Breakdown of an Ironclad Defense System: The Critical Role of NRF2 in Mediating Ferroptosis

The role of ferroptosis in esophageal cancer

Esophageal cancer is one of the most common cancers with high mortality rate around the world. Although the treatment strategy of this disease has made great progress, the prognosis of advanced patients is not ideal. Ferroptosis, a novel regulatory cell death model, that is different from traditional apoptosis and characterized by increased Fenton reaction mediated by intracellular free iron and lipid peroxidation of cell membrane. Ferroptosis has been proved to be closely linked to a variety of diseases, especially cancer. This review aims to summarize the core mechanism of ferroptosis in esophageal cancer, the regulation of ferroptosis signaling pathway and its current application. At the same time, we emphasize the potential and prospect of ferroptosis in the treatment of esophageal cancer. Collectively, targeting ferroptosis pathway may provide new insights into the diagnosis, treatment and prognosis of esophageal cancer.

Emerging role of ferroptosis in glioblastoma: Therapeutic opportunities and challenges

Glioblastoma (GBM) is the most common malignant craniocerebral tumor. The treatment of this cancer is difficult due to its high heterogeneity and immunosuppressive microenvironment. Ferroptosis is a newly found non-apoptotic regulatory cell death process that plays a vital role in a variety of brain diseases, including cerebral hemorrhage, neurodegenerative diseases, and primary or metastatic brain tumors. Recent studies have shown that targeting ferroptosis can be an effective strategy to overcome resistance to tumor therapy and immune escape mechanisms. This suggests that combining ferroptosis-based therapies with other treatments may be an effective strategy to improve the treatment of GBM. Here, we critically reviewed existing studies on the effect of ferroptosis on GBM therapies such as chemotherapy, radiotherapy, immunotherapy, and targeted therapy. In particular, this review discussed the potential of ferroptosis inducers to reverse drug resistance and enhance the sensitivity of conventional cancer therapy in combination with ferroptosis. Finally, we highlighted the therapeutic opportunities and challenges facing the clinical application of ferroptosis-based therapies in GBM. The data generated here provide new insights and directions for future research on the significance of ferroptosis-based therapies in GBM.

Targeting Ferroptosis in Colorectal Cancer

Ferroptosis is a unique way of regulating cell death (RCD), which is quite different from other programmed cell deaths such as autophagy. It presents iron overload, accumulation of reactive oxygen species (ROS), and lipid peroxidation. A ferroptotic cell usually has an intact cell structure as well as shrinking mitochondria with decreased or vanishing cristae, concentrated membrane density, and ruptured outer membrane. Recently, increasing investigations have discovered that tumor cells have a much greater iron demand than the normal ones, making them more sensitive to ferroptosis. In other words, ferroptosis may inhibit the progress of the tumor, which can be used in the therapy of tumor patients, especially for those with chemotherapy resistance. Therefore, ferroptosis has become one hot spot in the field of tumor research in recent years. Colorectal cancer (CRC) is one common type of gastrointestinal malignancy. The incidence of CRC appears to have an upward trend year by year since the enhancement of living standards. Although surgery and chemoradiotherapy have largely improved the prognosis of patients with CRC, some patients still appear to have severe adverse reactions and drug resistance. Moreover, much research has verified that ferroptosis has a necessary association with the occurrence and progression of gastrointestinal tumors. In this review, we provide a comprehensive evaluation of the main mechanisms of iron metabolism, lipid metabolism, and amino acid metabolism involved in the occurrence of ferroptosis, as well as the research progress of ferroptosis in CRC.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe²⁺, Ca²⁺, Zn²⁺, etc.) and anions (Cl^-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

Machine learning for the micropeptide encoded by LINC02381 regulates ferroptosis through the glucose transporter SLC2A10 in glioblastoma

Glioblastoma (GBM) is the most common primary intracranial tumor in the central nervous system, and resistance to temozolomide is an important reason for the failure of GBM treatment. We screened out that Solute Carrier Family 2 Member 10 (SLC2A10) is significantly highly expressed in GBM with a poor prognosis, which is also enriched in the NF-E2 p45-related factor 2 (NRF2) signalling pathway. The NRF2 signalling pathway is an important defence mechanism against ferroptosis. SLC2A10 related LINC02381 is highly expressed in GBM, which is localized in the cytoplasm/exosomes, and LINC02381 encoded micropeptides are localized in the exosomes. The micropeptide encoded by LINC02381 may be a potential treatment strategy for GBM, but the underlying mechanism of its function is not precise yet. We put forward the hypothesis: “The micropeptide encoded by LINC02381 regulates ferroptosis through the glucose transporter SLC2A10 in GBM.” This study innovatively used machine learning for micropeptide to provide personalized diagnosis and treatment plans for precise treatment of GBM, thereby promoting the development of translational medicine. The study aimed to help find new disease diagnoses and prognostic biomarkers and provide a new strategy for experimental scientists to design the downstream validation experiments.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

Nrf2 Knockout Affected the Ferroptosis Signaling Pathway against Cisplatin-Induced Hair Cell-Like HEI-OC1 Cell Death

Cisplatin is a well-known and widely used anticancer drug with high therapeutic efficacy in solid tumors; however, side effects are common with its use. Because cisplatin can be retained in the cochlea, ototoxicity leading to hearing loss limits its clinical applications. Here, we report that Nrf2 knockout (KO) strongly increased cisplatin resistance in HEI-OC1 cells, which are immortalized cells from the murine organ of Corti. The underlying mechanism of this phenomenon was uncovered, and an important novel therapeutic target for combating cisplatin-induced hearing loss was identified. Preliminary investigations determined that Nrf2 KO markedly decreased TfR1 protein levels and increased GPX4 protein levels. Thus, ferroptosis may protect organisms from cisplatin-induced cell death. Furthermore, Nrf2 KO cells were resistant to the classical ferroptosis inducers RSL3 and erastin, providing solid evidence that Nrf2 KO inhibits ferroptosis and that knocking out Nrf2 may be a new clinical strategy to prevent cisplatin-induced hearing loss.

Targeting ferroptosis as a vulnerability in cancer

Ferroptosis is an iron-dependent form of regulated cell death that is triggered by the toxic build-up of lipid peroxides on cellular membranes. In recent years, ferroptosis has garnered enormous interest in cancer research communities, partly because it is a unique cell death modality that is mechanistically and morphologically different from other forms of cell death, such as apoptosis, and therefore holds great potential for cancer therapy. In this Review, we summarize the current understanding of ferroptosis-inducing and ferroptosis defence mechanisms, dissect the roles and mechanisms of ferroptosis in tumour suppression and tumour immunity, conceptualize the diverse vulnerabilities of cancer cells to ferroptosis, and explore therapeutic strategies for targeting ferroptosis in cancer.

Targeting Ferroptosis Attenuates Inflammation, Fibrosis, and Mast Cell Activation in Chronic Prostatitis

Purpose

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common urological disorder. Although ferroptosis is closely associated with inflammation, oxidative stress, and neuropathic pain, its role in CP/CPPS has not yet been elucidated. Therefore, we sought to explore the role and mechanism of ferroptosis in the prostatitis development.

Methods

The experimental autoimmune prostatitis (EAP) was established through intradermal immunization of prostate extract. Iron chelator deferoxamine (DFO) and free radical scavenger edaravone (EDA) were applied to evaluate the effects of ferroptosis inhibition on oxidative stress, ferroptosis, inflammation, fibrosis, and mast cell activation in the context of CP/CPPS.

Results

Increased generation of lipid peroxidation products (ROS and MDA) and decreased activities of antioxidant enzymes (SOD and CAT) suggested an aberrant oxidative stress status in EAP model. Elevated iron concentration was observed in the EAP model. Meanwhile, we discovered significant biological performances associated with ferroptosis in CP/CPPS, including the downregulation of the system Xc^-/GPX4 axis and the upregulation of the ACSL4/LPCAT3 axis. EAP rats performed serious leukocyte infiltration, advanced inflammatory grade, and abnormal expression of inflammatory mediators. Abundant collagen deposition, enhanced RhoA, ROCK1, and α-SMA protein levels indicated that EAP rats were prone to suffer from stromal fibrosis compared with control group. An elevated number of degranulated mast cells and corresponding marker TPSB2 represented that mast cell-sensitized pain was amplified in the EAP model. Furthermore, reduction of NRF2/HO-1 indicated a vulnerability of EAP towards ferroptosis response. However, application of DFO and EDA had partially reversed the adverse influences mentioned above.

Conclusion

We first demonstrated that ferroptosis might be a crucial factor of chronic prostatitis progression. Inhibition of ferroptosis using DFO and EDA represented a promising approach for treating prostatitis by ameliorating inflammation, fibrosis, and mast cell activation.

Nutritional and Metabolic Control of Ferroptosis

Ferroptosis is a type of regulated cell death characterized by an excessive lipid peroxidation of cellular membranes caused by the disruption of the antioxidant defense system and/or an imbalanced cellular metabolism. Ferroptosis differentiates from other forms of regulated cell death in that several metabolic pathways and nutritional aspects, including endogenous antioxidants (such as coenzyme Q₁₀, vitamin E, and di/tetrahydrobiopterin), iron handling, energy sensing, selenium utilization, amino acids, and fatty acids, directly regulate the cells' sensitivity to lipid peroxidation and ferroptosis. As hallmarks of ferroptosis have been documented in a variety of diseases, including neurodegeneration, acute organ injury, and therapy-resistant tumors, the modulation of ferroptosis using pharmacological tools or by metabolic reprogramming holds great potential for the treatment of ferroptosis-associated diseases and cancer therapy. Hence, this review focuses on the regulation of ferroptosis by metabolic and nutritional cues and discusses the potential of nutritional interventions for therapy by targeting ferroptosis. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Hydrogen sulfide alleviates particulate matter-induced emphysema and airway inflammation by suppressing ferroptosis

BACKGROUND

Redox imbalance is an vital mechanism for COPD. At present, insufficient researches have been conducted on the protective effect of hydrogen sulfide (H₂S) on PM-induced COPD. However, whether H₂S exerts the anti-injury role by blocking ferroptosis and restoring redox equilibrium remain to be investigated.

METHODS

Human lung tissue samples were collected for IHC staining, and the expressions of Nrf2, ferritinophagy- and ferroptosis-related proteins were observed. The WT C57BL/6 and Nrf2 knockout mice models were established with PM(200 μg per mouse). NaHS(Exogenous H₂S) was injected intraperitoneally 30 min in advance. Twenty-nine days later, mice lung tissues were evaluated by HE's and PERLS-DAB's staining. Meanwhile, inflammation and oxidative stress indicators and iron levels were assessed by corresponding ELISA kit. Related protein expressions were detected through Western blot. BEAS-2B cells with or without H₂S were exposed to PM2.5 for 36 h. Cell viability, mitochondrial morphology, inflammatory cytokines, antioxidant factors, iron levels, autophagic flux and the levels of ROS, LIP ROS, MitoROS, MMP, as well as related protein expressions were detected by specific methods, respectively. In addition, V5-Nrf2, Nrf2 siRNA, Nrf2 inhibitor ML385, PPAR-γ inhibitor GW9662, autophagy inhibitor CQ, iron chelator DFO and ferroptosis inhibitor Fer-1 were used to verify the target signaling pathways.

RESULTS

We found that the expressions of LIP ROS, ROS, COX2, MDA and other oxidative factors increased, while the antioxidant markers GPX4, GSH and GSH-Px significantly decreased, as well as active iron accumulation in COPD patients, PM-exposured WT and Nrf2-KO mice models and PM2.5-mediated cell models. NaHS pretreatment markedly inhibited PM-induced emphysema and airway inflammation by alleviating ferroptotic changes in vivo and vitro. With the use of V5-Nrf2 overexpression plasmid, Nrf2 siRNA and pathway inhibitors, we found NaHS activates the expressions of Nrf2 and PPAR-γ, and inhibites ferritinophagy makers LC3B, NCOA4 and FTH1 in BEAS-2B cells. Moreover, the anti-ferroptotic effect of NaHS was further verified to be related to the activation of Nrf2 signal in MEF cells.

CONCLUSION

This research suggested that H₂S alleviated PM-induced emphysema and airway inflammation via restoring redox balance and inhibiting ferroptosis through regulating Nrf2-PPAR-ferritinophagy signaling pathway.

Type 2 diabetes mellitus-associated cognitive dysfunction: Advances in potential mechanisms and therapies

Type 2 diabetes (T2D) and its target organ injuries cause distressing impacts on personal health and put an enormous burden on the healthcare system, and increasing attention has been paid to T2D-associated cognitive dysfunction (TDACD). TDACD is characterized by cognitive dysfunction, delayed executive ability, and impeded information-processing speed. Brain imaging data suggest that extensive brain regions are affected in patients with T2D. Based on current findings, a wide spectrum of non-specific neurodegenerative mechanisms that partially overlap with the mechanisms of neurodegenerative diseases is hypothesized to be associated with TDACD. However, it remains unclear whether TDACD is a consequence of T2D or a complication that co-occurs with T2D. Theoretically, anti-diabetes methods are promising neuromodulatory approaches to reduce brain injury in patients with T2D. In this review, we summarize potential mechanisms underlying TDACD and promising neurotropic effects of anti-diabetes methods and some neuroprotective natural compounds. Constructing screening or diagnostic tools and developing targeted treatment and preventive strategies would be expected to reduce the burden of TDACD.

LncRNA PELATON, a Ferroptosis Suppressor and Prognositic Signature for GBM

PELATON is a long noncoding RNA also known as long intergenic nonprotein coding RNA 1272 (LINC01272). The known reports showed that PELATON functions as an onco-lncRNA or a suppressor lncRNA by suppressing miRNA in colorectal cancer, gastric cancer and lung cancer. In this study, we first found that PELATON, as an onco-lncRNA, alleviates the ferroptosis driven by mutant p53 and promotes mutant p53-mediated GBM proliferation. We also first confirmed that PELATON is a new ferroptosis suppressor lncRNA that functions as a ferroptosis inhibitor mainly by mutant P53 mediating the ROS ferroptosis pathway, which inhibits the production of ROS, reduces the levels of divalent iron ions, promotes the expression of SLC7A11, and inhibits the expression of ACSL4 and COX2.PELATON can inhibit the expression of p53 in p53 wild-type GBM cells and regulate the expression of BACH1 and CD44, but it has no effect on p53, BACH1 and CD44 in p53 mutant GBM cells. PELATON and p53 can form a complex through the RNA binding protein EIF4A3. Knockdown of PELATON resulted in smaller mitochondria, increased mitochondrial membrane density, and enhanced sensitivity to ferroptosis inducers to inhibit GBM cell proliferation and invasion. In addition, we established a favourite prognostic model with NCOA4 and PELATON. PELATON is a promising target for the prognosis and treatment of GBM.

A targetable CoQ-FSP1 axis drives ferroptosis- and radiation-resistance in KEAP1 inactive lung cancers

Targeting ferroptosis, a unique cell death modality triggered by unrestricted lipid peroxidation, in cancer therapy is hindered by our incomplete understanding of ferroptosis mechanisms under specific cancer genetic contexts. KEAP1 (kelch-like ECH associated protein 1) is frequently mutated or inactivated in lung cancers, and KEAP1 mutant lung cancers are refractory to most therapies, including radiotherapy. In this study, we identify ferroptosis suppressor protein 1 (FSP1, also known as AIFM2) as a transcriptional target of nuclear factor erythroid 2-related factor 2 (NRF2) and reveal that the ubiquinone (CoQ)-FSP1 axis mediates ferroptosis- and radiation- resistance in KEAP1 deficient lung cancer cells. We further show that pharmacological inhibition of the CoQ-FSP1 axis sensitizes KEAP1 deficient lung cancer cells or patient-derived xenograft tumors to radiation through inducing ferroptosis. Together, our study identifies CoQ-FSP1 as a key downstream effector of KEAP1-NRF2 pathway and as a potential therapeutic target for treating KEAP1 mutant lung cancers.

Activation of the PPARγ Prevents Ferroptosis-Induced Neuronal Loss in Response to Intracerebral Hemorrhage Through Synergistic Actions With the Nrf2

Intracerebral hemorrhage (ICH) is a subtype of stroke characterized by high mortality and disability rates. The long-term effects of ICH-induced intracranial hematoma on patients’ neurological function are unclear. Currently, an effective treatment that significantly reduces the rates of death and disability in patients with ICH is not available. Based on accumulating evidence, ferroptosis may be the leading factor contributing to the neurological impairment caused by ICH injury. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated receptor in the nuclear hormone receptor family that synergistically interacts with the nuclear factor erythrocyte 2-related factor 2 (Nrf2) pathway to promote the expression of related genes and inhibit ferroptosis. Primary rat hippocampal neurons were treated with heme (50 μM) and erastin (50 μM) to induce ferroptosis, followed by the PPARγ agonist pioglitazone (PDZ, 10 μM) to verify the inhibitory effect of PPARγ activation on ferroptosis. ML385 (2 μM), a novel and specific NRF2 inhibitor, was administered to the inhibitor group, followed by an analysis of cellular activity and immunofluorescence staining. In vivo Assays, ICH rats injected with autologous striatum were treated with 30 mg/kg/d pioglitazone, and the inhibitor group was injected with ML385 (30 mg/kg). The results showed that PDZ inhibited ferroptosis in neurons by increasing the expression of PPARγ, Nrf2 and Gpx4 in vitro, while PDZ reduced ferroptosis in neurons after ICH and promoted the recovery of neural function in vivo. Our results suggest that PDZ, a PPARγ agonist, promotes Gpx4 expression through the interaction between PPARγ and the Nrf2 pathway, inhibits ferroptosis of neurons after ICH, and promotes the recovery of neural function.

High Level of Uric Acid Promotes Atherosclerosis by Targeting NRF2-Mediated Autophagy Dysfunction and Ferroptosis

Atherosclerotic vascular disease (ASVD) is the leading cause of death worldwide. Hyperuricemia is the fourth risk factor for atherosclerosis after hypertension, diabetes, and hyperlipidemia. The mechanism of hyperuricemia affecting the occurrence and development of atherosclerosis has not been fully elucidated. Mononuclear macrophages play critical roles in all stages of atherosclerosis. Studies have confirmed that both hyperuricemia and ferroptosis promote atherosclerosis, but whether high level of uric acid (HUA) promotes atherosclerosis by regulating ferroptosis in macrophages remains unclear. We found that HUA significantly promoted the development of atherosclerotic plaque and downregulated the protein level of the NRF2/SLC7A11/GPX4 signaling pathway in ApoE−/− mice. Next, we evaluated the effect of HUA and ferroptosis inhibitor ferrostatin-1 (Fer-1) treatment on the formation of macrophage-derived foam cells. HUA promoted the formation of foam cells, decreased cell viability, and increased iron accumulation and lipid peroxidation in macrophages treated with oxidized low-density lipoprotein (oxLDL); these effects were reversed by Fer-1 treatment. Mechanistically, HUA significantly inhibited autophagy and the protein level of the NRF2/SLC7A11/GPX4 signaling pathway. Fer-1 activated autophagy and upregulated the level of ferroptosis-associated proteins. Moreover, an NRF2 inducer (tertbutyl hydroquinone (TBHQ)) and autophagy activator (rapamycin (RAPA)) could reverse the inhibitory effect of HUA on foam cell survival. Our results suggest that HUA-induced ferroptosis of macrophages is involved in the formation of atherosclerotic plaques. More importantly, enhancing autophagy and inhibiting ferroptosis by activating NRF2 may alleviate HUA-induced atherosclerosis. These findings might contribute to a deeper understanding of the role of HUA in the pathogenesis of atherosclerosis and provide a therapeutic target for ASVD associated with hyperuricemia.

Non-coding RNAs in ferroptotic cancer cell death pathway: meet the new masters

Despite the recent advances in cancer therapy, cancer chemoresistance looms large along with radioresistance, a major challenge in dire need of thorough and minute investigation. Not long ago, cancer cells were reported to have proven refractory to the ferroptotic cell death, a newly discovered form of regulated cell death (RCD), conspicuous enough to draw attention from scholars in terms of targeting ferroptosis as a prospective therapeutic strategy. However, our knowledge concerning the underlying molecular mechanisms through which cancer cells gain immunity against ferroptosis is still in its infancy. Of late, the implication of non-coding RNAs (ncRNAs), including circular RNAs (circRNAs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) in ferroptosis has been disclosed. Nevertheless, precisely explaining the molecular mechanisms behind the contribution of ncRNAs to cancer radio/chemotherapy resistance remains a challenge, requiring further clarification. In this review, we have presented the latest available information on the ways and means of regulating ferroptosis by ncRNAs. Moreover, we have provided important insights about targeting ncRNAs implicated in ferroptosis with the hope of opening up new horizons for overcoming cancer treatment modalities. Though a long path awaits until we make this ambitious dream come true, recent progress in gene therapy, including gene-editing technology will aid us to be optimistic that ncRNAs-based ferroptosis targeting would soon be on stream as a novel therapeutic strategy for treating cancer.

CEMIP promotes extracellular matrix-detached prostate cancer cells survival by inhibiting ferroptosis

Cells detached from the extracellular matrix (ECM) can trigger different modes of cell death, and the survival of ECM‐detached cells is one of the prerequisites for the metastatic cascade. Ferroptosis, a form of iron‐dependent programmed cell death, has recently been found to be involved in matrix‐detached cancer cells. However, the molecular mechanisms by which ECM‐detached cells escape ferroptosis are not fully understood. Here, we observed that cell migration‐inducing protein (CEMIP) upregulation facilitates ferroptosis resistance during ECM detachment by promoting cystine uptake in prostate cancer (PCa) cells. Meanwhile, silencing CEMIP causes it to lose its ability to promote cystine uptake and inhibit ferroptosis. Mechanistically, the interaction of CEMIP with inositol 1,4,5‐trisphosphate receptor type 3 (ITPR3) modulates calcium ion (Ca²⁺) leakage from the endoplasmic reticulum, activating calcium/calmodulin‐dependent protein kinase II (CaMKII), which further facilitates nuclear factor erythroid 2‐related factor 2 (NRF2) phosphorylation and nuclear localization, leading to elevated transcription of solute carrier family 7 member 11 (SLC7A11), a glutamate/cystine antiporter, in PCa cells. Our findings delineate a novel role of CEMIP in ferroptosis resistance during ECM detachment and provide new insights into therapeutic strategies for metastatic PCa.

Ferroptosis as a Novel Determinant of β-Cell Death in Diabetic Conditions

The main pathological hallmark of diabetes is the loss of functional β-cells. Among several types of β-cell death in diabetes, the involvement of ferroptosis remains elusive. Therefore, we investigated the potential of diabetes-mimicking factors: high glucose (HG), proinflammatory cytokines, hydrogen peroxide (H₂O₂), or diabetogenic agent streptozotocin (STZ) to induce ferroptosis of β-cells in vitro. Furthermore, we tested the contribution of ferroptosis to injury of pancreatic islets in an STZ-induced in vivo diabetic model. All in vitro treatments increased loss of Rin-5F cells along with the accumulation of reactive oxygen species, lipid peroxides and iron, inactivation of NF-E2-related factor 2 (Nrf2), and decrease in glutathione peroxidase 4 expression and mitochondrial membrane potential (MMP). Ferrostatin 1 (Fer-1), ferroptosis inhibitor, diminished the above-stated effects and rescued cells from death in case of HG, STZ, and H₂O₂ treatments, while failed to increase MMP and to attenuate cell death after the cytokines' treatment. Moreover, Fer-1 protected pancreatic islets from STZ-induced injury in diabetic in vivo model, since it decreased infiltration of macrophages and accumulation of lipid peroxides and increased the population of insulin-positive cells. Such results revealed differences between diabetogenic stimuli in determining the destiny of β-cells, emerging HG, H₂O₂, and STZ, but not cytokines, as contributing factors to ferroptosis and shed new light on an antidiabetic strategy based on Nrf2 activation. Thus, targeting ferroptosis in diabetes might be a promising new approach for preservation of the β-cell population. Our results obtained from in vivo study strongly justify this approach.

Nucleic Acid Nanotechnology for Diagnostics and Therapeutics in Acute Kidney Injury

Acute kidney injury (AKI) has impacted a heavy burden on global healthcare system with a high morbidity and mortality in both hospitalized and critically ill patients. However, there are still some shortcomings in clinical approaches for the disease to date, appealing for an earlier recognition and specific intervention to improve long-term outcomes. In the past decades, owing to the predictable base-pairing rule and highly modifiable characteristics, nucleic acids have already become significant biomaterials for nanostructure and nanodevice fabrication, which is known as nucleic acid nanotechnology. In particular, its excellent programmability and biocompatibility have further promoted its intersection with medical challenges. Lately, there have been an influx of research connecting nucleic acid nanotechnology with the clinical needs for renal diseases, especially AKI. In this review, we begin with the diagnostics of AKI based on nucleic acid nanotechnology with a highlight on aptamer- and probe-functionalized detection. Then, recently developed nanoscale nucleic acid therapeutics towards AKI will be fully elucidated. Furthermore, the strengths and limitations will be summarized, envisioning a wiser and wider application of nucleic acid nanotechnology in the future of AKI.

Fisetin Attenuates Doxorubicin-Induced Cardiomyopathy In Vivo and In Vitro by Inhibiting Ferroptosis Through SIRT1/Nrf2 Signaling Pathway Activation

Doxorubicin (DOX) is an anthracycline antibiotic that is used extensively for the management of carcinoma; however, its clinical application is limited due to its serious cardiotoxic side effects. Ferroptosis represents iron-dependent and reactive oxygen species (ROS)-related cell death and has been proven to contribute to the progression of DOX-induced cardiomyopathy. Fisetin is a natural flavonoid that is abundantly present in fruits and vegetables. It has been reported to exert cardioprotective effects against DOX-induced cardiotoxicity in experimental rats. However, the underlying mechanisms remain unknown. The present study investigated the cardioprotective role of fisetin and the underlying molecular mechanism through experiments in the DOX-induced cardiomyopathy rat and H9c2 cell models. The results revealed that fisetin treatment could markedly abate DOX-induced cardiotoxicity by alleviating cardiac dysfunction, ameliorating myocardial fibrosis, mitigating cardiac hypertrophy in rats, and attenuating ferroptosis of cardiomyocytes by reversing the decline in the GPX4 level. Mechanistically, fisetin exerted its antioxidant effect by reducing the MDA and lipid ROS levels and increasing the glutathione (GSH) level. Moreover, fisetin exerted its protective effect by increasing the SIRT1 expression and the Nrf2 mRNA and protein levels and its nuclear translocation, which resulted in the activation of its downstream genes such as HO-1 and FTH1. Selective inhibition of SIRT1 attenuated the protective effects of fisetin in the H9c2 cells, which in turn decreased the GSH and GPX4 levels, as well as Nrf2, HO-1, and FTH1 expressions. In conclusion, fisetin exerts its therapeutic effects against DOX-induced cardiomyopathy by inhibiting ferroptosis via SIRT1/Nrf2 signaling pathway activation.

The Role of Cystine/Glutamate Antiporter SLC7A11/xCT in the Pathophysiology of Cancer

SLC7A11/xCT is an antiporter that mediates the uptake of extracellular cystine in exchange for glutamate. Cystine is reduced to cysteine, which is a rate-limiting precursor in glutathione synthesis; a process that protects cells from oxidative stress and is, therefore, critical to cell growth, proliferation, and metabolism. SLC7A11 is expressed in different tissues and plays diverse functional roles in the pathophysiology of various diseases, including cancer, by regulating the processes of redox homeostasis, metabolic flexibility/nutrient dependency, immune system function, and ferroptosis. SLC7A11 expression is associated with poor prognosis and drug resistance in cancer and, therefore, represents an important therapeutic target. In this review, we discuss the molecular functions of SLC7A11 in normal versus diseased tissues, with a special focus on how it regulates gastrointestinal cancers. Further, we summarize current therapeutic strategies targeting SLC7A11 as well as novel avenues for treatment.

A comparative study of the effect of a gentle ketogenic diet containing medium-chain or long-chain triglycerides on chronic sleep deprivation-induced cognitive deficiency

The ketogenic diet (KD) is well known for its neuroprotective effect, but little is known about its prophylactic efficacy against chronic sleep deprivation (SD) induced cognitive deficiency. An emerging study indicated that ferroptosis plays an important role in neurologic diseases but has been rarely reported in chronic SD. Here, we investigated the prophylactic effects of a medium-chain triglyceride-enriched KD (MKD) and a long-chain triglyceride-enriched KD (LKD) on cognitive deficiency and revealed the underlying mechanism focused on ferroptosis in chronic SD model mice. The results showed that the MKD exhibited stronger effects than the LKD on improving cognitive deficiency via suppressing ferroptosis and improving synaptic plasticity. Further mechanism results indicated that MKD produced higher Sirt3 protein levels than LKD, which probably contributed to the synergistic effect of beta hydroxybutyric acid and decanoic acid. Our finds provide novel evidence for the KD as a safe and feasible dietary intervention to prevent chronic SD-induced cognitive deficiency, and suggest a better choice of medium-chain fatty acid-enriched KD.

Ferritinophagy-Mediated Ferroptosis and Activation of Keap1/Nrf2/HO-1 Pathway Were Conducive to EMT Inhibition of Gastric Cancer Cells in Action of 2,2'-Di-pyridineketone Hydrazone Dithiocarbamate Butyric Acid Ester

In metastasis of cancer cells, the epithelial-mesenchymal transition (EMT) is prerequired. Ferroptosis is an iron-mediated cellular death process, but whether it involves EMT regulation remains elusive. In addition, how stress responders (Nrf2) respond to the redox alteration and cross-talking between them needs to be determined. Our data revealed that DpdtbA (2,2'-di-pyridineketone hydrazone dithiocarbamate butyric acid ester) resisted TGF-β1-induced EMT in gastric cancer lines (SGC-7901 and MGC-823) through ferritinophagy-mediated ROS production. Furthermore, the depletion of Gpx4 and xCT as well as enhanced lipid peroxidation indicated that DpdtbA acted as Erastin did in ferroptosis induction, which thus provided chance to explore the causal relationship between ferroptosis and EMT. Our data illustrated that ferritinophagy-mediated ferroptosis promoted the EMT inhibition. In addition, activated Nrf2 involved the regulation on both ferroptosis and EMT in response to the alteration in the cellular redox environment. In brief, ferritinophagy-mediated ferroptosis and activation of the Keap1/Nrf2/HO-1 pathway were conducive to the EMT inhibition.

Ferroptosis in cancer and cancer immunotherapy

The hallmark of tumorigenesis is the successful circumvention of cell death regulation for achieving unlimited replication and immortality. Ferroptosis is a newly identified type of cell death dependent on lipid peroxidation which differs from classical programmed cell death in terms of morphology, physiology and biochemistry. The broad spectrum of injury and tumor tolerance are the main reasons for radiotherapy and chemotherapy failure. The effective rate of tumor immunotherapy as a new treatment method is less than 30%. Ferroptosis can be seen in radiotherapy, chemotherapy, and tumor immunotherapy; therefore, ferroptosis activation may be a potential strategy to overcome the drug resistance mechanism of traditional cancer treatments. In this review, the characteristics and causes of cell death by lipid peroxidation in ferroptosis are briefly described. In addition, the three metabolic regulations of ferroptosis and its crosstalk with classical signaling pathways are summarized. Collectively, these findings suggest the vital role of ferroptosis in immunotherapy based on the interaction of ferroptosis with tumor immunotherapy, chemotherapy and radiotherapy, thus, indicating the remarkable potential of ferroptosis in cancer treatment.

Ferroptosis: regulation by competition between NRF2 and BACH1 and propagation of the death signal

Ferroptosis is triggered by a chain of intracellular labile iron-dependent peroxidation of cell membrane phospholipids. Ferroptosis is important not only as a cause of ischaemic and neurodegenerative diseases but also as a mechanism of cancer suppression, and a better understanding of its regulatory mechanism is required. It has become clear that ferroptosis is finely controlled by two oxidative stress-responsive transcription factors, NRF2 (NF-E2-related factor 2) and BACH1 (BTB and CNC homology 1). NRF2 and BACH1 inhibit and promote ferroptosis, respectively, by activating or suppressing the expression of genes in the major regulatory pathways of ferroptosis: intracellular labile iron metabolism, the GSH (glutathione) -GPX4 (glutathione peroxidase 4) pathway and the FSP1 (ferroptosis suppressor protein 1)-CoQ (coenzyme Q) pathway. In addition to this, NRF2 and BACH1 control ferroptosis through the regulation of lipid metabolism and cell differentiation. This multifaceted regulation of ferroptosis by NRF2 and BACH1 is considered to have been acquired during the evolution of multicellular organisms, allowing the utilization of ferroptosis for maintaining homeostasis, including cancer suppression. In terms of cell-cell interaction, it has been revealed that ferroptosis has the property of propagating to surrounding cells along with lipid peroxidation. The regulation of ferroptosis by NRF2 and BACH1 and the propagation phenomenon could be used to realize anticancer cell therapy in the future. In this review, these points will be summarized and discussed.

Induction and application of ferroptosis in cancer therapy

At present, more than one cell death pathways have been found, one of which is ferroptosis. Ferroptosis was discovered in 2012 and described as an iron-dependent and lipid peroxidation-driven regulated cell death pathway. In the past few years, ferroptosis has been shown to induce tumor cell death, providing new ideas for tumor treatment. In this article, we summarize the latest advances in ferroptosis-induced tumor therapy at the intersection of tumor biology, molecular biology, redox biology, and materials chemistry. First, we state the characteristics of ferroptosis in cells, then introduce the key molecular mechanism of ferroptosis, and describes the relationship between ferroptosis and oxidative stress signaling pathways. Finally, we focused on several types of ferroptosis inducers discovered by scholars, and the application of ferroptosis in systemic chemotherapy, radiotherapy, immunotherapy and nanomedicine, in the hope that ferroptosis can exert its potential in the treatment of tumors.

Ferroptosis Signaling and Regulators in Atherosclerosis

Atherosclerosis (AS) is a major cause of cardiovascular diseases such as coronary heart disease, heart failure and stroke. Abnormal lipid metabolism, oxidative stress and inflammation are the main features of AS. Ferroptosis is an iron-driven programmed cell death characterized by lipid peroxidation, which have been proved to participate in the development and progression of AS by different signal pathways. NRF2-Keap1 pathway decreases ferroptosis associated with AS by maintaining cellular iron homeostasis, increasing the production glutathione, GPX4 and NADPH. The p53 plays different roles in ferroptosis at different stages of AS in a transcription-dependent and transcription- independent manner. The Hippo pathway is involved in progression of AS, which has been proved the activation of ferroptosis. Other transcription factors, such as ATF3, ATF4, STAT3, also involved in the occurrence of ferroptosis and AS. Certain proteins or enzymes also have a regulatory role in AS and ferroptosis. In this paper, we review the mechanism of ferroptosis and its important role in AS in an attempt to find a new relationship between ferroptosis and AS and provide new ideas for the future treatment of AS.

The Art of War: Ferroptosis and Pancreatic Cancer

Pancreatic cancer is a devastating gastrointestinal cancer, characterized by late diagnosis, low treatment success rate, and poor survival prognosis. The most common pathological type of pancreatic cancer is pancreatic ductal adenocarcinoma (PDAC), which is mainly driven by the K-Ras oncogene. Ferroptosis was originally described as Ras-dependent cell death, but is now defined as lipid peroxidation-mediated regulated necrosis, accompanied by excessive activation of the autophagy degradation pathway and limited membrane repair capacity. The impaired ferroptotic pathway is involved in many types of cancer, including PDAC. On the one hand, the chronic inflammation caused by ferroptotic damage contributes to the formation of K-Ras-driven PDAC. On the other hand, drug-induced ferroptosis is an emerging strategy to suppress tumor growth in established PDAC. In this mini-review, we outline the core process of ferroptosis, discuss the regulatory mechanism of ferroptosis in PDAC, and highlight some of the challenges of targeting ferroptosis in PDAC therapy.

Maresin conjugates in tissue regeneration-1 suppresses ferroptosis in septic acute kidney injury

Background

Ferroptosis is unique among different types of regulated cell death and closely related to organ injury. Whether ferroptosis occurs in sepsis-associated acute kidney injury (SA-AKI) is not clear. Nuclear factor-erythroid-2-related factor 2 (Nrf2) is crucial to the regulation of ferroptosis. We and others have shown that Maresin conjugates in tissue regeneration 1 (MCTR1) or other members of specialized pro-resolving mediators (SPMs) can actively regulate inflammation resolution and protect organs against injury in inflammatory diseases by activating the Nrf2 signaling. The aim of this study was to determine whether ferroptosis occurs in SA-AKI. Furthermore, we investigated the potential role and mechanism of MCTR1 in the regulation of ferroptosis in SA-AKI, which mainly focus on the Nrf2 signaling.

Results

We demonstrated for the first time that ferroptosis is present in SA-AKI. Moreover, MCTR1 effectively suppressed ferroptosis in SA-AKI. Meanwhile, MCTR1 upregulated the expression of Nrf2 in the kidney of septic mice. Nrf2 inhibitor ML-385 reversed MCTR1-regulated ferroptosis and AKI, implying that Nrf2 is involved in the inhibitory effects of MCTR1 on ferroptosis in SA-AKI. Further, MCTR1 inhibited ferroptosis and elevated the expression of Nrf2 in LPS-induced HK-2 cells. However, Nrf2 siRNA offset the effect of MCTR1 on ferroptosis. Finally, we observed that MCTR1 ameliorates multi-organ injury and improves survival in animal models of sepsis.

Conclusions

These data demonstrate that MCTR1 suppresses ferroptosis in SA-AKI through the Nrf2 signaling. Our study enriches the pathophysiological mechanism of SA-AKI and provides new therapeutic ideas and potential intervention targets for SA-AKI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00734-x.

Hypermethylation of the Nrf2 Promoter Induces Ferroptosis by Inhibiting the Nrf2-GPX4 Axis in COPD

Background

Nuclear factor E2-related factor 2 (Nrf2) is involved in oxidative stress and lung inflammation and regulates the etiology of chronic obstructive pulmonary disease (COPD). Ferroptosis is characterized by the accumulation of lipid reactive oxygen species (ROS) via ferrous ion-dependent Fenton reactions and is involved in COPD. However, the role of Nrf2 in ferroptosis and its epigenetic regulation in the pathogenesis of COPD remain unclear.

Methods

Ferroptosis was detected by 4-HNE, MDA, C11BODIPY, DCFH-DA, Peals’ staining and CCK-8 assays. qPCR and Western blotting were performed to examine the Nrf2 levels in peripheral lung tissues, primary epithelial cells collected from patients with COPD and subjects with normal pulmonary function (never-smoker [control-NS]; smoker [control-S]), and cigarette smoke extract (CSE)-treated human bronchial epithelial (HBE) cells. ELISA was used to quantify IL-8 and IL-1β levels. Methylation of the Nrf2 promoter was analyzed by bisulfite sequencing and pyrosequencing.

Results

Ferroptosis was involved in COPD and glutathione peroxidase 4 (GPX4) expression was downregulated in the COPD group. Reactive oxygen species (ROS), lipid peroxides and MDA were increased, but GPX4 and SOD were exhausted in CSE-treated HBE cells. The production of IL-1β and IL-8 was promoted in HBE cells in response to CSE but could be reversed by the ferroptosis inhibitor fer-1. The Nrf2 level was significantly decreased in the COPD group compared with the control-S and control-NS groups. Increased Nrf2 expression enhanced GPX4 and SOD levels and inhibited ferroptosis and proinflammatory cytokines in the supernatant. Inhibition of GPX4 reversed the effect of Nrf2 overexpression and promoted ferroptosis. Two specific CpG sites within the Nrf2 promoter were hypermethylated in the COPD group. Similarly, CSE-treated HBE cells exhibited hypermethylation of the Nrf2 gene.

Conclusion

Nrf2 expression was downregulated in the lungs of COPD patients due to hypermethylation of the Nrf2 promoter, inhibiting Nrf2/GPX4 and ferroptosis, which is related to the initiation and progression of COPD. Targeting Nrf2/GPX4 may inhibit ferroptosis, which could provide strategies to delay or treat COPD.

Pharmacological Targeting of Ferroptosis in Cancer Treatment

Ferroptosis is a non-apoptotic mode of Regulated Cell Death (RCD) driven by excessive accumulation of toxic lipid peroxides and iron overload. Ferroptosis could be triggered by inhibiting the antioxidant defense system and accumulating iron-dependent Reactive Oxygen Species (ROS) that react with polyunsaturated fatty acids in abundance. Emerging evidence over the past few years has revealed that ferroptosis is of great potential in inhibiting growth and metastasis and overcoming tumor cell resistance. Thus, targeting this form of cell death could be perceived as a potentially burgeoning approach in cancer treatment. This review briefly presents the underlying mechanisms of ferroptosis and further aims to discuss various types of existing drugs and natural compounds that could be potentially repurposed for targeting ferroptosis in tumor cells. This, in turn, will provide critical perspectives on future studies concerning ferroptosis-based cancer therapy.

Suppression of uterine and placental ferroptosis by N-acetylcysteine in a rat model of polycystic ovary syndrome

The mechanisms that link hyperandrogenism and insulin (INS) resistance (HAIR) to the increased miscarriage rate in women with polycystic ovary syndrome (PCOS) remain elusive. Previous studies demonstrate that increased uterine and placental ferroptosis is associated with oxidative stress-induced fetal loss in a pre-clinical PCOS-like rat model. Here, we investigated the efficacy and molecular mechanism of action of the antioxidant N-acetylcysteine (NAC) in reversing gravid uterine and placental ferroptosis in pregnant rats exposed to 5α-dihydrotestosterone (DHT) and INS. Molecular and histological analyses showed that NAC attenuated DHT and INS-induced uterine ferroptosis, including dose-dependent increases in anti-ferroptosis gene content. Changes in other molecular factors after NAC treatment were also observed in the placenta exposed to DHT and INS, such as increased glutathione peroxidase 4 protein level. Furthermore, increased apoptosis-inducing factor mitochondria-associated 2 mRNA expression was seen in the placenta but not in the uterus. Additionally, NAC was not sufficient to rescue DHT + INS-induced mitochondria-morphological abnormalities in the uterus, whereas the same treatment partially reversed such abnormalities in the placenta. Finally, we demonstrated that NAC selectively normalized uterine leukemia inhibitory factor, osteopontin/secreted phosphoprotein 1, progesterone receptor, homeobox A11 mRNA expression and placental estrogen-related receptor beta and trophoblast-specific protein alpha mRNA expression. Collectively, our data provide insight into how NAC exerts beneficial effects on differentially attenuating gravid uterine and placental ferroptosis in a PCOS-like rat model with fetal loss. These results indicate that exogenous administration of NAC represents a potential therapeutic strategy in the treatment of HAIR-induced uterine and placental dysfunction.

Cashing in on ferroptosis against tumor cells: Usher in the next chapter

Ferroptosis is a new type of non-apoptotic regulated cell death (RCD) driven by unrestricted lethal lipid peroxidation, which is totally distinct from other forms of RCD in genetic and biochemical characteristics. It is generally believed that iron dependency, malfunction of the redox system, and excessive lipid peroxidation are the main hallmarks of ferroptosis. Accumulating pieces of evidence over the past few years have shown that ferroptosis is tightly related to various types of diseases, especially cancers. Ferroptosis has recently attracted great attention in the field of cancer research. A plethora of evidence shows that employing ferroptosis as a powerful weapon can remarkably enhance the efficacy of tumor cell annihilation. Better knowledge of the ferroptosis mechanisms and their interplay with cancer biology would enable us to use this fashionable tool in the best way. Herein, we will briefly present the relevant mechanisms of ferroptosis, the multifaceted relation between ferroptosis and cancer, encompassing tumor immunity, overcoming chemoresistance, and epithelial to mesenchymal transition. In the end, we will also briefly discuss the potential approaches to ferroptosis-based cancer therapy, such as using drugs and small molecules, nanoparticles, mitochondrial targeting, and photodynamic therapy.

Ferroptosis: New Dawn for Overcoming the Cardio-Cerebrovascular Diseases

The dynamic balance of cardiomyocytes and neurons is essential to maintain the normal physiological functions of heart and brain. If excessive cells die in tissues, serious Cardio-Cerebrovascular Diseases would occur, namely, hypertension, myocardial infarction, and ischemic stroke. The regulation of cell death plays a role in promoting or alleviating Cardio-Cerebrovascular Diseases. Ferroptosis is an iron-dependent new type of cell death that has been proved to occur in a variety of diseases. In our review, we focus on the critical role of ferroptosis and its regulatory mechanisms involved in Cardio-Cerebrovascular Diseases, and discuss the important function of ferroptosis-related inhibitors in order to propose potential implications for the prevention and treatment of Cardio-Cerebrovascular Diseases.

Cell death in pancreatic cancer: from pathogenesis to therapy

Pancreatic cancer is a devastating gastrointestinal cancer characterized by late diagnosis, limited treatment success and dismal prognosis. Exocrine tumours account for 95% of pancreatic cancers and the most common pathological type is pancreatic ductal adenocarcinoma (PDAC). The occurrence and progression of PDAC involve multiple factors, including internal genetic alterations and external inflammatory stimuli. The biology and therapeutic response of PDAC are further shaped by various forms of regulated cell death, such as apoptosis, necroptosis, ferroptosis, pyroptosis and alkaliptosis. Cell death induced by local or systemic treatments suppresses tumour proliferation, invasion and metastasis. However, unrestricted cell death or tissue damage might result in an inflammation-related immunosuppressive microenvironment, which is conducive to tumour progression or recurrence. The precise extent to which cell death affects PDAC is not yet well described. A growing body of preclinical and clinical studies document significant correlations between mutations (for example, in KRAS and TP53), stress responses (such as hypoxia and autophagy), metabolic reprogramming and chemotherapeutic responses. Here, we describe the molecular machinery of cell death, discuss the complexity and multifaceted nature of lethal signalling in PDAC cells, and highlight the challenges and opportunities for activating cell death pathways through precision oncology treatments.

The E3 Ligase MIB1 Promotes Proteasomal Degradation of NRF2 and Sensitizes Lung Cancer Cells to Ferroptosis

Dysregulation of Notch signaling has been implicated in cellular transformation and tumorigenesis in a variety of cancers while potential roles of MIB1, an E3 ubiquitin ligase required for efficient Notch activation, remains to be investigated. We analyzed MIB1 expression levels in tumor samples and performed gain-of-function and loss-of-function studies in cell lines to investigate potential roles of MIB1 in epithelial-to-mesenchymal transition (EMT), cell migration, and cell survival. We found that overexpression of MIB1 is detected in a subset of lung squamous carcinoma and adenocarcinoma samples and negative correlation is observed between MIB1 expression and overall patient survival. Ectopic expression of MIB1 in A549 cells induces EMT and stimulates cell migration via a Notch-dependent pathway. Meanwhile, MIB1 stimulates the degradation of nuclear factor erythroid 2-related factor 2 (NRF2) in a Notch-independent manner and disrupts the antioxidant capacity of cells, rendering them more sensitive to inducers of ferroptosis. On the other hand, MIB1 knockout induces accumulation of NRF2 and resistance to ferroptosis. Collectively, these results indicate that MIB1 may function as a positive regulator of ferroptosis through targeted degradation of the master antioxidant transcription factor NRF2. IMPLICATIONS: This study identifies a MIB1-induced proteasomal degradation pathway for NRF2 and reveals elevated ferroptosis sensitivity in MIB1-overexpressing cells which may provide novel insights into the treatment of MIB1-overexpressing cancers.

Toward improved human health: Nrf2 plays a critical role in regulating ferroptosis

Ferroptosis is a recently defined type of regulated cell death caused by an excess iron-dependent accumulation of lipid peroxides and is morphologically and biochemically distinct from other types of cell death. Notably, Nrf2 is identified to exquisitely modulate ferroptosis due to its ability to target a host of ferroptosis cascade genes, which places Nrf2 in the pivotal position of ferroptosis. This paper reviews the regulation effect of Nrf2 on ferroptosis, different activation mechanisms of Nrf2 as well as the relevance of the Nrf2-ferroptosis axis in diseases, and finally summarizes foods with beneficial effects in ferroptosis via the Nrf2 pathway and aims to serve as a reference for follow-up studies of food functions related to Nrf2, ferroptosis, and human health.

Melatonin protects against PM2.5-induced lung injury by inhibiting ferroptosis of lung epithelial cells in a Nrf2-dependent manner

PM2.5 refers to ambient air particulate matter with aerodynamic diameters ≤ 2.5 µm, which has been a global environmental problem threatening public health in recent years. Melatonin serving as one of the predominant hormones secreted by the pineal gland displays multiple pharmacological properties in various diseases. However, little is known about the possible effects of melatonin in the development of lung injury induced by PM2.5. This study was designed to explore the potential roles of melatonin as well as its possible mechanisms in PM2.5-induced lung injury. In the present study, mice were intratracheally instilled with PM2.5 dissolved in sterile water to induce lung injury with or without intragastric administration of melatonin. The results showed that melatonin treatment significantly alleviated lung pathological injury and edema, apart from inhibiting inflammatory cell infiltration. Meantime, melatonin also decreased the makers of ferroptosis and lipid peroxidation products in lung tissues challenged with PM2.5. Additionally, melatonin promoted the nuclear translocation and expression of Nrf2 and the protein degradation of Keap1. However, the pulmonary protection and anti-ferroptosis effect of melatonin were counteracted in Nrf2-deficiency mice. In vitro experiments further demonstrated that Nrf2 knockdown could offset anti-ferroptosis effect of melatonin in MLE-12 lung epithelial cells. Taken together, our study disclosed that melatonin could relieve PM2.5-induced lung injury via inhibiting ferroptosis of lung epithelial cells by activating Nrf2. Hence, melatonin may be a promising candidate against lung injury associated with air particulate matter.

Nrf2 Is a Potential Modulator for Orchestrating Iron Homeostasis and Redox Balance in Cancer Cells

Iron is an essential trace mineral element in almost all living cells and organisms. However, cellular iron metabolism pathways are disturbed in most cancer cell types. Cancer cells have a high demand of iron. To maintain rapid growth and proliferation, cancer cells absorb large amounts of iron by altering expression of iron metabolism related proteins. However, iron can catalyze the production of reactive oxygen species (ROS) through Fenton reaction. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is an important player in the resistance to oxidative damage by inducing the transcription of antioxidant genes. Aberrant activation of Nrf2 is observed in most cancer cell types. It has been revealed that the over-activation of Nrf2 promotes cell proliferation, suppresses cell apoptosis, enhances the self-renewal capability of cancer stem cells, and even increases the chemoresistance and radioresistance of cancer cells. Recently, several genes involving cellular iron homeostasis are identified under the control of Nrf2. Since cancer cells require amounts of iron and Nrf2 plays pivotal roles in oxidative defense and iron metabolism, it is highly probable that Nrf2 is a potential modulator orchestrating iron homeostasis and redox balance in cancer cells. In this hypothesis, we summarize the recent findings of the role of iron and Nrf2 in cancer cells and demonstrate how Nrf2 balances the oxidative stress induced by iron through regulating antioxidant enzymes and iron metabolism. This hypothesis provides new insights into the role of Nrf2 in cancer progression. Since ferroptosis is dependent on lipid peroxide and iron accumulation, Nrf2 inhibition may dramatically increase sensitivity to ferroptosis. The combination of Nrf2 inhibitors with ferroptosis inducers may exert greater efficacy on cancer therapy.

Ferroptosis Mechanisms Involved in Hippocampal-Related Diseases

Ferroptosis is a newly recognized type of cell death that is different from traditional forms of cell death, such as apoptosis, autophagy, and necrosis. It is caused by the accumulation of intracellular iron, promoting lipid peroxidation and leading to cell death. Iron is essential as a redox metal in several physiological functions. The brain is one of the organs known to be affected by iron homeostatic balance disruption. An increased concentration of iron in the central nervous system has been associated with oxidative stress, lipid peroxidation of proteins, and cell death. The hippocampus is an important brain region for learning, memory, and emotional responses, and is also a sensitive part of the brain to the dysfunctional homeostasis of transition metals. Damage of hippocampal structure and function are intimately involved in the pathogenic mechanisms underlying neurodegenerative diseases. Currently, ferroptosis is playing an increasingly important role in treatment areas of central nervous system diseases. Thus, we provide an overview of ferroptosis regulatory mechanisms, such as lipid metabolism, glutathione metabolism, and iron metabolism in this review. We also highlight the role of ferroptosis in hippocampal-related diseases and investigate a theoretical basis for further research on the role of ferroptosis in nervous system disease treatment.

A Ferrocene-Functionalized Covalent Organic Framework for Enhancing Chemodynamic Therapy via Redox Dyshomeostasis

Chemodynamic therapy (CDT), which induces cell death by decomposing high levels of H₂ O₂ in tumor cells into highly toxic ·OH, is recognized as a promising antineoplastic approach. However, current CDT approaches are often restricted by the highly controlled and upregulated cellular antioxidant defense. To enhance ·OH-induced cellular damage by CDT, a covalent organic framework (COF)-based, ferrocene (Fc)- and glutathione peroxidase 4 (GPX4) inhibitor-loaded nanodrug, RSL3@COF-Fc (2b), is fabricated. The obtained 2b not only promotes in situ Fenton-like reactions to trigger ·OH production in cells, but also attenuates the repair mechanisms under oxidative stress via irreversible covalent GPX4 inhibition. As a result, these two approaches synergistically result in massive lipid peroxide accumulation, subsequent cell damage, and ultimately ferroptosis, while not being limited by intracellular glutathione. It is believed that this research provides a paradigm for enhancing reactive oxygen species-mediated oncotherapy through redox dyshomeostasis and may provide new insights for developing COF-based nanomedicine.

Ginkgolide B protects against cognitive impairment in senescence-accelerated P8 mice by mitigating oxidative stress, inflammation and ferroptosis

Alzheimer's disease (AD) is a destructive neurodegenerative disease that currently has no effective treatment option available. Ginkgolide B (GB) is a terpene lactone derivative of Ginkgo biloba that possesses neuroprotective effects in various diseases. The aim of the present study was to investigate whether GB protects against cognitive impairment in AD by mitigating oxidative stress, inflammation and ferroptosis using senescence-accelerated P8 (SAMP8) mice. The results showed that GB improved the cognitive dysfunction of SAMP8 mice in the Morris water maze and novel object recognition test, which was associated with the attenuation of oxidative stress, inflammation and nuclear factor erythroid 2-related factor 2/glutathione peroxidase 4 (GPX4) pathway-mediated ferroptosis. Furthermore, Ras-selective lethal small molecule 3, a GPX4 inhibitor and ferroptosis inducer, compromised GB-induced cognitive performance in SAMP8 mice. These findings suggested that GB alleviated AD-induced cognitive defects by mitigating oxidative stress, neuroinflammation and ferroptosis, and that the inhibition of ferroptosis is required for GB to have beneficial effects in AD.

Newcastle-disease-virus-induced ferroptosis through nutrient deprivation and ferritinophagy in tumor cells

A number of new cell death processes have been discovered in recent years, including ferroptosis, which is characterized by the accumulation of lipid peroxidation products derived from iron metabolism. The evidence suggests that ferroptosis has a tumor-suppressor function. However, the mechanism by which ferroptosis mediates the response of tumor cells to oncolytic viruses remains poorly understood. The Newcastle disease virus (NDV) can selectively replicate in tumor cells. We show that NDV-induced ferroptosis acts through p53-SLC7A11-GPX4 pathway. Meanwhile, the levels of intracellular reactive oxygen species and lipid peroxides increased in tumor cells. Ferritinophagy was induced by NDV promotion of ferroptosis through the release of ferrous iron and an enhanced Fenton reaction. Collectively, these observations demonstrated that the NDV can kill tumor cells through ferroptosis. Our study provides novel insights into the mechanisms of NDV-induced ferroptosis and highlights the critical role of viruses in treating therapy-resistant cancers.

•

Oncolytic viruses NDV caused tumor cells death through ferroptosis

•

NDV-induced ferroptosis acts through nutrient deprivation by suppression of System Xc⁻

•

P53 activation is required for NDV-induced ferroptosis initiation

•

Ferritinophagy induced by NDV promotes ferroptosis through release of ferrous iron

Ferritinophagy and ferroptosis in cardiovascular disease: Mechanisms and potential applications

Ferroptosis is a type of regulated cell death driven by iron dependent accumulation of cellular reactive oxygen species (ROS) when glutathione (GSH)-dependent lipid peroxidation repair systems are compromised. Nuclear receptor co-activator 4 (NCOA4)-mediated selective autophagy of ferritin, termed ferritinophagy, involves the regulation of ferroptosis. Emerging evidence has revealed that ferritinophagy and ferroptosis exert a significant role in the occurrence and development of cardiovascular disease. In the present review, we aimed to present a brief overview of ferritinophagy and ferroptosis focusing on the underlying mechanism and regulations involved. We summarize and discuss relevant research progress on the role of ferritinophagy and ferroptosis in cardiovascular diseases accompanied with potential applications of ferritinophagy and ferroptosis modulators in the treatment of ferroptosis-associated cardiovascular diseases.

Ferroptosis in Different Pathological Contexts Seen through the Eyes of Mitochondria

Ferroptosis is a recently described form of regulated cell death characterized by intracellular iron accumulation and severe lipid peroxidation due to an impaired cysteine-glutathione-glutathione peroxidase 4 antioxidant defence axis. One of the hallmarks of ferroptosis is a specific morphological phenotype characterized by extensive ultrastructural changes of mitochondria. Increasing evidence suggests that mitochondria play a significant role in the induction and execution of ferroptosis. The present review summarizes existing knowledge about the mitochondrial impact on ferroptosis in different pathological states, primarily cancer, cardiovascular diseases, and neurodegenerative diseases. Additionally, we highlight pathologies in which the ferroptosis/mitochondria relation remains to be investigated, where the process of ferroptosis has been confirmed (such as liver- and kidney-related pathologies) and those in which ferroptosis has not been studied yet, such as diabetes. We will bring attention to avenues that could be followed in future research, based on the use of mitochondria-targeted approaches as anti- and proferroptotic strategies and directed to the improvement of existing and the development of novel therapeutic strategies.

Knowledge Domain and Emerging Trends in Ferroptosis Research: A Bibliometric and Knowledge-Map Analysis

Objectives

To identify the cooperation and impact of authors, countries, institutions, and journals, evaluate the knowledge base, find the hotspot trends, and detect the emerging topics regarding ferroptosis research.

Methods

The articles and reviews related to ferroptosis were obtained from the Web of Science Core Collection on November 1, 2020. Two scientometric software (CiteSpace 5.7 and VOSviewer 1.6.15) were used to perform bibliometric and knowledge-map analysis.

Results

A total of 1,267 papers were included, in 466 academic journals by 6,867 authors in 438 institutions from 61 countries/regions. The ferroptosis-related publications were increasing rapidly. Cell Death & Disease published the most papers on ferroptosis, while Cell was the top co-cited journal, publication journals and co-cited journals were major in the molecular and biology fields. The United States and China were the most productive countries; meanwhile, the University of Pittsburgh, Columbia University and Guangzhou Medical University were the most active institutions. Brent R Stockwell published the most papers, while Scott J Dixon had the most co-citations; simultaneously, active cooperation existed in ferroptosis researchers. Ten references on reviews, mechanisms, and diseases were regarded as the knowledge base. Five main aspects of ferroptosis research included regulation mechanisms, nervous system injury, cancer, relationships with other types of cell death, and lipid peroxidation. The latest hotspots were nanoparticle, cancer therapy, iron metabolism, and in-depth mechanism. Notably Nrf2 might have turning significance. The emerging topics on ferroptosis research were the further molecular mechanism of ferroptosis and the wider application of ferroptosis-related disease with advanced technology.

Conclusion

This study performed a full overview of the ferroptosis research using bibliometric and visual methods. The information would provide helpful references for scholars focusing on ferroptosis.

MGST1, a new soldier of NRF2 in the battle against ferroptotic death

In this issue of Cell Chemical Biology, Kuang et al. (2021) identify microsomal glutathione-S-transferase 1 (MGST1) as an NRF2 target gene that suppresses ferroptosis in pancreatic cancer cells. Mechanistically, MGST1 binds ALOX5 during ferroptosis induction, inhibiting lipid peroxide production. Thus, MGST1 could represent a viable therapeutic target for treating pancreatic cancer.