Ferrostatin-1 improves BMSC survival by inhibiting ferroptosis

Cell life-or-death events in osteoporosis: All roads lead to mitochondrial dynamics

Mitochondria exhibit heterogeneous shapes and networks within and among cell types and tissues, also in normal or osteoporotic bone tissues with complex cell types. This dynamic characteristic is determined by the high plasticity provided by mitochondrial dynamics and is stemmed from responding to the survival and functional requirements of various bone cells in a specific microenvironments. In contrast, mitochondrial dysfunction, induced by dysregulation of mitochondrial dynamics, may act as a trigger of cell death signals, including common apoptosis and other forms of programmed cell death (PCD). These PCD processes consisting of tightly structured cascade gene expression events, can further influence the bone remodeling by facilitating the death of various bone cells. Mitochondrial dynamics, therefore, drive the bone cells to stand at the crossroads of life and death by integrating external signals and altering metabolism, shape, and signal-response properties of mitochondria. This implies that targeting mitochondrial dynamics displays significant potential in treatment of osteoporosis. Considerable effort has been made in osteoporosis to emphasize the parallel roles of mitochondria in regulating energy metabolism, calcium signal transduction, oxidative stress, inflammation, and cell death. However, the emerging field of mitochondrial dynamics-related PCD is not well understood. Herein, to bridge the gap, we outline the latest knowledge on mitochondrial dynamics regulating bone cell life or death during normal bone remodeling and osteoporosis.

Matrine induces cardiotoxicity by promoting ferroptosis through the Nrf2 antioxidant system in H9c2 cells

Matrine (MT) has shown promising efficacy in various cancers and chronic hepatitis; however, its clinical application is limited because of its side effects. Our previous studies have indicated that MT can induce severe hepatotoxicity and nephrotoxicity. The current study aimed to investigate its cardiotoxicity and potential underlying mechanisms in H9c2 cells. Our results showed that MT induced H9c2 cell death and disrupted the cellular membrane integrity. Moreover, MT decreased glutathione (GSH) and cysteine (Cys) levels, and increased Fe2+, lipid peroxidation, reactive oxygen species (ROS), and MDA levels, ultimately leading to ferroptosis. Interestingly, these phenomena were alleviated by the ferroptosis inhibitor Fer-1, whereas MT-induced ferroptosis was exacerbated by the ferroptosis agonist RSL3. In addition, MT significantly reduced FTH, Nrf2, xCT, GPX4, and FSP1 protein levels and inhibited the transcriptional activity of Nrf2 while increasing TFR1 protein levels. Supplementation with Nrf2 agonist (Dimethyl fumarate, DMF) or selenium (Sodium selenite, SS) and CoQ10 alleviated MT-induced cytotoxic effects in H9c2 cells. These results suggest that ferroptosis, which is mediated by an imbalance in the Nrf2 antioxidant system, is involved in MT-induced cardiac toxicity.

Cellular preconditioning and mesenchymal stem cell ferroptosis

In this editorial, we comment on the article published in the recent issue of the World Journal of Stem Cells. They focus on stem cell preconditioning to prevent ferroptosis by modulating the cystathionine γ-lyase/hydrogen sulfide (H2S) pathway as a novel approach to treat vascular disorders, particularly pulmonary hypertension. Preconditioned stem cells are gaining popularity in regenerative medicine due to their unique ability to survive by resisting the harsh, unfavorable microenvironment of the injured tissue. They also secrete various paracrine factors against apoptosis, necrosis, and ferroptosis to enhance cell survival. Ferroptosis, a regulated form of cell death characterized by iron accumulation and oxidative stress, has been implicated in various pathologies encompassing degenerative disorders to cancer. The lipid peroxidation cascade initiates and sustains ferroptosis, generating many reactive oxygen species that attack and damage multiple cellular structures. Understanding these intertwined mechanisms provides significant insights into developing therapeutic modalities for ferroptosis-related diseases. This editorial primarily discusses stem cell preconditioning in modulating ferroptosis, focusing on the cystathionase gamma/H2S ferroptosis pathway. Ferroptosis presents a significant challenge in mesenchymal stem cell (MSC)-based therapies; hence, the emerging role of H2S/cystathionase gamma/H2S signaling in abrogating ferroptosis provides a novel option for therapeutic intervention. Further research into understanding the precise mechanisms of H2S-mediated cytoprotection against ferroptosis is warranted to enhance the therapeutic potential of MSCs in clinical settings, particularly vascular disorders.

Fructus Ligustri Lucidi inhibits ferroptosis in ovariectomy‑induced osteoporosis in rats via the Nrf2/HO‑1 signaling pathway

Postmenopausal osteoporosis (PMOP) has increased in prevalence in recent years, thus researchers have evaluated alternative medicine therapies. Fructus Ligustri Lucidi (FLL) can inhibit bone loss, and ferroptosis serves an important role in osteoporosis. Therefore, the present study assessed the presence of ferroptosis in PMOP and whether FLL could inhibit ferroptosis to improve bone microstructure in ovariectomized rats. Ovariectomized rats were treated with FLL (1.56 g/kg/day) for 12 weeks. Micro-CT was performed to evaluate the bone microstructure and bone mineral density. Western blotting and reverse transcription-quantitative PCR were performed to assess the relative expression levels of proteins and mRNA. Subsequently, malondialdehyde (MDA) and Fe2+ assay kits were used to quantify the MDA and Fe2+ content, respectively. The results demonstrated that ovariectomy (OVX) resulted in iron overload and the accumulation of lipid peroxide. Furthermore, the expression of key factors that inhibited ferroptosis, glutathione peroxidase 4 and solute carrier family 7 member 11 was significantly downregulated in ovariectomized rats, which was significantly reversed by FLL treatment. Furthermore, bone formation was assessed using the expression of osteogenesis-related genes, runt-related transcription factor 2 and osterix, which revealed significantly higher levels in FLL-treated rats compared with ovariectomized rats. The levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were also significantly recovered following FLL treatment. In the present study, OVX of postmenopausal osteoporotic rats was found to induce ferroptosis by enhancing lipid peroxidation and Fe2+ levels. FLL significantly suppressed ferroptosis, protected the osteogenic ability of ovariectomized rats and promoted the Nrf2/HO-1 signaling pathway.

Study of the effect of keap1 on oxidative stress in human umbilical cord mesenchymal stem cells

BACKGROUND

HucMSCs had shown promising efficacy in treating childhood diseases, but oxidative stress induced by the poor microenvironment at the site of damage resulted in low cell survival after transplantation, thus preventing the cells from maximizing therapeutic efficacy. Therefore, this study aimed to investigate the role and mechanism of keap1 in oxidative stress injury of human umbilical cord mesenchymal stem cells (hucMSCs), and to provide theoretical support for improving the efficacy of stem cell therapy.

METHODS

The hucMSCs were treated with hypoxic low-sugar-free serum (GSDH) to mimic the damaged site microenvironment after implantation. Adenoviral overexpression of keap1 gene of hucMSCs was performed in vitro, and cell proliferation ability was detected by CCK8 assay, crystal violet staining assay, and cell cycle assay. Cellular redox level was assessed by Amplex Red, MDA, and GSH/GSSG kit. Mitochondrial morphology was evaluated by mitotracker Red staining. ATP production was estimated by ATP detection kit. The mRNA and protein expression levels were tested by western blotting and RT-qPCR.

RESULTS

GSDH treatment substantially upregulated keap1 expression. Subsequently, we found that overexpression of keap1 notably inhibited cell proliferation and caused cells to stagnate in G1 phase. At the same time, overexpression of keap1 induced the production of large amounts of H2O2 and the accumulation of MDA, but suppressed the GSH/GSSG ratio and the expression of antioxidant proteins NQO1 and SOD1, which caused oxidative stress damage. Overexpression of keap1 induced cells to produce a large number of dysfunctional mitochondria resulting in reduced ATP production. Moreover, Overexpression of keap1 significantly decreased the IKKβ protein level, while upregulating IkB mRNA levels and downregulating P50 mRNA levels.

CONCLUSIONS

Overexpression of keap1 may induce oxidative stress injury in hucMSCs by down-regulating IKKβ expression and inhibiting NF-κB pathway activation. This implies the importance of keap1 in hucMSCs and it may be a potential gene for genetic modification of hucMSCs.

Polyphyllin I induced ferroptosis to suppress the progression of hepatocellular carcinoma through activation of the mitochondrial dysfunction via Nrf2/HO-1/GPX4 axis

BACKGROUND

Ferroptosis is an emerging iron-dependent programmed cell death mode characterized by lipid peroxidation and iron accumulation, closely associated with Hepatocellular Carcinoma (HCC) progression. Although the impact of Polyphyllin I (PPI), a prominent bioactive constituent derived from Paris polyphylla, on diverse malignancies has been established, the specific role and potential mechanistic pathways through which PPI modulates ferroptosis in HCC remain elusive.

PURPOSE

This study aimed to elucidate the anti-cancer properties and potential mechanisms of PPI in inducing ferroptosis and triggering mitochondrial injury in HCC.

METHODS

Cell viability was assessed using CCK-8 assays. EdU proliferation and colony formation assays were employed to evaluate cell proliferation. A wound-healing assay was performed to assess cell migration. Transwell assay was utilized to evaluate cell invasion. Ferroptosis was evaluated through the utilization of a FerroOrange fluorescent probe, malondialdehyde (MDA) and reduced glutathione (GSH) assay kits, DCFH-DA fluorescent probe, western blotting, and transmission electron microscopy (TEM) analysis. Molecular docking, immunofluorescence, and western blotting were employed to predict and validate the binding and interaction of PPI with Nrf2, HO-1, xCT, and GPX4. Mitochondrial structure and membrane potential changes were evaluated using JC-1 and Mito Tracker Green fluorescent probes. A nude mice xenograft model was constructed to determine the inhibitory effects and the levels of ferroptosis of PPI on HCC through hematoxylin and eosin (H&E), Prussian blue reaction, immunofluorescence staining, immunohistochemistry, and western blotting analysis, in vivo.

RESULTS

PPI exhibited dose-dependent inhibitory effects on the proliferation, invasion, and metastasis of HCC cells mediated by increasing reactive oxygen species (ROS) and MDA levels, promoting Fe2+ accumulation, depleting GSH, and suppressing the expression of xCT and GPX4, thereby inducing ferroptosis in HCC. The induction of ferroptosis by PPI was associated with the binding of PPI to Nrf2, HO-1, and GPX4 proteins, modulating the Nrf2/HO-1/GPX4 antioxidant axis. PPI also induced mitochondrial structural damage and decreased mitochondrial membrane potential (MMP). Inhibition of ferroptosis by ferrostatin-1 (Fer-1) mitigated the mitochondrial disruption induced by PPI. In vivo, PPI inhibited Nrf2/HO-1/GPX4 axis-induced ferroptosis, impeding HCC growth similar to the effects of sorafenib.

CONCLUSION

These results demonstrated that PPI intervention can suppress the proliferation, invasion, and metastasis of HCC cells by enhancing mitochondrial disruption and inducing ferroptosis via the Nrf2/HO-1/GPX4 axis. Consequently, our research advances the frontiers of pharmacodynamics and deepens our comprehension of the intricate mechanisms underpinning PPI. Furthermore, it has yielded an innovative treatment stratagem rooted in the tenets of Traditional Chinese Medicine (TCM), thereby furnishing a novel therapeutic avenue for addressing HCC.

NCI677397 targeting USP24-mediated induction of lipid peroxidation induces ferroptosis in drug-resistant cancer cells

Cancer represents a profound challenge to healthcare systems and individuals worldwide. The development of multiple drug resistance is a major problem in cancer therapy and can result in progression of the disease. In our previous studies, we developed small-molecule inhibitors targeting ubiquitin-specific peptidase 24 (USP24) to combat drug-resistant lung cancer. Recently, we found that the USP24 inhibitor NCI677397 induced ferroptosis, a type of programmed cell death, in drug-resistant cancer cells by increasing lipid reactive oxygen species (ROS) levels. In the present study, we investigated the molecular mechanisms and found that the targeting of USP24 by NCI677397 increased gene expression of most lipogenesis-related genes, such as acyl-CoA synthetase long-chain family member 4 (ACSL4), and activated autophagy. In addition, the activity of several antioxidant enzymes, such as glutathione peroxidase 4 (GPX4) and dihydrofolate reductase (DHFR), was inhibited by NCI677397 treatment via an increase in protein degradation, thereby inducing lipid ROS production and lipid peroxidation. In summary, we demonstrated that NCI677397 induced a marked increase in lipid ROS levels, subsequently causing lipid peroxidation and leading to the ferroptotic death of drug-resistant cancer cells. Our study provides new insights into the clinical use of USP24 inhibitors as ferroptosis inducers (FINs) to block drug resistance during chemotherapy.

New insight of the pathogenesis in osteoarthritis: the intricate interplay of ferroptosis and autophagy mediated by mitophagy/chaperone-mediated autophagy

Ferroptosis, characterized by iron accumulation and lipid peroxidation, is a form of iron-driven cell death. Mitophagy is a type of selective autophagy, where degradation of damaged mitochondria is the key mechanism for maintaining mitochondrial homeostasis. Additionally, Chaperone-mediated autophagy (CMA) is a biological process that transports individual cytoplasmic proteins to lysosomes for degradation through companion molecules such as heat shock proteins. Research has demonstrated the involvement of ferroptosis, mitophagy, and CMA in the pathological progression of Osteoarthritis (OA). Furthermore, research has indicated a significant correlation between alterations in the expression of reactive oxygen species (ROS), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and hypoxia-inducible factors (HIFs) and the occurrence of OA, particularly in relation to ferroptosis and mitophagy. In light of these findings, our study aims to assess the regulatory functions of ferroptosis and mitophagy/CMA in the pathogenesis of OA. Additionally, we propose a mechanism of crosstalk between ferroptosis and mitophagy, while also examining potential pharmacological interventions for targeted therapy in OA. Ultimately, our research endeavors to offer novel insights and directions for the prevention and treatment of OA.