Ferrostatins inhibit oxidative lipid damage and cell death in diverse disease models

Mitochondrial Regulation of Ferroptosis in Cancer Therapy

Ferroptosis, characterized by glutamate overload, glutathione depletion, and cysteine/cystine deprivation during iron- and oxidative-damage-dependent cell death, is a particular mode of regulated cell death. It is expected to effectively treat cancer through its tumor-suppressor function, as mitochondria are the intracellular energy factory and a binding site of reactive oxygen species production, closely related to ferroptosis. This review summarizes relevant research on the mechanisms of ferroptosis, highlights mitochondria's role in it, and collects and classifies the inducers of ferroptosis. A deeper understanding of the relationship between ferroptosis and mitochondrial function may provide new strategies for tumor treatment and drug development based on ferroptosis.

Identification of potential necroinflammation-associated necroptosis-related biomarkers for delayed graft function and renal allograft failure: a machine learning-based exploration in the framework of predictive, preventive, and personalized medicine

Delayed graft function (DGF) is one of the key post-operative challenges for a subset of kidney transplantation (KTx) patients. Graft survival is significantly lower in recipients who have experienced DGF than in those who have not. Assessing the risk of chronic graft injury, predicting graft rejection, providing personalized treatment, and improving graft survival are major strategies for predictive, preventive, and personalized medicine (PPPM/3PM) to promote the development of transplant medicine. However, since PPPM aims to accurately identify disease by integrating multiple omics, current methods to predict DGF and graft survival can still be improved. Renal ischemia/reperfusion injury (IRI) is a pathological process experienced by all KTx recipients that can result in varying occurrences of DGF, chronic rejection, and allograft failure depending on its severity. During this process, a necroinflammation-mediated necroptosis-dependent secondary wave of cell death significantly contributes to post-IRI tubular cell loss. In this article, we obtained the expression matrices and corresponding clinical data from the GEO database. Subsequently, nine differentially expressed necroinflammation-associated necroptosis-related genes (NiNRGs) were identified by correlation and differential expression analysis. The subtyping of post-KTx IRI samples relied on consensus clustering; the grouping of prognostic risks and the construction of predictive models for DGF (the area under the receiver operating characteristic curve (AUC) of the internal validation set and the external validation set were 0.730 and 0.773, respectively) and expected graft survival after a biopsy (the internal validation set's 1-year AUC: 0.770; 2-year AUC: 0.702; and 3-year AUC: 0.735) were based on the least absolute shrinkage and selection operator regression algorithms. The results of the immune infiltration analysis showed a higher infiltration abundance of myeloid immune cells, especially neutrophils, macrophages, and dendritic cells, in the cluster A subtype and prognostic high-risk groups. Therefore, in the framework of PPPM, this work provides a comprehensive exploration of the early expression landscape, related pathways, immune features, and prognostic impact of NiNRGs in post-KTx patients and assesses their capabilities as.predictors of post-KTx DGF and graft loss,targets of the vicious loop between regulated tubular cell necrosis and necroinflammation for targeted secondary and tertiary prevention, andreferences for personalized immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-023-00320-w.

AKT activation because of PTEN loss upregulates xCT via GSK3β/NRF2, leading to inhibition of ferroptosis in PTEN-mutant tumor cells

Here, we show that the tumor suppressor phosphatase and tensin homolog deleted from chromosome 10 (PTEN) sensitizes cells to ferroptosis, an iron-dependent form of cell death, by restraining the expression and activity of the cystine/glutamate antiporter system Xc- (xCT). Loss of PTEN activates AKT kinase to inhibit GSK3β, increasing NF-E2 p45-related factor 2 (NRF2) along with transcription of one of its known target genes encoding xCT. Elevated xCT in Pten-null mouse embryonic fibroblasts increases the flux of cystine transport and synthesis of glutathione, which enhances the steady-state levels of these metabolites. A pan-cancer analysis finds that loss of PTEN shows evidence of increased xCT, and PTEN-mutant cells are resistant to ferroptosis as a consequence of elevated xCT. These findings suggest that selection of PTEN mutation during tumor development may be due to its ability to confer resistance to ferroptosis in the setting of metabolic and oxidative stress that occurs during tumor initiation and progression.

Ferroptosis and multi-organ complications in COVID-19: mechanisms and potential therapies

COVID-19 is an infectious disease caused by SARS-CoV-2, with respiratory symptoms as primary manifestations. It can progress to severe illness, leading to respiratory failure and multiple organ dysfunction. Recovered patients may experience persistent neurological, respiratory, or cardiovascular symptoms. Mitigating the multi-organ complications of COVID-19 has been highlighted as a crucial part of fighting the epidemic. Ferroptosis is a type of cell death linked to altered iron metabolism, glutathione depletion, glutathione peroxidase 4 (GPX4) inactivation, and increased oxidative stress. Cell death can prevent virus replication, but uncontrolled cell death can also harm the body. COVID-19 patients with multi-organ complications often exhibit factors related to ferroptosis, suggesting a possible connection. Ferroptosis inhibitors can resist SARS-CoV-2 infection from damaging vital organs and potentially reduce COVID-19 complications. In this paper, we outline the molecular mechanisms of ferroptosis and, based on this, discuss multi-organ complications in COVID-19, then explore the potential of ferroptosis inhibitors as a supplementary intervention for COVID-19. This paper will provide a reference for the possible treatment of SARS-CoV-2 infected disease to reduce the severity of COVID-19 and its subsequent impact.

Ferrostatin-1 alleviates ventilator-induced lung injury by inhibiting ferroptosis

Ventilator-induced lung injury (VILI) has become an increasingly common complication in the clinic concerning mechanical ventilation. Previous research showed that VILI is the result of a response to cascade inflammation; however, the inflammatory mechanism involved remains unclear. As a newly recognized form of cell death, ferroptosis can release damage-related molecules (DAMPs) to trigger and amplify the inflammatory response and is involved in several inflammatory diseases. The present study aimed to investigate a previously unrecognized role of ferroptosis in VILI. A mouse model of VILI and a model of cyclic stretching (CS)-induced lung epithelial cell injury were established. Mice and cells were pretreated with ferrostain-1, an inhibitor of ferroptosis. Lung tissue and cells were then harvested to determine lung injury, inflammatory responses, indicators and protein expression associated with ferroptosis. Compared to the control group, mice subjected to high tidal volumes (HTV) for 4 h showed more severe pulmonary edema and inflammation and the activation of ferroptosis. Ferrostain-1 significantly ameliorated histological injury and inflammation in the VILI mouse and alleviated CS-induced lung epithelial cell injury. Mechanistically, ferrostain-1 markedly limited the activation of ferroptosis and recovered functionality of the SLC7A11/GPX4 axis both in vitro and in vivo, thus demonstrating its potential as a novel therapeutic target for VILI.

vPIF-1 is an insulin-like antiferroptotic viral peptide

Iridoviridae, such as the lymphocystis disease virus-1 (LCDV-1) and other viruses, encode viral insulin-like peptides (VILPs) which are capable of triggering insulin receptors (IRs) and insulin-like growth factor receptors. The homology of VILPs includes highly conserved disulfide bridges. However, the binding affinities to IRs were reported to be 200- to 500-fold less effective compared to the endogenous ligands. We therefore speculated that these peptides also have noninsulin functions. Here, we report that the LCDV-1 VILP can function as a potent and highly specific inhibitor of ferroptosis. Induction of cell death by the ferroptosis inducers erastin, RSL3, FIN56, and FINO2 and nonferroptotic necrosis produced by the thioredoxin-reductase inhibitor ferroptocide were potently prevented by LCDV-1, while human insulin had no effect. Fas-induced apoptosis, necroptosis, mitotane-induced cell death and growth hormone-releasing hormone antagonist-induced necrosis were unaffected, suggesting the specificity to ferroptosis inhibition by the LCDV-1 VILP. Mechanistically, we identified the viral C-peptide to be required for inhibition of lipid peroxidation and ferroptosis inhibition, while the human C-peptide exhibited no antiferroptotic properties. In addition, the deletion of the viral C-peptide abolishes radical trapping activity in cell-free systems. We conclude that iridoviridae, through the expression of insulin-like viral peptides, are capable of preventing ferroptosis. In analogy to the viral mitochondrial inhibitor of apoptosis and the viral inhibitor of RIP activation (vIRA) that prevents necroptosis, we rename the LCDV-1 VILP a viral peptide inhibitor of ferroptosis-1. Finally, our findings indicate that ferroptosis may function as a viral defense mechanism in lower organisms.

Ferroptosis as an emerging therapeutic target in liver diseases

Ferroptosis is an iron-dependently nonapoptotic cell death characterized by excessive accumulation of lipid peroxides and cellular iron metabolism disturbances. Impaired iron homeostasis and dysregulation of metabolic pathways are contributors to ferroptosis. As a major metabolic hub, the liver synthesizes and transports plasma proteins and endogenous fatty acids. Also, it acts as the primary location of iron storage for hepcidin generation and secretion. To date, although the intricate correlation between ferroptosis and liver disorders needs to be better defined, there is no doubt that ferroptosis participates in the pathogenesis of liver diseases. Accordingly, pharmacological induction and inhibition of ferroptosis show significant potential for the treatment of hepatic disorders involved in lipid peroxidation. In this review, we outline the prominent features, molecular mechanisms, and modulatory networks of ferroptosis and its physiopathologic functions in the progression of liver diseases. Further, this review summarizes the underlying mechanisms by which ferroptosis inducers and inhibitors ameliorate liver diseases. It is noteworthy that natural active ingredients show efficacy in preclinical liver disease models by regulating ferroptosis. Finally, we analyze crucial concepts and urgent issues concerning ferroptosis as a novel therapeutic target in the diagnosis and therapy of liver diseases.

Emerging Role of Ferroptosis in Diabetic Kidney Disease: Molecular Mechanisms and Therapeutic Opportunities

Diabetic kidney disease (DKD) is one of the most common and severe microvascular complications of diabetes mellitus (DM), and has become the leading cause of end-stage renal disease (ESRD) worldwide. Although the exact pathogenic mechanism of DKD is still unclear, programmed cell death has been demonstrated to participate in the occurrence and development of diabetic kidney injury, including ferroptosis. Ferroptosis, an iron-dependent form of cell death driven by lipid peroxidation, has been identified to play a vital role in the development and therapeutic responses of a variety of kidney diseases, such as acute kidney injury (AKI), renal cell carcinoma and DKD. In the past two years, ferroptosis has been well investigated in DKD patients and animal models, but the specific mechanisms and therapeutic effects have not been fully revealed. Herein, we reviewed the regulatory mechanisms of ferroptosis, summarized the recent findings associated with the involvement of ferroptosis in DKD, and discussed the potential of ferroptosis as a promising target for DKD treatment, thereby providing a valuable reference for basic study and clinical therapy of DKD.

Neutrophil metabolomics in severe COVID-19 reveal GAPDH as a suppressor of neutrophil extracellular trap formation

Severe COVID-19 is characterized by an increase in the number and changes in the function of innate immune cells including neutrophils. However, it is not known how the metabolome of immune cells changes in patients with COVID-19. To address these questions, we analyzed the metabolome of neutrophils from patients with severe or mild COVID-19 and healthy controls. We identified widespread dysregulation of neutrophil metabolism with disease progression including in amino acid, redox, and central carbon metabolism. Metabolic changes in neutrophils from patients with severe COVID-19 were consistent with reduced activity of the glycolytic enzyme GAPDH. Inhibition of GAPDH blocked glycolysis and promoted pentose phosphate pathway activity but blunted the neutrophil respiratory burst. Inhibition of GAPDH was sufficient to cause neutrophil extracellular trap (NET) formation which required neutrophil elastase activity. GAPDH inhibition increased neutrophil pH, and blocking this increase prevented cell death and NET formation. These findings indicate that neutrophils in severe COVID-19 have an aberrant metabolism which can contribute to their dysfunction. Our work also shows that NET formation, a pathogenic feature of many inflammatory diseases, is actively suppressed in neutrophils by a cell-intrinsic mechanism controlled by GAPDH.

Zooming in and out of ferroptosis in human disease

Ferroptosis is defined as an iron-dependent regulated form of cell death driven by lipid peroxidation. In the past decade, it has been implicated in the pathogenesis of various diseases that together involve almost every organ of the body, including various cancers, neurodegenerative diseases, cardiovascular diseases, lung diseases, liver diseases, kidney diseases, endocrine metabolic diseases, iron-overload-related diseases, orthopedic diseases and autoimmune diseases. Understanding the underlying molecular mechanisms of ferroptosis and its regulatory pathways could provide additional strategies for the management of these disease conditions. Indeed, there are an expanding number of studies suggesting that ferroptosis serves as a bona-fide target for the prevention and treatment of these diseases in relevant pre-clinical models. In this review, we summarize the progress in the research into ferroptosis and its regulatory mechanisms in human disease, while providing evidence in support of ferroptosis as a target for the treatment of these diseases. We also discuss our perspectives on the future directions in the targeting of ferroptosis in human disease.

Ferroptotic mechanisms and therapeutic targeting of iron metabolism and lipid peroxidation in the kidney

Ferroptosis is a mechanism of regulated necrotic cell death characterized by iron-dependent, lipid peroxidation-driven membrane destruction that can be inhibited by glutathione peroxidase 4. Morphologically, it is characterized by cellular, organelle and cytoplasmic swelling and the loss of plasma membrane integrity, with the release of intracellular components. Ferroptosis is triggered in cells with dysregulated iron and thiol redox metabolism, whereby the initial robust but selective accumulation of hydroperoxy polyunsaturated fatty acid-containing phospholipids is further propagated through enzymatic and non-enzymatic secondary mechanisms, leading to formation of oxidatively truncated electrophilic species and their adducts with proteins. Thus, ferroptosis is dependent on the convergence of iron, thiol and lipid metabolic pathways. The kidney is particularly susceptible to redox imbalance. A growing body of evidence has linked ferroptosis to acute kidney injury in the context of diverse stimuli, such as ischaemia-reperfusion, sepsis or toxins, and to chronic kidney disease, suggesting that ferroptosis may represent a novel therapeutic target for kidney disease. However, further work is needed to address gaps in our understanding of the triggers, execution and spreading mechanisms of ferroptosis.

Defense systems to avoid ferroptosis caused by lipid peroxidation-mediated membrane damage

The presence of hydrogen peroxide along with ferrous iron produces hydroxyl radicals that preferably oxidize polyunsaturated fatty acids (PUFA) to alkyl radicals (L•). The reaction of L• with an oxygen molecule produces lipid peroxyl radical (LOO•) that collectively trigger chain reactions, which results in the accumulation of lipid peroxidation products (LOOH). Oxygenase enzymes, such as lipoxygenase, also stimulate the peroxidation of PUFA. The production of phospholipid hydroperoxides (P-LOOH) can result in the destruction of the architecture of cell membranes and ultimate cell death. This iron-dependent regulated cell death is generally referred to as ferroptosis. Radical scavengers, which include tocopherol and nitric oxide (•NO), react with lipid radicals and terminate the chain reaction. When tocopherol reductively detoxifies lipid radicals, the resultant tocopherol radicals are recycled via reduction by coenzyme Q or ascorbate. CoQ radicals are reduced back by the anti-ferroptotic enzyme FSP1. •NO reacts with lipid radicals and produces less reactive nitroso compounds. The resulting P-LOOH is reductively detoxified by the action of glutathione peroxidase 4 (GPX4) or peroxiredoxin 6 (PRDX6). The hydrolytic removal of LOOH from P-LOOH by calcium-independent phospholipase A2 leads the preservation of membrane structure. While the expression of such protective genes or the presence of these anti-oxidant compounds serve to maintain a healthy condition, tumor cells employ them to make themselves resistant to anti-tumor treatments. Thus, these defense mechanisms against ferroptosis are protective in ordinary cells but are also potential targets for cancer treatment.

Protective effect of curcumin on hepatolenticular degeneration through copper excretion and inhibition of ferroptosis

BACKGROUND

Hepatolenticular degeneration (HLD) is an autosomal recessive disorder concerning copper metabolism. Copper overload is also accompanied by iron overload in HLD patients, which can lead to ferroptosis. Curcumin, the active component in turmeric, has the potential to inhibit ferroptosis.

PURPOSE

The current study proposed a systematic investigation of the protective effects of curcumin against HLD and the underlying mechanisms.

METHODS

The protective effect of curcumin on toxic milk (TX) mice was studied. Liver tissue was observed via hematoxylin-eosin (H&E) staining and the ultrastructure of the liver tissue was observed through transmission electron microscopy. Copper levels in the tissues, serum, and metabolites were measured by atomic absorption spectrometry (AAS). In addition, serum and liver indicators were evaluated. In cellular experiments, the effect of curcumin on the viability of rat normal liver cells (BRL-3A) was determined via the 3-[4,5-dimethylthiazol-2-yl)]-2,5-diphenyltetrazolium bromide (MTT) assay. Cell and mitochondrial morphology were observed in curcumin-mediated HLD model cells. The intracellular copper ion fluorescence intensity was observed via fluorescence microscopy, and intracellular copper iron content was detected using AAS. Further, oxidative stress indicators were evaluated. Cellular reactive oxygen species (ROS) and cellular mitochondrial membrane potential were examined via flow cytometry. Furthermore, the expression levels of nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and glutathione peroxidase 4 (GPX4) were determined via western blotting (WB).

RESULTS

The histopathology of the liver confirmed the hepatoprotective effects of curcumin. Curcumin improved copper metabolism in TX mice. Both serum liver enzyme markers and antioxidant enzyme levels indicated the protective effect of curcumin against HLD-related liver injury. The MTT assay results showed that curcumin was protective against excess copper-induced injury. Curcumin improved the morphology of HLD model cells and their mitochondrial morphology. The Cu²⁺ fluorescent probe and the AAS results indicated that curcumin reduced Cu²⁺ content in HLD hepatocytes. In addition, curcumin improved oxidative stress levels and prevented the decline of mitochondrial membrane potential in HLD model cells. The ferroptosis inducer Erastin reversed these effects of curcumin. WB revealed that curcumin promoted Nrf2, HO-1, and GPX4 protein expression in HLD model cells, and the Nrf2 inhibitor ML385 reversed the effects of curcumin.

CONCLUSION

Curcumin demonstrates a protective role by expelling copper and inhibiting ferroptosis, activating the Nrf2/HO-1/GPX4 signaling pathway in HLD.

Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

Ferroptosis regulates key signaling pathways in gastrointestinal tumors: Underlying mechanisms and therapeutic strategies

Ferroptosis is an emerging novel form of non-apoptotic, regulated cell death that is heavily dependent on iron and characterized by rupture in plasma membrane. Ferroptosis is distinct from other regulated cell death modalities at the biochemical, morphological, and molecular levels. The ferroptotic signature includes high membrane density, cytoplasmic swelling, condensed mitochondrial membrane, and outer mitochondrial rupture with associated features of accumulation of reactive oxygen species and lipid peroxidation. The selenoenzyme glutathione peroxidase 4, a key regulator of ferroptosis, greatly reduces the lipid overload and protects the cell membrane against oxidative damage. Ferroptosis exerts a momentous role in regulating cancer signaling pathways and serves as a therapeutic target in cancers. Dysregulated ferroptosis orchestrates gastrointestinal (GI) cancer signaling pathways leading to GI tumors such as colonic cancer, pancreatic cancer, and hepatocellular carcinoma. Crosstalk exists between ferroptosis and other cell death modalities. While apoptosis and autophagy play a detrimental role in tumor progression, depending upon the factors associated with tumor microenvironment, ferroptosis plays a decisive role in either promoting tumor growth or suppressing it. Several transcription factors, such as TP53, activating transcription factors 3 and 4, are involved in influencing ferroptosis. Importantly, several molecular mediators of ferroptosis, such as p53, nuclear factor erythroid 2-related factor 2/heme oxygenase-1, hypoxia inducible factor 1, and sirtuins, coordinate with ferroptosis in GI cancers. In this review, we elaborated on key molecular mechanisms of ferroptosis and the signaling pathways that connect ferroptosis to GI tumors.

Structure Revisions of Phenolic Bisabolane Sesquiterpenes and a Ferroptosis Inhibitor from the Marine-Derived Fungus Aspergillus versicolor YPH93

Seven new phenolic bisabolane sesquiterpenoids (1-7), along with 10 biogenetically related analogues (8-17), were obtained from the deep-sea-derived fungus Aspergillus versicolor YPH93. The structures were elucidated based on extensive analyses of the spectroscopic data. Compounds 1-3 are the first examples of phenolic bisabolanes that contain two hydroxy groups attached to the pyran ring. The structures of sydowic acid derivatives (1-6 and 8-10) were carefully studied, leading to the structure revisions of six known analogues, including a revision of the absolute configuration for sydowic acid (10). All metabolites were evaluated for their effects on ferroptosis. Compound 7 exerted inhibition on erastin/RSL3-induced ferroptosis with EC50 values ranging from 2 to 4 μM, while it exhibited no effects on TNFα-induced necroptosis or H2O2-induced cell necrosis.

Revisiting the intersection of microglial activation and neuroinflammation in Alzheimer's disease from the perspective of ferroptosis

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by chronic neuroinflammation with amyloid beta-protein deposition and hyperphosphorylated tau protein. The typical clinical manifestation of AD is progressive memory impairment, and AD is considered a multifactorial disease with various etiologies (genetic factors, aging, lifestyle, etc.) and complicated pathophysiological processes. Previous research identified that neuroinflammation and typical microglial activation are significant mechanisms underlying AD, resulting in dysfunction of the nervous system and progression of the disease. Ferroptosis is a novel modality involved in this process. As an iron-dependent form of cell death, ferroptosis, characterized by iron accumulation, lipid peroxidation, and irreversible plasma membrane disruption, promotes AD by accelerating neuronal dysfunction and abnormal microglial activation. In this case, disturbances in brain iron homeostasis and neuronal ferroptosis aggravate neuroinflammation and lead to the abnormal activation of microglia. Abnormally activated microglia release various pro-inflammatory factors that aggravate the dysregulation of iron homeostasis and neuroinflammation, forming a vicious cycle. In this review, we first introduce ferroptosis, microglia, AD, and their relationship. Second, we discuss the nonnegligible role of ferroptosis in the abnormal microglial activation involved in the chronic neuroinflammation of AD to provide new ideas for the identification of potential therapeutic targets for AD.

Future Perspectives of Oxytosis/Ferroptosis Research in Neurodegeneration Diseases

The current report briefly summarizes the existing hypotheses and relevant evidence of oxytosis/ferroptosis-mediated cell death and outlines future perspectives of neurodegeneration research. Furthermore, it highlights the potential application of specific markers (e.g., activators, inhibitors, redox modulators, antioxidants, iron chelators) in the study of regulatory mechanisms of oxytosis/ferroptosis. It appears that these markers may be a suitable option for experimental investigations targeting key pathways of oxytosis/ferroptosis, such as the inhibition of the cystine/glutamate antiporter/glutathione/glutathione peroxidase 4 axis, glutamate oxidative toxicity, glutathione depletion, iron dyshomeostasis, iron-mediated lipid peroxidation, and others. From a clinical perspective, an innovative research approach to investigate the oxytosis/ferroptosis pathways in cells of the central nervous system and their relationship to neurodegenerative diseases is desirable. It is necessary to expand the existing knowledge about the molecular mechanisms of neurodegenerative diseases and to provide innovative diagnostic procedures to prevent their progression, as well as to develop effective neuroprotective treatment. The importance of preclinical studies focused predominantly on oxytosis/ferroptosis inhibitors (iron chelators or lipoxygenase inhibitors and lipophilic antioxidants) that could chelate iron or inhibit lipid peroxidation is also discussed. Specifically, this targeted inhibition of neuronal death could represent a potential therapeutic strategy for some neurodegenerative diseases.

Disease-associated metabolic pathways affected by heavy metals and metalloid

Increased exposure to environmental heavy metals and metalloids and their associated toxicities has become a major threat to human health. Hence, the association of these metals and metalloids with chronic, age-related metabolic disorders has gained much interest. The underlying molecular mechanisms that mediate these effects are often complex and incompletely understood. In this review, we summarize the currently known disease-associated metabolic and signaling pathways that are altered following different heavy metals and metalloids exposure, alongside a brief summary of the mechanisms of their impacts. The main focus of this study is to explore how these affected pathways are associated with chronic multifactorial diseases including diabetes, cardiovascular diseases, cancer, neurodegeneration, inflammation, and allergic responses upon exposure to arsenic (As), cadmium (Cd), chromium (Cr), iron (Fe), mercury (Hg), nickel (Ni), and vanadium (V). Although there is considerable overlap among the different heavy metals and metalloids-affected cellular pathways, these affect distinct metabolic pathways as well. The common pathways may be explored further to find common targets for treatment of the associated pathologic conditions.

Structure-activity relationship study of RSL3-based GPX4 degraders and its potential noncovalent optimization

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.

Self-adaptive nanoassembly enabling turn-on hypoxia illumination and periphery/center closed-loop tumor eradication

Solid tumors are regarded as complex evolving systems rather than simple diseases. Self-adaptive synthetic therapeutics are required to cope with the challenges of entire tumors; however, limitations in accurate positioning and destruction of hypoxic niches seriously hinder complete tumor eradication. In this study, we engineer a molecular nanoassembly of sorafenib and a hypoxia-sensitive cyanine probe (CNO) to facilitate periphery/center synergistic cancer therapies. The self-adaptive nanoassembly with cascade drug release features not only effectively kills the peripheral tumor cells in normoxic rims but precisely illuminates hypoxic niches following the reduction of CNO by nitroreductase. More important, CNO is found to synergistically induce tumor ferroptosis with sorafenib via nicotinamide adenine dinucleotide phosphate (NADPH) depletion in hypoxic niches. As expected, the engineered nanoassembly demonstrates self-adaptive hypoxic illumination and periphery/center synergetic tumor eradication in colon and breast cancer BALB/c mouse xenograft models. This study advances turn-on hypoxia illumination and chemo-ferroptosis toward clinical applicability.

Ferritinophagy in the etiopathogenic mechanism of related diseases

Iron is an essential trace element that is involved in a variety of physiological processes. Ferritinophagy is selective autophagy mediated by nuclear receptor coactivator 4 (NCOA4), which regulates iron homeostasis in the body. Upon iron depletion or starvation, ferritinophagy is activated, releasing large amounts of Fe²⁺ and increasing reactive oxygen species (ROS), leading to ferroptosis. This plays a significant role in the etiopathogenesis of many diseases, such as metabolic diseases, neurodegenerative diseases, infectious diseases, tumors, cardiomyopathy, and ischemia-reperfusion ischemia-reperfusion injury. Here, we first review the regulation and functions of ferritinophagy and then describe its involvement in different diseases, with hopes of providing new understanding and insights into iron metabolism and iron disorder-related diseases and the therapeutic opportunity for targeting ferritinophagy.

Inhibition of spinal ferroptosis-like cell death alleviates hyperalgesia and spontaneous pain in a mouse model of bone cancer pain

Bone cancer pain (BCP) impairs patients' quality of life. However, the underlying mechanisms are still unclear. This study investigated the role of spinal interneuron death using a pharmacological inhibitor of ferroptosis in a mouse model of BCP. Lewis lung carcinoma cells were inoculated into the femur, resulting in hyperalgesia and spontaneous pain. Biochemical analysis revealed that spinal levels of reactive oxygen species and malondialdehyde were increased, while those of superoxide dismutase were decreased. Histological analysis showed the loss of spinal GAD65+ interneurons and provided ultrastructural evidence of mitochondrial shrinkage. Pharmacologic inhibition of ferroptosis using ferrostatin-1 (FER-1, 10 mg/kg, intraperitoneal for 20 consecutive days) attenuated ferroptosis-associated iron accumulation and lipid peroxidation and alleviated BCP. Furthermore, FER-1 inhibited the pain-associated activation of ERK1/2 and COX-2 expression and prevented the loss of GABAergic interneurons. Moreover, FER-1 improved analgesia by the COX-2 inhibitor Parecoxib. Taken together, this study shows that pharmacological inhibition of ferroptosis-like cell death of spinal interneurons alleviates BCP in mice. The results suggest that ferroptosis is a potential therapeutic target in patients suffering on BCP and possibly other types of pain.

Effect of deferoxamine and ferrostatin-1 on salivary gland dysfunction in ovariectomized rats

The mechanism underlying xerostomia after menopause has not yet been fully elucidated. This study aimed to investigate the mechanism of xerostomia and the effect of the ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (FER) on salivary gland dysfunction in a postmenopausal animal model. Twenty-four female Sprague-Dawley rats were randomly divided into four groups: a SHAM group (n = 6, sham-operated rats), an OVX group (n = 6, ovariectomized rats), an FER group (n = 6, ovariectomized rats injected intraperitoneally with FER), and a DFO group (n = 6, ovariectomized rats injected intraperitoneally with DFO). GPX4 activity, iron accumulation, lipid peroxidation, inflammation, fibrosis, and salivary gland function were analyzed. Recovery of GPX4 activity and a decrease in iron accumulation and cytosolic MDA + HAE were observed in the DFO group. In addition, collagen I, collagen III, TGF-β, IL-6, TNF-α, and TGF-β levels were decreased in the DFO group compared to the OVX group. Recovery of GPX4 activity and the morphology of mitochondria, and reduction of cytosolic MDA + HAE were also observed in the FER group. In addition, decreased expression of inflammatory cytokines and fibrosis markers and increased expression of AQP5 were observed in both the DFO and FER groups. Postmenopausal salivary gland dysfunction is associated with ferroptosis, and DFO and FER may reverse the postmenopausal salivary gland dysfunction after menopause. DFO and FER are hence considered promising treatments for postmenopausal xerostomia.

Ferroptosis: A flexible constellation of related biochemical mechanisms

It is common to think about and depict biological processes as being governed by fixed pathways with specific components interconnected by concrete positive and negative interactions. However, these models may fail to effectively capture the regulation of cell biological processes that are driven by chemical mechanisms that do not rely absolutely on specific metabolites or proteins. Here, we discuss how ferroptosis, a non-apoptotic cell death mechanism with emerging links to disease, may be best understood as a highly flexible mechanism that can be executed and regulated by many functionally related metabolites and proteins. The inherent plasticity of ferroptosis has implications for how to define and study this mechanism in healthy and diseased cells and organisms.

Ferroptosis and Neurodegenerative Diseases: Insights into the Regulatory Roles of SLC7A11

Programed cell death plays a key role in promoting human development and maintaining homeostasis. Ferroptosis is a recently identified pattern of programmed cell death that is closely associated with the onset and progression of neurodegenerative diseases. Ferroptosis is mainly caused by the intracellular accumulation of iron-dependent lipid peroxides. The cysteine/glutamate antibody Solute carrier family 7 member 11 (SLC7A11, also known as xCT) functions to import cysteine for glutathione biosynthesis and antioxidant defense. SLC7A11 has a significant impact on ferroptosis, and inhibition of SLC7A11 expression promotes ferroptosis. Moreover, SLC7A11 is also closely associated with neurodegenerative diseases. In this paper, we summarize the relationship between ferroptosis and neurodegenerative diseases and the role of SLC7A11 during this process. The various regulatory mechanisms of SLC7A11 are also discussed. In conclusion, we are looking forward to a theoretical basis for further understanding the occurrence and development of ferroptosis in SLC7A11 and neurodegenerative diseases, and to seek new clues for the treatment of neurodegenerative diseases.

Discovery of a Potent Chloroacetamide GPX4 Inhibitor with Bioavailability to Enable Target Engagement in Mice, a Potential Tool Compound for Inducing Ferroptosis In Vivo

Compounds that inhibit glutathione peroxidase 4 (GPX4) hold promise as cancer therapeutics in their ability to induce a form of nonapoptotic cell death called ferroptosis. Our research identified 24, a structural analog of the potent GPX4 inhibitor RSL3, that has much better plasma stability (t_1/2 > 5 h in mouse plasma). The bioavailability of 24 provided efficacious plasma drug concentrations with IP dosing, thus enabling in vivo studies to assess tolerability and efficacy. An efficacy study in mouse using a GPX4-sensitive tumor model found that doses of 24 up to 50 mg/kg were tolerated for 20 days but had no effect on tumor growth, although partial target engagement was observed in tumor homogenate.

TRIM21 ubiquitylates GPX4 and promotes ferroptosis to aggravate ischemia/reperfusion-induced acute kidney injury

AIMS

This study aims to verify the molecular mechanism that Tripartite motif containing 21 (TRIM21) promotes ubiquitination degradation of glutathione peroxidase 4 (GPX4) by regulating ferroptosis, and to discuss the feasibility of TRIM21 as a new therapeutic target for acute kidney injury (AKI).

MATERIALS AND METHODS

Ischemia-reperfusion (I/R)-AKI model was constructed using Trim21^+/+ and Trim21^-/- mice, and the expression of markers associated with kidney injury and ferroptosis were evaluated. HK-2 cells were treated by RSL3 and Erastin, and a hypoxia/reoxygenation (H/R) model was constructed to simulate I/R injury in vivo.

KEY FINDINGS

In vivo, TRIM21 is highly expressed in I/R kidney tissues. Loss of TRIM21 alleviated I/R-AKI and improved renal function. The upregulation of GPX4, a key ferroptosis regulator, and the mild mitochondrial damage suggested that loss of TRIM21 had a negative regulation of ferroptosis. In vitro, TRIM21 was highly expressed in H/R models, and overexpression of TRIM21 in HK-2 cells increased ROS production, promoted intracellular iron accumulation, and boosted cellular sensitivity to RSL3 and Erastin. Mechanistically, we confirmed that GPX4 is a substrate of TRIM21 and can be degraded by TRIM21-mediated ubiquitination, suggesting that inhibiting TRIM21 attenuates ferroptosis. A JAK2 inhibitor Fedratinib downregulated TRIM21 expression and reduced damage both in vivo and in vitro, which is correlated with the upregulation of GPX4.

SIGNIFICANCE

Our study showed that loss of TRIM21 could alleviate ferroptosis induced by I/R, revealed the mechanism of ubiquitination degradation of GPX4 by TRIM21 and suggested TRIM21 is a potential target for the treatment of AKI.

Novel druggable mechanism of Parkinson's disease: Potential therapeutics and underlying pathogenesis based on ferroptosis

Genetics, age, environmental factors, and oxidative stress have all been implicated in the development of Parkinson's disease (PD); however, a complete understanding of its pathology remains elusive. At present, there is no cure for PD, and currently available therapeutics are insufficient to meet patient needs. Ferroptosis, a distinctive iron-dependent cell death mode characterized by lipid peroxidation and oxidative stress, has pathophysiological features similar to those of PD, including iron accumulation, reactive oxygen species-induced oxidative damage, and mitochondrial dysfunction. Ferroptosis has been identified as a specific pathway of neuronal death and is closely related to the pathogenesis of PD. Despite the similarities in the biological targets involved in PD pathogenesis and ferroptosis, the relationship between novel targets in PD and ferroptosis has been neglected in the literature. In this review, the mechanism of ferroptosis is discussed, and the potential therapeutic targets implicated in both PD and ferroptosis are compared. Furthermore, the anti-PD effects of several ferroptosis inhibitors, as well as clinical studies thereof, and the identification of novel lead compounds for the treatment of PD and the inhibition of ferroptosis are reviewed. It is hoped that this review can promote research to further elucidate the relationship between ferroptosis and PD and provide new strategies for the development of novel ferroptosis-targeting PD therapy.

Targeting regulated cell death pathways in acute myeloid leukemia

The use of the BCL2 inhibitor venetoclax has transformed the management of patients with acute myeloid leukemia (AML) who are ineligible for intensive chemotherapy. By triggering intrinsic apoptosis, the drug is an excellent illustration of how our greater understanding of molecular cell death pathways can be translated into the clinic. Nevertheless, most venetoclax-treated patients will relapse, suggesting the need to target additional regulated cell death pathways. To highlight advances in this strategy, we review the recognized regulated cell death pathways, including apoptosis, necroptosis, ferroptosis and autophagy. Next, we detail the therapeutic opportunities to trigger regulated cell death in AML. Finally, we describe the main drug discovery challenges for regulated cell death inducers and their translation into clinical trials. A better knowledge of the molecular pathways regulating cell death represents a promising strategy to develop new drugs to cure resistant or refractory AML patients, particularly those resistant to intrinsic apoptosis.

Synergistic disruption of BTK and BCL-2 causes apoptosis while inducing ferroptosis in double-hit lymphoma

Double-hit lymphoma (DHL) is an aggressive subset of Diffuse Large B-cell Lymphoma (DLBCL) with poor outcomes and without satisfying treatment options. BTK inhibitor monotherapy is ineffective to suppress aggressive lymphoma. Hence, combination with other potential agents is warranted. Here, we demonstrated the second generation of BTK inhibitor, zanubrutinib, and a BCL-2 inhibitor, navitoclax, worked in synergistic manner to suppress DHL. Comprehensive in silico approach by interrogating single-cell to bulk-level profiling was employed along with in vitro and in vivo validation in DHL cell lines. Ablation of BTK enhanced sensitivity to navitoclax and suppressed proliferation of DHL cells. Combination of second generation of BTK inhibitor with navitoclax synergistically suppressed DLBCL cells with higher synergy score in DHL subset. The drug combination triggered apoptosis and ferroptosis, with the latter being characterized by reactive oxygen species (ROS) accumulation, extensive lipid peroxidation, and depletion of reduced glutathione. Moreover, ablation of BTK sensitized DHL cells to ferroptosis. Mechanistically, disruption of BTK and BCL-2 triggered ferroptosis by downregulating NRF2 and HMOX1, while deactivating GPX4. Combination of zanubrutinib and navitoclax effectively suppressed tumor growth in vivo. Our data suggest that zanubrutinib and navitoclax synergistically suppressed DHL by inducing apoptosis and ferroptosis.

Bioactive poly(2-oxazoline)-based nanomaterials bearing arylalkylamine and benzamide motifs possess intrinsic radical trapping and anti-ferroptosis properties

Radical trapping agents such as Ferrostatin-1 (Fer-1) are capable of rescuing cells from ferroptosis, an iron-dependent form of cell death. Previously, poly(2-oxazoline)-Fer-1 (POx-Fer-1) conjugates were reported, which possess increased water-solubility and remain active after covalent conjugation of Fer-1. In this study, we break down the structural and functional layers of POx-Fer-1 conjugates and reveal that drug-free POx containing arylalkylamine and benzamide motifs show anti-ferroptosis properties. Intriguingly, even the basic construct poly(2-methyl-2-oxazoline-grad-2-phenyl-2-oxazoline) P(MeOx-grad-PhOx) was found to be active. Therefore, P(MeOx-grad-PhOx) of varying compositions were prepared, characterized by ¹H NMR spectroscopy and size exclusion chromatography and investigated with regard to their self-assembly in aqueous solution and activity in an in vitro ferroptosis model. These findings were further explored for the design of defined and bioactive core-crosslinked micelles with intrinsic anti-ferroptosis behaviour. Cellular interaction studies involving C₁₁-BODIPY assays and confocal microscopy investigations revealed lysosomal processing of the nanomaterials and perturbation of ferroptotic cell death through reducing lipid-peroxidation. This study highlights new drug/cargo-free anti-ferroptotic nanomaterials as proof of concept that hold potential for therapy of ferroptosis-associated diseases and highlights the role of nanocarriers in a therapeutic context.

Self-assembled nanomaterials for ferroptosis-based cancer theranostics

Most ferroptosis nanomedicines based on organic or inorganic carriers have difficulties in further clinical translation due to their serious side effects and complicated preparation. Self-assembled nanomedicines can reduce the biological toxicity caused by additional chemical modifications and excipients, offering better biocompatibility and safety. Ferroptosis therapy is an iron-associated programmed cell death dependent on lipid peroxidation with efficient tumor selectivity and biosafety. Therefore, the application of self-assembled nanomedicines with good biosafety in the ferroptosis treatment of tumors has attracted extensive attention. In this review, recent advances in the field of ferroptosis-based self-assembled nanomaterials for cancer therapy are presented, with emphasis on how these nanomaterial components interact and their distinct mechanisms for inducing ferroptosis in tumor cells, including iron metabolism, amino acid metabolism and CoQ/FSP1, as well as their respective advantages and challenges. This review would therefore help the spectrum of advanced and novice researchers interested in this area to quickly zoom in on the essential information and glean some thought-provoking ideas to advance this subfield in cancer nanomedicine.

Nature-Inspired Bioactive Compounds: A Promising Approach for Ferroptosis-Linked Human Diseases?

Ferroptosis is a type of cell death driven by iron overload and lipid peroxidation. It is considered a key mechanism in the development of various diseases such as atherosclerosis, Alzheimer, diabetes, cancer, and renal failure. The redox status of cells, such as the balance between intracellular oxidants (lipid peroxides, reactive oxygen species, free iron ions) and antioxidants (glutathione, glutathione Peroxidase 4), plays a major role in ferroptosis regulation and constitutes its principal biomarkers. Therefore, the induction and inhibition of ferroptosis are promising strategies for disease treatments such as cancer or neurodegenerative and cardiovascular diseases, respectively. Many drugs have been developed to exert ferroptosis-inducing and/or inhibiting reactions, such as erastin and iron-chelating compounds, respectively. In addition, many natural bioactive compounds have significantly contributed to regulating ferroptosis and ferroptosis-induced oxidative stress. Natural bioactive compounds are largely abundant in food and plants and have been for a long time, inspiring the development of various low-toxic therapeutic drugs. Currently, functional bioactive peptides are widely reported for their antioxidant properties and application in human disease treatment. The scientific evidence from biochemical and in vitro tests of these peptides strongly supports the existence of a relationship between their antioxidant properties (such as iron chelation) and ferroptosis regulation. In this review, we answer questions concerning ferroptosis milestones, its importance in physiopathology mechanisms, and its downstream regulatory mechanisms. We also address ferroptosis regulatory natural compounds as well as provide promising thoughts about bioactive peptides.

Oxygen Self-Generating Nanoreactor Mediated Ferroptosis Activation and Immunotherapy in Triple-Negative Breast Cancer

The hypoxia microenvironment of solid tumors poses a technological bottleneck for ferroptosis and immunotherapy in clinical oncology. Nanoreactors based on special physiological signals in tumor cells are able to avoid various tumor tolerance mechanisms by alleviating the intracellular hypoxia environment. Herein we reported a nanoreactor Cu_2-xSe that enabled the conversion of Cu elements between Cu⁺ and Cu²⁺ for the generation of O₂ and the consumption of intracellular GSH content. Furthermore, to enhance the catalytic and ferroptosis-inducing activities of the nanoreactors, the ferroptosis agonist Erastin was loaded on the ZIF-8 coating on the surface of Cu_2-xSe to up-regulate the expression of NOX4 protein, increase the intracellular H₂O₂ content, catalyze the Cu⁺ to produce O₂ and activate ferroptosis. In addition, the nanoreactors were simultaneously surface functionalized with PEG polymer and folic acid molecules, which ensured the in vivo blood circulation and tumor-specific uptake. In vitro and in vivo experiments demonstrated that the functionalized self-supplying nanoreactors can amplify the ability to generate O₂ and consume intracellular GSH via the interconversion of Cu elements Cu⁺ and Cu²⁺, and impair the GPX4/GSH pathway and HIF-1α protein expression. At the same time, by alleviating the intracellular hypoxia environment, the expression of miR301, a gene in the secreted exosomes was decreased, which ultimately affected the phenotype polarization of TAMs and increased the content of IFN γ secreted by CD8⁺ T cells, which further promoted the ferroptosis induced by Erastin-loaded nanoreactors. This combined therapeutic strategy of activating the tumor immune response and ferroptosis via self-supplying nanoreactors provides a potential strategy for clinical application.

Ferroptosis: The functions of Nrf2 in human embryonic stem cells

Human embryonic stem cells (hESCs) have the capacity of self-renewal as well as differentiation towards three germ layer derivatives which makes them as a source of therapeutic application. hESCs are tremendously prone to cell death after dissociation into single cells. Therefore, it technically hinders their applications. Our recent study has revealed that hESCs can be prone to ferroptosis which differs from those in earlier explorations reporting that cellular detachment results in a process cited as anoikis. Ferroptosis occurs via increasing intracellular iron. Therefore, this form of programmed cell death is distinct from other cell deaths in terms of biochemistry, morphology, and genetics. Ferroptosis is found by excessive iron which plays an important part role in reactive oxygen species (ROS) generation through the Fenton reaction as a cofactor. Many genes are related to ferroptosis under the control of nuclear factor erythroid 2-related factor 2 (Nrf2) which is a transcription factor regulating the expression of genes to protect cells from oxidative stress. Nrf2 was demonstrated to take a perilous role in the suppression of ferroptosis by regulating the iron, antioxidant defense enzymes, usage, and restoration of glutathione, thioredoxin, and NADPH. Mitochondrial function is another target of Nrf2 to control cell homeostasis through the modulation of ROS production. In this review, we will give a succinct overview of lipid peroxidation and discuss the major players in the ferroptotic cascade. Additionally, we discussed the important role of the Nrf2 signaling pathway in mediating lipid peroxidation and ferroptosis, with a focus on known Nrf2 target genes that inhibit these processes and their possible role in hESCs.

Molecular mechanisms of ferroptosis and their involvement in brain diseases

Ferroptosis is a type of regulated cell death characterized by intracellular accumulation of iron and reactive oxygen species, inhibition of system Xc-, glutathione depletion, nicotinamide adenine dinucleotide phosphate oxidation and lipid peroxidation. Since its discovery and characterization in 2012, many efforts have been made to reveal the underlying mechanisms, modulating compounds, and its involvement in disease pathways. Ferroptosis inducers include erastin, sorafenib, sulfasalazine and glutamate, which, by inhibiting system Xc-, prevent the import of cysteine into the cells. RSL3, statins, Ml162 and Ml210 induce ferroptosis by inhibiting glutathione peroxidase 4 (GPX4), which is responsible for preventing the formation of lipid peroxides, and FIN56 and withaferin trigger GPX4 degradation. On the other side, ferroptosis inhibitors include ferrostatin-1, liproxstatin-1, α-tocopherol, zileuton, FSP1, CoQ10 and BH4, which interrupt the lipid peroxidation cascade. Additionally, deferoxamine, deferiprone and N-acetylcysteine, by targeting other cellular pathways, have also been classified as ferroptosis inhibitors. Increased evidence has established the involvement of ferroptosis in distinct brain diseases, including Alzheimer's, Parkinson's and Huntington's diseases, amyotrophic lateral sclerosis, multiple sclerosis, and Friedreich's ataxia. Thus, a deep understanding of how ferroptosis contributes to these diseases, and how it can be modulated, can open a new window of opportunities for novel therapeutic strategies and targets. Other studies have shown a sensitivity of cancer cells with mutated RAS to ferroptosis induction and that chemotherapeutic agents and ferroptosis inducers synergize in tumor treatment. Thus, it is tempting to consider that ferroptosis may arise as a target mechanistic pathway for the treatment of brain tumors. Therefore, this work provides an up-to-date review on the molecular and cellular mechanisms of ferroptosis and their involvement in brain diseases. In addition, information on the main ferroptosis inducers and inhibitors and their molecular targets is also provided.

Mouse embryonic stem cell-derived motor neurons are susceptible to ferroptosis

Ferroptosis is a regulated form of cell death driven by the lethal accumulation of lipid peroxides in cell membranes. Several regulators of ferroptosis have been identified using cancer cell lines. However, the cellular pathways of ferroptosis in neurons remain poorly characterized. In this study, we used a mouse embryonic stem cell-derived motor neuron model to investigate how motor neurons respond to ferroptosis inducers. Pharmacological and genetic inhibition of glutathione peroxidase 4 (GPx4) induced ferroptosis in motor neurons, while system x_c ^- inhibition by erastin had no effect. RNA-seq analysis showed that the expression levels of several genes were altered during RSL3-induced ferroptosis. Subsequent bioinformatic analysis revealed alterations in several biological pathways during ferroptosis, including synaptogenesis and calcium signaling. Finally, we found that edaravone, an FDA-approved drug for treating amyotrophic lateral sclerosis (ALS) disease, rescued motor neurons from RSL3-induced ferroptosis. Our data highlight the crucial role of GPx4 in ferroptosis regulation and demonstrate that stem cell-derived motor neuron culture is a valuable model to study ferroptosis at the single-cell level in a neuronal context.

Lipid peroxidation and its repair in malaria parasites

During its life cycle, the human malaria parasite Plasmodium falciparum is subjected to elevated levels of oxidative stress that cause damage to membrane lipids, a process referred to as lipid peroxidation. Control and repair of lipid peroxidation is critical for survival of P. falciparum. Here, we present an introduction into lipid peroxidation and review the current knowledge about the control and repair of the damage caused by lipid peroxidation in P. falciparum blood stages. We also review the recent identification of host peroxiredoxin 6 (PRDX6), as a key lipid-peroxidation-repair enzyme in P. falciparum blood stages. Such critical host factors provide novel targets for development of drugs against malaria.

Paeoniflorin alleviates ischemia/reperfusion induced acute kidney injury by inhibiting Slc7a11-mediated ferroptosis

The pathophysiological mechanism of acute kidney injury (AKI) is complicated, and effective drugs are still lacking. Ferroptosis is a newly discovered regulatory cell death mode characterized by the lethal accumulation of iron and reactive oxygen species-(ROS-)-dependent lipid hydroperoxides. In recent years, ferroptosis has been confirmed to be involved in the progression of AKI. Paeoniflorin (PF) is a traditional Chinese medicine that has protective effects on a variety of kidney diseases including AKI. However, the mechanism by which PF attenuates AKI is unclear. We detected that PF attenuated serum biochemical markers, histological damage, ferroptosis and inflammation in a dose-dependent manner in a mouse AKI model with bilateral renal artery ischemia-reperfusion (IR). Hypoxia-reoxygenation (HR)-induced ferroptosis and inflammation was also inhibited by PF in human renal tubular epithelial cells (HK2). RNA sequence analysis revealed that PF inhibited ferroptosis in HK2 cells by upregulating Slc7a11 in the glutathione pathway after HR treatment. PF failed to further protect cells with specific knockdown of Slc7a11 from ferroptosis under HR conditions. Consequently, these data indicated that PF prevention of ferroptosis in AKI requires dependence on Slc7a11. This study provided a scientific basis for the clinical search for drugs to prevent IR induced AKI.

PRDX6-mediated pulmonary artery endothelial cell ferroptosis contributes to monocrotaline-induced pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a life-threatening cardiopulmonary disorder whose underlying pathogenesis is unknown. Our previous study showed that pulmonary endothelial cell (PAEC) ferroptosis is involved in the progression of PH by releasing High-mobility group box 1 (HMGB1) and activating Toll-like receptor 4/NOD-like receptor family pyrin domain containing 3 (TLR4/NLRP3) inflammasome signalling. The precise mechanisms that regulate ferroptosis in PH are unclear. This study aimed to investigate the effect of peroxiredoxin 6 (PRDX6) on PAEC ferroptosis in PH.

METHODS

A rat model of PH was established with monocrotaline (MCT), and the distribution and expression of PRDX6 in the pulmonary artery were examined. Lentiviral vectors carrying PRDX6 (LV-PRDX6) were transfected into PAECs and injected into MCT-induced PH rats. Cell viability, MDA levels, reactive oxygen species (ROS) levels, labile iron pool (LIP) levels and mitochondrial morphology were examined. Ferroptosis-related proteins (NADPH oxidase-4 (NOX4), glutathione peroxidase 4 (GPX4), and ferritin heavy chain 1(FTH1)), TLR4, NLRP3 inflammasome markers, HMGB1 and inflammatory cytokines were examined. Pulmonary vascular remodelling and right ventricular structure and function were measured.

RESULTS

PRDX6 was expressed in PAECs and was significantly decreased in PH. PRDX6 overexpression significantly inhibited ferroptosis in PAECs under PH conditions in vitro and in vivo, as indicated by increased cell viability, decreased MDA, ROS and LIP levels, inhibited mitochondrial damage, upregulated GPX4 and FTH1 expression, and downregulated NOX4 expression. PRDX6 overexpression attenuated pulmonary vascular remodelling and changes in right ventricle structure and function in MCT-induced PH rats. Moreover, PRDX6 overexpression prevented HMGB1 release by PAECs and decreased TLR4 and NLRP3 inflammasome expression and inflammatory cytokine release in macrophages, while RSL3, a specific activator of ferroptosis, reversed these effects.

CONCLUSIONS

Taken together, these findings indicate that PRDX6 regulates PAEC ferroptosis through the release of HMGB1 and activation of the TLR4/NLRP3 inflammasome signalling pathway, providing novel therapeutic targets for the treatment of PH.

ALOX5-mediated ferroptosis acts as a distinct cell death pathway upon oxidative stress in Huntington's disease

Although it is well established that Huntington's disease (HD) is mainly caused by polyglutamine-expanded mutant huntingtin (mHTT), the molecular mechanism of mHTT-mediated actions is not fully understood. Here, we showed that expression of the N-terminal fragment containing the expanded polyglutamine (HTTQ94) of mHTT is able to promote both the ACSL4-dependent and the ACSL4-independent ferroptosis. Surprisingly, inactivation of the ACSL4-dependent ferroptosis fails to show any effect on the life span of Huntington's disease mice. Moreover, by using RNAi-mediated screening, we identified ALOX5 as a major factor required for the ACSL4-independent ferroptosis induced by HTTQ94. Although ALOX5 is not required for the ferroptotic responses triggered by common ferroptosis inducers such as erastin, loss of ALOX5 expression abolishes HTTQ94-mediated ferroptosis upon reactive oxygen species (ROS)-induced stress. Interestingly, ALOX5 is also required for HTTQ94-mediated ferroptosis in neuronal cells upon high levels of glutamate. Mechanistically, HTTQ94 activates ALOX5-mediated ferroptosis by stabilizing FLAP, an essential cofactor of ALOX5-mediated lipoxygenase activity. Notably, inactivation of the Alox5 gene abrogates the ferroptosis activity in the striatal neurons from the HD mice; more importantly, loss of ALOX5 significantly ameliorates the pathological phenotypes and extends the life spans of these HD mice. Taken together, these results demonstrate that ALOX5 is critical for mHTT-mediated ferroptosis and suggest that ALOX5 is a potential new target for Huntington's disease.

Cationic amphiphilic antihistamines inhibit STAT3 via Ca2+-dependent lysosomal H+ efflux

Commonly used antihistamines and other cationic amphiphilic drugs (CADs) are emerging as putative cancer drugs. Their unique chemical structure enables CADs to accumulate rapidly inside lysosomes, where they increase lysosomal pH, alter lysosomal lipid metabolism, and eventually cause lysosomal membrane permeabilization. Here, we show that CAD-induced rapid elevation in lysosomal pH is caused by a lysosomal H+ efflux that requires P2RX4-mediated lysosomal Ca2+ release and precedes the lysosomal membrane permeabilization. The subsequent cytosolic acidification triggers the dephosphorylation, lysosomal translocation, and inactivation of the oncogenic signal transducer and activator of transcription 3 (STAT3) transcription factor. Moreover, CAD-induced lysosomal H+ efflux sensitizes cancer cells to apoptosis induced by STAT3 inhibition and acts synergistically with STAT3 inhibition in restricting the tumor growth of A549 non-small cell lung carcinoma xenografts. These findings identify lysosomal H+ efflux and STAT3 inhibition as anticancer mechanisms of CADs and reinforce the repurposing of safe and inexpensive CADs as cancer drugs with a drug combination strategy.

Ferroptosis: From Basic Research to Clinical Therapeutics in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and highly heterogeneous malignancies worldwide. Despite the rapid development of multidisciplinary treatment and personalized precision medicine strategies, the overall survival of HCC patients remains poor. The limited survival benefit may be attributed to difficulty in early diagnosis, the high recurrence rate and high tumor heterogeneity. Ferroptosis, a novel mode of cell death driven by iron-dependent lipid peroxidation, has been implicated in the development and therapeutic response of various tumors, including HCC. In this review, we discuss the regulatory network of ferroptosis, describe the crosstalk between ferroptosis and HCC-related signaling pathways, and elucidate the potential role of ferroptosis in various treatment modalities for HCC, such as systemic therapy, radiotherapy, immunotherapy, interventional therapy and nanotherapy, and applications in the diagnosis and prognosis of HCC, to provide a theoretical basis for the diagnosis and treatment of HCC to effectively improve the survival of HCC patients.

Enlightening the mechanism of ferroptosis in epileptic heart

Epilepsy is a chronic neurological degenerative disease with a high incidence, affecting all age groups. Refractory Epilepsy (RE) occurs in approximately 30-40% of cases with a higher risk of sudden unexpected death in epilepsy (SUDEP). Recent studies have shown that spontaneous seizures developed in epilepsy can be related to an increase in oxidative stress and reactive oxygen derivatives (ROS) production. Increasing ROS concentration causes lipid peroxidation, protein oxidation, destruction of nuclear genetic material, enzyme inhibition, and cell death by a mechanism known as "ferroptosis" (Fts). Inactivation of glutathione peroxidase 4 (GPX4) induces Fts, while oxidative stress is linked with increased intracellular free iron (Fe+2) concentration. Fts is also a non-apoptotic programmed cell death mechanism, where a hypoxia-inducible factor 1 alpha (HIF-141) dependent hypoxic stress-like condition appears to occur with accumulation of iron and cytotoxic ROS in affected cells. Assuming convulsive crises as hypoxic stress, repetitive convulsive/hypoxic stress can be an effective inducer of the "epileptic heart" (EH), which is characterized by altered autonomic function and a high risk of malignant or fatal bradycardia. We previously reported that experimental recurrent seizures induce cardiomyocyte Fts associated with SUDEP. Furthermore, several genes related to Fts and hypoxia have recently been identified in acute myocardial infarction. An emerging theme from recent studies indicates that inhibition of GPX4 through modulating expression or activities of the xCT antiporter system (SLC7A11) governs cell sensitivity to oxidative stress from ferroptosis. Furthermore, during hypoxia, an increased expression of stress transcriptional factor ATF3 can promote Fts induced by erastin in a HIF-141-dependent manner. We propose that inhibition of Fts with ROS scavengers, iron chelators, antioxidants, and transaminase inhibitors could provide a therapeutic effect in epilepsy and improve the prognosis of SUDEP risk by protecting the heart from ferroptosis.

Cell Replacement Therapy for Type 1 Diabetes Patients: Potential Mechanisms Leading to Stem-Cell-Derived Pancreatic β-Cell Loss upon Transplant

Cell replacement therapy using stem-cell-derived insulin-producing β-like cells (sBCs) has been proposed as a practical cure for patients with type one diabetes (T1D). sBCs can correct diabetes in preclinical animal models, demonstrating the promise of this stem cell-based approach. However, in vivo studies have demonstrated that most sBCs, similarly to cadaveric human islets, are lost upon transplantation due to ischemia and other unknown mechanisms. Hence, there is a critical knowledge gap in the current field concerning the fate of sBCs upon engraftment. Here we review, discuss effects, and propose additional potential mechanisms that could contribute toward β-cell loss in vivo. We summarize and highlight some of the literature on phenotypic loss in β-cells under both steady, stressed, and diseased diabetic conditions. Specifically, we focus on β-cell death, dedifferentiation into progenitors, trans-differentiation into other hormone-expressing cells, and/or interconversion into less functional β-cell subtypes as potential mechanisms. While current cell replacement therapy efforts employing sBCs carry great promise as an abundant cell source, addressing the somewhat neglected aspect of β-cell loss in vivo will further accelerate sBC transplantation as a promising therapeutic modality that could significantly enhance the life quality of T1D patients.

Signaling pathways in Parkinson's disease: molecular mechanisms and therapeutic interventions

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, and its treatment remains a big challenge. The pathogenesis of PD may be related to environmental and genetic factors, and exposure to toxins and gene mutations may be the beginning of brain lesions. The identified mechanisms of PD include α-synuclein aggregation, oxidative stress, ferroptosis, mitochondrial dysfunction, neuroinflammation, and gut dysbiosis. The interactions among these molecular mechanisms complicate the pathogenesis of PD and pose great challenges to drug development. At the same time, the diagnosis and detection of PD are also one of obstacles to the treatment of PD due to its long latency and complex mechanism. Most conventional therapeutic interventions for PD possess limited effects and have serious side effects, heightening the need to develop novel treatments for this disease. In this review, we systematically summarized the pathogenesis, especially the molecular mechanisms of PD, the classical research models, clinical diagnostic criteria, and the reported drug therapy strategies, as well as the newly reported drug candidates in clinical trials. We also shed light on the components derived from medicinal plants that are newly identified for their effects in PD treatment, with the expectation to provide the summary and outlook for developing the next generation of drugs and preparations for PD therapy.

Influence of FOSL1 Inhibition on Vascular Calcification and ROS Generation through Ferroptosis via P53-SLC7A11 Axis

BACKGROUND

Vascular calcification during aging is highly prevalent in patients with cardiovascular disease; however, there is still no improvement in clarifying the development of vascular calcification. FOSL1 is a transcription regulator belonging to the AP-1 family, which has a unique function in vascular senescence, but its role in vascular calcification needs to be further explored.

METHODS

Primary mouse vascular smooth muscle cells were isolated and used to construct a calcification model in vitro. Seven-week-old male C57BL/6 mice were used to build the vitD3-induced calcification model in vivo. qRT-PCR and western blot were used to verify the expression of FOSL1 and other genes expressed in vascular smooth muscle cells and aortas. The level of calcification was determined by Alizarin Red S (ARS) staining and the calcium content assay. The level of cellular GSH was detected by the GSH assay kit.

RESULTS

Here, we report that FOSL1 was up-regulated after high-calcium/phosphate treatment in both the in vivo and in vitro vascular calcification models. Functional studies have shown that the reduction of FOSL1 attenuates ferroptosis and calcification in vascular smooth muscle cells, as indicated by ARS staining, calcium content assay, and western blot. The inhibition of FOSL1 downregulated the expression of bone-related molecules including Msh Homeobox 2 (MSX2) and tumor necrosis factor receptor superfamily, member 11b/osteoprotegerin (OPG), suggesting that FOSL1 promoted osteogenic differentiation of vascular smooth muscle cells. Furthermore, we found that the ferroptosis-inducing drug erastin can significantly accelerate calcification in the aortic ring while Ferrostatin-1 (fer-1), a drug to protect cells from ferroptosis, can alleviate calcification. Further experiments have shown that inhibiting FOSL1 can promote the expression of ferroptosis-related genes and attenuate calcification. Functionally, cellular GSH levels were increased after the reduction of FOSL1.

CONCLUSIONS

In this study, we observed a significant protective effect when we reduced the expression of FOSL1 during vascular calcification, and this effect might regulate ferroptosis to a great extent.

Nucleotide metabolism is linked to cysteine availability

The small molecule erastin inhibits the cystine-glutamate antiporter, system x_c^-, which leads to intracellular cysteine and glutathione depletion. This can cause ferroptosis, which is an oxidative cell death process characterized by uncontrolled lipid peroxidation. Erastin and other ferroptosis inducers have been shown to affect metabolism but the metabolic effects of these drugs have not been systematically studied. To this end, we investigated how erastin impacts global metabolism in cultured cells and compared this metabolic profile to that caused by the ferroptosis inducer RAS-selective lethal 3 or in vivo cysteine deprivation. Common among the metabolic profiles were alterations in nucleotide and central carbon metabolism. Supplementing nucleosides to cysteine-deprived cells rescued cell proliferation in certain contexts, showing that these alterations to nucleotide metabolism can affect cellular fitness. While inhibition of the glutathione peroxidase GPX4 caused a similar metabolic profile as cysteine deprivation, nucleoside treatment did not rescue cell viability or proliferation under RAS-selective lethal 3 treatment, suggesting that these metabolic changes have varying importance in different scenarios of ferroptosis. Together, our study shows how global metabolism is affected during ferroptosis and points to nucleotide metabolism as an important target of cysteine deprivation.

Targeting ferroptosis: Paving new roads for drug design and discovery

Ferroptosis, first proposed in 2012, is an iron-dependent form of regulated cell death characterized by excessive polyunsaturated fatty acid oxidation. In the past decade, researchers have revealed the formation and mechanisms of ferroptosis. Cancer drug resistance can be reversed by ferroptosis induction, and inhibiting ferroptosis has been shown to block certain disease processes. As a result, several ferroptosis-targeting drugs have been developed. However, the first-generation ferroptosis-targeting agents remain hampered from clinical use, mainly due to poor selectivity and pharmacokinetics. The discoveries of FSP1, GCH1, and other potential ferroptosis-regulating pathways independent of Xc^--GSH-GPX4 provide novel targets for drug design. Recently, protein-targeted degradation and antibody-drug conjugate strategy show promise in future drug design. With novel targets, further optimizations, and new technologies, the next-generation ferroptosis-targeting agents show a promising future with improved selectivity and efficacy. In this review, we summarize mechanisms, target types, drug design, and novel technologies of ferroptosis, aiming to pave the way for future drug design and discovery in the next decade.