HSPB1 as a novel regulator of ferroptotic cancer cell death

Therapeutic Implications of Ferroptosis in Renal Fibrosis

Renal fibrosis is a common feature of chronic kidney disease (CKD), and can lead to the destruction of normal renal structure and loss of kidney function. Little progress has been made in reversing fibrosis in recent years. Ferroptosis is more immunogenic than apoptosis due to the release and activation of damage-related molecular patterns (DAMPs) signals. In this paper, the relationship between renal fibrosis and ferroptosis was reviewed from the perspective of iron metabolism and lipid peroxidation, and some pharmaceuticals or chemicals associated with both ferroptosis and renal fibrosis were summarized. Other programmed cell death and ferroptosis in renal fibrosis were also firstly reviewed for comparison and further investigation.

Novel Prognostic Signature for Acute Myeloid Leukemia: Bioinformatics Analysis of Combined CNV-Driven and Ferroptosis-Related Genes

Background: Acute myeloid leukemia (AML), which has a difficult prognosis, is the most common hematologic malignancy. The role of copy number variations (CNVs) and ferroptosis in the tumor process is becoming increasingly prominent. We aimed to identify specific CNV-driven ferroptosis-related genes (FRGs) and establish a prognostic model for AML.

Methods: The combined analysis of CNV differential data and differentially expressed genes (DEGs) data from The Cancer Genome Atlas (TCGA) database was performed to identify key CNV-driven FRGs for AML. A risk model was constructed based on univariate and multivariate Cox regression analysis. The Gene Expression Omnibus (GEO) dataset was used to validate the model. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to clarify the functional roles of DEGs and CNV-driven FRGs.

Results: We identified a total of 6828 AML-related DEGs, which were shown to be significantly associated with cell cycle and immune response processes. After a comprehensive analysis of CNVs and corresponding DEGs and FRGs, six CNV-driven FRGs were identified, and functional enrichment analysis indicated that they were involved in oxidative stress, cell death, and inflammatory response processes. Finally, we screened 2 CNV-driven FRGs (DNAJB6 and HSPB1) to develop a prognostic risk model. The overall survival (OS) of patients in the high-risk group was significantly shorter in both the TCGA and GEO (all p < 0.05) datasets compared to the low-risk group.

Conclusion: A novel signature based on CNV-driven FRGs was established to predict the survival of AML patients and displayed good performance. Our results may provide potential targets and new research ideas for the treatment and early detection of AML.

Ferroptosis Biology and Implication in Cancers

Ferroptosis, a novel form of regulated cell death (RCD), has garnered increasing attention in studies on numerous human diseases in the last decade. Emerging evidence has indicated that the pathological process of ferroptosis involves the overloaded production of reactive oxygen species (ROS), followed by aberrant accumulation of lipid peroxidation in an iron-dependent manner, accompanied with an increased uptake of polyunsaturated fatty acids into the cellular membrane, further unfolding an ancient vulnerability in multiple context. The unique nature of ferroptosis differentiates it from other forms of RCD, as it is intricately associated with several biological processes, including the metabolism of iron, amino acids, synthesis of ROS and lipid peroxidation. Accordingly, inducers and inhibitors designed to target the key processes of ferroptosis have been extensively studied. Characterized by its distinct properties as mentioned above and its inducible nature, ferroptosis has been widely implicated in several diseases, and numerous studies have focused on identifying effective therapeutic targets for multiple human diseases, including in cancer, by targeting this process. In the present review, recent studies on the involvement of ferroptosis in several types of cancer are summarized and the findings discussed, highlighting the need for increased contemplation of its involvement in the study of cancer, particularly in the clinical setting. A comprehensive summary of the biological mechanisms underlying ferroptosis, the implications of the multiple inducers of ferroptosis, as well as immunotherapy targeting ferroptosis in different types of cancer is provided in this review to highlight the pathophysiological role of ferroptosis in carcinogenesis, to serve as an aid in future studies on the role of ferroptosis in cancer.

Regulation of Inflammatory Cell Death by Phosphorylation

Cell death is a necessary event in multi-cellular organisms to maintain homeostasis by eliminating unrequired or damaged cells. Currently, there are many forms of cell death, and several of them, such as necroptosis, pyroptosis and ferroptosis, even apoptosis trigger an inflammatory response by releasing damage-associated molecular patterns (DAMPs), which are involved in the pathogenesis of a variety of human inflammatory diseases, including autoimmunity disease, diabetes, Alzheimer’s disease and cancer. Therefore, the occurrence of inflammatory cell death must be strictly regulated. Recently, increasing studies suggest that phosphorylation plays a critical role in inflammatory cell death. In this review, we will summarize current knowledge of the regulatory role of phosphorylation in inflammatory cell death and also discuss the promising treatment strategy for inflammatory diseases by targeting related protein kinases that mediate phosphorylation or phosphatases that mediate dephosphorylation.

Shotgun Proteomics for the Identification and Profiling of the Tear Proteome of Keratoconus Patients

Purpose

The qualitative approach followed in this study aims to obtain an extensive view of the keratoconus (KC) tear proteome, which could highlight proteins previously undetected and enlarge our knowledge of the disease's pathophysiology.

Methods

Twenty-five patients diagnosed with KC and 25 control subjects were studied in a prospective, cross-sectional study. KC screening examinations, including clinical and tomographic examinations, were performed on all participants. Tear samples were collected using Schirmer strips and analyzed by liquid chromatography-tandem mass spectrometry in a data-dependent workflow. A spectral count was used as a semiquantification tool. The tear proteomes of both groups were identified and profiled, and the functional interactions and biological characterization of differential proteins were analyzed using in silico tools.

Results

We identified a total of 232 proteins, of whom 133 were expressed in both groups’ samples; 41 were observed only in control samples and 58 were identified just in tears of patients with KC. A semiquantitative analysis showed the dysregulation of 17 proteins in the KC samples. An in silico analysis linked proteins only expressed in KC samples to oxidative stress, skin development, and apoptosis. The dysregulation of proteins involved in iron transport, inflammation, oxidative stress, and protease inhibition was observed in the semiquantitative results.

Conclusions

A shotgun analysis showed that the tear proteome of patients with KC differed from controls by more than one-third of the total proteins identified, highlighting the relationship of the proteins only expressed in KC tears with processes of cell death, oxidative damage, and inflammation. The underexpression of proteins involved in iron pathways might support the iron imbalance as a contributing factor to cellular damage and death in KC disease.

The E3 Ubiquitin Ligase Fbxo4 Functions as a Tumor Suppressor: Its Biological Importance and Therapeutic Perspectives

Simple Summary

Fbxo4 is an E3 ubiquitin ligase that requires the formation of a complex with S-phase kinase-associated protein 1 and Cullin1 to catalyze the ubiquitylation of its substrates. Moreover, Fbxo4 depends on the existence of posttranslational modifications and/or co-factor to be activated to perform its biological functions. The well-known Fbxo4 substrates have oncogenic or oncogene-like activities, for example, cyclin D1, Trf1/Pin2, p53, Fxr1, Mcl-1, ICAM-1, and PPARγ; therefore, Fbxo4 is defined as a tumor suppressor. Biologically, Fbxo4 regulates cell cycle progression, DNA damage response, tumor metabolism, cellular senescence, metastasis and tumor cells’ response to chemotherapeutic compounds. Clinicopathologically, the expression of Fbxo4 is associated with patients’ prognosis depending on different tumor types. Regarding to its complicated regulation, more in-depth studies are encouraged to dissect the detailed molecular mechanisms to facilitate developing new treatment through targeting Fbxo4.

Abstract

Fbxo4, also known as Fbx4, belongs to the F-box protein family with a conserved F-box domain. Fbxo4 can form a complex with S-phase kinase-associated protein 1 and Cullin1 to perform its biological functions. Several proteins are identified as Fbxo4 substrates, including cyclin D1, Trf1/Pin2, p53, Fxr1, Mcl-1, ICAM-1, and PPARγ. Those factors can regulate cell cycle progression, cell proliferation, survival/apoptosis, and migration/invasion, highlighting their oncogenic or oncogene-like activities. Therefore, Fbxo4 is defined as a tumor suppressor. The biological functions of Fbxo4 make it a potential candidate for developing new targeted therapies. This review summarizes the gene and protein structure of Fbxo4, the mechanisms of how its expression and activity are regulated, and its substrates, biological functions, and clinicopathological importance in human cancers.

Revealing the Effects of Endoplasmic Reticulum Stress on Ferroptosis by Two-Channel Real-Time Imaging of pH and Viscosity

Endoplasmic reticulum (ER) is sensitive to changes in the intracellular environment such as pH and viscosity, and slight changes may trigger stress response. Besides, different from apoptosis and necrosis, ferroptosis is the result of lipid peroxidation accumulation. There is evidence that ferroptosis is closely related to endoplasmic reticulum stress (ERS). However, the possible changes in the pH and viscosity of the ER during the ferroptosis process have not yet been studied. Therefore, we used a new type of ER-targeted dual-excitation fluorescent probe (DSPI-3) to investigate the possible changes of pH and viscosity of ER during the ferroptosis. The novel probe DSPI-3 exhibited a highly sensitive and selective response to pH and viscosity. During the bioimaging process, it was found that the ER acidified and viscosity increased during the ferroptosis process induced by erastin, while the cells treated with ferrostatin-1 did not alter significantly. In addition, when dithiothreitol (DTT) and erastin stimulated the cells at the same time, we discovered that ER was acidified considerably at short notice, but the pH was slightly increased in the later stage. Besides, the change of the viscosity enhanced slowly with the passage of time, and there was a noteworthy decline in the later stage, demonstrating that the DTT-induced ERS accelerated the process of ferroptosis. We hope that this unique fluorescent probe can provide an effective method for studying the relationship between ERS and ferroptosis.

Heat Shock Proteins and Ferroptosis

Ferroptosis is a new form of regulatory cell death named by Dixon in 2012, which is characterized by the accumulation of lipid peroxides and iron ions. Molecular chaperones are a class of evolutionarily conserved proteins in the cytoplasm. They recognize and bind incompletely folded or assembled proteins to help them fold, transport or prevent their aggregation, but they themselves do not participate in the formation of final products. As the largest number of molecular chaperones, heat shock proteins can be divided into five families: HSP110 (HSPH), HSP90 (HSPC), HSP70 (HSPA), HSP40 (DNAJ) and small heat shock proteins (HSPB). Different heat shock proteins play different roles in promoting or inhibiting ferroptosis in different diseases. It is known that ferroptosis is participated in tumors, nervous system diseases, renal injury and ischemia-reperfusion injury. However, there are few reviews about the relationship of heat shock proteins and ferroptosis. In this study, we systematically summarize the roles of heat shock proteins in the occurrence of ferroptosis, and predict the possible mechanisms of different families of heat shock proteins in the development of ferroptosis.

Protein post-translational modifications in the regulation of cancer hallmarks

Posttranslational modifications (PTMs) of proteins, the major mechanism of protein function regulation, play important roles in regulating a variety of cellular physiological and pathological processes. Although the classical PTMs, such as phosphorylation, acetylation, ubiquitination and methylation, have been well studied, the emergence of many new modifications, such as succinylation, hydroxybutyrylation, and lactylation, introduces a new layer to protein regulation, leaving much more to be explored and wide application prospects. In this review, we will provide a broad overview of the significant roles of PTMs in regulating human cancer hallmarks through selecting a diverse set of examples, and update the current advances in the therapeutic implications of these PTMs in human cancer.

Ferroptosis in hematological malignancies and its potential network with abnormal tumor metabolism

Ferroptosis, a new type of regulated cell death, displays characteristics that transparently differ from apoptosis, autophagy and necroptosis. There is growing appreciation that targeting ferroptosis is potentially a novel strategy in anti-tumor therapy, especially for invasive malignancies demonstrating resistance to chemotherapy. Almost all types of cancer cells depend on abnormal metabolic activities to participate in vicious progression, giving the possibility to interfere with underlying metabolic preferences and compromise malignant cells by inducing ferroptosis. In this perspective, we give an overview of potential interactions between ferroptosis and abnormal tumor metabolism, with special focus on systematic researches in hematological malignancies.

Monitoring the induction of ferroptosis following dissociation in human embryonic stem cells

Human embryonic stem cells (hESCs) are vulnerable to cell death upon dissociation. Thus, dissociation is an obstacle in culturing, maintaining, and differentiating of hESCs. To date, apoptosis has become the focus of research into the nature of cell death triggered by cellular detachment; it remains baffling whether another form of cell death can occur upon dissociation in hESCs. Here, we demonstrate that iron accumulation and subsequently lipid peroxidation are responsible for dissociation-mediated hESC death. Moreover, we found that a decrease of glutathione peroxidase 4 because of iron accumulation promotes ferroptosis. Inhibition of lipid peroxidation (ferrostatin-1) or chelating iron (deferoxamine) largely suppresses iron accumulation-induced ferroptosis in dissociated hESCs. The results show that P53 mediates the dissociation-induced ferroptosis in hESCs, which is suppressed by pifithrin α. Multiple genes involved in ferroptosis are regulated by the nuclear factor erythroid 2-related factor 2 (Nrf2). In this study, solute carrier family 7 member 11 and glutathione peroxidase 4 are involved in GSH synthesis decreased upon dissociation as a target of Nrf2. In conclusion, our study demonstrates that iron accumulation as a consequence of cytoskeleton disruption appears as a pivotal factor in the initiation of ferroptosis in dissociated hESCs. Nrf2 inhibits ferroptosis via its downstream targets. Our study suggests that the antiferroptotic target might be a good candidate for the maintenance of hESCs.

Application of Regulatory Cell Death in Cancer: Based on Targeted Therapy and Immunotherapy

The development of cancer treatment methods is constantly changing. For common cancers, our treatment methods are still based on conventional treatment methods, such as chemotherapy, radiotherapy, and targeted drug therapy. Nevertheless, the emergence of tumor resistance has a negative impact on treatment. Regulated cell death is a gene-regulated mode of programmed cell death. After receiving specific signal transduction, cells change their physical and chemical properties and the extracellular microenvironment, resulting in structural destruction and decomposition. As research accumulates, we now know that by precisely inducing specific cell death patterns, we can treat cancer with less collateral damage than other treatments. Many newly discovered types of RCD are thought to be useful for cancer treatment. However, some experimental results suggest that some RCDs are not sensitive to cancer cell death, and some may even promote cancer progression. This review summarizes the discovered types of RCDs, reviews their clinical efficacy in cancer treatment, explores their anticancer mechanisms, and discusses the feasibility of some newly discovered RCDs for cancer treatment in combination with the immune and tumor microenvironment.

The Potential Mechanisms by which Artemisinin and Its Derivatives Induce Ferroptosis in the Treatment of Cancer

Artemisinin (ART) is a bioactive molecule derived from the Chinese medicinal plant Artemisia annua (Asteraceae). ART and artemisinin derivatives (ARTs) have been effectively used for antimalaria treatment. The structure of ART is composed of a sesquiterpene lactone, including a peroxide internal bridge that is essential for its activity. In addition to their well-known antimalarial effects, ARTs have been shown recently to resist a wide range of tumors. The antineoplastic mechanisms of ART mainly include cell cycle inhibition, inhibition of tumor angiogenesis, DNA damage, and ferroptosis. In particular, ferroptosis is a novel nonapoptotic type of programmed cell death. However, the antitumor mechanisms of ARTs by regulating ferroptosis remain unclear. Through this review, we focus on the potential antitumor function of ARTs by acting on ferroptosis, including the regulation of iron metabolism, generation of reactive oxygen species (ROS), and activation of endoplasmic reticulum stress (ERS). This article systematically reviews the recent progress in ferroptosis research and provides a basis for ARTs as an anticancer drug in clinical practice.

The Role of Ferroptosis in the Treatment and Drug Resistance of Hepatocellular Carcinoma

Cell death is a fundamental feature of multicellular organisms’ development and a key driver of degenerative diseases. Ferroptosis is a new regulatory cell death mediated by iron-dependent lipid peroxidation, which is different from apoptosis and necrosis in morphology, pathophysiology and mechanism. Recent studies have found that ferroptosis is involved in the development of many diseases including hepatocellular carcinoma (HCC). As further research progresses, specific mechanisms of ferroptosis in HCC are being revealed. In this review, we summarize these recent advances about the treatment of drug-resistance in HCC and the latest ferroptosis-related treatment for HCC.

Ferroptosis: An emerging therapeutic opportunity for cancer

Ferroptosis, a new form of non-apoptotic, regulated cell death characterized by iron dependency and lipid peroxidation, is involved in many pathological conditions such as neurodegenerative diseases, heart ischemia/reperfusion injury, acute renal failure, and cancer. While metabolic dysfunctions can lead to excessive lipid peroxidation culminating in ferroptotic cell death, glutathione peroxidase 4 (GPX4) resides in the center of a network that functions to prevent lipid hydroperoxides from accumulation, thereby suppressing ferroptosis. Indeed, RSL3 and other small-molecule GPX4 inhibitors can induce ferroptosis in not only cultured cancer cells but also tumor xenografts implanted in mice. Similarly, erastin and other system Xc- inhibitors can deplete intracellular glutathione required for GPX4 function, leading to lipid peroxidation and ferroptosis. As therapy-resistant cancer cells are sensitive to GPX4-targeted therapeutic regimens, the agents capable of inducing ferroptosis hold great promises to improve current cancer therapy. This review will outline the molecular basis of ferroptosis, but focus on the strategies and the agents developed in recent years for therapeutic induction of ferroptosis. The potentials of these ferroptosis-inducing agents, which include system Xc- inhibitors, GPX4 inhibitors, and iron-based nanoparticles, in cancer therapy will be subsequently discussed.

Comprehensive analysis of ferroptosis-related genes and prognosis of cutaneous melanoma

BACKGROUND

Cutaneous Melanoma (CM) is a malignant disease with increasing incidence and high mortality. Ferroptosis is a new kind of cell death and related to tumor blood and lymphatic metastasis. This study aims at using bioinformatics technology to construct a prognostic signature and identify ferroptosis-related biomarkers to improve the prognosis and treatment of cutaneous melanoma.

METHODS

We used bioinformatics tools to analyze RNA sequencing expression data with clinical information from multiple databases, utilized varieties of statistical methods to construct a ferroptosis-related prognostic signature of cutaneous melanoma and screened out specific genes with independent prognostic ability.

RESULTS

We obtained 22 ferroptosis-related (P < 0.05) prognostic DEGs in the uniCox regression analysis, among which 10 high-expressed genes (ATG5, CHAC1, FANCD2, FBXL5, HMOX2, HSPB1, NQO1, PEBP1, PRNP, SLC3A2) were screened out by LASSO regression analysis to establish a predictive model. Meanwhile, the ferroptosis-related signature and the nomogram we drew performed an excellent performance based on Kaplan-Meier (K-M), Receiver operating characteristic (ROC) and calibration curves. Univariate and multivariable cox analyses displayed that our model was greater than other prognostic features. GO and KEGG analyses revealed that 10-biomarker signature was mainly related to epidermis differentiation and immunity. ssGSEA analysis indicated that the immune status between the two risk groups was highly different. Besides, we found that two genes (CP, ZEB1) had independent prognostic ability and can be applied for drug research. Both genes were highly related to immunity. GSEA illustrated that ZEB1 may be involved in cellular functions such as proliferation, apoptosis, and migration, while CP was closely connected to immune cell related functions.

CONCLUSION

The present study suggested a 10-biomarker signature can be clinically used to predict the prognosis of cutaneous melanoma, which was better than conventional factors. CP and ZEB1 were independent prognostic genes and can be applied to guide treatment. In addition, ZEB1 mutation was highly related to overall survival in cutaneous melanoma, while CP may be associated with tumor progression. Our study comprehensively analyzed the relationship between iron metabolism, ferroptosis-related genes, and the prognosis of cutaneous melanoma, provided new insight for molecular mechanisms and treatment of ferroptosis and cutaneous melanoma.

Tumour cells are sensitised to ferroptosis via RB1CC1‐mediated transcriptional reprogramming

Background

Ferroptosis, a form of regulated cell death, is an important topic in the field of cancer research. However, the signalling pathways and factors that sensitise tumour cells to ferroptosis remain elusive.

Methods

We determined the level of ferroptosis in cells by measuring cell death and lipid reactive oxygen species (ROS) production. The expression of RB1‐inducible coiled‐coil 1 (RB1CC1) and related proteins was analyzed by immunoblotting and immunohistochemistry. Immunofluorescence was used to determine the subcellular localization of RB1CC1. We investigated the mechanism of RB1CC1 nuclear translocation by constructing a series of RB1CC1 variants. To examine the ferroptosis‐ and RB1CC1‐dependent transcriptional program in tumour cells, chromatin immunoprecipitation sequencing was performed. To assess the effect of c‐Jun N‐terminal kinase (JNK) agonists on strenthening imidazole ketone erastin (IKE) therapy, we constructed cell‐derived xenograft mouse models. Mouse models of hepatocellular carcinoma to elucidate the importance of Rb1cc1 in IKE‐based therapy of liver tumourigenesis.

Results

RB1CC1 is upregulated by lipid ROS and that nuclear translocation of phosphorylation of RB1CC1 at Ser537 was essential for sensitising ferroptosis in tumour cells. Upon ferroptosis induction, nuclear RB1CC1 sharing forkhead box (FOX)‐binding motifs recruits elongator acetyltransferase complex subunit 3 (ELP3) to strengthen H4K12Ac histone modifications within enhancers linked to ferroptosis. This also stimulated transcription of ferroptosis‐associated genes, such as coiled‐coil–helix–coiled‐coil–helix domain containing 3 (CHCHD3), which enhanced mitochondrial function to elevate mitochondrial ROS early following induction of ferroptosis. FDA‐approved JNK activators reinforced RB1CC1 nuclear translocation and sensitised cells to ferroptosis, which strongly suggested that JNK is upstream of RB1CC1. Nuclear localisation of RB1CC1 correlated with lipid peroxidation in clinical lung cancer specimens. Rb1cc1 was essential for ferroptosis agonists to suppress liver tumourigenesis in mice.

Conclusions

Our findings indicate that RB1CC1‐associated signalling sensitises tumour cells to ferroptosis and that targeting RB1CC1 may be beneficial for tumour treatment.

Insights Into Ferroptosis, a Novel Target for the Therapy of Cancer

Ferroptosis is a new form of programmed cell death (PCD) characterized by an excess iron accumulation and subsequent unbalanced redox states. Ferroptosis is different from the already reported PCD and has unique morphological features and biochemical processes. Ferroptosis was first elaborated by Brent R. Stockwell’s lab in 2012, in which small molecules erastin and RSL-3 induce PCD in Ras mutant cell lines. Ferroptosis involves various physiological processes and occurrence of disease and especially shows strong potential in cancer treatment. Development of small molecule compounds based on Stockwell’s research was found to kill cancer cells, and some FDA-approved drugs were discovered to result in ferroptosis of cancer cells. Radiotherapy and checkpoint therapy have been widely used as a treatment for many types of cancer. Recently, some papers have reported that chemotherapy, radiotherapy, and checkpoint therapy induce ferroptosis of cancer cells, which provides new strategies for cancer treatment. Nevertheless, the limitless proliferation of tumor cells and the lack of cell death mechanisms are important reasons for drug resistance for tumor therapy. Therefore, we reviewed the molecular mechanism of ferroptosis and sensitivity to ferroptosis of different cancer cells and tumor treatment strategy.

Ferroptosis Inhibitors as Potential New Therapeutic Targets for Cardiovascular Disease

Abstract:

Ferroptosis is a novel form of programmed cell death that arises as a result of an increase in iron levels. Ferroptosis is implicated in a number of cardiovascular diseases, including myocardial infarction (MI), reperfusion damage, and heart failure(HF). Because cardiomyocyte depletion is the leading cause of patient morbidity and mortality, it is critical to thoroughly comprehend the regulatory mechanisms of ferroptosis activation. In fact, inhibiting cardiac ferroptosis has the potential to be a useful therapeutic method for cardiovascular disorders. The iron, lipid, amino acid, and glutathione metabolism strictly governs the beginning and execution of ferroptosis. Therefore, ferroptosis can be inhibited by iron chelators, free radical-trapping antioxidants, GPX4 (Glutathione Peroxidase 4) activators, and lipid peroxidation (LPO) inhibitors. However, the search for new molecular targets for ferroptosis is becoming increasingly important in cardiovascular disease research. In this review, we address the importance of ferroptosis in various cardiovascular illnesses, provide an update on current information about the molecular mechanisms that drive ferroptosis, and discuss the role of ferroptosis inhibitors in cardiovascular disease.

The Emerging Role of Ferroptosis in Cardiovascular Diseases

Ferroptosis is one type of programmed cell death discovered in recent years, which is characterized by iron-dependent lipid peroxidation and participating in iron, lipid and antioxidant metabolism. Ferroptosis is different from the traditional cell death types such as apoptosis, necroptosis and autophagy in morphology, biochemistry and genetics. Cardiovascular diseases are considered as an important cause of death from non-communicable diseases in the global population and poses a serious threat to human health. Apoptosis has long been thought to be the major type of cardiomyocyte death, but now ferroptosis has been shown to play a major role in cardiovascular diseases as well. This review will discuss related issues such as the mechanisms of ferroptosis and its effects on the occurrence and development of cardiovascular diseases, aiming to provide a novel target for the prevention and treatment of cardiovascular diseases.

Genetic analysis of potential biomarkers and therapeutic targets in ferroptosis from coronary artery disease

Ferroptosis plays a key role in the death of cells including cardiomyocytes, and it is related to a variety of cardiac diseases. However, the role of ferroptosis‐related genes (FRGs) in coronary artery disease (CAD) is not well characterized. We downloaded CAD‐related information and FRGs from the gene expression omnibus (GEO) database and Ferroptosis Database (FerrDb) respectively. A total of 10 CAD‐related DE‐FRGs were obtained, which were closely linked to autophagy regulation and immune response. Subsequently, CA9, CBS, CEBPG, HSPB1, SLC1A4, STMN1 and TRIB3 among the 10 DE‐FRGs were identified as marker genes by LASSO and SVM‐RFE algorithms, which had tolerable diagnostic capabilities. Subsequent functional enrichment analysis showed that these marker genes may play a corresponding role in CAD by participating in the regulation of immune response, amino acid metabolism, cell cycle and multiple pathways related to the pathogenesis of CAD. Furthermore, a total of 58 drugs targeting 7 marker genes had been obtained. On the contrary, the ceRNA network revealed a complex regulatory relationship based on the marker genes. Also, CIBERSORT analysis showed that the changes in the immune microenvironment of CAD patients may be related to CBS, HSPB1 and CEBPG. We developed a diagnostic potency and provided an insight for exploring the mechanism for CAD. Before clinical application, further research is needed to test its diagnostic value for CAD.

Targeting Ferroptosis Pathways: A Novel Strategy for Cancer Therapy

Abstract:

Ferroptosis is an iron-dependent nonapoptotic kind of regulated cell death resulting from the destruction of redox balance in the cytosol. Unlike apoptosis, ferroptosis is caused by an increase in intracellular iron and lipid peroxides that causes significant damage to the membrane lipid bilayer and mitochondria, which leads to cell death. Increased iron level in the cell promotes ROS production. Ferroptosis inducer molecules increase ROS production and inhibit the antioxidant defence mechanism to facilitate ferroptosis in cancer cells. Inhibition of GPX4, redox-active iron availability, and lipid peroxidation are major contributors to ferroptosis. Ferroptosis is involved in many diseases like heart disease, neurodegenerative disease as well as cancer. Ferroptosis induction recently emerged as an attractive strategy for cancer therapy. In this review, we discuss the regulatory mechanism of ferroptosis, its different hallmarks, including genetic and metabolic regulators and inducers that promote ferroptosis in the cancer cells. Finally, the latest progress and development in ferroptosis research in different cancer with a focus on proposing a novel strategy in cancer therapy, are discussed.

A Ferroptosis-Related Gene Prognostic Index Associated With Biochemical Recurrence and Radiation Resistance for Patients With Prostate Cancer Undergoing Radical Radiotherapy

Background: Ferroptosis is a new type of programmed cell death which has been reported to be involved in the development of various cancers. In this study, we attempted to explore the possible links between ferroptosis and prostate cancer (PCa), and a novel ferroptosis-related gene prognostic index (FGPI) was constructed to predict biochemical recurrence (BCR) and radiation resistance for PCa patients undergoing radical radiotherapy (RRT). Moreover, the tumor immune microenvironment (TME) of PCa was analyzed.

Methods: We merged four GEO datasets by removing batch effects. All analyses were conducted with R version 3.6.3 and its suitable packages. Cytoscape 3.8.2 was used to establish a network of transcriptional factor and competing endogenous RNA.

Results: We established the FGPI based on ACSL3 and EPAS1. We observed that FGPI was an independent risk factor of BCR for PCa patients (HR: 3.03; 95% CI: 1.68–5.48), consistent with the result of internal validation (HR: 3.44; 95% CI: 1.68–7.05). Furthermore, FGPI showed high ability to identify radiation resistance (AUC: 0.963; 95% CI: 0.882–1.00). LncRNA PART1 was significantly associated with BCR and might modulate the mRNA expression of EPAS1 and ACSL3 through interactions with 60 miRNAs. Gene set enrichment analysis indicated that FGPI was enriched in epithelial–mesenchymal transition, allograft rejection, TGF beta signaling pathway, and ECM receptor interaction. Immune checkpoint and m6A analyses showed that PD-L2, CD96, and METTL14 were differentially expressed between BCR and no BCR groups, among which CD96 was significantly associated with BCR-free survival (HR: 1.79; 95% CI: 1.06–3.03). We observed that cancer-related fibroblasts (CAFs), macrophages, stromal score, immune score, estimate score, and tumor purity were differentially expressed between BCR and no BCR groups and closely related to BCR-free survival (HRs were 2.17, 1.79, 2.20, 1.93, 1.92, and 0.52 for cancer-related fibroblasts, macrophages, stromal score, immune score, estimate score, and tumor purity, respectively). Moreover, cancer-related fibroblasts (coefficient: 0.20), stromal score (coefficient: 0.14), immune score (coefficient: 0.14), estimate score (coefficient: 0.15), and tumor purity (coefficient: −0.15) were significantly related to FGPI, among which higher positive correlation between cancer-related fibroblasts and FGPI was observed.

Conclusion: We found that FGPI based on ACSL3 and EPAS1 might be used to predict BCR and radiation resistance for PCa patients. CD96 and PD-L2 might be a possible target for drug action. Besides, we highlighted the importance of immune evasion in the process of BCR.

Targeting ferroptosis in acute kidney injury

Acute kidney injury (AKI) is a major public health problem with high incidence and mortality. As a form of programmed cell death (PCD), ferroptosis could be considered as a process of iron accumulation and enhanced lipid peroxidation. Recently, the fundamental roles of ferroptosis in AKI have attracted much attention. The network mechanism of ferroptosis in AKI and its roles in the AKI to chronic kidney disease (CKD) transition is complicated and multifactorial. Strategies targeting ferroptosis show great potential. Here, we review the research progress on ferroptosis and its participation in AKI. We hope that this work will provide clues for further studies of ferroptosis in AKI.

Vulnerability of Triple-Negative Breast Cancer to Saponin Formosanin C-Induced Ferroptosis

Targeting ferritin via autophagy (ferritinophagy) to induce ferroptosis, an iron- and reactive oxygen species (ROS)-dependent cell death, provides novel strategies for cancer therapy. Using a ferroptosis-specific inhibitor and iron chelator, the vulnerability of triple-negative breast cancer (TNBC) MDA-MB-231 cells to ferroptosis was identified and compared to that of luminal A MCF-7 cells. Saponin formosanin C (FC) was revealed as a potent ferroptosis inducer characterized by superior induction in cytosolic and lipid ROS formation as well as GPX4 depletion in MDA-MB-231 cells. The FC-induced ferroptosis was paralleled by downregulation of ferroportin and xCT expressions. Immunoprecipitation and electron microscopy demonstrated the involvement of ferritinophagy in FC-treated MDA-MB-231 cells. The association of FC with ferroptosis was strengthened by the results that observed an enriched pathway with differentially expressed genes from FC-treated cells. FC sensitized cisplatin-induced ferroptosis in MDA-MB-231 cells. Through integrated analysis of differentially expressed genes and pathways using the METABRIC patients’ database, we confirmed that autophagy and ferroptosis were discrepant between TNBC and luminal A and that TNBC was hypersensitive to ferroptosis. Our data suggest a therapeutic strategy by ferroptosis against TNBC, an aggressive subtype with a poor prognosis.

The multifaceted role of ferroptosis in liver disease

Ferroptosis is an iron-dependent form of non-apoptotic cell death characterized by excessive lipid peroxidation and associated with a plethora of pathological conditions in the liver. Emerging evidence supports the notion that dysregulated metabolic pathways and impaired iron homeostasis play a role in the progression of liver disease via ferroptosis. Although the molecular mechanisms by which ferroptosis causes disease are poorly understood, several ferroptosis-associated genes and pathways have been implicated in liver disease. Here, we review the physiological role of the liver in processing nutrients, our current understanding of iron metabolism, the characteristics of ferroptosis, and the mechanisms that regulate ferroptosis. In addition, we summarize the role of ferroptosis in the pathogenesis of liver disease, including liver injury, non-alcoholic steatohepatitis, liver fibrosis, liver cirrhosis, and hepatocellular carcinoma. Finally, we discuss the therapeutic potential of targeting ferroptosis for managing liver disease.

Ferroptosis: A Potential Target in Cardiovascular Disease

Ferroptosis is a new form of regulatory cell death characterized by iron-dependent and intracellular lipid peroxidation. Ferroptosis can be divided into two stages. The first stage is iron overload in the cell, which generates a large amount of reactive oxygen species through the Fenton reaction, and the second stage results from an imbalance of the intracellular antioxidant system. Excessive phospholipid hydroperoxides cannot be removed by reduction reactions, as this could destroy the cell membrane structure and interfere with mitochondrial function, eventually leading to ferroptosis of the cell. Cardiovascular diseases have gradually become the leading cause of death in modern society. The relationship between ferroptosis and the occurrence and progression of cardiovascular disease has become a research hotspot in recent years. In this review, we summarize the mechanism of ferroptosis and its specific role in cardiovascular disease.

Molecular regulatory mechanism of ferroptosis and its role in gastrointestinal oncology: Progress and updates

Gastrointestinal (GI) tumors, including liver, pancreatic, gastric, and colorectal cancers, have a high incidence rate and low survival rate due to the lack of effective therapeutic methods and frequent relapses. Surgery and postoperative chemoradiotherapy have largely reduced the fatality rates for most GI tumors, but these therapeutic approaches result in poor prognoses due to severe adverse reactions and the development of drug resistance. Recent studies have shown that ferroptosis plays an important role in the onset and progression of GI tumors. Ferroptosis is a new non-apoptotic form of cell death, which is iron-dependent, non-apoptotic cell death characterized by the accumulation of lipid reactive oxygen species (ROS). The activation of ferroptosis can lead to tumor cell death. Thus, regulating ferroptosis in tumor cells may become a new therapeutic approach for tumors, making it become a research hotspot. Current studies suggest that ferroptosis is mainly triggered by the accumulation of lipid ROS. Furthermore, several studies have indicated that ferroptosis may be a new approach for the treatment of GI tumors. Here, we review current research progress on the mechanism of ferroptosis, current inducers and inhibitors of ferroptosis, and the role of ferroptosis in GI tumors to propose new methods for the treatment of such tumors.

Autophagy-Dependent Ferroptosis-Related Signature is Closely Associated with the Prognosis and Tumor Immune Escape of Patients with Glioma

Background

Ferroptosis is an autophagy-dependent form of cell death, sometimes called “ferritinophagy”. Its related pathway has been proven to regulate the programmed death of glioma stem cells. Mining autophagy-dependent ferroptosis-related gene (AD-FRG) signature could facilitate the discovery of mechanisms and therapeutic targets showing drug resistance to chemotherapeutic drugs.

Methods

We exhaustively searched HADB, MSigDB and FerrDb datasets and obtained 25 genes confirmed to exist in autophagy and ferroptosis death pathways. Glioma gene expression and clinicopathological data were collected from TCGA and CGGA datasets.

Results

Lasso regression and Cox regression analysis were carried out to construct a nine AD-FRGs signature (SIRT1, MTDH, HSPB1, CISD2, HMOX1, ATG7, MTOR, PRKAA2 and EIF2AK4). ROC curve showed that nine genes signature could effectively predict 1- (AUC = 0.869), 3- (AUC = 0.922) and 5-year (AUC = 0.870) survival rates. Immunohistochemical images confirmed the protein expression level of the gene model. The prognostic nomogram of risk score, age, WHO grade, isocitrate dehydrogenase (IDH) wild-type condition, 1p/19q co-deletion state was built. The calibration curve demonstrated that the prediction of the nomogram is highly consistent with the actual results. Moreover, tumor microenvironment analysis showed that the high-risk group was associated with high immune infiltration status and high tumor purity. Correlation analysis showed that the expression of SIRT1, CISD2 and HSPB1 might be related to macrophage infiltration and immunotolerance in glioma tissues.

Conclusion

Based on autophagy-dependent ferroptosis-related genes, we established gene signature and nomogram that maybe effectively predict the overall survival rate of glioma and correlate with the immunosuppressive tumor microenvironment (TME).

Identification of Ferroptosis-Related Gene Prognostic Signature and HSF1 for Reversing Doxorubicin and Gemcitabine Resistance in Uterine Carcinosarcoma

Purpose

Iron metabolism and ferroptosis play crucial roles in the pathogenesis of cancer. In this study, we aim to study the role of ferroptosis-related genes (FRGs) in uterine carcinosarcoma (UCS) and identify potential target for UCS.

Methods

Prognostic differentially expressed FRGs were identified of in the TCGA cohort. Integrated analysis, cox regression, and the least absolute shrinkage and selection operator (LASSO) methods of FRGs were performed to construct a multigene signature prognostic model. Moreover, a dataset from Gene Expression Omnibus (GEO) served as an external validation. HSF1 was knockdown in MES-SA and FU-MMT-1 cells, and cell viability, lipid ROS, and intracellular iron level were detected when combined with doxorubicin or gemcitabine.

Result

Five FRGs were selected to construct a prognostic model of UCS. The group with high-risk signature score exhibited obviously lower overall survival (OS) than the group with low risk signature score in both TCGA and validated GEO cohorts. Multivariate Cox regression analysis further indicated that the risk score was an independent factor for the prognosis of UCS patients. The high-risk group of UCS has a higher sensitivity in the treatment of doxorubicin and gemcitabine. Knocking down of HSF1 in MES-SA and FU-MMT-1 cells was more sensitive to doxorubicin and gemcitabine via increasing ferroptosis.

Conclusions

The five FRGs risk signature prognostic model having a superior and drug sensitivity predictive performance for OS in UCS, and HSF1 is a potential marker sensitive to doxorubicin and gemcitabine in UCS patients.

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.

Hepcidin Promoted Ferroptosis through Iron Metabolism which Is Associated with DMT1 Signaling Activation in Early Brain Injury following Subarachnoid Hemorrhage

Iron metabolism disturbances play an important role in early brain injury (EBI) after subarachnoid hemorrhage (SAH), and hepcidin largely influences iron metabolism. Importantly, iron metabolism may be associated with ferroptosis, recently a nonapoptotic iron-dependent form of cell death that may have a great impact on brain injury after SAH. We investigated hepcidin on iron metabolism and ferroptosis involving divalent metal transporter 1 (DMT1), and ferroportin-1 (FPN1) in a rat model of SAH. Male Sprague-Dawley rats were subjected to the endovascular perforation to induce SAH, and treated with heparin (inhibitor of hepcidin), or oncostatin M (OSM, inducer of hepcidin), or ebselen (inhibitor of DMT1) by intracerebroventricular injections. Hepcidin, DMT1, FPN1 and glutathione peroxidase 4 (GPX4), were detected by western blot and immunofluorescence. Iron metabolism was detected through Perl's iron staining and iron content assay. Ferroptosis, the ROS production, lipid peroxidation (LPO) was evaluated by monitoring methane dicarboxylic aldehyde (MDA), glutathione (GSH), glutathione peroxidase 4 (GPX4) activity, and transmission electron microscopy. Neurological deficit scores, Evans blue staining and brain water content were also determined to detect EBI 72 h after SAH. Our results showed that inhibition of DMT1 by ebselen could suppress iron accumulation and lipid peroxidation, and thereby alleviate ferroptosis and EBI in SAH rats. Heparin downregulated the expression of hepcidin and DMT1, increased FPN1, and exerted protective effects that were equivalent to those of ebselen on ferroptosis and EBI. In addition, OSM increased the expression of hepcidin and DMT1, decreased FPN1, and aggravated ferroptosis and EBI, while the effect on ferroptosis was reversed by ebselen. Therefore, the study revealed that hepcidin could regulate iron metabolism and contribute to ferroptosis via DMT1 signaling activation in rats with EBI after SAH.

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.

A century of programmed cell death in the ovary: a commentary

Programmed cell death (PCD) has been discussed and categorized endlessly over the years. Herein, we comment on the chaotic classification of PCD in the mammalian ovary and the compartmentalized ovarian follicle based on an unfiltered overview of the extent of publication about some of the different modes of PCD on PubMed.

Ferroptosis as a Novel Therapeutic Target for Diabetes and Its Complications

The global diabetes epidemic and its complications are increasing, thereby posing a major threat to public health. A comprehensive understanding of diabetes mellitus (DM) and its complications is necessary for the development of effective treatments. Ferroptosis is a newly identified form of programmed cell death caused by the production of reactive oxygen species and an imbalance in iron homeostasis. Increasing evidence suggests that ferroptosis plays a pivotal role in the pathogenesis of diabetes and diabetes-related complications. In this review, we summarize the potential impact and regulatory mechanisms of ferroptosis on diabetes and its complications, as well as inhibitors of ferroptosis in diabetes and diabetic complications. Therefore, understanding the regulatory mechanisms of ferroptosis and developing drugs or agents that target ferroptosis may provide new treatment strategies for patients with diabetes.

Integrative analysis of the molecular mechanisms, immunological features and immunotherapy response of ferroptosis regulators across 33 cancer types

Ferroptosis is a recently described mode of cell death caused by the accumulation of intracellular iron and lipid reactive oxygen species (ROS), which play critical roles in tumorigenesis and cancer progression. However, the underlying molecular mechanisms and promising biomarkers of ferroptosis among cancers remain to be elucidated. In this study, 30 ferroptosis regulators in ferroptosis-related signaling pathways were identified and analyzed in 33 cancer types. We found transcriptomic aberrations and evaluated the prognostic value of ferroptosis regulators across 33 cancer types. Then, we predicted and validated potential transcription factors (including E2F7, KLF5 and FOXM1) and therapeutic drugs (such as cyclophosphamide, vinblastine, and gefitinib) that target ferroptosis regulators in cancer. Moreover, we explored the molecular mechanisms of ferroptosis and found that signaling pathways such as the IL-1 and IL-2 pathways are closely associated with ferroptosis. Additionally, we found that ferroptosis regulators have a close relationship with immunity-related parameters, including the immune score, immune cell infiltration level, and immune checkpoint protein level. Finally, we determined a ferroptosis score using GSVA method. We found that the ferroptosis score effectively predicted ferroptotic cell death in tumor samples. And ferroptosis score is served as an independent prognostic indicator for the incidence and recurrence of cancers. More importantly, patients with high ferroptosis scores received greater benefit from immunotherapy. We aslo created an online webserver based on the nomogram prognostic model to predict the survival in immunotherapy cohort. The reason for this outcome is partially the result of patients with a high ferroptosis rate also having high immune scores, HLA-related gene expression and immune checkpoint protein expression, such as PDL2 and TIM3. Moreover, patients with high ferroptosis scores exhibited CD8 T cell and TIL infiltration and immune-related signaling pathway enrichment. In summary, we systematically summarize the molecular characteristics, clinical relevance and immune features of ferroptosis across cancers and show that the ferroptosis score can be used as a prognostic factor and for the evaluation of immunotherapy effects.

Ferroptosis-Enhanced Cancer Immunity by a Ferrocene-Appended Iridium(III) Diphosphine Complex

Ferroptosis is a programmed cell death pathway discovered in recent years, and ferroptosis-inducing agents have great potential as new antitumor candidates. Here, we report a Ir(III) complex (Ir1) containing a ferrocene-modified diphosphine ligand that localizes in lysosomes. Under the acidic environments of lysosomes, Ir1 can effectively catalyze Fenton reaction, produce hydroxyl radicals, induce lipid peroxidation, down-regulate glutathione peroxidase 4, and induce ferroptosis. RNA sequencing analysis shows that Ir1 can significantly affect pathways related to ferroptosis and cancer immunity. Accordingly, Ir1 can induce immunogenic cells death and suppress tumor growth in vitro, regulate T cell activity and immune microenvironments in vivo. In conclusion, we show the potential of small molecules with ferroptosis-inducing capabilities for effective cancer immunotherapy.

Roles of ferroptosis in urologic malignancies

Ferroptosis, an iron-dependent form of non-apoptotic cell death, is believed to strongly contribute to the pathogenesis of multiple cancers. Recently, the positive association between ferroptosis and urologic malignancies has drawn considerable attention, while a comprehensive review focused on this issue is absent. Based on this review, ferroptosis has been implicated in the development and therapeutic responses of prostate cancer, kidney cancer, and bladder cancer. Mechanistically, a large number of biomolecules and tumor-associated signaling pathways, including DECR1, PANX2, HSPB1, ACOT8, SUV39H1, NCOA4, PI3K-AKT-mTOR signaling, VHL/HIF-2α pathway, and Hippo/TAZ signaling pathway, have been reported to regulate ferroptosis in urologic cancers. Ferroptosis inducers, such as erastin, ART, CPNPs, and quinazolinyl-arylurea derivatives, exert potential therapeutic effects per se and/or enhance the anticancer response of other anticancer drugs in urologic oncology. A better understanding of ferroptosis may provide a promising way to treat therapy-resistant urologic cancers.

Ferroptosis: The Silver Lining of Cancer Therapy

Regulatory cell death has been a major focus area of cancer therapy research to improve conventional clinical cancer treatment (e.g. chemotherapy and radiotherapy). Ferroptosis, a novel form of regulated cell death mediated by iron-dependent lipid peroxidation, has been receiving increasing attention since its discovery in 2012. Owing to the highly iron-dependent physiological properties of cancer cells, targeting ferroptosis is a promising approach in cancer therapy. In this review, we summarised the characteristics of ferroptotic cells, associated mechanisms of ferroptosis occurrence and regulation and application of the ferroptotic pathway in cancer therapy, including the use of ferroptosis in combination with other therapeutic modalities. In addition, we presented the challenges of using ferroptosis in cancer therapy and future perspectives that may provide a basis for further research.

Research progress on the mechanism of ferroptosis and its clinical application

Ferroptosis is a mode of cell death dependent on iron ions, which is mainly induced by the decrease of the biological activity of glutathione peroxidase or the accumulation of lipid peroxidation and reactive oxygen species (ROS). It is significantly different from autophagy and other forms of cell death in terms of cell morphology and biochemistry. The exact mechanisms of ferroptosis are not clear. More and more studies have shown that various tumor diseases and nervous system diseases are closely related to ferroptosis. The occurrence and development of related diseases can be tolerated by stimulating or inhibiting the occurrence of ferroptosis. Therefore, ferroptosis has occupied a very important position in recent years. This article reviews the discovery process, characteristics, mechanisms, inducers, inhibitors of ferroptosis and its related clinical applications to lay a foundation for follow-up researchers to study ferroptosis and provide some reference value.

Iron homeostasis in arthropathies: From pathogenesis to therapeutic potential

Iron is an essential element for proper functioning of cells within mammalian organ systems; in particular, iron homeostasis is critical for joint health. Excess iron can induce oxidative stress damage, associated with the pathogenesis of iron-storage and ageing-related diseases. Therefore, iron levels in body tissues and cells must be tightly regulated. In the past decades, excess iron content within joints has been found in some patients with joint diseases including hemophilic arthropathy, hemochromatosis arthropathy, and osteoarthritis (OA). Currently, increased evidence has shown that iron accumulation is closely associated with multiple pathological changes of these arthropathies. This review summarizes system-level and intracellular regulation of iron homeostasis, and emphasizes the role of iron in synovial alterations, cartilage degeneration, and subchondral bone of several arthropathies. Of note, we discuss the potential link between iron homeostasis and OA pathogenesis. Finally, we discuss the therapeutic potential of maintaining iron homeostasis in these arthropathies.

SLC7A11/ xCT is a target of miR-5096 and its restoration partially rescues miR-5096-mediated ferroptosis and anti-tumor effects in human breast cancer cells

Breast cancer cells evade cell death by overexpressing SLC7A11, which functions by transporting cystine into cells in exchange for intracellular glutamate facilitating glutathione synthesis and reducing reactive oxygen species (ROS)-mediated stress. Using an in silico approach, we predicted an miRNA (miR-5096) that can target and downregulate SLC7A11. We demonstrated SLC7A11 as a target of miR-5096 by 3'UTR luciferase assay and further validated it by identifying reduced mRNA and protein levels of SLC7A11 upon miR-5096 overexpression. miR-5096-induced ferroptotic cell death in human breast cancer cells was confirmed by concurrently increased ROS, OH^-, lipid ROS, and iron accumulation levels and decreased GSH and mitochondrial membrane potential (MitoTracker™ Orange) with mitochondrial shrinkage and partial cristae loss (observed by TEM). miR-5096 inhibited colony formation, transwell migration, and breast cancer cell invasion, whereas antimiR-5096 promoted these tumorigenic properties. Ectopic expression of SLC7A11 partly reversed miR-5096-mediated effects on cell survival, ROS, lipid peroxides, iron accumulation, GSH, hydroxyl radicals, mitochondrial membrane potential, and colony formation. miR-5096 modulated the expression of epithelial-mesenchymal transition markers in vitro and inhibited the metastatic potential of MDA-MB-231 cells in a tumor xenograft model of zebrafish larvae. Our results demonstrate that miR-5096 is a tumor-suppressive miRNA in breast cancer cells, and this paper discusses its therapeutic implications.

Cancer: The role of iron and ferroptosis

Iron is an essential element for virtually all living things. Body iron levels are tightly controlled as both increased iron levels and iron deficiency are associated with many clinical conditions. Increased iron levels are associated with a worse prognosis in some cancers, so understanding the role of iron in cancer development has thus been an active area of research. Regulated forms of cell death are important in development and disease pathogenesis. In this Medicine in Focus review article, we discuss the role of iron in cancer, and ferroptosis, a new form of iron-regulated cell death triggered by increased iron and peroxidation of lipids. We also review the pathogenesis of cancer, potential therapeutics for targeting the increased requirement of iron, as well as how ferroptosis activation may have a role in treatment of cancers.

Prognostic Model and Nomogram Construction Based on a Novel Ferroptosis-Related Gene Signature in Lower-Grade Glioma

Background: Low-grade glioma (LGG) is considered a fatal disease for young adults, with overall survival widely ranging from 1 to 15 years depending on histopathologic and molecular subtypes. As a novel type of programmed cell death, ferroptosis was reported to be involved in tumorigenesis and development, which has been intensively studied in recent years.

Methods: For the discovery cohort, data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) were used to identify the differentially expressed and prognostic ferroptosis-related genes (FRGs). The least absolute shrinkage and selection operator (LASSO) and multivariate Cox were used to establish a prognostic signature with the above-selected FRGs. Then, the signature was developed and validated in TCGA and Chinese Glioma Genome Atlas (CGGA) databases. By combining clinicopathological features and the FRG signature, a nomogram was established to predict individuals’ one-, three-, and five-year survival probability, and its predictive performance was evaluated by Harrell’s concordance index (C-index) and calibration curves. Enrichment analysis was performed to explore the signaling pathways regulated by the signature.

Results: A novel risk signature contains seven FRGs that were constructed and were used to divide patients into two groups. Kaplan–Meier (K−M) survival curve and receiver-operating characteristic (ROC) curve analyses confirmed the prognostic performance of the risk model, followed by external validation based on data from the CGGA. The nomogram based on the risk signature and clinical traits was validated to perform well for predicting the survival rate of LGG. Finally, functional analysis revealed that the immune statuses were different between the two risk groups, which might help explain the underlying mechanisms of ferroptosis in LGG.

Conclusion: In conclusion, this study constructed a novel and robust seven-FRG signature and established a prognostic nomogram for LGG survival prediction.

Biological protein mediated ferroptotic tumor nanotherapeutics

Ferroptosis, a cell death pathway involving iron-related generation of lipid hydroperoxides for achieving incredible tumor suppression, has reignited the hope of chemotherapy in tumor treatment in the past decade. With extensive research studies, various bioactive proteins and cellular pathways have been demonstrated to regulate the occurrence and development of ferroptosis. The gradually established ferroptotic regulatory network is conducive to find effective proteins from a holistic perspective and guides better designs for future ferroptotic tumor therapies. The first section of this review summarizes the recent advances in ferroptotic regulatory mechanisms of proteins and attempts to clarify their latent function in the ferroptotic regulatory network. Second, the existing protein-mediated ferroptotic tumor nanotherapeutic strategies were reviewed, including the protein-mediated iron supplement, cell membrane transporter inhibition, glutathione peroxidase 4 interference, glutathione depletion, bioenzyme-mediated reactive oxygen species generation, heat shock protein inhibition, and tumor-overexpressed protein-triggered drug release for ferroptotic therapy. Finally, the future expectations and challenges of ferroptotic tumor nanotherapeutics for clinical cancer therapy are highlighted.

Iron Overload, Oxidative Stress, and Ferroptosis in the Failing Heart and Liver

Iron accumulation is a key mediator of several cytotoxic mechanisms leading to the impairment of redox homeostasis and cellular death. Iron overload is often associated with haematological diseases which require regular blood transfusion/phlebotomy, and it represents a common complication in thalassaemic patients. Major damages predominantly occur in the liver and the heart, leading to a specific form of cell death recently named ferroptosis. Different from apoptosis, necrosis, and autophagy, ferroptosis is strictly dependent on iron and reactive oxygen species, with a dysregulation of mitochondrial structure/function. Susceptibility to ferroptosis is dependent on intracellular antioxidant capacity and varies according to the different cell types. Chemotherapy-induced cardiotoxicity has been proven to be mediated predominantly by iron accumulation and ferroptosis, whereas there is evidence about the role of ferritin in protecting cardiomyocytes from ferroptosis and consequent heart failure. Another paradigmatic organ for transfusion-associated complication due to iron overload is the liver, in which the role of ferroptosis is yet to be elucidated. Some studies report a role of ferroptosis in the initiation of hepatic inflammation processes while others provide evidence about an involvement in several pathologies including immune-related hepatitis and acute liver failure. In this manuscript, we aim to review the literature to address putative common features between the response to ferroptosis in the heart and liver. A better comprehension of (dys)similarities is pivotal for the development of future therapeutic strategies that can be designed to specifically target this type of cell death in an attempt to minimize iron-overload effects in specific organs.