Dioscin induces ferroptosis and synergistic cytotoxicity with chemotherapeutics in melanoma cells

A systematic review of spirostanol saponins and anticancer natural products isolated from Tacca plantaginea (Hance) Drenth

The plant genus Tacca comprises twenty species including Tacca plantaginea, essentially distributed in the Indo-China region. Medicinal preparations from the rhizomes are used traditionally to treat gastrointestinal ailments, stomach aches and inflammatory disorders. A variety of bioactive molecules have been isolated from T. plantaginea, including potent anticancer steroids such as the taccanolides which interfere with microtubules dynamic. Other efficient anticancer natural products have been isolated from the plant, in particular a series of diosgenin/yamogenin-type sapogenins including taccaoside (monodesmosidic) and taccaoside A (bidesmosidic). Taccaoside A displays marked anticancer properties through two complementary mechanisms: a direct action on cancer stem cells via HRas and Pi3K/Akt signaling and an indirect immunomodulatory action via activation of cytotoxic T cells. A similar mechanism of action has been invoked with a total saponin extract from Schizocapsa plantaginea Hance (synonym to T. plantaginea) and the saponin SSPH 1. This saponin reduced tumor growth in mice through stimulation of cytotoxic T lymphocytes. Other bioactive products have been isolated from T. plantaginea, including withanolide-type steroids (plantagiolides, chantriolides), diarylheptanoids (plantagineosides) and different saponins (diosbulbisides, lieguonins). The discussion centers around the mechanism of action of spirostanol saponins, with the objective to promote their study as immuno-active anticancer agents.

Molecular and therapeutic landscape of ferroptosis in skin diseases

ABSTRACT

Regulated cell death (RCD) is a critical physiological process essential in maintaining skin homeostasis. Among the various forms of RCD, ferroptosis stands out due to its distinct features of iron accumulation, lipid peroxidation, and involvement of various inhibitory antioxidant systems. In recent years, an expanding body of research has solidly linked ferroptosis to the emergence of skin disorders. Therefore, understanding the mechanisms underlying ferroptosis in skin diseases is crucial for advancing therapy and prevention strategies. This review commences with a succinct elucidation of the mechanisms that underpin ferroptosis, embarks on a thorough exploration of ferroptosis's role across a spectrum of skin conditions, encompassing melanoma, psoriasis, systemic lupus erythematosus (SLE), vitiligo, and dermatological ailments precipitated by ultraviolet (UV) exposure, and scrutinizes the potential therapeutic benefits of pharmacological interventions aimed at modulating ferroptosis for the amelioration of skin diseases.

FerroLigandDB: A Ferroptosis Ligand Database of Structure-Activity Relations

Ferroptosis is an iron-dependent programmed cell death characterized by lipid peroxidation that is linked to the pathophysiological processes in many diseases, such as neurodegenerative diseases, cancers, ischemia-reperfusion injuries, and organ damages. Many proteins are associated with ferroptosis signal transduction pathways. Novel chemical compounds are demanded to explore and regulate these pathways. Therefore, a ferroptosis ligand database, which holds relations among chemical structures, targets, bioactivities, and diseases, is needed for discovering and designing new ferroptosis regulators. This work reports FerroLigandDB, a manually curated database for small-molecular ferroptosis regulators. The database comprises 466 ferroptosis inducer entries (with 380 unique molecular structures) and 539 ferroptosis inhibitor entries (with 468 unique molecular structures) (note: one compound can be recorded as multiple entries due to the different assays). Each ferroptosis ligand entry is detailed with compound IDs, structure attributes, bioactivity values, test objects, target information, associated diseases, and references. The fields in the FerroLigandDB database implicitly contain relationships among chemical structures, bioactivities, targets, and diseases. Thus, FerroLigandDB is a comprehensive resource for scientists to design and discover novel ferroptosis regulators. The user interface of FerroLigandDB is implemented with query features and data visualization facilities. With compound identifiers, the compounds are linked to the records of other chemoinformatics databases (such as PubChem and SciFinder). The FerroLigandDB database is freely accessible at http://ferr.gulab.org.cn/.

Targeting ferroptosis in melanoma: cancer therapeutics

Melanoma is an aggressive kind of skin cancer; its rate has risen rapidly over the past few decades. Melanoma reports for only about 1% of skin cancers but leads to a high majority of skin cancer deaths. Thus, new useful therapeutic approaches are currently required, to state effective treatments to consistently enhance the overall survival rate of melanoma patients. Ferroptosis is a recently identified cell death process, which is different from autophagy, apoptosis, necrosis, and pyroptosis in terms of biochemistry, genetics, and morphology which plays an important role in cancer treatment. Ferroptosis happens mostly by accumulating iron and lipid peroxides in the cell. Recently, studies have revealed that ferroptosis has a key role in the tumor's progression. Especially, inducing ferroptosis in cells can inhibit the tumor cells' growth, leading to back warding tumorigenesis. Here, we outline the ferroptosis characteristics from its basic role in melanoma cancer and mention its possible applications in melanoma cancer treatment. Video Abstract.

Steroidal Saponins: Naturally Occurring Compounds as Inhibitors of the Hallmarks of Cancer

Cancer is a global health burden responsible for an exponentially growing number of incidences and mortalities, regardless of the significant advances in its treatment. The identification of the hallmarks of cancer is a major milestone in understanding the mechanisms that drive cancer initiation, development, and progression. In the past, the hallmarks of cancer have been targeted to effectively treat various types of cancers. These conventional cancer drugs have shown significant therapeutic efficacy but continue to impose unfavorable side effects on patients. Naturally derived compounds are being tested in the search for alternative anti-cancer drugs. Steroidal saponins are a group of naturally occurring compounds that primarily exist as secondary metabolites in plant species. Recent studies have suggested that steroidal saponins possess significant anti-cancer capabilities. This review aims to summarize the recent findings on steroidal saponins as inhibitors of the hallmarks of cancer and covers key studies published between the years 2014 and 2024. It is reported that steroidal saponins effectively inhibit the hallmarks of cancer, but poor bioavailability and insufficient preclinical studies limit their utilization.

Hyperforin Enhances Heme Oxygenase-1 Expression Triggering Lipid Peroxidation in BRAF-Mutated Melanoma Cells and Hampers the Expression of Pro-Metastatic Markers

Hyperforin (HPF) is an acylphloroglucinol compound found abundantly in Hypericum perforatum extract which exhibits antidepressant, anti-inflammatory, antimicrobial, and antitumor activities. Our recent study revealed a potent antimelanoma effect of HPF, which hinders melanoma cell proliferation, motility, colony formation, and induces apoptosis. Furthermore, we have identified glutathione peroxidase-4 (GPX-4), a key enzyme involved in cellular protection against iron-induced lipid peroxidation, as one of the molecular targets of HPF. Thus, in three BRAF-mutated melanoma cell lines, we investigated whether iron unbalance and lipid peroxidation may be a part of the molecular mechanisms underlying the antimelanoma activity of HPF. Initially, we focused on heme oxygenase-1 (HO-1), which catalyzes the heme group into CO, biliverdin, and free iron, and observed that HPF treatment triggered the expression of this inducible enzyme. In order to investigate the mechanism involved in HO-1 induction, we verified that HPF downregulates the BTB and CNC homology 1 (BACH-1) transcription factor, an inhibitor of the heme oxygenase 1 (HMOX-1) gene transcription. Remarkably, we observed a partial recovery of cell viability and an increase in the expression of the phosphorylated and active form of retinoblastoma protein when we suppressed the HMOX-1 gene using HMOX-1 siRNA while HPF was present. This suggests that the HO-1 pathway is involved in the cytostatic effect of HPF in melanoma cells. To explore whether lipid peroxidation is induced, we conducted cytofluorimetric analysis and observed a significant increase in the fluorescence of the BODIPY C-11 probe 48 h after HPF administration in all tested melanoma cell lines. To discover the mechanism by which HPF triggers lipid peroxidation, along with the induction of HO-1, we examined the expression of additional proteins associated with iron homeostasis and lipid peroxidation. After HPF administration, we confirmed the downregulation of GPX-4 and observed low expression levels of SLC7A11, a cystine transporter crucial for the glutathione production, and ferritin, able to sequester free iron. A decreased expression level of these proteins can sensitize cells to lipid peroxidation. On the other hand, HPF treatment resulted in increased expression levels of transferrin, which facilitates iron uptake, and LC3B proteins, a molecular marker of autophagy induction. Indeed, ferritin and GPX-4 have been reported to be digested during autophagy. Altogether, these findings suggest that HPF induced lipid peroxidation likely through iron overloading and decreasing the expression of proteins that protect cells from lipid peroxidation. Finally, we examined the expression levels of proteins associated with melanoma cell invasion and metastatic potential. We observed the decreased expression of CD133, octamer-4, tyrosine-kinase receptor AXL, urokinase plasminogen activator receptor, and metalloproteinase-2 following HPF treatment. These findings provide further support for our previous observations, demonstrating the inhibitory effects of HPF on cell motility and colony formation in soft agar, which are both metastasis-related processes in tumor cells.

Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

Abietic acid induces ferroptosis via the activation of the HO-1 pathway in bladder cancer cells

BACKGROUND

Bladder cancer (BC) is a common urological malignancy that still lacks effective treatments. Abietic acid (AA) is an abietane diterpene that possesses various biological activities, including antitumor activity. This study aimed at evaluating the effects of AA on BC cells.

MATERIALS AND METHODS

The 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to assess the effects of AA on the viability of BC cells. Annexin-V and FITC staining was used to assess cellular death. The type of cell death was determined by the administration of various specific cell death inhibitors. Commercial kits were used to measure the levels of reactive oxygen species (ROS), intracellular iron, malondialdehyde (MDA), and glutathione (GSH). Real-time polymerase chain reaction (RT-PCR) and western blot analysis were used to assay mRNA and protein levels, respectively. The role of glutathione peroxidase 4 (GPX4) in the antitumor effects of AA was evaluated using the forced expression of GPX4 in BC cells. The impact of HO-1 on the antitumor effects of AA was examined by gene silencing and pharmacological inhibition of the protein. Finally, the antitumor effects of AA were evaluated in xenograft models.

RESULTS

AA selectively inhibited the viability of BC cells but not normal cells. AA-induced ferroptosis in BC cells was evidenced by the upregulation of ROS, intracellular iron, and MDA. AA treatment led to the downregulation of GPX4 and the upregulation of HO-1 in BC cells. Forced expression of GPX4 or inhibition of HO-1 resulted in decreased ferroptosis triggered by AA in BC cells. AA also showed synergistic effects with various chemotherapeutic agents against BC and inhibited the growth of BC cells in vivo.

CONCLUSION

This study revealed AA-induced ferroptosis in BC cells both in vitro and in vivo. AA might be applied as a promising agent for the treatment of BC.

Phenolic furanochromene hydrazone derivatives: Synthesis, antioxidant activity, ferroptosis inhibition, DNA cleavage and DNA molecular docking studies

Twenty-four phenolic furanochromene hydrazone derivatives were designed and synthesized in order to evaluate structure-activity relationships in a series of antioxidant-related assays. The derivatives have varying substitution patterns on the phenol ring, with some compounds having one, two or three hydroxy groups, and others containing one hydroxy group in combination with methoxy, methyl, bromo, iodo and/or nitro groups. Antioxidant activity was determined using the DPPH free radical scavenging and CUPRAC assays. Compounds containing ortho-dihydroxy and para-dihydroxy patterns had the highest free radical scavenging activity, with IC50 values ranging from 5.0 to 28 μM. Similarly, derivatives with ortho-dihydroxy and para-dihydroxy patterns, together with a 4-hydroxy-3,5‑dimethoxy pattern, displayed strong copper (II) ion reducing capacity, using Trolox as a standard. Trolox equivalent antioxidant capacity (TEAC) coefficients for these derivatives ranged from 1.75 to 3.97. As further evidence of antioxidant potential, greater than half of the derivatives reversed erastin-induced ferroptosis in HaCaT cells. In addition, twenty-three of the derivatives were effective at cleaving supercoiled plasmid DNA in the presence of copper (II) ions at 1 mM, with the 3,4‑dihydroxy derivative showing cleavage to both the linear and open circular forms at 3.9 uM. The interaction of the phenolic furanochromene derivatives with DNA was confirmed by molecular docking studies, which revealed that all the derivatives bind favorably in the minor groove of DNA.

Ferroptosis in heart failure

With its complicated pathobiology and pathophysiology, heart failure (HF) remains an increasingly prevalent epidemic that threatens global human health. Ferroptosis is a form of regulated cell death characterized by the iron-dependent lethal accumulation of lipid peroxides in the membrane system and is different from other types of cell death such as apoptosis and necrosis. Mounting evidence supports the claim that ferroptosis is mainly regulated by several biological pathways including iron handling, redox homeostasis, and lipid metabolism. Recently, ferroptosis has been identified to play an important role in HF induced by different stimuli such as myocardial infarction, myocardial ischemia reperfusion, chemotherapy, and others. Thus, it is of great significance to deeply explore the role of ferroptosis in HF, which might be a prerequisite to precise drug targets and novel therapeutic strategies based on ferroptosis-related medicine. Here, we review current knowledge on the link between ferroptosis and HF, followed by critical perspectives on the development and progression of ferroptotic signals and cardiac remodeling in HF.

Gambogenic acid antagonizes the expression and effects of long non-coding RNA NEAT1 and triggers autophagy and ferroptosis in melanoma

In this study, we investigated the molecular mechanism underlying melanoma proliferation, with the aim to discover effective interventions which may markedly improve clinical prognosis. The results showed that gambogenic acid (GNA) could inhibit the proliferation of melanoma cells in vivo (C57BL/6 mice) and in vitro. Long non-coding RNA sequencing was used to identify the most significant long non-coding RNA, i.e., nuclear enriched abundant transcript 1 (NEAT1). NEAT1 was is up-regulated in melanoma, which was found to closely relate to cell proliferation. Melanoma cell lines either over-expressing NEAT1 or with NEAT1 knockdown was established through cloning experiments. A model of transplanted tumors was established to verify the inhibitory effect of GNA on the proliferation of melanoma cells in vitro and in vivo by downregulating NEAT1. Downregulation of NEAT1-induced ferroptosis and autophagy was demonstrated by detecting the effects of NEAT1 overexpressed and downregulated melanoma cell lines and melanoma transplantation model mice. Mechanistically, downregulation of NEAT1 can weaken the direct binding of Slc7a11, indirectly leading to inhibiting GPX-4 activity and subsequent ferroptosis, while, mediating the AMPK/mTOR signal axis-induced autophagy. The levels of Furthermore, NEAT1 decrease under the treatment of Gambogenic acid (GNA), a promising natural anticancer compound, while NEAT1 overexpression suppresses GNA inhibition on cell vitality and eliminates GNA-induced melanoma cell ferroptosis and autophagy.

Relevance of Ferroptosis to Cardiotoxicity Caused by Anthracyclines: Mechanisms to Target Treatments

Anthracyclines (ANTs) are a class of anticancer drugs widely used in oncology. However, the clinical application of ANTs is limited by their cardiotoxicity. The mechanisms underlying ANTs-induced cardiotoxicity (AIC) are complicated and involve oxidative stress, inflammation, topoisomerase 2β inhibition, pyroptosis, immunometabolism, autophagy, apoptosis, ferroptosis, etc. Ferroptosis is a new form of regulated cell death (RCD) proposed in 2012, characterized by iron-dependent accumulation of reactive oxygen species (ROS) and lipid peroxidation. An increasing number of studies have found that ferroptosis plays a vital role in the development of AIC. Therefore, we aimed to elaborate on ferroptosis in AIC, especially by doxorubicin (DOX). We first summarize the mechanisms of ferroptosis in terms of oxidation and anti-oxidation systems. Then, we discuss the mechanisms related to ferroptosis caused by DOX, particularly from the perspective of iron metabolism of cardiomyocytes. We also present our research on the prevention and treatment of AIC based on ferroptosis. Finally, we enumerate our views on the development of drugs targeting ferroptosis in this emerging field.

Study of Saponin Components after Biotransformation of Dioscorea nipponica by Endophytic Fungi C39

This study conducted the solid fermentation process of Dioscorea nipponica using endophytic fungi C39 to determine the changes in the diosgenin concentration. The results revealed that endophytic fungi C39 could effectively biotransform the saponin components in D. nipponica. Moreover, the maximum increase in the diosgenin concentration reached 62.67% in 15 days of solid fermentation. MTT assay results demonstrated that the inhibitory effects of the fermentation drugs on four types of cancer cells (liver cancer cells (HepG2), stomach cancer cells (BGC823), cervical cancer cells (HeLa), and lung cancer cells (A549)) were better than those of the crude drugs obtained from D. nipponica. The chemical composition of the samples obtained before and after the biotransformation of D. nipponica was analyzed by UPLC-Q-TOF-MS. A total of 32 compounds were identified, 21 of which have been reported in Dioscorea saponins and the ChemSpider database and 11 compounds were identified for the first time in D. nipponica. The biotransformation process was inferred based on the variation trend of saponins, which included transformation pathways pertaining to glycolytic metabolism, ring closure reaction, dehydrogenation, and carbonylation. The cumulative findings provide the basis for the rapid qualitative analysis of the saponin components of D. nipponica before and after biotransformation. The 11 metabolites obtained from biotransformation are potential active ingredients obtained from D. nipponica, which can be used to further identify pharmacodynamically active substances.