Arsenic induces pancreatic dysfunction and ferroptosis via mitochondrial ROS-autophagy-lysosomal pathway

Ferroptosis and Autophagy-Related Genes in the Pathogenesis of Ischemic Cardiomyopathy

Background

Obesity plays an important role in type 2 diabetes mellitus (T2DM) and myocardial infarction (MI). Ferroptosis and ferritinophagy are related to metabolic pathways, such as fatty acid metabolism and mitochondrial respiration. We aimed to investigate the ferroptosis- and autophagy-related differentially expressed genes (DEGs) that might be potential targets for MI progression.

Methods

GSE116250 was analyzed to obtain DEGs. A Venn diagram was used to obtain the overlapping ferroptosis- and autophagy-related DEGs. The enrichment pathway analysis was performed and the hub genes were obtained. Pivotal miRNAs, transcription factors, and drugs with the hub genes interactions were also predicted. The MI mice model was constructed, and qPCR analysis and single-cell sequencing were used to validate the hub genes.

Results

Utilizing the limma package and the Venn diagram, 26 ferroptosis-related and 29 autophagy-related DEGs were obtained. The list of ferroptosis-related DEGs was analyzed, which were involved in the cellular response to a toxic substance, cellular oxidant detoxification, and the IL-17 signaling pathway. The list of autophagy-related DEGs was involved in the regulation of autophagy, the regulation of JAK-STAT signaling pathway, and the regulation of MAPK cascade. In the protein-protein interaction network, the hub DEGs, such as IL-6, PTGS2, JUN, NQO1, NOS3, LEPR, NAMPT, CDKN2A, CDKN1A, and Snai1, were obtained. After validation using qPCR analysis in the MI mice model and single-cell sequencing, the 10 hub genes can be the potential targets for MI deterioration.

Conclusion

The screened hub genes, IL-6, PTGS2, JUN, NQO1, NOS3, LEPR, NAMPT, CDKN2A, CDKN1A, and Snai1, may be therapeutic targets for patients with MI and may prevent adverse cardiovascular events.

GJA1 reverses arsenic-induced EMT via modulating MAPK/ERK signaling pathway

Arsenic is known as a well-established human carcinogen. Gap Junction Protein Alpha 1 (GJA1) is a multifunction protein that forms gap junction channels and is important for intercellular communication. Recently, its aberrant expression has been shown to associate with cancer recurrence and metastatic spread. However, whether GJA1 plays a role in arsenic carcinogenesis remains unknown. Here, we demonstrated that chronic exposure of human bronchial epithelial BEAS-2B cells to sodium arsenite promoted epithelial-mesenchymal transition (EMT) via increasing the expression of EMT inducer S100A4 and activation of MAPK/ERK signaling. In vitro and in vivo experiments showed that chronic exposure to sodium arsenite reduced GJA1 expression. Forced expression of GJA1 inhibited sodium arsenite-induced EMT via suppressing MAPK/ERK signaling whereas GJA1 knockdown produced an opposite effect. Intriguingly, chronic exposure to sodium arsenite increased autophagy flux. Inhibition of autophagy by pharmacological intervention or genetic deletion of autophagy core gene Beclin-1 upregulated GJA1 expression. These results suggested that GJA1 restrained the carcinogenic effect of sodium arsenite by limiting MAPK/ERK signaling, and GJA1 expression was decreased by arsenic-activated autophagy. In addition, interventions directed at enhancing the level or functional activity of GJA1 could be of preventive and therapeutic interest.

Ferroptosis as a mechanism of non-ferrous metal toxicity

Ferroptosis is a recently discovered form of regulated cell death, implicated in multiple pathologies. Given that the toxicity elicited by some metals is linked to alterations in iron metabolism and induction of oxidative stress and lipid peroxidation, ferroptosis might be involved in such toxicity. Although direct evidence is insufficient, certain pioneering studies have demonstrated a crosstalk between metal toxicity and ferroptosis. Specifically, the mechanisms underlying metal-induced ferroptosis include induction of ferritinophagy, increased DMT-1 and TfR cellular iron uptake, mitochondrial dysfunction and mitochondrial reactive oxygen species (mitoROS) generation, inhibition of Xc-system and glutathione peroxidase 4 (GPX4) activity, altogether resulting in oxidative stress and lipid peroxidation. In addition, there is direct evidence of the role of ferroptosis in the toxicity of arsenic, cadmium, zinc, manganese, copper, and aluminum exposure. In contrast, findings on the impact of cobalt and nickel on ferroptosis are scant and nearly lacking altogether for mercury and especially lead. Other gaps in the field include limited studies on the role of metal speciation in ferroptosis and the critical cellular targets. Although further detailed studies are required, it seems reasonable to propose even at this early stage that ferroptosis may play a significant role in metal toxicity, and its modulation may be considered as a potential therapeutic tool for the amelioration of metal toxicity.

Arsenate and arsenite differential toxicity in Tetrahymena thermophila

A comparative analysis of toxicities of both arsenic forms (arsenite and arsenate) in the model eukaryotic microorganism Tetrahymena thermophila (ciliate protozoa) has shown the presence of various detoxification mechanisms and cellular effects comparable to those of animal cells under arsenic stress. In the wild type strain SB1969 arsenate is almost 2.5 times more toxic than arsenite. According to the concentration addition model used in binary metallic mixtures their toxicities show an additive effect. Using fluorescent assays and flow cytometry, it has been detected that As(V) generates elevated levels of ROS/RNS compared to As(III). Both produce the same levels of superoxide anion, but As(V) also causes greater increases in hydrogen peroxide and peroxynitrite. The mitochondrial membrane potential is affected by both As(V) and As(III), and electron microscopy has also revealed that mitochondria are the main target of both arsenic ionic forms. Fusion/fission and swelling mitochondrial and mitophagy, together with macroautophagy, vacuolization and mucocyst extruction are mainly associated to As(V) toxicity, while As(III) induces an extensive lipid metabolism dysfunction (adipotropic effect). Quantitative RT-PCR analysis of some genes encoding antioxidant proteins or enzymes has shown that glutathione and thioredoxin metabolisms are involved in the response to arsenic stress. Likewise, the function of metallothioneins seems to be crucial in arsenic detoxification processes, after using both metallothionein knockout and knockdown strains and cells overexpressing metallothionein genes from this ciliate. The analysis of the differential toxicity of As(III) and As(V) shown in this study provides cytological and molecular tools to be used as biomarkers for each of the two arsenic ionic forms.

Mitochondrial ROS, ER Stress, and Nrf2 Crosstalk in the Regulation of Mitochondrial Apoptosis Induced by Arsenite

Long-term ingestion of arsenicals, a heterogeneous group of toxic compounds, has been associated with a wide spectrum of human pathologies, which include various malignancies. Although their mechanism of toxicity remains largely unknown, it is generally believed that arsenicals mainly produce their effects via direct binding to protein thiols and ROS formation in different subcellular compartments. The generality of these mechanisms most probably accounts for the different effects mediated by different forms of the metalloid in a variety of cells and tissues. In order to learn more about the molecular mechanisms of cyto- and genotoxicity, there is a need to focus on specific arsenic compounds under tightly controlled conditions. This review focuses on the mechanisms regulating the mitochondrial formation of ROS after exposure to low concentrations of a specific arsenic compound, NaAsO₂, and their crosstalk with the nuclear factor (erythroid-2 related) factor 2 antioxidant signaling and the endoplasmic reticulum stress response.

A minimalist and robust chemo-photothermal nanoplatform capable of augmenting autophagy-modulated immune response against breast cancer

Previously used in anti-fungal therapy, itraconazole has now been shown to be successful in treating advanced breast cancer (NCT00798135). However, its poor solubility still restricts its application in clinical treatment. There is therefore an urgent need for combined methods to enhance the therapeutic effect of itraconazole (IC) in breast cancer treatment. With this goal, co-assembled IC/IR820 NPs with synergistic photonic hyperthermia and itraconazole payloads have been constructed to overcome these shortcomings. The IC/IR820 NPs show an enhanced therapeutic effect on breast cancer by inducing reactive oxygen species (ROS)-mediated apoptosis and autophagic death. Further evaluation in a mouse model has shown impressive effects of the IC/IR820 NPs on both inhibiting tumor metastasis and activating immunity to prevent tumor recurrence. Mechanistically, itraconazole may promote both tumor cell antigen presentation through autophagy and the activation of dendritic cells to induce an immune response, which displays a synergistic effect with the immune response generated by photothermal therapy to inhibit tumor recurrence. This strategy of combining itraconazole and IR820 into one minimalist and robust nanoplatform through co-assembly results in excellent therapeutic efficacy, suggesting its potential application as an alternative method for the clinical treatment of breast cancer.

Nickel oxide nanoparticles induce apoptosis and ferroptosis in airway epithelial cells via ATF3

Exposure to nickel oxide nanoparticles (NiONPs), which have been widely produced and applied in industry, leads to adverse pulmonary and systemic effects. The aim of this study is to investigate the involvement of apoptosis and ferroptosis in NiONPs-induced acute lung injury (ALI). Intratracheal instillation of NiONPs into mice elevated the levels of pro-inflammatory cytokines, neutrophils, and proteins in the bronchoalveolar lavage fluid, and triggered apoptosis and ferroptosis in the lung tissues. Consistently, NiONPs-induced apoptosis and ferroptosis were observed in in vitro experiments using human lung epithelial cells. Activating transcription factor 3 (ATF3), a stress-inducible transcription factor, was upregulated by NiONPs exposure in both murine lung tissues and human lung epithelial cells. Moreover, human lung epithelial cells with ATF3 deficiency exhibited a lower level of apoptosis and ferroptosis when exposed to NiONPs. Collectively, our findings demonstrated that ATF3 was responsive to NiONPs exposure, and promoted NiONPs-induced apoptosis and ferroptosis in lung epithelial cells, indicating that ATF3 is a potential biomarker and therapeutic target for NiONPs-associated ALI.

Ethyl carbamate triggers ferroptosis in liver through inhibiting GSH synthesis and suppressing Nrf2 activation

Humans are inevitably exposed to ethyl carbamate (EC) via consumption of fermented food and beverages. EC, known as an environmental toxin, can cause oxidative stress-mediated severe toxicity, but the underlying mechanisms remain unveiled. Ferroptosis is a newly identified ROS-mediated non-apoptotic cell death characterized by iron accumulation and excessive lipid oxidation. In this study, we first found that EC triggered ferroptosis in liver cells by detection of decreased cell viability, GSH, GPX4 and Ferritin levels, as well as increased iron and MDA contents. Ferroptosis inhibitor ferrostatin-1 (Fer-1) pretreatment rescued ferroptotic damage, indicating that ferroptosis was critical for EC-caused cell death. Furthermore, GSH synthesis precursor N-acetylcysteine displayed significant anti-ferroptotic properties and we suggested that GSH depletion might be the main cause of ferroptosis under EC exposure. EC-triggered GSH depletion mainly depended on suppressed GSH synthesis via inhibition of SLC7A11 and GCLC expressions. Notably, EC blocked Nrf2 activation by repression of phosphorylation modification and nuclear translocation, which further resulted in ferroptosis occurrence. We also observed EC-induced liver dysfunction and inflammation, accompanied with oxidative stress, ferroptosis and downregulated Nrf2 signaling in Balb/c mice, which could be effectively reversed by Fer-1 and tBHQ pretreatment. Together, our study indicated that ferroptosis is a new mechanism for EC-caused toxicity, which was attributed to Nrf2 inactivation and GSH depletion.

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Ethyl carbamate (EC) caused ferroptosis in L02 cells and liver tissues.

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GSH depletion was critical for EC-induced ferroptotic cell death.

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EC exposure blocked GSH synthesis-related pathways.

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Inactivation of Nrf2 signaling was involved in EC-triggered ferroptosis.

Ferroptosis in plants: regulation of lipid peroxidation and redox status

Regulated cell death (RCD) is an essential process that plays key roles along the plant life cycle. Unlike accidental cell death, which is an uncontrolled biological process, RCD involves integrated signaling cascades and precise molecular-mediated mechanisms that are triggered in response to specific exogenous or endogenous stimuli. Ferroptosis is a cell death pathway characterized by the iron-dependent accumulation of lipid reactive oxygen species. Although first described in animals, ferroptosis in plants shares all the main core mechanisms observed for ferroptosis in other systems. In plants as in animals, oxidant and antioxidant systems outline the process of lipid peroxidation during ferroptosis. In plants, cellular compartments such as mitochondria, chloroplasts and cytosol act cooperatively and coordinately to respond to changing redox environments. This particular context makes plants a unique model to study redox status regulation and cell death. In this review, we focus on our most recent understanding of the regulation of redox state and lipid peroxidation in plants and their role during ferroptosis.

Targeting Mitochondrial ROS-Mediated Ferroptosis by Quercetin Alleviates High-Fat Diet-Induced Hepatic Lipotoxicity

Background: The protective effect of quercetin on nonalcoholic fatty liver disease (NAFLD) has been reported, but its mechanism remains poorly understood. Recently, quercetin was reported to be capable of inhibiting ferroptosis, which is a recognized type of regulated cell death. Moreover, hepatic ferroptosis plays an important role in the progression of NAFLD, but experimental evidence is limited. Hence, our study aimed to investigate the effect of quercetin on hepatic ferroptosis in high-fat diet (HFD)-induced NAFLD and further elucidate the underlying molecular mechanism.

Methods: C57BL/6J mice were fed either a normal diet (ND), an HFD, or an HFD supplemented with quercetin for 12 weeks. Hepatic lipid peroxidation, steatosis, ferroptosis and iron overload were examined. In vitro, steatotic L-02 cells was used to study the potential mechanism.

Results: We found that the HFD caused lipid peroxidation, lipid accumulation and ferroptosis in the liver, which were rescued by quercetin supplementation. Consistent with the in vivo results, quercetin alleviated lipid droplet accumulation and reduced the levels of lipid reactive oxygen species (ROS) and ferroptosis in steatotic L-02 cells. Using a mitochondrial ROS (MtROS) scavenger (Mito-TEMPO) and ferroptosis specific inhibitor (Fer-1), we found that quercetin remarkably alleviated lipid droplet accumulation and lipid peroxidation by reducing MtROS-mediated ferroptosis in steatotic L-02 cells.

Conclusion: Our data showed that HFD consumption induced lipid accumulation and triggered ferroptosis in liver, ultimately leading to hepatic lipotoxicity, which can be alleviated by quercetin. Findings from this study provide new insight into the mechanism by which quercetin can be used for the prevention and treatment of NAFLD.

Glycyrrhizin Attenuates Hypoxic-Ischemic Brain Damage by Inhibiting Ferroptosis and Neuroinflammation in Neonatal Rats via the HMGB1/GPX4 Pathway

With unknown etiology and limited treatment options, neonatal hypoxic-ischemic brain damage (HIBD) remains a major cause of mortality in newborns. Ferroptosis, a recently discovered type of cell death triggered by lipid peroxidation, is closely associated with HIBD. High-mobility group box 1 (HMGB1), a molecule associated with inflammation damage, can induce neuronal death in HIBD. However, it remains unknown whether HMGB1 contributes to neuronal ferroptosis in patients with HIBD. Herein, glycyrrhizin (GL), an HMGB1 inhibitor, was used to investigate the relationship between ferroptosis and HMGB1. RAS-selective lethal 3(RSL3), a ferroptosis agonist, was administered to further confirm the changes in the signaling pathway between HMGB1 and ferroptosis. Western blot analysis revealed that GL markedly suppressed the expression of HMGB1 and increased the level of GPX4 in the context of HIBD. We observed changes in neuronal ultrastructure via transmission electron microscopy to further confirm the occurrence of ferroptosis. Real-time PCR indicated that GL inhibited the expression of ferroptosis-related genes and inflammatory factors. Immunofluorescence and immunohistochemistry staining confirmed GL inhibition of neuronal damage and ferroptosis in HIBD associated with GPX4 and ROS. GL not only inhibited ferroptosis induced by RSL3 and oxygen-glucose deprivation in vitro but also inhibited ferroptosis induced by HIBD in vivo. More importantly, GL may improve oxidative stress imbalance and mitochondrial damage, alleviate the downstream production of inflammatory factors, and ultimately reduce ferroptosis and damage to cortical neurons following HIBD via the HMGB1/GPX4 pathway. In conclusion, we showed for the first time that GL could suppress the occurrence of neuronal ferroptosis and reduce neuronal loss in HIBD via the HMGB1/GPX4 pathway. These findings highlight the potential of HMGB1 signaling antagonists to treat neuronal damage by suppressing ferroptosis, provide new and unique insights into GL as a neuroprotective agent, and suggest new prevention and treatment strategies for HIBD.

Mechanistic understanding of the toxic effects of arsenic and warfare arsenicals on human health and environment

Worldwide, more than 200 million people are estimated to be exposed to unsafe levels of arsenic. Chronic exposure to unsafe levels of groundwater arsenic is responsible for multiple human disorders, including dermal, cardiovascular, neurological, pulmonary, renal, and metabolic conditions. Consumption of rice and seafood (where high levels of arsenic are accumulated) is also responsible for human exposure to arsenic. The toxicity of arsenic compounds varies greatly and may depend on their chemical form, solubility, and concentration. Surprisingly, synthetic organoarsenicals are extremely toxic molecules which created interest in their development as chemical warfare agents (CWAs) during World War I (WWI). Among these CWAs, adamsite, Clark I, Clark II, and lewisite are of critical importance, as stockpiles of these agents still exist worldwide. In addition, unused WWII weaponized arsenicals discarded in water bodies or buried in many parts of the world continue to pose a serious threat to the environment and human health. Metabolic inhibition, oxidative stress, genotoxicity, and epigenetic alterations including micro-RNA-dependent regulation are some of the underlying mechanisms of arsenic toxicity. Mechanistic understanding of the toxicity of organoarsenicals is also critical for the development of effective therapeutic interventions. This review provides comprehensive details and a critical assessment of recently published data on various chemical forms of arsenic, their exposure, and implications on human and environmental health.

Tetrandrine Ameliorates Traumatic Brain Injury by Regulating Autophagy to Reduce Ferroptosis

Traumatic brain injury (TBI) is the leading cause of death and disability in trauma patients. However, the effects and mechanism of autophagy after TBI remain unclear. This study aimed to investigate whether tetrandrine could ameliorate TBI through autophagy to reduce ferroptosis. A mice model for TBI was implemented. Behavioral and histomorphological experiments were performed to evaluate outcomes of the mice. The ferroptosis levels was detected by Perls staining. Enzyme-linked immunosorbent assay (ELISA) was applied to detect malondialdehyde (MDA), glutathione (GSH), and glutathione peroxidase 4 (GPX4) levels in the brain tissue. Western blot test was performed to detect Beclin 1, light chain 3 (LC3) II/I, p62, GPX4, SCL7A11, and ferritin heavy chain 1 (FTH1) levels, and the expression of LC3B, Beclin 1, GPX4, and FTH1 in the brain tissue was detected by immunofluorescence (IF). The behavioral and histomorphological results demonstrated that tetrandrine improved the neurological function and cerebral edema on days 1, 3, and 7 after TBI. The ELISA results suggested that tetrandrine reduced the MDA concentration and increased GSH concentration on days 1, 3, and 7 after TBI. IF staining and Perls staining reflected that tetrandrine promoted autophagy and inhibited ferroptosis on days 1, 3, and 7 after TBI, respectively. Tetrandrine further improved the neurological function, cerebral edema, autophagy, and ferroptosis on days 1, 3, and 7 after TBI after adding the autophagy inducer rapamycin. The effect of TET in alleviating TBI increased with the increase of time and dose. Tetrandrine ameliorated TBI by regulating autophagy to reduce ferroptosis, providing a new therapeutic strategy for TBI.

Bupivacaine modulates the apoptosis and ferroptosis in bladder cancer via phosphatidylinositol 3-kinase (PI3K)/AKT pathway

The study aimed to explore the effects of local anesthetic bupivacaine on bladder cancer cells in vivo and in vitro. The cytotoxicity was detected by MTT assay. Apoptosis was measured by Hoechst 33342 staining and TUNEL. The contents of Fe²⁺, Malondialdehyde (MDA), Glutathione (GSH) and reactive oxygen species (ROS) were evaluated by the corresponding kit. Mitochondrial membrane potential was assessed by JC-1 kit. HE staining, TUNEL and immunohistochemistry were used to detect the xenografted tumors. Protein expression was estimated by Western blot. Bupivacaine significantly inhibited the activity of T24 cells and 5637 cells at 0.25-16 mM. Bupivacaine promoted cell apoptosis with increased concentration. bupivacaine inhibited the expression of Bcl-2 and increased the expression of Bax and cytochrome C. Moreover, bupivacaine amplified the level of Fe²⁺ and ROS, and restrained the expression of cystine/glutamic acid reverse transporter (xCT) and glutathione peroxidase 4 (GPX4). Further results showed that bupivacaine decreased mitochondrial membrane potential, reduced GSH, and increased MDA levels. Besides, bupivacaine attenuated the phosphorylation of PI3K, Akt, and mTOR. In addition, bupivacaine suppressed the growth of xenografted tumors, induced apoptosis and ferroptosis, and inhibited the activity of PI3K/AKT signaling pathway in xenografted tumors. Bupivacaine could induce apoptosis and ferroptosis by inhibiting PI3K/Akt signaling pathway in bladder cancer cells.

Protective Effects of Alpha Lipoic Acid Against Arsenic Induced Oxidative Stress in Isolated Rat Liver Mitochondria

Arsenic as a heavy metal and toxic pollutant has been established that has the hepatotoxic effect in animal and human models. Previous studies showed that mitochondria as the first target of arsenic toxicity has a pathogenic role in liver diseases. This study investigated alpha lipoic acid (ALA) as an antioxidant could ameliorate against liver toxicity induced by arsenic in rat mitochondria. First, mitochondria were isolated by the liver tissue centrifugation protocol. Then, isolated mitochondria were exposed with different concentrations of ALA and arsenic in different times for receiving the optimum dose and time. Finally, mitochondria were pretreated with the optimum concentrations and times of ALA and then treated with optimum concentration and time of arsenic (160 μg/ml; 30 min). The results demonstrated a significant decrease in total mitochondrial dehydrogenase activity (mitochondrial complex II) by 3, 4 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay after arsenic exposure. Mitochondria treated with arsenic also showed a significant increase in ROS generation, MMP, and MDA levels. The activity of mitochondrial catalase and mitochondrial GSH significantly decreased after exposure of mitochondria with arsenic. Pretreatment of mitochondria with ALA improved mitochondrial complex II activity; decreased mitochondrial membrane damage, MDA, and ROS amounts; and ameliorated mitochondrial GSH levels and mitochondrial catalase activity. These findings revealed that arsenic induced oxidative stress and mitochondria dysfunction, while ALA improved mitochondrial function through increasing of antioxidant defense or preserving of complex II, but suggested that ALA could prevent from mitochondria dysfunction.

Arsenic trioxide-induced cardiotoxicity triggers ferroptosis in cardiomyoblast cells

Arsenic trioxide (ATO) has been found to be effective in acute promyelocytic leukemia. However, ATO-induced severe cardiotoxicity limits its clinical application. To date, the mechanisms of ATO-induced cardiotoxicity remain unclear. It is hypothesized that ferroptosis may trigger ATO-induced cardiotoxicity; however, this has not yet been investigated. To clarify this hypothesis, rat cardiomyocyte H9c2 cells were treated with ATO with or without ferrostain-1 (Fer-1). The results indicated that ATO exposure induced H9c2 cell death and apoptosis, and the ferroptosis inhibitor Fer-1, administered for 24 h before ATO exposure, suppressed ATO-induced cell death, and apoptosis, as determined by Annexin V-APC/7-AAD apoptosis assay. Furthermore, Fer-1 displayed a cardioprotective effect through inhibiting the ATO-induced production of intracellular reactive oxygen species, improving the ATO-induced loss of the mitochondrial membrane potential, alleviating hyperactive endoplasmic reticulum stress, and alleviating the ATO-induced impairment in autophagy in H9c2 cells. Overall, the cardioprotective effect of Fer-1 against ATO-induced cell injury implies that ATO may trigger ferroptosis to induce cardiotoxicity. These findings lay the foundation for exploring the potential value of ferroptosis inhibitors against ATO-induced cardiotoxicity in the future.

Mitochondrial oxidative stress mediated Fe-induced ferroptosis via the NRF2-ARE pathway

Ferroptosis is a regulated form of cell death induced by iron (Fe)-dependent lipid peroxidation. At present, the underlying molecular mechanisms remain elusive. Herein, we hypothesized that mitochondria and the NRF2 (transcription factor nuclear factor E2-related factor 2) are potential mediators of ferroptosis, considering their well-established involvement in the oxidative stress pathway. We found that a high iron diet increased hepatic iron content and promoted glutathione (GSH) depletion, lipid peroxidation and oxidative stress. Dietary iron overload also decreased mRNA and protein expression levels of glutathione peroxidase 4 (GPX4) and cystine-glutamate antiporter (SLC7A11), and increased mRNA and protein expression of acyl-CoA synthetase long-chain family member 4 (ACSL4), which are all markers of ferroptosis. Consistent with ferroptosis, iron overload promoted lipid peroxidation and the generation of mitochondrial reactive oxygen species (ROS), and decreased the mitochondrial membrane potential (MMP). Pre-treatment with deferoxamine mesylate (DFO, an iron chelator) alleviated ROS generation and lipid peroxidation, indicating a causative link between iron overload and lipid peroxidation. Suppression of mitochondrial oxidative stress attenuated ferroptosis. Experiments with HEK293T cells revealed that Fe-induced ferroptosis involved direct inhibition of NRF2 binding to antioxidant response elements (AREs) within the promoters of the gpx4 and slc7a11 genes, which in turn induced transcriptional silencing. In conclusion, our study provided a direct link between mitochondrial oxidative stress and ferroptosis via the NRF2-ARE pathway.

Prognostication of Pancreatic Cancer Using The Cancer Genome Atlas Based Ferroptosis-Related Long Non-Coding RNAs

Background: Long non-coding RNAs (lncRNAs) are key regulators of pancreatic cancer development and are involved in ferroptosis regulation. LncRNA transcript levels serve as a prognostic factor for pancreatic cancer. Therefore, identifying ferroptosis-related lncRNAs (FRLs) with prognostic value in pancreatic cancer is critical.

Methods: In this study, FRLs were identified by combining The Cancer Genome Atlas (TCGA) and FerrDb databases. For training cohort, univariate Cox, Lasso, and multivariate Cox regression analyses were applied to identify prognosis FRLs and then construct a prognostic FRLs signature. Testing cohort and entire cohort were applied to validate the prognostic signature. Moreover, the nomogram was performed to predict prognosis at different clinicopathological stages and risk scores. A co-expression network with 76 lncRNA-mRNA targets was constructed.

Results: Univariate Cox analysis was performed to analyze the prognostic value of 193 lncRNAs. Furthermore, the least absolute shrinkage and selection operator and the multivariate Cox analysis were used to assess the prognostic value of these ferroptosis-related lncRNAs. A prognostic risk model, of six lncRNAs, including LINC01705, AC068620.2, TRAF3IP2-AS1, AC092171.2, AC099850.3, and MIR193BHG was constructed. The Kaplan Meier (KM) and time-related receiver operating characteristic (ROC) curve analysis were performed to calculate overall survival and compare high- and low-risk groups. There was also a significant difference in survival time between the high-risk and low-risk groups for the testing cohort and the entire cohort, with AUCs of .723, .753, respectively. Combined with clinicopathological characteristics, the risk model was validated as a new independent prognostic factor for pancreatic adenocarcinoma through univariate and multivariate Cox regression. Moreover, a nomogram showed good prediction.

Conclusion: The signature of six FRLs had significant prognostic value for pancreatic adenocarcinoma. They may be a promising therapeutic target in clinical practice.

Ferroptosis in cancer and cancer immunotherapy

The hallmark of tumorigenesis is the successful circumvention of cell death regulation for achieving unlimited replication and immortality. Ferroptosis is a newly identified type of cell death dependent on lipid peroxidation which differs from classical programmed cell death in terms of morphology, physiology and biochemistry. The broad spectrum of injury and tumor tolerance are the main reasons for radiotherapy and chemotherapy failure. The effective rate of tumor immunotherapy as a new treatment method is less than 30%. Ferroptosis can be seen in radiotherapy, chemotherapy, and tumor immunotherapy; therefore, ferroptosis activation may be a potential strategy to overcome the drug resistance mechanism of traditional cancer treatments. In this review, the characteristics and causes of cell death by lipid peroxidation in ferroptosis are briefly described. In addition, the three metabolic regulations of ferroptosis and its crosstalk with classical signaling pathways are summarized. Collectively, these findings suggest the vital role of ferroptosis in immunotherapy based on the interaction of ferroptosis with tumor immunotherapy, chemotherapy and radiotherapy, thus, indicating the remarkable potential of ferroptosis in cancer treatment.

The BMSC-derived exosomal lncRNA Mir9-3hg suppresses cardiomyocyte ferroptosis in ischemia-reperfusion mice via the Pum2/PRDX6 axis

BACKGROUND AND AIMS

The exosomal long noncoding RNAs (lncRNAs) have been reported to have cardioprotective effects on ischemia-reperfusion (I/R) injury by hindering ferroptosis, but the role of lncRNA Mir9-3 host gene (Mir9-3hg) in cardiac I/R injury remains unclear.

METHODS AND RESULTS

Exosomes were extracted from mouse bone marrow mesenchymal stem cells (BMSCs) and identified by detecting the exosome specific marker levels, and the results showed that Mir9-3hg was highly expressed in BMSCs-Exo. Hypoxia/reoxygenation (H/R)-treated HL-1 mouse cardiomyocytes were incubated with exosomes extracted from BMSCs transfected with Mir9-3hg siRNA. BMSCs-Exo incubation observably facilitated cell proliferation, increased glutathione (GSH) content, and reduced iron ion concentration, reactive oxygen species (ROS) level and ferroptosis marker protein levels in H/R-treated cells, while interfering Mir9-3hg reversed these effects. RNA binding protein immunoprecipitation assay was found that Mir9-3hg bound with pumilio RNA binding family member 2 (Pum2) protein and downregulated Pum2 expression. Silence of Pum2 reversed the effects of Mir9-3hg inhibition on cell functions. Chromatin immunoprecipitation assay was revealed that Pum2 bound with peroxiredoxin 6 (PRDX6) promoter and restrained PRDX6 expression. Silence of PRDX6 reversed the improved effects of Pum2 downregulation on cell functions. Additionally, BMSCs-Exo treatment ameliorated cardiac function in I/R-treated mice by inhibiting cardiomyocyte ferroptosis.

CONCLUSIONS

BMSCs-Exo treatment attenuates I/R-induced cardiac injury by inhibiting cardiomyocyte ferroptosis through modulating the Pum2/PRDX6 axis, thereby ameliorating cardiac function.

Targeting ferroptosis in acute kidney injury

Acute kidney injury (AKI) is a major public health problem with high incidence and mortality. As a form of programmed cell death (PCD), ferroptosis could be considered as a process of iron accumulation and enhanced lipid peroxidation. Recently, the fundamental roles of ferroptosis in AKI have attracted much attention. The network mechanism of ferroptosis in AKI and its roles in the AKI to chronic kidney disease (CKD) transition is complicated and multifactorial. Strategies targeting ferroptosis show great potential. Here, we review the research progress on ferroptosis and its participation in AKI. We hope that this work will provide clues for further studies of ferroptosis in AKI.

Low-intensity pulsed ultrasound-generated singlet oxygen induces telomere damage leading to glioma stem cell awakening from quiescence

Cancer stem cells, quiescent and drug resistant, have become a therapeutic target. Unlike high-intensity focused ultrasound directly killing tumor, low-intensity pulsed ultrasound (LIPUS), a new noninvasive physical device, promotes pluripotent stem cell differentiation and is primarily applied in tissue engineering but rarely in oncotherapy. We explored the effect and mechanism of LIPUS on glioma stem cell (GSC) expulsion from quiescence. Here, we observed that LIPUS led to attenuated expression of GSC biomarkers, promoted GSC escape from G0 quiescence, and significantly weakened the Wnt and Hh pathways. Of note, LIPUS transferred sonomechanical energy into cytochrome c and B5 proteins, which converted oxygen molecules into singlet oxygen, triggering telomere crisis. The in vivo and in vitro results confirmed that LIPUS enhanced the GSC sensitivity to temozolomide. These results demonstrated that LIPUS "waked up" GSCs to improve their sensitivity to chemotherapy, and importantly, we confirmed the direct targeted proteins of LIPUS in GSCs.

Alliin alleviates LPS-induced pyroptosis via promoting mitophagy in THP-1 macrophages and mice

Pyroptosis is a new type of programmed cell death associated with inflammation. Excessive pyroptosis can cause body damage. Alliin is an organosulfur compound extracted from garlic, bearing anti-oxidation and anti-inflammatory properties. In this study, we revealed that alliin alleviated LPS-induced macrophage pyroptosis by detecting PI staining, IL-1β and IL-18 release in vitro and in vivo. In the study of mechanism, we found that alliin might reduce the activation of NLRP3 inflammosome by decreasing intracellular ROS generation. Subsequently, we detected the effect of alliin on mitophagy which degraded damaged mitochondria. The results showed that alliin promoted PINK 1/Parkin-mediated mitophagy. After adding the mitophagy inhibitor CsA, the alleviating effect of alliin on mitochondrial damage and mitochondrial ROS were reversed and the relieving effect of alliin on LPS-induced pyroptosis was inhibited. These results suggested that alliin might reduce intracellular ROS production by promoting mitophagy, thus alleviating LPS-induced macrophages pyroptosis. Our study provides a new perspective and theoretical basis for alliin to alleviate pyroptosis which could further induce body damage.

Cadmium induces ferroptosis and apoptosis by modulating miR-34a-5p/Sirt1axis in PC12 cells

Cadmium (Cd) is a potent neurotoxic metal present in the environment and food. In this study, CdCl₂ (2 or 4 μM) induced cytotoxicity and neurotoxicity in PC12 cells, causing decreases in cell viability and NEP protein expression and increase in p-tau protein expression. For the first time, CdCl₂ -initiated injury was found to result from the induction of not only apoptosis but also ferroptosis, as evidenced by the increased iron content, ROS production, and mitochondrial membrane potential along with changes in the expressions of iron death-related genes (FTH1, GPX4, ASCL4, PTGS2, and NOX1) and levels of caspase9, Bax, and Bcl-2 proteins. The molecular mechanisms leading to apoptosis and ferroptosis at least included the participation of the miR-34a-5p/Sirt1 axis, in which miR-34a-5p promoted CdCl₂ -induced neurotoxicity through targeting Sirt1. Knocking out miR-34a-5p attenuated CdCl₂ -induced damage of PC12 cells, cytotoxicity and neurotoxicity. This research provides the underlying molecular mechanisms of CdCl₂ -induced damage and asserts the role of miRNAs as critical regulators.

Ferroptosis as a Novel Therapeutic Target for Diabetes and Its Complications

The global diabetes epidemic and its complications are increasing, thereby posing a major threat to public health. A comprehensive understanding of diabetes mellitus (DM) and its complications is necessary for the development of effective treatments. Ferroptosis is a newly identified form of programmed cell death caused by the production of reactive oxygen species and an imbalance in iron homeostasis. Increasing evidence suggests that ferroptosis plays a pivotal role in the pathogenesis of diabetes and diabetes-related complications. In this review, we summarize the potential impact and regulatory mechanisms of ferroptosis on diabetes and its complications, as well as inhibitors of ferroptosis in diabetes and diabetic complications. Therefore, understanding the regulatory mechanisms of ferroptosis and developing drugs or agents that target ferroptosis may provide new treatment strategies for patients with diabetes.

Is Arsenic Exposure a Risk Factor for Metabolic Syndrome? A Review of the Potential Mechanisms

Exposure to arsenic in drinking water is a worldwide health problem. This pollutant is associated with increased risk of developing chronic diseases, including metabolic diseases. Metabolic syndrome (MS) is a complex pathology that results from the interaction between environmental and genetic factors. This condition increases the risk of developing type 2 diabetes, cardiovascular diseases, and cancer. The MS includes at least three of the following signs, central obesity, impaired fasting glucose, insulin resistance, dyslipidemias, and hypertension. Here, we summarize the existing evidence of the multiple mechanisms triggered by arsenic to developing the cardinal signs of MS, showing that this pollutant could contribute to the multifactorial origin of this pathology.

Mitochondria damage and ferroptosis involved in Ni-induced hepatotoxicity in mice

Nickel (Ni) is an environmental toxicant that can cause toxic damage to humans and animals. Although the hepatotoxicity of Ni has been confirmed, its precise mechanism is still unclear. In this study, the results showed that nickel chloride (NiCl₂)-treatment could induce mice hepatotoxicity including hepatic histopathological alterations and up-regulation of serum AST and ALT. According to the results, NiCl₂ increased malondialdehyde (MDA) production while reducing total antioxidant capacity (T-AOC) activity and glutathione (GSH) content. Additionally, NiCl₂ induced mitochondrial damage which was featured by increase in mitochondrial ROS (mt-ROS) and mitochondrial membrane potential (MMP) depolarization. The mitochondrial respiratory chain complexes I-IV and ATP content were decreased in the liver of NiCl₂-treated mice. Meanwhile, NiCl₂ caused hepatic ferroptosis accompanied by increased iron content in the liver and up-regulation of cyclooxygenase 2 (COX-2) protein and mRNA expression levels, down-regulation of glutathione eroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1) and nuclear receptor coactivator 4 (NCOA4) protein and mRNA expression levels. Altogether, the above mentioned results indicate that NiCl₂ treatment may induce hepatic damage through mitochondrial damage and ferroptosis.

Research progress on the mechanism of ferroptosis and its clinical application

Ferroptosis is a mode of cell death dependent on iron ions, which is mainly induced by the decrease of the biological activity of glutathione peroxidase or the accumulation of lipid peroxidation and reactive oxygen species (ROS). It is significantly different from autophagy and other forms of cell death in terms of cell morphology and biochemistry. The exact mechanisms of ferroptosis are not clear. More and more studies have shown that various tumor diseases and nervous system diseases are closely related to ferroptosis. The occurrence and development of related diseases can be tolerated by stimulating or inhibiting the occurrence of ferroptosis. Therefore, ferroptosis has occupied a very important position in recent years. This article reviews the discovery process, characteristics, mechanisms, inducers, inhibitors of ferroptosis and its related clinical applications to lay a foundation for follow-up researchers to study ferroptosis and provide some reference value.

Ubiquitinated gasdermin D mediates arsenic-induced pyroptosis and hepatic insulin resistance in rat liver

As an environmental toxicant, arsenic exposure may cause insulin resistance (IR). Previous studies have shown that pyroptosis plays an important role in the occurrence and development of IR. Although gasdermin D (GSDMD) functions as an executor of pyroptosis, the relationship between GSDMD-mediated pyroptosis and hepatic IR remains unclear. Here, we observed that sodium arsenite (NaAsO₂) activated NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasomes, promoted GSDMD activation, induced pyroptosis and hepatic IR, while GSDMD knockdown attenuated pyroptosis and hepatic IR caused by NaAsO₂. However, GSDMD interference did not affect NLRP3 activation. Ubiquitination modification is widely involved in protein regulation and intracellular signal transduction, and whether it regulates GSDMD and affects its degradation, and exerts effects on arsenic-induced pyroptosis remain unclear. We observed that NaAsO₂ reduced the K48- and K63-linked ubiquitination of GSDMD, thereby inhibiting its degradation through the ubiquitin-proteasome system (UPS) and the autophagy-lysosome pathway (ALP), causing GSDMD to accumulate and lyse into GSDMD-N, which promoted pyroptosis. In summary, we demonstrated that GSDMD participated in arsenic-induced hepatic IR. Moreover, NaAsO₂ reduced GSDMD ubiquitination and decreased its intracellular degradation, aggravating pyroptosis and hepatic IR. We have revealed the molecular mechanism underpinning arsenic-induced IR, and we provide potential solutions for the prevention and treatment of type 2 diabetes (T2D).

Insight into the Double-Edged Role of Ferroptosis in Disease

Ferroptosis, a newly described type of iron-dependent programmed cell death that is distinct from apoptosis, necroptosis, and other types of cell death, is involved in lipid peroxidation (LP), reactive oxygen species (ROS) production, and mitochondrial dysfunction. Accumulating evidence has highlighted vital roles for ferroptosis in multiple diseases, including acute kidney injury, cancer, hepatic fibrosis, Parkinson's disease, and Alzheimer's disease. Therefore, ferroptosis has become one of the research hotspots for disease treatment and attracted extensive attention in recent years. This review mainly summarizes the relationship between ferroptosis and various diseases classified by the system, including the urinary system, digestive system, respiratory system, nervous system. In addition, the role and molecular mechanism of multiple inhibitors and inducers for ferroptosis are further elucidated. A deeper understanding of the relationship between ferroptosis and multiple diseases may provide new strategies for researching diseases and drug development based on ferroptosis.

Zinc oxide nanosphere for hydrogen sulfide scavenging and ferroptosis of colorectal cancer

Background

Colorectal cancer is a common malignancy occurring in the digestive system and ranks second in cancer mortality worldwide. In colorectal cancer, hydrogen sulfide (H₂S) is selectively upregulated, resulting in the further exacerbation of the disease. Therefore, the clearance of H₂S and the regulation of the enzymes on the H₂S pathways are of great significance for colorectal cancer therapy.

Methods

Here, we investigated the H₂S content in various clinical tumor tissues from patients and confirmed that overproduced concentration of H₂S in colorectal cancer. Accordingly, we developed an H₂S-responsive nanoplatform based on zinc oxide coated virus-like silica nanoparticles (VZnO) for the therapy of colorectal cancer.

Results

Owing to its excellent H₂S scavenging ability, VZnO could effectively reduce H₂S content in colorectal cancer to prohibit the growth of CT26 and HCT116 colorectal cancer cells. Moreover, the removal of H₂S in colorectal cancer also leads to tumor inhibition through activating ferroptosis, a non-apoptotic form of cell death. The biosafety-related toxicological and pathological analysis confirmed the low toxicity and high safety of VZnO in colorectal cancer treatment. Furthermore, as an H₂S-responsible nanosystem, VZnO appears to have no therapeutic effect on other non H₂S rich cancers, such as the 4T1 breast cancer model.

Conclusions

We anticipate that the H₂S-depletion-induced ferroptosis strategy using zinc oxide-based nanomaterials would provide insights in designing nanomedicines for colorectal cancer-target theranostics and may offer clinical promise.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01069-y.

Radiotherapy-Induced Digestive Injury: Diagnosis, Treatment and Mechanisms

Radiotherapy is one of the main therapeutic methods for treating cancer. The digestive system consists of the gastrointestinal tract and the accessory organs of digestion (the tongue, salivary glands, pancreas, liver and gallbladder). The digestive system is easily impaired during radiotherapy, especially in thoracic and abdominal radiotherapy. In this review, we introduce the physical classification, basic pathogenesis, clinical characteristics, predictive/diagnostic factors, and possible treatment targets of radiotherapy-induced digestive injury. Radiotherapy-induced digestive injury complies with the dose-volume effect and has a radiation-based organ correlation. Computed tomography (CT), MRI (magnetic resonance imaging), ultrasound (US) and endoscopy can help diagnose and evaluate the radiation-induced lesion level. The latest treatment approaches include improvement in radiotherapy (such as shielding, hydrogel spacers and dose distribution), stem cell transplantation and drug administration. Gut microbiota modulation may become a novel approach to relieving radiogenic gastrointestinal syndrome. Finally, we summarized the possible mechanisms involved in treatment, but they remain varied. Radionuclide-labeled targeting molecules (RLTMs) are promising for more precise radiotherapy. These advances contribute to our understanding of the assessment and treatment of radiation-induced digestive injury.

Endoplasmic reticulum stress-mediated autophagy activation is involved in cadmium-induced ferroptosis of renal tubular epithelial cells

Acute cadmium (Cd) exposure is a significant risk factor for renal injury and lacks effective treatment strategies. Ferroptosis is a recently identified iron-dependent form of nonapoptotic cell death mediated by membrane damage resulting from lipid peroxidation, and it is implicated in many diseases. However, whether ferroptosis is involved in Cd-induced renal injury and, if so, how it operates. Here, we show that Cd can induce ferroptosis in kidney and renal tubular epithelial cells, as demonstrated by elevation of intracellular iron levels and lipid peroxidation, as well as impaired antioxidant production. Treatment with a ferroptosis inhibitor alleviated Cd-induced cell death. Intriguingly, we established that Cd-induced ferroptosis depended on endoplasmic reticulum (ER) stress, by demonstrating that Cd activated the PERK-eIF2α-ATF4-CHOP pathway and that inhibition of ER stress reduced ferroptosis caused by Cd. We further found that autophagy was required for Cd-induced ferroptosis because the inhibition of autophagy by chloroquine mitigated Cd-induced ferroptosis. Furthermore, we showed that iron dysregulation by ferritinophagy contributed to Cd-induced ferroptosis, by showing that the iron chelator desferrioxamine alleviated Cd-induced cell death and lipid peroxidation. In addition, ER stress is likely activated by MitoROS which trigger autophagy and ferroptosis. Collectively, our results indicate that ferroptosis is involved in Cd-induced renal toxicity and regulated by the MitoROS-ER stress-ferritinophagy axis.

Ferroptosis-related gene SOCS1, a marker for tuberculosis diagnosis and treatment, involves in macrophage polarization and facilitates bone destruction in tuberculosis

This study was aimed to reveal the role of ferroptosis in tuberculosis infection. To elucidate the ferroptosis-related DEGs, GEO datasets associated with tuberculosis infection were downloaded. The two external validation GEO datasets were exploited for subsequent verification of the ferroptosis-related DEGs. We further evaluated the correlation among the ferroptosis-related DEGs, therapeutic effects, and drug resistance. Finally, we tried to reveal the engagement of the ferroptosis-related DEGs in bone destruction during TB infection. The present study identified SOCS1 as the only ferroptosis-related DEGs. Compared to the non-TB patients, up-regulation of SOCS1 was evident in the TB patients. After receiving standard anti-TB treatment, significant down-regulation of SOCS1 confirmed its acceptance as the marker for therapeutic efficacy. The involvement of SOCS1 has also been suggested in the regulation of the micro immune environment in TB. Furthermore, SOCS1 might play an important role in causing bone destruction during TB infection. FRGs-SOCS1 may be the key gene involved in the pathogenesis and progression of TB infection.

Oxalate Activates Autophagy to Induce Ferroptosis of Renal Tubular Epithelial Cells and Participates in the Formation of Kidney Stones

Renal tubular epithelial cell damage is the basis for the formation of kidney stones. Oxalate can induce human proximal tubular (HK-2) cells to undergo autophagy and ferroptosis. The present study was aimed at investigating whether the ferroptosis of HK-2 cells induced by oxalate is caused by the excessive activation of autophagy. We treated HK-2 cells with 2 mmol/L of oxalate to establish a kidney stone model. First, we tested the degree of oxidative damage and the level of autophagy and ferroptosis in the control group and the oxalate intervention group. We then knocked down and overexpressed the BECN1 gene and knocked down the NCOA4 gene in HK-2 cells, followed by redetection of the above indicators. We confirmed that oxalate could induce autophagy and ferroptosis in HK-2 cells. Moreover, after oxalate treatment, overexpression of the BENC1 gene increased cell oxidative damage and ferroptosis. In addition, knockdown of NCOA4 reversed the effect of oxalate-induced ferroptosis in HK-2 cells. Our results show that the effects of oxalate on the ferroptosis of HK-2 cells are caused by the activation of autophagy, and knockdown of the NCOA4 could ameliorate this effect.

Toward improved human health: Nrf2 plays a critical role in regulating ferroptosis

Ferroptosis is a recently defined type of regulated cell death caused by an excess iron-dependent accumulation of lipid peroxides and is morphologically and biochemically distinct from other types of cell death. Notably, Nrf2 is identified to exquisitely modulate ferroptosis due to its ability to target a host of ferroptosis cascade genes, which places Nrf2 in the pivotal position of ferroptosis. This paper reviews the regulation effect of Nrf2 on ferroptosis, different activation mechanisms of Nrf2 as well as the relevance of the Nrf2-ferroptosis axis in diseases, and finally summarizes foods with beneficial effects in ferroptosis via the Nrf2 pathway and aims to serve as a reference for follow-up studies of food functions related to Nrf2, ferroptosis, and human health.

NLRP3 inflammasome blocked the glycolytic pathway via targeting to PKLR in arsenic-induced hepatic insulin resistance

Arsenic exposure is related to insulin resistance (IR). However, the underlying mechanism is still uncertain. NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasome is a key driving factor of IR. We found that NaAsO₂ caused hepatic IR, activated NLRP3 inflammasome, and inhibited glycolysis pathway in vivo. We also found that tricarboxylic acid cycle (TCA cycle) was inhibited, and the content of hepatic lactate was upregulated with the treatment of arsenic. Consistent with these findings, we found that NLRP3 inflammasome and glycolysis were involved in the development of IR in L-02 cells. Besides, inhibiting NLRP3 inflammasome upregulated aerobic glycolysis and inhibited anaerobic glycolysis. Moreover, we demonstrated that NLRP3 inflammasome could bind to pyruvate kinase, liver and RBC (PKLR). Simultaneously, insulin signaling rather than NLRP3 inflammasome activation was altered by overexpressing PKLR. In summary, after treatment with NaAsO₂, NLRP3 inflammasome blocked the glycolytic pathway via binding to PKLR, which in turn caused hepatic IR_. This study shed new light on the molecular mechanism underlying arsenic-induced IR.

CoCrMo-Nanoparticles induced peri-implant osteolysis by promoting osteoblast ferroptosis via regulating Nrf2-ARE signalling pathway

Objectives

Aseptic loosening (AL) is the most common reason of total hip arthroplasty (THA) failure and revision surgery. Osteolysis, caused by wear particles released from implant surfaces, has a vital role in AL. Although previous studies suggest that wear particles always lead to osteoblast programmed death in the process of AL, the specific mechanism remains incompletely understood and osteoblast ferroptosis maybe a new mechanism of AL.

Materials and Methods

CoCrMo nanoparticles (CoNPs) were prepared to investigate the influence of ferroptosis in osteoblasts and calvaria resorption animal models. Periprosthetic osteolytic bone tissue was collected from patients who underwent AL after THA to verify osteoblast ferroptosis.

Results

Our study demonstrated that CoNPs induced significant ferroptosis in osteoblasts and particles induced osteolysis (PIO) animal models. Blocking ferroptosis with specific inhibitor Ferrostatin‐1 dramatically reduced particle‐induced ferroptosis in vitro. Moreover, in osteoblasts, CoNPs significantly downregulated the expression of Nrf2 (nuclear factor erythroid 2‐related factor 2), a core element in the antioxidant response. The overexpression of Nrf2 by siKeap1 or Nrf2 activator Oltipraz obviously upregulated antioxidant response elements (AREs) and suppressed ferroptosis in osteoblasts. Furthermore, in PIO animal models, the combined utilization of Ferrostatin‐1 and Oltipraz dramatically ameliorated ferroptosis and the severity of osteolysis.

Conclusions

These results indicate that CoNPs promote osteoblast ferroptosis by regulating the Nrf2‐ARE signalling pathway, which suggests a new mechanism underlying PIO and represents a potential therapeutic approach for AL.

Arsenic and antimony co-induced nephrotoxicity via autophagy and pyroptosis through ROS-mediated pathway in vivo and in vitro

Arsenic (As) and antimony (Sb) are commonly accumulated environmental pollutants that often coexist in nature and cause serious widespread biological toxicity. To investigate the nephrotoxicity induced by As and Sb in detail, we explored the mechanism by which As and Sb cotreatment induced autophagy and pyroptosis in vivo and in vitro. In this study, mice were treated with 4 mg/kg arsenic trioxide (ATO) or/and 15 mg/kg antimony trichloride (SbCl₃) by intragastric intubation for 60 days. TCMK-1 cells were treated with ATO (12.5 μM), SbCl₃ (25 μM) or a combination of As and Sb for 24 h. The results of the in vivo experiment demonstrated that As or/and Sb exposure could induce histopathological changes in the kidneys, and increase the levels of biochemical indicators of nephrotoxicity. In addition, As and Sb can co-induce oxidative stress, which further activate autophagy and pyroptosis. In an in vitro experiment, As and/or Sb coexposure increased ROS generation and decreased MMP. Moreover, the results of related molecular experiments further confirmed that As and Sb coactivated autophagy and pyroptosis. In conclusion, our results indicated that As and Sb co-exposure could cause autophagy and pyroptosis via the ROS pathway, and these two metals might have a synergistic effect on nephrotoxicity.

Multiplexed quantitative evaluation on mitochondrial toxicity of tris (2,3-dibromopropyl) phosphate in hepatocyte

The frequent detection of (2,3-dibromopropyl) phosphate (TDBPP) in environment has led to a consistent risk to organisms. However, little is known about the toxicity of TDBPP exclusive for its carcinogen. Mitochondrion that tightly relates to adverse outcomes once deteriorated is referred as a target of environmental pollutants. Here, we investigated the role of mitochondrial abnormality in development of cellular pathobiology especially lipid deposition when response to TDBPP in mitochondria-rich hepatocyte (AML12) at the same order of magnitude as the environmental concentrations (10^-6 mol/L or below) via multiplexed quantitative high content analytic system. The present study claimed TDBPP shifted mitochondria from fusion morphology to fission phenotype charactering by less mitochondrial networks, larger mitochondrial areas and shorter branch length at 10^-7 mol/L or above. This dynamic imbalance was triggered by high levels of fis and drp1 genes when treated with TDBPP. The deformation caused by TDBPP reciprocally influenced biogenesis through PGC1α and electron transport chains via ectopic expression of genes encoding for mitochondria complex I and III subunits. Accordingly, we observed high mitoROS level and low mitochondria membrane potential. Consequently, cells contained those abnormal mitochondria were predisposed to accumulating lipids after exposure to TDBPP. Here we showed that TDBPP deteriorated mitochondrial morphology and function, which may induce lipid generation. As for a banned while still emerged contaminant, our study also claimed further exploration on the non-carcinogenic toxicity of TDBPP.

A Metabolic Profiling Study of Realgar-Induced Acute Kidney Injury in Mice

Realgar has been used as a type of mineral drug that contains arsenic for thousands of years. Previous studies have shown that Realgar-induced acute kidney injury is associated with abnormal metabolism, but the underlying mechanism is poorly understood. The aim of this study is to investigate the metabolic changes in serum and kidney tissues of mice exposed to Realgar by using a metabolomic approach and explore the molecular mechanisms of acute kidney injury induced by Realgar. Forty mice were randomly divided into four groups: Control group, 0.5-, 1.0, and 2.0 g/kg Realgar group. After 1 week, the body weight and kidney weight of the mice were measured. The serum and kidney samples were used for LC-MS spectroscopic metabolic profiling. Principal component analysis (PCA), correlation analysis, and pathway analysis were used to detect the nephrotoxic effects of Realgar. Body weight decreased significantly in the 2.0 g/kg group, and the kidney weight index also showed a dose-dependent increase in Realgar. The PCA score plot showed the serum and kidney tissue metabolic profile of mice exposed to 2.0 g/kg Realgar separated from the control group, while the lower-doses of 0.5 g/kg and 1.0 g/kg Realgar shown a similar view to the Control group. Thirty-three metabolites and seventeen metabolites were screened and identified in the serum and kidney of mice in a dose-dependent manner. respectively. Correlation analysis showed a strong correlation among these metabolites. Amino acid metabolism, lipid metabolism, glutathione metabolism, and purine metabolism pathways were found to be mainly associated with Realgar nephrotoxicity. This work illustrated the metabolic alterations in Realgar-induced nephrotoxic mice through a metabolomic approach.

Autophagy Inhibition Plays a Protective Role in Ferroptosis Induced by Alcohol via the p62-Keap1-Nrf2 Pathway

Binge alcohol consumption is a serious health concern. Ferroptosis is an iron-dependent lipid peroxidation mediated cell death. Activation of the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway has been shown to exert a protective effect by blunting the responses to ferroptosis inducers. The autophagy substrate p62 was demonstrated to modulate Nrf2 and contribute to the suppression of ferroptosis. Furthermore, autophagy inhibition resulted in the accumulation of p62, which is a specific substrate for this process. Therefore, we aimed to explore the protective effect of autophagy inhibition against alcohol-induced ferroptosis through activating the p62-Keap1-Nrf2 pathway. Our results demonstrated that alcohol induced ferroptosis, which could be significantly reduced by ferrostatin-1. Additionally, we found that autophagy inhibition could protect HepG2 cells against alcohol-induced ferroptosis by activating the p62-Keap1-Nrf2 pathway. Furthermore, inhibition of autophagy increased the expression of p62, which interacted with Keap1 to promote Nrf2 translocation into the nucleus and upregulation its target proteins ferritin heavy (FTH), ferroportin (FPN), and heme oxygenase-1 (HO-1). This study provides a theoretical basis for further elucidation of the relationship between autophagy and ferroptosis and lays a preliminary foundation for further research concerning dietary guidance in the prevention and treatment of diseases related to alcohol-induced ferroptosis.

Ferroptosis: Biological Rust of Lipid Membranes

Significance: Iron is an essential element required for growth and proper functioning of the body. However, an excess of labile ferrous iron increases the risk of oxidative stress-induced injury due to the high reactivity of the unpaired reactive electrons of both ferrous iron and oxygen. This high reactivity can be exemplified in the outside world by one of its consequences, rust formation. In cells, this redox-active iron is involved in the formation of lipid radicals. Recent Advances: Defect or insufficient membrane-protective mechanisms can result in iron-catalyzed excessive lipid peroxidation and subsequent cell death, now conceptualized as ferroptosis. Growing reports propose the detrimental role of iron and ferroptosis in many experimental disease models such as ischemia-reperfusion, acute and chronic organ injuries. Critical Issues: This review first provides a snapshot of iron metabolism, followed by a brief introduction of the molecular mechanisms of ferroptosis, as an iron-dependent lipid peroxidation-driven mode of cell death. Upon describing how iron dysbiosis affects ferroptosis induction, we elaborate on the detrimental role of the iron-ferroptosis axis in several diseases. Future Directions: Despite compelling findings suggesting a role of ferroptosis in experimental animal models, the exact contribution of ferroptosis in human contexts still needs further investigation. Development of reliable ferroptosis biomarkers will be an important step in characterizing ferroptosis in human disease. This can provide therapeutic opportunities aiming at targeting ferroptosis in human diseases. Antioxid. Redox Signal. 35, 487-509.

Exposure to Environmental Arsenic and Emerging Risk of Alzheimer's Disease: Perspective Mechanisms, Management Strategy, and Future Directions

Alzheimer’s disease (AD) is one of the most prevailing neurodegenerative diseases, characterized by memory dysfunction and the presence of hyperphosphorylated tau and amyloid β (Aβ) aggregates in multiple brain regions, including the hippocampus and cortex. The exact etiology of AD has not yet been confirmed. However, epidemiological reports suggest that populations who were exposed to environmental hazards are more likely to develop AD than those who were not. Arsenic (As) is a naturally occurring environmental risk factor abundant in the Earth’s crust, and human exposure to As predominantly occurs through drinking water. Convincing evidence suggests that As causes neurotoxicity and impairs memory and cognition, although the hypothesis and molecular mechanism of As-associated pathobiology in AD are not yet clear. However, exposure to As and its metabolites leads to various pathogenic events such as oxidative stress, inflammation, mitochondrial dysfunctions, ER stress, apoptosis, impaired protein homeostasis, and abnormal calcium signaling. Evidence has indicated that As exposure induces alterations that coincide with most of the biochemical, pathological, and clinical developments of AD. Here, we overview existing literature to gain insights into the plausible mechanisms that underlie As-induced neurotoxicity and the subsequent neurological deficits in AD. Prospective strategies for the prevention and management of arsenic exposure and neurotoxicity have also been discussed.

ATF3 inhibits arsenic-induced malignant transformation of human bronchial epithelial cells by attenuating inflammation

Arsenic is a naturally occurring metalloid strongly associated with the incidence of lung cancer. Understanding the mechanisms of arsenic-induced carcinogenesis favors the development of effective interventions to reduce the incidence and mortality of lung cancer. In this study, we investigated the role of activating transcription factor 3 (ATF3) in arsenic-induced transformation of human bronchial epithelial cells. ATF3 was upregulated during chronic exposure to 0.25 μM arsenic, and loss of ATF3 promoted arsenic-induced transformation. Moreover, arsenic-transformed ATF3 knockout (ATF3 KO-AsT) cells exhibited more aggressive characteristics, including acceleration in proliferation, resistance to chemotherapy and increase in migratory capacity. RNA-seq revealed that pathways involved in inflammation, cell cycle, EMT and oncogenesis were affected due to ATF3 deficiency during chronic arsenic exposure. Further experiments confirmed the overproduction of IL-6, IL-8 and TNFα as well as enhanced phosphorylation of AKT and STAT3 in ATF3 KO-AsT cells. Our results demonstrate that ATF3 upregulated by chronic low-dose arsenic exposure represses cell transformation and acquisition of malignant characteristics through inhibiting the production of proinflammatory cytokines and activation of downstream proteins AKT and STAT3, providing a new strategy for the prevention of carcinogen-induced lung cancer.

Autophagy-dependent ferroptosis contributes to cisplatin-induced hearing loss

Cisplatin-induced hearing loss is a common side effect of cisplatin chemotherapy, for which clinical therapy remains unavailable. Apoptosis of hair cells is considered the primary cause of cisplatin-induced ototoxicity; however, inhibiting apoptosis can only partially restore cisplatin-induced hearing loss. Therefore, auditory cell death caused by cisplatin damage requires further study. Ferroptosis, a novel form of regulated cell death, has been shown to play a role in the mechanism of cisplatin toxicity. In this study, we observed proferroptotic alterations (lipid peroxidation and impaired antioxidant capacity) in the cochleae of C57BL/6 mice after cisplatin damage, verifying the induction of ferroptosis. Using the HEI-OC1 cell line, we observed that cisplatin induced proferroptotic alterations and activated ferritinophagy (specific autophagy pathway). Employing chloroquine, we confirmed that the blockage of autophagy remarkably alleviated cisplatin-induced ferroptosis in HEI-OC1 cells; therefore, the induction of ferroptosis in cisplatin-treated auditory cells was dependent on the activation of autophagy. In addition, the ferroptosis inhibitor ferrostatin-1 and iron chelator deferoxamine significantly attenuated cisplatin-induced cytotoxicity in HEI-OC1 cells and cochlear explants. Moreover, pharmacologically inhibiting ferroptosis using ferrostatin-1 significantly decreased the auditory cell loss and, notably, attenuated hearing loss in C57BL/6 mice after cisplatin damage. Collectively, these findings indicate that autophagy-dependent ferroptosis plays an integrated role in the mechanism of cisplatin-induced hearing loss.

Arsenic or/and antimony induced mitophagy and apoptosis associated with metabolic abnormalities and oxidative stress in the liver of mice

Arsenic and antimony are coexisting cumulative environmental pollutants that cause severe and extensive biological toxicity. However, their interactions and toxic mechanisms in the liver remain to be fully elucidated. In this study, a total of sixty 4-week-old mice were divided into four groups and treated with 4 mg/kg arsenic trioxide (ATO) or/and 15 mg/kg antimony (Sb) for 60 days. The results demonstrated that biochemical indicators of hepatotoxicity (ALT, AST, ALP) were upregulated in all treated groups. Additionally, the oxidative burden of the liver was increased in the cotreated groups compared with the individual toxicant-treated groups. Meanwhile, mitochondrial injury, autophagosomes, hepatic-congestion and karyopyknosis were obviously observed in cotreated groups. Additionally, coupled with serum biochemical index (TG, TC), histopathology examination and metabolomics results, we found that cotreatment with ATO and Sb resulted in lipid metabolism disorder and steatosis of liver tissues. Our further investigation found that the levels of pro-apoptotic (Caspase-3, Caspase-9, Bax, P53, Cytc) and mitophagy (LC3-B, P62, PINK1, Parkin) indexes in the cotreated groups were markedly increased, whereas the levels of anti-apoptosis index (Bcl-2) were decreased. Collectively, these results show that co-exposure to ATO and Sb can cause abnormal liver energy metabolism and oxidative stress. Moreover, mitophagy and apoptosis play important roles in the mechanisms of arsenic/antimony cytotoxicity to mouse livers.

Ferroptosis and Its Potential Role in Metabolic Diseases: A Curse or Revitalization?

Ferroptosis is classified as an iron-dependent form of regulated cell death (RCD) attributed to the accumulation of lipid hydroperoxides and redox imbalance. In recent years, accumulating researches have suggested that ferroptosis may play a vital role in the development of diverse metabolic diseases, for example, diabetes and its complications (e.g., diabetic nephropathy, diabetic cardiomyopathy, diabetic myocardial ischemia/reperfusion injury and atherosclerosis [AS]), metabolic bone disease and adrenal injury. However, the specific physiopathological mechanism and precise therapeutic effect is still not clear. In this review, we summarized recent advances about the development of ferroptosis, focused on its potential character as the therapeutic target in metabolic diseases, and put forward our insights on this topic, largely to offer some help to forecast further directions.