Identification and initial characterization of a potent inhibitor of ferroptosis

Mutant p53 reactivators protect breast cancer cells from ferroptosis

Ferroptosis is a novel nonapoptotic form of cell death characterized by iron-dependent reactive oxygen species-mediated lipid peroxidation. In several different cell systems, the tumor suppressor p53 can enhance sensitivity to ferroptotic inducers. At least half of all human cancers show loss of function of p53. Furthermore, many of those tumors express mutant forms of p53 that has lost its wild-type function. Several groups have designed small molecules that can reactivate the wild-type function of these missense p53 mutants. We reasoned that p53 reactivators may also enhance sensitivity of certain cancer cells to ferroptosis stimuli. To test this idea we combined a number of different p53 reactivators with small molecule inducers of ferroptosis. In contrast, we observed that several p53 reactivators protected cells from cell death induced by ferroptotic inducers. Surprisingly, this protection still occurred in p53-null cell lines. We observed that these reactivators were neither free radical scavengers nor ion chelators. One of these p53 reactivator molecules, NSC 59984, reduced expression of GPX4, which is unlikely to explain its ability to reduce sensitivity to ferroptosis. We suggest that these p53 reactivators function via an unknown, p53-independent manner to suppress ferroptosis.

Ferroptosis in non-alcoholic liver disease: Molecular mechanisms and therapeutic implications

Ferroptosis refers to a novel modality of regulated cell death characterized by excessive iron accumulation and overwhelming lipid peroxidation, which takes an important part in multiple pathological processes associated with cell death. Considering the crucial roles of the liver in iron and lipid metabolism and its predisposition to oxidative insults, more and more studies have been conducted to explore the relationship between ferroptosis and various liver disorders, including non-alcoholic fatty liver disease (NAFLD). With increased morbidity and high mortality rates, NAFLD has currently emerged as a global public health issue. However, the etiology of NAFLD is not fully understood. In recent years, an accumulating body of evidence have suggested that ferroptosis plays a pivotal role in the pathogenesis of NAFLD, but the precise mechanisms underlying how ferroptosis affects NAFLD still remain obscure. Here, we summarize the molecular mechanisms of ferroptosis and its complicated regulation systems, delineate the different effects that ferroptosis exerts in different stages of NAFLD, and discuss some potential effective therapies targeting ferroptosis for NAFLD treatment, which putatively points out a novel direction for NAFLD treatment.

Berberine hydrochloride alleviates imatinib mesylate - induced cardiotoxicity through the inhibition of Nrf2-dependent ferroptosis

Imatinib mesylate (IMA) belonging to the selective tyrosine kinase inhibitor family has been proven to induce cardiotoxic effects along with therapeutic strategies. Nrf2-dependent ferroptosis has been implicated in the cardiotoxicity induced by IMA. The present study was designed to investigate the protective effects of berberine hydrochloride (Ber) on cardiac injuries induced by IMA and to explore its potential mechanisms. In H9c2 cells, cell viability, the generation of reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and labile iron pool (LIP) levels were measured. In a mouse model of IMA-induced cardiomyopathy, serum biomarkers and cardiac tissues were examined. A western blot assay was performed to evaluate the expression of ferroptosis-related proteins in vitro and in vivo. Our results indicated that Ber increased cell viability and MMP and decreased cellular ROS and iron levels in comparison to the IMA group of H9c2 cells. In mice, Ber significantly improved cardiac status and attenuated the level of ferroptosis biomarkers including malonaldehyde (MDA) and iron content. Additionally, Ber downregulated the expression of transferrin receptor (TfR) and P53 and upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase-1 (NQO1), ferritin heavy chain-1 (FTH1), and glutathione peroxidase 4 (GPX4) in H9c2 cells and mice. The present data indicated that Ber has the potential to protect against IMA-induced cardiotoxicity, partly via inhibiting Nrf2-dependent ferroptosis.

First-in-Class Dual Mechanism Ferroptosis-HDAC Inhibitor Hybrids

HDAC inhibitors are an attractive class of cytotoxic agents for the design of hybrid molecules. Several HDAC hybrids have emerged over the years, but none combines HDAC inhibition with ferroptosis, a combination which is being extensively studied because it leads to enhanced cytotoxicity and attenuated neuronal toxicity. We combined the pharmacophores of SAHA and CETZOLE molecules to design the first-in-class dual mechanism hybrid molecules, which induce ferroptosis and inhibit HDAC proteins. The involvement of both mechanisms in cytotoxicity was confirmed by a series of biological assays. The cytotoxic effects were evaluated in a series of cancer and neuronal cell lines. Analogue HY-1 demonstrated the best cytotoxic profile with GI50 values as low as 20 nM. Although the increase in activity of the hybrids over the combinations is modest in cellular systems, they have the potential advantage of homogeneous spatiotemporal distribution in in vivo systems.

Tunable Cysteine-Targeting Electrophilic Heteroaromatic Warheads Induce Ferroptosis

Once considered potential liabilities, the modern era witnesses a renaissance of interest in covalent inhibitors in drug discovery. The available toolbox of electrophilic warheads is limited by constraints on tuning reactivity and selectivity. Following our work on a class of ferroptotic agents termed CETZOLEs, we discovered new tunable heterocyclic electrophiles which are capable of inducing ferroptosis. The biological evaluation demonstrated that thiazoles with an alkyne electrophile at the 2-position selectively induce ferroptosis with high potency. Density functional theory calculations and NMR kinetic studies demonstrated the ability of our heterocycles to undergo thiol addition, an apparent prerequisite for cytotoxicity. Chemoproteomic analysis indicated several potential targets, the most prominent among them being GPX4 protein. These results were further validated by western blot analysis and the cellular thermal shift assay. Incorporation of these heterocycles into appropriate pharmacophores generated highly cytotoxic agents such as the analogue BCP-T.A, with low nM IC50 values in ferroptosis-sensitive cell lines.

Molecular mechanisms of ferroptosis and its role in prostate cancer therapy

Prostate cancer (PCa) is a highly prevalent disease that affects men's health worldwide and is the second most common malignancy in males. Ferroptosis is a novel form of programmed cell death characterized by iron overload and the accumulation of lipid peroxidation, which differs from the regulated cell death modes of necrosis, apoptosis, and autophagy. Substantial progress has been achieved in researching the occurrence and regulatory mechanisms of ferroptosis, which is closely associated with cancer initiation, progression, and suppression and is expected to become a new breakthrough point in the PCa treatment. This review will summarize the mechanisms involved in PCa, and we detail the molecular mechanisms of ferroptosis and its role in PCa treatment.

Efficient Magnetic Nanocatalyst-Induced Chemo- and Ferroptosis Synergistic Cancer Therapy in Combination with T1-T2 Dual-Mode Magnetic Resonance Imaging Through Doxorubicin Delivery

Excessive iron ions in cancer cells can catalyze H₂O₂ into highly toxic ^•OH and then promote the generation of reactive oxygen species (ROS), inducing cancer ferroptosis. However, the efficacy of the ferroptosis catalyst is still insufficient because of low Fe(II) release, which severely limited its application in clinic. Herein, we developed a novel magnetic nanocatalyst for MRI-guided chemo- and ferroptosis synergistic cancer therapies through iRGD-PEG-ss-PEG-modified gadolinium engineering magnetic iron oxide-loaded Dox (ipGdIO-Dox). The introduction of the gadolinium compound disturbed the structure of ipGdIO-Dox, making the magnetic nanocatalyst be more sensitive to weak acid. When ipGdIO-Dox entered into cancer cells, abundant Fe(II) ions were released and then catalyzed H₂O₂ into highly toxic OH^•, which would elevate cellular oxidative stress to damage mitochondria and cell membranes and induce cancer ferroptosis. In addition, the iRGD-PEG-ss-PEG chain coated onto the nanoplatform was also broken by high expression of GSH, and then, the Dox was released. This process not only effectively inhibited DNA replication but also further activated cellular ROS, making the nanoplatform achieve stronger anticancer ability. Besides, the systemic delivery of ipGdIO-Dox significantly enhanced the T₁- and T₂-weighted MRI signal of the tumor, endowing accurate diagnostic capability for tumor recognition. Therefore, ipGdIO-Dox might be a promising candidate for developing an MRI-guided chemo- and ferroptosis synergistic theranostic system.

Role of Ferroptosis in Non-Alcoholic Fatty Liver Disease and Its Implications for Therapeutic Strategies

Non-alcoholic fatty liver disease (NAFLD) has become the chronic liver disease with the highest incidence throughout the world, but its pathogenesis has not been fully elucidated. Ferroptosis is a novel form of programmed cell death caused by iron-dependent lipid peroxidation. Abnormal iron metabolism, lipid peroxidation, and accumulation of polyunsaturated fatty acid phospholipids (PUFA-PLs) can all trigger ferroptosis. Emerging evidence indicates that ferroptosis plays a critical role in the pathological progression of NAFLD. Because the liver is the main organ for iron storage and lipid metabolism, ferroptosis is an ideal target for liver diseases. Inhibiting ferroptosis may become a new therapeutic strategy for the treatment of NAFLD. In this article, we describe the role of ferroptosis in the progression of NAFLD and its related mechanisms. This review will highlight further directions for the treatment of NAFLD and the selection of corresponding drugs that target ferroptosis.

Tumor suppressor p53 promotes ferroptosis in oxidative stress conditions independent of modulation of ferroptosis by p21, CDKs, Rb and E2F

p53 is a well-established critical cell cycle regulator. By inducing transcription of the gene encoding p21, p53 inhibits cyclin-dependent kinase (CDK)-mediated phosphorylation of cell cycle inhibitor RB proteins. Phosphorylation of RB releases E2F transcription factor proteins that transactivate cell cycle-promoting genes. Here we sought to uncover the contribution of p53, p21, CDK, RB, and E2F to the regulation of ferroptosis, an oxidative form of cell death. Our studies have uncovered unexpected complexity in this regulation. First, we showed that elevated levels of p53 enhance ferroptosis in multiple inducible and isogenic systems. On the other hand, we found that p21 suppresses ferroptosis. Elevation of CDK activity also suppressed ferroptosis under conditions where p21 suppressed ferroptosis, suggesting that the impact of p21 must extend beyond CDK inhibition. Furthermore, we showed that overexpression of E2F suppresses ferroptosis in part via a p21-dependent mechanism, consistent with reports that this transcription factor can induce transcription of p21. Finally, deletion of RB genes enhanced ferroptosis. Taken together, these results show that signals affecting ferroptotic sensitivity emanate from multiple points within the p53 tumor suppressor pathway.