Biochemical mechanism of erastin-induced ferroptotic cell death in neuronal cells

Ferroptosis is a new form of nonapoptotic cell death closely associated with glutathione (GSH) peroxidase 4 inhibition and/or GSH depletion, resulting in the accumulation of cellular iron and lipid peroxides. The exact mechanism by which GSH depletion causes the accumulation of reactive oxygen species (ROS) and lipid-ROS and subsequent ferroptotic cell death in neuronal cells remains unclear. In the present study, using immortalized HT22 mouse hippocampal neuronal cells as a model, we show that nitric oxide (NO) accumulation via protein disulfide isomerase (PDI)-mediated neuronal nitric oxide synthase (nNOS) activation plays a critical role in chemically-induced ferroptosis. Mechanistically, we find that erastin-induced GSH depletion leads to activation of PDI, which then mediates ferroptosis by catalyzing nNOS dimerization, followed by accumulation of cellular NO, ROS and lipid ROS and ultimately ferroptotic cell death. Pharmacological inhibition of PDI enzymatic activity or selective PDI knockdown can effectively abrogate erastin-induced ferroptosis in HT22 cells. The results of this study reveal an important role of PDI in mediating chemically induced ferroptosis in a neuronal cell model, and PDI may serve as a potential drug target for protection against GSH depletion-associated ferroptotic neuronal cell death.

The Regulatory Mechanism and Research Progress of Ferroptosis in Gastric Cancer

Ferroptosis is a novel cell death modality discovered in recent years that is different from apoptosis and necrosis. It is usually associated with changes in the regulatory signaling in multiple organelles and depends on iron. It is caused by an imbalance between the generation and degradation of intracellular lipid reactive oxygen species (ROS). In addition to increased levels of cytoplasmic ROS and lipids, decreased mitochondrial volume and thickened mitochondrial membranes are markers of ferroptotic death. Gastric cancer is a common malignant tumor, but few studies on the possible role of ferroptosis in gastric cancer have been reported. Although ferroptosis is involved in multifactor-induced carcinogenesis, studies have also shown the role of ferroptosis in the selective killing of tumor cells, thereby inhibiting tumor progression and metastasis. In this paper, the definition, characteristics, and regulatory mechanism of ferroptosis and its potential role in gastric cancer are discussed. Therefore, this review is expected to provide a reference for the treatment of diseases based on ferroptosis and provide a direction for future research on the pathogenesis and development of gastric cancer and the development of anticancer drugs.

Calycosin plays a protective role in diabetic kidney disease through the regulation of ferroptosis

CONTEXT

Diabetic kidney disease (DKD) is a devastating complication of diabetes. Renal functional deterioration caused by tubular injury is the primary change associated with this disease. Calycosin shows protective roles in various diseases.

OBJECTIVES

This study explored the function and underlying mechanism of calycosin in DKD.

MATERIALS AND METHODS

HK-2 cells were treated with 25 mM high glucose (HG) to establish a renal tubule injury cell model. Then, the viability of cells treated with 0, 5, 10, 20, 40 and 80 μM of calycosin was measured using Cell Counting Kit-8. For the in vivo model, db/db mice were treated with 10 and 20 mg/kg/day of calycosin; db/m mice served as controls. The histomorphology was analyzed via haematoxylin and eosin staining.

RESULTS

HG-induced decreased expression of glutathione (491.57 ± 33.56 to 122.6 ± 9.78 μmol/mL) and glutathione peroxidase 4 (inhibition rate 92.3%) and increased expression of lactate dehydrogenase (3.85 ± 0.89 to 16.84 ± 2.18 U/mL), malondialdehyde (3.72 ± 0.66 to 18.2 ± 1.58 nmol/mL), lipid ROS (4.31-fold increase) and NCOA4 (7.69-fold increase). The effects induced by HG could be blocked by calycosin. Moreover, calycosin alleviated the HG-induced decrease of cell viability and the increase of lipid ROS, but erastin could block the effects caused by calycosin. The in vivo model showed that calycosin alleviated the renal injury caused by diabetes.

DISCUSSION AND CONCLUSION

Calycosin has a protective effect on diabetic kidney disease; ferroptosis may be involved in this process.