DeAngelo Stephen L, Zhao Liang, Dziechciarz Sofia, Shin Myungsun, Solanki Sumeet, Balia Andrii, El-Derany Marwa O, Castillo Cristina, Qin Yao, Das Nupur K, Bell Hannah N, Paulo Joao A, Zhang Yuezhong, Rossiter Nicholas J, McCulla Elizabeth C, He Jianping, Talukder Indrani, Ng Billy Wai-Lung, Schafer Zachary T, Neamati Nouri, Mancias Joseph D, Koutmos Markos, Shah Yatrik M
Doctoral Program in Cancer Biology, University of Michigan Medical School, Ann Arbor, Michigan.
Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan.
Cancer Res. 2025 Aug 1;85(15):2788-2804. doi: 10.1158/0008-5472.CAN-24-3478.
Ferroptosis is a nonapoptotic form of cell death driven by iron-dependent lipid peroxide accumulation. Colorectal cancer cells feature elevated intracellular iron and reactive oxygen species that heighten ferroptosis sensitivity. The ferroptosis inducer (S)-RSL3 [(1S,3R)-RSL3] is widely described as a selective inhibitor of the selenocysteine-containing enzyme (selenoprotein) glutathione peroxidase 4 (GPX4), which detoxifies lipid peroxides using glutathione. However, through chemical controls using the (R) stereoisomer of RSL3 [(1R,3R)-RSL3] that does not bind GPX4, combined with inducible genetic knockdowns of GPX4 in colorectal cancer cell lines, we revealed in this study that GPX4 dependency does not always align with (S)-RSL3 sensitivity, thereby questioning the current characterization of GPX4 as the primary target of (S)-RSL3. Affinity pull-down mass spectrometry with modified (S)-RSL3 probes identified multiple selenoprotein targets, indicating broad selenoprotein inhibition. Further investigation of the therapeutic potential of broadly disrupting the selenoproteome as a therapeutic strategy in colorectal cancer showed that the selenoprotein inhibitor auranofin, an FDA-approved gold salt, chemically induced oxidative cell death and ferroptosis in colorectal cancer models in vitro and in vivo. Similarly, genetic perturbation of ALKBH8, a tRNA-selenocysteine methyltransferase required for selenoprotein translation, suppressed colorectal cancer growth. In summary, these findings recharacterize the mechanism of (S)-RSL3 beyond GPX4 inhibition and establish selenoproteome disruption as a colorectal cancer therapeutic strategy.
Chemoproteomic profiling reveals that RSL3 functions through pan-selenoprotein inhibition beyond GPX4 and identifies ALKBH8, a tRNA-selenocysteine methyltransferase essential for selenoprotein translation, as a therapeutic target to disrupt redox balance in colorectal cancer. See related commentary by Short, p. 2775.
铁死亡是一种由铁依赖性脂质过氧化物积累驱动的非凋亡性细胞死亡形式。结肠直肠癌细胞具有细胞内铁和活性氧升高的特征，这会增强铁死亡敏感性。铁死亡诱导剂（S）-RSL3 [（1S，3R）-RSL3] 被广泛描述为含硒半胱氨酸酶（硒蛋白）谷胱甘肽过氧化物酶4（GPX4）的选择性抑制剂，GPX4利用谷胱甘肽使脂质过氧化物解毒。然而，通过使用不与GPX4结合的RSL3的（R）立体异构体 [（1R，3R）-RSL3] 进行化学对照，结合结肠直肠癌细胞系中GPX4的诱导性基因敲低，我们在本研究中发现GPX4依赖性并不总是与（S）-RSL3敏感性一致，从而对目前将GPX4表征为（S）-RSL3的主要靶点提出质疑。用修饰的（S）-RSL3探针进行的亲和下拉质谱鉴定了多个硒蛋白靶点，表明对硒蛋白有广泛抑制作用。进一步研究广泛破坏硒蛋白组作为结肠癌治疗策略的治疗潜力表明，硒蛋白抑制剂金诺芬（一种FDA批准的金盐）在体外和体内的结肠癌模型中化学诱导氧化细胞死亡和铁死亡。同样，对硒蛋白翻译所需的tRNA-硒半胱氨酸甲基转移酶ALKBH8的基因干扰抑制了结肠癌的生长。总之，这些发现重新描述了（S）-RSL3除抑制GPX4之外的作用机制，并将破坏硒蛋白组确立为一种结肠癌治疗策略。
化学蛋白质组学分析表明，RSL3通过对GPX4以外的泛硒蛋白抑制发挥作用，并确定了对硒蛋白翻译至关重要的tRNA-硒半胱氨酸甲基转移酶ALKBH8作为破坏结肠癌氧化还原平衡的治疗靶点。见Short的相关评论，第2775页。
