铁过载性细胞死亡（Ferroptosis）是一种铁依赖的非凋亡性细胞死亡形式，涉及各种疾病过程。机制上，谷胱甘肽过氧化物酶4（GPX4）是一种氧化还原酶，能将脂质过氧化物转化为无害的脂肪醇，以保护细胞免受铁过载性细胞死亡的伤害。因此，靶向操纵GPX4可能代表一种有前途的策略，用于调节细胞氧化还原平衡和铁过载性细胞死亡。在本研究中，我们使用PROTAC策略设计、合成和评估了一系列基于RSL3的GPX4降解剂。系统研究了这些化合物与不同的E3连接酶配体、连接链长度和化学组成之间的结构活性关系。其中碳链连接剂和lenalidomide E3连接酶的R17化合物被选为在野生肿瘤细胞或耐药肿瘤细胞中，在纳摩尔水平降解GPX4蛋白的最有效的GPX4降解剂。我们还将R17的POI配体进行了优化，将氯乙酰胺替换为丙酰胺，以构建非共价GPX4降解剂NC-R17。这种非共价修饰导致了适度的GPX4降解活性，并代表了一种有前途的非共价GPX4 PROTACs开发策略。总的来说，我们筛选了一组GPX4降解剂，得到了具有优异蛋白质降解活性的化合物R17，并进一步优化得到了适度疗效的非共价降解剂NC-R17。这些结果为发现针对GPX4的新型抗肿瘤药物奠定了坚实基础，并为设计非共价GPX4 PROTACs提供了概念验证。© 2023 Elsevier Masson SAS。保留所有权利。

Ferroptosis is an iron-dependent, non-apoptotic form of cell death involving in various disease processes. Mechanistically, glutathione peroxidase 4 (GPX4) which belongs to the redox enzyme can convert lipid hydroperoxides into innocuous lipid alcohol to protect cells from ferroptosis. Therefore, targeting manipulation of GPX4 may represent a promising strategy for regulating cell redox homeostasis and ferroptosis. In this work, we designed, synthesized and evaluated a series of RSL3-based GPX4 degraders using PROTAC strategy. The structure-activity relationship of these compounds with different E3 ligase ligands, linker lengths and chemical compositions was systematically studied. Compound R17 with carbon chain linker and lenalidomide E3 ligand was selected as the most potent GPX4 degrader for degrading GPX4 protein in nanomolar level either in wild tumor cells or in drug-resistant tumor cells. We also optimized the POI ligand of R17 with chloracetylamine replaced to propionamide to construct noncovalent GPX4 degrader NC-R17. Such noncovalent modification led to a moderate GPX4 degradation activity and represents a promising strategy for the development of noncovalent GPX4 PROTACs. In general, we screened a set of GPX4 degraders to give the compound R17 with excellent protein degradation activity, and further optimization gave the noncovalent degrader NC-R17 with moderate efficacy. These results lay a firm foundation for the discovery of novel anti-tumor drugs targeting GPX4 and offer the proof of concept for the design of noncovalent GPX4 PROTACs.Copyright © 2023 Elsevier Masson SAS. All rights reserved.