Membrane Damage during Ferroptosis Is Caused by Oxidation of Phospholipids Catalyzed by the Oxidoreductases POR and CYB5R1

Sex differences in antioxidant defence and the regulation of redox homeostasis in physiology and pathology

Reactive oxygen species (ROS) is a term that defines a group of unstable compounds derived from exogenous sources or endogenous metabolism. Under physiological conditions, low levels of ROS play a key role in the regulation of signal transduction- or transcription-mediated cellular responses. In contrast, excessive and uncontrolled loading of ROS results in a pathological state known as oxidative stress (OS), a leading contributor to aging and a pivotal factor for the onset and progression of many disorders. Evolution has endowed cells with an antioxidant system involved in stabilizing ROS levels to a specific threshold, preserving ROS-induced signalling function and limiting negative side effects. In mammals, a great deal of evidence indicates that females defence against ROS is more proficient than males, determining a longer lifespan and lower incidence of most chronic diseases. In this review, we will summarize the most recent sex-related differences in the regulation of redox homeostasis. We will highlight the peculiar aspects of the antioxidant defence in sex-biased diseases whose onset or progression is driven by OS, and we will discuss the molecular, genetic, and evolutionary determinants of female proficiency to cope with ROS.

SLC27A4-mediated selective uptake of mono-unsaturated fatty acids promotes ferroptosis defense in hepatocellular carcinoma

Aberrant lipid metabolism mediated by the selective transport of fatty acids plays vital roles in cancer initiation, progression, and therapeutic failure. However, the biological function and clinical significance of abnormal fatty acid transporters in human cancer remain unclear. In the present study, we reported that solute carrier family 27 member 4 (SLC27A4) is significantly overexpressed in 21 types of human cancer, especially in the fatty acids-enriched microenvironment surrounding hepatocellular carcinoma (HCC), breast cancer, and ovarian cancer. Upregulated SLC27A4 expression correlated with shorter overall and relapse-free survival of patients with HCC, breast cancer, or ovarian cancer. Lipidomic analysis revealed that overexpression of SLC27A4 significantly promoted the selective uptake of mono-unsaturated fatty acids (MUFAs), which induced a high level of MUFA-containing phosphatidylcholine and phosphatidylethanolamine in HCC cells, consequently resulting in resistance to lipid peroxidation and ferroptosis. Importantly, silencing SLC27A4 significantly promoted the sensitivity of HCC to sorafenib treatment, both in vitro and in vivo. Our findings revealed a plausible role for SLC27A4 in ferroptosis defense via lipid remodeling, which might represent an attractive therapeutic target to increase the effectiveness of sorafenib treatment in HCC.

Accumulated cholesterol protects tumours from elevated lipid peroxidation in the microenvironment

Elevated lipid peroxidation (LPO), usually present in the tumour microenvironment (TME), is profoundly implicated in antitumour immunity and may be targeted for the development of new antitumour therapies. However, tumour cells may also rewire their metabolism to survive elevated LPO. Here, we report a novel and nonantioxidant mechanism by which tumour cells benefit from accumulated cholesterol to restrain LPO and ferroptosis, a nonapoptotic form of cell death characterized by accumulated LPO. Modulating cholesterol metabolism, especially LDLR-mediated cholesterol uptake, shifted the susceptibility of tumour cells to ferroptosis. Elevation of cellular cholesterol content specifically restrained LPO triggered by GSH-GPX4 inhibition or oxidizing factors in the TME. Furthermore, depletion of TME cholesterol by MβCD efficiently enhanced the antitumour efficacy of ferroptosis in a mouse xenograft model. Distinct from the antioxidant effect of its metabolic intermediates, the protective role of cholesterol was ascribed to its ability to decrease membrane fluidity and promote lipid raft formation, which affects the diffusion of LPO substrates. A correlation between LPO and lipid rafts was also found in tumour tissues from renal cancer patients. Together, our findings have identified a general and nonsacrificial mechanism by which cholesterol suppresses LPO, which can be exploited to enhance the efficacy of ferroptosis-based antitumour strategies.

The Emerging Role of Heat Shock Factor 1 (HSF1) and Heat Shock Proteins (HSPs) in Ferroptosis

Cells employ a well-preserved physiological stress response mechanism, termed the heat shock response, to activate a certain type of molecular chaperone called heat shock proteins (HSPs). HSPs are activated by transcriptional activators of heat shock genes known as heat shock factors (HSFs). These molecular chaperones are categorized as the HSP70 superfamily, which includes HSPA (HSP70) and HSPH (HSP110) families; the DNAJ (HSP40) family; the HSPB family (small heat shock proteins (sHSPs)); chaperonins and chaperonin-like proteins; and other heat-inducible protein families. HSPs play a critical role in sustaining proteostasis and protecting cells against stressful stimuli. HSPs participate in folding newly synthesized proteins, holding folded proteins in their native conformation, preventing protein misfolding and accumulation, and degrading denatured proteins. Ferroptosis is a recently identified type of oxidative iron-dependent cell demise. It was coined recently in 2012 by Stockwell Lab members, who described a special kind of cell death induced by erastin or RSL3. Ferroptosis is characterized by alterations in oxidative status resulting from iron accumulation, increased oxidative stress, and lipid peroxidation, which are mediated by enzymatic and non-enzymatic pathways. The process of ferroptotic cell death is regulated at multiple, and it is involved in several pathophysiological conditions. Much research has emerged in recent years demonstrating the involvement of HSPs and their regulator heat shock factor 1 (HSF1) in ferroptosis regulation. Understanding the machinery controlling HSF1 and HSPs in ferroptosis can be employed in developing therapeutic interventions for ferroptosis occurrence in a number of pathological conditions. Therefore, this review comprehensively summarized the basic characteristics of ferroptosis and the regulatory functions of HSF1 and HSPs in ferroptosis.

B cell-derived anti-beta 2 glycoprotein I antibody mediates hyperhomocysteinemia-aggravated hypertensive glomerular lesions by triggering ferroptosis

Hyperhomocysteinemia (HHcy) is a risk factor for chronic kidney diseases (CKDs) that affects about 85% CKD patients. HHcy stimulates B cells to secrete pathological antibodies, although it is unknown whether this pathway mediates kidney injury. In HHcy-treated 2-kidney, 1-clip (2K1C) hypertensive murine model, HHcy-activated B cells secreted anti-beta 2 glycoprotein I (β₂GPI) antibodies that deposited in glomerular endothelial cells (GECs), exacerbating glomerulosclerosis and reducing renal function. Mechanistically, HHcy 2K1C mice increased phosphatidylethanolamine (PE) (18:0/20:4, 18:0/22:6, 16:0/20:4) in kidney tissue, as determined by lipidomics. GECs oxidative lipidomics validated the increase of oxidized phospholipids upon Hcy-activated B cells culture medium (Hcy-B CM) treatment, including PE (18:0/20:4 + 3[O], PE (18:0a/22:4 + 1[O], PE (18:0/22:4 + 2[O] and PE (18:0/22:4 + 3[O]). PE synthases ethanolamine kinase 2 (etnk2) and ethanolamine-phosphate cytidylyltransferase 2 (pcyt2) were increased in the kidney GECs of HHcy 2K1C mice and facilitated polyunsaturated PE synthesis to act as lipid peroxidation substrates. In HHcy 2K1C mice and Hcy-B CM-treated GECs, the oxidative environment induced by iron accumulation and the insufficient clearance of lipid peroxides caused by transferrin receptor (TFR) elevation and down-regulation of SLC7A11/glutathione peroxidase 4 (GPX4) contributed to GECs ferroptosis of the kidneys. In vivo, pharmacological depletion of B cells or inhibition of ferroptosis mitigated the HHcy-aggravated hypertensive renal injury. Consequently, our findings uncovered a novel mechanism by which B cell-derived pathogenic anti-β₂GPI IgG generated by HHcy exacerbated hypertensive kidney damage by inducing GECs ferroptosis. Targeting B cells or ferroptosis may be viable therapeutic strategies for ameliorating lipid peroxidative renal injury in HHcy patients with hypertensive nephropathy.

Ferroptosis, pyroptosis and necroptosis in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute and uncontrolled pulmonary inflammation caused by various insults. Cell death is a critical mechanism in the pathogenesis of ARDS. Ferroptosis, a novel form of cell death defined as iron-mediated lipid peroxidation, has been shown to play a role in the pathogenesis of ARDS. Additionally, pyroptosis and necroptosis are also involved in the pathophysiological process of ARDS. The crosstalk among ferroptosis, pyroptosis, and necroptosis is getting increasing attention. Therefore, this review will mainly summarize the molecular mechanisms and central pathophysiological role of ferroptosis in ARDS. We will also discuss our understanding of pyroptosis and necroptosis as they pertain to the pathogenesis of ARDS. Furthermore, we also describe the pathological processes that engage crosstalk among ferroptosis, pyroptosis, and necroptosis. We consider that individual pathways of ferroptosis, pyroptosis, and necroptosis are highly interconnected and can compensate for one another to promote cell death.

Lipidomics analysis of Sanhuang chicken during cold storage reveals possible molecular mechanism of lipid changes

Lipidomic profiles changes of the Sanhuang chicken breast meat during cold storage (4 °C) were analyzed using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS)-based lipidomic analysis. Total lipids content decreased 16.8% after storage. Triacylglycerol (TAG), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) significantly decreased, while lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) increased. Particularly, there was a trend that TAGs with fatty acids of 16:0 and 18:1, and phospholipids containing 18:1, 18:2 and 20:4 were more likely to be downregulated. The increase in the ratio of lysophospholipids/phospholipids and the degree of lipid oxidation demonstrated oxidation and enzymatic hydrolysis are potentially responsible for the lipid transformation. Moreover, 12 lipid species (P < 0.05, VIP > 1, FC < 0.8 or >1.25) were identified to be associated with the spoilage of meat. Glycerophospholipid metabolism and linoleic acid metabolism were the key metabolic pathways involved in the lipid transformations of chilled chicken.

Polyunsaturated Fatty Acids Drive Lipid Peroxidation during Ferroptosis

Ferroptosis is a form of regulated cell death that is intricately linked to cellular metabolism. In the forefront of research on ferroptosis, the peroxidation of polyunsaturated fatty acids has emerged as a key driver of oxidative damage to cellular membranes leading to cell death. Here, we review the involvement of polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), lipid remodeling enzymes and lipid peroxidation in ferroptosis, highlighting studies revealing how using the multicellular model organism Caenorhabditis elegans contributes to the understanding of the roles of specific lipids and lipid mediators in ferroptosis.

Tubastatin A potently inhibits GPX4 activity to potentiate cancer radiotherapy through boosting ferroptosis

Ferroptosis, an iron-dependent lipid peroxidation-driven programmed cell death, is closely related to cancer therapy. The development of druggable ferroptosis inducers and their rational application in cancer therapy are critical. Here, we identified Tubastatin A, an HDAC6 inhibitor as a novel druggable ferroptosis inducer through large-scale drug screening. Tubastatin A directly bonded to GPX4 and inhibited GPX4 enzymatic activity through biotin-linked Tubastatin A putdown and LC/MS analysis, which is independent of its inhibition of HDAC6. In addition, our results showed that radiotherapy not only activated Nrf2-mediated GPX4 transcription but also inhibited lysosome-mediated GPX4 degradation, subsequently inducing ferroptosis tolerance and radioresistance in cancer cells. Tubastatin A overcame ferroptosis resistance and radioresistance of cancer cells by inhibiting GPX4 enzymatic activity. More importantly, Tubastatin A has excellent bioavailability, as demonstrated by its ability to significantly promote radiotherapy-induced lipid peroxidation and tumour suppression in a mouse xenograft model. Our findings identify a novel druggable ferroptosis inducer, Tubastatin A, which enhances radiotherapy-mediated antitumor effects. This work provides a compelling rationale for the clinical evaluation of Tubastatin A, especially in combination with radiotherapy.

TMEM164 is a new determinant of autophagy-dependent ferroptosis

Macroautophagy (hereafter "autophagy") is a membrane-mediated biological process that involves engulfing and delivering cytoplasmic components to lysosomes for degradation. In addition to autophagy's pro-survival effect during nutrient starvation, excessive activation of autophagy machinery can also cause regulated cell death, especially iron-dependent ferroptosis. Here, we report a key role of TMEM164 (transmembrane protein 164) in selectively mediating ATG5 (autophagy related 5)-dependent autophagosome formation during ferroptosis, rather than during starvation. In contrast, the membrane protein ATG9A (autophagy-related 9A) is dispensable for the formation of autophagosomes during ferroptosis. TMEM164-mediated autophagy degrades ferritin, GPX4 (glutathione peroxidase 4), and lipid droplets to increase iron accumulation and lipid peroxidation, thereby promoting ferroptotic cell death. Consequently, the loss of TMEM164 limits the anticancer activity of ferroptosis-mediated cytotoxicity in mice. High TMEM164 expression is associated with improved survival and increased immune cell infiltration in patients with pancreatic cancer. These findings establish a new mode of autophagy-dependent ferroptosis.

A tale of two lipids: Lipid unsaturation commands ferroptosis sensitivity

Membrane lipids play important roles in the regulation of cell fate, including the execution of ferroptosis. Ferroptosis is a non-apoptotic cell death mechanism defined by iron-dependent membrane lipid peroxidation. Phospholipids containing polyunsaturated fatty acids (PUFAs) are highly vulnerable to peroxidation and are essential for ferroptosis execution. By contrast, the incorporation of less oxidizable monounsaturated fatty acids (MUFAs) in membrane phospholipids protects cells from ferroptosis. The enzymes and pathways that govern PUFA and MUFA metabolism therefore play a critical role in determining cellular sensitivity to ferroptosis. Here, we review three lipid metabolic processes-fatty acid biosynthesis, ether lipid biosynthesis, and phospholipid remodeling-that can govern ferroptosis sensitivity by regulating the balance of PUFAs and MUFAs in membrane phospholipids.

The role of ferroptosis in prostate cancer: a novel therapeutic strategy

The incidence of prostate cancer is the second most among male cancers after lung cancer. Prostate cancer develops rapidly and is inclined to metastasize, and castration-resistant prostate cancer (CRPC) can be formed in the later stage, which brings great challenges to the prognosis and treatment. At present, the main treatment of prostate cancer is generally divided into four methods: surgery, chemotherapy, radiotherapy and endocrine therapy. However, the efficacy of these methods fails to satisfy the demands of patient prognosis. Ferroptosis is a newly discovered iron-dependent process, characterized by lipid peroxidation. Ferroptosis is associated with many diseases, especially tumor growth. In recent years, inhibiting tumor growth and overcoming tumor drug resistance by inducing ferroptosis has become a hot research topic. Previous studies have shown that induction of ferroptosis may be a new treatment for prostate cancer. We review the research progress of ferroptosis in prostate cancer in order to provide highly effective therapies for patients with prostate cancer.

Multifaceted role of ferroptosis in cardiovascular disease

Ferroptosis is a newly identified form of non-apoptotic cell death characterised primarily by iron-dependent lipid peroxidation. It differs morphologically, biochemically, and genetically from other forms of cell death, such as apoptosis, autophagy, and necrosis. Although the molecular mechanism underlying ferroptosis remains unclear, multiple biological processes, such as iron metabolism, lipid peroxides, and systems, such as the glutathione system and the tetrahydrobiopterin/coenzyme Q10 system, appear to be involved. While the contribution of ferroptotic mechanisms to human diseases is not clear, recent studies have identified a number of ferroptosis-related genes. Cardiovascular diseases are the main cause of death globally. In this review, we outline the progress regarding the emerging role of ferroptosis in the pathogenesis of cardiac pathophysiological conditions and the association of ferroptosis with cardiomyopathy, myocardial ischemia-reperfusion injury, heart failure, and atherosclerosis. We further summarise newly discovered ferroptotic targets for the development of therapies for cardiovascular diseases. Finally, we discuss the current challenges and future research directions in cardiovascular disease treatments.

Lipid metabolism alterations and ferroptosis in cancer: Paving the way for solving cancer resistance

Cancer often perturbs lipid metabolism, which leads to the alteration of metabolism intermediates, contributing to their deregulated growth and metastasis. Alteration of lipid metabolism shifting to contain more polyunsaturated fatty acids (PUFAs) in membrane phospholipids (PLs) also leads to cancer therapy resistance. High amounts of PL-PUFAs render cancer cells more vulnerable to lipid peroxidation (LPO), predisposing them towards ferroptosis, a new form of iron-dependent oxidative regulated cell death. The commitment of cancer undergoing ferroptotic cell death depends on the adaptive lipidome remodeling, LPO patterns, and LPO scavenging ability in heterogeneous cancer cells. Ferroptosis is receiving attention in cancer research as treating cancers, altering membrane lipid homeostasis, and refractory from conventional therapies. Therefore, a better understanding of the molecular underpinning of lipid metabolism alterations may provide new opportunities for solving cancer resistance. This review intends to understand altered lipid metabolism in cancers and discuss lipid composition and metabolic processes associated with ferroptosis induction in cancers.

Bioinorganic Modulators of Ferroptosis: A Review of Recent Findings

Ferroptosis was first reported as a separate modality of regulated cell death in 2008 and distinguished under its current name in 2012 after it was first induced with erastin. In the following decade, multiple other chemical agents were researched for their pro- or anti-ferroptotic properties. Complex organic structures with numerous aromatic moieties make up the majority of this list. This review fills a more overlooked niche by gathering, outlining and setting out conclusions regarding less prominent cases of ferroptosis induced by bioinorganic compounds and reported on within the last few years. The article contains a short summary of the application of bioinorganic chemicals based on gallium, several chalcogens, transition metals and elements known as human toxicants used for the purpose of evoking ferroptotic cell death in vitro or in vivo. These are used in the form of free ions, salts, chelates, gaseous and solid oxides or nanoparticles. Knowledge of how exactly these modulators promote or inhibit ferroptosis could be beneficial in the context of future therapies aimed against cancer or neurodegenerative diseases, respectively.

Gold Nanorods Inhibit Tumor Metastasis by Regulating MMP-9 Activity: Implications for Radiotherapy

Dysregulation of matrix metalloproteinase (MMP) is strongly implicated in tumor invasion and metastasis. Nanomaterials can interact with proteins and have impacts on protein activity, which provides a potential strategy for inhibiting tumor invasion and metastasis. However, the regulation of MMP activity by nanomaterials has not been fully determined. Herein, we have found that gold nanorods (Au NRs) are able to induce the change of the secondary structure of MMP-9 and thereby inhibit their activity. Interestingly, the inhibition of MMP-9 activity is highly dependent on the aspect ratio of Au NRs, and an aspect ratio of 3.3 shows the maximum inhibition efficiency. Molecular dynamics simulations combined with mathematical statistics algorithm reveal the binding behaviors and interaction modes of MMP-9 with Au NRs in atomic details and disclose the mechanism of aspect ratio-dependent inhibition effect of Au NRs on MMP-9 activity. Au NRs with an aspect ratio of 3.3 successfully suppress the X-ray-activated invasion and metastasis of tumor by inhibiting MMP-9 activity. Our findings provide important guidance for the modulation of MMP-9 activity by tuning key parameters of nanomaterials and demonstrate that gold nanorods could be developed as potential MMP inhibitors.

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.

Targeting ferroptosis: a novel insight against myocardial infarction and ischemia-reperfusion injuries

Ferroptosis, a newly discovered form of regulated cell death dependent on iron and reactive oxygen species, is mainly characterized by mitochondrial shrinkage, increased density of bilayer membranes and the accumulation of lipid peroxidation, causing membrane lipid peroxidation and eventually cell death. Similar with the most forms of regulated cell death, ferroptosis also participated in the pathological metabolism of myocardial infarction and myocardial ischemia/reperfusion injuries, which are still the leading causes of death worldwide. Given the crucial roles ferroptosis played in cardiovascular diseases, such as myocardial infarction and myocardial ischemia/reperfusion injuries, it is considerable to delve into the molecular mechanisms of ferroptosis contributing to the progress of cardiovascular diseases, which might offer the potential role of ferroptosis as a targeted treatment for a wide range of cardiovascular diseases. This review systematically summarizes the process and regulatory metabolisms of ferroptosis, discusses the relationship between ferroptosis and myocardial infarction as well as myocardial ischemia/reperfusion injuries, which might potentially provide novel insights for the pathological metabolism and original ideas for the prevention as well as treatment targeting ferroptosis of cardiovascular diseases such as myocardial infarction and myocardial ischemia/reperfusion injuries.

Neutral amino acid transporter SLC38A2 protects renal medulla from hyperosmolarity-induced ferroptosis

Hyperosmolarity of the renal medulla is essential for urine concentration and water homeostasis. However, how renal medullary collecting duct (MCD) cells survive and function under harsh hyperosmotic stress remains unclear. Using RNA-Seq, we identified SLC38A2 as a novel osmoresponsive neutral amino acid transporter in MCD cells. Hyperosmotic stress-induced cell death in MCD cells occurred mainly via ferroptosis, and it was significantly attenuated by SLC38A2 overexpression but worsened by Slc38a2-gene deletion or silencing. Mechanistic studies revealed that the osmoprotective effect of SLC38A2 is dependent on the activation of mTORC1. Moreover, an in vivo study demonstrated that Slc38a2-knockout mice exhibited significantly increased medullary ferroptosis following water restriction. Collectively, these findings reveal that Slc38a2 is an important osmoresponsive gene in the renal medulla and provide novel insights into the critical role of SLC38A2 in protecting MCD cells from hyperosmolarity-induced ferroptosis via the mTORC1 signalling pathway.

Ferroptosis Activation Contributes to the Formation of Skin Lesions in Psoriasis Vulgaris

(1) Background: Ferroptosis is a newly coined form of programmed cell death marked by lethal accumulation of lipid peroxidation and ferrous iron overload. A few studies on the specific mechanism of ferroptosis in the genesis and development of psoriasis are available. (2) Methods: Levels of lipid reactive oxygen species (ROS) and ferrous iron were measured by flow cytometry. Ultrastructure analysis was performed by transmission electron microscopy. Imiquimod-induced psoriasis-like mice were treated with a ferroptosis inducer. The expressions of mRNA of genes were measured by qRT-PCR. HaCaT cells were used to explore the function of Cyb561d2. (3) Results: In this work, we observed that levels of lipid ROS and ferrous iron in the epidermis of psoriasis vulgaris (PV) patients were increased. The existence of ferroptosis activation in the epidermis of individuals with PV was confirmed by transmission electron microscope both in patients with PV and psoriasis-like mice models. Intradermal injection of the ferroptosis inducer RSL3 in psoriasis-like mice significantly promoted and aggravated the development of psoriasis-like dermatitis, and the level of serum transferrin was also increased in PV samples. Moreover, abnormal expression of some genes related to iron metabolism was also proved in the epidermis of PV cases, among which Cyb561d2 was shown to promote ferrous iron overload and lipid peroxidation accumulation in HaCaT cells. (4) Conclusions: In summary, our study suggested that ferroptosis activation owing to iron overload may be a novel mechanism underlying the formation of skin lesions in individuals with PV.

Melatonin alleviates lead-induced fatty liver in the common carps (Cyprinus carpio) via gut-liver axis

As a widespread aquatic environmental contaminant, Lead (Pb) can provoke hepatic injury in various animals. Melatonin (MT) plays a crucial role in the regulation of inflammatory response. Accumulating evidence elucidates exogenous toxins can elicit hepatic lipid metabolic disorders by influencing the gut microbiome. Nevertheless, the effects of Pb on gut microbiota and hepatic lipid metabolism of the common carps, and whether MT can prevent and cure Pb-induced toxicity via regulating microbiome remains unknown. Here, metagenomic and transcriptomic analysis were subsequently implemented to identify the Pb exposure-triggered prominent alternation of gut-liver signal. In the present study the severe intestinal injury and fatty liver formation caused by Pb in common carp were preliminarily determined. Metagenomic analysis confirmed that the gut microbiome dominant phyla, family and genus of the common carps were Fusobacteria, Fusobacteriaceae and Cetobacterium. Meanwhile, lipopolysaccharide (LPS) biosynthesis pathway was regarded as one of the main responsible for Pb exposure. Subsequently, LPS was demonstrated as the Pb-triggered microbial-derived signal of the common carps by ELISA analysis, and involves in the hepatic metabolic disorders via deteriorating the intestinal barrier. Additionally, it confirmed that hepatocytes ferroptosis associated with Pb-evoked fatty liver of the common carps, and the aggravation of lysosomal dyshomeostasis as well as inhibition of AMPK phosphorylation were referred to lipid metabolic disorders. The results of the present study demonstrated microbial-derived signal induced by aquatic Pb contaminant cause fatty liver formation in the common carps, and the protective effects of MT on Pb toxicity were performed by receding LPS over-synthesis, restraining microbiota-sourced LPS transport, along with attenuation of hepatocytes ferroptosis.

Effect of regulatory cell death on the occurrence and development of head and neck squamous cell carcinoma

Head and neck cancer is a malignant tumour with a high mortality rate characterized by late diagnosis, high recurrence and metastasis rates, and poor prognosis. Head and neck squamous cell carcinoma (HNSCC) is the most common type of head and neck cancer. Various factors are involved in the occurrence and development of HNSCC, including external inflammatory stimuli and oncogenic viral infections. In recent years, studies on the regulation of cell death have provided new insights into the biology and therapeutic response of HNSCC, such as apoptosis, necroptosis, pyroptosis, autophagy, ferroptosis, and recently the newly discovered cuproptosis. We explored how various cell deaths act as a unique defence mechanism against cancer emergence and how they can be exploited to inhibit tumorigenesis and progression, thus introducing regulatory cell death (RCD) as a novel strategy for tumour therapy. In contrast to accidental cell death, RCD is controlled by specific signal transduction pathways, including TP53 signalling, KRAS signalling, NOTCH signalling, hypoxia signalling, and metabolic reprogramming. In this review, we describe the molecular mechanisms of nonapoptotic RCD and its relationship to HNSCC and discuss the crosstalk between relevant signalling pathways in HNSCC cells. We also highlight novel approaches to tumour elimination through RCD.

Hepatic nuclear factor 4 alpha promotes the ferroptosis of lung adenocarcinoma via transcriptional activation of cytochrome P450 oxidoreductase

Background

Lung adenocarcinoma is one of the most prevalent cancers while ferroptosis is crucial for cancer therapies. This study aims to investigate the function and mechanism of hepatic nuclear factor 4 alpha (HNF4A) in lung adenocarcinomas' ferroptosis.

Materials and Methods

HNF4A expression in ferroptotic A549 cells was detected. Then HNF4A was knocked down in A549 cells while overexpressed in H23 cells. Cells with changed HNF4A expression were tested for cytotoxicity and the level of cellular lipid peroxidation. The expression of cytochrome P450 oxidoreductase (POR) expression was examined after HNF4A was knocked down or overexpressed. Chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) and dual-luciferase assays were performed to validate the regulation of HNF4A on POR. Finally, POR was restored in HNF4A-altered cells to check whether it restores the effect of HNF4A on ferroptosis.

Results

We found that HNF4A expression significantly decreased in the ferroptosis of A549 cells, and this change can be blocked by deferoxamine, an inhibitor of ferroptosis. Knockdown of HNF4A inhibited ferroptosis in A549 cells while overexpression of HNF4A promoted ferroptosis in H23 cells. We identified a key ferroptosis-related gene, POR serves as a potential target gene of HNF4A, whose expression was significantly changed in lung adenocarcinoma cells knocking down or overexpressing HNF4A. We demonstrated that HNF4A was bound to the POR's promoter to enhance POR expression, and identified the binding sites via ChIP-qPCR and luciferase assays. Restoration of POR expression blocked the promoting effect of HNF4A on ferroptosis in lung adenocarcinoma.

Conclusion

HNF4A promotes POR expression through binding to the POR's promoter, and subsequently promotes the ferroptosis of lung adenocarcinoma.

Identification of HPCAL1 as a specific autophagy receptor involved in ferroptosis

Selective macroautophagy/autophagy maintains cellular homeostasis through the lysosomal degradation of specific cellular proteins or organelles. The pro-survival effect of selective autophagy has been well-characterized, but the mechanism by which it drives cell death is still poorly understood. Here, we use a quantitative proteomic approach to identify HPCAL1 (hippocalcin like 1) as a novel autophagy receptor for the selective degradation of CDH2 (cadherin 2) during ferroptosis. HPCAL1-dependent CDH2 depletion increases susceptibility to ferroptotic death by reducing membrane tension and favoring lipid peroxidation. Site-directed mutagenesis aided by bioinformatic analyses revealed that the autophagic degradation of CDH2 requires PRKCQ (protein kinase C theta)-mediated HPCAL1 phosphorylation on Thr149, as well as a non-classical LC3-interacting region motif located between amino acids 46-51. An unbiased drug screening campaign involving 4208 small molecule compounds led to the identification of a ferroptosis inhibitor that suppressed HPCAL1 expression. The genetic or pharmacological inhibition of HPCAL1 prevented ferroptosis-induced tumor suppression and pancreatitis in suitable mouse models. These findings provide a framework for understanding how selective autophagy promotes ferroptotic cell death.Abbreviations: ANXA7: annexin A7; ARNTL: aryl hydrocarbon receptor nuclear translocator like; CCK8: cell counting kit-8; CDH2: cadherin 2; CETSAs: cellular thermal shift assays; CPT2: carnitine palmitoyltransferase 2; DAMP, danger/damage-associated molecular pattern; DPPH: 2,2-diphenyl-1-picrylhydrazyl; DFO: deferoxamine; EBNA1BP2: EBNA1 binding protein 2; EIF4G1: eukaryotic translation initiation factor 4 gamma 1; FBL: fibrillarin; FKBP1A: FKBP prolyl isomerase 1A; FTH1: ferritin heavy chain 1; GPX4: glutathione peroxidase 4; GSDMs: gasdermins; HBSS: Hanks' buffered salt solution; HMGB1: high mobility group box 1; HNRNPUL1: heterogeneous nuclear ribonucleoprotein U like 1; HPCAL1: hippocalcin like 1; H1-3/HIST1H1D: H1.3 linker histone, cluster member; IKE: imidazole ketone erastin; KD: knockdown; LDH: lactate dehydrogenase; LIR: LC3-interacting region; MAGOH: mago homolog, exon junction complex subunit; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MDA: malondialdehyde; MLKL: mixed lineage kinase domain like pseudokinase; MPO: myeloperoxidase; MTOR: mechanistic target of rapamycin kinase; OE: overexpressing; OSTM1: osteoclastogenesis associated transmembrane protein 1; PRKC/PKC: protein kinase C; PRKAR1A: protein kinase cAMP-dependent type I regulatory subunit alpha; PRDX3: peroxiredoxin 3; PTGS2: prostaglandin-endoperoxide synthase 2; ROS: reactive oxygen species; SLC7A11: solute carrier family 7 member 11; SLC40A1: solute carrier family 40 member 1; SPTAN1: spectrin alpha, non-erythrocytic 1; STS: staurosporine; UBE2M: ubiquitin conjugating enzyme E2 M; ZYX: zyxin.

Quantitative reactive cysteinome profiling reveals a functional link between ferroptosis and proteasome-mediated degradation

Ferroptosis is a unique type of cell death that is hallmarked with the imbalanced redox homeostasis as triggered by iron-dependent lipid peroxidation. Cysteines often play critical roles in proteins to help maintain a healthy cellular environment by dynamically switching between their reduced and oxidized forms, however, how the global redox landscape of cysteinome is perturbed upon ferroptosis remains unknown to date. By using a quantitative chemical proteomic strategy, we systematically profiled the dynamic changes of cysteinome in ferroptotic cells and identified a list of candidate sites whose redox states are precisely regulated under ferroptosis-inducing and rescuing conditions. In particular, C106 of the protein/nucleic acid deglycase DJ-1 acts as an intriguing sensor switch for the ferroptotic condition, whose oxidation results in the disruption of its interaction with the 20S proteasome and leads to a marked activation in the proteasome system. Our chemoproteomic profiling and associated functional studies reveal a novel functional link between ferroptosis and the proteasome-mediated protein degradation. It also suggests proteasome as a promising target for developing treatment strategies for ferroptosis-related diseases.

Ultrasound-Targeted Microbubble Disruption with Key Nanodroplets for Effective Ferroptosis in Triple-Negative Breast Cancer Using Animal Model

Introduction

Triple-negative breast cancer (TNBC) is known to be the most aggressive form of breast cancer. Due to its high recurrence and mortality rates, the treatment of TNBC is a significant challenge for the medical community. Besides, ferroptosis is an emerging regulatory cell death that may provide new insights into the treatment of TNBC. As a central inhibitor of the ferroptosis process, the selenoenzyme glutathione peroxidase 4 (GPX4) is its classical therapeutic target. However, inhibition of GPX4 expression is quite detrimental to normal tissues. Ultrasound contrast agents, as an emerging visualization precision treatment, may provide a solution to the existing problem.

Methods

In this study, nanodroplets (NDs) carrying simvastatin (SIM) were constructed using the homogeneous/emulsification method. Then, the characterization of SIM-NDs was systematically evaluated. Meanwhile, in this study, the ability of SIM-NDs combined with ultrasound-targeted microbubble disruption (UTMD) to initiate ferroptosis and its respective mechanisms of ferroptosis induction were verified. Finally, the antitumor activity of SIM-NDs was investigated in vitro and in vivo using MDA-MB-231 cells and TNBC animal models.

Results

SIM-NDs exhibited excellent pH- and ultrasound-responsive drug release and noticeable ultrasonographic imaging ability, also showing good biocompatibility and biosafety. UTMD could promote increased intracellular reactive oxygen species and consume intracellular glutathione. However, SIM-NDs were efficiently internalized into cells under ultrasound irradiation, followed by the rapid release of SIM, which inhibited intracellular mevalonate production, and synergistically downregulated GPX4 expression, thereby promoting ferroptosis. Moreover, this combined treatment demonstrated strong antitumor ability in vitro and in vivo.

Conclusion

The combination of UTMD and SIM-NDs presents a promising avenue for harnessing ferroptosis in the treatment of malignant tumors.

Membrane Integrity Assay in Ferroptosis

Ferroptosis is a form of regulated cell death that relies on the accumulation of intracellular iron and subsequent oxidative stress. Ferroptotic cell death is characterized by uncontrolled lipid peroxidation, which leads to plasma membrane damage and rupture. The loss of plasma membrane integrity results in the release of intracellular components, including damage-associated molecular patterns, and can propagate death between cells in a synchronized manner. Understanding the mechanisms of ferroptotic membrane damage is crucial to comprehending this form of cell death. This chapter provides a summary of techniques for detecting plasma membrane integrity in ferroptosis, including transmission electron microscopy analysis, flow cytometry analysis, and assessments of oxidoreductase-mediated membrane damage.

Ferroptosis and Iron Metabolism after Intracerebral Hemorrhage

The method of iron-dependent cell death known as ferroptosis is distinct from apoptosis. The suppression of ferroptosis after intracerebral hemorrhage (ICH) will effectively treat ICH and improve prognosis. This paper primarily summarizes the mechanism of ferroptosis after ICH, with an emphasis on lipid peroxidation, the antioxidant system, iron metabolism, and other pathways. In addition, regulatory targets and drug molecules were described. Although there has been some progress in the field of study, there are still numerous gaps. The mechanism by which non-heme iron enters neurons through the blood-brain barrier (BBB), the mitochondrial role in ferroptosis, and the specific mechanism by which lipid peroxidation induces ferroptosis remain unclear and require further study. In addition, the inhibitory effect of many drugs on ferroptosis after ICH has only been demonstrated in basic experiments and must be translated into clinical trials. In summary, research on ferroptosis following ICH will play an important role in the treatment of ICH.

Research progress on the role of ferroptosis in cardiovascular disease

The cardiovascular disease pathogenesis is extremely complex and seriously threatens human health. Cardiomyocyte death plays a significant role in cardiovascular disease occurrence and development. In addition to the previously revealed modes of cell death (apoptosis, autophagy, and pyroptosis), ferroptosis is highly related to the development of cardiovascular diseases, including arrhythmia, atherosclerosis, and myocardial ischemia/reperfusion. Ferroptosis is a novel cell death pathway driven by lipid peroxidation and iron overload. Lipid, amino acid, and iron metabolism regulate the ferroptosis pathway. Small molecule compounds (iron chelators, antioxidants, and ferroptosis inhibitors) and genetic programming can alleviate or prevent cardiovascular disease by inhibiting the ferroptosis pathway. Ferroptosis plays a key role in various cardiovascular disease occurrence and development, and inhibiting ferroptosis in cardiomyocytes is expected to become a feasible treatment method. In this mini-review, we systematically summarize the molecular mechanisms of ferroptosis in different cardiovascular diseases, delineate the regulatory network between ferroptosis and cardiovascular diseases, and highlight its potential therapeutic targets.

A Class of Disulfide Compounds Suppresses Ferroptosis by Stabilizing GPX4

Ferroptosis is a nonapoptotic form of cell death characterized by iron-dependent lipid peroxidation and has been implicated in multiple pathological conditions. Glutathione peroxidase 4 (GPX4) plays an essential role in inhibiting ferroptosis by eliminating lipid peroxide using glutathione (GSH) as a reductant. In this study, we found Ellman's reagent DTNB and a series of disulfide compounds, including disulfiram (DSF), an FDA-approved drug, which protect cells from erastin-induced ferroptosis. Mechanistically, DTNB or DSF is conjugated to multiple cysteine residues in GPX4 and disrupts GPX4 interaction with HSC70, an adaptor protein for chaperone mediated autophagy, thus preventing GPX4 degradation induced by erastin. In addition, DSF ameliorates concanavalin A induced acute liver injury by suppressing ferroptosis in a mouse model. Our work reveals a novel regulatory mechanism for GPX4 protein stability control. We also discover disulfide compounds as a new class of ferroptosis inhibitors and suggest therapeutic repurposing of DSF in treating ferroptosis-related diseases.

Inhibition of Protein Disulfide Isomerase (PDIA1) Leads to Proteasome-Mediated Degradation of Ubiquitin-like PHD and RING Finger Domain-Containing Protein 1 (UHRF1) and Increased Sensitivity of Glioblastoma Cells to Topoisomerase II Inhibitors

Glioblastoma (GBM) is the most aggressive brain tumor, and the prognosis remains poor with current available treatments. PDIA1 is considered a promising therapeutic target in GBM. In this study, we demonstrate that targeting PDIA1 results in increased GBM cell death by topoisomerase II (Top-II) inhibitors resulting in proteasome-mediated degradation of the oncogenic protein UHRF1. Combination of the PDIA1 inhibitor, bepristat-2a, produces strong synergy with doxorubicin, etoposide, and mitoxantrone in GBM and other cancer cell lines. Our bioinformatics analysis of multiple datasets revealed downregulation of UHRF1, upon PDIA1 inhibition. In addition, PDIA1 inhibition results in proteasome-mediated degradation of UHRF1 protein. Interestingly, treatment of GBM cells with bepristat-2a results in increased apoptosis and resistance to ferroptosis. Our findings emphasize the importance of PDIA1 as a therapeutic target in GBM and present a promising new therapeutic approach using Top-II inhibitors for GBM treatment.

Ferroptosis of tumour neutrophils causes immune suppression in cancer

Ferroptosis is a non-apoptotic form of regulated cell death that is triggered by the discoordination of regulatory redox mechanisms culminating in massive peroxidation of polyunsaturated phospholipids. Ferroptosis inducers have shown considerable effectiveness in killing tumour cells in vitro, yet there has been no obvious success in experimental animal models, with the notable exception of immunodeficient mice1,2. This suggests that the effect of ferroptosis on immune cells remains poorly understood. Pathologically activated neutrophils (PMNs), termed myeloid-derived suppressor cells (PMN-MDSCs), are major negative regulators of anti-tumour immunity3-5. Here we found that PMN-MDSCs in the tumour microenvironment spontaneously die by ferroptosis. Although decreasing the presence of PMN-MDSCs, ferroptosis induces the release of oxygenated lipids and limits the activity of human and mouse T cells. In immunocompetent mice, genetic and pharmacological inhibition of ferroptosis abrogates suppressive activity of PMN-MDSCs, reduces tumour progression and synergizes with immune checkpoint blockade to suppress the tumour growth. By contrast, induction of ferroptosis in immunocompetent mice promotes tumour growth. Thus, ferroptosis is a unique and targetable immunosuppressive mechanism of PMN-MDSCs in the tumour microenvironment that can be pharmacologically modulated to limit tumour progression.

Cytochrome b5 reductases: Redox regulators of cell homeostasis

The cytochrome-b5 reductase (CYB5R) family of flavoproteins is known to regulate reduction-oxidation (redox) balance in cells. The five enzyme members are highly compartmentalized at the subcellular level and function as "redox switches" enabling the reduction of several substrates, such as heme and coenzyme Q. Critical insight into the physiological and pathophysiological significance of CYB5R enzymes has been gleaned from several human genetic variants that cause congenital disease and a broad spectrum of chronic human diseases. Among the CYB5R genetic variants, CYB5R3 is well-characterized and deficiency in expression and activity is associated with type II methemoglobinemia, cancer, neurodegenerative disorders, diabetes, and cardiovascular disease. Importantly, pharmacological and genetic-based strategies are underway to target CYB5R3 to circumvent disease onset and mitigate severity. Despite our knowledge of CYB5R3 in human health and disease, the other reductases in the CYB5R family have been understudied, providing an opportunity to unravel critical function(s) for these enzymes in physiology and disease. In this review, we aim to provide the broad scientific community an up-to-date overview of the molecular, cellular, physiological, and pathophysiological roles of CYB5R proteins.

Detoxification mechanisms of electroactive microorganisms under toxicity stress: A review

Remediation of environmental toxic pollutants has attracted extensive attention in recent years. Microbial bioremediation has been an important technology for removing toxic pollutants. However, microbial activity is also susceptible to toxicity stress in the process of intracellular detoxification, which significantly reduces microbial activity. Electroactive microorganisms (EAMs) can detoxify toxic pollutants extracellularly to a certain extent, which is related to their unique extracellular electron transfer (EET) function. In this review, the extracellular and intracellular aspects of the EAMs’ detoxification mechanisms are explored separately. Additionally, various strategies for enhancing the effect of extracellular detoxification are discussed. Finally, future research directions are proposed based on the bottlenecks encountered in the current studies. This review can contribute to the development of toxic pollutants remediation technologies based on EAMs, and provide theoretical and technical support for future practical engineering applications.

The gut microbiota metabolite glycochenodeoxycholate activates TFR-ACSL4-mediated ferroptosis to promote the development of environmental toxin-linked MAFLD

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become the most common chronic liver disorders in the world, and yet has no approved pharmacotherapy due to the etiology is complex. In the last ten years, increasing evidence have identified the environmental pollutants as risk factors for MAFLD. However, the underlying mechanism remains unclear. Our study found that bromoacetic acid (BAA, a typical kind of environmental toxin) increased triglycerides and total cholesterol levels as well as induced obvious hepatic steatosis and inflammation. The lipidomics showed that ferroptosis was implicated in the environmental toxin-linked MAFLD. Besides, the analysis of microbial metabolomics showed significant change of gut microbiome in BAA groups and the content of gut microbiota metabolite (glycochenodeoxycholate, GCDCA) increased sharply. In vitro study, we observed features of ferroptotic cells by transmission electron microscopy after BAA/GCDCA treatment. Besides, we demonstrated that BAA/GCDCA significantly increased iron contents, with upregulating transferrin receptor (TFR) and acyl-CoA synthetase long-chain family 4 (ACSL4) expression levels. By contrast, iron chelator or silencing TFR relieved BAA/GCDCA-induced lipid metabolism disorder and inflammation. What's more, the interaction between TFR and ACSL4 was also identified. Taken together, we found that, in response to environmental toxin, gut microbiota metabolite GCDCA activates TFR-ACSL4-mediated ferroptosis, which triggered subsequent lipid metabolism disorder and inflammation. Moreover, these findings firstly highlighted the functional relevance among ferroptosis, lipid metabolism and gut microbiota metabolite during environmental pollutant exposure, which shed light on the deep mechanism of environmental toxin-related MAFLD, providing potential targets for the prevention of MAFLD.

Inhibition of ferroptosis promotes retina ganglion cell survival in experimental optic neuropathies

Retinal ganglion cell (RGC) death is a hallmark of traumatic optic neuropathy, glaucoma, and other optic neuropathies that result in irreversible vision loss. However, therapeutic strategies for rescuing RGC loss still remain challenging, and the molecular mechanism underlying RGC loss has not been fully elucidated. Here, we highlight the role of ferroptosis, a non-apoptotic form of programmed cell death characterized by iron-dependent lethal lipid peroxides accumulation, in RGC death using an experimental model of glaucoma and optic nerve crush (ONC). ONC treatment resulted in significant downregulation of glutathione peroxidase 4 (GPx4) and system xc(-) cystine/glutamate antiporter (xCT) in the rat retina, accompanied by increased lipid peroxide and iron levels. The reduction of GPx4 expression in RGCs after ONC was confirmed by laser-capture microdissection and PCR. Transmission electron microscopy (TEM) revealed alterations in mitochondrial morphology, including increased membrane density and reduced mitochondrial cristae in RGCs after ONC. Notably, the ferroptosis inhibitor ferrostatin-1 (Fer-1) significantly promoted RGC survival and preserved retinal function in ONC and microbead-induced glaucoma mouse models. In addition, compared to the apoptosis inhibitor Z-VAD-FMK, Fer-1 showed better effect in rescuing RGCs death in ONC retinas. Mechanistically, we found the downregulation of GPx4 mainly occurred in the mitochondrial compartment, accompanied by increased mitochondrial reactive oxygen species (ROS) and lipid peroxides. The mitochondria-selective antioxidant MitoTEMPO attenuated RGC loss after ONC, implicating mitochondrial ROS and lipid peroxides as major mechanisms in ferroptosis-induced RGC death in ONC retinas. Notably, administering Fer-1 effectively prevented the production of mitochondrial lipid peroxides, the impairment of mitochondrial adenosine 5'-triphosphate (ATP) production, and the downregulation of mitochondrial genes, such as mt-Cytb and MT-ATP6, in ONC retinas. Our findings suggest that ferroptosis is a major form of regulated cell death for RGCs in experimental glaucoma and ONC models and suggesting targeting mitochondria-dependent ferroptosis as a protective strategy for RGC injuries in optic neuropathies.

Signaling pathways and defense mechanisms of ferroptosis

As a type of lytic cell death driven by unrestricted lipid peroxidation and subsequent plasma membrane damage, ferroptosis occurs and develops because of sophisticated signals and regulatory mechanisms. The reactive oxygen species (ROS) used to initiate ferroptosis come from a variety of sources, including iron-mediated Fenton reactions, mitochondrial ROS, and membrane-associated ROS driven by the NOX protein family. Polyunsaturated fatty acid-containing phospholipids are the main substrates of lipid peroxidation in ferroptosis, which is positively regulated by enzymes, such as ACSL4, LPCAT3, ALOXs, or POR. Selective activation of autophagic degradation pathways promotes ferroptosis by increasing iron accumulation to cause lipid peroxidation. In contrast, system xc^- -glutathione-GPX4 axis plays a central role in limiting lipid peroxidation, although other antioxidants (such as coenzyme Q10 and tetrahydrobiopterin) can also inhibit ferroptosis. A main nuclear mechanism of cell defense against ferroptosis is the activation of the NFE2L2-dependent antioxidant response by transcriptionally upregulating the expression of antioxidants or cytoprotective genes. Additionally, the membrane damage caused by ferroptotic stimulus can be repaired by ESCRT-III-dependent membrane scission machinery. In this review, we summarize recent progress in understanding the signaling pathways and defense mechanisms of ferroptosis.

Tanshinone functions as a coenzyme that confers gain of function of NQO1 to suppress ferroptosis

Ferroptosis is triggered by the breakdown of cellular iron-dependent redox homeostasis and the abnormal accumulation of lipid ROS. Cells have evolved defense mechanisms to prevent lipid ROS accumulation and ferroptosis. Using a library of more than 4,000 bioactive compounds, we show that tanshinone from Salvia miltiorrhiza (Danshen) has very potent inhibitory activity against ferroptosis. Mechanistically, we found that tanshinone functions as a coenzyme for NAD(P)H:quinone oxidoreductase 1 (NQO1), which detoxifies lipid peroxyl radicals and inhibits ferroptosis both in vitro and in vivo. Although NQO1 is recognized as an oxidative stress response gene, it does not appear to have a direct role in ferroptosis inhibition in the absence of tanshinone. Here, we demonstrate a gain of function of NQO1 induced by tanshinone, which is a novel mechanism for ferroptosis inhibition. Using mouse models of acute liver injury and ischemia/reperfusion heart injury, we observed that tanshinone displays protective effects in both the liver and the heart in a manner dependent on NQO1. Our results link the clinical use of tanshinone to its activity in ferroptosis inhibition.

The Complex Dynamic of Phase I Drug Metabolism in the Early Stages of Doxorubicin Resistance in Breast Cancer Cells

The altered activity of drug metabolism enzymes (DMEs) is a hallmark of chemotherapy resistance. Cytochrome P450s (CYPs), mainly CYP3A4, and several oxidoreductases are responsible for Phase I metabolism of doxorubicin (DOX), an anthracycline widely used in breast cancer (BC) treatment. This study aimed to investigate the role of Phase I DMEs involved in the first stages of acquisition of DOX-resistance in BC cells. For this purpose, the expression of 92 DME genes and specific CYP-complex enzymes activities were assessed in either sensitive (MCF-7 parental cells; MCF-7/DOX^S) or DOX-resistant (MCF-7/DOX^R) cells. The DMEs genes detected to be significantly differentially expressed in MCF-7/DOX^R cells (12 CYPs and eight oxidoreductases) were indicated previously to be involved in tumor progression and/or chemotherapy response. The analysis of CYP-mediated activities suggests a putative enhanced CYP3A4-dependent metabolism in MCF-7/DOX^R cells. A discrepancy was observed between CYP-enzyme activities and their corresponding levels of mRNA transcripts. This is indicative that the phenotype of DMEs is not linearly correlated with transcription induction responses, confirming the multifactorial complexity of this mechanism. Our results pinpoint the potential role of specific CYPs and oxidoreductases involved in the metabolism of drugs, retinoic and arachidonic acids, in the mechanisms of chemo-resistance to DOX and carcinogenesis of BC.

A noncanonical function of EIF4E limits ALDH1B1 activity and increases susceptibility to ferroptosis

Ferroptosis is a type of lipid peroxidation-dependent cell death that is emerging as a therapeutic target for cancer. However, the mechanisms of ferroptosis during the generation and detoxification of lipid peroxidation products remain rather poorly defined. Here, we report an unexpected role for the eukaryotic translation initiation factor EIF4E as a determinant of ferroptotic sensitivity by controlling lipid peroxidation. A drug screening identified 4EGI-1 and 4E1RCat (previously known as EIF4E-EIF4G1 interaction inhibitors) as powerful inhibitors of ferroptosis. Genetic and functional studies showed that EIF4E (but not EIF4G1) promotes ferroptosis in a translation-independent manner. Using mass spectrometry and subsequent protein-protein interaction analysis, we identified EIF4E as an endogenous repressor of ALDH1B1 in mitochondria. ALDH1B1 belongs to the family of aldehyde dehydrogenases and may metabolize the aldehyde substrate 4-hydroxynonenal (4HNE) at high concentrations. Supraphysiological levels of 4HNE triggered ferroptosis, while low concentrations of 4HNE increased the cell susceptibility to classical ferroptosis inducers by activating the NOX1 pathway. Accordingly, EIF4E-dependent ALDH1B1 inhibition enhanced the anticancer activity of ferroptosis inducers in vitro and in vivo. Our results support a key function of EIF4E in orchestrating lipid peroxidation to ignite ferroptosis.

Ferroptosis and musculoskeletal diseases: “Iron Maiden” cell death may be a promising therapeutic target

Ferroptosis is a novel form of cell death precisely regulated by iron metabolism, antioxidant processes, and lipid metabolism that plays an irreplaceable role in the development of many diseases. Musculoskeletal disorders (MSKs), including osteoporosis, osteoarthritis, rheumatoid arthritis, intervertebral disc degeneration, sarcopenia, and rhabdomyolysis, have become one of the most common causes of disability and a major burden on public health and social care systems. The mechanism of ferroptosis in MSKs has recently been elucidated. In this review, we briefly introduce the ferroptosis mechanism and illustrate the pathological roles of ferroptosis in MSKs with a focus on how ferroptosis can be exploited as a promising treatment strategy. Notably, because the toxicity of compounds that inhibit or induce ferroptosis in other organs is largely unknown, ferroptosis appears to be a double-edged sword. We point out that more research is needed in the future to verify the therapeutic effects based on ferroptosis in MSKs.

Explicating the publication paradigm by bibliometric approaches: A case of interplay between nanoscience and ferroptosis

Background

Ferroptosis has been widely investigated as an emerging drug target, while its combination with nanoscience provides bourgeoning application prospects. The development of ferroptosis regulating nanomedicines have attracted worldwide attentions in recent years. It would be meaningful to describe the relevant publication paradigm.

Methods

Herein, a bibliometric analysis was performed using the database of Web of Science Core Collection to clarify the publication paradigm. The development of related publications in the last 6 years was described, and the revolutionary trends were figured out. Ultimately, the possible future exploration directions were proposed.

Results

The bibliometric analysis of 327 documents of interest indicated that the main research focus was in multiple fields including Materials science, Science & technology, Chemistry, and Pharmacology & pharmacy. With widely cooperation and strong funding, the researchers from Chinese organizations contributed most of publications, followed with United States and Australia. Cocitation analysis revealed that several original papers reported the key molecular mechanisms of ferroptosis were considered as the foundation for subsequent studies, and some nanomedicines-related documents were taken as examples and discussed. Mining results showed that the mechanism evaluation of ferroptosis regulation therapy for cancer treatment was the hotspot. Then, several possible future explorations of ferroptosis-related nanoscience were presented and discussed.

Conclusions

The bibliometric profile of nanoscience-ferroptosis research was analyzed in detail. We believe that the bibliometric analysis could act as a robust method for explicating the publication paradigm as a certain field.

Physiological Effects of Ferroptosis on Organ Fibrosis

Ferroptosis is a new type of programmed cell death with unique morphological, biochemical, and genetic features. From the initial study of histomorphology to the exploration of subcellular organelles and even molecular mechanisms, a net connecting ferroptosis and fibrosis is being woven and formed. Inflammation may be the bridge between both processes. In this review, we will discuss the ferroptosis theory and process and the physiological functions of ferroptosis, followed by a description of the pathological effects and the underlying mechanisms of ferroptosis in the pathogenesis of tumorigenesis, ischemic damage, degenerative lesions, autoimmune diseases, and necroinflammation. We then focus on the role of ferroptosis in the fibrosis process in the liver, lung, kidney, heart, and other organs. Although the molecular mechanism of ferroptosis has been explored extensively in the past few years, many challenges remain to be resolved to translate this information into antifibrotic practice, which is becoming a promising new direction in the field of fibrotic disease prevention and treatment.

Ferroptosis in glioma treatment: Current situation, prospects and drug applications

Ferroptosis is a regulatory form of iron-dependent cell death caused by the accumulation of lipid-based reactive oxygen species (ROS) and differs from apoptosis, pyroptosis, and necrosis. Especially in neoplastic diseases, the susceptibility of tumor cells to ferroptosis affects prognosis and is associated with complex effects. Gliomas are the most common primary intracranial tumors, accounting for disease in 81% of patients with malignant brain tumors. An increasing number of studies have revealed the particular characteristics of iron metabolism in glioma cells. Therefore, agents that target a wide range of molecules involved in ferroptosis may regulate this process and enhance glioma treatment. Here, we review the underlying mechanisms of ferroptosis and summarize the potential therapeutic options for targeting ferroptosis in glioma.

Ferroptosis and its emerging role in esophageal cancer

The occurrence and development of tumors involve a series of life activities of cells, among which cell death has always been a crucial part in the research of tumor mechanisms and treatment methods. Ferroptosis is a non-apoptotic form of cell death, which is characterized by lipid peroxidation accumulation and further cell membrane rupture caused by excessive production of intracellular oxygen free radicals dependent on iron ions. Esophageal cancer is one of the common digestive tract tumors. Patients in the early stage are mainly treated with surgery, and the curative effect is awe-inspiring. However, surgery is far from enough for terminal patients, and it is the best choice to combine radiotherapy and chemotherapy before the operation or during the perioperative period. Although the treatment plan for patients with advanced esophageal cancer is constantly being optimized, we are disappointed at the still meager 5-year survival rate of patients and the poor quality of life. A series of complex problems, such as increased chemotherapy drug resistance and decreased radiotherapy sensitivity of esophageal cancer cells, are waiting for us to tackle. Perhaps ferroptosis can provide practical and feasible solutions and bring new hope to patients with advanced esophageal cancer. The occurrence of ferroptosis is related to the dysregulation of iron metabolism, lipid metabolism, and glutamate metabolism. Therefore, these dysregulated metabolic participant proteins and signaling pathways are essential entry points for using cellular ferroptosis to resist the occurrence and development of cancer cells. This review first introduced the main regulatory mechanisms of ferroptosis. It then summarized the current research status of ferroptosis in esophageal cancer, expecting to provide ideas for the research related to ferroptosis in esophageal cancer.

Analysis and Validation of Differentially Expressed Ferroptosis-Related Genes in Regorafenib-Induced Cardiotoxicity

Background

Although tyrosine kinase inhibitors (TKIs) constitute a type of anticancer drugs, the underlying mechanisms of TKI-associated cardiotoxicity remain largely unknown. Ferroptosis is a regulated cell death form that implicated in several tumors' biological processes. Our objective was to probe into the differential expression of ferroptosis-related genes in regorafenib-induced cardiotoxicity through multiple bioinformatics analysis and validation.

Methods and Materials

Four adult human cardiomyocyte cell lines treated with regorafenib were profiled using Gene Expression Omnibus (GEO) (GSE146096). Differentially expressed genes (DEGs) were identified using DESeq2 in R (V.3.6.3). Then, Gene Ontology (GO) Enrichment Analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) Enrichment Analysis, and Gene Set Enrichment Analysis (GSEA) were used to explore DEGs' bioinformatics functions and enriched pathways. We intersected DEGs with 259 ferroptosis-related genes from the FerrDb database. Finally, the mRNA levels of differentially expressed ferroptosis-related genes (DEFRGs) were validated in regorafenib-cultured cardiomyocytes to anticipate the link between DEFRGs and cardiotoxicity.

Results

747,1127,773 and 969 DEGs were screened out in adult human cardiomyocyte lines A, B, D, and E, respectively. The mechanism by which REG promotes cardiotoxicity associated with ferroptosis may be regulated by PI3K-Akt, TGF-beta, and MAPK. GSEA demonstrated that REG can promote cardiotoxicity by suppressing genes and pathways encoding extracellular matrix and related proteins, oxidative phosphorylation, or ATF-2 transcription factor network. After overlapping DEGs with ferroptosis-related genes, we got seven DEFRGs and found that ATF3, MT1G, and PLIN2 were upregulated and DDIT4 was downregulated. The ROC curve demonstrated that these genes predict regorafenib-induced cardiotoxicity well.

Conclusion

We identified four DEFRGs which may become potential predictors and participate in the regorafenib-induced cardiotoxicity. Our findings provide possibility that targeting these ferroptosis-related genes may be an alternative for clinical prevention and therapy of regorafenib-related cardiotoxicity.

Discovery of a New Class of Uracil Derivatives as Potential Mixed Lineage Kinase Domain-like Protein (MLKL) Inhibitors

Necroptosis is a form of programmed cell death. Mixed lineage kinase domain-like protein (MLKL) is the necroptosis executor, and it is involved in various diseases such as tissue damage and neurodegeneration-related diseases. Here, we report the development of novel MLKL inhibitors with a uracil nucleus through scaffold morphing from our previously reported xanthine MLKL inhibitor TC13172. After a rational structure-activity relationship study, we obtained the highly potent compounds 56 and 66. Mechanism studies revealed that these compounds partially inhibited MLKL oligomerization and significantly inhibited MLKL translocation to the membrane. Compared with TC13172, 56 and 66 have a different mode of action and, importantly, their reaction rate with glutathione is more than 150-fold lower. This reduction in potential off-target effects and cell toxicity makes this series an attractive starting point for further drug development for MLKL-related disease treatments.

Context-dependent regulation of ferroptosis sensitivity

Ferroptosis is an important mediator of pathophysiological cell death and an emerging target for cancer therapy. Whether ferroptosis sensitivity is governed by a single regulatory mechanism is unclear. Here, based on the integration of 24 published chemical genetic screens combined with targeted follow-up experimentation, we find that the genetic regulation of ferroptosis sensitivity is highly variable and context-dependent. For example, the lipid metabolic gene acyl-coenzyme A (CoA) synthetase long chain family member 4 (ACSL4) appears far more essential for ferroptosis triggered by direct inhibition of the lipid hydroperoxidase glutathione peroxidase 4 (GPX4) than by cystine deprivation. Despite this, distinct pro-ferroptotic stimuli converge upon a common lethal effector mechanism: accumulation of lipid peroxides at the plasma membrane. These results indicate that distinct genetic mechanisms regulate ferroptosis sensitivity, with implications for the initiation and analysis of this process in vivo.