of caspa se-8, caspase-9 and caspase-3, HNE-induced caspase-3 processing was confirm ed by a how cytometric demonstration of increased catalytic activity on the substrate peptide. EINE treatment also led to remarkable cleavage of poly( ADP-ribose) polymerase (PARP), which was prevented by pretreatment of cells with DEVD-FMK as a caspase-3 inhibitor. The HNE-mediated activation of cas pases, cleavage of PARP and DNA fragmentation were blocked by antioxidants cysteine, N-acety-L-cysteine and dithiothreitol, but not by two other HNE-r eactive amino acids lysine and histidine, or by cystine, the oxidized form of cysteine, HNE rapidly decreased levels of intracellular reduced glutathi one (GSH) and its oxidized form GSSG, and these were also attenuated by the reductants, Coincubation of Jurkat cells with a blocking anti-Fas antibody prevented Fas-induced but not HNE-induced activation of caspase-3, HNE als o activated caspase-3 in K562 cells that do not express functional Fas, Our results thereby demonstrate that HNE triggers oxidative stress-linked apop totic cell death through activation of the caspase cascade. The results als o suggest a possible mechanism involving a direct scavenge of intracellular GSH by HNE.