Nrf2 inhibition reverses the resistance of cisplatin-resistant head and neck cancer cells to artesunate-induced ferroptosis

A Ferroptosis-Related Gene Signature for Predicting the Prognosis and Drug Sensitivity of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers worldwide and has a high mortality. Ferroptosis, an iron-dependent form of programmed cell death, plays a crucial role in tumor suppression and chemotherapy resistance in cancer. However, the prognostic and clinical values of ferroptosis-related genes (FRGs) in HNSCC remain to be further explored. In the current study, we constructed a ferroptosis-related prognostic model based on the Cancer Genome Atlas database and then explored its prognostic and clinical values in HNSCC via a series of bioinformatics analyses. As a result, we built a four-gene prognostic signature, including FTH1, BNIP3, TRIB3, and SLC2A3. Survival analysis showed that the high-risk group presented significantly poorer overall survival than the low-risk group. Moreover, the ferroptosis-related signature was found to be an independent prognostic predictor with high accuracy in survival prediction for HNSCC. According to immunity analyses, we found that the low-risk group had higher anti-tumor immune infiltration cells and higher expression of immune checkpoint molecules and meanwhile corelated more closely with some anti-tumor immune functions. Meanwhile, all the above results were validated in the independent HSNCC cohort GSE65858. Besides, the signature was found to be remarkably correlated with sensitivity of common chemotherapy drugs for HNSCC patients and the expression levels of signature genes were also significantly associated with drug sensitivity to cancer cells. Overall, we built an effective ferroptosis-related prognostic signature, which could predict the prognosis and help clinicians to perform individualized treatment strategy for HNSCC patients.

Reactive oxygen species: Role in carcinogenesis, cancer cell signaling and tumor progression

Cancer is one of the major causes of death in the world and its global burden is expected to continue increasing. In several types of cancers, reactive oxygen species (ROS) have been extensively linked to carcinogenesis and cancer progression. However, studies have reported conflicting evidence regarding the role of ROS in cancer, mostly dependent on the cancer type or the step of the tumorigenic process. We review recent studies describing diverse aspects of the interplay of ROS with cancer in the different stages of cancer progression, with a special focus on their role in carcinogenesis, their importance for cancer cell signaling and their relationship to the most prevalent cancer risk factors.

Nrf2 attenuates ferroptosis-mediated IIR-ALI by modulating TERT and SLC7A11

Acute lung injury (ALI) carries a mortality rate of ~50% and is a hot topic in the world of critical illness research. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a critical modulator of intracellular oxidative homeostasis and serves as an antioxidant. The Nrf2-related anti-oxidative stress is strongly associated with ferroptosis suppression. Meanwhile, telomerase reverse transcriptase (TERT), the catalytic portion of the telomerase protein, is reported to travel to the mitochondria to alleviate ROS. In our study, we found that TERT was significantly reduced in lung tissue of Nrf2^-/- mice in the model of intestinal ischemia/reperfusion-induced acute lung injury (IIR-ALI). In addition, MDA levels showed marked increase, whereas GSH and GPX4 levels fell drastically in ALI models. Moreover, typical-related structural changes were observed in the type II alveolar epithelial cells in the IIR model. We further employed the scanning transmission X-ray microscopy (STXM) to examine Fe levels and distribution within cells. Based on our observations, massive aggregates of Fe were found in the MLE-12 cells upon OGD/R (oxygen and glucose deprivation/reperfusion) induction. Additionally, Nrf2 silencing dramatically reduced TERT and SLC7A11 levels, and further exacerbated cellular injuries. In contrast, TERT-overexpressing cells exhibited marked elevation in SLC7A11 levels and thereby inhibited ferroptosis. Collectively, these data suggest that Nrf2 can negatively regulate ferroptosis via modulation of TERT and SLC7A11 levels. The conclusion from this study brings insight into new candidates that can be targeted in future IIR-ALI therapy.

Emerging Pathological Engagement of Ferroptosis in Gut Diseases

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is mainly characterized by chronic and progressive inflammation that damages the gastrointestinal mucosa. Increasing studies have enlightened that dysregulated cell death occurs in the inflamed sites, leading to the disruption of the intestinal barrier and aggravating inflammatory response. Ferroptosis, a newly characterized form of regulated cell death, is driven by the lethal accumulation of lipid peroxides catalyzed by cellular free iron. It has been widely documented that the fundamental features of ferroptosis, including iron deposition, GSH exhaustion, GPX4 inactivation, and lipid peroxidation, are manifested in the injured gastrointestinal tract in IBD patients. Furthermore, manipulation of the critical ferroptotic genes could alter the progression, severity, or even morbidity of the experimental colitis. Herein, we critically summarize the recent advances in the field of ferroptosis, focusing on interpreting the potential engagement of ferroptosis in the pathogenesis of IBD. Moreover, we are attempting to shed light on a perspective insight into the possibility of targeting ferroptosis as novel therapeutic designs for the clinical intervention of these gastrointestinal diseases.

Natural medicinal ingredients induce tumor ferroptosis and related mechanisms

Ferroptosis is an iron-dependent programmed cell death characterized by reactive oxygen species-induced lipid peroxide accumulation, which is different from cell apoptosis, pyroptosis, necrosis or autophagy. Ferroptosis plays an important role in the regulation of tumorigenesis and tumor development. Recent studies have shown that natural medicinal ingredients can induce ferroptosis in tumor cells through glutathione (GSH)/glutathione peroxidase 4 (GPx4) pathway, iron metabolism, lipid metabolism or other mechanisms. It has been reported that more than 30 natural medicinal ingredients can induce ferroptosis in tumor cells with multiple pathways and multiple targets. This article reviews the current research progress on the antitumor effects of natural medicinal ingredients through inducing cell ferroptosis.

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

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

A Novel Ferroptosis-Related Gene Signature Predicts Recurrence in Patients With Pancreatic Ductal Adenocarcinoma

Background: Recurrence after surgery is largely responsible for the extremely poor outcomes for patients with pancreatic ductal adenocarcinoma (PDAC). Ferroptosis is implicated in chemotherapy sensitivity and tumor recurrence, we aimed to find out survival-associated ferroptosis-related genes and use them to build a practical risk model with the purpose to predict PDAC recurrence. Methods: Univariate Cox regression analysis was conducted to obtain prognostic ferroptosis-related genes in The Cancer Genome Atlas (TCGA, N = 140) cohort. Multivariate Cox regression analysis was employed to construct a reliable and credible gene signature. The prognostic performance was verified in a MTAB-6134 (N = 286) validation cohort and a PACA-CA (N = 181) validation cohort. The stability of the signature was tested in TCGA and MTAB-6134 cohorts by ROC analyses. Pathway enrichment analysis was adopted to preliminary illuminate the biological relevance of the gene signature. Results: Univariate and multivariate Cox regression analyses identified a 5-gene signature that contained CAV1, DDIT4, SLC40A1, SRXN1 and TFAP2C. The signature could efficaciously stratify PDAC patients with different recurrence-free survival (RFS), both in the training and validation cohorts. Results of subgroup receiver operating characteristic curve (ROC) analyses confirmed the stability and the independence of this signature. Our signature outperformed clinical indicators and previous reported models in predicting RFS. Moreover, the signature was found to be closely associated with several cancer-related and drug response pathways. Conclusion: This study developed a precise and concise prognostic model with the clinical implication in predicting PDAC recurrence. These findings may facilitate individual management of postoperative recurrence in patients with PDAC.

Ferroptosis: At the Crossroad of Gemcitabine Resistance and Tumorigenesis in Pancreatic Cancer

The overall five-year survival rate of pancreatic cancer has hardly changed in the past few decades (less than 10%) because of resistance to all known therapies, including chemotherapeutic drugs. In the past few decades, gemcitabine has been at the forefront of treatment for pancreatic ductal adenocarcinoma, but more strategies to combat drug resistance need to be explored. One promising possibility is ferroptosis, a form of a nonapoptotic cell death that depends on intracellular iron and occurs through the accumulation of lipid reactive oxygen species, which are significant in drug resistance. In this article, we reviewed gemcitabine-resistance mechanisms; assessed the relationship among ferroptosis, tumorigenesis and gemcitabine resistance, and explored a new treatment method for pancreatic cancer.

Ferroptosis in liver disease: new insights into disease mechanisms

Characterized by excessive iron accumulation and lipid peroxidation, ferroptosis is a novel form of iron-dependent cell death, which is morphologically, genetically, and biochemically distinct from other well-known cell death. In recent years, ferroptosis has been quickly gaining attention in the field of liver diseases, as the liver is predisposed to oxidative injury and generally, excessive iron accumulation is a primary characteristic of most major liver diseases. In the current review, we first delineate three cellular defense mechanisms against ferroptosis (GPx4 in the mitochondria and cytosol, FSP1 on plasma membrane, and DHODH in mitochondria), along with four canonical modulators of ferroptosis (system Xc⁻, nuclear factor erythroid 2-related factor 2, p53, and GTP cyclohydrolase-1). Next, we review recent progress of ferroptosis studies delineating molecular mechanisms underlying the pathophysiology of several common liver diseases including ischemia/reperfusion-related injury (IRI), nonalcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), hemochromatosis (HH), drug-induced liver injury (DILI), and hepatocellular carcinoma (HCC). Furthermore, we also highlight both challenges and promises that emerged from recent studies that should be addressed and pursued in future investigations before ferroptosis regulation could be adopted as an effective therapeutic target in clinical practice.

Nrf2 Is a Potential Modulator for Orchestrating Iron Homeostasis and Redox Balance in Cancer Cells

Iron is an essential trace mineral element in almost all living cells and organisms. However, cellular iron metabolism pathways are disturbed in most cancer cell types. Cancer cells have a high demand of iron. To maintain rapid growth and proliferation, cancer cells absorb large amounts of iron by altering expression of iron metabolism related proteins. However, iron can catalyze the production of reactive oxygen species (ROS) through Fenton reaction. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is an important player in the resistance to oxidative damage by inducing the transcription of antioxidant genes. Aberrant activation of Nrf2 is observed in most cancer cell types. It has been revealed that the over-activation of Nrf2 promotes cell proliferation, suppresses cell apoptosis, enhances the self-renewal capability of cancer stem cells, and even increases the chemoresistance and radioresistance of cancer cells. Recently, several genes involving cellular iron homeostasis are identified under the control of Nrf2. Since cancer cells require amounts of iron and Nrf2 plays pivotal roles in oxidative defense and iron metabolism, it is highly probable that Nrf2 is a potential modulator orchestrating iron homeostasis and redox balance in cancer cells. In this hypothesis, we summarize the recent findings of the role of iron and Nrf2 in cancer cells and demonstrate how Nrf2 balances the oxidative stress induced by iron through regulating antioxidant enzymes and iron metabolism. This hypothesis provides new insights into the role of Nrf2 in cancer progression. Since ferroptosis is dependent on lipid peroxide and iron accumulation, Nrf2 inhibition may dramatically increase sensitivity to ferroptosis. The combination of Nrf2 inhibitors with ferroptosis inducers may exert greater efficacy on cancer therapy.

Emerging role of ferroptosis in breast cancer: New dawn for overcoming tumor progression

Breast cancer has become a serious threat to women's health. Cancer progression is mainly derived from resistance to apoptosis induced by procedures or therapies. Therefore, new drugs or models that can overcome apoptosis resistance should be identified. Ferroptosis is a recently identified mode of cell death characterized by excess reactive oxygen species-induced lipid peroxidation. Since ferroptosis is distinct from apoptosis, necrosis and autophagy, its induction successfully eliminates cancer cells that are resistant to other modes of cell death. Therefore, ferroptosis may become a new direction around which to design breast cancer treatment. Unfortunately, the complete appearance of ferroptosis in breast cancer has not yet been fully elucidated. Furthermore, whether ferroptosis inducers can be used in combination with traditional anti- breast cancer drugs is still unknown. Moreover, a summary of ferroptosis in breast cancer progression and therapy is currently not available. In this review, we discuss the roles of ferroptosis-associated modulators glutathione, glutathione peroxidase 4, iron, nuclear factor erythroid-2 related factor-2, superoxide dismutases, lipoxygenase and coenzyme Q in breast cancer. Furthermore, we provide evidence that traditional drugs against breast cancer induce ferroptosis, and that ferroptosis inducers eliminate breast cancer cells. Finally, we put forward prospect of using ferroptosis inducers in breast cancer therapy, and predict possible obstacles and corresponding solutions. This review will deepen our understanding of the relationship between ferroptosis and breast cancer, and provide new insights into breast cancer-related therapeutic strategies.

Discovery of a Potent Glutathione Peroxidase 4 Inhibitor as a Selective Ferroptosis Inducer

Potent and selective ferroptosis regulators promote an intensive understanding of the regulation and mechanisms underlying ferroptosis, which is highly associated with various diseases. In this study, through a stepwise structure optimization, a potent and selective ferroptosis inducer was developed targeting to inhibit glutathione peroxidase 4 (GPX4), and the structure-activity relationship (SAR) of these compounds was uncovered. Compound 26a exhibited outstanding GPX4 inhibitory activity with a percent inhibition up to 71.7% at 1.0 μM compared to 45.9% of RSL-3. At the cellular level, 26a could significantly induce lipid peroxide (LPO) increase and effectively induce ferroptosis with satisfactory selectivity (the value of 31.5). The morphological analysis confirmed the ferroptosis induced by 26a. Furthermore, 26a significantly restrained tumor growth in a mouse 4T1 xenograft model without obvious toxicity.

Progress on the study of the anticancer effects of artesunate

Artesunate (ART) is a derivative of artemisinin that is extracted from the wormwood plant Artemisia annua. ART is an antimalarial drug that has been shown to be safe and effective for clinical use. In addition to its antimalarial properties, ART has been attracting attention over recent years due to its reported inhibitory effects on cancer cell proliferation, invasion and migration. Therefore, ART has a wider range of potential clinical applications than first hypothesized. The aim of the present review was to summarize the latest research progress on the possible anticancer effects of ART, in order to lay a theoretical foundation for the further development of ART as a therapeutic option for cancer.

MAFG-AS1/MAFG positive feedback loop contributes to cisplatin resistance in bladder urothelial carcinoma through antagonistic ferroptosis

Though promoting ferroptosis can reduce cisplatin resistance in tumor cells, ferroptosis and cisplatin resistance in bladder urothelial carcinoma (BUC) following long non-coding RNAs (lncRNAs) is largely unknown. Here, we found the highly expressed lncRNA MAF transcription factor G antisense RNA 1 (MAFG-AS1) in BUC, and its inhibition increased the sensitivity of BUC cells to cisplatin by promoting ferroptosis. Mechanically, binding to iron chaperone poly(rC)-binding protein 2 (PCBP2) facilitated the recruitments of MAFG-AS1 to deubiquitinase ubiquitin carboxyl-terminal hydrolase isozyme L5 (UCHL5), thus stabilizing PCBP2 protein itself. Then PCBP2 was confirmed to interact with ferroportin 1 (FPN1), an iron export protein, leading to inhibition of ferroptosis. Moreover, the expression of MAFG-AS1 was regulated by the transcriptional factor MAFG. Interestingly, MAFG-AS1 stimulated MAFG transcription by recruiting histone acetyltransferase p300 (EP300) to promote the histone 3 at lysine 27 (H3K27ac) at genomic locus of MAFG, forming a MAFG-AS1/MAFG positive feedback loop. In patient samples, higher expression of MAFG-AS1 and MAFG in BUC tissues was significantly correlated with T status and N status, such that MAFG-AS1, MAFG, and the combination of the two were independent prognostic indicators and chemotherapy sensitivity predictive biomarkers for BUC patients. These findings suggest that inhibition of MAFG-AS1 and MAFG can increase the sensitivity of BUC cells to cisplatin through promoting ferroptosis, indicating the novel chemotherapy sensitivity biomarkers and therapeutic target for BUC.

The Role of HO-1 and Its Crosstalk with Oxidative Stress in Cancer Cell Survival

Heme oxygenases (HOs) act on heme degradation to produce carbon monoxide (CO), free iron, ferritin, and biliverdin. Upregulation of cellular HO-1 levels is signature of oxidative stress for its downstream effects particularly under pro-oxidative status. Subcellular traffics of HO-1 to different organelles constitute a network of interactions compromising a variety of effectors such as pro-oxidants, ROS, mitochondrial enzymes, and nucleic transcription factors. Some of the compartmentalized HO-1 have been demonstrated as functioning in the progression of cancer. Emerging data show the multiple roles of HO-1 in tumorigenesis from pathogenesis to the progression to malignancy, metastasis, and even resistance to therapy. However, the role of HO-1 in tumorigenesis has not been systematically addressed. This review describes the crosstalk between HO-1 and oxidative stress, and following redox regulation in the tumorigenesis. HO-1-regulated signaling pathways are also summarized. This review aims to integrate basic information and current progress of HO-1 in cancer research in order to enhance the understandings and facilitate following studies.

CISD2 Promotes Resistance to Sorafenib-Induced Ferroptosis by Regulating Autophagy in Hepatocellular Carcinoma

Purpose

Sorafenib is a multi-kinase inhibitor that is used as a standard treatment for advanced hepatocellular carcinoma (HCC). However, the mechanism of sorafenib resistance in HCC is still unclear. It has been shown that CISD2 expression is related to the progression and poor prognosis of HCC. Here, we show a new role for CISD2 in sorafenib resistance in HCC.

Methods

Bioinformatic analysis was used to detect the expression of negative regulatory genes of ferroptosis in sorafenib-resistant samples. The concentration gradient method was used to establish sorafenib-resistant HCC cells. Western blot was used to detect the protein expression of CISD2, LC3, ERK, PI3K, AKT, mTOR, and Beclin1 in HCC samples. Quantitative real-time PCR (qPCR) was used to detect gene expression. CISD2 shRNA and Beclin1 shRNA were transfected to knock down the expression of the corresponding genes. Cell viability was detected by a CCK-8 assay. ROS were detected by DCFH-DA staining, and MDA and GSH were detected with a Lipid Peroxidation MDA Assay Kit and Micro Reduced Glutathione (GSH) Assay Kit, respectively. Flow cytometry was used to detect apoptosis and the levels of ROS and iron ions.

Results

CISD2 was highly expressed in HCC cells compared with normal cells and was associated with poor prognosis in patients. Knockdown of CISD2 promoted a decrease in the viability of drug-resistant HCC cells. CISD2 knockdown promoted sorafenib-induced ferroptosis in resistant HCC cells. The levels of ROS, MDA, and iron ions increased, but the change in GSH was not obvious. Knockdown of CISD2 promoted uncontrolled autophagy in resistant HCC cells. Inhibition of autophagy attenuated CISD2 knockdown-induced ferroptosis. The autophagy promoted by CISD2 knockdown was related to Beclin1. When CISD2 and Beclin1 were inhibited, the effect on ferroptosis was correspondingly weakened.

Conclusion

Inhibition of CISD2 promoted sorafenib-induced ferroptosis in resistant cells, and this process promoted excessive iron ion accumulation through autophagy, leading to ferroptosis. The combination of CISD2 inhibition and sorafenib treatment is an effective therapeutic strategy for resistant HCC.

Artesunate Restrains Maturation of Dendritic Cells and Ameliorates Heart Transplantation-Induced Acute Rejection in Mice through the PERK/ATF4/CHOP Signaling Pathway

Background

Heart transplantation (HT) is the only effective treatment for end-stage heart failure because it can effectively improve the survival rate and quality of life of patients with heart failure. Artesunate (ART) is an artemisinin derivative, with good water solubility and higher oral bioavailability. The main aim of this study was to determine the role of ART in HT mice.

Methods

In animal experiments, mice were divided into the control group, HT group, low ART+HT group, and high ART+HT group. Next, inflammatory cell infiltration, oxidative stress injury, and myocardial cell apoptosis were determined in heart tissue. The proportion of multiple lymphocytes in spleen and lymph nodes was then determined using flow cytometry. In addition, cell experiments were conducted to determine the changes in expression of surface maturation markers of BMDC and changes in intracellular reactive oxygen species after LPS stimulation. Finally, western blot analysis was performed to determine the levels of endoplasmic reticulum stress-related proteins (CHOP/ATF4/PERK).

Results

The survival time of mice in the ART treatment group was significantly prolonged and was positively correlated with the dose. In animal experiments, ART significantly reduced inflammatory cell infiltration in heart tissue and the proportion of CD4+CD8+ T cells in spleens and lymph nodes. Moreover, ART treatment lowered the 8-OHdg in hearts and myocardial apoptosis. In cell experiments, ART treatment slowed down the development and maturation of BMDCs by inhibiting the expression of endoplasmic reticulum stress-related proteins. Furthermore, the treatment alleviated the oxidative stress damage of BMDCs.

Conclusion

ART can inhibit maturation of dendritic cells through the endoplasmic reticulum stress signaling pathway, thereby alleviating acute rejection in mice after heart transplantation.

Ferroptosis and its emerging role in tumor

Ferroptosis is a novel form of programmed cell death characterized by iron-dependent lipid peroxidation accumulation. It is morphologically, biochemically, and genetically distinct from other known cell death, such as apoptosis, necrosis, and pyroptosis. Its regulatory mechanisms include iron metabolism, fatty acid metabolism, mitochondrial respiration, and antioxidative systems eliminating lipid peroxidation, such as glutathione synthesis, selenium-dependent glutathione peroxidase 4, and ubiquinone. The disruption of cellular redox systems causes damage to the cellular membrane leading to ferroptotic cell death. Recent studies have shown that numerous pathological diseases, like tumors, neurodegenerative disorders, and ischemia-reperfusion injury are associated with ferroptosis. As such, pharmacological regulation of ferroptosis either by activation or by suppression will provide a vast potential for treatments of relevant diseases. This review will discuss the advanced progress in ferroptosis and its regulatory mechanisms from both the antioxidative and oxidative sides. In addition, the roles of ferroptosis in various tumorigenesis, development, and therapeutic strategies will be addressed, particularly to chemotherapy and immunotherapy, as well as the discoveries from Traditional Chinese Medicine. This review will lead us to have a comprehensive understanding of the future exploration of ferroptosis and cancer therapy.

Ferroptosis-Related Genes in Lung Adenocarcinoma: Prognostic Signature and Immune, Drug Resistance, Mutation Analysis

It is reported that ferroptosis has close relation with tumorigenesis and drug resistance. However, the clinical significance of ferroptosis in lung adenocarcinoma (LUAD) remains elusive, and the potential targets for ferroptosis-based treatment are limited. In this study, we constructed a 15-gene prognostic signature predicting overall survival based on ferroptosis-related genes (ferroptosis driver genes VDAC2, GLS2, FLT3, TLR4, PHKG2, phosphogluconate dehydrogenase (PGD), PANX1, KRAS, PEBP1, ALOX15, and ALOX12B, and suppressor genes ACSL3, CISD1, FANCD2, and SLC3A2) in The Cancer Genome Atlas (TCGA)-LUAD cohort. The signature’s predictive ability was validated in the GSE68465 and GSE72094 cohorts by survival analysis and independent prognostic analysis with clinical features. Nomograms were provided for clinical reference. Functional analysis revealed that ferroptosis was closely related to cell cycle, cell metabolism, and immune pathways. Pan-cancer analysis comprehensively analyzed these 15 genes in 33 cancer types, indicating that the heterogeneity of 15 genes was evident across different cancer types. Besides, these genes were critical regulators modulating drug resistance, tumor microenvironment infiltration, and cancer stemness. Then, we screened 10 genes (TLR4, PHKG2, PEBP1, GLS2, FLT3, ALOX15, ACSL3, CISD1, FANCD2, and SLC3A2) as potential targets for further research because their biological functions in ferroptosis were consistent with their prognostic significance. Somatic mutation and copy number variation analysis revealed that the alteration rates of KRAS, PGD, and ALOX15 were more than 1% and significantly associated with overall survival in LUAD. Moreover, the expression of KRAS and PGD was positively related to tumor mutation burden, indicating that KRAS and PGD could serve as novel biomarkers for predicting immunotherapy response rate. Our study identified and validated a ferroptosis-related gene signature for LUAD, provided a 10-gene set for future research, and screened KRAS and PGD as potential novel immunotherapy biomarkers.

SLC7A11 regulated by NRF2 modulates esophageal squamous cell carcinoma radiosensitivity by inhibiting ferroptosis

BACKGROUND

Solute carrier family 7 member 11(SLC7A11) is a component of cysteine/glutamate transporter, which plays a key role in tumor growth; however, its underlying effect on radiosensitivity in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aimed to clarify SLC7A11's expression and correlation with nuclear expression of nuclear factor erythroid-2 (NRF2)-associated radioresistance in ESCC.

METHODS

We included 127 ESCC patients who received radical chemoradiotherapy. Immunohistochemical staining was used to detect SLC7A11 and NRF2 nuclear expression, and the relationship between clinicopathological characteristics and survival rates or therapy response were evaluated. Western blot, dual-reporter assays and Chromatin immunoprecipitation (ChIP)-sequencing were used to analyze their relationship in vitro. Their roles in radioresistance were then investigated through multiple validation steps.

RESULTS

NRF2 nuclear expression and SLC7A11 expression were overexpressed in ESCC tissues and were positively correlated with one another. NRF2 nuclear expression was significantly associated with tumor length, lymph node metastasis, and TNM stage, while SLC7A11 expression was associated with lymph node metastasis. Patients with high NRF2 nuclear expression and SLC7A11 expression had significantly shorter overall and progression-free survival, and poor treatment response. The multivariate model showed that NRF2 nuclear expression and SLC7A11 expression, sex and tumor location are independent prognostic factors. In vitro analysis confirmed that hyperactivation of NRF2 induced SLC7A11 expression by directly binding to its promoter region, promoting radioresistance, reducing radiotherapy-induced lipid peroxidation levels, PTGS2 expression, and radiotherapy-related ferroptosis morphologic features.

CONCLUSION

Our study reveals a connection between high SLC7A11 expression and NRF2 nuclear expression in patients with ESCC that was related to worse survival and poorer therapy outcomes. SLC7A11-mediated ferroptosis inhibition induced NRF2-associated radioresistance, highlighting potential of NRF2/SLC7A11/ferroptosis axis as future therapeutic targets against therapy resistance biomarker.

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

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

Cell Ferroptosis: New Mechanism and New Hope for Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a leading cause of inherited retinal degeneration, with more than 60 gene mutations. Despite the genetic heterogenicity, photoreceptor cell damage remains the hallmark of RP pathology. As a result, RP patients usually suffer from reduced night vision, loss of peripheral vision, decreased visual acuity, and impaired color perception. Although photoreceptor cell death is the primary outcome of RP, the underlying mechanisms are not completely elucidated. Ferroptosis is a novel programmed cell death, with characteristic iron overload and lipid peroxidation. Recent studies, using in vitro and in vivo RP models, discovered the involvement of ferroptosis-associated cell death, suggesting a possible new mechanism for RP pathogenesis. In this review, we discuss the association between ferroptosis and photoreceptor cell damage, and its implication in the pathogenesis of RP. We propose that ferroptotic cell death not only opens up a new research area in RP, but may also serve as a novel therapeutic target for RP.

Recurrent Human Papillomavirus-Related Head and Neck Cancer Undergoes Metabolic Reprogramming and Is Driven by Oxidative Phosphorylation

PURPOSE

Human papillomavirus (HPV) infection drives the development of some head and neck squamous cell carcinomas (HNSCC). This disease is rapidly increasing in incidence worldwide. Although these tumors are sensitive to treatment, approximately 10% of patients fail therapy. However, the mechanisms that underlie treatment failure remain unclear.

EXPERIMENTAL DESIGN

We performed RNA sequencing (RNA-seq) on tissues from matched primary- (pHNSCC) and metachronous-recurrent cancers (rHNSCC) to identify transcriptional differences to gain mechanistic insight into the evolutionary adaptations of metachronous-recurrent tumors. We used HPV-related HNSCC cells lines to investigate the effect of (i) NRF2 overexpression on growth in vitro and in vivo, (ii) oxidative phosphorylation (OXPHOS) inhibition using IACS-010759 on NRF2-dependent cells, and (iii) combination of cisplatin and OXPHOS inhibition.

RESULTS

The OXPHOS pathway is enriched in recurrent HPV-associated HNSCC and may contribute to treatment failure. NRF2-enriched HNSCC samples from The Cancer Genome Atlas (TCGA) with enrichment in OXPHOS, fatty-acid metabolism, Myc, Mtor, reactive oxygen species (ROS), and glycolytic signaling networks exhibited worse survival. HPV-positive HNSCC cells demonstrated sensitivity to the OXPHOS inhibitor, in a NRF2-dependent manner. Further, using murine xenograft models, we identified NRF2 as a driver of tumor growth. Mechanistically, NRF2 drives ROS and mitochondrial respiration, and NRF2 is a critical regulator of redox homeostasis that can be crippled by disruption of OXPHOS. NRF2 also mediated cisplatin sensitivity in endogenously overexpressing primary HPV-related HNSCC cells.

CONCLUSIONS

These results unveil a paradigm-shifting translational target harnessing NRF2-mediated metabolic reprogramming in HPV-related HNSCC.

A Shortage of FTH Induces ROS and Sensitizes RAS-Proficient Neuroblastoma N2A Cells to Ferroptosis

Ferroptosis, an iron-dependent form of programmed cell death, has excellent potential as an anti-cancer therapeutic strategy in different types of tumors, especially in RAS-mutated ones. However, the function of ferroptosis for inhibiting neuroblastoma, a common child malignant tumor with minimal treatment, is unclear. This study investigated the anti-cancer function of ferroptosis inducer Erastin or RSL3 in neuroblastoma N2A cells. Our results show that Erastin or RSL3 induces ROS level and cell death and, therefore, reduces the viability of RAS-proficient N2A cells. Importantly, inhibitors to ferroptosis, but not apoptosis, ameliorate the high ROS level and viability defect in Erastin- or RSL3-treated cells. In addition, our data also show that N2A cells are much more sensitive to ferroptosis inducers than primary mouse cortical neural stem cells (NSCs) or neurons. Moreover, a higher level of ROS and PARylation is evidenced in N2A, but not NSCs. Mechanically, ferritin heavy chain 1 (Fth), the ferroxidase function to oxidate redox-active Fe²⁺ to redox-inactive Fe³⁺, is likely responsible for the hypersensitivity of N2A to ferroptosis induction since its expression is lower in N2A compared to NSCs; ectopic expression of Fth reduces ROS levels and cell death, and induces expression of GPX4 and cell viability in N2A cells. Most importantly, neuroblastoma cell lines express a significantly low level of Fth than almost all other types of cancer cell lines. All these data suggest that Erastin or RSL3 induce ferroptosis cell death in neuroblastoma N2A cells, but not normal neural cells, regardless of RAS mutations, due to inadequate FTH. This study, therefore, provides new evidence that ferroptosis could be a promising therapeutic target for neuroblastoma.

Scalp Acupuncture Protects Against Neuronal Ferroptosis by Activating The p62-Keap1-Nrf2 Pathway in Rat Models of Intracranial Haemorrhage

Intracerebral haemorrhage (ICH) can be a catastrophic event; even if the initial stages of the pathology were well-managed, a number of patients experience varied residual neurological deficits following the insult. Ferroptosis is a recently identified type of cell demise which is tightly linked to the neurological impairment associated with ICH. In the current work, the prophylactic impact of scalp acupuncture (SA) therapy on autologous blood injection murine models of ICH was investigated in order to establish whether SA could mitigate the secondary damage arising following ICH by moderating ferroptosis. The pathophysiological mechanisms associated with this process were also explored. Ludmila Belayev tests were utilised for the characterisation of neurological damage. Haematoxylin–eosin staining was employed in order to determine the cerebral impact of the induced ICH. Malondialdehyde (MDA) and iron titres in peri-haemorrhagic cerebral tissues were appraised using purchased assay kits. Transmission electron microscopy delineated mitochondrial appearances within nerve cell bodies from the area of haemorrhage. Western blotting techniques were utilised to assay the degree of protein expression of NeuN, sequestosome 1 (p62), nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap1), glutathione peroxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1). The frequencies of Nrf2, GPX4 and FTH1 positive cells, respectively, were documented with immunohistochemical staining. The results demonstrated that therapy with SA after ICH mitigated MDA and iron sequestration, diminished the appearance of contracted mitochondria with increased outer mitochondrial membrane diameter within the nerve cell bodies, and suppressed neuronal ferroptosis. The pathways responsible for these effects may encompass amplified p62, Nrf2, GPX4 and FTH1 expression, together with decreased Keap1 expression. Application of SA reduced identified neurobehavioural abnormalities after ICH; no disparities were observed between the consequences of SA therapy and deferoxamine delivery. It can be surmised that intervention with SA enhanced recovery after ICH by triggering the antioxidant pathway, p62/Keap1/Nrf2, and causing FTH1 and GPX4 upregulation, factors that participate in diminishing excess iron and thus in mitigating lipid peroxidation insults arising from ferroptosis following ICH.

Ferroptosis: A Trusted Ally in Combating Drug Resistance in Cancer

Ferroptosis, which is an iron-dependent, non-apoptotic cell death mechanism, has recently been proposed as a novel approach in cancer treatment. Bearing distinctive features and its exclusive mechanism have put forward the potential therapeutic benefit of triggering this newly discovered form of cell death. Numerous studies have indicated that apoptotic pathways are often deactivated in resistant cells, leading to a failure in therapy. Hence, alternative strategies to promote cell death are required. Mounting evidence suggests that drug-resistant cancer cells are particularly sensitive to ferroptosis. Given that cancer cells consume a higher amount of iron than healthy ones, ferroptosis not only stands as an excellent alternative to trigger cell death and reverse drug-resistance, but also provides selectivity in therapy. This review focuses specifically on overcoming drug-resistance in cancer through activating ferroptotic pathways and brings together the relevant chemotherapeutics-based and nanotherapeutics-based studies to offer a perspective for researchers regarding the potential use of this mechanism in developing novel therapeutic strategies.

Redox modulation of vitagenes via plant polyphenols and vitamin D: Novel insights for chemoprevention and therapeutic interventions based on organoid technology

Polyphenols are chemopreventive through the induction of nuclear factor erythroid 2 related factor 2 (Nrf2)-mediated proteins and anti-inflammatory pathways. These pathways, encoding cytoprotective vitagenes, include heat shock proteins, such as heat shock protein 70 (Hsp70) and heme oxygenase-1 (HO-1), as well as glutathione redox system to protect against cancer initiation and progression. Phytochemicals exhibit biphasic dose responses on cancer cells, activating at low dose, signaling pathways resulting in upregulation of vitagenes, as in the case of the Nrf2 pathway upregulated by hydroxytyrosol (HT) or curcumin and NAD/NADH-sirtuin-1 activated by resveratrol. Here, the importance of vitagenes in redox stress response and autophagy mechanisms, as well as the potential use of dietary antioxidants in the prevention and treatment of multiple types of cancer are discussed. We also discuss the possible relationship between SARS-CoV-2, inflammation and cancer, exploiting innovative therapeutic approaches with HT-rich aqueous olive pulp extract (Hidrox®), a natural polyphenolic formulation, as well as the rationale of Vitamin D supplementation. Finally, we describe innovative approaches with organoids technology to study human carcinogenesis in preclinical models from basic cancer research to clinical practice, suggesting patient-derived organoids as an innovative tool to test drug toxicity and drive personalized therapy.

The developmental origin of cancers defines basic principles of cisplatin resistance

Cisplatin-based chemotherapy has been used for more than four decades as a standard therapeutic option in several tumor entities. However, being a multifaceted and heterogeneous phenomenon, inherent or acquired resistance to cisplatin remains a major obstacle during the treatment of several solid malignancies and inevitably results in disease progression. Hence, we felt there was an urgent need to evaluate common mechanisms between multifarious cancer entities to identify patient-specific therapeutic strategies. We found joint molecular and (epi)genetic resistance mechanisms and specific cisplatin-induced mutational signatures that depended on the developmental origin (endo-, meso-, ectoderm) of the tumor tissue. Based on the findings of thirteen tumor entities, we identified three resistance groups, where Group 1 (endodermal origin) prominently indicates NRF2-pathway activation, Group 2 (mesodermal origin, primordial germ cells) shares elevated DNA repair mechanisms and decreased apoptosis induction, and Group 3 (ectodermal and paraxial mesodermal origin) commonly presents deregulated apoptosis induction and alternating pathways as the main cisplatin-induced resistance mechanisms. This review further proposes potential and novel therapeutic strategies to improve the outcome of cisplatin-based chemotherapy.

Role of NRF2 in Lung Cancer

The gene expression program induced by NRF2 transcription factor plays a critical role in cell defense responses against a broad variety of cellular stresses, most importantly oxidative stress. NRF2 stability is fine-tuned regulated by KEAP1, which drives its degradation in the absence of oxidative stress. In the context of cancer, NRF2 cytoprotective functions were initially linked to anti-oncogenic properties. However, in the last few decades, growing evidence indicates that NRF2 acts as a tumor driver, inducing metastasis and resistance to chemotherapy. Constitutive activation of NRF2 has been found to be frequent in several tumors, including some lung cancer sub-types and it has been associated to the maintenance of a malignant cell phenotype. This apparently contradictory effect of the NRF2/KEAP1 signaling pathway in cancer (cell protection against cancer versus pro-tumoral properties) has generated a great controversy about its functions in this disease. In this review, we will describe the molecular mechanism regulating this signaling pathway in physiological conditions and summarize the most important findings related to the role of NRF2/KEAP1 in lung cancer. The focus will be placed on NRF2 activation mechanisms, the implication of those in lung cancer progression and current therapeutic strategies directed at blocking NRF2 action.

Autophagy-dependent ferroptosis contributes to cisplatin-induced hearing loss

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

Identification and validation of a novel ferroptosis-related gene model for predicting the prognosis of gastric cancer patients

Background

Ferroptosis is a novel form of regulated cell death that plays a critical role in tumorigenesis. The purpose of this study was to establish a ferroptosis-associated gene (FRG) signature and assess its clinical outcome in gastric cancer (GC).

Methods

Differentially expressed FRGs were identified using gene expression profiles from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. Univariate and least absolute shrinkage and selection operator (LASSO) Cox regression analyses were performed to construct a prognostic signature. The model was validated using an independent GEO dataset, and a genomic-clinicopathologic nomogram integrating risk scores and clinicopathological features was established.

Results

An 8-FRG signature was constructed to calculate the risk score and classify GC patients into two risk groups (high- and low-risk) according to the median value of the risk score. The signature showed a robust predictive capacity in the stratification analysis. A high-risk score was associated with advanced clinicopathological features and an unfavorable prognosis. The predictive accuracy of the signature was confirmed using an independent GSE84437 dataset. Patients in the two groups showed different enrichment of immune cells and immune-related pathways. Finally, we established a genomic-clinicopathologic nomogram (based on risk score, age, and tumor stage) to predict the overall survival (OS) of GC patients.

Conclusions

The novel FRG signature may be a reliable tool for assisting clinicians in predicting the OS of GC patients and may facilitate personalized treatment.

Cisplatin synergizes with PRLX93936 to induce ferroptosis in non-small cell lung cancer cells

Ferroptosis is a newly identified type of regulated cell death that is affected by lipid peroxidation and reactive oxygen species (ROS). In the current study, we showed that cisplatin and PRLX93936, an analog of erastin that has been tested in clinical trials, demonstrated synergistic effects against non-small cell lung cancer (NSCLC) cells. Cotreatment with cisplatin and PRLX93936 induced ferroptosis, as evidenced by the upregulation of ROS, lipid peroxidation and Fe²⁺. Further investigation revealed that cotreatment with cisplatin and PRLX93936 inhibited GPX4 and that overexpression of GPX4 prevented cell death. Moreover, the Nrf2/Keap1 pathway also regulated the sensitivity to cisplatin and PRLX93936 in NSCLC cells. Nrf2 silencing increased this sensitivity while inhibition of Keap1 attenuated it. Overall, our data reveal a new effective treatment for NSCLC by synergizing cisplatin and PRLX93936 to induce ferroptosis.

Progress in Redirecting Antiparasitic Drugs for Cancer Treatment

Drug repurposing is a feasible strategy in developing novel medications. Regarding the cancer field, scientists are continuously making efforts to redirect conventional drugs into cancer treatment. This approach aims at exploring new applications in the existing agents. Antiparasitic medications, including artemisinin derivatives (ARTs), quinine-related compounds, niclosamide, ivermectin, albendazole derivatives, nitazoxanide and pyrimethamine, have been deeply investigated and widely applied in treating various parasitic diseases for a long time. Generally, their pharmacokinetic and pharmacodynamic properties are well understood, while the side effects are roughly acceptable. Scientists noticed that some of these agents have anticancer potentials and explored the underlying mechanisms to achieve drug repurposing. Recent studies show that these agents inhibit cancer progression via multiple interesting ways, inducing ferroptosis induction, autophagy regulation, mitochondrial disturbance, immunoregulation, and metabolic disruption. In this review, we summarize the recent advancement in uncovering antiparasitic drugs' anticancer properties from the perspective of their pharmacological targets. Instead of paying attention to the previously discovered mechanisms, we focus more on newly emerging ones that are worth noticing. While most investigations are focusing on the mechanisms of their antiparasitic effect, more in vivo exploration in clinical trials in the future is necessary. Moreover, we also paid attention to what limits the clinical application of these agents. For some of these agents like ARTs and niclosamide, drug modification, novel delivery system invention, or drug combination are strongly recommended for future exploration.

Ferroptosis Holds Novel Promise in Treatment of Cancer Mediated by Non-coding RNAs

Ferroptosis is a newly identified form of regulated cell death that is associated with iron metabolism and oxidative stress. As a physiological mechanism, ferroptosis selectively removes cancer cells by regulating the expression of vital chemical molecules. Current findings on regulation of ferroptosis have largely focused on the function of non-coding RNAs (ncRNAs), especially microRNAs (miRNAs), in mediating ferroptotic cell death, while the sponging effect of circular RNAs (circRNAs) has not been widely studied. In this review, we discuss the molecular regulation of ferroptosis and highlight the value of circRNAs in controlling ferroptosis and carcinogenesis. Herein, we deliberate future role of this emerging form of regulated cell death in cancer therapeutics and predict the progression and prognosis of oncogenesis in future clinical therapy.

Inhibition of the NRF2/KEAP1 Axis: A Promising Therapeutic Strategy to Alter Redox Balance of Cancer Cells

Significance: The nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (NRF2/KEAP1) pathway is a crucial and highly conserved defensive system that is required to maintain or restore the intracellular homeostasis in response to oxidative, electrophilic, and other types of stress conditions. The tight control of NRF2 function is maintained by a complex network of biological interactions between positive and negative regulators that ultimately ensure context-specific activation, culminating in the NRF2-driven transcription of cytoprotective genes. Recent Advances: Recent studies indicate that deregulated NRF2 activation is a frequent event in malignant tumors, wherein it is associated with metabolic reprogramming, increased antioxidant capacity, chemoresistance, and poor clinical outcome. On the other hand, the growing interest in the modulation of the cancer cells' redox balance identified NRF2 as an ideal therapeutic target. Critical Issues: For this reason, many efforts have been made to identify potent and selective NRF2 inhibitors that might be used as single agents or adjuvants of anticancer drugs with redox disrupting properties. Despite the lack of specific NRF2 inhibitors still represents a major clinical hurdle, the researchers have exploited alternative strategies to disrupt NRF2 signaling at different levels of its biological activation. Future Directions: Given its dualistic role in tumor initiation and progression, the identification of the appropriate biological context of NRF2 activation and the specific clinicopathological features of patients cohorts wherein its inactivation is expected to have clinical benefits, will represent a major goal in the field of cancer research. In this review, we will briefly describe the structure and function of the NRF2/ KEAP1 system and some of the most promising NRF2 inhibitors, with a particular emphasis on natural compounds and drug repurposing. Antioxid. Redox Signal. 34, 1428-1483.

Recent pharmacological advances in the repurposing of artemisinin drugs

Artemisinins are a family of sesquiterpene lactones originally derived from the sweet wormwood (Artemisia annua). Beyond their well-characterized role as frontline antimalarial drugs, artemisinins have also received increased attention for other potential pharmaceutical effects, which include antiviral, antiparsitic, antifungal, anti-inflammatory, and anticancer activities. With concerted efforts in further preclinical and clinical studies, artemisinin-based drugs have the potential to be viable treatments for a great variety of human diseases. Here, we provide a comprehensive update on recent reports of pharmacological actions and applications of artemisinins outside of their better-known antimalarial role and highlight their potential therapeutic viability for various diseases.

Artesunate combined with verteporfin inhibits uveal melanoma by regulation of the MALAT1/yes-associated protein signaling pathway

Uveal melanoma (UM) is the most common ocular malignancy and has no effective clinical treatment. Therefore, novel drugs to suppress UM tumor progression are urgently required. The present study aimed to clarify the underlying mechanism of the inhibitory effects of artesunate on UM. By using plasmid transfection and detecting apoptotic level, the present study identified artesunate as a potential candidate for UM treatment. Compared with those in the vehicle (DMSO)-treated control cells, artesunate enhanced the apoptotic rate and increased lactate dehydrogenase release, reactive oxygen species and IL1b and IL18 levels in C918 cells. Overexpression of yes-associated protein (YAP) or metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in C918 cells reversed the effects of artesunate and reduced the apoptotic rate compared with those observed in cells transfected with the negative control plasmid. Notably, verteporfin enhanced the effects of artesunate on C918 cells by increasing the apoptotic rate, indicating that combined therapy was more effective compared with treatment with artesunate alone. In conclusion, the results of the present study demonstrated that artesunate elevated the apoptotic rate and suppressed C918 cell viability by regulating the MALAT1/YAP signaling pathway, and these effects were enhanced by supplementation with verteporfin. These results suggested that artesunate may exert an inhibitory effect on C918 cells and that the MALAT1/YAP signaling may serve important role in mediating these effects, providing evidence of its potential for treating UM in the clinic.

A Promising Future of Ferroptosis in Tumor Therapy

Currently, mechanisms and therapeutic approaches have been thoroughly studied in various prevalent malignant tumors, such as breast and lung cancer. However, there is inevitable tumor progression and drug resistance. Uncovering novel treatment strategies to inhibit tumor development is important. Ferroptosis, a form of cell death associated with iron and lipid peroxidation, has drawn extensive attention. In this paper, we reviewed the underlying mechanisms of ferroptosis (i.e., iron, glutathione, and lipid metabolism) and its role in various tumors (i.e., lung cancer, liver carcinoma, breast cancer, and pancreatic cancer). Moreover, we summarized ferroptosis-related anti-tumor drugs and emphasized the potential of combined treatment of anti-tumor drugs and radiotherapy in an effort to provide novel anti-tumor treatments.

Iron-Bound Lipocalin-2 Protects Renal Cell Carcinoma from Ferroptosis

While the importance of the iron-load of lipocalin-2 (Lcn-2) in promoting tumor progression is widely appreciated, underlying molecular mechanisms largely remain elusive. Considering its role as an iron-transporter, we aimed at clarifying iron-loaded, holo-Lcn-2 (hLcn-2)-dependent signaling pathways in affecting renal cancer cell viability. Applying RNA sequencing analysis in renal CAKI1 tumor cells to explore highly upregulated molecular signatures in response to hLcn-2, we identified a cluster of genes (SLC7A11, GCLM, GLS), which are implicated in regulating ferroptosis. Indeed, hLcn-2-stimulated cells are protected from erastin-induced ferroptosis. We also noticed a rapid increase in reactive oxygen species (ROS) with subsequent activation of the antioxidant Nrf2 pathway. However, knocking down Nrf2 by siRNA was not sufficient to induce erastin-dependent ferroptotic cell death in hLcn-2-stimulated tumor cells. In contrast, preventing oxidative stress through N-acetyl-l-cysteine (NAC) supplementation was still able to induce erastin-dependent ferroptotic cell death in hLcn-2-stimulated tumor cells. Besides an oxidative stress response, we noticed activation of the integrated stress response (ISR), shown by enhanced phosphorylation of eIF-2α and induction of ATF4 after hLcn-2 addition. ATF4 knockdown as well as inhibition of the ISR sensitized hLcn-2-treated renal tumor cells to ferroptosis, thus linking the ISR to pro-tumor characteristics of hLcn-2. Our study provides mechanistic details to better understand tumor pro-survival pathways initiated by iron-loaded Lcn-2.

Mechanisms of Ferroptosis and Application to Head and Neck Squamous Cell Carcinoma Treatments

Many kinds of cancer cells are intrinsically sensitive to ferroptosis, and research interest regarding ferroptosis has been sparked by its significant role in many detrimental diseases. Ferroptosis is a novel type of iron-dependent cell death mediated by accumulation of reactive oxygen species and lipid peroxidation. Furthermore, a large number of small agents can induce ferroptosis in numerous kinds of cancer cells, including prostate cancer, pancreatic cancer, breast cancer, lymphomas, and renal cancer. These insights may help discover novel approaches for cancer therapeutic strategies; however, there is considerable uncertainty regarding ferroptosis in head and neck cancer (HNC). So far, no review of the current studies on this topic has been published. Therefore, we here elaborate the mechanisms of ferroptosis and summarize the latest findings regarding its role in HNC according to current literature. The respective findings shed light on the role of ferroptosis in HNC treatment with a number of important implications for future practice in HNC management, as outlined in this review.

Ferroptotic Cell Death: New Regulatory Mechanisms for Metabolic Diseases

Background:

Cell death is a fundamental biological phenomenon that contributes to the pathogenesis of various diseases. Regulation of iron and iron metabolism has received considerable research interests especially concerning the progression of metabolic diseases.

Discussion:

Emerging evidence shows that ferroptosis, a non-apoptotic programmed cell death induced by iron-dependent lipid peroxidation, contributes to the development of complex diseases such as non-alcoholic steatohepatitis, cardiomyopathy, renal ischemia-reperfusion, and neurodegenerative diseases. Therefore, inhibiting ferroptosis can improve the pathophysiology of associated metabolic diseases. This review describes the vital role of ferroptosis in mediating the development of certain metabolic diseases. Besides, the potential risk of iron and ferroptosis in atherosclerosis and cardiovascular diseases is also described. Iron overload and ferroptosis are potential secondary causes of death in metabolic diseases. Moreover, this review also provides potential novel approaches against ferroptosis based on recent research advances.

Conclusion:

Several controversies exist concerning mechanisms underlying ferroptotic cell death in metabolic diseases, particularly in atherosclerosis. Since ferroptosis participates in the progression of metabolic diseases such as non-alcoholic steatohepatitis (NASH), there is a need to develop new drugs targeting ferroptosis to alleviate such diseases.

Downregulation of SELENBP1 enhances oral squamous cell carcinoma chemoresistance through KEAP1-NRF2 signaling

PURPOSE

Limited value is achieved in systemic chemotherapy for oral squamous cell carcinoma (OSCC), due to cancer cell resistance against cytotoxic agents. Tumor suppressor activities of selenium-binding protein 1 (SELENBP1) have been shown in multiple human cancers except for OSCC. The aim of this study is to clarify the biological functions and potential mechanism of SELENBP1 in OSCC.

METHODS

SELENBP1 expression and its clinical significance in OSCC were analyzed from The Cancer Genome Atlas (TCGA) database. Quantitative polymerase chain reaction (qPCR) or western blot was applied to determine SELENBP1, NRF2 and KEAP1 mRNA or protein levels. Sulforhodamine B assay (SRB) was performed to examine the cytotoxic effects of 5-fluorouracil (5-FU) and cisplatin on OSCC cells. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay were conducted to investigate the role of SELENBP1 in KEAP1 transcription.

RESULTS

SELENBP1 downregulation is positively correlated with a poor prognosis for OSCC patients. SELENBP1 knockdown enhances resistance of OSCC cells to 5-FU and cisplatin, while SENENBP1 overexpression displays the opposite effects. Mechanistically, SELENBP1 reduces NRF2 protein levels by promoting its polyubiquitination and degradation. SELENBP1 induces KEAP1 transcription by binding to KEAP1 promoter. Downregulation of SELENBP1 is induced by miR-4786-3p binding to the 3' untranslated region (UTR) of SELENBP1.

CONCLUSION

SENENBP1 is identified as a novel protective biomarker for OSCC patients. Targeting at the miR-4786-3p-SELENBP1-KEAP1-NRF2 signaling axis may enhance the efficacy of chemotherapy for OSCC.

Elucidating Role of Reactive Oxygen Species (ROS) in Cisplatin Chemotherapy: A Focus on Molecular Pathways and Possible Therapeutic Strategies

The failure of chemotherapy is a major challenge nowadays, and in order to ensure effective treatment of cancer patients, it is of great importance to reveal the molecular pathways and mechanisms involved in chemoresistance. Cisplatin (CP) is a platinum-containing drug with anti-tumor activity against different cancers in both pre-clinical and clinical studies. However, drug resistance has restricted its potential in the treatment of cancer patients. CP can promote levels of free radicals, particularly reactive oxygen species (ROS) to induce cell death. Due to the double-edged sword role of ROS in cancer as a pro-survival or pro-death mechanism, ROS can result in CP resistance. In the present review, association of ROS with CP sensitivity/resistance is discussed, and in particular, how molecular pathways, both upstream and downstream targets, can affect the response of cancer cells to CP chemotherapy. Furthermore, anti-tumor compounds, such as curcumin, emodin, chloroquine that regulate ROS and related molecular pathways in increasing CP sensitivity are described. Nanoparticles can provide co-delivery of CP with anti-tumor agents and by mediating photodynamic therapy, and induce ROS overgeneration to trigger CP sensitivity. Genetic tools, such as small interfering RNA (siRNA) can down-regulate molecular pathways such as HIF-1α and Nrf2 to promote ROS levels, leading to CP sensitivity. Considering the relationship between ROS and CP chemotherapy, and translating these findings to clinic can pave the way for effective treatment of cancer patients.

Ferroptosis Resistance in Cancer: An Emerging Crisis of New Hope

Ferroptosis, a new mode of nonapoptotic cell death, is increasingly recognized as a new hope in overcoming resistance to chemotherapy in cancer. Both canonical and noncanonical pathways can trigger ferroptosis execution via an iron-dependent lethal lipid peroxidation manner. However, growing evidence has shown that some cancer cells can survive ferroptotic stress through metabolic remodeling as regards iron metabolism, anti-oxidative systems, and lipid metabolism. In addition to the well-known roles of the XC−/glutathione/glutathione peroxidase 4 (XC‐/GSH/GPX4) axis in blocking ferroptosis, several recently identified pathways, including the Mevalonate-ferroptosis suppressor protein 1 (MVA-FSP1) axis, the GTP cyclohydrolase 1-Tetrahydrobiopterin (GCH1-BH4) axis, the peroxisome-ether-phospholipid axis, the acyl-CoA synthetase long-chain family member 3-monounsaturated fatty acids (ACSL3-MUFA) axis, and the Liver kinase B1-AMP-activated protein kinase (LKB1-AMPK) axis, can negatively regulate susceptibility to ferroptosis. Prominin-2, a newly identified ferroptosis-modulating protein, also drives cancer cells to escape from ferroptosis induction. These findings collectively led to major challenges and opportunities in the development of novel therapies that target the ferroptosis resistance of cancer cells.SignificanceFerroptosis is a lethal consequence of accumulated lipid peroxidation catalyzed by ferrous iron and oxygen. This unique cell death process appears to involve many diseases, such as neurodegeneration, ischemia/reperfusion injury, kidney disease, and a druggable target in therapy-resistant cancers. There is great expectation of being able to exploit ferroptosis for the treatment of as yet incurable diseases. However, the state of ferroptosis susceptibility is linked to various regulation pathways. This perspective aims to integrate the current understanding of signaling mechanisms for ferroptotic defenses and facilitates movement toward novel cancer therapeutic strategies.

NRF2-GPX4/SOD2 axis imparts resistance to EGFR-tyrosine kinase inhibitors in non-small-cell lung cancer cells

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have achieved satisfactory clinical effects in the therapy of non-small cell lung cancer (NSCLC), but acquired resistance limits their clinical application. NRF2 has been shown to enhance the resistance to apoptosis induced by radiotherapy and some chemotherapy. In this study, we investigated the role of NRF2 in resistance to EGFR-TKIs. We showed that NRF2 protein levels were markedly increased in a panel of EGFR-TKI-resistant NSCLC cell lines due to slow degradation of NRF2 protein. NRF2 knockdown overcame the resistance to EGFR-TKIs in HCC827ER and HCC827GR cells. Furthermore, we demonstrated that NRF2 imparted EGFR-TKIs resistance in HCC827 cells via upregulation of GPX4 and SOD2, and suppression of GPX4 and SOD2 reversed resistance to EGFR-TKIs. Thus, we conclude that targeting NRF2-GPX4/SOD2 pathway is a potential strategy for overcoming resistance to EGFR-TKIs.

Ferroptosis: Biochemistry and Biology in Cancers

The challenge of eradicating cancer is that cancer cells possess diverse mechanisms to protect themselves from clinical strategies. Recently, ferroptosis has been shown to exhibit appreciable anti-tumor activity that could be harnessed for cancer therapy in the future. Ferroptosis is an iron-dependent form of regulated cell death that is characterized by the oxidization of polyunsaturated fatty acids (PUFAs) and accumulation of lipid peroxides. Ferroptosis has been closely correlated with numerous biological processes, such as amino acid metabolism, glutathione metabolism, iron metabolism, and lipid metabolism, as well as key regulators including GPX4, FSP1, NRF2, and p53. Although ferroptosis could be involved in killing various cancer cells, multiple aspects of this phenomenon remain unresolved. In this review, we summarize the biochemistry and biology of ferroptosis in diverse cancers and discuss the potential mechanisms of ferroptosis, which might pave the way for guiding cancer therapeutics.

Emerging mechanisms and targeted therapy of ferroptosis in cancer

Ferroptosis is an iron- and lipid reactive oxygen species (ROS)-dependent form of programmed cell death that is distinct from other forms of regulatory cell death at the morphological, biological, and genetic levels. Emerging evidence suggests critical roles for ferroptosis in cell metabolism, the redox status, and various diseases, such as cancers, nervous system diseases, and ischemia-reperfusion injury, with ferroptosis-related proteins. Ferroptosis is inhibited in diverse cancer types and functions as a dynamic tumor suppressor in cancer development, indicating that the regulation of ferroptosis can be utilized as an interventional target for tumor treatment. Small molecules and nanomaterials that reprogram cancer cells to undergo ferroptosis are considered effective drugs for cancer therapy. Here, we systematically summarize the molecular basis of ferroptosis, the suppressive effect of ferroptosis on tumors, the effect of ferroptosis on cellular metabolism and the tumor microenvironment (TME), and ferroptosis-inducing agents for tumor therapeutics. An understanding of the latest progress in ferroptosis could provide references for proposing new potential targets for the treatment of cancers.

Regulation of ferroptosis by bioactive phytochemicals: Implications for medical nutritional therapy

Ferroptosis is an iron- and lipotoxicity-dependent regulated cell death that has been implicated in various diseases, such as cancer, neurodegeneration and stroke. The biosynthesis of phospholipids, coenzyme Q₁₀, and glutathione, and the metabolism of iron, amino acids and polyunsaturated fatty acid, are tightly associated with cellular sensitivity to ferroptosis. Up to now, only limited drugs targeting ferroptosis have been documented and exploring novel effective ferroptosis-modulating compound is needed. Natural bioactive products are conventional resources for drug discovery, and some of them have been clinically used against cancers and neurodegenerative diseases as dietary supplements or pharmaceutic agents. Notably, increasing evidence demonstrates that natural compounds, such as saponins, flavonoids and isothiocyanates, can either induce or inhibit ferroptosis, further expanding their therapeutic potentials. In this review, we highlight current advances of the emerging molecular mechanisms and disease relevance of ferroptosis. We also systematically summarize the regulatory effects of natural phytochemicals on ferroptosis, and clearly indicate that saponins, terpenoids and alkaloids induce ROS- and ferritinophagy-dependent ferroptosis, whereas flavonoids and polyphenols modulate iron metabolism and nuclear factor erythroid 2-related factor 2 (NRF2) signaling to inhibit ferroptosis. Finally, we explore their clinical applications in ferroptosis-related diseases, which may facilitate the development of their dietary usages as nutraceuticals.

Suppressing the KIF20A/NUAK1/Nrf2/GPX4 signaling pathway induces ferroptosis and enhances the sensitivity of colorectal cancer to oxaliplatin

Oxaliplatin resistance can develop in colorectal cancer (CRC), which may involve inhibition of ferroptosis, although further research is needed to understand this potential mechanism. We evaluated CRC cells with acquired oxaliplatin resistance (HCT116-Or) or congenital resistance (H716) to determine whether a ferroptosis inducer (RSL3) or inhibitor (liproxstatin-1) could modulate the effects of oxaliplatin. The results suggested that induction of ferroptosis could significantly reverse the oxaliplatin resistance of the CRC cells. Bioinformatic and cytobiological searches also revealed that KIF20A was highly expressed in the oxaliplatin-resistant cell lines and was strongly correlated with survival among CRC patients. Silencing KIF20A enhanced cellular sensitivity to oxaliplatin both in vivo and in vitro, and silencing KIF20A also suppressed NUAK1 activation, while a NUAK1 agonist (ETC-1002) could reverse the oxaliplatin sensitivity of KIF20A-silenced cells. Moreover, silencing NUAK1 up-regulated the expression of PP1β, down-regulated the phosphorylation of downstream GSK3βSer9, suppressed the nuclear import of Nrf2, inhibited the expression of a ferroptosis key negative regulatory protein (GPX4), and blocked cellular resistance. Applying a Nrf2 agonist (oltipraz) also reversed the oxaliplatin sensitivity of NUAK1-silenced cells. Therefore, cellular ferroptosis may be inhibited via the KIF20A/NUAK1/PP1β/GPX4 pathway in CRC cells, which may underly the resistance of CRC to oxaliplatin.