Modulatory profiling identifies mechanisms of small molecule-induced cell death

Thirty years of NRF2: advances and therapeutic challenges

Over the last 30 years, NRF2 has evolved from being recognized as a transcription factor primarily involved in redox balance and detoxification to a well-appreciated master regulator of cellular proteostasis, metabolism and iron homeostasis. NRF2 plays a pivotal role in diverse pathologies, including cancer, and metabolic, inflammatory and neurodegenerative disorders. It exhibits a Janus-faced duality, safeguarding cellular integrity in normal cells against environmental insults to prevent disease onset, whereas in certain cancers, constitutively elevated NRF2 levels provide a tumour survival advantage, promoting progression, therapy resistance and metastasis. Advances in understanding the mechanistic regulation of NRF2 and its roles in human pathology have propelled the investigation of NRF2-targeted therapeutic strategies. This Review dissects the mechanistic intricacies of NRF2 signalling, its cross-talk with biological processes and its far-reaching implications for health and disease, highlighting key discoveries that have shaped innovative therapeutic approaches targeting NRF2.

Iron and ferroptosis in kidney disease: molecular and metabolic mechanisms

Maintaining iron homeostasis is necessary for kidney functioning. There is more and more research indicating that kidney disease is often caused by iron imbalance. Over the past decade, ferroptosis' role in mediating the development and progression of renal disorders, such as acute kidney injury (renal ischemia-reperfusion injury, drug-induced acute kidney injury, severe acute pancreatitis induced acute kidney injury and sepsis-associated acute kidney injury), chronic kidney disease (diabetic nephropathy, renal fibrosis, autosomal dominant polycystic kidney disease) and renal cell carcinoma, has come into focus. Thus, knowing kidney iron metabolism and ferroptosis regulation may enhance disease therapy. In this review, we discuss the metabolic and molecular mechanisms of iron signaling and ferroptosis in kidney disease. We also explore the possible targets of ferroptosis in the therapy of renal illness, as well as their existing limitations and future strategies.

Improving understanding of ferroptosis: Molecular mechanisms, connection with cellular senescence and implications for aging

In the face of cell damage, cells can initiate a response ranging from survival to death, the balance being crucial for tissue homeostasis and overall health. Cell death, in both accidental and regulated forms, plays a fundamental role in maintaining tissue homeostasis. Among the regulated mechanisms of cell death, ferroptosis has garnered attention for its iron-dependent phospholipid (PL) peroxidation and its implications in aging and age-related disorders, as well as for its therapeutic relevance. In this review, we provide an overview of the mechanisms, regulation, and physiological and pathological roles of ferroptosis. We present new insights into the relationship between ferroptosis, cellular senescence and aging, emphasizing how alterations in ferroptosis pathways contribute to aging-related tissue dysfunction. In addition, we examine the therapeutic potential of ferroptosis in aging-related diseases, offering innovative insights into future interventions aimed at mitigating the effects of aging and promoting longevity.

Dietary pro-oxidant therapy by a vitamin K precursor targets PI 3-kinase VPS34 function

Men taking antioxidant vitamin E supplements have increased prostate cancer (PC) risk. However, whether pro-oxidants protect from PC remained unclear. In this work, we show that a pro-oxidant vitamin K precursor [menadione sodium bisulfite (MSB)] suppresses PC progression in mice, killing cells through an oxidative cell death: MSB antagonizes the essential class III phosphatidylinositol (PI) 3-kinase VPS34-the regulator of endosome identity and sorting-through oxidation of key cysteines, pointing to a redox checkpoint in sorting. Testing MSB in a myotubular myopathy model that is driven by loss of MTM1-the phosphatase antagonist of VPS34-we show that dietary MSB improved muscle histology and function and extended life span. These findings enhance our understanding of pro-oxidant selectivity and show how definition of the pathways they impinge on can give rise to unexpected therapeutic opportunities.

Chemical screens for particle-induced macrophage death identifies kinase inhibitors of phagocytosis as targets for toxicity

BACKGROUND

Nanoparticles are increasingly being used in medicine, cosmetics, food, and manufacturing. However, potential toxicity may limit the use of newly engineered nanoparticles. Prior studies have identified particle characteristics that are predictive of toxicity, although the mechanisms responsible for toxicity remain largely unknown. Nanoparticle treatment in cell culture, combined with high-throughput chemical screen allows for systematic perturbations of thousands of molecular targets against potential pathways of toxicity. The resulting data matrix, called chemical compendium, can provide insights into the mechanism of toxicity as well as help classify nanoparticles based on toxicity pathway.

RESULTS

We performed unbiased screens of 1280 bioactive chemicals against a panel of four particles, searching for inhibitors of macrophage toxicity. Our hit compounds clustered upon inhibitors of kinases involved in phagocytosis, including focal adhesion kinase (FAK), with varying specificity depending on particles. Interestingly, known inhibitors of cell death including NLRP3 inflammasome inhibitor were unable to suppress particle-induced macrophage death for many of the particles. By searching for upstream receptors of kinases, we identified Cd11b as one of the receptors involved in recognizing a subset of particles. We subsequently used these hit compounds and antibodies to further characterize a larger panel of particles and identified hydrodynamic size as an important particle characteristic in Cd11b-mediated particle uptake and toxicity.

CONCLUSIONS

Our chemical compendium and workflow can be expanded across cell types and assays to characterize the toxicity mechanism of newly engineered nanoparticles. The data in their current form can also be analyzed to help design future high-throughput screening for nanoparticle toxicity.

Recent advancements in nanomaterial-mediated ferroptosis-induced cancer therapy: Importance of molecular dynamics and novel strategies

Ferroptosis is a novel type of controlled cell death resulting from an imbalance between oxidative harm and protective mechanisms, demonstrating significant potential in combating cancer. It differs from other forms of cell death, such as apoptosis and necrosis. Molecular therapeutics have hard time playing the long-acting role of ferroptosis induction due to their limited water solubility, low cell targeting capacity, and quick metabolism in vivo. To this end, small molecule inducers based on biological factors have long been used as strategy to induce cell death. Research into ferroptosis and advancements in nanotechnology have led to the discovery that nanomaterials are superior to biological medications in triggering ferroptosis. Nanomaterials derived from iron can enhance ferroptosis induction by directly releasing large quantities of iron and increasing cell ROS levels. Moreover, utilizing nanomaterials to promote programmed cell death minimizes the probability of unfavorable effects induced by mutations in cancer-associated genes such as RAS and TP53. Taken together, this review summarizes the molecular mechanisms involved in ferroptosis along with the classification of ferroptosis induction. It also emphasized the importance of cell organelles in the control of ferroptosis in cancer therapy. The nanomaterials that trigger ferroptosis are categorized and explained. Iron-based and noniron-based nanomaterials with their characterization at the molecular and cellular levels have been explored, which will be useful for inducing ferroptosis that leads to reduced tumor growth. Within this framework, we offer a synopsis, which traverses the well-established mechanism of ferroptosis and offers practical suggestions for the design and therapeutic use of nanomaterials.

Mitochondria-mediated Ferroptosis in Diseases Therapy: From Molecular Mechanisms to Implications

Ferroptosis, a type of cell death involving iron and lipid peroxidation, has been found to be closely associated with the development of many diseases. Mitochondria are vital components of eukaryotic cells, serving important functions in energy production, cellular metabolism, and apoptosis regulation. Presently, the precise relationship between mitochondria and ferroptosis remains unclear. In this study, we aim to systematically elucidate the mechanisms via which mitochondria regulate ferroptosis from multiple perspectives to provide novel insights into mitochondrial functions in ferroptosis. Additionally, we present a comprehensive overview of how mitochondria contribute to ferroptosis in different conditions, including cancer, cardiovascular disease, inflammatory disease, mitochondrial DNA depletion syndrome, and novel coronavirus pneumonia. Gaining a comprehensive understanding of the involvement of mitochondria in ferroptosis could lead to more effective approaches for both basic cell biology studies and medical treatments.

Ferroptosis and cuproptposis in kidney Diseases: dysfunction of cell metabolism

Metal ions play an important role in living organisms and are involved in essential physiological activities. However, the overload state of ions can cause excess free radicals, cell damage, and even cell death. Ferroptosis and cuproptosis are specific forms of cell death that are distinct from apoptosis, necroptosis, and other regulated cell death. These unique modalities of cell death, dependent on iron and copper, are regulated by multiple cellular metabolic pathways, including steady-state metal redox treatment mitochondrial activity of lipid, amino acid and glucose metabolism, and various signaling pathways associated with disease. Although the mechanisms of ferroptosis and cuproptosis are not yet fully understood, there is no doubt that ion overload plays a crucial act in these metal-dependent cell deaths. In this review, we discussed the core roles of ion overload in ferroptosis and cuproptosis, the association between metabolism imbalance and ferroptosis and cuproptosis, the extract the diseases caused by ion overload and current treatment modalities.

Discovery of GPX4 inhibitors through FP-based high-throughput screening

Ferroptosis is a form of non-apoptotic cell death, regulated by phospholipid hydroperoxide glutathione peroxidase 4 (GPX4), a selenoprotein with a selenocysteine residue (sec) in the active site. GPX4 is a promising target for cancer cells in therapy-resistant conditions via ferroptosis, which can reduce the level of lipid reactive oxygen species (ROS). So far, all existing GPX4 inhibitors covalently bind to GPX4 via a reactive alkyl chloride moiety or masked nitrile-oxide electrophiles with poor selectivity and pharmacokinetic properties and most were obtained by cell phenotype-based screening. Lacking of effective high-throughput screening methods for GPX4 protein limits the discovery of GPX4 inhibitors. Here, we report a fluorescence polarization (FP)-based high throughput screening (HTS) assay for GPX4-U46C-C10A-C66A in vitro, and found Metamizole sodium from our in-house compound library inhibits GPX4-U46C-C10A-C66A enzyme activity. Structure-activity relationships (SAR) demonstrated the importance of sulfonyl group on interaction between Metamizole sodium and GPX4-U46C-C10A-C66A. Our FP assay could be an effective tool for discovery of GPX4 inhibitors and Metamizole sodium was a potential inhibitor for GPX4 in vitro.

IP3R-Mediated Calcium Release Promotes Ferroptotic Death in SH-SY5Y Neuroblastoma Cells

Ferroptosis is an iron-dependent cell death pathway that involves the depletion of intracellular glutathione (GSH) levels and iron-mediated lipid peroxidation. Ferroptosis is experimentally caused by the inhibition of the cystine/glutamate antiporter xCT, which depletes cells of GSH, or by inhibition of glutathione peroxidase 4 (GPx4), a key regulator of lipid peroxidation. The events that occur between GPx4 inhibition and the execution of ferroptotic cell death are currently a matter of active research. Previous work has shown that calcium release from the endoplasmic reticulum (ER) mediated by ryanodine receptor (RyR) channels contributes to ferroptosis-induced cell death in primary hippocampal neurons. Here, we used SH-SY5Y neuroblastoma cells, which do not express RyR channels, to test if calcium release mediated by the inositol 1,4,5-trisphosphate receptor (IP3R) channel plays a role in this process. We show that treatment with RAS Selective Lethal Compound 3 (RSL3), a GPx4 inhibitor, enhanced reactive oxygen species (ROS) generation, increased cytoplasmic and mitochondrial calcium levels, increased lipid peroxidation, and caused cell death. The RSL3-induced calcium signals were inhibited by Xestospongin B, a specific inhibitor of the ER-resident IP3R calcium channel, by decreasing IP3R levels with carbachol and by IP3R1 knockdown, which also prevented the changes in cell morphology toward roundness induced by RSL3. Intracellular calcium chelation by incubation with BAPTA-AM inhibited RSL3-induced calcium signals, which were not affected by extracellular calcium depletion. We propose that GPx4 inhibition activates IP3R-mediated calcium release in SH-SY5Y cells, leading to increased cytoplasmic and mitochondrial calcium levels, which, in turn, stimulate ROS production and induce lipid peroxidation and cell death in a noxious positive feedback cycle.

A ferroptosis-related ceRNA network for investigating the molecular mechanisms and the treatment of neonatal hypoxic-ischemic encephalopathy

Background

Neonatal hypoxic-ischemic brain damage (HIBD) is a clinical syndrome causing brain injury in newborns with obscure etiology. Increasing evidence suggests that ferroptosis plays a role in HIBD. This study aimed to clarify the key ferroptosis-related genes (FRGs) of HIBD, construct a long non-coding RNA-microRNA-messenger RNA (lncRNA-miRNA-mRNA) network, and further investigate the pathogenesis of HIBD.

Methods

Gene expression data were downloaded from the Gene Expression Omnibus and FerrDb databases. The differentially expressed lncRNAs and FRGs were screened, and the related miRNAs and mRNAs were predicted. The obtained mRNA was intersected with the differentially expressed FRGs (DE-FRGs) to identify the key DE-FRGs. Cell-type Identification by Estimating Relative Subsets of RNA Transcripts method was applied to analyze the immune cell infiltration level and the relationship between key genes and immune cells.

Results

Gene differential expression analysis revealed that 1,178 lncRNAs, 207 miRNAs, and 647 mRNAs were differentially expressed in the blood of HIBD patients in comparison to healthy controls. The correlations of the lncRNAs, miRNAs, and mRNAs lead to the establishment of a competing endogenous RNA (ceRNA) network associated with ferroptosis in HIBD. Further validation using an external dataset and quantitative real-time polymerase chain reaction (PCR) analysis of brain tissues from hypoxic-ischemic encephalopathy rats confirmed the expression patterns of three key genes, including HMOX1, MYCN, and QSOX1. Meanwhile, the three key genes were closely correlated with the infiltration of multiple immune cells and might affect the function of HIBD regulatory genes such as CPT2 and GCK. In addition, drug prediction suggested that four drugs, including cephaeline, emetine, mestranol, and sulmazole, might alleviate HIBD.

Conclusions

Our study established a ceRNA network, identified three key genes, and predicted four drugs that are associated with ferroptosis in HIBD, which provides new ideas for the investigation of the disease mechanisms and might facilitate the diagnosis and treatment of the disease.

Hydrogen sulfide ameliorates endothelial dysfunction in aging arteries by regulating ferroptosis

Aging causes vascular endothelial dysfunction. We aimed to investigate the causes of vascular endothelial dysfunction during aging using plasma and renal arteries from patients who underwent nephrectomy and animal models. The results showed that the endogenous H2S-producing enzyme cystathione-γ-lyase (CSE) protein expression was downregulated in renal artery tissue, plasma H2S levels were reduced. Moreover, elevated lipid peroxidation and iron accumulation levels led to ferroptosis and endothelial diastolic function in the renal arteries was impaired in the elderly group. H2S enhanced the endogenous CSE expression in the elderly group, promoted endogenous H2S production, decreased lipid peroxide expression, and inhibited ferroptosis, which in turn improved vascular endothelial function in the elderly group. In animal models, we also observed the same results. In addition, we applied NaHS, Ferrostatin-1 (ferroptosis inhibitor) and erastin (ferroptosis inducer) to incubate renal arteries of SD rats. The results showed that NaHS enhanced ferroptosis related proteins expression, inhibited ferroptosis and improved vascular endothelial function. We demonstrated that endothelial dysfunction associated with aging is closely related to reduced endogenous H2S levels and ferroptosis in vascular endothelial cells. Notably, H2S reduced lipid peroxidation levels in vascular endothelial cells, inhibited ferroptosis in vascular endothelial cells, and improved endothelial dysfunction.

A novel approach for predicting upstream regulators (PURE) that affect gene expression

External factors such as exposure to a chemical, drug, or toxicant (CDT), or conversely, the lack of certain chemicals can cause many diseases. The ability to identify such causal CDTs based on changes in the gene expression profile is extremely important in many studies. Furthermore, the ability to correctly infer CDTs that can revert the gene expression changes induced by a given disease phenotype is a crucial step in drug repurposing. We present an approach for Predicting Upstream REgulators (PURE) designed to tackle this challenge. PURE can correctly infer a CDT from the measured expression changes in a given phenotype, as well as correctly identify drugs that could revert disease-induced gene expression changes. We compared the proposed approach with four classical approaches as well as with the causal analysis used in Ingenuity Pathway Analysis (IPA) on 16 data sets (1 rat, 5 mouse, and 10 human data sets), involving 8 chemicals or drugs. We assessed the results based on the ability to correctly identify the CDT as indicated by its rank. We also considered the number of false positives, i.e. CDTs other than the correct CDT that were reported to be significant by each method. The proposed approach performed best in 11 out of the 16 experiments, reporting the correct CDT at the very top 7 times. IPA was the second best, reporting the correct CDT at the top 5 times, but was unable to identify the correct CDT at all in 5 out of the 16 experiments. The validation results showed that our approach, PURE, outperformed some of the most popular methods in the field. PURE could effectively infer the true CDTs responsible for the observed gene expression changes and could also be useful in drug repurposing applications.

Tenuifolin in the prevention of Alzheimer's disease-like phenotypes: Investigation of the mechanisms from the perspectives of calpain system, ferroptosis, and apoptosis

Polygala tenuifolia was documented to calm the mind and promote wisdom. However, its underlying mechanisms are still unclear. This study aimed to investigate the mechanisms underlying the effects of tenuifolin (Ten) on Alzheimer's disease (AD)-like phenotypes. We first applied bioinformatics methods to screen the mechanisms of P. tenuifolia in the treatment of AD. Thereafter, the d-galactose combined with Aβ1-42 (GCA) was applied to model AD-like behaviors and investigate the action mechanisms of Ten, one active component of P. tenuifolia. The data showed that P. tenuifolia actioned through multi-targets and multi-pathways, including regulation of synaptic plasticity, apoptosis, and calcium signaling, and so forth. Furthermore, in vitro experiments demonstrated that Ten prevented intracellular calcium overload, abnormal calpain system, and down-regulation of BDNF/TrkB signaling induced by GCA. Moreover, Ten suppressed oxidative stress and ferroptosis in HT-22 cells induced by GCA. Calpeptin and ferroptosis inhibitor prevented the decrease of cell viability induced by GCA. Interestingly, calpeptin did not interrupt GCA-induced ferroptosis in HT-22 cells but blocked the apoptosis. Animal experiments further demonstrated that Ten prevented GCA-induced memory impairment in mice and increased synaptic protein expression while reducing m-calpain expression. Ten prevents AD-like phenotypes through multiple signaling by inhibiting oxidative stress and ferroptosis, maintaining the stability of calpain system, and suppressing neuronal apoptosis.

Revisiting the intersection of microglial activation and neuroinflammation in Alzheimer's disease from the perspective of ferroptosis

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by chronic neuroinflammation with amyloid beta-protein deposition and hyperphosphorylated tau protein. The typical clinical manifestation of AD is progressive memory impairment, and AD is considered a multifactorial disease with various etiologies (genetic factors, aging, lifestyle, etc.) and complicated pathophysiological processes. Previous research identified that neuroinflammation and typical microglial activation are significant mechanisms underlying AD, resulting in dysfunction of the nervous system and progression of the disease. Ferroptosis is a novel modality involved in this process. As an iron-dependent form of cell death, ferroptosis, characterized by iron accumulation, lipid peroxidation, and irreversible plasma membrane disruption, promotes AD by accelerating neuronal dysfunction and abnormal microglial activation. In this case, disturbances in brain iron homeostasis and neuronal ferroptosis aggravate neuroinflammation and lead to the abnormal activation of microglia. Abnormally activated microglia release various pro-inflammatory factors that aggravate the dysregulation of iron homeostasis and neuroinflammation, forming a vicious cycle. In this review, we first introduce ferroptosis, microglia, AD, and their relationship. Second, we discuss the nonnegligible role of ferroptosis in the abnormal microglial activation involved in the chronic neuroinflammation of AD to provide new ideas for the identification of potential therapeutic targets for AD.

Anti-Ferroptotic Effects of Nrf2: Beyond the Antioxidant Response

The transcription factor Nrf2 was originally identified as a master regulator of redox homeostasis, as it governs the expression of a battery of genes involved in mitigating oxidative and electrophilic stress. However, the central role of Nrf2 in dictating multiple facets of the cellular stress response has defined the Nrf2 pathway as a general mediator of cell survival. Recent studies have indicated that Nrf2 regulates the expression of genes controlling ferroptosis, an ironand lipid peroxidation-dependent form of cell death. While Nrf2 was initially thought to have anti-ferroptotic function primarily through regulation of the antioxidant response, accumulating evidence has indicated that Nrf2 also exerts anti-ferroptotic effects via regulation of key aspects of iron and lipid metabolism. In this review, we will explore the emerging role of Nrf2 in mediating iron homeostasis and lipid peroxidation, where several Nrf2 target genes have been identified that encode critical proteins involved in these pathways. A better understanding of the mechanistic relationship between Nrf2 and ferroptosis, including how genetic and/or pharmacological manipulation of Nrf2 affect the ferroptotic response, should facilitate the development of new therapies that can be used to treat ferroptosis-associated diseases.

Reference compounds for characterizing cellular injury in high-content cellular morphology assays

Robust, generalizable approaches to identify compounds efficiently with undesirable mechanisms of action in complex cellular assays remain elusive. Such a process would be useful for hit triage during high-throughput screening and, ultimately, predictive toxicology during drug development. Here we generate cell painting and cellular health profiles for 218 prototypical cytotoxic and nuisance compounds in U-2 OS cells in a concentration-response format. A diversity of compounds that cause cellular damage produces bioactive cell painting morphologies, including cytoskeletal poisons, genotoxins, nonspecific electrophiles, and redox-active compounds. Further, we show that lower quality lysine acetyltransferase inhibitors and nonspecific electrophiles can be distinguished from more selective counterparts. We propose that the purposeful inclusion of cytotoxic and nuisance reference compounds such as those profiled in this resource will help with assay optimization and compound prioritization in complex cellular assays like cell painting.

Ferroptosis, pyroptosis and necroptosis in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is an acute and uncontrolled pulmonary inflammation caused by various insults. Cell death is a critical mechanism in the pathogenesis of ARDS. Ferroptosis, a novel form of cell death defined as iron-mediated lipid peroxidation, has been shown to play a role in the pathogenesis of ARDS. Additionally, pyroptosis and necroptosis are also involved in the pathophysiological process of ARDS. The crosstalk among ferroptosis, pyroptosis, and necroptosis is getting increasing attention. Therefore, this review will mainly summarize the molecular mechanisms and central pathophysiological role of ferroptosis in ARDS. We will also discuss our understanding of pyroptosis and necroptosis as they pertain to the pathogenesis of ARDS. Furthermore, we also describe the pathological processes that engage crosstalk among ferroptosis, pyroptosis, and necroptosis. We consider that individual pathways of ferroptosis, pyroptosis, and necroptosis are highly interconnected and can compensate for one another to promote cell death.

Surveying the landscape of emerging and understudied cell death mechanisms

Cell death can be a highly regulated process. A large and growing number of mammalian cell death mechanisms have been described over the past few decades. Major pathways with established roles in normal or disease biology include apoptosis, necroptosis, pyroptosis and ferroptosis. However, additional non-apoptotic cell death mechanisms with unique morphological, genetic, and biochemical features have also been described. These mechanisms may play highly specialized physiological roles or only become activated in response to specific lethal stimuli or conditions. Understanding the nature of these emerging and understudied mechanisms may provide new insight into cell death biology and suggest new treatments for diseases such as cancer and neurodegeneration.

NRF2 controls iron homeostasis and ferroptosis through HERC2 and VAMP8

Enhancing the intracellular labile iron pool (LIP) represents a powerful, yet untapped strategy for driving ferroptotic death of cancer cells. Here, we show that NRF2 maintains iron homeostasis by controlling HERC2 (E3 ubiquitin ligase for NCOA4 and FBXL5) and VAMP8 (mediates autophagosome-lysosome fusion). NFE2L2/NRF2 knockout cells have low HERC2 expression, leading to a simultaneous increase in ferritin and NCOA4 and recruitment of apoferritin into the autophagosome. NFE2L2/NRF2 knockout cells also have low VAMP8 expression, which leads to ferritinophagy blockage. Therefore, deletion of NFE2L2/NRF2 results in apoferritin accumulation in the autophagosome, an elevated LIP, and enhanced sensitivity to ferroptosis. Concordantly, NRF2 levels correlate with HERC2 and VAMP8 in human ovarian cancer tissues, as well as ferroptosis resistance in a panel of ovarian cancer cell lines. Last, the feasibility of inhibiting NRF2 to increase the LIP and kill cancer cells via ferroptosis was demonstrated in preclinical models, signifying the impact of NRF2 inhibition in cancer treatment.

Ferroptosis: mechanisms and advances in ocular diseases

As an essential trace element in the body, iron is critical for the maintenance of organismal metabolism. Excessive iron facilitates reactive oxygen species generation and inflicts damage on cells and tissues. Ferroptosis, a newly identified iron-dependent type of programmed cell death, has been implicated in a broad set of metabolic disorders. Ferroptosis is mainly characterized by excess iron accumulation, elevated lipid peroxides and reactive oxygen species, and reduced levels of glutathione and glutathione peroxidase 4. The vast emerging literature on ferroptosis has shown that numerous diseases, such as cancers, neurodegeneration, and autoimmune diseases, are associated with ferroptosis. Meanwhile, recent studies have confirmed the relationship between ferroptosis and eye diseases including keratopathy, cataract, glaucoma, retinal ischemia-reperfusion injury, age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and retinoblastoma, indicating the critical role of ferroptosis in ocular diseases. In this article, we introduce the primary signaling pathways of ferroptosis and review current advances in research on ocular diseases involving iron overload and ferroptosis. Furthermore, several unanswered questions in the area are raised. Addressing these unanswered questions promises to provide new insights into preventing, controlling, and treating not only ocular diseases but also a variety of other diseases in the near future.

Ferroptosis contributes to hypoxic-ischemic brain injury in neonatal rats: Role of the SIRT1/Nrf2/GPx4 signaling pathway

AIMS

Hypoxic-ischemic brain injury (HIBI) often results in cognitive impairments. Herein, we investigated the roles of ferroptosis in HIBI and the underlying signaling pathways.

METHODS

Ferrostatin-1 (Fer-1) or resveratrol (Res) treatments were administered intracerebroventricularly 30 min before HIBI in 7-day-old rats. Glutathione peroxidase 4 (GPx4) expression, malondialdehyde (MDA) concentration, iron content, mitochondrial morphology, and the expression of silent information regulator factor 2-related enzyme 1 (SIRT1) and nuclear factor erythroid-2-related factor 2 (Nrf2) were measured after HIBI. Additionally, the weight ratio of left/right hemisphere, brain morphology, Nissl staining, and the Morris water maze test were conducted to estimate brain damage.

RESULTS

At 24-h post-HIBI, GPx4 expression was decreased, and MDA concentration and iron content were increased in the hippocampus. HIBI led to mitochondrial atrophy, brain atrophy/damage, and resultant learning and memory impairments, which were alleviated by Fer-1-mediated inhibition of ferroptosis. Furthermore, Res-mediated SIRT1 upregulation increased Nrf2 and GPx4 expression, thereby attenuating ferroptosis, reducing brain atrophy/damage, and improving learning and memory abilities.

CONCLUSION

The results demonstrated that during HIBI, ferroptosis occurs via the SIRT1/Nrf2/GPx4 signaling pathway, suggesting it as a potential therapeutic target for inhibiting ferroptosis and ameliorating HIBI-induced cognitive impairments.

Hepcidin regulates neuronal ferroptosis: A mechanism for postoperative cognitive dysfunction

Toll-like receptor 4 (TLR4) is a signaling molecule responsible for the expression of hepcidin (Hepc), while myeloid differentiation protein 2 (MD2) is one major accessory protein of TLR4. This study focuses on exploring the neurocyte ferroptosis mediated through the regulation of Hepc expression by MD2, which is also one of the mechanisms for postoperative cognitive dysfunction (POCD). An experimental study was carried out using aged wild-type (Wt) and MD2 transgenic (Tg) mice. The neurocyte ferroptosis and POCD in the mice were assessed following splenectomy. Morris water maze was utilized to assess the neurocognitive abilities, hematoxylin and eosin (H&E) assay was performed to examine histopathology, and Nissl staining was used to evaluate the neurocyte damage. The Fe²⁺ , superoxide dismutase(SOD), malondialdehyde (MDA), glutathione(GSH), and glutathione peroxidase 4 (GPX4) levels were determined with kits. The expressions of transferrin receptor (TFR), Hepc, and MD2 were measured by Western blotting, while the expressions of TFR and GPX4 were measured by immunohistochemical staining. In Tg mice, we observed neurocyte ferroptosis and POCD following treatment with an MD2 inhibitor. PC12 cells were used as a neurocyte model. Ferroptosis was induced after treatment with an MD2 inhibitor, and the cell viability was assayed by Cell Counting Kit-8. Immunofluorescent staining was used to measure the TFR and GPX4 expressions. Meanwhile, the intracellular levels of Fe²⁺ , SOD, MDA, GSH, GPX4, and Hepc were also measured. POCD occurred among aged Wt and Tg mice. The Tg-POCD mice had more apparent POCD than the Wt-POCD mice. Nissl and H&E staining revealed neurocyte damage in brain tissues. Besides this, the Fe²⁺ and MDA expressions were upregulated, while the SOD, GSH, and GPX4 expressions were downregulated. Elevations in tissue levels of TFR, Hepc, and MD2 were observed, which were higher than those of Wt-POCD mice. After treatment with an MD2 inhibitor, the POCD could be prominently ameliorated in Tg-POCD mice, the Fe²⁺ and MDA levels could be reduced, while the SOD, GSH, and GPX4 levels could be elevated. In the PC12 model, ferroptosis could be suppressed by inhibiting the expression of MD2. MD2 is capable of regulating neurocyte ferroptosis by promoting Hepc expression, which has great potential as a novel target for POCD therapy.

Ferroptosis turns 10: Emerging mechanisms, physiological functions, and therapeutic applications

Ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, was identified as a distinct phenomenon and named a decade ago. Ferroptosis has been implicated in a broad set of biological contexts, from development to aging, immunity, and cancer. This review describes key regulators of this form of cell death within a framework of metabolism, ROS biology, and iron biology. Key concepts and major unanswered questions in the ferroptosis field are highlighted. The next decade promises to yield further breakthroughs in the mechanisms governing ferroptosis and additional ways of harnessing ferroptosis for therapeutic benefit.

Multifunctional Nanomaterials for Ferroptotic Cancer Therapy

Patient outcomes from the current clinical cancer therapy remain still far from satisfactory. However, in recent years, several biomedical discoveries and nanotechnological innovations have been made, so there is an impetus to combine these with conventional treatments to improve patient experience and disease prognosis. Ferroptosis, a term first coined in 2012, is an iron-dependent regulated cell death (RCD) based on the production of reactive oxygen species (ROS) and the consequent oxidization of polyunsaturated fatty acids (PUFAs). Many nanomaterials that can induce ferroptosis have been explored for applications in cancer therapy. In this review, we summarize the recent developments in ferroptosis-based nanomaterials for cancer therapy and discuss the future of ferroptosis, nanomedicine, and cancer therapy.

Synergistic Effect of Erastin Combined with Nutlin-3 on Vestibular Schwannoma Cells as p53 Modulates Erastin-Induced Ferroptosis Response

Vestibular schwannoma (VS) is a rare neurotology neoplasm that results in partial neurological defects. As we know, a comprehensive understanding of basic mechanisms and targeted therapy is vital for disease management. In VS, p53 has been proved to suppress tumor progression via a cooperative with the key protein, merlin, as well as regulation of the cell cycle. However, there are more potential mechanisms of p53 in VS needed to exploit. First, via genome-wide RNA expression analysis, we identified differentially expressed genes in VS compared with normal nerves, and then, bioinformatics analyses were used to analyze these differential expression data and suggested a high level of enrichment of cysteine and glutathione metabolism pathways in VS. Meanwhile, we observed a downregulation of SLC7A11/xCT, a component of the cystine/glutamate antiporter (also known as system x_c⁻) involved in cystine uptake. Next, for a deeper study, our group extracted tumor cells from vestibular schwannoma tissues and established two immortalized cell lines named JEI-001 and JEI-002. Secondly, in our established cells, we demonstrated that ferroptosis participated in erastin-induced growth inhibition. As a novel cell death process, ferroptosis driven by iron-mediated lipid reactive oxygen species (lipid ROS), as well as cysteine and glutathione metabolism. Furthermore, ferroptosis contributes to the inhibitory effects of tumor suppressor p53. Here, we show that p53 sensitizes schwannoma cells to ferroptosis by repressing expression of SLC7A11/xCT. Finally, erastin combined with Nutlin-3, which s to p53 activation, triggered antitumor effects of ferroptosis on the growth of schwannoma cells in vitro. These findings present potential mechanism of p53 in schwannomas and raise the possibility of treatment strategies directed against this pathogenesis.

The Use of Informer Sets in Screening: Perspectives on an Efficient Strategy to Identify New Probes

Small-molecule discovery typically involves large-scale screening campaigns, spanning multiple compound collections. However, such activities can be cost- or time-prohibitive, especially when using complex assay systems, limiting the number of compounds tested. Further, low hit rates can make the process inefficient. Sparse coverage of chemical structure or biological activity space can lead to limited success in a primary screen and represents a missed opportunity by virtue of selecting the "wrong" compounds to test. Thus, the choice of screening collections becomes of paramount importance. In this perspective, we discuss the utility of generating "informer sets" for small-molecule discovery, and how this strategy can be leveraged to prioritize probe candidates. While many researchers may assume that informer sets are focused on particular targets (e.g., kinases) or processes (e.g., autophagy), efforts to assemble informer sets based on historical bioactivity or successful human exposure (e.g., repurposing collections) have shown promise as well. Another method for generating informer sets is based on chemical structure, particularly when the compounds have unknown activities and targets. We describe our efforts to screen an informer set representing a collection of 100,000 small molecules synthesized through diversity-oriented synthesis (DOS). This process enables researchers to identify activity early and more extensively screen only a few chemical scaffolds, rather than the entire collection. This elegant and economic outcome is a goal of the informer set approach. Here, we aim not only to shed light on this process, but also to promote the use of informer sets more widely in small-molecule discovery projects.

Mechanisms of Modulation of Ferroptosis and Its Role in Central Nervous System Diseases

Ferroptosis is a new form of programmed cell death characterized by intracellular iron-dependent accumulation of lipid peroxide and primarily associated with iron metabolism, glutathione-dependent pathway, and coenzyme Q10-dependent pathway. Recent studies demonstrate that ferroptosis is associated with central nervous system (CNS) diseases, such as stroke, Parkinson's disease, Alzheimer's disease, and Huntington's disease. This review summarizes the key regulatory mechanisms of ferroptosis and its role in CNS diseases. These updates may provide novel perspective for the development of therapeutical agents against CNS diseases.

A compendium of kinetic modulatory profiles identifies ferroptosis regulators

Cell death can be executed by regulated apoptotic and nonapoptotic pathways, including the iron-dependent process of ferroptosis. Small molecules are essential tools for studying the regulation of cell death. Using time-lapse imaging and a library of 1,833 bioactive compounds, we assembled a large compendium of kinetic cell death modulatory profiles for inducers of apoptosis and ferroptosis. From this dataset we identify dozens of ferroptosis suppressors, including numerous compounds that appear to act via cryptic off-target antioxidant or iron chelating activities. We show that the FDA-approved drug bazedoxifene acts as a potent radical trapping antioxidant inhibitor of ferroptosis both in vitro and in vivo. ATP-competitive mechanistic target of rapamycin (mTOR) inhibitors, by contrast, are on-target ferroptosis inhibitors. Further investigation revealed both mTOR-dependent and mTOR-independent mechanisms that link amino acid metabolism to ferroptosis sensitivity. These results highlight kinetic modulatory profiling as a useful tool to investigate cell death regulation.

Crosstalk between Oxidative Stress and Ferroptosis/Oxytosis in Ischemic Stroke: Possible Targets and Molecular Mechanisms

Oxidative stress is a key cause of ischemic stroke and an initiator of neuronal dysfunction and death, mainly through the overproduction of peroxides and the depletion of antioxidants. Ferroptosis/oxytosis is a unique, oxidative stress-induced cell death pathway characterized by lipid peroxidation and glutathione depletion. Both oxidative stress and ferroptosis/oxytosis have common molecular pathways. This review summarizes the possible targets and the mechanisms underlying the crosstalk between oxidative stress and ferroptosis/oxytosis in ischemic stroke. This knowledge might help to further understand the pathophysiology of ischemic stroke and open new perspectives for the treatment of ischemic stroke.

Ferroptotic pores induce Ca2+ fluxes and ESCRT-III activation to modulate cell death kinetics

Ferroptosis is an iron-dependent form of regulated necrosis associated with lipid peroxidation. Despite its key role in the inflammatory outcome of ferroptosis, little is known about the molecular events leading to the disruption of the plasma membrane during this type of cell death. Here we show that a sustained increase in cytosolic Ca²⁺ is a hallmark of ferroptosis that precedes complete bursting of the cell. We report that plasma membrane damage leading to ferroptosis is associated with membrane nanopores of a few nanometers in radius and that ferroptosis, but not lipid peroxidation, can be delayed by osmoprotectants. Importantly, Ca²⁺ fluxes during ferroptosis induce the activation of the ESCRT-III-dependent membrane repair machinery, which counterbalances the kinetics of cell death and modulates the immunological signature of ferroptosis. Our findings with ferroptosis provide a unifying concept that sustained increase of cytosolic Ca²⁺ prior to plasma membrane rupture is a common feature of regulated types of necrosis and position ESCRT-III activation as a general protective mechanism in these lytic cell death pathways.

Ferroptosis Is a Potential Novel Diagnostic and Therapeutic Target for Patients With Cardiomyopathy

Cardiomyocyte death is a fundamental progress in cardiomyopathy. However, the mechanism of triggering the death of myocardial cells remains unclear. Ferroptosis, which is the nonapoptotic, iron-dependent, and peroxidation-driven programmed cell death pathway, that is abundant and readily accessible, was not discovered until recently with a pharmacological approach. New researches have demonstrated the close relationship between ferroptosis and the development of many cardiovascular diseases, and several ferroptosis inhibitors, iron chelators, and small antioxidant molecules can relieve myocardial injury by blocking the ferroptosis pathways. Notably, ferroptosis is gradually being considered as an important cell death mechanism in the animal models with multiple cardiomyopathies. In this review, we will discuss the mechanism of ferroptosis and the important role of ferroptosis in cardiomyopathy with a special emphasis on the value of ferroptosis as a potential novel diagnostic and therapeutic target for patients suffering from cardiomyopathy in the future.

Ferroptosis: Biochemistry and Biology in Cancers

The challenge of eradicating cancer is that cancer cells possess diverse mechanisms to protect themselves from clinical strategies. Recently, ferroptosis has been shown to exhibit appreciable anti-tumor activity that could be harnessed for cancer therapy in the future. Ferroptosis is an iron-dependent form of regulated cell death that is characterized by the oxidization of polyunsaturated fatty acids (PUFAs) and accumulation of lipid peroxides. Ferroptosis has been closely correlated with numerous biological processes, such as amino acid metabolism, glutathione metabolism, iron metabolism, and lipid metabolism, as well as key regulators including GPX4, FSP1, NRF2, and p53. Although ferroptosis could be involved in killing various cancer cells, multiple aspects of this phenomenon remain unresolved. In this review, we summarize the biochemistry and biology of ferroptosis in diverse cancers and discuss the potential mechanisms of ferroptosis, which might pave the way for guiding cancer therapeutics.

Ferroptosis, trophoblast lipotoxic damage, and adverse pregnancy outcome

Programmed cell death is a central process in the control of tissue development, organismal physiology, and disease. Ferroptosis is a recently identified form of programmed cell death that is uniquely defined by redox-active iron-dependent hydroxy-peroxidation of polyunsaturated fatty acid (PUFA)-containing phospholipids and a loss of lipid peroxidation repair capacity. This distinctive form of lipotoxic cell death has been recently implicated in multiple human diseases, spanning ischemia-reperfusion heart injury, brain damage, acute kidney injury, cancer, and asthma. Intriguingly, settings that have been associated with ferroptosis are linked to placental physiology and trophoblast injury. Such circumstances include hypoxia-reperfusion during placental development, physiological uterine contractions or pathological changes in placental bed perfusion, the abundance of trophoblastic iron, evidence for lipotoxicity during the pathophysiology of major placental disorders such as preeclampsia, fetal growth restriction, and preterm birth, and reduced glutathione peroxidation capacity and lipid peroxidation repair during placental injury. We recently interrogated placental ferroptosis in placental dysfunction in human and mouse pregnancy, dissected its relevance to placental injury, and validated the role of glutathione peroxidase-4 in guarding placental trophoblasts against ferroptotic injury. We also uncovered a role for the phospholipase PLA2G6 (PNPLA9) in attenuating trophoblast ferroptosis. Here, we summarize current data on trophoblast ferroptosis, and the role of several proteins and microRNAs as regulators of this process. Our text offers insights into new opportunities for regulating ferroptosis as a means for protecting placental trophoblasts against lipotoxic injury.

The Multifaceted Regulation of Mitochondria in Ferroptosis

Ferroptosis is characterized as a novel form of regulated cell death, which is initiated by the lethal accumulation of lipid peroxidation catalyzed by cellular labile free iron. This iron driven cell death sharply differs from other well characterized forms of regulated cell death at morphological, genetic and biochemical levels. Increasing research has elaborated a high relevance between dysregulated ferroptosis and the pathogenesis of degenerative diseases and organs injury in human patients. Additionally, targeted induction of ferroptosis is considered as a potentially therapeutic design for the clinical intervention of other therapy-resistant cancers. It is well understood that mitochondria, the cellular powerhouse, determine several types of regulated cell death. Recently, compromised mitochondrial morphology and functionalities have been primarily formulated in ferroptosis. Several mitochondria associated proteins and metabolic processes have been elaborated to fine-tune ferroptotic program. Herein, we critically review the recent advances in this booming field, with focus on summarizing the multifaceted mitochondrial regulation of ferroptosis and providing a perspective on the potential biochemical basis. Finally, we are attempting to shed light on an integrative view on the possibility of mitochondria- and ferroptosis-targeting therapeutics as novel treatment designs for the intervention of ferroptosis related diseases.

TREAP: A New Topological Approach to Drug Target Inference

Over 50% of drugs fail in stage 3 clinical trials, many because of a poor understanding of the drug's mechanisms of action (MoA). A better comprehension of drug MoA will significantly improve research and development (R&D). Current proposed algorithms, such as ProTINA and DeMAND, can be overly complex. Additionally, they are unable to predict whether the drug-induced gene expression or the topology of the networks used to model gene regulation primarily impacts accurate drug target inference. In this work, we evaluate how network and gene expression data affect ProTINA's accuracy. We find that network topology predominantly determines the accuracy of ProTINA's predictions. We further show that the size of an interaction network and/or selecting cell-specific networks has a limited effect on accuracy. We then demonstrate that a specific network topology measure, betweenness, can be used to improve drug target prediction. Based on these results, we create a new algorithm, TREAP, that combines betweenness values and adjusted p-values for target inference. TREAP offers an alternative approach to drug target inference and is advantageous because it is not computationally demanding, provides easy-to-interpret results, and is often more accurate at predicting drug targets than current state-of-the-art approaches.

Abnormal Ferroptosis in Myelodysplastic Syndrome

Background

Ferroptosis is a form of iron-dependent non-apoptotic cell death, with characteristics of loss of the activity of the lipid repair enzyme, glutathione (GSH) peroxidase 4 (GPX4), and accumulation of lethal reactive lipid oxygen species. The mechanism of ferroptosis in myelodysplastic syndrome (MDS) is unclear.

Methods

Cell viability assay, reactive oxygen species (ROS) assay, GSH assay, and GPX activity assay were performed to study the regulation of ferroptosis in MDS cells obtained from MDS patients, the iron overload model mice, and cell lines.

Results

The growth-inhibitory effect of decitabine could be partially reversed by ferrostatin-1 and iron-chelating agent [desferrioxamine (DFO)] in MDS cell lines. Erastin could increase the cytotoxicity of decitabine on MDS cells. The level of GSH and the activity of GPX4 decreased, whereas the ROS level increased in MDS cells upon treatment with decitabine, which could be reversed by ferrostatin-1. The concentration of hemoglobin in peripheral blood of iron overload mice was negatively correlated with intracellular Fe²⁺ level and ferritin concentration. Iron overload (IO) led to decreased viability of bone marrow mononuclear cells (BMMNCs), which was negatively correlated with intracellular Fe²⁺ level. Ferrostatin-1 partially reversed the decline of cell viability in IO groups. The level of GSH and the activity of GPX4 decreased, whereas the ROS level increased in BMMNCs of IO mice. DFO could increase the level of GSH. Ferrostatin-1 and DFO could increase the GPX4 activity of BMMNCs in IO mice. Ferrostatin-1 could significantly reverse the growth-inhibitory effect of decitabine in MDS patients. Decitabine could significantly increase the ROS level in MDS groups, which could be inhibited by ferrostatin-1 or promoted by erastin. Ferrostatin-1 could significantly reverse the inhibitory effect of decitabine on GSH levels in MDS patients. Erastin combined with decitabine could further reduce the GSH level. Erastin could further decrease the activity of GPX4 compared with the decitabine group.

Conclusion

Ferroptosis may account for the main mechanisms of how decitabine induced death of MDS cells. Decitabine-induced ROS raise leads to ferroptosis in MDS cells by decreasing GSH level and GPX4 activity.

Ferroptosis in Acute Central Nervous System Injuries: The Future Direction?

Acute central nervous system (CNS) injuries, such as stroke, traumatic brain injury (TBI), and spinal cord injury (SCI) present a grave health care challenge worldwide due to high morbidity and mortality, as well as limited clinical therapeutic strategies. Established literature has shown that oxidative stress (OS), inflammation, excitotoxicity, and apoptosis play important roles in the pathophysiological processes of acute CNS injuries. Recently, there have been many studies on the topic of ferroptosis, a form of regulated cell death characterized by the accumulation of iron-dependent lipid peroxidation. Some studies have revealed an emerging connection between acute CNS injuries and ferroptosis. Ferroptosis, induced by the abnormal metabolism of lipids, glutathione (GSH), and iron, can accelerate acute CNS injuries. However, pharmaceutical agents, such as iron chelators, ferrostatin-1 (Fer-1), and liproxstatin-1 (Lip-1), can inhibit ferroptosis and may have neuroprotective effects after acute CNS injuries. However, the specific mechanisms underlying this connection has not yet been clearly elucidated. In this paper, we discuss the general mechanisms of ferroptosis and its role in stroke, TBI, and SCI. We also summarize ferroptosis-related drugs and highlight the potential therapeutic strategies in treating various acute CNS injuries. Additionally, this paper suggests a testable hypothesis that ferroptosis may be a novel direction for further research of acute CNS injuries by providing corresponding evidence.

Kinetic Heterogeneity of Cancer Cell Fractional Killing

Lethal drugs can induce incomplete cell death in a population of cancer cells, a phenomenon referred to as fractional killing. Here, we show that high-throughput population-level time-lapse imaging can be used to quantify fractional killing in response to hundreds of different drug treatments in parallel. We find that stable intermediate levels of fractional killing are uncommon, with many drug treatments resulting in complete or near-complete eradication of all cells, if given enough time. The kinetics of fractional killing over time vary substantially as a function of drug, drug dose, and genetic background. At the molecular level, the antiapoptotic protein MCL1 is an important determinant of the kinetics of fractional killing in response to MAPK pathway inhibitors but not other lethal stimuli. These studies suggest that fractional killing is governed by diverse lethal stimulus-specific mechanisms.

The Relationship between Ferroptosis and Tumors: A Novel Landscape for Therapeutic Approach

BACKGROUND

Ferroptosis is a newly discovered form of iron-dependent oxidative cell death characterized by lethal accumulation of lipid-based reactive oxygen species (ROS). It is distinct from other forms of cell death including apoptosis, necrosis, and autophagy in terms of morphology, biochemistry and genetics.

DISCUSSION

Ferroptosis can be induced by system xc- inhibitors or glutathione peroxidase 4 (GPx4) inhibitors, as well as drugs such as sorafenib, sulfasalazine (SAS), and artesunate (ART). Ferroptosis has been recently shown to be critical in regulating growth of tumors, such as hepatocellular carcinoma (HCC), renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC), ovarian cancer, pancreatic carcinoma, and diffuse large B cell lymphoma (DLBCL). Ferroptosis is also associated with resistance to chemotherapeutic drugs and the anti-tumor efficacy of immunotherapy.

CONCLUSION

This review summarizes the mechanism of ferroptosis and its relationship with different types of tumors, to advance our understanding of cell death and to find a novel approach for clinical cancer management.

Molecular Mechanisms of Ferroptosis and Its Role in Pulmonary Disease

Ferroptosis is a new mode of cell death that is characterized by the excessive accumulation of iron and lipid peroxides. It has unique morphological changes and disparate biochemical features and plays an intricate role in many pathophysiological processes. A great deal of researches confirms that ferroptosis can be regulated by numerous molecules through different mechanisms, supporting great potentials for novel pharmacological therapeutics. Recently, several studies reveal that ferroptosis is also closely associated with the initiation and development of respiratory disease. Understanding the specific mechanism, the molecular trait of ferroptosis and their relationship with pulmonary disease could provide significant references regarding effective treatment of these obstinate disease.

Recent progress in nanotechnology based ferroptotic therapies for clinical applications

Ferroptosis is a new iron and reactive oxygen species dependent programmed cell death process which is different from apoptosis, necrosis, and autophagy. It is closely related to a number of disease progression including cancers, neurodegenerative disease, cerebral hemorrhage, liver disease, and renal failure. The development of different ferroptotic inducers has been proved as an efficient therapeutic strategy for a variety of chemoradiotherapy-resistant cancer cells and cancer stem cells. In addition, the development of ferroptotic inhibitors is also becoming an emerging research hotspot for the treatment of many non-cancerous diseases. Furthermore, the combination of nanotechnology with ferroptotic therapies has exhibited additional advantages such as enhanced targeting and/or stimuli-responsive ability to tumor microenvironment, ameliorated drug solubility, ease of preparation and the integration of multifunctional theranostic platforms to develop synergetic combined therapies of great clinical importance. This paper reviews the latest advances of using tailored ferroptotic nanoparticles and ferroptotic molecular probes to be relevant for the accurate diagnosis and treatment of different diseases. Finally, the opportunities and challenges of this burgeoning field were spotlighted to promote the rational design of nano-ferroptotic drugs or theranostic probes in the near future.

Investigating Nonapoptotic Cell Death Using Chemical Biology Approaches

Nonapoptotic cell death is important for human health and disease. Here, we show how various tools and techniques drawn from the chemical biology field have played a central role in the discovery and characterization of nonapoptotic cell death pathways. Focusing on the example of ferroptosis, we describe how phenotypic screening, chemoproteomics, chemical genetic analysis, and other methods enabled the elucidation of this pathway. Synthetic small-molecule inducers and inhibitors of ferroptosis identified in early studies have now been leveraged to identify an even broader set of compounds that affect ferroptosis and to validate new chemical methods and probes for various ferroptosis-associated processes. A number of limitations associated with specific chemical biology tools or techniques have also emerged and must be carefully considered. Nevertheless, the study of ferroptosis provides a roadmap for how chemical biology methods may be used to discover and characterize nonapoptotic cell death mechanisms.

The primary mechanism of cytotoxicity of the chemotherapeutic agent CX-5461 is topoisomerase II poisoning

Small molecules can affect many cellular processes. The disambiguation of these effects to identify the causative mechanisms of cell death is extremely challenging. This challenge impacts both clinical development and the interpretation of chemical genetic experiments. CX-5461 was developed as a selective RNA polymerase I inhibitor, but recent evidence suggests that it may cause DNA damage and induce G-quadraplex formation. Here we use three complimentary data mining modalities alongside biochemical and cell biological assays to show that CX-5461 exerts its primary cytotoxic activity through topoisomerase II poisoning. We then show that acquired resistance to CX-5461 in previously sensitive lymphoma cells confers collateral resistance to the topoisomerase II poison doxorubicin. Doxorubicin is already a frontline chemotherapy in a variety of hematopoietic malignancies, and CX-5461 is being tested in relapse/refractory hematopoietic tumors. Our data suggest that the mechanism of cell death induced by CX-5461 is critical for rational clinical development in these patients. Moreover, CX-5461 usage as a specific chemical genetic probe of RNA polymerase I function is challenging to interpret. Our multimodal data-driven approach is a useful way to detangle the intended and unintended mechanisms of drug action across diverse essential cellular processes.

Doxorubicin loaded ferritin nanoparticles for ferroptosis enhanced targeted killing of cancer cells

In recent years, ferroptosis has been investigated widely as a new form of cell death. Development of nanodrugs for ferroptosis induction in cancer cells may be a promising approach for cancer treatment. Here, we developed a type of nanoparticle consisting of the antitumor drug doxorubicin and exogenous ferritin. The drug loading process did not change the size of ferritin obviously. And this nanoparticle could induce the accumulation of ROS and cell ferroptosis for transferrin receptor overexpressed tumor cell, HT29. The ferroptosis process was also confirmed using inhibitors for ferroptosis. The cytotoxicity of this nanoparticle is similar to that of free DOX. This study provides a new strategy for targeting and killing transferrin receptor overexpressed tumor cells.

Iron and Cancer

This review explores the multifaceted role that iron has in cancer biology. Epidemiological studies have demonstrated an association between excess iron and increased cancer incidence and risk, while experimental studies have implicated iron in cancer initiation, tumor growth, and metastasis. The roles of iron in proliferation, metabolism, and metastasis underpin the association of iron with tumor growth and progression. Cancer cells exhibit an iron-seeking phenotype achieved through dysregulation of iron metabolic proteins. These changes are mediated, at least in part, by oncogenes and tumor suppressors. The dependence of cancer cells on iron has implications in a number of cell death pathways, including ferroptosis, an iron-dependent form of cell death. Uniquely, both iron excess and iron depletion can be utilized in anticancer therapies. Investigating the efficacy of these therapeutic approaches is an area of active research that promises substantial clinical impact.

Aryl-phosphorus-containing flame retardants induce oxidative stress, the p53-dependent DNA damage response and mitochondrial impairment in A549 cells

Aryl phosphorus-containing flame retardants (aryl-PFRs) have been frequently detected with increasingly used worldwide as one of alternatives for brominated flame retardants. However, information on their adverse effects on human health and ecosystem is insufficient, with limited study on their molecular mode of action in vitro. In this study, the cytotoxicity, DNA damage, mitochondrial impairment and the involved molecular mechanisms of certain frequently detectable aryl-PFRs, including 2-ethylhexyldiphenyl phosphate (EHDPP), methyl diphenyl phosphate (MDPP), bisphenol-A bis (diphenyl phosphate) (BDP), isodecyl diphenyl phosphate (IDPP), cresyl diphenyl phosphate (CDP) and the structurally similar and widely used organophosphorus pesticide chlorpyrifos (CPF), were evaluated in A549 cells using high-content screening (HCS) system. Aryl-PFRs showed different lethal concentration 50 (LC50) values ranging from 97.94 to 546.85 μM in A549 cells using CCK-8 assay. EHDPP, IDPP, CDP, MDPP and CPF demonstrated an ability to induce DNA damage, evidenced by increased DNA content and S phase-reducing cell cycle arrest effect using fluorophore dye cocktail assay. Additionally, the selected aryl-PFRs induced mitochondrial impairment by the increasing mitochondrial mass and decreasing mitochondrial membrane potential. Moreover, BDP, MDPP, and CDP, which contain short alkyl chains showed their potential oxidative stress with intracellular ROS and mitochondrial superoxide overproduction from an initially relatively low concentration. Additionally, based on the promotion of firefly luminescence in p53-transfected A549 cells, p53 activation was found to be involved in aryl-PFRs-induced DNA damage. Further real-time PCR results showed that all selected aryl-PFRs triggered p53/p21/gadd45β-, and p53/p21/mdm2-mediated cell cycle pathways, and the p53/bax mediated apoptosis pathway to induce DNA damage and cytotoxic effects. These results suggest that aryl-PFRs (e.g., BDP, MDPP, CDP) cause oxidative stress-mediated DNA damage and mitochondrial impairment, and p53-dependent pathway was involved in the aryl-PFRs-induced DNA damage and cell cycle arrest. In conclusion, this study improves the understanding of PFRs-induced adverse outcomes and the involved molecular mechanism.

Establishing cell painting in a smaller chemical biology lab - A report from the frontier

In this paper we will outline the efforts we have made recently to establish the profiling platform known as cell painting in our laboratory. This platform, which is based on fluorescence microscopy, allows rapid and cheap access to bioactivity fingerprints for small molecules and thereby can contribute with important information in many experimental situations that is faced in laboratories involved in molecular probe design, mode-of-action studies or that perform focused phenotypic screens. We have tried to achieve the following two objectives: (1) provide a detailed description of the hurdles that we had to overcome during establishment and describe our final protocol; (2) provide a more pedagogical description of the different methods used to analyse and represent data from this experiment. Finally, we provide an example of how the method can be used to clarify mechanistic dichotomies.

High-throughput screening and classification of chemicals and their effects on neuronal gene expression using RASL-seq

We previously used RNA-seq to identify chemicals whose effects on neuronal gene expression mimicked transcriptional signatures of autism, aging, and neurodegeneration. However, this approach was costly and time consuming, which limited our study to testing a single chemical concentration on mixed sex cortical neuron cultures. Here, we adapted a targeted transcriptomic method (RASL-seq, similar to TempO-seq) to interrogate changes in expression of a set of 56 signature genes in response to a library of 350 chemicals and chemical mixtures at four concentrations in male and female mouse neuronal cultures. This enabled us to replicate and expand our previous classifications, and show that transcriptional responses were largely equivalent between sexes. Overall, we found that RASL-seq can be used to accelerate the pace at which chemicals and mixtures that transcriptionally mimic autism and other neuropsychiatric diseases can be identified, and provides a cost-effective way to quantify gene expression with a panel of marker genes.