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Ferroptosis is a type of programmed cell death characterized by accumulation of free iron, reactive oxygen species generation and lipid peroxidation and is distinct from other types of regulated cell deaths such as apoptosis, necrosis and autophagy. Ferroptosis is distinct from other programmed cell deaths for its iron dependence and its significant role in tumor suppression. Therefore, harnessing ferroptosis may offer promising avenues for cancer therapy. In the present review, the different pathways that lead to ferroptosis, the genes and transcription factors involved in both iron and lipid metabolism, as well as the impact of small‑molecule alterations on the regulation of ferroptotic cell death, were discussed. Furthermore, the emergence of combination therapies with ferroptosis‑inducing molecules that overcome resistance to conventional chemotherapy, particularly in solid tumors, were highlighted. Show less

A new generation of backbone-functionalized NHC–gold( i ) complexes reveals ferroptosis through comprehensive mechanistic and biological investigation. Show less

Ferroptosis is a form of iron-mediated regulated cell death driven by lipid peroxidation (LPO). It has not only further improved our understanding of the cell death mechanism but also shown enormous potential in therapeutic applications. While the precise subcellular itinerary of ferroptotic cell death remains a subject of ongoing debate, radical-trapping antioxidants (RTAs) are widely recognized as efficient antiferroptotic agents due to their ability to interrupt LPO chain propagation. Here, we highlight recent pioneering works in the field, showing how probes derived from RTAs serve as powerful chemical tools for resolving the mechanism of ferroptosis across multiple cellular compartments. Show less

Ligands containing a dearomatized ligand motif are often employed to stabilize transition metal complexes and may be employed in catalytic transformations. While complexes containing one dearomatized structural feature are common, dual dearomatized systems are seldom encountered. In this article, we describe the synthesis of various iron complexes based upon a macrocyclic PNPN ligand. Synthetic entry to the dual dearomatized ligand (PNPN*) can be achieved upon deprotonation of the Fe dibromide complex with base in the presence of π-acidic ligands. The electronic structure of these complexes was examined by NMR- and ⁵⁷Fe Mössbauer spectroscopy and computationally modeled. Reactivity studies regarding ligand substitution of the π-acidic ligands and protonation of the PNPN* scaffold are described. Show less

Mononuclear nonheme iron(III)-peroxo complexes bearing N-tetramethylated cyclam (n-TMC) ligands, [Fe^III(O₂)(n-TMC)]⁺ (n = 12, 13, and 14), have recently shown highly intriguing reactivities in various oxidation reactions, such as the cis-dihydroxylation and C-H functionalization reactions, which were previously associated only with high-valent iron-oxo intermediates in heme and nonheme iron enzymes. Herein, we extend our study to report [Fe^III(O₂)(n-TMC)]⁺ mediated N-demethylation of N,N-dimethylanilines (DMAs), another reaction that was previously associated only with high-valent iron-oxo cores. Most importantly, we provide definitive evidence of the occurrence of electron transfer from DMAs to [Fe^III(O₂)(n-TMC)]⁺, thereby establishing an electron-transfer (ET) pathway for the N-demethylation reaction. Investigation of the ET reactivity of [Fe^III(O₂)(n-TMC)]⁺ in light of the Marcus theory of ET, and a comparison of the N-demethylation and the ET rate constants corroborate a mechanism, whereby N-demethylation of DMAs by [Fe^III(O₂)(n-TMC)]⁺ proceeds via the peroxide O-O bond cleavage of [Fe^III(O₂)(n-TMC)]⁺ to form a transient [Fe^IV(O^2-)(O^• -)(n-TMC)]⁺ species, which undergoes a proton-coupled electron-transfer (PCET) or an uncoupled electron transfer-proton transfer (ET/PT) in the presence of DMAs. Saturation kinetics support the rate-determining formation of [Fe^IV(O^2-)(O^• -)(n-TMC)]⁺ in a pre-equilibrium step with the same values of the O-O bond cleavage rate constants irrespective of the substrates, such as DMAs and one-electron oxidants. The present study corroborates that mononuclear nonheme iron(III)-peroxo cores are not mere pass-through points en route to high-valent metal-oxo intermediates, but they can play an important role in the diverse oxidation reactions of Rieske oxygenases, such as in the N-demethylation reaction. Show less

Ferroptosis suppressor protein 1 (FSP1) has emerged as a critical regulator of ferroptosis, an iron-dependent form of programmed cell death with significant therapeutic potential in cancer treatment. Despite rapidly expanding research, current knowledge on FSP1 remains fragmented across various tumor types and experimental contexts. The aim of this review is to systematically integrate the latest evidence regarding the molecular structure, biological functions, and regulatory mechanisms controlling FSP1 expression, emphasizing its involvement in tumor progression and resistance to therapy. Readers can expect comprehensive coverage of FSP1's structural characteristics, enzymatic roles, transcriptional and post-transcriptional regulation, and its pathological significance in hepatocellular carcinoma, colorectal cancer, pancreatic cancer, gastric cancer, breast cancer, lung cancer, and leukemia. We further evaluate emerging therapeutic strategies targeting FSP1 aimed at overcoming resistance and improving clinical outcomes. Relevant studies were systematically identified by searching PubMed, Web of Science, and Embase databases, focusing particularly on the recent and impactful literature to guide future research directions. Show less

Serpentinizing hydrothermal vents are likely sites for the origin of metabolism because they produce H2 as a source of electrons for CO2 reduction while depositing zero-valent iron, cobalt, and nickel as catalysts for organic reactions. Recent work has shown that solid-state nickel can catalyze the H2-dependent reduction of CO2 to various organic acids and their reductive amination with H2 and NH3 to biological amino acids under the conditions of H2-producing hydrothermal vents and that amino acid synthesis from NH3, H2, and 2-oxoacids is facile in the presence of Ni0. Such reactions suggest a metallic origin of metabolism during early biochemical evolution because single metals replace the function of over 130 enzymatic reactions at the core of metabolism in microbes that use the acetyl-CoA pathway of CO2 fixation. Yet solid-state catalysts tether primordial amino synthesis to a mineral surface. Many studies have shown that pyridoxal catalyzes transamination reactions without enzymes. Here we show that pyridoxamine, the NH2-transferring intermediate in pyridoxal-dependent transamination reactions, is generated from pyridoxal by reaction with NH3 (as little as 5 mm) and H2 (5 bar) on Ni0 as catalyst at pH 11 and 80 °C within hours. These conditions correspond to those in hydrothermal vents undergoing active serpentinization. The results indicate that at the origin of metabolism, pyridoxamine provided a soluble, organic amino donor for aqueous amino acid synthesis, mediating an evolutionary transition from NH3-dependent amino acid synthesis on inorganic surfaces to pyridoxamine-dependent organic reactions in the aqueous phase. Show less

Conditions that led to the synthesis of iron-sulfur clusters coordinated to tripeptides with a single thiolate ligand were investigated by UV-vis, NMR, EPR, and Mössbauer spectroscopies and by electrochemistry. Increasing concentrations of hydrosulfide correlated with the formation of higher nuclearity iron-sulfur clusters from mononuclear to [2Fe-2S] to [4Fe-4S] and finally to a putative, nitrogenase-like [6Fe-9S] complex. Increased nuclearity was also associated with decreased dynamics and increased stability. The synthesis of higher nuclearity iron-sulfur clusters is compatible with shallow, alkaline bodies of water on the surface of the early Earth, although other niche environments are possible. Because of the plasticity of such complexes, the type of iron-sulfur cluster formed on the prebiotic Earth would have been greatly influenced by the chemical environment and the thiolate containing scaffold. The discovery that all the major classes of iron-sulfur clusters easily form under prebiotically reasonable conditions broadens the chemistry accessible to protometabolic systems. Show less

Ferredoxins (FDXs) are evolutionarily conserved iron-sulfur (Fe-S) proteins that serve as master regulators of mitochondrial redox homeostasis, governing critical processes including electron transfer, energy metabolism, Fe-S cluster biogenesis, and steroidogenesis. In humans, the mitochondrial isoforms FDX1 and FDX2 exhibit specialized yet complementary functions: FDX1 directs steroidogenesis, protein lipoylation, and copper redox cycling, while FDX2 is a core factor in Fe-S cluster assembly. Crucially, dysregulation of these proteins disrupts mitochondrial integrity, impairs redox balance, and activates multiple programmed cell death (PCD) pathways such as cuproptosis, ferroptosis, apoptosis, and autophagic cell death. This review systematically analyzes their isoform-specific roles in mitochondrial electron transport, Fe-S cluster dynamics, metabolic regulation, and summarizes major advances in understanding how FDX1 and FDX2 orchestrate mitochondrial-PCD crosstalk. The work further examines their critical functions in PCD execution, including FDX1-mediated cuproptosis through Cu+-dependent aggregation of lipoylated proteins and FDX2-deficiency-driven ferroptosis via Fe-S cluster collapse and iron overload. Disease mechanisms across multiple pathologies, including cancer, neurodegeneration, cardiovascular disease, endocrine disorders, and genetic syndromes, are explored, highlighting links to FDX dysfunction, with emerging therapeutic strategies targeting FDXs also addressed. By elucidating the synergistic roles of FDX1 and FDX2 as metabolic-death gatekeepers, this review establishes a foundation for developing isoform-targeted therapies against diverse pathologies. Show less

Ubellacker and Dixon summarize the latest discoveries on ferroptosis in cancer, covering the molecular and cellular pathways underlying sensitivity and resistance to this type of cell death, as well as potential translational applications in cancer therapeutics. Show less

Ferroptosis, the non-apoptotic, iron-dependent form of cell death is an unavoidable outcome and byproduct of cellular metabolism. Reactive oxygen species generation during metabolic activities transcends to Fe2+-induced lipid peroxidation, leading to ferroptosis. Cancer cells being highly metabolic are more prone to ferroptosis. However, their neoplastic nature enables them to bypass ferroptosis and become ferroptosis-resistant. The capability of cancer cells to reprogram its metabolic activities is one of its finest abilities to abort oxidative damage, and hence ferroptosis. Moreover, the reprogrammed metabolism of cancer cells, also associates with the radical trapping antioxidant systems to enhance the scavenging of ferroptosis and thereby tumor progression. Additionally, the TME, which is an inevitable part and regulator of carcinogenesis, presents an intricate cooperation with tumor metabolism to build an immuno-metabolic environment to regulate the sustenance of cell proliferation and survival. This review focuses on the current understanding of ferroptosis in carcinogenesis and its resistance acquired by cancer cells via several modulators including the radical trapping antioxidant systems, the reprogrammed metabolism, the TME, and intertwined role of cancer metabolism and tumor immunity. The reprogrammed metabolism section further comprehends the functional role of lipids, iron and glucose metabolism against ferroptosis defense separately. The affiliation of TME in ferroptosis regulation is further sectioned with reference to different immune cells present within the TME such as tumor-associated macrophages, tumor-infiltrating neutrophils, myeloid-derived suppressor cells, T-cells, natural killer cells, dendritic cells, and B-cells, modifying the TME in both pro and anti-tumorigenic manner. Subsequently, this review also discusses the convergence of immuno-metabolic environment in ferroptosis regulation, and eventually brings up research gaps in this context providing consequential and significant questions to explore for better understanding of the immuno-metabolic environment's role in driving ferroptosis resistance for anti-cancer treatment progress. Show less

Ferroptosis is a non-apoptotic type of cell death that is induced by uncontrolled iron-dependent phospholipid peroxidation and has important roles in disease. This Expert Recommendation article summarizes ferroptosis regulation and mechanisms and provides recommendations to increase the reproducibility and robustness of ferroptosis research. Show less

Lipid peroxidation stands as a prominent hallmark and a prerequisite for the onset of ferroptosis. Lipid metabolism holds a pivotal role in regulating this process, forming the metabolic foundation for cellular sensitivity to ferroptosis. Studies in lipid metabolomics reveal that the activation of Polyunsaturated fatty acids (PUFA), specifically arachidonic acid and adrenoic acid (AdA), mediated by acyl-CoA synthetase long-chain family member 4 (ACSL4), represents a critical step in generating lipid peroxidation substrates. The expression level or enzymatic activity of ACSL4 emerges as a potential indicator of cellular susceptibility to ferroptosis. Additionally, other members of the ACSL family can indirectly influence the occurrence of ferroptosis by modifying the fatty acid composition of the cell membrane. Given the high expression of ACSL4 in various human tumors, targeting lipid peroxidation with ACSL4 as the focal point may pave a new path in tumor therapy. This article provides a brief overview of the primary structure and function of ACSL4, its role in lipid peroxidation, and summarizes the current advancements in drug development targeting ACSL4 and lipid peroxidation. Show less

FSP1 is a key suppressor of lipid peroxidation and ferroptosis, yet it is largely dispensable in standard cell culture models. Two new studies now show that FSP1 becomes essential for tumour growth in vivo, establishing it as a context-specific cancer vulnerability and highlighting the therapeutic potential of FSP1 inhibition. Show less

Abstract Cancer cells rely heavily on de novo pyrimidine synthesis. Inhibiting pyrimidine metabolism directly suppresses tumor growth and fosters immune activation within the tumor microenvironment. Dihydroorotate dehydrogenase (DHODH) is a key enzyme in the de novo pyrimidine synthesis pathway. Inhibiting DHODH can reverse immune suppression and trigger a mild innate immune response. However, the impact of DHODH inhibition on natural killer (NK) cells remains to be explored. In this study, we found that DHODH inhibition promoted NK cell infiltration into tumors efficiently. Mechanistically, DHODH suppression induced mitochondrial oxidative stress, leading to mitochondrial DNA (mtDNA) release into the cytoplasm through voltage-dependent anion channel (VDAC) oligomerization and caspase-3 activation. This subsequently activated the stimulator of interferon gene (STING) pathway, triggered ferroptosis, and induced gasdermin E (GSDME) mediated pyroptosis in cancer cells. These changes collectively facilitated NK cell recruitment. Furthermore, infiltrated NK cells enhanced GSDME-dependent pyroptosis in tumor cells through granzyme release, establishing a positive feedback loop that amplified anti-tumor immunity. Additionally, we developed EA6, a novel DHODH inhibitor that is more effective at promoting NK cell infiltration. In summary, this study reveals that targeting pyrimidine metabolism activates a novel mechanism involving pyroptosis-ferroptosis crosstalk and STING pathway activation to enhance NK cell-mediated immunity. These finding opens new avenues for enhancing the efficacy of targeted nucleotide metabolism in cancer therapy. Show less

Electron transfer coupled to redox chemistry is at the heart of metabolism. The proteins responsible for moving electrons (protein electron carriers) must have emerged at the origin of life. The small iron-sulfur-binding bacterial ferredoxins were likely among these first proteins. Embedded within the ferredoxin sequence and structure is a symmetry that points to an ancient gene duplication event. Little is understood about the nature of ferredoxins prior to this duplication event or what environmental factors may have driven the selection for more complex forms. The deep-time molecular history of ferredoxins goes back billions of years and cannot be reconstructed by phylogenetic analyses based on amino acid sequences. Here, we use structure-guided protein design to model a fossil half-ferredoxin stage in the evolution of this fold, the semidoxins, and their symmetric full-length counterparts, the symdoxins. Semidoxin designs homodimerize, exhibiting structural, thermodynamic, and electrochemical behaviors in most cases identical to cognate symdoxins. However, the semi- and symdoxin fossil stages behave differently when incorporated into an in vivo electron transfer complementation assay. Both can support bacterial growth dependent on protein expression. Growth rates of bacteria expressing the semidoxins are much more sensitive to oxygen than those of bacteria expressing symdoxins. Motivated by the in vivo functionality of designed semidoxins, we identified putative naturally occurring semidoxins in extant anaerobic microorganisms. This is consistent with the observed in vivo oxygen sensitivity of the semidoxin designs. One natural semidoxin is shown to be folded and redox active. However, it exists as a mixture of monomers and dimers, suggesting a potential connection between semidoxins and even simpler single iron-sulfur cluster-binding peptides. Show less

Ferroptosis is an iron-dependent form of regulated cell death driven by lipid peroxidation. Since the identification of dihydroorotate dehydrogenase (DHODH) as a mitochondrial suppressor of ferroptosis in 2021, increasing evidence has highlighted its role in linking nucleotide metabolism, redox regulation, and tumor progression. We conducted a comprehensive review of publications on DHODH, ferroptosis, and cancer. Relevant studies were analyzed to synthesize mechanistic insights, translational implications, and therapeutic perspectives. DHODH, a flavin-dependent mitochondrial enzyme catalyzing the oxidation of dihydroorotate to orotate, integrates pyrimidine biosynthesis with electron transport chain activity. Beyond its canonical metabolic role, DHODH regenerates ubiquinol (CoQ10H2) to suppress mitochondrial lipid peroxidation and ferroptosis. Elevated DHODH expression in colorectal, hepatocellular, breast, renal, and brain cancers correlates with poor prognosis, therapy resistance, and immune evasion. Pharmacological inhibition of DHODH disrupts pyrimidine synthesis and redox defense, sensitizing GPX4-low tumors to ferroptosis. Preclinical studies demonstrate synergy between DHODH inhibitors and chemotherapy, radiotherapy, or immune checkpoint blockade. Nanoparticle-based delivery systems enhance therapeutic efficacy by simultaneously targeting multiple ferroptosis defense arms while reducing toxicity. DHODH serves as both a metabolic and redox checkpoint in cancer, linking ferroptosis suppression to proliferation and immune escape. Targeting DHODH offers a promising strategy to dismantle cancer resilience, particularly in combination with ferroptosis inducers and immunotherapies. Future research should focus on biomarker-guided stratification, nanomedicine platforms, and clinical translation of DHODH inhibitors. Show less

Molecular hydrogen is the electron donor for the ancient exergonic reductive acetyl-coenzyme A pathway (acetyl-CoA pathway), which is used by hydrogenotrophic methanogenic archaea. How the presence of iron-sulfides influenced the acetyl-CoA pathway under primordial early Earth geochemistry is still poorly understood. Here we show that the iron-sulfides mackinawite (FeS) and greigite (Fe3S4), which formed in chemical garden experiments simulating geochemical conditions of the early Archaean eon (4.0-3.6 billion years ago), produce abiotic H2 in sufficient quantities to support hydrogenotrophic growth of the hyperthermophilic methanogen Methanocaldococcus jannaschii. Abiotic H2 from iron-sulfide formation promoted CO2 fixation and methanogenesis and induced overexpression of genes encoding the acetyl-CoA pathway. We demonstrate that H2 from iron-sulfide precipitation under simulated early Earth hydrothermal geochemistry fuels a H2-dependent primordial metabolism. Show less

Mitochondrial outer membrane permeabilization (MOMP) refers to the increase in permeability of the mitochondrial outer membrane, allowing proteins, DNA, and other molecules to pass through the intermembrane space into the cytosol. As a crucial event in the induction of apoptosis, MOMP plays a significant role in regulating various forms of cell death, including apoptosis, ferroptosis, and pyroptosis. Importantly, MOMP is not a binary process of "all-or-nothing." Under sub-lethal stress stimuli, cells may experience a phenomenon referred to as minority MOMP (miMOMP), where only a subset of mitochondria undergo functional impairment, thereby disrupting the normal life cycle of the cell. This can lead to pathological and physiological changes such as tumor formation, cellular senescence, innate immune dysfunction, and chronic inflammation. This review focuses on the diversity of MOMP events to elucidate how varying degrees of MOMP under different stress conditions influence cell fate. Additionally, it summarizes the current research progress on novel antitumor therapeutic strategies targeting MOMP in clinical contexts. Show less

Iron-sulfur (Fe-S) clusters are critical cofactors in metalloproteins, essential for cellular processes such as energy production, DNA repair, enzymatic catalysis, and metabolic regulation. While Fe-S cluster functions are intimately linked to their redox properties, their precise roles in many proteins remain unclear. In this study, we present a regression model based on experimental redox potential (E m ) data, utilizing only two features: the Fe-S cluster's total charge and the Fe atoms' average valence. This model achieves a high correlation with experimental data (R 2 = 0.82) and an average prediction error of 0.12 V. Applying this model across the Protein Data Bank, we predict E m values for all cataloged Fe-S clusters, uncovering redox potential trends across diverse cluster classes. The computed redox potentials showed strong agreement with experimental values, achieving an overall accuracy of 88%. This streamlined, computationally accessible approach enhances the annotation and mechanistic understanding of Fe-S proteins, offering new insights into the redox variability of electron transport proteins. Our model holds promise for advancing studies of metalloprotein function and facilitating the design of bioinspired redox systems. Show less

Oxidative stress appears to act globally and span body systems (e.g., nervous, immune, and endocrine). Currently, there is no single, generally-accepted measurement of oxidative stress. Many possible measurement approaches focus on the bottom-up analysis of individual molecules (e.g., reactive species, antioxidants, hormones or signaling molecules) or combinations of molecules (e.g., proteomics or metabolomics). Efforts to develop a global measurement of oxidative stress often detect a sample's ability to reduce a metal-ion (e.g., iron or copper) or quench a free radical. Here, we review results from a recently-developed iridium-reducing capacity assay (Ir-RCA) and suggest that this method offers several key benefits as a potential measurement of oxidative stress. First, the Ir-RCA employs simple optical and/or electrochemical measurements that can be extended to high throughput formats. Second, the Ir-RCA appears to be more sensitive than alternative global antioxidant assays. Third, the Ir-RCA measures stable molecular features of a sample. Fourth, the Ir-RCA has been "validated" by showing statistically significant differences in persons diagnosed with schizophrenia (N = 73) versus healthy controls (N = 45). Fifth, the Ir-RCA measurement of oxidative stress is "movable": psychosocial stressors can increase this measure of oxidative stress, while beneficial dietary interventions can decrease this measure of oxidative stress. Limitations and future directions for the Ir-RCA are discussed. Show less

N-acetyl-l-cysteine (NAC) is a medication and a widely used antioxidant in cell death research. Despite its somewhat obscure mechanism of action, its role in inhibiting ferroptosis is gaining increasing recognition. In this study, we demonstrate that NAC treatment rapidly replenishes the intracellular cysteine pool, reinforcing its function as a prodrug for cysteine. Interestingly, its enantiomer, N-acetyl-d-cysteine (d-NAC), which cannot be converted into cysteine, also exhibits a strong anti-ferroptotic effect. We further clarify that NAC, d-NAC, and cysteine all act as direct reducing substrates for GPX4, counteracting lipid peroxidation. Consequently, only GPX4-rather than system xc-, glutathione biosynthesis, or ferroptosis suppressor protein 1-is necessary for NAC and d-NAC to prevent ferroptosis. Additionally, we identify a broad range of reducing substrates for GPX4 in vitro, including β-mercaptoethanol. These findings provide new insights into the mechanisms underlying the protective effects of NAC and other potential GPX4-reducing substrates against ferroptosis. Show less

Ferroptosis is a distinct form of regulated cell death characterized by iron-dependent lipid peroxidation, which plays a critical role in the pathogenesis of various diseases, including ischemic tissue injury, infectious diseases, neurodegenerative disorders, and cancer. The regulatory mechanisms underlying ferroptosis involve a complex interplay of multiple subcellular organelles, orchestrating iron homeostasis, lipid metabolism, and the generation of reactive oxygen species (ROS) that drive peroxidation processes, ultimately leading to membrane damage and cell death. Numerous antioxidant systems play pivotal roles in regulating and preventing ferroptosis, among which the recently identified mitochondrial inner membrane enzyme dihydroorotate dehydrogenase (DHODH) represents a novel therapeutic target for ferroptosis intervention. This systematic review comprehensively elucidates several key cellular defense mechanisms against ferroptosis that counteract ROS-driven peroxidation and operate through distinct subcellular localizations. We particularly focus on delineating the molecular mechanisms by which DHODH regulates ferroptosis, with special emphasis on its role in suppressing mitochondrial lipid peroxidation. Furthermore, we systematically evaluate the therapeutic potential of DHODH inhibitors in oncology, virology, and immune-inflammatory disorders. By integrating ferroptosis biology with DHODH-mediated cytoprotective networks, this review aims to provide mechanistic insights and novel therapeutic strategies for cancer and oxidative stress-related disorders. Show less

BACKGROUND: The adaptation of the redox system and bioenergetics is a major factor contributing to cancer metabolism. Redox therapy is promising but still requires molecular studies that consider the reactive species interactome (RSI) concept, which integrates reactive oxygen, nitrogen, sulfur, carbonyl species, and redox enzymes. Our aim was to decipher the role of the RSI in glioblastoma (GBM), including by challenging the RSI with the MnTBAP redox agent. METHODS: The effects of MnTBAP on the redox system and bioenergetics were investigated on several GBM models, namely in vitro 2D culture, in vitro 3D culture with two human GBM tumoroids, and in vivo preclinical model, which included male and female comparisons. RESULTS: We show - for the first time - that MnTBAP represses the sulfide:quinone oxidoreductase (SQOR) involved in the sulfur metabolism and bioenergetics, and targets the RSI through the sulfido-redox system. Through in vitro silencing and overexpression approaches, we also demonstrate that SQOR contributed to GBM cell growth and that its decrease is involved in the molecular effect of MnTBAP. Consequently, MnTBAP induces a switch between apoptosis, uncontrolled necrosis, and ferroptosis depending on the glioblastoma models. CONCLUSION: Our findings represent the next step in establishing a better understanding of redox biology in the context of GBM. Show less

Ferroptosis, a novel form of regulated cell death induced by the excessive accumulation of lipid peroxidation products, plays a pivotal role in the suppression of tumorigenesis. Two prominent mitochondrial ferroptosis defense systems are glutathione peroxidase 4 (GPX4) and dihydroorotate dehydrogenase (DHODH), both of which are localized within the mitochondria. However, the existence of supplementary cellular defense mechanisms against mitochondrial ferroptosis remains unclear. Our findings unequivocally demonstrate that inactivation of mitochondrial respiratory chain complex I (MCI) induces lipid peroxidation and consequently invokes ferroptosis across GPX4 low-expression cancer cells. However, in GPX4 high expression cancer cells, the MCI inhibitor did not induce ferroptosis, but increased cell sensitivity to ferroptosis induced by the GPX4 inhibitor. Overexpression of the MCI alternative protein yeast NADH-ubiquinone reductase (NDI1) not only quells ferroptosis induced by MCI inhibitors but also confers cellular protection against ferroptosis inducers. Mechanically, MCI inhibitors actuate an elevation in the NADH level while concomitantly diminishing the CoQH2 level. The manifestation of MCI inhibitor-induced ferroptosis can be reversed by supplementation with mitochondrial-specific analogues of CoQH2. Notably, MCI operates in parallel with mitochondrial-localized GPX4 and DHODH to inhibit mitochondrial ferroptosis, but independently of cytosolically localized GPX4 or ferroptosis suppressor protein 1(FSP1). The MCI inhibitor IACS-010759, is endowed with the ability to induce ferroptosis while concurrently impeding tumor proliferation in vivo. Our results identified a ferroptosis defense mechanism mediated by MCI within the mitochondria and suggested a therapeutic strategy for targeting ferroptosis in cancer treatment. Show less