mTORC1 and ferroptosis: Regulatory mechanisms and therapeutic potential

Nitidine chloride inhibits mTORC1 signaling through ATF4-mediated Sestrin2 induction and targets IGF2R for lysosomal degradation

AIMS

Nitidine chloride (NC), a natural phytochemical alkaloid derived from Zanthoxylum nitidum (Roxb.) DC, exhibits multiple bioactivities, including antitumor, anti-inflammatory, and other therapeutic effects. However, the primary targets of NC and the mechanism of action (MOA) have not been explicitly defined.

METHODS

We explored the effects of NC on mTORC1 signaling by immunoblotting and fluorescence microscopy in wild-type and gene knockout cell lines generated by the CRISPR/Cas9 gene editing technique. We identified IGF2R as a direct target of NC via the drug affinity-responsive target stability (DARTS) method. We investigated the antitumor effects of NC using a mouse melanoma B16 tumor xenograft model.

KEY FINDINGS

NC inhibits mTORC1 activity by targeting amino acid-sensing signaling through activating transcription factor 4 (ATF4)-mediated Sestrin2 induction. NC directly binds to IGF2R and promotes its lysosomal degradation. Moreover, NC displayed potent cytotoxicity against various cancer cells and inhibited B16 tumor xenografts.

SIGNIFICANCE

NC inhibits mTORC1 signaling through nutrient sensing and directly targets IGF2R for lysosomal degradation, providing mechanistic insights into the MOA of NC.

Long non-coding RNA KB-1460A1.5 promotes ferroptosis by inhibiting mTOR/SREBP-1/SCD1-mediated polyunsaturated fatty acid desaturation in glioma

Ferroptosis is a new form of regulated cell death caused by the iron-dependent peroxidation of phospholipids and is related to cell metabolism, redox homeostasis and various signalling pathways related to cancer. The long non-coding RNA (lncRNA) KB-1460A1.5 acts as a tumour suppressor gene to regulate tumour growth in gliomas, but its molecular network regulatory mechanism is still unclear. In this study, we found that KB-1460A1.5 can induce ferroptosis in glioma and enhance sensitivity to RSL3, a ferroptosis inducer. Tandem mass tag proteomics and nontargeted metabolomics suggest that KB-1460A1.5 affects polyunsaturated fatty acid metabolic processes. Gas chromatography-mass spectrometry-based medium- and long-chain fatty acid-targeted metabolomics confirmed that upregulation of KB-1460A1.5 decreased the levels of monounsaturated fatty acids, oleic acid (OA) and palmitoleic acid (PO) in glioma cells. The addition of OA and PO restored KB-1460A1.5-induced cellular ferroptosis. Molecularly, KB-1460A1.5 inhibited the mammalian target of rapamycin signalling pathway to suppress the expression of downstream sterol regulatory element-binding protein 1 (SREBP-1), thereby attenuating the stearoyl-CoA desaturase-1 (SCD1)-mediated desaturation of polyunsaturated fatty acids. Finally, an animal model of subcutaneous glioma confirmed that KB-1460A1.5 could inhibit tumour progression, SREBP-1/SCD1 expression and ferroptosis. In conclusion, increasing the expression level of KB-1460A1.5 in glioma can promote the induction of oxidative stress and ferroptosis in cancer cells through SREBP-1/SCD1-mediated adipogenesis, demonstrating therapeutic potential in preclinical models.

Mechanism of targeting the mTOR pathway to regulate ferroptosis in NSCLC with different EGFR mutations

Patients with non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR)-activating mutations can be treated with EGFR-tyrosine kinase inhibitors (TKIs). Although EGFR-TKI-targeted drugs bring survival promotion in patients with EGFR mutations, drug resistance is inevitable, so it is urgent to explore new treatments to overcome drug resistance. In addition, wild-type EGFR lacks targeted drugs, and new targeted therapies need to be explored. Ferroptosis is a key research direction for overcoming drug resistance. However, the role and mechanism of regulating ferroptosis in different EGFR-mutant NSCLC types remains unclear. In the present study, H1975 (EGFR T790M/L858R mutant), A549 (EGFR wild-type) and H3255 (EGFR L858R mutant) NSCLC cell lines were used. The expression of ferroptosis markers in these cell lines was detected using western blotting and reverse transcription-quantitative PCR. Cell viability was determined using the MTT assay and reactive oxygen species (ROS) levels were measured using flow cytometry. The results showed that, compared with EGFR wild-type/sensitive mutant cells, EGFR-resistant mutant cells were more sensitive to the ferroptosis inducer, erastin. Furthermore, the mammalian target of rapamycin (mTOR) inhibitor, everolimus (RAD001), induced cell death in all three cell lines in a dose-dependent manner. The ferroptosis inhibitor, ferrostatin-1, could reverse cell death in EGFR-resistant mutant and EGFR wild-type cells induced by RAD001, but could not reverse cell death in EGFR-sensitive mutant cells. Compared with EGFR wild-type/sensitive mutant cells, EGFR-resistant mutant cells were more sensitive to RAD001 combined with erastin. In addition, a high-dose of RAD001 reduced the expression levels of ferritin heavy-chain polypeptide 1 (FTH1), glutathione peroxidase 4 (GPX4) and ferroportin and significantly increased ROS and malondialdehyde (MDA) levels in EGFR-resistant mutant and EGFR wild-type cells. In the present study, GPX4 inhibitor only or combined with RAD001 inhibited the AKT/mTOR pathway in EGFR-resistant mutant cells. Therefore, the results of the present study suggested that inhibition of the mTOR pathway may downregulate the expression of ferroptosis-related proteins in EGFR-resistant and EGFR wild-type NSCLC cells, increase the ROS and MDA levels and ultimately induce ferroptosis.

International consensus guidelines for the definition, detection, and interpretation of autophagy-dependent ferroptosis

Macroautophagy/autophagy is a complex degradation process with a dual role in cell death that is influenced by the cell types that are involved and the stressors they are exposed to. Ferroptosis is an iron-dependent oxidative form of cell death characterized by unrestricted lipid peroxidation in the context of heterogeneous and plastic mechanisms. Recent studies have shed light on the involvement of specific types of autophagy (e.g. ferritinophagy, lipophagy, and clockophagy) in initiating or executing ferroptotic cell death through the selective degradation of anti-injury proteins or organelles. Conversely, other forms of selective autophagy (e.g. reticulophagy and lysophagy) enhance the cellular defense against ferroptotic damage. Dysregulated autophagy-dependent ferroptosis has implications for a diverse range of pathological conditions. This review aims to present an updated definition of autophagy-dependent ferroptosis, discuss influential substrates and receptors, outline experimental methods, and propose guidelines for interpreting the results.Abbreviation: 3-MA:3-methyladenine; 4HNE: 4-hydroxynonenal; ACD: accidentalcell death; ADF: autophagy-dependentferroptosis; ARE: antioxidant response element; BH2:dihydrobiopterin; BH4: tetrahydrobiopterin; BMDMs: bonemarrow-derived macrophages; CMA: chaperone-mediated autophagy; CQ:chloroquine; DAMPs: danger/damage-associated molecular patterns; EMT,epithelial-mesenchymal transition; EPR: electronparamagnetic resonance; ER, endoplasmic reticulum; FRET: Försterresonance energy transfer; GFP: green fluorescent protein;GSH: glutathione;IF: immunofluorescence; IHC: immunohistochemistry; IOP, intraocularpressure; IRI: ischemia-reperfusion injury; LAA: linoleamide alkyne;MDA: malondialdehyde; PGSK: Phen Green™ SK;RCD: regulatedcell death; PUFAs: polyunsaturated fatty acids; RFP: red fluorescentprotein;ROS: reactive oxygen species; TBA: thiobarbituricacid; TBARS: thiobarbituric acid reactive substances; TEM:transmission electron microscopy.

Augmented ERO1α upon mTORC1 activation induces ferroptosis resistance and tumor progression via upregulation of SLC7A11

BACKGROUND

The dysregulated mechanistic target of rapamycin complex 1 (mTORC1) signaling plays a critical role in ferroptosis resistance and tumorigenesis. However, the precise underlying mechanisms still need to be fully understood.

METHODS

Endoplasmic reticulum oxidoreductase 1 alpha (ERO1α) expression in mTORC1-activated mouse embryonic fibroblasts, cancer cells, and laryngeal squamous cell carcinoma (LSCC) clinical samples was examined by quantitative real-time PCR (qRT-PCR), western blotting, immunofluorescence (IF), and immunohistochemistry. Extensive in vitro and in vivo experiments were carried out to determine the role of ERO1α and its downstream target, member 11 of the solute carrier family 7 (SLC7A11), in mTORC1-mediated cell proliferation, angiogenesis, ferroptosis resistance, and tumor growth. The regulatory mechanism of ERO1α on SLC7A11 was investigated via RNA-sequencing, a cytokine array, an enzyme-linked immunosorbent assay, qRT-PCR, western blotting, IF, a luciferase reporter assay, and a chromatin immunoprecipitation assay. The combined therapeutic effect of ERO1α inhibition and the ferroptosis inducer imidazole ketone erastin (IKE) on mTORC1-activated cells was evaluated using cell line-derived xenografts, LSCC organoids, and LSCC patient-derived xenograft models.

RESULTS

ERO1α is a functional downstream target of mTORC1. Elevated ERO1α induced ferroptosis resistance and exerted pro-oncogenic roles in mTORC1-activated cells via upregulation of SLC7A11. Mechanically, ERO1α stimulated the transcription of SLC7A11 by activating the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) pathway. Moreover, ERO1α inhibition combined with treatment using the ferroptosis inducer IKE exhibited synergistic antitumor effects on mTORC1-activated tumors.

CONCLUSIONS

The ERO1α/IL-6/STAT3/SLC7A11 pathway is crucial for mTORC1-mediated ferroptosis resistance and tumor growth, and combining ERO1α inhibition with ferroptosis inducers is a novel and effective treatment for mTORC1-related tumors.

Emerging mechanisms of ferroptosis and its implications in lung cancer

ABSTRACT

Lung cancer is one of the most common malignancies and has the highest number of deaths among all cancers. Despite continuous advances in medical strategies, the overall survival of lung cancer patients is still low, probably due to disease progression or drug resistance. Ferroptosis is an iron-dependent form of regulated cell death triggered by the lethal accumulation of lipid peroxides, and its dysregulation is implicated in cancer development. Preclinical evidence has shown that targeting the ferroptosis pathway could be a potential strategy for improving lung cancer treatment outcomes. In this review, we summarize the underlying mechanisms and regulatory networks of ferroptosis in lung cancer and highlight ferroptosis-targeting preclinical attempts to provide new insights for lung cancer treatment.

Regulation of ferroptosis by PI3K/Akt signaling pathway: a promising therapeutic axis in cancer

The global challenge posed by cancer, marked by rising incidence and mortality rates, underscores the urgency for innovative therapeutic approaches. The PI3K/Akt signaling pathway, frequently amplified in various cancers, is central in regulating essential cellular processes. Its dysregulation, often stemming from genetic mutations, significantly contributes to cancer initiation, progression, and resistance to therapy. Concurrently, ferroptosis, a recently discovered form of regulated cell death characterized by iron-dependent processes and lipid reactive oxygen species buildup, holds implications for diseases, including cancer. Exploring the interplay between the dysregulated PI3K/Akt pathway and ferroptosis unveils potential insights into the molecular mechanisms driving or inhibiting ferroptotic processes in cancer cells. Evidence suggests that inhibiting the PI3K/Akt pathway may sensitize cancer cells to ferroptosis induction, offering a promising strategy to overcome drug resistance. This review aims to provide a comprehensive exploration of this interplay, shedding light on the potential for disrupting the PI3K/Akt pathway to enhance ferroptosis as an alternative route for inducing cell death and improving cancer treatment outcomes.

Ferroptosis in cancer: From molecular mechanisms to therapeutic strategies

Ferroptosis is a non-apoptotic form of regulated cell death characterized by the lethal accumulation of iron-dependent membrane-localized lipid peroxides. It acts as an innate tumor suppressor mechanism and participates in the biological processes of tumors. Intriguingly, mesenchymal and dedifferentiated cancer cells, which are usually resistant to apoptosis and traditional therapies, are exquisitely vulnerable to ferroptosis, further underscoring its potential as a treatment approach for cancers, especially for refractory cancers. However, the impact of ferroptosis on cancer extends beyond its direct cytotoxic effect on tumor cells. Ferroptosis induction not only inhibits cancer but also promotes cancer development due to its potential negative impact on anticancer immunity. Thus, a comprehensive understanding of the role of ferroptosis in cancer is crucial for the successful translation of ferroptosis therapy from the laboratory to clinical applications. In this review, we provide an overview of the recent advancements in understanding ferroptosis in cancer, covering molecular mechanisms, biological functions, regulatory pathways, and interactions with the tumor microenvironment. We also summarize the potential applications of ferroptosis induction in immunotherapy, radiotherapy, and systemic therapy, as well as ferroptosis inhibition for cancer treatment in various conditions. We finally discuss ferroptosis markers, the current challenges and future directions of ferroptosis in the treatment of cancer.

Exploring KRAS-mutant pancreatic ductal adenocarcinoma: a model validation study

Introduction

Pancreatic ductal adenocarcinoma (PDAC) has the highest mortality rate among all solid tumors. Tumorigenesis is promoted by the oncogene KRAS, and KRAS mutations are prevalent in patients with PDAC. Therefore, a comprehensive understanding of the interactions between KRAS mutations and PDAC may expediate the development of therapeutic strategies for reversing the progression of malignant tumors. Our study aims at establishing and validating a prediction model of KRAS mutations in patients with PDAC based on survival analysis and mRNA expression.

Methods

A total of 184 and 412 patients with PDAC from The Cancer Genome Atlas (TCGA) database and the International Cancer Genome Consortium (ICGC), respectively, were included in the study.

Results

After tumor mutation profile and copy number variation (CNV) analyses, we established and validated a prediction model of KRAS mutations, based on survival analysis and mRNA expression, that contained seven genes: CSTF2, FAF2, KIF20B, AKR1A1, APOM, KRT6C, and CD70. We confirmed that the model has a good predictive ability for the prognosis of overall survival (OS) in patients with KRAS-mutated PDAC. Then, we analyzed differential biological pathways, especially the ferroptosis pathway, through principal component analysis, pathway enrichment analysis, Gene Ontology (GO) enrichment analysis, and gene set enrichment analysis (GSEA), with which patients were classified into low- or high-risk groups. Pathway enrichment results revealed enrichment in the cytokine-cytokine receptor interaction, metabolism of xenobiotics by cytochrome P450, and viral protein interaction with cytokine and cytokine receptor pathways. Most of the enriched pathways are metabolic pathways predominantly enriched by downregulated genes, suggesting numerous downregulated metabolic pathways in the high-risk group. Subsequent tumor immune infiltration analysis indicated that neutrophil infiltration, resting CD4 memory T cells, and resting natural killer (NK) cells correlated with the risk score. After verifying that the seven gene expression levels in different KRAS-mutated pancreatic cancer cell lines were similar to that in the model, we screened potential drugs related to the risk score.

Discussion

This study established, analyzed, and validated a model for predicting the prognosis of PDAC based on risk stratification according to KRAS mutations, and identified differential pathways and highly effective drugs.

Identification of ferroptosis-related proteins in ameloblastoma based on proteomics analysis

PURPOSE

We used proteomic sequencing and experimental verification to identify the potential ferroptosis-related proteins in ameloblastoma.

METHODS

Samples of ameloblastoma (n = 14) and normal gingival tissues (n = 5) were collected for proteomic sequencing to identify differentially expressed proteins (DEPs) in ameloblastoma. Ferroptosis-related genes were downloaded from FerrDb V2, which were then compared with DEPs to obtain ferroptosis-related DEPs (FR-DEPs). A functional enrichment analysis was performed, and a protein-protein interaction network was built. The hub proteins were screened using the Cytoscape software, and potential drugs targeting them were retrieved from the DrugBank database. A hub protein was selected for immunohistochemical validation, and its expression was assessed in ameloblastomas, odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. The primary ameloblastoma cells were cultured to explore the effect of the protein on the migratory properties of the tumour cells.

RESULTS

A total of 58 FR-DEPs were screened, and six hub proteins were identified: mTOR, NFE2L2, PRKCA, STAT3, EGFR, and CDH1. Immunohistochemical analysis showed that mTOR expression was upregulated in ameloblastomas compared with that in odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. p-mTOR was highly expressed in ameloblastomas, with a positivity rate of 83.3%. In addition, rapamycin, an inhibitor of mTOR, can inhibit the migratory capacity of primary cultured ameloblastoma cells.

CONCLUSION

Our results revealed the ferroptosis-related proteins in ameloblastomas and their underlying biological processes. Additionally, mTOR was overexpressed and was found to be associated with the aggressiveness of ameloblastomas, which may be a potential target for future treatments.

Mechanisms of ferroptosis and targeted therapeutic approaches in lymphoma

Lymphoma is the sixth most common type of cancer worldwide. Under the current treatment standards, patients with lymphoma often fail to respond to treatment or relapse early and require further therapy. Hence, novel therapeutic strategies need to be explored and our understanding of the molecular underpinnings of lymphomas should be expanded. Ferroptosis, a non-apoptotic regulated cell death, is characterized by increased reactive oxygen species and lipid peroxidation due to metabolic dysfunction. Excessive or lack of ferroptosis has been implicated in tumor development. Current preclinical evidences suggest that ferroptosis participates in tumorigenesis, progression, and drug resistance of lymphoma, identifying a potential biomarker and an attractive molecular target. Our review summarizes the core mechanisms and regulatory networks of ferroptosis and discusses existing evidences of ferroptosis induction for the treatment of lymphoma, with intent to provide a framework for understanding the role of ferroptosis in lymphomagenesis and a new perspective of lymphoma treatment.

mTOR inhibition suppresses salinomycin-induced ferroptosis in breast cancer stem cells by ironing out mitochondrial dysfunctions

Ferroptosis constitutes a promising therapeutic strategy against cancer by efficiently targeting the highly tumorigenic and treatment-resistant cancer stem cells (CSCs). We previously showed that the lysosomal iron-targeting drug Salinomycin (Sal) was able to eliminate CSCs by triggering ferroptosis. Here, in a well-established breast CSCs model (human mammary epithelial HMLER CD24low/CD44high), we identified that pharmacological inhibition of the mechanistic target of rapamycin (mTOR), suppresses Sal-induced ferroptosis. Mechanistically, mTOR inhibition modulates iron cellular flux and thereby limits iron-mediated oxidative stress. Furthermore, integration of multi-omics data identified mitochondria as a key target of Sal action, leading to profound functional and structural alteration prevented by mTOR inhibition. On top of that, we found that Sal-induced metabolic plasticity is mainly dependent on the mTOR pathway. Overall, our findings provide experimental evidence for the mechanisms of mTOR as a crucial effector of Sal-induced ferroptosis pointing not only that metabolic reprogramming regulates ferroptosis, but also providing proof-of-concept that careful evaluation of such combination therapy (here mTOR and ferroptosis co-targeting) is required in the development of an effective treatment.

Synergistic Renoprotective Effect of Melatonin and Zileuton by Inhibition of Ferroptosis via the AKT/mTOR/NRF2 Signaling in Kidney Injury and Fibrosis

According to recent evidence, ferroptosis is a major cell death mechanism in the pathogenesis of kidney injury and fibrosis. Despite the renoprotective effects of classical ferroptosis inhibitors, therapeutic approaches targeting kidney ferroptosis remain limited. In this study, we assessed the renoprotective effects of melatonin and zileuton as a novel therapeutic strategy against ferroptosis-mediated kidney injury and fibrosis. First, we identified RSL3-induced ferroptosis in renal tubular epithelial HK-2 and HKC-8 cells. Lipid peroxidation and cell death induced by RSL3 were synergistically mitigated by the combination of melatonin and zileuton. Combination treatment significantly downregulated the expression of ferroptosis-associated proteins, 4-HNE and HO-1, and upregulated the expression of GPX4. The expression levels of p-AKT and p-mTOR also increased, in addition to that of NRF2 in renal tubular epithelial cells. When melatonin (20 mg/kg) and zileuton (20 mg/kg) were administered to a unilateral ureteral obstruction (UUO) mouse model, the combination significantly reduced tubular injury and fibrosis by decreasing the expression of profibrotic markers, such as α-SMA and fibronectin. More importantly, the combination ameliorated the increase in 4-HNE levels and decreased GPX4 expression in UUO mice. Overall, the combination of melatonin and zileuton was found to effectively ameliorate ferroptosis-related kidney injury by upregulating the AKT/mTOR/ NRF2 signaling pathway, suggesting a promising therapeutic strategy for protection against ferroptosis-mediated kidney injury and fibrosis.

Harnessing Ferroptosis to Overcome Drug Resistance in Colorectal Cancer: Promising Therapeutic Approaches

Drug resistance remains a significant challenge in the treatment of colorectal cancer (CRC). In recent years, the emerging field of ferroptosis, a unique form of regulated cell death characterized by iron-dependent lipid peroxidation, has offered new insights and potential therapeutic strategies for overcoming drug resistance in CRC. This review examines the role of ferroptosis in CRC and its impact on drug resistance. It highlights the distinctive features and advantages of ferroptosis compared to other cell death pathways, such as apoptosis and necrosis. Furthermore, the review discusses current research advances in the field, including novel treatment approaches that target ferroptosis. These approaches involve the use of ferroptosis inducers, interventions in iron metabolism and lipid peroxidation, and combination therapies to enhance the efficacy of ferroptosis. The review also explores the potential of immunotherapy in modulating ferroptosis as a therapeutic strategy. Additionally, it evaluates the strengths and limitations of targeting ferroptosis, such as its selectivity, low side effects, and potential to overcome resistance, as well as challenges related to treatment specificity and drug development. Looking to the future, this review discusses the prospects of ferroptosis-based therapies in CRC, emphasizing the importance of further research to elucidate the interaction between ferroptosis and drug resistance. It proposes future directions for more effective treatment strategies, including the development of new therapeutic approaches, combination therapies, and integration with emerging fields such as precision medicine. In conclusion, harnessing ferroptosis represents a promising avenue for overcoming drug resistance in CRC. Continued research efforts in this field are crucial for optimizing therapeutic outcomes and providing hope for CRC patients.

Autophagy mediates an amplification loop during ferroptosis

Ferroptosis, a programmed cell death, has been identified and associated with cancer and various other diseases. Ferroptosis is defined as a reactive oxygen species (ROS)-dependent cell death related to iron accumulation and lipid peroxidation, which is different from apoptosis, necrosis, autophagy, and other forms of cell death. However, accumulating evidence has revealed a link between autophagy and ferroptosis at the molecular level and has suggested that autophagy is involved in regulating the accumulation of iron-dependent lipid peroxidation and ROS during ferroptosis. Understanding the roles and pathophysiological processes of autophagy during ferroptosis may provide effective strategies for the treatment of ferroptosis-related diseases. In this review, we summarize the current knowledge regarding the regulatory mechanisms underlying ferroptosis, including iron and lipid metabolism, and its association with the autophagy pathway. In addition, we discuss the contribution of autophagy to ferroptosis and elucidate the role of autophagy as a ferroptosis enhancer during ROS-dependent ferroptosis.

mTOR in programmed cell death and its therapeutic implications

Mechanistic target of rapamycin (mTOR), a highly conserved serine/threonine kinase, is involved in cellular metabolism, protein synthesis, and cell death. Programmed cell death (PCD) assists in eliminating aging, damaged, or neoplastic cells, and is indispensable for sustaining normal growth, fighting pathogenic microorganisms, and maintaining body homeostasis. mTOR has crucial functions in the intricate signaling pathway network of multiple forms of PCD. mTOR can inhibit autophagy, which is part of PCD regulation. Cell survival is affected by mTOR through autophagy to control reactive oxygen species production and the degradation of pertinent proteins. Additionally, mTOR can regulate PCD in an autophagy-independent manner by affecting the expression levels of related genes and phosphorylating proteins. Therefore, mTOR acts through both autophagy-dependent and -independent pathways to regulate PCD. It is conceivable that mTOR exerts bidirectional regulation of PCD, such as ferroptosis, according to the complexity of signaling pathway networks, but the underlying mechanisms have not been fully explained. This review summarizes the recent advances in understanding mTOR-mediated regulatory mechanisms in PCD. Rigorous investigations into PCD-related signaling pathways have provided prospective therapeutic targets that may be clinically beneficial for treating various diseases.

AKT activation because of PTEN loss upregulates xCT via GSK3β/NRF2, leading to inhibition of ferroptosis in PTEN-mutant tumor cells

Here, we show that the tumor suppressor phosphatase and tensin homolog deleted from chromosome 10 (PTEN) sensitizes cells to ferroptosis, an iron-dependent form of cell death, by restraining the expression and activity of the cystine/glutamate antiporter system Xc- (xCT). Loss of PTEN activates AKT kinase to inhibit GSK3β, increasing NF-E2 p45-related factor 2 (NRF2) along with transcription of one of its known target genes encoding xCT. Elevated xCT in Pten-null mouse embryonic fibroblasts increases the flux of cystine transport and synthesis of glutathione, which enhances the steady-state levels of these metabolites. A pan-cancer analysis finds that loss of PTEN shows evidence of increased xCT, and PTEN-mutant cells are resistant to ferroptosis as a consequence of elevated xCT. These findings suggest that selection of PTEN mutation during tumor development may be due to its ability to confer resistance to ferroptosis in the setting of metabolic and oxidative stress that occurs during tumor initiation and progression.

Malic Enzyme 1 as a Novel Anti-Ferroptotic Regulator in Hepatic Ischemia/Reperfusion Injury

Ferroptosis has been linked to the pathogenesis of hepatic injury induced by ischemia/reperfusion (I/R). However, the mechanistic basis remains unclear. In this study, by using a mouse model of hepatic I/R injury, it is observed that glutathione (GSH) and cysteine depletion are associated with deficiency of the reducing power of nicotinamide adenine dinucleotide phosphate (NADPH). Genes involved in maintaining NADPH homeostasis are screened, and it is identified that I/R-induced hepatic ferroptosis is significantly associated with reduced expression and activity of NADP⁺ -dependent malic enzyme 1 (Me1). Mice with hepatocyte-specific Me1 gene deletion exhibit aggravated ferroptosis and liver injury under I/R treatment; while supplementation with L-malate, the substrate of ME1, restores NADPH and GSH levels and eventually inhibits I/R-induced hepatic ferroptosis and injury. A mechanistic study further reveals that downregulation of hepatic Me1 expression is largely mediated by the phosphatase and tensin homologue (PTEN)-dependent suppression of the mechanistic target of rapamycin/sterol regulatory element-binding protein 1 (mTOR/SREBP1) signaling pathway in hepatic I/R model. Finally, PTEN inhibitor, mTOR activator, or SREBP1 over-expression all increase hepatic NADPH, block ferroptosis, and protect liver against I/R injury. Taken together, the findings suggest that targeting ME1 may provide new therapeutic opportunities for I/R injury and other ferroptosis-related hepatic conditions.

Inhibiting SCD expression by IGF1R during lorlatinib therapy sensitizes melanoma to ferroptosis

Induction of ferroptosis is an emerging strategy to suppress melanoma progression. Strategies to enhance the sensitivity to ferroptosis induction would be a major advance in melanoma therapy. Here, we used a drug synergy screen that combined a ferroptosis inducer, RSL3, with 240 anti-tumor drugs from the FDA-approved drug library and identified lorlatinib to synergize with RSL3 in melanoma cells. We further demonstrated that lorlatinib sensitized melanoma to ferroptosis through inhibiting PI3K/AKT/mTOR signaling axis and its downstream SCD expression. Moreover, we found that lorlatinib's target IGF1R, but not ALK or ROS1, was the major mediator of lorlatinib-mediated sensitivity to ferroptosis through targeting PI3K/AKT/mTOR signaling axis. Finally, lorlatinib treatment sensitized melanoma to GPX4 inhibition in preclinical animal models, and melanoma patients with low GPX4 and IGF1R expression in their tumors survived for longer period. Altogether, lorlatinib sensitizes melanoma to ferroptosis by targeting IGF1R-mediated PI3K/AKT/mTOR signaling axis, suggesting that combination with lorlatinib could greatly expand the utility of GPX4 inhibition to melanoma patients with IGF1R-proficient expression.

Butyrate dictates ferroptosis sensitivity through FFAR2-mTOR signaling

Evidence shows that short-chain fatty acids (SCFAs) play an important role in health maintenance and disease development. In particular, butyrate is known to induce apoptosis and autophagy. However, it remains largely unclear whether butyrate can regulate cell ferroptosis, and the mechanism by which has not been studied. In this study, we found that RAS-selective lethal compound 3 (RSL3)- and erastin-induced cell ferroptosis were enhanced by sodium butyrate (NaB). With regard to the underlying mechanism, our results showed that NaB promoted ferroptosis by inducing lipid ROS production via downregulating the expression of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4). Moreover, the FFAR2-AKT-NRF2 axis and FFAR2-mTORC1 axis accounts for the NaB-mediated downregulation of SLC7A11 and GPX4, respectively, in a cAMP-PKA-dependent manner. Functionally, we found that NaB can inhibit tumor growth and the inhibitory effect could be eliminated by administrating MHY1485 (mTORC1 activator) and Ferr-1 (ferroptosis inhibitor). Altogether, in vivo results suggest that NaB treatment is correlated to the mTOR-dependent ferroptosis and consequent tumor growth through xenografts and colitis-associated colorectal tumorigenesis, implicating the potential clinical applications of NaB for future colorectal cancer treatments. Based on all these findings, we have proposed a regulatory mechanism via which butyrate inhibits the mTOR pathway to control ferroptosis and consequent tumorigenesis.

TEA Domain Transcription Factor 1 Inhibits Ferroptosis and Sorafenib Sensitivity of Hepatocellular Carcinoma Cells

BACKGROUND

Ferroptosis, as a unique form of cell death, plays crucial negative roles in tumorigenesis and progression. This study aimed to investigate the role and molecular mechanism of TEA domain transcription factor 1 (TEAD1) in HCC and its effect on sorafenib-induced ferroptosis.

METHODS

TEAD1 expression was analyzed in HCC tissues using quantitative PCR, and western blot. The effects on cell proliferation, migration and invasion were determined by CCK-8, wound healing and Transwell assays. Intracellular iron, reactive oxygen species (ROS), malondialdehyde (MDA) and GSH measurement was used to assess ferroptosis. Chromatin immunoprecipitation and luciferase reporter gene assays were performed to verify the relationship between TEAD1 and solute carrier family 3 member 2 (SLC3A2). Expression of mTOR, ribosomal protein S6, glutathione peroxidase 4 (GPX4) and SLC3A2 was analyzed by western blot. Tumor xenografts were used assess the effect of TEAD1 on tumor growth in vivo.

RESULTS

TEAD1 was more abundant in HCC compared with normal tissues. Overexpression of TEAD1 enhanced the proliferation, migration, and invasion of HCC cells, while knockdown of TEAD1 inhibited these cell behaviors. Further, TEAD1 inhibited ferroptosis, which was demonstrated by decreased intracellular Fe²⁺ content, ROS, and MDA levels, and increased GSH activity. Mechnistically, TEAD1 promotes the transcription of SLC3A2 and activates the mTOR signaling. Additionally, silenced TEAD1 restrained tumor growth and enhance sorafenib-induced antitumor activity in vivo.

CONCLUSIONS

TEAD1 confers resistance of HCC cells to ferroptosis, thereby promoting the progression of HCC, suggesting the potential value of TEAD1 in the diagnosis and treatment of HCC.

DHODH Inhibition Exerts Synergistic Therapeutic Effect with Cisplatin to Induce Ferroptosis in Cervical Cancer through Regulating mTOR Pathway

Ferroptosis exhibits a potent antitumor effect and dihydroorotate dehydrogenase (DHODH) has recently been identified as a novel ferroptosis defender. However, the role of DHODH inhibition in cervical cancer cells is unclear, particularly in synergy with cisplatin via ferroptosis. Herein, shRNA and brequinar were used to knock down DHODH and directly inhibit DHODH, respectively. Immunohistochemistry and Western blotting assays were performed to measure the expression of proteins. CCK-8 and colony formation assays were employed to assess the cell viability and proliferation. Ferroptosis was monitored through flow cytometry, the malondialdehyde assay kit and JC-1 staining analyses. The nude mouse xenograft model was generated to examine the effect of combination of DHODH inhibition and cisplatin on tumor growth in vivo. The expression of DHODH was increased in cervical cancer tissues. DHODH inhibition inhibited the proliferation and promoted the ferroptosis in cervical cancer cells. A combination of DHODH inhibition and cisplatin synergistically induced both in vitro and in vivo ferroptosis and downregulated the ferroptosis defender mTOR pathway. Therefore, the combination of DHODH inhibition and cisplatin exhibits synergistic effects on ferroptosis induction via inhibiting the mTOR pathway could provide a promising way for cervical cancer therapy.

Cell death-related biomarker SLC2A1 has a significant role in prognosis prediction and immunotherapy efficacy evaluation in pan-cancer

Introduction: SLC2A1, a member of the SLC transporter family, is involved in a variety of cell death modalities and has been found to be associated with the prognosis and immune microenvironment of a variety of tumors. However, there is a lack of systematic and comprehensive studies on the role of SLC2A1 in pan-cancer. Methods: The mRNA, promoter methylation, and protein expression levels of SLC2A1 in pan-cancer were comprehensively evaluated using GEPIA2.0, TIMER2.0, and UALCAN databases. UCSCXenaShiny based on the cancer genomic atlas pan-cancer data and GEPIA2.0 database were used to assess the prognostic significance of SLC2A1 in pan-cancer. Genetic alterations in SLC2A1 were also evaluated using cBioPortal. The relevance of SLC2A1 to immune infiltrating cells in pan-cancer was evaluated using the XCELL algorithm in combination with the TIMER2.0 database. The correlation of SLC2A1 with the efficacy of immune checkpoint blocker (ICB) therapy was evaluated using the tumor immune dysfunction and exclusion (TIDE) score. The correlation of SLC2A1 with numerous immune-related markers was also evaluated using the TISIDB database. The correlation of SLC2A1 with tumor biological function was evaluated at the single-cell level using the CancerSEA database. Finally, the biological function of SLC2A1 was comprehensively evaluated using gene set enrichment analysis (GSEA) and protein interaction networks. Results: SLC2A1 expression is aberrant in a variety of tumors and is strongly associated with the prognosis of several cancers. SLC2A1 is significantly associated with a variety of immune infiltrating cells including CD8⁺ T cells, myeloid-derived suppressor cells and macrophages in a variety of tumors. Meanwhile, the expression of SLC2A1 significantly correlated with multiple immune-related markers. In addition, SLC2A1 can also predict the effect of immune checkpoint blocker therapy in some tumors. In a functional analysis, SLC2A1 was significantly associated with hypoxia, epithelial-mesenchymal transition, mTORC1 signaling, and multiple metabolic pathways in pan-cancer. Conclusion: Our study systematically and comprehensively summarizes the prognostic significance and immune-related role of SLC2A1 in pan-cancer and reveals the potential mechanism of SLC2A1 in regulating the tumor microenvironment and tumor behavior, providing a new effective pan-applicable biomarker for prognostic prediction and the evaluation of immunotherapeutic strategies for tumors.

DN200434, an orally available inverse agonist of estrogen-related receptor γ, induces ferroptosis in sorafenib-resistant hepatocellular carcinoma

Sorafenib, originally identified as an inhibitor of multiple oncogenic kinases, induces ferroptosis in hepatocellular carcinoma (HCC) cells. Several pathways that mitigate sorafenib-induced ferroptosis confer drug resistance; thus strategies that enhance ferroptosis increase sorafenib efficacy. Orphan nuclear receptor estrogen-related receptor γ (ERRγ) is upregulated in human HCC tissues and plays a role in cancer cell proliferation. The aim of this study was to determine whether inhibition of ERRγ with DN200434, an orally available inverse agonist, can overcome resistance to sorafenib through induction of ferroptosis. Sorafenib-resistant HCC cells were less sensitive to sorafenibinduced ferroptosis and showed significantly higher ERRγ levels than sorafenib-sensitive HCC cells. DN200434 induced lipid peroxidation and ferroptosis in sorafenib-resistant HCC cells. Mechanistically, DN200434 increased mitochondrial ROS generation by reducing glutathione/glutathione disulfide levels, which subsequently reduced mTOR activity and GPX4 levels. DN200434 induced amplification of the antitumor effects of sorafenib was confirmed in a tumor xenograft model. The present results indicate that DN200434 may be a novel therapeutic strategy to re-sensitize HCC cells to sorafenib. [BMB Reports 2022; 55(11): 547-552].

DN200434, an orally available inverse agonist of estrogen-related receptor γ, induces ferroptosis in sorafenib-resistant hepatocellular carcinoma

Sorafenib, originally identified as an inhibitor of multiple oncogenic kinases, induces ferroptosis in hepatocellular carcinoma (HCC) cells. Several pathways that mitigate sorafenib-induced ferroptosis confer drug resistance; thus strategies that enhance ferroptosis increase sorafenib efficacy. Orphan nuclear receptor estrogen-related receptor γ (ERRγ) is upregulated in human HCC tissues and plays a role in cancer cell proliferation. The aim of this study was to determine whether inhibition of ERRγ with DN200434, an orally available inverse agonist, can overcome resistance to sorafenib through induction of ferroptosis. Sorafenib-resistant HCC cells were less sensitive to sorafenibinduced ferroptosis and showed significantly higher ERRγ levels than sorafenib-sensitive HCC cells. DN200434 induced lipid peroxidation and ferroptosis in sorafenib-resistant HCC cells. Mechanistically, DN200434 increased mitochondrial ROS generation by reducing glutathione/glutathione disulfide levels, which subsequently reduced mTOR activity and GPX4 levels. DN200434 induced amplification of the antitumor effects of sorafenib was confirmed in a tumor xenograft model. The present results indicate that DN200434 may be a novel therapeutic strategy to re-sensitize HCC cells to sorafenib. [BMB Reports 2022; 55(11): 547-552].

KIAA0101 and IL2RA Were Identified as Core Genes in Hormone-Resistant Nephropathy

Objectives

To analyze the tissue heterogeneity of hormone-sensitive and drug-resistant nephrotic syndrome genes using a bioinformatics approach and to analyze gene-related functional pathways.

Methods

The limma package of R software was used to screen differential genes from the nephropathy datasets GSE145969 and GSE189734. The differential genes were analyzed for functional and pathway enrichment in terms of biological processes, cellular components, and molecular functions. The Metascape tool was used to construct protein networks for the differential genes, and the results were imported into Cytoscape software for visualization. The genes were identified as key modules and genes using the MCODE plug-in. Gene set enrichment analysis was performed for the HALLMARK analysis of the two microarray key genes to obtain the relevant pathways.

Results

GSE145969 screened 351 differential genes, 168 upregulated genes, and 183 downregulated genes. The differential genes were enriched in biological processes, cellular components, and molecular functions, such as myocardial contraction, intracellular nonmembrane organelles, and structural molecular activities. The protein-protein interaction (PPI) network contained 140 nodes, with the highest-scoring module containing seven genes, and the MCODE plug-in calculated the downseed. The key gene was KIAA0101, whose HALLMARK pathway was significantly enriched in the mTORC1 signaling pathway. A total of 263 differential genes were screened by GSE189734, and they were enriched in biological processes, molecular functions, and cellular components, such as immune system processes, signaling receptor binding, and the cytoplasmic matrix. The PPI network contained 253 nodes, with the highest-scoring module containing 37 genes. The seed gene obtained through the MCODE plug-in calculation was IL2RA, whose HALLMARK pathway was significantly enriched in the KRAS signaling pathway.

Conclusion

By analyzing the gene sets of different tissues in nephropathy, two key genes, namely KIAA0101 and IL2RA, were obtained. Their gene function enrichment is related to cell growth, development, and reproduction. Therefore, IL2RA and KIAA0101 can be used as diagnostic markers for hormone-resistant nephropathy.

UFL1 alleviates ER stress and apoptosis stimulated by LPS via blocking the ferroptosis pathway in human granulosa-like cells

Ubiquitin-like modifier 1 ligating enzyme 1 (UFL1) is a unique E3 ligase of the UFMylation system. Recent studies have shown that this enzyme plays a crucial role in the processes of endoplasmic reticulum stress (ER stress) and apoptosis. Lipopolysaccharide (LPS) can cause injury to ovarian granule cells and hinder follicular development by triggering ER stress and apoptosis. Our study aimed to investigate the mechanism by which UFL1 alleviates ER stress and apoptosis caused by LPS in human granulosa-like cells (KGNs). In this study, we found that the protein levels of UFL1 were increased obviously under LPS stimulation in KGNs and that ER stress and apoptosis were further aggravated when UFL1 was knocked down; in contrast, these events were rescued when UFL1 was overexpressed. Next, we showed that the levels of ferroptosis-related proteins were relatively altered, accompanied by the accumulation of reactive oxygen species (ROS) and Fe2+, following the inhibition of UFL1 expression. In contrast, the overexpression of UFL1 reversed the ferroptosis process by regulating the P53/SLC7A11 (solute carrier family 7, member 11, SLC7A11) system and autophagy in response to LPS stimulation. Furthermore, apoptosis and ER stress in KGNs are rescued by the administration of the ferroptosis inhibitor ferrostatin-1 (Fer-1). Collectively, our research demonstrated a new mechanism for UFL1 that can alleviate ER stress and apoptosis stimulated by LPS; this occurred via the regulation of the ferroptosis pathway in KGNs and may provide a new strategy for research in the field of reproduction.

Aspirin promotes RSL3-induced ferroptosis by suppressing mTOR/SREBP-1/SCD1-mediated lipogenesis in PIK3CA-mutant colorectal cancer

Ferroptosis, a new form of regulated cell death triggered by the iron-dependent peroxidation of phospholipids, is associated with cellular metabolism, redox homeostasis, and various signaling pathways related to cancer. Aspirin is a widely used non-steroidal anti-inflammatory drug (NSAID) and has been reported to show therapeutic benefit in cancers harboring oncogenic PIK3CA, which encodes the catalytic p110α subunit of phosphoinositide 3-kinase (PI3K). In this study, we found that aspirin sensitized cancer cells harboring oncogenic activation of PIK3CA to ferroptosis induction. Mechanistically, aspirin inhibited protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling, suppressed downstream sterol regulatory element-binding protein 1 (SREBP-1) expression, and attenuated stearoyl-CoA desaturase-1 (SCD1)-mediated lipogenesis of monounsaturated fatty acids, thus promoting RSL3-induced ferroptosis in colorectal cancer (CRC) cells. Moreover, genetic ablation of SREBP-1 or SCD1 conferred cancer cells greater sensitivity to ferroptosis induction. Conversely, ectopic expression of SREBP-1 or SCD1 restored ferroptosis resistance in CRC cells and abolished the effect of aspirin on RSL3-induced cytotoxicity. Additionally, the synergistic effects of aspirin and RSL3 were confirmed in a xenograft mouse model. The combined use of aspirin and RSL3 resulted in significant tumor suppression. Our work demonstrated that aspirin enhanced the cytotoxic effect of RSL3 in PIK3CA-mutant cancers, and the combination of aspirin and ferroptosis inducer displayed promising therapeutic effects in cancer treatment.

Citrate Regulates the Saccharomyces cerevisiae Mitochondrial GDP/GTP Carrier (Ggc1p) by Triggering Unidirectional Transport of GTP

The yeast mitochondrial transport of GTP and GDP is mediated by Ggc1p, a member of the mitochondrial carrier family. The physiological role of Ggc1p in S. cerevisiae is probably to transport GTP into mitochondria in exchange for GDP generated in the matrix. ggc1Δ cells exhibit lower levels of GTP and increased levels of GDP in mitochondria, are unable to grow on nonfermentable substrates and lose mtDNA. Because in yeast, succinyl-CoA ligase produces ATP instead of GTP, and the mitochondrial nucleoside diphosphate kinase is localized in the intermembrane space, Ggc1p is the only supplier of mitochondrial GTP required for the maturation of proteins containing Fe-S clusters, such as aconitase [4Fe-4S] and ferredoxin [2Fe-2S]. In this work, it was demonstrated that citrate is a regulator of purified and reconstituted Ggc1p by trans-activating unidirectional transport of GTP across the proteoliposomal membrane. It was also shown that the binding site of Ggc1p for citrate is different from the binding site for the substrate GTP. It is proposed that the citrate-induced GTP uniport (CIGU) mediated by Ggc1p is involved in the homeostasis of the guanine nucleotide pool in the mitochondrial matrix.

Targeting Molecular Mediators of Ferroptosis and Oxidative Stress for Neurological Disorders

With the acceleration of population aging, nervous system diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), anxiety, depression, stroke, and traumatic brain injury (TBI) have become a huge burden on families and society. The mechanism of neurological disorders is complex, which also lacks effective treatment, so relevant research is required to solve these problems urgently. Given that oxidative stress-induced lipid peroxidation eventually leads to ferroptosis, both oxidative stress and ferroptosis are important mechanisms causing neurological disorders, targeting mediators of oxidative stress and ferroptosis have become a hot research direction at present. Our review provides a current view of the mechanisms underlying ferroptosis and oxidative stress participate in neurological disorders, the potential application of molecular mediators targeting ferroptosis and oxidative stress in neurological disorders. The target of molecular mediators or agents of oxidative stress and ferroptosis associated with neurological disorders, such as reactive oxygen species (ROS), nuclear factor erythroid 2–related factor-antioxidant response element (Nrf2-ARE), n-acetylcysteine (NAC), Fe²⁺, NADPH, and its oxidases NOX, has been described in this article. Given that oxidative stress-induced ferroptosis plays a pivotal role in neurological disorders, further research on the mechanisms of ferroptosis caused by oxidative stress will help provide new targets for the treatment of neurological disorders.

Hypersensitivity to ferroptosis in chromophobe RCC is mediated by a glutathione metabolic dependency and cystine import via solute carrier family 7 member 11

Chromophobe (Ch) renal cell carcinoma (RCC) arises from the intercalated cell in the distal nephron. There are no proven treatments for metastatic ChRCC. A distinguishing characteristic of ChRCC is strikingly high levels of reduced (GSH) and oxidized (GSSG) glutathione. Here, we demonstrate that ChRCC-derived cells exhibit higher sensitivity to ferroptotic inducers compared with clear-cell RCC. ChRCC-derived cells are critically dependent on cystine via the cystine/glutamate antiporter xCT to maintain high levels of glutathione, making them sensitive to inhibitors of cystine uptake and cyst(e)inase. Gamma-glutamyl transferase 1 (GGT1), a key enzyme in glutathione homeostasis, is markedly suppressed in ChRCC relative to normal kidney. Importantly, GGT1 overexpression inhibits the proliferation of ChRCC cells in vitro and in vivo, suppresses cystine uptake, and decreases levels of GSH and GSSG. Collectively, these data identify ferroptosis as a metabolic vulnerability in ChRCC, providing a potential avenue for targeted therapy for these distinctive tumors.

Targeting ferroptosis as a vulnerability in cancer

Ferroptosis is an iron-dependent form of regulated cell death that is triggered by the toxic build-up of lipid peroxides on cellular membranes. In recent years, ferroptosis has garnered enormous interest in cancer research communities, partly because it is a unique cell death modality that is mechanistically and morphologically different from other forms of cell death, such as apoptosis, and therefore holds great potential for cancer therapy. In this Review, we summarize the current understanding of ferroptosis-inducing and ferroptosis defence mechanisms, dissect the roles and mechanisms of ferroptosis in tumour suppression and tumour immunity, conceptualize the diverse vulnerabilities of cancer cells to ferroptosis, and explore therapeutic strategies for targeting ferroptosis in cancer.

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.

Non-coding RNAs in ferroptotic cancer cell death pathway: meet the new masters

Despite the recent advances in cancer therapy, cancer chemoresistance looms large along with radioresistance, a major challenge in dire need of thorough and minute investigation. Not long ago, cancer cells were reported to have proven refractory to the ferroptotic cell death, a newly discovered form of regulated cell death (RCD), conspicuous enough to draw attention from scholars in terms of targeting ferroptosis as a prospective therapeutic strategy. However, our knowledge concerning the underlying molecular mechanisms through which cancer cells gain immunity against ferroptosis is still in its infancy. Of late, the implication of non-coding RNAs (ncRNAs), including circular RNAs (circRNAs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) in ferroptosis has been disclosed. Nevertheless, precisely explaining the molecular mechanisms behind the contribution of ncRNAs to cancer radio/chemotherapy resistance remains a challenge, requiring further clarification. In this review, we have presented the latest available information on the ways and means of regulating ferroptosis by ncRNAs. Moreover, we have provided important insights about targeting ncRNAs implicated in ferroptosis with the hope of opening up new horizons for overcoming cancer treatment modalities. Though a long path awaits until we make this ambitious dream come true, recent progress in gene therapy, including gene-editing technology will aid us to be optimistic that ncRNAs-based ferroptosis targeting would soon be on stream as a novel therapeutic strategy for treating cancer.

Silencing of lncRNA MALAT1 facilitates erastin-induced ferroptosis in endometriosis through miR-145-5p/MUC1 signaling

Endometriosis is a chronic disorder characterized by the implantation of endometrial glands and stroma outside the uterus. However, the pathogenesis of endometriosis is still unclear. To date, there is no fully effective treatment without trauma because of various side effects. Recent data suggest that ferroptosis is a novel recognized form of nonapoptosis-regulated cell death characterized by iron-dependent and lethal lipid peroxidation accumulation, showing great promise in the treatment of many diseases. In the present study, we verified that erastin induced ferroptosis in ectopic endometrial stromal cells (EESCs). Furthermore, we found that the expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was decreased during erastin-induced ferroptosis. Knockdown of MALAT1 significantly aggravated the inhibition of cell viability and increased intracellular iron, Liperfluo, and MDA levels in EESCs upon erastin treatment. Mechanistically, we demonstrated that MALAT1 served as a competing endogenous RNA of miR-145-5p to regulate the expression of MUC1, a suppressor of ferroptosis. MALAT1 knockdown-mediated ferroptotic cell death and MUC1 downregulation could be abrogated by inhibition of miR-145-5p. In addition, miR-145-5p inhibition-mediated ferroptotic cell death could be abolished by MUC1 knockdown. Furthermore, erastin-induced ferroptosis shrunk endometriotic lesions via the MALAT1/miR-145-5p/MUC1 axis in vivo. Taken together, our data indicate that knockdown of MALAT1 facilitates ferroptosis upon erastin treatment via miR-145-5p/MUC1 signaling. The synergistic effect of MALAT1 knockdown and erastin induction in ferroptosis may be a new therapeutic strategy for endometriosis.

Single PFAS and PFAS mixtures affect nuclear receptor- and oxidative stress-related pathways in precision-cut liver slices of Atlantic cod (Gadus morhua)

The aim of the present study was to investigate effects of per- and polyfluoroalkyl substances (PFAS), both single compounds and a mixture of these, using precision-cut liver slices (PCLS) from Atlantic cod (Gadus morhua). PCLS were exposed for 48 h to perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) (10, 50 and 100 μM), and three mixtures of these at equimolar concentrations (10, 50 and 100 μM). Transcriptomic responses were assessed using RNA sequencing. Among exposures to single PFAS, PFOS produced the highest number of differentially expressed genes (DEGs) compared to PFOA and PFNA (86, 25 and 31 DEGs, respectively). Exposure to the PFAS mixtures resulted in a markedly higher number of DEGs (841). Clustering analysis revealed that the expression pattern of the PFAS mixtures were more similar to PFOS compared to PFOA and PFNA, suggesting that effects induced by the PFAS mixtures may largely be attributed to PFOS. Pathway analysis showed significant enrichment of pathways related to oxidative stress, cholesterol metabolism and nuclear receptors in PFOS-exposed PCLS. Fewer pathways were significantly enriched following PFOA and PFNA exposure alone. Significantly enriched pathways following mixture exposure included lipid biosynthesis, cancer-related pathways, nuclear receptor pathways and oxidative stress-related pathways such as ferroptosis. The expression of most of the genes within these pathways was increased following PFAS exposure. Analysis of non-additive effects in the 100 μM PFAS mixture highlighted genes involved in the antioxidant response and membrane transport, among others, and the majority of these genes had synergistic expression patterns in the mixture. Nevertheless, 90% of the DEGs following mixture exposure showed additive expression patterns, suggesting additivity to be the major mixture effect. In summary, PFAS exposure promoted effects on cellular processes involved in oxidative stress, nuclear receptor pathways and sterol metabolism in cod PCLS, with the strongest effects observed following PFAS mixture exposure.

NVP-BEZ235 Inhibits Renal Cell Carcinoma by Targeting TAK1 and PI3K/Akt/mTOR Pathways

In spite of the promising in vitro and preclinical results, dual PI3K/Akt/mTOR inhibitor NVP-BEZ235, and ATP-competitive mTOR inhibitor PP242 both failed to confirm their inhibitory efficacy against renal cell carcinoma (RCC) in clinical settings. Therefore, a better understanding of the molecular mechanism is essential so as to provide possibilities for their use in combination with other agents. In present study, RCC cell lines (UMRC6, 786-0 and UOK121) were treated with NVP-BEZ235, PP242 or Rapamycin, an mTOR complex 1 (mTORC1)-specific inhibitor. They all suppressed cell proliferation and invasion, induced apoptosis and cell cycle arrest, and the effects were in the order of NVP-BEZ235 > PP242 > Rapamycin. Accordingly, the marked and sustained decrease in speckle-type POZ protein (SPOP) expression and phosphorylation of Akt and mTOR kinases was observed in RCC cells treated with NVP-BEZ235 and PP242, whereas only potent inhibition of mTOR activity was induced in Rapamycin-treated cells. In considering the overactivation of c-Jun and IκB-α in human renal tumor tissue, we next investigated the role of JNK and IKK pathways in the response of RCC cells to these compounds. First of all, transforming growth factor β activated kinase 1 (TAK1)-dependent activation of JNK/ (activator protein-1) AP-1 axis in RCC cells was proved by the repression of AP-1 activity with TAK1 or JNK inhibitor. Second, the profound inhibition of TAK1/JNK/AP-1 pathway was demonstrated in RCC cells treated with NVP-BEZ235 or PP242 but not Rapamycin, which is manifested as a reduction in activity of TAK1, c-Jun and AP-1. Meanwhile, subsequent to TAK1 inactivation, the activation of IκB-α was also reduced by NVP-BEZ235 and PP242. Likewise, in vivo, treatment with NVP-BEZ235 and PP242 suppressed the growth of xenografts generated from 786-0 and A498 cells, along with decreased expression of phospho-TAK1, phospho-c-Jun, and phospho-IκB-α. In contrast, Rapamycin elicited no significant inhibitory effects on tumor growth and phosphorylation of TAK1, c-Jun and IκB-α. We conclude that besides PI3K/Akt/mTOR signaling, NVP-BEZ235, and PP242 simultaneously target TAK1-dependent pathways in RCC cells. Notably, these effects were more marked in the presence of NVP-BEZ235 than PP242, indicating the potential application of NVP-BEZ235 in combination therapy for RCC.