Activation of reactive oxygen species/AMP activated protein kinase signaling mediates fisetin-induced apoptosis in multiple myeloma U266 cells

We investigated the molecular mechanisms responsible for fisetin-induced apoptosis in U266 cells. Fisetin elicited the cytotoxicity in U266 cells, manifested as an increased fraction of the cells with sub-G1 content or stained positively with TUNEL labeling. Fisetin enhanced caspase-3 activation, downregulation of Bcl-2 and Mcl-1L, and upregulation of Bax, Bim and Bad. Fisetin activated AMPK as well as its substrate acetyl-CoA carboxylase (ACC), along with a decreased phosphorylation of AKT and mTOR. Fisetin also stimulated generation of ROS in U266 cells. Conversely, compound C or N-acetyl-l-cystein blocked fisetin-induced apoptosis. Our data suggest that fisetin-induced apoptosis in U266 cells is through ROS and AMPK pathways.