Ferroptosis is a form of regulated cell death triggered by lipid peroxidation after inhibition of the cystine/glutamate antiporter system Xc-. However, key regulators of system Xc- activity in ferroptosis remain undefined. Here, we show that BECN1 plays a hitherto unsuspected role in promoting ferroptosis through directly blocking system Xc- activity via binding to its core component, SLC7A11 (solute carrier family 7 member 11). Knockdown of BECN1 by shRNA inhibits ferroptosis induced by system Xc- inhibitors (e.g., erastin, sulfasalazine, and sorafenib), but not other ferroptosis inducers including RSL3, FIN56, and buthionine sulfoximine. Mechanistically, AMP-activated protein kinase (AMPK)-mediated phosphorylation of BECN1 at Ser90/93/96 is required for BECN1-SLC7A11 complex formation and lipid peroxidation. Inhibition of PRKAA/AMPKα by siRNA or compound C diminishes erastin-induced BECN1 phosphorylation at S93/96, BECN1-SLC7A11 complex formation, and subsequent ferroptosis. Accordingly, a BECN1 phosphorylation-defective mutant (S90,93,96A) reverses BECN1-induced lipid peroxidation and ferroptosis. Importantly, genetic and pharmacological activation of the BECN1 pathway by overexpression of the protein in tumor cells or by administration of the BECN1 activator peptide Tat-beclin 1, respectively, increases ferroptotic cancer cell death (but not apoptosis and necroptosis) in vitro and in vivo in subcutaneous and orthotopic tumor mouse models. Collectively, our work reveals that BECN1 plays a novel role in lipid peroxidation that could be exploited to improve anticancer therapy by the induction of ferroptosis.

中文翻译：

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AMPK 介导的 BECN1 磷酸化通过直接阻断系统 Xc 活性促进铁死亡。


铁死亡是抑制胱氨酸/谷氨酸逆向转运蛋白系统 Xc- 后由脂质过氧化引发的一种受调节细胞死亡形式。然而，铁死亡中Xc-系统活性的关键调节因子仍不清楚。在这里，我们表明 BECN1 通过与其核心成分 SLC7A11（溶质载体家族 7 成员 11）结合直接阻断系统 Xc 活性，在促进铁死亡方面发挥着迄今为止未被怀疑的作用。 shRNA 敲低 BECN1 可抑制系统 Xc 抑制剂（例如erastin、柳氮磺吡啶和索拉非尼）诱导的铁死亡，但不会抑制其他铁死亡诱导剂（包括 RSL3、FIN56 和丁硫氨酸亚磺酰亚胺）诱导的铁死亡。从机制上讲，AMP 激活蛋白激酶 (AMPK) 介导的 BECN1 Ser90/93/96 磷酸化是 BECN1-SLC7A11 复合物形成和脂质过氧化所必需的。 siRNA 或化合物 C 抑制 PRKAA/AMPKα 可减少erastin 诱导的 BECN1 S93/96 磷酸化、BECN1-SLC7A11 复合物形成以及随后的铁死亡。因此，BECN1 磷酸化缺陷突变体 (S90,93,96A) 可逆转 BECN1 诱导的脂质过氧化和铁死亡。重要的是，通过在肿瘤细胞中过表达该蛋白或通过施用 BECN1 激活肽 Tat-beclin 1 分别对 BECN1 通路进行遗传和药理学激活，可在体外和体内增加铁死亡癌细胞死亡（但不增加细胞凋亡和坏死性凋亡）在皮下和原位肿瘤小鼠模型中。总的来说，我们的工作揭示了 BECN1 在脂质过氧化中发挥着新的作用，可用于通过诱导铁死亡来改善抗癌治疗。