Lipid Peroxidation, GSH Depletion, and SLC7A11 Inhibition Are Common Causes of EMT and Ferroptosis in A549 Cells, but Different in Specific Mechanisms

Ferritinophagy-Mediated Ferroptosis and Activation of Keap1/Nrf2/HO-1 Pathway Were Conducive to EMT Inhibition of Gastric Cancer Cells in Action of 2,2'-Di-pyridineketone Hydrazone Dithiocarbamate Butyric Acid Ester

In metastasis of cancer cells, the epithelial-mesenchymal transition (EMT) is prerequired. Ferroptosis is an iron-mediated cellular death process, but whether it involves EMT regulation remains elusive. In addition, how stress responders (Nrf2) respond to the redox alteration and cross-talking between them needs to be determined. Our data revealed that DpdtbA (2,2'-di-pyridineketone hydrazone dithiocarbamate butyric acid ester) resisted TGF-β1-induced EMT in gastric cancer lines (SGC-7901 and MGC-823) through ferritinophagy-mediated ROS production. Furthermore, the depletion of Gpx4 and xCT as well as enhanced lipid peroxidation indicated that DpdtbA acted as Erastin did in ferroptosis induction, which thus provided chance to explore the causal relationship between ferroptosis and EMT. Our data illustrated that ferritinophagy-mediated ferroptosis promoted the EMT inhibition. In addition, activated Nrf2 involved the regulation on both ferroptosis and EMT in response to the alteration in the cellular redox environment. In brief, ferritinophagy-mediated ferroptosis and activation of the Keap1/Nrf2/HO-1 pathway were conducive to the EMT inhibition.

The role of ferroptosis in acute lung injury

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a common disease with high morbidity and mortality, and its pathogenesis is believed to be related to oxidative stress, apoptosis, inflammation, and hypoxia. Ferroptosis is a type of nonapoptotic cell death characterized by iron-dependent lipid peroxide accumulation and is involved in many cellular physiological processes. Recent studies have confirmed that ferroptosis may be involved in the development of ALI. This review summarizes the most recent discoveries on the role of ferroptosis in ALI to provide new strategies for its prevention and treatment.

Hydroxysafflor yellow A and anhydrosafflor yellow B alleviate ferroptosis and parthanatos in PC12 cells injured by OGD/R

Ferroptosis and parthanatos are two types of programmed cell death associated with cerebral ischemia. There is a sizeable interest in seeking chemical components for the regulation of ferroptosis and parthanatos. Hydroxysafflor yellow A (HSYA) and anhydrosafflor yellow B (AHSYB) mitigated cell death caused by oxidative stress due to antioxidant capacity, yet the mechanism is still uncertain. Thus, we investigated whether HSYA and AHSYB prevent death through these two pathways with the aim to elucidate their potential protective mechanisms of cerebral ischemia. In this study, oxidative stress model was established by treating PC12 cells with oxygen glucose deprivation and reperfusion (OGD/R). Cellular functions and signaling pathways were analyzed in PC12 cells using cell counting kit-8 (CCK-8), flow cytometry, ELISA, iron assay kit, transmission electron microscopy (TEM), immunofluorescence, and western blot analysis. And the research proved HSYA and AHSYB protected cells from oxidative stress. The phenomenon is associated with ferroptosis and parthanatos. HSYA and AHSYB upregulated cystine/glutamate antiporter system x_c^- (system x_c^-) and glutathione peroxidase 4 (GPX4), returned the levels of GSH/GSSG ratio, reactive oxygen species (ROS) and iron ion, as well as alleviated lipid peroxidation. By reason of reducing ROS, HSYA and AHSYB restrained poly(ADP-ribose) polymerase-1 (PARP-1) overactivation, reduced the production of excess poly(ADP-ribose) (PAR) polymer and apoptosis inducing factor (AIF) nuclear translocation. The results suggested that HSYA and AHSYB limited ferroptosis and parthanatos to alleviate oxidative stress in PC12 cells. These findings may have implications for improving understanding of how drugs reduce oxidative stress and develop new strategies for treating degenerative diseases such as cerebral ischemia.

Single-Cell RNA-Seq Reveals the Promoting Role of Ferroptosis Tendency During Lung Adenocarcinoma EMT Progression

Epithelial-mesenchymal transition (EMT) and ferroptosis are two important processes in biology. In tumor cells, they are intimately linked. We used single-cell RNA sequencing to investigate the regulatory connection between EMT and ferroptosis tendency in LUAD epithelial cells. We used Seurat to construct the expression matrix using the GEO dataset GSE131907 and extract epithelial cells. We found a positive correlation between the trends of EMT and ferroptosis tendency. Then we used SCENIC to analyze differentially activated transcription factors and constructed a molecular regulatory directed network by causal inference. Some ferroptosis markers (GPX4, SCP2, CAV1) were found to have strong regulatory effects on EMT. Cell communication networks were constructed by iTALK and implied that Ferro_High_EMT_High cells have a higher expression of SDC1, SDC4, and activation of LGALS9-HARVCR2 pathways. By deconvolution of bulk sequencing, the results of CIBERSORTx showed that the co-occurrence of ferroptosis tendency and EMT may lead to tumor metastasis and non-response to immunotherapy. Our findings showed there is a strong correlation between ferroptosis tendency and EMT. Ferroptosis may have a promotive effect on EMT. High propensities of ferroptosis and EMT may lead to poor prognosis and non-response to immunotherapy.

Histone methyltransferase SETDB1 inhibits TGF-β-induced epithelial-mesenchymal transition in pulmonary fibrosis by regulating SNAI1 expression and the ferroptosis signaling pathway

The epithelial-mesenchymal transition (EMT) is an important pathological process in the occurrence of pulmonary fibrosis. Changes in histone methylation modifications of key genes play an important role in this process. As a histone methyltransferase, the regulatory mechanism and role of SET domain bifurcated 1 (SETDB1) in pulmonary fibrosis remain unclear. We found that SETDB1 inhibited EMT and that cells attenuated the expression of SETDB1 to relieve this inhibition during transforming growth factor-β (TGF-β)-induced EMT. Silencing SETDB1 expression significantly enhanced the mesenchymal phenotype induced by TGF-β and the expression and deposition of fibronectin and significantly reduced the expression of E-cadherin. The decrease in E-cadherin expression and the induction of EMT led to increased lipid reactive oxygen species (ROS) and ferrous ions, which induced ferroptosis. Chromatin immunoprecipitation (ChIP) results showed that SETDB1 regulates the expression of Snai1 by catalyzing the histone H3 lysine 9 trimethylation (H3K9me3) of Snai1, the main transcription factor that initiates the process of EMT, and thus, indirectly regulates E-cadherin. Surprisingly, when examining the effect of overexpressed SETDB1 on EMT, we found that overexpressed SETDB1 alleviated EMT and also caused ferroptosis. We suggest that the overexpression of SETDB1 partially reverses the mesenchymal phenotype to an epithelial state, while those cells that fail to reverse are depleted by ferroptosis. In conclusion, the histone methylase SETDB1 regulates Snai1 epigenetically, driving EMT gene reprogramming and ferroptosis in response to TGF-β. However, there are unexplored links between the epigenetic reprogramming and transcriptional processes that regulate EMT in a TGF-β-dependent manner.

Ferritinophagic Flux Was a Driving Force in Determination of Status of EMT, Ferroptosis, and NDRG1 Activation in Action of Mechanism of 2-Pyridylhydrazone Dithiocarbamate S-Acetic Acid

Ferritinophagy is a process of ferritin degradation in lysosomes; however, how its effect on other cellular events, such as epithelial-mesenchymal transition (EMT) and ferroptosis remains elusive. In this study, we determined how ferritinophagic flux influence the status of EMT and ferroptosis in HepG2 cell. Our data revealed that 2-pyridylhydrazone dithiocarbamate s-acetic acid (PdtaA) induced EMT inhibition involved ferritinophagy-mediated ROS production, but addition of ferrostatin-1 could attenuate the effect of PdtaA on the regulation of EMT-related proteins, suggesting that ferroptosis might involve in the EMT regulation. Next, downregulation of Gpx4 and xCT as well as enhanced lipid peroxidation further supported that PdtaA was able to induce ferroptosis. Knockdown of NCOA4 significantly attenuated the regulatory effect of PdtaA on related proteins which highlighted that the strength of ferritinophagic flux (NCOA4/ferritin) was a driving force in determination of the status of EMT and ferroptosis. Furthermore, NDRG1 activation was also observed, and knockdown of NDRG1 similarly influenced the expressions of ferroptosis-related proteins, suggesting that NDRG1 also involved ferroptosis induction, which was first reported. Taken together, PdtaA-induced EMT inhibition, ferroptosis, and NDRG1 activation all depended on the strength of ferritinophagic flux.

Prevention of ferroptosis in acute scenarios: an in vitro study with classic and novel anti-ferroptotic compounds

Ferroptosis, an iron-dependent form of cell death, has critical roles in diverse pathologies. Data on the temporal events mediating the prevention of ferroptosis are lacking. Focused on temporal aspects of cytotoxicity/protection, we investigated the effects of classic (Fer-1) and novel [2,6-di-tert-butyl-4-(2-thienylthio)phenol (C1) and 2,6-di-tert-butyl-4-(2-thienylselano)phenol (C2)] anti-ferroptotic agents against RSL3-, BSO- or glutamate-induced ferroptosis in cultured HT22 neuronal cell line, comparing their effects with those of the antioxidants trolox, ebselen and probucol. Glutamate (5 mM), BSO (25 μM) and RSL3 (50 nM) decreased approximately 40% of cell viability at 24 h. At these concentrations, none of these agents changed cell viability at 6 h after treatments; RSL3 increased lipoperoxidation from 6 h, although BSO and glutamate only did so at 12 h after treatments. At similar conditions, BSO and glutamate (but not RSL3) decreased GSH levels at 6 h after treatments. Fer-1, C1 and C2 exhibited similar protective effects against glutamate-, BSO- and RSL3-cytotoxicity, but this protection was limited when the protective agents were delivered to cells at time-points characterized by increased lipoperoxidation (but not glutathione depletion). Compared to Fer-1, C1 and C2, the anti-ferroptotic effects of trolox, ebselen and probucol were minor. Cytoprotective effects were not associated with direct antioxidant efficacies. These results indicate that the temporal window is central in affecting the efficacies of anti-ferroptotic drugs in acute scenarios; ferroptosis prevention is improbable when significant rates of lipoperoxidation were already achieved. C1 and C2 displayed remarkable cytoprotective effects, representing a promising new class of compounds to treat ferroptosis-related pathologies.

Treatment of early brain injury after subarachnoid hemorrhage in the rat model by inhibiting p53-induced ferroptosis

Post-subarachnoid hemorrhage (SAH) survivors experience severe neurological disability. Previous studies implicate that ferroptosis is involved in SAH. Ferroptosis is an iron-dependent form of regulated cell death caused by the accumulation of lipid peroxidation. However, the role and the mechanism of ferroptosis in SAH are still uncertain and need further study. Thus, we investigated the effect of ferroptosis on early brain injury (EBI) after SAH and further clarified its mechanism. The results showed ferroptosis characteristics appeared in the cerebral cortex of rats with SAH after 24 h. However, ferroptosis could be rescued by Ferrostatin-1 (Fer-1). Treatment with Fer-1 could increase SLc7a11 and GPx4, and alleviated damage-associated molecular pattern molecules and inflammatory cytokines. Similarly, blood-brain barrier impairment, brain edema, behavioral deficits and neuronal damage were reduced by inhibiting ferroptosis. More importantly, the p53 inhibitor pifithrin-α could significantly block cortical SAH-induced ferroptosis. Collectively, these results indicated that ferroptosis aggravated EBI after SAH was partly dependent on p53, and inhibiting ferroptosis might be an effective therapeutic target for EBI.

Role of Ferroptosis in Lung Diseases

Ferroptosis is a new type of programmed cell death characterized by intracellular iron accumulation and lipid peroxidation that leads to oxidative stress and cell death. The metabolism of iron, lipids, and amino acids and multiple signalling pathways precisely regulate the process of ferroptosis. Emerging evidence has demonstrated that ferroptosis participates in the occurrence and progression of various pathological conditions and diseases, such as infections, neurodegeneration, tissue ischaemia-reperfusion injury and immune diseases. Recent studies have also indicated that ferroptosis plays a critical role in the pathogenesis of acute lung injury, chronic obstructive pulmonary disease, pulmonary fibrosis, pulmonary infection and asthma. Herein, we summarize the latest knowledge on the regulatory mechanism of ferroptosis and its association with iron, lipid and amino acid metabolism as well as several signalling pathways. Furthermore, we review the contribution of ferroptosis to the pathogenesis of lung diseases and discuss ferroptosis as a novel therapeutic target for various lung diseases.

The Cross-Link between Ferroptosis and Kidney Diseases

Acute and chronic kidney injuries result from structural dysfunction and metabolic disorders of the kidney in various etiologies, which significantly affect human survival and social wealth. Nephropathies are often accompanied by various forms of cell death and complex microenvironments. In recent decades, the study of kidney diseases and the traditional forms of cell death have improved. Nontraditional forms of cell death, represented by ferroptosis and necroptosis, have been discovered in the field of kidney diseases, which have reshuffled the role of traditional cell death in nephropathies. Although interactions between ferroptosis and acute kidney injury (AKI) have been continuously explored, studies on ferroptosis and chronic kidney disease (CKD) remain limited. Here, we have reviewed the therapeutic significance of ferroptosis in AKI and anticipated the curative potential of ferroptosis for CKD in the hope of providing insights into ferroptosis and CKD.