Fumarate hydratase inactivation in hereditary leiomyomatosis and renal cell cancer is synthetic lethal with ferroptosis induction

Ferroptosis in Renal Cancer Therapy: A Narrative Review of Drug Candidates

Renal cancer is a common and serious malignant tumor of the urinary system. While surgery effectively treats early-stage renal cancer, advanced cases pose a significant challenge due to poor treatment outcomes and chemotherapy resistance. Therefore, there is an urgent need to develop alternative therapeutic strategies. Ferroptosis is a newly defined form of programmed cell death characterized by the accumulation of iron-dependent lipid peroxides, which plays a critical role in tumor progression and drug resistance. Recent studies have shown that ferroptosis is involved in the occurrence and development of renal cancer, and ferroptosis-related genes can induce cell apoptosis and can be used as potential biomarkers for early diagnosis of renal cancer and participate in drug resistance of renal cancer chemotherapy. With the continuous improvement of the mechanism of ferroptosis, drugs targeting ferroptosis for the treatment of renal cancer are emerging in an endless stream. Based on the theoretical basis of the occurrence of ferroptosis, this paper reviewed drug-induced ferroptosis in renal cancer cells from the aspects of herbal medicine, natural compounds, drug resistance mechanisms, and nanomaterials, and delves into the clinical application potential of ferroptosis-related drugs in the treatment of renal cancer.

The role of glutathione peroxidase 4 in neuronal ferroptosis and its therapeutic potential in ischemic and hemorrhagic stroke

Ferroptosis is a type of cell death that depends on iron and is driven by lipid peroxidation, playing a crucial role in neuronal death during stroke. A central element in this process is the inactivation of glutathione peroxidase 4 (GPx4), an antioxidant enzyme that helps maintain redox balance by reducing lipid hydroperoxides. This review examines the critical function of GPx4 in controlling neuronal ferroptosis following ischemic and hemorrhagic stroke. We explore the mechanisms through which GPx4 becomes inactivated in various stroke subtypes. In strokes, excess glutamate depletes glutathione (GSH) and products of hemoglobin breakdown overwhelm GPx4. Studies using genetic models with GPx4 deficiency underscore its vital role in maintaining neuronal survival and function. We also consider new therapeutic approaches to enhance GPx4 activity, including novel small molecule activators, adjustments in GSH metabolism, and selenium supplementation. Additionally, we outline the potential benefits of combining these GPx4-focused strategies with other anti-ferroptotic methods like iron chelation and lipoxygenase inhibition for enhanced neuroprotection. Furthermore, we highlight the significance of understanding the timing of GPx4 inactivation during stroke progression to design effective therapeutic interventions.

Itaconate protects ferroptotic neurons by alkylating GPx4 post stroke

Neuronal ferroptosis plays a key role in neurologic deficits post intracerebral hemorrhage (ICH). However, the endogenous regulation of rescuing ferroptotic neurons is largely unexplored. Here, we analyzed the integrated alteration of metabolomic landscape after ICH using LC-MS and MALDI-TOF/TOF MS, and demonstrated that aconitate decarboxylase 1 (Irg1) and its product itaconate, a derivative of the tricarboxylic acid cycle, were protectively upregulated. Deficiency of Irg1 or depletion of neuronal Irg1 in striatal neurons was shown to exaggerate neuronal loss and behavioral dysfunction in an ICH mouse model using transgenic mice. Administration of 4-Octyl itaconate (4-OI), a cell-permeable itaconate derivative, and neuronal Irg1 overexpression protected neurons in vivo. In addition, itaconate inhibited ferroptosis in cortical neurons derived from mouse and human induced pluripotent stem cells in vitro. Mechanistically, we demonstrated that itaconate alkylated glutathione peroxidase 4 (GPx4) on its cysteine 66 and the modification allosterically enhanced GPx4's enzymatic activity by using a bioorthogonal probe, itaconate-alkyne (ITalk), and a GPx4 activity assay using phosphatidylcholine hydroperoxide. Altogether, our research suggested that Irg1/itaconate-GPx4 axis may be a future therapeutic strategy for protecting neurons from ferroptosis post ICH.

Recent progress of ferroptosis in cancers and drug discovery

Ferroptosis is a nonapoptotic form of cell death characterized by iron dependence and lipid peroxidation. Ferroptosis is involved in a range of pathological processes, such as cancer. Many studies have confirmed that ferroptosis plays an essential role in inhibiting cancer cell proliferation. In addition, a series of small-molecule compounds have been developed, including erastin, RSL3, and FIN56, which can be used as ferroptosis inducers. The combination of ferroptosis inducers with anticancer drugs can produce a significant synergistic effect in cancer treatment, and patients treated with these combinations exhibit a better prognosis than patients receiving traditional therapy. Therefore, a thorough understanding of the roles of ferroptosis in cancer is of great significance for the treatment of cancer. This review mainly elaborates the molecular biological characteristics and mechanism of ferroptosis, summarizes the function of ferroptosis in cancer development and treatment,illustrates the application of ferroptosis in patient's prognosis prediction and drug discovery, and discusses the prospects of targeting ferroptosis.

Ten "Cheat Codes" for Measuring Oxidative Stress in Humans

Formidable and often seemingly insurmountable conceptual, technical, and methodological challenges hamper the measurement of oxidative stress in humans. For instance, fraught and flawed methods, such as the thiobarbituric acid reactive substances assay kits for lipid peroxidation, rate-limit progress. To advance translational redox research, we present ten comprehensive "cheat codes" for measuring oxidative stress in humans. The cheat codes include analytical approaches to assess reactive oxygen species, antioxidants, oxidative damage, and redox regulation. They provide essential conceptual, technical, and methodological information inclusive of curated "do" and "don't" guidelines. Given the biochemical complexity of oxidative stress, we present a research question-grounded decision tree guide for selecting the most appropriate cheat code(s) to implement in a prospective human experiment. Worked examples demonstrate the benefits of the decision tree-based cheat code selection tool. The ten cheat codes define an invaluable resource for measuring oxidative stress in humans.

Ferroptosis: a promising target for fumarate hydratase-deficient tumor therapeutics literature review

Background and Objective

This review aims to investigate the ferroptosis mechanism of fumarate hydratase (FH)-related tumors for the purpose of possible treatment of tumors. Ferroptosis is an iron (Fe)-dependent form of regulated cell death caused by lipid peroxidation on the cell membrane. Studies have implicated FH in tumorigenesis. As mutations in the FH gene alter cellular metabolism and increase tumorigenesis risk, particularly in the kidneys. As most tumor cells require higher amounts of ferrous ions (Fe2+) than normal cells, they are more susceptible to ferroptosis. Recent studies have indicated that ferroptosis is inhibited the pathogenesis and progression of FH-deficient tumors by regulating lipid and iron metabolism, glutathione-glutathione peroxidase 4 (GSH-GPX4), nuclear factor-erythroid 2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) pathways. While the Fe2+ content is significantly lower in FH-deficient tumor cells, than that in normal cells. It is promising to promote ferroptosis by increasing the concentration of Fe2+ in cells to achieve the purpose of tumor treatment.

Methods

In this study, we searched for relevant articles on ferroptosis and FH-deficient tumors using PubMed database.

Key Content and Findings

FH is a tumor suppressor. A number of basic studies have shown that the loss of FH plays an important role in hereditary leiomyomas and tumors such as renal cell carcinoma, ovarian cancer, and other tumors. This type of tumor cells can through induce ferroptosis, inhibit proliferation, migration and invasion of tumor cells, increase the sensitivity of tumor cells to chemotherapy, and reverse the drug resistance through various molecular mechanisms. At present, the research on ferroptosis in FH-related tumors is still in the basic experimental stage.

Conclusions

This article reviews the anti-tumor effects and mechanisms of FH and ferroptosis, in order to further explore the medical value of ferroptosis in FH-related tumor therapy.

Dimethyl Fumarate Mediates Sustained Vascular Smooth Muscle Cell Remodeling in a Mouse Model of Cerebral Aneurysm

Cerebral aneurysms (CA) are a type of vascular disease that causes significant morbidity and mortality with rupture. Dysfunction of the vascular smooth muscle cells (VSMCs) from circle of Willis (CoW) vessels mediates CA formation, as they are the major cell type of the arterial wall and play a role in maintaining vessel integrity. Dimethyl fumarate (DMF), a first-line oral treatment for relapsing-remitting multiple sclerosis, has been shown to inhibit VSMC proliferation and reduce CA formation in a mouse model. Potential unwanted side effects of DMF on VSMC function have not been investigated yet. The present study characterizes the impact of DMF on VSMC using single-cell RNA-sequencing (scRNA-seq) in CoW vessels following CA induction and further explores its role in mitochondrial function using in vitro VSMC cultures. Two weeks of DMF treatment following CA induction impaired the transcription of the glutathione redox system and downregulated mitochondrial respiration genes in VSMCs. In vitro, DMF treatment increased lactate formation and enhanced the mitochondrial production of reactive oxygen species (ROS). These effects rendered VSMCs vulnerable to oxidative stress and led to mitochondrial dysfunction and enhancement of apoptosis. Taken together, our data support the concept that the DMF-mediated antiproliferative effect on VSMCs is linked to disturbed antioxidative functions resulting in altered mitochondrial metabolism. This negative impact of DMF treatment on VSMCs may be linked to preexisting alterations of cerebrovascular function due to renal hypertension. Therefore, before severe adverse effects emerge, it would be clinically relevant to develop indices or biomarkers linked to this disturbed antioxidative function to monitor patients undergoing DMF treatment.

The Role of Nrf2 in the Regulation of Mitochondrial Function and Ferroptosis in Pancreatic Cancer

The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) represents the master regulator of the cellular antioxidant response and plays a critical role in tumorigenesis. This includes a preventive effect of Nrf2 on cell death through ferroptosis, which represents an essential mechanism of therapy resistance in malignant tumors, such as pancreatic ductal adenocarcinoma (PDAC) as one of the most aggressive and still incurable tumors. Addressing this issue, we provide an overview on Nrf2 mediated antioxidant response with particular emphasis on its effect on mitochondria as the organelle responsible for the execution of ferroptosis. We further outline how deregulated Nrf2 adds to the progression and therapy resistance of PDAC, especially with respect to the role of ferroptosis in anti-cancer drug mediated cell killing and how this is impaired by Nrf2 as an essential mechanism of drug resistance. Our review further discusses recent approaches for Nrf2 inhibition by natural and synthetic compounds to overcome drug resistance based on enhanced ferroptosis. Finally, we provide an outlook on therapeutic strategies based on Nrf2 inhibition combined with ferroptosis inducing drugs.

A guide to ferroptosis in cancer

Ferroptosis is a newly identified iron-dependent type of regulated cell death that can also be regarded as death caused by the specific collapse of the lipid antioxidant defence machinery. Ferroptosis has gained increasing attention as a potential therapeutic strategy for therapy-resistant cancer types. However, many ferroptosis-inducing small molecules do not reach the pharmacokinetic requirements for their effective clinical use yet. Nevertheless, their clinical optimization is under development. In this review, we summarize the current understanding of molecular pathways regulating ferroptosis, how cells protect themselves from the induction of ferroptotic cell death, and how a better understanding of cancer cell metabolism can represent vulnerabilities for ferroptosis-based therapies. Lastly, we discuss the context-dependent effect of ferroptosis on various cell types within the tumor microenvironment and address controversies on how tissue ferroptosis might impact systemic cancer immunity in a paracrine manner.

Recent advancements in nanomaterial-mediated ferroptosis-induced cancer therapy: Importance of molecular dynamics and novel strategies

Ferroptosis is a novel type of controlled cell death resulting from an imbalance between oxidative harm and protective mechanisms, demonstrating significant potential in combating cancer. It differs from other forms of cell death, such as apoptosis and necrosis. Molecular therapeutics have hard time playing the long-acting role of ferroptosis induction due to their limited water solubility, low cell targeting capacity, and quick metabolism in vivo. To this end, small molecule inducers based on biological factors have long been used as strategy to induce cell death. Research into ferroptosis and advancements in nanotechnology have led to the discovery that nanomaterials are superior to biological medications in triggering ferroptosis. Nanomaterials derived from iron can enhance ferroptosis induction by directly releasing large quantities of iron and increasing cell ROS levels. Moreover, utilizing nanomaterials to promote programmed cell death minimizes the probability of unfavorable effects induced by mutations in cancer-associated genes such as RAS and TP53. Taken together, this review summarizes the molecular mechanisms involved in ferroptosis along with the classification of ferroptosis induction. It also emphasized the importance of cell organelles in the control of ferroptosis in cancer therapy. The nanomaterials that trigger ferroptosis are categorized and explained. Iron-based and noniron-based nanomaterials with their characterization at the molecular and cellular levels have been explored, which will be useful for inducing ferroptosis that leads to reduced tumor growth. Within this framework, we offer a synopsis, which traverses the well-established mechanism of ferroptosis and offers practical suggestions for the design and therapeutic use of nanomaterials.

GPX4, ferroptosis, and diseases

GPX4 (Glutathione peroxidase 4) serves as a crucial intracellular regulatory factor, participating in various physiological processes and playing a significant role in maintaining the redox homeostasis within the body. Ferroptosis, a form of iron-dependent non-apoptotic cell death, has gained considerable attention in recent years due to its involvement in multiple pathological processes. GPX4 is closely associated with ferroptosis and functions as the primary inhibitor of this process. Together, GPX4 and ferroptosis contribute to the pathophysiology of several diseases, including sepsis, nervous system diseases, ischemia reperfusion injury, cardiovascular diseases, and cancer. This review comprehensively explores the regulatory roles and impacts of GPX4 and ferroptosis in the development and progression of these diseases, with the aim of providing insights for identifying potential therapeutic strategies in the future.

Ferroptosis in liver cancer: a key role of post-translational modifications

Ferroptosis is an emerging form of regulated cell death in an oxidative stress- and iron-dependent manner, primarily induced by the over-production of reactive oxygen species (ROS). Manipulation of ferroptosis has been considered a promising therapeutic approach to inhibit liver tumor growth. Nevertheless, the development of resistance to ferroptosis in liver cancer poses a significant challenge in cancer treatment. Post-translational modifications (PTMs) are crucial enzymatic catalytic reactions that covalently regulate protein conformation, stability and cellular activities. Additionally, PTMs play pivotal roles in various biological processes and divergent programmed cell death, including ferroptosis. Importantly, key PTMs regulators involved in ferroptosis have been identified as potential targets for cancer therapy. PTMs function of two proteins, SLC7A11, GPX4 involved in ferroptosis resistance have been extensively investigated in recent years. This review will summarize the roles of PTMs in ferroptosis-related proteins in hepatocellular carcinoma (HCC) treatment.

Ferroptosis-Based Therapeutic Strategies toward Precision Medicine for Cancer

Ferroptosis is a type of iron-dependent programmed cell death characterized by the dysregulation of iron metabolism and the accumulation of lipid peroxides. This nonapoptotic mode of cell death is implicated in various physiological and pathological processes. Recent findings have underscored its potential as an innovative strategy for cancer treatment, particularly against recalcitrant malignancies that are resistant to conventional therapies. This article focuses on ferroptosis-based therapeutic strategies for precision cancer treatment, covering the molecular mechanisms of ferroptosis, four major types of ferroptosis inducers and their inhibitory effects on diverse carcinomas, the detection of ferroptosis by fluorescent probes, and their implementation in image-guided therapy. These state-of-the-art tactics have manifested enhanced selectivity and efficacy against malignant carcinomas. Given that the administration of ferroptosis in cancer therapy is still at a burgeoning stage, some major challenges and future perspectives are discussed for the clinical translation of ferroptosis into precision cancer treatment.

Glycyrrhizin attenuates myocardial ischemia reperfusion injury by suppressing Inflammation, oxidative stress, and ferroptosis via the HMGB1-TLR4-GPX4 pathway

Ferroptosis, a form of regulated cell death process, play an important role in myocardial ischemia‒reperfusion (I/R) injury. Glycyrrhizin (GL), a natural glycoconjugate triterpene, has the property to improve growth rate, immune regulation, antioxidant, anti-inflammatory. However, whether GL can attenuate myocardial I/R injury by modulating ferroptosis or other mechanisms are still unclear. In this study, SD rats underwent in vivo myocardial ischemia/reperfusion (I/R) surgery, while H9C2 cells were subjected to the hypoxia/reoxygenation (H/R) model for in vitro experiments. In addition, TAK-242, a TLR4-specific antagonist, and GL were also used to evaluate the effect and mechanisms of GL on the cardiac function and expression of ferroptosis-related gene and protein in vivo and vitro. The results show that GL decreased not only the expression of the inflammation-related factors (HMGB1, TNF-α, IL-6, IL-18 and IL-1β), but also reduced the number of TUNEL-positive cardiomyocytes, and mitigated pathological alterations in I/R injury. In addition, GL decreased the levels of MDA, promoted antioxidant capacity such as GSH, CAT, Cu/Zn-SOD, Mn-SOD, and SOD in vivo and vitro. More importantly, GL and TAK-242 regulate ferroptosis-related protein and gene expression in I/R and H/R model. Surprisingly, GL may ameliorate cardiomyocyte ferroptosis and ultimately improves cardiac function induced by H/R via the HMGB1-TLR4-GPX4 axis. Therefore, we have highlighted a novel mechanism by which GL regulates inflammation, oxidative stress, and ferroptosis via the HMGB1-TLR4-GPX4 pathway to prevent myocardial I/R injury. GL appears to be a potentially applicable drug for the treatment of myocardial I/R injury.

The Effect of Race/Ethnicity and MED12 Mutation on the Expression of Long Non-Coding RNAs in Uterine Leiomyoma and Myometrium

The objective of this study was to elucidate the expression of long non-coding RNA (lncRNA) in leiomyomas (Lyo) and paired myometrium (Myo) and explore the impact of race and MED12 mutation. Fold change analysis (Lyo/paired Myo) indicated the expression of 63 lncRNAs was significantly altered in the mutated group but not in the non-mutated Lyo. Additionally, 65 lncRNAs exhibited an over 1.5-fold change in the Black but not the White group. Fifteen differentially expressed lncRNAs identified with next-generation sequencing underwent qRT-PCR confirmation. Compared with Myo, the expression of TPTEP1, PART1, RPS10P7, MSC-AS1, SNHG12, CA3-AS1, LINC00337, LINC00536, LINC01436, LINC01449, LINC02433, and LINC02624 was significantly higher, while the expression of ZEB2-AS1, LINC00957, and LINC01186 was significantly lower. Comparison of normal Myo with diseased Myo showed significant differences in the expression of several lncRNAs. Analysis based on race and Lyo MED12 mutation status indicated a significantly higher expression of RPS10P7, SNHG12, LINC01449, LINC02433, and LINC02624 in Lyo from Black patients. The expression of TPTEP1, PART1, RPS10P7, MSC-AS1, LINC00337, LINC00536, LINC01436, LINC01449, LINC02433, and LINC02624 was higher, while LINC01186 was significantly lower in the MED12-mutated group. These results indicate that Lyo are characterized by aberrant lncRNA expression, which is further impacted by race and Lyo MED12 mutation status.

GPX4 in cell death, autophagy, and disease

Selenoprotein GPX4 (glutathione peroxidase 4), originally known as PHGPX (phospholipid hydroperoxide glutathione peroxidase), is the main oxidoreductase in the use of glutathione as a reducing agent in scavenging lipid peroxidation products. There are three GPX4 isoforms: cytosolic (cGPX4), mitochondrial (mGPX4), and nuclear (nGPX4), with distinct spatiotemporal expression patterns during embryonic development and adult life. In addition to inducing the main phenotype of ferroptosis, the loss of GPX4 can in some cells trigger apoptosis, necroptosis, pyroptosis, or parthanatos, which mediates or accelerates developmental defects, tissue damage, and sterile inflammation. The interaction of GPX4 with the autophagic degradation pathway further modulates cell fate in response to oxidative stress. Impaired GPX4 function is implicated in tumorigenesis, neurodegeneration, infertility, inflammation, immune disorders, and ischemia-reperfusion injury. Additionally, the R152H mutation in GPX4 can promote the development of Sedaghatian-type spinal metaphyseal dysplasia, a rare and fatal disease in newborns. Here, we discuss the roles of classical GPX4 functions as well as emerging GPX4-regulated processes in cell death, autophagy, and disease.Abbreviations: AA: arachidonic acid; cGPX4: cytosolic GPX4; CMA: chaperone-mediated autophagy; DAMPs: danger/damage-associated molecular patterns; mGPX4: mitochondrial GPX4; nGPX4: nuclear GPX4; GSDMD-N: N-terminal fragment of GSDMD; I/R: ischemia-reperfusion; PLOOH: phospholipid hydroperoxide; PUFAs: polyunsaturated fatty acids; RCD: regulated cell death; ROS: reactive oxygen species; Se: selenium; SSMD: Sedaghatian-type spondylometaphyseal dysplasia; UPS: ubiquitin-proteasome system.

Arginine Expedites Erastin-Induced Ferroptosis through Fumarate

Ferroptosis is a newly characterized form of programmed cell death. The fundamental biochemical feature of ferroptosis is the lethal accumulation of iron-catalyzed lipid peroxidation. It has gradually been recognized that ferroptosis is implicated in the pathogenesis of a variety of human diseases. Increasing evidence has shed light on ferroptosis regulation by amino acid metabolism. Herein, we report that arginine deprivation potently inhibits erastin-induced ferroptosis, but not RSL3-induced ferroptosis, in several types of mammalian cells. Arginine presence reduces the intracellular glutathione (GSH) level by sustaining the biosynthesis of fumarate, which functions as a reactive α,β-unsaturated electrophilic metabolite and covalently binds to GSH to generate succinicGSH. siRNA-mediated knockdown of argininosuccinate lyase, the critical urea cycle enzyme directly catalyzing the biosynthesis of fumarate, significantly decreases cellular fumarate and thus relieves erastin-induced ferroptosis in the presence of arginine. Furthermore, fumarate is decreased during erastin exposure, suggesting that a protective mechanism exists to decelerate GSH depletion in response to pro-ferroptotic insult. Collectively, this study reveals the ferroptosis regulation by the arginine metabolism and expands the biochemical functionalities of arginine.

Emerging significance and therapeutic targets of ferroptosis: a potential avenue for human kidney diseases

Kidney diseases remain one of the leading causes of human death and have placed a heavy burden on the medical system. Regulated cell death contributes to the pathology of a plethora of renal diseases. Recently, with in-depth studies into kidney diseases and cell death, a new iron-dependent cell death modality, known as ferroptosis, has been identified and has attracted considerable attention among researchers in the pathogenesis of kidney diseases and therapeutics to treat them. The majority of studies suggest that ferroptosis plays an important role in the pathologies of multiple kidney diseases, such as acute kidney injury (AKI), chronic kidney disease, and renal cell carcinoma. In this review, we summarize recently identified regulatory molecular mechanisms of ferroptosis, discuss ferroptosis pathways and mechanisms of action in various kidney diseases, and describe the protective effect of ferroptosis inhibitors against kidney diseases, especially AKI. By summarizing the prominent roles of ferroptosis in different kidney diseases and the progress made in studying ferroptosis, we provide new directions and strategies for future research on kidney diseases. In summary, ferroptotic factors are potential targets for therapeutic intervention to alleviate different kidney diseases, and targeting them may lead to new treatments for patients with kidney diseases.

Investigating Fumarate Hydratase-Deficient Uterine Fibroids: A Case Series

Uterine leiomyomas or uterine fibroids are the most common benign soft tissue tumor in reproductive-aged women. Fumarate hydratase deficient (FH-d) uterine fibroids are a rare subtype that is diagnosed only on pathologic evaluation. FH-d uterine fibroids may be the first indicator of hereditary leiomyomatosis and renal cell cancer (HLRCC) syndrome. Therefore, identifying and understanding the clinical implication and diagnosis of FH-d uterine fibroids is critical for early diagnosis of HLRCC. This case series investigates the uncommon yet significant condition of FH-d uterine fibroids. We examined the clinical manifestation, diagnostic imaging, and histopathological characteristics of FH-d uterine fibroids in five cases identified at our institution over the last ten years. All diagnoses were confirmed by pathologic evaluation after surgical treatment. Gynecologists and pathologists play a critical role in the early diagnosis of FH-d uterine fibroids and must recognize the relevant clinical and pathologic findings that raise suspicion about this diagnosis. The detection of these cases is largely dependent on the pathologist's ability to recognize unique histopathologic features. Once these characteristics are identified, it should prompt a referral to a gynecologist to consider conducting germline genetic testing. The management of FH-d uterine fibroids necessitates a multidisciplinary approach, including proper genetic screening and regular surveillance, especially for renal tumors.

The diversified role of mitochondria in ferroptosis in cancer

Ferroptosis is a form of regulated cell death induced by iron-dependent lipid peroxidation, and it has been studied extensively since its discovery in 2012. Induced by iron overload and ROS accumulation, ferroptosis is modulated by various cellular metabolic and signaling pathways. The GSH-GPX4 pathway, the FSP1-CoQ10 pathway, the GCH1-BH4 pathway, the DHODH-CoQH2 system and the sex hormones suppress ferroptosis. Mitochondrial iron metabolism regulates ferroptosis and mitochondria also undergo a morphological change during ferroptosis, these changes include increased membrane density and reduced mitochondrial cristae. Moreover, mitochondrial energy metabolism changes during ferroptosis, the increased oxidative phosphorylation and ATP production rates lead to a decrease in the glycolysis rate. In addition, excessive oxidative stress induces irreversible damage to mitochondria, diminishing organelle integrity. ROS production, mitochondrial membrane potential, mitochondrial fusion and fission, and mitophagy also function in ferroptosis. Notably, some ferroptosis inhibitors target mitochondria. Ferroptosis is a major mechanism for cell death associated with the progression of cancer. Metastasis-prone or metastatic cancer cells are more susceptible to ferroptosis. Inducing ferroptosis in tumor cells shows very promising potential for treating drug-resistant cancers. In this review, we present a brief retrospect of the discovery and the characteristics of ferroptosis, then we discuss the regulation of ferroptosis and highlight the unique role played by mitochondria in the ferroptosis of cancer cells. Furthermore, we explain how ferroptosis functions as a double-edged sword as well as novel therapies aimed at selectively manipulating cell death for cancer eradication.

Protein phosphatase 2A-B55β mediated mitochondrial p-GPX4 dephosphorylation promoted sorafenib-induced ferroptosis in hepatocellular carcinoma via regulating p53 retrograde signaling

Rationale: As a key endogenous negative regulator of ferroptosis, glutathione peroxidase 4 (GPX4) can regulate its antioxidant function through multiple post-translational modification pathways. However, the effects of the phosphorylation/dephosphorylation status of GPX4 on the regulation of inducible ferroptosis in hepatocellular carcinoma (HCC) remain unclear. Methods: To investigate the effects and molecular mechanism of GPX4 phosphorylation/dephosphorylation modification on ferroptosis in HCC cells. Sorafenib (Sora) was used to establish the ferroptosis model in HCC cells in vitro. Using the site-directed mutagenesis method, we generated the mimic GPX4 phosphorylation or dephosphorylation HCC cell lines at specific serine sites of GPX4. The effects of GPX4 phosphorylation/dephosphorylation modification on ferroptosis in HCC cells were examined. The interrelationships among GPX4, p53, and protein phosphatase 2A-B55β subunit (PP2A-B55β) were also explored. To explore the synergistic anti-tumor effects of PP2A activation on Sora-administered HCC, we established PP2A-B55β overexpression xenograft tumors in a nude mice model in vivo. Results: In the Sora-induced ferroptosis model of HCC in vitro, decreased levels of cytoplasmic and mitochondrial GPX4, mitochondrial dysfunction, and enhanced p53 retrograde signaling occurred under Sora treatment. Further, we found that mitochondrial p53 retrograded remarkably into the nucleus and aggravated Sora-induced ferroptosis. The phosphorylation status of GPX4 at the serine 2 site (GPX4Ser2) revealed that mitochondrial p-GPX4Ser2 dephosphorylation was positively associated with ferroptosis, and the mechanism might be related to mitochondrial p53 retrograding into the nucleus. In HCC cells overexpressing PP2A-B55β, it was found that PP2A-B55β directly interacted with mitochondrial GPX4 and promoted Sora-induced ferroptosis in HCC. Further, PP2A-B55β reduced the interaction between mitochondrial GPX4 and p53, leading to mitochondrial p53 retrograding into the nucleus. Moreover, it was confirmed that PP2A-B55β enhanced the ferroptosis-mediated tumor growth inhibition and mitochondrial p53 retrograde signaling in the Sora-treated HCC xenograft tumors. Conclusion: Our data uncovered that the PP2A-B55β/p-GPX4Ser2/p53 axis was a novel regulatory pathway of Sora-induced ferroptosis. Mitochondrial p-GPX4Ser2 dephosphorylation triggered ferroptosis via inducing mitochondrial p53 retrograding into the nucleus, and PP2A-B55β was an upstream signal modulator responsible for mitochondrial p-GPX4Ser2 dephosphorylation. Our findings might serve as a potential theranostic strategy to enhance the efficacy of Sora in HCC treatment through the targeted intervention of p-GPX4 dephosphorylation via PP2A-B55β activation.

Broadening horizons: the multifaceted functions of ferroptosis in kidney diseases

Ferroptosis is an iron-dependent programmed cell death pattern that is characterized by iron overload, reactive oxygen species (ROS) accumulation and lipid peroxidation. Growing viewpoints support that the imbalance of iron homeostasis and the disturbance of lipid metabolism contribute to tissue or organ injury in various kidney diseases by triggering ferroptosis. At present, the key regulators and complicated network mechanisms associated with ferroptosis have been deeply studied; however, its role in the initiation and progression of kidney diseases has not been fully revealed. Herein, we aim to discuss the features, key regulators and complicated network mechanisms associated with ferroptosis, explore the emerging roles of organelles in ferroptosis, gather its pharmacological progress, and systematically summarize the most recent discoveries about the crosstalk between ferroptosis and kidney diseases, including renal cell carcinoma (RCC), acute kidney injury (AKI), diabetic kidney disease (DKD), autosomal dominant polycystic kidney disease (ADPKD), renal fibrosis, lupus nephritis (LN) and IgA nephropathy. We further conclude the potential therapeutic strategies by targeting ferroptosis for the prevention and treatment of kidney diseases and hope that this work will provide insight for the further study of ferroptosis in the pathogenesis of kidney-related diseases.

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

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

Ferroptosis-mediated immune responses in cancer

Cell death is a universal biological process in almost every physiological and pathological condition, including development, degeneration, inflammation, and cancer. In addition to apoptosis, increasing numbers of cell death types have been discovered in recent years. The biological significance of cell death has long been a subject of interest and exploration and meaningful discoveries continue to be made. Ferroptosis is a newfound form of programmed cell death and has been implicated intensively in various pathological conditions and cancer therapy. A few studies show that ferroptosis has the direct capacity to kill cancer cells and has a potential antitumor effect. As the rising role of immune cells function in the tumor microenvironment (TME), ferroptosis may have additional impact on the immune cells, though this remains unclear. In this study we focus on the ferroptosis molecular network and the ferroptosis-mediated immune response, mainly in the TME, and put forward novel insights and directions for cancer research in the near future.

Metronomic capecitabine inhibits liver transplant rejection in rats by triggering recipients’ T cell ferroptosis

BACKGROUND

Capecitabine (CAP) is a classic antimetabolic drug and has shown potential antirejection effects after liver transplantation (LT) in clinical studies. Our previous study showed that metronomic CAP can cause the programmed death of T cells by inducing oxidative stress in healthy mice. Ferroptosis, a newly defined non-apoptotic cell death that occurs in response to iron overload and lethal levels of lipid peroxidation, is an important mechanism by which CAP induces cell death. Therefore, ferroptosis may also play an important role in CAP-induced T cell death and play an immunosuppressive role in acute rejection after trans-plantation.

AIM

To investigate the functions and underlying mechanisms of antirejection effects of metronomic CAP.

METHODS

A rat LT model of acute rejection was established, and the effect of metronomic CAP on splenic hematopoietic function and acute graft rejection was evaluated 7 d after LT. In vitro, primary CD3⁺ T cells were sorted from rat spleens and human peripheral blood, and co-cultured with or without 5-fluorouracil (5-FU) (active agent of CAP). The levels of ferroptosis-related proteins, ferrous ion concentration, and oxidative stress-related indicators were observed. The changes in mito-chondrial structure were observed using electron microscopy.

RESULTS

With no significant myelotoxicity, metronomic CAP alleviated graft injury (Banff score 9 vs 7.333, P < 0.001), prolonged the survival time of the recipient rats (11.5 d vs 16 d, P < 0.01), and reduced the infiltration rate of CD3⁺ T cells in peripheral blood (6.859 vs 3.735, P < 0.001), liver graft (7.459 vs 3.432, P < 0.001), and spleen (26.92 vs 12.9, P < 0.001), thereby inhibiting acute rejection after LT. In vitro, 5-FU, an end product of CAP metabolism, induced the degradation of the ferritin heavy chain by upregulating nuclear receptor coactivator 4, which caused the accumulation of ferrous ions. It also inhibited nuclear erythroid 2 p45-related factor 2, heme oxygenase-1, and glutathione peroxidase 4, eventually leading to oxidative damage and ferroptosis of T cells.

CONCLUSION

Metronomic CAP can suppress acute allograft rejection in rats by triggering CD3⁺ T cell ferroptosis, which makes it an effective immunosuppressive agent after LT.

Novel Insight into Ferroptosis in Kidney Diseases

BACKGROUND

Various kidney diseases such as acute kidney injury, chronic kidney disease, polycystic kidney disease, renal cancer, and kidney stones, are an important part of the global burden, bringing a huge economic burden to people around the world. Ferroptosis is a type of nonapoptotic iron-dependent cell death caused by the excess of iron-dependent lipid peroxides and accompanied by abnormal iron metabolism and oxidative stress. Over the past few decades, several studies have shown that ferroptosis is associated with many types of kidney diseases. Studying the mechanism of ferroptosis and related agonists and inhibitors may provide new ideas and directions for the treatment of various kidney diseases.

SUMMARY

In this review, we discuss the differences between ferroptosis and other types of cell death such as apoptosis, necroptosis, pyroptosis, cuprotosis, pathophysiological features of the kidney, and ferroptosis-induced kidney injury. We also provide an overview of the molecular mechanisms involved in ferroptosis and events that lead to ferroptosis. Furthermore, we summarize the possible clinical applications of this mechanism among various kidney diseases.

KEY MESSAGE

The current research suggests that future therapeutic efforts to treat kidney ailments would benefit from a focus on ferroptosis.

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

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

Butyrate dictates ferroptosis sensitivity through FFAR2-mTOR signaling

Evidence shows that short-chain fatty acids (SCFAs) play an important role in health maintenance and disease development. In particular, butyrate is known to induce apoptosis and autophagy. However, it remains largely unclear whether butyrate can regulate cell ferroptosis, and the mechanism by which has not been studied. In this study, we found that RAS-selective lethal compound 3 (RSL3)- and erastin-induced cell ferroptosis were enhanced by sodium butyrate (NaB). With regard to the underlying mechanism, our results showed that NaB promoted ferroptosis by inducing lipid ROS production via downregulating the expression of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4). Moreover, the FFAR2-AKT-NRF2 axis and FFAR2-mTORC1 axis accounts for the NaB-mediated downregulation of SLC7A11 and GPX4, respectively, in a cAMP-PKA-dependent manner. Functionally, we found that NaB can inhibit tumor growth and the inhibitory effect could be eliminated by administrating MHY1485 (mTORC1 activator) and Ferr-1 (ferroptosis inhibitor). Altogether, in vivo results suggest that NaB treatment is correlated to the mTOR-dependent ferroptosis and consequent tumor growth through xenografts and colitis-associated colorectal tumorigenesis, implicating the potential clinical applications of NaB for future colorectal cancer treatments. Based on all these findings, we have proposed a regulatory mechanism via which butyrate inhibits the mTOR pathway to control ferroptosis and consequent tumorigenesis.

Targeting GPX4 in human cancer: Implications of ferroptosis induction for tackling cancer resilience

Cancer metabolic alterations have been emphasized to protect cancer cells from cell death. The metabolic reprogramming toward a mesenchymal state makes cancer cells resistant to therapy but vulnerable to ferroptosis induction. Ferroptosis is a new form of regulated cell death based on the iron-dependent accumulation of excessive lipid peroxidation. Glutathione peroxidase 4 (GPX4) is the core regulator of ferroptosis by detoxifying cellular lipid peroxidation using glutathione as a cofactor. GPX4 synthesis requires selenium incorporation into the selenoprotein through isopentenylation and selenocysteine tRNA maturation. GPX4 synthesis and expression can be regulated by multiple levels of its transcription, translation, posttranslational modifications, and epigenetic modifications. Targeting GPX4 in cancer may be a promising strategy for effectively inducing ferroptosis and killing therapy-resistant cancer. Several pharmacological therapeutics targeting GPX4 have been developed constantly to activate ferroptosis induction in cancer. The potential therapeutic index of GPX4 inhibitors remains to be tested with thorough examinations of their safety and adverse effects in vivo and clinical trials. Many papers have been published continuously in recent years, requiring state-of-the-art updates in targeting GPX4 in cancer. Herein, we summarize targeting the GPX4 pathway in human cancer, which leads to implications of ferroptosis induction for tackling cancer resilience.

Inaugurating a novel adjuvant therapy in urological cancers: Ferroptosis

Ferroptosis, a distinctive form of programmed cell death, is involved in numerous diseases with specific characteristics, including certain cell morphology, functions, biochemistry, and genetics, that differ from other forms of programmed cell death, such as apoptosis. Many studies have explored ferroptosis and its associated mechanisms, drugs, and clinical applications in diseases such as kidney injury, stroke, ischemia-reperfusion injury, and prostate cancer. In this review, we summarize the regulatory mechanisms of some ferroptosis inducers, such as enzalutamide and erastin. These are current research focuses and have already been studied extensively. In summary, this review focuses on the use of ferroptosis induction as a therapeutic strategy for treating tumors of the urinary system.

Propofol Inhibits Ferroptotic Cell Death Through the Nrf2/Gpx4 Signaling Pathway in the Mouse Model of Cerebral Ischemia-Reperfusion Injury

Ferroptosis is characterized by excessive accumulation of iron and lipid peroxides, which are involved in ischemia, reperfusion-induced organ injury, and stroke. Propofol, an anesthetic agent, has neuroprotective effects due to its potent antioxidant, anti-ischemic, and anti-inflammatory properties. However, the relationship between propofol and ferroptosis is still unclear. In the current study, we elucidated the role of ferroptosis in the neuroprotective effect of propofol in mouse brains subjected to cerebral ischemia reperfusion injury (CIRI). Ferroptosis was confirmed by Western blotting assays, transmission electron microscopy, and glutathione assays. Propofol regulated Nrf2/Gpx4 signaling, enhanced antioxidant potential, inhibited the accumulation of lipid peroxides in CIRI-affected neurons, and significantly reversed CIRI-induced ferroptosis. Additionally, Gpx4 inhibitor RSL3 and Nrf2 inhibitor ML385 attenuated the effects of propofol on antioxidant capacity, lipid peroxidation, and ferroptosis in CIRI-affected neurons. Our data support a protective role of propofol against ferroptosis as a cause of cell death in mice with CIRI. Propofol protected against CIRI-induced ferroptosis partly by regulating the Nrf2/Gpx4 signaling pathway. These findings may contribute to the development of future therapies targeting ferroptosis induced by CIRI.

GPX4: The hub of lipid oxidation, ferroptosis, disease and treatment

Glutathione peroxidase 4 (GPx4) moonlights as structural protein and antioxidase that powerfully inhibits lipid oxidation. In the past years, it is considered as a key regulator of ferroptosis, which takes role in the lipid and amine acid metabolism and influences the cell aging, oncogenesis, and cell death. More and more evidences show that targeting GPX4-induced ferroptosis is a promising strategy for disease therapy, especially cancer treatment. In view of these, we generalize the function of GPX4 and regulatory mechanism between GPX4 and ferroptosis, discuss its roles in the disease pathology, and focus on the recent advances of disease therapeutic potential.

Tiliroside targets TBK1 to induce ferroptosis and sensitize hepatocellular carcinoma to sorafenib

BACKGROUND

Combination therapy with other antineoplastic agent is a favorable approach for targeting the molecules involved in sorafenib resistance.

PURPOSE

In the present study, we determined whether tiliroside, a natural flavonoid glycoside isolated from oriental paperbush flower, could improve the sensitivity of hepatocellular carcinoma (HCC) cells to sorafenib. Furthermore, we investigated the mechanisms and identified the potential drug targets of tiliroside.

METHODS

Synergy was performed using CalcuSyn. Transcriptomic studies were adopted to investigate whether tiliroside could induce ferroptosis and inhibit the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in HCC cells. Ferroptosis was analyzed using western blotting, flow cytometry, and transmission electron microscopy. Immunofluorescence, co-immunoprecipitation, and Nrf2 knockdown or overexpression were performed to confirm the involvement of Nrf2 in tiliroside-induced ferroptosis. Additionally, molecular docking and biolayer interferometry-based measurements were used to confirm the direct target of tiliroside. Finally, subcutaneous xenograft and orthotopic xenograft tumors in nude mice were used to assess the effects of tiliroside in vivo.

RESULTS

Tiliroside significantly enhanced the anti-HCC activity of sorafenib without any discernible side effects. Moreover, the combination of tiliroside and sorafenib induced synergistic effects against HCC in vitro. The inhibitory effects of tiliroside on HCC were antagonized by N-acetylcysteine and the ferroptosis inhibitor liproxstatin-1. Studies on the mechanism of action revealed that tiliroside could directly bind to TANK-binding kinase 1 (TBK1) and inhibit its enzymatic activity. Inhibition of TBK1 by tiliroside decreased the phosphorylation of serine 349 on sequestosome-1 (p62) and the affinity of p62 for kelch like ECH-associated protein 1 (Keap1) and promoted Keap1-mediated Nrf2 ubiquitination and degradation. The downstream target proteins of Nrf2, including glutathione peroxidase 4, ferritin heavy chain 1, and glucose-6-phosphate dehydrogenase, demonstrated similar results to that of Nrf2 protein, inducing ferroptosis in tiliroside-treated HCC cells. We extended these findings in vivo and found that tiliroside inhibited the growth of HepG2 tumors in both subcutaneous xenograft and orthotopic xenograft tumor models of HCC.

CONCLUSION

Our findings imply that tiliroside is a potent TBK1 inhibitor and a candidate natural anti-cancer product that could function as a sensitizer of sorafenib in HCC treatment by targeting TBK1 to induce ferroptosis.

Ferroptosis: Mechanism and connections with cutaneous diseases

Ferroptosis is a recognized novel form of programmed cell death pathway, featuring abnormalities in iron metabolism, SystemXc^-/glutathione axis, and lipid peroxidation regulation. A variety of ferroptosis inducers can influence glutathione peroxidase directly or indirectly via diverse pathways, leading to decreased antioxidant capacity, accumulated cellular lipid peroxides, and finally inducing ferroptosis. To date, mounting studies confirm the association of ferroptosis with various cutaneous diseases, including skin homeostasis, neoplastic diseases, infectious diseases, genetic skin disease, inflammatory skin diseases, and autoimmune diseases. There are shared characteristics regarding ferroptosis and various cutaneous diseases in terms of pathophysiological mechanisms, such as oxidative stress associated with iron metabolism disorder and accumulated lipid peroxides. Therefore, we summarize the current knowledge regarding the mechanisms involved in the regulation of ferroptosis for further discussion of its role in the pathogenesis and prognosis of skin diseases. Gaining insight into the underlying mechanisms of ferroptosis and the associated dermatological disorders could illuminate the pathogenesis and treatments of different cutaneous diseases.

Targeting Mitochondrial Metabolism to Reverse Radioresistance: An Alternative to Glucose Metabolism

Radiotherapy failure and poor tumor prognosis are primarily attributed to radioresistance. Improving the curative effect of radiotherapy and delaying cancer progression have become difficult problems for clinicians. Glucose metabolism has long been regarded as the main metabolic process by which tumor cells meet their bioenergetic and anabolic needs, with the complex interactions between the mitochondria and tumors being ignored. This misconception was not dispelled until the early 2000s; however, the cellular molecules and signaling pathways involved in radioresistance remain incompletely defined. In addition to being a key metabolic site that regulates tumorigenesis, mitochondria can influence the radiation effects of malignancies by controlling redox reactions, participating in oxidative phosphorylation, producing oncometabolites, and triggering apoptosis. Therefore, the mitochondria are promising targets for the development of novel anticancer drugs. In this review, we summarize the internal relationship and related mechanisms between mitochondrial metabolism and cancer radioresistance, thus exploring the possibility of targeting mitochondrial signaling pathways to reverse radiation insensitivity. We suggest that attention should be paid to the potential value of mitochondria in prolonging the survival of cancer patients.

System Xc−/GSH/GPX4 axis: An important antioxidant system for the ferroptosis in drug-resistant solid tumor therapy

The activation of ferroptosis is a new effective way to treat drug-resistant solid tumors. Ferroptosis is an iron-mediated form of cell death caused by the accumulation of lipid peroxides. The intracellular imbalance between oxidant and antioxidant due to the abnormal expression of multiple redox active enzymes will promote the produce of reactive oxygen species (ROS). So far, a few pathways and regulators have been discovered to regulate ferroptosis. In particular, the cystine/glutamate antiporter (System Xc−), glutathione peroxidase 4 (GPX4) and glutathione (GSH) (System Xc−/GSH/GPX4 axis) plays a key role in preventing lipid peroxidation-mediated ferroptosis, because of which could be inhibited by blocking System Xc−/GSH/GPX4 axis. This review aims to present the current understanding of the mechanism of ferroptosis based on the System Xc−/GSH/GPX4 axis in the treatment of drug-resistant solid tumors.

GPX4 suppresses ferroptosis to promote malignant progression of endometrial carcinoma via transcriptional activation by ELK1

Background

Glutathione Peroxidase 4 (GPX4) is a key protein that inhibits ferroptosis. However, its biological regulation and mechanism in endometrial cancer (EC) have not been reported in detail.

Methods

The expression of GPX4 in EC tissues was determined by TCGA databases, qRT-PCR, Western blot, and immunohistochemistry (IHC). The effects of GPX4 on EC cell proliferation, migration, apoptosis, and tumorigenesis were studied in vivo and in vitro. In addition, ETS Transcription Factor ELK1 (ELK1) was identified by bioinformatics methods, dual-luciferase reporter assay, and chromatin immunoprecipitation (ChIP). Pearson correlation analysis was used to evaluate the association between ELK1 and GPX4 expression.

Results

The expression of GPX4 was significantly up-regulated in EC tissues and cell lines. Silencing GPX4 significantly inhibited the proliferation, migration ability, induced apoptosis, and arrested the cell cycle of Ishikawa and KLE cells. Knockdown of GPX4 accumulated intracellular ferrous iron and ROS, disrupted MMP, and increased MDA levels. The xenograft tumor model also showed that GPX4 knockdown markedly reduced tumor growth in mice. Mechanically, ELK1 could bind to the promoter of GPX4 to promote its transcription. In addition, the expression of ELK1 in EC was positively correlated with GPX4. Rescue experiments confirmed that GPX4 knockdown could reverse the strengthens of cell proliferation and migration ability and the lower level of Fe²⁺ and MDA caused by upregulating ELK1.

Conclusion

The results of the present study suggest that ELK1 / GPX4 axis plays an important role in the progress of EC by promoting the malignant biological behavior and inducing ferroptosis of EC cells, which provides evidence for investigating the potential therapeutic strategies of endometrial cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09986-3.

The Mechanisms of Ferroptosis and the Applications in Tumor Treatment: Enemies or Friends?

Ferroptosis, as a newly discovered non-apoptotic cell death mode, is beginning to be explored in different cancer. The particularity of ferroptosis lies in the accumulation of iron dependence and lipid peroxides, and it is different from the classical cell death modes such as apoptosis and necrosis in terms of action mode, biochemical characteristics, and genetics. The mechanism of ferroptosis can be divided into many different pathways, so it is particularly important to identify the key sites of ferroptosis in the disease. Herein, based on ferroptosis, we analyze the main pathways in detail. More importantly, ferroptosis is linked to the development of different systems of the tumor, providing personalized plans for the examination, treatment, and prognosis of cancer patients. Although some mechanisms and side effects of ferroptosis still need to be studied, it is still a promising method for cancer treatment.

Identification of immunity- and ferroptosis-related genes for predicting the prognosis of serous ovarian cancer

BACKGROUND

Serous ovarian cancer (SOC) is the most common type of ovarian cancer (OC), with bad outcomes. To improve the prognosis of SOC patients, a novel risk signature was developed by combining immunity- and ferroptosis-related genes.

METHODS

By means of comparing SOC tissues with normal tissues, we screened the differential expression of immunity-related genes (DE-IRGs) and ferroptosis-related genes(DE-FRGs) with the standards of |log₂fold change| > 1 and false discovery rate (FDR) < 0.05. After obtaining the meaningful differentially expressed genes from immune and ferroptosis (DEGs), we established a prognostic risk signature by utilizing Cox regression analyses in TCGA training set, which was validated in TCGA testing set and GSE26712 dataset. Besides, the differential expression of immune-related markers, immunophenoscore (IPS), TIDE score,T cell dysfunction score and T cell exclusion score were also analyzed. We further verified the expression of target genes in ovarian tumor cells lines by QRT-PCR.

RESULTS

A risk signature constructed by totally four immunity- and ferroptosis-related DEGs (CXCL11, CX3CR1, FH, and DNAJB6) was developed, which distinguished the SOC patients as high-risk and low-risk groups. Patients in the high-risk group showed a lower overall survival (OS) than those in the low-risk group. Furthermore, the risk score was independent when analyzed with clinical augments, which was significantly associated with 13 KEGG signaling pathways. The gene signature showed favorable predictive performance according to Receiver operating characteristic (ROC) curves. Notably, the expression of immune-related markers or IPS indicated a negative connection with the risk score. SOC patients had a lower score of TIDE and T cell dysfunction than Whom had a higher score. Nonetheless, there were no significant differences in T cell exclusion scores between the two groups.Compared with normal ovarian cell line IOSE-80,QRT-PCR experiments exhibited that CXCL11, CX3CR1and FH were up-regulated in ovarian tumor cells lines(SK-OV-3,COC1,A2780),while DNAJB6 was down-regulated.

CONCLUSION

Four-biomarker signature formed by immunity- and ferroptosis-related genes may be clinically used as risk stratifcation tool in serous ovarian cancer,which can help further clinical decision-making regarding prognostic prediction,individualized treatment and follow-up scheduling.

Solasonine Causes Redox Imbalance and Mitochondrial Oxidative Stress of Ferroptosis in Lung Adenocarcinoma

Ferroptosis, a type of iron-dependent oxidative cell death caused by excessive lipid peroxidation, is emerging as a promising cancer therapeutic strategy. Solasonine has been reported as a potential compound in tumor suppression, which is closely linked to ferroptosis. However, ferroptosis caused by solasonine is insufficiently identified and elaborated in lung adenocarcinoma, a fatal disease with high morbidity and mortality rates. First, the biochemical and morphological changes in Calu-1 and A549 cells exposed to solasonine are observed using a cell death assay and a microscope. The cell viability assay is performed after determining the executive concentration of solasonine to assess the effects of solasonine on tumor growth in Calu-1 and A549 cells. The ferroptosis is then identified by using ferroptosis-related reagents on CCK-8, lipid peroxidation assessment, Fe²⁺, and ROS detection. Furthermore, the antioxidant system, which includes GSH, Cys, GPx4, SLC7A11, and mitochondrial function, is measured to identify the potential pathways. According to the results, solasonine precisely exerts antitumor ability in lung adenocarcinoma cells. Ferroptosis is involved in the solasonine-induced cell death, as well as the accumulation of lipid peroxide, Fe²⁺, and ROS. Moreover, the failures of antioxidant defense and mitochondrial damage are considered to make a significant contribution to the occurrence of ferroptosis caused by solasonine. The study describes the potential process of ferroptosis caused by solasonine when dealing with lung adenocarcinoma. This encouraging evidence suggests that solasonine may be useful in the treatment of lung cancer.

Post-Translational Modification of GPX4 is a Promising Target for Treating Ferroptosis-Related Diseases

Glutathione peroxidase 4 (GPX4) is one of the most important antioxidant enzymes. As the key regulator of ferroptosis, GPX4 has attracted considerable attention in the fields of cancer, cardiovascular, and neuroscience research in the past 10 years. How to regulate GPX4 activity has become a hot topic nowadays. GPX4 protein level is regulated transcriptionally by transcription factor SP2 or Nrf2. GPX4 activity can be upregulated by supplementing intracellular selenium or glutathione, and also be inhibited by ferroptosis inducers such as ML162 and RSL3. These regulatory mechanisms of GPX4 level/activity have already shown a great potential for treating ferroptosis-related diseases in preclinical studies, especially in cancer cells. Until recently, research show that GPX4 can undergo post-translational modifications (PTMs), such as ubiquitination, succination, phosphorylation, and glycosylation. PTMs of GPX4 affect the protein level/activity of GPX4, indicating that modifying these processes can be a potential therapy for treating ferroptosis-related diseases. This article summarizes the protein characteristics, enzyme properties, and PTMs of GPX4. It also provides a hypothetical idea for treating ferroptosis-related diseases by targeting the PTMs of GPX4.

Therapeutic implications of germline vulnerabilities in DNA repair for precision oncology

DNA repair vulnerabilities are present in a significant proportion of cancers. Specifically, germline alterations in DNA repair not only increase cancer risk but are associated with treatment response and clinical outcomes. The therapeutic landscape of cancer has rapidly evolved with the FDA approval of therapies that specifically target DNA repair vulnerabilities. The clinical success of synthetic lethality between BRCA deficiency and poly(ADP-ribose) polymerase (PARP) inhibition has been truly revolutionary. Defective mismatch repair has been validated as a predictor of response to immune checkpoint blockade associated with durable responses and long-term benefit in many cancer patients. Advances in next generation sequencing technologies and their decreasing cost have supported increased genetic profiling of tumors coupled with germline testing of cancer risk genes in patients. The clinical adoption of panel testing for germline assessment in high-risk individuals has generated a plethora of genetic data, particularly on DNA repair genes. Here, we highlight the therapeutic relevance of germline aberrations in DNA repair to identify patients eligible for precision treatments such as PARP inhibitors (PARPis), immune checkpoint blockade, chemotherapy, radiation therapy and combined treatment. We also discuss emerging mechanisms that regulate DNA repair.

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.

Cyst(e)inase-Rapamycin combination induces ferroptosis in both in vitro and in vivo models of hereditary leiomyomatosis and renal cell cancer

Renal cell carcinomas associated with hereditary leiomyomatosis and renal cell cancer (HLRCC) are notoriously aggressive and represent the leading cause of death among HLRCC patients. To date, a safe and effective standardized therapy for this tumor type is lacking. Here we show that the engineered synthetic therapeutic enzyme, Cyst(e)inase, when combined with rapamycin, can effectively induce ferroptosis in HLRCC cells in vivo. The drug combination promotes lipid peroxidation to a greater degree than cysteine deprivation or Cyst(e)inase treatment alone, while rapamycin treatment alone does not induce ferroptosis. Mechanistically, Cyst(e)inase induces ferroptosis by depleting the exogenous cysteine/cystine supply, while rapamycin reduces cellular ferritin level by promoting ferritins' destruction via ferritinophagy. Since both Cyst(e)inase and rapamycin are well-tolerated clinically, the combination represents an opportunity to exploit ferroptosis induction as a cancer management strategy. Accordingly, using a xenograft mouse model, we showed that the combination treatment resulted in tumor growth suppression without any notable side effects. In contrast, both Cyst(e)inase only and rapamycin only treatment groups failed to induce a significant change when compared to the vehicle control group. Our results demonstrated the effectiveness of Cyst(e)inase-rapamycin combination in inducing ferroptotic cell death in vivo, supporting the potential translation of the combination therapy into clinical HLRCC management.

Abnormal Iron and Lipid Metabolism Mediated Ferroptosis in Kidney Diseases and Its Therapeutic Potential

Ferroptosis is a newly identified form of regulated cell death driven by iron-dependent phospholipid peroxidation and oxidative stress. Ferroptosis has distinct biological and morphology characteristics, such as shrunken mitochondria when compared to other known regulated cell deaths. The regulation of ferroptosis includes different molecular mechanisms and multiple cellular metabolic pathways, including glutathione/glutathione peroxidase 4(GPX4) signaling pathways, which are involved in the amino acid metabolism and the activation of GPX4; iron metabolic signaling pathways, which are involved in the regulation of iron import/export and the storage/release of intracellular iron through iron-regulatory proteins (IRPs), and lipid metabolic signaling pathways, which are involved in the metabolism of unsaturated fatty acids in cell membranes. Ferroptosis plays an essential role in the pathology of various kidneys diseases, including acute kidney injury (AKI), chronic kidney disease (CKD), autosomal dominant polycystic kidney disease (ADPKD), and renal cell carcinoma (RCC). Targeting ferroptosis with its inducers/initiators and inhibitors can modulate the progression of kidney diseases in animal models. In this review, we discuss the characteristics of ferroptosis and the ferroptosis-based mechanisms, highlighting the potential role of the main ferroptosis-associated metabolic pathways in the treatment and prevention of various kidney diseases.

Hypoxia blocks ferroptosis of hepatocellular carcinoma via suppression of METTL14 triggered YTHDF2-dependent silencing of SLC7A11

Residue hepatocellular carcinoma (HCC) cells enduring hypoxic environment triggered by interventional embolization obtain more malignant potential with little clarified mechanism. The N⁶ -methyladenosine (m⁶ A) biological activity plays essential roles in diverse physiological processes. However, its role under hypoxic condition remains largely unexplored. RT-qPCR and Western blot were used to evaluate METTL14 expression in hypoxic HCC cells. MDA assay and electronic microscopy photography were used to evaluate ferroptosis. The correlation between SLC7A11 and METTL14 was conducted by bioinformatical analysis. Flow cytometry was used to verify the effect of SLC7A11 on ROS production. Cell counting kit-8 assay was performed to detect cells proliferation ability. Hypoxia triggered suppression of METTL14 in a HIF-1α-dependent manner potently abrogated ferroptosis of HCC cells. Mechanistic investigation identified SLC7A11 was a direct target of METTL14. Both in vitro and in vivo assay demonstrated that METTL14 induced m⁶ A modification at 5'UTR of SLC7A11 mRNA, which in turn underwent degradation relied on the YTHDF2-dependent pathway. Importantly, ectopic expression of SLC7A11 strongly blocked METTL14-induced tumour-suppressive effect in hypoxic HCC. Our investigations lay the emphasis on the hypoxia-regulated ferroptosis in HCC cells and identify the HIF-1α /METTL14/YTHDF2/SLC7A11 axis as a potential therapeutic target for the HCC interventional embolization treatment.

Ferroptosis as a new therapeutic opportunity for nonviral liver disease

Nonviral liver disease is a global public health problem due to its high mortality and morbidity. However, its underlying mechanism is unclear. Ferroptosis is a novel form of cell death that is involved in a variety of disease processes. Both abnormal iron metabolism (e.g., iron overload) and lipid peroxidation, which is induced by deletion of glutathione (GSH) or glutathione peroxidase 4 (GPX4), and the accumulation of polyunsaturated fatty acid-containing phospholipids (PUFA-PLs) trigger ferroptosis. Recently, ferroptosis has been involved in the pathological process of nonviral liver diseases [including alcohol-related liver disease (ALD); nonalcoholic fatty liver disease (NAFLD); hereditary hemochromatosis (HH); drug-, ischemia/reperfusion- or immune-induced liver injury; liver fibrosis; and liver cancer]. Hepatocyte ferroptosis is activated in ALD; NAFLD; HH; drug-, ischemia/reperfusion- or immune-induced liver injury; and liver fibrosis, whereas hepatic stellate cell and liver cancer cell ferroptosis are inhibited in liver fibrosis and liver cancer, respectively. Thus, ferroptosis is an ideal target for nonviral liver diseases. In the present review, we discuss the latest findings on ferroptosis and potential drugs targeting ferroptosis for nonviral liver diseases. This review will highlight further directions for the treatment and prevention of nonviral liver diseases.

Organelle-specific regulation of ferroptosis

Ferroptosis, a cell death modality characterized by iron-dependent lipid peroxidation, is involved in the development of multiple pathological conditions, including ischemic tissue damage, infection, neurodegeneration, and cancer. The cellular machinery responsible for the execution of ferroptosis integrates multiple pro-survival or pro-death signals from subcellular organelles and then 'decides' whether to engage the lethal process or not. Here, we outline the evidence implicating different organelles (including mitochondria, lysosomes, endoplasmic reticulum, lipid droplets, peroxisomes, Golgi apparatus, and nucleus) in the ignition or avoidance of ferroptosis, while emphasizing their potential relevance for human disease and their targetability for pharmacological interventions.

Overview of Ferroptosis and Synthetic Lethality Strategies

Ferroptosis, a term first proposed in 2012, is iron-dependent, non-apoptotic regulatory cell death induced by erastin. Ferroptosis was originally discovered during synthetic lethal screening for drugs sensitive to RAS mutant cells, and is closely related to synthetic lethality. Ferroptosis sensitizes cancer stem cells and tumors that undergo epithelial-mesenchymal transition and are resistant to anticancer drugs or targeted therapy. Therefore, ferroptosis-inducing molecules are attractive new research targets. In contrast, synthetic lethal strategies approach mechanisms and genetic abnormalities that cannot be directly targeted by conventional therapeutic strategies, such as RAS mutations, hypoxia, and abnormalities in the metabolic environment. They also target the environment and conditions specific to malignant cells, have a low toxicity to normal cells, and can be used in combination with known drugs to produce new ones. However, the concept of synthetic lethality has not been widely adopted with ferroptosis. In this review, we surveyed the literature on ferroptosis-related factors and synthetic lethality to examine the potential therapeutic targets in ferroptosis-related molecules, focusing on factors related to synthetic lethality, discovery methods, clinical application stages, and issues in drug discovery.

Scalp Acupuncture Protects Against Neuronal Ferroptosis by Activating The p62-Keap1-Nrf2 Pathway in Rat Models of Intracranial Haemorrhage

Intracerebral haemorrhage (ICH) can be a catastrophic event; even if the initial stages of the pathology were well-managed, a number of patients experience varied residual neurological deficits following the insult. Ferroptosis is a recently identified type of cell demise which is tightly linked to the neurological impairment associated with ICH. In the current work, the prophylactic impact of scalp acupuncture (SA) therapy on autologous blood injection murine models of ICH was investigated in order to establish whether SA could mitigate the secondary damage arising following ICH by moderating ferroptosis. The pathophysiological mechanisms associated with this process were also explored. Ludmila Belayev tests were utilised for the characterisation of neurological damage. Haematoxylin–eosin staining was employed in order to determine the cerebral impact of the induced ICH. Malondialdehyde (MDA) and iron titres in peri-haemorrhagic cerebral tissues were appraised using purchased assay kits. Transmission electron microscopy delineated mitochondrial appearances within nerve cell bodies from the area of haemorrhage. Western blotting techniques were utilised to assay the degree of protein expression of NeuN, sequestosome 1 (p62), nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap1), glutathione peroxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1). The frequencies of Nrf2, GPX4 and FTH1 positive cells, respectively, were documented with immunohistochemical staining. The results demonstrated that therapy with SA after ICH mitigated MDA and iron sequestration, diminished the appearance of contracted mitochondria with increased outer mitochondrial membrane diameter within the nerve cell bodies, and suppressed neuronal ferroptosis. The pathways responsible for these effects may encompass amplified p62, Nrf2, GPX4 and FTH1 expression, together with decreased Keap1 expression. Application of SA reduced identified neurobehavioural abnormalities after ICH; no disparities were observed between the consequences of SA therapy and deferoxamine delivery. It can be surmised that intervention with SA enhanced recovery after ICH by triggering the antioxidant pathway, p62/Keap1/Nrf2, and causing FTH1 and GPX4 upregulation, factors that participate in diminishing excess iron and thus in mitigating lipid peroxidation insults arising from ferroptosis following ICH.