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

The influence of ferroptosis on the in vitro OGD/R model in rat microglia

OBJECTIVE

We aimed to explore the influence of ferroptosis on an oxygen-glucose deprivation/reoxygenation (OGD/R) model in primary rat microglia.

METHODS

Primary microglia were extracted from rats and cultured in vitro. The cells were subjected to a hypoxic environment for 6 h in a glucose-free medium, and then re-oxygenated for 24 h in DMEM/F12. Rat microglia were pretreated with the ferroptosis activator erastin and the ferroptosis inhibitor ferrostatin 1 for 24 h, followed by detection of cell cycle progression and apoptosis by flow cytometry. Intracellular total iron levels were measured. In addition, the relative levels of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were determined using enzyme-linked immunosorbent assay. The protein levels of 15-lox2, GPX4, SLC7A11, ACSL4, and TFR1 were examined by western blotting.

RESULTS

Compared with rat microglia subjected to OGD/R, pretreatment with erastin did not influence cell apoptosis but significantly enhanced total iron levels, MDA, and ROS levels, whereas it reduced SOD levels. Moreover, it upregulated ACSL4, TFR1, and 15-lox2 and downregulated GPX4 and SLC7A11. Pretreatment with ferrostatin 1 significantly inhibited cell apoptosis and cell cycle arrest in the G0/G1 phase. It significantly reduced total iron levels, MDA, and ROS levels and enhanced SOD levels, which also downregulated ACSL4, TFR1, and 15-lox2, and upregulated GPX4 and SLC7A11.

CONCLUSION

Our study showed that inhibition of ferroptosis is favorable against potential OGD/R-induced damage in rat microglia.

Bioactive compound schaftoside from Clinacanthus nutans attenuates acute liver injury by inhibiting ferroptosis through activation the Nrf2/GPX4 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Clinacanthus nutans (Burm. f.) Lindau, a traditional herb renowned for its anti-tumor, antioxidant, and anti-inflammatory properties, has garnered considerable attention. Although its hepatoprotective effects have been described, there is still limited knowledge of its treatment of acute liver injury (ALI), and its mechanisms remain unclear.

AIM OF THE STUDY

To assess the efficacy of Clinacanthus nutans in ALI and to identify the most effective fractions and their underlying mechanism of action.

METHODS

Bioinformatics was employed to explore the underlying anti-hepatic injury mechanisms and active compounds of Clinacanthus nutans. The binding ability of schaftoside, a potential active ingredient in Clinacanthus nutans, to the core target nuclear factor E2-related factor 2 (Nrf2) was further determined by molecular docking. The role of schaftoside in improving histological abnormalities in the liver was observed by H&E and Masson's staining in an ALI model induced by CCl4. Serum and liver biochemical parameters were measured using AST, ALT and hydroxyproline kits. An Fe2+ kit, transmission electron microscopy, western blotting, RT-qPCR, and DCFH-DA were used to measure whether schaftoside reduces ferroptosis-induced ALI. Subsequently, specific siRNA knockdown of Nrf2 in AML12 cells was performed to further elucidate the mechanism by which schaftoside attenuates ferroptosis-induced ALI.

RESULTS

Bioinformatics analysis and molecular docking showed that schaftoside is the principal compound from Clinacanthus nutans. Schaftoside was shown to diminish oxidative stress levels, attenuate liver fibrosis, and forestall ferroptosis. Deeper investigations revealed that schaftoside amplified Nrf2 expression and triggered the Nrf2/GPX4 pathway, thereby reversing mitochondrial aberrations triggered by lipid peroxidation, GPX4 depletion, and ferroptosis.

CONCLUSION

The lead compound schaftoside counters ferroptosis through the Nrf2/GPX4 axis, providing insights into a novel molecular mechanism for treating ALI, thereby presenting an innovative therapeutic strategy for ferroptosis-induced ALI.

ROS mediated Cu[Fe(CN)5NO] nanoparticles for triple negative breast cancer: A detailed study in preclinical mouse model

Triple negative breast cancer (TNBC) is an aggressive form of tumor, more prevalent in younger women resulting in poor survival rate (2nd in cancer deaths) because of its asymptomatic existence. The most popular and convenient approach for the treatment of TNBC is chemotherapy which is associated with several limitations. Considering the importance of nanotechnology in health care system, in the present manuscript, we have designed and developed a simple, efficient, cost effective, and ecofriendly method for the synthesis of copper nitroprusside analogue nanoparticles (Cu[Fe(CN)5NO] which is abbreviated as CuNPANP that may be the potential anti-cancer nanomedicine for the treatment of TNBC. Copper (present in CuNPANP) is used because of its affordability, nutritional value and various biomedical applications. The CuNPANP are thoroughly characterized using several analytical techniques. The in vitro cell viability (in normal cells) and the ex vivo hemolysis assay reveal the biocompatible nature of CuNPANP. The anti-cancer activity of the CuNPANP is established in TNBC cells (MDA-MB-231 and 4T1) through several in vitro assays along with plausible mechanisms. The intraperitoneal administration of CuNPANP in orthotopic breast tumor model by transplanting 4T1 cells into the mammary fat pad of BALB/c mouse significantly inhibits the growth of breast carcinoma as well as increases the survival time of tumor-bearing mice. These results altogether potentiate the anti-cancer efficacy of CuNPANP as a smart therapeutic nanomedicine for treating TNBC in near future after bio-safety evaluation in large animals.

Involvement of ferroptosis in eribulin-induced cytotoxicity in ovarian clear cell carcinoma

Ovarian clear cell carcinoma (OCCC) is a unique clinicopathological subtype of epithelial ovarian cancer that is resistant to standard chemotherapy. Eribulin, a microtubule dynamics inhibitor of halichondrin class, has unique effects in the cancer microenvironment such as induction of epithelization and reduction in metastatic potential in breast cancer cells; however, nothing is known about the effect of eribulin and the detailed mechanisms in OCCC. This study aimed to investigate the involvement of ferroptosis and its mechanism in the antitumor activity of eribulin in OCCC cells and a mouse xenograft model. We found that eribulin-induced cell death was reduced by ferroptosis inhibitors; deferoxamine, an iron chelator and ferrostatin-1, a lipid peroxidation inhibitor. Eribulin increased the levels of intracellular iron, reactive oxygen species (ROS), and lipid peroxides, and increased the mitochondrial membrane potential. Eribulin downregulated the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH), and superoxide dismutase (SOD) activity. The combination of eribulin and ML210, a glutathione peroxidase 4-inhibiting ferroptosis inducer, had a synergistic effect on ferroptosis. Taken together, our findings show firstly that eribulin triggers ferroptosis in OCCC and this effect occurs via the suppression of the Nrf2-HO-1 signaling pathway, SOD activity and the promotion of lipid peroxidation. These findings suggest that eribulin-induced ferroptosis is associated with its anti-tumor effect and also could be a potential therapeutic target in OCCC.

YES1 as a potential target to overcome drug resistance in EGFR-deregulated non-small cell lung cancer

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) such as gefitinib and osimertinib have primarily been used as first-line treatments for patients with EGFR-activating mutations in non-small cell lung cancer (NSCLC). Novel biomarkers are required to distinguish patients with lung cancer who are resistant to EGFR-TKIs. The aim of the study is to investigate the expression and functional role of YES1, one of the Src-family kinases, in EGFR-TKI-resistant NSCLC. YES1 expression was elevated in gefitinib-resistant HCC827 (HCC827/GR) cells, harboring EGFR mutations. Moreover, HCC827/GR cells exhibited increased reactive oxygen species (ROS) levels compared to those of the parent cells, resulting in the phosphorylation/activation of YES1 due to oxidation of the cysteine residue. HCC827/GR cells showed elevated expression levels of YES1-associated protein 1 (YAP1), NF-E2-related factor 2 (Nrf2), cancer stemness-related markers, and antioxidant proteins compared to those of the parent cells. Knockdown of YES1 in HCC827/GR cells suppressed YAP1 phosphorylation, leading to the inhibition of Bcl-2, Bcl-xL, and Cyclin D1 expression. Silencing YES1 markedly attenuated the proliferation, migration, and tumorigenicity of HCC827/GR cells. Dasatinib inhibited the proliferation of HCC827/GR cells by targeting YES1-mediated signaling pathways. Furthermore, the combination of gefitinib and dasatinib demonstrated a synergistic effect in suppressing the proliferation of HCC827/GR cells. Notably, YES1- and Nrf2-regulated genes showed a positive regulatory relationship in patients with lung cancer and in TKI-resistant NSCLC cell lines. Taken together, these findings suggest that modulation of YES1 expression and activity may be an attractive therapeutic strategy for the treatment of drug-resistant NSCLC.

Induction of ferroptosis by natural products in non-small cell lung cancer: a comprehensive systematic review

Lung cancer is one of the leading causes of cancer-related deaths worldwide that presents a substantial peril to human health. Non-Small Cell Lung Cancer (NSCLC) is a main subtype of lung cancer with heightened metastasis and invasion ability. The predominant treatment approaches currently comprise surgical interventions, chemotherapy regimens, and radiotherapeutic procedures. However, it poses significant clinical challenges due to its tumor heterogeneity and drug resistance, resulting in diminished patient survival rates. Therefore, the development of novel treatment strategies for NSCLC is necessary. Ferroptosis was characterized by iron-dependent lipid peroxidation and the accumulation of lipid reactive oxygen species (ROS), leading to oxidative damage of cells and eventually cell death. An increasing number of studies have found that exploiting the induction of ferroptosis may be a potential therapeutic approach in NSCLC. Recent investigations have underscored the remarkable potential of natural products in the cancer treatment, owing to their potent activity and high safety profiles. Notably, accumulating evidences have shown that targeting ferroptosis through natural compounds as a novel strategy for combating NSCLC holds considerable promise. Nevertheless, the existing literature on comprehensive reviews elucidating the role of natural products inducing the ferroptosis for NSCLC therapy remains relatively sparse. In order to furnish a valuable reference and support for the identification of natural products inducing ferroptosis in anti-NSCLC therapeutics, this article provided a comprehensive review explaining the mechanisms by which natural products selectively target ferroptosis and modulate the pathogenesis of NSCLC.

Nrf2 protein in melanoma progression, as a new means of treatment

Melanoma is a potentially lethal form of skin cancer resulting from the unlimited proliferation of melanocytes. Melanocytic lineage appears to have a greater rate of reactive oxygen species (ROS) production, possibly as a result of exposure to ultraviolet (UV) light and the production of melanin. It has been established that nuclear factor erythroid 2-related factor 2 (Nrf2) serves as a master regulator of the cellular response to oxidative stresses. Recent research has shown that the Nrf2 and its critical negative regulator Kelch-like ECH-associated protein 1 (Keap1) are misregulated in melanoma, and the Keap1-Nrf2 pathway has emerged as a promising new target for treating and preventing melanoma. In melanoma, Nrf2 may either limit tumor growth or promote its development. This review covers a wide range of topics, including the dual functions played by the Keap1-Nrf2 signaling pathway in melanoma and the most recent targeting techniques of the Nrf2.

SOD2 confers anlotinib resistance via regulation of mitochondrial damage in OSCC

OBJECTIVE

Previous studies had revealed that anlotinib had outstanding anti-tumor efficacy on oral squamous cell carcinoma. However, the underlying mechanism is still unclear.

MATERIALS AND METHODS

Anlotinib resistant OSCC cells were established and analyzed by RNA-sequencing. The correlations between SOD2 expression and anlotinib resistance were investigated in OSCC cells and PDX models. Functional assays were performed to verify the SOD2 expression and anlotinib resistance in OSCC cells.

RESULTS

Anlotinib resistant genes were enriched in the biological processes of mitochondrion organization and the gene pathway of reactive oxygen species. SOD2 expression level was positively correlated with the resistance of anlotinib in OSCC cells and PDX models. Higher SOD2 expression of OSCC cells was more resistant to anlotinib. Anlotinib induced ROS generation, apoptosis and mitochondrial damage in OSCC cells, which can be enhanced by SOD2 knockdown and decreased by SOD2 overexpression. Mitochondrial damage was identified as swelling and cristae disappearance morphology under TEM, decreased mitochondrial membrane potential and lower MFN2 expression.

CONCLUSIONS

SOD2 may be capable of protecting mitochondria by downregulating ROS generation, which contributes to the resistance of anlotinib in OSCC cells. SOD2 can be utilized as a potential therapeutic target to improve the anti-cancer efficacy of anlotinib in OSCC.

Butyrate ameliorated ferroptosis in ulcerative colitis through modulating Nrf2/GPX4 signal pathway and improving intestinal barrier

Oxidative stress and intestinal inflammation are main pathological features of ulcerative colitis (UC). Ferroptosis, characterized by iron accumulation and lipid peroxidation, is closely related to the pathologic process of UC. 16S rRNA sequencing for intestinal microbiota analysis and gas chromatography-mass spectrometry (GC-MS) for short-chain fatty acid (SCFA) contents clearly demonstrated lower amounts of butyrate-producing bacteria and butyrate in colitis mice. However, the precise mechanisms of sodium butyrate (NaB) in treating UC remain largely unclear. We found that ferroptosis occurred in colitis models, as evidenced by the inflammatory response, intracellular iron level, mitochondria ultrastructural observations and associated protein expression. NaB inhibited ferroptosis in colitis, significantly rescued weight loss and colon shortening in mice and reduced inflammatory lesions and mitochondrial damage. Furthermore, NaB improved intestinal barrier integrity and markedly suppressed the expression of pro-ferroptosis proteins. Conversely, the protein expression of anti-ferroptosis markers including nuclear factor erythroid-related Factor 2 (Nrf2) and glutathione peroxidase 4 (GPX4), was significantly upregulated with NaB treatment. Moreover, the knockdown of Nrf2 reversed the anti-colitis effect of NaB. Taken together, NaB exhibited a protective effect by ameliorating ferroptosis in experimental colitis through Nrf2/GPX4 signaling and improving intestinal barrier integrity, which provides a novel mechanism for NaB prevention of UC.

Novel bioactive 2-phenyl-4-aminopyrimidine derivatives as EGFRDel19/T790M/C797S inhibitors for the treatment of non-small cell lung cancer

Overexpression of the epidermal growth factor receptor (EGFR) has been implicated in the development of non-small-cell lung cancer (NSCLC). Thus, EGFR is an effective drug target for the treatment of NSCLC, and developing fourth-generation EGFR inhibitors to overcome the resistance mediated by T790M/C797S mutations are currently under investigation. In this study, based on the binding model between Angew2017-7634-1 and EGFRT790M/C797S , several series of 2-phenyl-4-aminopyrimidine derivatives were designed and synthesized. The bioactivity of these compounds was evaluated and it is suggested that compound A23 could effectively inhibit the proliferation of Ba/F3-EGFRDel19/T790M/C797S and H1975-EGFRL858R/T790M cells, with an IC50 of 0.22 ± 0.07 and 0.52 ± 0.03 μM, respectively. Meanwhile, the kinase activity of A23 against EGFRL858R/T790M and EGFRDel19/T790M/C797S was also evaluated, with an IC50 of 0.33 and 0.133 μM, respectively. Moreover, compound A23 was further evaluated in the H1975 xenograft models with significant in vivo tumor growth inhibitions of 25.5%, which means that A23 could effectively inhibit the growth of tumor cells and promote the death of tumor cells. As a result, A23 could be identified as a novel potential EGFRDel19/T790M/C797S inhibitor.

Mitochondrial Glutathione in Cellular Redox Homeostasis and Disease Manifestation

Mitochondria are critical for providing energy to maintain cell viability. Oxidative phosphorylation involves the transfer of electrons from energy substrates to oxygen to produce adenosine triphosphate. Mitochondria also regulate cell proliferation, metastasis, and deterioration. The flow of electrons in the mitochondrial respiratory chain generates reactive oxygen species (ROS), which are harmful to cells at high levels. Oxidative stress caused by ROS accumulation has been associated with an increased risk of cancer, and cardiovascular and liver diseases. Glutathione (GSH) is an abundant cellular antioxidant that is primarily synthesized in the cytoplasm and delivered to the mitochondria. Mitochondrial glutathione (mGSH) metabolizes hydrogen peroxide within the mitochondria. A long-term imbalance in the ratio of mitochondrial ROS to mGSH can cause cell dysfunction, apoptosis, necroptosis, and ferroptosis, which may lead to disease. This study aimed to review the physiological functions, anabolism, variations in organ tissue accumulation, and delivery of GSH to the mitochondria and the relationships between mGSH levels, the GSH/GSH disulfide (GSSG) ratio, programmed cell death, and ferroptosis. We also discuss diseases caused by mGSH deficiency and related therapeutics.

The application of approaches in detecting ferroptosis

Ferroptosis is a regulatory cell death (RCD) caused by iron-dependent lipid peroxidation, which is the backbone of regulating various diseases such as tumor, nervous system diseases and so on. Despite ferroptosis without specific detection methods currently, there are numerous types of detection technology commonly used, including flow cytometry, cell activity assay, microscopic imaging, western blotting, quantitative polymerase chain reaction (qPCR). In addition, ferroptosis could be detected by quantifying oxygen-free radicals reactive oxygen species (ROS), the lipid metabolite (malondialdehyde ((MDA)), related pathways and observing mitochondrial damage. In the face of numerous detection methods, how to choose appropriate detection methods based on experimental purposes has become a problem that needs to be solved at present. In this review, we summarized the commonly used detection methods of the critical substances in the process of ferroptosis, in the hope of facilitating the comprehensive study of ferroptosis, with a view to providing a guidance for subsequent related research.

Cytoplasmic Shotgun Proteomic Points to Key Proteins and Pathways in Temozolomide-Resistant Glioblastoma Multiforme

Temozolomide (TMZ) is the first line of chemotherapy to treat primary brain tumors of the type glioblastoma multiforme (GBM). TMZ resistance (TMZR) is one of the main barriers to successful treatment and is a principal factor in relapse, resulting in a poor median survival of 15 months. The present paper focuses on proteomic analyses of cytosolic fractions from TMZ-resistant (TMZR) LN-18 cells. The experimental workflow includes an easy, cost-effective, and reproducible method to isolate subcellular fraction of cytosolic (CYTO) proteins, mitochondria, and plasma membrane proteins for proteomic studies. For this study, enriched cytoplasmic fractions were analyzed in replicates by nanoflow liquid chromatography tandem high-resolution mass spectrometry (nLC-MS/MS), and proteins identified were quantified using a label-free approach (LFQ). Statistical analysis of control (CTRL) and temozolomide-resistant (TMZR) proteomes revealed proteins that appear to be differentially controlled in the cytoplasm. The functions of these proteins are discussed as well as their roles in other cancers and TMZ resistance in GBM. Key proteins are also described through biological processes related to gene ontology (GO), molecular functions, and cellular components. For protein-protein interactions (PPI), network and pathway involvement analyses have been performed, highlighting the roles of key proteins in the TMZ resistance phenotypes. This study provides a detailed insight into methods of subcellular fractionation for proteomic analysis of TMZ-resistant GBM cells and the potential to apply this approach to future large-scale studies. Several key proteins, protein-protein interactions (PPI), and pathways have been identified, underlying the TMZ resistance phenotype and highlighting the proteins' biological functions.

Nanomedicine targeting ferroptosis to overcome anticancer therapeutic resistance

A potential reason for the failure of tumor therapies is treatment resistance. Resistance to chemotherapy, radiotherapy, and immunotherapy continues to be a major obstacle in clinic, resulting in tumor recurrence and metastasis. The major mechanisms of therapy resistance are inhibitions of cell deaths, like apoptosis and necrosis, through drug inactivation and excretion, repair of DNA damage, tumor heterogeneity, or changes in tumor microenvironment, etc. Recent studies have shown that ferroptosis play a major role in therapies resistance by inducing phospholipid peroxidation and iron-dependent cell death. Some ferroptosis inducers in combination with clinical treatment techniques have been used to enhance the effect in tumor therapy. Notably, versatile ferroptosis nanoinducers exhibit an extensive range of functions in reversing therapy resistance, including directly triggering ferroptosis and feedback regulation. Herein, we provide a detailed description of the design, mechanism, and therapeutic application of ferroptosis-mediated synergistic tumor therapeutics. We also discuss the prospect and challenge of nanomedicine in tumor therapy resistance by regulating ferroptosis and combination therapy.

Inhibition of ferroptosis by POLE2 in gastric cancer cells involves the activation of NRF2/GPX4 pathway

Gastric cancer results in great cancer mortality worldwide, and inducing ferroptosis dramatically improves the malignant phenotypes of gastric cancer. DNA polymerase epsilon subunit 2 (POLE2) plays indispensable roles in tumorigenesis; however, its involvement and molecular basis in ferroptosis and gastric cancer are not clear. Human gastric cancer cells were infected with lentiviral vectors to knock down or overexpress POLE2, and cell ferroptosis was detected. To further validate the involvement of nuclear factor erythroid 2-related factor 2 (NRF2) and glutathione peroxidase 4 (GPX4), lentiviral vectors were used. POLE2 expression was elevated in human gastric cancer cells and tissues and closely correlated with clinicopathological features in gastric cancer patients. POLE2 knockdown was induced, while POLE2 overexpression inhibited ferroptosis of human gastric cancer cells, thereby modulating the malignant phenotypes of gastric cancer. Mechanistic studies revealed that POLE2 overexpression elevated NRF2 expression and activity and subsequently activated GPX4, which then prevented lipid peroxidation and ferroptosis in human gastric cancer cells. In contrast, either NRF2 or GPX4 silence significantly prevented POLE2 overexpression-mediated inductions of cell proliferation, migration, invasion and inhibition of ferroptosis. POLE2 overexpression inhibits ferroptosis in human gastric cancer cells through activating NRF2/GPX4 pathway, and inhibiting POLE2 may be a crucial strategy to treat gastric cancer.

Water Extract of Capsella bursa-pastoris Mitigates Doxorubicin-Induced Cardiotoxicity by Upregulating Antioxidant Enzymes

Doxorubicin (DOX), an effective chemotherapeutic drug, causes cardiotoxicity in a cumulative and dose-dependent manner. The aim of this study is to investigate the effects of hot-water extract of Capsella bursa-pastoris (CBW) on DOX-induced cardiotoxicity (DICT). We utilized H9c2 rat cardiomyocytes and MDA-MB-231 human breast cancer cells to evaluate the effects of CBW on DOX-induced cell death. Superoxide dismutase (SOD) levels, reactive oxygen species (ROS) production, and oxygen consumption rate were measured in H9c2 cells. C57BL/6 mice were treated with DOX and CBW to assess their impact on various cardiac parameters. Human-induced pluripotent stem-cell-derived cardiomyocytes were also used to investigate DOX-induced electrophysiological changes and the potential ameliorative effects of CBW. UPLC-TQ/MS analysis identified seven flavonoids in CBW, with luteolin-7-O-glucoside and isoorientin as the major compounds. CBW inhibited DOX-induced death of H9c2 rat cardiomyocytes but did not affect DOX-induced death of MDA-MB-231 human breast cancer cells. CBW increased SOD levels in a dose-dependent manner, reducing ROS production and increasing the oxygen consumption rate in H9c2 cells. The heart rate, RR interval, QT, and ST prolongation remarkably recovered in C57BL/6 mice treated with the combination of DOX and CBW compared to those in mice treated with DOX alone. Administration of CBW with DOX effectively alleviated collagen accumulation, cell death in mouse heart tissues, and reduced the levels of creatinine kinase (CK) and lactate dehydrogenase (LDH) in serum. Furthermore, DOX-induced pathological electrophysiological features in human-induced pluripotent stem-cell-derived cardiomyocytes were ameliorated by CBW. CBW may prevent DICT by stabilizing SOD and scavenging ROS. The presence of flavonoids, particularly luteolin-7-O-glucoside and isoorientin, in CBW may contribute to its protective effects. These results suggest the potential of CBW as a traditional therapeutic option to mitigate DOX-induced cardiotoxicity.

CFTR potentiator ivacaftor protects against noise-induced hair cell loss by increasing Nrf2 and reducing oxidative stress

Over-production of reactive oxygen species (ROS) in the inner ear can be triggered by a variety of pathological events identified in animal models after traumatic noise exposure. Our previous research found that inhibition of the AMP-activated protein kinase alpha subunit (AMPKα) protects against noise-induced cochlear hair cell loss and hearing loss by reducing ROS accumulation. However, the molecular pathway through which AMPKα exerts its antioxidative effect is still unclear. In this study, we have investigated a potential target of AMPKα and ROS, cystic fibrosis transmembrane conductance regulator (CFTR), and the protective effect against noise-induced hair cell loss of an FDA-approved CFTR potentiator, ivacaftor, in FVB/NJ mice, mouse explant cultures, and HEI-OC1 cells. We found that noise exposure increases phosphorylation of CFTR at serine 737 (p-CFTR, S737), which reduces wildtype CFTR function, resulting in oxidative stress in cochlear sensory hair cells. Pretreatment with a single dose of ivacaftor maintains CFTR function by preventing noise-increased p-CFTR (S737). Furthermore, ivacaftor treatment increases nuclear factor E2-related factor 2 (Nrf2) expression, diminishes ROS formation, and attenuates noise-induced hair cell loss and hearing loss. Additionally, inhibition of noise-induced AMPKα activation by compound C also diminishes p-CFTR (S737) expression. In line with these in-vivo results, administration of hydrogen peroxide to cochlear explants or HEI-OC1 cells increases p-CFTR (S737) expression and induces sensory hair cell or HEI-OC1 cell damage, while application of ivacaftor halts these effects. Although ivacaftor increases Nrf2 expression and reduces ROS accumulation, cotreatment with ML385, an Nrf2 inhibitor, abolishes the protective effects of ivacaftor against hydrogen-peroxide-induced HEI-OC1 cell death. Our results indicate that noise-induced sensory hair cell damage is associated with p-CFTR. Ivacaftor has potential for treatment of noise-induced hearing loss by maintaining CFTR function and increasing Nrf2 expression for support of redox homeostasis in sensory hair cells.

The effects of Korean Red Ginseng on heme oxygenase-1 with a focus on mitochondrial function in pathophysiologic conditions

Korean Red Ginseng (KRG) plays a key role in heme oxygenase (HO)-1 induction under physical and moderate oxidative stress conditions. The transient and mild induction of HO-1 is beneficial for cell protection, mitochondrial function, regeneration, and intercellular communication. However, chronic HO-1 overexpression is detrimental in severely injured regions. Thus, in a chronic pathological state, diminishing HO-1-mediated ferroptosis is beneficial for a therapeutic approach. The molecular mechanisms by which KRG protects various cell types in the central nervous system have not yet been established, especially in terms of HO-1-mediated mitochondrial functions. Therefore, in this review, we discuss the multiple roles of KRG in the regulation of astrocytic HO-1 under pathophysiological conditions. More specifically, we discuss the role of the KRG-mediated astrocytic HO-1 pathway in regulating mitochondrial functions in acute and chronic neurodegenerative diseases as well as physiological conditions.

Methylseleninic acid overcomes gefitinib resistance through asparagine-MET-TOPK signaling axis in non-small cell lung cancer cells

Acquired resistance compromises the efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-based therapy for non-small cell lung cancer (NSCLC), and activation of hepatocyte growth factor receptor (MET) is one of the pivotal strategies for cancer cells to acquire refractory phenotype. However, the mechanisms involved in regulating MET activity remain to be further elucidated. Using gefitinib-resistant HCC827GR cell line as a model, we unraveled that the dysregulated amino acid metabolisms reflected by elevated expression of cysteine-preferring transporter 2 (ASCT2), cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11) and asparagine synthetase (ASNS) might contribute to survival advantage of HCC827GR cells, and rendered the cells more sensitive to asparagine (ASN) deprivation compared to parental HCC827 cells. We further identified that the increased ASNS expression is a contributing factor for the activation of MET in HCC827GR cells. More importantly, we found that methylseleninic acid (MSeA), a precursor of methylselenol, effectively suppressed tumor growth in HCC827GR xenograft model, which is associated with decrease of intracellular ASN content along with inactivation of MET- T-lymphokine-activated killer cell-originated protein kinase (TOPK) signaling axis. Finally, we demonstrated that combination of MSeA and gefitinib induced a synergistic growth inhibition in HCC827GR cells. The findings of our work reveal that ASN-MET-TOPK signaling axis as a novel mechanism contributed to gefitinib-resistance and combined utilization of gefitinib and MSeA holds potential to improve the efficacy for gefitinib-resistant NSCLC.

Tripterygium glycosides reverse chemotherapy resistance in ovarian cancer by targeting the NRF2/GPX4 signal axis to induce ferroptosis of drug-resistant human epithelial ovarian cancer cells

Cisplatin resistance is the main cause of postoperative recurrence and difficulty in the treatment of ovarian cancer. It is urgently needed to identify therapeutic drugs with unique functions to overcome the current challenges in the treatment of ovarian cancer. In this study, we found that TG promoted the accumulation of ROS and MDA in A2780/DDP cells and downregulated the expression of key antioxidant molecules. In vivo, the survival rate of tumor-bearing nude mice was prolonged by TG without significant hepatotoxic reaction. The expression of key antioxidant molecules in tumor tissues was consistent with that in vitro. These findings revealed that TG disrupted homeostasis of redox reactions and induced ferroptosis in A2780/DDP cells, thereby enhancing cisplatin chemosensitivity of ovarian cancer. Overall, TG may be a novel potential therapeutic option for reversing resistance to cisplatin chemotherapy.

Bazedoxifene-induced ROS promote mitochondrial dysfunction and enhance osimertinib sensitivity by inhibiting the p-STAT3/SOCS3 and KEAP1/NRF2 pathways in non-small cell lung cancer

Although the advent of osimertinib has brought revolutionary changes to the treatment landscape of non-small cell lung cancer (NSCLC) patients, acquired resistance remains a major obstacle limiting long-term survival benefits for the treatment of cancer. The purpose of this study was to examine the mechanisms involved in the ability of bazedoxifene to synergistically enhance osimertinib sensitivity, which will aid in delaying and overcoming osimertinib resistance to improve patient outcomes. Here, we found that osimertinib increased the production of reactive oxygen species (ROS), promoted mitochondrial fission, diminished mitochondrial membrane potential, and activated cell apoptosis. Moreover, the p-STAT3/suppressor of cytokine signaling 3 (SOCS3) and KEAP1/NRF2 signaling pathways were activated to scavenge ROS and promote osimertinib resistance. Mechanistically, SOCS3 can directly bind to KEAP1 to prevent the degradation of NRF2, resulting in the activation of an NRF2-dependent transcriptional program. Furthermore, the osimertinib-induced mitochondrial dysfunction and apoptosis were enhanced by bazedoxifene, thereby delaying and overcoming osimertinib resistance by inhibiting these pathways in vitro and in vivo. These findings identified a new critical link in the p-STAT3/SOCS3 pathway, KEAP1/NRF2 pathway, mitochondrial dysfunction, and osimertinib resistance. The present study demonstrated that bazedoxifene can be used for delaying or overcoming osimertinib resistance in NSCLC.

Integrin αvβ3 Is a Master Regulator of Resistance to TKI-Induced Ferroptosis in HER2-Positive Breast Cancer

Human epidermal growth factor receptor-2 (HER2)-targeting therapies provide clinical benefits for patients with HER2-positive breast cancer. However, the resistance to monotherapies invariably develops and leads to disease relapse and treatment failure. Previous studies have demonstrated a link between the potency of HER2-targeting tyrosine kinase inhibitors (TKIs) and their ability to induce an iron-dependent form of cell death called ferroptosis. The aim of this study was to understand the mechanisms of resistance to TKI-induced ferroptosis and identify novel approaches to overcome treatment resistance. We used mouse and human HER2-positive models of acquired TKI resistance to demonstrate an intimate link between the resistance to TKIs and to ferroptosis and present the first evidence that the cell adhesion receptor αvβ3 integrin is a critical mediator of resistance to TKI-induced ferroptosis. Our findings indicate that αvβ3 integrin-mediated resistance is associated with the re-wiring of the iron/antioxidant metabolism and persistent activation of AKT signalling. Moreover, using gene manipulation approaches and pharmacological inhibitors, we show that this "αvβ3 integrin addiction" can be targeted to reverse TKI resistance. Collectively, these findings provide critical insights into new therapeutic strategies to improve the treatment of advanced HER2-positive breast cancer patients.

Erk1/2-Dependent HNSCC Cell Susceptibility to Erastin-Induced Ferroptosis

Unfavorable clinical outcomes mean that cancer researchers must attempt to develop novel therapeutic strategies to overcome therapeutic resistance in patients with HNSCC. Recently, ferroptosis was shown to be a promising pathway possessing druggable targets, such as xCT (SLC7A11). Unfortunately, little is known about the molecular mechanisms underlying the susceptibility of HNSCC cells to ferroptosis. The goal of this study was to determine whether HNSCC cells with activated Erk1/2 are vulnerable to ferroptosis induction. Our results have shown that xCT (SLC7A11) was overexpressed in malignant tissues obtained from the patients with HNSCC, whereas normal mucosa demonstrated weak expression of the protein. In order to investigate the role of Erk1/2 in the decrease in cell viability caused by erastin, xCT-overexpressing FaDu and SCC25 HNSCC cells were used. The ravoxertinib-dependent inhibition of Erk1/2 signaling led to the decrease in erastin efficacy due to the effect on ROS production and the upregulation of ROS scavengers SOD1 and SOD2, resulting in repressed lipid peroxidation. Therefore, it was concluded that the erastin-dependent activation of ferroptosis seems to be a promising approach which can be further developed as an additional strategy for the treatment of HNSCC. As ferroptosis induction via erastin is strongly dependent on the expression of Erk1/2, this MAP kinase can be considered as a predictor for cancer cells' response to erastin.

Natural product manoalide promotes EGFR-TKI sensitivity of lung cancer cells by KRAS-ERK pathway and mitochondrial Ca2+ overload-induced ferroptosis

Background: Manoalide (MA), a proven natural inhibitor of PLA2 has anticancer effects, but its potential application and mechanism as an anticancer drug to promote EGFR-TKI sensitivity in lung cancer cells have not been studied. Methods: KRAS-mutated lung cancer cells and organoids, acquired osimertinib-resistant lung cancer cell lines HCC827OR, were used as EGFR-TKI-resistant models. CCK-8, clone formation, apoptosis assays, and calcein-AM staining were performed to investigate the inhibitory effects of MA in lung cancer cells and organoids. The flow cytometry or confocal microscope was used to detect lipid droplets, ROS, lipid peroxidation, mitochondria Ca²⁺, and iron content. The oxygen consumption rate (OCR) and fatty acid oxidation (FAO) were used to estimate the effect of MA on mitochondrial function. Results: MA inhibits the proliferation of KRAS-mutated lung cancer cells and organoids. In addition, MA induces ER stress in a ROS-dependent mechanism. The ROS induced by MA is mainly in mitochondrial and causes lipid peroxidation, thereby inhibiting mitochondrial FAO metabolism and promoting the accumulation of lipid droplets. MA also suppresses the KRAS-ERK pathway through ROS and promotes the sensitivity of KRAS-mutated lung cancer cells and organoids to osimertinib. Furthermore, MA induces ferroptosis by suppressing the NRF2-SLC7A11 axis and mitochondrial Ca²⁺ overload induced-FTH1 pathways to promote the sensitivity of osimertinib-resistant lung cancer cells to osimertinib. Conclusions: MA is a candidate EGFR-TKI sensitizer in KRAS-mutated and osimertinib-resistant lung cancer cells.

NEK6 Regulates Redox Balance and DNA Damage Response in DU-145 Prostate Cancer Cells

NEK6 is a central kinase in developing castration-resistant prostate cancer (CRPC). However, the pathways regulated by NEK6 in CRPC are still unclear. Cancer cells have high reactive oxygen species (ROS) levels and easily adapt to this circumstance and avoid cell death by increasing antioxidant defenses. We knocked out the NEK6 gene and evaluated the redox state and DNA damage response in DU-145 cells. The knockout of NEK6 decreases the clonogenic capacity, proliferation, cell viability, and mitochondrial activity. Targeting the NEK6 gene increases the level of intracellular ROS; decreases the expression of antioxidant defenses (SOD1, SOD2, and PRDX3); increases JNK phosphorylation, a stress-responsive kinase; and increases DNA damage markers (p-ATM and γH2AX). The exogenous overexpression of NEK6 also increases the expression of these same antioxidant defenses and decreases γH2AX. The depletion of NEK6 also induces cell death by apoptosis and reduces the antiapoptotic Bcl-2 protein. NEK6-lacking cells have more sensitivity to cisplatin. Additionally, NEK6 regulates the nuclear localization of NF-κB2, suggesting NEK6 may regulate NF-κB2 activity. Therefore, NEK6 alters the redox balance, regulates the expression of antioxidant proteins and DNA damage, and its absence induces the death of DU-145 cells. NEK6 inhibition may be a new strategy for CRPC therapy.

Insights into Manganese Superoxide Dismutase and Human Diseases

Redox equilibria and the modulation of redox signalling play crucial roles in physiological processes. Overproduction of reactive oxygen species (ROS) disrupts the body's antioxidant defence, compromising redox homeostasis and increasing oxidative stress, leading to the development of several diseases. Manganese superoxide dismutase (MnSOD) is a principal antioxidant enzyme that protects cells from oxidative damage by converting superoxide anion radicals to hydrogen peroxide and oxygen in mitochondria. Systematic studies have demonstrated that MnSOD plays an indispensable role in multiple diseases. This review focuses on preclinical evidence that describes the mechanisms of MnSOD in diseases accompanied with an imbalanced redox status, including fibrotic diseases, inflammation, diabetes, vascular diseases, neurodegenerative diseases, and cancer. The potential therapeutic effects of MnSOD activators and MnSOD mimetics are also discussed. Targeting this specific superoxide anion radical scavenger may be a clinically beneficial strategy, and understanding the therapeutic role of MnSOD may provide a positive insight into preventing and treating related diseases.

Role of ferroptosis inhibitors in the management of diabetes

Ferroptosis, the iron-dependent, lipid peroxide-mediated cell death, has garnered attention due to its critical involvement in crucial physiological and pathological cellular processes. Indeed, several studies have attributed its role in developing a range of disorders, including diabetes. As accumulating evidence further the understanding of ferroptotic mechanisms, the impact this specialized mode of cell death has on diabetic pathogenesis is still unclear. Several in vivo and in vitro studies have highlighted the association of ferroptosis with beta-cell death and insulin resistance, supported by observations of marked alterations in ferroptotic markers in experimental diabetes models. The constant improvement in understanding ferroptosis in diabetes has demonstrated it as a potential therapeutic target in diabetic management. In this regard, ferroptosis inhibitors promise to rescue pancreatic beta-cell function and alleviate diabetes and its complications. This review article elucidates the key ferroptotic pathways that mediate beta-cell death in diabetes, and its complications. In particular, we share our insight into the cross talk between ferroptosis and other hallmark pathogenic mediators such as oxidative and endoplasmic reticulum stress regulators relevant to diabetes progression. Further, we extensively summarize the recent developments on the role of ferroptosis inhibitors and their therapeutic action in alleviating diabetes and its complications.

VDR activation attenuates osteoblastic ferroptosis and senescence by stimulating the Nrf2/GPX4 pathway in age-related osteoporosis

Ferroptosis plays an essential role in the pathology of osteoporosis. This study investigated whether vitamin D receptor (VDR) activation could protect against age-related osteoporosis through an anti-ferroptosis mechanism. d-galactose (D-gal)-induced mice and VDR-knockout mice were used in the in-vivo study. The VDR activator (1,25(OH)₂D₃) attenuated senescence and ferroptosis in the D-gal-induced bone, as illustrated by downregulated senescence-associated secretory phenotype genes, improved mitochondrial morphology, elevated glutathione, and decreased lipid peroxidation markers (malondialdehyde and 4-hydroxynonenal). The pre-osteoblast MC3T3-E1 cells and primary rat osteoblasts were applied in the in-vitro studies. 1,25(OH)₂D₃ or ferroptosis inhibitor (ferrostatin-1) treatment downregulated the cellular senescence markers in D-gal-induced osteoblasts. Mechanistically, 1,25(OH)₂D₃ activated the VDR and its downstream nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway, resulting in the downregulation of lipid peroxidation. Nrf2 knockdown or addition of GPX4 inhibitor (RSL-3) blocked the protective effect of 1,25(OH)₂D₃ against D-gal-induced ferroptosis and senescence. VDR knockdown impeded the 1,25(OH)₂D₃-induced activation of Nrf2/GPX4 pathway in osteoblasts. Proteomics and immunofluorescence analysis confirmed that ferroptosis and suppression of the Nrf2/GPX4 pathway occurred in VDR-knockout mice. Our data demonstrated that ferroptosis played an essential role in age-related osteoporosis. The VDR activation attenuated osteoblast ferroptosis via stimulating the Nrf2/GPX4 signaling pathway.

Inhibition of ferroptosis attenuates oligospermia in male Nrf2 knockout mice

Nuclear factor-E2-related factor 2 (Nrf2) expression in sperm decreases in some oligospermia patients. However, the mechanism of reduced Nrf2 expression in sperm of oligospermia men is not elucidated. In the present study, our clinical trial results showed that Nrf2 and glutathione peroxidase 4 (GPX4) protein expressions in sperm of oligospermia men significantly decreased than those of healthy men. In animal experiments, mice were randomly divided into 3 groups: wild type (WT), Nrf2 knockout (Nrf2^-/-) and Nrf2^-/- + ferroptosis inhibitor (Fer-1) groups. Fer-1 was intraperitoneally injected in Nrf2^-/- mice for 4 weeks. The results showed that male Nrf2^-/- mice displayed decreased sperm concentration and motility, and significantly lower fertility. Compared with WT mice, malondialdehyde (MDA) content and prostaglandin-endoperoxide synthase 2 (Ptgs2) mRNA expression increased, but nicotinamide adenine dinucleotide phosphate oxidase (NADPH) content decreased in the testes of Nrf2^-/- mice, which were biomarkers of ferroptosis. Furthermore, treatment with Fer-1 in Nrf2^-/- mice reversed the decreased sperm concentration and motility. Meanwhile, histology showed that spermatogenic cells obviously decreased, and vacuolization formed in the testes of Nrf2^-/- mice, which were reversed by Fer-1 treatment. Additionally, compared with WT mice, GPX4, solute carrier family 7 member 11 (SLC7A11), glutamate-cysteine ligase, catalytic subunit (Gclc), glutamate-cysteine ligase, modifier subunit (Gclm) and ferroportin 1 (FPN1) mRNA and protein expressions significantly decreased, but transferrin receptor 1 (TfR1) and divalent metal transporter 1 (DMT1) mRNA and protein expressions increased in testicular tissues in Nrf2^-/- mice. After treatment with Fer-1, only Gclc and Gclm mRNA and protein expressions increased. Taken together, our data suggested that deletion of Nrf2 leads to downregulation of GPX4 and regulation of other ferroptosis-related genes, resulting in ferroptosis occurrence in spermatogenic cells and ultimately oligospermia.

Shenmai Injection Attenuates Myocardial Ischemia/Reperfusion Injury by Targeting Nrf2/GPX4 Signalling-Mediated Ferroptosis

OBJECTIVE

To examine the effect of Shenmai Injection (SMJ) on ferroptosis during myocardial ischemia reperfusion (I/R) injury in rats and the underlying mechanism.

METHODS

A total of 120 SPF-grade adult male SD rats, weighing 220-250 g were randomly divided into different groups according to a random number table. Myocardial I/R model was established by occluding the left anterior descending artery for 30 min followed by 120 min of reperfusion. SMJ was injected intraperitoneally at the onset of 120 min of reperfusion, and erastin (an agonist of ferroptosis), ferrostatin-1 (Fer-1, an inhibitor of ferroptosis) and ML385 (an inhibitor of nuclear factor erythroid-2 related factor 2 (Nrf2)) were administered intraperitoneally separately 30 min before myocardial ischemia as different pretreatments. Cardiac function before ischemia, after ischemia and after reperfusion was analysed. Pathological changes in the myocardium and the ultrastructure of cardiomyocytes were observed, and the myocardial infarction area was measured. Additionally, the concentration of Fe2+ in heart tissues and the levels of creatine kinase-MB (CK-MB), troponin I (cTnl), malondialdehyde (MDA) and superoxide dismutase (SOD) in serum were measured using assay kits, and the expressions of Nrf2, glutathione peroxidase 4 (GPX4) and acyl-CoA synthetase long-chain family member 4 (ACSL4) were examined by Western blot.

RESULTS

Compared with the sham group, I/R significantly injured heart tissues, as evidenced by the disordered, ruptured and oedematous myocardial fibres; the increases in infarct size, serum CK-MB, cTnI and MDA levels, and myocardial Fe2+ concentrations; and the decreases in SOD activity (P<0.05). These results were accompanied by ultrastructural alterations to the mitochondria, increased expression of ACSL4 and inhibited the activation of Nrf2/GPX4 signalling (P<0.05). Compared with I/R group, pretreatment with 9 mL/kg SMJ and 2 mg/kg Fer-1 significantly reduced myocardial I/R injury, Fe2+ concentrations and ACSL4 expression and attenuated mitochondrial impairment, while 14 mg/kg erastin exacerbated myocardial I/R injury (P<0.05). In addition, cardioprotection provided by 9 mL/kg SMJ was completely reversed by ML385, as evidenced by the increased myocardial infarct size, CK-MB, cTnI, MDA and Fe2+ concentrations, and the decreased SOD activity (P<0.05).

CONCLUSIONS

Ferroptosis is involved in myocardial I/R injury. Pretreatment with SMJ alleviated myocardial I/R injury by activating Nrf2/GPX4 signalling-mediated ferroptosis, thereby providing a strategy for the prevention and treatment of ischemic heart diseases.

DNMT3A R882H mutation drives daunorubicin resistance in acute myeloid leukemia via regulating NRF2/NQO1 pathway

BACKGROUND

DNA methyltransferase 3A (DNMT3A) often mutate on arginine 882 (DNMT3A^R882) in acute myeloid leukemia (AML). AML patients with DNMT3A R882 mutation are usually resistant to daunorubicin treatment; however, the associated mechanism is still unclear. Therefore, it is urgent to investigate daunorubicin resistance in AML patients with DNMT3A R882 mutant.

METHOD

AML cell lines with DNMT3A-wild type (DNMT3A-WT), and DNMT3A-Arg882His (DNMT3A-R882H) mutation were constructed to investigate the role of DNMT3A R882H mutation on cell proliferation, apoptosis and cells' sensitivity to Danunorubin. Bioinformatics was used to analyze the role of nuclear factor-E2-related factor (NRF2) in AML patients with DNMT3A R882 mutation. The regulatory mechanism of DNMT3A R882H mutation on NRF2 was studied by Bisulfite Sequencing and CO-IP. NRF2 inhibitor Brusatol (Bru) was used to explore the role of NRF2 in  AML cells carried DNMT3A R882H mutation.

RESULTS

AML cells with a DNMT3A R882H mutation showed high proliferative and anti-apoptotic activities. In addition, mutant cells were less sensitive to daunorubicin and had a higher NRF2 expression compared with those in WT cells. Furthermore, the NRF2/NQO1 pathway was activated in mutant cells in response to daunorubicin treatment. DNMT3A R882H mutation regulated the expression of NRF2 via influencing protein stability rather than decreasing methylation of NRF2 promoter. Also, NRF2/NQO1 pathway inhibition improved mutant cells' sensitivity to daunorubicin significantly.

CONCLUSION

Our findings identified NRF2 as an important player in the regulation of cell apoptosis through which helps mediate chemoresistance to daunorubicin in AML cells with DNMT3A R882H mutation. Targeting NRF2 might be a novel therapeutic approach to treat AML patients with a DNMT3A R882H mutation. Video abstract.

Gingerenone A Alleviates Ferroptosis in Secondary Liver Injury in Colitis Mice via Activating Nrf2-Gpx4 Signaling Pathway

Patients with ulcerative colitis (UC) have been found to be frequently associated with secondary liver injury (SLI). In this study, we investigated the protective effect of GA on dextran sodium sulfate (DSS)-induced SLI in mice and its mechanism. The SLI was established by adding 4% DSS in the drinking water of mice, and the effects of GA (5, 20 mg/kg, p.o., once a day for 7 days) in hepatic tissues were analyzed. HepG2 cells were induced by lipopolysaccharide (LPS) to detect the effect of GA on ferroptosis and the underlying mechanism. Pathological damage was determined by H&E. Liver parameters (AST and ALT), antioxidant enzyme activities (MDA and SOD), and the level of Fe²⁺ in the liver were detected by kits. Cytokine levels (TNF-α, IL-1β, and IL-6) and Gpx4 activity in the liver were detected by ELISA. Finally, the activation of nuclear factor erythroid 2-like 2 (Nrf2) was detected to explore the mechanism. The results indicated that GA significantly attenuated DSS-induced hepatic pathological damage, liver parameters, and cytokine levels and increased the antioxidant enzyme activities. Moreover, GA attenuated ferroptosis in DSS-induced liver injury and upregulated Gpx4 expression in DSS-induced mice. Mechanistic experiments revealed that GA activated Nrf2 in mice. Taken together, this study demonstrates that GA can alleviate ferroptosis in SLI in DSS-induced colitis mice, and its protective effects are associated with activating the Nrf2-Gpx4 signaling pathway.

Effects of an obesogenic diet on the oviduct depend on the duration of feeding

Research question

How long does it take for an obesogenic (high-fat/high-sugar, HF/HS) diet to influence the oviductal microenvironment? What are the affected cellular pathways and are they dependent on the genetic background of the mouse model?

Design

Female Swiss (outbred) and C57BL/6N (B6, inbred) mice were fed either a control (10% fat) or HF/HS (60% fat, 20% fructose) diet. Body weight was measured weekly. Mice were sacrificed at 3 days (3d), 1 week (1w), 4w, 8w, 12w and 16w on the diet (n = 5 per treatment per time point). Total cholesterol concentrations and inflammatory cytokines were measured in serum. Oviductal epithelial cells (OECs) were used to study the expression of genes involved in (mitochondrial) oxidative stress (OS), endoplasmic reticulum (ER) stress and inflammation using qPCR.

Results

Body weight and blood cholesterol increased significantly in the HF/HS mice in both strains compared to controls. In Swiss mice, HF/HS diet acutely increased ER-stress and OS-related genes in the OECs already after 3d. Subsequently, mitochondrial and cytoplasmic antioxidants were upregulated and ER-stress was alleviated at 1w. After 4-8w (mid-phase), the expression of ER-stress and OS-related genes was increased again and persisted throughout the late-phase (12-16w). Serum inflammatory cytokines and inflammatory marker-gene expression in the OECs were increased only in the late-phase. Some of the OEC stress responses were stronger or earlier in the B6.

Conclusions

OECs are sensitive to an obesogenic diet and may exhibit acute stress responses already after a few days of feeding. This may impact the oviductal microenvironment and contribute to diet-induced subfertility.

Protein tyrosine kinase inhibitor resistance in malignant tumors: molecular mechanisms and future perspective

Protein tyrosine kinases (PTKs) are a class of proteins with tyrosine kinase activity that phosphorylate tyrosine residues of critical molecules in signaling pathways. Their basal function is essential for maintaining normal cell growth and differentiation. However, aberrant activation of PTKs caused by various factors can deviate cell function from the expected trajectory to an abnormal growth state, leading to carcinogenesis. Inhibiting the aberrant PTK function could inhibit tumor growth. Therefore, tyrosine kinase inhibitors (TKIs), target-specific inhibitors of PTKs, have been used in treating malignant tumors and play a significant role in targeted therapy of cancer. Currently, drug resistance is the main reason for limiting TKIs efficacy of cancer. The increasing studies indicated that tumor microenvironment, cell death resistance, tumor metabolism, epigenetic modification and abnormal metabolism of TKIs were deeply involved in tumor development and TKI resistance, besides the abnormal activation of PTK-related signaling pathways involved in gene mutations. Accordingly, it is of great significance to study the underlying mechanisms of TKIs resistance and find solutions to reverse TKIs resistance for improving TKIs efficacy of cancer. Herein, we reviewed the drug resistance mechanisms of TKIs and the potential approaches to overcome TKI resistance, aiming to provide a theoretical basis for improving the efficacy of TKIs.

Norcantharidin induces ferroptosis via the suppression of NRF2/HO‑1 signaling in ovarian cancer cells

Increasing evidence has indicated a crucial role of ferroptosis in ovarian cancer (OC). Norcantharidin (NCTD), a normethyl compound of cantharidin, is extensively used in clinical practice as an optional anticancer drug. However, whether NCTD leads to ferroptosis in OC has not been previously explored, at least to the best of our knowledge. In the present study, the effect of NCTD on SKOV3 and OVCAR-3 cells was evaluated. The experimental data of the present study revealed that NCTD significantly suppressed SKOV3 and OVCAR-3 cell viability in a concentration- and time-dependent manner. The results of Cell Counting Kit-8 assay revealed that NCTD treatment decreased SKOV3 and OVCAR-3 cell viability. In comparison, pre-incubation with ferrostatin-1 (Fer-1) significantly reversed the NCTD-induced reduction in SKOV3 and OVCAR-3 cell viability; however, no changes in cell viability were observed when the SKOV3 and OVCAR-3 cells were treated with NCTD, in combination with the apoptosis inhibitor, Z-VAD-FMK, the ferroptosis inhibitor, necrostatin-1, and the autophagy inhibitor, 3-methyladenine. Additionally, it was observed that NCTD markedly enhanced reactive oxygen species production and malondialdehyde and ferrous ion levels in the SKOV3 and OVCAR-3 cells; however, pre-incubation with Fer-1 abolished these effects. Flow cytometry also demonstrated a significant increase in cell death following treatment of the SKOV3 and OVCAR-3 cells with NCTD; however, pre-incubation with Fer-1 also reversed these effects. In vivo experiments demonstrated that NCTD significantly reduced tumor volume and weight. More importantly, it was revealed that nuclear factor erythroid 2-related factor 2 (NRF2), heme oxygenase 1 (HO-1), glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (xCT) expression levels were significantly decreased following NCTD treatment. Collectively, NCTD may represent a potent anticancer agent in OC cells, and NCTD-induced ferroptotic cell death may be achieved by inhibiting the NRF2/HO-1/GPX4/xCT axis.

Inhibition of the PIN1-NRF2/GPX4 axis imparts sensitivity to cisplatin in cervical cancer cells

The incidence of cervical cancer (CC) ranks the fourth in female malignant tumors globally. Chemoresistance is one of the main causes of treatment failure in advanced recurrent CC. Prolyl isomerase 1 (PIN1) is overexpressed in a variety of tumors, and is closely associated with the malignant potential of tumor cells, such as transformation, proliferation, invasion and metastasis. In the present study, we demonstrate that cell death induced by suppression of PIN1 could be inhibited by ferrostatin-1 (Fer-1) and ferroptosis biomarkers including lactate dehydrogenase (LDH) release, lipid peroxidation and malondialdehyde (MDA) are upregulated by downregulating PIN1. We then discover that abrogation of PIN1 greatly decreases the level of glutathione peroxidase 4 (GPX4) and the level of PIN1 is positively correlated with the level of GPX4. Furthermore, the knockdown of PIN1 promotes ferroptosis induced by RSL3. The mechanism involves PIN1 silencing which downregulates GPX4 by decreasing the level of nuclear factor E2-related factor 2 (NRF2). Furthermore, overexpression of NRF2 inhibits RSL3-mediated ferroptosis of CC cells when PIN1 is silenced. In addition, our results indicate that cisplatin (DDP) induces ferroptosis, which is restrained by overexpression of PIN1. The PIN1 inhibitor, KPT-6566, promotes the cytotoxic effect of DDP. The present study reveals that PIN1 affects ferroptosis and sensitivity to DDP in CC cells via the NRF2/GPX4 axis, thereby identifying PIN1 as a potential therapeutic target for CC.

Ferroptosis in sepsis: The mechanism, the role and the therapeutic potential

Sepsis is a common critical illness in the Intensive care unit(ICU) and its management and treatment has always been a major challenge in critical care medicine. The dysregulated host response to infection, causing systemic multi-organ and multi-system damage is the main pathogenesis. Notably, intense stress during sepsis can lead to metabolic disturbances of ions, lipids and energy in the organism. Ferroptosis is an iron-dependent, non-apoptotic cell death distinguished by a disruption of iron metabolism and iron-dependent accumulation of lipid peroxides. Mounting researches have established that ferroptosis has an essential part in anti-inflammatory and sepsis, and drugs targeting ferroptosis-related molecules, such as ferroptosis inhibitors, are gradually proving their effectiveness in sepsis. This paper summarizes and reviews the pathogenesis of ferroptosis, its regulatory network, and its vital involvement in the initiation of sepsis and related organ damage, and finally discusses the possible target drugs provided by the above mechanisms, describes the dilemmas as well as the outlook, in the hope of finding more links between ferroptosis and sepsis and providing new perspectives for the future treatment of sepsis.

Beneficial and Detrimental Roles of Heme Oxygenase-1 in the Neurovascular System

Heme oxygenase (HO) has both beneficial and detrimental effects via its metabolites, including carbon monoxide (CO), biliverdin or bilirubin, and ferrous iron. HO-1 is an inducible form of HO that is upregulated by oxidative stress, nitric oxide, CO, and hypoxia, whereas HO-2 is a constitutive form that regulates vascular tone and homeostasis. In brains injured by trauma, ischemia-reperfusion, or Alzheimer’s disease (AD), the long-term expression of HO-1 can be detected, which can lead to cytotoxic ferroptosis via iron accumulation. In contrast, the transient induction of HO-1 in the peri-injured region may have regenerative potential (e.g., angiogenesis, neurogenesis, and mitochondrial biogenesis) and neurovascular protective effects through the CO-mediated signaling pathway, the antioxidant properties of bilirubin, and the iron-mediated ferritin synthesis. In this review, we discuss the dual roles of HO-1 and its metabolites in various neurovascular diseases, including age-related macular degeneration, ischemia-reperfusion injury, traumatic brain injury, Gilbert’s syndrome, and AD.

Oxidative stress from DGAT1 oncoprotein inhibition in melanoma suppresses tumor growth when ROS defenses are also breached

Dysregulated cellular metabolism is a cancer hallmark for which few druggable oncoprotein targets have been identified. Increased fatty acid (FA) acquisition allows cancer cells to meet their heightened membrane biogenesis, bioenergy, and signaling needs. Excess FAs are toxic to non-transformed cells but surprisingly not to cancer cells. Molecules underlying this cancer adaptation may provide alternative drug targets. Here, we demonstrate that diacylglycerol O-acyltransferase 1 (DGAT1), an enzyme integral to triacylglyceride synthesis and lipid droplet formation, is frequently up-regulated in melanoma, allowing melanoma cells to tolerate excess FA. DGAT1 over-expression alone transforms p53-mutant zebrafish melanocytes and co-operates with oncogenic BRAF or NRAS for more rapid melanoma formation. Antagonism of DGAT1 induces oxidative stress in melanoma cells, which adapt by up-regulating cellular reactive oxygen species defenses. We show that inhibiting both DGAT1 and superoxide dismutase 1 profoundly suppress tumor growth through eliciting intolerable oxidative stress.

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.

Nrf2 Overexpression Decreases Vincristine Chemotherapy Sensitivity Through the PI3K-AKT Pathway in Adult B-Cell Acute Lymphoblastic Leukemia

Uncontrolled proliferation is an important cancer cell biomarker, which plays a critical role in carcinogenesis, progression and development of resistance to chemotherapy. An improved understanding of novel genes modulating cancer cell proliferation and mechanism will help develop new therapeutic strategies. The nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor, decreases apoptosis when its expression is upregulated. However, the relationship between Nrf2 and Vincristine (VCR) chemotherapy resistance in B-cell acute lymphoblastic leukemia (B-ALL) is not yet established. Our results showed that Nrf2 levels could sufficiently modulate the sensitivity of B-ALL cells to VCRby regulating an apoptotic protein, i.e., the Bcl-2 agonist of cell death (BAD). Chemotherapeutic agents used for the treatment of B-ALL induced Nrf2 overactivation and PI3K-AKT pathway activation in the cells, independent of the resistance to chemotherapy; thus, a potential resistance loop during treatment for B-ALL with a drug combination is established. Therefore, B-ALL patients with a high expression of Nrf2 might mean induction chemotherapy with VCR effective little.

Identification and Validation of a GPX4-Related Immune Prognostic Signature for Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is a commonly occurring histological subtype of lung cancer. Glutathione peroxidase 4 (GPX4) is an important regulatory factor of ferroptosis and is involved in the development of many cancers, but its prognostic significance has not been systematically described in LUAD. In this study, we focused on developing a robust GPX4-related prognostic signature (GPS) for LUAD. Data for the training cohort was extracted from The Cancer Genome Atlas, and that for the validation cohort was sourced from the GSE72094 dataset including 863 LUAD patients. GPX4-related genes were screened out by weighted gene coexpression network analysis and Spearman’s correlation analysis. Then, Cox regression and least absolute shrinkage and selection operator regression analyses were employed to construct a GPS. The ESTIMATE algorithm, single-sample gene set enrichment analysis (ssGSEA), and GSEA were utilized to evaluate the relationship between GPS and the tumor microenvironment (TME). We constructed and validated a GPS premised on four GPX4-related genes (KIF14, LATS2, PRKCE, and TM6SF1), which could classify LUAD patients into low- and high-score cohorts. The high-risk cohort presented noticeably poorer overall survival (OS) as opposed to the low-risk cohort, meaning that the GPS may be utilized as an independent predictor of the OS of LUAD. The GPS was also adversely correlated with multiple tumor-infiltrating immune cells and immune-related processes and pathways in TME. Furthermore, greater sensitivity to erlotinib and lapatinib were identified in the low-risk cohort based on the GDSC database. Our findings suggest that the GPS can effectively forecast the prognosis of LUAD patients and may possibly regulate the TME of LUAD.

The Value of Serum Exosomal miR-184 in the Diagnosis of NSCLC

Lung cancer has the highest morbidity rate (11.6%) and mortality rate (18.4%) among all current tumors. The morbidity rate in China accounts for approximately one-third, and it is still rising. Nonsmall cell lung cancer is the most common type of lung cancer, accounting for 80%-85% of all lung cancers, and approximately 57% of patients with advanced nonsmall cell lung cancer have distant metastases at the time of diagnosis. To explore the expression changes in microRNA-184 (miR-184) and its clinical value in serum exosomes of patients with nonsmall cell lung cancer (NSCLC). This study adopted a case-control study method, selecting 88 patients (NSCLC group) from June 2015 to June 2017 in our hospital who are confirmed to have NSCLC by fiber-optic bronchoscopy, and 90 patients who are confirmed to have benign lung diseases by pathological examination during the same period (control group). Fluorescence quantitative PCR technology is used to detect the levels of miR-184 in serum exosomes of the two groups, and the differences in the levels of miR-184 in serum exosomes of NSCLC patients with different pathological characteristics are analyzed. According to the results of the 3-year follow-up, the miR-184 levels in serum exosomes of NSCLC patients are grouped and compared. The expression level of miR-184 in serum exosomes in the NSCLC group is significantly higher than that in the control group, and the difference between the two groups is statistically significant (p < 0.05). The ROC curve is drawn with the expression level of miR-184 in serum exosomes of the two groups of patients. The results showed that the area under the ROC curve for the differential diagnosis of NSCLC and benign lung tumors with the expression level of miR-184 in serum exosomes is 0.927, and the sensitivity is 87.61%, while the specificity is 84.02%. The expression levels of miR-184 in serum exosomes of NSCLC patients with different pathological characteristics, in different TNM stages [(I+II) vs. (III+IV)], lymph node metastasis (yes vs. no), and different degrees of differentiation [(High + Medium) vs. Poorly differentiated] are compared and showed statistical significance (p < 0.05). In 88 NSCLC patients, after 3 years of follow-up, 33 survived, and 55 died, with a survival rate of 37.50%. The expression of miR-184 in serum exosomes of the 33 surviving patients is significantly lower than that of the nonsurviving group (p < 0.05). The expression level of miR-184 in serum exosomes of NSCLC patients is significantly increased, which has a certain value for the differential diagnosis of the nature of benign and malignant lung diseases and is closely related to the prognosis of patients.

Targeting lncRNAs in programmed cell death as a therapeutic strategy for non-small cell lung cancer

Lung cancer is a leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the most common histological type. Owing to the limited therapeutic efficacy and side effects of currently available therapies for NSCLC, it is necessary to identify novel therapeutic targets for NSCLC. Long non-coding RNAs (lncRNAs) are non-protein-coding RNAs with a transcript length of more than 200 nucleotides, which play a vital role in the tumorigenesis and progression of multiple cancers, including NSCLC. Induction of programmed cell death (PCD) is the main mechanism leading to tumour cell death in most cancer treatments. Recent studies have demonstrated that lncRNAs are closely correlated with PCD including apoptosis, pyroptosis, autophagy and ferroptosis, which can regulate PCD and relevant death pathways to affect NSCLC progression and the efficacy of clinical therapy. Therefore, in this review, we focused on the function of lncRNAs in PCD of NSCLC and summarized the therapeutic role of targeting lncRNAs in PCD for NSCLC treatment, aiming to provide new sights into the underlying pathogenic mechanisms and propose a potential new strategy for NSCLC therapy so as to improve therapeutic outcomes with the ultimate goal to benefit the patients.

Potential Role of APEX1 During Ferroptosis

Ferroptosis is a recently discovered category of programmed cell death. It is much different from other types of cell death such as apoptosis, necrosis and autophagy. The main pathological feature of ferroptosis is the accumulation of iron-dependent lipid peroxidation. The typical changes in the morphological features of ferroptosis include cell volume shrinkage and increased mitochondrial membrane area. The mechanisms of ferroptosis may be mainly related to lipid peroxidation accumulation, imbalance in amino acid antioxidant system, and disturbance of iron metabolism. Besides, hypoxia-inducible factor (HIF), nuclear factor-E2-related factor 2 (Nrf2), and p53 pathway have been demonstrated to be involved in ferroptosis. At present, the molecular mechanisms of ferroptosis pathway are still unmapped. In this review, an outlook has been put forward about the crucial role of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) in the regulation of ferroptosis. APEX1 plays an important role in the regulation of intracellular redox balance and can be used as a potential inhibitor of ferroptotic cell death. Bioinformatics analysis indicated that the mRNA level of APEX1 is decreased in cases of ferroptosis triggered by erastin. Besides, it was found that there was a significant correlation between APEX1 and genes in the ferroptosis pathway. We have discussed the possibility to employ APEX1 inducers or inhibitors in the regulation of ferroptosis as a new strategy for the treatment of various human diseases.

NRF2 and Key Transcriptional Targets in Melanoma Redox Manipulation

Melanocytes are dendritic, pigment-producing cells located in the skin and are responsible for its protection against the deleterious effects of solar ultraviolet radiation (UVR), which include DNA damage and elevated reactive oxygen species (ROS). They do so by synthesizing photoprotective melanin pigments and distributing them to adjacent skin cells (e.g., keratinocytes). However, melanocytes encounter a large burden of oxidative stress during this process, due to both exogenous and endogenous sources. Therefore, melanocytes employ numerous antioxidant defenses to protect themselves; these are largely regulated by the master stress response transcription factor, nuclear factor erythroid 2-related factor 2 (NRF2). Key effector transcriptional targets of NRF2 include the components of the glutathione and thioredoxin antioxidant systems. Despite these defenses, melanocyte DNA often is subject to mutations that result in the dysregulation of the proliferative mitogen-activated protein kinase (MAPK) pathway and the cell cycle. Following tumor initiation, endogenous antioxidant systems are co-opted, a consequence of elevated oxidative stress caused by metabolic reprogramming, to establish an altered redox homeostasis. This altered redox homeostasis contributes to tumor progression and metastasis, while also complicating the application of exogenous antioxidant treatments. Further understanding of melanocyte redox homeostasis, in the presence or absence of disease, would contribute to the development of novel therapies to aid in the prevention and treatment of melanomas and other skin diseases.

Cur@SF NPs alleviate Friedreich's ataxia in a mouse model through synergistic iron chelation and antioxidation

Abnormal iron metabolism, mitochondrial dysfunction and the derived oxidative damage are the main pathogeneses of Friedrich's ataxia (FRDA), a single-gene inherited recessive neurodegenerative disease characterized by progressive cerebellar and sensory ataxia. This disease is caused by frataxin (FXN) mutation, which reduces FXN expression and impairs iron sulfur cluster biogenesis. To date, there is no effective therapy to treat this condition. Curcumin is proposed harboring excellent ability to resist oxidative stress through Nrf2 activation and its newly found ability to chelate iron. However, its limitation is its poor water solubility and permeability. Here, we synthesized slow-release nanoparticles (NPs) by loading curcumin (Cur) into silk fibroin (SF) to form NPs with an average size of 150 nm (Cur@SF NPs), which exhibited satisfactory therapeutic effects on the improvement of FRDA manifestation in lymphoblasts (1 μM) derived from FRDA patients and in YG8R mice (150 mg/kg/5 days). Cur@SF NPs not only removed iron from the heart and diminished oxidative stress in general but also potentiate iron-sulfur cluster biogenesis, which compensates FXN deficiency to improve the morphology and function of mitochondria. Cur@SF NPs showed a significant advantage in neuron and myocardial function, thereby improving FRDA mouse behavior scores. These data encourage us to propose that Cur@SF NPs are a promising therapeutic compound in the application of FRDA disease.

Yeast β-glucan increases etoposide sensitivity in lung cancer cell line A549 by suppressing Nrf2 via the non-canonical NF-κB pathway

Etoposide is regarded as one of the main standard cytotoxic drugs for lung cancer. However, mutations in Keap1, the main regulator of nuclear factor erythroid 2-related factor 2 (Nrf2), are often detected in lung cancer and lead to chemoresistance. Since the aberrant activation of Nrf2 enhances drug resistance, the suppression of the Nrf2 pathway is a promising therapeutic strategy for lung cancer. We herein used the human lung adenocarcinoma cell line A549 because it harbors a Keap1 loss-of-function mutation. A treatment with β-glucan, a major component of the fungal cell wall, reduced Nrf2 protein levels, down-regulated the expression of CYP3A5, UGT1A1, and MDR1, and increased etoposide sensitivity in A549 cells. Furthermore, the ephrin type-A receptor 2 (EphA2) receptor was important for the recognition and biological activity of β-glucan in A549 cells. EphA2 signaling includes nuclear factor kappa B (NF-κB), STAT3, and p38 mitogen-activated protein kinase (MAPK). However, treatment of cells with stattic (STAT3 inhibitor) or SB203580 (p38 MAPK inhibitor) did not diminish the effects of β-glucan. In contrast, knockdown of RelB abolished the effects of β-glucan, suggesting the involvement of the non-canonical NF-κB pathway. The β-glucan effects were also attenuated by the knockdown of WDR23. The β-glucan treatment and RelB overexpression induced the expression of CUL4A, which increased WDR23 ligase activity and promoted the subsequent depletion of Nrf2. These results revealed a novel property of β-glucan as a resistance-modifying agent in addition to its widely reported immunomodulatory effects for lung cancer therapy via the EphA2-RelB-CUL4A-Nrf2 axis. Significance Statement Chemotherapeutic resistance remains a major obstacle in cancer therapy despite extensive efforts to elucidate the underlying molecular mechanisms and overcome multidrug resistance. The present study revealed a novel resistance-modifying property of β-glucan, thereby expanding our knowledge on the beneficial roles of β-glucan and providing an alternative strategy to prevent drug resistance by cancer. The present results provide evidence for the involvement of a novel mode of NF-κB and Nrf2 crosstalk in the drug resistance phenotype.

Identification of Targetable Liabilities in the Dynamic Metabolic Profile of EGFR-Mutant Lung Adenocarcinoma: Thinking beyond Genomics for Overcoming EGFR TKI Resistance

The use of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) as first-line treatment in patients with lung adenocarcinoma (LUAD) harboring EGFR-activating mutations has resulted in a dramatic improvement in the management of the disease. However, the long-term clinical benefit is inevitably compromised by multiple resistance mechanisms. Accumulating evidence suggests that metabolic landscape remodeling is one of the mechanisms that EGFR-mutant LUAD cells activate, thus acquiring higher plasticity, tolerating EGFR TKI-mediated cytotoxic stress, and sustaining their oncogenic phenotype. Several metabolic pathways are upregulated in EGFR TKI-resistant models modulating the levels of numerous metabolites such as lipids, carbohydrates, and metabolic enzymes which have been suggested as potential mediators of resistance to EGFR TKIs. Moreover, metabolites have been shown to carry signals and stimulate oncogenic pathways and tumor microenvironment (TME) components such as fibroblasts, facilitating resistance to EGFR TKIs in various ways. Interestingly, metabolic signatures could function as predictive biomarkers of EGFR TKI efficacy, accurately classifying patients with EGFR-mutant LUAD. In this review, we present the identified metabolic rewiring mechanisms and how these act either independently or in concert with epigenetic or TME elements to orchestrate EGFR TKI resistance. Moreover, we discuss potential nutrient dependencies that emerge, highlighting them as candidate druggable metabolic vulnerabilities with already approved drugs which, in combination with EGFR TKIs, might counteract the solid challenge of resistance, hopefully prolonging the clinical benefit.

Nrf2 activation mediates the protection of mouse Sertoli Cells damage under acute heat stress conditions

Heat stress is known to negatively impact the reproductive process of livestock, which inevitably leads to a decline in animal fertility. Nuclear factor E2-related factor 2 (Nrf2) is an inducible transcription factor, which is essential for maintaining redox signal transmission against oxidative stress. However, there is no reliable research on the response mechanism of Sertoli Cells (SCs) against heat stress and the activation of Nrf2 when SCs are exposed to heat stress. Here, we used primary mouse SCs and SCs line TM4, along with Nrf2 specific inhibitor to determine the reaction mechanism of SCs to maintain intracellular redox homeostasis and self-survival by activating Nrf2. We found that acute heat stress only affected the vitality of SCs and the expression of functional molecules (tight junction-associated proteins and lactate dehydrogenase A [LDHA]) but did not cause cell apoptosis. When Nrf2 was inhibited, more cell death occurred in TM4 cells post heat stress treatment, along with a greater decrease in cell viability and a significant increase in intracellular ROS levels. Our study clarified for the first time the protective effect of Nrf2 activation on heat stress-induced SCs damage. It explained the possible reasons or mechanisms involved in the survival of SCs, the critical protective cells in the testis, which were not affected by heat stress. This study further improved the response mechanism of SCs in the reproductive injury caused by a high-temperature environment.