Targeting NRF2 and Its Downstream Processes: Opportunities and Challenges

Hyperhomocysteinaemia aggravates periodontitis by suppressing the Nrf2/HO-1 signalling pathway

Periodontitis, a common dental illness, causes periodontal tissue inflammation and irreversible bone loss, inevitably resulting in tooth loss. Hyperhomocysteinaemia (HHcy), defined as blood total homocysteine (Hcy) levels greater than 15 µmol/L, is linked to increased cardiovascular disease risk. Mounting evidence indicates a connection between HHcy and periodontitis; however, the underlying processes remain unknown. Herein, we explored the mechanisms by which HHcy exacerbates periodontal tissue inflammation and osteoclast formation. In an animal model of periodontitis treated with HHcy, periodontal attachment loss was aggravated, and both systemic and gingival tissue inflammation levels tended to increase; additionally, antioxidant-related proteins were suppressed and expressed at low levels, whereas oxidative damage-related protein expression increased. In RAW264.7 cells treated with LPS or LPS + Hcy, the LPS + Hcy group presented increased reactive oxygen species (ROS) fluorescence intensity, and Nrf2/HO-1 signalling pathway suppression was associated with inflammatory cytokine (TNF-α) expression. In monocyte osteoclasts treated with Rankl or Rankl + Hcy, the Rankl + Hcy group presented Nrf2/HO-1 signalling pathway suppression, an increase in osteoclast-related proteins (NFATc-1 and CTSK), and a more pronounced osteoclastic phenotype. Therefore, HHcy may exacerbate inflammation severity and osteoclast generation in periodontitis by promoting ROS production and inhibiting the Nrf2/HO-1 signalling pathway.

Purslane leaf powder dietary supplementation rescues cadmium-induced disruption of behavior, antioxidant status, and expression of tight junction genes, in the brain of Nile tilapia (Oreochromis niloticus)

This study examined the effects of supplementing the Nile tilapia (Oreochromis niloticus) diet with purslane (Portulaca oleracea L.) leaf powder (PLNP, 10 g/kg) on neurobehavioral performance, brain oxidative status, tight junction mRNA expression, and brain histology in fish exposed to waterborne cadmium (Cd, 50 μg /L) for 60 days. Adding PLNP to the diet ameliorated the Cd-induced decline in ingestive behavior and swimming behavior, and reversed the Cd-induced increase in aggressive behavior. The significant decrease in the non-enzymatic (reduced glutathione) and enzymatic (catalase and superoxide dismutase) brain antioxidants detected in Cd-exposed fish was eliminated by dietary PLNP. PLNP supplementation also led to a decrease in brain malondialdehyde content, which was elevated by Cd exposure. In addition, dietary PLNP increased brain acetylcholinesterase content, upregulated mRNA expression of tight junction (zo-2, claudin-4, and zo-1) and oxidative stress genes (sod-2, gpx, and nrf-2), and downregulated apoptotic genes (p53, caspase-9, caspase-8, and caspase-3) in the brain, relative to the alterations in these parameters caused by Cd exposure. Furthermore, the Cd-induced histological changes in the Nile tilapia brain were ameliorated by PLNP dietary supplementation. In light of these findings, PLNP may be a useful dietary supplement for reducing the harmful effects of Cd on the brain and behavior of Nile tilapia.

The clinical-grade CBP/ p300 inhibitor CCS1477 represses the global NRF2-dependent cytoprotective transcription program and re-sensitizes cancer cells to chemotherapeutic drugs

Constitutive activation of NRF2 provides a selective advantage to malignant tumour clones through the hijacking of the NRF2-dependent cytoprotective transcriptional program, which allows the cancer cells to survive and thrive in the chemically stressful tumour niche, whilst also providing resistance to anti-cancer drugs due to the upregulation of xenobiotic metabolizing enzymes and drug efflux pumps. Through a small-molecule epigenetic screen carried out in KEAP1 mutant lung cancer cells, in this study, we identified CCS1477 (Inobrodib) to be an inhibitor of the global NRF2-dependent transcription program. Mechanistically, CCS1477 is able to repress NRF2's cytoprotective response through the inhibition of its obligate transcriptional activator partner CBP/p300. Importantly, in addition to repressing NRF2-dependent anti-oxidative stress and xenobiotic metabolizing enzyme gene expression, CCS1477 treatment is also able to reverse the chemoresistance phenotype and re-sensitize NRF2-activated tumour cells to anti-cancer drugs. Furthermore, in co-culture experiments of KEAP1 mutant cancer cells with primary human T cells, CCS1477 treatment suppressed the acquisition of the T cell exhaustion transcriptional state, which should function to augment the anti-cancer immune response. Thus, CCS1477-mediated inhibition of CBP/p300 represents a novel therapeutic strategy with which to target the currently untreatable tumours with aberrant NRF2 activation.

Lipotoxicity, lipid peroxidation and ferroptosis: a dilemma in cancer therapy

The vulnerability of tumor cells to lipid peroxidation, driven by redox imbalance and lipid overabundance within the tumor microenvironment (TME), has become a focal point for novel antitumor strategies. Ferroptosis, a form of regulated cell death predicated on lipid peroxidation, is emerging as a promising approach. Beyond their role in directly eliminating tumor cells, lipid peroxidation and its products, such as 4-hydroxynonenal (HNE), exert an additional influence by damaging DNA and shaping an environment conducive to tumor growth and metastasis. This process polarizes macrophages towards a pro-inflammatory phenotype, dampens the antigen-presenting capacity of dendritic cells (DCs), and undermines the cytotoxic functions of T and NK cells. Furthermore, it transforms neutrophils into pro-tumorigenic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). The lipid peroxidation of stroma cells also contributes to tumor progression. Although advanced nanotherapies have shown the ability to target tumor cells precisely, they often overlook the nuanced effects of lipid peroxidation products. In this review, we highlight a synergistic mechanism in which lipid peroxidation products and ferroptosis contribute to an immunosuppressive state that is temporally distinct from cell death. This insight broadens our understanding of ferroptosis-derived immunosuppression, encompassing all types of immune cells within the TME. This review aims to catalyze further research in this underexplored area, emphasizing the potential of lipid peroxidation products to hinder the clinical translation of ferroptosis-based therapies.

5-methoxytryptophan ameliorates renal ischemia/reperfusion injury by alleviating endoplasmic reticulum stress-mediated apoptosis through the Nrf2/HO-1 pathway

Background

Renal ischemia/reperfusion (I/R) injury is a prevalent clinical complication characterized by high incidence and mortality rates. The endogenous metabolite, 5-Methoxytryptophan (5-MTP), derived from tryptophan, possesses anti-inflammatory and antioxidant properties. However, its role in renal I/R injury remains unclear. In this study, we investigated whether 5-MTP could protect the kidney from I/R injury by ameliorating endoplasmic reticulum stress (ERS)-mediated apoptosis through the Nrf2/HO-1 pathway.

Methods and results

We established models to examine renal I/R injury in C57BL/6J mice with bilateral renal pedicles clamped and HK-2 cells subjected to hypoxia/reoxygenation (H/R). The administration of 5-MTP improved renal tissue damage and kidney dysfunction impairment and reduced inflammation and oxidative stress. Moreover, 5-MTP attenuated ERS and ERS-mediated apoptosis, while upregulating Nrf2 and HO-1 expression. Additionally, Nrf2-deficient mice and cells were used to determine whether the Nrf2/HO-1 pathway was involved in the role of 5-MTP in alleviating ERS-mediated apoptosis. Nrf2 deficiency led to a partial reduction in the suppressive effects of 5-MTP on inflammation, oxidative stress, and ERS-mediated apoptosis.

Conclusion

Our findings suggest that 5-MTP alleviates renal I/R injury by inhibiting ERS-related apoptosis via the Nrf2/HO-1 pathway.

Pharmacological Inhibition of TXNRD1 by a Small Molecule Flavonoid Butein Overcomes Cisplatin Resistance in Lung Cancer Cells

Mammalian cytosolic selenoprotein thioredoxin reductase (TXNRD1) is crucial for maintaining the reduced state of cellular thioredoxin 1 (TXN1) and is commonly up-regulated in cancer cells. TXNRD1 has been identified as an effective target in cancer chemotherapy. Discovering novel TXNRD1 inhibitors and elucidating the cellular effects of TXNRD1 inhibition are valuable for developing targeted therapies based on redox regulation strategies. In this study, we demonstrated that butein, a plant-derived small molecule flavonoid, is a novel TXNRD1 inhibitor. We found that butein irreversibly inhibited recombinant TXNRD1 activity in a time-dependent manner. Using TXNRD1 mutant variants and LC-MS, we identified that butein modifies the catalytic cysteine (Cys) residues of TXNRD1. In cellular contexts, butein promoted the accumulation of reactive oxygen species (ROS) and exhibited cytotoxic effects in HeLa cells. Notably, we found that pharmacological inhibition of TXNRD1 by butein overcame the cisplatin resistance of A549 cisplatin-resistant cells, accompanied by increased cellular ROS levels and enhanced expression of p53. Taken together, the results of this study demonstrate that butein is an effective small molecule inhibitor of TXNRD1, highlighting the therapeutic potential of inhibiting TXNRD1 in platinum-resistant cancer cells.

Lactylation-Driven HECTD2 Limits the Response of Hepatocellular Carcinoma to Lenvatinib

Drug resistance remains a major hurdle for the therapeutic efficacy of lenvatinib in hepatocellular carcinoma (HCC). However, the underlying mechanisms remain largely undetermined. Unbiased proteomic screening is performed to identify the potential regulators of lenvatinib resistance in HCC. Patient-derived organoids, patient-derived xenograft mouse models, and DEN/CCl4 induced HCC models are constructed to evaluate the effects of HECTD2 both in vitro and in vivo. HECTD2 is found to be highly expressed in lenvatinib-resistant HCC cell lines, patient tissues, and patient-derived organoids and xenografts. In vitro and in vivo experiments demonstrated that overexpression of HECTD2 limits the response of HCC to lenvatinib treatment. Mechanistically, HECTD2 functions as an E3 ubiquitin ligase of KEAP1, which contributes to the degradation of KEAP1 protein. Subsequently, the KEAP1/NRF2 signaling pathway initiates the antioxidative response of HCC cells. Lactylation of histone 3 on lysine residue 18 facilitates the transcription of HECTD2. Notably, a PLGA-PEG nanoparticle-based drug delivery system is synthesized, effectively targeting HECTD2 in vivo. The NPs achieved tumor-targeting, controlled-release, and biocompatibility, making them a promising therapeutic strategy for mitigating lenvatinib resistance. This study identifies HECTD2 as a nanotherapeutic target for overcoming lenvatinib resistance, providing a theoretical basis and translational application for HCC treatment.

Copper-luteolin nanocomplexes for Mediating multifaceted regulation of oxidative stress, intestinal barrier, and gut microbiota in inflammatory bowel disease

Oxidative stress, dysbiosis, and immune dysregulation have been confirmed to play pivotal roles in the complex pathogenesis of inflammatory bowel disease (IBD). Herein, we design copper ion-luteolin nanocomplexes (CuL NCs) through a metal-polyphenol coordination strategy, which plays a multifaceted role in the amelioration of IBD. The fabricated CuL NCs function as therapeutic agents with exceptional antioxidant and anti-inflammatory capabilities because of their great stability and capacity to scavenge reactive oxygen species (ROS). It can effectively modulate the inflammatory microenvironment including facilitating the efficient reduction of pro-inflammatory cytokine levels, protecting intestinal epithelial cells, promoting mucosal barrier repair and regulating intestinal microbiota. In addition, CuL NCs have been found to enhance cellular antioxidant and anti-inflammatory capacities by regulating the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) oxidative stress pathway and nuclear factor kappa B (NF-κB) signaling pathway, respectively. Notably, CuL NCs demonstrate significant prophylactic and therapeutic efficacy in mouse models with typical IBD, including ulcerative colitis (UC) and Crohn's disease (CD). This study provides a new approach for building multifaceted therapeutic platforms for natural products to treat IBD.

Redox regulation: mechanisms, biology and therapeutic targets in diseases

Redox signaling acts as a critical mediator in the dynamic interactions between organisms and their external environment, profoundly influencing both the onset and progression of various diseases. Under physiological conditions, oxidative free radicals generated by the mitochondrial oxidative respiratory chain, endoplasmic reticulum, and NADPH oxidases can be effectively neutralized by NRF2-mediated antioxidant responses. These responses elevate the synthesis of superoxide dismutase (SOD), catalase, as well as key molecules like nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), thereby maintaining cellular redox homeostasis. Disruption of this finely tuned equilibrium is closely linked to the pathogenesis of a wide range of diseases. Recent advances have broadened our understanding of the molecular mechanisms underpinning this dysregulation, highlighting the pivotal roles of genomic instability, epigenetic modifications, protein degradation, and metabolic reprogramming. These findings provide a foundation for exploring redox regulation as a mechanistic basis for improving therapeutic strategies. While antioxidant-based therapies have shown early promise in conditions where oxidative stress plays a primary pathological role, their efficacy in diseases characterized by complex, multifactorial etiologies remains controversial. A deeper, context-specific understanding of redox signaling, particularly the roles of redox-sensitive proteins, is critical for designing targeted therapies aimed at re-establishing redox balance. Emerging small molecule inhibitors that target specific cysteine residues in redox-sensitive proteins have demonstrated promising preclinical outcomes, setting the stage for forthcoming clinical trials. In this review, we summarize our current understanding of the intricate relationship between oxidative stress and disease pathogenesis and also discuss how these insights can be leveraged to optimize therapeutic strategies in clinical practice.

Paeonol ameliorates ferroptosis and inflammation in chondrocytes through AMPK/Nrf2/GPX4 pathway

Introduction

Chondrocyte ferroptosis is an important component of the pathogenesis of osteoarthritis. Paeonol, the main pharmacologically active ingredient of the Paeonia suffruticosa Andrews, is a natural radical scavenger with potent biological activities, including antioxidant, anti-inflammatory, and cartilage protection effects. However, the molecular mechanisms underlying its role in regulating chondrocytes ferroptosis remain unclear.

Methods

To investigate the effect of paeonol on ferroptosis and inflammation of chondrocytes through interleukin-1β (IL-1β), the proliferation activity, lipid peroxidation level, endogenous antioxidant capacity, and mitochondrial membrane potential of chondrocytes were evaluated in detail. Intracellular ferrous ion concentration was detected by FerroOrange fluorescent probe staining. Western blotting and immunofluorescence staining were used to detect biomarker proteins of ferroptosis, inflammation, and AMPK/Nrf2/GPX4 signaling pathway proteins.

Results

The results showed that paeonol significantly depressed IL-1β-induced ferroptosis and inflammation in chondrocytes. Specifically, paeonol protects cell viability, reduces lipid peroxidation damage, maintains mitochondrial function, and inhibits pro-ferroptosis and pro-inflammation biomarker proteins. In addition, the anti-inflammatory ability of paeonol was partially inhibited after the addition of ferroptosis agonist erastin, suggesting that paeonol protects against inflammatory injury in part by inhibiting ferroptosis. Further studies showed that paeonol activated AMPK phosphorylation and promoted Nrf2 nuclear translocation and Keap1 degradation. Finally, the AMPK-Nrf2-GPX4 signaling pathway was confirmed to be the underlying mechanism of paeonol against ferroptosis by the simultaneous use of the AMPK agonist and Nrf2 inhibitor.

Conclusion

These results indicate that paeonol significantly inhibits IL-1β-induced ferroptosis and inflammation in chondrocytes, and the underlying mechanism of paeonol against ferroptosis is partly through the AMPK/Nrf2/GPX4 axis.

Dulaglutide accelerates diabetic wound healing by suppressing Nrf2-dependent ferroptosis in diabetic mice

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are frequently utilized to treat type 2 diabetes mellitus (T2DM). Several GLP-1RAs (Exendin-4 and liraglutide) have been shown to accelerate diabetic wound healing. The major aim of the study was to investigate the roles of dulaglutide in wound healing in diabetic mice and identify the underlying mechanism involved. Round-shape, full-thickness wounds were created on the backs of db/db diabetic mice. Subsequently, dulaglutide was delivered via subcutaneous injections surrounding the wound's perimeter, and the wound closure rates were monitored. In vitro, keratinocytes were treated with dulaglutide under high glucose (HG) conditions, and cell viability was assessed by cell counting kit-8 (CCK-8) and EdU assays. The roles of dulaglutide in ferroptosis were assessed by measuring the levels of Fe2 + and oxidative stress, as well as the expression of ferroptosis markers. The results demonstrated that dulaglutide treatment increased the expression of vascular endothelial growth factor (VEGF) and the proliferation marker Ki67, thereby accelerating wound healing in diabetic mice. In vitro, dulaglutide promoted HaCaT cell proliferation and migration under HG conditions. Exposure of HaCaT cells to HG resulted in ferroptosis in vivo and in vitro, as evidenced by the significant increase in Fe2+, reactive oxygen species (ROS), and malondialdehyde (MDA) levels and the decrease in glutathione (GSH) and superoxide dismutase (SOD) levels. All these effects were reversed by dulaglutide. Mechanistically, dulaglutide activated NFE2-related factor 2 (Nrf2) signaling under HG conditions, which increased glutathione peroxidase (Gpx4) and solute carrier family 7-member 11 (Slc7a11) expression, thereby inhibiting ferroptosis. In summary, these results demonstrate dulaglutide as a promising agent for treating diabetic wounds by regulating Nrf2-dependent ferroptosis.

Bioactive Decellularized Extracellular Matrix Platform Integrating Multifunctional Nanozymes and Cell-Laden Microgels for Acute Liver Failure Treatment

Mesenchymal stem cell (MSC) therapy has emerged as a promising alternative approach for treating acute liver failure (ALF) while confronting the shortage of low efficiency and poor engraftment within a hostile liver milieu. In this study, we establish a bioactive decellularized extracellular matrix (dECM) platform that incorporates dihydrolipoic acid (DHLA)-protected Pt nanoclusters doped with Cu (PtCu-DHLA) nanozymes and cell-laden microgels. The PtCu-DHLA nanozymes, selected for their versatility, function as antioxidant, anti-inflammatory, pro-proliferative, and pro-angiogenic agents, enhancing ALF alleviation and providing an optimal microenvironment for MSC transplantation. Additionally, a methacrylic anhydride (MA)-modified porcine liver-derived decellularized extracellular matrix (PLdECM) hydrogel (PLdECMMA) has been developed for the construction of microgels via microfluidic devices. Interferon γ (IFNγ) preconditioned MSCs encapsulated in PLdECMMA microgels exhibit enhanced immunomodulating activity and prolonged survival. PtCu-DHLA nanozymes and cell-laden microgels are codelivered by leveraging the PLdECM hydrogel for orthotopic transplantation. The transplanted dECM platform enables an efficient and successful rescue of CCl4-induced ALF by counteracting oxidative stress, suppressing inflammatory storms, and promoting cellular regeneration. Overall, this study highlights a synergistic and reinforced strategy that combines biomimetic nanozymes with MSC therapy, offering significant potential for ALF treatment and broader applications in regenerative medicine.

Oxidative Stress and Redox Signaling in Gastric Cancer: From Mechanisms to Therapeutic Implications

Oxidative stress, which is characterized by an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, has critical roles in the initiation, progression, and treatment of gastric cancer. On the one hand, an excessive ROS accumulation induces oxidative damage and cancer cell death. On the other hand, moderate levels of ROS cause genetic mutations and dysregulation of signaling pathways to promote proliferation, inflammation, angiogenesis, and metastasis in gastric cancer. Notably, emerging evidence has revealed that ROS also mediate oxidative post-translational modifications (oxPTMs) of redox-sensitive proteins, which can directly affect protein functions and regulate redox signaling in cancer cells. Therefore, elucidating the regulatory mechanisms of oxidative stress and redox signaling in gastric cancer holds great promise to identify novel therapeutic targets or redox-targeting strategies. This review will summarize the mechanisms of oxidative stress in regulating the hallmarks of gastric cancer and highlight the roles of ROS-mediated oxPTMs in gastric cancer. In addition, we will discuss emerging strategies targeting oxidative stress for the treatment of gastric cancer, with an emphasis on the use of bioactive natural products and nanomaterials.

Evidence for a Functional Link Between the Nrf2 Signalling Pathway and Cytoprotective Effect of S-Petasin in Human Retinal Pigment Epithelium Cells Exposed to Oxidative Stress

The retinal pigment epithelium (RPE) is a highly specialised monolayer epithelium subjected to constant oxidative stress, which, in the long term, favours the development of a complex pathological process that is the underlying cause of macular damage. Therefore, counteracting the overproduction of ROS is the best-researched approach to preserve the functional integrity of the RPE. S-Petasin, a secondary metabolite extracted from the plant Petasites hybridus, has numerous biological effects, which highlight its anti-inflammatory and antioxidative properties. The aim of our study is to investigate whether S-Petasin exerts cytoprotective effects by protecting the RPE from oxidative damage. The effects of pretreatment with S-Petasin were assessed by the determination of the cell viability, intracellular ROS levels, activation of the Nrf2 pathway and the resulting post-transcriptional antioxidant/antiapoptotic response. Our results show that S-Petasin pretreatment (1) reduces intracellular ROS levels, improving cell viability of RPE exposed to oxidative damage; (2) activates the Nrf2 signalling pathway, modulating the post-transcriptional response of its antioxidant chemical biomarkers; (3) reduces the Bax levels, and an increase in those of Bcl-2, with a concomitant downregulation of the Bax/Bc-2 ratio. Overall, our results provide the first evidence that S-Petasin is able to protect the RPE from oxidative damage.

Polydatin protects against DSS-induced ulcerative colitis via Nrf2/Slc7a11/Gpx4-dependent inhibition of ferroptosis signalling activation

Introduction

Ulcerative colitis (UC), a form of inflammatory irritable bowel disease, is characterized by a recurrent and persistent nonspecific inflammatory response. Polydatin (PD), a natural stilbenoid polyphenol with potent properties, exhibits unexpected beneficial effects beyond its well-documented anti-inflammatory and antioxidant activities. In this study, we presented evidence that PD confers protection against dextran sodium sulfate (DSS)-induced ulcerative colitis.

Methods

The protective effect of PD on colitis was examined in cultured caco-2 cells and DSS-induced colitis mouse model. Bulk RNA sequencing and differential gene expression analysis were used to investigate the protective mechanism of PD on DSS-induced colitis. Ferroptosis was determined by MDA levels, SOD levels, mitochondrial iron accumulation and ROS production. Ferroptosis-related proteins Slc7a11, Nrf2 and Gpx4 levels were measured by western blot, immunohistochemical and immunofluorescence staining.

Results

PD mitigated the DSS-induced increases in pro-inflammatory cytokines (IL-6, TNF-α, and IL-1β), alleviated colon length shortening, reduced morphological damage to the intestinal mucosa, and preserved tight junction proteins (TJ) occludin and Zonula occludens-1 (ZO-1) in both caco-2 cells and murine models of colitis. Mechanistically, PD reversed the reduction of Nrf2, Slc7a11 and Gpx4, the degree of nuclear translocation of Nrf2 induced by DSS in vitro and in vivo significantly. Moreover, the protective effect of PD is attenuated by erastin and resembled that of Fer-1 in caco-2 cells model.

Discussion

Our study suggested that PD protects against DSS-induced ulcerative colitis via Nrf2/Slc7a11/Gpx4-dependent inhibition of ferroptosis signalling activation. Further investigation into the precise mechanisms underlying this phenomenon is warranted. The findings presented herein indicated that PD may serve as a potential therapeutic agent for patients with UC.

The Antioxidant Ergothioneine Alleviates Cisplatin-Induced Hearing Loss Through the Nrf2 Pathway

Aims: Cisplatin (CDDP) is a commonly used chemotherapeutic agent for treating head and neck tumors. However, there is high incidence of ototoxicity in patients treated with CDDP, which may be caused by the excessive reactive oxygen species (ROS) generation in the inner ear. Many studies have demonstrated the strong antioxidant effects of ergothioneine (EGT). Therefore, we assumed that EGT could also attenuate cisplatin-induced hearing loss (CIHL) as well. However, the protective effect and mechanism of EGT on CIHL have not been elucidated as so far. In this study, we investigated whether EGT could treat CIHL and the mechanism. Results: In our study, we confirmed the protective effect of EGT on preventing CDDP-induced toxicity both in vitro and in vivo. The auditory brainstem response threshold shift in the EGT + CDDP treatment mice was 30 dB less than that in the CDDP treatment mice. EGT suppressed production of ROS and proapoptotic proteins both in tissue and cells. By silencing nuclear factor erythroid 2-related factor 2 (Nrf2), we confirmed that EGT protected against CIHL via the Nrf2 pathway. We also found that SLC22A4 (OCTN1), an important molecule involved in transporting EGT, was expressed in the cochlea. Innovation: Our results revealed the role of EGT in the prevention of CIHL by activating Nrf2/HO-1/NQO-1 pathway, and broadened a new perspective therapeutic target of EGT. Conclusion: EGT decreased ROS production and promoted the expression of antioxidative enzymes to maintain redox homeostasis in sensory hair cells. Overall, our results indicated that EGT may serve as a novel treatment drug to attenuate CIHL. Antioxid. Redox Signal. 42, 97-114.

Protective Effect of Aloe-emodin on Cognitive Function in Copper-loaded Rats Based on The Inhibition of Hippocampal Neuron Ferroptosis

BACKGROUND

Aloe-emodin (AE), a monomer derived from traditional Chinese medicine, has demonstrated remarkable efficacy in the clinical management of cognitive disorders. Ferroptosis (FPT), a specialized form of programmed cell death, plays a critical role in the pathological progression of various cognitive diseases.

METHODS

This study explored the therapeutic potential of AE in a rat model of Wilson's disease cognitive impairments (WDCI) and examined whether these effects are mediated through the silencing information regulator 1 (SIRT1)-regulated FPT signaling pathway. Employing techniques, such as the Morris water maze (MWM), Hematoxylin & eosin (H&E) staining, Transmission electron microscopy (TEM), Immunofluorescence (IF), assessments of oxidative stress markers, and measurements of FPT-related protein levels, we evaluated the extent of SIRT1-mediated FPT and the therapeutic efficacy of AE.

RESULTS

The findings from the WD copper-loaded rat model experiments revealed that MWM, H&E, TEM, and IF outcomes indicated AE's potential to promote the restoration of learning and memory functions, ameliorate hippocampal neuronal morphological damage, and preserve cell membrane integrity. Results from western blot (WB) and ELISA analyses demonstrated that AE markedly upregulated the expression of SIRT1, nuclear factor erythroid-2-related factor 2 (Nrf2), solute carrier family 7 member 11 (SCL7A11), and glutathione peroxidase 4 (GPX4) proteins while simultaneously reversing the expression of oxidative stress markers such as malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD), and reactive oxygen species (ROS). Consequently, we posit that AE may attenuate WD copper-loaded rat model hippocampal neuronal FPT by activating the SIRT1-mediated signaling pathway.

CONCLUSION

These findings suggested that AE mitigates WD copper-loaded rat model hippocampal neuronal damage through the activation of SIRT1-mediated FPT, thereby presenting a valuable candidate Chinese herbal monomer for the clinical treatment of WDCI.

Adipose tissue macrophages-derived exosomal MiR-500a-5p under high glucose promotes adipocytes inflammation by suppressing Nrf2 expression

BACKGROUND

Type 2 diabetes (T2DM) is a chronic metabolic disorder characterized by insulin resistance and chronic inflammation. Adipose tissue macrophages (ATMs), central players in mediating pro-inflammatory responses within adipose tissue, have been shown to influence insulin sensitivity through exosome secretion. While the role of macrophages-derived exosomal miRNA has been studied in various diseases, their pathogenic roles in T2DM, particularly ATMs-derived exosomal miRNA in adipose tissue inflammation, remain underexplored.

OBJECTIVES

This study focuses specifically on T2DM, investigating the role of ATM-derived exosomal miRNAs in adipose tissue inflammation, a critical factor in the pathogenesis of T2DM.

METHODS

ATM were isolated from visceral adipose tissues in patients with or without diabetes. Differentially expressed miRNAs in ATM-derived exosomes were predicted by high-throughput RNA sequencing. The RAW264.7 macrophages and 3T3-L1 preadipocytes was selected as a model system. Quantitative RT-PCR was used to assess miR-500a-5p expression. The direct binding of miR-500a-5p to Nrf2 mRNA 3' UTR was verified by dual luciferase assay.

RESULTS

MiR-500a-5p was also enriched in the exosomes of high-glucose-treated macrophages. Furthermore, these exosomes induced high expression of miR-500a-5p and activation of the NLRP3 inflammasome in adipocytes when co-cultured with them. Additionally, the reduction of miR-500a-5p expression in macrophages by using a miR-500a-5p inhibitor ameliorated the pro-inflammatory properties of the exosomes, and co-culturing these exosomes with adipocytes resulted in decreased expression of NLRP3 inflammasome-associated proteins in adipocytes. In contrast, induction of miR-500a-5p expression led to the opposite results. Moreover, the dual-luciferase assay confirmed that miR-500a-5p directly targeted the 3' UTR of Nrf2 mRNA. Unlike miR-500a-5p, Nrf2 exhibited an anti-inflammatory response.

CONCLUSION

The results indicate that ATM-derived exosomal miR-500a-5p promotes NLRP3 inflammasome activation and adipose tissue inflammation through down-regulation of Nrf2 in adipocytes.

Kelch-like ECH-associated Protein 1/Nuclear Factor Erythroid 2-related Factor 2 Pathway and Its Interplay with Oncogenes in Lung Tumorigenesis

Nuclear factor erythroid 2-related factor 2 (NRF2), a transcription factor regulating cellular redox homeostasis, exhibits a complex role in cancer biology. Genetic mutations in the Kelch-like ECH-associated protein 1 (KEAP1)/NRF2 system, which lead to NRF2 hyperactivation, are found in 20% to 30% of lung cancer cases. This review explores the intricate interplay between NRF2 and key oncogenic pathways in lung cancer, focusing on the interaction of KEAP1/NRF2 system with Kirsten rat sarcoma virus (KRAS), tumor protein P53 (TP53), epidermal growth factor receptor (EGFR), and phosphatidylinositol 3-kinases (PI3K)/AKT signaling. While NRF2 activation alone is insufficient to initiate tumorigenesis, it can significantly impact tumor initiation and progression when combined with oncogenic drivers such as KRAS. The review highlights the context-dependent effects of NRF2, from its protective role against chemical carcinogen-induced tumor initiation to its potential promotion of tumor growth in established cancers. These findings suggest the need for nuanced, stage-specific approaches to targeting the NRF2 pathway in cancer therapy.

Naoqing formula alleviates acute ischaemic stroke-induced ferroptosis via activating Nrf2/xCT/GPX4 pathway

Backgrounds

Ferroptosis is a form of regulated cell death. The accumulation of iron in the brain is linked to trigger ferroptosis after an ischaemic stroke (IS). Naoqing formula (NQ) is a traditional Chinese medicine metabolites with the clinical function of activating blood circulation, which is applied to treat IS clinically in China.

Methods

Mice and SH-SY5Y cells were utilized to investigate the protective effects and the underlying mechanism of NQ against middle cerebral artery occlusion (MCAO) induced acute ischaemic stroke (AIS) and neuronal cellular ferroptosis caused by ferroptosis inducer Erastin in vitro and in vivo. Utilizing molecular biological techniques, transcriptomics, and proteomics analyses, the role of NQ in Nrf2 regulation and ferroptosis was evaluated through the pharmacologic inhibition of Nrf2.

Results

NQ attenuated AIS-induced neuronal damage and cerebral infarction by increasing cortical blood flow (CBF). Transcriptomics and proteomics analyses revealed that NQ might regulate lipid and iron metabolism through Nrf2 pathway. Additionally, NQ can protect AIS from ferroptosis by reducing oxidative stress and iron overload. Meanwhile, Nrf2, solute carrier family 7 member 11 (SLC7A11; also known as xCT) and glutathione peroxidase 4 (GPX4) were upregulated in NQ-treated AIS mice. Consistent with the results in vivo, NQ led to ferroptosis resistance upon exposure to a ferroptosis-inducing compound through activation of Nrf2/xCT/GPX4 pathway in vitro. Notably, in vivo inhibition of Nrf2 expression by ML385 aggravated the ferroptotic events and weakened the neuroprotective effect of NQ as well as subsequently reduced the expression of xCT and GPX4.

Conclusion

This study demonstrated that NQ protected against AIS via suppression of ferroptosis and oxidative stress, which were largely dependent on the upregulation of Nrf2 pathway.

Renal microRNA-144-3p is associated with transforming growth factor-β1-induced oxidative stress and fibrosis by suppressing the NRF2 pathway in hypertensive diabetic kidney disease

Chronic kidney disease (CKD) is a global health problem characterized by progressive renal fibrosis and excessive extracellular matrix deposition. Oxidative stress and epigenetic regulation, particularly through microRNAs (miRNAs), play crucial roles in the pathogenesis of CKD. In this study, we investigated the role of urinary miR-144-3p, which is upregulated in rats with CKD induced by diabetes and hypertension, in renal fibrosis progression, particularly its regulation of the nuclear factor erythroid-2-related factor 2 (NRF2) pathway. Our findings revealed elevated miR-144-3p levels and reduced NRF2 and target gene levels in kidney tissues of streptozotocin-treated spontaneously hypertensive rats. In vitro experiments demonstrated that miR-144-3p directly binds to the 3'-untranslated region of nrf2, suppressing the NRF2 pathway in renal tubular epithelial cells. Additionally, the profibrogenic factor transforming growth factor (TGF)-β1 increased miR-144-3p expression. TGF-β1-induced NRF2 suppression and reactive oxygen species elevation were found to be mediated through miR-144-3p upregulation. In vivo, cilostazol, an antiplatelet drug with an NRF2-activating effect, ameliorated renal injury in diabetic hypertensive rats by decreasing TGF-β1 and miR-144-3p levels while increasing NRF2 and its target gene levels in the kidneys. These findings highlight the potential therapeutic value of targeting the miR-144-3p/NRF2 pathway to attenuate CKD progression in hypertensive diabetic conditions.

Androgen Receptor Mediates Dopamine Agonist Resistance by Regulating Intracellular Reactive Oxygen Species in Prolactin-Secreting Pituitary Adenoma

Aims: Dopamine agonists (DAs) are the first-line treatment for patients with prolactin-secreting pituitary adenoma (PRL adenoma). However, a subset of individuals exhibits poor responses, known as DA resistance. Previous studies have reported that DA resistance is more prevalent in male patients. This study aims to investigate the relationship between androgen receptor (AR) expression and DA resistance, as well as to explore underlying mechanisms of AR-mediated DA resistance. Results: Our results demonstrated that patients with higher AR expression exhibit greater resistance to DA in our cohort of DA-resistant PRL adenoma. Furthermore, AR was found to be involved in cell proliferation, PRL secretion, and resistance to bromocriptine (BRC) both in vitro and in vivo. Mechanistically, we demonstrated that intracellular reactive oxygen species (ROS) function as upstream mediators of apoptosis and ferroptosis following BRC treatment. As a ligand-dependent transcription factor, AR could translocate to the nucleus and transcriptionally promote NFE2-like bZIP transcription factor 2 (NRF2) expression, which regulates intracellular ROS levels, thereby enhancing cell viability and conferring DA resistance to pituitary adenoma (PA) cells. Finally, AR targeting agents were used to inhibit AR signaling, downregulate NRF2 transcription, and sensitize PA cells to BRC treatment. Conclusion and Innovation: We demonstrated that AR plays a crucial role in mediating DA resistance in PRL adenoma. Mechanistically, AR promotes cell proliferation and PRL secretion and confers drug resistance by transcriptionally regulating NRF2 expression to maintain redox homeostasis in PA cells. Finally, combining AR targeting agents with BRC shows promise as a therapeutic strategy for treating PRL adenomas. Antioxid. Redox Signal. 00, 000-000.

NRF2 in age-related musculoskeletal diseases: Role and treatment prospects

The NRF2 pathway is a metabolic- and redox-sensitive signaling axis in which the transcription factor controls the expression of a multitude of genes that enable cells to survive environmental stressors, such as oxidative stress, mainly by inducing the expression of cytoprotective genes. Basal NRF2 levels are maintained under normal physiological conditions, but when exposed to oxidative stress, cells activate the NRF2 pathway, which is crucial for supporting cell survival. Recently, the NRF2 pathway has been found to have novel functions in metabolic regulation and interplay with other signaling pathways, offering novel insights into the treatment of various diseases. Numerous studies have shown that targeting its pathway can effectively investigate the development and progression of age-related musculoskeletal diseases, such as sarcopenia, osteoporosis, osteoarthritis, and intervertebral disc degeneration. Appropriate regulation of the NRF2 pathway flux holds promise as a means to improve musculoskeletal function, thereby providing a new avenue for drug treatment of age-related musculoskeletal diseases in clinical settings. The review summarized an overview of the relationship between NRF2 and cellular processes such as oxidative stress, apoptosis, inflammation, mitochondrial dysfunction, ferroptosis, and autophagy, and explores the potential of targeted NRF2 regulation in the treatment of age-related musculoskeletal diseases.

Role of oxidative stress in mitochondrial dysfunction and their implications in intervertebral disc degeneration: Mechanisms and therapeutic strategies

Background

Intervertebral disc degeneration (IVDD) is widely recognized as one of the leading causes of low back pain. Intervertebral disc cells are the main components of the intervertebral disc (IVD), and their functions include synthesizing and secreting collagen and proteoglycans to maintain the structural and functional stability of the IVD. In addition, IVD cells are involved in several physiological processes. They help maintain nutrient metabolism balance in the IVD. They also have antioxidant and anti-inflammatory effects. Because of these roles, IVD cells are crucial in IVDD. When IVD cells are subjected to oxidative stress, mitochondria may become damaged, affecting normal cell function and accelerating degenerative changes. Mitochondria are the energy source of the cell and regulate important intracellular processes. As a key site for redox reactions, excessive oxidative stress and reactive oxygen species can damage mitochondria, leading to inflammation, DNA damage, and apoptosis, thus accelerating disc degeneration.

Aim of review

Describes the core knowledge of IVDD and oxidative stress. Comprehensively examines the complex relationship and potential mechanistic pathways between oxidative stress, mitochondrial dysfunction and IVDD. Highlights potential therapeutic targets and frontier therapeutic concepts. Draws researchers' attention and discussion on the future research of all three.

Key scientific concepts of review

Origin, development and consequences of IVDD, molecular mechanisms of oxidative stress acting on mitochondria, mechanisms of oxidative stress damage to IVD cells, therapeutic potential of targeting mitochondria to alleviate oxidative stress in IVDD.

The translational potential of this article

Targeted therapeutic strategies for oxidative stress and mitochondrial dysfunction are particularly critical in the treatment of IVDD. Using antioxidants and specific mitochondrial therapeutic agents can help reduce symptoms and pain. This approach is expected to significantly improve the quality of life for patients. Individualized therapeutic approaches, on the other hand, are based on an in-depth assessment of the patient's degree of oxidative stress and mitochondrial functional status to develop a targeted treatment plan for more precise and effective IVDD management. Additionally, we suggest preventive measures like customized lifestyle changes and medications. These are based on understanding how IVDD develops. The aim is to slow down the disease and reduce the chances of it coming back. Actively promoting clinical trials and evaluating the safety and efficacy of new therapies helps translate cutting-edge treatment concepts into clinical practice. These measures not only improve patient outcomes and quality of life but also reduce the consumption of healthcare resources and the socio-economic burden, thus having a positive impact on the advancement of the IVDD treatment field.

Reactive oxygen species promote endurance exercise-induced adaptations in skeletal muscles

The discovery that contracting skeletal muscle generates reactive oxygen species (ROS) was first reported over 40 years ago. The prevailing view in the 1980s was that exercise-induced ROS production promotes oxidation of proteins and lipids resulting in muscle damage. However, a paradigm shift occurred in the 1990s as growing research revealed that ROS are signaling molecules, capable of activating transcriptional activators/coactivators and promoting exercise-induced muscle adaptation. Growing evidence supports the notion that reduction-oxidation (redox) signaling pathways play an important role in the muscle remodeling that occurs in response to endurance exercise training. This review examines the specific role that redox signaling plays in this endurance exercise-induced skeletal muscle adaptation. We begin with a discussion of the primary sites of ROS production in contracting muscle fibers followed by a summary of the antioxidant enzymes involved in the regulation of ROS levels in the cell. We then discuss which redox-sensitive signaling pathways promote endurance exercise-induced muscle adaptation and debate the strength of the evidence supporting the notion that redox signaling plays an essential role in muscle adaptation to endurance exercise training. In hopes of stimulating future research, we highlight several important unanswered questions in this field.

The Complex Roles of Redox and Antioxidant Biology in Cancer

Redox reactions control fundamental biochemical processes, including energy production, metabolism, respiration, detoxification, and signal transduction. Cancer cells, due to their generally active metabolism for sustained proliferation, produce high levels of reactive oxygen species (ROS) compared to normal cells and are equipped with antioxidant defense systems to counteract the detrimental effects of ROS to maintain redox homeostasis. The KEAP1-NRF2 system plays a major role in sensing and regulating endogenous antioxidant defenses in both normal and cancer cells, creating a bivalent contribution of NRF2 to cancer prevention and therapy. Cancer cells hijack the NRF2-dependent antioxidant program and exploit a very unique metabolism as a trade-off for enhanced antioxidant capacity. This work provides an overview of redox metabolism in cancer cells, highlighting the role of the KEAP1-NRF2 system, selenoproteins, sulfur metabolism, heme/iron metabolism, and antioxidants. Finally, we describe therapeutic approaches that can be leveraged to target redox metabolism in cancer.

Pharmacological USP2 targeting suppresses ovarian cancer growth by potentiating apoptosis and ferroptosis

Ovarian cancer is a frequently observed type of gynaecologic malignancy generally associated with poor prognosis around the world. Ubiquitin-specific proteases (USPs) form the largest subfamily of deubiquitylating enzymes and have emerged as potential therapeutic targets against human cancers. Through a systematic analysis of the prognostic significance of USP expression, USP2 was found to be inversely correlated with patient survival in ovarian cancer. Accordingly, we investigated the effects of pharmacological inhibition of USP2 on ovarian cancer by exploiting its small molecule inhibitor ML364. Our findings show that ML364 effectively hindered ovarian cancer growth and migration using a series of in vitro assays. In addition to apoptosis induction, ML364 also sensitized ovarian cancer cells to ferroptosis. Mechanistically, ML364 treatment resulted in cyclin D1 downregulation, increased poly (ADP-ribose) polymerase (PARP) cleavage, and elevated ROS levels in ovarian cancer cells. Collectively, our findings suggest USP2 as a potential therapeutic target in ovarian cancer, and hence, its pharmacological inhibition warrants further investigation.

Nrf2/Keap1/ARE regulation by plant secondary metabolites: a new horizon in brain tumor management

Brain cancer is regarded as one of the most life-threatening forms of cancer worldwide. Oxidative stress acts to derange normal brain homeostasis, thus is involved in carcinogenesis in brain. The Nrf2/Keap1/ARE pathway is an important signaling cascade responsible for the maintenance of redox homeostasis, and regulation of anti-inflammatory and anticancer activities by multiple downstream pathways. Interestingly, Nrf2 plays a somewhat, contradictory role in cancers, including brain cancer. Nrf2 has traditionally been regarded as a tumor suppressor since its cytoprotective functions are considered to be the principle cellular defense mechanism against exogenous and endogenous insults, such as xenobiotics and oxidative stress. However, hyperactivation of the Nrf2 pathway supports the survival of normal as well as malignant cells, protecting them against oxidative stress, and therapeutic agents. Plants possess a pool of secondary metabolites with potential chemotherapeutic/chemopreventive actions. Modulation of Nrf2/ARE and downstream activities in a Keap1-dependant manner, with the aid of plant-derived secondary metabolites exhibits promise in the management of brain tumors. Current article highlights the effects of Nrf2/Keap1/ARE cascade on brain tumors, and the potential role of secondary metabolites regarding the management of the same.

Discovery and Optimization of a Series of Vinyl Sulfoximine-Based Analogues as Potent Nrf2 Activators for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease of the central nervous system (CNS), which leads to demyelination, axonal loss, and neurodegeneration. Increased oxidative stress and neurodegeneration have been implicated in all stages of MS, making neuroprotective therapeutics a promising strategy for its treatment. We previously have reported vinyl sulfones with antioxidative and anti-inflammatory properties that activate nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor that induces the expression of cytoprotective genes against oxidative stress. In this study, we synthesized vinyl sulfoximine derivatives by modifying the core structure and determined therapeutic potential as Nrf2 activators. Among them, 10v effectively activated Nrf2 (EC50 = 83.5 nM) and exhibited favorable drug-like properties. 10v successfully induced expression of Nrf2-dependent antioxidant enzymes and suppressed lipopolysaccharide (LPS)-induced inflammatory responses in BV-2 microglial cells. We also confirmed that 10v effectively reversed disease progression and attenuated demyelination in an experimental autoimmune encephalitis (EAE) mouse model of MS.

NRF2 and Thioredoxin Reductase 1 as Modulators of Interactions between Zinc and Selenium

BACKGROUND

Selenium and zinc are essential trace elements known to regulate cellular processes including redox homeostasis. During inflammation, circulating selenium and zinc concentrations are reduced in parallel, but underlying mechanisms are unknown. Accordingly, we modulated the zinc and selenium supply of HepG2 cells to study their relationship.

METHODS

HepG2 cells were supplied with selenite in combination with a short- or long-term zinc treatment to investigate intracellular concentrations of selenium and zinc together with biomarkers describing their status. In addition, the activation of the redox-sensitive transcription factor NRF2 was analyzed.

RESULTS

Zinc not only increased the nuclear translocation of NRF2 after 2 to 6 h but also enhanced the intracellular selenium content after 72 h, when the cells were exposed to both trace elements. In parallel, the activity and expression of the selenoprotein thioredoxin reductase 1 (TXNRD1) increased, while the gene expression of other selenoproteins remained unaffected or was even downregulated. The zinc effects on the selenium concentration and TXNRD activity were reduced in cells with stable NRF2 knockdown in comparison to control cells.

CONCLUSIONS

This indicates a functional role of NRF2 in mediating the zinc/selenium crosstalk and provides an explanation for the observed unidirectional behavior of selenium and zinc.

4-Octyl itaconate promotes alveolar ridge preservation following tooth extraction

The search for medications that can effectively reduce alveolar bone loss following tooth extraction is of great interest. This study aimed to observe the roles of 4-octyl itaconate (4-OI) in RANKL-induced osteoclastogenesis of bone marrow macrophages (BMMs) in vitro. Mandibular second molars were extracted to evaluate whether 4-OI could alleviate alveolar bone loss. 4-OI inhibited RANKL-induced osteoclastogenesis and promoted Nrf2 expression in bone marrow macrophages in vitro. Positive Nrf2 expressions were observed in inflammatory cells and osteoclasts in vivo. Treatment with 4-octyl itaconate increased Nrf2 expression, resulting in reduced inflammatory infiltration and osteoclastic activity after tooth extraction. Furthermore, increased expression of OCN and enhanced-alveolar bone healing of extraction socket were observed in the 4-OI group compared to the control group. Our results suggested that 4-OI could serve as a promising pharmacologic candidate for alveolar ridge preservation by alleviating alveolar bone loss following tooth extraction in rats.

NRF2 signaling plays an essential role in cancer progression through the NRF2-GPX2-NOTCH3 axis in head and neck squamous cell carcinoma

The activation of nuclear factor erythroid 2-related factor 2 (NRF2) has been observed in various cancers. Yet its exact contribution to the development of head and neck squamous cell carcinoma (HNSCC) remains undetermined. We previously found that NRF2 signaling is critical for the differentiation of squamous basal progenitor cells, while disruption of NRF2 causes basal cell hyperplasia. In this study, we revealed a correlation between elevated NRF2 activity and poor outcomes in HNSCC patients. We demonstrated that NRF2 facilitates tumor proliferation, migration, and invasion, as evidenced by both in vitro and in vivo studies. Significantly, NRF2 augments the expression of the antioxidant enzyme GPX2, thereby enhancing the proliferative, migratory, and invasive properties of HNSCC cells. Activation of GPX2 is critical for sustaining cancer stem cells (CSCs) by up-regulating NOTCH3, a key driver of cancer progression. These results elucidate that NRF2 regulates HNSCC progression through the NRF2-GPX2-NOTCH3 axis. Our findings proposed that pharmacological targeting of the NRF2-GPX2-NOTCH3 axis could be a potential therapeutic approach against HNSCC.

Supramolecular nanoparticle loaded with bilirubin enhances cartilage protection and alleviates osteoarthritis via modulating oxidative stress and inflammatory responses

Osteoarthritis (OA) is a chronic inflammation that gradually leads to cartilage degradation. Prolonged chondrocyte oxidative stress contributes to the development of diseases, including chondrocyte apoptosis, cartilage matrix degradation, and aggravation of articular cartilage damage. Bilirubin (BR) possesses strong antioxidant properties by scavenging reactive oxygen species (ROS) and potent protection effects against inflammation. However, its insolubility and short half-life limit its clinical use. Therefore, we developed a supramolecular system of ε-polylysine (EPL) conjugated by β-cyclodextrin (β-CD) on the side chain, and bilirubin was loaded via host-guest interactions, which resulted in the self-assemble of this system into bilirubin-loaded polylysine-β-cyclodextrin nanoparticle (PB) with improving solubility while reducing toxicity and prolonging medication action time. To explore PB's potential pharmacological mechanisms on OA, we established in vitro and in vivo OA models. PB exerted ROS-scavenging proficiency and anti-apoptotic effects on rat chondrocytes by activating the Nrf2-HO-1/GPX4 signaling pathway. Additionally, PB reprogrammed the cartilage microenvironment by regulating the NF-κB signaling pathway to maintain chondrocyte function. Animal experiments further confirmed that PB had excellent scavenging ability for ROS and inflammatory factors related to charge adsorption with cartilage as well as long retention ability. Together, this work suggests that PB has superior protective abilities with beneficial effects on OA, indicating its great potential for intervention therapy targeting chondrocytes.

Advanced glycation end products and reactive oxygen species: uncovering the potential role of ferroptosis in diabetic complications

Advanced glycation end products (AGEs) are a diverse range of compounds that are formed when free amino groups of proteins, lipids, and nucleic acids are carbonylated by reactive carbonyl species or glycosylated by reducing sugars. Hyperglycemia in patients with diabetes can cause an overabundance of AGEs. Excess AGEs are generally acknowledged as major contributing factors to the development of diabetic complications because of their ability to break down the extracellular matrix directly and initiate intracellular signaling pathways by binding to the receptor for advanced glycation end products (RAGE). Inflammation and oxidative stress are the two most well-defined pathophysiological states induced by the AGE-RAGE interaction. In addition to oxidative stress, AGEs can also inhibit antioxidative systems and disturb iron homeostasis, all of which may induce ferroptosis. Ferroptosis is a newly identified contributor to diabetic complications. This review outlines the formation of AGEs in individuals with diabetes, explores the oxidative damage resulting from downstream reactions of the AGE-RAGE axis, and proposes a novel connection between AGEs and the ferroptosis pathway. This study introduces the concept of a vicious cycle involving AGEs, oxidative stress, and ferroptosis in the development of diabetic complications.

The involvement of the Stat1/Nrf2 pathway in exacerbating Crizotinib-induced liver injury: implications for ferroptosis

Crizotinib carries an FDA hepatotoxicity warning, yet analysis of the FAERS database suggests that the severity of its hepatotoxicity risks, including progression to hepatitis and liver failure, might be underreported. However, the underlying mechanism remains poorly understood, and effective intervention strategies are lacking. Here, mRNA-sequencing analysis, along with KEGG and GO analyses, revealed that DEGs linked to Crizotinib-induced hepatotoxicity predominantly associate with the ferroptosis pathway which was identified as the principal mechanism behind Crizotinib-induced hepatocyte death. Furthermore, we found that ferroptosis inhibitors, namely Ferrostatin-1 and Deferoxamine mesylate, significantly reduced Crizotinib-induced hepatotoxicity and ferroptosis in both in vivo and in vitro settings. We have also discovered that overexpression of AAV8-mediated Nrf2 could mitigate Crizotinib-induced hepatotoxicity and ferroptosis in vivo by restoring the imbalance in glutathione metabolism, iron homeostasis, and lipid peroxidation. Additionally, both Stat1 deficiency and the Stat1 inhibitor NSC118218 were found to reduce Crizotinib-induced ferroptosis. Mechanistically, Crizotinib induces the phosphorylation of Stat1 at Ser727 but not Tyr701, promoting the transcriptional inhibition of Nrf2 expression after its entry into the nucleus to promote ferroptosis. Meanwhile, we found that MgIG and GA protected against hepatotoxicity to counteract ferroptosis without affecting or compromising the anti-cancer activity of Crizotinib, with a mechanism potentially related to the Stat1/Nrf2 pathway. Overall, our findings identify that the phosphorylation activation of Stat1 Ser727, rather than Tyr701, promotes ferroptosis through transcriptional inhibition of Nrf2, and highlight MgIG and GA as potential therapeutic approaches to enhance the safety of Crizotinib-based cancer therapy.

Nrf2-Mediated Antioxidant Response and Drug Efflux Transporters Upregulation as Possible Mechanisms of Resistance in Photodynamic Therapy of Cancers

Photodynamic therapy (PDT) is a groundbreaking approach involving the induction of cytotoxic reactive oxygen species (ROS) within tumors through visible light activation of photosensitizers (PS) in the presence of molecular oxygen. This innovative therapy has demonstrated success in treating various cancers. While PDT proves highly effective in most solid tumors, there are indications that certain cancers exhibit resistance, and some initially responsive cancers may develop intrinsic or acquired resistance to PDT. The molecular mechanisms underlying this resistance are not fully understood. Recent evidence suggests that, akin to other traditional cancer treatments, the activation of survival pathways, such as the KEAP1/Nrf2 signaling pathway, is emerging as an important mechanism of post-PDT resistance in many cancers. This article explores the dual role of Nrf2, highlighting evidence linking aberrant Nrf2 expression to treatment resistance across a range of cancers. Additionally, it delves into the specific role of Nrf2 in the context of photodynamic therapy for cancers, emphasizing evidence that suggests Nrf2-mediated upregulation of antioxidant responses and induction of drug efflux transporters are potential mechanisms of resistance to PDT in diverse cancer types. Therefore, understanding the specific role(s) of Nrf2 in PDT resistance may pave the way for the development of more effective cancer treatments using PDT.

Cyclopeptide RA-V from Rubia yunnanensis restores activity of Adagrasib against colorectal cancer by reducing the expression of Nrf2

Adagrasib (MRTX849), an approved and promising KRAS G12C inhibitor, has shown the promising results for treating patients with advanced non-small cell lung cancer (NSCLC) or colorectal cancer (CRC) harboring KRAS-activating mutations. However, emergence of the acquired resistance limits its long-term efficacy and clinical application. Further understanding of the mechanism of the acquired resistance is crucial for developing more new effective therapeutic strategies. Herein, we firstly found a new connection between the acquired resistance to MRTX849 and nuclear factor erythroid 2-related factor 2 (Nrf2). The expression levels of Nrf2 and GLS1 proteins were substantially elevated in different CRC cell lines with the acquired resistance to MRTX849 in comparison with their corresponding parental cell lines. Next, we discovered that RA-V, one of natural cyclopeptides isolated from the roots of Rubia yunnanensis, could restore the response of resistant CRC cells to MRTX849. The results of molecular mechanisms showed that RA-V suppressed Nrf2 protein through the ubiquitin-proteasome-dependent degradation, leading to the induction of oxidative and ER stress, and DNA damage in CRC cell lines. Consequently, RA-V reverses the resistance to MRTX849 by inhibiting the Nrf2/GLS1 axis, which shows the potential for further developing into one of novel adjuvant therapies of MRTX849.

The roles of dietary polyphenols at crosstalk between type 2 diabetes and Alzheimer's disease in ameliorating oxidative stress and mitochondrial dysfunction via PI3K/Akt signaling pathways

Alzheimer's disease (AD) is a fatal neurodegenerative disease in which senile plaques and neurofibrillary tangles are crucially involved in its physiological and pathophysiological processes. Growing animal and clinical studies have suggested that AD is also comorbid with some metabolic diseases, including type 2 diabetes mellitus (T2DM), and therefore, it is often considered brain diabetes. AD and T2DM share multiple molecular and biochemical mechanisms, including impaired insulin signaling, oxidative stress, gut microbiota dysbiosis, and mitochondrial dysfunction. In this review article, we mainly introduce oxidative stress and mitochondrial dysfunction and explain their role and the underlying molecular mechanism in T2DM and AD pathogenesis; then, according to the current literature, we comprehensively evaluate the possibility of regulating oxidative homeostasis and mitochondrial function as therapeutics against AD. Furthermore, considering dietary polyphenols' antioxidative and antidiabetic properties, the strategies for applying them as potential therapeutical interventions in patients with AD symptoms are assessed.

Novel methyltransferase G9a inhibitor induces ferroptosis in multiple myeloma through Nrf2/HO-1 pathway

Multiple myeloma (MM) is a common malignant hematologic neoplasm, and the involvement of epigenetic modifications in its development and drug resistance has received widespread attention. Ferroptosis, a new ferroptosis-dependent programmed death mode, is closely associated with the development of MM. The novel methyltransferase inhibitor DCG066 has higher cell activity, but its mechanism of action in MM has not been clarified. Here, we found that DCG066 (5µM) inhibited the proliferation and induced ferroptosis in MM cells; the intracellular levels of ROS, iron, and MDA were significantly elevated, and the level of GSH was reduced after the treatment of DCG066; The protein expression levels of SLC7A11, GPX4, Nrf2 and HO-1 were significantly reduced, and these phenomena could be reversed by ferroptosis inhibitor Ferrostatin-1 (Fer-1) and Nrf2 activator Tert-butyl hydroquinone (TBHQ). Meanwhile, the protein expression levels of Keap1 was increased, and heat shock proteins (HSP70, HSP90 and HSPB1) were reduced after DCG066 treatment. In conclusion, this study confirmed that DCG066 inhibits MM proliferation and induces ferroptosis via the Nrf2/HO-1 pathway.

The molecular effects underlying the pharmacological activities of daphnetin

As an increasingly well-known derivative of coumarin, daphnetin (7,8-dithydroxycoumarin) has demonstrated various pharmacological activities, including anti-inflammation, anti-cancer, anti-autoimmune diseases, antibacterial, organ protection, and neuroprotection properties. Various studies have been conducted to explore the action mechanisms and synthetic methods of daphnetin, given its therapeutic potential in clinical. Despite these initial insights, the precise mechanisms underlying the pharmacological activities of daphnetin remain largely unknown. In order to address this knowledge gap, we explore the molecular effects from the perspectives of signaling pathways, NOD-like receptor protein 3 (NLRP3) inflammasome and inflammatory factors; and try to find out how these mechanisms can be utilized to inform new combined therapeutic strategies.

Naringenin, a flavanone constituent from Sea buckthorn pulp extract, prevents ultraviolet (UV)-B radiation-induced skin damage via alleviation of impaired mitochondrial dynamics mediated inflammation in human dermal fibroblasts and Balb/c mice models

Ultraviolet-B (UV-B) irradiation has been reported to cause oxidative stress and inflammation-mediated skin photo-damage. Furthermore, mitochondrial dynamics have been implicated to play a critical role in these processes. For the first time, we describe in this study how UVB-induced aberrant mitochondrial dynamics and inflammation interact in primary human dermal fibroblasts (HDFs). Our findings demonstrated that UV-B irradiation induced -impairment in mitochondrial dynamics by increasing mitochondrial fragmentation in HDFs. Imbalanced mitochondrial dynamics lead to the activation of NFкB and pro-inflammatory cytokines. The current study further aimed to investigate the protective effect of Naringenin (a naturally occurring flavonoid isolated from Sea buckthorn fruit pulp) against UV-B-induced mitochondrial fragmentation and inflammation in HDFs and Balb/c mice. Although Naringenin has been shown to have anti-inflammatory and antioxidant potential, its effects and mechanisms of action on UVB-induced inflammation remained unclear. We observed that Naringenin restored the UV-B-induced imbalance in mitochondrial fission and fusion in HDFs. It also inhibited the phosphorylation of NFкB and reduced the generation of pro-inflammatory cytokines. Naringenin also alleviated UV-B-induced oxidative stress by scavenging the reactive oxygen species and up-regulating the cellular antioxidant enzymes (Catalase and Nrf2). Topical application of Naringenin to the dorsal skin of Balb/c mice exposed to UV-B radiation prevented mitochondrial fragmentation and progression of inflammatory responses. Naringenin treatment prevented neutrophil infiltration and epidermal thickening in mice's skin. These findings provide an understanding for further research into impaired mitochondrial dynamics as a therapeutic target for UV-B-induced inflammation. Our findings imply that Naringenin could be developed as a therapeutic remedy against UVB-induced inflammation.

Bivalent inhibitors of the BTB E3 ligase KEAP1 enable instant NRF2 activation to suppress acute inflammatory response

Most BTB-containing E3 ligases homodimerize to recognize a single substrate by engaging multiple degrons, represented by E3 ligase KEAP1 dimer and its substrate NRF2. Inactivating KEAP1 to hinder ubiquitination-dependent NRF2 degradation activates NRF2. While various KEAP1 inhibitors have been reported, all reported inhibitors bind to KEAP1 in a monovalent fashion and activate NRF2 in a lagging manner. Herein, we report a unique bivalent KEAP1 inhibitor, biKEAP1 (3), that engages cellular KEAP1 dimer to directly release sequestered NRF2 protein, leading to an instant NRF2 activation. 3 promotes the nuclear translocation of NRF2, directly suppressing proinflammatory cytokine transcription. Data from in vivo experiments showed that 3, with unprecedented potency, reduced acute inflammatory burden in several acute inflammation models in a timely manner. Our findings demonstrate that the bivalent KEAP1 inhibitor can directly enable sequestered substrate NRF2 to suppress inflammatory transcription response and dampen various acute inflammation injuries.

Targeting kelch-like (KLHL) proteins: achievements, challenges and perspectives

Kelch-like proteins (KLHLs) are a large family of BTB-containing proteins. KLHLs function as the substrate adaptor of Cullin 3-RING ligases (CRL3) to recognize substrates. KLHLs play pivotal roles in regulating various physiological and pathological processes by modulating the ubiquitination of their respective substrates. Mounting evidence indicates that mutations or abnormal expression of KLHLs are associated with various human diseases. Targeting KLHLs is a viable strategy for deciphering the KLHLs-related pathways and devising therapies for associated diseases. Here, we comprehensively review the known KLHLs inhibitors to date and the brilliant ideas underlying their development.

Amino acid deprivation induces TXNIP expression by NRF2 downregulation

Thioredoxin-interacting protein (TXNIP) is sensitive to oxidative stress and is involved in the pathogenesis of various metabolic, cardiovascular, and neurodegenerative disorders. Therefore, several studies have suggested that TXNIP is a promising therapeutic target for several diseases, particularly cancer and diabetes. However, the regulation of TXNIP expression under amino acid (AA)-restricted conditions is not well understood. In the present study, we demonstrated that TXNIP expression was promoted by the deprivation of AAs, especially arginine, glutamine, lysine, and methionine, in non-small cell lung cancer (NSCLC) cells. Interestingly, we determined that increased TXNIP expression induced by AA deprivation was associated with nuclear factor erythroid 2-related factor 2 (NRF2) downregulation, but not with activating transcription factor 4 (ATF4) activation. Furthermore, N-acetyl-l-cysteine (NAC), a scavenger of reactive oxygen species (ROS), suppressed TXNIP expression in NSCLC cells deprived of AA. Collectively, the induction of TXNIP expression by AA deprivation was mediated by ROS production, potentially through NRF2 downregulation. Our findings suggest that TXNIP expression may be associated with the redox homeostasis of AA metabolism and provide a possible rationale for a therapeutic strategy to treat cancer with AA restriction.

Hypoxia, oxidative stress, and the interplay of HIFs and NRF2 signaling in cancer

Oxygen is crucial for life and acts as the final electron acceptor in mitochondrial energy production. Cells adapt to varying oxygen levels through intricate response systems. Hypoxia-inducible factors (HIFs), including HIF-1α and HIF-2α, orchestrate the cellular hypoxic response, activating genes to increase the oxygen supply and reduce expenditure. Under conditions of excess oxygen and resulting oxidative stress, nuclear factor erythroid 2-related factor 2 (NRF2) activates hundreds of genes for oxidant removal and adaptive cell survival. Hypoxia and oxidative stress are core hallmarks of solid tumors and activated HIFs and NRF2 play pivotal roles in tumor growth and progression. The complex interplay between hypoxia and oxidative stress within the tumor microenvironment adds another layer of intricacy to the HIF and NRF2 signaling systems. This review aimed to elucidate the dynamic changes and functions of the HIF and NRF2 signaling pathways in response to conditions of hypoxia and oxidative stress, emphasizing their implications within the tumor milieu. Additionally, this review explored the elaborate interplay between HIFs and NRF2, providing insights into the significance of these interactions for the development of novel cancer treatment strategies.

Reduced Zn2+ promotes retinal ganglion cells survival and optic nerve regeneration after injury through inhibiting autophagy mediated by ROS/Nrf2

The molecular mechanism of how reduced mobile zinc (Zn2+) affected retinal ganglion cell (RGC) survival and optic nerve regeneration after optic nerve crush (ONC) injury remains unclear. Here, we used conditionally knocked out ZnT-3 in the amacrine cells (ACs) of mice (CKO) in order to explore the role of reactive oxygen species (ROS), nuclear factor erythroid 2-related factor 2 (NFE2L2, Nrf2) and autophagy in the protection of RGCs and axon regeneration after ONC injury. We found that reduced Zn2+ can promote RGC survival and axonal regeneration by decreasing ROS, activating Nrf2, and inhibiting autophagy. Additionally, autophagy after ONC is regulated by ROS and Nrf2. Visual function in mice after ONC injury was partially recovered through the reduction of Zn2+, achieved by using a Zn2+ specific chelator N,N,N',N'-tetrakis-(2-Pyridylmethyl) ethylenediamine (TPEN) or through CKO mice. Overall, our data reveal the crosstalk between Zn2+, ROS, Nrf2 and autophagy following ONC injury. This study verified that TPEN or knocking out ZnT-3 in ACs is a promising therapeutic option for the treatment of optic nerve damage and elucidated the postsynaptic molecular mechanism of Zn2+-triggered damage to RGCs after ONC injury.

ZMYND8 protects breast cancer stem cells against oxidative stress and ferroptosis through activation of NRF2

Breast cancer stem cells (BCSCs) mitigate oxidative stress to maintain their viability and plasticity. However, the regulatory mechanism of oxidative stress in BCSCs remains unclear. We recently found that the histone reader ZMYND8 was upregulated in BCSCs. Here, we showed that ZMYND8 reduced ROS and iron to inhibit ferroptosis in aldehyde dehydrogenase-high (ALDHhi) BCSCs, leading to BCSC expansion and tumor initiation in mice. The underlying mechanism involved a two-fold posttranslational regulation of nuclear factor erythroid 2-related factor 2 (NRF2). ZMYND8 increased stability of NRF2 protein through KEAP1 silencing. On the other hand, ZMYND8 interacted with and recruited NRF2 to the promoters of antioxidant genes to enhance gene transcription in mammospheres. NRF2 phenocopied ZMYND8 to enhance BCSC stemness and tumor initiation by inhibiting ROS and ferroptosis. Loss of NRF2 counteracted ZMYND8's effects on antioxidant genes and ROS in mammospheres. Interestingly, ZMYND8 expression was directly controlled by NRF2 in mammospheres. Collectively, these findings uncover a positive feedback loop that amplifies the antioxidant defense mechanism sustaining BCSC survival and stemness.

Formononetin ameliorates cisplatin-induced hair cell death via activation of the PI3K/AKT-Nrf2 signaling pathway

Cisplatin (CDDP) stands as a highly effective chemotherapeutic agent; however, its ototoxicity remains a perplexing challenge in the field. Formononetin (FMNT), a potent flavonoid isolated from Astragalus membranaceus, displays a diverse range of promising pharmacological activities, encompassing antioxidant, anti-apoptotic, and anti-inflammatory effects. Nonetheless, the advantageous effects of FMNT on cisplatin-induced cochlear hair cell injury demand further investigation. This study aimed to assess the protective properties of FMNT against cisplatin-induced hair cell damage by conducting in vitro assays on explant-cultured cochlear hair cells. The findings revealed that FMNT exhibited a notable reduction in cisplatin-induced hair cell apoptosis. Also, FMNT effectively mitigated the accumulation of reactive oxygen species and mitochondrial damage in cochlear explants exposed to cisplatin, while also restoring the turnover of the reduced glutathione (GSH)/glutathione disulfide (GSSG) ratio. Furthermore, our study demonstrated that FMNT protects hair cells against CDDP injury through the activation of the PI3K/AKT-Nrf2 signaling pathway. Consequently, formononetin emerges as a potential therapeutic agent for the treatment of cisplatin-induced ototoxicity.

Baicalein Alleviates Arsenic-induced Oxidative Stress through Activation of the Keap1/Nrf2 Signalling Pathway in Normal Human Liver Cells

BACKGROUND

Oxidative stress is a key mechanism underlying arsenicinduced liver injury, the Kelch-like epichlorohydrin-related protein 1 (Keap1)/nuclear factor E2 related factor 2 (Nrf2) pathway is the main regulatory pathway involved in antioxidant protein and phase II detoxification enzyme expression. The aim of the present study was to investigate the role and mechanism of baicalein in the alleviation of arsenic-induced oxidative stress in normal human liver cells.

METHODS

Normal human liver cells (MIHA cells) were treated with NaAsO2 (0, 5, 10, 20 μM) to observe the effect of different doses of NaAsO2 on MIHA cells. In addition, the cells were treated with DMSO (0.1%), NaAsO2 (20 μM), or a combination of NaAsO2 (20 μM) and Baicalein (25, 50 or 100 μM) for 24 h to observe the antagonistic effect of Baicalein on NaAsO2. Cell viability was determined using a Cell Counting Kit- 8 (CCK-8 kit). The intervention doses of baicalein in subsequent experiments were determined to be 25, 50 and 100μM. The intracellular content of reactive oxygen species (ROS) was assessed using a 2',7'-dichlorodihydrofluorescein diacetate (DCFHDA) probe kit. The malonaldehyde (MDA), Cu-Zn superoxide dismutase (Cu-Zn SOD) and glutathione peroxidase (GSH-Px) activities were determined by a test kit. The expression levels of key genes and proteins were determined by real-time fluorescence quantitative polymerase chain reaction (qPCR) and Western blotting.

RESULTS

Baicalein upregulated the protein expression levels of phosphorylated Nrf2 (p-Nrf2) and nuclear Nrf2, inhibited the downregulation of Nrf2 target genes induced by arsenic, and decreased the production of ROS and MDA. These results demonstrate that baicalein promotes Nrf2 nuclear translocation by upregulating p-Nrf2 and inhibiting the downregulation of Nrf2 target genes in arsenic-treated MIHA cells, thereby enhancing the antioxidant capacity of cells and reducing oxidative stress.

CONCLUSION

Baicalein alleviated arsenic-induced oxidative stress through activation of the Keap1/Nrf2 signalling pathway in normal human liver cells.

Grape seed-derived procyanidin inhibits glyphosate-induced hepatocyte ferroptosis via enhancing crosstalk between Nrf2 and FGF12

BACKGROUND

Glyphosate (GLY) exposure induces hepatocyte ferroptosis through overproduction of reactive oxygen species, regarded as an important contributor to liver damage. Grape seed-derived procyanidin (GSDP) has been reported to be an effective antioxidant, but whether and, if any, how GSDP can attenuate GLY-induced liver injury via inhibiting ferroptosis is unclear.

PURPOSE

The current study aimed to investigate the hepato-protective effects and possible mechanisms of GSDP.

METHODS

GLY-induced liver damage mice model was established to explore the hepatoprotective roles of GSPE in vivo. Subsequently, bioinformatics methodology was used to predict the key pathways and factors related to the action targets of GSPE against hepatocyte ferroptosis. Finally, we explored the roles of nuclear factor E2 related factor 2 (Nrf2) and fibroblast growth factor 21 (FGF21) in blunting GLY-induced liver damage via suppressing ferroptosis in vitro.

RESULTS

GSDP exerts hepato-protective effects in vivo and in vitro through reduced oxidative stress and inhibited ferroptosis, which was related to the activation of Nrf2. Bioinformatics analysis showed an interaction between Nrf2 and FGF21. Furthermore, Nrf2 inhibition reduced FGF21 expression in the mRNA and protein levels. Fgf21 knockdown suppressed Nrf2 expression level, but recombinant FGF21 protein increased Nrf2 expression and promoted Nrf2 translocation into nucleus, suggesting a crosstalk between Nrf2 and FGF21. Intriguingly, the decreased levels of Nrf2 and FGF21 compromised the protective roles of GSDP against GLY-induced hepatocyte ferroptosis.

CONCLUSION

These findings suggest that GSDP attenuates GLY-caused hepatocyte ferroptosis via enhancing the interplay between Nrf2 and FGF21. Thus, GSDP may be a promising natural compound to antagonize ferroptosis-related damage.