Significance: Phosphatidylethanolamine (PE)-linked arachidonic acid (AA) and adrenic acid (AdA) are well-known substrates for lipid peroxidation, which are indispensable for ferroptosis, an iron-dependent regulated necrosis. However, how cells differentially regulate the intracellular pools of AA and AdA is not fully understood. Here, elongation of very long-chain fatty acid protein 5 (ELOVL5) and fatty acid desaturase 1 (FADS1) are differentially expressed in gastric cancer cells, discriminating the cellular susceptibility to ferroptosis. Biochemical and lipidomics analyses support the hypothesis that ELOVL5 and FADS1 are required to maintain intracellular levels of AA and AdA and promote ferroptosis. Our study highlights the biosynthesis of AA and AdA by ELOVL5 and FADS1 as a critical checkpoint in the ferroptosis pathway.

Ferroptosis is a form of regulated cell death characterized by iron-dependent lipid peroxidation. This process contributes to cellular and tissue damage in various human diseases, such as cardiovascular diseases, neurodegeneration, liver disease, and cancer. Although polyunsaturated fatty acids (PUFAs) in membrane phospholipids are preferentially oxidized, saturated/monounsaturated fatty acids (SFAs/MUFAs) also influence lipid peroxidation and ferroptosis. In this review, we first explain how cells differentially synthesize SFA/MUFAs and PUFAs and how they control fatty acid pools via fatty acid uptake and β-oxidation, impacting ferroptosis. Furthermore, we discuss how fatty acids are stored in different lipids, such as diacyl or ether phospholipids with different head groups; triglycerides; and cholesterols. Moreover, we explain how these fatty acids are released from these molecules. In summary, we provide an integrated view of the diverse and dynamic metabolic processes in the context of ferroptosis by revisiting lipidomic studies. Thus, this review contributes to the development of therapeutic strategies for ferroptosis-related diseases.

Ferroptosis, a type of cell death induced by lipid peroxidation, has emerged as a novel anti-cancer strategy. Cancer cells frequently acquire resistance to ferroptosis. However, the underlying mechanisms are poorly understood. To address this issue, we conducted a thorough investigation of the genomic and transcriptomic data derived from hundreds of human cancer cell lines and primary tissue samples, with a particular focus on non-small cell lung carcinoma (NSCLC). It was observed that mutations in Kelch-like ECH-associated protein 1 (KEAP1) and subsequent nuclear factor erythroid 2-related factor 2 (NRF2, also known as NFE2L2) activation are strongly associated with ferroptosis resistance in NSCLC. Additionally, AIFM2 gene, which encodes ferroptosis suppressor protein 1 (FSP1), was identified as the gene most significantly correlated with ferroptosis resistance, followed by multiple NRF2 targets. We found that inhibition of NRF2 alone was not sufficient to reduce FSP1 protein levels and promote ferroptosis, whereas FSP1 inhibition effectively sensitized KEAP1-mutant NSCLC cells to ferroptosis. Furthermore, we found that combined inhibition of FSP1 and NRF2 induced ferroptosis more intensely. Our findings imply that FSP1 is a crucial suppressor of ferroptosis whose expression is partially dependent on NRF2 and that synergistically targeting both FSP1 and NRF2 may be a promising strategy for overcoming ferroptosis resistance in cancer.

Doxorubicin is an anthracycline anticancer drug commonly used to treat lymphoma and breast cancer. Its major side effect is cardiotoxicity, which occurs by damaging cardiomyocytes. The mechanisms of doxorubicin-induced cardiotoxicity remain unclear; however, recent studies suggest that ferroptosis, an iron-dependent form of lipid peroxidation-mediated cell death, may play a key role. In this study, we investigated the role of ferroptosis in doxorubicin-induced cardiotoxicity using ferroptosis-specific inhibitors (ferrostatin-1 and liproxstatin-1). In both H9c2 cardiomyocyte cell lines and human induced pluripotent stem cell-derived cardiomyocytes, ferrostatin-1 and liproxstatin-1 rescued cell death induced by RSL3, a ferroptosis inducer, but failed to prevent doxorubicin-induced cell death. Additionally, the ferroptosis inhibitors did not restore the electrophysiological function of cardiomyocytes, measured using a multi-electrode array system, and instead slightly accelerated cardiomyocyte beating. Finally, doxorubicin-injected mice treated with ferroptosis inhibitors exhibited significantly reduced survival and increased levels of N-terminal pro B-type natriuretic peptide, a biomarker of heart failure. These findings suggest that inhibiting ferroptosis alone is insufficient to mitigate doxorubicin-induced cardiotoxicity.

Ferroptosis is a lipid peroxidation-induced cell death mechanism that is regulated by amino acid metabolism. Cystine deprivation induces ferroptosis, but ferroptosis execution requires other amino acids. While methionine contributes to several metabolic pathways, including transsulfuration (TS), its role in ferroptosis remains controversial. Here, we report that methionine is required for ferroptosis triggered by cysteine deprivation. Notably, the TS pathway and methionine cycle in lung cancer cells are largely inactive, and methionine is instead funneled into polyamine synthesis via the methionine salvage route. Methionine depletion provokes metabolic shifts that dampen glutamine catabolism via the glutamine-methionine bi-cycle. Furthermore, methionine depletion alters phospholipid metabolism by promoting ACSL4 degradation, limiting polyunsaturated fatty acid (PUFA) incorporation into phospholipids. The methionine cycle intermediate S-adenosylmethionine (SAM) supplementation is sufficient to restore the perturbed metabolic state and ferroptosis sensitivity. Taken together, the results of this study highlight methionine as a key coordinator of ferroptosis through dynamic metabolic remodeling.

In pancreatic ductal adenocarcinoma (PDAC), irinotecan (1μmol/L) chemotherapy triggers a dual-phase autophagy process that drives drug resistance. Although mTOR and autophagy exert suppressive effects on each other, coactivation of mTOR and autophagy has been observed when PDAC cells begin to regrow after treatment. Therefore, we hypothesized that the distinct temporal phases of autophagy are governed by independent upstream pathways. Initially, DNA damage activated AMPK, inducing early autophagy within 24 hours that fueled fatty acid oxidation (FAO), boosting ATP production. After 48 hours, elevated ATP levels inactivated AMPK and activated mTOR, which typically suppresses autophagy. However, autophagy and FAO activity persisted beyond 72 hours of irinotecan treatment via the JNK1–Beclin-1 pathway. This created a paradoxical state in which mTOR and autophagy were coactivated, promoting cell survival under irinotecan treatment. Irinotecan combined with FAO inhibition using KN510713 (a combination of KN510 targeting the carnitine–acylcarnitine transporter and KN713 targeting acetyl-CoA acyltransferase1/2) or FAO gene knockdown blocked autophagy flux and cell growth. FAO inhibition–induced fatty acid accumulation impaired autophagy flux and induced cytotoxicity, leading to cancer cell death. In xenograft models, combining irinotecan with KN510713 significantly prevented tumor regrowth compared with irinotecan alone. These findings suggest that targeting FAO induced by autophagy activation may overcome acquired drug resistance in PDAC while minimizing the toxic side effects associated with systemic inhibition of autophagy in healthy cells. Significance: Combined treatment with irinotecan and fatty acid oxidation inhibition reverses acquired drug resistance driven by autophagy in pancreatic cancer.