Iron-Sensitive Prodrugs That Trigger Active Ferroptosis in Drug-Tolerant Pancreatic Cancer Cells

Effect of stereochemistry at position C20 on the antiproliferative activity and selectivity of N-acylated derivatives of salinomycin

Salinomycin (SAL), a natural polyether ionophore, exhibits a broad spectrum of pharmacological activities, including potent anticancer activity. Over the past decade, much effort has been put into developing methods for rational chemical modification of SAL to obtain semisynthetic analogs with higher anticancer activity than the native structure. In this paper, we describe an optimized procedure for synthesizing C20-aminosalinomycin 2 with native stereochemistry at position C20, which was confirmed by single-crystal X-ray diffraction analysis. We further transformed amine precursor 2 into a series of 48 C20-N-(thio)acylated products, including N-(sulfon)amides, N-(thio)ureas, and N-carbamates (urethanes), along with their sulfur analogs, i.e., S-substituted thiocarbamates and dithiocarbamates. This previously unreported class of derivatives showed superior cytotoxicity mostly in the nano- and subnanomolar concentration range and improved selectivity toward human cancer cells compared to those of chemically unmodified SAL and a commonly used oncological drug cisplatin. Of note, the obtained products inhibited the proliferation of reference cancer cells more effectively than their C20-epi-N-acylated counterparts, pointing out the pivotal role of stereochemistry at position C20. Our findings support the premise that the modification of SAL is a fruitful strategy for products with promising biological activity profiles. Moreover, the straightforward protocols should be of significant value for more elaborate modifications of SAL in the future.

Activation of lysosomal iron triggers ferroptosis in cancer

Iron catalyses the oxidation of lipids in biological membranes and promotes a form of cell death called ferroptosis1. Defining where this chemistry occurs in the cell can inform the design of drugs capable of inducing or inhibiting ferroptosis in various disease-relevant settings. Genetic approaches have revealed suppressors of ferroptosis2-4; by contrast, small molecules can provide spatiotemporal control of the chemistry at work5. Here we show that the ferroptosis inhibitor liproxstatin-1 exerts cytoprotective effects by inactivating iron in lysosomes. We also show that the ferroptosis inducer RSL3 initiates membrane lipid oxidation in lysosomes. We designed a small-molecule activator of lysosomal iron-fentomycin-1-to induce the oxidative degradation of phospholipids and ultimately ferroptosis. Fentomycin-1 is able to kill iron-rich CD44high primary sarcoma and pancreatic ductal adenocarcinoma cells, which can promote metastasis and fuel drug tolerance. In such cells, iron regulates cell adaptation6,7 while conferring vulnerability to ferroptosis8,9. Sarcoma cells exposed to sublethal doses of fentomycin-1 acquire a ferroptosis-resistant cell state characterized by the downregulation of mesenchymal markers and the activation of a membrane-damage response. This phospholipid degrader can eradicate drug-tolerant persister cancer cells in vitro and reduces intranodal tumour growth in a mouse model of breast cancer metastasis. Together, these results show that control of iron reactivity confers therapeutic benefits, establish lysosomal iron as a druggable target and highlight the value of targeting cell states10.

The Role of Cancer Organoids in Ferroptosis, Pyroptosis, and Necroptosis: Functions and Clinical Implications

The enduring prevalence of cancer worldwide constitutes a significant public health challenge, thereby emphasizing the imperative for the development of therapeutic models capable of accounting for the heterogeneity inherent in tumors. In this context, cancer organoids have emerged as powerful tools for studying tumor biology, providing valuable insights into the complex interactions within the tumor microenvironment. Concurrently, research is increasingly focused on non-apoptotic forms of regulated cell death (RCD)-including ferroptosis, pyroptosis, and necroptosis-which exert pivotal influences on cancer development and progression. Cancer organoids not only recapitulate the genetic and phenotypic heterogeneity of the original tumors but also enable more precise investigations into the roles of non-apoptotic RCDs within oncology. This review explores the utility of cancer organoids in delineating the molecular mechanisms underlying RCDs and their implications for cancer biology and treatment responses. By synthesizing recent research findings, it highlights the essential role of organoid models in uncovering the intricate details of non-apoptotic RCDs. Furthermore, it emphasizes promising directions for future research that aim to deepen our understanding of these pathways and their therapeutic potential. The integration of organoid models into investigations of ferroptosis, pyroptosis, and necroptosis provides novel insights into oncogenic mechanisms and facilitates the development of targeted therapeutic strategies. By bridging cancer organoids with human pathophysiology, this approach not only provides a transformative framework for dissecting oncogenic pathways but also enables the design of precision therapeutics that selectively target the molecular machinery underlying non-apoptotic RCDs.

Dysregulation of Labile Iron Predisposes Chemotherapy Resistant Cancer Cells to Ferroptosis

Despite centuries of research, metastatic cancer remains incurable due to resistance to all conventional cancer therapeutics. Alternative strategies leveraging non-proliferative vulnerabilities in cancer are required to overcome cancer recurrence. Ferroptosis is an iron dependent cell death pathway that has shown promising pre-clinical activity in several contexts of therapeutic resistant cancer. However, ferroptosis sensitivity is highly variable across tissue types and cell states, posing a challenge for clinical translation. We describe a convergent phenotype induced by chemotherapy where cells surviving chemotherapy have dysregulated iron homeostasis, regardless of initial cell type or chemotherapy used. Elevated labile iron levels are counteracted by NRF2 signaling, yet the resulting antioxidant programs do not alleviate the labile iron burden. Selectively inhibiting GPX4 leads to uniform susceptibility to ferroptosis in surviving cells, highlighting the common reliance on lipid peroxidation defenses. Cellular iron dysregulation is a vulnerability of chemoresistant cancer cells that can be leveraged by triggering ferroptosis.

Programmed enhancement of endogenous iron-mediated lysosomal membrane permeabilization for tumor ferroptosis/pyroptosis dual-induction

Ferroptosis and pyroptosis, as emerging regulated forms of cell death capable of overcoming apoptotic resistance, demonstrate promising potential in tumor therapy. Given that iron manipulation and reactive oxygen species elevation serve as common stimuli for both processes, inducing lysosomal membrane permeabilization (LMP) with ensuing release of lysosomal contents (including iron ions and cathepsins) is anticipated to realize dual induction of ferroptosis/pyroptosis. Herein, we report a folic acid and croconaine molecule-functionalized upconversion nanoparticle (UCNP-Cro/FA) that is able to mobilize intracellular stores of endogenous iron and spatiotemporally control the lysosome-intrinsic Fenton chemistry, thereby triggering LMP-associated cell death. The process of endogenous iron mobilization occurs through two key steps: Cro-mediated coordination of abundant Fe3+ ions within lysosomes, followed by UV-emitting upconversion core-mediated photoreduction, resulting in Fe2+ ions release. Both in vitro and in vivo experiments show that UCNP-Cro/FA + NIR treatment effectively boost LMP by endogenous iron-mediated •OH production, ultimately triggering irreversible tumor cell death via ferroptosis and Caspase-1/GSDMD-dependent pyroptosis pathways. Moreover, this process potentiates tumor immunogenicity, holding promise for tumor immunotherapy. Overall, this work proposes a feasible tumor therapy strategy that integrates ferroptosis and pyroptosis through the efficient application and activation of endogenous iron.

Copper and iron orchestrate cell-state transitions in cancer and immunity

Whereas genetic mutations can alter cell properties, nongenetic mechanisms can drive rapid and reversible adaptations to changes in their physical environment, a phenomenon termed 'cell-state transition'. Metals, in particular copper and iron, have been shown to be rate-limiting catalysts of cell-state transitions controlling key chemical reactions in mitochondria and the cell nucleus, which govern metabolic and epigenetic changes underlying the acquisition of distinct cell phenotypes. Acquisition of a distinct cell identity, independently of genetic alterations, is an underlying phenomenon of various biological processes, including development, inflammation, erythropoiesis, aging, and cancer. Here, mechanisms that have been uncovered related to the role of these metals in the regulation of cell plasticity are described, illustrating how copper and iron can be exploited for therapeutic intervention.

Metal Ion Signaling in Biomedicine

Complex multicellular organisms are composed of distinct tissues involving specialized cells that can perform specific functions, making such life forms possible. Species are defined by their genomes, and differences between individuals within a given species directly result from variations in their genetic codes. While genetic alterations can give rise to disease-causing acquisitions of distinct cell identities, it is now well-established that biochemical imbalances within a cell can also lead to cellular dysfunction and diseases. Specifically, nongenetic chemical events orchestrate cell metabolism and transcriptional programs that govern functional cell identity. Thus, imbalances in cell signaling, which broadly defines the conversion of extracellular signals into intracellular biochemical changes, can also contribute to the acquisition of diseased cell states. Metal ions exhibit unique chemical properties that can be exploited by the cell. For instance, metal ions maintain the ionic balance within the cell, coordinate amino acid residues or nucleobases altering folding and function of biomolecules, or directly catalyze specific chemical reactions. Thus, metals are essential cell signaling effectors in normal physiology and disease. Deciphering metal ion signaling is a challenging endeavor that can illuminate pathways to be targeted for therapeutic intervention. Here, we review key cellular processes where metal ions play essential roles and describe how targeting metal ion signaling pathways has been instrumental to dissecting the biochemistry of the cell and how this has led to the development of effective therapeutic strategies.

Urea and Thiourea Derivatives of Salinomycin as Agents Targeting Malignant Colon Cancer Cells

BACKGROUND

Since it was discovered that a natural polyether ionophore called salinomycin (SAL) selectively inhibits human cancer cells, the scientific world has been paying special attention to this compound. It has been studied for nearly 15 years.

OBJECTIVE

Thus, a very interesting research direction is the chemical modification of SAL structure, which could give more biologically active agents.

METHODS

We evaluated the anticancer activity of (thio)urea analogues class of C20-epi-aminosalinomycin (compound 3b). The studies covered the generation of reactive oxygen species (ROS), proapoptotic activity, cytotoxic activity, and lipid peroxidation in vitro.

RESULTS

Thioureas 5a-5d showed antiproliferative activity against selected human colon cancer cell lines greater than that of chemically unmodified SAL, with a 2~10-fold higher potency towards a metastatic variant of colon cancer cells (SW620). Mechanistically, SAL derivatives showed proapoptotic activity in primary colon cancer cells and induced the production of reactive oxygen species (ROS) in these cells. In SW620 cells, SAL derivatives increased lipid peroxidation with a weak effect on apoptosis and low ROS formation with cytotoxic effects followed by cytostatic ones, suggesting different modes of action of the compounds against primary and metastatic colon cancer cells.

CONCLUSION

The results of this study suggested that urea and thiourea derivatives of SAL provide promising leads for the rational development of new anticancer active agents.

Effective Synthesis of C20-Epi-Isothiocyanato-Salinomycin and its Thiourea Derivatives as Potential Anticancer Agents

Salinomycin, a naturally occurring polyether ionophore antibiotic isolated from Streptomyces albus, has been demonstrated potent cytotoxic activity against a variety of cancer cell lines. In particular, it exhibits selective targeting of cancer stem cells. However, systemic toxicity, drug resistance and low bioavailability of the drug significantly limit its potential applications. In this study, the C20-epi-isothiocyanate of salinomycin was designed and synthesized, and then reacted with amines as a versatile synthon to assemble a series of salinomycin thiourea derivatives, which improved the druggability of salinomycin. The antiproliferative activities of the compounds were evaluated in vitro against A549, HepG2, HeLa, 4T1, and MCF-7 cancer cell lines using the CCK-8 assay. The pharmacological results showed that some salinomycin thiourea derivatives exhibited excellent inhibitory activity against at least one of the tested tumor cells and high selectivity. Further mechanistic studies showed that compound 9 f, containing a 3,5-difluorobenzyl moiety, could directly induce apoptosis, probably by increasing caspase-9 protein expression and cell cycle arrest in G1 phase in a concentration dependent manner.

A peptide-salinomycin conjugate with a bystander effect reduces the stemness characteristics of ovarian cancer cells and enhances drug sensitivity

Salinomycin (Sal) has attracted considerable attention in the field of tumor treatment, especially for its inhibitory effect on cancer stem cells (CSCs) and drug-resistant tumor cells. However, its solubility and targeting specificity pose significant challenges to its pharmaceutical development. Sal-A6, a novel peptide-drug conjugate (PDC), was formed by linking the peptide A6 targeting the CSC marker CD44 with Sal using a specific linker. This conjugation markedly enhances the physicochemical properties of Sal and compared to Sal, Sal-A6 demonstrated a significantly increased activity against ovarian cancer. Furthermore, Sal-A6, employing a disulfide bond as a linker, exhibited bystander killing effect. Moreover, it induces substantial cytotoxic effect on both cancer stem cells and drug-resistant cells in addition to enhance chemosensitivity of resistant ovarian cancer cells. In summary, the results indicated that Sal-A6, a novel PDC derived from Sal, has potential therapeutic applications in the treatment of ovarian cancer and drug-resistant patients. Additionally, this discovery offers insights for developing PDC-type drugs using Sal as a foundation.

Inhibition of PCSK9: A Promising Enhancer for Anti-PD-1/PD-L1 Immunotherapy

Immune checkpoint therapy, such as programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) blockade, has achieved remarkable results in treating various tumors. However, most cancer patients show a low response rate to PD-1/PD-L1 blockade, especially those with microsatellite stable/mismatch repair-proficient colorectal cancer subtypes, which indicates an urgent need for new approaches to augment the efficacy of PD-1/PD-L1 blockade. Cholesterol metabolism, which involves generating multifunctional metabolites and essential membrane components, is also instrumental in tumor development. In recent years, inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9), a serine proteinase that regulates cholesterol metabolism, has been demonstrated to be a method enhancing the antitumor effect of PD-1/PD-L1 blockade to some extent. Mechanistically, PCSK9 inhibition can maintain the recycling of major histocompatibility protein class I, promote low-density lipoprotein receptor-mediated T-cell receptor recycling and signaling, and modulate the tumor microenvironment (TME) by affecting the infiltration and exclusion of immune cells. These mechanisms increase the quantity and enhance the antineoplastic effect of cytotoxic T lymphocyte, the main functional immune cells involved in anti-PD-1/PD-L1 immunotherapy, in the TME. Therefore, combining PCSK9 inhibition therapy with anti-PD-1/PD-L1 immunotherapy may provide a novel option for improving antitumor effects and may constitute a promising research direction. This review concentrates on the relationship between PCSK9 and cholesterol metabolism, systematically discusses how PCSK9 inhibition potentiates PD-1/PD-L1 blockade for cancer treatment, and highlights the research directions in this field.

Natural products targeting ferroptosis pathways in cancer therapy (Review)

Ferroptosis inducers (FIN) have a key role in cancer therapy and provide novel and innovative treatment strategies. Although many researchers have performed FIN screening of synthetic compounds, studies on the identification of FIN from natural products are limited, particularly in the field of drug development and combination therapy. In this review, this gap was addressed by comprehensively summarizing recent studies on ferroptosis. The causes of ferroptosis were categorized into driving and defensive factors, elucidating key pathways and targets. Next, through summarizing research on natural products that induce ferroptosis, the study elaborated in detail on the natural products that have FIN functions. Their discovery and development were also described and insight for clinical drug development was provided. In addition, the mechanisms of action were analyzed and potential combination therapies, resistance reversal and structural enhancements were presented. By highlighting the potential of natural products in inducing ferroptosis for cancer treatment, this review may serve as a reference for utilizing these compounds against cancer. It not only showed the significance of natural products but may also promote further investigation into their therapeutic effects, thus encouraging research in this field.

Ferroptosis-based advanced therapies as treatment approaches for metabolic and cardiovascular diseases

Ferroptosis has attracted attention throughout the last decade because of its tremendous clinical importance. Here, we review the rapidly growing body of literature on how inhibition of ferroptosis may be harnessed for the treatment of common diseases, and we focus on metabolic and cardiovascular unmet medical needs. We introduce four classes of preclinically established ferroptosis inhibitors (ferrostatins) such as iron chelators, radical trapping agents that function in the cytoplasmic compartment, lipophilic radical trapping antioxidants and ninjurin-1 (NINJ1) specific monoclonal antibodies. In contrast to ferroptosis inducers that cause serious untoward effects such as acute kidney tubular necrosis, the side effect profile of ferrostatins appears to be limited. We also consider ferroptosis as a potential side effect itself when several advanced therapies harnessing small-interfering RNA (siRNA)-based treatment approaches are tested. Importantly, clinical trial design is impeded by the lack of an appropriate biomarker for ferroptosis detection in serum samples or tissue biopsies. However, we discuss favorable clinical scenarios suited for the design of anti-ferroptosis clinical trials to test such first-in-class compounds. We conclude that targeting ferroptosis exhibits outstanding treatment options for metabolic and cardiovascular diseases, but we have only begun to translate this knowledge into clinically relevant applications.

Ferroptosis in health and disease

Ferroptosis is a pervasive non-apoptotic form of cell death highly relevant in various degenerative diseases and malignancies. The hallmark of ferroptosis is uncontrolled and overwhelming peroxidation of polyunsaturated fatty acids contained in membrane phospholipids, which eventually leads to rupture of the plasma membrane. Ferroptosis is unique in that it is essentially a spontaneous, uncatalyzed chemical process based on perturbed iron and redox homeostasis contributing to the cell death process, but that it is nonetheless modulated by many metabolic nodes that impinge on the cells' susceptibility to ferroptosis. Among the various nodes affecting ferroptosis sensitivity, several have emerged as promising candidates for pharmacological intervention, rendering ferroptosis-related proteins attractive targets for the treatment of numerous currently incurable diseases. Herein, the current members of a Germany-wide research consortium focusing on ferroptosis research, as well as key external experts in ferroptosis who have made seminal contributions to this rapidly growing and exciting field of research, have gathered to provide a comprehensive, state-of-the-art review on ferroptosis. Specific topics include: basic mechanisms, in vivo relevance, specialized methodologies, chemical and pharmacological tools, and the potential contribution of ferroptosis to disease etiopathology and progression. We hope that this article will not only provide established scientists and newcomers to the field with an overview of the multiple facets of ferroptosis, but also encourage additional efforts to characterize further molecular pathways modulating ferroptosis, with the ultimate goal to develop novel pharmacotherapies to tackle the various diseases associated with - or caused by - ferroptosis.

Strategic design and development of a siderophore mimic: pioneering anticancer therapy via ROS generation and ferroptosis

We designed a tris-catecholate-based siderophore mimic, H6-T-CATL, to selectively chelate iron(III) from mitochondrial cytochromes and other iron-containing proteins within cellular matrices. This strategic sequestration aims to trigger apoptosis or ferroptosis in cancer cells through the glutathione (GSH)-dependent release of reduced iron and subsequent ROS-mediated cytotoxicity. Synthesis of H6-T-CATL involved precise peptide coupling reactions. Using the Fe(III)-porphyrin model (Fe-TPP-Cl), akin to cytochrome c, we studied H6-T-CATL's ability to extract iron(III), yielding a binding constant (Krel) of 1014 for the resulting iron(III) complex (FeIII-T-CATL)3-. This complex readily underwent GSH-mediated reduction to release bioavailable iron(II), which catalyzed Fenton-like reactions generating hydroxyl radicals (˙OH), confirmed by spectroscopic analyses. Our research underscores the potential of H6-T-CATL to induce cancer cell death by depleting iron(III) from cellular metalloproteins, releasing pro-apoptotic iron(II). Evaluation across various cancer types, including normal cells, demonstrated H6-T-CATL's cytotoxicity through ROS production, mitochondrial dysfunction, and activation of ferroptosis and DNA damage pathways. These findings propose a novel mechanism for cancer therapy, leveraging endogenous iron stores within cells. H6-T-CATL emerges as a promising next-generation anticancer agent, exploiting iron metabolism vulnerabilities to induce selective cancer cell death through ferroptosis induction.

A platinum(IV)-artesunate complex triggers ferroptosis by boosting cytoplasmic and mitochondrial lipid peroxidation to enhance tumor immunotherapy

Ferroptosis is an iron-dependent cell death form that initiates lipid peroxidation (LPO) in tumors. In recent years, there has been growing interest on ferroptosis, but how to propel it forward translational medicine remains in mist. Although experimental ferroptosis inducers such as RSL3 and erastin have demonstrated bioactivity in vitro, the poor antitumor outcome in animal model limits their development. In this study, we reveal a novel ferroptosis inducer, oxaliplatin-artesunate (OART), which exhibits substantial bioactivity in vitro and vivo, and we verify its feasibility in cancer immunotherapy. For mechanism, OART induces cytoplasmic and mitochondrial LPO to promote tumor ferroptosis, via inhibiting glutathione-mediated ferroptosis defense system, enhancing iron-dependent Fenton reaction, and initiating mitochondrial LPO. The destroyed mitochondrial membrane potential, disturbed mitochondrial fusion and fission, as well as downregulation of dihydroorotate dehydrogenase mutually contribute to mitochondrial LPO. Consequently, OART enhances tumor immunogenicity by releasing damage associated molecular patterns and promoting antigen presenting cells maturation, thereby transforming tumor environment from immunosuppressive to immunosensitive. By establishing in vivo model of tumorigenesis and lung metastasis, we verified that OART improves the systematic immune response. In summary, OART has enormous clinical potential for ferroptosis-based cancer therapy in translational medicine.

Adaptations of membrane trafficking in cancer and tumorigenesis

Membrane trafficking, a fundamental cellular process encompassing the transport of molecules to specific organelles, endocytosis at the plasma membrane and protein secretion, is crucial for cellular homeostasis and signalling. Cancer cells adapt membrane trafficking to enhance their survival and metabolism, and understanding these adaptations is vital for improving patient responses to therapy and identifying therapeutic targets. In this Review, we provide a concise overview of major membrane trafficking pathways and detail adaptations in these pathways, including COPII-dependent endoplasmic reticulum (ER)-to-Golgi vesicle trafficking, COPI-dependent retrograde Golgi-to-ER trafficking and endocytosis, that have been found in cancer. We explore how these adaptations confer growth advantages or resistance to cell death and conclude by discussing the potential for utilising this knowledge in developing new treatment strategies and overcoming drug resistance for cancer patients.

Ironing out the role of ferroptosis in immunity

Ferroptosis is a type of regulated cell death that drives the pathophysiology of many diseases. Oxidative stress is detectable in many types of regulated cell death, but only ferroptosis involves lipid peroxidation and iron dependency. Ferroptosis originates and propagates from several organelles, including the mitochondria, endoplasmic reticulum, Golgi, and lysosomes. Recent data have revealed that immune cells can both induce and undergo ferroptosis. A mechanistic understanding of how ferroptosis regulates immunity is critical to understanding how ferroptosis controls immune responses and how this is dysregulated in disease. Translationally, more work is needed to produce ferroptosis-modulating immunotherapeutics. This review focuses on the role of ferroptosis in immune-related diseases, including infection, autoimmune diseases, and cancer. We discuss how ferroptosis is regulated in immunity, how this regulation contributes to disease pathogenesis, and how targeting ferroptosis may lead to novel therapies.

Ferroptosis: a potential therapeutic target for stroke

Ferroptosis is a form of regulated cell death characterized by massive iron accumulation and iron-dependent lipid peroxidation, differing from apoptosis, necroptosis, and autophagy in several aspects. Ferroptosis is regarded as a critical mechanism of a series of pathophysiological reactions after stroke because of iron overload caused by hemoglobin degradation and iron metabolism imbalance. In this review, we discuss ferroptosis-related metabolisms, important molecules directly or indirectly targeting iron metabolism and lipid peroxidation, and transcriptional regulation of ferroptosis, revealing the role of ferroptosis in the progression of stroke. We present updated progress in the intervention of ferroptosis as therapeutic strategies for stroke in vivo and in vitro and summarize the effects of ferroptosis inhibitors on stroke. Our review facilitates further understanding of ferroptosis pathogenesis in stroke, proposes new targets for the treatment of stroke, and suggests that more efforts should be made to investigate the mechanism of ferroptosis in stroke.

Ether lipids influence cancer cell fate by modulating iron uptake

Cancer cell fate has been widely ascribed to mutational changes within protein-coding genes associated with tumor suppressors and oncogenes. In contrast, the mechanisms through which the biophysical properties of membrane lipids influence cancer cell survival, dedifferentiation and metastasis have received little scrutiny. Here, we report that cancer cells endowed with a high metastatic ability and cancer stem cell-like traits employ ether lipids to maintain low membrane tension and high membrane fluidity. Using genetic approaches and lipid reconstitution assays, we show that these ether lipid-regulated biophysical properties permit non-clathrin-mediated iron endocytosis via CD44, leading directly to significant increases in intracellular redox-active iron and enhanced ferroptosis susceptibility. Using a combination of in vitro three-dimensional microvascular network systems and in vivo animal models, we show that loss of ether lipids also strongly attenuates extravasation, metastatic burden and cancer stemness. These findings illuminate a mechanism whereby ether lipids in carcinoma cells serve as key regulators of malignant progression while conferring a unique vulnerability that can be exploited for therapeutic intervention.

A Cancer Nanovaccine Based on an FeAl-Layered Double Hydroxide Framework for Reactive Oxygen Species-Augmented Metalloimmunotherapy

The complexity and heterogeneity of individual tumors have hindered the efficacy of existing therapeutic cancer vaccines, sparking intensive interest in the development of more effective in situ vaccines. Herein, we introduce a cancer nanovaccine for reactive oxygen species-augmented metalloimmunotherapy in which FeAl-layered double hydroxide (LDH) is used as a delivery vehicle with dihydroartemisinin (DHA) as cargo. The LDH framework is acid-labile and can be degraded in the tumor microenvironment, releasing iron ions, aluminum ions, and DHA. The iron ions contribute to aggravated intratumoral oxidative stress injury by the synergistic Fenton reaction and DHA activation, causing apoptosis, ferroptosis, and immunogenic cell death in cancer cells. The subsequently released tumor-associated antigens with the aluminum adjuvant form a cancer nanovaccine to generate robust and long-term immune responses against cancer recurrence and metastasis. Moreover, Fe ion-enabled T1-weighted magnetic resonance imaging can facilitate real-time tumor therapy monitoring. This cancer-nanovaccine-mediated metalloimmunotherapy strategy has the potential for revolutionizing the precision immunotherapy landscape.

Mechanisms controlling cellular and systemic iron homeostasis

In mammals, hundreds of proteins use iron in a multitude of cellular functions, including vital processes such as mitochondrial respiration, gene regulation and DNA synthesis or repair. Highly orchestrated regulatory systems control cellular and systemic iron fluxes ensuring sufficient iron delivery to target proteins is maintained, while limiting its potentially deleterious effects in iron-mediated oxidative cell damage and ferroptosis. In this Review, we discuss how cells acquire, traffick and export iron and how stored iron is mobilized for iron-sulfur cluster and haem biogenesis. Furthermore, we describe how these cellular processes are fine-tuned by the combination of various sensory and regulatory systems, such as the iron-regulatory protein (IRP)-iron-responsive element (IRE) network, the nuclear receptor co-activator 4 (NCOA4)-mediated ferritinophagy pathway, the prolyl hydroxylase domain (PHD)-hypoxia-inducible factor (HIF) axis or the nuclear factor erythroid 2-related factor 2 (NRF2) regulatory hub. We further describe how these pathways interact with systemic iron homeostasis control through the hepcidin-ferroportin axis to ensure appropriate iron fluxes. This knowledge is key for the identification of novel therapeutic opportunities to prevent diseases of cellular and/or systemic iron mismanagement.

Diapause-like Drug-Tolerant Persister State: The Key to Nirvana Rebirth

Cancer is one of the leading causes of death in the world. Various drugs have been developed to eliminate it but to no avail because a tumor can go into dormancy to avoid therapy. In the past few decades, tumor dormancy has become a popular topic in cancer therapy. Recently, there has been an important breakthrough in the study of tumor dormancy. That is, cancer cells can enter a reversible drug-tolerant persister (DTP) state to avoid therapy, but no exact mechanism has been found. The study of the link between the DTP state and diapause seems to provide an opportunity for a correct understanding of the mechanism of the DTP state. Completely treating cancer and avoiding dormancy by targeting the expression of key genes in diapause are possible. This review delves into the characteristics of the DTP state and its connection with embryonic diapause, and possible treatment strategies are summarized. The authors believe that this review will promote the development of cancer therapy.

Ferroptosis and its modulators: A raising target for cancer and Alzheimer's disease

The process of ferroptosis, a recently identified form of regulated cell death (RCD) is associated with the overloading of iron species and lipid-derived ROS accumulation. Ferroptosis is induced by various mechanisms such as inhibiting system Xc, glutathione depletion, targeting excess iron, and directly inhibiting GPX4 enzyme. Also, ferroptosis inhibition is achieved by blocking excessive lipid peroxidation by targeting different pathways. These mechanisms are often related to the pathophysiology and pathogenesis of diseases like cancer and Alzheimer's. Fundamentally distinct from other forms of cell death, such as necrosis and apoptosis, ferroptosis differs in terms of biochemistry, functions, and morphology. The mechanism by which ferroptosis acts as a regulatory factor in many diseases remains elusive. Studying the activation and inhibition of ferroptosis as a means to mitigate the progression of various diseases is a highly intriguing and actively researched topic. It has emerged as a focal point in etiological research and treatment strategies. This review systematically summarizes the different mechanisms involved in the inhibition and induction of ferroptosis. We have extensively explored different agents that can induce or inhibit ferroptosis. This review offers current perspectives on recent developments in ferroptosis research, highlighting the disease's etiology and presenting references to enhance its understanding. It also explores new targets for the treatment of cancer and Alzheimer's disease.

Experimental and DFT Study of Monensinate and Salinomycinate Complexes Containing {Fe3(µ3-O)}7+ Core

Two trinuclear oxo-centred iron(III) coordination compounds of monensic and salinomycinic acids (HL) were synthesized and their spectral properties were studied using physicochemical/thermal methods (FT-IR, TG-DTA, TG-MS, EPR, Mössbauer spectroscopy, powder XRD) and elemental analysis. The data suggested the formation of [Fe3(µ3-O)L3(OH)4] and the probable complex structures were modelled using the DFT method. The computed spectral parameters of the optimized constructs were compared to the experimentally measured ones. In each complex, three metal centres were joined together at the axial position by a μ3-O unit to form a {Fe3O}7+ core. The antibiotics monoanions served as bidentate ligands through the carboxylate and hydroxyl groups located at the termini. The carboxylate moieties played a dual role bridging each two metal centres. Hydroxide anions secured the overall neutral character of the coordination species. Mössbauer spectra displayed asymmetric quadrupole doublets that were consistent with the existence of two types of high-spin iron(III) sites with different environments-two Fe[O5] and one Fe[O6] centres. The solid-state EPR studies confirmed the +3 oxidation state of iron with a total spin St = 5/2 per trinuclear cluster. The studied complexes are the first iron(III) coordination compounds of monensin and salinomycin reported so far.

Ferroptosis resistance in cancer: recent advances and future perspectives

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death and has been implicated in the occurrence and development of various diseases, including heart disease, nervous system diseases and cancer. Ferroptosis induction recently emerged as an attractive strategy for cancer therapy. Ferroptosis has become a potential target for intervention in these diseases or injuries in relevant preclinical models. This review summarizes recent progress on the mechanisms of ferroptosis resistance in cancer, highlights redox status and metabolism's role in it. Combination therapy for ferroptosis has great potential in cancer treatment, especially malignant tumors that are resistant to conventional therapies. This review will lead us to have a comprehensive understanding of the future exploration of ferroptosis and cancer therapy. A deeper understanding of the relationship between ferroptosis resistance and metabolism reprogramming may provide new strategies for tumor treatment and drug development based on ferroptosis.

Beyond ferrostatin-1: a comprehensive review of ferroptosis inhibitors

Ferroptosis is an iron-catalysed form of regulated cell death, which is critically dependent on phospholipid peroxidation of cellular membranes. Ferrostatin 1 was one of the first synthetic radical-trapping antioxidants (RTAs) reported to block ferroptosis and it is widely used as reference compound. Ferroptosis has been linked to multiple diseases and the use of its inhibitors could have therapeutic potential. Although, novel biochemical pathways provide insights for different pharmacological targets, the use of lipophilic RTAs to block ferroptosis remains superior. In this Review, we provide a comprehensive overview of the different classes of ferroptosis inhibitors, focusing on endogenous and synthetic RTAs. A thorough analysis of their chemical, pharmacokinetic, and pharmacological properties and potential for in vivo use is provided.

Biomimetic inducer enabled dual ferroptosis of tumor and M2-type macrophages for enhanced tumor immunotherapy

Tumor-associated macrophages (TAMs) are abundant in the tumor microenvironment which promotes the formation of the immunosuppressive tumor microenvironment (ITME) through multiple mechanisms, severely counteracting the therapeutic efficacy of immunotherapy. In this study, a novel biomimetic ferroptosis inducer (D@FMN-M) capable of ITME regulation for enhanced cancer ferroptosis immunotherapy is reported. Upon tumor accumulation of D@FMN-M, the intratumoral mild acidity triggers the biodegradation of Fe-enriched nanocarriers and the concurrent co-releases of dihydroartemisinin (DHA) and Fe3+. The released Fe3+ is reduced to Fe2+ by consuming intratumoral glutathione (GSH), which promotes abundant free radical generation via triggering Fenton and Fe2+-DHA reactions, thus inducing ferroptosis of both cancer cells and M2-type TAMs. Resultantly, the anticancer immune response is strongly activated by the massive tumor-associated antigens released by ferroptositic cancer cells. Also importantly, the ferroptosis-sensitive M2-type TAMs will be either damaged or gradually domesticated to ferroptosis-resistant M1 TAMs under the ferroptosis stress, favoring the normalization of ITME and finally amplifying cancer ferroptosis immunotherapeutic efficacy. This work provides a novel strategy for ferroptosis immunotherapy of solid tumors featuring TAMs infiltration and immunosuppression by inducing dual ferroptosis of tumor cells and M2-type TAMs.

Drug-tolerant persister cells in cancer: the cutting edges and future directions

Drug-tolerant persister (DTP) cell populations were originally discovered in antibiotic-resistant bacterial biofilms. Similar populations with comparable features have since been identified among cancer cells and have been linked with treatment resistance that lacks an underlying genomic alteration. Research over the past decade has improved our understanding of the biological roles of DTP cells in cancer, although clinical knowledge of the role of these cells in treatment resistance remains limited. Nonetheless, targeting this population is anticipated to provide new treatment opportunities. In this Perspective, we aim to provide a clear definition of the DTP phenotype, discuss the underlying characteristics of these cells, their biomarkers and vulnerabilities, and encourage further research on DTP cells that might improve our understanding and enable the development of more effective anticancer therapies.

Sonocatalytic In Situ Induced Oxygen Storm Precision Enhanced Reactive Oxygen Therapy for Pancreatic Cancer

Deep‐buried tissue, extremely hypoxic blood supply, and complex tumor microenvironment are considered to be the hardest difficult barriers to the accurate treatment of pancreatic cancer. Herein, a novel Au@Co3O4 (AC)‐polyvinylpyrrolidone (AC‐PVP) sonocatalytic agent and radiation sensitizer with a multicore–shell structure are synthesized by a mild reduction method for reshaping the special physiological environment of pancreatic cancer. Oxygen storms can be generated under ultrasonic activation by in situ catalyzed H2O2 in tumor tissue. The oxygen storm improves the ability to produce superoxide anions by sonodynamic therapy as well as rapidly supplements the oxygen‐dependent on active oxygen such as auger electrons produced by high‐energy ray ionization during radiotherapy (RT), further enhancing the efficiency of RT. Interestingly, AC‐PVP can reduce the intracellular glutathione (GSH) level, thus preventing the generated reactive oxygen species from being consumed by GSH. More importantly, the glucose oxidase‐like of AC‐PVP can catalyze glucose in tumor tissue to produce H2O2, and continuously provide substrates for sonocatalytic to form self‐cycling oxygen production. This study offers a novel paradigm for achieving in situ precise self‐oxygenation to overcome the special physiological barrier of pancreatic cancer and efficient sonodynamic synergistic radiotherapy.

Recent advances of ferroptosis in tumor: From biological function to clinical application

Ferroptosis is a recently recognized form of cell death with distinct features in terms of morphology, biochemistry, and molecular mechanisms. Unlike other types of cell death, ferroptosis is characterized by iron dependence, reactive oxygen species accumulation and lipid peroxidation. Recent studies have demonstrated that selective autophagy plays a vital role in the induction of ferroptosis, including ferritinophagy, lipophagy, clockophagy, and chaperone-mediated autophagy. Emerging evidence has indicated the involvement of ferroptosis in tumorigenesis through regulating various biological processes, including tumor growth, metastasis, stemness, drug resistance, and recurrence. Clinical and preclinical studies have found that novel therapies targeting ferroptosis exert great potential in the treatment of tumors. This review provides a comprehensive overview of the molecular mechanisms in ferroptosis, especially in autophagy-driven ferroptosis, discusses the recent advances in the biological roles of ferroptosis in tumorigenesis, and highlights the application of novel ferroptosis-targeted therapies in the clinical treatment of tumors.

Combination therapy to overcome ferroptosis resistance by biomimetic self-assembly nano-prodrug

Ferroptosis has emerged as a potent form of no-apoptotic cell death that offers a promising alternative to avoid the chemoresistance of apoptotic pathways and serves as a vulnerability of cancer. Herein, we have constructed a biomimetic self-assembly nano-prodrug system that enables the co-delivery of gefitinib (Gefi), ferrocene (Fc) and dihydroartemisinin (DHA) for the combined therapy of both ferroptosis and apoptosis. In the tumor microenvironment, this nano-prodrug is able to disassemble and trigger drug release under high levels of GSH. Interestingly, the released DHA can downregulate GPX4 level for the enhancement of intracellular ferroptosis from Fc, further executing tumor cell death with concomitant chemotherapy by Gefi. More importantly, this nano-prodrug provides highly homologous targeting ability by coating related cell membranes and exhibits outstanding inhibition of tumor growth and metastasis, as well as no noticeable side-effects during treatments. This simple small molecular self-assembled nano-prodrug provides a new reasonably designed modality for ferroptosis-combined chemotherapy.

Screening and identification of genes related to ferroptosis in keratoconus

Corneal keratoconus (KC) is a dilated (ectatic) corneal disease characterized by a central thinning of the cornea, which causes protrusion into a conical shape that seriously affects vision. However, due to the complex etiology of keratoconus, its entire mechanism remains unclear and there is no mechanism-directed treatment method. Ferroptosis is a novel programmed cell death mechanism related to lipid peroxidation, stress, and amino acid metabolism, which plays a crucial role in various diseases. This study aimed to explore the relationship between keratoconus and ferroptosis, to provide new insights into the mechanism of keratoconus development, and potential treatment options based on further elucidation of this mechanism. The corresponding mRNA microarray expression matrix data of KC patients were obtained from GEO database (GSE204791). Weighted co-expression network analysis (WGCNA) and support vector machine recursive feature elimination (SVM-RFE) were selected to screen hub genes, which were overlapped with ferroptosis genes (FRGs) from FerrDb. GO and GSEA were performed to analyze differential pathways, ssGSEA was used to determine immune status, and then, feasible drugs were predicted by gene-drug network. Additionally, we predicted the miRNA and IncRNA of hub genes to identify the underlying mechanism of disease so as to predict treatment for the disease. The epithelial transcriptome from keratoconus tissue mRNA microarray data (GSE204791) was extracted for the main analysis, including eight epithelial cells and eight epithelial control cells. The differential genes that were overlapped by WGCAN, SVM-RFE and FRGs were mainly related to oxidative stress, immune regulation, cellular inflammation, and metal ion transport. Through further analysis, aldo-keto reductase family 1 member C3 (AKR1C3) was selected, and negatively correlated with mature CD56 natural killer (NK) cells and macrophages. Then, gene-drug interaction network analysis and miRNA prediction were performed through the website. It was concluded that four immune-related drugs (INDOMETHACIN, DAUNORUBICIN, DOXORUBICIN, DOCETAXEL) and a miRNA (has-miR-184) were screened to predict potential drugs and targets for disease treatment. To our knowledge, this was the first report of KC being associated with ferroptosis and prompted search for differential genes to predict drug targets of gene immunotherapy. Our findings provided insight and a solid basis for the analysis and treatment of KC.

Ferroptosis and EMT: key targets for combating cancer progression and therapy resistance

Iron-dependent lipid peroxidation causes ferroptosis, a form of regulated cell death. Crucial steps in the formation of ferroptosis include the accumulation of ferrous ions (Fe2+) and lipid peroxidation, of which are controlled by glutathione peroxidase 4 (GPX4). Its crucial role in stopping the spread of cancer has been shown by numerous studies undertaken in the last ten years. Epithelial-mesenchymal transition (EMT) is the process by which epithelial cells acquire mesenchymal characteristics. EMT is connected to carcinogenesis, invasiveness, metastasis, and therapeutic resistance in cancer. It is controlled by a range of internal and external signals and changes the phenotype from epithelial to mesenchymal like. Studies have shown that mesenchymal cancer cells tend to be more ferroptotic than their epithelial counterparts. Drug-resistant cancer cells are more easily killed by inducers of ferroptosis when they undergo EMT. Therefore, understanding the interaction between ferroptosis and EMT will help identify novel cancer treatment targets. In-depth discussion is given to the regulation of ferroptosis, the potential application of EMT in the treatment of cancer, and the relationships between ferroptosis, EMT, and signaling pathways associated with tumors. Invasion, metastasis, and inflammation in cancer all include ferroptosis and EMT. The goal of this review is to provide suggestions for future research and practical guidance for applying ferroptosis and EMT in clinical practice.

Targeting regulated cell death pathways in acute myeloid leukemia

The use of the BCL2 inhibitor venetoclax has transformed the management of patients with acute myeloid leukemia (AML) who are ineligible for intensive chemotherapy. By triggering intrinsic apoptosis, the drug is an excellent illustration of how our greater understanding of molecular cell death pathways can be translated into the clinic. Nevertheless, most venetoclax-treated patients will relapse, suggesting the need to target additional regulated cell death pathways. To highlight advances in this strategy, we review the recognized regulated cell death pathways, including apoptosis, necroptosis, ferroptosis and autophagy. Next, we detail the therapeutic opportunities to trigger regulated cell death in AML. Finally, we describe the main drug discovery challenges for regulated cell death inducers and their translation into clinical trials. A better knowledge of the molecular pathways regulating cell death represents a promising strategy to develop new drugs to cure resistant or refractory AML patients, particularly those resistant to intrinsic apoptosis.

Epithelial-Mesenchymal Plasticity: Implications for Ferroptosis Vulnerability and Cancer Therapy

Cancers polarized to a mesenchymal or poorly differentiated state can often evade cell death induced by conventional therapies. The epithelial-mesenchymal transition is involved in lipid metabolism and increases polyunsaturated fatty acid levels in cancer cells, contributing to chemo- and radio-resistance. Altered metabolism in cancer enables invasion and metastasis but is prone to lipid peroxidation under oxidative stress. Cancers with mesenchymal rather than epithelial signatures are highly vulnerable to ferroptosis. Therapy-resistant persister cancer cells show a high mesenchymal cell state and dependence on the lipid peroxidase pathway, which can respond more sensitively to ferroptosis inducers. Cancer cells may survive under specific metabolic and oxidative stress conditions, and targeting this unique defense system can selectively kill only cancer cells. Therefore, this article summarizes the core regulatory mechanisms of ferroptosis in cancer, the relationship between ferroptosis and epithelial-mesenchymal plasticity, and the implications of epithelial-mesenchymal transition for ferroptosis-based cancer therapy.

Local delivery of artesunate dimer liposomes incorporated injectable hydrogel for H2O2 and pH-independent chemodynamic therapy

Chemodynamic therapy (CDT) has emerged as a powerful tumor treatment option by inducing the imbalance of redox homeostasis in cancer cells. Nevertheless, the therapeutic outcomes were greatly limited because of insufficient endogenous H₂O₂ and upregulated cellular antioxidant defense in the tumor microenvironment (TME). Herein, a liposome-incorporated in-situ alginate hydrogel locoregional treatment strategy was developed, which involves using hemin-loaded artesunate dimer liposomes (HAD-LP) as redox-triggered self-amplified C-center free radical nanogenerator to enhance CDT. First, HAD-LP based on artesunate dimer glycerophosphocholine (ART-GPC) was prepared by a thin film method. Their spherical structure was manifested by dynamic light scattering (DLS) and transmission electron microscope (TEM). The generation of C-center free radicals from HAD-LP was carefully evaluated by using methylene blue (MB) degradation method. The results suggested that the hemin was reduced to heme under the action of glutathione (GSH), which could catalyze the breakage of endoperoxide of ART-GPC derived dihydroartemisinin (DHA) to generate toxic C-centered free radicals in a H₂O₂ and pH-independent manner. Moreover, the change of intracellular GSH and free radical level was monitored through ultraviolet spectroscopy and confocal laser scanning microscope (CLSM). It was revealed that the hemin reduction induced GSH depletion and elevated free radical level, disrupting cellular redox homeostasis. After co-incubation with MDA-MB-231 or 4 T1 cells, HAD-LP was found to be highly cytotoxic. In order to prolong retention and improve antitumor efficacy, HAD-LP was mixed with alginate and injected intratumorally into 4 T1 tumor bearing mice. The injected HAD-LP and alginate mixture formed in-situ hydrogel and achieved best antitumor effect with the growth inhibition rate of 72.6%. Together, the hemin-loaded artesunate dimer liposome-incorporated alginate hydrogel possessed effective antitumor activity through redox-triggered C-center free radical generation induced apoptosis in a H₂O₂ and pH-independent manner, which might be a promising candidate in the application of chemodynamic anti-tumor therapy.

Redox signaling in drug-tolerant persister cells as an emerging therapeutic target

Drug-tolerant persister (DTP) cells have attracted significant interest, given their predominant role in treatment failure. In this respect, DTP cells reportedly survive after anticancer drug exposure, and their DNA repair mechanisms are altered to enhance adaptive mutation, accounting for the emergence of drug-resistant mutations. DTP cells resume proliferation upon treatment withdrawal and are responsible for cancer relapse. Current evidence suggests that DTP cells mediate redox signaling-mediated cellular homeostasis by developing various adaptive mechanisms, especially metabolic reprogramming that promotes mitochondrial oxidative respiration and a robust antioxidant process. There is an increasing consensus that disrupting redox homeostasis by intervening with redox signaling is theoretically a promising therapeutic strategy for targeting these sinister cells. In this review, we provide a comprehensive overview of the characteristics of DTP cells and the underlying mechanisms involved in redox signaling, aiming to provide a unique perspective on potential therapeutic applications based on their vulnerabilities to redox regulation.

Bioinorganic Modulators of Ferroptosis: A Review of Recent Findings

Ferroptosis was first reported as a separate modality of regulated cell death in 2008 and distinguished under its current name in 2012 after it was first induced with erastin. In the following decade, multiple other chemical agents were researched for their pro- or anti-ferroptotic properties. Complex organic structures with numerous aromatic moieties make up the majority of this list. This review fills a more overlooked niche by gathering, outlining and setting out conclusions regarding less prominent cases of ferroptosis induced by bioinorganic compounds and reported on within the last few years. The article contains a short summary of the application of bioinorganic chemicals based on gallium, several chalcogens, transition metals and elements known as human toxicants used for the purpose of evoking ferroptotic cell death in vitro or in vivo. These are used in the form of free ions, salts, chelates, gaseous and solid oxides or nanoparticles. Knowledge of how exactly these modulators promote or inhibit ferroptosis could be beneficial in the context of future therapies aimed against cancer or neurodegenerative diseases, respectively.

Targeting ferroptosis: Paving new roads for drug design and discovery

Ferroptosis, first proposed in 2012, is an iron-dependent form of regulated cell death characterized by excessive polyunsaturated fatty acid oxidation. In the past decade, researchers have revealed the formation and mechanisms of ferroptosis. Cancer drug resistance can be reversed by ferroptosis induction, and inhibiting ferroptosis has been shown to block certain disease processes. As a result, several ferroptosis-targeting drugs have been developed. However, the first-generation ferroptosis-targeting agents remain hampered from clinical use, mainly due to poor selectivity and pharmacokinetics. The discoveries of FSP1, GCH1, and other potential ferroptosis-regulating pathways independent of Xc^--GSH-GPX4 provide novel targets for drug design. Recently, protein-targeted degradation and antibody-drug conjugate strategy show promise in future drug design. With novel targets, further optimizations, and new technologies, the next-generation ferroptosis-targeting agents show a promising future with improved selectivity and efficacy. In this review, we summarize mechanisms, target types, drug design, and novel technologies of ferroptosis, aiming to pave the way for future drug design and discovery in the next decade.

Nanotechnology-integrated ferroptosis inducers: a sharp sword against tumor drug resistance

Presently, the biggest hurdle to cancer therapy is the inevitable emergence of drug resistance. Since conventional therapeutic schedules fall short of the expectations in curbing drug resistance, the development of novel drug resistance management strategies is critical. Extensive research over the last decade has revealed that the process of ferroptosis is correlated with cancer resistance; moreover, it has been demonstrated that ferroptosis inducers reverse drug resistance. To elucidate the development and promote the clinical transformation of ferroptosis strategies in cancer therapy, we first analyzed the roles of key ferroptosis-regulating molecules in the progression of drug resistance in-depth and then reviewed the design of ferroptosis-inducing strategies based on nanotechnology for overcoming drug resistance, including glutathione depletion, reactive oxygen species generation, iron donation, lipid peroxidation aggregation, and multiple-drug resistance-associated tumor cell destruction. Finally, the prospects and challenges of regulating ferroptosis as a therapeutic strategy for reversing cancer therapy resistance were evaluated. This review aimed to provide a comprehensive understanding for researchers to develop ferroptosis-inducing nanoplatforms that can overcome drug resistance.

A reactive oxygen species-replenishing coordination polymer nanomedicine disrupts redox homeostasis and induces concurrent apoptosis-ferroptosis for combinational cancer therapy

Reactive oxygen species (ROS) are important signal molecules and imbalanced ROS level could lead to cell death. Elevated ROS levels in tumor tissues offer an opportunity to design ROS-responsive drug delivery systems (DDSs) or ROS-based cancer therapy such as chemodynamic therapy. However, their anticancer efficacies are hampered by the ROS-consuming nature of these DDSs as well as the high concentration of reductive agents like glutathione (GSH). Here we developed a doxorubicin (DOX)-incorporated iron coordination polymer nanoparticle (PCFD) for efficient chemo-chemodynamic cancer therapy by using a cinnamaldehyde (CA)-based ROS-replenishing organic ligand (TCA). TCA can ROS-responsively release CA to supplement intracellular ROS and deplete GSH by a thiol-Michael addition reaction, which together with DOX-triggered ROS upregulation and Fe³⁺-enabled GSH depletion facilitated efficient DOX release and enhanced Fenton reaction, thereby inducing redox dyshomeostasis and cancer cell death in a concurrent apoptosis-ferroptosis way. Both in vitro and in vivo study revealed that ROS-replenishing PCFD exhibited much better anticancer effect than ROS-consuming control nanoparticle PAFD. The ingenious ROS-replenishing strategy could be expanded to construct versatile ROS-responsive DDSs and ROS-based nanomedicines with potentiated anticancer activity. STATEMENT OF SIGNIFICANCE: We develop a doxorubicin (DOX)-incorporated iron coordination polymer nanoparticle (PCFD) for efficient chemo-chemodynamic cancer therapy by using a cinnamaldehyde-based reactive oxygen species (ROS)-replenishing organic ligand. This functional ligand can ROS-responsively release cinnamaldehyde to supplement intracellular H₂O₂ and deplete glutathione (GSH) by a thiol-Michael addition reaction, which together with DOX-triggered ROS upregulation and Fe³⁺-enabled GSH depletion facilitates efficient DOX release and enhanced Fenton reaction, thereby inducing redox dyshomeostasis and cancer cell death in a concurrent apoptosis-ferroptosis way. Both in vitro and in vivo study reveal that ROS-replenishing PCFD exhibit much better anticancer effect than ROS consuming counterpart. This study provides a facile and straightforward strategy to design ROS amplifying nanoplatforms for cancer treatment.