Ferroportin downregulation promotes cell proliferation by modulating the Nrf2-miR-17-5p axis in multiple myeloma

Enteromorpha prolifera polysaccharide-Fe (III) complex promotes intestinal development as a new iron supplement

Iron is a crucial micronutrient, and its deficiency can have detrimental effects on the health of infants. Dietary polysaccharide-iron (III) complexes (PICs) are promising for addressing iron deficiency due to their minimal adverse reactions and high iron absorption rate. This study aimed to investigate the effects of dietary Enteromorpha prolifera polysaccharide-Fe (III) complex (EP-Fe) on newborns, using 3-day weaned piglets as the iron-deficiency model. Results showed that EP-Fe improved iron levels and promoted intestinal development in piglets. Transcriptome sequencing revealed that EP-Fe increased the survival of intestinal epithelial cells under hypoxia by upregulating the expression of genes that promote the development of the vascular system. Additionally, EP-Fe enhanced the mucosal barrier functions by inhibiting myosin light chain kinase (MLCK)/phosphorylated myosin light chain (p-MLC) signaling pathway to increase the expression of intestinal tight junction proteins. Furthermore, the 16S rRNA gene sequencing of gut microbiota showed that EP-Fe promoted the enrichment of Bacteroides_fragilis and other gut microbes that can metabolize carbohydrates. In conclusion, EP-Fe is an effective iron supplement for newborns, and it can be developed as a comprehensive nutritional supplement.

Defective ferritinophagy and imbalanced iron metabolism in PBDE-47-triggered neuronal ferroptosis and salvage by Canolol

The brominated flame retardant 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) is a ubiquitous environmental pollutant that causes neurotoxicity. However, incomplete understanding of the underlying mechanisms has hampered the development of effective intervention strategies. Oxidative stress and related cell death are the modes of action for PBDE-47 neurotoxicity, which are also the characteristics of ferroptosis. Nonetheless, the role of ferroptosis in PBDE-47-induced neurotoxicity remains unclear. In the present study, we found that PBDE-47 triggered ferroptosis in neuron-like PC12 cells, as evidenced by intracellular iron overload, lipid peroxidation, and mitochondrial damage. This was confirmed by ferroptosis inhibitors including the lipid reactive oxygen species scavenger ferrostatin-1 and iron chelator deferoxamine mesylate. Mechanistically, PBDE-47 impaired ferritinophagy by disrupting nuclear receptor coactivator 4-mediated lysosomal degradation of the iron storage protein ferritin. Moreover, PBDE-47 disturbed iron metabolism by increasing cellular iron import via upregulation of transferrin receptor 1 and decreasing cellular iron export via downregulation of ferroportin 1 (FPN1). Intriguingly, rescuing lysosomal function by overexpressing cathepsin B (CatB) mitigated PBDE-47-induced ferroptosis by partially restoring dysfunctional ferritinophagy and enhancing iron excretion via the upregulation of FPN1. However, FPN1 knockdown reversed the beneficial effects of CatB overexpression on the PBDE-47-induced iron overload. Finally, network pharmacology integrated with experimental validation revealed that Canolol, the main phenolic compound in canola oil, protected against PBDE-47-evoked iron overload, resulting in ferroptosis by restoring defective ferritinophagy and improving abnormal iron metabolism via lowering iron uptake and facilitating iron excretion. Overall, these data suggest that ferroptosis is a novel mechanism of PBDE-47-induced neuronal death and that manipulation of ferritinophagy and iron metabolism via Canolol represents a promising therapeutic strategy.

The interplay between microRNAs and Nrf2 signaling in human cancers

MicroRNAs (miRNAs), as a class of nonprotein-coding RNAs, post-transcriptionally regulate the expression of target genes by base pairing to 3'-untranslated regions (3'-UTRs). Nuclear factor E2-related factor 2 (Nrf2) has been identified as a critical component of the antioxidant defense mechanism. Dysregulation is associated with chemoresistance and radioresistance in cancerous cells. MiRNA-mediated regulation of the Nrf2 signaling pathway has been shown to have important implications for the development of various cancers. In this article, we review the roles of miRNAs as regulators of the Nrf2 pathway in different human cancers. Ras-associated binding (Rab) proteins have an essential role regulation of vesicle transport, as well as oncogenic functions in preventing chemotherapy efficacy and cancer development. More importantly, increased evidence indicated that the interaction between miRNAs and Rabs has been determined to play critical roles in cancer therapy. However, the significant limitations in using miRNAs for therapeutic applications include cross-targeting and instability of miRNAs. The detailed aspect of the interaction of miRNAs and Rabs is not clearly understood. In the current review, we highlighted the involvement of these molecules as regulators of the Nrf2 pathway in cancer pathogenesis. Potential methods and several obstacles in developing miRNAs as an anticancer therapy are also mentioned.

A guide to ferroptosis, the biological rust of cellular membranes

Unprotected iron can rust due to oxygen exposure. Similarly, in our body, oxidative stress can kill cells in an iron-dependent manner, which can give rise to devastating diseases. This type of cell death is referred to as ferroptosis. Generally, ferroptosis is defined as an iron-catalyzed form of regulated necrosis that occurs through excessive peroxidation of polyunsaturated fatty acids within cellular membranes. This review summarizes how ferroptosis is executed by a rather primitive biochemical process, under tight regulation of lipid, iron, and redox metabolic processes. An overview is given of major classes of ferroptosis inducers and inhibitors, and how to detect ferroptosis. Finally, its detrimental role in disease is briefly discussed.

microRNAs, oxidative stress, and genotoxicity as the main inducers in the pathobiology of cancer development

Cancer is one of the most serious leading causes of death in the world. Many eclectic factors are involved in cancer progression including genetic and epigenetic alongside environmental ones. In this account, the performance and fluctuations of microRNAs are significant in cancer diagnosis and treatment, particularly as diagnostic biomarkers in oncology. So, microRNAs manage and control the gene expression after transcription by mRNA degradation, or also they can inhibit their translation. Conspicuously, these molecular structures take part in controlling the cellular, physiological and pathological functions, which many of them can accomplish as tumor inhibitors or oncogenes. Relatively, Oxidative stress is defined as the inequality between the creation of reactive oxygen species (ROS) and the body's ability to detoxify the reactive mediators or repair the resulting injury. ROS and microRNAs have been recognized as main cancer promoters and possible treatment targets. Importantly, genotoxicity has been established as the primary reason for many diseases as well as several malignancies. The procedures have no obvious link with mutagenicity and influence the organization, accuracy of the information, or fragmentation of DNA. Conclusively, mutations in these patterns can lead to carcinogenesis. In this review article, we report the impressive and practical roles of microRNAs, oxidative stress, and genotoxicity in the pathobiology of cancer development in conjunction with their importance as reliable cancer biomarkers and their association with circulating miRNA, exosomes and exosomal miRNAs, RNA remodeling, DNA methylation, and other molecular elements in oncology.

NRF2 activation ameliorates blood-brain barrier injury after cerebral ischemic stroke by regulating ferroptosis and inflammation

Arterial occlusion-induced ischemic stroke (IS) is a highly frequent stroke subtype. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that modulates antioxidant genes. Its role in IS is still unelucidated. The current study focused on constructing a transient middle cerebral artery occlusion (tMCAO) model for investigating the NRF2-related mechanism underlying cerebral ischemia/reperfusion (I/R) injury. Each male C57BL/6 mouse was injected with/with no specific NRF2 activator post-tMCAO. Changes in blood-brain barrier (BBB)-associated molecule levels were analyzed using western-blotting, PCR, immunohistochemistry, and immunofluorescence analysis. NRF2 levels within cerebral I/R model decreased at 24-h post-ischemia. NRF2 activation improved brain edema, infarct volume, and neurological deficits after MCAO/R. Similarly, sulforaphane (SFN) prevented the down-regulated tight junction proteins occludin and zonula occludens 1 (ZO-1) and reduced the up-regulated aquaporin 4 (AQP4) and matrix metalloproteinase 9 (MMP9) after tMCAO. Collectively, NRF2 exerted a critical effect on preserving BBB integrity modulating ferroptosis and inflammation. Because NRF2 is related to BBB injury regulation following cerebral I/R, this provides a potential therapeutic target and throws light on the underlying mechanism for clinically treating IS.

Intracellular Regulation Limits the Response of Intestinal Ferroportin to Iron Status in Suckling Rats

SCOPE

Iron status is regulated via iron absorption as there is no active iron excretion. Divalent metal-ion transporter-1 (DMT1) and ferroportin (FPN) are two key proteins vital for iron absorption, but the regulation of them in suckling mammals differs from that in adults. This study aims to explore regulation of iron transporters under different iron conditions during suckling.

METHODS AND RESULTS

This study developed suckling rats under different iron conditions. Unexpectedly, unchanged FPN at different iron status are detected. Since FPN is the only known iron exporter for mammals, unchanged FPN limits iron exported into blood during suckling. Thus, factors regulating FPN at transcriptional, post-transcriptional, and post-translational levels are detected. Results showed that Fpn mRNA is upregulated, while micro RNA-485(miR-485) which could silence Fpn mRNA is upregulated at low iron status limiting translation of Fpn mRNA. Besides, serum hepcidin and liver Hamp mRNA are upregulated, but ring finger protein 217( Rnf217) mRNA remained unchanged at high iron status leading to FPN not downregulated as adults.

CONCLUSIONS

Overall, this study indicates that translational regulation limits intestinal FPN protein response to iron deficiency and Rnf217 cannot effectively mediate the degradation of FPN at high iron status, which provides a reference for maintaining iron homeostasis during suckling.

The interplay of miRNAs and ferroptosis in diseases related to iron overload

Ferroptosis has been conceptualized as a novel cell death modality distinct from apoptosis, necroptosis, pyroptosis and autophagic cell death. The sensitivity of cellular ferroptosis is regulated at multiple layers, including polyunsaturated fatty acid metabolism, glutathione-GPX4 axis, iron homeostasis, mitochondria and other parallel pathways. In addition, microRNAs (miRNAs) have been implicated in modulating ferroptosis susceptibility through targeting different players involved in the execution or avoidance of ferroptosis. A growing body of evidence pinpoints the deregulation of miRNA-regulated ferroptosis as a critical factor in the development and progression of various pathophysiological conditions related to iron overload. The revelation of mechanisms of miRNA-dependent ferroptosis provides novel insights into the etiology of diseases and offers opportunities for therapeutic intervention. In this review, we discuss the interplay of emerging miRNA regulators and ferroptosis players under different pathological conditions, such as cancers, ischemia/reperfusion, neurodegenerative diseases, acute kidney injury and cardiomyopathy. We emphasize on the relevance of miRNA-regulated ferroptosis to disease progression and the targetability for therapeutic interventions.

SRRM2 may be a potential biomarker and immunotherapy target for multiple myeloma: a real-world study based on flow cytometry detection

Serine/arginine repetitive matrix 2 (SRRM2) has been implicated in tumorigenesis, cancer development, and drug resistance through aberrant splicing; however, its correlation with multiple myeloma (MM) has not been reported. We investigated the potential of SRRM2 as a biomarker and immunotherapeutic target in MM by examining its expression in MM cells using flow cytometry. Our study included 95 patients with plasma cell disease, including 80 MM cases, and we detected SRRM2 expression on plasma cells and normal blood cells to analyze its relationship with clinical profiles. We found widespread positive expression of SRRM2 on plasma cells with little expression on normal blood cells, and its expression on abnormal plasma cells was higher than that on normal plasma cells. Comparative analysis with clinical data suggests that SRRM2 expression on plasma cells correlates with MM treatment response. MM patients with high SRRM2 expression had higher levels of serum β2-mg and LDH, ISS staging, and plasma cell infiltration, as well as high-risk mSMART 3.0 stratification and cytogenetic abnormalities, particularly 1q21 amplification. In patients with previous MM, high SRRM2 expression on plasma cells was associated with higher plasma cell infiltration, high-risk mSMART 3.0 risk stratification, cytogenetic abnormalities, more relapses, and fewer autologous stem cell transplant treatments. In summary, SRRM2 may serve as a novel biomarker and immunotherapeutic target for MM. Its expression level on plasma cells can help in risk stratification of MM and monitoring of treatment response.

Modulation of ferroptosis by non‑coding RNAs in cancers: Potential biomarkers for cancer diagnose and therapy

Ferroptosis is a recently discovered cell programmed death. Extensive researches have indicated that ferroptosis plays an essential role in tumorigenesis, development, migration and chemotherapy drugs resistance, which makes it become a new target for tumor therapy. Non-coding RNAs (ncRNAs) are considered to control a wide range of cellular processes by modulating gene expression. Recent studies have indicated that ncRNAs regulate the process of ferroptosis via various pathway to affect the development of cancer. However, the regulation network remains ambiguous. In this review, we outlined the major metabolic processes of ferroptosis and concluded the relationship between ferroptosis-related ncRNAs and cancer progression. In addition, the prospect of ncRNAs being new therapeutic targets and early diagnosis biomarkers for cancer by regulating ferroptosis were presented, and the possible obstacles were also predicted. This could help in discovering novel cancer early diagnostic methods and therapeutic approaches.

Lipocalin-2: A Nurturer of Tumor Progression and a Novel Candidate for Targeted Cancer Therapy

Within the tumor microenvironment (TME) exists a complex signaling network between cancer cells and stromal cells, which determines the fate of tumor progression. Hence, interfering with this signaling network forms the basis for cancer therapy. Yet, many types of cancer, in particular, solid tumors, are refractory to the currently used treatments, so there is an urgent need for novel molecular targets that could improve current anti-cancer therapeutic strategies. Lipocalin-2 (Lcn-2), a secreted siderophore-binding glycoprotein that regulates iron homeostasis, is highly upregulated in various cancer types. Due to its pleiotropic role in the crosstalk between cancer cells and stromal cells, favoring tumor progression, it could be considered as a novel biomarker for prognostic and therapeutic purposes. However, the exact signaling route by which Lcn-2 promotes tumorigenesis remains unknown, and Lcn-2-targeting moieties are largely uninvestigated. This review will (i) provide an overview on the role of Lcn-2 in orchestrating the TME at the level of iron homeostasis, macrophage polarization, extracellular matrix remodeling, and cell migration and survival, and (ii) discuss the potential of Lcn-2 as a promising novel drug target that should be pursued in future translational research.

Microglia-derived exosomal circZNRF1 alleviates paraquat-induced neuronal cell damage via miR-17-5p

Paraquat (PQ) is an environmental poison that causes clinical symptoms similar to those of Parkinson's disease (PD) in vitro and in rodents. It can lead to the activation of microglia and apoptosis of dopaminergic neurons. However, the exact role and mechanism of microglial activation in PQ-induced neuronal degeneration remain unknown. Here, we isolated the microglia-derived exosomes exposed with 0 and 40 μM PQ, which were subsequently co-incubated with PQ-exposed neuronal cells to simulate intercellular communication. First, we found that exosomes released from microglia caused a change in neuronal cell vitality and reversed PQ-induced neuronal apoptosis. RNA sequencing data showed that these activated microglia-derived exosomes carried large amounts of circZNRF1. Moreover, a bioinformatics method was used to study the underlying mechanism of circZNRF1 in regulating PD, and miR-17-5p was predicted to be its target. Second, an increased Bcl2/Bax ratio could play an anti-apoptotic role. Bcl2 was predicted to be a downstream target of miR-17-5p. Our results showed that circZNRF1 plays an anti-apoptotic role by absorbing miR-17-5p and regulating the binding of Bcl2 after exosomes are internalized by dopaminergic neurons. In conclusion, we demonstrated a new intercellular communication mechanism between microglia and neurons, in which circZNRF1 plays a key role in protecting against PQ-induced neuronal apoptosis through miR-17-5p to regulate the biological process of PD. These findings may offer a novel approach to preventing and treating PD.

Noncoding RNAs in cancer ferroptosis: From biology to clinical opportunity

Ferroptosis is a recently discovered pattern of programmed cell death that is nonapoptotic and irondependent. It is involved in lipid peroxidation dependent on reactive oxygen species. Ferroptosis has been verified to play a crucial regulatory role in a variety of pathological courses of disease, in particularly cancer. Emerging research has highlighted the potential of ferroptosis in tumorigenesis, cancer development and resistance to chemotherapy. However, the regulatory mechanism of ferroptosis remains unclear, which limits the application of ferroptosis in cancer treatment. Noncoding RNAs (ncRNAs) are noncoding transcripts that regulate gene expression in various ways to affect the malignant phenotypes of cancer cells. At present, the biological function and underlying regulatory mechanism of ncRNAs in cancer ferroptosis have been partially elucidated. Herein, we summarize the current knowledge of the central regulatory network of ferroptosis, with a focus on the regulatory functions of ncRNAs in cancer ferroptosis. The clinical application and prospects of ferroptosis-related ncRNAs in cancer diagnosis, prognosis and anticancer therapies are also discussed. Elucidating the function and mechanism of ncRNAs in ferroptosis, along with assessing the clinical significance of ferroptosis-related ncRNAs, provides new perspectives for understanding cancer biology and treatment approaches, which may benefit numerous cancer patients in the future.

Cyclovirobuxine D pretreatment ameliorates septic heart injury through mitigation of ferroptosis

Myocardial dysfunction is a frequent complication in patients with severe sepsis. However, effective drugs for the prevention of myocardial dysfunction and the molecular mechanisms of the disease remain elusive. The present study demonstrated that Cyclovirobuxine D (CVB-D) could improve cardiac dysfunction in a cecal ligation and puncture (CLP) model in rodents and in a lipopolysaccharide (LPS) model in vitro. Echocardiography and histopathological examination were used to detect changes in cardiac structure and function. Kits were used to detect indicators of cardiac injury, transmission electron microscopy to detect structural changes in mitochondria and reverse transcription-quantitative PCR to detect prostaglandin-endoperoxide synthase 2 and hamp expression levels. L-Glutathione and malondialdehyde levels and superoxide dismutase activity were measured using kits. Cell viability was measured with the Cell Counting Kit-8. Iron metabolism-related proteins, inflammatory factor levels and related pathway proteins were detected using western blot analysis. Changes in L-type calcium currents were detected by membrane clamp, and contractility of cardiomyocytes was measured by Ion Optix. CVB-D attenuated CLP-induced cardiac malfunction in septic rats, with changes observed in myocardial pathological structure, creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI). CVB-D attenuated sepsis-induced lipid peroxidation and iron overload. In addition, CVB-D decreased the expression of CK-MB, LDH and cTnI, suppressed oxidative stress index levels and reduced the production of reactive oxygen species. CVB-D decreased LPS-induced cytoplasmic iron overload by increasing upregulation of iron uptake molecules. Conversely, CVB-D significantly increased the upregulation of ferroportin 1. CVB-D pretreatment significantly reduced the levels of hamp mRNA compared with the LPS-treated group. CVB-D pretreatment significantly reduced inflammatory factor levels and the ratio of phosphorylated vs. total signal transducer and activator of transcription 3. The expression of SLC7A11 and GPX4 was upregulated in septic cells pretreated with CVB-D, however treatment with ML385 largely decreased this upregulation. Of note, CVB-D inhibited the inward flow of calcium ions through the LTCC. In conclusion, these findings suggest that CVB-D alleviated sepsis-induced cardiac iron toxicity by alleviating iron metabolism.

Ferroportin1 in the brain

Despite years of research, it remains unclear why certain brain regions of patients with neurodegenerative diseases (NDs) have abnormally high levels of iron, although it has long been suggested that disrupted expression of iron-metabolizing proteins due to genetic or non-genetic factors is responsible for the enhancement in brain iron contents. In addition to the increased expression of cell-iron importers lactoferrin (lactotransferrin) receptor (LfR) in Parkinson's disease (PD) and melanotransferrin (p97) in Alzheimer's disease (AD), some investigations have suggested that cell-iron exporter ferroportin 1 (Fpn1) may be also associated with the elevated iron observed in the brain. The decreased expression of Fpn1 and the resulting decrease in the amount of iron excreted from brain cells has been thought to be able to enhance iron levels in the brain in AD, PD and other NDs. Cumulative results also suggest that the reduction of Fpn1 can be induced by hepcidin-dependent and -independent pathways. In this article, we discuss the current understanding of Fpn1 expression in the brain and cell lines of rats, mice and humans, with emphasis on the potential involvement of reduced Fpn1 in brain iron enhancement in patients with AD, PD and other NDs.

Emerging roles of ferroptosis-related miRNAs in tumor metastasis

Ferroptosis, a novel mode of cell death dependent on iron and reactive oxygen species, has been extensively explored during malignant tumors metastasis. Ferroptosis can interact with multiple components of the tumor microenvironment to regulate metastasis. These interactions generally include the following aspects: (1) Epithelial-mesenchymal transformation, which can help cancer cells increase their sensitivity to ferroptosis while they have multiple mechanisms to fight against it; (2) Disorder of iron metabolism in cancer stem cells which maintains their stem characteristics; (3) Polarization of M0 macrophages to M2. (4) The paradoxical effects of iron metabolism and CD8 + T cells induced by ferroptosis (5) Regulation of angiogenesis. In addition, ferroptosis can be regulated by miRNAs through the reprogramming of various intracellular metabolism processes, including the regulation of the glutathione- glutathione peroxidase 4 pathway, glutamic acid/cystine transport, iron metabolism, lipid metabolism, and oxidative stress. Therefore, there are many potential interactions between ferroptosis-related miRNAs and tumor metastasis, including interaction with cancer cells and immune cells, regulating cytokines, and angiogenesis. This review focuses on the role of ferroptosis-related miRNA in tumor metastasis, aiming to help readers understand their relationship and provide a new perspective on the potential treatment strategies of malignant tumors.

Anti-Ferroptotic Effects of Nrf2: Beyond the Antioxidant Response

The transcription factor Nrf2 was originally identified as a master regulator of redox homeostasis, as it governs the expression of a battery of genes involved in mitigating oxidative and electrophilic stress. However, the central role of Nrf2 in dictating multiple facets of the cellular stress response has defined the Nrf2 pathway as a general mediator of cell survival. Recent studies have indicated that Nrf2 regulates the expression of genes controlling ferroptosis, an ironand lipid peroxidation-dependent form of cell death. While Nrf2 was initially thought to have anti-ferroptotic function primarily through regulation of the antioxidant response, accumulating evidence has indicated that Nrf2 also exerts anti-ferroptotic effects via regulation of key aspects of iron and lipid metabolism. In this review, we will explore the emerging role of Nrf2 in mediating iron homeostasis and lipid peroxidation, where several Nrf2 target genes have been identified that encode critical proteins involved in these pathways. A better understanding of the mechanistic relationship between Nrf2 and ferroptosis, including how genetic and/or pharmacological manipulation of Nrf2 affect the ferroptotic response, should facilitate the development of new therapies that can be used to treat ferroptosis-associated diseases.

Ferroportin depletes iron needed for cell cycle progression in head and neck squamous cell carcinoma

Introduction

Ferroportin (FPN), the only identified eukaryotic iron efflux channel, plays an important role in iron homeostasis and is downregulated in many cancers. To determine if iron related pathways are important for Head and Neck Squamous Cell Carcinoma (HNSCC) progression and proliferation, we utilize a model of FPN over-expression to simulate iron depletion and probe associated molecular pathways.

Methods

The state of iron related proteins and ferroptosis sensitivity was assessed in a panel of metastatic HNSCC cell lines. Stable, inducible expression of FPN was confirmed in the metastatic HNSCC lines HN12 and JHU-022 as well as the non-transformed normal oral keratinocyte (NOK) cell line and the effect of FPN mediated iron depletion was assessed in these cell lines.

Results

HNSCC cells are sensitive to iron chelation and ferroptosis, but the non-transformed NOK cell line is not. We found that FPN expression inhibits HNSCC cell proliferation and colony formation but NOK cells are unaffected. Inhibition of cell proliferation is rescued by the addition of hepcidin. Decreases in proliferation are due to the disruption of iron homeostasis via loss of labile iron caused by elevated FPN levels. This in turn protects HNSCC cells from ferroptotic cell death. Expression of FPN induces DNA damage, activates p21, and reduces levels of cyclin proteins thereby inhibiting cell cycle progression of HNSCC cells, arresting cells in the S-phase. Induction of FPN severely inhibits Edu incorporation and increased β-galactosidase activity, indicating cells have entered senescence. Finally, in an oral orthotopic mouse xenograft model, FPN induction yields a significant decrease in tumor growth.

Conclusions

Our results indicate that iron plays a role in HNSCC cell proliferation and growth and is important for cell cycle progression. Iron based interventional strategies such as ferroptosis or iron chelation may have potential therapeutic benefits in advanced HNSCC.

Emerging role of miRNAs in the regulation of ferroptosis

Ferroptosis is a kind of cell death which has distinctive features differentiating it from autophagy, necrosis and apoptosis. This iron-dependent form of cell death is described by an increase in lipid reactive oxygen species, shrinkage of mitochondria and decrease in mitochondrial cristae. Ferroptosis is involved in the initiation and progression of many diseases and is regarded as a hotspot of investigations on treatment of disorders. Recent studies have shown that microRNAs partake in the regulation of ferroptosis. The impact of microRNAs on this process has been verified in different cancers as well as intervertebral disc degeneration, acute myocardial infarction, vascular disease, intracerebral hemorrhage, preeclampsia, hemorrhagic stroke, atrial fibrillation, pulmonary fibrosis and atherosclerosis. miR-675, miR-93, miR-27a, miR-34a and miR-141 have been shown to affect iron metabolism, antioxidant metabolism and lipid metabolism, thus influencing all pivotal mechanisms in the ferroptosis process. In the current review, we summarize the role of microRNAs in ferroptosis and their involvement in the pathetiology of malignant and non-malignant disorders.

Expression of hub genes of endothelial cells in glioblastoma-A prognostic model for GBM patients integrating single-cell RNA sequencing and bulk RNA sequencing

BACKGROUND

This study aimed to use single-cell RNA-seq (scRNA-seq) to discover marker genes in endothelial cells (ECs) and construct a prognostic model for glioblastoma multiforme (GBM) patients in combination with traditional high-throughput RNA sequencing (bulk RNA-seq).

METHODS

Bulk RNA-seq data was downloaded from The Cancer Genome Atlas (TCGA) and The China Glioma Genome Atlas (CGGA) databases. 10x scRNA-seq data for GBM were obtained from the Gene Expression Omnibus (GEO) database. The uniform manifold approximation and projection (UMAP) were used for downscaling and cluster identification. Key modules and differentially expressed genes (DEGs) were identified by weighted gene correlation network analysis (WGCNA). A non-negative matrix decomposition (NMF) algorithm was used to identify the different subtypes based on DEGs, and multivariate cox regression analysis to model the prognosis. Finally, differences in mutational landscape, immune cell abundance, immune checkpoint inhibitors (ICIs)-associated genes, immunotherapy effects, and enriched pathways were investigated between different risk groups.

RESULTS

The analysis of scRNA-seq data from eight samples revealed 13 clusters and four cell types. After applying Fisher's exact test, ECs were identified as the most important cell type. The NMF algorithm identified two clusters with different prognostic and immunological features based on DEGs. We finally built a prognostic model based on the expression levels of four key genes. Higher risk scores were significantly associated with poorer survival outcomes, low mutation rates in IDH genes, and upregulation of immune checkpoints such as PD-L1 and CD276.

CONCLUSION

We built and validated a 4-gene signature for GBM using 10 scRNA-seq and bulk RNA-seq data in this work.

Role of microRNAs in B-Cell Compartment: Development, Proliferation and Hematological Diseases

B-cell development is a very orchestrated pathway that involves several molecules, such as transcription factors, cytokines, microRNAs, and also different cells. All these components maintain the ideal microenvironment and control B-cell differentiation. MicroRNAs are small non-coding RNAs that bind to target mRNA to control gene expression. These molecules could circulate in the body in a free form, protein-bounded, or encapsulated into extracellular vesicles, such as exosomes. The comprehension of the role of microRNAs in the B-cell development was possible based on microRNA profile of each B-cell stage and functional studies. Herein, we report the knowledge about microRNAs in the B-cell the differentiation, proliferation, and also in hematological malignancies.

Sensitivity and specificity of microRNA-204, CA125, and CA19.9 as biomarkers for diagnosis of ovarian cancer

Background

Ovarian cancer is usually detected at later stages and no effective screening approach, has been identified. Therefore, sensitive and specific biomarkers for detecting ovarian cancer are urgently needed.

Objective

This study aimed to investigate the efficacy of six biomarkers for the early clinical diagnosis of ovarian cancer.

Subjects & methods

The study included 120 patients (benign ovarian tumors and early and late ovarian carcinoma) and 30 control healthy volunteers. MiRNA-204, CA125, CA19.9, hepcidin, microfibril-associated glycoprotein 2, and ferroportin levels were determined in all patients and control volunteers.

Results

The combined area under the receiver operating characteristic curves for miRNA-204, CA125, and CA19.9 were 0.938, 1.000, and 0.998 for benign tumors and early and late ovarian carcinomas, respectively. The sensitivities of miRNA-204, CA125, and CA19.9 were 98.04%, 100.00%, and 96.19% and the specificities were 58.33%, 62.50%, and 57.78%, respectively.

Conclusion

The positive predictivity of miRNA-204, CA125, and CA19.9 for ovarian cancer is high (59.57%, 58.24%, and 61.67%, respectively). Thus, the combination of these three biomarkers is a good diagnostic tool for ovarian cancer.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

Regulation of VEGFA, KRAS, and NFE2L2 Oncogenes by MicroRNAs in Head and Neck Cancer

Mutations and alterations in the expression of VEGFA, KRAS, and NFE2L2 oncogenes play a key role in cancer initiation and progression. These genes are enrolled not only in cell proliferation control, but also in angiogenesis, drug resistance, metastasis, and survival of tumor cells. MicroRNAs (miRNAs) are small, non-coding regulatory RNA molecules that can regulate post-transcriptional expression of multiple target genes. We aimed to investigate if miRNAs hsa-miR-17-5p, hsa-miR-140-5p, and hsa-miR-874-3p could interfere in VEGFA, KRAS, and NFE2L2 expression in cell lines derived from head and neck cancer (HNC). FADU (pharyngeal cancer) and HN13 (oral cavity cancer) cell lines were transfected with miR-17-5p, miR-140-5p, and miR-874-3p microRNA mimics. RNA and protein expression analyses revealed that miR-17-5p, miR-140-5p and miR-874-3p overexpression led to a downregulation of VEGFA, KRAS, and NFE2L2 gene expression in both cell lines analyzed. Taken together, our results provide evidence for the establishment of new biomarkers in the diagnosis and treatment of HNC.

A small molecule redistributes iron in ferroportin-deficient mice and patient-derived primary macrophages

Iron misdistribution underlies various diseases, ranging from anemia to neurodegeneration, but approaches to addressing this general problem are lacking. We recently reported that a small molecule natural product, hinokitiol, is capable of restoring hemoglobinization in various animal models with missing iron transporters. We now show that hinokitiol is capable of redistributing iron systemically, which in turn restores iron homeostasis in ferroportin-deficient mice and in primary macrophages derived from patients with ferroportin disease. We also elucidated the stepwise mechanism of hinokitiol-mediated iron redistribution and physiological restoration. Together, these results provide foundational support for using a molecular prosthetics approach for better understanding and possibly treating iron misdistribution.

Deficiencies of the transmembrane iron-transporting protein ferroportin (FPN1) cause the iron misdistribution that underlies ferroportin disease, anemia of inflammation, and several other human diseases and conditions. A small molecule natural product, hinokitiol, was recently shown to serve as a surrogate transmembrane iron transporter that can restore hemoglobinization in zebrafish deficient in other iron transporting proteins and can increase gut iron absorption in FPN1-deficient flatiron mice. However, whether hinokitiol can restore normal iron physiology in FPN1-deficient animals or primary cells from patients and the mechanisms underlying such targeted activities remain unknown. Here, we show that hinokitiol redistributes iron from the liver to red blood cells in flatiron mice, thereby increasing hemoglobin and hematocrit. Mechanistic studies confirm that hinokitiol functions as a surrogate transmembrane iron transporter to release iron trapped within liver macrophages, that hinokitiol-Fe complexes transfer iron to transferrin, and that the resulting transferrin-Fe complexes drive red blood cell maturation in a transferrin-receptor–dependent manner. We also show in FPN1-deficient primary macrophages derived from patients with ferroportin disease that hinokitiol moves labile iron from inside to outside cells and decreases intracellular ferritin levels. The mobilization of nonlabile iron is accompanied by reductions in intracellular ferritin, consistent with the activation of regulated ferritin proteolysis. These findings collectively provide foundational support for the translation of small molecule iron transporters into therapies for human diseases caused by iron misdistribution.

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.

Ferroptotic stress promotes macrophages against intracellular bacteria

Rational: Intracellular bacterial survival is a major factor causing chronic or recurrent infection, leading to the failure of both host defense and/or antibiotic treatment. However, the elimination of intracellular bacteria is challenging as they are protected from antibiotics and host immune attack. Recent studies have indicated that iron helps macrophages against intracellular bacteria, contradictory to traditional "nutritional immunity", in which iron is considered a key nutrient for bacterial survival in host cells. However, how iron facilitates intracellular bacterial death has not been fully clarified. In this study, we found that ferroptotic stress can help macrophages suppress intracellular bacteria by reversing the importation of ferrous iron into bacterial vacuoles via ferroportin and thereby inducing in situ ferroptosis-like bacterial death. Methods: A macrophage model of bacterial invasion was established to monitor dynamic changes in ferroptotic hallmarks, including ferrous iron and lipid peroxidation. Ferroptosis inducers and inhibitors were added to the model to evaluate the relationship between ferroptotic stress and intracellular bacterial survival. We then determined the spatiotemporal distributions of ferroportin, ferrous iron, and lipid peroxidation in macrophages and intracellular bacteria. A bacterial infection mouse model was established to evaluate the therapeutic effects of drugs that regulate ferroptotic stress. Results: Ferrous iron and lipid peroxidation increased sharply in the early stage of bacterial infection in the macrophages, then decreased to normal levels in the late stage of infection. The addition of ferroptosis inducers (ras-selective lethal small molecule 3, sulfasalazine, and acetaminophen) in macrophages promoted intracellular bacterial suppression. Further studies revealed that ferrous iron could be delivered to the intracellular bacterial compartment via inward ferroportin transportation, where ferrous iron induced ferroptosis-like death of bacteria. In addition, ferroptotic stress declined to normal levels in the late stage of infection by regulating iron-related pathways in the macrophages. Importantly, we found that enhancing ferroptotic stress with a ferroptosis inducer (sulfasalazine) successfully suppressed bacteria in the mouse infection models. Conclusions: Our study suggests that the spatiotemporal response to ferroptosis stress is an efficient pathway for macrophage defense against bacterial invasion, and targeting ferroptosis may achieve therapeutic targets for infectious diseases challenged by intracellular pathogens.

Hepatic Homeostasis of Metal Ions Following Acute Repeated Stress Exposure in Rats

Essential metals such as copper, iron, and zinc are cofactors in various biological processes including oxygen utilisation, cell growth, and biomolecular synthesis. The homeostasis of these essential metals is carefully controlled through a system of protein transporters involved in the uptake, storage, and secretion. Some metal ions can be transformed by processes including reduction/oxidation (redox) reactions, and correspondingly, the breakdown of metal ion homeostasis can lead to formation of reactive oxygen and nitrogen species. We have previously demonstrated rapid biochemical responses to stress involving alterations in the redox state to generate free radicals and the resultant oxidative stress. However, the effects of stress on redox-active metals including iron and copper and redox-inert zinc have not been well characterised. Therefore, this study aims to examine the changes in these essential metals following exposure to short-term repeated stress, and to further elucidate the alterations in metal homeostasis through expression analysis of different metal transporters. Outbred male Wistar rats were exposed to unrestrained (control), 1 day, or 3 days of 6 h restraint stress (n = 8 per group). After the respective stress treatment, blood and liver samples were collected for the analysis of biometal concentrations and relative gene expression of metal transporter and binding proteins. Exposure to repeated restraint stress was highly effective in causing hepatic redox imbalance. Stress was also shown to induce hepatic metal redistribution, while modulating the mRNA levels of key metal transporters. Overall, this study is the first to characterise the gene expression profile of metal homeostasis following stress and provide insight into the changes occurring prior to the onset of chronic stress conditions.

The Role of Iron in Cancer Progression

Iron is an essential trace element for the human body, and its deficiency or excess can induce a variety of biological processes. Plenty of evidences have shown that iron metabolism is closely related to the occurrence and development of tumors. In addition, iron plays an important role in cell death, which is very important for the development of potential strategies for tumor treatment. Here, we reviewed the latest research about iron metabolism disorders in various types of tumors, the functions and properties of iron in ferroptosis and ferritinophagy, and new opportunities for iron-based on treatment methods for tumors, providing more information regarding the prevention and treatment of tumors.

Utilization of Pharmacological Ascorbate to Enhance Hydrogen Peroxide-Mediated Radiosensitivity in Cancer Therapy

Interest in the use of pharmacological ascorbate as a treatment for cancer has increased considerably since it was introduced by Cameron and Pauling in the 1970s. Recently, pharmacological ascorbate has been used in preclinical and early-phase clinical trials as a selective radiation sensitizer in cancer. The results of these studies are promising. This review summarizes data on pharmacological ascorbate (1) as a safe and efficacious adjuvant to cancer therapy; (2) as a selective radiosensitizer of cancer via a mechanism involving hydrogen peroxide; and (3) as a radioprotector in normal tissues. Additionally, we present new data demonstrating the ability of pharmacological ascorbate to enhance radiation-induced DNA damage in glioblastoma cells, facilitating cancer cell death. We propose that pharmacological ascorbate may be a general radiosensitizer in cancer therapy and simultaneously a radioprotector of normal tissue.

Nrf2 Alleviates Cognitive Dysfunction and Brain Inflammatory Injury via Mediating Wfs1 in Rats with Depression-Like Behaviors

Depression is a major threat to global mental health and demands targeted therapeutic regimens. The current study set out to evaluate the regulatory mechanism of nuclear factor erythroid-2 related factor 2 (Nrf2) in depression-induced cognitive dysfunction and inflammatory injury. First, depressive rat models were established via chronic unpredicted mild stress (CUMS) treatment. Cognitive function of rats was assessed by a series of behavioral tests. Rats were further stereotactically injected with Nrf2 overexpression vector, with expression patterns of Nrf2, miR-17-5p, and wolfram syndrome 1 (Wfs1) detected using qRT-PCR and Western blot assay. In addition, pathological changes of murine hippocampus were analyzed using hematoxylin-eosin staining. In vitro cell models were additionally established using lipopolysaccharide. Cell viability was detected via the CCK-8 method. Moreover, levels of TNF-α, IL-1β, and IL-10 were detected via ELISA. Furthermore, the binding relationships between Nrf2 and the miR-17-5p promoter, miR-17-5p, and Wfs1 were verified. It was found that Nrf2 was weakly expressed in CUMS-treated rats, whereas Nrf2 upregulation alleviated cognitive dysfunction and brain inflammatory injury. Meanwhile, Nrf2 inhibited miR-17-5p expression via binding to the miR-17-5p promoter. miR-17-5p was also found to limit Wfs1 transcription. miR-17-5p overexpression or Wfs1 downregulation partly reversed the role of Nrf2 in reliving inflammatory injury of murine hippocampal neurons. Overall, our findings indicated that Nrf2 inhibited miR-17-5p expression and promoted Wfs1 transcription, thereby alleviating cognitive dysfunction and inflammatory injury in rats with depression-like behaviors.

circ_0005379 inhibits the progression of oral squamous cell carcinoma by regulating the miR-17-5p/acyl-CoA oxidase 1 axis

OBJECTIVES

To investigate the effects of circ_0005379 on the proliferation, apoptosis, migration, and invasion of oral squamous cell carcinoma (OSCC) cells and its mechanism.

METHODS

Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression levels of circ_0005379 and miR-17-5p in OSCC tissues and SCC15 cell lines. Western blot was used to detect the expression levels of acyl-CoA oxidase 1 (ACOX1). The circ_0005379 overexpression vector was transfected into SCC15 cells. Methyl thiazolyl tetrazolium blue staining, flow cytometry, Transwell, and Western blot were used to detect the effects of circ_0005379 overexpression on the proliferation, apoptosis, migration, and invasion of SCC15 cells and the expression of E-cadherin, β-catenin, and Snail proteins. Dual luciferase reporter assay and RNA immunoprecipitation were used to examine the regulation of circ_0005379, miR-17-5p, miR-17-5p, and ACOX1 in SCC15 cells. A nude mouse xenograft model of SCC15 cells stably overexpressing circ_0005379 was established, and the effect of circ_0005379 overexpression on the growth of xenografts in nude mice was observed.

RESULTS

Compared with adjacent cancer tissues, the expression levels of circ_0005379 and ACOX1 proteins in OSCC tissues were decreased (P<0.05), and the expression level of miR-17-5p was increased (P<0.05). Compared with HOK-16A cells, the expression levels of circ_0005379 and ACOX1 proteins in SCC15 cell lines were decreased (P<0.05), and the expression level of miR-17-5p was increased (P<0.05). After overexpressing circ_0005379, the activity and number of migrating and invading SCC15 cells and the expression levels of β-catenin and Snail proteins were decreased (P<0.05); however, the apoptosis rate and expression level of E-cadherin protein were increased (P<0.05). In SCC15 cells, circ_0005379 targeted the negative regulation of miR-17-5p expression, and miR-17-5p targeted the negative regulation of ACOX1 expression. Overexpressing miR-17-5p or silencing ACOX1 could reverse the effects of circ_0005379 overexpression on the proliferation, apoptosis, migration, and invasion of OSCC cell lines. The tumor volume and weight of nude mice overexpressing circ_0005379 were decreased (P<0.05), the expression levels of circ_0005379 and ACOX1 protein in tumor tissues were increased (P<0.05), and the expression level of miR-17-5p was decreased (P<0.05).

CONCLUSIONS

circ_0005379 may inhibit the proliferation, migration, and invasion of OSCC cells by downregulating the expression of miR-17-5p and upregulating ACOX1, which promote apoptosis and inhibit tumor growth in vivo. circ_0005379 may be a potential target for OSCC treatment.

Targeting iron metabolism in cancer therapy

Iron is a critical component of many cellular functions including DNA replication and repair, and it is essential for cell vitality. As an essential element, iron is critical for maintaining human health. However, excess iron can be highly toxic, resulting in oxidative DNA damage. Many studies have observed significant associations between iron and cancer, and the association appears to be more than just coincidental. The chief characteristic of cancers, hyper-proliferation, makes them even more dependent on iron than normal cells. Cancer therapeutics are becoming as diverse as the disease itself. Targeting iron metabolism in cancer cells is an emerging, formidable field of therapeutics. It is a strategy that is highly diverse with regard to specific targets and the various ways to reach them. This review will discuss the importance of iron metabolism in cancer and highlight the ways in which it is being explored as the medicine of tomorrow.

Long non‑coding RNA DANCR represses the viability, migration and invasion of multiple myeloma cells by sponging miR‑135b‑5p to target KLF9

Multiple myeloma (MM) is a malignancy of plasma cells that leads to marrow failure and bone lesions. Numerous studies have verified the link between long non‑coding RNAs (lncRNAs) and MM. The present study aimed to examine the role and underlying mechanism of differentiation antagonizing non‑protein coding RNA (DANCR) in MM cells. The relative expression levels of DANCR, microRNA (miR)‑135b‑5p and Krüppel‑like factor 9 (KLF9) were examined using reverse transcription‑quantitative PCR. Cell viability was assessed using the MTT assay, while relative cell migration and invasion were evaluated using Transwell assays. Moreover, the dual‑luciferase reporter assay was used to examine the interplay between DANCR, miR‑135b‑5p and KLF9. Western blotting was performed to determine the expression level of KLF9. It was found that lncRNA DANCR and KLF9 were downregulated, while miR‑135b‑5p was upregulated in the serum of patients with MM and in MM cells compared with the controls. Overexpressing DANCR or knocking down miR‑135b‑5p reduced the viability of the MM cells, as well as restrained MM cells from migrating and invading. Furthermore, DANCR directly targeted miR‑135b‑5p and was negatively correlated with miR‑135b‑5p. It was also found that KLF9 was targeted by miR‑135b‑5p and was inversely correlated with miR‑135b‑5p expression. The impact of lncRNA DANCR‑mediated suppression on cell viability, invasion and migration was partially abolished by short hairpin RNA KLF9 or miR‑135b‑5p mimics transfection in MM cells. Thus, it was suggested that lncRNA DANCR repressed the viability, migration and invasion of MM cells by sponging miR‑135b‑5p to target KLF9.

Succinate accumulation contributes to oxidative stress and iron accumulation in pentylenetetrazol-induced epileptogenesis and kainic acid-induced seizure

This study explored the role of succinate accumulation in the oxidative stress and iron accumulation in both pentylenetetrazol (PTZ)-induced epileptogenesis and kainic acid (KA)-induced status epilepticus (SE). The levels of succinate, oxidative stress, iron content, iron-related protein expression, and the severity of neuronal injury and seizures were measured in both models. We found that increased concentrations of succinate were associated with increased levels of oxidative stress, iron content, iron regulator protein, and iron importer divalent metal transporter 1, as well as decreased levels of iron exporter ferropotin 1. Aggravated neuronal injury was observed in the hippocampi and cortices of both models. The cell-permeable molecule dimethyl malonate (DM), a competitive inhibitor of succinate dehydrogenase (SDH), significantly attenuated succinate accumulation, reduced the oxidative stress and iron levels, and mitigated the severity of the seizures and neuronal injury. Our results thus indicate that the accumulation of succinate due to the reverse catalysis of SDH may exacerbate oxidative stress and thus induce iron accumulation and neuronal injury in both models. Targeting succinate accumulation may achieve neuroprotective and anti-seizure effects.

Insights into the Role of the Discontinuous TM7 Helix of Human Ferroportin through the Prism of the Asp325 Residue

The negatively charged Asp325 residue has proved to be essential for iron export by human (HsFPN1) and primate Philippine tarsier (TsFpn) ferroportin, but its exact role during the iron transport cycle is still to be elucidated. It has been posited as being functionally equivalent to the metal ion-coordinating residue His261 in the C-lobe of the bacterial homolog BbFpn, but the two residues arise in different sequence motifs of the discontinuous TM7 transmembrane helix. Furthermore, BbFpn is not subject to extracellular regulation, contrary to its mammalian orthologues which are downregulated by hepcidin. To get further insight into the molecular mechanisms related to iron export in mammals in which Asp325 is involved, we investigated the behavior of the Asp325Ala, Asp325His, and Asp325Asn mutants in transiently transfected HEK293T cells, and performed a comparative structural analysis. Our biochemical studies clearly distinguished between the Asp325Ala and Asp325His mutants, which result in a dramatic decrease in plasma membrane expression of FPN1, and the Asp325Asn mutant, which alters iron egress without affecting protein localization. Analysis of the 3D structures of HsFPN1 and TsFpn in the outward-facing (OF) state indicated that Asp325 does not interact directly with metal ions but is involved in the modulation of Cys326 metal-binding capacity. Moreover, models of the architecture of mammalian proteins in the inward-facing (IF) state suggested that Asp325 may form an inter-lobe salt-bridge with Arg40 (TM1) when not interacting with Cys326. These findings allow to suggest that Asp325 may be important for fine-tuning iron recognition in the C-lobe, as well as for local structural changes during the IF-to-OF transition at the extracellular gate level. Inability to form a salt-bridge between TM1 and TM7b during iron translocation could lead to protein instability, as shown by the Asp325Ala and Asp325His mutants.

Ferroptosis Suppressive Genes Correlate with Immunosuppression in Glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most lethal primary tumor in the central nervous system. Ferroptosis is a type of programmed iron-dependent cell death. In the present study, we aimed to identify prognostic ferroptosis-related genes and their role in tumor immunity.

METHODS

We used differential and survival analysis and The Cancer Genome Atlas (TCGA) GBM RNA sequencing data. We also used systematic bioinformatic methods.

RESULTS

Using differential and survival analysis, we found that a ferroptosis suppressor was predominant within ferroptosis-related genes in TCGA GBM RNA sequencing data. By integrating TCGA and gene expression omnibus GBM cohorts, 12 dysregulated ferroptosis suppressors were detected. Among the suppressors, CD44, heat shock protein family B (small) member 1 (HSPB1), and solute carrier family 40 member 1 (SLC40A1) were relevant to overall survival. Using systematic bioinformatic methods, we observed that ferroptosis suppressor expression correlated with immunosuppression, which could be attributed to T-cell exhaustion and cytotoxic T-lymphocyte evasion. Finally, we observed that a potential ferroptosis-inducing drug, acetaminophen, interacted with CD44, HSPB1, and SLC40A1.

CONCLUSIONS

The ferroptosis suppressors CD44, HSPB1, and SLC40A1 were significantly associated with prognosis in GBM and correlated with immunosuppression (i.e., T-cell exhaustion and cytotoxic T-lymphocyte evasion). Acetaminophen might have an antitumor function in GBM by regulating CD44, HSPB1, and SLC40A1 to induce ferroptosis. Our results are expected to be of great significance in developing new immunotherapy strategies for GBM.

A guide to plasma membrane solute carrier proteins

This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.

The Role of NRF2/KEAP1 Signaling Pathway in Cancer Metabolism

The nuclear factor-erythroid 2 p45-related factor 2 (NRF2, also called Nfe2l2) and its cytoplasmic repressor, Kelch-like ECH-associated protein 1 (KEAP1), are major regulators of redox homeostasis controlling a multiple of genes for detoxification and cytoprotective enzymes. The NRF2/KEAP1 pathway is a fundamental signaling cascade responsible for the resistance of metabolic, oxidative stress, inflammation, and anticancer effects. Interestingly, a recent accumulation of evidence has indicated that NRF2 exhibits an aberrant activation in cancer. Evidence has shown that the NRF2/KEAP1 signaling pathway is associated with the proliferation of cancer cells and tumerigenesis through metabolic reprogramming. In this review, we provide an overview of the regulatory molecular mechanism of the NRF2/KEAP1 pathway against metabolic reprogramming in cancer, suggesting that the regulation of NRF2/KEAP1 axis might approach as a novel therapeutic strategy for cancers.

TAM-ing the CIA-Tumor-Associated Macrophages and Their Potential Role in Unintended Side Effects of Therapeutics for Cancer-Induced Anemia

Cancer-induced anemia (CIA) is a common consequence of neoplasia and has a multifactorial pathophysiology. The immune response and tumor treatment, both intended to primarily target malignant cells, also affect erythropoiesis in the bone marrow. In parallel, immune activation inevitably induces the iron-regulatory hormone hepcidin to direct iron fluxes away from erythroid progenitors and into compartments of the mononuclear phagocyte system. Moreover, many inflammatory mediators inhibit the synthesis of erythropoietin, which is essential for stimulation and differentiation of erythroid progenitor cells to mature cells ready for release into the blood stream. These pathophysiological hallmarks of CIA imply that the bone marrow is not only deprived of iron as nutrient but also of erythropoietin as central growth factor for erythropoiesis. Tumor-associated macrophages (TAM) are present in the tumor microenvironment and display altered immune and iron phenotypes. On the one hand, their functions are altered by adjacent tumor cells so that they promote rather than inhibit the growth of malignant cells. As consequences, TAM may deliver iron to tumor cells and produce reduced amounts of cytotoxic mediators. Furthermore, their ability to stimulate adaptive anti-tumor immune responses is severely compromised. On the other hand, TAM are potential off-targets of therapeutic interventions against CIA. Red blood cell transfusions, intravenous iron preparations, erythropoiesis-stimulating agents and novel treatment options for CIA may interfere with TAM function and thus exhibit secondary effects on the underlying malignancy. In this Hypothesis and Theory, we summarize the pathophysiological hallmarks, clinical implications and treatment strategies for CIA. Focusing on TAM, we speculate on the potential intended and unintended effects that therapeutic options for CIA may have on the innate immune response and, consequently, on the course of the underlying malignancy.

Iron-Bound Lipocalin-2 from Tumor-Associated Macrophages Drives Breast Cancer Progression Independent of Ferroportin

Macrophages supply iron to the breast tumor microenvironment by enforced secretion of lipocalin-2 (Lcn-2)-bound iron as well as the increased expression of the iron exporter ferroportin (FPN). We aimed at identifying the contribution of each pathway in supplying iron for the growing tumor, thereby fostering tumor progression. Analyzing the expression profiles of Lcn-2 and FPN using the spontaneous polyoma-middle-T oncogene (PyMT) breast cancer model as well as mining publicly available TCGA (The Cancer Genome Atlas) and GEO Series(GSE) datasets from the Gene Expression Omnibus database (GEO), we found no association between tumor parameters and Lcn-2 or FPN. However, stromal/macrophage-expression of Lcn-2 correlated with tumor onset, lung metastases, and recurrence, whereas FPN did not. While the total iron amount in wildtype and Lcn-2^-/- PyMT tumors showed no difference, we observed that tumor-associated macrophages from Lcn-2^-/- compared to wildtype tumors stored more iron. In contrast, Lcn-2^-/- tumor cells accumulated less iron than their wildtype counterparts, translating into a low migratory and proliferative capacity of Lcn-2^-/- tumor cells in a 3D tumor spheroid model in vitro. Our data suggest a pivotal role of Lcn-2 in tumor iron-management, affecting tumor growth. This study underscores the role of iron for tumor progression and the need for a better understanding of iron-targeted therapy approaches.

Downregulation of FPN1 acts as a prognostic biomarker associated with immune infiltration in lung cancer

Lung cancer morbidity and mortality remain the leading causes of tumor-associated death worldwide. The discovery of early diagnostic and prognostic markers of lung cancer could significantly improve the survival rate and decrease the mortality rate. FPN1 is the only known mammalian iron exporter. However, the molecular and biological functions of FPN1 in lung cancer remain unclear. Here, FPN1 mRNA expression in lung cancer was estimated using the TCGA, Oncomine, TIMER, and UALCAN databases. The prognostic role of FPN1 was evaluated using Kaplan-Meier plotter and PrognoScan. Associations between FPN1 and immune infiltration in lung cancer were evaluated by the TIMER and CIBERSORT algorithms. FPN1 mRNA and protein expressions were significantly downregulated in lung cancer. Low FPN1 expression was strongly related to worse prognosis in patients with lung cancer. GO and KEGG analyses and GSEA suggested that FPN1 was remarkably related to iron homeostasis and immunity. Importantly, FPN1 was remarkably associated with the infiltrating abundance of multiple immune cells. Moreover, FPN1 displayed a strong correlation with various immune marker sets. We investigated the clinical application value of FPN1 and provided a basis for the sensitive diagnosis, prognostication and targeted therapy of lung cancer.

Biology of the iron efflux transporter, ferroportin

Iron, the most common metal in the earth, is also an essential component for almost all living organisms. While these organisms require iron for many biological processes, too much or too little iron itself poses many issues; this is most easily recognized in human beings. The control of body iron levels is thus an important metabolic process which is regulated essentially by controlling the expression, activity and levels of the iron transporter ferroportin. Ferroportin is the only known iron exporter. The function and activity of ferroportin is influenced by its interaction with the iron-regulatory peptide hepcidin, which itself is regulated by many factors. Here we review the current state of understanding of the mechanisms that regulate ferroportin and its function.

New promising developments for potential therapeutic applications of high-dose ascorbate as an anticancer drug

Vitamin C (ascorbate) is an essential dietary requirement, with fundamental redox, anti-oxidant functions at physiologic concentrations. Vitamin C is a cofactor for Fe²⁺ and 2-oxoglutarate-dependent dioxygenases, englobing large families of enzymes, including also epigenetic regulators of DNA and histone methylation. Importantly, vitamin C is involved in the control of the activity of TET (ten-eleven translocation) enzymes, key epigenetic regulators. For this spectrum of activities, often involving pathways deregulated in cancer cells, vitamin C possesses some pharmacologic activities that can be exploited in anticancer therapy. In particular, the capacity of pharmacological doses of vitamin C to target redox imbalance and to rescue deregulated epigenetic program observed in some cancer cells represents a consistent therapeutic potentiality. Several recent studies have identified some cancer subsets that could benefit from the pharmacological activities of vitamin C. The identification of these potentially responsive patients will help to carefully define controlled clinical trials aiming to evaluate the anticancer activity of Vitamin C.

Extracellular Citrate Fuels Cancer Cell Metabolism and Growth

Cancer cells need excess energy and essential nutrients/metabolites not only to divide and proliferate but also to migrate and invade distant organs for metastasis. Fatty acid and cholesterol synthesis, considered a hallmark of cancer for anabolism and membrane biogenesis, requires citrate. We review here potential pathways in which citrate is synthesized and/or supplied to cancer cells and the impact of extracellular citrate on cancer cell metabolism and growth. Cancer cells employ different mechanisms to support mitochondrial activity and citrate synthesis when some of the necessary substrates are missing in the extracellular space. We also discuss the different transport mechanisms available for the entry of extracellular citrate into cancer cells and how citrate as a master metabolite enhances ATP production and fuels anabolic pathways. The available literature suggests that cancer cells show an increased metabolic flexibility with which they tackle changing environmental conditions, a phenomenon crucial for cancer cell proliferation and metastasis.

Iron Dysregulation in Human Cancer: Altered Metabolism, Biomarkers for Diagnosis, Prognosis, Monitoring and Rationale for Therapy

Simple Summary

Iron is the more abundant metal ion in humans. It is essential for life as it has a role in various cellular processes involved, for instance, in cell metabolism and DNA synthesis. These functions are crucial for cell proliferation, and it is therefore not surprising that iron is accumulated in tumors. In this review, we describe normal and altered iron homeostasis mechanisms. We also provide a vision of iron-related proteins with altered expression in cancers and discuss their potential as diagnostic and/or prognostic biomarkers. Finally, we give an overview of therapeutic strategies acting on iron metabolism to fight against cancers.

Abstract

Iron (Fe) is a trace element that plays essential roles in various biological processes such as DNA synthesis and repair, as well as cellular energy production and oxygen transport, and it is currently widely recognized that iron homeostasis is dysregulated in many cancers. Indeed, several iron homeostasis proteins may be responsible for malignant tumor initiation, proliferation, and for the metastatic spread of tumors. A large number of studies demonstrated the potential clinical value of utilizing these deregulated proteins as prognostic and/or predictive biomarkers of malignancy and/or response to anticancer treatments. Additionally, the iron present in cancer cells and the importance of iron in ferroptosis cell death signaling pathways prompted the development of therapeutic strategies against advanced stage or resistant cancers. In this review, we select relevant and promising studies in the field of iron metabolism in cancer research and clinical oncology. Besides this, we discuss some co-existing discrepant findings. We also present and discuss the latest lines of research related to targeting iron, or its regulatory pathways, as potential promising anticancer strategies for human therapy. Iron chelators, such as deferoxamine or iron-oxide-based nanoparticles, which are already tested in clinical trials, alone or in combination with chemotherapy, are also reported.

Iron and Cancer: 2020 Vision

New and provocative insights into the relationships between iron and cancer have been uncovered in recent years. These include delineation of connections that link cellular iron to DNA repair, genomic integrity, and oncogenic signaling as well as the discovery of ferroptosis, a novel iron-dependent form of cell death. In parallel, new molecules and pathways that regulate iron influx, intracellular iron trafficking, and egress in normal cells, and their perturbations in cancer have been discovered. In addition, insights into the unique properties of iron handling in tumor-initiating cells (cancer stem cells), novel contributions of the tumor microenvironment to the uptake and regulation of iron in cancer cells, and new therapeutic modalities that leverage the iron dependence of cancer have emerged.

Revisiting cancer hallmarks: insights from the interplay between oxidative stress and non-coding RNAs

Cancer is one of the most common disease worldwide, with complex changes and certain traits which have been described as “The Hallmarks of Cancer.” Despite increasing studies on in-depth investigation of these hallmarks, the molecular mechanisms associated with tumorigenesis have still not yet been fully defined. Recently, accumulating evidence supports the observation that microRNAs and long noncoding RNAs (lncRNAs), two main classes of noncoding RNAs (ncRNAs), regulate most cancer hallmarks through their binding with DNA, RNA or proteins, or encoding small peptides. Reactive oxygen species (ROS), the byproducts generated during metabolic processes, are known to regulate every step of tumorigenesis by acting as second messengers in cancer cells. The disturbance in ROS homeostasis leads to a specific pathological state termed “oxidative stress”, which plays essential roles in regulation of cancer progression. In addition, the interplay between oxidative stress and ncRNAs is found to regulate the expression of multiple genes and the activation of several signaling pathways involved in cancer hallmarks, revealing a potential mechanistic relationship involving ncRNAs, oxidative stress and cancer. In this review, we provide evidence that shows the essential role of ncRNAs and the interplay between oxidative stress and ncRNAs in regulating cancer hallmarks, which may expand our understanding of ncRNAs in the cancer development from the new perspective.

Mitochondrion-mediated iron accumulation promotes carcinogenesis and Warburg effect through reactive oxygen species in osteosarcoma

Background

Iron metabolism disorder is closely associated with several malignant tumors, however the mechanisms underlying iron and the carcinogenesis in osteosarcoma are not yet well understood.

Methods

Cell proliferation ability of osteosarcoma cell lines was measured by CCK-8, EdU incorporation and colony formation assays. Cell cycle analysis was detected by flow cytometry. The carcinogenesis of osteosarcoma was measured by soft-agar formation, trans-well and Wound healing-scratch assay. Warburg effect was detected by Seahorse respirometry assays. Reactive oxygen species (ROS) level was measured by Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescent probes. Western blotting was used to measure the expression of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28). Iron level in vitro and vivo was detected by iron assay kit. RNAi stable cell lines was generated using shRNA.

Results

Iron promoted proliferation, carcinogenesis and Warburg effect of osteosarcoma cells. Iron-induced reactive oxygen species (ROS) played an important role in these processes. Iron accumulated more in mitochondrion than in cytoplasm, suggesting mitochondrion-mediated iron accumulation was involved in the development of osteosarcoma. Moreover, iron upregulated the expression of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28). Knock-down of mitoferrin 1 (SLC25A37) and mitoferrin 2 (SLC25A28) decreased the production of ROS. In addition, iron increased the expression of Warburg key enzymes HK2 and Glut1, and affected AMPK/mTORC1 signaling axis.

Conclusions

Mitochondrion-mediated iron accumulation promotes carcinogenesis and Warburg effect of osteosarcoma cells. Meanwhile, iron deprivation might be a novel effective strategy in the treatment of osteosarcoma.