39 Lysosome disruptor’s siramesine and the kinase inhibitor lapatinib induce synergistic cell death through ferroptosis in glioma cells

Glioblastoma is inherently resistant to radiation and drug treatments. This is mediated by the most common forms of cell death are often actively inhibited. Identifying and exploiting alternative cell death pathways are essential to overcoming or bypassing drug resistance. Ferroptosis, a newly described, morphologically and biochemically distinct, cell death mechanism is characterized by iron-dependent cellular accumulation of reactive oxygen species. The combination of siramesine, a lysosome disruptor, and lapatinib, a dual tyrosine kinase inhibitor (TKI), synergistically induced death in glioma cancer cells. This cell death had characteristics of ferroptosis: it was blocked by the ferroptosis inhibitor ferrostatin-1 and the iron chelator deferoxamine. In addition, the amount of ROS and lipid peroxidation were increased in glioma cells. Iron transport protein remained unchanged but reactive iron levels increased. One target for kinase inhibitors is protein bisulfate isomerase (PDI). Knockdown of PDI in combination with siramesine increased cell death that was blocked by ferrostatin-1. Taken together, drug combinations that alter reactive iron and ROS levels might induce ferroptosis and overcome drug resistance in glioma cells.