Selenium reduction of ubiquinone via SQOR suppresses ferroptosis

Knockout of the sulfide: quinone oxidoreductase SQR reduces growth of HCT116 tumor xenograft

Colorectal cancer (CRC) exhibits significant diversity and heterogeneity, posing a requirement for novel therapeutic targets. Polysulfides are associated with CRC progression and immune evasion, but the underlying mechanisms are not fully understood. Sulfide: quinone oxidoreductase (SQR), a mitochondrial flavoprotein, catalyzes hydrogen sulfide (H2S) oxidation and polysulfides production. Herein, we explored its role in CRC pathogenesis and its potential as a therapeutic target. Our findings revealed that SQR knockout disrupted polysulfides homeostasis, diminished mitochondrial function, impaired cell proliferation, and triggered early apoptosis in HCT116 CRC cells. Moreover, the SQR knockout led to markedly reduced tumor sizes in mice models of colon xenografts. Although the transcription of glycolytic genes remained largely unchanged, metabolomic analysis demonstrated a reprogramming of glycolysis at the fructose-1,6-bisphosphate degradation step, catalyzed by aldolase A (ALDOA). Both Western blot analysis and enzymatic assays confirmed the decrease in ALDOA levels and activity. In conclusion, the study establishes the critical role of SQR in mitochondrial function and metabolic regulation in CRC, with its knockout leading to metabolic reprogramming and diminished tumor growth in HCT116 tumor xenografts. These insights lay a foundation for the development of SQR-targeted therapies for CRC.

Mechanism of ferroptosis in heart failure: The role of the RAGE/TLR4-JNK1/2 pathway in cardiomyocyte ferroptosis and intervention strategies

The ferroptosis of cardiomyocytes has been recognized as the core pathological mechanism of heart failure. During the evolution of cardiovascular diseases, the accumulation of angiotensin II and advanced glycation end products can lead to the excessive activation of the RAGE/TLR4-JNK1/2 pathway, which subsequently triggers ferritinophagy, clockophagy, and enhanced p53 activity, ultimately leading to cardiomyocyte ferroptosis. It is evident that deeply unraveling the specific mechanisms in this field and comprehensively evaluating potential drugs and therapeutic strategies targeting this pathway is crucial for improving the status of cardiomyocyte ferroptosis. However, our current understanding of this pathway's specific molecular biological mechanisms in the process of cardiomyocyte ferroptosis remains limited. In light of this, this paper first comprehensively reviews the historical context of ferroptosis research, compares the similarities and differences between ferroptosis and other standard modes of cell death, elucidates the core mechanisms of ferroptosis and its close connection with heart failure, aiming to establish a basic cognitive framework for readers on ferroptosis and its role in heart failure. Subsequently, the paper delves into the pivotal role of the RAGE/TLR4-JNK1/2 pathway in cardiomyocyte ferroptosis and its intricate molecular biological regulatory network. Furthermore, it systematically integrates various therapeutic approaches aimed at inhibiting RAGE, TLR4, and JNK1/2 activity to alleviate cardiomyocyte ferroptosis, encompassing RNA interference technology, gene knockout techniques, small molecule inhibitors, natural active ingredients, as well as traditional Chinese and Western medicines, with the ultimate goal of forging new avenues and strategies for the prevention and treatment of heart failure.

Comprehensive analysis of SQOR involvement in ferroptosis resistance of pancreatic ductal adenocarcinoma in hypoxic environments

Introduction

Pancreatic ductal adenocarcinoma (PDAC) exhibits higher hypoxia level than most solid tumors, and the presence of intratumoral hypoxia is associated with a poor prognosis. However, the identification of hypoxia levels based on pathological images, and the mechanisms regulating ferroptosis resistance, remain to be elucidated. The objective of this study was to construct a deep learning model to evaluate the hypoxia characteristics of PDAC and to explore the role of Sulfide quinone oxidoreductase (SQOR) in hypoxia-mediated ferroptosis resistance.

Methods

Multi-omics data were integrated to analyze the correlation between hypoxia score of PDAC, SQOR expression and prognosis, and ferroptosis resistance level. A deep learning model of Whole Slide Images (WSIs) were constructed to predict the hypoxia level of patients. In vitro hypoxia cell models, SQOR knockdown experiments and nude mouse xenograft models were used to verify the regulatory function of SQOR on ferroptosis.

Results

PDAC exhibited significantly higher hypoxia levels than normal tissues, correlating with reduced overall survival in patients. In slide level, our deep learning model can effectively identify PDAC hypoxia levels with good performance. SQOR was upregulated in tumor tissues and positively associated with both hypoxia score and ferroptosis resistance. SQOR promotes the malignant progression of PDAC in hypoxic environment by enhancing the resistance of tumor cells to ferroptosis. SQOR knockdown resulted in decreased cell viability, decreased migration ability and increased MDA level under hypoxic Ersatin induced conditions. Furthermore, SQOR inhibitor in combination with ferroptosis inducer has the potential to inhibit tumor growth in vivo in a synergistic manner.

Discussion

This study has established a hypoxia detection model of PDAC based on WSIs, providing a new tool for clinical evaluation. The study revealed a new mechanism of SQOR mediating ferroptosis resistance under hypoxia and provided a basis for targeted therapy.

Thiosulphate sulfurtransferase: Biological roles and therapeutic potential

Mitochondria are central to eukaryotic cell function, driving energy production, intermediary metabolism, and cellular homeostasis. Dysregulation of mitochondrial function often results in oxidative stress, a hallmark of numerous diseases, underscoring the critical need for maintaining mitochondrial integrity. Among mitochondrial enzymes, thiosulfate sulfurtransferase (TST) has emerged as a key regulator of sulfur metabolism, redox balance, and Fe-S protein maintenance. Beyond its well-known role in cyanide detoxification, TST facilitates hydrogen sulfide (H2S) metabolism by catalyzing the transfer of sulfur from persulfides (R-SSH) to thiosulfate (S2O32-), promoting H2S oxidation and preventing its toxic accumulation. Additionally, TST contributes to the thiol-dependent antioxidant system by regulating reactive sulfur species and sustaining mitochondrial functionality through its role in sulfide-driven bioenergetics. This review highlights the biochemical and therapeutic significance of TST in mitochondrial and cellular health, emphasizing its protective roles in diseases associated with oxidative stress and mitochondrial dysfunction. Dysregulation of TST has been implicated in diverse pathologies, including specific metabolic disorders, neurological diseases, cardiovascular conditions, kidney dysfunction, inflammatory bowel disease, and cancer. These associations underline TST's potential as a biomarker and therapeutic target. Therapeutic strategies to activate the TST pathway are explored, with a focus on sodium thiosulfate (STS), novel small molecule (Hit 2), and recombinant hTST protein. STS, an FDA-approved compound, has demonstrated antioxidant and anti-inflammatory effects across multiple preclinical models, mitigating oxidative damage and improving mitochondrial integrity. A slow-release oral formulation of STS is under development, offering promise for expanding its clinical applications. Small molecule activators like Hit 2 and hTST protein have shown efficacy in enhancing mitochondrial respiration and reducing oxidative stress, though both reagents need further in vitro and in vivo investigations. Despite promising advancements, TST-based therapies remain underexplored. Future research should focus on leveraging TST's interplay with pathways like NRF2 signaling, investigating its broader protective roles in cellular health, and developing targeted interventions. Enhancing TST activity represents an innovative therapeutic approach for addressing mitochondrial dysfunction, oxidative stress, and their associated pathologies, offering new hope for the treatment of diseases associated with mitochondrial dysfunction.

Phosphorylation of eIF2α suppresses the impairment of GSH/NADPH homeostasis and mitigates the activation of cell death pathways, including ferroptosis, during ER stress

eIF2α Phosphorylation helps maintain cellular homeostasis and overcome endoplasmic reticulum (ER) stress through transcriptional and translational reprogramming. This study aims to elucidate the transcriptional regulation of glutathione (GSH) and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) homeostasis through eIF2α phosphorylation and its impact on cell death during ER stress. eIF2α phosphorylation-deficient (A/A) cells exhibited decreased expression of multiple genes involved in GSH synthesis and NADPH production, leading to an exacerbated depletion of both cellular and mitochondrial GSH, as well as mitochondrial NADPH, during ER stress. Impaired GSH homeostasis resulted from deficient expression of ATF4 and/or its dependent factor, Nrf2, which are key transcription factors in the antioxidant response during ER stress. In contrast, the exacerbation of NADPH depletion may primarily be attributed to the dysregulated expression of mitochondrial serine-driven 1-carbon metabolism pathway genes, which are regulated by an unidentified eIF2α phosphorylation-dependent mechanism during ER stress. Moreover, the eIF2α phosphorylation-ATF4 axis was responsible for upregulation of ferroptosis-inhibiting genes and downregulation of ferroptosis-activating genes upon ER stress. Therefore, ER stress strongly induced ferroptosis of A/A cells, which was significantly inhibited by treatments with cell-permeable GSH and the ferroptosis inhibitor ferrostatin-1. ATF4 overexpression suppressed impairment of GSH homeostasis in A/A cells during ER stress by promoting expression of downstream target genes. Consequently, ATF4 overexpression mitigated ferroptosis as well as apoptosis of A/A cells during ER stress. Our findings underscore the importance of eIF2α phosphorylation in maintaining GSH/NADPH homeostasis and inhibiting ferroptosis through ATF4 and unidentified eIF2α phosphorylation-dependent target(s)-mediated transcriptional reprogramming during ER stress.

Deletion of Pyruvate Carboxylase in Tubular Epithelial Cell Promotes Renal Fibrosis by Regulating SQOR/cGAS/STING-Mediated Glycolysis

Renal fibrosis is a common pathway involved in the progression of various chronic kidney diseases to end-stage renal disease. Recent studies show that mitochondrial injury of renal tubular epithelial cells (RTECs) is a crucial pathological foundation for renal fibrosis. However, the underlying regulatory mechanisms remain unclear. Pyruvate carboxylase (PC) is a catalytic enzyme located within the mitochondria that is intricately linked with mitochondrial damage and metabolism. In the present study, the downregulation of PC in various fibrotic animal and human kidney samples is demonstrated. Renal proximal tubule-specific Pcx gene knockout mice (PcxcKO) has significant interstitial fibrosis compared to control mice, with heightened expression of extracellular matrix molecules. This is further demonstrated in a stable PC knock-out RTEC line. Mechanistically, PC deficiency reduces its interaction with sulfide:quinone oxidoreductase (SQOR), increasing the ubiquitination and degradation of SQOR. This leads to mitochondrial morphological and functional disruption, increased mtDNA release, activation of the cGAS-STING pathway, and elevated glycolysis levels, and ultimately, promotes renal fibrosis. This study investigates the molecular mechanisms through which PC deficiency induces mitochondrial injury and metabolic reprogramming in RTECs. This study provides a novel theoretical foundation and potential therapeutic targets for the pathogenesis and treatment of renal fibrosis.

Ferroptosis: when metabolism meets cell death

We present here a comprehensive update on recent advancements in the field of ferroptosis, with a particular emphasis on its metabolic underpinnings and physiological impacts. After briefly introducing landmark studies that have helped to shape the concept of ferroptosis as a distinct form of cell death, we critically evaluate the key metabolic determinants involved in its regulation. These include the metabolism of essential trace elements such as selenium and iron; amino acids such as cyst(e)ine, methionine, glutamine/glutamate, and tryptophan; and carbohydrates, covering glycolysis, the citric acid cycle, the electron transport chain, and the pentose phosphate pathway. We also delve into the mevalonate pathway and subsequent cholesterol biosynthesis, including intermediate metabolites like dimethylallyl pyrophosphate, squalene, coenzyme Q (CoQ), vitamin K, and 7-dehydrocholesterol, as well as fatty acid and phospholipid metabolism, including the biosynthesis and remodeling of ester and ether phospholipids and lipid peroxidation. Next, we highlight major ferroptosis surveillance systems, specifically the cyst(e)ine/glutathione/glutathione peroxidase 4 axis, the NAD(P)H/ferroptosis suppressor protein 1/CoQ/vitamin K system, and the guanosine triphosphate cyclohydrolase 1/tetrahydrobiopterin/dihydrofolate reductase axis. We also discuss other potential anti- and proferroptotic systems, including glutathione S-transferase P1, peroxiredoxin 6, dihydroorotate dehydrogenase, glycerol-3-phosphate dehydrogenase 2, vitamin K epoxide reductase complex subunit 1 like 1, nitric oxide, and acyl-CoA synthetase long-chain family member 4. Finally, we explore ferroptosis's physiological roles in aging, tumor suppression, and infection control, its pathological implications in tissue ischemia-reperfusion injury and neurodegeneration, and its potential therapeutic applications in cancer treatment. Existing drugs and compounds that may regulate ferroptosis in vivo are enumerated.

Methylseleninic Acid Elevating the Nrf2-GPX4 Axis Relieves Endothelial Dysfunction and Ferroptosis Induced by Arsenic Exposure

Chronic exposure to arsenic (As), a ubiquitous contaminant, poses deleterious health risks to humans, including cardiovascular disease. Recent studies have implicated ferroptosis, in which the essential micronutrient selenium (Se) plays a crucial role, in several As-induced pathological processes. However, whether Se can counteract As-induced endothelial dysfunction through ferroptosis remains unclear. Herein, methylseleninic acid (MSA), a methylselenium metabolite, was used as a Se supplement to investigate the underlying effect and mechanism of Se in As-induced endothelial dysfunction involving ferroptosis in vivo and in vitro. As exposure induced endothelial dysfunction in mice, as indicated by increased aortic permeability, increased number of circulating endothelial cells, and endothelial mitochondria exhibiting ferroptosis-related alterations. Additionally, As induced ferroptosis-related cell death in mouse aortic endothelial cells, accompanied by impaired redox homeostasis, relatively low Se status, and decreased expressions of selenoproteome, including GPX4. Notably, these were attenuated by MSA via activation of Nrf2 and upregulation of three GPX4 isoforms, which were further abrogated by the Nrf2 antagonist ML385. Finally, MSA exhibited ameliorative effects on endothelial ferroptosis and dysfunction in the aortas of As-exposed mice. These results demonstrate that As causes endothelial ferroptosis and dysfunction by affecting the Se-Nrf2/GPX4 axis, which can be relieved by MSA. This study provides novel evidence implicating Se in As-induced endothelial dysfunction by mitigating ferroptosis.

Dietary and nutritional interventions for human diseases: their modulatory effects on ferroptosis

A balanced diet is essential for maintaining human health. Increasing evidence suggests that dietary and nutritional interventions contribute to disease management and are associated with reduced healthcare costs and economic burden. Ferroptosis, a novel type of regulated cell death (RCD) driven by lipid peroxidation, has been shown to be involved in various pathological conditions, including diabetes, ischemia/reperfusion (I/R) injury, inflammation-related diseases, and cancer. Therefore, specifically targeting the uncontrolled ferroptosis process may offer new therapeutic opportunities. Of note, certain interventions, such as small-molecule compounds, natural products, herbal medicines, and non-pharmacological approaches, have been reported to prevent and treat multiple human diseases by reversing the dysregulation of ferroptosis. In this review, we present the key molecular mechanisms that regulate ferroptosis. Importantly, interventions targeting ferroptosis are summarized from the perspective of dietary patterns, food and nutrients. By understanding these advances, innovative ideas can be provided for individualized dietary interventions and treatment strategies.

Adapt or Perish: Efficient Selenocysteine Insertion Is Critical for Metastasizing Cancer Cells

During metastasis, cancer cells detach from the primary tumor, circulate through the bloodstream, and establish themselves at distant sites, facing increased levels of reactive oxygen species that act as significant barriers to metastatic progression. Adapting to and surviving in these high reactive oxygen species environments are thus crucial for successful metastasis. A recent study by Nease and colleagues identified FTSJ1 as the methyltransferase responsible for methylation of the U34 position wobble uridine modification of selenocysteine (Sec) tRNA. This methylation enables efficient Sec insertion, leading to increased translation of a subset of stress-responsive selenoproteins that combat the oxidative stress encountered during the metastatic process. This study establishes FTSJ1 as an essential redox regulator during metastasis through its role in enhancing Sec insertion efficiency and introduces a potential therapeutic strategy against metastasis.

Advancements in programmed cell death research in antitumor therapy: a comprehensive overview

Cell death is a normal physiological process within cells that involves multiple pathways, such as normal DNA damage, cell cycle arrest, and programmed cell death (PCD). Cell death has been a hot spot of research in tumor-related fields, especially programmed cell death, which is a key form of cell death and is classified into different types according to the mechanism of occurrence, such as apoptosis, autophagy, necroptosis, pyroptosis, ferroptosis, and disulfidptosis. Given the important role of PCD in maintaining tissue homeostasis and inhibiting tumorigenesis and development, more and more basic and clinical studies are devoted to revealing its potential application in anti-tumor strategies. The purpose of this review is to systematically review the regulatory mechanisms of PCD and to summarize the latest research progress of anti-tumor treatment strategies based on PCD.

Ferroptosis Transcriptional Regulation and Prognostic Impact in Medulloblastoma Subtypes Revealed by RNA-Seq

Medulloblastoma (MB) is the most common malignant brain tumor in children, typically arising during infancy and childhood. Despite multimodal therapies achieving a response rate of 70% in children older than 3 years, treatment remains challenging. Ferroptosis, a form of regulated cell death, can be induced in medulloblastoma cells in vitro using erastin or RSL3. Using two independent medulloblastoma RNA-sequencing cohorts (MB-PBTA and MTAB-10767), we investigated the expression of ferroptosis-related molecules through multiple approaches, including Weighted Gene Co-Expression Network Analysis (WGCNA), molecular subtype stratification, protein-protein interaction (PPI) networks, and univariable and multivariable overall survival analyses. A prognostic expression score was computed based on a cross-validated ferroptosis signature. In training and validation cohorts, the regulation of the ferroptosis transcriptional program distinguished the four molecular subtypes of medulloblastoma. WGCNA identified nine gene modules in the MB tumor transcriptome; five correlated with molecular subtypes, implicating pathways related to oxidative stress, hypoxia, and trans-synaptic signaling. One module, associated with disease recurrence, included epigenetic regulators and nucleosome organizers. Univariable survival analyses identified a 45-gene ferroptosis prognostic signature associated with nutrient sensing, cysteine and methionine metabolism, and trans-sulfuration within a one-carbon metabolism. The top ten unfavorable ferroptosis genes included CCT3, SNX5, SQOR, G3BP1, CARS1, SLC39A14, FAM98A, FXR1, TFAP2C, and ATF4. Patients with a high ferroptosis score showed a worse prognosis, particularly in the G3 and SHH subtypes. The PPI network highlighted IL6 and CBS as unfavorable hub genes. In a multivariable overall survival model, which included gender, age, and the molecular subtype classification, the ferroptosis expression score was validated as an independent adverse prognostic marker (hazard ratio: 5.8; p-value = 1.04 × 10-9). This study demonstrates that the regulation of the ferroptosis transcriptional program is linked to medulloblastoma molecular subtypes and patient prognosis. A cross-validated ferroptosis signature was identified in two independent RNA-sequencing cohorts, and the ferroptosis score was confirmed as an independent and adverse prognostic factor in medulloblastoma.

Ferroptosis: A Targetable Vulnerability for Melanoma Treatment

Melanoma is a devastating form of skin cancer characterized by a high mutational burden, limited treatment success, and dismal prognosis. Although immunotherapy and targeted therapies have significantly revolutionized melanoma treatment, the majority of patients fail to achieve durable responses, highlighting the urgent need for novel therapeutic strategies. Ferroptosis, an iron-dependent form of regulated cell death driven by the overwhelming accumulation of lipid peroxides, has emerged as a promising therapeutic approach in preclinical melanoma models. A deeper understanding of the ferroptosis landscape in melanoma based on its biology characteristics, including phenotypic plasticity, metabolic state, genomic alterations, and epigenetic changes, as well as the complex role and mechanisms of ferroptosis in immune cells could provide a foundation for developing effective treatments. In this review, we outline the molecular mechanisms of ferroptosis, decipher the role of melanoma biology in ferroptosis regulation, reveal the therapeutic potential of ferroptosis in melanoma, and discuss the pressing questions that should guide future investigations into ferroptosis in melanoma.

Selenium: 48-year journey of global clinical trials

Selenium, an essential trace mineral for health, has seen a rise in clinical trials over the past nearly 5 decades. Our aim here is to provide a comprehensive and concise overview of selenium clinical trials from 1976 to 2023. Overall, the evolution of selenium clinical trials over 48 years has advanced through phases of emergence, prosperity, and either stability or transition. The USA plays pivotal roles in establishing large research clusters and fostering strong collaborative ties of selenium clinical trials. Low-selenium levels are noted in a higher proportion of selenium observational trials, while selenium intervention trials are delineated by nine key functional classifications. The emphasis in intervention trials is that selenium product development should be on conducting clinical trials in diseases with higher efficacy, such as those involving antioxidant and endocrine and metabolic disease. Moreover, inorganic forms such as sodium selenite and semi-organic forms like selenized yeast were recognized as primary sources of selenium, while nano-selenium has emerged as a new selenium source in clinical treatments. Selenium is mainly consumed through tablets and oral administration, with a recommended upper limit of 200 µg per day for managing most diseases. In addition, genes encoding selenoproteins or factors of relevance for selenium metabolism, inflammation, and immunity, which have a higher number of records in all trials, are poised to steer future investigations into functional mechanisms of selenium. We believe this review will offer fresh perspectives on selenium clinical trials and identify potential avenues for future selenium research.

Circulating Glutathione Peroxidase-3 in Elderly-Association with Renal Function, Cardiovascular Mortality, and Impact of Selenium and Coenzyme Q10 Supplementation

Low-selenium status was associated with impaired renal function, which improved after selenium and coenzyme Q10 supplementation in an RCT. Here, we evaluated serum glutathione peroxidase-3 (GPx3) and its relation to serum selenium, selenoprotein P (SELENOP), renal function, mortality, and the impact of supplementation, which are all important, especially in elderly individuals. In total, 383 study participants (197 receiving selenium yeast and coenzyme Q10 and 186 on a placebo) were evaluated. We applied benchmark dose modelling to determine GPx3 saturation, ANCOVA, Kaplan-Meier, and multivariate Cox proportional regression analyses for mortality evaluations. Selenium and GPx3 activity were modestly correlated. In comparison with SELENOP, GPx3 levelled off at a much lower value, 100 vs. 150 µg Se/L. GPx3 was associated with renal function, but not SELENOP. Supplementation increased glomerular function by ≈23% with an increase in GPx3. Being low in GPx3 displayed twice the risks of mortality in both placebos and active treatments. At serum selenium <100 µg/L, GPx3 activity was dependent on both selenium status and renal function. As renal function is reduced in the elderly, GPx3 is not an appropriate marker of selenium status. Low GPx3 was associated with an increased risk of mortality dependent of selenium status and independent of renal function.

PRDX6 dictates ferroptosis sensitivity by directing cellular selenium utilization

Selenium-dependent glutathione peroxidase 4 (GPX4) is the guardian of ferroptosis, preventing unrestrained (phospho)lipid peroxidation by reducing phospholipid hydroperoxides (PLOOH). However, the contribution of other phospholipid peroxidases in ferroptosis protection remains unclear. We show that cells lacking GPX4 still exhibit substantial PLOOH-reducing capacity, suggesting a contribution of alternative PLOOH peroxidases. By scrutinizing potential candidates, we found that although overexpression of peroxiredoxin 6 (PRDX6), a thiol-specific antioxidant enzyme with reported PLOOH-reducing activity, failed to prevent ferroptosis, its genetic loss sensitizes cancer cells to ferroptosis. Mechanistically, we uncover that PRDX6, beyond its known peroxidase activity, acts as a selenium-acceptor protein, facilitating intracellular selenium utilization and efficient selenium incorporation into selenoproteins, including GPX4. Its physiological significance was demonstrated by reduced GPX4 expression in Prdx6-deficient mouse brains and increased sensitivity to ferroptosis in PRDX6-deficient tumor xenografts in mice. Our study highlights PRDX6 as a critical player in directing cellular selenium utilization and dictating ferroptosis sensitivity.

Inhibition of Selenoprotein I promotes ferroptosis and reverses resistance to platinum chemotherapy by impairing Akt phosphorylation in ovarian cancer

Ovarian cancer (OV) ranks among the deadliest gynecological cancer, known for its high risk of relapse and metastasis, and a general resistance to conventional platinum-based chemotherapy. Selenoprotein I (SELENOI) is a crucial mediator implicated in human hereditary spastic paraplegia. However, its role in human tumors remains poorly elucidated. Here, we comprehensively analyzed SELENOI expression patterns, functions, and clinical implications across various malignancies through the integration of bulk transcriptomics, cancer databases, and in vitro and in vivo experiments. Pan-cancer analysis indicated upregulated SELENOI expression across various cancers, correlating with augmented malignancy, suppressed tumor immunity and poor prognosis. Knockdown of SELENOI caused G0/G1-phase cell cycle arrest and diminished aggressive cancer phenotypes in OV cells. Moreover, SELENOI inhibition augments ferroptosis and reverses the cisplatin resistance in OV cells by modulating Akt phosphorylation. Conversely, overexpression of SELENOI in OV cells enhanced therapeutic sensitivity to cisplatin by upregulating Akt phosphorylation. Importantly, in vivo studies demonstrated that SELENOI inhibition suppressed ovarian tumor growth and enhanced cisplatin's anticancer effects. These findings highlight the significant role of SELENOI in OV by modulating ferroptosis and chemotherapy resistance. Targeting SELENOI represents a promising therapeutic approach to promote the efficacy of platinum-based chemotherapy in OV, particularly in cases of resistance.

Exploiting ferroptosis vulnerabilities in cancer

Ferroptosis is a distinct lipid peroxidation-dependent form of necrotic cell death. This process has been increasingly contemplated as a new target for cancer therapy because of an intrinsic or acquired ferroptosis vulnerability in difficult-to-treat cancers and tumour microenvironments. Here we review recent advances in our understanding of the molecular mechanisms that underlie ferroptosis and highlight available tools for the modulation of ferroptosis sensitivity in cancer cells and communication with immune cells within the tumour microenvironment. We further discuss how these new insights into ferroptosis-activating pathways can become new armouries in the fight against cancer.

Immunometabolism of ferroptosis in the tumor microenvironment

Ferroptosis is an iron-dependent form of cell death that results from excess lipid peroxidation in cellular membranes. Within the last decade, physiological and pathological roles for ferroptosis have been uncovered in autoimmune diseases, inflammatory conditions, infection, and cancer biology. Excitingly, cancer cell metabolism may be targeted to induce death by ferroptosis in cancers that are resistant to other forms of cell death. Ferroptosis sensitivity is regulated by oxidative stress, lipid metabolism, and iron metabolism, which are all influenced by the tumor microenvironment (TME). Whereas some cancer cell types have been shown to adapt to these stressors, it is not clear how immune cells regulate their sensitivities to ferroptosis. In this review, we discuss the mechanisms of ferroptosis sensitivity in different immune cell subsets, how ferroptosis influences which immune cells infiltrate the TME, and how these interactions can determine epithelial-to-mesenchymal transition (EMT) and metastasis. While much focus has been placed on inducing ferroptosis in cancer cells, these are important considerations for how ferroptosis-modulating strategies impact anti-tumor immunity. From this perspective, we also discuss some promising immunotherapies in the field of ferroptosis and the challenges associated with targeting ferroptosis in specific immune cell populations.

Nanomedicines Targeting Ferroptosis to Treat Stress-Related Diseases

Ferroptosis, a unique form of regulated cell death driven by iron-dependent lethal lipid peroxidation, is implicated in various stress-related diseases like neurodegeneration, vasculopathy, and metabolic disturbance. Stress-related diseases encompass widespread medical disorders that are influenced or exacerbated by stress. These stressors can manifest in various organ or tissue systems and have significant implications for human overall health. Understanding ferroptosis in these diseases offers insights for therapeutic strategies targeting relevant pathways. This review explores ferroptosis mechanisms, its role in pathophysiology, its connection to stress-related diseases, and the potential of ferroptosis-targeted nanomedicines in treating conditions. This monograph also delves into the engineering of ferroptosis-targeted nanomedicines for tackling stress-related diseases, including cancer, cardia-cerebrovascular, neurodegenerative, metabolic and inflammatory diseases. Anyhow, nanotherapy targeting ferroptosis holds promise by both promoting and suppressing ferroptosis for managing stress-related diseases.

The Ubiquinone-Ubiquinol Redox Cycle and Its Clinical Consequences: An Overview

Coenzyme Q10 (CoQ10) plays a key role in many aspects of cellular metabolism. For CoQ10 to function normally, continual interconversion between its oxidised (ubiquinone) and reduced (ubiquinol) forms is required. Given the central importance of this ubiquinone-ubiquinol redox cycle, this article reviews what is currently known about this process and the implications for clinical practice. In mitochondria, ubiquinone is reduced to ubiquinol by Complex I or II, Complex III (the Q cycle) re-oxidises ubiquinol to ubiquinone, and extra-mitochondrial oxidoreductase enzymes participate in the ubiquinone-ubiquinol redox cycle. In clinical terms, the outcome of deficiencies in various components associated with the ubiquinone-ubiquinol redox cycle is reviewed, with a particular focus on the potential clinical benefits of CoQ10 and selenium co-supplementation.

Selenium-Enriched E. coli Bacteria Mitigate the Age-Associated Degeneration of Cholinergic Neurons in C. elegans

Selenium (Se) is an essential trace element for humans and animals, but high-dose supplementation with Se compounds, most notably selenite, may exert cytotoxic and other adverse effects. On the other hand, bacteria, including Escherichia coli (E. coli), are capable of reducing selenite to red elemental Se that may serve as a safer Se source. Here, we examined how a diet of Se-enriched E. coli bacteria affected vital parameters and age-associated neurodegeneration in the model organism Caenorhabditis elegans (C. elegans). The growth of E. coli OP50 for 48 h in medium supplemented with 1 mM sodium selenite resulted in reddening of the bacterial culture, accompanied by Se accumulation in the bacteria. Compared to nematodes supplied with the standard E. coli OP50 diet, the worms fed on Se-enriched bacteria were smaller and slimmer, even though their food intake was not diminished. Nevertheless, given the choice, the nematodes preferred the standard diet. The fecundity of the worms was not affected by the Se-enriched bacteria, even though the production of progeny was somewhat delayed. The levels of the Se-binding protein SEMO-1, which serves as a Se buffer in C. elegans, were elevated in the group fed on Se-enriched bacteria. The occurrence of knots and ruptures within the axons of cholinergic neurons was lowered in aged nematodes provided with Se-enriched bacteria. In conclusion, C. elegans fed on Se-enriched E. coli showed less age-associated neurodegeneration, as compared to nematodes supplied with the standard diet.