Pooled Screening of Cancer Cell Lines Identifies Vulnerability to Polyunsaturated Fatty-Acid-Induced Ferroptosis.

Polyunsaturated fatty acids (PUFAs) are essential nutrients supporting numerous cellular processes in normal and neoplastic cells, yet PUFA-containing phospholipids predispose cells to ferroptosis. How cancer cells from various lineages or genetic backgrounds proliferate in the presence of PUFA remains poorly understood. Here, by systematically profiling various fatty acids using a barcoded and pooled cancer cell line library, we show that a subset of cell lines is sensitive to PUFA treatment at concentrations comparable to physiological levels. We demonstrate that PUFA treatment alone is sufficient to induce ferroptosis in these cell lines that are also vulnerable to GPX4 inhibition. By correlating patterns of PUFA sensitivity with cancer cell line features including basal mRNA transcript levels, we show that PUFA sensitivity is positively associated with fatty acid binding protein 1 (FABP1) expression. Additionally, by profiling a diverse collection of fatty acids and analogs, we find that ferroptosis in cancer cells can be effectively induced by conjugated linolenic acids, in addition to PUFAs containing 1,4-pentadiene groups. Genome-wide CRISPR modifier screens in the PUFA-sensitive ES2 cells reveal a pro-ferroptosis pathway defined by enzymes that convert PUFAs to membrane-associated phospholipids, and an anti-ferroptosis pathway that segregates PUFAs by delivering them to lipid droplets. Together, we present the first comprehensive data set of PUFA-induced ferroptosis sensitivity in a collection of 554 cell lines from 19 primary lineages and suggest a potential therapeutic avenue to induce tumor cell ferroptosis using dietary metabolites.