We have demonstrated that RRR-α-tocopheryl succinate (10 μg/mL vitamin E succinate (VES) treatment of estrogen receptor-negative MDA-MB-435 human breast cancer cells induces 9, 19, 51, and 72% apoptotic cells on days 1-4, respectively, after treatment, which involves transforming growth factor-β signaling. Here, we show that VES-triggered apoptosis of MDA-MB-435 cells induced prolonged elevated expression of c-jun mRNA and protein (neither of which was caused by major increases in stability) and also induced enhanced activator protein-1 (AP-1) binding to the consensus DNA oligomer. Furthermore, VES treatments resulted in increased AP-1 transactivation activity, as measured with an AP-1 promoter/luciferase reporter construct and by the measurement of increased mRNA expression of the AP-l-dependent endogenous gene collagenase. Evidence of VES-induced involvement of the c- jun amino-terminal kinase in these AP-1-dependent events was suggested by data showing prolonged activity of this kinase, as measured by a kinase assay using glutathione Stransferase-c-jun as the substrate. The c-jun-dependent transcriptional activity was verified by cotransfection of a chimetic transcription factor having a galactose 4 DNA-binding domain coupled with the transactivation domain of c-jun plus the reporter plasmid 5X GAL4- luciferase. MDA-MB-435 cells infected with an adenovirus expression vector containing the TAM-67 sequence for dominant/negative-acting mutant c-jun or transiently transfected with c-jun antisense exhibited a 50-77% reduction in VES-mediated apoptosis as compared with control adenovirus-infected or control sense oligomer-transfected cells.