Seratrodast inhibits ferroptosis by suppressing lipid peroxidation.

Ferroptosis is a regulated and non-apoptotic form of cell death mediated by iron-dependent peroxidation of polyunsaturated fatty acyl tails in phospholipids. Research of the past years has shed light on the occurrence of ferroptosis in organ injury and degenerative diseases of the brain, kidney, heart, and other tissues. Hence, ferroptosis inhibition may prove therapeutically beneficial to treat distinct diseases.

PRDX6 contributes to selenocysteine metabolism and ferroptosis resistance.

Selenocysteine (Sec) metabolism is crucial for cellular function and ferroptosis prevention and begins with the uptake of the Sec carrier, selenoprotein P (SELENOP). Following uptake, Sec released from SELENOP is metabolized via selenocysteine lyase (SCLY), producing selenide, a substrate for selenophosphate synthetase 2 (SEPHS2), which provides the essential selenium donor, selenophosphate (HSePO), for the biosynthesis of the Sec-tRNA. Here, we discovered an alternative pathway in Sec metabolism mediated by peroxiredoxin 6 (PRDX6), independent of SCLY.

Troubling bonds: lipid unsaturation promotes selenium dependency and sensitivity to ferroptosis.

Cancer cells exhibit a remarkable ability to orchestrate metabolic adaptations to survive and proliferate. Such metabolic adaptations, including carbohydrates, amino acids and lipid metabolism, have been shown to also contribute to the pathological cascade during cancer progression and therapy resistance. Importantly, these adaptations provide a rational for targeted therapies inducing selective cell death.

Iron: The Secret Ingredient Breaking PARPi Resistance.

PARP inhibitors (PARPi) are used as a first-line treatment option for cancers with BRCA1/2 mutations, yet a significant number of patients show a limited response to these agents. In the present study, Lei and colleagues demonstrate that PARPi promote increased ferroptosis sensitivity and this can be exploited therapeutically to improve the response to PARPi, marking an important therapeutic concept to exploit ferroptosis-based strategies in clinical settings. See related article by Lei et al.

Zeb1 mediates EMT/plasticity-associated ferroptosis sensitivity in cancer cells by regulating lipogenic enzyme expression and phospholipid composition.

Therapy resistance and metastasis, the most fatal steps in cancer, are often triggered by a (partial) activation of the epithelial-mesenchymal transition (EMT) programme. A mesenchymal phenotype predisposes to ferroptosis, a cell death pathway exerted by an iron and oxygen-radical-mediated peroxidation of phospholipids containing polyunsaturated fatty acids. We here show that various forms of EMT activation, including TGFβ stimulation and acquired therapy resistance, increase ferroptosis susceptibility in cancer cells, which depends on the EMT transcription factor Zeb1.

PRDX6 contributes to selenocysteine metabolism and ferroptosis resistance.

Selenocysteine (Sec) metabolism is crucial for cellular function and ferroptosis prevention and has traditionally been thought to begin with the uptake of the Sec carrier selenoprotein P (SELENOP). Following uptake, Sec released from SELENOP undergoes metabolisation via selenocysteine lyase (SCLY), producing selenide, a substrate used by selenophosphate synthetase 2 (SEPHS2), which provides the essential selenium donor - selenophosphate - for the biosynthesis of the selenocysteine tRNA. Here, we report the discovery of an alternative pathway mediating Sec metabolisation that is independent of SCLY and mediated by peroxiredoxin 6 (PRDX6).

Degradation of hexosylceramides is required for timely corpse clearance via formation of cargo-containing phagolysosomal vesicles.

Efficient degradation of phagocytic cargo in lysosomes is crucial to maintain cellular homeostasis and defending cells against pathogens. However, the mechanisms underlying the degradation and recycling of macromolecular cargo within the phagolysosome remain incompletely understood. We previously reported that the phagolysosome containing the corpse of the polar body in C.

Enhancing 7-dehydrocholesterol suppresses brain ferroptosis and tissue injury after neonatal hypoxia-ischemia.

Neonatal hypoxic-ischemic brain injury (HIBI) results in part from excess reactive oxygen species and iron-dependent lipid peroxidation (i.e. ferroptosis).

Treatment with siRNAs is commonly associated with GPX4 up-regulation and target knockdown-independent sensitization to ferroptosis.

Small interfering RNAs (siRNAs) are widely used in biomedical research and in clinical trials. Here, we demonstrate that siRNA treatment is commonly associated with significant sensitization to ferroptosis, independently of the target protein knockdown. Genetically targeting mitochondrial antiviral-signaling protein (MAVS) reversed the siRNA-mediated sensitizing effect, but no activation of canonical MAVS signaling, which involves phosphorylation of IkBα and interferon regulatory transcription factor 3 (IRF3), was observed.

Aminic Organoselenium Compounds as Glutathione Peroxidase Mimics and Inhibitors of Ferroptosis.

The synthesis of diarylamine-based organoselenium compounds via the nucleophilic substitution reactions has been described. Symmetrical monoselenides and diselenides were conveniently synthesized by the reduction of their corresponding selenocyanates using sodium borohydride. Selenocyanates were obtained from 2-chloro acetamides by the nucleophilic displacement with potassium selenocyanate.

Thiol starvation triggers melanoma state switching in an ATF4 and NRF2-dependent manner.

The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma.

Integrated chemical and genetic screens unveil FSP1 mechanisms of ferroptosis regulation.

Ferroptosis, marked by iron-dependent lipid peroxidation, may present an Achilles heel for the treatment of cancers. Ferroptosis suppressor protein-1 (FSP1), as the second ferroptosis mainstay, efficiently prevents lipid peroxidation via NAD(P)H-dependent reduction of quinones. Because its molecular mechanisms have remained obscure, we studied numerous FSP1 mutations present in cancer or identified by untargeted random mutagenesis.

Sabotaging the breaks: FSEN1 expands the toolbox of FSP1 inhibitors.

The report of heightened lipid peroxidation has shone a spotlight on vulnerabilities within challenging cancers. In this context, FSP1 emerges as a pivotal regulator, actively countering the destructive effects of lipid peroxidation. In a groundbreaking development detailed in the latest issue of Cell Chemical Biology, Hendricks et al.

LRP8-mediated selenocysteine uptake is a targetable vulnerability in MYCN-amplified neuroblastoma.

Ferroptosis has emerged as an attractive strategy in cancer therapy. Understanding the operational networks regulating ferroptosis may unravel vulnerabilities that could be harnessed for therapeutic benefit. Using CRISPR-activation screens in ferroptosis hypersensitive cells, we identify the selenoprotein P (SELENOP) receptor, LRP8, as a key determinant protecting MYCN-amplified neuroblastoma cells from ferroptosis.

The integrated stress response effector ATF4 is an obligatory metabolic activator of NRF2.

The redox regulator NRF2 becomes activated upon oxidative and electrophilic stress and orchestrates a response program associated with redox regulation, metabolism, tumor therapy resistance, and immune suppression. Here, we describe an unrecognized link between the integrated stress response (ISR) and NRF2 mediated by the ISR effector ATF4. The ISR is commonly activated after starvation or ER stress and plays a central role in tissue homeostasis and cancer plasticity.

Ferroptosis: mechanisms and implications for cancer development and therapy response.

As cancer cells develop resistance to apoptosis, non-apoptotic cell death modalities, such as ferroptosis, have emerged as promising strategies to combat therapy-resistant cancers. Cells that develop resistance to conventional therapies or metastatic cancer cells have been shown to have increased sensitivity to ferroptosis. Therefore, targeting the regulatory elements of ferroptosis in cancer could offer novel therapeutic opportunities.

Molecular characterization of AIFM2/FSP1 inhibition by iFSP1-like molecules.

Ferroptosis is a form of cell death characterized by phospholipid peroxidation, where numerous studies have suggested that the induction of ferroptosis is a therapeutic strategy to target therapy refractory cancer entities. Ferroptosis suppressor protein 1 (FSP1), an NAD(P)H-ubiquinone reductase, is a key determinant of ferroptosis vulnerability, and its pharmacological inhibition was shown to strongly sensitize cancer cells to ferroptosis. A first generation of FSP1 inhibitors, exemplified by the small molecule iFSP1, has been reported; however, the molecular mechanisms underlying inhibition have not been characterized in detail.

Hydropersulfides inhibit lipid peroxidation and ferroptosis by scavenging radicals.

Ferroptosis is a type of cell death caused by radical-driven lipid peroxidation, leading to membrane damage and rupture. Here we show that enzymatically produced sulfane sulfur (S) species, specifically hydropersulfides, scavenge endogenously generated free radicals and, thereby, suppress lipid peroxidation and ferroptosis. By providing sulfur for S biosynthesis, cysteine can support ferroptosis resistance independently of the canonical GPX4 pathway.

GPX4: old lessons, new features.

GPX4 is a selenocysteine-containing protein that plays an essential role in repairing peroxidised phospholipids. Its role in organismal homeostasis has been known for decades, and it has been reported to play a pivotal role in cell survival and mammalian embryonic development. In recent years, GPX4 has been associated with a cell death modality dubbed ferroptosis.

CD8 T cells PUF(A)ing the flames of cancer ferroptotic cell death.

In this issue of Cancer Cell, Liao et al. demonstrate that CD8 T cell-secreted interferon-gamma (IFN-γ) rewires cancer cell lipid metabolism via the enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4). ACSL4 activates polyunsaturated fatty acids and sensitizes cancer cells to ferroptosis in immunotherapy-relevant settings.