Artemisinin compounds sensitize cancer cells to ferroptosis by regulating iron homeostasis

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

Anticancer activity of an Artemisia annua L. hydroalcoholic extract on canine osteosarcoma cell lines

Since ancient times, Artemisia annua (A. annua) has been used as a medicinal plant in Traditional Chinese Medicine. In addition, recent studies have investigated the cytotoxic effects of A. annua extracts towards cancer cells. The leading aim of the present research is to evaluate the cytotoxic effects of an hydroalcoholic extract of A. annua on two canine osteosarcoma (OSA) cell lines, OSCA-8 and OSCA-40, focusing on the possible involvement of ferroptosis. The quantitative determination of artemisinin concentration in the extract, culture medium and OSA cells was carried out through the use of an instrumental analytical method based on liquid chromatography coupled with spectrophotometric detection and tandem mass spectrometry (LC-DAD-MS/MS). OSCA-8 and OSCA-40 were exposed to different dilutions of the extract for the EC₅₀ calculation then the uptake of artemisinin by the cells, the effects on the cell cycle, the intracellular iron level, the cellular morphology and the lipid oxidation state were evaluated. A concentration of artemisinin of 63.8 ± 3.4 μg/mL was detected in the extract. A dose-dependent cytotoxic effect was evidenced. In OSCA-40 alterations of the cell cycle and a significantly higher intracellular iron content were observed. In both cell lines the treatment with the extract was associated with lipid peroxidation and with the appearance of a "ballooning" phenotype suggesting the activation of ferroptosis. In conclusion the A. annua idroalcoholic extract utilized in this study showed anticancer activity on canine OSA cell lines that could be useful in treating drug resistant canine OSAs.

Corosolic acid sensitizes ferroptosis by upregulating HERPUD1 in liver cancer cells

Primary liver cancer is the third leading cause of cancer death in the world, and the lack of effective treatments is the main reason for the high mortality. Corosolic acid (CA) has been proved to have antitumor activity. In this study, we found that CA can sensitize liver cancer cells to ferroptosis, which is a regulated form of cell death characterized by iron-dependent lipid peroxides reaching lethal levels. Here, we revealed that CA can inhibit glutathione (GSH) synthesis via HERPUD1, decreasing the cellular GSH level and causing liver cancer cells to become more sensitive to ferroptosis. Mechanistically, further studies found that HERPUD1 reduced the ubiquitination of the GSS-associated E3 ubiquitin ligase MDM2, which promoted ubiquitination of GSS, thereby inhibiting GSH synthesis to increase ferroptosis susceptibility. Importantly, a mouse xenograft model also demonstrated that CA inhibits tumor growth via HERPUD1. Collectively, our findings suggesting that CA is a candidate component for the development of treatments against liver cancer.

Emerging role of ferroptosis in glioblastoma: Therapeutic opportunities and challenges

Glioblastoma (GBM) is the most common malignant craniocerebral tumor. The treatment of this cancer is difficult due to its high heterogeneity and immunosuppressive microenvironment. Ferroptosis is a newly found non-apoptotic regulatory cell death process that plays a vital role in a variety of brain diseases, including cerebral hemorrhage, neurodegenerative diseases, and primary or metastatic brain tumors. Recent studies have shown that targeting ferroptosis can be an effective strategy to overcome resistance to tumor therapy and immune escape mechanisms. This suggests that combining ferroptosis-based therapies with other treatments may be an effective strategy to improve the treatment of GBM. Here, we critically reviewed existing studies on the effect of ferroptosis on GBM therapies such as chemotherapy, radiotherapy, immunotherapy, and targeted therapy. In particular, this review discussed the potential of ferroptosis inducers to reverse drug resistance and enhance the sensitivity of conventional cancer therapy in combination with ferroptosis. Finally, we highlighted the therapeutic opportunities and challenges facing the clinical application of ferroptosis-based therapies in GBM. The data generated here provide new insights and directions for future research on the significance of ferroptosis-based therapies in GBM.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe²⁺, Ca²⁺, Zn²⁺, etc.) and anions (Cl^-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

Dihydroartemisinin remodels macrophage into an M1 phenotype via ferroptosis-mediated DNA damage

Lung cancer recruits tumor-associated macrophages (TAMs) massively, whose predominantly pro-tumor M2 phenotype leads to immunosuppression. Dihydroartemisinin (DHA) has been proven to remodel TAM into an anti-tumor M1 phenotype at certain concentrations in the present study, which was hypothesized to facilitate anti-lung cancer immunotherapy. However, how DHA remodels the TAM phenotype has not yet been uncovered. Our previous work revealed that DHA could trigger ferroptosis in lung cancer cells, which may also be observed in TAM thereupon. Sequentially, in the current study, DHA was found to remodel TAM into the M1 phenotype in vitro and in vivo. Simultaneously, DHA was observed to trigger ferroptosis in TAM and cause the DNA damage response and NF-κB activation. Conversely, the DHA-induced DNA damage response and NF-κB activation in TAM were attenuated after the inhibition of ferroptosis in TAM using an inhibitor of ferroptosis. Importantly, a ferroptosis inhibitor could also abolish the DHA-induced phenotypic remodeling of TAM toward the M1 phenotype. In a nutshell, this work demonstrates that DHA-triggered ferroptosis of TAM results in DNA damage, which could activate downstream NF-κB to remodel TAM into an M1 phenotype, providing a novel strategy for anti-lung cancer immunotherapy. This study offers a novel strategy and theoretical basis for the use of traditional Chinese medicine monomers to regulate the anti-tumor immune response, as well as a new therapeutic target for TAM phenotype remodeling.

Folate-modified erythrocyte membrane nanoparticles loaded with Fe3O4 and artemisinin enhance ferroptosis of tumors by low-intensity focused ultrasound

To overcome the challenges of the low efficiency of artemisinin (ART) in anticancer therapy due to its poor water solubility and poor bioavailability, we constructed folate (FA)-modified erythrocyte membrane (EM)-camouflaged poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) (PFH/ART@PLGA/Fe3O4-eFA). Specifically, the inner core of these NPs is mainly composed of phase-changeable perfluorohexane (PFH), magnetic Fe3O4 and ART. In vitro experiments showed that the prepared PFH/ART@PLGA/Fe3O4-eFA was readily taken up by 4T1 cancer cells. PFH/ART@PLGA/Fe3O4-eFA was exposed to low-intensity focused ultrasound (LIFU) irradiation to induce PFH phase transition and NPs collapse, which promoted the release of ART and Fe3O4. After LIFU irradiation, the proportion of dead 4T1 cells, the level of reactive oxygen species (ROS) and the concentration of intracellular Fe2+ ions in the PFH/ART@PLGA/Fe3O4-eFA group were much higher than those in the other group, indicating that the synergistic effect between the intracellular Fe2+ ions and the released ART played a critical role in tumor cell ferroptosis by enhancing ROS generation in vitro. We demonstrated that FA-modified EM NPs could enhance the targeting and accumulation of the NPs at the tumor site in vivo. After LIFU irradiation at 3 W/m2 for 7 min, tumor growth was completely suppressed through FA-modified EM NPs collapse and the release of ART and Fe3O4, which exerted synergistic effects in inducing tumor ferroptosis. Because of these characteristics, these NPs are considered as a promising approach for the delivery of drugs with poor water solubility for efficient cancer therapy.

Artesunate Inhibits the Cell Growth in Colorectal Cancer by Promoting ROS-Dependent Cell Senescence and Autophagy

Although artesunate has been reported to be a promising candidate for colorectal cancer (CRC) treatment, the underlying mechanisms and molecular targets of artesunate are yet to be explored. Here, we report that artesunate acts as a senescence and autophagy inducer to exert its inhibitory effect on CRC in a reactive oxygen species (ROS)-dependent manner. In SW480 and HCT116 cells, artesunate treatment led to mitochondrial dysfunction, drastically promoted mitochondrial ROS generation, and consequently inhibited cell proliferation by causing cell cycle arrest at G0/G1 phase as well as subsequent p16- and p21-mediated cell senescence. Senescent cells underwent endoplasmic reticulum stress (ERS), and the unfolded protein response (UPR) was activated via IRE1α signaling, with upregulated BIP, IRE1α, phosphorylated IRE1α (p-IRE1α), CHOP, and DR5. Further experiments revealed that autophagy was induced by artesunate treatment due to oxidative stress and ER stress. In contrast, N-Acetylcysteine (NAC, an ROS scavenger) and 3-Methyladenine (3-MA, an autophagy inhibitor) restored cell viability and attenuated autophagy in artesunate-treated cells. Furthermore, cellular free Ca²⁺ levels were increased and could be repressed by NAC, 3-MA, and GSK2350168 (an IRE1α inhibitor). In vivo, artesunate administration reduced the growth of CT26 cell-derived tumors in BALB/c mice. Ki67 and cyclin D1 expression was downregulated in tumor tissue, while p16, p21, p-IRE1α, and LC3B expression was upregulated. Taken together, artesunate induces senescence and autophagy to inhibit cell proliferation in colorectal cancer by promoting excessive ROS generation.

Ferroptosis in sepsis: The mechanism, the role and the therapeutic potential

Sepsis is a common critical illness in the Intensive care unit(ICU) and its management and treatment has always been a major challenge in critical care medicine. The dysregulated host response to infection, causing systemic multi-organ and multi-system damage is the main pathogenesis. Notably, intense stress during sepsis can lead to metabolic disturbances of ions, lipids and energy in the organism. Ferroptosis is an iron-dependent, non-apoptotic cell death distinguished by a disruption of iron metabolism and iron-dependent accumulation of lipid peroxides. Mounting researches have established that ferroptosis has an essential part in anti-inflammatory and sepsis, and drugs targeting ferroptosis-related molecules, such as ferroptosis inhibitors, are gradually proving their effectiveness in sepsis. This paper summarizes and reviews the pathogenesis of ferroptosis, its regulatory network, and its vital involvement in the initiation of sepsis and related organ damage, and finally discusses the possible target drugs provided by the above mechanisms, describes the dilemmas as well as the outlook, in the hope of finding more links between ferroptosis and sepsis and providing new perspectives for the future treatment of sepsis.

Ferroptosis-based nano delivery systems targeted therapy for colorectal cancer: Insights and future perspectives

There are limited options for patients who develop liver metastasis from colorectal cancer (CRC), the leading cause of cancer-related mortality worldwide. Emerging evidence has provided insights into iron deficiency and excess in CRC. Ferroptosis is an iron-dependent form of programmed cell death characterized by aberrant iron and lipid metabolism, which play crucial roles in tumorigenesis, tumor progression, and treatment options. A better understanding of the underlying molecular mechanism of ferroptosis has shed light on the current findings of ferroptosis-based nanodrug targeting strategies, such as driving ferroptosis in tumor cells and the tumor microenvironment, emerging combination therapy and against multidrug resistance. Furthermore, this review highlights the challenge and perspective of a ferroptosis-driven nanodrug delivery system for CRC-targeted therapy.

MicroRNA-147a Targets SLC40A1 to Induce Ferroptosis in Human Glioblastoma

Objective. Glioblastoma is one of the most common malignant tumors in the brain, and these glioblastoma patients have very poor prognosis. Ferroptosis is involved in the progression of various tumors, including the glioblastoma. This study aims to determine the involvement of microRNA (miR)-147a in regulating ferroptosis of glioblastoma in vitro. Methods. Human glioblastoma cell lines were transfected with the inhibitor, mimic and matched negative controls of miR-147a in the presence or absence of ferroptotic inducers. To knock down the endogenous solute carrier family 40 member 1 (SLC40A1), cells were transfected with the small interfering RNA against SLC40A1. In addition, cells with or without the miR-147a mimic treatment were also incubated with temozolomide (TMZ) to investigate whether miR-147a overexpression could sensitize human glioblastoma cells to TMZ chemotherapy in vitro. Results. We found that miR-147a level was decreased in human glioblastoma tissues and cell lines and that the miR-147a mimic significantly suppressed the growth of glioblastoma cells in vitro. In addition, miR-147a expression was elevated in human glioblastoma cells upon erastin or RSL3 stimulation. Treatment with the miR-147a mimic significantly induced ferroptosis of glioblastoma cells, and the ferroptotic inhibitors could block the miR-147a mimic-mediated tumor suppression in vitro. Conversely, the miR-147a inhibitor prevented erastin- or RSL3-induced ferroptosis and increased the viability of glioblastoma cells in vitro. Mechanistically, we determined that miR-147a directly bound to the 3 $\prime$ -untranslated region of SLC40A1 and inhibited SLC40A1-mediated iron export, thereby facilitating iron overload, lipid peroxidation, and ferroptosis. Furthermore, miR-147a mimic-treated human glioblastoma cells exhibited higher sensitivity to TMZ chemotherapy than those treated with the mimic control in vitro. Conclusion. We for the first time determine that miR-147a targets SLC40A1 to induce ferroptosis in human glioblastoma in vitro.

Puzzling Out Iron Complications in Cancer Drug Resistance

Iron metabolism are frequently disrupted in cancer. Patients with cancer are prone to anemia and receive transfusions frequently; the condition which results in iron overload, contributing to serious therapeutic complications. Iron is introduced as a carcinogen that may increase tumor growth. However, investigations regarding its impact on response to chemotherapy, particularly the induction of drug resistance are still limited. Here, iron contribution to cell signaling and various molecular mechanisms underlying iron-mediated drug resistance are described. A dual role of this vital element in cancer treatment is also addressed. On one hand, the need to administer iron chelators to surmount iron overload and improve the sensitivity of tumor cells to chemotherapy is discussed. On the other hand, the necessary application of iron as a therapeutic option by iron-oxide nanoparticles or ferroptosis inducers is explained. Authors hope that this paper can help unravel the clinical complications related to iron in cancer therapy.

Artemisinin relieves osteoarthritis by activating mitochondrial autophagy through reducing TNFSF11 expression and inhibiting PI3K/AKT/mTOR signaling in cartilage

Osteoarthritis (OA) is a widespread chronic degenerative joint disease characterized by the degeneration of articular cartilage or inflamed joints. Our findings indicated that treatment with artemisinin (AT) downregulates the protein levels of MMP3, MMP13, and ADAMTS5, which are cartilage degradation-related proteins in OA, and inhibits the expression of inflammatory factors in interleukin-1β (IL-1β)-stimulated chondrocytes. However, the mechanism of the role of AT in OA remains unclear. Here, we performed gene sequencing and bioinformatics analysis in control, OA, and OA + AT groups to demonstrate that several mRNA candidates were enriched in the PI3K/AKT/mTOR signaling pathway, and TNFSF11 was significantly downregulated after AT treatment. TNFSF11 was downregulated in the OA + AT group, whereas it was upregulated in rat OA tissues and OA chondrocytes. Therefore, we confirmed that TNFSF11 was the target gene of AT. In addition, our study revealed that AT relieved cartilage degradation and defection by activating mitochondrial autophagy via inhibiting the PI3K/AKT/mTOR signaling pathway in IL-1β-induced chondrocytes. Furthermore, an OA model was established in rats with medial meniscus destabilization. Injecting AT into the knee joints of OA rat alleviated surgical resection-induced cartilage destruction. Thus, these findings revealed that AT relieves OA by activating mitochondrial autophagy by reducing TNFSF11 expression and inhibiting PI3K/AKT/mTOR signaling.

Dihydroartemisinin Reduces Irradiation-Induced Mitophagy and Radioresistance in Lung Cancer A549 Cells via CIRBP Inhibition

Radiotherapy is a major therapeutic strategy for lung cancer, and radiation resistance (radioresistance) is an important cause of residual and recurring cancer after treatment. However, the mechanism of radioresistance remains unclear. Mitochondrial autophagy (mitophagy), an important selective autophagy, plays an important role in maintaining cell homeostasis and affects the response to therapy. Recent studies have shown that dihydroartemisinin (DHA), a derivative of artemisinin, can increase the sensitivity to treatment in multiple types of cancer, including lung cancer. The purpose of this study was to elucidate the function and molecular mechanisms of DHA-regulating mitophagy and DHA-reducing radioresistance in lung cancer A549 cells. We first constructed the radioresistant lung cancer A549 cells model (A549R) through fractional radiation, then elucidated the function and mechanism of DHA-regulating mitophagy to reduce the radioresistance of lung cancer by genomic, proteomic, and bioinformatic methods. The results showed that fractional radiation can significantly induce radioresistance and mitophagy in A549 cells, DHA can reduce mitophagy and radioresistance, and the inhibition of mitophagy can reduce radioresistance. Protein chip assay and bioinformatics analysis showed the following: Cold-Inducible RNA Binding Protein (CIRBP) might be a potential target of DHA-regulating mitophagy; CIRBP is highly expressed in A549R cells; the knockdown of CIRBP increases the effect of DHA, reduces mitophagy and radioresistance, and inhibits the mitophagy-related PINK1/Parkin pathway. In conclusion, we believe that DHA reduces radiation-induced mitophagy and radioresistance of lung cancer A549 cells via CIRBP inhibition.

Regulated necrosis, a proinflammatory cell death, potentially counteracts pathogenic infections

Since the discovery of cell apoptosis, other gene-regulated cell deaths are gradually appreciated, including pyroptosis, ferroptosis, and necroptosis. Necroptosis is, so far, one of the best-characterized regulated necrosis. In response to diverse stimuli (death receptor or toll-like receptor stimulation, pathogenic infection, or other factors), necroptosis is initiated and precisely regulated by the receptor-interacting protein kinase 3 (RIPK3) with the involvement of its partners (RIPK1, TRIF, DAI, or others), ultimately leading to the activation of its downstream substrate, mixed lineage kinase domain-like (MLKL). Necroptosis plays a significant role in the host's defense against pathogenic infections. Although much has been recognized regarding modulatory mechanisms of necroptosis during pathogenic infection, the exact role of necroptosis at different stages of infectious diseases is still being unveiled, e.g., how and when pathogens utilize or evade necroptosis to facilitate their invasion and how hosts manipulate necroptosis to counteract these detrimental effects brought by pathogenic infections and further eliminate the encroaching pathogens. In this review, we summarize and discuss the recent progress in the role of necroptosis during a series of viral, bacterial, and parasitic infections with zoonotic potentials, aiming to provide references and directions for the prevention and control of infectious diseases of both human and animals.

Ferroptosis turns 10: Emerging mechanisms, physiological functions, and therapeutic applications

Ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, was identified as a distinct phenomenon and named a decade ago. Ferroptosis has been implicated in a broad set of biological contexts, from development to aging, immunity, and cancer. This review describes key regulators of this form of cell death within a framework of metabolism, ROS biology, and iron biology. Key concepts and major unanswered questions in the ferroptosis field are highlighted. The next decade promises to yield further breakthroughs in the mechanisms governing ferroptosis and additional ways of harnessing ferroptosis for therapeutic benefit.

Ropivacaine has the potential to relieve PM2.5‑induced acute lung injury

Ropivacaine is a commonly used local anesthetic in the clinic due to its low toxicity to the cardiovascular system or central nervous system, good tolerance and high clearance rate. The present study intended to investigate the effect of ropivacaine on PM2.5-induced acute lung injury (ALI) and reveal the underlying mechanism. After ropivacaine exposure, cell viability, oxidative stress and inflammation in PM2.5-induced BEAS-2B cells were assessed by Cell Counting Kit-8 and DCFH-DA staining, corresponding commercial kits and ELISA, respectively. The effects of ropivacaine on the expression of MMP9 and MMP12 and the proteins related to NLRP3/Caspase-1 signaling were then determined by western blot and reverse transcription-quantitative PCR analyses. In addition, NLR family pyrin domain containing 3 (NLRP3) agonist monosodium urate (MSU) was used to treat BEAS-2B cells followed by ropivacaine treatment and the effects on the above-mentioned cellular behaviors were determined again. The results indicated that the viability of BEAS-2B cells was decreased after PM2.5 induction, accompanied by aggravated oxidative stress and inflammation. However, ropivacaine alleviated oxidative stress and inflammation in PM2.5-induced BEAS-2B cells in a dose-dependent manner. Ropivacaine was also indicated to decrease the expression levels of NLRP3/Caspase-1 signaling-related proteins in PM2.5-induced BEAS-2B cells. Furthermore, cell viability was decreased, while oxidative stress and inflammatory response were aggravated, in PM2.5-induced BEAS-2B cells treated with MSU. In summary, the present results implied that ropivacaine exerted protective effects on PM2.5-induced ALI, and this effect may be related to NLRP3/Caspase-1 signaling.

Synthesis of Thiophene/Furan-Artemisinin Hybrid Molecules

Natural products with semi-synthetic molecules displays higher biological activities, and creates new biological properties for the treatment of diseases. Although, natural products like artemisinin have been used as a traditional medicine over thousands of years, structure and biological properties of many natural products were investigated in the 20th century.  Design and synthesis of new biologically active compounds including natural products have very critical roles to find novel drug candidates. Herein, novel thiophene/furan bridge artemisinin derivatives were synthesized by starting from artemisinin.  Firstly, benzothiophene derivatives are synthesized, then Stergich esterification reactions give the new artemisinin hybrid molecules with moderate to high yields.

Regulatory pathways and drugs associated with ferroptosis in tumors

Ferroptosis is a type of cell death that depends on iron and reactive oxygen species (ROS). The accumulation of iron and lipid peroxidation primarily initiates oxidative membrane damage during ferroptosis. The core molecular mechanism of ferroptosis includes the regulation of oxidation and the balance between damage and antioxidant defense. Tumor cells usually contain a large amount of H₂O₂, and ferrous/iron ions will react with excessive H₂O₂ in cells to produce hydroxyl radicals and induce ferroptosis in tumor cells. Here, we reviewed the latest studies on the regulation of ferroptosis in tumor cells and introduced the tumor-related signaling pathways of ferroptosis. We paid particular attention to the role of noncoding RNA, nanomaterials, the role of drugs, and targeted treatment using ferroptosis drugs for mediating the ferroptosis process in tumor cells. Finally, we discussed the currently unresolved problems and future research directions for ferroptosis in tumor cells and the prospects of this emerging field. Therefore, we have attempted to provide a reference for further understanding of the pathogenesis of ferroptosis and proposed new targets for cancer treatment.

Nutritional and Metabolic Control of Ferroptosis

Ferroptosis is a type of regulated cell death characterized by an excessive lipid peroxidation of cellular membranes caused by the disruption of the antioxidant defense system and/or an imbalanced cellular metabolism. Ferroptosis differentiates from other forms of regulated cell death in that several metabolic pathways and nutritional aspects, including endogenous antioxidants (such as coenzyme Q₁₀, vitamin E, and di/tetrahydrobiopterin), iron handling, energy sensing, selenium utilization, amino acids, and fatty acids, directly regulate the cells' sensitivity to lipid peroxidation and ferroptosis. As hallmarks of ferroptosis have been documented in a variety of diseases, including neurodegeneration, acute organ injury, and therapy-resistant tumors, the modulation of ferroptosis using pharmacological tools or by metabolic reprogramming holds great potential for the treatment of ferroptosis-associated diseases and cancer therapy. Hence, this review focuses on the regulation of ferroptosis by metabolic and nutritional cues and discusses the potential of nutritional interventions for therapy by targeting ferroptosis. Expected final online publication date for the Annual Review of Nutrition, Volume 42 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Ferroptosis-Driven Nanotherapeutics to Reverse Drug Resistance in Tumor Microenvironment

Ferroptosis, characterized by iron-dependent lipid reactive oxygen species (ROS) accumulation, is non-apoptotic programmed cell death highly relevant to tumor development. It was found to manipulate oncogenes and resistant mutations of cancer cells via lipid metabolism pathways converging on phospholipid glutathione peroxidase (GPX4) that squanders lipid peroxides (L-OOH) to block the iron-mediated reactions of peroxides, thus rendering resistant cancer cells vulnerable to ferroptotic cell death. By accumulating ROS and lipid peroxidation (LPO) products to lethal levels in tumor microenvironment (TME), ferroptosis-driven nanotherapeutics show a superior ability of eradicating aggressive malignancies than traditional therapeutic modalities, especially for the drug-resistant tumors with high metastasis tendency. Moreover, Fenton reaction, inhibition of GPX-4, and exogenous regulation of LPO are three major therapeutic strategies to induce ferroptosis in cancer cells, which were generally applied in ferroptosis-driven nanotherapeutics. In this review, we elaborate current trends of ferroptosis-driven nanotherapeutics to reverse drug resistance of tumors in anticancer fields at the intersection of cancer biology, materials science, and chemistry. Finally, their challenges and perspectives toward feasible translational studies are spotlighted, which would ignite the hope of anti-resistant cancer treatment.

MicroRNA-4735-3p Facilitates Ferroptosis in Clear Cell Renal Cell Carcinoma by Targeting SLC40A1

Objective. Clear cell renal cell carcinoma (ccRCC) is the major histopathological subtype of renal cancer, and ferroptosis is implicated in the pathogenesis of ccRCC. The present study was aimed at investigating the role and underlying mechanisms of microRNA-4735-3p (miR-4735-3p) in ccRCC. Methods. Human ccRCC cell lines were transfected with the miR-4735-3p mimic or inhibitor to manipulate the expression of miR-4735-3p. Cell proliferation, colony formation, cell migration, cell invasion, cell death, oxidative stress, lipid peroxidation, and iron metabolism were determined. To validate the necessity of solute carrier family 40 member 1 (SLC40A1), human ccRCC cell lines were overexpressed with SLC40A1 using adenoviral vectors. Results. miR-4735-3p expression was reduced in human ccRCC tissues and cell lines but elevated upon ferroptotic stimulation. The miR-4735-3p mimic increased, while the miR-4735-3p inhibitor decreased oxidative stress, lipid peroxidation, iron overload, and ferroptosis of human ccRCC cell lines. Mechanistic studies identified SLC40A1 as a direct target of miR-4735-3p, and SLC40A1 overexpression significantly attenuated iron overload and ferroptosis in the miR-4735-3p mimic-treated human ccRCC cell lines. Conclusion. miR-4735-3p facilitates ferroptosis and tumor suppression in ccRCC by targeting SLC40A1.

Ethyl carbamate triggers ferroptosis in liver through inhibiting GSH synthesis and suppressing Nrf2 activation

Humans are inevitably exposed to ethyl carbamate (EC) via consumption of fermented food and beverages. EC, known as an environmental toxin, can cause oxidative stress-mediated severe toxicity, but the underlying mechanisms remain unveiled. Ferroptosis is a newly identified ROS-mediated non-apoptotic cell death characterized by iron accumulation and excessive lipid oxidation. In this study, we first found that EC triggered ferroptosis in liver cells by detection of decreased cell viability, GSH, GPX4 and Ferritin levels, as well as increased iron and MDA contents. Ferroptosis inhibitor ferrostatin-1 (Fer-1) pretreatment rescued ferroptotic damage, indicating that ferroptosis was critical for EC-caused cell death. Furthermore, GSH synthesis precursor N-acetylcysteine displayed significant anti-ferroptotic properties and we suggested that GSH depletion might be the main cause of ferroptosis under EC exposure. EC-triggered GSH depletion mainly depended on suppressed GSH synthesis via inhibition of SLC7A11 and GCLC expressions. Notably, EC blocked Nrf2 activation by repression of phosphorylation modification and nuclear translocation, which further resulted in ferroptosis occurrence. We also observed EC-induced liver dysfunction and inflammation, accompanied with oxidative stress, ferroptosis and downregulated Nrf2 signaling in Balb/c mice, which could be effectively reversed by Fer-1 and tBHQ pretreatment. Together, our study indicated that ferroptosis is a new mechanism for EC-caused toxicity, which was attributed to Nrf2 inactivation and GSH depletion.

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Ethyl carbamate (EC) caused ferroptosis in L02 cells and liver tissues.

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GSH depletion was critical for EC-induced ferroptotic cell death.

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EC exposure blocked GSH synthesis-related pathways.

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Inactivation of Nrf2 signaling was involved in EC-triggered ferroptosis.

HO-1 Contributes to Luteolin-Triggered Ferroptosis in Clear Cell Renal Cell Carcinoma via Increasing the Labile Iron Pool and Promoting Lipid Peroxidation

Ferroptosis, a novel form of regulated cell death characterized by disrupted iron metabolism and the accumulation of lipid peroxides, has exhibited enormous potential in the therapy of cancer particularly clear cell renal cell carcinoma (ccRCC). Luteolin (Lut), a natural flavonoid widely existing in various fruits and vegetables, has been proven to exert potent anticancer activity in vitro and in vivo. However, previous studies on the anticancer mechanism of Lut have been shown in apoptosis but not ferroptosis. In the present study, we identified that Lut substantially inhibited the survival of ccRCC in vitro and in vivo, and this phenomenon was accompanied by excessively increased intracellular Fe2+ and abnormal depletion of GSH. In addition, Lut induced the imbalance of mitochondrial membrane potential, classical morphological alterations of mitochondrial ferroptosis, generation of ROS, and occurrence of lipid peroxidation in an iron-dependent manner in ccRCC cells. However, these alterations induced by Lut could be reversed to some extent by the iron ion chelator deferiprone or the ferroptosis inhibitor ferrostatin-1, indicating that ccRCC cells treated with Lut underwent ferroptosis. Mechanistically, molecular docking further established that Lut probably promoted the heme degradation and accumulation of labile iron pool (LIP) by excessively upregulating the HO-1 expression, which led to the Fenton reaction, GSH depletion, and lipid peroxidation in ccRCC, whereas blocking this signaling pathway evidently rescued the Lut-induced cell death of ccRCC by inhibiting ferroptosis. Altogether, the current study shows that the natural compound monomer Lut exerted anticancer efficacy by excessively upregulating HO-1 expression and activating LIP to trigger ferroptosis in ccRCC and could be a promising and potent drug candidate for ccRCC treatment.

Ferroptosis in hematological malignancies and its potential network with abnormal tumor metabolism

Ferroptosis, a new type of regulated cell death, displays characteristics that transparently differ from apoptosis, autophagy and necroptosis. There is growing appreciation that targeting ferroptosis is potentially a novel strategy in anti-tumor therapy, especially for invasive malignancies demonstrating resistance to chemotherapy. Almost all types of cancer cells depend on abnormal metabolic activities to participate in vicious progression, giving the possibility to interfere with underlying metabolic preferences and compromise malignant cells by inducing ferroptosis. In this perspective, we give an overview of potential interactions between ferroptosis and abnormal tumor metabolism, with special focus on systematic researches in hematological malignancies.

Non-apoptotic cell death-based cancer therapy: Molecular mechanism, pharmacological modulators, and nanomedicine

As an emerging cancer therapeutic target, non-apoptotic cell death such as ferroptosis, necroptosis and pyroptosis, etc., has revealed significant potential in cancer treatment for bypassing apoptosis to enhance the undermined therapeutic efficacy triggered by apoptosis resistance. A variety of anticancer drugs, synthesized compounds and natural products have been proven recently to induce non-apoptotic cell death and exhibit excellent anti-tumor effects. Moreover, the convergence of nanotechnology with functional materials and biomedicine science has provided tremendous opportunities to construct non-apoptotic cell death-based nanomedicine for innovative cancer therapy. Nanocarriers are not only employed in targeted delivery of non-apoptotic inducers, but also used as therapeutic components to induce non-apoptotic cell death to achieve efficient tumor treatment. This review first introduces the main characteristics, the mechanism and various pharmacological modulators of different non-apoptotic cell death forms, including ferroptosis, necroptosis, pyroptosis, autophagy, paraptosis, lysosomal-dependent cell death, and oncosis. Second, we comprehensively review the latest progresses of nanomedicine that induces various forms of non-apoptotic cell death and focus on the nanomedicine targeting different pathways and components. Furthermore, the combination therapies of non-apoptotic cell death with photothermal therapy, photodynamic therapy, immunotherapy and other modalities are summarized. Finally, the challenges and future perspectives in this regard are also discussed.

Nobiletin Induces Ferroptosis in Human Skin Melanoma Cells Through the GSK3β-Mediated Keap1/Nrf2/HO-1 Signalling Pathway

Melanoma is an aggressive malignant skin tumour with an increasing global incidence. However, current treatments have limitations owing to the acquired tumour drug resistance. Ferroptosis is a recently discovered form of programmed cell death characterised by iron accumulation and lipid peroxidation and plays a critical role in tumour growth inhibition. Recently, ferroptosis inducers have been regarded as a promising therapeutic strategy to overcome apoptosis resistance in tumour cells. In this study, we reported that nobiletin, a natural product isolated from citrus peel, and exhibited antitumour activity by inducing ferroptosis in melanoma cells. Subsequently, we further explored the potential mechanism of nobiletin-induced ferroptosis, and found that the expression level of glycogen synthase kinase 3β (GSK3β) in the skin tissue of patients with melanoma was significantly reduced compared to that in the skin of normal tissue. Additionally, nobiletin increased GSK3β expression in melanoma cells. Moreover, the level of Kelch-like Ech-associated protein-1 (Keap1) was increased, while the level of nuclear factor erythroid 2-related factor 2 (Nrf2), and haem oxygenase-1 (HO-1) was decreased in nobiletin-treated melanoma cells, suggesting that the antioxidant defence system was downregulated. Furthermore, knockdown of GSK3β significantly reduced nobiletin-induced ferroptosis and upregulated the Keap1/Nrf2/HO-1 signalling pathway, while the opposite was observed in cells overexpressing GSK3β. In addition, molecular docking assay results indicated that nobiletin showed strong binding affinities for GSK3β, Keap1, Nrf2, and HO-1. Taken together, our results demonstrated that nobiletin could induce ferroptosis by regulating the GSK3β-mediated Keap1/Nrf2/HO-1 signalling pathway in human melanoma cells. Hence, nobiletin stands as a promising drug candidate for melanoma treatment with development prospects.

Cell-Specific Metabolic Reprogramming of Tumors for Bioactivatable Ferroptosis Therapy

Ferroptosis is a nonapoptotic iron-dependent cell death pathway with a significant clinical potential, but its translation is impeded by lack of tumor-specific ferroptosis regulators and aberrant tumor iron metabolism. Herein, we report a combinational strategy based on clinically tested constituents to selectively induce ferroptosis in metabolically reprogrammed tumor cells through cooperative GPX4-inhibition and ferritinophagy-enabled Fe²⁺ reinforcement. Azido groups were first introduced on tumor cells using biocompatible long-circulating self-assemblies based on polyethylene glycol-disulfide-N-azidoacetyl-d-mannosamine via metabolic glycoengineering. The azido-expressing tumor cells could specifically react with dibenzocyclooctyne-modified disulfide-bridged nanoassemblies via bioorthogonal click reactions, where the nanoassemblies were loaded with ferroptosis inducer RSL3 and ferritinophagy initiator dihydroartemisinin (DHA) and could release them in a bioresponsive manner. DHA-initiated ferritinophagy could degrade intracellular ferritin to liberate stored iron species and cooperate with the RSL3-mediated GPX4-inhibition for enhanced ferroptosis therapy. This tumor-specific ferroptosis induction strategy provides a generally applicable therapy with enhanced translatability, especially for tumors lacking targetable endogenous receptors.

Scutellaria barbata Inhibits Hepatocellular Carcinoma Tumorigenicity by Inducing Ferroptosis of Hepatocellular Carcinoma Cells

Ferroptosis is caused by accumulation of iron-dependent lipid peroxidation, which is characterized by reduction in cell volume and increase in mitochondrial membrane density. Studies have shown that ferroptosis contributes to the development and progression of numerous major diseases, including hepatocellular carcinoma (HCC). As a unique biomedical resource, Traditional Chinese Medicine (TCM) has been widely used in the treatment of HCC. In this present study, Scutellaria barbata was used to treat HCC cells in vitro, and the results revealed that S. barbata suppressed HCC cell growth through inducing ferroptosis. Next, the exploration of the molecular mechanism on how S. barbata induced ferroptosis in HCC cells suggested that S. barbata may induce ferroptosis by promoting iron perioxidation and lipid ROS metabolism. Finally, S. barbata also inhibited HCC tumorigenicity in vivo by inducing ferroptosis of HCC cells. These results provided theoretical basis for explaining the mechanism of TCM treatment for HCC and offered therapeutic opportunities for HCC patients.

The Potential Mechanisms by which Artemisinin and Its Derivatives Induce Ferroptosis in the Treatment of Cancer

Artemisinin (ART) is a bioactive molecule derived from the Chinese medicinal plant Artemisia annua (Asteraceae). ART and artemisinin derivatives (ARTs) have been effectively used for antimalaria treatment. The structure of ART is composed of a sesquiterpene lactone, including a peroxide internal bridge that is essential for its activity. In addition to their well-known antimalarial effects, ARTs have been shown recently to resist a wide range of tumors. The antineoplastic mechanisms of ART mainly include cell cycle inhibition, inhibition of tumor angiogenesis, DNA damage, and ferroptosis. In particular, ferroptosis is a novel nonapoptotic type of programmed cell death. However, the antitumor mechanisms of ARTs by regulating ferroptosis remain unclear. Through this review, we focus on the potential antitumor function of ARTs by acting on ferroptosis, including the regulation of iron metabolism, generation of reactive oxygen species (ROS), and activation of endoplasmic reticulum stress (ERS). This article systematically reviews the recent progress in ferroptosis research and provides a basis for ARTs as an anticancer drug in clinical practice.

m6A methylation is required for dihydroartemisinin to alleviate liver fibrosis by inducing ferroptosis in hepatic stellate cells

Activation of hepatic stellate cells (HSCs) is a central event in the development of liver fibrosis, and the elimination of activated HSCs is considered to be an effective anti-fibrotic strategy. Here, we report that dihydroartemisinin (DHA) prevented the activation of HSCs via ferroptosis pathway. Importantly, DHA treatment increased the level of autophagy in HSCs. The inhibition of autophagy by 3-MA dramatically abolished the DHA-induced ferroptosis in HSCs. Mechanistically, the up-regulated m6A modification is essential for the activation of autophagy by DHA through the reduction of fat mass and obesity-associated gene (FTO). Down-regulation of m6A modification by FTO overexpression could impair autophagy and the classical ferroptotic events. Interestingly, the m6A modification of BECN1 mRNA was evidently up-regulated compared with other autophagy-related genes. More importantly, YTHDF1 was identified as a key m6A reader protein for BECN1 mRNA stability, and knockdown of YTHDF1 could prevent DHA-induced HSC ferroptosis. Noteworthy, YTH domain was essential for YTHDF1 to prolong the half-life of BECN1 mRNA in DHA-induced HSC ferroptosis. In mice, DHA treatment alleviated liver fibrosis by triggering HSC ferroptosis. HSC-specific inhibition of m6A modification and autophagy could impair DHA-induced HSC ferroptosis in murine liver fibrosis. Overall, these results provided novel implications to reveal the molecular mechanism of DHA-induced ferroptosis, by which pointed to m6A modification-dependent ferroptosis as a potential target for the treatment of liver fibrosis.

Insights Into Ferroptosis, a Novel Target for the Therapy of Cancer

Ferroptosis is a new form of programmed cell death (PCD) characterized by an excess iron accumulation and subsequent unbalanced redox states. Ferroptosis is different from the already reported PCD and has unique morphological features and biochemical processes. Ferroptosis was first elaborated by Brent R. Stockwell’s lab in 2012, in which small molecules erastin and RSL-3 induce PCD in Ras mutant cell lines. Ferroptosis involves various physiological processes and occurrence of disease and especially shows strong potential in cancer treatment. Development of small molecule compounds based on Stockwell’s research was found to kill cancer cells, and some FDA-approved drugs were discovered to result in ferroptosis of cancer cells. Radiotherapy and checkpoint therapy have been widely used as a treatment for many types of cancer. Recently, some papers have reported that chemotherapy, radiotherapy, and checkpoint therapy induce ferroptosis of cancer cells, which provides new strategies for cancer treatment. Nevertheless, the limitless proliferation of tumor cells and the lack of cell death mechanisms are important reasons for drug resistance for tumor therapy. Therefore, we reviewed the molecular mechanism of ferroptosis and sensitivity to ferroptosis of different cancer cells and tumor treatment strategy.

Autophagy and cancer treatment: four functional forms of autophagy and their therapeutic applications

Cancer is the leading cause of death worldwide. Drugs play a pivotal role in cancer treatment, but the complex biological processes of cancer cells seriously limit the efficacy of various anticancer drugs. Autophagy, a self-degradative system that maintains cellular homeostasis, universally operates under normal and stress conditions in cancer cells. The roles of autophagy in cancer treatment are still controversial because both stimulation and inhibition of autophagy have been reported to enhance the effects of anticancer drugs. Thus, the important question arises as to whether we should try to strengthen or suppress autophagy during cancer therapy. Currently, autophagy can be divided into four main forms according to its different functions during cancer treatment: cytoprotective (cell survival), cytotoxic (cell death), cytostatic (growth arrest), and nonprotective (no contribution to cell death or survival). In addition, various cell death modes, such as apoptosis, necrosis, ferroptosis, senescence, and mitotic catastrophe, all contribute to the anticancer effects of drugs. The interaction between autophagy and these cell death modes is complex and can lead to anticancer drugs having different or even completely opposite effects on treatment. Therefore, it is important to understand the underlying contexts in which autophagy inhibition or activation will be beneficial or detrimental. That is, appropriate therapeutic strategies should be adopted in light of the different functions of autophagy. This review provides an overview of recent insights into the evolving relationship between autophagy and cancer treatment.

Artemisinin-Type Drugs in Tumor Cell Death: Mechanisms, Combination Treatment with Biologics and Nanoparticle Delivery

Artemisinin, the most famous anti-malaria drug initially extracted from Artemisia annua L., also exhibits anti-tumor properties in vivo and in vitro. To improve its solubility and bioavailability, multiple derivatives have been synthesized. However, to reveal the anti-tumor mechanism and improve the efficacy of these artemisinin-type drugs, studies have been conducted in recent years. In this review, we first provide an overview of the effect of artemisinin-type drugs on the regulated cell death pathways, which may uncover novel therapeutic approaches. Then, to overcome the shortcomings of artemisinin-type drugs, we summarize the recent advances in two different therapeutic approaches, namely the combination therapy with biologics influencing regulated cell death, and the use of nanocarriers as drug delivery systems. For the former approach, we discuss the superiority of combination treatments compared to monotherapy in tumor cells based on their effects on regulated cell death. For the latter approach, we give a systematic overview of nanocarrier design principles used to deliver artemisinin-type drugs, including inorganic-based nanoparticles, liposomes, micelles, polymer-based nanoparticles, carbon-based nanoparticles, nanostructured lipid carriers and niosomes. Both approaches have yielded promising findings in vitro and in vivo, providing a strong scientific basis for further study and upcoming clinical trials.

Ferroptosis in cancer and cancer immunotherapy

The hallmark of tumorigenesis is the successful circumvention of cell death regulation for achieving unlimited replication and immortality. Ferroptosis is a newly identified type of cell death dependent on lipid peroxidation which differs from classical programmed cell death in terms of morphology, physiology and biochemistry. The broad spectrum of injury and tumor tolerance are the main reasons for radiotherapy and chemotherapy failure. The effective rate of tumor immunotherapy as a new treatment method is less than 30%. Ferroptosis can be seen in radiotherapy, chemotherapy, and tumor immunotherapy; therefore, ferroptosis activation may be a potential strategy to overcome the drug resistance mechanism of traditional cancer treatments. In this review, the characteristics and causes of cell death by lipid peroxidation in ferroptosis are briefly described. In addition, the three metabolic regulations of ferroptosis and its crosstalk with classical signaling pathways are summarized. Collectively, these findings suggest the vital role of ferroptosis in immunotherapy based on the interaction of ferroptosis with tumor immunotherapy, chemotherapy and radiotherapy, thus, indicating the remarkable potential of ferroptosis in cancer treatment.

Dihydroartemisinin and Artesunate Inhibit Aerobic Glycolysis via Suppressing c-Myc Signaling in non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) cells exhibit aberrant metabolism characterized by high glycolysis even in the presence of abundant oxygen. Inhibition of aerobic glycolysis remains challenging when identifying potential cancer-specific inhibitors while maintaining or even boosting the anti-cancer immunity. Artemisinin derivatives DHA and AS have shown excellent anti-tumor and immunoenhancing roles in numerous malignancies, but the molecular mechanism of DHA and AS in regulating cancer glucose metabolism is largely unknown. In this study, we proved that DHA and AS inhibit NSCLC growth via prohibiting cancer cell aerobic glycolysis through ERK/c-Myc pathway. First, we proved that DHA and AS have comparable anti-cancer growth roles in both NSCLC cell lines and mouse Lewis Lung Cancer model. Then, our data clearly showed that DHA and AS dose- and time-dependently reduce the uptake of glucose, the production of ATP, and the secretion of lactate, the expression of glucose transporter GLUT1 and two key glycolysis-related enzymes hexokinase and lactate dehydrogenase, as well as the level of c-Myc. Finally, we generated c-Myc^high stable-expressing NSCLC cell line and treated it with DHA or AS, respectively. Our data clearly showed that c-Myc overexpression can partially reverse the glycolysis-repressing role of DHA and AS which strongly supported our proposal that AS and DHA suppress aerobic glycolysis in a c-Myc-dependent manner in NSCLC cells. This study extends our knowledge of artemisinin derivatives in regulating tumor glucose metabolism and provides potential strategy in the therapy of lung cancer.

Ferroptosis triggered by dihydroartemisinin facilitates chlorin e6 induced photodynamic therapy by inhibiting GPX4 and enhancing ROS

Photodynamic therapy (PDT) is noninvasive, low toxicity, and photo-selective, but may be resisted by malignant cells. A previous study found chlorin e6 (Ce6) mediated PDT showed drug resistance in lung cancer cells (LLC), which may be associated with PDT-induced DNA damage response (DDR). DDR may up-regulate glutathione peroxidase 4 (GPX4), which in turn degrade ROS induced by PDT. However, dihydroartemisinin (DHA) was found to down-regulate GPX4. Accordingly, the DHA was hypothesized to improve the resistance to PDT. The present work explores the mechanism of Ce6 mediated drug resistance and reveals whether DHA can enhance the efficacy of PDT by suppressing GPX4. The in vitro experiments found Ce6 treatment did not inhibit the viability of LLC within 6 hr without inducing significant apoptosis, suggesting LLC were resistant to PDT. Further investigation demonstrated PDT could damage DNA and up-regulate GPX4, thus degrading the generated ROS. DHA effectively inhibited the viability of LLC and induced apoptosis. Importantly, DHA displayed a prominent inhibitory effect on the GPX4 expression and thereby triggered ferroptosis. Combining DHA with Ce6 for treatment of LLC resulted in the suppressed GPX4 and elevated ROS. Finally, the findings showed DHA combined with Ce6 exhibited superb anti-lung cancer efficacy. In summary, Ce6 PDT damages DNA, up-regulates GPX4 to degrade ROS, thereby inducing drug resistance. Down-regulation of GPX4 by DHA-triggered ferroptosis significantly enhances the efficacy of PDT. This study provides an outstanding theoretical basis for the regulation of the intratumoral redox system and improving PDT efficacy against lung cancer by herbal monomer DHA.

Systematic review on the application of machine learning to quantitative structure-activity relationship modeling against Plasmodium falciparum

Malaria accounts for over two million deaths globally. To flatten this curve, there is a need to develop new and high potent drugs against Plasmodium falciparum. Some major challenges include the dearth of suitable animal models for anti-P. falciparum assays, resistance to first-line drugs, lack of vaccines and the complex life cycle of Plasmodium. Gladly, newer approaches to antimalarial drug discovery have emerged due to the release of large datasets by pharmaceutical companies. This review provides insights into these new approaches to drug discovery covering different machine learning tools, which enhance the development of new compounds. It provides a systematic review on the use and prospects of machine learning in predicting, classifying and clustering IC₅₀ values of bioactive compounds against P. falciparum. The authors identified many machine learning tools yet to be applied for this purpose. However, Random Forest and Support Vector Machines have been extensively applied though on a limited dataset of compounds.

Metabolic regulation of ferroptosis in the tumor microenvironment

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death triggered by impaired redox and antioxidant machinery and propagated by the accumulation of toxic lipid peroxides. A compendium of experimental studies suggest that ferroptosis is tumor-suppressive. Sensitivity or resistance to ferroptosis can be regulated by cell-autonomous and non-cell-autonomous metabolic mechanisms. This includes a role for ferroptosis that extends beyond the tumor cells themselves, mediated by components of the tumor microenvironment, including T cells and other immune cells. Herein, we review the intrinsic and extrinsic factors that promote the sensitivity of cancer cells to ferroptosis and conclude by describing approaches to harness the full utility of ferroptotic agents as therapeutic options for cancer therapy.

Repurposing Artemisinin and its Derivatives as Anticancer Drugs: A Chance or Challenge?

Cancer has become a global health problem, accounting for one out of six deaths. Despite the recent advances in cancer therapy, there is still an ever-growing need for readily accessible new therapies. The process of drug discovery and development is arduous and takes many years, and while it is ongoing, the time for the current lead compounds to reach clinical trial phase is very long. Drug repurposing has recently gained significant attention as it expedites the process of discovering new entities for anticancer therapy. One such potential candidate is the antimalarial drug, artemisinin that has shown anticancer activities in vitro and in vivo. In this review, major molecular and cellular mechanisms underlying the anticancer effect of artemisinin and its derivatives are summarised. Furthermore, major mechanisms of action and some key signaling pathways of this group of compounds have been reviewed to explore potential targets that contribute to the proliferation and metastasis of tumor cells. Despite its established profile in malaria treatment, pharmacokinetic properties, anticancer potency, and current formulations that hinder the clinical translation of artemisinin as an anticancer agent, have been discussed. Finally, potential solutions or new strategies are identified to overcome the bottlenecks in repurposing artemisinin-type compounds as anticancer drugs.

Emerging Mechanisms and Disease Implications of Ferroptosis: Potential Applications of Natural Products

Ferroptosis, a newly discovered form of regulatory cell death (RCD), has been demonstrated to be distinct from other types of RCD, such as apoptosis, necroptosis, and autophagy. Ferroptosis is characterized by iron-dependent lipid peroxidation and oxidative perturbation, and is inhibited by iron chelators and lipophilic antioxidants. This process is regulated by specific pathways and is implicated in diverse biological contexts, mainly including iron homeostasis, lipid metabolism, and glutathione metabolism. A large body of evidence suggests that ferroptosis is interrelated with various physiological and pathological processes, including tumor progression (neuro)degenerative diseases, and hepatic and renal failure. There is an urgent need for the discovery of novel effective ferroptosis-modulating compounds, even though some experimental reagents and approved clinical drugs have been well documented to have anti- or pro-ferroptotic properties. This review outlines recent advances in molecular mechanisms of the ferroptotic death process and discusses its multiple roles in diverse pathophysiological contexts. Furthermore, we summarize chemical compounds and natural products, that act as inducers or inhibitors of ferroptosis in the prevention and treatment of various diseases. Herein, it is particularly highlighted that natural products show promising prospects in ferroptosis-associated (adjuvant) therapy with unique advantages of having multiple components, multiple biotargets and slight side effects.

MicroRNA-1287-5p promotes ferroptosis of osteosarcoma cells through inhibiting GPX4

Osteosarcoma is the most prevalent primary bone malignancy in adolescents, and ferroptosis is implicated in its pathogenesis. MicroRNA (miR)-1287-5p plays critical roles in multiple human cancers, and the present study aims to investigate the role and underlying mechanisms of miR-1287-5p in regulating ferroptosis and osteosarcoma progression. Human osteosarcoma cell lines were treated with the mimic, inhibitor or matched controls of miR-1287-5p. Cell viability, colony formation, cell death ratio and ferroptosis were determined. miR-1287-5p expression was downregulated in human osteosarcoma, but upregulated upon ferroptotic stimulation. Overexpression of miR-1287-5p significantly induced, while inhibition of miR-1287-5p suppressed ferroptosis of osteosarcoma cells, thereby modulating cell viability and colony formation. Mechanistic studies indicated that miR-1287-5p directly bound to the 3'-untranslated region of glutathione peroxidase 4 (GPX4) to inhibit its protein level and activity, and that GPX4 overexpression completely abolished the miR-1287-5p mimic-mediated ferroptotic induction and tumor suppression. Moreover, the miR-1287-5p mimic dramatically sensitized human osteosarcoma cells to cisplatin chemotherapy. Our findings prove that miR-1287-5p promotes ferroptosis of osteosarcoma cells through inhibiting GPX4, identifying an adjuvant and even alternative method for the treatment of human osteosarcoma.

Induction and application of ferroptosis in cancer therapy

At present, more than one cell death pathways have been found, one of which is ferroptosis. Ferroptosis was discovered in 2012 and described as an iron-dependent and lipid peroxidation-driven regulated cell death pathway. In the past few years, ferroptosis has been shown to induce tumor cell death, providing new ideas for tumor treatment. In this article, we summarize the latest advances in ferroptosis-induced tumor therapy at the intersection of tumor biology, molecular biology, redox biology, and materials chemistry. First, we state the characteristics of ferroptosis in cells, then introduce the key molecular mechanism of ferroptosis, and describes the relationship between ferroptosis and oxidative stress signaling pathways. Finally, we focused on several types of ferroptosis inducers discovered by scholars, and the application of ferroptosis in systemic chemotherapy, radiotherapy, immunotherapy and nanomedicine, in the hope that ferroptosis can exert its potential in the treatment of tumors.

Dihydroartemisinin enhances the inhibitory effect of sorafenib on HepG2 cells by inducing ferroptosis and inhibiting energy metabolism

Although sorafenib (Sora) shows improved efficacy in clinical liver cancer therapy, its therapeutic efficacy is still greatly limited due to side effects as well as drug resistance. Thus new drug intervention strategies are imperative. Our research showed the combined application of Dihydroartemisinin (DHA) and Sora had a synergistic inhibitory effect on HepG2 and SW480 cells, and DHA enhanced Sora efficacy on xenograft tumor in nude mice. DHA and Sora significantly inhibited the cell energy metabolism by decreasing the ATP synthesis rate of oxidative phosphorylation and glycolysis rate, and induced ferroptosis by increasing the level of lipid reactive oxygen species (L-ROS), labile iron pool (LIP) as well as malondialdehyde (MDA) and decreasing the level of glutathione (GSH) in HepG2 cells. In addition, DHA and Sora significantly decreased the levels of SLC7A11 (xCT), GCLC, GPX4, and HO-1 protein in HepG2 cells. Importantly, the above-mentioned indicators changed more significantly after the combined application of DHA and Sora as compared with Sora. In conclusion, DHA and Sora had the same mechanism, and the combined application of them could have a synergistic anti-tumor effect by inducing ferroptosis and inhibiting energy metabolism in HepG2 cells.

Co-delivery of dihydroartemisinin and pyropheophorbide-iron elicits ferroptosis to potentiate cancer immunotherapy

Dihydroartemisinin (DHA) has shown cytotoxicity against various tumor cells in vitro in an iron-dependent manner, but its in vivo antitumor efficacy is compromised by its rapid degradation and clearance. Here we show the induction of ferroptosis by DHA in an immunogenic fashion and the maximization of in vivo antitumor efficacy of DHA by co-delivering a cholesterol derivative of DHA (Chol-DHA) and Pyropheophorbide-iron (Pyro-Fe) in ZnP@DHA/Pyro-Fe core-shell nanoparticles. ZnP@DHA/Pyro-Fe particles stabilize DHA against hydrolysis and prolong blood circulation of Chol-DHA and Pyro-Fe for their enhanced uptake in tumors. Co-delivery of an exogenous iron complex and DHA induces more ROS production and causes significant tumor inhibition in vivo. By increasing tumor immunogenicity, the combination of DHA and Pyro-Fe sensitizes non-immunogenic colorectal tumors to anti-PD-L1 checkpoint blockade immunotherapy. These findings suggest the potential of using nanotechnology to repurpose DHA and other drugs with excellent safety profiles for combination with immune checkpoint blockade to treat cancers.

Intracellular ferritin heavy chain plays the key role in artesunate-induced ferroptosis in ovarian serous carcinoma cells

Artesunate, an antimalarial drug, induces ferroptosis, but the mechanism is still unclear. In the present study, we investigated how Artesunate induces ferroptosis in ovarian serous carcinoma. Experiments were performed using the ovarian serous carcinoma cell lines CaOV3 and SKOV3ip1, and the sensitivity of CaOV3 to Artesunate was higher than that of SKOV3ip1. Ferroptosis inhibitors inhibited Artesunate-induced intracellular lipid peroxi­dation and cell death. However, unlike class 1 ferroptosis inducer erastin, Artesunate had no effect on intracellular glutathione-SH levels. We found that Artesunate-induced changes in lysosomal Fe‍²⁺ were parallel to the induction of ferroptosis. Therefore, ferritin, which oxidizes and binds intracellular Fe‍²⁺, may have an inhibitory effect on ferroptosis. Knockdown of nuclear coactivator 4, a key molecule of ferritinophagy (ferritin-specific autophagy), suppressed Artesunate-induced cell death. Knockdown of ferritin heavy chain by siRNA greatly enhanced the sensitivity to Artesunate, and overexpression of ferritin heavy chain greatly reduced the sensitivity of ovarian cancer cell lines to Artesunate. These results can explain the differential sensitivity of CaOV3 and SKOV3ip1 to Artesunate. In conclusion, enhancement of ferritinophagy is an important step involved in the mechanism of Artesunate-induced ferroptosis, and ferritin heavy chain levels may contribute to the regulation of sensitivity in Artesunate-induced ferroptosis in ovarian serous carcinoma cells.