2-Methoxy-6-acetyl-7-methyljuglone (MAM) induced programmed necrosis in glioblastoma by targeting NAD(P)H: Quinone oxidoreductase 1 (NQO1)

SP600125, a selective JNK inhibitor, is a potent inhibitor of NAD(P)H: quinone oxidoreductase 1 (NQO1)

The c-Jun N-terminal kinases (JNKs) has been identified as a critical modulator in multiple cellular processes, including stress stimulus, inflammation, cell proliferation, apoptosis, etc. SP600125 is a widely used ATP-competitive reversible JNKs inhibitor. NAD(P)H: quinone oxidoreductase 1 (NQO1) is a flavoprotein mediated two or four electron-reduction of quinones. Here, we showed that SP600125 bind to the active pocket of NQO1 and inhibit NQO1 activity. SP600125 exhibits comparable inhibitory effects on NQO1-mediated quinone bioactivation, H2O2 generation, and cell death, as the specific NQO1 inhibitor dicoumarol (DIC). Importantly, the inhibitory effects of SP600125 on NQO1 are independent of JNKs inhibition. These results suggested that SP600125 is a novel NQO1 inhibitor, which provides new insights into the mechanism of action of SP600125. Furthermore, SP600125 should be used more cautiously as a JNKs inhibitor, especially when NQO1 is highly expressed. SP600125 competed with β-Lap (NQO1-bioactivated drugs) for binding to NQO1, and inhibited NQO1-dependent cell death.

A small molecule cryptotanshinone induces non-enzymatic NQO1-dependent necrosis in cancer cells through the JNK1/2/Iron/PARP/calcium pathway

Human NAD(P)H: quinone oxidoreductase 1 (NQO1) is a flavoenzyme expressed at high levels in multiple solid tumors, making it an attractive target for anticancer drugs. Bioactivatable drugs targeting NQO1, such as β-lapachone (β-lap), are currently in clinical trials for the treatment of cancer. β-Lap selectively kills NQO1-positive (NQO1+) cancer cells by inducing reactive oxygen species (ROS) via catalytic activation of NQO1. In this study, we demonstrated that cryptotanshinone (CTS), a naturally occurring compound, induces NQO1-dependent necrosis without affecting NQO1 activity. CTS selectively kills NQO1+ cancer cells by inducing NQO1-dependent necrosis. Interestingly, CTS directly binds to NQO1 but does not activate its catalytic activity. In addition, CTS enables activation of JNK1/2 and PARP, accumulation of iron and Ca2+, and depletion of ATP and NAD+. Furthermore, CTS selectively suppressed tumor growth in the NQO1+ xenograft models, which was reversed by NQO1 inhibitor and NQO1 shRNA. In conclusion, CTS induces NQO1-dependent necrosis via the JNK1/2/iron/PARP/NAD+/Ca2+ signaling pathway. This study demonstrates the non-enzymatic function of NQO1 in inducing cell death and provides new avenues for the design and development of NQO1-targeted anticancer drugs.

Tumor-Specific Nano-Herb Delivery System with High L-Arginine Loading for Synergistic Chemo and Gas Therapy against Cervical Cancer

Cancer metastasis poses significant challenges in current clinical therapy. Osthole (OST) has demonstrated efficacy in treating cervical cancer and inhibiting metastasis. Despite these positive results, its limited solubility, poor oral absorption, low bioavailability, and photosensitivity hinder its clinical application. To address this limitation, a glutathione (GSH)-responded nano-herb delivery system (HA/MOS@OST&L-Arg nanoparticles, HMOA NPs) is devised for the targeted delivery of OST with cascade-activatable nitric oxide (NO) release. The HMOA NPs system is engineered utilizing enhanced permeability and retention (EPR) effects and active targeting mediated by hyaluronic acid (HA) binding to glycoprotein CD44. The cargoes, including OST and L-Arginine (L-Arg), are released rapidly due to the degradation of GSH-responsive mesoporous organic silica (MOS). Then abundant reactive oxygen species (ROS) are produced from OST in the presence of high concentrations of NAD(P)H quinone oxidoreductase 1 (NQO1), resulting in the generation of NO and subsequently highly toxic peroxynitrite (ONOO-) by catalyzing guanidine groups of L-Arg. These ROS, NO, and ONOO- molecules have a direct impact on mitochondrial function by reducing mitochondrial membrane potential and inhibiting adenosine triphosphate (ATP) production, thereby promoting increased apoptosis and inhibiting metastasis. Overall, the results indicated that HMOA NPs has great potential as a promising alternative for the clinical treatment of cervical cancer.

Inducing ferroptosis by traditional medicines: a novel approach to reverse chemoresistance in lung cancer

Lung cancer is the leading cause of global cancer-related deaths. Platinum-based chemotherapy is the first-line treatment for the most common type of lung cancer, i.e., non-small-cell lung cancer (NSCLC), but its therapeutic efficiency is limited by chemotherapeutic resistance. Therefore, it is vital to develop effective therapeutic modalities that bypass the common molecular mechanisms associated with chemotherapeutic resistance. Ferroptosis is a form of non-apoptotic regulated cell death characterized by iron-dependent lipid peroxidation (LPO). Ferroptosis is crucial for the proper therapeutic efficacy of lung cancer-associated chemotherapies. If targeted as a novel therapeutic mechanism, ferroptosis modulators present new opportunities for increasing the therapeutic efficacy of lung cancer chemotherapy. Emerging studies have revealed that the pharmacological induction of ferroptosis using natural compounds boosts the efficacy of chemotherapy in lung cancer or drug-resistant cancer. In this review, we first discuss chemotherapeutic resistance (or chemoresistance) in lung cancer and introduce the core mechanisms behind ferroptosis. Then, we comprehensively summarize the small-molecule compounds sourced from traditional medicines that may boost the anti-tumor activity of current chemotherapeutic agents and overcome chemotherapeutic resistance in NSCLC. Cumulatively, we suggest that traditional medicines with ferroptosis-related anticancer activity could serve as a starting point to overcome chemotherapeutic resistance in NSCLC by inducing ferroptosis, highlighting new potential therapeutic regimens used to overcome chemoresistance in NSCLC.

A review of natural products and small-molecule therapeutics acting on central nervous system malignancies: Approaches for drug development, targeting pathways, clinical trials, and challenges

In 2021, the World Health Organization released the fifth edition of the central nervous system (CNS) tumor classification. This classification uses histopathology and molecular pathogenesis to group tumors into more biologically and molecularly defined entities. The prognosis of brain cancer, particularly malignant tumors, has remained poor worldwide, approximately 308,102 new cases of brain and other CNS tumors were diagnosed in the year 2020, with an estimated 251,329 deaths. The cost and time-consuming nature of studies to find new anticancer agents makes it necessary to have well-designed studies. In the present study, the pathways that can be targeted for drug development are discussed in detail. Some of the important cellular origins, signaling, and pathways involved in the efficacy of bioactive molecules against CNS tumorigenesis or progression, as well as prognosis and common approaches for treatment of different types of brain tumors, are reviewed. Moreover, different study tools, including cell lines, in vitro, in vivo, and clinical trial challenges, are discussed. In addition, in this article, natural products as one of the most important sources for finding new chemotherapeutics were reviewed and over 700 reported molecules with efficacy against CNS cancer cells are gathered and classified according to their structure. Based on the clinical trials that have been registered, very few of these natural or semi-synthetic derivatives have been studied in humans. The review can help researchers understand the involved mechanisms and design new goal-oriented studies for drug development against CNS malignancies.

Application of calcium overload-based ion interference therapy in tumor treatment: strategies, outcomes, and prospects

Low selectivity and tumor drug resistance are the main hinderances to conventional radiotherapy and chemotherapy against tumor. Ion interference therapy is an innovative anti-tumor strategy that has been recently reported to induce metabolic disorders and inhibit proliferation of tumor cells by reordering bioactive ions within the tumor cells. Calcium cation (Ca2+) are indispensable for all physiological activities of cells. In particular, calcium overload, characterized by the abnormal intracellular Ca2+ accumulation, causes irreversible cell death. Consequently, calcium overload-based ion interference therapy has the potential to overcome resistance to traditional tumor treatment strategies and holds promise for clinical application. In this review, we 1) Summed up the current strategies employed in this therapy; 2) Described the outcome of tumor cell death resulting from this therapy; 3) Discussed its potential application in synergistic therapy with immunotherapy.

Glioblastoma research on zebrafish xenograft models: a systematic review

Glioblastoma (GBM) constitutes the most common primary brain tumor in adults. The challenges in GBM therapeutics have shed light on zebrafish used as a promising animal model for preclinical GBM xenograft studies without a standardized methodology. This systematic review aims to summarize the advances in zebrafish GBM xenografting, compare research protocols to pinpoint advantages and underlying limitations, and designate the predominant xenografting parameters. Based on the PRISMA checklist, we systematically searched PubMed, Scopus, and ZFIN using the keywords "glioblastoma," "xenotransplantation," and "zebrafish" for papers published from 2005 to 2022, available in English. 46 articles meeting the review criteria were examined for the zebrafish strain, cancer cell line, cell labeling technique, injected cell number, time and site of injection, and maintenance temperature. Our review designated that AB wild-type zebrafish, Casper transparent mutants, transgenic Tg(fli1:EGFP), or crossbreeding of these predominate among the zebrafish strains. Orthotopic transplantation is more commonly employed. A number of 50-100 cells injected at 48 h post-fertilization in high density and low infusion volume is considered as an effective xenografting approach. U87 cells are used for GBM angiogenesis studies, U251 for GBM proliferation studies, and patient-derived xenograft (PDX) to achieve clinical relevance. Gradual acclimatization to 32-33 °C can partly address the temperature differential between the zebrafish and the GBM cells. Zebrafish xenograft models constitute valuable tools for preclinical studies with clinical relevance regarding PDX. The GBM xenografting research requires modification based on the objective of each research team. Automation and further optimization of the protocol parameters could scale up the anticancer drug trials.

Regulated cell death in glioma: promising targets for natural small-molecule compounds

Gliomas are prevalent malignant tumors in adults, which can be categorized as either localized or diffuse gliomas. Glioblastoma is the most aggressive and deadliest form of glioma. Currently, there is no complete cure, and the median survival time is less than one year. The main mechanism of regulated cell death involves organisms coordinating the elimination of damaged cells at risk of tumor transformation or cells hijacked by microorganisms for pathogen replication. This process includes apoptosis, necroptosis, autophagy, ferroptosis, pyroptosis, necrosis, parthanayosis, entosis, lysosome-dependent death, NETosis, oxiptosis, alkaliptosis, and disulfidaptosis. The main goal of clinical oncology is to develop therapies that promote the effective elimination of cancer cells by regulating cell death are the main goal of clinical oncology. Recently, scientists have utilized pertinent regulatory factors and natural small-molecule compounds to induce regulated cell death for the treatment of gliomas. By analyzing the PubMed and Web of Science databases, this paper reviews the research progress on the regulation of cell death and the role of natural small-molecule compounds in glioma. The aim is to provide help for the treatment of glioblastoma.

Impact of NQO1 dysregulation in CNS disorders

NAD(P)H Quinone Dehydrogenase 1 (NQO1) plays a pivotal role in the regulation of neuronal function and synaptic plasticity, cellular adaptation to oxidative stress, neuroinflammatory and degenerative processes, and tumorigenesis in the central nervous system (CNS). Impairment of the NQO1 activity in the CNS can result in abnormal neurotransmitter release and clearance, increased oxidative stress, and aggravated cellular injury/death. Furthermore, it can cause disturbances in neural circuit function and synaptic neurotransmission. The abnormalities of NQO1 enzyme activity have been linked to the pathophysiological mechanisms of multiple neurological disorders, including Parkinson's disease, Alzheimer's disease, epilepsy, multiple sclerosis, cerebrovascular disease, traumatic brain injury, and brain malignancy. NQO1 contributes to various dimensions of tumorigenesis and treatment response in various brain tumors. The precise mechanisms through which abnormalities in NQO1 function contribute to these neurological disorders continue to be a subject of ongoing research. Building upon the existing knowledge, the present study reviews current investigations describing the role of NQO1 dysregulations in various neurological disorders. This study emphasizes the potential of NQO1 as a biomarker in diagnostic and prognostic approaches, as well as its suitability as a target for drug development strategies in neurological disorders.

Fighting drug-resistant lung cancer by induction of NAD(P)H:quinone oxidoreductase 1 (NQO1)-mediated ferroptosis

Drug resistance is a major challenge in cancer treatment. The substrates of NAD(P)H:quinone oxidoreductase 1 (NQO1) show a promising anticancer effect in clinical trials. We previously identified a natural NQO1 substrate 2-methoxy-6-acetyl-7-methyljuglone (MAM) with a potent anticancer effect. The present study was designed to explore the efficacy of MAM in fighting against drug-resistant non-small cell lung cancer (NSCLC). The anticancer effect of MAM was evaluated in cisplatin-resistant A549 and AZD9291-resistant H1975 cells. The interaction of MAM with NQO1 was measured by cellular thermal shift assay and drug affinity responsive target stability assay. The NQO1 activity and expression were measured using NQO1 recombinant protein, Western blotting, and immunofluorescence staining assay. The roles of NQO1 were examined by NQO1 inhibitor, small interfering RNA (siRNA), and short hairpin RNA (shRNA). The roles of reactive oxygen species (ROS), labile iron pool (LIP), and lipid peroxidation were determined. MAM induced significant cell death in drug-resistant cells with similar potency to that of parental cells, which were completely abolished by NQO1 inhibitor, NQO1 siRNA, and iron chelators. MAM activates and binds to NQO1, which triggers ROS generation, LIP increase, and lipid peroxidation. MAM significantly suppressed tumor growth in the tumor xenograft zebrafish model. These results showed that MAM induced ferroptosis by targeting NQO1 in drug-resistant NSCLC cells. Our findings provided a novel therapeutic strategy for fighting against drug resistance by induction of NQO1-mediated ferroptosis.

The Anticancer Effect of Napabucasin (BBI608), a Natural Naphthoquinone

Napabucasin (also known as BBI608) is a natural naphthoquinone originally identified as a cancer cell stemness inhibitor. Accumulated in vitro and in vivo evidence demonstrated that napabucasin showed significant anticancer effects in various types of cancers. Napabucasin inhibits cancer cell proliferation, induces apoptosis and cell cycle arrest, and suppresses metastasis and relapse. Such anticancer activities of napabucasin mainly rely on the inhibition of cancer stemness by targeting signal transducer and activator of transcription 3 (STAT3) and its related gene inhibition. However, several novel molecular targets for napabucasin, such as NAD(P)H:quinone oxidoreductase 1 (NQO1) and thioredoxin reductase 1 (TrxR1), have been reported. Napabucasin represents a promising anticancer lead for multiple cancers. In this mini review, the anticancer potential and the molecular mechanism of napabucasin will be briefly highlighted.

Application of Zebrafish as a Model for Anti-Cancer Activity Evaluation and Toxicity Testing of Natural Products

Developing natural product-based anti-cancer drugs/agents is a promising way to overcome the serious side effects and toxicity of traditional chemotherapeutics for cancer treatment. However, rapid assessment of the in vivo anti-cancer activities of natural products is a challenge. Alternatively, zebrafish are useful model organisms and perform well in addressing this challenging issue. Nowadays, a growing number of studies have utilized zebrafish models to evaluate the in vivo activities of natural compounds. Herein, we reviewed the application of zebrafish models for evaluating the anti-cancer activity and toxicity of natural products over the past years, summarized its process and benefits, and provided future outlooks for the development of natural product-based anti-cancer drugs.

Nitrovin (difurazone), an antibacterial growth promoter, induces ROS-mediated paraptosis-like cell death by targeting thioredoxin reductase 1 (TrxR1)

Glioblastoma multiforme (GBM) is one of the most lethal malignant tumors in the human brain, with only a few chemotherapeutic drugs available after surgery. Nitrovin (difurazone) is widely used as an antibacterial growth promoter in livestock. Here, we reported that nitrovin might be a potential anticancer lead. Nitrovin showed significant cytotoxicity to a panel of cancer cell lines. Nitrovin induced cytoplasmic vacuolation, reactive oxygen species (ROS) generation, MAPK activation, and Alix inhibition but had no effect on caspase-3 cleavage and activity, suggesting paraptosis activation. Nitrovin-induced cell death of GBM cells was significantly reversed by cycloheximide (CHX), N-acetyl-l-cysteine (NAC), glutathione (GSH), and thioredoxin reductase 1 (TrxR1) overexpression. Vitamins C and E, inhibitors of pan-caspase, MAPKs, and endoplasmic reticulum (ER) stress failed to do so. Nitrovin-triggered cytoplasmic vacuolation was reversed by CHX, NAC, GSH, and TrxR1 overexpression but not by Alix overexpression. Furthermore, nitrovin interacted with TrxR1 and significantly inhibited its activity. In addition, nitrovin showed a significant anticancer effect in a zebrafish xenograft model, which was reversed by NAC. In conclusion, our results showed that nitrovin induced non-apoptotic and paraptosis-like cell death mediated by ROS through targeting TrxR1. Nitrovin might be a promising anticancer lead for further development.

Inhibition of the pseudokinase MLKL alters extracellular vesicle release and reduces tumor growth in glioblastoma

Extracellular vesicles (EVs) are lipid-based nanosized particles that convey biological material from donor to recipient cells. EVs play key roles in glioblastoma progression because glioblastoma stem-like cells (GSCs) release pro-oncogenic, pro-angiogenic, and pro-inflammatory EVs. However, the molecular basis of EV release remains poorly understood. Here, we report the identification of the pseudokinase MLKL, a crucial effector of cell death by necroptosis, as a regulator of the constitutive secretion of EVs in GSCs. We find that genetic, protein, and pharmacological targeting of MLKL alters intracellular trafficking and EV release, and reduces GSC expansion. Nevertheless, this function ascribed to MLKL appears independent of its role during necroptosis. In vivo, pharmacological inhibition of MLKL reduces the tumor burden and the level of plasmatic EVs. This work highlights the necroptosis-independent role of MLKL in vesicle release and suggests that interfering with EVs is a promising therapeutic option to sensitize glioblastoma cells.

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The pseudokinase MLKL governs extracellular vesicle release in glioblastoma cells

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Blocking MLKL is deleterious to glioblastoma cell expansion in vitro and in vivo

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MLKL action in glioblastoma patient cells does not involve necroptosis death

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MLKL inhibition potentiates TMZ-induced cell death in glioblastoma patient cells

Exogenous iron impairs the anti-cancer effect of ascorbic acid both in vitro and in vivo

INTRODUCTION

The anti-cancer effect of high concentrations of ascorbic acid (AA) has been well established while its underlying mechanisms remain unclear. The association between iron and AA has attracted great attention but was still controversial due to the complicated roles of iron in tumors.

OBJECTIVES

Our study aims to explore the anti-cancer mechanisms of AA and the interaction between AA and iron in cancer.

METHODS

The MTT and ATP assays were used to evaluate the cytotoxicity of AA. Reactive oxygen species (ROS) generation, calcium (Ca²⁺), and lipid peroxidation were monitored with flow cytometry. Mitochondrial dysfunction was assessed by mitochondrial membrane potential (MMP) detection with JC-1 or tetramethylrhodamine methyl ester (TMRM) staining. Mitochondrial swelling was monitored with MitoTracker Green probe. FeSO₄ (Fe²⁺), FeCl₃ (Fe³⁺), Ferric ammonium citrate (Fe³⁺), hemin chloride (Fe³⁺) were used as an iron donor to investigate the effects of iron on AA's anti-tumor activity. The in vivo effects of AA and iron were analyzed in xenograft zebrafish and allograft mouse models.

RESULTS

High concentrations of AA exhibited cytotoxicity in a panel of cancer cells. AA triggered ROS-dependent non-apoptotic cell death. AA-induced cell death was essentially mediated by the accumulated intracellular Ca²⁺, which was partly originated from endoplasmic reticulum (ER). Surprisingly, exogenous iron could significantly reverse AA-induced ROS generation, Ca²⁺ overloaded, and cell death. Especially, the iron supplements significantly impaired the in vivo anti-tumor activity of AA.

CONCLUSIONS

Our study elucidated the protective roles of iron in ROS/Ca²⁺ mediated necrosis triggered by AA both in vitro and in vivo, which might shed novel insight into the anti-cancer mechanisms and provide clinical application strategies for AA in cancer treatment.

Osthole Induces Apoptosis and Caspase-3/GSDME-Dependent Pyroptosis via NQO1-Mediated ROS Generation in HeLa Cells

Osthole is a natural coumarin which has been proved to inhibit growth of cancer cells by inducing cell death, while its mechanism was considered to be just caused by apoptosis. In our study, we found that osthole activated not just apoptosis, but also pyroptosis which is a form of regulated cell death accompanied by loss of cell membrane integrity and lactate dehydrogenase (LDH) release. Caspase-3 is a key protein of apoptosis as well as pyroptosis. The apoptosis and pyroptosis induced by osthole were all inhibited by irreversible caspase-3 inhibitor Z-DEVD-FMK. Meanwhile, knockdown of gasdermin E (GSDME) only reduced the osthole-induced pyroptosis but did not affect the occurrence of apoptosis. Our proteomic analysis revealed that the expression of NAD(P)H: quinone oxidoreductase 1 (NQO1) was decreased in osthole-treated cells. Moreover, NQO1 inhibition by osthole induced the overproduction of reactive oxygen species (ROS), as well as apoptosis and pyroptosis. ROS inhibitor N-Acetyl-L-cysteine (NAC) not only reduced osthole-induced apoptosis but also reversed its effect on the pyroptosis. Meanwhile, knockdown of NQO1 by si-NQO1 or its inhibitor dicoumarol (DIC) not only enhanced ROS generation but also strengthened the GSDME-mediated pyroptosis. Finally, we demonstrated that osthole inhibited tumor growth and the expression of NQO1 in a HeLa xenograft mode. Similar to the results in vitro, osthole stimulated the activation of caspase-3, PARP, and GSDME in vivo. Taken together, all these data suggested that osthole induced apoptosis and caspase-3/GSDME-mediated pyroptosis via NQO1-mediated ROS accumulation.

Patient-Derived Xenotransplant of CNS Neoplasms in Zebrafish: A Systematic Review

Glioblastoma and neuroblastoma are the most common central nervous system malignant tumors in adult and pediatric populations. Both are associated with poor survival. These tumors are highly heterogeneous, having complex interactions among different cells within the tumor and with the tumor microenvironment. One of the main challenges in the neuro-oncology field is achieving optimal conditions to evaluate a tumor’s molecular genotype and phenotype. In this respect, the zebrafish biological model is becoming an excellent alternative for studying carcinogenic processes and discovering new treatments. This review aimed to describe the results of xenotransplantation of patient-derived CNS tumors in zebrafish models. The reviewed studies show that it is possible to maintain glioblastoma and neuroblastoma primary cell cultures and transplant the cells into zebrafish embryos. The zebrafish is a suitable biological model for understanding tumor progression and the effects of different treatments. This model offers new perspectives in providing personalized care and improving outcomes for patients living with central nervous system tumors.

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) inhibitors Necrostatin-1 (Nec-1) and 7-Cl-O-Nec-1 (Nec-1s) are potent inhibitors of NAD(P)H: Quinone oxidoreductase 1 (NQO1)

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) has been identified as a critical mediator of cell death (necroptosis and apoptosis) and inflammation. Necrostatin-1 (Nec-1) and 7-Cl-O-Nec-1 (Nec-1s) are widely used as selective small-molecule inhibitors of RIPK1 in various culture cells and disease models. NAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme that catalyzes the reduction and detoxification of quinones and other organic compounds. Here, we showed that Nec-1 and Nec-1s could bind and inhibit NQO1 activity. Similar to dicoumarol, the specific inhibitor of NQO1, both Nec-1 and Nec-1s significantly suppress NQO1-dependent cell death. However, dicoumarol failed to reverse necroptosis induced by TNFα/BV6/Z-VAD-FMK (TBZ) in HT29 cells. These findings suggest that besides RIPK1, NQO1 might be another target for Nec-1 and Nec-1s and provide new insights for the interpretation of Nec-1-based experimental results.

2-Methoxy-6-Acetyl-7-Methyljuglone: A Bioactive Phytochemical with Potential Pharmacological Activities

Natural products have been the focus of biomedical and pharmaceutical research to develop new therapies in recent years. 2-methoxy-6-acetyl-7-methyljuglone (2-methoxystypandrone, MAM), a natural bioactive juglone derivative, is known to have various levels of pharmacotherapeutic efficacies as an anti-inflammatory, anticancer, antioxidant, antimicrobial, and anti-HIV activity. MAM fights cancer progression by inducing apoptosis, necroptosis, and deregulating signaling pathways through H2O2-induced JNK/iNOS/NO and MAPK, ERK1/2 pathways, JNK activation, and the RIP1/RIP3 complex. In this review, we summarize the pharmacological importance of MAM in the field of drug discovery. Furthermore, this review not only emphasizes the medicinal properties of MAM but also discusses its potential efficacy in future medicinal products.

A novel strategy for glioblastoma treatment by induction of noptosis, an NQO1-dependent necrosis

Glioblastoma (GBM) is one of the most prevalent malignant primary tumors in the human brain. Temozolomide (TMZ), the chemotherapeutic drug for GBM treatment, induces apoptosis. Unfortunately, apoptosis-resistance to TMZ results in treatment failure. GBM shows enhanced expression of NAD(P)H: quinone oxidoreductase 1 (NQO1). Recently, noptosis, a type of NQO1-dependent necrosis, was proposed. Here, we identified that tanshindiol B (TSB) inhibits GBM growth by induction of noptosis. TSB triggered significant cell death, which did not fit the criteria of apoptosis but oxidative stress-induced necrosis. Molecular docking, cellular thermal shift assay, and NQO1 activity assay revealed that TSB bind to and promptly activated NQO1 enzyme activity. As the substrate of NQO1, TSB induced oxidative stress, which resulted in dramatic DNA damage, poly (ADP-ribose) polymerase 1 (PARP1) hyperactivation, and NAD⁺ depletion, leading to necrotic cell death. These effects of TSB were completely abolished by specific NQO1 inhibitor dicoumarol (DIC). Furthermore, the c-Jun N-terminal kinase 1/2 (JNK1/2) plays an essential role in mediating TSB-induced cell death. Besides, TSB significantly suppressed tumor growth in a zebrafish xenograft model mediated by NQO1. In conclusion, these results showed that TSB was an NQO1 substrate and triggered noptosis of GBM. TSB exhibited anti-tumor potentials in GBM both in vitro and in vivo. This study provides a novel strategy for fighting GBM through the induction of noptosis.

Cellular and Molecular Mechanisms Underlying Glioblastoma and Zebrafish Models for the Discovery of New Treatments

Glioblastoma (GBM) is the most common of all brain malignant tumors; it displays a median survival of 14.6 months with current complete standard treatment. High heterogeneity, aggressive and invasive behavior, the impossibility of completing tumor resection, limitations for drug administration and therapeutic resistance to current treatments are the main problems presented by this pathology. In recent years, our knowledge of GBM physiopathology has advanced significantly, generating relevant information on the cellular heterogeneity of GBM tumors, including cancer and immune cells such as macrophages/microglia, genetic, epigenetic and metabolic alterations, comprising changes in miRNA expression. In this scenario, the zebrafish has arisen as a promising animal model to progress further due to its unique characteristics, such as transparency, ease of genetic manipulation, ethical and economic advantages and also conservation of the major brain regions and blood-brain-barrier (BBB) which are similar to a human structure. A few papers described in this review, using genetic and xenotransplantation zebrafish models have been used to study GBM as well as to test the anti-tumoral efficacy of new drugs, their ability to interact with target cells, modulate the tumor microenvironment, cross the BBB and/or their toxicity. Prospective studies following these lines of research may lead to a better diagnosis, prognosis and treatment of patients with GBM.

Natural Products as Inducers of Non-Canonical Cell Death: A Weapon against Cancer

Simple Summary

Anticancer therapeutic approaches based solely on apoptosis induction are often unsuccessful due to the activation of resistance mechanisms. The identification and characterization of compounds capable of triggering non-apoptotic, also called non-canonical cell death pathways, could represent an important strategy that may integrate or offer alternative approaches to the current anticancer therapies. In this review, we critically discuss the promotion of ferroptosis, necroptosis, and pyroptosis by natural compounds as a new anticancer strategy.

Abstract

Apoptosis has been considered the main mechanism induced by cancer chemotherapeutic drugs for a long time. This paradigm is currently evolving and changing, as increasing evidence pointed out that antitumor agents could trigger various non-canonical or non-apoptotic cell death types. A considerable number of antitumor drugs derive from natural sources, both in their naturally occurring form or as synthetic derivatives. Therefore, it is not surprising that several natural compounds have been explored for their ability to induce non-canonical cell death. The aim of this review is to highlight the potential antitumor effects of natural products as ferroptosis, necroptosis, or pyroptosis inducers. Natural products have proven to be promising non-canonical cell death inducers, capable of overcoming cancer cells resistance to apoptosis. However, as discussed in this review, they often lack a full characterization of their antitumor activity together with an in-depth investigation of their toxicological profile.

A pharmacological review of dicoumarol: An old natural anticoagulant agent

Dicoumarol is an oral anticoagulant agent prescribed in clinical for decades. It is a natural hydroxycoumarin discovered from the spoilage of Melilotus officinalis (L.) Pall and is originally discovered as a rodenticide. Due to its structural similarity to that of vitamin K, it significantly inhibits vitamin K epoxide reductase and acts as a vitamin K antagonist. Dicoumarol is mainly used as an anticoagulant to prevent thrombogenesis and to cure vascular thrombosis. Other biological activities besides anticoagulants such as anticancer, antimicrobial, antiviral, etc., have also been documented. The side effects of dicoumarol raise safety concerns for clinical application. In this review, the physicochemical property, the pharmacological activities, the side effects, and the pharmacokinetics of dicoumarol were summarized, aiming to provide a whole picture of the "old" anticoagulant.

Induction of programmed necrosis: A novel anti-cancer strategy for natural compounds

Cell death plays a critical role in organism development and the pathogenesis of diseases. Necrosis is considered a non-programmed cell death in an extreme environment. Recent advances have provided solid evidence that necrosis could be programmed and quite a few types of programmed necrosis, such as necroptosis, ferroptosis, pyroptosis, paraptosis, mitochondrial permeability transition-driven necrosis, and oncosis, have been identified. The specific biomarkers, detailed signaling, and precise pathophysiological importance of programmed necrosis are yet to be clarified, but these forms of necrosis provide novel strategies for the treatment of various diseases, including cancer. Natural compounds are a unique source of lead compounds for the discovery of anti-cancer drugs. Natural compounds can induce both apoptosis and programmed necrosis. In this review, we summarized the recent progress of programmed necrosis and introduced their natural inducers. Noptosis, which is a novel type of programmed necrosis that is strictly dependent on NAD(P)H: quinone oxidoreductase 1-derived oxidative stress was proposed. Furthermore, the anti-cancer strategies that take advantage of programmed necrosis and the main concerns from the scientific community in this regard were discussed.