Ferroptotic cell death triggered by conjugated linolenic acids is mediated by ACSL1

Ferroptosis is associated with lipid hydroperoxides generated by oxidation of polyunsaturated acyl chains. Lipid hydroperoxides are reduced by glutathione peroxidase 4 (GPX4) and GPX4 inhibitors induce ferroptosis. However, the therapeutic potential of triggering ferroptosis in cancer cells with polyunsaturated fatty acids is unknown. We identified conjugated linoleates including α-eleostearic acid (αESA) as novel ferroptosis inducers. αESA did not alter GPX4 activity but was incorporated into cellular lipids and promoted lipid peroxidation and cell death in diverse cancer cell types. αESA-triggered death was mediated by acyl-CoA synthetase long-chain isoform 1, which promoted αESA incorporation into neutral lipids including triacylglycerols. Interfering with triacylglycerol biosynthesis suppressed ferroptosis triggered by αESA but not by GPX4 inhibition. Orally administered tung oil, naturally rich in αESA, limited tumor growth and metastasis with transcriptional changes consistent with ferroptosis. Overall, these findings illuminate a novel approach to ferroptosis, complementary to GPX4 inhibition, with therapeutic potential. Three independent replicates of MDA-MB-231 cells incubated for 5 hours with ML162 (125 nM) or ESA (100 µM) and 2 replicates for the control incubated with the vehicle for ESA (methanol) were sequenced.