Cytosolic citrate is maintained by SLC25A1 and ACLY and governs ferroptosis susceptibility of cancer cells via FSP1 acetylation

Ferroptosis, an iron-dependent form of programmed cell death characterized by excessive lipid hydroperoxides accumulation, emerges as a promising target in cancer therapy. Among the solute carrier (SLC) superfamily, the cystine/glutamate transporter system antiporter components SLC3A2 and SLC7A11 are known to regulate ferroptosis by facilitating cystine import for ferroptosis inhibition. However, the contribution of additional SLC superfamily members to ferroptosis remains poorly understood. Here, we use a targeted CRISPR-Cas9 screen of the SLC superfamily to identify SLC25A1 as a critical ferroptosis regulator in human cancer cells. SLC25A1 drives citrate export from the mitochondria to the cytosol, where it fuels acetyl-CoA synthesis by ATP citrate lyase (ACLY). This acetyl-CoA supply sustains FSP1 acetylation and prevents its degradation by the proteasome via K29-linked ubiquitin chains. K168 is the primary site of FSP1 acetylation and deacetylation by KAT2B and HDAC3, respectively. Pharmacological inhibition of SLC25A1 and ACLY significantly enhances cancer cell susceptibility to ferroptosis both in vitro and in vivo. Targeting the SLC25A1-ACLY axis is therefore a potential therapeutic strategy for ferroptosis-targeted cancer intervention.

铁死亡（Ferroptosis）是一种铁依赖性程序性细胞死亡形式，以过量脂质过氧化物积累为核心特征，现已成为癌症治疗中颇具前景的干预靶点。在溶质载体（solute carrier, SLC）超家族中，胱氨酸/谷氨酸转运系统的反向转运蛋白组分SLC3A2与SLC7A11，可通过促进胱氨酸摄取来抑制铁死亡，进而调控该过程。然而，其余SLC超家族成员对铁死亡的调控贡献仍不甚明晰。本研究通过针对SLC超家族的靶向CRISPR-Cas9筛选，在人类癌细胞中鉴定出SLC25A1作为关键的铁死亡调控因子。SLC25A1可介导柠檬酸从线粒体向细胞质转运，为细胞质中的ATP柠檬酸裂解酶（ATP citrate lyase, ACLY）合成乙酰辅酶A提供代谢底物。该乙酰辅酶A供应可维持FSP1的乙酰化修饰，并通过K29连接型泛素链抑制其被蛋白酶体降解。K168是FSP1发生乙酰化与去乙酰化的主要位点，分别由KAT2B与HDAC3介导调控。在体外与体内实验中，靶向抑制SLC25A1与ACLY均可显著增强癌细胞对铁死亡的易感性。因此，靶向SLC25A1-ACLY轴有望成为铁死亡靶向癌症干预的潜在治疗策略。