Brain‐Targeted HFn‐Cu‐REGO Nanoplatform for Site‐Specific Delivery and Manipulation of Autophagy and Cuproptosis in Glioblastoma

Copper is an essential cofactor for all organisms, and yet it becomes toxic if concentrations exceed a threshold maintained by evolutionarily conserved homeostatic mechanisms. How excess copper induces cell death, however, is unknown. Here, we show in human cells that copper-dependent, regulated cell death is distinct from known death mechanisms and is dependent on mitochondrial respiration. We show that copper-dependent death occurs by means of direct binding of copper to lipoylated components of the tricarboxylic acid (TCA) cycle. This results in lipoylated protein aggregation and subsequent iron-sulfur cluster protein loss, which leads to proteotoxic stress and ultimately cell death. These findings may explain the need for ancient copper homeostatic mechanisms. Cell death is an essential, finely tuned process that is critical for the removal of damaged and superfluous cells. Multiple forms of programmed and nonprogrammed cell death have been identified, including apoptosis, ferroptosis, and necroptosis. Tsvetkov et al . investigated whether abnormal copper ion elevations may sensitize cells toward a previously unidentified death pathway (see the Perspective by Kahlson and Dixon). By performing CRISPR/Cas9 screens, several genes were identified that could protect against copper-induced cell killing. Using genetically modified cells and a mouse model of a copper overload disorder, the researchers report that excess copper promotes the aggregation of lipoylated proteins and links mitochondrial metabolism to copper-dependent death. —PNK Lipoylation determines sensitivity to copper-induced cell death. Show more

The cystine/glutamate antiporter SLC7A11 (also commonly known as xCT) functions to import cystine for glutathione biosynthesis and antioxidant defense and is overexpressed in multiple human cancers. Recent studies revealed that SLC7A11 overexpression promotes tumor growth partly through suppressing ferroptosis, a form of regulated cell death induced by excessive lipid peroxidation. However, cancer cells with high expression of SLC7A11 (SLC7A11 high ) also have to endure the significant cost associated with SLC7A11-mediated metabolic reprogramming, leading to glucose- and glutamine-dependency in SLC7A11 high cancer cells, which presents potential metabolic vulnerabilities for therapeutic targeting in SLC7A11 high cancer. In this review, we summarize diverse regulatory mechanisms of SLC7A11 in cancer, discuss ferroptosis-dependent and -independent functions of SLC7A11 in promoting tumor development, explore the mechanistic basis of SLC7A11-induced nutrient dependency in cancer cells, and conceptualize therapeutic strategies to target SLC7A11 in cancer treatment. This review will provide the foundation for further understanding SLC7A11 in ferroptosis, nutrient dependency, and tumor biology and for developing novel effective cancer therapies. Show more

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death caused by lipid peroxidation, which is controlled by integrated oxidation and antioxidant systems. The iron-containing enzyme lipoxygenase is the main promoter of ferroptosis by producing lipid hydroperoxides, and its function relies on the activation of ACSL4-dependent lipid biosynthesis. In contrast, the selenium-containing enzyme GPX4 is currently recognized as a central repressor of ferroptosis, and its activity depends on glutathione produced from the activation of the cystine-glutamate antiporter SLC7A11. Many metabolic (especially involving iron, lipids, and amino acids) and degradation pathways (macroautophagy/autophagy and the ubiquitin-proteasome system) orchestrate the complex ferroptotic response through direct or indirect regulation of iron accumulation or lipid peroxidation. Although the detailed mechanism of membrane injury during ferroptosis remains a mystery, ESCRT III-mediated plasma membrane repair can make cells resistant to ferroptosis. Here, we review the recent rapid progress in understanding the molecular mechanisms of ferroptosis and focus on the epigenetic, transcriptional, and posttranslational regulation of this process.Abbreviations: 2ME: beta-mercaptoethanol; α-KG: α-ketoglutarate; ccRCC: clear cell renal cell carcinoma; EMT: epithelial-mesenchymal transition; FAO: fatty acid beta-oxidation; GSH: glutathione; MEFs: mouse embryonic fibroblasts; MUFAs: monounsaturated fatty acids; NO: nitric oxide; NOX: NADPH oxidase; PPP: pentose phosphate pathway; PUFA: polyunsaturated fatty acid; RCD: regulated cell death; RNS: reactive nitrogen species; ROS: reactive oxygen species; RTAs: radical-trapping antioxidants; UPS: ubiquitin-proteasome system; UTR: untranslated region. Show more