NCOA4-Mediated Ferritinophagy Is a Pancreatic Cancer Dependency via Maintenance of Iron Bioavailability for Iron-Sulfur Cluster Proteins

Nanoparticles targeting OPN loaded with BY1 inhibits vascular restenosis by inducing FTH1-dependent ferroptosis in vascular smooth muscle cells

Vascular restenosis following angioplasty continues to pose a significant challenge. The heterocyclic trioxirane compound [1, 3, 5-tris((oxiran-2-yl)methyl)-1, 3, 5-triazinane-2, 4, 6-trione (TGIC)], known for its anticancer activity, was utilized as the parent ring to conjugate with a non-steroidal anti-inflammatory drug, resulting in the creation of the spliced conjugated compound BY1. We found that BY1 induced ferroptosis in VSMCs as well as in neointima hyperplasia. Furthermore, ferroptosis inducers amplified BY1-induced cell death, while inhibitors mitigated it, indicating the contribution of ferroptosis to BY1-induced cell death. Additionally, we established that ferritin heavy chain1 (FTH1) played a pivotal role in BY1-induced ferroptosis, as evidenced by the fact that FTH1 overexpression abrogated BY1-induced ferroptosis, while FTH1 knockdown exacerbated it. Further study found that BY1 induced ferroptosis by enhancing the NCOA4-FTH1 interaction and increasing the amount of intracellular ferrous. We compared the effectiveness of various administration routes for BY1, including BY1-coated balloons, hydrogel-based BY1 delivery, and nanoparticles targeting OPN loaded with BY1 (TOP@MPDA@BY1) for targeting proliferated VSMCs, for prevention and treatment of the restenosis. Our results indicated that TOP@MPDA@BY1 was the most effective among the three administration routes, positioning BY1 as a highly promising candidate for the development of drug-eluting stents or treatments for restenosis.

The Mutual Regulatory Role of Ferroptosis and Immunotherapy in Anti-tumor Therapy

Ferroptosis is a form of cell death that is triggered by the presence of ferrous ions and is characterized by lipid peroxidation induced by these ions. The mechanism exhibits distinct morphological characteristics compared to apoptosis, autophagy, and necrosis. A notable aspect of ferroptosis is its ability to inhibit uncontrolled tumor replication and immortalization, especially in malignant, drug-resistant, and metastatic tumors. Additionally, immunotherapy, a novel therapeutic approach for tumors, has been found to have a reciprocal regulatory relationship with ferroptosis in the context of anti-tumor therapy. A comprehensive analysis of ferroptosis and immunotherapy in tumor therapy is presented in this paper, highlighting the potential for mutual adjuvant effects. Specifically, we discuss the mechanisms underlying ferroptosis and immunotherapy, emphasizing their ability to improve the tumor immune microenvironment and enhance immunotherapeutic effects. Furthermore, we investigate how immunotherapeutic factors may increase the sensitivity of tumor cells to ferroptosis. We aim to provide a prospective view of the promising value of combined ferroptosis and immunotherapy in anticancer therapy by elucidating the mutual regulatory network between each.

Exploiting pancreatic cancer metabolism: challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive form of pancreatic cancer, known for its challenging diagnosis and limited treatment options. The focus on metabolic reprogramming as a key factor in tumor initiation, progression, and therapy resistance has gained prominence. In this review we focus on the impact of metabolic changes on the interplay among stromal, immune, and tumor cells, as glutamine and branched-chain amino acids (BCAAs) emerge as pivotal players in modulating immune cell functions and tumor growth. We also discuss ongoing clinical trials that explore metabolic modulation for PDAC, targeting mitochondrial metabolism, asparagine and glutamine addiction, and autophagy inhibition. Overcoming challenges in understanding nutrient effects on immune-stromal-tumor interactions holds promise for innovative therapeutic strategies.

Anticancer efficacy triggered by synergistically modulating the homeostasis of anions and iron: Design, synthesis and biological evaluation of dual-functional squaramide-hydroxamic acid conjugates

Targeting the homeostasis of anions and iron has emerged as a promising therapeutic approach for the treatment of cancers. However, single-targeted agents often fall short of achieving optimal treatment efficacy. Herein we designed and synthesized a series of novel dual-functional squaramide-hydroxamic acid conjugates that are capable of synergistically modulating the homeostasis of anions and iron. Among them, compound 16 exhibited the most potent antiproliferative activity against a panel of selected cancer cell lines, and strong in vivo anti-tumor efficacy. This compound effectively elevated lysosomal pH through anion transport, and reduced the levels of intracellular iron. Compound 16 could disturb autophagy in A549 cells and trigger robust apoptosis. This compound caused cell cycle arrest at the G1/S phase, altered the mitochondrial function and elevated ROS levels. The present findings clearly demonstrated that synergistic modulation of anion and iron homeostasis has high potentials in the development of promising chemotherapeutic agents with dual action against cancers.

Dissecting tumor transcriptional heterogeneity from single-cell RNA-seq data by generalized binary covariance decomposition

Profiling tumors with single-cell RNA sequencing (scRNA-seq) has the potential to identify recurrent patterns of transcription variation related to cancer progression, and produce new therapeutically relevant insights. However, the presence of strong inter-tumor heterogeneity often obscures more subtle patterns that are shared across tumors, some of which may characterize clinically relevant disease subtypes. Here we introduce a new statistical method, generalized binary covariance decomposition (GBCD), to address this problem. We show that GBCD can help decompose transcriptional heterogeneity into interpretable components - including patient-specific, dataset-specific and shared components relevant to disease subtypes - and that, in the presence of strong inter-tumor heterogeneity, it can produce more interpretable results than existing methods. Applied to data from three studies on pancreatic cancer adenocarcinoma (PDAC), GBCD produces a refined characterization of existing tumor subtypes (e.g., classical vs. basal), and identifies a new gene expression program (GEP) that is prognostic of poor survival independent of established prognostic factors such as tumor stage and subtype. The new GEP is enriched for genes involved in a variety of stress responses, and suggests a potentially important role for the integrated stress response in PDAC development and prognosis.

Myeloid NCOA4 sequesters KEAP1 to reduce ferroptosis for protection against salmonellosis in mice

Salmonellosis, caused by Salmonella enterica serovar Typhimurium, is a significant global threat. Host immunity limits bacterial replication by inducing hepcidin, which degrades ferroportin, reducing iron transfer. However, this boosts macrophage iron storage, aiding intracellular pathogens like Salmonella. Mice lacking ferritin heavy chain (FTH1) in myeloid cells suffer worsened Salmonella infection. Nuclear receptor co-activator 4 (NCOA4) regulates iron release via FTH1 degradation during low iron, but its role in salmonellosis is unclear. Here, we reveal that myeloid NCOA4 deficiency augments spleen iron levels and increases cellular iron accumulation, oxidative stress, and ferroptosis in bone marrow-derived macrophages. This deficiency also increases susceptibility to Salmonella-induced colitis in mice. Mechanistically, NCOA4 suppresses oxidative stress by directly binding to the E3 ubiquitin ligase Kelch-like ECH-associated protein 1 (KEAP1) and stabilizing the antioxidant transcription factor nuclear factor-erythroid 2-related factor 2 (NRF2). Activation of NRF2 protects myeloid NCOA4 knockout mice from Salmonella-induced colitis. Antioxidant Tempol and myeloid cell-targeted curcumin offer protection against colitis in myeloid NCOA4-deficient mice. A low iron diet and ferroptosis inhibition also mitigate the heightened colitis in these mice. Overexpression of myeloid cell-specific NCOA4 confers protection against Salmonella-induced colitis via upregulating NRF2 signaling. Serum iron was reduced in myeloid NCOA4-overexpressing mice, but not in NCOA4-deficient mice. Targeted serum metabolomics analysis revealed that many lipids were decreased in myeloid NCOA4-deficient mice, while several of them were increased in myeloid NCOA4-overexpressing mice. Together, this study not only advances our understanding of NCOA4/KEAP1/NRF2/ferroptosis axis but also paves the way for novel myeloid cell-targeted therapies to combat salmonellosis.

Ferritinophagy mediates adaptive resistance to EGFR tyrosine kinase inhibitors in non-small cell lung cancer

Osimertinib (Osi) is a widely used epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). However, the emergence of resistance is inevitable, partly due to the gradual evolution of adaptive resistant cells during initial treatment. Here, we find that Osi treatment rapidly triggers adaptive resistance in tumor cells. Metabolomics analysis reveals a significant enhancement of oxidative phosphorylation (OXPHOS) in Osi adaptive-resistant cells. Mechanically, Osi treatment induces an elevation of NCOA4, a key protein of ferritinophagy, which maintains the synthesis of iron-sulfur cluster (ISC) proteins of electron transport chain and OXPHOS. Additionally, active ISC protein synthesis in adaptive-resistant cells significantly increases the sensitivity to copper ions. Combining Osi with elesclomol, a copper ion ionophore, significantly increases the efficacy of Osi, with no additional toxicity. Altogether, this study reveals the mechanisms of NCOA4-mediated ferritinophagy in Osi adaptive resistance and introduces a promising new therapy of combining copper ionophores to improve its initial efficacy.

Structural basis for the intracellular regulation of ferritin degradation

The interaction between nuclear receptor coactivator 4 (NCOA4) and the iron storage protein ferritin is a crucial component of cellular iron homeostasis. The binding of NCOA4 to the FTH1 subunits of ferritin initiates ferritinophagy-a ferritin-specific autophagic pathway leading to the release of the iron stored inside ferritin. The dysregulation of NCOA4 is associated with several diseases, including neurodegenerative disorders and cancer, highlighting the NCOA4-ferritin interface as a prime target for drug development. Here, we present the cryo-EM structure of the NCOA4-FTH1 interface, resolving 16 amino acids of NCOA4 that are crucial for the interaction. The characterization of mutants, designed to modulate the NCOA4-FTH1 interaction, is used to validate the significance of the different features of the binding site. Our results explain the role of the large solvent-exposed hydrophobic patch found on the surface of FTH1 and pave the way for the rational development of ferritinophagy modulators.

Combinatorial strategies to target RAS-driven cancers

Although RAS was formerly considered undruggable, various agents that inhibit RAS or specific RAS oncoproteins have now been developed. Indeed, the importance of directly targeting RAS has recently been illustrated by the clinical success of mutant-selective KRAS inhibitors. Nevertheless, responses to these agents are typically incomplete and restricted to a subset of patients, highlighting the need to develop more effective treatments, which will likely require a combinatorial approach. Vertical strategies that target multiple nodes within the RAS pathway to achieve deeper suppression are being investigated and have precedence in other contexts. However, alternative strategies that co-target RAS and other therapeutic vulnerabilities have been identified, which may mitigate the requirement for profound pathway suppression. Regardless, the efficacy of any given approach will likely be dictated by genetic, epigenetic and tumour-specific variables. Here we discuss various combinatorial strategies to treat KRAS-driven cancers, highlighting mechanistic concepts that may extend to tumours harbouring other RAS mutations. Although many promising combinations have been identified, clinical responses will ultimately depend on whether a therapeutic window can be achieved and our ability to prospectively select responsive patients. Therefore, we must continue to develop and understand biologically diverse strategies to maximize our likelihood of success.

Iron, Copper, and Selenium: Cancer's Thing for Redox Bling

Cells require micronutrients for numerous basic functions. Among these, iron, copper, and selenium are particularly critical for redox metabolism, and their importance is heightened during oncogene-driven perturbations in cancer. In this review, which particularly focuses on iron, we describe how these micronutrients are carefully chaperoned about the body and made available to tissues, a process that is designed to limit the toxicity of free iron and copper or by-products of selenium metabolism. We delineate perturbations in iron metabolism and iron-dependent proteins that are observed in cancer, and describe the current approaches being used to target iron metabolism and iron-dependent processes.

Ferritinophagy Is Critical for Deoxynivalenol-Induced Liver Injury in Mice

Background: Deoxynivalenol (DON) contamination, pervasive throughout all stages of food production and processing, presents a significant threat to human health. The degradation of ferritin mediated by nuclear receptor coactivator 4 (NCOA4), termed ferritinophagy, plays a crucial role in maintaining iron homeostasis and regulating ferroptosis. Aim: This study aims to elucidate the role of ferritinophagy and ferroptosis in DON-induced liver injury. Methods: Male mice and AML12 cells were subjected to varying doses of DON, serving as in vivo and in vitro models, respectively. Protein expression was assessed by using immunofluorescence and western blot techniques. Co-immunoprecipitation was employed to investigate the protein-protein interactions. Results: Our findings demonstrate that DON triggers hepatocyte ferroptosis in a ferritinophagy-dependent manner. Specifically, DON impedes the activation of the mammalian target of rapamycin complex 1 (mTORC1) by inhibiting RAC1's binding to mTOR, thereby ultimately inducing autophagy. Concurrently, DON amplifies NCOA4's affinity for ferritin by facilitating NCOA4 phosphorylation through the ataxia-telangiectasia mutated kinase (ATM), thus promoting the autophagy-dependent degradation of ferritin. Both autophagy inhibition and NCOA4 expression suppression ameliorate DON-induced ferroptosis. Conclusion: Our study concludes that DON facilitates NCOA4-mediated ferritinophagy via the ATM-NCOA4 pathway, subsequently inducing ferroptosis in the liver.

Targeting PIKfyve-driven lipid homeostasis as a metabolic vulnerability in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) subsists in a nutrient-deregulated microenvironment, making it particularly susceptible to treatments that interfere with cancer metabolism12. For example, PDAC utilizes and is dependent on high levels of autophagy and other lysosomal processes3-5. Although targeting these pathways has shown potential in preclinical studies, progress has been hampered by the challenge of identifying and characterizing favorable targets for drug development6. Here, we characterize PIKfyve, a lipid kinase integral to lysosomal functioning7, as a novel and targetable vulnerability in PDAC. In human patient and murine PDAC samples, we discovered that PIKFYVE is overexpressed in PDAC cells compared to adjacent normal cells. Employing a genetically engineered mouse model, we established the essential role of PIKfyve in PDAC progression. Further, through comprehensive metabolic analyses, we found that PIKfyve inhibition obligated PDAC to upregulate de novo lipid synthesis, a relationship previously undescribed. PIKfyve inhibition triggered a distinct lipogenic gene expression and metabolic program, creating a dependency on de novo lipid metabolism pathways, by upregulating genes such as FASN and ACACA. In PDAC, the KRAS-MAPK signaling pathway is a primary driver of de novo lipid synthesis, specifically enhancing FASN and ACACA levels. Accordingly, the simultaneous targeting of PIKfyve and KRAS-MAPK resulted in the elimination of tumor burden in a syngeneic orthotopic model and tumor regression in a xenograft model of PDAC. Taken together, these studies suggest that disrupting lipid metabolism through PIKfyve inhibition induces synthetic lethality in conjunction with KRAS-MAPK-directed therapies for PDAC.

Lysosomes as coordinators of cellular catabolism, metabolic signalling and organ physiology

Every cell must satisfy basic requirements for nutrient sensing, utilization and recycling through macromolecular breakdown to coordinate programmes for growth, repair and stress adaptation. The lysosome orchestrates these key functions through the synchronised interplay between hydrolytic enzymes, nutrient transporters and signalling factors, which together enable metabolic coordination with other organelles and regulation of specific gene expression programmes. In this Review, we discuss recent findings on lysosome-dependent signalling pathways, focusing on how the lysosome senses nutrient availability through its physical and functional association with mechanistic target of rapamycin complex 1 (mTORC1) and how, in response, the microphthalmia/transcription factor E (MiT/TFE) transcription factors exert feedback regulation on lysosome biogenesis. We also highlight the emerging interactions of lysosomes with other organelles, which contribute to cellular homeostasis. Lastly, we discuss how lysosome dysfunction contributes to diverse disease pathologies and how inherited mutations that compromise lysosomal hydrolysis, transport or signalling components lead to multi-organ disorders with severe metabolic and neurological impact. A deeper comprehension of lysosomal composition and function, at both the cellular and organismal level, may uncover fundamental insights into human physiology and disease.

Alleviated NCOA4-mediated ferritinophagy protected RA FLSs from ferroptosis in lipopolysaccharide-induced inflammation under hypoxia

OBJECTIVE

Ferroptosis is a reactive oxygen species (ROS)- and iron-dependent form of non-apoptotic cell death process. Previous studies have demonstrated that ferroptosis participates in the development of inflammatory arthritis. However, the role of ferroptosis in rheumatoid arthritis (RA) inflammatory hypoxic joints remains unclear. This study sought to explore the underlying mechanism of ferroptosis on lipopolysaccharide (LPS)-induced RA fibroblast-like synoviocytes (FLSs).

METHODS

FLSs, isolated from patients with RA, were treated with LPS and ferroptosis inducer (erastin and RSL-3), and ferroptosis inhibitor (Fer-1 and DFO), respectively. The cell viability was measured by CCK-8. The cell death was detected by flow cytometer. The proteins level were tested by Western blot. The cytosolic ROS and lipid peroxidation were determined using DCFH-DA and C11-BODIPY581/591 fluorescence probes, respectively. The small interfering RNA (siRNA) was used to knock down related proteins. The levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), iron, inflammatory cytokines (IL6 and IL8), and LDH were analyzed by commercial kits.

RESULTS

Ferroptosis was activated by LPS in RA FLS with increased cellular damage, ROS and lipid peroxidation, intracellular Fe and IL8, which can be further amplified by ferroptosis inducer (erastin and RSL-3) and inhibited by ferroptosis inhibitor (Fer-1 and DFO). Mechanistically, LPS triggered ferroptosis via NCOA4-mediated ferritinophagy in RA FLSs, and knockdown of NCOA4 strikingly prevent the process of ferroptosis. Intriguingly, LPS-induced RA FLSs became insensitive to ferroptosis and NCOA4-mediated ferritinophagy under hypoxia compared with normoxia. Knockdown of HIF-1α reverted ferroptosis and ferritinophagy evoking by LPS-induced RA FLSs inflammation under hypoxia. In addition, low dose of auranofin (AUR) induced re-sensitization of ferroptosis and ferritinophagy through inhibiting the expression of HIF-1α under hypoxia.

CONCLUSIONS

NCOA4-mediated ferritinophagy was a key driver of ferroptosis in inflammatory RA FLSs. The suppression of NCOA4-mediated ferritinophagy protected RA FLSs from ferroptosis in LPS-induced inflammation under hypoxia. Targeting HIF-1α/NCOA4 and ferroptosis could be an effective and valuable therapeutic strategy for synovium hyperplasia in the patients with RA.

Ferroptosis and EMT resistance in cancer: a comprehensive review of the interplay

Ferroptosis differs from traditional cell death mechanisms like apoptosis, necrosis, and autophagy, primarily due to its reliance on iron metabolism and the loss of glutathione peroxidase activity, leading to lipid peroxidation and cell death. The dysregulation of iron metabolism is a hallmark of various cancers, contributing to tumor progression, metastasis, and notably, drug resistance. The acquisition of mesenchymal characteristics by epithelial cells is known as Epithelial-Mesenchymal Transition (EMT), a biological process intricately linked to cancer development, promoting traits such as invasiveness, metastasis, and resistance to therapeutic interventions. EMT plays a pivotal role in cancer progression and contributes significantly to the complex dynamics of carcinogenesis. Research findings indicate that mesenchymal cancer cells exhibit greater susceptibility to ferroptosis compared to their epithelial counterparts. The induction of ferroptosis becomes more effective in eliminating drug-resistant cancer cells during the process of EMT. The interplay between ferroptosis and EMT, a process where epithelial cells transform into mobile mesenchymal cells, is crucial in understanding cancer progression. EMT is associated with increased cancer metastasis and drug resistance. The review delves into how ferroptosis and EMT influence each other, highlighting the role of key proteins like GPX4, which protects against lipid peroxidation, and its inhibition can induce ferroptosis. Conversely, increased GPX4 expression is linked to heightened resistance to ferroptosis in cancer cells. Moreover, the review discusses the implications of EMT-induced transcription factors such as Snail, Zeb1, and Twist in modulating the sensitivity of tumor cells to ferroptosis, thereby affecting drug resistance and cancer treatment outcomes. Targeting the ferroptosis pathway offers a promising therapeutic strategy, particularly for tumors resistant to conventional treatments. The induction of ferroptosis in these cells could potentially overcome drug resistance. However, translating these findings into clinical practice presents challenges, including understanding the precise mechanisms of ferroptosis induction, identifying predictive biomarkers, and optimizing combination therapies. The review underscores the need for further research to unravel the complex interactions between ferroptosis, EMT, and drug resistance in cancer. This could lead to the development of more effective, targeted cancer treatments, particularly for drug-resistant tumors, offering new hope in cancer therapeutics.

Clinical Evaluation of the Pancreatic Cancer Microenvironment: Opportunities and Challenges

Advances in our understanding of pancreatic ductal adenocarcinoma (PDAC) and its tumor microenvironment (TME) have the potential to transform treatment for the hundreds of thousands of patients who are diagnosed each year. Whereas the clinical assessment of cancer cell genetics has grown increasingly sophisticated and personalized, current protocols to evaluate the TME have lagged, despite evidence that the TME can be heterogeneous within and between patients. Here, we outline current protocols for PDAC diagnosis and management, review novel biomarkers, and highlight potential opportunities and challenges when evaluating the PDAC TME as we prepare to translate emerging TME-directed therapies to the clinic.

Mechanisms controlling cellular and systemic iron homeostasis

In mammals, hundreds of proteins use iron in a multitude of cellular functions, including vital processes such as mitochondrial respiration, gene regulation and DNA synthesis or repair. Highly orchestrated regulatory systems control cellular and systemic iron fluxes ensuring sufficient iron delivery to target proteins is maintained, while limiting its potentially deleterious effects in iron-mediated oxidative cell damage and ferroptosis. In this Review, we discuss how cells acquire, traffick and export iron and how stored iron is mobilized for iron-sulfur cluster and haem biogenesis. Furthermore, we describe how these cellular processes are fine-tuned by the combination of various sensory and regulatory systems, such as the iron-regulatory protein (IRP)-iron-responsive element (IRE) network, the nuclear receptor co-activator 4 (NCOA4)-mediated ferritinophagy pathway, the prolyl hydroxylase domain (PHD)-hypoxia-inducible factor (HIF) axis or the nuclear factor erythroid 2-related factor 2 (NRF2) regulatory hub. We further describe how these pathways interact with systemic iron homeostasis control through the hepcidin-ferroportin axis to ensure appropriate iron fluxes. This knowledge is key for the identification of novel therapeutic opportunities to prevent diseases of cellular and/or systemic iron mismanagement.

Targeting ferroptosis and ferritinophagy: new targets for cardiovascular diseases

Cardiovascular diseases (CVDs) are a leading factor driving mortality worldwide. Iron, an essential trace mineral, is important in numerous biological processes, and its role in CVDs has raised broad discussion for decades. Iron-mediated cell death, namely ferroptosis, has attracted much attention due to its critical role in cardiomyocyte damage and CVDs. Furthermore, ferritinophagy is the upstream mechanism that induces ferroptosis, and is closely related to CVDs. This review aims to delineate the processes and mechanisms of ferroptosis and ferritinophagy, and the regulatory pathways and molecular targets involved in ferritinophagy, and to determine their roles in CVDs. Furthermore, we discuss the possibility of targeting ferritinophagy-induced ferroptosis modulators for treating CVDs. Collectively, this review offers some new insights into the pathology of CVDs and identifies possible therapeutic targets.

Ferritinophagy: research advance and clinical significance in cancers

Ferritinophagy, a process involving selective autophagy of ferritin facilitated by nuclear receptor coactivator 4 (NCOA4), entails the recognition of ferritin by NCOA4 and subsequent delivery to the autophagosome. Within the autophagosome, ferritin undergoes degradation, leading to the release of iron in the lysosome. It is worth noting that excessive iron levels can trigger cell death. Recent evidence has elucidated the significant roles played by ferritinophagy and ferroptosis in regulation the initiation and progression of cancer. Given the crucial role of ferritinophagy in tumor biology, it may serve as a potential target for future anti-tumor therapeutic interventions. In this study, we have provided the distinctive features of ferritinophagy and its distinctions from ferroptosis. Moreover, we have briefly examined the fundamental regulatory mechanisms of ferritinophagy, encompassing the involvement of the specific receptor NCOA4, the Nrf2/HO-1 signaling and other pathways. Subsequently, we have synthesized the current understanding of the impact of ferritinophagy on cancer progression and its potential therapeutic applications, with a particular emphasis on the utilization of chemotherapy, nanomaterials, and immunotherapy to target the ferritinophagy pathway for anti-tumor purposes.

Organic Selenium induces ferroptosis in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDA) cells reprogram both mitochondrial and lysosomal functions to support growth. At the same time, this causes significant dishomeostasis of free radicals. While this is compensated by the upregulation of detoxification mechanisms, it also represents a potential vulnerability. Here we demonstrate that PDA cells are sensitive to the inhibition of the mevalonate pathway (MVP), which supports the biosynthesis of critical antioxidant intermediates and protect from ferroptosis. We attacked the susceptibility of PDA cells to ferroptotic death with selenorganic compounds, including dibenzyl diselenide (DBDS) that exhibits potent pro-oxidant properties and inhibits tumor growth in vitro and in vivo. DBDS treatment induces the mobilization of iron from mitochondria enabling uncontrolled lipid peroxidation. Finally, we showed that DBDS and statins act synergistically to promote ferroptosis and provide evidence that combined treatment is a viable strategy to combat PDA.

New Perspectives on Circulating Ferritin: Its Role in Health and Disease

The diagnosis of iron disturbances usually includes the evaluation of serum parameters. Serum iron is assumed to be entirely bound to transferrin, and transferrin saturation-the ratio between the serum iron concentration and serum transferrin-usually reflects iron availability. Additionally, serum ferritin is commonly used as a surrogate of tissue iron levels. Low serum ferritin values are interpreted as a sign of iron deficiency, and high values are the main indicator of pathological iron overload. However, in situations of inflammation, serum ferritin levels may be very high, independently of tissue iron levels. This presents a particularly puzzling challenge for the clinician evaluating the overall iron status of the patient in the presence of an inflammatory condition. The increase in serum ferritin during inflammation is one of the enigmas regarding iron metabolism. Neither the origin, the mechanism of release, nor the effects of serum ferritin are known. The use of serum ferritin as a biomarker of disease has been rising, and it has become increasingly diverse, but whether or not it contributes to controlling the disease or host pathology, and how it would do it, are important, open questions. These will be discussed here, where we spotlight circulating ferritin and revise the recent clinical and preclinical data regarding its role in health and disease.

STING promotes ferroptosis through NCOA4-dependent ferritinophagy in acute kidney injury

Ferroptosis in tubules has been implicated in the pathogenesis of acute kidney injury (AKI), whereas the regulatory mechanism remains unclear. The stimulator of interferon genes (STING) is previously recognized as a critical mediator of innate immunity via a DNA-sensing pathway and has been increasingly linked to lipid peroxidation, a hallmark of ferroptosis. Herein we investigated the role and the underlying mechanism of STING in AKI models established by ischemia/reperfusion (IR) in C57BL mice. The expression level of STING was predominantly increased in tubules of kidney after IR treatment. Besides, STING deficiency markedly alleviated IR-induced lipid peroxidation, tissue damage and renal dysfunction. Consistently, in vitro experiments demonstrated that the increase in ferroptotic cell death, lipid ROS production and the decrease in GSH peroxidase 4 (GPX4) expression in renal tubular cells subjected to ferroptosis agonist or hypoxia/reoxygenation intervention were all mitigated by genetic deficiency or pharmacological inhibition of STING, while all exacerbated by STING overexpression. Further, these detrimental effects of STING overexpression relied on the induction of ferritinophagy, i.e. autophagic degradation of ferritin, leading to iron overload. Mechanistically, STING mediated the initiation of ferritinophagy through interacting with nuclear receptor coactivator 4 (NCOA4), a fundamental receptor for the transfer of ferritin into lysosome. Collectively, STING contributes to ferroptosis during ischemic AKI through facilitating NCOA4-mediated ferritinophagy and shows the potential as a promising therapeutic choice for AKI.

Genome, Metabolism, or Immunity: Which Is the Primary Decider of Pancreatic Cancer Fate through Non-Apoptotic Cell Death?

Pancreatic ductal adenocarcinoma (PDAC) is a solid tumor characterized by poor prognosis and resistance to treatment. Resistance to apoptosis, a cell death process, and anti-apoptotic mechanisms, are some of the hallmarks of cancer. Exploring non-apoptotic cell death mechanisms provides an opportunity to overcome apoptosis resistance in PDAC. Several recent studies evaluated ferroptosis, necroptosis, and pyroptosis as the non-apoptotic cell death processes in PDAC that play a crucial role in the prognosis and treatment of this disease. Ferroptosis, necroptosis, and pyroptosis play a crucial role in PDAC development via several signaling pathways, gene expression, and immunity regulation. This review summarizes the current understanding of how ferroptosis, necroptosis, and pyroptosis interact with signaling pathways, the genome, the immune system, the metabolism, and other factors in the prognosis and treatment of PDAC.

Autophagy: Regulator of cell death

Autophagy is the process by which cells degrade and recycle proteins and organelles to maintain intracellular homeostasis. Generally, autophagy plays a protective role in cells, but disruption of autophagy mechanisms or excessive autophagic flux usually leads to cell death. Despite recent progress in the study of the regulation and underlying molecular mechanisms of autophagy, numerous questions remain to be answered. How does autophagy regulate cell death? What are the fine-tuned regulatory mechanisms underlying autophagy-dependent cell death (ADCD) and autophagy-mediated cell death (AMCD)? In this article, we highlight the different roles of autophagy in cell death and discuss six of the main autophagy-related cell death modalities, with a focus on the metabolic changes caused by excessive endoplasmic reticulum-phagy (ER-phagy)-induced cell death and the role of mitophagy in autophagy-mediated ferroptosis. Finally, we discuss autophagy enhancement in the treatment of diseases and offer a new perspective based on the use of autophagy for different functional conversions (including the conversion of autophagy and that of different autophagy-mediated cell death modalities) for the clinical treatment of tumors.

The emerging role of ferroptosis in female reproductive disorders

Iron, as an essential trace element for the organism, is vital for maintaining the organism's health. Excessive iron can promote reactive oxygen species (ROS) accumulation, thus damaging cells and tissues. Ferroptosis is a novel form of programmed cell death distinguished by iron overload and lipid peroxidation, which is unique from autophagy, apoptosis and necrosis, more and more studies are focusing on ferroptosis. Recent evidence suggests that ferroptosis is associated with the development of female reproductive disorders (FRDs), including polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI), endometriosis (EMs), ovarian cancer (OC), preeclampsia (PE) and spontaneous abortion (SA). Pathways and genes associated with ferroptosis may participate in processes that regulate granulosa cell proliferation and secretion, oocyte development, ovarian reserve function, early embryonic development and placental oxidative stress. However, its exact mechanism has not been fully revealed. Therefore, our review systematically elaborates the occurrence mechanism of ferroptosis and its research progress in the development of FRDs, with a view to providing literature references for clinical targeting of ferroptosis -related pathways and regulatory factors for the management of FRDs.

Tumor microenvironmental nutrients, cellular responses, and cancer

Over the last two decades, the rapidly expanding field of tumor metabolism has enhanced our knowledge of the impact of nutrient availability on metabolic reprogramming in cancer. Apart from established roles in cancer cells themselves, various nutrients, metabolic enzymes, and stress responses are key to the activities of tumor microenvironmental immune, fibroblastic, endothelial, and other cell types that support malignant transformation. In this article, we review our current understanding of how nutrient availability affects metabolic pathways and responses in both cancer and "stromal" cells, by dissecting major examples and their regulation of cellular activity. Understanding the relationship of nutrient availability to cellular behaviors in the tumor ecosystem will broaden the horizon of exploiting novel therapeutic vulnerabilities in cancer.

Why Is Iron Deficiency/Anemia Linked to Alzheimer's Disease and Its Comorbidities, and How Is It Prevented?

Impaired iron metabolism has been increasingly observed in many diseases, but a deeper, mechanistic understanding of the cellular impact of altered iron metabolism is still lacking. In addition, deficits in neuronal energy metabolism due to reduced glucose import were described for Alzheimer's disease (AD) and its comorbidities like obesity, depression, cardiovascular disease, and type 2 diabetes mellitus. The aim of this review is to present the molecular link between both observations. Insufficient cellular glucose uptake triggers increased ferritin expression, leading to depletion of the cellular free iron pool and stabilization of the hypoxia-induced factor (HIF) 1α. This transcription factor induces the expression of the glucose transporters (Glut) 1 and 3 and shifts the cellular metabolism towards glycolysis. If this first line of defense is not adequate for sufficient glucose supply, further reduction of the intracellular iron pool affects the enzymes of the mitochondrial electron transport chain and activates the AMP-activated kinase (AMPK). This enzyme triggers the translocation of Glut4 to the plasma membrane as well as the autophagic recycling of cell components in order to mobilize energy resources. Moreover, AMPK activates the autophagic process of ferritinophagy, which provides free iron urgently needed as a cofactor for the synthesis of heme- and iron-sulfur proteins. Excessive activation of this pathway ends in ferroptosis, a special iron-dependent form of cell death, while hampered AMPK activation steadily reduces the iron pools, leading to hypoferremia with iron sequestration in the spleen and liver. Long-lasting iron depletion affects erythropoiesis and results in anemia of chronic disease, a common condition in patients with AD and its comorbidities. Instead of iron supplementation, drugs, diet, or phytochemicals that improve energy supply and cellular glucose uptake should be administered to counteract hypoferremia and anemia of chronic disease.

Identification of hepatocellular carcinoma-related subtypes and development of a prognostic model: a study based on ferritinophagy-related genes

BACKGROUND

Hepatocellular carcinoma still has a high incidence and mortality rate worldwide, and further research is needed to investigate its occurrence and development mechanisms in depth in order to identify new therapeutic targets. Ferritinophagy is a type of autophagy and a key factor in ferroptosis that could influence tumor onset and progression. Although, the potential role of ferritinophagy-related genes (FRGs) in liver hepatocellular carcinoma (LIHC) is unknown.

METHODS

Single-cell RNA sequencing (scRNA-seq) data of LIHC were obtained from the Gene Expression Omnibus (GEO) dataset. In addition, transcriptome and clinical follow-up outcome data of individuals with LIHC were extracted from the The Cancer Genome Atlas (TCGA) dataset. FRGs were collected through the GeneCards database. Differential cell subpopulations were distinguished, and differentially expressed FRGs (DEFRGs) were obtained. Differential expression of FRGs and prognosis were observed according to the TCGA database. An FRG-related risk model was constructed to predict patient prognosis by absolute shrinkage and selection operator (LASSO) and COX regression analyses, and its prognosis predictive power was validated. Ultimately, the association between risk score and tumor microenvironment (TME), immune cell infiltration, immune checkpoints, drug sensitivity, and tumor mutation burden (TMB) was analyzed. We also used quantitative reverse transcription polymerase chain reaction (qRT-PCR) to validate the expression of key genes in normal liver cells and liver cancer cells.

RESULTS

We ultimately identified 8 cell types, and 7 differentially expressed FRGs genes (ZFP36, NCOA4, FTH1, FTL, TNF, PCBP1, CYB561A3) were found among immune cells, and we found that Monocytes and Macrophages were closely related to FRGs genes. Subsequently, COX regression analysis showed that patients with high expression of FTH1, FTL, and PCBP1 had significantly worse prognosis than those with low expression, and our survival prediction model, constructed based on age, stage, and risk score, showed better prognostic prediction ability. Our risk model based on 3 FRGs genes ultimately revealed significant differences between high-risk and low-risk groups in terms of immune infiltration and immune checkpoint correlation, drug sensitivity, and somatic mutation risk. Finally, we validated the key prognostic genes FTH1, FTL, using qRT-PCR, and found that the expression of FTH1 and FTL was significantly higher in various liver cancer cells than in normal liver cells. At the same time, immunohistochemistry showed that the expression of FTH1, FTL in tumor tissues was significantly higher than that in para-tumor tissues.

CONCLUSION

This study identifies a considerable impact of FRGs on immunity and prognosis in individuals with LIHC. The collective findings of this research provide new ideas for personalized treatment of LIHC and a more targeted therapy approach for individuals with LIHC to improve their prognosis.

HIF2α, Hepcidin and their crosstalk as tumour-promoting signalling

Not all aspects of the disruption of iron homeostasis in cancer have been fully elucidated. Iron accumulation in cancer cells is frequent for many solid tumours, and this is often accompanied by the contemporary rise of two key iron regulators, HIF2α and Hepcidin. This scenario is different from what happens under physiological conditions, where Hepcidin parallels systemic iron concentrations while HIF2α levels are inversely associated to Hepcidin. The present review highlights the increasing body of evidence for the pro-tumoral effect of HIF2α and Hepcidin, discusses the possible imbalance in HIF2α, Hepcidin and iron homeostasis during cancer, and explores therapeutic options relying on these pathways as anticancer strategies.

A novel view of ferritin in cancer

Since its discovery more than 85 years ago, ferritin has principally been known as an iron storage protein. However, new roles, beyond iron storage, are being uncovered. Novel processes involving ferritin such as ferritinophagy and ferroptosis and as a cellular iron delivery protein not only expand our thinking on the range of contributions of this protein but present an opportunity to target these pathways in cancers. The key question we focus on within this review is whether ferritin modulation represents a useful approach for treating cancers. We discussed novel functions and processes of this protein in cancers. We are not limiting this review to cell intrinsic modulation of ferritin in cancers, but also focus on its utility in the trojan horse approach in cancer therapeutics. The novel functions of ferritin as discussed herein realize the multiple roles of ferritin in cell biology that can be probed for therapeutic opportunities and further research.

Targeting Iron-Sulfur Clusters in Cancer: Opportunities and Challenges for Ferroptosis-Based Therapy

Iron dysregulation is a hallmark of cancer, characterized by an overexpression of genes involved in iron metabolism and iron-sulfur cluster (ISC) biogenesis. Dysregulated iron homeostasis increases intracellular labile iron, which may lead to the formation of excess cytotoxic radicals and make it vulnerable to various types of regulated cell death, including ferroptosis. The inhibition of ISC synthesis triggers the iron starvation response, increasing lipid peroxidation and ferroptosis in cancer cells treated with oxidative stress-inducing agents. Various methods, such as redox operations, iron chelation, and iron replacement with redox-inert metals, can destabilize or limit ISC formation and function, providing potential therapeutic strategies for cancer treatment. Targeting ISCs to induce ferroptosis represents a promising approach in cancer therapy. This review summarizes the state-of-the-art overview of iron metabolism and ferroptosis in cancer cells, the role of ISC modulation in ferroptosis, and the potential of targeting ISCs for ferroptosis induction in cancer therapy. Further research is necessary to develop and validate these strategies in clinical trials for various cancers, which may ultimately lead to the development of novel and effective treatments for cancer patients.

Impact of context-dependent autophagy states on tumor progression

Macroautophagy is a cellular quality-control process that degrades proteins, protein aggregates and damaged organelles. Autophagy plays a fundamental role in cancer where, in the presence of stressors (for example, nutrient starvation, hypoxia, mechanical pressure), tumor cells activate it to degrade intracellular substrates and provide energy. Cell-autonomous autophagy in tumor cells and cell-nonautonomous autophagy in the tumor microenvironment and in the host converge on mechanisms that modulate metabolic fitness, DNA integrity and immune escape and, consequently, support tumor growth. In this Review, we will discuss insights into the tumor-modulating roles of autophagy in different contexts and reflect on how future studies using physiological culture systems may help to understand the complexity and open new therapeutic avenues.

Recent advances in targeting autophagy in cancer

Autophagy is a cellular homeostasis mechanism that fuels the proliferation and survival of advanced cancers by degrading and recycling organelles and proteins. Preclinical studies have identified that within an established tumor, tumor cell autophagy and host cell autophagy conspire to support tumor growth. A growing body of evidence suggests that autophagy inhibition can augment the efficacy of chemotherapy, targeted therapy, or immunotherapy to enhance tumor shrinkage. First-generation autophagy inhibition trials in cancer using the lysosomal inhibitor hydroxychloroquine (HCQ) have produced mixed results but have guided the way for the development of more potent and specific autophagy inhibitors in clinical trials. In this review, we will discuss the role of autophagy in cancer, newly discovered molecular mechanisms of the autophagy pathway, the effects of autophagy modulation in cancer and host cells, and novel autophagy inhibitors that are entering clinical trials.

Autophagy supports mitochondrial metabolism through the regulation of iron homeostasis in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) cells maintain a high level of autophagy, allowing them to thrive in an austere microenvironment. However, the processes through which autophagy promotes PDAC growth and survival are still not fully understood. Here, we show that autophagy inhibition in PDAC alters mitochondrial function by losing succinate dehydrogenase complex iron sulfur subunit B expression by limiting the availability of the labile iron pool. PDAC uses autophagy to maintain iron homeostasis, while other tumor types assessed require macropinocytosis, with autophagy being dispensable. We observed that cancer-associated fibroblasts can provide bioavailable iron to PDAC cells, promoting resistance to autophagy ablation. To overcome this cross-talk, we used a low-iron diet and demonstrated that this augmented the response to autophagy inhibition therapy in PDAC-bearing mice. Our work highlights a critical link between autophagy, iron metabolism, and mitochondrial function that may have implications for PDAC progression.

Ferritinophagy in the etiopathogenic mechanism of related diseases

Iron is an essential trace element that is involved in a variety of physiological processes. Ferritinophagy is selective autophagy mediated by nuclear receptor coactivator 4 (NCOA4), which regulates iron homeostasis in the body. Upon iron depletion or starvation, ferritinophagy is activated, releasing large amounts of Fe²⁺ and increasing reactive oxygen species (ROS), leading to ferroptosis. This plays a significant role in the etiopathogenesis of many diseases, such as metabolic diseases, neurodegenerative diseases, infectious diseases, tumors, cardiomyopathy, and ischemia-reperfusion ischemia-reperfusion injury. Here, we first review the regulation and functions of ferritinophagy and then describe its involvement in different diseases, with hopes of providing new understanding and insights into iron metabolism and iron disorder-related diseases and the therapeutic opportunity for targeting ferritinophagy.

Pancreatic cancer: Advances and challenges

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers. Significant efforts have largely defined major genetic factors driving PDAC pathogenesis and progression. Pancreatic tumors are characterized by a complex microenvironment that orchestrates metabolic alterations and supports a milieu of interactions among various cell types within this niche. In this review, we highlight the foundational studies that have driven our understanding of these processes. We further discuss the recent technological advances that continue to expand our understanding of PDAC complexity. We posit that the clinical translation of these research endeavors will enhance the currently dismal survival rate of this recalcitrant disease.

Oxygen modulates iron homeostasis by switching iron-sensing of NCOA4

To ensure proper utilization of iron and avoid its toxicity, cells are equipped with iron-sensing proteins to maintain cellular iron homeostasis. We showed previously that NCOA4, a ferritin-specific autophagy adapter, intricately regulates the fate of ferritin; upon binding to Fe³⁺, NCOA4 forms insoluble condensates and regulates ferritin autophagy in iron-replete conditions. Here, we demonstrate an additional iron-sensing mechanism of NCOA4. Our results indicate that the insertion of an Fe-S cluster enables preferential recognition of NCOA4 by the HERC2 ubiquitin ligase in iron-replete conditions, resulting in degradation by the proteasome and subsequent inhibition of ferritinophagy. We also found that both condensation and ubiquitin-mediated degradation of NCOA4 can occur in the same cell, and the cellular oxygen tension determines the selection of these pathways. Fe-S cluster-mediated degradation of NCOA4 is enhanced under hypoxia, whereas NCOA4 forms condensates and degrades ferritin at higher oxygen levels. Considering the involvement of iron in oxygen handling, our findings demonstrate that the NCOA4/ferritin axis is another layer of cellular iron regulation in response to oxygen levels.

A novel sesquiterpene lactone fraction from Eupatorium chinense L. suppresses hepatocellular carcinoma growth by triggering ferritinophagy and mitochondrial damage

BACKGROUND

Hepatocellular carcinoma (HCC) is an aggressive tumor with limited treatment options, and it is the third leading cause of cancer-related deaths. Hence, novel therapeutic strategies are required to treat HCC. Eupatorium chinense L. is a traditional Chinese medicine (TCM) that can effectively neutralize heat and smoothen the flow of "Qi" through the liver. However, the anti-HCC effects of Eupatorium chinense L. remain unknown.

PURPOSE

The present study investigated the anti-HCC effects and the underlying mechanisms of the electrophilic sesquiterpenes isolated from E. chinense L. (EChLESs) in the regulation of ferroptosis and apoptosis in HCC cells.

STUDY DESIGN/METHODS

Cell viability was assessed by the MTT assay. Cell apoptosis was confirmed by flow cytometry and western blotting assay. Ferroptosis was assessed by flow cytometry, transmission electron microscopy, and western blotting assay. Ferritinophagy was detected by acridine orange staining and western blotting assay. Small interfering RNA of nuclear receptor coactivator 4 (NCOA4) was used to confirm the role of ferritinophagy in the therapeutic effect of EChLESs on HCC cells. A mouse xenograft model was constructed to determine the inhibitory effect of EChLESs on HCC in vivo.

RESULTS

EChLESs induced apoptosis by disrupting mitochondrial membrane potential depolarization and mitochondrial reactive oxygen species. EChLESs induced ferroptosis as noted by a significant increase in mitochondrial disruption, lipid peroxidation, and intracellular iron level and decreased glutathione level. The apoptosis inhibitor Z-VAD-FMK and lipid reactive oxygen species scavenger ferrostatin 1 attenuated EChLESs-induced cell death. NCOA4-mediated ferritinophagy through autophagic flux was the crucial pathway for ferroptosis induced by EChLESs. NCOA4 knockdown alleviated EChLESs-induced cell death. EChLESs controlled the expression of NCOA4 at the transcriptional and post-transcriptional levels. In the in vivo experiment, EChLESs suppressed HCC growth in the xenograft tumor mouse model.

CONCLUSION

EChLESs enhances cell apoptosis through mitochondrial dysfunction and ferroptosis through NCOA4-mediated ferritinophagy. Thus, Eupatorium chinense L. could be a potential TCM for treating HCC.

Susceptibility of cervical cancer to dihydroartemisinin-induced ferritinophagy-dependent ferroptosis

The clinical therapeutics of cervical cancer is limited due to the drug resistance and metastasis of tumor. As a novel target for antitumor therapy, ferroptosis is deemed to be more susceptible for those cancer cells with resistance to apoptosis and chemotherapy. Dihydroartemisinin (DHA), the primary active metabolites of artemisinin and its derivatives, has exhibited a variety of anticancer properties with low toxicity. However, the role of DHA and ferroptosis in cervical cancer remained unclear. Here, we showed that DHA could time-dependently and dose-dependently inhibit the proliferation of cervical cancer cells, which could be alleviated by the inhibitors of ferroptosis rather than apoptosis. Further investigation confirmed that DHA treatment initiated ferroptosis, as evidenced by the accumulation of reactive oxygen species (ROS), malondialdehyde (MDA) and liquid peroxidation (LPO) levels and simultaneously depletion of glutathione peroxidase 4 (GPX4) and glutathione (GSH). Moreover, nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy was also induced by DHA leading to subsequent increases of intracellular labile iron pool (LIP), exacerbated the Fenton reaction resulting in excessive ROS production, and enhanced cervical cancer ferroptosis. Among them, we unexpectedly found that heme oxygenase-1 (HO-1) played an antioxidant role in DHA-induced cell death. In addition, the results of synergy analysis showed that the combination of DHA and doxorubicin (DOX) emerged a highly synergistic lethal effect for cervical cancer cells, which was related also to ferroptosis. Overall, our data revealed the molecular mechanisms that DHA triggered ferritinophagy-dependent ferroptosis and sensitized to DOX in cervical cancer, which may provide novel avenues for future therapy development.

β-Elemene enhances erlotinib sensitivity through induction of ferroptosis by upregulating lncRNA H19 in EGFR-mutant non-small cell lung cancer

Nearly half of all Asian non-small cell lung cancer (NSCLC) patients harbour epidermal growth factor receptor (EGFR) mutations, and first-generation EGFR tyrosine kinase inhibitors (TKIs) are one of the first-line treatments that have improved the outcomes of these patients. Unfortunately, 20% of these patients can not benefit from the treatment. The basis of this primary resistance is poorly understood. Therefore, overcoming EGFR-TKI primary resistance and maintaining the efficacy of TKIs has become a key issue. β-Elemene, a sesquiterpene compound extracted from Curcuma aromatica Salisb. (wenyujing), has shown potent antitumor effects. In this research, we found that β-elemene combined with erlotinib enhanced the cytotoxicity of erlotinib to primary EGFR-TKI-resistant NSCLC cells with EGFR mutations and that ferroptosis was involved in the antitumor effect of the combination treatment. We found that lncRNA H19 was significantly downregulated in primary EGFR-TKI-resistant NSCLC cell lines and was upregulated by the combination treatment. Overexpression or knockdown of H19 conferred sensitivity or resistance to erlotinib, respectively, in both in vitro and in vivo studies. The high level of H19 enhanced the cytotoxicity of erlotinib by inducing ferroptosis. In conclusion, our data showed that β-elemene combined with erlotinib could enhance sensitivity to EGFR-TKIs through induction of ferroptosis via H19 in primary EGFR-TKI-resistant lung cancer, providing a promising strategy to overcome EGFR-TKI resistance in NSCLC patients.

Autophagy-Dependent Ferroptosis in Cancer

Significance: Autophagy is a self-degrading process that determines cell fate in response to various environmental stresses. In contrast to autophagy-mediated cell survival, the signals, mechanisms, and effects of autophagy-dependent cell death remain obscure. The discovery of autophagy-dependent ferroptosis provides a paradigm for understanding the relationship between aberrant degradation pathways and excessive lipid peroxidation in driving regulated cell death. Recent Advances: Ferroptosis was originally described as an autophagy-independent and iron-mediated nonapoptotic cell death. Current studies reveal that the level of intracellular autophagy is positively correlated with ferroptosis sensitivity. Selective autophagic degradation of proteins (e.g., ferritin, SLC40A1, ARNTL, GPX4, and CDH2) or organelles (e.g., lipid droplets or mitochondria) promotes ferroptosis by inducing iron overload and/or lipid peroxidation. Several upstream autophagosome regulators (e.g., TMEM164), downstream autophagy receptors (e.g., HPCAL1), or danger signals (e.g., DCN) are selectively required for ferroptosis-related autophagy, but not for starvation-induced autophagy. The induction of autophagy-dependent ferroptosis is an effective approach to eliminate drug-resistant cancer cells. Critical Issues: How different organelles selectively activate autophagy to modulate ferroptosis sensitivity is not fully understood. Identifying direct protein effectors of ferroptotic cell death remains a challenge. Future Directions: Further understanding of the molecular mechanics and immune consequences of autophagy-dependent ferroptosis is critical for the development of precision antitumor therapies.