Autophagy induced by mechanical stress sensitizes cells to ferroptosis by NCOA4-FTH1 axis

Ferroptosis is an iron-dependent regulated form of cell death implicated in various diseases, including cancers, with its progression influenced by iron-dependent peroxidation of phospholipids and dysregulation of the redox system. Whereas the extracellular matrix of tumors provides mechanical cues influencing tumor initiation and progression, its impact on ferroptosis and its mechanisms remains largely unexplored. In this study, we reveal that heightened mechanical tension sensitizes cells to ferroptosis, whereas decreased mechanics confers resistance. Mechanistically, reduced mechanical tension reduces intracellular free iron levels by enhancing FTH1 protein expression. Additionally, low mechanics significantly diminishes NCOA4, pivotal in mediating FTH1 phase separation-induced ferritinophagy. Targeting NCOA4 effectively rescues ferroptosis susceptibility under low mechanical tension through modulation of FTH1 phase separation-driven autophagy. In conclusion, our findings demonstrate that mechanics regulates iron metabolism via NCOA4-FTH1 phase separation-mediated autophagy, thereby influencing ferroptosis sensitivity and offering promising therapeutic avenues for future exploration. <b>Abbreviations:</b> ACO1: aconitase 1; ATG5: autophagy related 5; DMSO: dimethyl sulfoxide; EGFP: enhanced green fluorescent protein; FACS: fluorescence-activated cell sorting; FER-1: ferrostatin-1; FTH1: ferritin heavy chain 1; FTL: ferritin light chain; GPX4: glutathione peroxidase 4; IR: ionizing radiation; IREB2: iron responsive element binding protein 2; NCOA4: nuclear receptor coactivator 4; NFE2L2: NFE2 like bZIP transcription factor 2; NOPP: norepinephrine; PBS: phosphate-buffered saline; PI: propidium iodide; RSL3: (1S,3 R)-RSL3; TCGA: The Cancer Genome Atlas; WWTR1: WW domain containing transcription regulator 1; YAP1: Yes1 associated transcriptional regulator.

铁死亡（Ferroptosis）是一种铁依赖性的调控性细胞死亡形式，与包括癌症在内的多种疾病密切相关，其进程受磷脂的铁依赖性过氧化作用以及氧化还原系统失调的调控。肿瘤细胞外基质（extracellular matrix）可提供影响肿瘤发生与发展的机械信号，但其对铁死亡的影响及其作用机制在很大程度上仍未被阐明。本研究发现，升高的机械张力会使细胞对铁死亡更为敏感，而降低机械张力则会赋予细胞铁死亡抵抗性。从机制上来说，降低机械张力可通过增强铁蛋白重链1（FTH1）的蛋白表达，降低细胞内游离铁水平。此外，低机械张力会显著减少核受体辅激活因子4（NCOA4）的表达，而NCOA4在介导FTH1相分离诱导的铁蛋白自噬中发挥关键作用。靶向NCOA4可通过调控FTH1相分离驱动的自噬，有效逆转低机械张力下细胞的铁死亡易感性。综上，本研究结果表明，机械张力可通过NCOA4-FTH1相分离介导的自噬调控铁代谢，进而影响铁死亡敏感性，为未来的治疗探索提供了极具前景的方向。<b>缩略词：</b>ACO1：顺乌头酸酶1（aconitase 1）；ATG5：自噬相关5（autophagy related 5）；DMSO：二甲基亚砜（dimethyl sulfoxide）；EGFP：增强型绿色荧光蛋白（enhanced green fluorescent protein）；FACS：荧光激活细胞分选术（fluorescence-activated cell sorting）；FER-1：铁抑素-1（ferrostatin-1）；FTH1：铁蛋白重链1（ferritin heavy chain 1）；FTL：铁蛋白轻链（ferritin light chain）；GPX4：谷胱甘肽过氧化物酶4（glutathione peroxidase 4）；IR：电离辐射（ionizing radiation）；IREB2：铁应答元件结合蛋白2（iron responsive element binding protein 2）；NCOA4：核受体辅激活因子4（nuclear receptor coactivator 4）；NFE2L2：NFE2样bZIP转录因子2（NFE2 like bZIP transcription factor 2）；NOPP：去甲肾上腺素（norepinephrine）；PBS：磷酸盐缓冲液（phosphate-buffered saline）；PI：碘化丙啶（propidium iodide）；RSL3：(1S,3R)-RSL3；TCGA：癌症基因组图谱（The Cancer Genome Atlas）；WWTR1：含WW结构域转录调节因子1（WW domain containing transcription regulator 1）；YAP1：Yes1相关转录调节因子（Yes1 associated transcriptional regulator）