Curcumin Induces Ferroptosis in A549 CD133+ Cells through the GSH-GPX4 and FSP1-CoQ10-NAPH Pathways

BACKGROUND

Cancer stem cells (CSCs) are characterized by an ability for unlimited proliferation and efficiency of self-renewal. The targeting of lung CSCs (LCSCs)-related signaling pathways represent a promising therapeutic strategy for treatment of lung cancer. Ferroptosis a potential strategy for LCSCs treatment, and curcumin cloud induce ferroptosis. In this study, we aimed to observe the effects of curcumin on LCSCs via ferroptosis-related pathways.

METHODS

In this study, A549 cluster of differentiation (CD)133⁺ and A549 CD133^- cells were isolated using magnetic bead-based separation. Colony formation and sphere formation assays, as well as cells injection in non-obese diabetes/severe combined immune deficiency (NOD/SCID) mice, were used to analyze the tumorigenic ability of cells differentially expressing CD133. A549 CD133⁺ cells were treated with different doses of curcumin (0, 10, 20, 40, 80 μM). Cell viability, glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1) expressions were measured. The 50% inhibitory concentration (IC₅₀) of curcumin, two ferroptosis inducers, inhibitor of GPX4 (RSL3) and inhibitor of FSP1 (iFSP1), and a ferroptosis inhibitor, ferrostatin-1 (Fer-1), were used to investigate the mechanism underlying the effect of curcumin on ferroptosis in A549 CD133⁺ cells.

RESULTS

A549 CD133⁺ cells had greater tumorigenic ability than A549 cells. Curcumin treatment suppressed the expressions of GPX4 (glutathione peroxidase 4) and FSP1 in A549 CD133⁺ cells, thereby inducing ferroptosis. RSL3 and iFSP1 respectively suppressed the GSH (glutathione)-GPX4 and FSP1 (ferroptosis suppressor protein 1)-CoQ10 (coenzyme Q10)-nicotinamide adenine dinucleotide (NADH) pathways in A549 CD133⁺ cells. However, the roles of curcumin were blocked by Fer-1 treatment.

CONCLUSIONS

In this study, curcumin induced ferroptosis through inhibiting the GSH-GPX4 and FSP1-CoQ10-NADH pathways in A549 CD133⁺ cells, resulting in the inhibition of their self-renewal potential.

Effects of ferroptosis in myocardial ischemia/reperfusion model of rat and its association with Sestrin 1

BACKGROUND

Ferroptosis is a type of iron-dependent programmed cell death. The inhibition of ferroptosis has been reported to alleviate myocardial ischemia/reperfusion injury (IRI). However, it is unknown whether this protective effect occurs in the ischemia or reperfusion phase. Sestrin 1 (Sesn1) possesses remarkable cytoprotective functions to diverse cellular stresses. However, whether Sesn1 is involved in the regulatory process of ferroptosis during myocardial IRI is unknown.

OBJECTIVES

This study aimed to simulate an acute myocardial infarction (AMI) that occurs in rats within 6 h, verify the occurrence and effects of ferroptosis in the phases of ischemia and reperfusion, and further explore the relationship between ferroptosis, IRI and Sesn1.

MATERIAL AND METHODS

The hearts of Sprague Dawley (SD) rats undergoing ischemia for varying lengths of time or having undergone ischemia followed by varying lengths of reperfusion were examined. The occurrence of ferroptosis was verified by detecting changes in ferroptosis biomarkers. In addition, ferrstatin-1 (Fer-1) was administered to demonstrate the effect of ferroptosis in myocardial IRI and to detect changes in Sesn1.

RESULTS

The results showed that the myocardial damage was more severe with more prolonged myocardial ischemia. There were no significant changes in ferroptosis biomarkers in cardiac tissues during the ischemia phase, the levels of iron and malondialdehyde (MDA) were elevated, and the expression of glutathione peroxidase 4 (GPX4) and ferritin heavy chain 1 (FTH1) were decreased after myocardial IRI. Compared to the ischemia/reperfusion (I/R) group, the treatment with Fer-1 before reperfusion can attenuate myocardial IRI, reverse the decrease in GPX4 and FTH1 expression, and decrease the rise in iron content and MDA. In addition, we found that the expression of Sesn1 was reduced in hearts that suffered IRI; however, the treatment with Fer-1 can reverse this situation.

CONCLUSIONS

Ferroptosis occurred during the myocardial reperfusion phase but not ischemia. The inhibition of ferroptosis exerted beneficial effects on myocardial IRI, providing a theoretical basis for targeted therapy in patients with AMI. Sestrin 1, regulated by ferroptosis, may play an important role in myocardial IRI.

Quercetin alleviates ferroptosis accompanied by reducing M1 macrophage polarization during neutrophilic airway inflammation

Ferroptosis is a kind of regulated cell death, supporting the pathological process of lung inflammation, including asthma. Quercetin (QCT), a kind of natural dietary flavonoid, exerts anti-inflammatory and anti-ferroptosis effects in various diseases. However, the role of QCT in ferroptosis-associated airway inflammation of neutrophilic asthma remains to be described. Our study aimed to investigate the therapeutic effects of QCT on neutrophilic airway inflammation of asthma. Ferrostatin-1 (Fer-1), as a kind of ferroptosis inhibitor, was used to demonstrate whether neutrophilic airway inflammation of asthma relied on ferroptosis. In our study, the alleviation effect of QCT on neutrophilic airway inflammation was similar to Fer-1. Moreover, the significantly decreased levels of ferroptosis anti-oxidant protein (GPX4 and SLC7A11), increased malondialdehyde (MDA) levels, upregulated levels of 4-hydroxynonenal (4-HNE) expression by immunohistochemistry, and distorted mitochondria morphological changes in the lung tissues suggested lung ferroptosis in neutrophilic airway inflammation, which could be reversed by QCT treatment. In vitro experiments showed that QCT reduced LPS-induced ferroptosis through upregulating cell viability and levels of ferroptosis anti-oxidant protein (SLC7A11 and GPX4), reducing inflammatory cytokines, and decreasing the levels of MDA. Furthermore, ferroptosis was accompanied by enhancing M1 phenotype in neutrophilic airway inflammation, and QCT suppressed ferroptosis by inhibiting the pro-inflammatory M1 profile in vitro and in vivo, just as Fer-1 did. In conclusion, our study found that QCT ameliorated ferroptosis-associated neutrophilic airway inflammation accompanied by inhibiting M1 macrophage polarization. QCT may be a promising ferroptosis inhibitor for neutrophilic airway inflammation.

Single-cell RNA sequencing reveals a landscape and targeted treatment of ferroptosis in retinal ischemia/reperfusion injury

BACKGROUND

The aim of this study was to establish a complete retinal cell atlas of ischemia-reperfusion injury by single-cell RNA sequencing, and to explore the underlying mechanism of retinal ischemia-reperfusion injury in mice.

METHODS

Single-cell RNA sequencing was used to evaluate changes in the mouse retinal ischemia reperfusion model. In vivo and in vitro experiments were performed to verify the protective effect of inhibiting ferroptosis in retinal ischemia-reperfusion injury.

RESULTS

After ischemia-reperfusion injury, retinal cells were significantly reduced, accompanied by the activation of myeloid and a large amount of blood-derived immune cell infiltration. The IFNG, MAPK and NFKB signaling pathways in retinal neuronal cells, together with the TNF signaling pathway in myeloid give rise to a strong inflammatory response in the I/R state. Besides, the expression of genes implicating iron metabolism, oxidative stress and multiple programed cell death pathways have changed in cell subtypes described above. Especially the ferroptosis-related genes and blocking this process could apparently alleviate the inflammatory immune responses and enhance retinal ganglion cells survival.

CONCLUSIONS

We established a comprehensive landscape of mouse retinal ischemia-reperfusion injury at the single-cell level, revealing the important role of ferroptosis during this injury, and targeted inhibition of ferroptosis can effectively protect retinal structure and function.