Nrf2-Keap1 pathway promotes cell proliferation and diminishes ferroptosis

Ferroptosis: A new therapeutic target for bladder cancer

Bladder cancer (BC) is the most frequent type of urinary system cancer. The prognosis of BC is poor due to high metastasis rates and multidrug resistance. Hence, development of novel therapies targeting BC cell death is urgently needed. As a novel cell death type with strong antitumor potential, ferroptosis has been investigated by many groups for its potential in BC treatment. As an iron-dependent cell death process, ferroptosis is characterized by excessive oxidative phospholipids. The molecular mechanisms of ferroptosis include iron overload and the system Xc-GSH-GPX4 signaling pathway. A recent study revealed that ferroptosis is involved in the metastasis, treatment, and prognosis of BC. Herein, in this review, we comprehensively summarize the mechanism of ferroptosis, address newly identified targets involved in ferroptosis, and discuss the potential of new clinical therapies targeting ferroptosis in BC.

NAC, NAC, Knockin' on Heaven's door: Interpreting the mechanism of action of N-acetylcysteine in tumor and immune cells

N-acetylcysteine (NAC) has been used as a direct scavenger of reactive oxygen species (hydrogen peroxide, in particular) and an antioxidant in cancer biology and immuno-oncology. NAC is the antioxidant drug most frequently employed in studies using tumor cells, immune cells, and preclinical mouse xenografts. Most studies use redox-active fluorescent probes such as dichlorodihydrofluorescein, hydroethidine, mitochondria-targeted hydroethidine, and proprietary kit-based probes (i.e., CellROX Green and CellROX Red) for intracellular detection of superoxide or hydrogen peroxide. Inhibition of fluorescence by NAC was used as a key experimental observation to support the formation of reactive oxygen species and redox mechanisms proposed for ferroptosis, tumor metastasis, and redox signaling in the tumor microenvironment. Reactive oxygen species such as superoxide and hydrogen peroxide stimulate or abrogate tumor cells and immune cells depending on multiple factors. Understanding the mechanism of antioxidants is crucial for interpretation of the results. Because neither NAC nor the fluorescent probes indicated above react directly with hydrogen peroxide, it is critically important to reinterpret the results to advance our understanding of the mechanism of action of NAC and shed additional mechanistic insight on redox-regulated signaling in tumor biology. To this end, this review is focused on how NAC could affect multiple pathways in cancer cells, including iron signaling, ferroptosis, and the glutathione-dependent antioxidant and redox signaling mechanism, and how NAC could inhibit oxidation of the fluorescent probes through multiple mechanisms.

Apolipoprotein C1 promotes glioblastoma tumorigenesis by reducing KEAP1/NRF2 and CBS-regulated ferroptosis

Glioblastoma (GBM), a malignant brain tumor, is a world-wide health problem because of its poor prognosis and high rates of recurrence and mortality. Apolipoprotein C1 (APOC1) is the smallest of apolipoproteins, implicated in many diseases. Recent studies have shown that APOC1 promotes tumorigenesis and development of several types of cancer. In this study we investigated the role of APOC1 in GBM tumorigenesis. Using in silico assays we showed that APOC1 was highly expressed in GBM tissues and its expression was closely related to GBM progression. We showed that APOC1 protein expression was markedly increased in four GBM cell lines (U251, U138, A172 and U87) compared to the normal brain glia cell lines (HEB, HA1800). In U251 cells, overexpression of APOC1 promoted cell proliferation, migration, invasion and colony information, which was reversed by APOC1 knockdown. APOC1 knockdown also markedly inhibited the growth of GBM xenografts in the ventricle of nude mice. We further demonstrated that APOC1 reduced ferroptosis by inhibiting KEAP1, promoting nuclear translocation of NRF2 and increasing expression of HO-1 and NQO1 in GBM cells. APOC1 also induced ferroptosis resistance by increasing cystathionine beta-synthase (CBS) expression, which promoted trans-sulfuration and increased GSH synthesis, ultimately leading to an increase in glutathione peroxidase-4 (GPX4). Thus, APOC1 plays a key role in GBM tumorigenesis, conferring resistance to ferroptosis, and may be a promising therapeutic target for GBM.

Ferroptosis and Its Potential Role in Glioma: From Molecular Mechanisms to Therapeutic Opportunities

Glioma is the most common intracranial malignant tumor, and the current main standard treatment option is a combination of tumor surgical resection, chemotherapy and radiotherapy. Due to the terribly poor five-year survival rate of patients with gliomas and the high recurrence rate of gliomas, some new and efficient therapeutic strategies are expected. Recently, ferroptosis, as a new form of cell death, has played a significant role in the treatment of gliomas. Specifically, studies have revealed key processes of ferroptosis, including iron overload in cells, occurrence of lipid peroxidation, inactivation of cysteine/glutathione antiporter system Xc- (xCT) and glutathione peroxidase 4 (GPX4). In the present review, we summarized the molecular mechanisms of ferroptosis and introduced the application and challenges of ferroptosis in the development and treatment of gliomas. Moreover, we highlighted the therapeutic opportunities of manipulating ferroptosis to improve glioma treatments, which may improve the clinical outcome.

MiR-129-3p regulates ferroptosis in the liver of Selenium-deficient broilers by targeting SLC7A11

Selenium (Se) has been proven to be an essential trace element for organism. Se deficiency in poultry can cause widespread damage, such as exudative diathesis. The liver is not only the main organ of metabolism, but also one of the organs with high Se content in organism. Recent studies have shown that solute carrier family 7 member 11 (SLC7A11) plays a key role in the negative regulation of ferroptosis. In order to explore the mechanism of Se deficiency induces liver ferroptosis in broilers, and the role of microRNAs (miRNAs) in this process, we divided broilers into 2 groups: control group (0.2 mg/kg Se) and Se deficiency group (0.03 mg/kg Se). Hematoxylin-Eosin staining detected liver tissue damage in broilers. Predicted and verified the targeting relationship between miR-129-3p and SLC7A11 through miRDB and dual luciferase report experiments. The genes related to ferroptosis were detected by qRT-PCR and Western Blot. The results showed that the expression level of miR-129-3p mRNA in Se-deficient liver was significantly increased. To understand whether the miR-129-3p/SLC7A11 axis could involve in the process of ferroptosis, our further research showed that overexpression of miR-129-3p could reduce the expression of SLC7A11 and its downstream GCL, GSS, and GPX4, thereby inducing ferroptosis. These data indicates that miR-129-3p affected ferroptosis under Se deficiency conditions through the SLC7A11 pathway. Our research provides a new perspective for the mechanism of Se deficiency on the liver damage.

Ferroptosis of Endothelial Cells in Vascular Diseases

Endothelial cells (ECs) line the inner surface of blood vessels and play a substantial role in vascular biology. Endothelial dysfunction (ED) is strongly correlated with the initiation and progression of many vascular diseases. Regulated cell death, such as ferroptosis, is one of the multiple mechanisms that lead to ED. Ferroptosis is an iron-dependent programmed cell death associated with various vascular diseases, such as cardiovascular, cerebrovascular, and pulmonary vascular diseases. This review summarized ferroptosis of ECs in vascular diseases and discussed potential therapeutic strategies for treating ferroptosis of ECs. In addition to lipid peroxidation inhibitors and iron chelators, a growing body of evidence showed that clinical drugs, natural products, and intervention of noncoding RNAs may also inhibit ferroptosis of ECs.

Iron-Sulfur Clusters: A Key Factor of Regulated Cell Death in Cancer

Iron-sulfur clusters are ancient cofactors that play crucial roles in myriad cellular functions. Recent studies have shown that iron-sulfur clusters are closely related to the mechanisms of multiple cell death modalities. In addition, numerous previous studies have demonstrated that iron-sulfur clusters play an important role in the development and treatment of cancer. This review first summarizes the close association of iron-sulfur clusters with cell death modalities such as ferroptosis, cuprotosis, PANoptosis, and apoptosis and their potential role in cancer activation and drug resistance. This review hopes to generate new cancer therapy ideas and overcome drug resistance by modulating iron-sulfur clusters.

[Progress of NRF2 Signaling Pathway in Promoting Proliferation of Non-small Cell Lung Cancer]

The morbidity and mortality of lung cancer ranks among the top cancers in the world. Non-small cell lung cancer (NSCLC) is the main pathological type of lung cancer, with limited treatment options and poor prognosis. The nuclear factor E2-related factor 2 (NRF2) signaling pathway is highly mutated and activated in NSCLC, and promotes the malignant progression of lung cancer through various mechanisms. NRF2-targeted therapy will provide new treatment strategies for patients with NSCLC. This article will review the basic structure and response pathways of the NRF2 pathway, the mechanism of NRF2 regulating lung cancer cell proliferation, and the research and development progress of NRF2 inhibitors.
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Ferroptosis: Shedding Light on Mechanisms and Therapeutic Opportunities in Liver Diseases

Cell death is a vital physiological or pathological phenomenon in the development process of the organism. Ferroptosis is a kind of newly-discovered regulated cell death (RCD), which is different from other RCD patterns, such as apoptosis, necrosis and autophagy at the morphological, biochemical and genetic levels. It is a kind of iron-dependent mode of death mediated by lipid peroxides and lipid reactive oxygen species aggregation. Noteworthily, the number of studies focused on ferroptosis has been increasing exponentially since ferroptosis was first found in 2012. The liver is the organ that stores the most iron in the human body. Recently, it was frequently found that there are different degrees of iron metabolism disorder and lipid peroxidation and other ferroptosis characteristics in various liver diseases. Numerous investigators have discovered that the progression of various liver diseases can be affected via the regulation of ferroptosis, which may provide a potential therapeutic strategy for clinical hepatic diseases. This review aims to summarize the mechanism and update research progress of ferroptosis, so as to provide novel promising directions for the treatment of liver diseases.

Ferroptosis and musculoskeletal diseases: “Iron Maiden” cell death may be a promising therapeutic target

Ferroptosis is a novel form of cell death precisely regulated by iron metabolism, antioxidant processes, and lipid metabolism that plays an irreplaceable role in the development of many diseases. Musculoskeletal disorders (MSKs), including osteoporosis, osteoarthritis, rheumatoid arthritis, intervertebral disc degeneration, sarcopenia, and rhabdomyolysis, have become one of the most common causes of disability and a major burden on public health and social care systems. The mechanism of ferroptosis in MSKs has recently been elucidated. In this review, we briefly introduce the ferroptosis mechanism and illustrate the pathological roles of ferroptosis in MSKs with a focus on how ferroptosis can be exploited as a promising treatment strategy. Notably, because the toxicity of compounds that inhibit or induce ferroptosis in other organs is largely unknown, ferroptosis appears to be a double-edged sword. We point out that more research is needed in the future to verify the therapeutic effects based on ferroptosis in MSKs.

Astaxanthin attenuates osteoarthritis progression via inhibiting ferroptosis and regulating mitochondrial function in chondrocytes

Ferroptosis is a novel form of regulated cell death that has a close association with mitochondrial dysfunction and is characterized by iron overload, the accumulation of reactive oxygen species (ROS), and lipid ROS. Chondrocytes ferroptosis accelerates the progression of osteoarthritis (OA). Astaxanthin (ATX) is a xanthophyll carotenoid that possesses anti-inflammatory and antioxidant properties and has been explored in research studies for the treatment of diabetes and cardiovascular disease. However, the role it plays in OA, particularly in chondrocyte ferroptosis, has not yet been reported. In this study, ferroptosis-related events were analyzed in rat chondrocytes in vitro. A surgical destabilized medial meniscus was performed for the establishment of in vivo OA model. The results showed that interleukin-1β (IL-1β) induced inflammatory injury in chondrocytes through the promotion of the expressions of inflammatory factors including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2). IL-1β triggered chondrocyte ferroptosis by increasing the levels of intracellular ROS, lipid ROS, iron, and mitochondrial iron and inhibiting the expressions of SLC7A11/glutathione peroxidase 4 (GPX4) and Ferritin. The above indices were ameliorated by ferrostatin-1 (Fer-1, a classic ferroptosis inhibitor) and ATX. Furthermore, Fer-1 and ATX rescued the IL-1β-induced down-regulating collagen type II (collagen Ⅱ) and up-regulating matrix metalloproteinase 13 (MMP13). Following treatment with IL-1β, mitochondrial membrane potential decreased and the mitochondrial membrane was broken. At the same time, the mitochondrion shrank, becoming deformed as the mitochondrial cristae reduced and became disrupted. These changes were entirely consistent with ferroptosis features. All the aforementioned phenomena were reversed by Fer-1 and ATX. In addition, intra-articular injection of Fer-1 and ATX delayed articular cartilage degradation and OA progression. This study demonstrated that IL-1β can induce inflammatory damage and ferroptosis in chondrocytes. Both Fer-1 and ATX have the ability to mitigate chondrocyte injury and osteoarthritis progression by inhibiting ferroptosis and the regulation of mitochondrial function. Targeting ferroptosis has the potential to be a promising future treatment method for OA.

Ferroptosis in glioma treatment: Current situation, prospects and drug applications

Ferroptosis is a regulatory form of iron-dependent cell death caused by the accumulation of lipid-based reactive oxygen species (ROS) and differs from apoptosis, pyroptosis, and necrosis. Especially in neoplastic diseases, the susceptibility of tumor cells to ferroptosis affects prognosis and is associated with complex effects. Gliomas are the most common primary intracranial tumors, accounting for disease in 81% of patients with malignant brain tumors. An increasing number of studies have revealed the particular characteristics of iron metabolism in glioma cells. Therefore, agents that target a wide range of molecules involved in ferroptosis may regulate this process and enhance glioma treatment. Here, we review the underlying mechanisms of ferroptosis and summarize the potential therapeutic options for targeting ferroptosis in glioma.

Potential of Kalanchoe pinnata as a Cancer Treatment Adjuvant and an Epigenetic Regulator

Cancer is a global public health problem that is related to different environmental and lifestyle factors. Although the combination of screening, prevention, and treatment of cancer has resulted in increased patient survival, conventional treatments sometimes have therapeutic limitations such as resistance to drugs or severe side effects. Oriental culture includes herbal medicine as a complementary therapy in combination with chemotherapy or radiotherapy. This study aimed to identify the bioactive ingredients in Kalanchoe pinnata, a succulent herb with ethnomedical applications for several diseases, including cancer, and reveal its anticancer mechanisms through a molecular approach. The herb contains gallic acid, caffeic acid, coumaric acid, quercetin, quercitrin, isorhamnetin, kaempferol, bersaldegenin, bryophyllin a, bryophyllin c, bryophynol, bryophyllol and bryophollone, stigmasterol, campesterol, and other elements. Its phytochemicals participate in the regulation of proliferation, apoptosis, cell migration, angiogenesis, metastasis, oxidative stress, and autophagy. They have the potential to act as epigenetic drugs by reverting the acquired epigenetic changes associated with tumor resistance to therapy-such as the promoter methylation of suppressor genes, inhibition of DNMT1 and DNMT3b activity, and HDAC regulation-through methylation, thereby regulating the expression of genes involved in the PI3K/Akt/mTOR, Nrf2/Keap1, MEK/ERK, and Wnt/β-catenin pathways. All of the data support the use of K. pinnata as an adjuvant in cancer treatment.

Targeting Ferroptosis by Ubiquitin System Enzymes: A Potential Therapeutic Strategy in Cancer

Ferroptosis is a novel type of regulated cell death driven by the excessive accumulation of iron-dependent lipid peroxidation. Therapy-resistant tumor cells, particularly those in the mesenchymal-like state and prone to metastasis, are highly susceptible to ferroptosis, suggesting that induction of ferroptosis in tumor cells is a promising strategy for cancer therapy. Although ferroptosis is regulated at various levels, ubiquitination is key to post-translational regulation of ferroptotic cell death. E3 ubiquitin ligases (E3s) and deubiquitinating enzymes (DUBs) are the most remarkable ubiquitin system enzymes, whose dysregulation accounts for the progression of multiple cancers. E3s are involved in the attachment of ubiquitin to substrates for their degradation, and this process is reversed by DUBs. Accumulating evidence has highlighted the important role of ubiquitin system enzymes in regulating the sensitivity of ferroptosis. Herein, we will portray the regulatory networks of ferroptosis mediated by E3s or DUBs and discuss opportunities and challenges for incorporating this regulation into cancer therapy.

Exploring the role of Nrf2 signaling in glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the most aggressive glial cell tumors in adults. Although current treatment options for GBM offer some therapeutic benefit, median survival remains poor and does not generally exceed 14 months. Several genes, such as isocitrate dehydrogenase (IDH) enzyme and O6-methylguanine-DNA methyltransferase (MGMT), have been implicated in pathogenesis of the disease. Treatment is often adapted based on the presence of IDH mutations and MGMT promoter methylation status. Recent GBM cell line studies have associated Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) expression with high-grade tumors. Increased Nrf2 expression is often found in tumors with IDH-1 mutations. Nrf2 is an important transcription factor with anti-apoptotic, antioxidative, anti-inflammatory, and proliferative properties due to its complex interactions with multiple regulatory pathways. In addition, evidence suggests that Nrf2 promotes  GBM cell survival in hypoxic environment,by up-regulating hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF). Downregulation of Nrf2 has been shown to improve GBM sensitivity to chemotherapy drugs such as Temozolomide. Thus, Nrf2 could be a key regulator of GBM pathways and potential therapeutic target.  Further research efforts exploring an interplay between Nrf2 and major molecular signaling mechanisms could offer novel GBM drug candidates with a potential to significantly improve patients prognosis.

MicroRNA‑27a Aggravates Ferroptosis during early Ischemic Stroke of Rats Through Nrf2

Ischaemic stroke (IS) is characterized by high morbidity, disability and mortality and lacks effective solutions. MiRNA-27a has been implicated in ferroptosis, but evidence that miRNA-27a regulates ferroptosis in ischaemic stroke is lacking. Nrf2 could reduce brain tissue injury in ischaemic stroke and resist ferroptosis. The current study aimed to investigate the relationship between miRNA-27a/Nrf2 and ferroptosis in ischaemic stroke. In this study, IS was simulated using a permanent middle cerebral artery occlusion (pMCAO) model. The degree of brain tissue injury was assessed by conducting TTC staining and neurological function scoring. MiRNA-27a expression levels were altered via the intracerebroventricular injection of miRNA‑27a agonist or antagonist. Glutathione peroxidase 4 (GPX4), glutathione (GSH), Fe and malondialdehyde (MDA) are considered biomarkers for ferroptosis. The expression of GPX4 and Nrf2 was analysed by Western blot assay. The GSH, Fe and MDA contents were detected by detection kits. We found that the expression levels of Fe and MDA were increased, while GPX4 and GSH were decreased in the pMCAO groups compared with the control group. These results indicated that ferroptosis intensified over time during IS. In addition, the miRNA‑27a agonist significantly aggravated ferroptosis and reduced neurological function scores compared with those of the control group. Subsequently, a luciferase reporter gene system verified the targeted binding of miRNA‑27a to Nrf2. The results showed that miRNA‑27a inhibited Nrf2 in a targeted manner, which also exacerbated the extent of ferroptosis. However, the miRNA‑27a antagonist reversed the miR‑27a agonist‑mediated effects. Therefore, the present study indicated that miRNA‑27a may aggravate brain tissue ferroptosis during ischaemic stroke, potentially by inhibiting Nrf2.

LncRNAs regulate ferroptosis to affect diabetes and its complications

Worldwide, the rapid increase in the incidence of diabetes and its complications poses a serious threat to human health. Ferroptosis, which is a new nonapoptotic form of cell death, has been proven to be closely related to the occurrence and development of diabetes and its complications. In recent years, lncRNAs have been confirmed to be involved in the occurrence and development of diabetes and play an important role in regulating ferroptosis. An increasing number of studies have shown that lncRNAs can affect the occurrence and development of diabetes and its complications by regulating ferroptosis. Therefore, lncRNAs have great potential as therapeutic targets for regulating ferroptosis-mediated diabetes and its complications. This paper reviewed the potential impact and regulatory mechanism of ferroptosis on diabetes and its complications, focusing on the effects of lncRNAs on the occurrence and development of ferroptosis-mediated diabetes and its complications and the regulation of ferroptosis-inducing reactive oxygen species, the key ferroptosis regulator Nrf2 and the NF-κB signaling pathway to provide new therapeutic strategies for the development of lncRNA-regulated ferroptosis-targeted drugs to treat diabetes.

Ferroptosis: A novel therapeutic strategy and mechanism of action in glioma

Glioma is the most common malignant tumor of the central nervous system and resistance is easily developed to chemotherapy drugs during the treatment process, resulting in high mortality and short survival in glioma patients. Novel therapeutic approaches are urgently needed to improve the therapeutic efficacy of chemotherapeutic drugs and to improve the prognosis of patients with glioma. Ferroptosis is a novel regulatory cell death mechanism that plays a key role in cancer, neurodegenerative diseases, and other diseases. Studies have found that ferroptosis-related regulators are closely related to the survival of patients with glioma, and induction of ferroptosis can improve glioma resistance to chemotherapy drugs. Therefore, induction of tumor cell ferroptosis may be an effective therapeutic strategy for glioma. This review summarizes the relevant mechanisms of ferroptosis, systematically summarizes the key role of ferroptosis in the treatment of glioma and outlines the relationship between ferroptosis-related ncRNAs and the progression of glioma.

System Xc−/GSH/GPX4 axis: An important antioxidant system for the ferroptosis in drug-resistant solid tumor therapy

The activation of ferroptosis is a new effective way to treat drug-resistant solid tumors. Ferroptosis is an iron-mediated form of cell death caused by the accumulation of lipid peroxides. The intracellular imbalance between oxidant and antioxidant due to the abnormal expression of multiple redox active enzymes will promote the produce of reactive oxygen species (ROS). So far, a few pathways and regulators have been discovered to regulate ferroptosis. In particular, the cystine/glutamate antiporter (System Xc−), glutathione peroxidase 4 (GPX4) and glutathione (GSH) (System Xc−/GSH/GPX4 axis) plays a key role in preventing lipid peroxidation-mediated ferroptosis, because of which could be inhibited by blocking System Xc−/GSH/GPX4 axis. This review aims to present the current understanding of the mechanism of ferroptosis based on the System Xc−/GSH/GPX4 axis in the treatment of drug-resistant solid tumors.

The role of ferroptosis in esophageal cancer

Esophageal cancer is one of the most common cancers with high mortality rate around the world. Although the treatment strategy of this disease has made great progress, the prognosis of advanced patients is not ideal. Ferroptosis, a novel regulatory cell death model, that is different from traditional apoptosis and characterized by increased Fenton reaction mediated by intracellular free iron and lipid peroxidation of cell membrane. Ferroptosis has been proved to be closely linked to a variety of diseases, especially cancer. This review aims to summarize the core mechanism of ferroptosis in esophageal cancer, the regulation of ferroptosis signaling pathway and its current application. At the same time, we emphasize the potential and prospect of ferroptosis in the treatment of esophageal cancer. Collectively, targeting ferroptosis pathway may provide new insights into the diagnosis, treatment and prognosis of esophageal cancer.

Emerging role of ferroptosis in glioblastoma: Therapeutic opportunities and challenges

Glioblastoma (GBM) is the most common malignant craniocerebral tumor. The treatment of this cancer is difficult due to its high heterogeneity and immunosuppressive microenvironment. Ferroptosis is a newly found non-apoptotic regulatory cell death process that plays a vital role in a variety of brain diseases, including cerebral hemorrhage, neurodegenerative diseases, and primary or metastatic brain tumors. Recent studies have shown that targeting ferroptosis can be an effective strategy to overcome resistance to tumor therapy and immune escape mechanisms. This suggests that combining ferroptosis-based therapies with other treatments may be an effective strategy to improve the treatment of GBM. Here, we critically reviewed existing studies on the effect of ferroptosis on GBM therapies such as chemotherapy, radiotherapy, immunotherapy, and targeted therapy. In particular, this review discussed the potential of ferroptosis inducers to reverse drug resistance and enhance the sensitivity of conventional cancer therapy in combination with ferroptosis. Finally, we highlighted the therapeutic opportunities and challenges facing the clinical application of ferroptosis-based therapies in GBM. The data generated here provide new insights and directions for future research on the significance of ferroptosis-based therapies in GBM.

The molecular mechanisms of ferroptosis and its role in glioma progression and treatment

Ferroptosis is one of the programmed modes of cell death that has attracted widespread attention recently and is capable of influencing the developmental course and prognosis of many tumors. Glioma is one of the most common primary tumors of the central nervous system, but effective treatment options are very limited. Ferroptosis plays a critical role in the glioma progression, affecting tumor cell proliferation, angiogenesis, tumor necrosis, and shaping the immune-resistant tumor microenvironment. Inducing ferroptosis has emerged as an attractive strategy for glioma. In this paper, we review ferroptosis-related researches on glioma progression and treatment.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe²⁺, Ca²⁺, Zn²⁺, etc.) and anions (Cl^-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

The protective mechanism of protein kinase R to inhibit neuronal ferroptosis in cerebral injury from subarachnoid hemorrhage

PURPOSE

To investigate the role and mechanism of protein kinase R (PKR) in subarachnoid hemorrhage (SAH)-mediated ferroptosis.

METHODS

A rat SAH model was constructed and treated with PKR inhibitor C16 to observe SAH and neurological impairment in rats and to detect malonaldehyde (MDA), iron ions content, ferritin heavy polypeptide 1 (FTH1) and glutathione peroxidase 4 (GPX4), and other related ferroptosis indicators in brain tissue. RNA sequencing analysis was used to investigate the mechanism of PKR, affecting the ferroptosis network of SAH.

RESULTS

SAH caused severe fundic hemorrhage, neurological impairment, MDA and iron ion accumulation, and significant decrease in GPX4 and FTH1 levels in rats. C16 treatment significantly improved the above signs caused by SAH. By RNA-seq analysis, brain tissue of SAH-treated rats with SAH and C16 differentially expressed mRNA target genes enriched in stress response and organic developmental signaling pathways.

CONCLUSION

Inhibition of PKR may improve cerebral injury after SAH by inhibiting ferroptosis, and RNA sequencing staged its mechanism of action may be related to the stress response.

Role of Nrf2 in bisphenol effects: a review study

Bisphenols (BPs), the main endocrine-disrupting chemicals used in polycarbonate plastics, epoxy-phenol resins, and some other manufacturers, have been interestingly focused to find their toxic effects in recent years. Due to the strong relation between bisphenols and some crucial receptors such as ERs, AR, glucocorticoid receptor, THRs, ERRs, hPXR, AhR, and etcetera, the disrupting and oncogenic role of these chemicals on reproductive, respiratory, and circulatory systems and a broad group of body tissues have been investigated. BPs induce oxidant enzymes, exert antioxidant enzymes from body cells, and result in the expression of proinflammatory genes, leading to cell apoptosis and inflammation. To maintain the homeostasis of human body cells, Nrf2, the key regulator of oxidative stress (Ashrafizadeh et al., 2020a; Ashrafizadeh et al., 2020c; Boroumand et al., 2018), confronts BP-induced ROS and RNS through the activation of antioxidant enzymes such as SOD1/2, CAT, GSH, GPX, HO-1, and etcetera. Chemicals and drugs such as LUT, NAC, GEN, L-NMMA, Ph₂Se₂, and GE can regulate the interactions between BPs and Nrf2. Despite the vital role of controlled levels of Nrf2 as an anti-inflammatory and antiapoptotic element, the uncontrolled activity of this transcription factor could lead to cell proliferation and tumorigenesis through NQO1, SLC7a11, Gclm, HMOX1, NQO1 gene activation, and some other genes. To avoid the excessive activity of Nrf2, some protein complexes like CUL3-RBX1-Keap1 (as the primary regulator), β-TrCP, and WDR23 regulate Nrf2's function. It is necessary to note that BPA, as the most famous member, is further reviewed due to its resemblance to the bisphenol family to each other.

Normal and Pathological NRF2 Signalling in the Central Nervous System

The nuclear factor erythroid 2-related factor 2 (NRF2) was originally described as a master regulator of antioxidant cellular response, but in the time since, numerous important biological functions linked to cell survival, cellular detoxification, metabolism, autophagy, proteostasis, inflammation, immunity, and differentiation have been attributed to this pleiotropic transcription factor that regulates hundreds of genes. After 40 years of in-depth research and key discoveries, NRF2 is now at the center of a vast regulatory network, revealing NRF2 signalling as increasingly complex. It is widely recognized that reactive oxygen species (ROS) play a key role in human physiological and pathological processes such as ageing, obesity, diabetes, cancer, and neurodegenerative diseases. The high oxygen consumption associated with high levels of free iron and oxidizable unsaturated lipids make the brain particularly vulnerable to oxidative stress. A good stability of NRF2 activity is thus crucial to maintain the redox balance and therefore brain homeostasis. In this review, we have gathered recent data about the contribution of the NRF2 pathway in the healthy brain as well as during metabolic diseases, cancer, ageing, and ageing-related neurodegenerative diseases. We also discuss promising therapeutic strategies and the need for better understanding of cell-type-specific functions of NRF2 in these different fields.

Low ferroptosis score predicts chemotherapy responsiveness and immune-activation in colorectal cancer

BACKGROUND

Existing studies for ferroptosis and prognosis in colorectal cancer (CRC) were limited. In this study, we aim to investigate the prognostic role of ferroptosis markers in patients with CRC and exploration of its micro-environmental distributions.

METHODS

Immunohistochemical staining was performed for CRC patients' tissue microarray. Selection and prognostic validation of markers were based on mRNA data from the cancer genome atlas (TCGA) database. Gene Set Enrichment Analysis (GSEA) was performed to indicate relative immune landmarks and hallmarks. Ferroptosis and immune contexture were examined by CIBERSORT. Survival outcomes were analyzed by Kaplan-Meier analysis and cox analysis.

RESULTS

A panel of 42 genes was selected. Through mRNA expression difference and prognosis analysis, GPX4, NOX1 and ACSL4 were selected as candidate markers. By IHC, increased GPX4, decreased NOX1 and decreased FACL4 indicate poor prognosis and worse clinical characteristics. Ferroptosis score based on GPX4, NOX1 and ACSL4 was constructed and validated with high C-index. Low ferroptosis score can also demonstrate the better progression free survival and better adjuvant chemotherapy (ACT) responsiveness. Moreover, tumor with low ferroptosis score tend to be infiltrated with more CD4+ T cells, CD8+ T cells and less M1 macrophage. Finally, we found that IFN-γ was potentially the central molecule at the crossroad between ferroptosis and onco-immune response.

CONCLUSION

Ferroptosis plays important role on CRC tumor progression, ACT response and prognosis. Ferroptosis contributes to immune-supportive responses and IFN-γ was the central molecule for this process.

Salvianolate ameliorates renal tubular injury through the Keap1/Nrf2/ARE pathway in mouse kidney ischemia-reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Acute kidney injury (AKI) is a common clinical disease characterized by rapid loss of renal function. Salvianolate is a prescribed Chinese medicine derived from traditional Chinese medicine Salvia miltiorrhiza bunge that possesses many pharmacological effects, the active components extracted from Salvia miltiorrhiza bunge have been proved to protect ischemia-reperfusion (I/R)-AKI.

AIM OF THE STUDY

This study aims to validate the therapeutic effect of SAL on I/R-AKI, and explore its potential pharmacological mechanism.

MATERIALS AND METHODS

Mice were pretreated with/without salvianolate (10, 30, and 90 mg/kg) before renal ischemia-reperfusion operation. Serum creatinine, BUN, and H&E staining were performed to evaluate renal function. Immunofluorescence analysis was conducted to measure renal tubular injury including inflammatory factors and peroxide level. Apoptosis of the kidney tissues was determined by TUNEL assay. Keap1-Nrf2-ARE and apoptosis signaling pathways were measured by Western blot, RT-PCR, and YO-PRO-1 staining in kidneys or NRK52E cells.

RESULTS

Pretreatment with SAL effectively alleviated renal function and ameliorated epithelial tubular injury, oxidative stress, and inflammatory response. Furthermore, the mechanistic study demonstrated that the SAL exerts anti-apoptotic effects through activation of the Keap1-Nrf2-ARE signaling pathway in renal tubular cells.

CONCLUSION

These findings indicate the therapeutic benefit of salvianolate in the protection of renal injury from ischemia-reperfusion, and strengthen the evidence for the AKI treatment strategy by the anti-oxidative stress response, suggesting that SAL may be a potential agent for the treatment of AKI.

High levels of NRF2 sensitize temozolomide-resistant glioblastoma cells to ferroptosis via ABCC1/MRP1 upregulation

Glioblastoma patients have a poor prognosis mainly due to temozolomide (TMZ) resistance. NRF2 is an important transcript factor involved in chemotherapy resistance due to its protective role in the transcription of genes involved in cellular detoxification and prevention of cell death processes, such as ferroptosis. However, the relation between NRF2 and iron-dependent cell death in glioma is still poorly understood. Therefore, in this study, we analyzed the role of NRF2 in ferroptosis modulation in glioblastoma cells. Two human glioblastoma cell lines (U251MG and T98G) were examined after treatment with TMZ, ferroptosis inducers (Erastin, RSL3), and ferroptosis inhibitor (Ferrostatin-1). Our results demonstrated that T98G was more resistant to chemotherapy compared to U251MG and showed elevated levels of NRF2 expression. Interestingly, T98G revealed higher sensitivity to ferroptosis, and significant GSH depletion upon system xc^- blockage. NRF2 silencing in T98G cells (T98G-shNRF2) significantly reduced the viability upon TMZ treatment. On the other hand, T98G-shNRF2 was resistant to ferroptosis and reverted intracellular GSH levels, indicating that NRF2 plays a key role in ferroptosis induction through GSH modulation. Moreover, silencing of ABCC1, a well-known NRF2 target that diminishes GSH levels, has demonstrated a similar collateral sensitivity. T98G-siABCC1 cells were more sensitive to TMZ and resistant to Erastin. Furthermore, we found that NRF2 positively correlates with ABCC1 expression in tumor tissues of glioma patients, which can be associated with tumor aggressiveness, drug resistance, and poor overall survival. Altogether, our data indicate that high levels of NRF2 result in collateral sensitivity on glioblastoma via the expression of its pro-ferroptotic target ABCC1, which contributes to GSH depletion when the system xc^- is blocked by Erastin. Thus, ferroptosis induction could be an important therapeutic strategy to reverse drug resistance in gliomas with high NRF2 and ABCC1 expression.

The Potential Key Role of the NRF2/NQO1 Pathway in the Health Effects of Arsenic Pollution on SCC

Arsenic is widely present in nature and is a common environmental poison that seriously damages human health. Chronic exposure to arsenic is a major environmental poisoning factor that promotes cell proliferation and leads to malignant transformation. However, its molecular mechanism remains unclear. In this study, we found that arsenite can promote the transformation of immortalized human keratinocyte cells (HaCaT) from the G0/G1 phase to S phase and demonstrated malignant phenotypes. This phenomenon is accompanied by obviously elevated levels of NRF2, NQO1, Cyclin E, and Cyclin-dependent kinase 2 (CDK2). Silencing the NRF2 expression with small interfering RNA (siRNA) in arsenite-transformed (T-HaCaT) cells was shown to reverse the malignant phenotype. Furthermore, the siRNA silencing of NQO1 significantly decreased the levels of the cyclin E-CDK2 complex, inhibiting the G0/G1 to S phase cell cycle progression and transformation to the T-HaCaT phenotypes. Thus, we hypothesized that the NRF2/NQO1 pathway played a key role in the arsenite-induced malignancy of HaCaT cells. By increasing the expression of Cyclin E-CDK2, the NRF2/NQO1 pathway can affect cell cycle progression and cell proliferation. A new common health effect mechanism of arsenic carcinogenesis has been identified; thus, it would contribute to the development of novel treatments to prevent and treat skin cancer caused by arsenic.

Entacapone alleviates acute kidney injury by inhibiting ferroptosis

Acute kidney injury (AKI) is a common clinical problem and an efficacious treatment is lacking. Ferroptosis, a newly discovered type of programmed cell death, has been reported to alleviate renal tubular injury in ischemia/reperfusion-induced acute kidney injury (I/R-AKI). Entacapone is a specific inhibitor of catechol-O-methyltransferase, which is used as an adjuvant drug against Parkinson's disease. We demonstrated that entacapone prevents renal I/R injury by inhibiting ferroptosis. Compared with a sham group, entacapone treatment mitigated I/R-induced pathological alterations, improved renal function, and inhibited ferroptosis. In HK-2 cells, entacapone treatment significantly reduced the lipid peroxidation and iron accumulation induced by the ferroptosis inducers erastin and RSL3, and significantly regulated expression of ferroptosis-related proteins. Entacapone upregulates p62 expression and affects the p62-KEAP1-NRF2 pathway, thereby upregulating nuclear translocation of NRF2. This action results in increased expression of the downstream SLC7A11, and significant suppression of oxidative stress and ferroptosis. Our results identify entacapone as a ferroptosis inhibitor that enhances antioxidant capacity. Entacapone may serve as a novel strategy to improve treatment of, and recovery from, I/R-AKI.

Shikonin Could Be Used to Treat Tubal Pregnancy via Enhancing Ferroptosis Sensitivity

Background

Albeit oxidative stress has been implied in the pathogenesis of tubal pregnancy (TP), there are scant data to suggest that ferroptosis occurs in TP. Shikonin plays a pivotal role in redox status, but whether it can regulate ferroptosis to treat TP remains unknown.

Methods

We collected and analyzed ferroptosis-related indices from the villous tissue (VT) of women suffering from TP and from women with a normal pregnancy. In vitro, we used shikonin and/or RAS-selective lethal 3 (RSL3) to intervene HTR-8/SVneo cells and further detected ferroptosis indices and cell functions. Finally, the expression of the nuclear factor erythroid 2-related factor 2 (Nrf2) is pharmacologically activated to explore the effect of Nrf2 on shikonin regulating ferroptosis.

Results

Increased malondialdehyde content, reduced levels of glutathione and glutathione peroxidase (GPx), and upregulated protein expression which promoted ferroptosis were observed in the VT of TP patients, suggesting that ferroptosis occurred during TP. In vitro, shikonin enhanced ferroptosis sensitivity in HTR-8/SVneo cells induced by RSL3 via amplifying lipid peroxidation, which mainly included increasing cellular reactive oxygen species (ROS), lipid ROS and Fe²⁺ level. RSL3 and/or shikonin inhibited Nrf2 and downregulated protein expression of SLC7A11 and GPx4 caused by RSL3 + shikonin co-treatment, which could be reversed under activation of Nrf2. Hence, shikonin facilitated lipid peroxidation by inhibiting Nrf2 signaling. Additionally, shikonin and/or RSL3 potently inhibited the invasion and migration of HTR-8/SVneo cells.

Conclusion

This study firstly showed that ferroptosis may be involved in TP pathogenesis and shikonin potentially targeted ferroptosis to treat TP.

Ferroptosis: Opportunities and Challenges in Treating Endometrial Cancer

Ferroptosis, a new way of cell death, is involved in many cancers. A growing number of studies have focused on the unique role of ferroptosis on endometrial cancer. In this study, we made a comprehensive review of the relevant articles published to get deep insights in the association of ferroptosis with endometrial cancer and to present a summary of the roles of different ferroptosis-associated genes. Accordingly, we made an evaluation of the relationships between the ferroptosis-associated genes and TNM stage, tumor grade, histological type, primary therapy outcome, invasion and recurrence of tumor, and accessing the different prognosis molecular typing based on ferroptosis-associated genes. In addition, we presented an introduction of the common drugs, which targeted ferroptosis in endometrial cancer. In so doing, we clarified the opportunities and challenges of ferroptosis activator application in treating endometrial cancer, with a view to provide a novel approach to the disease.

RNA demethylase ALKBH5 regulates hypopharyngeal squamous cell carcinoma ferroptosis by posttranscriptionally activating NFE2L2/NRF2 in an m6 A-IGF2BP2-dependent manner

Background

Having emerged as the most abundant posttranscriptional internal mRNA modification in eukaryotes, N6‐methyladenosine (m⁶A) has attracted tremendous scientific interest in recent years. However, the functional importance of the m⁶A methylation machinery in ferroptosis regulation in hypopharyngeal squamous cell carcinoma (HPSCC) remains unclear.

Methods

We herein performed bioinformatic analysis, cell biological analyses, transcriptome‐wide m⁶A sequencing (m⁶A‐seq, MeRIP‐seq), RNA sequencing (RNA‐seq), and RNA immunoprecipitation sequencing (RIP‐seq), followed by m⁶A dot blot, MeRIP‐qPCR, RIP‐qPCR, and dual‐luciferase reporter assays.

Results

The results revealed that ALKBH5‐mediated m⁶A demethylation led to the posttranscriptional inhibition of NFE2L2/NRF2, which is crucial for the regulation of antioxidant molecules in cells, at two m⁶A residues in the 3′‐UTR. Knocking down ALKBH5 subsequently increased the expression of NFE2L2/NRF2 and increased the resistance of HPSCC cells to ferroptosis. In addition, m⁶A‐mediated NFE2L2/NRF2 stabilization was dependent on the m⁶A reader IGF2BP2. We suggest that ALKBH5 dysregulates NFE2L2/NRF2 expression in HPSCC through an m⁶A‐IGF2BP2‐dependent mechanism.

Conclusion

Together, these results have revealed an association between the ALKBH5‐NFE2L2/NRF2 axis and ferroptosis, providing insight into the functional importance of reversible mRNA m⁶A methylation and its modulators in HPSCC.

BH3 mimetic drugs cooperate with Temozolomide, JQ1 and inducers of ferroptosis in killing glioblastoma multiforme cells

Glioblastoma multiforme (GBM) is the most common and aggressive form of brain cancer, with treatment options often constrained due to inherent resistance of malignant cells to conventional therapy. We investigated the impact of triggering programmed cell death (PCD) by using BH3 mimetic drugs in human GBM cell lines. We demonstrate that co-targeting the pro-survival proteins BCL-XL and MCL-1 was more potent at killing six GBM cell lines compared to conventional therapy with Temozolomide or the bromodomain inhibitor JQ1 in vitro. Enhanced cell killing was observed in U251 and SNB-19 cells in response to dual treatment with TMZ or JQ1 combined with a BCL-XL inhibitor, compared to single agent treatment. This was reflected in abundant cleavage/activation of caspase-3 and cleavage of PARP1, markers of apoptosis. U251 and SNB-19 cells were more readily killed by a combination of BH3 mimetics targeting BCL-XL and MCL-1 as opposed to dual treatment with the BCL-2 inhibitor Venetoclax and a BCL-XL inhibitor. The combined loss of BAX and BAK, the essential executioners of intrinsic apoptosis, rendered U251 and SNB-19 cells refractory to any of the drug combinations tested, demonstrating that apoptosis is responsible for their killing. In an orthotopic mouse model of GBM, we demonstrate that the BCL-XL inhibitor A1331852 can penetrate the brain, with A1331852 detected in both tumour and healthy brain regions. We also investigated the impact of combining small molecule inducers of ferroptosis, erastin and RSL3, with BH3 mimetic drugs. We found that a BCL-XL or an MCL-1 inhibitor potently cooperates with inducers of ferroptosis in killing U251 cells. Overall, these findings demonstrate the potential of dual targeting of distinct PCD signalling pathways in GBM and may guide the utility of BCL-XL inhibitors and inducers of ferroptosis with standard of care treatment for improved therapies for GBM.

Sipeimine ameliorates PM2.5-induced lung injury by inhibiting ferroptosis via the PI3K/Akt/Nrf2 pathway: A network pharmacology approach

Fine particulate matter (PM2.5) exposure can cause lung injury and a large number of respiratory diseases. Sipeimine is a steroidal alkaloid isolated from Fritillaria roylei which has been associated with anti-inflammatory, antitussive and antiasthmatic properties. In this study, we explored the potential effects of sipeimine against PM2.5-induced lung injury in Sprague Dawley rats. Sipeimine alleviated lung injury caused by PM2.5 and decreased pulmonary edema, inflammation and the levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the bronchoalveolar lavage fluid. In addition, sipeimine upregulated the glutathione (GSH) expression and downregulated the expression of 4-hydroxynonenal (4-HNE), tissue iron and malondialdehyde (MDA). The downregulation of proteins involved in ferroptosis, including nuclear factor E2-related factor 2 (Nrf2), glutathione peroxidase 4 (GPX4), heme oxygenase-1 (HO-1) and solute carrier family 7 member 11 (SLC7A11) was reversed by sipeimine. The administration of RSL3, a potent ferroptosis-triggering agent, blocked the effects of sipeimine. Using network pharmacology, we found that the effects of sipeimine were presumably mediated through the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. A PI3K inhibitor (LY294002) blocked the PI3K/Akt signaling pathway and reversed the effects of sipeimine. Overall, this study suggested that the protective effect of sipeimine against PM2.5-induced lung injury was mainly mediated through the PI3K/Akt pathway, ultimately leading to a reduction in ferroptosis.

Pharmacological targets for the induction of ferroptosis: Focus on Neuroblastoma and Glioblastoma

Neuroblastomas are the main extracranial tumors that affect children, while glioblastomas are the most lethal brain tumors, with a median survival time of less than 12 months, and the prognosis of these tumors is poor due to multidrug resistance. Thus, the development of new therapies for the treatment of these types of tumors is urgently needed. In this context, a new type of cell death with strong antitumor potential, called ferroptosis, has recently been described. Ferroptosis is molecularly, morphologically and biochemically different from the other types of cell death described to date because it continues in the absence of classical effectors of apoptosis and does not require the necroptotic machinery. In contrast, ferroptosis has been defined as an iron-dependent form of cell death that is inhibited by glutathione peroxidase 4 (GPX4) activity. Interestingly, ferroptosis can be induced pharmacologically, with potential antitumor activity in vivo and eventual application prospects in translational medicine. Here, we summarize the main pathways of pharmacological ferroptosis induction in tumor cells known to date, along with the limitations of, perspectives on and possible applications of this in the treatment of these tumors.

The Role of SLC7A11 in Cancer: Friend or Foe?

SLC7A11 controls the uptake of extracellular cystine in exchange for glutamate at a ratio of 1:1, and it is overexpressed in a variety of tumours. Accumulating evidence has shown that the expression of SLC7A11 is fine-tuned at multiple levels, and plays diverse functional and pharmacological roles in tumours, such as cellular redox homeostasis, cell growth and death, and cell metabolism. Many reports have suggested that the inhibition of SLC7A11 expression and activity is favourable for tumour therapy; thus, SLC7A11 is regarded as a potential therapeutic target. However, emerging evidence also suggests that on some occasions, the inhibition of SLC7A11 is beneficial to the survival of cancer cells, and confers the development of drug resistance. In this review, we first briefly introduce the biological properties of SLC7A11, including its structure and physiological functions, and further summarise its regulatory network and potential regulators. Then, focusing on its role in cancer, we describe the relationships of SLC7A11 with tumourigenesis, survival, proliferation, metastasis, and therapeutic resistance in more detail. Finally, since SLC7A11 has been linked to cancer through multiple approaches, we propose that its contribution and regulatory mechanism require further elucidation. Thus, more personalised therapeutic strategies should be adapted when targeting SLC7A11.

Ferroptosis Modulation: Potential Therapeutic Target for Glioblastoma Treatment

Glioblastoma multiforme is a lethal disease and represents the most common and severe type of glioma. Drug resistance and the evasion of cell death are the main characteristics of its malignancy, leading to a high percentage of disease recurrence and the patients’ low survival rate. Exploiting the modulation of cell death mechanisms could be an important strategy to prevent tumor development and reverse the high mortality and morbidity rates in glioblastoma patients. Ferroptosis is a recently described type of cell death, which is characterized by iron accumulation, high levels of polyunsaturated fatty acid (PUFA)-containing phospholipids, and deficiency in lipid peroxidation repair. Several studies have demonstrated that ferroptosis has a potential role in cancer treatment and could be a promising approach for glioblastoma patients. Thus, here, we present an overview of the mechanisms of the iron-dependent cell death and summarize the current findings of ferroptosis modulation on glioblastoma including its non-canonical pathway. Moreover, we focused on new ferroptosis-inducing compounds for glioma treatment, and we highlight the key ferroptosis-related genes to glioma prognosis, which could be further explored. Thereby, understanding how to trigger ferroptosis in glioblastoma may provide promising pharmacological targets and indicate new therapeutic approaches to increase the survival of glioblastoma patients.

Aberrant ROS Served as an Acquired Vulnerability of Cisplatin-Resistant Lung Cancer

Lung cancer has become a global health issue in recent decades. Approximately 80-85% of cases are non-small-cell lung cancer (NSCLC). Despite the high rate of resistance, cisplatin-base chemotherapy is still the main treatment for NSCLC patients. Thus, overcoming cisplatin resistance is urgently needed in NSCLC therapy. In this study, we identify NADPH metabolism and reactive oxygen species (ROS) levels as the main causes accounting for cisplatin resistance. Based on a small panel consisting of common chemotherapy drugs or compounds, APR-246 is proved to be an effective compound targeting cisplatin-resistant NSCLC cells. APR-246 specially inhibits proliferation and colony formation of cisplatin-resistant cells. In details, APR-246 can significantly cause G0/G1 accumulation and S phase arrest of cisplatin resistant cells and gives rise to severe mitochondria dysfunction as well as elevated apoptosis. Further study proves that it is the aberrant ROS levels as well as NRF2/SLC7A11/GSH axis dysfunction accounting for the specific antitumor effects of APR-246. Scavenging ROS with N-acetylcysteine (NAC) disrupts the inhibitory effect of APR-246 on cisplatin-resistant cells. Mechanistically, NRF2 is specifically degraded by the proteasome following its own ubiquitylation in APR-246-treated cisplatin-resistant cells, which in turn decreases NRF2/SLC7A11/GSH axis activity. Our study provides new insights into the biology driving cisplatin resistance of lung cancer and highlights APR-246 as a potential therapeutic reagent for overcoming cisplatin resistance.

Ferroptosis and its role in cardiomyopathy

Heart disease is the leading cause of death worldwide. Cardiomyopathy is a disease characterized by the heart muscle damage, resulting heart in a structurally and functionally change, as well as heart failure and sudden cardiac death. The key pathogenic factor of cardiomyopathy is the loss of cardiomyocytes, but the related molecular mechanisms remain unclear. Ferroptosis is a newly discovered regulated form of cell death, characterized by iron accumulation and lipid peroxidation during cell death. Recent studies have shown that ferroptosis plays an important regulatory roles in the occurrence and development of many heart diseases such as myocardial ischemia/reperfusion injury, cardiomyopathy and heart failure. However, the systemic association of ferroptosis and cardiomyopathy remains largely unknown and needs to be elucidated. In this review, we provide an overview of the molecular mechanisms of ferroptosis and its role in individual cardiomyopathies, highlight that targeting ferroptosis maybe a potential therapeutic strategy for cardiomyopathy therapy in the future.

The Organelle-Specific Regulations and Epigenetic Regulators in Ferroptosis

Ferroptosis is fairly different from other types of cell-death in biochemical processes, morphological changes and genetics as a special programmed cell-death. Here we summarize the current literatures on ferroptosis, including the cascade reaction of key material metabolism in the process, dysfunction of organelles, the relationship between different organelles and the way positive and negative key regulatory factors to affect ferroptosis in the epigenetic level. Based on material metabolism or epigenetic regulation, it is obvious that the regulatory network of ferroptosis is interrelated and complex.

New Insights on Ferroptosis and Gynecological Malignancies

Ferroptosis is a new type of cell death different from apoptosis and necrosis, which can regulate the accumulation of lipid peroxidation through different pathways, ultimately leading to cell death. An increasing number of studies have revealed that the relationship between ferroptosis and cancer is extremely complex, which holds promise as a new treatment. In gynecological malignancies, ferroptosis has been found to have excellent antitumor activity, which can regulate the proliferation, metastasis and radiochemotherapy resistance. With the continuous progress of research, nanodrugs, gene therapy and other new therapeutic techniques for inducing ferroptosis have been proposed. However, the study of ferroptosis in gynecological malignancies is still in its infancy, and further research is needed to design safe and effective cancer therapies based on ferroptosis. This article reviews the mechanism of ferroptosis and the latest research progress and prospects in gynecological malignancies.

Materno-fetal iron transfer and the emerging role of ferroptosis pathways

A successful pregnancy and the birth of a healthy baby depend to a great extent on the controlled supply of essential nutrients via the placenta. Iron is essential for mitochondrial energy supply and oxygen distribution via the blood. However, its high reactivity requires tightly regulated transport processes. Disturbances of maternal-fetal iron transfer during pregnancy can aggravate or lead to severe pathological consequences for the mother and the fetus with lifelong effects. Furthermore, high intracellular iron levels due to disturbed gestational iron homeostasis have recently been associated with the non-apoptotic cell death pathway called ferroptosis. Therefore, the investigation of transplacental iron transport mechanisms, their physiological regulation and potential risks are of high clinical importance. The present review summarizes the current knowledge on principles and regulatory mechanisms underlying materno-fetal iron transport and gives insight into common pregnancy conditions in which iron homeostasis is disturbed. Moreover, the significance of the newly emerging ferroptosis pathway and its impact on the regulation of placental iron homeostasis, oxidative stress and gestational diseases will be discussed.

Molecular mechanisms of ferroptosis and its role in prostate cancer therapy

Prostate cancer (PCa) is a highly prevalent disease that affects men's health worldwide and is the second most common malignancy in males. Ferroptosis is a novel form of programmed cell death characterized by iron overload and the accumulation of lipid peroxidation, which differs from the regulated cell death modes of necrosis, apoptosis, and autophagy. Substantial progress has been achieved in researching the occurrence and regulatory mechanisms of ferroptosis, which is closely associated with cancer initiation, progression, and suppression and is expected to become a new breakthrough point in the PCa treatment. This review will summarize the mechanisms involved in PCa, and we detail the molecular mechanisms of ferroptosis and its role in PCa treatment.

Understanding the mechanistic regulation of ferroptosis in cancer: gene matters

Ferroptosis has emerged as a crucial regulated cell death involved in a variety of physiological processes or pathological diseases, such as tumor suppression. Though initially being found from anti-cancer drug screening and considered not essential as apoptosis for growth and development, numerous studies have demonstrated that ferroptosis is tightly regulated by key genetic pathways and/or genes, including several tumor suppressors and oncogenes. In this review, we will first introduce the basic concepts of ferroptosis, characterized by the features of non-apoptotic, iron-dependent and overwhelmed accumulation of lipid peroxides, and the underlying regulated circuits are considered to be pro-ferroptotic pathways. Then we discuss several established lipid peroxidation defending systems within cells, including SLC7A11/GPX4, FSP1/CoQ, GCH1/BH4, and mitochondria DHODH/CoQ, all of which serve as anti-ferroptoic pathways to prevent ferroptosis. Moreover, we provide a comprehensive summary of the genetic regulation of ferroptosis via targeting the above-mentioned pro-ferroptotic or anti-ferroptotic pathways. The regulation of pro- and anti-ferroptotic pathways gives rise to more specific responses to the tumor cells in a context-dependent manner, highlighting the unceasing study and deeper understanding of mechanistic regulation of ferroptosis for the purpose of applying ferroptosis induction in cancer therapy.

miR-6077 promotes cisplatin/pemetrexed resistance in lung adenocarcinoma via CDKN1A/cell cycle arrest and KEAP1/ferroptosis pathways

Lung adenocarcinoma (LUAD) is one of the most common malignancies worldwide. Combination chemotherapy with cisplatin (CDDP) plus pemetrexed (PEM) remains the predominant therapeutic regimen; however, chemoresistance greatly limits its curative potential. Here, through CRISPR-Cas9 screening, we identified miR-6077 as a key driver of CDDP/PEM resistance in LUAD. Functional experiments verified that ectopic overexpression of miR-6077 desensitized LUAD cells to CDDP/PEM in both cell lines and patient-derived xenograft models. Through RNA sequencing in cells and single-cell sequencing of samples from patients with CDDP/PEM treatments, we observed CDDP/PEM-induced upregulation of CDKN1A and KEAP1, which in turn activated cell-cycle arrest and ferroptosis, respectively, thus leading to cell death. Through miRNA pull-down, we identified and validated that miR-6077 targets CDKN1A and KEAP1. Furthermore, we demonstrated that miR-6077 protects LUAD cells from cell death induced by CDDP/PEM via CDKN1A-CDK1-mediated cell-cycle arrest and KEAP1-NRF2-SLC7A11/NQO1-mediated ferroptosis, thus resulting in chemoresistance in multiple LUAD cells both in vitro and in vivo. Moreover, we found that GMDS-AS1 and LINC01128 sensitized LUAD cells to CDDP/PEM by sponging miR-6077. Collectively, these results imply the critical role of miR-6077 in LUAD’s sensitivity to CDDP/PEM, thus providing a novel therapeutic strategy for overcoming chemoresistance in clinical practice.

Roles and Mechanisms of Regulated Necrosis in Corneal Diseases: Progress and Perspectives

Regulated necrosis is defined as cell death characterized by loss of the cell membrane integrity and release of the cytoplasmic content. It contributes to the development and progression of some diseases, including ischemic stroke injury, liver diseases, hypertension, and cancer. Various forms of regulated necrosis, particularly pyroptosis, necroptosis, and ferroptosis, have been implicated in the pathogenesis of corneal disease. Regulated necrosis of corneal cells enhances inflammatory reactions in the adjacent corneal tissues, leading to recurrence and aggravation of corneal disease. In this review, we summarize the molecular mechanisms of pyroptosis, necroptosis, and ferroptosis in corneal diseases and discuss the roles of regulated necrosis in inflammation regulation, tissue repair, and corneal disease outcomes.

Apatinib Induces Ferroptosis of Glioma Cells through Modulation of the VEGFR2/Nrf2 Pathway

Background

Glioma is a common tumor that originated from the brain, and molecular targeted therapy is one of the important treatment modalities of glioma. Apatinib is a small-molecule tyrosine kinase inhibitor, which is widely used for the treatment of glioma. However, the underlying molecular mechanism has remained elusive. Recently, emerging evidence has proved the remarkable anticancer effects of ferroptosis. In this study, a new ferroptosis-related mechanism of apatinib inhibiting proliferation of glioma cells was investigated, which facilitated further study on inhibitory effects of apatinib on cancer cells.

Methods

Human glioma U251 and U87 cell lines and normal astrocytes were treated with apatinib. Ferroptosis, cell cycle, apoptosis, and proliferation were determined. A nude mouse xenograft model was constructed, and tumor growth rate was detected. Tumor tissues were collected to estimate ferroptosis levels and to identify the relevant pathways after treatment with apatinib.

Results

Treatment with apatinib could induce loss of cell viability of glioma cells, but not of normal astrocytes, through eliciting ferroptosis in vitro and in vivo. It was also revealed that apatinib triggered ferroptosis of glioma cells via inhibiting the activation of nuclear factor erythroid 2-related factor 2/vascular endothelial growth factor receptor 2 (Nrf2/VEFGR2) pathway. The overexpression of Nrf2 rescued the therapeutic effects of apatinib.

Conclusion

Our study proved that treatment with apatinib could restrain proliferation of glioma cells through induction of ferroptosis via inhibiting the activation of VEGFR2/Nrf2/Keap1 pathway. Overexpression of Nrf2 could counteract the induction of ferroptosis by apatinib.