In cancer cells the small compounds erastin and RSL3 promote a novel type of cell death called ferroptosis, which requires iron‐dependent accumulation of lipid reactive oxygen species. Here we assessed the contribution of lipid peroxidation activity of lipoxygenases (LOX) to ferroptosis in oncogenic Ras‐expressing cancer cells. Several 12/15‐LOX inhibitors prevented cell death induced by erastin and RSL3. Furthermore, siRNA‐mediated silencing of ALOX15 significantly decreased both erastin‐induced and RSL3‐induced ferroptotic cell death, whereas exogenous overexpression of ALOX15 enhanced the effect of these compounds. Immunofluorescence analyses revealed that the ALOX15 protein consistently localizes to cell membrane during the course of ferroptosis. Importantly, treatments of cells with ALOX15‐activating compounds accelerated cell death at low, but not high doses of erastin and RSL3. These observations suggest that tumor ferroptosis is promoted by LOX‐catalyzed lipid hydroperoxide generation in cellular membranes.

Pharmacological challenges to oncogenic Ras-expressing cancer cells have shown a novel type of cell death, ferroptosis, which requires intracellular iron. In the present study, we assessed ferroptosis following treatment of human fibrosarcoma HT1080 cells with several inhibitors of lysosomal activity and found that they prevented cell death induced by the ferroptosis-inducing compounds erastin and RSL3. Fluorescent analyses with a reactive oxygen species (ROS) sensor revealed constitutive generation of ROS in lysosomes, and treatment with lysosome inhibitors decreased both lysosomal ROS and a ferroptotic cell-death-associated ROS burst. These inhibitors partially prevented intracellular iron provision by attenuating intracellular transport of transferrin or autophagic degradation of ferritin. Furthermore, analyses with a fluorescent sensor that detects oxidative changes in cell membranes revealed that formation of lipid ROS in perinuclear compartments probably represented an early event in ferroptosis. These results suggest that lysosomal activity is involved in lipid ROS-mediated ferroptotic cell death through regulation of cellular iron equilibria and ROS generation.

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Summary Ferroptosis, a type of oxidative stress cell death, has been implicated in cell injury in several diseases, and treatments with specific inhibitors have been shown to protect cells and tissues. Here we demonstrated that a treatment with the nitroxide radical, 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), prevented the ferroptotic cell death in an airborne manner. Other TEMPO derivatives and lipophilic antioxidants, such as Trolox and ferrostatin-1, also prevented cell death induced by erastin and RSL3; however, only TEMPO exhibited inhibitory activity from a physically distant location. TEMPO vaporized without decomposing, and then dissolved again into a nearby water solution. Volatilized TEMPO inhibited glutamate-induced cell death in mouse hippocampal cell lines, and also reduced neuronal cell death in a mouse ischemia model. These results suggest that TEMPO is a unique cell protective agent that acts in a volatility-mediated manner.

We report a case of embolic occlusion of the common carotid artery (CCA) in which a giant thrombus was retrieved using the parallel stent retriever technique.Case presentation: An 84-year-old woman without anticoagulant therapy despite a history of cardioembolic stroke presented to our hospital because of left hemiparesis after developing sudden vision loss in her right eye. Emergency angiography revealed a giant thrombus in the right CCA. After arresting flow in the CCA using a balloon-guided catheter (BGC), we deployed two stent retrievers in parallel from the internal carotid artery to the CCA, and slowly retrieved them simultaneously under manual aspiration through the BGC. As a result, complete recanalization was achieved. Conclusion:Thrombi causing acute embolic occlusion of the CCA are often too large to be completely retrieved using conventional thrombectomy techniques. The parallel stent retriever technique may be effective in such cases.Keywords▶ giant thrombus, embolic occlusion of the common carotid artery, endovascular thrombectomy, cardiogenic embolism