Ferroptosis is an
iron-dependent, oxidative cell death, and is distinct from apoptosis,
necrosis and autophagy. In this study, we demonstrated that lysosome disrupting agent,
siramesine and a
tyrosine kinase inhibitor,
lapatinib synergistically induced cell death and
reactive oxygen species (ROS) in MDA MB 231, MCF-7, ZR-75 and SKBr3
breast cancer cells over a 24 h time course. Furthermore, the
iron chelator deferoxamine (DFO) significantly reduced cytosolic ROS and cell death following treatment with
siramesine and
lapatinib. Furthermore, we determined that FeCl3 levels were elevated in cells treated with
siramesine and
lapatinib indicating an
iron-dependent cell death, ferroptosis. To confirm this, we treated cells with a potent inhibitor of ferroptosis, ferrastatin-1 that effectively inhibited cell death following
siramesine and
lapatinib treatment. The increase levels of
iron could be due to changes in
iron transport. We found that the expression of
transferrin, which is responsible for the transport of
iron into cells, is increased following treatment with
lapatinib alone or in combination with
siramesine. Knocking down of
transferrin resulted in decreased cell death and ROS
after treatment. In addition, ferroportin-1 (FPN) is an
iron transport protein, responsible for removal of
iron from cells. We found its expression is decreased
after treatment with
siramesine alone or in combination with
lapatinib. Overexpression FPN resulted in decreased ROS and cell death whereas knockdown of FPN increased cell death after
siramesine and
lapatinib treatment. This indicates a novel induction of ferroptosis through altered
iron regulation by treating
breast cancer cells with a lysosome disruptor and a
tyrosine kinase inhibitor.