Ferroptosis Suppressor Protein Research Articles

New Treatment Modalities for Colorectal Cancer Through Simultaneous Suppression of FSP1 and GPX4.

Ferroptosis is a nonapoptotic type of cell death that is dependent on iron and involves the accumulation of reactive oxygen species. Ferroptosis suppressor protein 1 (FSP1) and glutathione peroxidase 4 (GPX4) are ferroptosis regulators that inhibit ferroptosis through independent pathways. This study assessed the prognostic value of GPX4 and FSP1 expression in colorectal cancer (CRC). We also examined the effects of FSP1 and GPX4 inhibition on cell survival of CRC cells. This study included 206 surgical specimens from Stage II or III CRC patients. FSP1 and GPX4 expression was analyzed immunohistochemically, and the association of their expression levels with clinical outcome was evaluated. We also examined the effects of FSP1 and GPX4 inhibitors on the cell proliferative capacity of CRC cell lines. Overall survival and recurrence-free survival were reduced in patients with high expression of FSP1 or GPX4, and those with both GPX4 and FSP1 expression showed worse prognosis. Positivity of both FSP1 and GPX4 was an independent poor prognostic factor for CRC patients. In CRC cells, the combination of GPX4 and FSP1 inhibitors led to more effective cell death than either inhibitor alone. High expression of both GPX4 and FSP1 is a significant poor prognostic factor for CRC. Simultaneous inhibition of GPX4 and FSP1 to induce ferroptosis may be a novel therapeutic strategy in CRC.

Cefiderocol has immunoregulative effects in LPS-induced vitro experimental model via inhibiting inflammation and ferroptosis

BackgroundCefiderocol is a new catecholamine-containing siderophore cephalosporin. It, however, remains unclear how cefiderocol modulates the immune response of the host. ObjectivesThis study elucidated whether cefiderocol exerts immunoprotective effects in an in vitro experimental model induced with lipopolysaccharide (LPS). MethodsMouse macrophage RAW 264.7 cells were exposed to LPS (100 ng/mL) or LPS + cefiderocol (40 mg/L) to assess the immunomodulatory effect of cefiderocol in vitro. ELISA was performed on cell culture supernatants to estimate cytokine levels. Ferroptosis level was also quantified by detecting intracellular reactive oxygen species (ROS) and iron levels through flow cytometry analysis. Malondialdehyde (MDA) and glutathione (GSH) levels were estimated by ELISA. We conducted western blotting assay for evaluating key ferroptosis pathway proteins. ResultsCefiderocol alleviated LPS-induced inflammation by reducing IL-6, TNF-α, and IL-1β production levels and enhancing the IL-10 production level. Further analysis to determine the underlying mechanism revealed that cefiderocol inhibited ferroptosis; this was confirmed by reduced ROS, MDA, and Fe2+ ion levels; increased GSH levels; upregulated expression of solute carrier family 7 member 11, glutathione peroxidase 4, nuclear factor erythroid 2-related factor 2, and ferroptosis suppressor protein 1; and downregulated expression of acyl-CoA synthetase long-chain family member 4. ConclusionsCefiderocol may play a key role in reducing inflammation by decreasing inflammatory cytokine release and suppressing ferroptosis.

FSP1 Acts in Parallel with GPX4 to Inhibit Ferroptosis in COPD.

Glutathione peroxidase 4 (GPX4) has recently been reported to play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Ferroptosis suppressor protein-1 (FSP1) is a protein that defends against ferroptosis in parallel with GPX4, but its role in the pathogenesis of COPD remains unexplored, and further research is needed. Normal and COPD lung tissues were obtained from lobectomy and lung transplant specimens, respectively. FSP1-overexpressing mice were established by monthly transfection with AAV9-FSP1 through modified intranasal administration. The expression of FSP1, GPX4, and prostaglandin-endoperoxide synthase 2 (PTGS2) was measured by Western blotting, immunohistochemistry and other methods. The correlation between FSP1 and ferroptosis and the role of FSP1 in COPD were explored by screening the expression of ferroptosis-related genes in a COPD cell model after the inhibition and overexpression of FSP1. We then explored the underlying mechanism of low FSP1 expression in patients with COPD in vitro by methylated RNA immunoprecipitation (MeRIP)-qPCR. We found that cigarette smoke exposure can lead to an increase in lipid peroxide production and ultimately ferroptosis, which is negatively regulated by FSP1 activity. FSP1 overexpression can prevent ferroptosis and alleviate emphysema. Next, we found that decreased FSP1 expression was caused by increased m6A modification of FSP1 mRNA. Moreover, the level of FSP1 decreased in a YTHDF2-dependent manner. These results indicate that METTL3-induced FSP1 mRNA methylation leading to low FSP1 expression is a potential therapeutic target for COPD. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Cancer-associated fibroblast-secreted exosomal miR-454-3p inhibits lipid metabolism and ferroptosis in breast cancer by targeting ACSL4.

Cancer-associated fibroblasts (CAFs) participate in the development of the tumor microenvironment through the secretion of exosomes. Acyl-CoA synthetase long-chain family member 4 (ACSL4) is an essential component of ferroptosis. However, the regulatory mechanism of ACSL4 in breast cancer remains unexplored. The study aimed to determine the influence of exosomal miR-454-3p from CAFs on lipid metabolism and ferroptosis. CAF-derived exosomes (CAF-exo) were isolated from breast cancer tissue of breast cancer patients and characterized using transmission electron microscopy (TEM) and Western blot. Luciferase reporter assay and RNA immunoprecipitation (RIP) were used to demonstrate the relationship between miR-454-3p and ACSL4. Cell viability and ferroptosis-related markers were detected by CCK-8 and Western blot. Malondialdehyde (MDA), glutathione (GSH), and iron levels were detected. Reverse transcription-quantitative PCR (RT-qPCR) and fluorescence in situ hybridization (FISH) were used to assess miR-454-3p expression. miR-454-3p and ACSL4 levels were abnormally expressed in breast cancer tissues. CAF-exo significantly enhanced cell viability and GSH levels and suppressed MDA, and iron levels. CAF-exo upregulated ferroptosis suppressor protein 1 (FSP1) and glutathione peroxidase 4 (GPX4) expression, and reduced ACSL4 levels. miR-454-3p was strongly expressed in CAF-exo, and exosomal miR-454-3p suppressed lipid metabolism and ferroptosis in breast cancer cells. The effects of miR-454-3p inhibitor on lipid metabolism and ferroptosis were eliminated by ACSL4 knockdown. CAF-secreted exosomal miR-454-3p inhibited lipid metabolism and ferroptosis by targeting ACSL4 in breast cancer. This study revealed a novel molecular mechanism that offers a potential therapeutic intervention in breast cancer treatment.

Exosomes-Shuttled lncRNA SNHG7 by Bone Marrow Mesenchymal Stem Cells Alleviates Osteoarthritis Through Targeting miR-485-5p/FSP1 Axis-Mediated Chondrocytes Ferroptosis and Inflammation.

Osteoarthritis (OA), a degenerative joint disorder, is a major reason of disability in adults. Accumulating evidences have proved that bone marrow mesenchymal stem cells (BMSCs)-carried exosomes play a significant therapeutic effect on OA. However, the precise regulatory network remains unknown. OA and normal cartilage samples were acquired from patients, and chondrocytes were exposed to IL-1β to conduct a cellular OA model. Exosomes prepared from BMSCs were identified using nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). Cell viability was determined with CCK-8 assay. Inflammatory injury was assessed by LDH and inflammatory factors (TNF-α and IL-6) using corresponding ELISA kits, respectively. Ferroptosis was evaluated by GSH, MDA and iron levels using corresponding kits, and ROS level with DCFH-DA. The expressions of genes/proteins were determined with RT-qPCR/western bolt. RNA immunoprecipitation and luciferase activity assay were conducted for testing the interactions of small nucleolar RNA host gene 7 (SNHG7)/ferroptosis suppressor protein 1 (FSP1) and miR-485-5p. The expressions of SNHG7 and FSP1 were both reduced in IL-1β-induced chondrocytes and OA cartilage tissues, and there was a positive correlation between them in clinical level. Moreover, SNHG7 was enriched in BMSCs-derived exosomes (BMSCs-Exos) and could be internalized by chondrocytes. Functional analysis illustrated that BMSCs-Exos administration repressed inflammatory injury, oxidative stress and ferroptosis in IL-1β-induced chondrocytes, while these changes were reinforced when SNHG7 was overexpressed in BMSCs-Exos. Notably, FSP1 silencing in chondrocytes abolished the beneficial effects mediated by exosomal SNHG7. Exosomal SNHG7 released from BMSCs inhibited inflammation and ferroptosis in IL-1β-induced chondrocytes through miR-485-5p/FSP1 axis. This work suggested that BMSCs-derived exosomal SNHG7 would be a prospective target for OA treatment.

T-Box Transcription Factor 2 Mediates Chemoresistance of Endometrial Cancer via Regulating FSP1-involved Ferroptosis.

Chemotherapy is increasingly being used in the first-line treatment of endometrial cancer (EC) patients. However, chemoresistance seriously affects its efficacy. Understanding the underlying molecular mechanisms is critical for EC treatment. We explored the regulatory role of T-Box transcription factor 2 (TBX2)-ferroptosis suppressor protein 1 (FSP1) axis in ferroptosis and chemoresistance of EC. Cisplatin-resistant cell line Ishikawa/DDP cells were utilized to generate TBX2 and FSP1 overexpression and knockdown stable cell lines by using lentivirus infection and puromycin selection. Cell viability and ferroptosis status were evaluated in EC cells with or without Cisplatin and/or FSP1 inhibitor (iFSP1) using CKK-8, lipid peroxidation, malondialdehyde, and lactate dehydrogenase release assays. Endometrial carcinoma xenograft mouse model was established to further explore the function of TBX2-FSP1 axis on ferroptosis and tumor progression in EC. TBX2 suppressed Cisplatin-induced ferroptosis through up-regulating FSP1 expression level in EC cells. On the contrary, knockdown of TBX2 reduced FSP1 expression and significantly promoted Cisplatin-induced ferroptosis. TBX2 or FSP1 overexpression and knockdown promote and inhibit EC tumor growth under Cisplatin treatment, respectively. Interestingly, silence FSP1 could reverse TBX2-mediated ferroptosis inhibition and tumor-promoting effect. TBX2-FSP1 axis inhibits ferroptosis and enhances the Cisplatin resistance, which will provide an important theoretical basis and potential solution for the clinical treatment of EC.

Temsirolimus inhibits FSP1 enzyme activity to induce ferroptosis and restrain liver cancer progression.

Ferroptosis is a non-apoptotic mode of cell death characterized by iron-dependent accumulation of lipid peroxidation. While lipid radical elimination reaction catalyzed by glutathione peroxidase 4 (GPX4) is a major anti-ferroptosis mechanism, inhibiting this pathway pharmaceutically shows promise as an anti-tumor strategy. However, certain tumor cells exhibit redundancy in lipid radical elimination pathways, rendering them unresponsive to GPX4 inhibitors. In this study, we conducted screens across different cancer cell lines and FDA-approved drugs, leading to the identification of temsirolimus in combination with the GPX4 inhibitor RSL3 as a potent inducer of ferroptosis in liver cancer cells. Mechanistically, temsirolimus sensitized liver cancer cells to ferroptosis by directly binding to and inhibiting ferroptosis suppressor protein 1 (FSP1) enzyme. Notably, while temsirolimus is recognized as a potent mTOR inhibitor, its ferroptosis-inducing effect is primarily attributed to its inhibition of FSP1 rather than mTOR activity. By performing in vitro colony formation assays and in vivo tumor xenograft models, we demonstrated that the combination of temsirolimus and RSL3 effectively suppressed liver tumor progression. This tumoricidal effect was associated with increased lipid peroxidation and induction of ferroptosis. In conclusion, our findings underscore the potential of combining multi-target ferroptosis-inducing agents to circumvent resistance to ferroptosis in liver cancer cells and highlight temsirolimus as a promising FSP1 inhibitor and ferroptosis inducer, which also deserves further investigation in translational medicine.

FGF21 inhibits ferroptosis caused by mitochondrial damage to promote the repair of peripheral nerve injury.

Ferroptosis is a new type of cell death characterized by lipid peroxidation and iron dependency, representing an emerging disease regulation mechanism. The limited understanding of ferroptosis in peripheral nerve injury (PNI) complicates the management of such injuries. Mitochondrial dysfunction, which contributes to ferroptosis, further exacerbates the challenges of peripheral nerve repair. In this study, we established an in vitro model of Schwann cells model treated with TBHP and an in vivo sciatic nerve crush injury model in rats. These models were used to investigate the effects of fibroblast growth factor 21 (FGF21) on PNI, both in vitro and in vivo, and to explore the potential mechanisms linking injury-induced ferroptosis and mitochondrial dysfunction. Our findings reveal that PNI triggers abnormal accumulation of lipid reactive oxygen species (ROS) and inactivates mitochondrial respiratory chain complex III, leading to mitochondrial dysfunction. This dysfunction catalyzes the oxidation of excessive polyunsaturated fatty acids, resulting in antioxidant imbalance and loss of ferroptosis suppressor protein 1 (FSP1), which drives lipid peroxidation. Additionally, irregular iron metabolism, defective mitophagy, and other factors contribute to the induction of ferroptosis. Importantly, we found that FGF21 attenuates the abnormal accumulation of lipid ROS, restores mitochondrial function, and suppresses ferroptosis, thus promoting PNI repair. Notably, glutathione peroxidase 4 (GPX4), a downstream target of nuclear factor E2-related factor 2 (Nrf2), and the ERK/Nrf2 pathway are involved in the regulation of ferroptosis by FGF21. FGF21 promotes peripheral nerve repair by inhibiting ferroptosis caused by mitochondrial dysfunction. Therefore, targeting mitochondria and ferroptosis represents a promising therapeutic strategy for effective PNI repair.

Triggering multiple modalities of cell death via dual-responsive nanomedicines to address the narrow therapeutic window of β-lapachone

The clinical translation of the anticancer drug β-lapachone (LAP) has been limited by the narrow therapeutic window. Stimuli-responsive anticancer drug delivery systems have gained tremendous attention in recent years to alleviate adverse effects and enhance therapeutic efficacy. Here, we report a dual pH- and enzyme-responsive nanocarrier to address the above issue of LAP. In detail, the epigallocatechin gallate (EGCG) and ferric ions were employed to engineer nanoscale ferric ion-polyphenol complexes where LAP was physically encapsulated therein. The coordination bond between Fe3+ and the catechol moiety of EGCG was sensitive to the low pH, enabling the triggered cargo release in the acidic endosomes/lysosomes. Afterward, the released LAP was activated by the overexpressed NAD(P)H: quinone oxidoreductase 1 (NQO1) and ferroptosis suppressor protein 1 (FSP1) in the tumor cells, followed by the generation of reactive oxygen species (ROS), and the induction of oxidative stress and apoptotic cell death. Meanwhile, EGCG could upregulate gasdermin E (GSDME), and ferric ions were involved in the Fenton reaction. Hence, EGCG and ferric ions could sensitize the toxicity of LAP through the induction of multiple cell death pathways (e.g., pyroptosis, ferroptosis, apoptosis, and necroptosis). The current work enlarged the LAP’s therapeutic window via controlled cargo release and vehicle sensitization.

Engineering Biodegradable Hollow Silica/Iron Composite Nanozymes for Breast Tumor Treatment through Activation of the "Ferroptosis Storm".

The activation of cellular ferroptosis is promising in tumor therapy. However, ferroptosis is parallelly inhibited by antiferroptotic substances, including glutathione peroxidase 4 (GPX4), dihydroorotate dehydrogenase (DHODH), and ferroptosis suppressor protein 1 (FSP1). Thus, it is highly desirable, yet challenging, to simultaneously suppress these three antiferroptotic substances for activating ferroptosis. Here, we rationally designed a hollow iron-doped SiO2-based nanozyme (FeSHS) loaded with brequinar (BQR) and lificiguat (YC-1), named FeSHS/BQR/YC-1-PEG, for tumor ferroptosis activation. FeSHS were developed through the continuous etching of SiO2 nanoparticles by iron ions, which exhibit pH/glutathione-responsive biodegradability, along with mimicking the activities of peroxidase, glutathione oxidase, and NAD(P)H oxidase. Specifically, glutathione depletion and NAD(P)H oxidation by FeSHS will suppress the expression of GPX4 and inhibit FSP1 by disrupting the NAD(P)H/FSP1/ubiquinone axis. In addition, the released BQR can suppress the expression of DHODH. Meanwhile, YC-1 is able to increase the cellular polyunsaturated fatty acids (PUFAs) by destroying the HIF-1α/lipid droplet axis. The elevation of levels of iron and PUFAs while simultaneously disrupting the GPX4/DHODH/FSP1 inhibitory pathways by our designed nanoplatform displayed high therapeutic efficacy both in vitro and in vivo. This work elucidates rationally designing smart nanoplatforms for ferroptosis activation and future tumor treatments.

Lipid Peroxidation Regulators GPX4 and FSP1 as Prognostic Markers and Therapeutic Targets in Advanced Gastric Cancer.

Gastric cancer is one of the most common cancers worldwide, and new therapeutic strategies are urgently needed. Ferroptosis is an intracellular iron-dependent cell death induced by the accumulation of lipid peroxidation, a mechanism different from conventional apoptosis and necrosis. Therefore, induction of ferroptosis is expected to be a new therapeutic strategy. Glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1) have been identified as the major inhibitors of ferroptosis. Herein, we performed immunohistochemistry for GPX4, FSP1, and 4-HNE using tissues from patients with gastric cancer and investigated the relationship between these factors and prognosis. Patients with high GPX4 expression or high GPX4 expression and low 4-HNE accumulation tended to have a poor prognosis (p = 0.036, 0.023), whereas those with low FSP1 expression and high 4-HNE accumulation had a good prognosis (p = 0.033). The synergistic induction of cell death by inhibiting GPX4 and FSP1 in vitro was also observed, indicating that the cell death was non-apoptotic. Our results indicate that the expression and accumulation of lipid peroxidation-related factors play an important role in the clinicopathological significance of gastric cancer and that novel therapeutic strategies targeting GPX4 and FSP1 may be effective in treating patients with gastric cancer who have poor prognosis.

CRISPR screening identifies PRMT1 as a key pro-ferroptotic gene via a two-layer regulatory mechanism

Ferroptosis is a form of nonapoptotic cell death characterized by iron-dependent peroxidation of polyunsaturated phospholipids. However, much remains unknown about the regulators of ferroptosis. Here, using CRISPR-Cas9-mediated genetic screening, we identify protein arginine methyltransferase 1 (PRMT1) as a crucial promoter of ferroptosis. We find that PRMT1 decreases the expression of solute carrier family 7 member 11 (SLC7A11) to limit the abundance of intracellular glutathione (GSH). Moreover, we show that PRMT1 interacts with ferroptosis suppressor protein 1 (FSP1), a GSH-independent ferroptosis suppressor, to inhibit the membrane localization and enzymatic activity of FSP1 through arginine dimethylation at R316, thus reducing CoQ10H2 content and inducing ferroptosis sensitivity. Importantly, genetic depletion or pharmacological inhibition of PRMT1 in mice prevents ferroptotic events in the liver and improves the overall survival under concanavalin A (ConA) exposure. Hence, our findings suggest that PRMT1 is a key regulator of ferroptosis and a potential target for antiferroptosis therapeutics.

Cholesterol Depletion-Enhanced Ferroptosis and Immunotherapy via Engineered Nanozyme.

Ferroptosis, an iron- and reactive oxygen species (ROS)-dependent cell death, holds significant promise for tumor therapy due to its ability to induce lipid peroxidation (LPO) and trigger antitumor immune responses. However, elevated cholesterol levels in cancer cells impede ferroptosis and compromise immune function. Here, a novel nanozyme, Fe-MOF/CP, composed of iron metal-organic framework (Fe-MOF) nanoparticles loaded with cholesterol oxidase and PEGylation for integrated ferroptosis and immunotherapy is introduced. Fe-MOF/CP depletes cholesterol and generates hydrogen peroxide, enhancing ROS levels and inducing LPO, thereby promoting ferroptosis. This process disrupts lipid raft integrity and downregulates glutathione peroxidase 4 and ferroptosis suppressor protein 1, further facilitating ferroptosis. Concurrently, Fe-MOF/CP augments immunogenic cell death, reduces programmed death-ligand 1 expression, and revitalizes exhausted CD8+ T cells. In vivo studies demonstrate significant therapeutic efficacy in abscopal, metastasis, and recurrent tumor models, highlighting the robust antitumor immune responses elicited by Fe-MOF/CP. This study underscores the potential of Fe-MOF/CP as a multifunctional therapeutic agent that combines ferroptosis and immunotherapy, offering a promising strategy for effective and durable cancer treatment.

52 Ferroptosis Suppressor Protein 1 is a Potent and Targetable Inhibitor of Ferroptosis in Chromophobe Renal Cell

Abstract Background There are currently no proven therapies for metastatic or unresectable Chromophobe renal cell carcinoma (ChRCC). Ferroptosis is an iron-dependent form of cell death characterized by the peroxidation of membrane polyunsaturated fatty acids, leading to membrane damage and cell death. Glutathione, a potent cellular antioxidant, counters lipid peroxidation to prevent ferroptosis. Both reduced and oxidized glutathione are markedly elevated in ChRCC (PNAS, 2018). We have previously discovered that ChRCC is hypersensitive to ferroptotic cell death induced by the pharmacologic disruption of glutathione homeostasis via the cysteine transporter SLC7A11 or glutathione peroxidase (GPX4) inhibition (PNAS, 2022). Ferroptosis suppressor protein (FSP1) is a glutathione-independent suppressor of ferroptosis. FSP1’s role in ChRCC is unexplored. Methods Transcriptional data from DepMap (484 cell lines) and Cancer Therapeutics Response Portal (CTRP) (860 cell lines) were used to study genetic or pharmacologic inhibition of GPX4 and SLC7A11. Statistical analysis was performed in PRISM 10 using Mann-Whitney U and ANOVA tests. Statistical significance was defined as p < 0.05. Results DepMap data revealed that FSP1 is the top upregulated gene in cells resistant to RNAi inhibition of GPX4 (Achilles, DEMETER2) (Panel A). In CTRP data, FSP1 was the top upregulated gene in cells resistant to the GPX4 inhibitor RSL3 and the 19th most upregulated gene in cells resistant to the SCL7A11 inhibitor, Erastin (Panel B). In The Cancer Genomic Atlas (TCGA) KICH (ChRCC) dataset, FSP1 was 2-fold higher in ChRCC compared to normal kidney (mean RSEM = 818.9 vs 445.9, p-value <0.0001) (Panel C). In vitro studies of two ChRCC cell lines, UOK276 and RCJ-T2, revealed that while siRNA-mediated inhibition of GPX4 or FSP1 individually did not induce substantial cell death, their combination was synergistic and resulted in almost complete cell death (UOK276 mean viability 8% of siCTRL, p<0.0001; RCJ-T2 mean viability 13% of siCTRL, p<0.0001). Cell viability was completely rescued by the ferroptosis inhibitor ferrostatin-1 but not by the necroptosis inhibitor necrostatin-1 or the apoptosis inhibitor Z-Vad-FMK (Panel D). siRNA-mediated GPX4 knockdown combined with FSP1 pharmacologic inhibition (icFSP1 or FSEN1) induced extensive cell death (mean viability of siGPX4 + icFSP1 group = 21% of siCTRL + DMSO group, p<0.0001; mean viability of siGPX4 + FSEN1 group = 29% of siCTRL + DMSO group, p<0.0001) (Panel E). Combining RSL3 with FSEN1, or IKE with icFSP1, also demonstrated synergy, with the ChRCC cell lines showing increased overall sensitivity to these drug combinations compared to 786-0 cells (ccRCC-derived) and HeLa cells (Panel F). Snapshots from these experiments taken at [IKE] = 177nM and/or [icFSP1] = 20 mM for UOK276, and [RSL3] = 39.4 nM and/or [FSEN1] = 20 mM for RCJ-T2, show almost complete cell death when pharmacologic inhibitors of glutathione-dependent and -independent ferroptosis suppressors are combined, but no substantial cell death when each is used individually (7% and 10% viability in combination group compared to DMSO group for UOK276 and RCJ-T2 respectively, p<0.0001) (Panel G). Conclusions We show that in vitro genetic or pharmacologic inhibition of FSP1, a glutathione-independent inhibitor of ferroptosis, leads to ferroptosis in ChRCC-derived cells when combined with genetic or pharmacologic inhibition of the glutathione-dependent suppressors of ferroptosis GPX4 or SLC7A11.

Inhibition of FSP1: A new strategy for the treatment of tumors (Review).

Ferroptosis, a regulated form of cell death, is intricately linked to iron‑dependent lipid peroxidation. Recent evidence strongly supports the induction of ferroptosis as a promising strategy for treating cancers resistant to conventional therapies. A key player in ferroptosis regulation is ferroptosis suppressor protein 1 (FSP1), which promotes cancer cell resistance by promoting the production of the antioxidant form of coenzyme Q10. Of note, FSP1 confers resistance to ferroptosis independently of the glutathione (GSH) and glutathione peroxidase‑4 pathway. Therefore, targeting FSP1 to weaken its inhibition of ferroptosis may be a viable strategy for treating refractory cancer. This review aims to clarify the molecular mechanisms underlying ferroptosis, the specific pathway by which FSP1 suppresses ferroptosis and the effect of FSP1 inhibitors on cancer cells.

Nrf2/FSP1/CoQ10 axis-mediated ferroptosis is involved in sodium aescinate-induced nephrotoxicity

Sodium aescinate (SA), an active compound found in horse chestnut seeds, is widely used in clinical practice. Recently, the incidence of SA-induced adverse events, particularly renal impairment, has increased. Our previous work demonstrated that SA causes severe nephrotoxicity via nephrocyte ferroptosis; however, the underlying mechanism remains to be fully elucidated. In the current study, we investigated additional molecular pathways involved in SA-induced nephrotoxicity. Our results showed that SA inhibited cell viability, disrupted cellular membrane integrity, and enhanced reactive oxygen species (ROS), ferrous iron (Fe2+), and malondialdehyde (MDA) levels, as well as lipid peroxidation in rat proximal renal tubular epithelial cell line (NRK-52E) cells. SA also depleted coenzyme Q10 (CoQ10, ubiquinone) and nicotinamide adenine dinucleotide (NADH) and reduced ferroptosis suppressor protein 1 (FSP1) and polyprenyltransferase (coenzyme Q2, COQ2) activity, triggering lipid peroxidation and ROS accumulation in mouse kidneys and NRK-52E cells. The overexpression of COQ2, FSP1, or CoQ10 (ubiquinone) supplementation effectively attenuated SA-induced ferroptosis, whereas iFSP1 or 4-formylbenzoic acid (4-CBA) pretreatment exacerbated SA-induced nephrotoxicity. Additionally, SA decreased nuclear factor-erythroid-2-related factor 2 (Nrf2) levels and inhibited Nrf2 binding to the −1170/-1180 bp ARE site in FSP1 promoter, resulting in FSP1 suppression. Overexpression of Nrf2 or its agonist dimethyl fumarate (DMF) promoted FSP1 expression, thereby improving cellular antioxidant capacity and alleviating SA-induced ferroptosis. These results suggest that SA-triggers renal injury through oxidative stress and ferroptosis, driven by the suppression of the Nrf2/FSP1/CoQ10 axis.

Protopanaxadiol prevents cisplatin-induced acute kidney injury by regulating ferroptosis.

Acute kidney injury (AKI) caused by cisplatin (CDDP) is a complex, critical illness with no effective or specific treatment. The purpose of the study was to assess the protective effect of protopanaxadiol (PPD) on the kidneys in CDDP-induced AKI models and its possible mechanisms. In vitro, the protection of PPD was assessed in HK-2. KM mice were injected with CDDP to induce AKI models in vivo. The determination of blood urea nitrogen and serum creatinine (SCr) was performed, and pathological changes were examined by histopathological examination. Immunostaining and western blot analyses were used to analyze the expression levels of proteins. PPD can increase the viability of HK-2 cells damaged by CDDP, improve cell morphology, and alleviate the symptoms of AKI in mice. In addition, PPD can down-regulate the protein expression of TRF and up-regulate the protein expression of Ferritin heavy chain, Glutathione peroxidase 4, and ferroptosis suppressor protein 1 reduce the iron content in cells and kidney tissues, and restore the antioxidant defense system. PPD has an inhibitory effect on cisplatin-induced nephrotoxicity, which may be related to the inhibition of ferroptosis by regulating iron metabolism and lipid peroxidation.

Ginsenoside RK1 Induces Ferroptosis in Hepatocellular Carcinoma Cells through an FSP1-Dependent Pathway.

Hepatocellular carcinoma (HCC), currently ranking as the third most lethal malignancy, poses a grave threat to human health. Ferroptosis, a form of programmed cell demise, has emerged as a promising therapeutic target in HCC treatment. In this study, we investigated the impact of ginsenoside RK1 on ferroptosis induction in HCC cells and elucidated the underlying mechanisms. The HCC cell line HepG2 was utilized to evaluate the effects of ginsenoside RK1. Distinct dosages of ginsenoside RK1 (25 μM, 50 μM, and 100 μM) were selected based on half-maximal inhibitory concentration (IC50) values. Cellular viability was assessed using a CCK8 assay, cytotoxicity was measured via lactate dehydrogenase (LDH) release assay, and colony-forming ability was evaluated using the clone formation assay. Various inhibitors targeting apoptosis (Z-VAD-FMK 20 μM), necrosis (Nec-1, 10 μM), and ferroptosis (Fer-1, 10 μM; Lip-1, 1 μM) were employed to assess ginsenoside RK1's impact on cell demise. Intracellular levels of key ions, including glutathione (GSH), malondialdehyde (MDA), and iron ions, were quantified, and the protein expression levels of ferroptosis-related genes were evaluated. The sensitivity of HCC cells to ferroptosis induction by ginsenoside RK1 was examined following the overexpression and silencing of the aforementioned target genes. Ginsenoside RK1 exhibited an inhibitory effect on HCC cells with an IC50 value of approximately 20 μM. It attenuated cellular viability and colony-forming capacity in a dose-dependent manner, concurrently reducing intracellular GSH levels and increasing intracellular Malondialdehyde (MDA) and iron ion contents. Importantly, cell demise induced by ginsenoside RK1 was specifically counteracted by ferroptosis inhibitors. Furthermore, the modulation of Ferroptosis suppressor protein 1 (FSP1) expression influenced the ability of ginsenoside RK1 to induce ferroptosis. FSP1 overexpression or silencing enhanced or inhibited ferroptosis induction by ginsenoside RK1, respectively. Ginsenoside RK1 enhances ferroptosis in hepatocellular carcinoma through an FSP1-dependent pathway.

Inhibition of Ferroptosis by Mesenchymal Stem Cell-Derived Exosomes in Acute Spinal Cord Injury: Role of Nrf2/GCH1/BH4 Axis.

The therapeutic benefits of exosomes obtained from mesenchymal stem cells (MSCs) in acute spinal cord injury (SCI) have been demonstrated in recent years, but the precise mechanisms remain unknown. In this study, the efficacy and mechanisms of MSC-derived exosomes (MSC-Exo) in acute SCI were investigated. By utilizing a BV2 ferroptosis cellular model and an SCI rat model, we investigated the effects of MSC-Exo on iron death related indicators and NF-E2 related factor 2 (Nrf2)/GTP cyclolase I (GCH1)/5,6,7,8-tetrahydrobiopterin (BH4) signaling axis, as well as their therapeutic effects on SCI rats. The results revealed that MSC-Exo effectively inhibited the production of ferrous iron, lipid peroxidation products malonaldehyde and reactive oxygen species, and ferroptosis-promoting factor prostaglandin-endoperoxide synthase 2. Concurrently, they upregulated ferroptosis suppressors FTH-1 (ferritin heavy chain 1), SLC7A11 (solute carrier family 7 member 11), FSP1 (ferroptosis suppressor protein 1), and GPX4 (glutathione peroxidase 4), contributing to enhanced neurological recovery in SCI rats. Further analysis showed the Nrf2/GTP/BH4 signaling pathway's critical role in suppressing ferroptosis. Additionally, MSC-Exo was found to inhibit lipopolysaccharide-induced ferroptosis in BV2 cells and SCI rats by activating the Nrf2/GCH1/BH4 axis. In summary, the study demonstrates that MSC-Exo mitigates microglial cell ferroptosis via the Nrf2/GCH1/BH4 axis, showing potential for preserving and restoring neurological function post-SCI.

Central role of Sigma-1 receptor in ochratoxin A-induced ferroptosis.

Ochratoxin A (OTA), a secondary fungal metabolite known for its nephrotoxic effects, is prevalent in various feeds and food items. Our recent study suggests that OTA-induced nephrotoxicity is linked to the Sigma-1 receptor (Sig-1R)-mediated mitochondrial pathway apoptosis in human proximal tubule epithelial-originated kidney-2 (HK-2) cells. However, the contribution of Sig-1R to OTA-induced nephrotoxicity involving other forms of regulated cell death, such as ferroptosis, remains unexplored. In this investigation, cell viability, malondialdehyde (MDA) levels, glutathione (GSH) levels, and protein expressions in HK-2 cells treated with OTA and/or Ferrostatin-1/blarcamesine hydrochloride/BD1063 dihydrochloride were assessed. The results indicate that a 24h-treatment with 1μM OTA significantly induces ferroptosis by inhibiting Sig-1R, subsequently promoting nuclear receptor coactivator 4 (NCOA4), long-chain fatty acid-CoA ligase 4 (ACSL4), arachidonate 5-lipoxygenase (ALOX5), autophagy protein 5 (ATG5), and ATG7, inhibiting ferritin heavy chain (FTH1), solute carrier family 7 member 11 (SLC7A11/xCT), glutathione peroxidase 4 (GPX4), peroxiredoxin 6 (PRDX6), and ferroptosis suppressor protein 1 (FSP1), reducing GSH levels, and increasing MDA levels (P < 0.05). In conclusion, OTA induces ferroptosis by inhibiting Sig-1R, subsequently promoting ferritinophagy, inhibiting GPX4/FSP1 antioxidant systems, reducing GSH levels, and ultimately increasing lipid peroxidation levels in vitro.