Regulation of lipid peroxidation and ferroptosis in diverse species

Lipid metabolism alterations and ferroptosis in cancer: Paving the way for solving cancer resistance

Cancer often perturbs lipid metabolism, which leads to the alteration of metabolism intermediates, contributing to their deregulated growth and metastasis. Alteration of lipid metabolism shifting to contain more polyunsaturated fatty acids (PUFAs) in membrane phospholipids (PLs) also leads to cancer therapy resistance. High amounts of PL-PUFAs render cancer cells more vulnerable to lipid peroxidation (LPO), predisposing them towards ferroptosis, a new form of iron-dependent oxidative regulated cell death. The commitment of cancer undergoing ferroptotic cell death depends on the adaptive lipidome remodeling, LPO patterns, and LPO scavenging ability in heterogeneous cancer cells. Ferroptosis is receiving attention in cancer research as treating cancers, altering membrane lipid homeostasis, and refractory from conventional therapies. Therefore, a better understanding of the molecular underpinning of lipid metabolism alterations may provide new opportunities for solving cancer resistance. This review intends to understand altered lipid metabolism in cancers and discuss lipid composition and metabolic processes associated with ferroptosis induction in cancers.

Role of ferroptosis in colorectal cancer

Colorectal cancer (CRC) is the second deadliest cancer and the third-most common malignancy in the world. Surgery, chemotherapy, and targeted therapy have been widely used to treat CRC, but some patients still develop resistance to these treatments. Ferroptosis is a novel non-apoptotic form of cell death. It is an iron-dependent non-apoptotic cell death characterized by the accumulation of lipid reactive oxygen species and has been suggested to play a role in reversing resistance to anticancer drugs. This review summarizes recent advances in the prognostic role of ferroptosis in CRC and the mechanism of action in CRC.

A novel ferroptosis-related gene signature for predicting prognosis in multiple myeloma

Background

Multiple myeloma (MM) is a highly malignant hematological tumor with a poor overall survival (OS). Due to the high heterogeneity of MM, it is necessary to explore novel markers for the prognosis prediction for MM patients. Ferroptosis is a form of regulated cell death, playing a critical role in tumorigenesis and cancer progression. However, the predictive role of ferroptosis-related genes (FRGs) in MM prognosis remains unknown.

Methods

This study collected 107 FRGs previously reported and utilized the least absolute shrinkage and selection operator (LASSO) cox regression model to construct a multi-genes risk signature model upon FRGs. The ESTIMATE algorithm and immune-related single-sample gene set enrichment analysis (ssGSEA) were carried out to evaluate immune infiltration level. Drug sensitivity was assessed based on the Genomics of Drug Sensitivity in Cancer database (GDSC). Then the synergy effect was determined with Cell counting kit-8 (CCK-8) assay and SynergyFinder software.

Results

A 6-gene prognostic risk signature model was constructed, and MM patients were divided into high and low risk groups. Kaplan-Meier survival curves showed that patients in the high risk group had significantly reduced OS compared with patients in the low risk group. Besides, the risk score was an independent predictor for OS. Receiver operating characteristic (ROC) curve analysis confirmed the predictive capacity of the risk signature. Combination of risk score and ISS stage had better prediction performance. Enrichment analysis revealed immune response, MYC, mTOR, proteasome and oxidative phosphorylation were enriched in high risk MM patients. We found high risk MM patients had lower immune scores and immune infiltration levels. Moreover, further analysis found that MM patients in high risk group were sensitive to bortezomib and lenalidomide. At last, the results of the in vitro experiment showed that ferroptosis inducers (RSL3 and ML162) may synergistically enhance the cytotoxicity of bortezomib and lenalidomide against MM cell line RPMI-8226.

Conclusion

This study provides novel insights into roles of ferroptosis in MM prognosis prediction, immune levels and drug sensitivity, which complements and improves current grading systems.

Ferroptosis and tumor immunotherapy: A promising combination therapy for tumors

Low response rate and treatment resistance are frequent problems in the immunotherapy of tumors, resulting in the unsatisfactory therapeutic effects. Ferroptosis is a form of cell death characterized by the accumulation of lipid peroxides. In recent years, it has been found that ferroptosis may be related to the treatment of cancer. Various immune cells (including macrophages and CD8⁺ T cells) can induce ferroptosis of tumor cells, and synergistically enhance the anti-tumor immune effects. However, the mechanisms are different for each cell types. DAMP released in vitro by cancer cells undergoing ferroptosis lead to the maturation of dendritic cells, cross-induction of CD8⁺ T cells, IFN-γ production and M1 macrophage production. Thus, it activates the adaptability of the tumor microenvironment and forms positive feedback of the immune response. It suggests that induction of ferroptosis may contribute to reducing resistance of cancer immunotherapy and has great potential in cancer therapy. Further research into the link between ferroptosis and tumor immunotherapy may offer hope for those cancers that are difficult to treat. In this review, we focus on the role of ferroptosis in tumor immunotherapy, explore the role of ferroptosis in various immune cells, and discuss potential applications of ferroptosis in tumor immunotherapy.

Ferroptosis: Underlying mechanism and the crosstalk with other modes of neuronal death after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a serious cerebrovascular disease with high rates of morbidity, mortality, and disability. Optimal treatment of ICH is a major clinical challenge, as the underlying mechanisms remain unclear. Ferroptosis, a newly identified form of non-apoptotic programmed cell death, is characterized by the iron-induced accumulation of lipid reactive oxygen species (ROS), leading to intracellular oxidative stress. Lipid ROS causes damage to nucleic acids, proteins, and cell membranes, eventually resulting in ferroptosis. In the past 10 years, ferroptosis has resulted in plenty of discoveries and breakthroughs in cancer, neurodegeneration, and other diseases. Some studies have also reported that ferroptosis does occur after ICH in vitro and in vivo and contribute to neuronal death. However, the studies on ferroptosis following ICH are still in the preliminary stage. In this review, we will summarize the current evidence on the mechanism underlying ferroptosis after ICH. And review the traditional modes of neuronal death to identify the crosstalk with ferroptosis in ICH, including apoptosis, necroptosis, and autophagy. Additionally, we also aim to explore the promising therapeutic application of ferroptosis in cell death-based ICH.

Transcriptome Analysis of Heat Shock Factor C2a Over-Expressing Wheat Roots Reveals Ferroptosis-like Cell Death in Heat Stress Recovery

Wheat (Triticum aestivum L.) growing areas in many regions of the world are subject to heat waves which are predicted to increase in frequency because of climate change. The engineering of crop plants can be a useful strategy to mitigate heat stress-caused yield losses. Previously, we have shown that heat shock factor subclass C (TaHsfC2a-B)-overexpression significantly increased the survival of heat-stressed wheat seedlings. Although previous studies have shown that the overexpression of Hsf genes enhanced the survival of plants under heat stress, the molecular mechanisms are largely unknown. To understand the underlying molecular mechanisms involved in this response, a comparative analysis of the root transcriptomes of untransformed control and TaHsfC2a-overexpressing wheat lines by RNA-sequencing have been performed. The results of RNA-sequencing indicated that the roots of TaHsfC2a-overexpressing wheat seedlings showed lower transcripts of hydrogen peroxide-producing peroxidases, which corresponds to the reduced accumulation of hydrogen peroxide along the roots. In addition, suites of genes from iron transport and nicotianamine-related gene ontology categories showed lower transcript abundance in the roots of TaHsfC2a-overexpressing wheat roots than in the untransformed control line following heat stress, which are in accordance with the reduction in iron accumulation in the roots of transgenic plants under heat stress. Overall, these results suggested the existence of ferroptosis-like cell death under heat stress in wheat roots, and that TaHsfC2a is a key player in this mechanism. To date, this is the first evidence to show that a Hsf gene plays a key role in ferroptosis under heat stress in plants. In future, the role of Hsf genes could be further studied on ferroptosis in plants to identify root-based marker genes to screen for heat-tolerant genotypes.

Particulate matter induces ferroptosis by accumulating iron and dysregulating the antioxidant system

Particulate matter is an air pollutant composed of various components, and has adverse effects on the human body. Particulate matter is known to induce cell death by generating an imbalance in the antioxidant system; however, the underlying mechanism has not been elucidated. In the present study, we demonstrated the cytotoxic effects of the size and composition of particulate matter on small intestine cells. We found that particulate matter 2.5 (PM2.5) with extraction ion (EI) components (PM2.5 EI), is more cytotoxic than PM containing only polycyclic aromatic hydrocarbons (PAHs). Additionally, PM-induced cell death is characteristic of ferroptosis, and includes iron accumulation, lipid peroxidation, and reactive oxygen species (ROS) generation. Furthermore, ferroptosis inhibitor as liproxstatin-1 and iron-chelator as deferiprone attenuated cell mortality, lipid peroxidation, iron accumulation, and ROS production after PM2.5 EI treatment in human small intestinal cells. These results suggest that PM2.5 EI may increase ferroptotic-cell death by iron accumulation and ROS generation, and offer a potential therapeutic clue for inflammatory bowel diseases in human small intestinal cells. [BMB Reports 2023; 56(2): 96-101].

Iron-based and BRD4-downregulated strategy for amplified ferroptosis based on pH-sensitive/NIR-II-boosted nano-matchbox

Ferroptosis (FPT), a novel form of programmed cell death, is characterized by overwhelming iron/reactive oxygen species (ROS)-dependent accumulation of lipid peroxidation (LPO). However, the insufficiency of endogenous iron and ROS level limited the FPT therapeutic efficacy to a large extent. To overcome this obstacle, the bromodomain-containing protein 4 (BRD₄)-inhibitor (+)-JQ1 (JQ1) and iron-supplement ferric ammonium citrate (FAC)-loaded gold nanorods (GNRs) are encapsulated into the zeolitic imidazolate framework-8 (ZIF-8) to form matchbox-like GNRs@JF/ZIF-8 for the amplified FPT therapy. The existence of matchbox (ZIF-8) is stable in physiologically neutral conditions but degradable in acidic environment, which could prevent the loaded agents from prematurely reacting. Moreover, GNRs as the drug-carriers induce the photothermal therapy (PTT) effect under the irradiation of near-infrared II (NIR-II) light owing to the absorption by localized surface plasmon resonance (LSPR), while the hyperthermia also boosts the JQ1 and FAC releasing in the tumor microenvironment (TME). On one hand, the FAC-induced Fenton/Fenton-like reactions in TME can simultaneously generate iron (Fe³⁺/Fe²⁺) and ROS to initiate the FPT treatment by LPO elevation. On the other hand, JQ1 as a small molecule inhibitor of BRD₄ protein can amplify FPT through downregulating the expression of glutathione peroxidase 4 (GPX4), thus inhibiting the ROS elimination and leading to the LPO accumulation. Both in vitro and in vivo studies reveal that this pH-sensitive nano-matchbox achieves obvious suppression of tumor growth with good biosafety and biocompatibility. As a result, our study points out a PTT combined iron-based/BRD₄-downregulated strategy for amplified ferrotherapy which also opens the door of future exploitation of ferrotherapy systems.

Inhibition of autophagy and MEK promotes ferroptosis in Lkb1-deficient Kras-driven lung tumors

LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC) and cause aggressive tumor growth. Unfortunately, treatment with RAS-RAF-MEK-ERK pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Autophagy, an intracellular nutrient scavenging pathway, compensates for Lkb1 loss to support Kras-driven lung tumor growth. Here we preclinically evaluate the possibility of autophagy inhibition together with MEK inhibition as a treatment for Kras-driven lung tumors. We found that the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and the MEK inhibitor Trametinib displays synergistic anti-proliferative activity in KrasG12D/+;Lkb1-/- (KL) lung cancer cells, but not in KrasG12D/+;p53-/- (KP) lung cancer cells. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination of HCQ and Trametinib on KL but not KP tumors. We further found that the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production, while also increasing lipid peroxidation, indicative of ferroptosis, in KL tumor-derived cell lines (TDCLs) and KL tumors compared to treatment with single agents. Moreover, the reduced tumor growth by the combination treatment was rescued by ferroptosis inhibitor. Taken together, we demonstrate that autophagy upregulation in KL tumors causes resistance to Trametinib by inhibiting ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat NSCLC bearing co-mutations of LKB1 and KRAS.

Trabectedin induces ferroptosis via regulation of HIF-1α/IRP1/TFR1 and Keap1/Nrf2/GPX4 axis in non-small cell lung cancer cells

BACKGROUND AND OBJECTIVES

Non-small cell lung cancer (NSCLC) is a global health concern. NSCLC treatment outcomes are generally poor due to treatment resistance or toxicity. Ferroptosis is a novel cell death triggered by iron accumulation, reactive oxygen species (ROS), and lipid peroxidation. Ferroptosis may kill cancer cells, particularly those resistant to apoptosis.

MATERIALS AND METHODS

The Cell Counting Kit-8 assay assessed NSCLC cell viability after trabectedin treatment. Flow cytometry with Annexin V-FITC staining evaluated cell death. ROS, iron, lipid peroxidation, and GSH levels were measured using commercial kits. qRT-PCR and western blots evaluated messenger RNA and protein levels. Proteins were inhibited using short interfering RNA transfection and specific inhibitors.

RESULTS

Trabectedin was cytotoxic to NSCLC cells regardless of p53 status. Trabectedin upregulated iron, ROS, and lipid peroxidation in NSCLC cells, causing ferroptosis. Trabectedin increases iron and ROS levels by upregulating transferrin receptor 1 and the HIF-1/IRP1 axis. In NSCLC cells, trabectedin suppresses glutathione peroxidase 4, followed by the Keap1/Nrf2 axis.

CONCLUSIONS

Our findings imply that trabectedin may treat NSCLC effectively.

Enhanced photothermal-ferroptosis effects based on RBCm-coated PDA nanoparticles for effective cancer therapy

Ferroptosis, a type of programmed cell death induced by the iron-dependent lipid hydroperoxide pathway, has attracted widespread attention. However, Fenton response-dependent ferroptosis has many limitations, such as insufficient reaction conditions in the tumor micro-environment. Here, we propose an all-in-one phototherapy nanoplatform consisting of iron-polydopamine (Fe-PDA), a folic acid-modified red blood cell membrane (FA-RBCm), and epirubicin (EPI), namely, Fe-PDA-EPI@FA-RBCm NPs, to achieve enhanced photothermal-ferroptosis effects via overcoming the limitations of the Fenton-like reaction. The results showed that the synthesized biomimetic nanoparticles could decompose hydrogen peroxide (H₂O₂) to generate hydroxyl radicals (˙OH), and further induce the non-apoptotic ferroptosis pathway. After irradiation with near-infrared (NIR) light, the uptake of Fe-PDA-EPI@FA-RBCm NPs by cells could be effectively promoted, and it presented impressive in vitro and in vivo photothermal properties. In vitro and in vivo results showed that laser irradiation could enhance ferroptosis by promoting the production of reactive oxygen species (ROS) and lipid peroxides, down-regulating the expression of glutathione peroxidase 4 (GPX4), and reducing the mitochondrial membrane potential. Furthermore, the photothermal-promoted ferroptosis and apoptosis pathways (photothermal therapy and chemotherapy) exhibited outstanding synergistic antitumor efficacy in vitro and in vivo, with an in vivo tumor inhibition rate as high as 76.95%. In conclusion, the construction of tumor-targeted biomimetic nanocarriers utilizing the advantageous properties of RBCm has been investigated as a potential anticancer strategy.

Brain-Targeted HFn-Cu-REGO Nanoplatform for Site-Specific Delivery and Manipulation of Autophagy and Cuproptosis in Glioblastoma

Durable glioblastoma multiforme (GBM) management requires long-term chemotherapy after surgery to eliminate remaining cancerous tissues. Among chemotherapeutics, temozolomide is considered as the first-line drug for GBM therapy, but the treatment outcome is not satisfactory. Notably, regorafenib, an oral multi-kinase inhibitor, has been reported to exert a markedly superior effect on GBM suppression compared with temozolomide. However, poor site-specific delivery and bioavailability significantly restrict the efficient permeability of regorafenib to brain lesions and compromise its treatment efficacy. Therefore, human H-ferritin (HFn), regorafenib, and Cu²⁺ are rationally designed as a brain-targeted nanoplatform (HFn-Cu-REGO NPs), fulfilling the task of site-specific delivery and manipulating autophagy and cuproptosis against GBM. Herein, HFn affords a preferential accumulation capacity to GBM due to transferrin receptor 1 (TfR1)-mediated active targeting and pH-responsive delivery behavior. Moreover, regorafenib can inhibit autophagosome-lysosome fusion, resulting in lethal autophagy arrest in GBM cells. Furthermore, Cu²⁺ not only facilitates the encapsulation of regorafenib to HFn through coordination interaction but also disturbs copper homeostasis for triggering cuproptosis, resulting in a synergistical effect with regorafenib-mediated lethal autophagy arrest against GBM. Therefore, this work may broaden the clinical application scope of Cu²⁺ and regorafenib in GBM treatment via modulating autophagy and cuproptosis.

Iron Induces Resistance Against the Rice Blast Fungus Magnaporthe oryzae Through Potentiation of Immune Responses

Iron is an essential nutrient required for plant growth and development. The availability of iron might also influence disease resistance in plants. However, the molecular mechanisms involved in the plant response to iron availability and immunity have been investigated separately from each other. In this work, we found that exposure of rice plants to high iron enhances resistance to infection by the fungal pathogen Magnaporthe oryzae, the causal agent of blast disease. RNA-Seq analysis revealed that blast resistance in iron-treated rice plants was associated with superinduction of defense-related genes during pathogen infection, including Pathogenesis-Related genes. The expression level of genes involved in the biosynthesis of phytoalexins, both diterpene phytoalexins and the flavonoid phytoalexin sakuranetin, was also higher in iron-treated plants compared with control plants, which correlated well with increased levels of phytoalexins in these plants during M. oryzae infection. Upon pathogen infection, lipid peroxidation was also higher in iron-treated plants compared with non-treated plants. We also show that M. oryzae infection modulates the expression of genes that play a pivotal role in the maintenance of iron homeostasis. Histochemical analysis of M. oryzae-infected leaves revealed colocalization of iron and reactive oxygen species in cells located in the vicinity of fungal penetration sites (e.g. appressoria) in rice plants that have been exposed to iron. Together these findings support that ferroptosis plays a role in the response of iron-treated rice plants to infection by virulent M. oryzae. Understanding interconnected regulations between iron signaling and immune signaling in rice holds great potential for developing novel strategies to improve blast resistance in rice.

Regulation of programmed cell death by Brd4

Epigenetic factor Brd4 has emerged as a key regulator of cancer cell proliferation. Targeted inhibition of Brd4 suppresses growth and induces apoptosis of various cancer cells. In addition to apoptosis, Brd4 has also been shown to regulate several other forms of programmed cell death (PCD), including autophagy, necroptosis, pyroptosis, and ferroptosis, with different biological outcomes. PCD plays key roles in development and tissue homeostasis by eliminating unnecessary or detrimental cells. Dysregulation of PCD is associated with various human diseases, including cancer, neurodegenerative and infectious diseases. In this review, we discussed some recent findings on how Brd4 actively regulates different forms of PCD and the therapeutic potentials of targeting Brd4 in PCD-related human diseases. A better understanding of PCD regulation would provide not only new insights into pathophysiological functions of PCD but also provide new avenues for therapy by targeting Brd4-regulated PCD.

Ferroptosis: a potential therapeutic target for Alzheimer's disease

The most prevalent dementia-causing neurodegenerative condition is Alzheimer's disease (AD). The aberrant buildup of amyloid β and tau hyperphosphorylation are the two most well-known theories about the mechanisms underlying AD development. However, a significant number of pharmacological clinical studies conducted around the world based on the two aforementioned theories have not shown promising outcomes, and AD is still not effectively treated. Ferroptosis, a non-apoptotic programmed cell death defined by the buildup of deadly amounts of iron-dependent lipid peroxides, has received more attention in recent years. A wealth of data is emerging to support the role of iron in the pathophysiology of AD. Cell line and animal studies applying ferroptosis modulators to the treatment of AD have shown encouraging results. Based on these studies, we describe in this review the underlying mechanisms of ferroptosis; the role that ferroptosis plays in AD pathology; and summarise some of the research advances in the treatment of AD with ferroptosis modulators. We hope to contribute to the clinical management of AD.

CD44-Receptor Targeted Gold-Doxorubicin Nanocomposite for Pulsatile Chemo-Photothermal Therapy of Triple-Negative Breast Cancer Cells

This study reports the CD44 receptor-targeted gold-doxorubicin nanocomposite (TGNC-DOX) for pulsatile chemo-photothermal therapy of triple-negative breast cancer (TNBC). The developed TGNC-DOX was nanometric, having a particle size of 71.34 ± 3.66 nm. The doxorubicin was loaded by electrostatic interaction with high entrapment and loading efficiency (>75%). TGNC-DOX showed potent photothermal response and reversible photothermal stability following irradiation with 808 nm NIR laser irradiation. Further, TGNC-DOX showed laser-responsive and pH-dependent drug release behavior suggesting its suitability for chemo-photothermal therapy, specifically at the tumor microenvironment site. Cellular viability, cellular uptake, ROS generation, and apoptosis assays suggested selective localization of TGNC-DOX in cancer cells that showed a significant cytotoxic effect against MDA-MB-231 breast cancer cells. Moreover, the developed TGNC-DOX showed ferroptosis in MDA-MB-231 cells. The event of TGNC-DOX-mediated thermal ablation is marked by a significant generation of reactive oxygen species (ROS) and apoptosis, as affirmed by flow cytometry. NIR-808 laser-responsive photothermal therapy of cancer cells was found to be more effective than without NIR-808 laser-treated cells, suggesting the fundamental role of photothermal ablation. The outcome concludes developed TGNC-DOX is a novel and potential tool to mediate laser-guided chemo-photothermal ablation treatment of cancer cells.

New insights in ferroptosis: Potential therapeutic targets for the treatment of ischemic stroke

Stroke is a common disease in clinical practice, which seriously endangers people's physical and mental health. The neurovascular unit (NVU) plays a key role in the occurrence and development of ischemic stroke. Different from other classical types of cell death such as apoptosis, necrosis, autophagy, and pyroptosis, ferroptosis is an iron-dependent lipid peroxidation-driven new form of cell death. Interestingly, the function of NVU and stroke development can be regulated by activating or inhibiting ferroptosis. This review systematically describes the NVU in ischemic stroke, provides a comprehensive overview of the regulatory mechanisms and key regulators of ferroptosis, and uncovers the role of ferroptosis in the NVU and the progression of ischemic stroke. We further discuss the latest progress in the intervention of ferroptosis as a therapeutic target for ischemic stroke and summarize the research progress and regulatory mechanism of ferroptosis inhibitors on stroke. In conclusion, ferroptosis, as a new form of cell death, plays a key role in ischemic stroke and is expected to become a new therapeutic target for this disease.

Ferroptosis in lymphoma: Emerging mechanisms and a novel therapeutic approach

Unlike apoptosis, necroptosis, autophagy, and pyroptosis, ferroptosis represents a new type of cell death, which is characterized by iron-dependent lipid peroxidation. This process relies largely on the metabolite reactive oxygen species (ROS), phospholipids containing polyunsaturated fatty acids (PUFA-PL), transition metal iron, intra-, and intercellular signaling events, and environmental stress that regulate cellular metabolism and ROS levels. Recent studies show that ferroptosis plays an important role in tumorigenesis, tumor development, and the treatment of hematological malignancies, including lymphoma. Despite the constant emergence of new drugs, the differences in morphological features, immunophenotypes, biological patterns, rates of onset, and response to treatment in lymphoma pose major therapeutic challenges. Since lymphoma is associated with ferroptosis and shows sensitivity towards it, targeting the potential regulatory factors may regulate lymphoma progression. This has emerged as a research hotspot. This review summarizes the current knowledge on ferroptosis induction and resistance mechanisms, their roles and mechanistic details of ferroptosis in lymphoma suppression and immunity, and finally the treatment strategies for lymphoma by targeting ferroptosis.

Selenium: a potent regulator of ferroptosis and biomass production

Emerging evidence supports the notion that selenium (Se) plays a beneficial role in plant development for modern crop production and is considered an essential micronutrient and the predominant source of plants. However, the essential role of selenium in plant metabolism remains unclear. When used in moderate concentrations, selenium promotes plant physiological processes such as enhancing plant growth, increasing antioxidant capacity, reducing reactive oxygen species and lipid peroxidation and offering stress resistance by preventing ferroptosis cell death. Ferroptosis, a recently discovered mechanism of regulated cell death (RCD) with unique features such as iron-dependant accumulation of lipid peroxides, is distinctly different from other known forms of cell death. Glutathione peroxidase (GPX) activity plays a significant role in scavenging the toxic by-products of lipid peroxidation in plants. A low level of GPX activity in plants causes high oxidative stress, which leads to ferroptosis. An integrated view of ferroptosis and selenium in plants and the selenium-mediated nanofertilizers (SeNPs) have been discussed in more recent studies. For instance, selenium supplementation enhanced GPX4 expression and increased TFH cell (Follicular helper T) numbers and the gene transcriptional program, which prevent lipid peroxidase and protect cells from ferroptosis. However, though ferroptosis in plants is similar to that in animals, only few studies have focused on plant-specific ferroptosis; the research on ferroptosis in plants is still in its infancy. Understanding the implication of selenium with relevance to ferroptosis is indispensable for plant bioresource technology. In this review, we hypothesize that blocking ferroptosis cell death improves plant immunity and protects plants from abiotic and biotic stresses. We also examine how SeNPs can be the basis for emerging unconventional and advanced technologies for algae/bamboo biomass production. For instance, algae treated with SeNPs accumulate high lipid profile in algal cells that could thence be used for biodiesel production. We also suggest that further studies in the field of SeNPs are essential for the successful application of this technology for the large-scale production of plant biomass.

Insight into the potential role of ferroptosis in neurodegenerative diseases

Ferroptosis is a newly discovered way of programmed cell death, mainly caused by the accumulation of iron-dependent lipid peroxides in cells, which is morphologically, biochemically and genetically different from the previously reported apoptosis, necrosis and autophagy. Studies have found that ferroptosis plays a key role in the occurrence and development of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and vascular dementia, which suggest that ferroptosis may be involved in regulating the progression of neurodegenerative diseases. At present, on the underlying mechanism of ferroptosis in neurodegenerative diseases is still unclear, and relevant research is urgently needed to clarify the regulatory mechanism and provide the possibility for the development of agents targeting ferroptosis. This review focused on the regulatory mechanism of ferroptosis and its various effects in neurodegenerative diseases, in order to provide reference for the research on ferroptosis in neurodegenerative diseases.

Cadmium induces liver dysfunction and ferroptosis through the endoplasmic stress-ferritinophagy axis

Cadmium (Cd) is a type of high-risk heavy metal that can damage organs such as the liver, but its mechanism is not yet clear. Ferroptosis is a newly discovered mode of regulatory cell death. We explored whether ferroptosis is involved in Cd-induced liver damage and the underlying mechanism. Our research showed that Cd induced liver damage by inducing ferroptosis, and the use of ferroptosis inhibitors reduced the degree of liver damage. Moreover, the occurrence of ferroptosis was accompanied by the activation of the PERK-eIF2α-ATF4-CHOP signaling pathway, and inhibiting endoplasmic reticulum (ER) stress reduced ferroptosis demonstrating that ferroptosis induced by Cd is dependent on ER stress. In addition, chloroquine, a common autophagy inhibitor, mitigated ferroptosis caused by Cd exposure. Then, the iron chelator deferoxamine reduced Cd-induced lipid peroxidation and cell death, demonstrating that the iron regulation disorder caused by ferritin phagocytosis contributes to the Cd-induced ferroptosis. In conclusion, our results show that Cd-induced liver toxicity is accompanied by ferroptosis, which contributes to Cd inducing oxidative stress to trigger autophagy and ER stress to promote the process of ferroptosis.

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.

Quercetin protects rat BMSCs from oxidative stress via ferroptosis

Quercetin has been shown to have a wide range of beneficial effects, such as anti-inflammation, anti-oxidation and immunomodulation. The study was designed to explore the role and molecular mechanisms of quercetin on the protective effect of bone marrow-derived mesenchymal stem cells (BMSCs) under oxidative stress in vitro. BMSCs were isolated from 4-week-old male Sprague-Dawley rats. Upon H2O2 stimulation in vitro, the effects of quercetin on the proliferation, anti-oxidation and osteogenic differentiation of BMSCs were evaluated by Cell Counting Kit-8, reactive oxygen species analysis, Western blot (WB), real-time PCR (RT-PCR), alkaline phosphatase staining and alizarin red staining. Additionally, ferroptosis-related markers were examined by WB, RT-PCR and Mito-FerroGreen. Finally, PI3K/AKT/mTOR signaling pathway was explored in these processes. We found that quercetin significantly maintained BMSCs viability upon H2O2 stimulation. Quercetin upregulated protein (ALP, OPN and RUNX2) and mRNA (Alp, Opn, Ocn and Runx2) levels of osteogenic markers, downregulated ROS levels and upregulated antioxidative gene expressions (Nrf2, Cat, Sod-1 and Sod-2) compared with the H2O2 group. The ferroptosis in BMSCs was activated after H2O2 stimulation, and the phosphorylation level of PI3K, AKT and mTOR was upregulated in H2O2-stimulated BMSCs. More importantly, quercetin inhibited ferroptosis and the phosphorylation level of PI3K, AKT and mTOR were downregulated after quercetin treatment. We conclude that quercetin maintained the viability and the osteoblastic differentiation of BMSCs upon H2O2 stimulation, potentially via ferroptosis inhibition by PI3K/AKT/mTOR pathway.

Identification of a new small molecule that initiates ferroptosis in cancer cells by inhibiting the system Xc- to deplete GSH

Ferroptosis is a non-apoptotic cell death characterized by iron-mediated ROS accumulation and increasing lipid peroxidation. The activation of ferroptosis results in the destruction of cancer cells and overcoming the drug resistance associated with existing chemotherapeutic agents. It is essential to develop new ferroptosis inducers to provide new opportunities for cancer therapy. In this study, we found a small molecule Compound 8 which we had demonstrated to inhibit tumor growth in vivo initiated ferroptosis. Compound 8 treatment elevated the ferroptosis-related genes PTGS2 and CHAC1 mRNA levels in tumor cells. Ferroptosis inhibitors but not the necroptosis inhibitor or the apoptosis inhibitor can suppress the cell death induced by Compound 8. Compound 8 causes overall greater quantity of lipid peroxidation than the classic ferroptosis inducer Erastin through Flow cytometry analysis. The non-targeted lipidomic analysis also showed Compound 8 treatment resulted in oxidized lipid metabolites, similar to Erastin. The mechanism research showed that Compound 8 initiated ferroptosis by inhibiting the system Xc^- to deplete GSH. Based on our previous study that Compound 8 blocked the interaction of PKM2 and VDAC3 (a regulator of ferroptosis) to inhibit tumor growth in vivo, Compound 8 may also trigger ferroptosis by regulating VADC3. Thus, Compound 8 not only will offer a potential tumor therapeutic alternative, but also provide an entrance to explore the new mechanism of ferroptosis.

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

Heme oxygenase-1 modulates ferroptosis by fine-tuning levels of intracellular iron and reactive oxygen species of macrophages in response to Bacillus Calmette-Guerin infection

Macrophages are the host cells and the frontline defense against Mycobacterium tuberculosis (Mtb) infection, and the form of death of infected macrophages plays a pivotal role in the outcome of Mtb infections. Ferroptosis, a programmed necrotic cell death induced by overwhelming lipid peroxidation, was confirmed as one of the mechanisms of Mtb spread following infection and the pathogenesis of tuberculosis (TB). However, the mechanism underlying the macrophage ferroptosis induced by Mtb infection has not yet been fully understood. In the present study, transcriptome analysis revealed the upregulation of heme oxygenase-1 (HMOX1) and pro-ferroptosis cytokines, but downregulation of glutathione peroxidase 4 (GPX4) and other key anti-lipid peroxidation factors in the peripheral blood of both patients with extra-pulmonary tuberculosis (EPTB) and pulmonary tuberculosis (PTB). This finding was further corroborated in mice and RAW264.7 murine macrophage-like cells infected with Bacillus Calmette-Guerin (BCG). A mechanistic study further demonstrated that heme oxygenase-1 protein (HO-1) regulated the production of reactive oxygen species (ROS) and iron metabolism, and ferroptosis in BCG-infected murine macrophages. The knockdown of Hmox1 by siRNA resulted in a significant increase of intracellular ROS, Fe2+, and iron autophagy-mediated factor Ncoa4, along with the reduction of antioxidant factors Gpx4 and Fsp1 in macrophages infected with BCG. The siRNA-mediated knockdown of Hmox1 also reduced cell survival rate and increased the release of intracellular bacteria in BCG-infected macrophages. By contrast, scavenging ROS by N-acetyl cysteine led to the reduction of intracellular ROS, Fe2+, and Hmox1 concentrations, and subsequently inhibited ferroptosis and the release of intracellular BCG in RAW264.7 cells infected with BCG. These findings suggest that HO-1 is an essential regulator of Mtb-induced ferroptosis, which regulates ROS production and iron accretion to alter macrophage death against Mtb infections.

Research progress on ncRNAs regulation of mitochondrial dynamics in diabetes

Diabetes mellitus and its complications are major health concerns worldwide that should be routinely monitored for evaluating disease progression. And there is currently much evidence to suggest a critical role for mitochondria in the common pathogenesis of diabetes and its complications. Mitochondrial dynamics are involved in the development of diabetes through mediating insulin signaling and insulin resistance, and in the development of diabetes and its complications through mediating endothelial impairment and other closely related pathophysiological mechanisms of diabetic cardiomyopathy (DCM). noncoding RNAs (ncRNAs) are closely linked to mitochondrial dynamics by regulating the expression of mitochondrial dynamic-associated proteins, or by regulating key proteins in related signaling pathways. Therefore, this review summarizes the research progress on the regulation of Mitochondrial Dynamics by ncRNAs in diabetes and its complications, which is a promising area for future antibodies or targeted drug development.

PDTAC: Targeted Photodegradation of GPX4 Triggers Ferroptosis and Potent Antitumor Immunity

Targeted degradation of proteins, especially those regarded as undruggable or difficult to drug, attracts wide attention to develop novel therapeutic strategies. Glutathione peroxidase 4 (GPX4), the key enzyme regulating ferroptosis, is currently a target with just covalent inhibitors. Here, we developed a targeted photolysis approach and achieved efficient degradation of GPX4. The photodegradation-targeting chimeras (PDTACs) were synthesized by conjugating a clinically approved photosensitizer (verteporfin) to noninhibitory GPX4-targeting peptides. These chimeras selectively degraded the target protein in both cell lysates and living cells upon red-light irradiation. The targeted photolysis of GPX4 resulted in dominant ferroptotic cell death in malignant cancer cells. Moreover, the dying cells resulting from the PDTACs exhibited potent immunogenicity in vitro and efficiently elicited antitumor immunity in vivo. Our approach therefore provides a novel method to induce GPX4 dysfunction based on noncovalent binding and specifically trigger immunogenic ferroptosis, which may boost the application of ferroptosis in cancer immunotherapy.

Ether lipid deficiency disrupts lipid homeostasis leading to ferroptosis sensitivity

Ferroptosis is an iron-dependent form of regulated cell death associated with uncontrolled membrane lipid peroxidation and destruction. Previously, we showed that dietary dihomo-gamma-linolenic acid (DGLA; 20: 3(n-6)) triggers ferroptosis in the germ cells of the model organism, Caenorhabditis elegans. We also demonstrated that ether lipid-deficient mutant strains are sensitive to DGLA-induced ferroptosis, suggesting a protective role for ether lipids. The vinyl ether bond unique to plasmalogen lipids has been hypothesized to function as an antioxidant, but this has not been tested in animal models. In this study, we used C. elegans mutants to test the hypothesis that the vinyl ether bond in plasmalogens acts as an antioxidant to protect against germ cell ferroptosis as well as to protect from whole-body tert-butyl hydroperoxide (TBHP)-induced oxidative stress. We found no role for plasmalogens in either process. Instead, we demonstrate that ether lipid-deficiency disrupts lipid homeostasis in C. elegans, leading to altered ratios of saturated and monounsaturated fatty acid (MUFA) content in cellular membranes. We demonstrate that ferroptosis sensitivity in both wild type and ether-lipid deficient mutants can be rescued in several ways that change the relative abundance of saturated fats, MUFAs and specific polyunsaturated fatty acids (PUFAs). Specifically, we reduced ferroptosis sensitivity by (1) using mutant strains unable to synthesize DGLA, (2) using a strain carrying a gain-of-function mutation in the transcriptional mediator MDT-15, or (3) by dietary supplementation of MUFAs. Furthermore, our studies reveal important differences in how dietary lipids influence germ cell ferroptosis versus whole-body peroxide-induced oxidative stress. These studies highlight a potentially beneficial role for endogenous and dietary MUFAs in the prevention of ferroptosis.

G9a dictates neuronal vulnerability to inflammatory stress via transcriptional control of ferroptosis

Neuroinflammation leads to neuronal stress responses that contribute to neuronal dysfunction and loss. However, treatments that stabilize neurons and prevent their destruction are still lacking. Here, we identify the histone methyltransferase G9a as a druggable epigenetic regulator of neuronal vulnerability to inflammation. In murine experimental autoimmune encephalomyelitis (EAE) and human multiple sclerosis (MS), we found that the G9a-catalyzed repressive epigenetic mark H3K9me2 was robustly induced by neuroinflammation. G9a activity repressed anti-ferroptotic genes, diminished intracellular glutathione levels, and triggered the iron-dependent programmed cell death pathway ferroptosis. Conversely, pharmacological treatment of EAE mice with a G9a inhibitor restored anti-ferroptotic gene expression, reduced inflammation-induced neuronal loss, and improved clinical outcome. Similarly, neuronal anti-ferroptotic gene expression was reduced in MS brain tissue and was boosted by G9a inhibition in human neuronal cultures. This study identifies G9a as a critical transcriptional enhancer of neuronal ferroptosis and potential therapeutic target to counteract inflammation-induced neurodegeneration.

A non-canonical vitamin K cycle is a potent ferroptosis suppressor

Ferroptosis, a non-apoptotic form of cell death marked by iron-dependent lipid peroxidation¹, has a key role in organ injury, degenerative disease and vulnerability of therapy-resistant cancers². Although substantial progress has been made in understanding the molecular processes relevant to ferroptosis, additional cell-extrinsic and cell-intrinsic processes that determine cell sensitivity toward ferroptosis remain unknown. Here we show that the fully reduced forms of vitamin K—a group of naphthoquinones that includes menaquinone and phylloquinone³—confer a strong anti-ferroptotic function, in addition to the conventional function linked to blood clotting by acting as a cofactor for γ-glutamyl carboxylase. Ferroptosis suppressor protein 1 (FSP1), a NAD(P)H-ubiquinone reductase and the second mainstay of ferroptosis control after glutathione peroxidase-4^4,5, was found to efficiently reduce vitamin K to its hydroquinone, a potent radical-trapping antioxidant and inhibitor of (phospho)lipid peroxidation. The FSP1-mediated reduction of vitamin K was also responsible for the antidotal effect of vitamin K against warfarin poisoning. It follows that FSP1 is the enzyme mediating warfarin-resistant vitamin K reduction in the canonical vitamin K cycle⁶. The FSP1-dependent non-canonical vitamin K cycle can act to protect cells against detrimental lipid peroxidation and ferroptosis.

Biochemical and lipidomic analyses identify an anti-ferroptotic function of vitamin K and reveal ferroptosis suppressor protein 1 (FSP1) as the enzyme mediating warfarin-resistant vitamin K reduction in the canonical vitamin K cycle.

The Role of Ferroptosis in the Damage of Human Proximal Tubule Epithelial Cells Caused by Perfluorooctane Sulfonate

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant and environmental endocrine disruptor that has been shown to be associated with the development of many diseases; it poses a considerable threat to the ecological environment and to human health. PFOS is known to cause damage to renal cells; however, studies of PFOS-induced ferroptosis in cells have not been reported. We used the CCK-8 method to detect cell viability, flow cytometry and immunofluorescence methods to detect ROS levels and Western blot to detect ferroptosis, endoplasmic reticulum stress, antioxidant and apoptosis-related proteins. In our study, we found that PFOS could induce the onset of ferroptosis in HK-2 cells with decreased GPx4 expression and elevated ACSL4 and FTH1 expression, which are hallmarks for the development of ferroptosis. In addition, PFOS-induced ferroptosis in HK-2 cells could be reversed by Fer-1. We also found that endoplasmic reticulum stress and its mediated apoptotic mechanism and P53-mediated antioxidant mechanism are involved in the toxic damage of cells by PFOS. In this paper, we demonstrated for the first time that PFOS can induce ferroptosis in HK-2 cells. In addition, we preliminarily explored other mechanisms of cytotoxic damage by PFOS, which provides a new idea to study the toxicity of PFOS as well as the damage to the kidney and its mechanism.

Ferrocene and glucose oxidase-installed multifunctional hydrogel reactors for local cancer therapy

A hyaluronic acid (HA)-based one-pot hydrogel reactor with single syringe injection and immediate gelation was developed for starvation therapy (ST), chemodynamic therapy (CDT), ferroptosis, and photothermal therapy (PTT) against breast cancer. A rheologically tuned hydrogel network, composed of HA-phenylboronic acid (HP) and HA-dopamine (HD), was designed by introducing a boronate ester linkage (phenylboronic acid-dopamine interaction) and polydopamine bond (pH control). Ferrocene (Fc)-conjugated HP (Fc-HP) was synthesized to achieve ferroptosis, Fenton reaction-involved toxic hydroxyl radical (^•OH) generation, and photothermal ablation in cancer therapy. Glucose oxidase (GOx) was entrapped in the pH-modulated Fc-HP (Fc-HP°)/HD hydrogel network for converting intracellular glucose to H₂O₂ to enable its own supply. The GOx/Fc combination-installed hydrogel reactor system can provide sustained ST/CDT/PTT functions along with ferroptosis. Injection of Fc-HP°/HD/GOx hydrogel with single-syringe injectability, shear-thinning feature, and self-healing capability offered a slow biodegradation rate and high safety profiles. Peritumorally injected Fc-HP°/HD/GOx hydrogel also efficiently suppressed the growth of breast cancer based on multifunctional therapeutic approaches with reduced dosing frequency. Hyperthermia induced by near-infrared (NIR) laser absorption may amplify the therapeutic effects of free radicals. It is expected that this Fc-HP°/HD/GOx hydrogel system can be applied to local cancer therapy with high efficacy and safety profiles.

Targeting ferroptosis as a vulnerability in pulmonary diseases

Ferroptosis is an iron-dependent regulated cell death marked by excessive oxidative phospholipids (PLs). The polyunsaturated fatty acids-containing phospholipids (PUFA-PLs) are highly susceptible to lipid peroxidation under oxidative stress. Numerous pulmonary diseases occurrences and degenerative pathologies are driven by ferroptosis. This review discusses the role of ferroptosis in the pathogenesis of pulmonary diseases including asthma, lung injury, lung cancer, fibrotic lung diseases, and pulmonary infection. Additionally, it is proposed that targeting ferroptosis is a potential treatment for pulmonary diseases, particularly drug-resistant lung cancer or antibiotic-resistant pulmonary infection, and reduces treatment-related adverse events.

A geniposide-phospholipid complex ameliorates posthyperuricemia chronic kidney disease induced by inflammatory reactions and oxidative stress

Hyperuricemia is a common metabolic disease and is one of the factors that could induce chronic kidney disease (CKD). Geniposide (GEN) is a typical natural iridoid glucoside compound with a series of biological activities, but the poor bioavailability of GEN limits its clinical application. In this context, the pharmacological activity of the geniposide-phospholipid complex (GEN-PLC) in ameliorating posthyperuricemia CKD was evaluated by in vitro and in vivo experiments in this study. In vitro cell experiments showed that GEN-PLC treatment markedly decreased inflammatory cytokine levels and reactive oxygen species levels compared with those of GEN in uric acid-treated HKC cells. In vivo research results confirmed that a high concentration of uric acid could cause CKD by increasing inflammatory cytokines and reactive oxygen species in hyperuricemic mice. At the same time, GEN-PLC could regulate the PI3K/AKT/NF-κB and Keap1/Nrf2/HO-1 signaling pathways to effectively inhibit the inflammatory response and oxidative stress, thereby ameliorating posthyperuricemia CKD, and the therapeutic effect was better than that of GEN. In addition, the preparation technology of GEN-PLC was optimized, and the physiochemical analysis explained the intermolecular interactions of the two components. Based on the research results, GEN-PLC could enhance the bioavailability of GEN and become a promising candidate for clinical drug development.

Vitamin C Sensitizes Pancreatic Cancer Cells to Erastin-Induced Ferroptosis by Activating the AMPK/Nrf2/HMOX1 Pathway

Ferroptosis is a type of regulated cell death that displays a promising therapeutic pathway for drug-resistant tumor cells. However, some pancreatic cancer (PC) cells are less sensitive to erastin-induced ferroptosis, and normal pancreatic cells are susceptible to this newly discovered cell death. Therefore, there is an urgent need to find drugs to enhance the sensitivity of these PC cells to erastin while limiting side effects. Here, we found that the oxidized form of vitamin C-dehydroascorbic acid (DHA) can be transported into PC cells expressing high levels of GLUT1, resulting in ferroptosis. Moreover, pharmacological vitamin C combined with erastin can synergistically induce ferroptosis of PC cells involving glutathione (GSH) reduction and ferrous iron accumulation while inhibiting the cytotoxicity of normal cells. Mechanistically, as a direct system Xc^- inhibitor, erastin can directly suppress the synthesis of GSH, and the recycling of vitamin C and DHA is performed through GSH consumption, which is denoted as the classical mode. Furthermore, oxidative stress induced by erastin and vitamin C could enhance the expression of HMOX1 via the AMP-activated protein kinase (AMPK)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway to increase the labile iron level, which is named the nonclassical mode. In vivo experiments showed that erastin and vitamin C can significantly slow tumor growth in PC xenografts. In summary, the combination of erastin and vitamin C exerts a synergistic effect of classical and nonclassical modes to induce ferroptosis in PC cells, which may provide a promising therapeutic strategy for PC.

Eupalinolide B inhibits hepatic carcinoma by inducing ferroptosis and ROS-ER-JNK pathway

Primary hepatic carcinoma is a common malignant tumor. The classic molecular targeted drug sorafenib is costly and is only effective for some patients. Therefore, it is of great clinical significance to search for new molecular targeted drugs. Eupalinolide B (EB) from Eupatorium lindleyanum DC. is used to treat chronic tracheitis in clinical practice. However, the role of EB in hepatic carcinoma is unknown. In this study, we first measure the effect of EB on tumor growth in a xenograft model and PDX model. The cell proliferation and migration are also detected in human hepatocarcinoma cell lines (SMMC-7721 and HCCLM3). Then, we investigate cell cycle, cell apoptosis, cell necrosis, cell autophagy, and ferroptosis by flow cytometry, western blot analysis and electron microscopy. The results demonstrate that EB exerts anti-proliferative activity in hepatic carcinoma by blocking cell cycle arrest at S phase and inducing ferroptosis mediated by endoplasmic reticulum (ER) stress, as well as HO-1 activation. When HO-1 is inhibited, EB-induced cell death and ER protein expression are rescued. The migration-related mechanism consists of activation of the ROS-ER-JNK signaling pathway and is not connected to ferroptosis. In summary, we first discover that EB inhibits cell proliferation and migration in hepatic carcinoma, and thus EB is a promising anti-tumor compound that can be used for hepatic carcinoma.

Iron-overloaded follicular fluid increases the risk of endometriosis-related infertility by triggering granulosa cell ferroptosis and oocyte dysmaturity

Endometriosis (EMs) occurs in approximately 50% of women with infertility. The main causes of EMs-related infertility are follicle dysplasia and reduced oocyte quality. Iron overload occurs in ovarian follicular fluid (FF) of patients with EMs, and this condition is associated with oocyte maturation disorder. However, the underlying molecular mechanism remains largely unknown. In the present study, we identified the mechanism underlying ferroptosis in ovarian granulosa cells and oocyte maturation failure in EMs based on a retrospective review of in vitro fertilization/intracytoplasmic sperm injection-frozen embryo transfer outcomes in infertile patients with EMs. Mouse granulosa cells were treated with EMs-related infertile patients' follicular fluid (EMFF) in vitro. Western blot analysis, quantitative polymerase chain reaction, fluorescence staining, and transmission electron microscopy were used to assess granulosa cells ferroptosis. The effects of exosomes were examined by nanoparticle tracking analysis, RNA-seq, and Western blot analysis. Finally, the therapeutic values of vitamin E and iron chelator (deferoxamine mesylate) in vivo were evaluated in an EMs-related infertility model. Patients with ovarian EMs experienced poorer oocyte fertility than patients with non-ovarian EMs. We observed that EMFF with iron overload-induced granulosa cell ferroptosis in vitro and in vivo. Mechanically, nuclear receptor coactivator four-dependent ferritinophagy was involved in this process. Notably, granulosa cells undergoing ferroptosis further suppressed oocyte maturation by releasing exosomes from granulosa cells. In therapeutic studies, vitamin E and iron chelators effectively alleviated EMs-related infertility models. Our study indicates a novel mechanism through which EMFF with iron overload induces ferroptosis of granulosa cells and oocyte dysmaturity in EMs-related infertility, providing a potential therapeutic strategy for EMs-related infertility.

Zinc oxide nanoparticles synthesized using Hyssopus Officinalis L. Extract Induced oxidative stress and changes the expression of key genes involved in inflammatory and antioxidant Systems

BACKGROUND

Recent advances in the synthesis of bioactive nanoparticles resulted in the discovery and introduction of new bioactive nanoparticles to the pharmaceutical industry. In this regard, this research is aimed to synthesize the zinc oxide nanoparticles (ZnO-NPs) using Hyssopus officinalis L. extract and to evaluate the safety of nanoparticles using Balb/C mice.

METHODS

Forty male mice were divided into four groups and received 0, 50, 100, and 200 mg/kg of ZnO-NPs for thirty days. At the end of the experiment, blood sugar, creatinine, aspartate aminotransferase (A.S.T.), and alanine aminotransferase (A.L.T.) were determined. Furthermore, histopathological and oxidative stress biomarker analyses in liver and kidney tissues were performed. The changes in the major inflammatory- and antioxidant-related genes were determined.

RESULTS

The results showed that blood sugar and creatinine reduced significantly (P < 0.05) when 50, 100, and 200 mg/kg ZnO-NPs were supplemented to the diet. The serum ALT and AST and lipid peroxidation in the liver and kidney tissues were increased significantly (p < 0.05) when 50, 100, and 200 mg/kg ZnO-NPs were supplemented to the diet. Supplementation of ZnO-NPs suppressed the expression of antioxidant-related genes (SOD and CAT) and up-regulated the inflammatory biomarkers (iNOS and TNF- α). The concentration of 200 mg/Kg nanoparticles indicated cellular degeneration and necrosis in the liver and kidney tissues.

CONCLUSIONS

Overall, it can be concluded that supplementation of ZnO-NPs synthesized using Hyssopus Officinalis L. extract in this study at 50 mg/kg or higher concentrations might be toxic to the mice.

Mitochondrial Calcium Uniporter Drives Metastasis and Confers a Targetable Cystine Dependency in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic disease with few effective treatments. Here we show that the mitochondrial calcium uniporter (MCU) promotes PDAC cell migration, invasion, metastasis, and metabolic stress resistance by activating the Keap1-Nrf2 antioxidant program. The cystine transporter SLC7A11 was identified as a druggable target downstream of the MCU-Nrf2 axis. Paradoxically, despite the increased ability to uptake cystine, MCU-overexpressing PDAC demonstrated characteristics typical of cystine-deprived cells and were hypersensitive to cystine deprivation-induced ferroptosis. Pharmacologic inhibitors of SLC7A11 effectively induced tumor regression and abrogated MCU-driven metastasis in PDAC. In patient-derived organoid models in vitro and patient-derived xenograft models in vivo, MCU-high PDAC demonstrated increased sensitivity to SLC7A11 inhibition compared with MCU-low tumors. These data suggest that MCU is able to promote resistance to metabolic stress and to drive PDAC metastasis in a cystine-dependent manner. MCU-mediated cystine addiction could be exploited as a therapeutic vulnerability to inhibit PDAC tumor growth and to prevent metastasis.

SIGNIFICANCE

Elevated mitochondrial calcium uptake in PDAC promotes metastasis but exposes cystine addiction and ferroptosis sensitivity that could be targeted to improve pancreatic cancer treatment.

Nutritional and Metabolic Control of Ferroptosis

Ferroptosis is a type of regulated cell death characterized by an excessive lipid peroxidation of cellular membranes caused by the disruption of the antioxidant defense system and/or an imbalanced cellular metabolism. Ferroptosis differentiates from other forms of regulated cell death in that several metabolic pathways and nutritional aspects, including endogenous antioxidants (such as coenzyme Q₁₀, vitamin E, and di/tetrahydrobiopterin), iron handling, energy sensing, selenium utilization, amino acids, and fatty acids, directly regulate the cells' sensitivity to lipid peroxidation and ferroptosis. As hallmarks of ferroptosis have been documented in a variety of diseases, including neurodegeneration, acute organ injury, and therapy-resistant tumors, the modulation of ferroptosis using pharmacological tools or by metabolic reprogramming holds great potential for the treatment of ferroptosis-associated diseases and cancer therapy. Hence, this review focuses on the regulation of ferroptosis by metabolic and nutritional cues and discusses the potential of nutritional interventions for therapy by targeting ferroptosis. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

An evolutionary conserved detoxification system for membrane lipid-derived peroxyl radicals in Gram-negative bacteria

How double-membraned Gram-negative bacteria overcome lipid peroxidation is virtually unknown. Bactericidal antibiotics and superoxide ion stress stimulate the transcription of the Burkholderia cenocepacia bcnA gene that encodes a secreted lipocalin. bcnA gene orthologs are conserved in bacteria and generally linked to a conserved upstream gene encoding a cytochrome b561 membrane protein (herein named lcoA, lipocalin-associated cytochrome oxidase gene). Mutants in bcnA, lcoA, and in a gene encoding a conserved cytoplasmic aldehyde reductase (peroxidative stress-associated aldehyde reductase gene, psrA) display enhanced membrane lipid peroxidation. Compared to wild type, the levels of the peroxidation biomarker malondialdehyde (MDA) increase in the mutants upon exposure to sublethal concentrations of the bactericidal antibiotics polymyxin B and norfloxacin. Microscopy with lipid peroxidation-sensitive fluorescent probes shows that lipid peroxyl radicals accumulate at the bacterial cell poles and septum and peroxidation is associated with a redistribution of anionic phospholipids and reduced antimicrobial resistance in the mutants. We conclude that BcnA, LcoA, and PsrA are components of an evolutionary conserved, hitherto unrecognized peroxidation detoxification system that protects the bacterial cell envelope from lipid peroxyl radicals.

Opportunities and challenges of using high-sensitivity nanobiosensors to detect long noncoding RNAs: A preliminary review

The two types ofncRNAs, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), are responsible for several biological processes within cells, such as the immune responses, cell growth and invasion, and regulation of the cell cycle. Rapidly expanding class of ncRNAs, lncRNAsinteract with other molecules to form chromatin-remodeling complexes. These potential hallmarks of diseases contribute to transcriptional and post-transcriptional regulation of several genes, possibly via cross-talk with other RNAs. Aberrant expression of lncRNAshas drawn increasing attention to the pathophysiology of different diseases, includingcancer and cardiovasculardiseases. Unfortunately, circulating lncRNAs are presented in the bloodstream at very low levels, making sensitive detection difficult. Currently, there are few methods for detecting these ncRNAs from which quantitative real-time-polymerase chain reaction (qRT-PCR) is the most routinely used technique. These techniqueslack sensitivity for intracellular detection of lncRNAs. Moreover, they are tedious and require a large sample size. Currently, nanotechnology has taken over the diagnostic field because of the tunable properties and modification opportunities. Furthermore, these conventional techniques can be merged with nanotechnology to improve detection sensitivity.This review highlights some of the most recent findings on nanotechnology-based methods and possible obstacles intheir application for moreaccurate sensing of lncRNAs.

FAF1 blocks ferroptosis by inhibiting peroxidation of polyunsaturated fatty acids

Iron-dependent peroxidation of polyunsaturated fatty acids (PUFAs) leads to ferroptosis. While detoxification reactions removing lipid peroxides in phospholipids such as that catalyzed by glutathione peroxidase 4 (GPX4) protect cells from ferroptosis, the mechanism through which cells prevent PUFA peroxidation was not completely understood. We previously identified Fas-associated factor 1 (FAF1) as a protein directly interacting with free PUFAs through its UAS domain. Here we report that this interaction is crucial to protect cells from ferroptosis. In the absence of FAF1, cultured cells became sensitive to ferroptosis upon exposure to physiological levels of PUFAs, and mice developed hepatic injury upon consuming a diet enriched in PUFA. Mechanistically, we demonstrate that FAF1 assembles a globular structure that sequesters free PUFAs into a hydrophobic core, a reaction that prevents PUFA peroxidation by limiting its access to iron. Our study suggests that peroxidation of free PUFAs contributes to ferroptosis, and FAF1 acts upstream of GPX4 to prevents initiation of ferroptosis by limiting peroxidation of free PUFAs.

Moving beyond the Tip of the Iceberg: DJ-1 Implications in Cancer Metabolism

DJ-1, also called Parkinson’s protein 7 (PARK7), is ubiquitously expressed and plays multiple actions in different physiological and, especially, pathophysiological processes, as evidenced by its identification in neurodegenerative diseases and its high expression in different types of cancer. To date, the exact activity of DJ-1 in carcinogenesis has not been fully elucidated, however several recent studies disclosed its involvement in regulating fundamental pathways involved in cancer onset, development, and metastatization. At this purpose, we have dissected the role of DJ-1 in maintaining the transformed phenotype, survival, drug resistance, metastasis formation, and differentiation in cancer cells. Moreover, we have discussed the role of DJ-1 in controlling the redox status in cancer cells, along with the ability to attenuate reactive oxygen species (ROS)-dependent cell death, as well as to mediate ferropotosis. Finally, a mention to the development of therapeutic strategies targeting DJ-1 has been done. We have reported the most recent studies, aiming to shed light on the role played by DJ-1 in different cancer aspects and create the foundation for moving beyond the tip of the iceberg.

Diverse Cell Death Mechanisms Are Simultaneously Activated in Macrophages Infected by Virulent Mycobacterium tuberculosis

Macrophages are necessary to eliminate pathogens. However, some pathogens have developed mechanisms to avoid the immune response. One of them is modulating the cell death mechanism to favor pathogen survival. In this study, we evaluated if virulent Mycobacterium tuberculosis (M. tb) can simultaneously activate more than one cell death mechanism. We infected human monocyte-derived macrophages (MDM) in vitro with avirulent (H37Ra) and virulent (H37Rv) strains, and then we measured molecules involved in apoptosis, necroptosis, and pyroptosis. Our data showed that H37Rv infection increased the BCL-2 transcript and protein, decreased the BAX transcript, and increased phosphorylated BCL-2 at the protein level. Moreover, H37Rv infection increased the expression of the molecules involved in the necroptotic pathway, such as ASK1, p-38, RIPK1, RIPK3, and caspase-8, while H37Ra increased caspase-8 and decreased RIPK3 at the transcriptional level. In addition, NLRP3 and CASP1 expression was increased at low MOI in both strains, while IL-1β was independent of virulence but dependent on infection MOI, suggesting the activation of pyroptosis. These findings suggest that virulent M. tb inhibits the apoptosis mediated by BCL-2 family molecules but, at the same time, increases the expression of molecules involved in apoptosis, necroptosis, and pyroptosis at the transcriptional and protein levels, probably as a mechanism to avoid the immune response and guarantee its survival.