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Zinc is a crucial element in cellular processes, and its homeostasis has intricate relationships with the initiation, progression, and therapeutic intervention of cancer. Activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway has been proven to be an effective strategy for cancer immunotherapy. Herein, we report four phosphorescent iridium complexes (Ir1–Ir4) with zinc chelating ligands. Among them, Ir1 can bind and image mitochondrial chelatable zinc ions via phosphorescence-lifetime responses, consequently modulating the expression of zinc-regulatory proteins. Furthermore, the in situ formed heteronuclear metal complex Ir1-Zn2 shows nuclease mimetic activities, capable of hydrolyzing mitochondrial DNA (mtDNA) to release mtDNA fragments for the activation of the cGAS-STING pathway. In conclusion, we designed a mitochondria-targeting phosphorescent Ir(III) complex with dual functions in dysregulation of zinc homeostasis and generation of nuclease in situ, which provides an innovative approach to stimulate the cGAS-STING pathway. Show less

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

Abstract Most clinically used chemotherapeutic agents act by inducing apoptosis. However, their clinical effectiveness is often limited by poor therapeutic efficacy and the rapid development of drug resistance. In contrast, oncosis, as an inflammatory form of cell death independent of adenosine triphosphate (ATP) and apoptotic pathways, exhibits unique advantages in overcoming tumor drug resistance and regulating anti‐tumor immune responses. Herein, we present the first iridium(III)‐based immunogenic oncosis inducers designed to concurrently induce oncosis and activate the cGAS–STING pathway, thereby bridging chemotherapy with immunotherapy. Through a bioisosteric design strategy, we identified benzoselenazole and benzothiazole derivatives as key pharmacophores for triggering oncosis. These iridium(III)‐based oncosis‐inducers rapidly disrupt mitochondrial architecture, induce oxidative stress, and promote Ca(II) release, which subsequently activate calpain and porimin to initiate oncosis in multidrug‐resistant cancer cells. Transcriptomic profiling further revealed their ability to regulate actin cytoskeleton organization, modulate ABC transporter activity, and affect glycolysis/gluconeogenesis. Notably, the metal complexes induce mitochondrial swelling and mt‐DNA damage, leading to robust activation of the cGAS–STING innate immune pathway and eliciting a strong anticancer immune response. Based on these multimodal mechanisms, the Ir(III)‐based immunogenic oncosis inducers were able to effectively kill drug‐resistant cancer cells and enhance the anticancer immune response in tumor mouse models. Show less

Glutathione (GSH), the most abundant intracellular thiol-containing antioxidant, plays a pivotal role in cellular metabolism and redox homeostasis. Its critical involvement in cancer and neurodegenerative diseases has made it an important target for thiol detection systems. In this work, we report the design and synthesis of two novel near-infrared (NIR) phosphorescent Ir(III) complexes as multifunctional probes for GSH detection and photodynamic therapy (PDT). These probes feature an α,β-unsaturated ketone moiety that selectively reacts with the thiol group in GSH, enabling the specific sensing of intracellular and extracellular GSH with applications in bioimaging. Beyond their sensing capabilities, both Ir(III) complexes exhibit strong reactive oxygen species (ROS) generation efficiency, aggregation-induced emission (AIE) characteristics, and mitochondria-targeting properties, making them highly effective for PDT. Notably, upon cellular uptake, these complexes deplete mitochondrial GSH, disrupting redox homeostasis and triggering a rapid accumulation of localized ROS. This dual mechanism─combining GSH depletion and enhanced ROS production─induces potent apoptotic cell death. This work provides a strategic approach for developing advanced NIR photosensitizers with AIE activity, mitochondria-specific targeting, and the ability to simultaneously engage type I and type II PDT pathways while modulating intracellular antioxidant defense systems. Such multifunctional theranostic probes offer considerable potential for enhancing the efficacy of photodynamic cancer therapy, particularly in the treatment of hypoxic tumors. Show less

Nucleotide excision repair (NER) is a universal cut-and-paste DNA repair mechanism that corrects bulky DNA lesions such as those caused by UV radiation, environmental mutagens, and some chemotherapy drugs. In this review, we focus on the human transcription/DNA repair factor TFIIH, a key player of the NER pathway in eukaryotes. This 10-subunit multiprotein complex notably verifies the presence of a lesion and opens the DNA around the damage via its XPB and XPD subunits, two proteins identified in patients suffering from Xeroderma Pigmentosum syndrome. Isolated as a class II gene transcription factor in the late 1980s, TFIIH is a prototypic molecular machine that plays an essential role in both DNA repair and transcription initiation and harbors a DNA helicase, a DNA translocase, and kinase activity. More recently, TFIIH subunits have been identified as participating in other cellular processes, including chromosome segregation during mitosis, maintenance of mitochondrial DNA integrity, and telomere replication. Show less

Challenges in pancreatic cancer treatment primarily arise from chemotherapy resistance, cancer cell metastasis, and frequent late-stage diagnoses. These issues significantly compromise the effectiveness of standard treatments and highlight the urgent need for targeted approaches. In this context, we explored the anticancer potential of bis-quaternary ammonium-based compounds (BQACs), which remains largely uncharted. This study examines the structure-activity relationship of amphiphilic bicationic compounds as anticancer agents, focusing on their selectivity against pancreatic cancer cells. Our analysis revealed a potent antiproliferative effect associated with mitochondrial accumulation and subsequent mitochondrial membrane depolarization. Furthermore, combination therapies involving BQACs and chemotherapeutic drugs were explored to enhance treatment efficacy. Consequently, we propose a novel combination of BQACs with metformin, resulting in enhanced cellular uptake of the latter. The synergistic effect of the combination enables a significantly lower effective dose of metformin when used alongside BQACs to achieve therapeutic outcomes. Show less

The effectiveness of existing systemic and targeted therapies remains limited in triple-negative breast cancer (TNBC) treatment. Much research has been conducted on reactive oxygen species (ROS)-mediated cancer cell death to overcome the shortcomings of the currently applied chemotherapeutic treatments. Herein, we have developed novel Ru(II)/Ir(III)-mediated triazolylpyridine complexes as ROS inducers. Upon entering the TNBC cells, the Ru(II) complex effectively accumulated in mitochondria and triggered the creation of ROS, facilitating dysfunction of mitochondria and oxidative DNA damage, ultimately causing death of cells through G2/M phase cell cycle arrest. Eventually, this complex induced the upregulation of BAX (pro-apoptotic protein) and downregulation of BCL-2 (antiapoptotic protein) and triggered the caspase 3/9 pathway and released cytochrome c in the cytosol for apoptosis. The complex JRu (RuII triazolylpyridine) significantly reduced the integrity and viability of TNBC 3D spheroids. Show less

Mitochondria are associated with cellular energy metabolism, proliferation, and mode of death. Damage to mitochondrial DNA (mtDNA) greatly affects mitochondrial function by interfering with energy production and the signaling pathway. Monofunctional trinuclear platinum complex MTPC demonstrates different actions on the mtDNA of cancerous and normal cells. It severely impairs the integrity and function of mitochondria in the human lung cancer A549 cells, such as dissipating mitochondrial membrane potential, decreasing the copy number of mtDNA, interfering in nucleoid proteins and polymerase gamma gene, reducing adenosine triphosphate (ATP), and inducing mitophagy, whereas it barely affects the mtDNA of the human kidney 2 (HK-2) cells. Moreover, MTPC promotes the release of mtDNA into the cytosol and stimulates the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, thus showing the potential to trigger antitumor immunity. MTPC displays significant cytotoxicity against A549 cells, while it exhibits weak toxicity toward HK-2 cells, therefore displaying great advantage to overcome the lingering nephrotoxicity of platinum anticancer drugs. Discrepant effects of a metal complex on mitochondria of different cells mean that targeting mitochondria has special significance in cancer therapy. Show less

Mitochondria are the energy production centers in cells and have unique genetic information. Due to the irreplaceable function of mitochondria, mitochondrial dysfunction often leads to pathological changes. Mitochondrial dysfunction induces an imbalance between oxidation and antioxidation, mitochondrial DNA (mtDNA) damage, mitochondrial dynamics dysregulation, and changes in mitophagy. It results in oxidative stress due to excessive reactive oxygen species (ROS) generation, which contributes to cell damage and death. Mitochondrial dysfunction can also trigger inflammation through the activation of damage-associated molecular patterns (DAMPs), inflammasomes and inflammatory cells. Besides, mitochondrial alterations in the functional regulation, energy metabolism and genetic stability accompany the aging process, and there has been a lot of evidence suggesting that oxidative stress and inflammation, both of which are associated with mitochondrial dysfunction, are predisposing factors of aging. Therefore, this review hypothesizes that mitochondria serve as central hubs regulating oxidative stress, inflammation, and aging, and their dysfunction contributes to various diseases, including cancers, cardiovascular diseases, neurodegenerative disorders, metabolic diseases, sepsis, ocular pathologies, liver diseases, and autoimmune conditions. Moreover, we outline therapies aimed at various mitochondrial dysfunctions, highlighting their performance in animal models and human trials. Additionally, we focus on the limitations of mitochondrial therapy in clinical applications, and discuss potential future research directions for mitochondrial therapy. Show less

Redox signaling acts as a critical mediator in the dynamic interactions between organisms and their external environment, profoundly influencing both the onset and progression of various diseases. Under physiological conditions, oxidative free radicals generated by the mitochondrial oxidative respiratory chain, endoplasmic reticulum, and NADPH oxidases can be effectively neutralized by NRF2-mediated antioxidant responses. These responses elevate the synthesis of superoxide dismutase (SOD), catalase, as well as key molecules like nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), thereby maintaining cellular redox homeostasis. Disruption of this finely tuned equilibrium is closely linked to the pathogenesis of a wide range of diseases. Recent advances have broadened our understanding of the molecular mechanisms underpinning this dysregulation, highlighting the pivotal roles of genomic instability, epigenetic modifications, protein degradation, and metabolic reprogramming. These findings provide a foundation for exploring redox regulation as a mechanistic basis for improving therapeutic strategies. While antioxidant-based therapies have shown early promise in conditions where oxidative stress plays a primary pathological role, their efficacy in diseases characterized by complex, multifactorial etiologies remains controversial. A deeper, context-specific understanding of redox signaling, particularly the roles of redox-sensitive proteins, is critical for designing targeted therapies aimed at re-establishing redox balance. Emerging small molecule inhibitors that target specific cysteine residues in redox-sensitive proteins have demonstrated promising preclinical outcomes, setting the stage for forthcoming clinical trials. In this review, we summarize our current understanding of the intricate relationship between oxidative stress and disease pathogenesis and also discuss how these insights can be leveraged to optimize therapeutic strategies in clinical practice. Show less

Mitochondria are bilayer membrane organelles with basic metabolic activity. They are considered hubs for biosynthesis, bioenergy, and signaling functions, coordinating major biological pathways. Mitochondria are coupled to the oxidation of fatty acids and pyruvate through electron transport chains and have historically been considered the primary source of cellular energy. Recent studies have depicted that mitochondria are centers that promote inflammatory responses and play a crucial role in combating pathogenic infections. Moreover, mitochondria provide the basis for tumor synthesis metabolism, control redox and calcium homeostasis, participate in transcriptional regulation, and control cell death. Mitochondria are involved in all steps of tumorigenesis. This review discusses the relationship between mitochondria (including mitochondrial metabolism and mitophagy) and tumors, and the relationship between mtDNA and inflammation, as well as its clinical application in inflammatory diseases. More importantly, the application and targeted treatment strategies provide more opportunities for the development of new anticancer drugs. Show less

Cytochrome c (Cytc) is a multifunctional protein, essential for respiration and intrinsic apoptosis. Post-translational modifications of Cytc have been linked to physiological and pathophysiologic conditions, including cancer. Cytc tyrosine 67 (Y67) is a conserved residue that is important to the structure and function of Cytc. We here report the phosphorylation of Y67 of Cytc purified from bovine heart mapped by mass spectrometry. We characterized the functional effects of Y67 Cytc modification using in vitro and cell culture models. Y67 was mutated to the phosphomimetic glutamate (Y67E) and to phenylalanyl (Y67F) as a control. The phosphomimetic Y67E Cytc inhibited cytochrome c oxidase (COX) activity, redirecting energy metabolism toward glycolysis, and decreased the pro-apoptotic capabilities of Cytc. The phosphomimetic Y67E Cytc showed a significantly impaired rate of superoxide scavenging and a reduced rate of oxidation by hydrogen peroxide, suggesting a lower ability to transfer electrons and scavenge reactive oxygen species (ROS). Phosphomimetic Y67E replacement led to an almost complete loss of cardiolipin peroxidase activity, pointing to a central role of Y67 for this catalytic function of Cytc. In intact cells, phosphomimetic replacement leads to a reduction in cell respiration, mitochondrial membrane potential, and ROS levels. We propose that Y67 phosphorylation is cardioprotective and promotes cell survival. Show less

Abstract 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

Background Rhabdomyolysis (RM), particularly heat exhaustion-associated rhabdomyolysis (ehsRM), is a significant clinical issue associated with high mortality and healthcare costs. However, the cellular death mechanisms remain incompletely understood. Oncosis, a form of passive cell death distinct from apoptosis, is characterized by cell swelling and triggered by ATP depletion. Additionally, porimin, a specific biomarker, can uniquely identify oncosis. This study aims to investigate the role and mechanisms of oncosis in both in vitro and in vivo models of ehsRM. Objective This study aims to investigate the role and mechanisms of oncosis in both in vitro and in vivo models of ehsRM. Methods In the in vitro study, 6-8-week-old male rats were subjected to treadmill exercise at an ambient temperature of (39.5 ± 0.5)°C and relative humidity of 50%-60%, at a speed of 15 meters per minute until their core body temperature (Tc) reached 43.0°C to establish a heatstroke animal model. Skeletal muscle and blood samples from the gastrocnemius were collected for cytokine, biochemical, and histopathological analyses. Pathological findings revealed decreased muscle fiber density, structural disarray, swelling, degeneration, and hemorrhage. Ultrastructural analysis showed cell swelling, structural disarray, cytoplasmic vacuolation, mitochondrial swelling and degeneration, loss of cristae, and nuclear degeneration, indicating myocyte swelling and necrosis. Porimin, CytC, Bax, and caspase-1 expression increased, while Bcl-2 expression decreased. JC-1 staining indicated a decline in mitochondrial membrane potential and dysfunction. ATP levels decreased, and reactive oxygen species (ROS) production increased. In the in vivo study, HSKMC cells were subjected to 4 hours of heat shock at 43°C to establish a heatstroke-induced rhabdomyolysis cell model. Electron microscopy revealed cell swelling, cytoplasmic vacuolation, mitochondrial swelling and degeneration, and nuclear swelling; late-stage (necrotic-like death) was characterized by nucleolar dissolution, nuclear fragmentation, chromatin condensation, and collapse of cytoplasmic structures. After 24 hours post-modeling, the proportion of double-positive cells (porimin + /PI+) and ROS levels significantly increased, as did porimin expression, while mitochondrial membrane potential and ATP levels significantly decreased. The proportion of Annexin V + /PI + double-positive cells and caspase-3 levels showed no significant changes. Results In both in vitro and in vivo studies, oncosis played a crucial role in ehsRM. Pathological and ultrastructural analyses demonstrated cell swelling, structural disarray, mitochondrial damage, and nuclear degeneration. Porimin, CytC, Bax, and caspase-1 expression increased, while Bcl-2 expression decreased. ATP levels decreased, and ROS production increased. In the in vivo study, the proportion of porimin + /PI + double-positive cells and ROS levels significantly increased, while mitochondrial membrane potential and ATP levels significantly decreased. The proportion of Annexin V + /PI + double-positive cells and caspase-3 levels showed no significant changes. Conclusion Oncosis is predominant in ehsRM, involving mitochondrial dysfunction, ATP depletion, and oxidative stress. 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

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

Mitochondria are dynamic organelles that are essential for cellular energy generation, metabolic regulation, and signal transduction. Their structural complexity enables adaptive responses to diverse physiological demands. In cancer, mitochondria orchestrate multiple cellular processes critical to tumor development. Metabolic reprogramming enables cancer cells to exploit aerobic glycolysis, glutamine metabolism, and lipid alterations, supporting uncontrolled growth, survival, and treatment resistance. Genetic and epigenetic alterations in mitochondrial and nuclear DNA disrupt oxidative phosphorylation, tricarboxylic acid cycle dynamics, and redox homeostasis, driving oncogenic progression. Mitochondrial dysfunction in tumors is highly heterogeneous, influencing disease phenotypes and treatment responses across cancer types. Within the tumor microenvironment, mitochondria profoundly impact immune responses by modulating T-cell survival and function, macrophage polarization, NK cell cytotoxicity, and neutrophil activation. They also mediate stromal cell functions, particularly in cancer-associated fibroblasts and tumor endothelial cells. Although targeting mitochondrial function represents a promising therapeutic strategy, mitochondrial heterogeneity and adaptive resistance mechanisms complicate interventional approaches. Advances in mitochondrial genome editing, proteomics, and circulating mitochondrial DNA analysis have enhanced tumor diagnostic precision. This review synthesizes the developmental landscape of mitochondrial research in cancer, comprehensively summarizing mitochondrial structural dynamics, metabolic plasticity, signaling networks, and interactions with the tumor microenvironment. Finally, we discuss the translational challenges in developing effective mitochondria-based cancer interventions. Show less

Mitochondria are bilayer membrane organelles with basic metabolic activity. They are considered hubs for biosynthesis, bioenergy, and signaling functions, coordinating major biological pathways. Mitochondria are coupled to the oxidation of fatty acids and pyruvate through electron transport chains and have historically been considered the primary source of cellular energy. Recent studies have depicted that mitochondria are centers that promote inflammatory responses and play a crucial role in combating pathogenic infections. Moreover, Show less

Abstract 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

NRF2 is a redox-sensitive transcription factor that activates the expression of phase II detoxifying and antioxidant enzymes. In addition to maintaining redox homeostasis, NRF2 regulates various other processes, including metabolism, stem cell renewal, mitochondrial function, and proteostasis. NRF2 is considered a tumor suppressor because its activation by chemopreventive phytochemicals contributes to the detoxification of oxidants and electrophiles in normal cells. However, aberrant NRF2 activation occurs in cancer due to mutations in the KEAP1/NRF2 pathway, and it contributes to the generation of a tumor microenvironment that favors the proliferation, survival, and chemoresistance of cancer cells. In this review, we present the regulatory mechanisms of NRF2 and discuss how NRF2 activation contributes to chemoresistance. We also explain therapeutic strategies that exploit the vulnerabilities of NRF2-addicted cancer cells, providing NRF2 small-molecule inhibitors along with their mechanisms of action. 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

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

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

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

Studies by microbiologists in the 1970s provided robust estimates for the energy supply and demand of a prokaryotic cell. The amount of ATP needed to support growth was calculated from the chemical composition of the cell and known enzymatic pathways that synthesize its constituents from known substrates in culture. Starting in 2015, geneticists and evolutionary biologists began investigating the bioenergetic role of mitochondria at eukaryote origin and energy in metazoan evolution using their own, widely trusted-but hitherto unvetted-model for the costs of growth in terms of ATP per cell. The more recent model contains, however, a severe and previously unrecognized error that systematically overestimates the ATP cost of amino acid synthesis up to 200-fold. The error applies to all organisms studied by such models and leads to conspicuously false inferences, for example that the synthesis of an average amino acid in humans requires 30 ATP, which no biochemistry textbook will confirm. Their ATP 'cost' calculations would require that E. coli obtains ~100 ATP per glucose and that mammals obtain ~240 ATP per glucose, untenable propositions that invalidate and void all evolutionary inferences so based. By contrast, established methods for estimating the ATP cost of microbial growth show that the first mitochondrial endosymbionts could have easily doubled the host's available ATP pool, provided (i) that genes for growth on environmental amino acids were transferred from the mitochondrial symbiont to the archaeal host, and (ii) that the host for mitochondrial origin was an autotroph using the acetyl-CoA pathway. Stated in simple terms, the significance of these findings are this: Life is a chemical reaction. It requires energy release in order to proceed. The currency of energy in cells is adenosine triphosphate, ATP. Five decades ago, microbiologists were able to measure and understand the amount of ATP that cells require to grow. New studies by evolutionary biologists have appeared in the meantime that brush aside the older microbiological findings, using their own methods to calculate the ATP cost of growth instead. Science is, however, an imperfect undertaking. The new studies contain a major error, similar to conflating centimeters with yards. The error affects many publications and their conclusions. Using the old methods, we can still meaningfully study the role of energy in evolution, including the origin of complex, nucleus-bearing cells. Show less

PT-112 is a novel small molecule exhibiting promising clinical activity in patients with solid tumors. PT-112 kills malignant cells by inhibiting ribosome biogenesis while promoting the emission of immunostimulatory signals. Accordingly, PT-112 is an authentic immunogenic cell death (ICD) inducer and synergizes with immune checkpoint inhibitors in preclinical models of mammary and colorectal carcinoma. Moreover, PT-112 monotherapy has led to durable clinical responses, some of which persisting after treatment discontinuation. Mitochondrial outer membrane permeabilization (MOMP) regulates the cytotoxicity and immunogenicity of various anticancer agents. Here, we harnessed mouse mammary carcinoma TS/A cells to test whether genetic alterations affecting MOMP influence PT-112 activity. As previously demonstrated, PT-112 elicited robust antiproliferative and cytotoxic effects against TS/A cells, which were preceded by the ICD-associated exposure of calreticulin (CALR) on the cell surface, and accompanied by the release of HMGB1 in the culture supernatant. TS/A cells responding to PT-112 also exhibited eIF2α phosphorylation and cytosolic mtDNA accumulation, secreted type I IFN, and exposed MHC Class I molecules as well as the co-inhibitory ligand PD-L1 on their surface. Acute cytotoxicity and HMGB1 release caused by PT-112 in TS/A cells were influenced by MOMP competence. Conversely, PT-112 retained antiproliferative effects and its capacity to drive type I IFN secretion as well as CALR, MHC Class I and PD-L1 exposure on the cell surface irrespective of MOMP defects. These data indicate a partial involvement of MOMP in the mechanisms of action of PT-112, suggesting that PT-112 is active across various tumor types, including malignancies with MOMP defects. Show less

ATP synthase, the enzyme responsible for regenerating adenosine triphosphate (ATP) in the cell, comprises a proton-translocating motor in the cell membrane (labeled FO in bacteria, mitochondria, and chloroplasts), coupled by a common stalk to a catalytic motor F1 that synthesizes or hydrolyzes ATP, depending on the direction of rotation. The detailed mechanisms of FO, F1 and their coupling in ATP synthase have been elucidated through structural studies, single-molecule experiments, and molecular modeling. The outcomes of this body of work are reviewed with a particular focus on the features of the mechanism that enable the high energy efficiency and reversibility of ATP synthase. Models for the origin of chemiosmosis involve either ATP synthesis (driven by the proton gradient across the membrane) or ATP hydrolysis (for pumping protons out of the cell) as a primary function, the other function being a later development enabled by the coupled nature of the two motors. The mechanism of ATP synthase and the stringent requirements on efficiency to maintain life constrain existing models and the search for the origin of chemiosmosis. Show less

Mitochondria are the energy production centers in cells and have unique genetic information. Due to the irreplaceable function of mitochondria, mitochondrial dysfunction often leads to pathological changes. Mitochondrial dysfunction induces an imbalance between oxidation and antioxidation, mitochondrial DNA (mtDNA) damage, mitochondrial dynamics dysregulation, and changes in mitophagy. It results in oxidative stress due to excessive reactive oxygen species (ROS) generation, which contributes to cell damage and death. Mitochondrial dysfunction can also trigger inflammation through the activation of damage-associated molecular patterns (DAMPs), inflammasomes and inflammatory cells. Besides, mitochondrial alterations in the functional regulation, energy metabolism and genetic stability accompany the aging process, and there has been a lot of evidence suggesting that oxidative stress and inflammation, both of which are associated with mitochondrial dysfunction, are predisposing factors of aging. Therefore, this review hypothesizes that mitochondria serve as central hubs regulating oxidative stress, inflammation, and aging, and their dysfunction contributes to various diseases, including cancers, cardiovascular diseases, neurodegenerative disorders, metabolic diseases, sepsis, ocular pathologies, liver diseases, and autoimmune conditions. Moreover, we outline therapies aimed at various mitochondrial dysfunctions, highlighting their performance in animal models and human trials. Additionally, we focus on the limitations of mitochondrial therapy in clinical applications, and discuss potential future research directions for mitochondrial therapy. Show less

Platinum-based drugs are a mainstay in chemotherapy, with traditional forms exerting their work directly on DNA. In recent years, it has been observed that platinum complexes had the potential to induce immunogenic cell death (ICD) and effectively trigger antitumor immune responses. Herein, to obtain novel platinum complexes with chemo-immunological properties, a series of Pt(ΙΙ)-N-heterocyclic carbene (Pt(ΙΙ)-NHC) complexes derived from 4,5-diarylimidazoles were synthesized. Among them, the dominant complex 3f was proved to exhibit better anti-liver cancer capacity compared to cisplatin and oxaliplatin. Complex 3f showed the ability to cause DNA damage by binding to DNA. In addition, it triggered intracellular reactive oxygen species (ROS) generation, affected the function of mitochondria, and blocked cells in G0/G1 phase, ultimately induced apoptosis in liver cancer cells. Furthermore, complex 3f activated endoplasmic reticulum stress (ERS) which promoted the release of damage-associated molecular patterns (DAMPs), induced ICD and dendritic cells (DCs) maturation. Interestingly, complex 3f also upregulated PD-L1, consequently converted "cold tumors" into "hot tumors". Overall, complex 3f had the potential to be regarded as a promising chemoimmunotherapy for the treatment of liver cancer. Show less