Discovery of Novel Potent Covalent Glutathione Peroxidase 4 Inhibitors as Highly Selective Ferroptosis Inducers for the Treatment of Triple-Negative Breast Cancer

A novel cyanine photosensitizer for sequential dual-site GSH depletion and ROS-potentiated cancer photodynamic therapy

The efficacy of photodynamic therapy (PDT) is often limited by the reductive microenvironment in tumor cells due to the high level of glutathione (GSH) and glutathione peroxidase 4 (GPX4), which maintain redox homeostasis. Therefore, designing a GSH-responsive photosensitizer that depletes intracellular GSH is a promising strategy to enhance PDT selectivity and efficacy. Herein, we present a GSH-selective sequentially responsive theranostic photosensitizer, Cy-Res. This cyanine agent targeting mitochondria effectively depletes two GSH molecules, leading to the generation of abundant ROS and exacerbating oxidative stress. Additionally, it achieves an 80-fold fluorescence enhancement upon response to GSH, enabling selective imaging of tumor cells. By mitigating GSH's impact on PDT, Cy-ResNPs achieves synergistic and efficient PDT treatment of invasive melanoma under low-power irradiation (808 nm, 80 mW/cm2). The inhibitory processes downregulate GPX4, increase apoptotic proteins like Bax, and promote mixed cell death involving both ferroptosis and apoptosis. Overall, this study offers new insights and strategies for the development of GSH-responsive theranostic agents, highlighting their potential for application in tumor diagnosis and therapy.

Computational discovery of novel GPX4 inhibitors from herbal sources as potential ferroptosis inducers in cancer therapy

Ferroptosis, a cell death regulation process dependent on iron levels, represents a promising therapeutic target in cancer treatment. However, the scarcity of potent ferroptosis inducers hinders advancement in this area. This study addresses this gap by screening the PubChem database for compounds with favorable ADMET properties to identify potential GPX4 inhibitors. A structure-based virtual screening was conducted to compare binding affinities of selected compounds to that of RSL3. The candidates-isochondrodendrine, hinokiflavone, irinotecan, and ginkgetin-were further analyzed through molecular dynamics (MD) simulations to assess their stability within the GPX4-ligand complexes. The computed binding free energies for RSL3, isochondrodendrine, hinokiflavone, irinotecan and ginkgetin were -80.12, -107.31, -132.03, and -137.52 and -91.11 kJ/mol, respectively, indicating their significantly higher inhibitory effects compared to RSL3. These findings highlight the potential for developing novel GPX4 inhibitors to promote ferroptosis, warranting further experimental validation.

An overview of GPX4-targeting TPDs for cancer therapy

Ferroptosis is a newly identified form of regulated, non-apoptotic cell death caused by iron-dependent phospholipid peroxidation. Glutathione peroxidase 4 (GPX4) inactivation-induced ferroptosis is an efficient antitumor treatment. Currently, several GPX4 inhibitors have been identified. However, these inhibitors exhibit low selectivity and poor pharmacokinetic properties that preclude their clinical use. Targeted protein degradation (TPD) is an efficient strategy for discovering drugs and has unique advantages over target protein inhibition. Given GPX4's antitumor effects and the potential of TPD, researchers have explored GPX4-targeting TPDs, which outperform conventional inhibitors in several aspects, such as increased selectivity, strong anti-proliferative effects, overcoming drug resistance, and enhancing drug-like properties. In this review, we comprehensively summarize the progress in GPX4-targeting TPDs. In addition, we reviewed the changes and challenges related to the development of GPX4-targeting TPDs for cancer therapy.

A prospective therapeutic strategy: GPX4-targeted ferroptosis mediators

As a crucial regulator of oxidative homeostasis, seleno-protein glutathione peroxidase 4 (GPX4) represents the primary defense system against ferroptosis, making it a promising target with important clinical application prospects. From the discovery of covalent and allosteric sites in GPX4, substantial advancements in GPX4-targeted small molecules have been made through diverse discovery and design strategies in recent years. Moreover, as an emerging hotspot in drug development, seleno-organic compounds can functionally mimic GPX4 to reduce hydroperoxides. To facilitate the further development of selective ferroptosis mediators as potential pharmaceutical agents, this review comprehensively covers all GPX4-targeted small molecules, including inhibitors, degraders, and activators. In addition, seleno-organic compounds as GPX mimics are also included. We also provide perspectives regarding challenges and future research directions in this field.

Ferroptosis in hepatocellular carcinoma: Mechanisms and therapeutic implications

Ferroptosis is a novel form of oxidative cell death, in which highly expressed unsaturated fatty acids on the cell membrane are catalyzed by divalent iron or ester oxygenase to promote liposome peroxidation. This process reduces cellular antioxidant capacity, increases lipid reactive oxygen species, and leads to the accumulation of intracellular ferrous ions, which disrupts intracellular redox homeostasis and ultimately causes oxidative cell death. Studies have shown that ferroptosis induces an immune response that has a dual role in liver disease, ferroptosis also offers a promising strategy for precise cancer therapy. Ferroptosis regulators are beneficial in maintaining cellular homeostasis and tissue health, have shown efficacy in treating diseases of the hepatic system. However, the mechanisms of action and molecular regulatory pathways of ferroptosis in hepatocellular carcinoma (HCC) have not been fully elucidated. Therefore, deciphering the role of ferroptosis and its mechanisms in HCC progression is crucial for treating the disease. In this review, we introduce the morphological features and biochemical functions of ferroptosis, outline the molecular regulatory pathways of ferroptosis, and highlights the therapeutic potential of ferroptosis inhibitors and modulators to target it in HCC.

Concurrent Amplification of Ferroptosis and Immune System Activation Via Nanomedicine-Mediated Radiosensitization for Triple-Negative Breast Cancer Therapy

Radiation therapy (RT) is one of the core therapies for current cancer management. However, the emergence of radioresistance has become a major cause of radiotherapy failure and disease progression. Therefore, overcoming radioresistance to achieve highly effective treatment for refractory tumors is significant yet challenging. Here, pH-responsive DSPE-PEoz modified hollow Bi2Se3-RSL3/diABZi (DP-HBN/RA) nanomedicine is designed as a radiation sensitizer for efficient treatment of triple-negative breast cancer by simultaneously amplifying ferroptosis and immune system activation. DP-HBN/RA can efficiently concentrate X-ray radiation energy inside the tumor, thereby promoting precise ionizing radiation exposure in tumor cells to produce large amounts of reactive oxygen species (ROS), leading to lipid peroxidation-induced ferroptosis. Meanwhile, ferroptotic cell death is intensified through the inactivation of GPX4 by RSL3 released from DP-HBN/RA to acidic conditions in the tumor microenvironment. Additionally, DP-HBN/RA enhances RT efficacy to exacerbate unrepairable DNA damage and release DNA fragments that activate the cGAS-STING signal pathway, evoking a systematic immune response. Ingeniously, the released diABZi reinforces cGAS-STING activation to boost the immunology antitumor effect. This work links the induction of ferroptosis and the initiation of systematic immune response to achieve highly effective tumor suppression, which opens up new avenues for future treatments of refractory tumors.

Multi-species genome-wide CRISPR screens identify conserved suppressors of cold-induced cell death

Cells must adapt to environmental changes to maintain homeostasis. One of the most striking environmental adaptations is entry into hibernation during which core body temperature can decrease from 37°C to as low at 4°C. How mammalian cells, which evolved to optimally function within a narrow range of temperatures, adapt to this profound decrease in temperature remains poorly understood. In this study, we conducted the first genome-scale CRISPR-Cas9 screen in cells derived from Syrian hamster, a facultative hibernator, as well as human cells to investigate the genetic basis of cold tolerance in a hibernator and a non-hibernator in an unbiased manner. Both screens independently revealed glutathione peroxidase 4 (GPX4), a selenium-containing enzyme, and associated proteins as critical for cold tolerance. We utilized genetic and pharmacological approaches to demonstrate that GPX4 is active in the cold and its catalytic activity is required for cold tolerance. Furthermore, we show that the role of GPX4 as a suppressor of cold-induced cell death extends across hibernating species, including 13-lined ground squirrels and greater horseshoe bats, highlighting the evolutionary conservation of this mechanism of cold tolerance. This study identifies GPX4 as a central modulator of mammalian cold tolerance and advances our understanding of the evolved mechanisms by which cells mitigate cold-associated damage-one of the most common challenges faced by cells and organisms in nature.

Design, synthesis, and biological evaluation of RSL3-based GPX4 degraders with hydrophobic tags

Ferroptosis is a new type of programmed cell death characterized by iron-dependent lipid peroxidation, during which glutathione peroxidase 4 (GPX4) plays an essential role and is well-recognized as a promising therapeutic target for cancer treatment. Although some GPX4 degradation molecules have been developed to induce ferroptosis, the discovery of GPX4 degraders with hydrophobic tagging (HyT) as an innovative approach is more challenging. Herein, we designed and synthesized a series of HyT degraders by linking the GPX4 inhibitor RSL3 with a hydrophobic and bulky group of adamantane. Among them, compound R8 is a potent degrader (DC50, 24h = 0.019 μM) which can effectively degrade GPX4 in a dose- and time-dependent manner. Furthermore, compound R8 exhibited superior in vitro antitumor potency against HT1080 and MDA-MB-231 cell lines with IC50 values of 24 nM and 32 nM respectively, which are 4 times more potent than parental compound RSL3. Mechanistic investigation evidenced that R8 consumes GPX4 protein mainly through the ubiquitin proteasome (UPS) and enables to induce the accumulation of LPO, thereby triggering ferroptosis. Our work presented the novel GPX4 degrader of R8 by HyT strategy, and provided a promising pathway of degradation agents for the treatment of ferroptosis relevant diseases.

Mechanisms of ferroptosis and targeted therapeutic approaches in urological malignancies

The prevalence of urological malignancies remains a significant global health concern, particularly given the challenging prognosis for patients in advanced disease stages. Consequently, there is a pressing need to explore the molecular mechanisms that regulate the development of urological malignancies to discover novel breakthroughs in diagnosis and treatment. Ferroptosis, characterized by iron-ion-dependent lipid peroxidation, is a form of programmed cell death (PCD) distinct from apoptosis, autophagy, and necrosis. Notably, lipid, iron, and glutathione metabolism intricately regulate intracellular ferroptosis, playing essential roles in the progression of various neoplasms and drug resistance. In recent years, ferroptosis has been found to be closely related to urological malignancies. This paper provides an overview of the involvement of ferroptosis in the pathogenesis and progression of urological malignancies, elucidates the molecular mechanisms governing its regulation, and synthesizes recent breakthroughs in diagnosing and treating these malignancies. We aim to provide a new direction for the clinical treatment of urological malignancies.

Heat Shock Protein 90 Interactome-Mediated Proteolysis Targeting Chimera (HIM-PROTAC) Degrading Glutathione Peroxidase 4 to Trigger Ferroptosis

Targeted protein degradation (TPD) is an emerging therapeutic paradigm aimed at eliminating the disease-causing protein with aberrant expression. Herein, we report a new approach to inducing intracellular glutathione peroxidase 4 (GPX4) protein degradation to trigger ferroptosis by bridging the target protein to heat shock protein 90 (HSP90), termed HSP90 interactome-mediated proteolysis targeting chimera (HIM-PROTAC). Different series of HIM-PROTACs were synthesized and evaluated, and two of them, GDCNF-2/GDCNF-11 potently induced ferroptosis via HSP90-mediated ubiquitin-proteasomal degradation of GPX4 in HT-1080 cells with DC50 values of 0.18 and 0.08 μM, respectively. In particular, GDCNF-11 showed 15-fold more ferroptosis selectivity over GPX4 inhibitor ML162. Moreover, these two degraders effectively suppress tumor growth in the mice model with relatively low toxicity as compared to the combination therapy of GPX4 and HSP90 inhibitors. In general, this study demonstrated the feasibility of degrading GPX4 via HSP90 interactome, and thus provided a significant complement to existing TPD strategies.

Ferroptosis in Ischemic Stroke and Related Traditional Chinese Medicines

Stroke is a severe neurological disorder resulting from the rupture or blockage of blood vessels, leading to significant mortality and disability worldwide. Among the different types of stroke, ischemic stroke (IS) is the most prevalent, accounting for 70-80% of cases. Cell death following IS occurs through various mechanisms, including apoptosis, necrosis, and ferroptosis. Ferroptosis, a recently identified form of regulated cell death characterized by iron overload and lipid peroxidation, was first described by Dixon in 2012. Currently, the only approved pharmacological treatment for IS is recombinant tissue plasminogen activator (rt-PA), which is limited by a narrow therapeutic window and often results in suboptimal outcomes. Recent research has identified several traditional Chinese medicines (TCMs) that can inhibit ferroptosis, thereby mitigating the damage caused by IS. This review provides an overview of stroke, the role of ferroptosis in IS, and the potential of certain TCMs to inhibit ferroptosis and contribute to stroke treatment.

Exploiting ferroptosis vulnerabilities in cancer

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

Research progress on GPX4 targeted compounds

Blocking the System Xc-_ GSH_GPX4 pathway to induce ferroptosis in tumor cells is a novel strategy for cancer treatment. GPX4 serves as the core of the System Xc-/GSH/GPX4 pathway and is a predominant target for inducing ferroptosis in tumor cells. This article summarizes compounds identified in current research that directly target the GPX4 protein, including inhibitors, activators, small molecule degraders, chimeric degraders, and the application of combination therapies with other drugs, aiming to promote further research on the target and related diseases.

Targeting GPX4 in ferroptosis and cancer: chemical strategies and challenges

Selenoprotein glutathione peroxidase 4 (GPX4) serves as a crucial suppressor of oxidative stress-induced ferroptosis, making it an attractive target for disease therapy. Here, we discuss recent strategies and challenges associated with targeting GPX4 through covalent inhibitors, proteolysis targeting chimera (PROTAC) degraders, and cell-type-specific degraders in the context of cancer.

Modeling ferroptosis in human dopaminergic neurons: Pitfalls and opportunities for neurodegeneration research

The activation of ferroptosis is being pursued in cancer research as a strategy to target apoptosis-resistant cells. By contrast, in various diseases that affect the cardiovascular system, kidneys, liver, and central and peripheral nervous systems, attention is directed toward interventions that prevent ferroptotic cell death. Mechanistic insights into both research areas stem largely from studies using cellular in vitro models. However, intervention strategies that show promise in cellular test systems often fail in clinical trials, which raises concerns regarding the predictive validity of the utilized in vitro models. In this study, the human LUHMES cell line, which serves as a model for human dopaminergic neurons, was used to characterize factors influencing the activation of ferroptosis. Erastin and RSL-3 induced cell death that was distinct from apoptosis. Parameters such as the differentiation state of LUHMES cells, cell density, and the number and timing of medium changes were identified as determinants of sensitivity to ferroptosis activation. In differentiated LUHMES cells, interventions at mechanistically divergent sites (iron chelation, coenzyme Q10, peroxidase mimics, or inhibition of 12/15-lipoxygenase) provide almost complete protection from ferroptosis. LUHMES cells allowed the experimental modulation of intracellular iron concentrations and demonstrated a correlation between intracellular iron levels, the rate of lipid peroxidation, as well as the sensitivity of the cells to ferroptotic cell death. These findings underscore the importance of understanding the various factors that influence ferroptosis activation and highlight the need for well-characterized in vitro models to enhance the reliability and predictive value of observations in ferroptosis research, particularly when translating findings into in vivo contexts.

Ferroptosis in Cancer Therapy: Mechanisms, Small Molecule Inducers, and Novel Approaches

Ferroptosis, a unique form of programmed cell death, is initiated by an excess of iron accumulation and lipid peroxidation-induced damage. There is a growing body of evidence indicating that ferroptosis plays a critical role in the advancement of tumors. The increased metabolic activity and higher iron levels in tumor cells make them particularly vulnerable to ferroptosis. As a result, the targeted induction of ferroptosis is becoming an increasingly promising approach for cancer treatment. This review offers an overview of the regulatory mechanisms of ferroptosis, delves into the mechanism of action of traditional small molecule ferroptosis inducers and their effects on various tumors. In addition, the latest progress in inducing ferroptosis using new means such as proteolysis-targeting chimeras (PROTACs), photodynamic therapy (PDT), sonodynamic therapy (SDT) and nanomaterials is summarized. Finally, this review discusses the challenges and opportunities in the development of ferroptosis-inducing agents, focusing on discovering new targets, improving selectivity, and reducing toxic and side effects.

Ferroptosis as a promising targeted therapy for triple negative breast cancer

PURPOSE

Triple negative breast cancer (TNBC) is a challenging subtype characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Standard treatment options are limited, and approximately 45% of patients develop distant metastasis. Ferroptosis, a regulated form of cell death triggered by iron-dependent lipid peroxidation and oxidative stress, has emerged as a potential targeted therapy for TNBC.

METHODS

This study utilizes a multifaceted approach to investigate the induction of ferroptosis as a therapeutic strategy for TNBC. It explores metabolic alterations, redox imbalance, and oncogenic signaling pathways to understand their roles in inducing ferroptosis, characterized by lipid peroxidation, reactive oxygen species (ROS) generation, and altered cellular morphology. Critical pathways such as Xc-/GSH/GPX4, ACSL4/LPCAT3, and nuclear factor erythroid 2-related factor 2 (NRF2) are examined for their regulatory roles in ferroptosis and their potential dysregulation contributing to cancer cell survival and resistance.

RESULTS

Inducing ferroptosis has been shown to inhibit tumor growth, enhance the efficacy of conventional therapies, and overcome drug resistance in TNBC. Lipophilic antioxidants, GPX4 inhibitors, and inhibitors of the Xc- system have been demonstrated to be potential ferroptosis inducers. Additionally, targeting the NRF2 pathway and exploring other ferroptosis regulators, such as ferroptosis suppressor protein 1 (FSP1), and the PERK-eIF2α-ATF4-CHOP pathway, may offer novel therapeutic avenues.

CONCLUSION

Further research is needed to understand the mechanisms, optimize therapeutic strategies, and evaluate the safety and efficacy of ferroptosis-targeted therapies in TNBC treatment. Overall, targeting ferroptosis represents a promising approach to improving treatment outcomes and overcoming the challenges posed by TNBC.

Glycyrrhetinic Acid as a Hepatocyte Targeting Ligand-Functionalized Platinum(IV) Complexes for Hepatocellular Carcinoma Therapy and Overcoming Multidrug Resistance

Promising targeted therapy options to overcome drug resistance and side effects caused by platinum(II) drugs for treatment in hepatocellular carcinoma are urgently needed. Herein, six novel multifunctional platinum(IV) complexes through linking platinum(II) agents and glycyrrhetinic acid (GA) were designed and synthesized. Among them, complex 20 showed superior antitumor activity against tested cancer cells including cisplatin resistance cells than cisplatin and simultaneously displayed good liver-targeting ability. Moreover, complex 20 can significantly cause DNA damage and mitochondrial dysfunction, promote reactive oxygen species generation, activate endoplasmic reticulum stress, and eventually induce apoptosis. Additionally, complex 20 can effectively inhibit cell migration and invasion and trigger autophagy and ferroptosis in HepG-2 cells. More importantly, complex 20 demonstrated stronger tumor inhibition ability than cisplatin or the combo of cisplatin/GA with almost no systemic toxicity in HepG-2 or A549 xenograft models. Collectively, complex 20 could be developed as a potential anti-HCC agent for cancer treatment.

Cycloplatinated (II) Complex Based on Isoquinoline Alkaloid Elicits Ferritinophagy-Dependent Ferroptosis in Triple-Negative Breast Cancer Cells

The development and optimization of metal-based anticancer drugs with novel cytotoxic mechanisms have emerged as key strategies to overcome chemotherapeutic resistance and side effects. Agents that simultaneously induce ferroptosis and autophagic death have received extensive attention as potential modalities for cancer therapy. However, only a limited set of drugs or treatment modalities can synergistically induce ferroptosis and autophagic tumor cell death. In this work, we designed and synthesized four new cycloplatinated (II) complexes harboring an isoquinoline alkaloid C∧N ligand. On screening the in vitro activity of these agents, we found that Pt-3 exhibited greater selectivity of cytotoxicity, decreased resistance factors, and improved anticancer activity compared to cisplatin. Furthermore, Pt-3, which we demonstrate can initiate potent ferritinophagy-dependent ferroptosis, exhibits less toxic and better therapeutic activity than cisplatin in vivo. Our results identify Pt-3 as a promising candidate or paradigm for further drug development in cancer treatment.

ML162 derivatives incorporating a naphthoquinone unit as ferroptosis/apoptosis inducers: Design, synthesis, anti-cancer activity, and drug-resistance reversal evaluation

Activating apoptosis has long been viewed as an anti-cancer process, but recently increasing evidence has accumulated that induction of ferroptosis has emerged as a promising strategy for cancer therapeutics. Glutathione peroxidase 4 (GPX4) is one of the pivotal factors regulating ferroptosis that targeted inhibition or degradation of GPX4 could effectively trigger ferroptosis. In this study, a series of ML162-quinone conjugates were constructed by using pharmacophore hybridization and bioisosterism strategies, with the aim of obtaining more active anticancer agents via the ferroptosis and apoptosis dual cell death processes. Of these compounds, GIC-20 was identified as the most active one that exhibited promising anticancer activity both in vitro and in vivo via ferroptosis and apoptosis dual-targeting processes, without obvious toxicity compared with ML162. On one hand, GIC-20 could trigger ferroptosis in cells by inducing intracellular lipid peroxide and ROS accumulation, and destroying mitochondrial structure. In addition to GPX4 inhibition, GIC-20 can also trigger ferroptosis via proteasomal-mediated degradation of GPX4, suggesting GIC-20 may function as a molecule glue degrader. On the other hand, GIC-20 can also induce apoptosis via upregulating the level of apoptotic protein Bax and downregulating the level of anti-apoptotic protein Bcl-2 in HT1080 cells. Furthermore, GIC-20 also enhanced the sensitivity of resistant MIA-PaCa-2-AMG510R cells to AMG510, suggesting the great potential of GIC-20 in overcoming the acquired resistance of KRASG12C inhibitors. Overall, GIC-20 represents a novel dual ferroptosis/apoptosis inducer warranting further development for cancer therapeutics and overcoming drug resistance.

Peiminine triggers ferroptosis to inhibit breast cancer growth through triggering Nrf2 signaling

BACKGROUND

Peiminine (PMI) is an active alkaloid sourced from Fritillaria thunbergii, which has been shown to suppress the development of a variety of tumors. Whereas, the roles and precise mechanism of PMI in breast cancer (BC) development remain not been clarified.

METHODS

The cytotoxic effect of PMI on MCF-10A and BC cell lines (MCF-7 and BT-549) were assessed by MTT and LDH release assay. Cell proliferation was evaluated by EdU staining. Levels of Malondialdehyde (MDA), reactive oxygen species (ROS), glutathione (GSH) activity and iron assay were measured by Enzyme linked immunosorbent assay (ELISA) kits, respectively. Transmission Electron Microscope was performed to observe mitochondrial morphological structure. Immunofluorescence, immunohistochemistry, and western blot were conducted to examine protein levels, respectively. Xenograft model was used to confirm cellular findings.

RESULTS

PMI treatment reduced the viability and enhanced LDH level of MCF-7 and BT-549 cells in a time- and concentration-dependent manner, and further suppressed cell proliferation in vitro and tumor growth in vivo. Subsequently, PMI administration resulted in significant increases of ROS, MDA and iron levels, reduction of GSH activity as well as mitochondrial shrinkage and GPX4 reduction, while all these phenomena could be rescued by ferrostatin-1. Mechanistically, PMI treatment led to promoted Nrf2 expression and its nuclear translocation, as well as it's downstream protein HO-1 and NQO1 expressions. Notably, ML-385, a Nrf2 specific inhibitor, greatly reversed the anti-tumor effects and pro-ferroptosis role of PMI in BC cells.

CONCLUSION

Taking these finding together, PMI could stimulate ferroptosis to inhibit BC tumor growth by activating Nrf2-HO-1 signaling pathway.

Glutathione depletion and dihydroorotate dehydrogenase inhibition actuated ferroptosis-augment to surmount triple-negative breast cancer

Ferroptosis is a promising therapeutic approach for combating malignant cancers, but its effectiveness is limited in clinical due to the adaptability and self-repair abilities of cancer cells. Mitochondria, as the pivotal player in ferroptosis, exhibit tremendous therapeutic potential by targeting the intramitochondrial anti-ferroptotic pathway mediated by dihydroorotate dehydrogenase (DHODH). In this study, an albumin-based nanomedicine was developed to induce augmented ferroptosis in triple-negative breast cancer (TNBC) by depleting glutathione (GSH) and inhibiting DHODH activity. The nanomedicine (ATO/SRF@BSA) was developed by loading sorafenib (SRF) and atovaquone (ATO) into bovine serum albumin (BSA). SRF is an FDA-approved ferroptosis inducer and ATO is the only drug used in clinical that targets mitochondria. By combining the effects of SRF and ATO, ATO/SRF@BSA promoted the accumulation of lipid peroxides within mitochondria by inhibiting the glutathione peroxidase 4 (GPX4)-GSH pathway and downregulating the DHODH-coenzyme Q (CoQH2) defense mechanism, triggers a burst of lipid peroxides. Simultaneously, ATO/SRF@BSA suppressed cancer cell self-repair and enhanced cell death by inhibiting the synthesis of adenosine triphosphate (ATP) and pyrimidine nucleotides. Furthermore, the anti-cancer results showed that ATO/SRF@BSA exhibited tumor-specific killing efficacy, significantly improved the tumor hypoxic microenvironment, and lessened the toxic side effects of SRF. This work presents an efficient and easily achievable strategy for TNBC treatment, which may hold promise for clinical applications.

Butylated Hydroxytoluene (BHT) Protects SH-SY5Y Neuroblastoma Cells from Ferroptotic Cell Death: Insights from In Vitro and In Vivo Studies

Ferroptosis is a special kind of programmed cell death that has been implicated in the pathogenesis of a large number of human diseases. It involves dysregulated intracellular iron metabolism and uncontrolled lipid peroxidation, which together initiate intracellular ferroptotic signalling pathways leading to cellular suicide. Pharmacological interference with ferroptotic signal transduction may prevent cell death, and thus patients suffering from ferroptosis-related diseases may benefit from such treatment. Butylated hydroxytoluene (BHT) is an effective anti-oxidant that is frequently used in oil chemistry and in cosmetics to prevent free-radical-mediated lipid peroxidation. Since it functions as a radical scavenger, it has previously been reported to interfere with ferroptotic signalling. Here, we show that BHT prevents RSL3- and ML162-induced ferroptotic cell death in cultured human neuroblastoma cells (SH-SY5Y) in a dose-dependent manner. It prevents the RSL3-induced oxidation of membrane lipids and normalises the RSL3-induced inhibition of the intracellular catalytic activity of glutathione peroxidase 4. The systemic application of BHT in a rat Alzheimer's disease model prevented the upregulation of the expression of ferroptosis-related genes. Taken together, these data indicate that BHT interferes with ferroptotic signalling in cultured neuroblastoma cells and may prevent ferroptotic cell death in an animal Alzheimer's disease model.

Diazepam-based covalent modifiers of GPX4 induce ferroptosis in liver cancer cells

Developing new chemotherapeutics that are structurally and mechanistically unique is needed due to the rapid rise of the cancer incidence across the globe. Here, we report the identification of irreversible, thiol-reactive diazepam derivatives as GPX4 modifiers and nanomolar inducers of ferroptosis in liver cancer cells.

Novel Covalent Probe Selectively Targeting Glutathione Peroxidase 4 In Vivo: Potential Applications in Pancreatic Cancer Therapy

Glutathione peroxidase 4 (GPX4) emerges as a promising target for the treatment of therapy-resistant cancer through ferroptosis. Thus, there is a broad interest in the development of GPX4 inhibitors. However, a majority of reported GPX4 inhibitors utilize chloroacetamide as a reactive electrophilic warhead, and the selectivity and pharmacokinetic properties still need to be improved. Herein, we developed a compound library based on a novel electrophilic warhead, the sulfonyl ynamide, and executed phenotypic screening against pancreatic cancer cell lines. Notably, one compound A16 exhibiting potent cell toxicity was identified. Further chemical proteomics investigations have demonstrated that A16 specifically targets GPX4 under both in situ and in vivo conditions, inducing ferroptosis. Importantly, A16 exhibited superior selectivity and potency compared to reported GPX4 inhibitors, ML210 and ML162. This provides the structural diversity of tool probes for unraveling the fundamental biology of GPX4 and exploring the therapeutic potential of pancreatic cancer via ferroptosis induction.

A potent GPX4 degrader to induce ferroptosis in HT1080 cells

Glutathione peroxidase 4 (GPX4) is the most promising target for inducing ferroptosis. GPX4-targeting strategies primarily focus on inhibiting its activity or adjusting its cellular level. However, small inhibitors have limitations due to the covalent reactive alkyl chloride moiety, which could lead to poor selectivity and suboptimal pharmacokinetic properties. Herein, we designed and synthesized a series of proteolysis targeting chimeras (PROTACs) by connecting RSL3, a small molecule inhibitor of GPX4, with six different ubiquitin ligase ligands. As a highly effective degrader, compound 18a is a potent degrader (DC50, 48h = 1.68 μM, Dmax, 48h = 85 %). It also showed an obvious anti-proliferative effect with the IC50 value of 2.37 ± 0.17 μM in HT1080. Mechanism research showed that compound 18a formed a ternary complex with GPX4 and cIAP and induced the degradation of GPX4 through the ubiquitin-proteasome system pathway. Furthermore, compound 18a also induced the accumulation of lipid peroxides and mitochondrial depolarization, subsequently triggering ferroptosis. Our work demonstrated the practicality and efficiency of the PROTAC strategy and offered a promising avenue for designing degraders to induce ferroptosis in cancer cells.

Yi-qi-hua-yu-jie-du decoction induces ferroptosis in cisplatin-resistant gastric cancer via the AKT/GSK3β/NRF2/GPX4 axis

BACKGROUND

Resistance to chemotherapy in gastric cancer (GC) is a ubiquitous challenge for its treatment. Yi-qi-hua-yu-jie-du decoction (YJD), an empirical formula in Traditional Chinese Medicine (TCM), demonstrated survival-prolonging functions in patients with GC. Previous research has shown that YJD could also inhibit drug resistance in GC. However, the precise mechanisms for how YJD accomplishes this remain incompletely explained.

PURPOSE

The research aimed to identify differential metabolic characteristics in cisplatin-resistant GC and investigate whether YJD can target these differences to suppress GC drug resistance.

METHODS

Metabolomic analysis was conducted to identify metabolic disparities between cisplatin-resistant and parental GC cells, as well as metabolic modifications resulting from YJD intervention in cisplatin-resistant GC cells. The effect of YJD on ferroptosis stimulation was assessed by measuring the levels of reactive oxygen species (ROS), malondialdehyde (MDA), iron ions, the reduced glutathione (GSH) to oxidised glutathione (GSSG) ratio, and alterations in mitochondrial morphology. Western blotting and quantitative real-time polymerase chain reaction (Q-PCR) were employed to verity the mechanisms of YJD-triggered ferroptosis through GPX4 and NRF2 overexpression models, alongside the AKT activator SC79. In vivo validation was conducted using nude mouse xenograft models.

RESULTS

Cisplatin-resistant GC exhibited altered GSH/GPX4 metabolism, and ferroptosis was a significantly enriched cell death pattern with YJD treatment in cisplatin-resistant GC cells. Ferroptosis biomarkers, including ROS, MDA, iron ions, the GSH/GSSG ratio, and mitochondrial morphology, were remarkably changed with the YJD intervention. Mechanistic experiments demonstrated that YJD inhibited the phosphorylation cascade activity of the AKT/GSK3β pathway, thereby reducing NRF2 expression. The level of GPX4, a crucial enzyme involved in glutathione metabolism, was attenuated, facilitating ferroptosis induction in cisplatin-resistant GC.

CONCLUSION

The research reveals, for the first time, changes in GSH/GPX4 metabolism in cisplatin-resistant GC cells based on metabolomic analysis. YJD induced ferroptosis in cisplatin-resistant GC by inhibiting GPX4 through the AKT/GSK3β/NRF2 pathway, thus attenuating the cisplatin drug resistance in GC. Our findings identify metabolic changes in cisplatin-resistant GC and establish a theoretical framework for YJD on tackling drug resistance in GC through ferroptosis.

Ferroptosis induction via targeting metabolic alterations in triple-negative breast cancer

Triple-negative breast cancer (TNBC), the most aggressive form of breast cancer, presents severe threats to women's health. Therefore, it is critical to find novel treatment approaches. Ferroptosis, a newly identified form of programmed cell death, is marked by the buildup of lipid reactive oxygen species (ROS) and high iron concentrations. According to previous studies, ferroptosis sensitivity can be controlled by a number of metabolic events in cells, such as amino acid metabolism, iron metabolism, and lipid metabolism. Given that TNBC tumors are rich in iron and lipids, inducing ferroptosis in these tumors is a potential approach for TNBC treatment. Notably, the metabolic adaptability of cancer cells allows them to coordinate an attack on one or more metabolic pathways to initiate ferroptosis, offering a novel perspective to improve the high drug resistance and clinical therapy of TNBC. However, a clear picture of ferroptosis in TNBC still needs to be completely revealed. In this review, we provide an overview of recent advancements regarding the connection between ferroptosis and amino acid, iron, and lipid metabolism in TNBC. We also discuss the probable significance of ferroptosis as an innovative target for chemotherapy, radiotherapy, immunotherapy, nanotherapy and natural product therapy in TNBC, highlighting its therapeutic potential and application prospects.