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Ergothioneine Alleviated the Apoptosis of HK Cells by Regulating Ferroptosis.

INTRODUCTION/OBJECTIVE: Ergothioneine (EGT) is a naturally occurring antioxidant with protective effects on various human cell types. The impact of this substance on HK-2 cells, a human renal proximal tubular epithelial cell line, and the associated molecular mechanisms remain incompletely elucidated. METHODS: The present study aims to elucidate the effects of EGT on apoptosis induced by RAS-selective Lethal Molecule 3 (RSL3) and Erastin in HK-2 cells, as well as the potential mechanisms involved. The renal cortical proximal tubular epithelial HK-2 cells were cultured and exposed to RSL3 and Erastin, with or without EGT treatment. Cell viability and apoptosis were assessed using the Cell Counting Kit-8 (CCK-8) assay, while the detection of ferrous ion content and mitochondrial membrane potential changes was accomplished through the utilisation of flow cytometry and the JC-1 staining method, respectively. Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, proteomic analysis, and western blotting were employed to explore the molecular pathways involved. RESULTS: The data demonstrated that RSL3 and Erastin exhibited a substantial inhibitory effect on HK-2 cell proliferation, concomitant with the accumulation of intracellular ferrous ions and a shift in mitochondrial membrane potential. The EGT treatment effectively mitigated RSL3- and Erastin-induced apoptosis in HK-2 cells. GO and KEGG enrichment analysis demonstrated that EGT suppressed pathways and functions associated with oxidative stress during ferroptosis. Proteomics analysis further demonstrated that EGT modulated various biological processes, molecular functions, and cellular components in HK-2 cells. The protective mechanism of EGT against RSL3- and Erastin-induced HK-2 cells was potentially mediated through regulation of ferroptosis. The results of the western blot analysis demonstrated that EGT modulated the expression levels of Glutathione Peroxidase 4 (GPX4) and Solute Carrier Family 7 member 11 (SLC7A11) in HK-2 cells. CONCLUSION: These data demonstrated that EGT exerts an alleviating effect on the apoptosis of HK-2 cells induced by RSL3 and Erastin by modulating ferroptosis. These findings suggest that EGT has the potential to serve as a therapeutic candidate for the treatment of kidney diseases in the future.

Ergothioneine

KLF5-driven G6PD protects lung squamous cell carcinoma from ferroptosis by sustaining mitochondrial homeostasis and SLC7A11-dependent cystine uptake.

AIMS: Lung squamous cell carcinoma (LUSC) is a highly aggressive malignancy with limited therapeutic options. Ferroptosis has emerged as a promising antitumor strategy. However, the metabolic determinants governing ferroptotic vulnerability in LUSC remain incompletely understood. We investigated glucose-6-phosphate dehydrogenase (G6PD) in this context. MATERIALS AND METHODS: In vitro models using small interfering RNA (siRNA)-mediated G6PD depletion, together with pharmacological studies using 6-aminonicotinamide (6-AN) and LUSC xenograft models, were employed to investigate the underlying mechanisms. KEY FINDINGS: G6PD was markedly upregulated in LUSC, and analysis of the Cancer Genome Atlas lung squamous cell carcinoma (TCGA-LUSC) cohort showed that elevated G6PD expression was associated with advanced clinicopathological features and poorer overall survival. While ferroptosis inducers (erastin and RSL3) did not alter G6PD mRNA, they robustly increased G6PD protein during ferroptotic stress. Genetic or pharmacological inhibition of G6PD significantly sensitized LUSC cells to RSL3-induced ferroptosis, evidenced by enhanced lipid peroxidation, glutathione depletion, and ferrostatin-1-reversible cell death. Mechanistically, G6PD inhibition led to mitochondrial ferrous iron accumulation, elevated reactive oxygen species, impaired respiration, and activation of PINK1/Parkin-dependent mitophagy, which further exacerbated ferroptotic injury. In vivo, combined treatment with 6-aminonicotinamide and RSL3 markedly suppressed LUSC xenograft growth and enhanced biochemical markers of ferroptotic stress. Furthermore, G6PD protects cells by positively regulating the cystine/glutamate antiporter SLC7A11 to maintain redox homeostasis. Upstream, the oncogenic factor Krüppel-like factor 5 (KLF5) directly activates G6PD transcription. SIGNIFICANCE: Our findings identify a KLF5-G6PD-SLC7A11 axis as a critical metabolic safeguard against ferroptosis in LUSC. Targeting G6PD disrupts mitochondrial homeostasis, enhances mitophagy-dependent oxidative stress, and sensitizes tumors to ferroptotic therapy, highlighting a promising therapeutic strategy for LUSC.

Ferroptosis

AGRN activates GPX4 via the Wnt/beta-catenin signaling pathway to suppress ferroptosis in cervical cancer cells.

Cervical cancer remains a leading cause of cancer-related deaths among women worldwide. Targeting ferroptosis, a regulated form of cell death driven by lipid peroxidation, has emerged as a promising therapeutic strategy. This study aimed to elucidate the mechanisms by which cervical cancer cells acquire resistance to ferroptosis. AGRN expression and its prognostic significance were analyzed in cervical cancer using TCGA and GTEx data. In vitro, AGRN levels were measured in HeLa, CaSki, and Ect1/E6E7 cells via qRT-PCR. mRNA and protein expression levels of AGRN, beta-catenin, and ferroptosis-related markers were evaluated by qRT-PCR and western blot (WB). Cell viability, RSL3 sensitivity (IC50), and lipid ROS were assessed via CCK-8 assay and flow cytometry. In a xenograft model, RSL3's effect on tumor growth was examined. Immunohistochemistry (IHC) and molecular analyses (qRT-PCR, WB, and flow cytometry) were performed on tumor tissues to evaluate AGRN, beta-catenin, Ki-67, ferroptosis-related genes, and lipid ROS. It is found through research that, AGRN was significantly upregulated in cervical cancer tissues and cell lines. Its overexpression activated Wnt/beta-catenin signaling, resulting in elevated GPX4 and SLC7A11 levels and reduced CHAC1 and PTGS2 expression levels. These alterations decreased lipid ROS accumulation and enhanced resistance to RSL3-induced ferroptosis, an effect further confirmed in xenograft models. In short, In short, AGRN promotes ferroptosis resistance in cervical cancer by activating the Wnt/beta-catenin signaling pathway and upregulating GPX4 expression. Targeting the AGRN-Wnt/beta-catenin-GPX4 axis may represent a novel therapeutic approach for cervical cancer.

Humans

Glutathione reductase deficiency potentiates the immunogenicity of ferroptosis and cuproptosis via amplified reactive oxygen species accumulation and cGAS-STING pathway activation.

BACKGROUND: Cancer remains a major therapeutic challenge due to drug resistance and metastasis, processes driven by oxidative stress and redox imbalance. Targeting this vulnerability through ferroptosis (iron-dependent lipid peroxidation) and cuproptosis (copper-driven mitochondrial dysfunction), two ROS-mediated cell death pathways, offers a promising therapeutic strategy. However, clinical translation is hindered by incomplete understanding of their redox regulation and limited immunogenicity. METHODS: A genome-wide CRISPR knockout screen was performed to identify key regulators of ferroptosis. Genetic depletion or pharmacological inhibition of candidate genes was evaluated across multiple cancer cell lines for sensitivity to ferroptosis inducer RSL3 and the cuproptosis inducer elesclomol (Es). Antitumor efficacy was assessed in xenograft, orthotopic, metastatic, and syngeneic mouse models, alone or combined with immune checkpoint inhibitors. Mechanistic studies also examined ROS production, mitochondrial stress, mitochondrial DNA release, cGAS-STING activation, and immune responses within the tumor microenvironment. RESULTS: Glutathione reductase (GSR), a central enzyme maintaining reduced glutathione (GSH) homeostasis, was identified as the top suppressor of ferroptosis. GSR knockout or pharmacological inhibition markedly sensitized diverse cancer cell lines to RSL3-induced ferroptosis, while GSR overexpression conferred resistance. Strikingly, GSR depletion also enhanced sensitivity to cuproptosis triggered by the copper ionophore Es. In multiple in vivo tumor models, GSR inhibition synergizes with RSL3 or Es to suppress tumor growth, inhibit lung metastasis, and prolong survival. Mechanistically, GSR deficiency amplified ROS production, induced mitochondrial stress, and triggered the cytosolic mitochondrial DNA release under ferroptotic or cuproptotic stress, activating the cGAS-STING pathway in vitro and in vivo. This increased inflammatory cytokine production, promoted immunogenic cell death, and enhanced the release of damage-associated molecular patterns (DAMPs), including HMGB1. Together, GSR inhibition combined with a ferroptosis or cuproptosis inducer transformed the tumor microenvironment into a highly immune stimulatory state, thereby enhancing the efficacy of immune checkpoint blockade through increased dendritic cell activation and T-cell infiltration and activation. CONCLUSIONS: GSR represents a key molecular node connecting and modulating ferroptosis and cuproptosis through redox regulation. Targeting GSR amplifies ROS-mediated immunogenic cell death, triggers cGAS-STING activation in cancer cells, and enhances the efficacy of cancer immunotherapy, providing a promising redox-based therapeutic strategy.

Ferroptosis