Evidence for the involvement of carbon-centered radicals in the induction of apoptotic cell death by artemisinin compounds

New hydrazide derivatives of N-amino-11-azaartemisinin as promising epidermal growth factor receptor inhibitors for therapeutic development in triple-negative breast cancer

Triple-negative breast cancer (TNBC) treatments, such as DNA-damaging agents like carboplatin, pose considerable human toxicity and may contribute to cancer relapse. Artemisinin derivatives offer a less toxic alternative; however, their specific role in TNBC management remains to be established. To address this gap, computational models were employed to design and evaluate artemisinin-based prototypes as potential TNBC therapeutics, aiming to provide safer and more effective treatment options for this aggressive cancer subtype. Among the series of hydrazide derivatives of azaartemisinin (10a-l) reported herein, compound 10j emerged as the most promising, exhibiting notable cytotoxicity with IC50 values of 1.74 and 1.64 µM against MDA-MB-231 and MDA-MB-468 cells, respectively. The clinically useful drug doxorubicin provided IC50 values of 0.29 and 0.29 µM against MDA-MB-231 and MDA-MB-468 cells, while artemisinin provided IC50 values of 107.30 and 116.60 µM, respectively. Furthermore, putative interactions between the synthesized compounds and the epidermal growth factor receptor (EGFR) were identified using molecular docking studies, suggesting a possible mechanism for their anticancer effect. Additionally, to determine the thermodynamic parameters of the interactions between artemisinin, azaartemisinin, and biomolecules, isothermal titration calorimetry experiments were performed. The binding constant value on the order of 104 indicates a comparatively stronger binding affinity of azaartemisinin with human serum albumin (HSA) compared to artemisinin with HSA. These findings support the potential of azaartemisinin derivatives as promising EGFR inhibitors for therapeutic development in TNBC, offering a new avenue for less toxic and more effective cancer treatments.

Design, synthesis, and in vitro and in vivo biological evaluation of dihydroartemisinin derivatives as potent anti-cancer agents with ferroptosis-inducing and apoptosis-activating properties

Natural products play a pivotal role in drug development, including their direct use as pharmaceuticals and their structural modification, yielding molecules with enhanced therapeutic potential. The discovery of bioactive molecules, lead compounds, and novel drugs is intrinsically linked to the structural optimization of natural products. In this study, forty-one derivatives of dihydroartemisinin (DHA) were synthesized by incorporating fragments with anti-tumour activity via molecular hybridization, and assessed for their anti-proliferative activity against human cancer cell lines (A549, Bel-7402, HCT-116, and SW620) and normal human liver cells (LO2). Most derivatives exhibited superior anti-proliferative activity compared to DHA. Notably, compound A3, featuring a 4-Cl phenyl carbamate moiety, demonstrated significant anti-proliferative activity against HCT-116 cells with an IC50 of 0.31 μM, making it 16-fold more potent than DHA (IC50 = 5.10 μM). The anti-proliferative mechanism did not involve cytotoxicity (SI = 54.13), indicating its superior safety profile compared to DHA (SI = 1.65). Further mechanistic studies revealed that compound A3 inhibits HCT-116 cell proliferation by modulating the expression of PI3K/AKT/mTOR and STAT3 proteins. STAT3 downregulation represses the expression of the critical ferroptosis protein glutathione peroxidase 4 (GPX4), aggravating the accumulation of reactive oxygen species (ROS) and depletion of glutathione (GSH). This redox imbalance triggers and accelerates ferroptosis. Additionally, A3 also induces apoptosis by damaging mitochondria and influencing MAPK signaling. Compound A3 arrested cells in the G2/M phase by regulating p53 expression. In an HCT-116 xenograft mouse model, compound A3 exhibited significant anti-cancer efficacy, with a tumor growth inhibition rate of 58.7 %. Therefore, compound A3 thus has the potential to serve as a lead compound for the development of new anti-tumor drugs.

Natural products targeting ferroptosis pathways in cancer therapy (Review)

Ferroptosis inducers (FIN) have a key role in cancer therapy and provide novel and innovative treatment strategies. Although many researchers have performed FIN screening of synthetic compounds, studies on the identification of FIN from natural products are limited, particularly in the field of drug development and combination therapy. In this review, this gap was addressed by comprehensively summarizing recent studies on ferroptosis. The causes of ferroptosis were categorized into driving and defensive factors, elucidating key pathways and targets. Next, through summarizing research on natural products that induce ferroptosis, the study elaborated in detail on the natural products that have FIN functions. Their discovery and development were also described and insight for clinical drug development was provided. In addition, the mechanisms of action were analyzed and potential combination therapies, resistance reversal and structural enhancements were presented. By highlighting the potential of natural products in inducing ferroptosis for cancer treatment, this review may serve as a reference for utilizing these compounds against cancer. It not only showed the significance of natural products but may also promote further investigation into their therapeutic effects, thus encouraging research in this field.

Artemisinin: An Anti-Leishmania Drug that Targets the Leishmania Parasite and Activates Apoptosis of Infected Cells

Leishmaniasis is a relevant disease worldwide due to its presence in many countries and an estimated prevalence of 10 million people. The causative agent of this disease is the obligate intracellular parasite Leishmania which can infect different cell types. Part of its success depends on its ability to evade host defense mechanisms such as apoptosis. Apoptosis is a finely programmed process of cell death in which cells silently dismantle and actively participate in several processes such as immune response, differentiation, and cell growth. Leishmania has the ability to delay its initiation to persist in the cell. It has been well documented that different Leishmania species target different pathways that lead to apoptosis of cells such as macrophages, neutrophils, and dendritic cells. In many cases, the observed anti-apoptotic effect has been associated with a significant reduction in caspase-3 activity. Leishmania has also been shown to target several pathways involved in apoptosis such as MAPK, PI3K/Akt, and the antiapoptotic protein Bcl-xL. Understanding the strategies used by Leishmania to subvert the defense mechanisms of host cells, particularly apoptosis, is very relevant for the development of therapies and vaccines. In recent years, the drug artemisinin has been shown to be effective against several parasitic diseases. Its role against Leishmania may be promising. In this review, we provide important aspects of the disease, the strategies used by the parasite to suppress apoptosis, and the role of artemisinin in Leishmania infection.

Natural endoperoxides as promising anti-leishmanials

BACKGROUND

The discovery of artemisinin, an endoperoxide, encouraged the scientific community to explore endoperoxides as potential anti-parasitic molecules. Although artemisinin derivatives are rapidly evolving as potent anti-malarials, their potential as anti-leishmanials is emerging gradually. The treatment of leishmaniasis, a group of neglected tropical diseases is handicapped by lack of effective vaccines, drug toxicities and drug resistance. The weak antioxidant defense mechanism of the Leishmania parasites due to lack of catalase and a selenium dependent glutathione peroxidase system makes them vulnerable to oxidative stress, and this has been successful exploited by endoperoxides.

PURPOSE

The study aimed to review the available literature on the anti-leishmanial efficacy of natural endoperoxides with a view to achieve insights into their mode of actions.

METHODS

We reviewed more around 110 research and review articles restricted to the English language, sourced from electronic bibliographic databases including PubMed, Google, Web of Science, Google scholar etc. RESULTS: Natural endoperoxides could potentially augment the anti-leishmanial drug library, with artemisinin and ascaridole emerging as potential anti-leishmanial agents. Due to higher reactivity of the cyclic peroxide moiety, and exploiting the compromised antioxidant defense of Leishmania, endoperoxides like artemisinin and ascaridole potentiate their leishmanicidal efficacy by creating a redox imbalance. Furthermore, these molecules minimally impair oxidative phosphorylation; instead inhibit glycolytic functions, culminating in depolarization of the mitochondrial membrane and depletion of ATP. Additionally, the carbon-centered free radicals generated from endoperoxides, participate in chain reactions that can generate even more reactive organic radicals that are toxic to macromolecules, including lipids, proteins and DNA, leading to cell cycle arrest and apoptosis of Leishmania parasites. However, the precise target(s) of the toxic free radicals remains open-ended.

CONCLUSION

In this overview, the spectrum of natural endoperoxide molecules as major anti-leishmanials and their mechanism of action has been delineated. In view of the substantial evidence that natural endoperoxides (e.g., artemisinin, ascaridole) exert a noxious effect on different species of Leishmania, identification and characterization of other natural endoperoxides is a promising therapeutic option worthy of further pharmacological consideration.

Ferroptosis mechanisms and its novel potential therapeutic targets for DLBCL

Diffuse large B-cell lymphoma (DLBCL), a heterogeneous lymphoid malignancy, poses a significant threat to human health. The standard therapeutic regimen for patients with DLBCL is rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), with a typical cure rate of 50-70%. However, some patients either relapse after complete remission (CR) or exhibit resistance to R-CHOP treatment. Therefore, novel therapeutic approaches are imperative for managing high-risk or refractory DLBCL. Ferroptosis is driven by iron-dependent phospholipid peroxidation, a process that relies on the transition metal iron, reactive oxygen species (ROS), and phospholipids containing polyunsaturated fatty acids-containing phospholipids (PUFA-PLs). Research indicates that ferroptosis is implicated in various carcinogenic and anticancer pathways. Several hematological disorders exhibit heightened sensitivity to cell death induced by ferroptosis. DLBCL cells, in particular, demonstrate an increased demand for iron and an upregulation in the expression of fatty acid synthase. Additionally, there exists a correlation between ferroptosis-associated genes and the prognosis of DLBCL. Therefore, ferroptosis may be a promising novel target for DLBCL therapy. In this review, we elucidate ferroptosis mechanisms, its role in DLBCL, and the potential therapeutic targets in DLBCL. This review offers novel insights into the application of ferroptosis in treatment strategies for DLBCL.

An overview on the antimalarial activity of 1,2,4-trioxanes, 1,2,4-trioxolanes and 1,2,4,5-tetraoxanes

The demand for novel, fast-acting, and effective antimalarial medications is increasing exponentially. Multidrug resistant forms of malarial parasites, which are rapidly spreading, pose a serious threat to global health. Drug resistance has been addressed using a variety of strategies, such as targeted therapies, the hybrid drug idea, the development of advanced analogues of pre-existing drugs, and the hybrid model of resistant strains control mechanisms. Additionally, the demand for discovering new potent drugs grows due to the prolonged life cycle of conventional therapy brought on by the emergence of resistant strains and ongoing changes in existing therapies. The 1,2,4-trioxane ring system in artemisinin (ART) is the most significant endoperoxide structural scaffold and is thought to be the key pharmacophoric moiety required for the pharmacodynamic potential of endoperoxide-based antimalarials. Several derivatives of artemisinin have also been found as potential treatments for multidrug-resistant strain in this area. Many 1,2,4-trioxanes, 1,2,4-trioxolanes, and 1,2,4,5-tetraoxanes derivatives have been synthesised as a result, and many of these have shown promise antimalarial activity both in vivo and in vitro against Plasmodium parasites. As a consequence, efforts to develop a functionally straight-forward, less expensive, and vastly more effective synthetic pathway to trioxanes continue. This study aims to give a thorough examination of the biological properties and mode of action of endoperoxide compounds derived from 1,2,4-trioxane-based functional scaffolds. The present system of 1,2,4-trioxane, 1,2,4-trioxolane, and 1,2,4,5-tetraoxane compounds and dimers with potentially antimalarial activity will be highlighted in this systematic review (January 1963-December 2022).

Boosting Reactive Oxygen Species Generation with a Dual-Catalytic Nanomedicine for Enhanced Tumor Nanocatalytic Therapy

Generating lethal reactive oxygen species (ROS) within tumors by nanocatalytic medicines is an advanced strategy for tumor-specific therapy in recent years. Nevertheless, the low yield of ROS restrains its therapeutic efficiency. Herein, a dual-catalytic nanomedicine based on tumor microenvironment (TME)-responsive liposomal nanosystem co-delivering CuO2 and dihydroartemisinin (DHA) (LIPSe@CuO2&DHA) is developed to boost ROS generation against tumor. The liposomal nanosystem can degrade in the ROS-overexpressed TME and liberate CuO2 and DHA to initiate Cu-based dual-catalytic ROS generation. Serving as generators of H2O2 and Cu2+, CuO2 can self-produce plenty of toxic hydroxyl radicals via Fenton-like reaction in the acidic TME. Meanwhile, the released Cu2+ can catalyze DHA to generate cytotoxic C-centered radicals. Together, the self-supplied H2O2 and Cu-based dual-catalytic reaction greatly increase the intratumoral level of lethal ROS. Importantly, Cu2+ can decrease the GSH-mediated scavenging effect on the produced ROS via a redox reaction and undergo a Cu2+-to-Cu+ conversion to enhance the Fenton-like reaction, further guaranteeing the high efficiency of ROS generation. Resultantly, LIPSe@CuO2&DHA induces remarkable cancer cell death and tumor growth inhibition, which may present a promising nanocatalytic medicine for cancer therapy.

Dynamic nanoassemblies derived from small-molecule homodimeric prodrugs for in situ drug activation and safe osteosarcoma treatment

Supramolecular prodrug self-assembly is a cost-effective and powerful approach for creating injectable anticancer nanoassemblies. Herein, we describe the self-assembly of small-molecule prodrug nanotherapeutics for tumor-restricted pharmacology that can be self-activated and independent of the exogenous stimuli. Covalent dimerization of the anticancer agent cabazitaxel via reactive oxygen species (ROS)- and esterase-activatable linkages produced the homodimeric prodrug diCTX, which was further coassembled with an ROS generator, dimeric dihydroartemisinin (diDHA). The coassembled nanoparticles were further refined in an amphiphilic matrix, making them suitable for in vivo administration. The ROS obtained from the coassembled diDHA synergized with intracellular esterase to activate the neighboring diCTX, which in turn induced potent cytotoxicity. In a preclinical orthotopic model of human osteosarcomas, nanoparticle administration exhibited durable antitumor efficacy. Furthermore, this smart, dual-responsive nanotherapeutic exhibited lower toxicity in animals than those of free drug combinations. We predict that this platform has great potential for further clinical translation.

The Potential of Artemisinins as Novel Treatment for Thyroid Eye Disease by Inhibiting Adipogenesis in Orbital Fibroblasts

Purpose

Thyroid eye disease (TED) causes cosmetic defect and even threatens eyesight due to tissue remodeling in which orbital fibroblast (OF) plays a central role mainly by differentiating into adipocytes. Repurposing old drugs to novel applications is of particular interest. Here, we aimed to evaluate the effects of the antimalarials artemisinin (ARS) and the derivatives on the OFs isolated from patients with TED and their counterparts.

Methods

OFs isolated from patients with TED or their counterparts were cultured and passaged in proliferation medium (PM) and stimulated by differentiation medium (DM) for adipogenesis. OFs were treated with or without ARS, dihydroartemisinin (DHA), and artesunate (ART) at different concentrations, before being examined in vitro. CCK-8 were used to assess cellular viability. Cell proliferation was determined by EdU incorporation and flow cytometry. Lipid accumulation within the cells was evaluated by Oil Red O staining. Hyaluronan production was determined by ELISA. RNAseq, qPCR, and Western blot analysis were performed to illustrate the underlying mechanisms.

Results

ARSs dose-dependently interfered with lipid accumulation of TED-OFs, rather than non-TED-OFs. Meanwhile, the expression of key adipogenic markers, such as PLIN1, PPARG, FABP4, and CEBPA, was suppressed. During adipogenesis as being cultivated in DM, instead of PM, ARSs also inhibited cell cycle, hyaluronan production and the expression of hyaluronan synthase 2 (HAS2) in a concentration-dependent manner. Mechanically, the favorable effects were potentially mediated by the repression of IGF1R-PI3K-AKT signaling by dampening IGF1R expression.

Conclusions

Collectedly, our data evidenced that the conventional antimalarials ARSs were potentially therapeutic for TED.

Antimalarial and anticancer activity evaluation of bridged ozonides, aminoperoxides and tetraoxanes

Bridged aminoperoxides, for the first time, were investigated for the in vitro antimalarial activity against the chloroquine-resistant Plasmodium falciparum strain K1 and for their cytotoxic activities against immortalized human normal liver (LO2) and lung (BEAS-2B) cell lines as well as human liver (HepG2) and lung (A549) cancer cell lines. Aminoperoxides exhibit good cytotoxicity against lung A549 cancer cells line. Synthetic ozonides were shown to have high activity against the chloroquine-resistant P. falciparum . A cyclic voltammetry study of peroxides was performed, and most of the compounds did not show a direct correlation in oxidative capacity-activity. Peroxides were analyzed for ROS production to understand their mechanism of action. However, none of the compounds has an impact on ROS generation, suggesting that ozonides induce apoptosis in HepG2 cells through ROS - independent dysfunction pathway.

Mechanistic Evaluation of the Stability of Arylvinyl-1,2,4-trioxanes under Acidic Conditions for Their Oral Administration as an Antimalarial Drug

A mechanistic approach to understand the course of metabolism for synthetic 1,2,4-trioxanes, potent antimalarial compounds, to evaluate their bioavailability for antimalarial action has been studied in the present work. It is an important parameter to study the course of metabolism of a drug candidate molecule when administered via oral route during its journey from oral intake to its target site. From the pharmacokinetics point of view, it determines the bioavailability of an active drug or a prodrug at the target point. In this work, synthetic arylvinyl-1,2,4-trioxanes 1a-u have been evaluated under various acidic conditions to mimic the milieu of the stomach (pH between 1.5 and 3.5) through which they have to pass when administered orally. The effect of acid on trioxanes led to their degradation into corresponding ketones and glyoxal. Under such acidic conditions glyoxal polymerized to form a nonisolable condensate product. The study indicates that the actual bioavailability of the drug is far less than the administered dose.

Artesunate Suppresses the Growth of Lung Cancer Cells by Downregulating the AKT/Survivin Signaling Pathway

NSCLC (non-small-cell lung cancer) is the deadliest cancer in the world. Artesunate is one of the most potent and rapidly acting antimalarial agents. Recently, emerging evidence has suggested the anticancer function of artesunate. In our work, we aimed to investigate the molecular mechanism of artesunate-induced growth inhibition in human lung adenocarcinoma cells and reported that the anticancer effects of artesunate is related to its ability in downregulating AKT/Survivin signaling in A549 cells. The effect of artesunate on the proliferation of A549 cells was determined by CCK-8 assay and colony formation assay; its effect on A549 cell apoptosis was evaluated by lactate dehydrogenase (LDH) release assay. The role of artesunate on the activation of AKT/Survivin signaling was analyzed by western blot and quantitative QPCR. Finally, we used two mouse tumor models to investigate the function of artesunate on the in vivo growth of lung cancer cells. Artesunate treatment caused significant growth inhibition and apoptosis in A549 cells. Mechanistically, artesunate downregulated the activation of AKT/Survivin signaling. In agreement, hyperactivation of AKT signaling restored artesunate-induced growth inhibition in A549 cells. In mouse lung cancer models, artesunate administration significantly reduced the growth of A549 cells and LLC cells in nude mice and immunocompetent mice, respectively. Our findings suggest that artesunate serves as a potential tumor suppressor in lung cancer and hopefully can provide new insight into the development of therapeutic strategies in the clinical lung cancer treatment.

Intelligent Nanoplatform with Multi Therapeutic Modalities for Synergistic Cancer Therapy

Chemodynamic therapy (CDT) has attracted increasing attention in tumor treatment but is limited by insufficient endogenous H₂O₂. Moreover, it is challenging for monotherapy to achieve a satisfactory outcome due to tumor complexity. Herein, we developed an intelligent nanoplatform that could respond to a tumor microenvironment to induce efficient CDT without complete dependence on H₂O₂ and concomitantly generate chemotherapy and oncosis therapy (OT). The nanoplatform was constructed by a calcium- and iron-doped mesoporous silica nanoparticle (CFMSN) loaded with dihydroartemisinin (DHA). After entering into cancer cells, the nanoplatform could directly convert the intracellular H₂O₂ into toxic •OH due to the Fenton-like activity of CFMSN. Meanwhile, the acidic microenvironment and endogenous chelating molecules triggered Ca²⁺ and Fe³⁺ release from the nanoplatform, causing particle collapse with accompanying DHA release for chemotherapy. Simultaneously, the released Ca²⁺ induced intracellular Ca²⁺-overloading for OT, which was further enhanced by DHA, while the released Fe³⁺ was reduced to reactive Fe²⁺ by intracellular glutathione, guaranteeing efficient Fenton reaction-mediated CDT. Moreover, Fe²⁺ cleaved the peroxy bonds of DHA to generate C-centered radicals to further amplify CDT. Both in vitro and in vivo results confirmed that the nanoplatform exhibited excellent anticancer efficacy via the synergistic effect of multi therapeutic modalities, which is extremely promising for high-efficient cancer therapy.

Combination of artesunate and WNT974 induces KRAS protein degradation by upregulating E3 ligase ANACP2 and β-TrCP in the ubiquitin–proteasome pathway

Background

KRAS mutation is one of the dominant gene mutations in colorectal cancer (CRC). Up to present, targeting KRAS for CRC treatment remains a clinical challenge. WNT974 (LGK974) is a porcupine inhibitor that interferes Wnt signaling pathway. Artesunate (ART) is a water-soluble semi-synthetic derivative of artemisinin.

Methods

The synergistic effect of ART and WNT974 combination in reducing CRC cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RT-PCR was utilized for the mRNA levels of KRAS, CUL7, ANAPC2, UBE2M, RNF123, SYVN1, or β-TrCP. Western blot assay was utilized for the protein levels of NRAS, HRAS, KRAS, ANAPC2, β-TrCP, GSK-3β, p-Akt (Ser473), t-Akt, p-PI3K (Tyr458), t-PI3K, p-mTOR (Ser2448), t-mTOR. Xenograft mouse model assay was performed for the anti-CRC effect of combination of ART and WNT974 in vivo. IHC assay was utilized for the levels of KRAS, β-TrCP, GSK-3β or ANAPC2 in tumor tissues.

Results

Our study shows that the combination of WNT974 and ART exhibits synergistic effect in reducing CRC growth. The combination treatment significantly reduces KRAS protein level and activity in CRC cells. Interestingly, the combination treatment increases E3 ligases ANAPC2 expression. Our data show that overexpression of ANAPC2 significantly reduces KRAS protein levels, which is reversed by MG132. Knockdown of ANAPC2 in CRC abolishes the combination treatment-reduce KRAS expression. Besides, the treatment also increases the expressions of GSK-3β and E3 ligase β-TrCP that is known to degrade GSK-3β-phosphorylated KRAS protein. Knockdown of β-TrCP- and inhibition of GSK-3β abolish the combination treatment-induce KRAS ubiquitination and reduction in expression. Last but not least, combination treatment suppresses PI3K/Akt/m-TOR signaling pathway.

Conclusions

Our data clearly show that the combination treatment significantly enhances KRAS protein degradation via the ubiquitination ubiquitin–proteasome pathway, which is also demonstrated in xenograft mouse model. The study provides strong scientific evidence for the development of the combination of WNT974 and ART as KRAS-targeting therapeutics for CRC treatment.

Biological Evaluation in Resistant Cancer Cells and Study of Mechanism of Action of Arylvinyl-1,2,4-Trioxanes

1,2,4-trioxane is a pharmacophore, which possesses a wide spectrum of biological activities, including anticancer effects. In this study, the cytotoxic effect and anticancer mechanism of action of a set of 10 selected peroxides were investigated on five phenotypically different cancer cell lines (A549, A2780, HCT8, MCF7, and SGC7901) and their corresponding drug-resistant cancer cell lines. Among all peroxides, only 7 and 8 showed a better P-glycoprotein (P-gp) inhibitory effect at a concentration of 100 nM. These in vitro results were further validated by in silico docking and molecular dynamic (MD) studies, where compounds 7 and 8 exhibited docking scores of −7.089 and −8.196 kcal/mol, respectively, and remained generally stable in 100 ns during MD simulation. Further experiments revealed that peroxides 7 and 8 showed no significant effect on ROS accumulations and caspase-3 activity in A549 cells. Peroxides 7 and 8 were also found to decrease cell membrane potential. In addition, peroxides 7 and 8 were demonstrated to oxidize a flavin cofactor, possibly elucidating its mechanism of action. In conclusion, apoptosis induced by 1,2,4-trioxane was shown to undergo via a ROS- and caspase-3-independent pathway with hyperpolarization of cell membrane potential.

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.

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.

Targeted Lipid Nanoparticles Encapsulating Dihydroartemisinin and Chloroquine Phosphate for Suppressing the Proliferation and Liver Metastasis of Colorectal Cancer

Antimalarial drugs Dihydroartemisinin (DHA) and chloroquine phosphate (CQ) exhibit evident anti-cancer activity, particularly as combination therapy. DHA and CQ combination therapy has been proved to exhibit higher cytotoxic effect in tumor cells and lower toxicity to normal cells than combination of artemisinin derivatives (ARTs) and anticancer chemotherapy drugs. However, different physiochemical properties of DHA and CQ, leading to distinctive in vivo outcomes, considerably limited their synergistic effect in cancer treatment. Herein, we developed a lipid nanoparticle (LNP) for co-delivery of DHA and CQ to inhibit proliferation and metastasis of colorectal cancer. Considering the beneficial effects of acid/reactive oxide species (ROS)-sensitive phospholipids and targeting ligands for colorectal cancer cells, an RGD peptide-modified pH/ROS dual-sensitive LNP loaded with DHA and CQ (RLNP/DC) was prepared. It exhibited optimal cytotoxicity and suppression of invasion and metastasis in HCT116 cells in vitro, attributable to irreversible upregulation of intracellular ROS levels, downregulation of VEGF expression, and upregulation of paxillin expression. A mouse model of orthotopic metastasis of colorectal cancer was established to evaluate anti-proliferation and anti-metastasis effects of RLNP/DC in vivo. Thus, an optimized nanoplatform for DHA and CQ combination therapy was developed in this study that offered potential antitumor efficacy against colorectal cancer.

1,2,3-Triazole tethered 1,2,4‑trioxane trimer induces apoptosis in metastatic cancer cells and inhibits their proliferation, migration and invasion

Artemisinin (ART) has been in use against different cancer cells and its derivatives and conjugates are more cytotoxic to iron-rich cancer cells. It is desirable to develop easily achievable synthetic 1,2,4-trioxanes having the same pharmacophore as that of ART. To explore more efficient compounds, a 1,2,3-triazole tethered 1,2,4‑trioxane trimer (4T) was synthesized and the anti-cancer effects of ART and 4T on MDA-MB-435 and MDA-MB-231 cells were investigated concerning regulation of osteopontin (OPN) expression, which is associated with cancer progression and malignancy. ¹H NMR and ¹³C NMR, oxidative stress analysis, flow cytometry, western blot, Real-Time PCR, transfections, luciferase assay, cell viability, proliferation, migration and chemotactic invasion assays were used in this study. It was observed that the 4T induced apoptosis by inhibiting Bcl-2 (~0.6-fold) and cleavage of caspase-3 (intrinsic pathway) in these metastatic cancer cells, and also reduced colony formation, migration and invasion of these cancer cells. The treatment of 4T decreased the reduced glutathione level and increased the activities of glucose-6-phosphate dehydrogenase and glutathione reductase in the 4T treated cancer cells as compared to their respective controls. Further, the expression of OPN was diminished (~0.5-fold) by the 4T in these cell lines. It was also observed that the key mitogen-activated protein kinase pathway proteins, mitogen-activated protein kinase kinase1/2 (~1.8-fold) and extracellular signal-regulated kinase1/2 (~16-fold), were also activated following the treatment of the 4T. However, the phosphorylated c-Jun level, a component of activator protein-1, was significantly reduced in these cancer cells upon 4T treatment. Taken together, we hypothesize that 4T may be useful for controlling cancer progression and malignancy.

Ferroptosis: A Novel Mechanism of Artemisinin and its Derivatives in Cancer Therapy

BACKGROUND

Artemisinin is a sesquiterpene lactone compound with a special peroxide bridge that is tightly linked to the cytotoxicity involved in fighting malaria and cancer. Artemisinin and its derivatives (ARTs) are considered to be potential anticancer drugs that promote cancer cell apoptosis, induce cell cycle arrest and autophagy, inhibit cancer cell invasion and migration. Additionally, ARTs significantly increase intracellular Reactive Oxygen Species (ROS) in cancer cells, which result in ferroptosis, a new form of cell death, depending on the ferritin concentration. Ferroptosis is regarded as a cancer suppressor and as well as considered a new mechanism for cancer therapy.

METHODS

The anticancer activities of ARTs and reference molecules were compared by literature search and analysis. The latest research progress on ferroptosis was described, with a special focus on the molecular mechanism of artemisinin-induced ferroptosis.

RESULTS

Artemisinin derivatives, artemisinin-derived dimers, hybrids and artemisinin-transferrin conjugates, could significantly improve anticancer activity, and their IC50 values are lower than those of reference molecules such as doxorubicin and paclitaxel. The biological activities of linkers in dimers and hybrids are important in the drug design processes. ARTs induce ferroptosis mainly by triggering intracellular ROS production, promoting the lysosomal degradation of ferritin and regulating the System Xc-/Gpx4 axis. Interestingly, ARTs also stimulate the feedback inhibition pathway.

CONCLUSION

Artemisinin and its derivatives could be used in the future as cancer therapies with broader applications due to their induction of ferroptosis. Meanwhile, more attention should be paid to the development of novel artemisinin-related drugs based on the mechanism of artemisinininduced ferroptosis.

Artemisinin-type drugs for the treatment of hematological malignancies

Qinghaosu, known as artemisinin (ARS), has been for over two millennia, one of the most common herbs prescribed in traditional Chinese medicine (TCM). ARS was developed as an antimalarial drug and currently belongs to the established standard treatments of malaria as a combination therapy worldwide. In addition to the antimalarial bioactivity of ARS, anticancer activities have been shown both in vitro and in vivo. Like other natural products, ARS acts in a multi-specific manner also against hematological malignancies. The chemical structure of ARS is a sesquiterpene lactone, which contains an endoperoxide bridge essential for activity. The main mechanism of action of ARS and its derivatives (artesunate, dihydroartemisinin, artemether) toward leukemia, multiple myeloma, and lymphoma cells comprises oxidative stress response, inhibition of proliferation, induction of various types of cell death as apoptosis, autophagy, ferroptosis, inhibition of angiogenesis, and signal transducers, as NF-κB, MYC, amongst others. Therefore, new pharmaceutically active compounds, dimers, trimers, and hybrid molecules, could enhance the existing therapeutic alternatives in combating hematologic malignancies. Owing to the high potency and good tolerance without side effects of ARS-type drugs, combination therapies with standard chemotherapies could be applied in the future after further clinical trials in hematological malignancies.

Dihydroartemisinin Inhibits the Proliferation, Colony Formation and Induces Ferroptosis of Lung Cancer Cells by Inhibiting PRIM2/SLC7A11 Axis

Objective

Lung cancer is the first leading cause of cancer-related deaths both worldwide and in China and threatens human health and quality of life. New drugs and therapeutic methods are urgently needed. Our study evaluated the roles of dihydroartemisinin (DHA) in lung cancer and further explored its underlying mechanisms.

Methods

CCK-8, colony formation and trypan blue exclusion assays were used to detect the cell viability, colony formation ability and cell death. qRT-PCR and Western blotting assays were applied to analyze the expressions of key molecules.

Results

DHA inhibited the proliferation and colony formation abilities and enhanced the cell death and induced ferroptosis of lung NCI-H23 and XWLC-05 cancer cells. DHA reduced PRIM2 expression and silencing PRIM2 mimicked the inhibitory roles on proliferation and colony formation and promotive roles on cell death and ferroptosis of DHA in lung NCI-H23 and XWLC-05 cancer cells. We further found that DHA treatment and loss of PRIM2 reduced the GSH level and increased the cellular lipid ROS and mitochondrial MDA levels, and further downregulated the expressions of SLC7A11 and β-catenin in lung cancer cells, respectively. Exogenetic overexpression of PRIM2 recovered the inhibitory effects of DHA on proliferation and colony formation in lung NCI-H23 cancer cells, meanwhile loss of PRIM2 sensitizes NCI-H23 cells to DHA therapy. In vivo experiment further showed that DHA treatment significantly suppressed the tumor growth and downregulated PRIM2 and SLC7A11.

Conclusion

Our study suggested that DHA inhibited the proliferation, colony formation and enhanced cell death and induced ferroptosis of lung cancer cells by inactivating PRIM2/SLC7A11 axis. Loss of PRIM2 induced ferroptosis might developed to be a novel therapeutic method in lung cancer therapy.

Heme-Dependent ER Stress Apoptosis: A Mechanism for the Selective Toxicity of the Dihydroartemisinin, NSC735847, in Colorectal Cancer Cells

Colorectal cancer (CRC) is a leading cause of cancer death in the United States. Artemisinin derivatives, including the dihydroartemisinin (DHA) monomers, are widely used as clinical agents for the treatment of malaria. Numerous studies demonstrate that these molecules also display antineoplastic activity with minimal toxicity. Of interest, dimeric DHA molecules are more active than their monomeric counterparts. Our previous data showed that the DHA dimer, NSC735847, was a potent inducer of death in different cancer cell types. However, the mechanism of action and activity of NSC735847 in colon cancer cells was not explored. The present study investigated the anticancer activity of NSC735847 and four structurally similar analog in human tumorigenic (HT-29 and HCT-116) and non-tumorigenic (FHC) colon cell lines. NSC735847 was more cytotoxic toward tumorigenic than non-tumorigenic colonocytes. In addition, NSC735847 exhibited greater cytotoxicity and tumor selectivity than the NSC735847 derivatives. To gain insight into mechanisms of NSC735847 activity, the requirement for endoplasmic reticulum (ER) stress and oxidative stress was tested. The data show that ER stress played a key role in the cytotoxicity of NSC735847 while oxidative stress had little impact on cell fate. In addition, it was observed that the cytotoxic activity of NSC735847 required the presence of heme, but not iron. The activity of NSC735847 was then compared to clinically utilized CRC therapeutics. NSC735847 was cytotoxic toward colon tumor cells at lower concentrations than oxaliplatin (OX). In addition, cell death was achieved at lower concentrations in colon cancer cells that were co-treated with folinic acid (Fol), 5-FU (F), and NSC735847 (FolFNSC), than Fol, F, and OX (FolFOX). The selective activity of NSC735847 and its ability to induce cytotoxicity at low concentrations suggest that NSC735847 may be an alternative for oxaliplatin in the FolFOX regimen for patients who are unable to tolerate its adverse effects.

Evaluation of artesunate for the treatment of adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive disease caused by infection with human T-cell leukemia virus type 1 (HTLV-1). Successful treatment is limited by resistance to chemotherapies. Therefore, there is an urgent need to develop novel effective strategies. Artesunate (ART), a widely used antimalarial compound, has been shown to exert cytotoxicity. Here, we aimed to assess the anti-ATLL activities of ART and to elucidate the possible molecular mechanisms involved in this effect. Compared with uninfected T cells, HTLV-1-infected T-cell lines were sensitive to ART-induced cytotoxicity. ART caused cell cycle arrest at G₁ and/or G₂/M phases, which was associated with decreased expression of cyclin dependent kinase 1/2/4/6, cyclin B1/D2/E and c-Myc, and increased expression of p21. ART-induced apoptosis corresponded to activation of caspase-8/9/3; decreased expression of Bcl-xL, Bcl-2, myeloid cell leukemia-1, survivin, X-linked inhibitor of apoptosis protein and cellular inhibitor of apoptosis 1/2; and increased expression of Bak. ART increased intracellular reactive oxygen species and activation of the DNA damage marker γ-H2AX. Moreover, ART-induced cytotoxicity was partly reversed by treatment with a reactive oxygen species scavenger, iron chelator, and necroptosis or ferroptosis inhibitor, suggesting the involvement of caspase-dependent and -independent lethal pathways. These effects were correlated with inhibition of nuclear factor-κB and activator protein-1 signaling through dephosphorylation of IκBα, IκB kinase (IKK) α and IKKβ, and decreased expression of JunB and JunD. Importantly, intraperitoneal injection with ART lowered tumor burden in an ATLL murine model. These preclinical results provide a rationale for evaluating the efficacy of ART in patients with ATLL.

Unexpected mechanism of colitis amelioration by artesunate, a natural product from Artemisia annua L

BACKGROUND

Artemisinin and its derivatives are known to exert immunosuppressive effects through modulating adaptive immunity. We investigated a novel role of artesunate in regulating innate immunity, including both macrophages (MΦ) and dendritic cells (DCs), which are known to involve in DSS-induced colitis.

METHODS

Effects of artesunate on innate immunity were extensively evaluated, both in vivo using DSS-colitis model with WT and T cell-deficient RAG mice (RAG^-/-) and in vitro using cell culture models, including in-depth analyses of MΦ/DC apoptosis and cytokine expression by flow cytometry, Western blot, or immunohistology.

RESULTS

Unexpectedly, artesunate significantly ameliorated the DSS colitis of both WT and RAG1^-/- mice with similar potency, suggesting a mechanism that involves primarily innate rather than adaptive immunity. In vivo mechanistic studies revealed that artesunate markedly induced apoptosis of lamina propria MΦs and DCs and suppressed mucosal TNF-α and IL-12p70 in DSS-colitis. In vitro, artesunate potently induced a dose- and time-dependent apoptosis of murine bone marrow-derived DCs and human THP-1 MΦs, through the caspases-9-mediated intrinsic pathway. Artesunate significantly decreased the secretion of IL-12p40/70 by DCs and TNF-α by MΦs. Furthermore, a combination of artesunate with an immunomodulator (methotrexate/triptolide/azathioprine) exhibited superior potency in promoting apoptosis of MΦs than any individual drug alone.

CONCLUSIONS

The immunomodulatory mechanism of artesunate in colitis involves a novel and potent induction of the intrinsic apoptosis pathway of proliferating MΦs and DCs and suppression of IL-12 and TNF-α. Artemisinin and its derivatives are promising new therapeutic alternatives for IBD, either alone or in combination with other immunomodulators.

Drug Repurposing in the Development of Anticancer Agents

BACKGROUND

Research into repositioning known drugs to treat cancer other than the originally intended disease continues to grow and develop, encouraged in part, by several recent success stories. Many of the studies in this article are geared towards repurposing generic drugs because additional clinical trials are relatively easy to perform and the drug safety profiles have previously been established.

OBJECTIVE

This review provides an overview of anticancer drug development strategies which is one of the important areas of drug restructuring.

METHODS

Repurposed drugs for cancer treatments are classified by their pharmacological effects. The successes and failures of important repurposed drugs as anticancer agents are evaluated in this review.

RESULTS AND CONCLUSION

Drugs could have many off-target effects, and can be intelligently repurposed if the off-target effects can be employed for therapeutic purposes. In cancer, due to the heterogeneity of the disease, often targets are quite diverse, hence a number of already known drugs that interfere with these targets could be deployed or repurposed with appropriate research and development.

Exogenous Iron Increases Fasciocidal Activity and Hepatocellular Toxicity of the Synthetic Endoperoxides OZ78 and MT04

The synthetic peroxides OZ78 and MT04 recently emerged as fasciocidal drug candidates. However, the effect of iron on fasciocidal activity and hepatocellular toxicity of these compounds is unknown. We investigated the in vitro fasciocidal activity and hepatocellular toxicity of OZ78 and MT04 in absence and presence of Fe(II)chloride and hemin, and conducted a toxicological study in mice. Studies were performed in comparison with the antimalarial artesunate (AS), a semisynthetic peroxide. Fasciocidal effects of OZ78 and MT04 were confirmed and enhanced by Fe²⁺ or hemin. In HepG2 cells, AS reduced cellular ATP and impaired membrane integrity concentration-dependently. In comparison, OZ78 or MT04 were not toxic at 100 µM and reduced the cellular ATP by 13% and 19%, respectively, but were not membrane-toxic at 500 µM. The addition of Fe²⁺ or hemin increased the toxicity of OZ78 and MT04 significantly. AS inhibited complex I, II, and IV of the mitochondrial electron transport chain, and MT04 impaired complex I and II, whereas OZ78 was not toxic. All three compounds increased cellular reactive oxygen species (ROS) concentration-dependently, with a further increase by Fe²⁺ or hemin. Mice treated orally with up to 800 mg OZ78, or MT04 showed no relevant hepatotoxicity. In conclusion, we confirmed fasciocidal activity of OZ78 and MT04, which was increased by Fe²⁺ or hemin. OZ78 and MT04 were toxic to HepG2 cells, which was explained by mitochondrial damage associated with ROS generation in the presence of iron. No relevant hepatotoxicity was observed in mice in vivo, possibly due to limited exposure and/or high antioxidative hepatic capacity.

Artemisinin suppresses hepatocellular carcinoma cell growth, migration and invasion by targeting cellular bioenergetics and Hippo-YAP signaling

The primary liver cancer (PLC) is one of the leading causes of cancer-related death worldwide. The predominant form of PLC is hepatocellular carcinoma (HCC), which accounts for about 85% of all PLC. Artemisinin (ART) was clinically used as anti-malarial agents. Recently, it was demonstrated to inhibit cell growth and migration in multiple cancer types. However, the molecular mechanism underlying these anti-cancer activity remains largely unknown. Herein, it is discovered that ART dramatically suppresses HCC cell growth in vitro through arresting cell cycle progression, and represses cell migration and invasion via regulating N-cadherin-Snail-E-cadherin axis. In addition, the disruption of cellular bioenergetics contributed to ART-caused cell growth, migration and invasion inhibition. Moreover, ART (100 mg/kg, intraperitoneally) substantially inhibits HCC xenograft growth in vivo. Importantly, Hippo-YAP signal transduction is remarkably inactivated in HCC cells upon ART administration. Collectively, these data reveal a novel mechanism of ART in regulating HCC cell growth, migration, and invasion, which indicates that ART could be considered as a potential drug for the treatment of HCC.

Artesunate activates the ATF4-CHOP-CHAC1 pathway and affects ferroptosis in Burkitt's Lymphoma

Currently, there is no effective treatment for Burkitt's lymphoma in patients aged above 60 years, and thus research on effective treatment options for Burkitt's lymphoma has been gaining increasing attention. Artesunate has been identified as a novel effective growth suppressor in Burkitt's lymphoma. Here, we utilized molecular biology, transcriptome analysis, and other techniques to study artesunate-induced death of the Burkitt's lymphoma cells DAUDI and CA-46, the effect of artesunate on gene expression in DAUDI and CA-46 cells, and the effect of artesunate-induced ATF4-CHOP-CHAC1 pathway on ferroptosis. We also studied the inhibitory effects and ferroptosis induction of artesunate on CA-46 cells in mouse xenografts. Results showed that artesunate induced ferroptosis in DAUDI and CA-46 cells, as evidenced by the protective effect of liproxstatin-1, ferrostatin-1, and desferoxamine, resulting in an endoplasmic reticulum stress response, activation of the ATF4-CHOP-CHAC1 pathway enhanced ferroptosis in DAUDI and CA-46 cells. A mouse-transplanted tumor model showed that artesunate can inhibit the proliferation and induce ferroptosis of CA-46 cells in vivo. This study provides a novel perspective for the development of drugs against different types of Burkitt's lymphomas.

Dihydroartemisinin and doxorubicin co-loaded Soluplus®-TPGS mixed micelles: formulation characterization, cellular uptake, and pharmacodynamic studies

Clinically, co-delivery of chemotherapeutics has been limited by poor water-solubility and severe systemic toxicity. This study was aimed at integrating the merits of combination chemotherapy and mixed micellar technology and demonstrating the anticancer potential of doxorubicin (DOX) and dihydroartemisinin (DHA) co-loaded Soluplus^®-TPGS mixed micellar system. In this study, physiochemically stable multidrug loaded mixed micelles were successfully prepared, encapsulation efficiencies of DOX and DHA were as high as 90%, and the average diameter of the micelles was 64.27 nm. The cellular uptake of DOX from the mixed micelles increased by 1.3 and 1.2 times for MCF-7 and MCF-7/ADR cell lines, respectively. The micelles were more cytotoxic than free DHA-DOX. Surprisingly, the co-loaded mixed micelles exhibited higher antitumor activity, while the systemic toxicity was reduced during the treatment. Therefore, the DOX and DHA mixed micelle might be a potential, effective, and less toxic drug-delivery system for cancer therapy.

Effect of dihydroartemisinin on epithelial-to-mesenchymal transition in canine mammary tumour cells

Epithelial-to-mesenchymal transition (EMT) is a process by which epithelial cells acquire mesenchymal properties, generating metastases. Dihydroartemisinin (DHA) exhibits potent anti-cancer activities. CMTs is a potential suitable model for studies in human breast cancer research. In the present study, we separated DHA-untreated cells from CMTs cells to be a control group, the rest of the CMTs cells treated by DHA which were composed of three concentrations 5,10 as well as 20 μM. After that we cultivate the cells severally under the condition of 24, 48 and 72 h at 37 °C. CMTs cells were evaluated by Cell viability assay, Wound healing assay, Invasion assay and RT-PCR analysis for the expression of Slug, ZEB1, ZEB2 and Twist. Our results showed that DHA increased the inhibitory rate of CMTs cell and restrain TGF-β1-induced migration and invasion of cells in a time and concentration reliant manner efficaciously. Our result also show DHA inhibits the expression of Slug, ZEB1, ZEB2 and Twist at the mRNA in vitro, the media concentration DHA (10 μM) decreased the expression level of the Slug, ZEB1, ZEB2 mRNA significantly. In conclusion, DHA inhibits canine mammary tumours cells migration and invasiveness by regulating the expression of EMT-related genes.

Synthesis of artemisinin derived glycoconjugates inspired by click chemistry

Cu(i)-catalysed click reactions between β-propargylated dihydroartemisinin and azido sugars were carried out to furnish artemisinin based glycoconjugates.

Current scenario of artemisinin and its analogues for antimalarial activity

Human malaria, one of the most striking, reemerging infectious diseases, is caused by several types of Plasmodium parasites. Whilst advances have been made in lowering the numbers of cases and deaths, it is clear that a strategy based solely on disease control year on year, without reducing transmission and ultimately eradicating the parasite, is unsustainable. Natural products have served as a template for the design and development of antimalarial drugs currently in the clinic or in the development phase. Artemisinin combine potent, rapid antimalarial activity with a wide therapeutic index and an absence of clinically important resistance. The alkylating ability of artemisinin and its semi-synthetic analogues toward heme related to their antimalarial efficacy are underlined. Although impressive results have already been achieved in malaria research, more systematization and concentration of efforts are required if real breakthroughs are to be made. This review will concisely cover the clinical, preclinical antimalarial and current updates in artemisinin based antimalarial drugs. Diverse classes of semi-synthetic analogs of artemisinin reported in the last decade have also been extensively studied. The experience gained in this respect is discussed.

The leishmanicidal activity of artemisinin is mediated by cleavage of the endoperoxide bridge and mitochondrial dysfunction

Endoperoxides kill malaria parasites via cleavage of their endoperoxide bridge by haem or iron, leading to generation of cytotoxic oxygen-centred radicals. In view of the Leishmania parasites having a relatively compromised anti-oxidant defense and high iron content, this study aims to establish the underlying mechanism(s) accounting for the apoptotic-like death of Leishmania promastigotes by artemisinin, an endoperoxide. The formation of reactive oxygen species was confirmed by flow cytometry and was accompanied by inhibition of mitochondrial complexes I-III and II-III. However, this did not translate into a generation of mitochondrial superoxide or decrease in oxygen consumption, indicating minimal impairment of the electron transport chain. Artemisinin caused depolarization of the mitochondrial membrane along with a substantial depletion of adenosine triphosphatase (ATP), but it was not accompanied by enhancement of ATP hydrolysis. Collectively, the endoperoxide-mediated radical formation by artemisinin in Leishmania promastigotes was the key step for triggering its antileishmanial activity, leading secondarily to mitochondrial dysfunction indicating that endoperoxides represent a promising therapeutic strategy against Leishmania worthy of pharmacological consideration.

Artemisinin and Its Synthetic Derivatives as a Possible Therapy for Cancer

To assess the possibility of using the antimalarial drug artemisinin and its synthetic derivatives as antineoplastic drugs. A Pubmed and Google Scholar (1983–2018) search was performed using the terms artemisinin, cancer, artesunate and Artemisia annua. Case reports and original research articles, review articles, and clinical trials in both humans and animals were evaluated. Both in vitro and in vivo clinical trials and case reports have shown promising activity of the artemisinin drug derivatives in treating certain types of cancer. However, the reported articles are few, and therefore not statistically significant. The minimal toxicity shown in clinical trials and case reports, along with the selective cytotoxic activity of the compounds, make them possible cancer therapies due to the emerging evidence of the drug’s effectiveness.

A phase I study of intravenous artesunate in patients with advanced solid tumor malignancies

PURPOSE

The artemisinin class of anti-malarial drugs has shown significant anti-cancer activity in pre-clinical models. Proposed anti-cancer mechanisms include DNA damage, inhibition of angiogenesis, TRAIL-mediated apoptosis, and inhibition of signaling pathways. We performed a phase I study to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs) of intravenous artesunate (IV AS).

METHODS

Patients were enrolled in an accelerated titration dose escalation study with planned dose levels of 8, 12, 18, 25, 34 and 45 mg/kg given on days 1 and 8 of a 21-day cycle. Toxicities were assessed using the NCI CTCAE (ver. 4.0), and response was assessed using RECIST criteria (version 1.1). Pharmacokinetic (PK) studies were performed during cycle 1.

RESULTS

A total of 19 pts were enrolled, 18 of whom were evaluable for toxicity and 15 were evaluable for efficacy. DLTs were seen at dosages of 12 (1 of 6 patients), 18 (1 of 6) and 25 mg/kg (2 of 2), and were neutropenic fever (Gr 4), hypersensitivity reaction (Gr 3), liver function test abnormalities (Gr 3/4) along with neutropenic fever, and nausea/vomiting (Gr 3) despite supportive care. The MTD was determined to be 18 mg/kg. No responses were observed, while four patients had stable disease, including three with prolonged stable disease for 8, 10, and 11 cycles, for a disease control rate of 27%. PK parameters of AS and its active metabolite, dihydroartemisinin (DHA), correlated with dose.

CONCLUSION

The MTD of intravenous artesunate is 18 mg/kg on this schedule. Treatment was well tolerated. Modest clinical activity was seen in this pre-treated population. CLINICALTRIALS.

GOV IDENTIFIER

NCT02353026.

Dihydroartemisinin Induces Endoplasmic Reticulum Stress-Mediated Apoptosis in HepG2 Human Hepatoma Cells

Aims and Background

Previous studies showed that dihydroartemisinin (DHA) possessed antitumor activity in many human tumor cells through the induction of apoptosis. The aim of this study was to investigate the effects of DHA on apoptosis in the human hepatocellular carcinoma cell line HepG2 and the possible molecular mechanisms involved.

Methods

The inhibitory effect of DHA on HepG2 cells was measured by MTT assay. The percentage of apoptotic cells was detected by flow cytometry with double staining of fluorescein isothiocyanate-annexin V/propidium iodide. The intracellular production of reactive oxygen species (ROS) and intracellular Ca2+ concentration ([Ca2+]i) were detected by fluorescence spectrophotometry. Protein expression of GADD153, Bcl-2 and Bax in HepG2 cells was examined by Western blot and immunocytochemistry.

Results

DHA significantly inhibited proliferation of HepG2 cells in a dose- and time-dependent manner. The apoptosis rates in HepG2 cells treated with 0, 50, 100 and 200 mol/L DHA for 24 hours were 2.53 ± 0.88%, 24.85 ± 3.63%, 35.27 ± 5.92% and 48.53 ± 7.76%, respectively. Compared with the control group, DHA significantly increased ROS generation and [Ca2+]i level (P <0.05), with the generation of ROS preceding the increase in [Ca2+]i. An increase in GADD153 and Bax expression and a decrease in Bcl-2 were observed in DHA-treated cells. Pretreatment with the antioxidant N-acetylcysteine could attenuate the effects of DHA in the experiments.

Conclusion

DHA could inhibit proliferation and induce apoptosis in HepG2 cell lines through increasing the intracellular production of ROS and [Ca2+]i. Endoplasmic reticulum stress-induced apoptosis may contribute to this effect by regulating the expression of GADD153, proapoptotic Bax, and antiapoptotic Bcl-2.

Synthesis of novel 1,2,3-triazole based artemisinin derivatives and their antiproliferative activity

Novel artemisinin-1,2,3-triazole derivatives show significant antiproliferative activity, and induce apoptosis and ROS generation and arrest the cell cycle at the G2/M phase.

Transcriptome analysis of genes associated with breast cancer cell motility in response to Artemisinin treatment

Background

Well-known anti-malarial drug artemisinin exhibits potent anti-cancerous activities. In-vivo and in-vitro studies showed its anti-tumor and immunomodulatory properties signifying it as a potent drug candidate for study. The studies of mechanisms of cell movement are relevant which can be understood by knowing the involvement of genes in an effect of a drug. Although cytotoxicity and anti-proliferative activity of artemisinin is evident, the genes participating in its anti-migratory and reduced invasive effect are not well studied. The present study reports the alteration in the expression of 84 genes involved in cell motility upon artemisinin treatment in MCF-7 breast cancer cells using pathway focused gene expression PCR array. In addition, the effect of artemisinin on epigenetic modifier HDACs is studied.

Methods

We checked the functional stimulus of artemisinin on cell viability, migration, invasion and apoptosis in breast cancerous cell lines. Using qRT-PCR and western blot, we validated the altered expression of relevant genes associated with proliferation, migration, invasion, apoptosis and mammary gland development.

Results

Artemisinin inhibited cell proliferation of estrogen receptor negative breast cancer cells with fewer efficacies in comparison to estrogen receptor positive ones. At the same time, cell viability and proliferation of normal breast epithelial MCF10A cells was un-affected. Artemisinin strongly inhibited cancer cell migration and invasion. Along with orphan nuclear receptors (ERRα, ERRβ and ERRγ), artemisinin altered the ERα/ERβ/PR/Her expression status of MCF-7 cells. The expression of genes involved in the signaling pathways associated with proliferation, migration, invasion and apoptosis was significantly altered which cooperatively resulted into reduced growth promoting activities of breast cancer cells. Interestingly, artemisinin exhibited inhibitory effect on histone deacetylases (HDACs).

Conclusions

Upregulated expression of tumor suppressor genes along with reduced expression of oncogenes significantly associated with growth stimulating signaling pathways in response to artemisinin treatment suggests its efficacy as an effective drug in breast cancer treatment.

Dihydroartemisinin-regulated mRNAs and lncRNAs in chronic myeloid leukemia

Chronic myelocytic leukemia (CML) is characterized by increased and unregulated growth of predominantly myeloid cells in the bone marrow, and accumulation of these cells in blood. We investigated the effects of an anti-malarial drug, dihydroartemisinin (DHA), on K562 CML cells. We identified 34 mRNAs and eight lncRNAs dysregulated following DHA treatment in pure and hemin-induced K562 cells. Up- or downregulation of these potential DHA targets increased with increasing DHA concentration. We also constructed and analyzed a DHA-related mRNA-lncRNA regulation network in K562 cells, and found that four DHA-modulated mRNAs regulated by four lncRNAs participated in the steroid biosynthesis pathway. Some estrogen-related drugs, such as tamoxifen, shared common targets with DHA. We inferred that DHA exerted anti-cancer effects on K562 cells by influencing estrogen levels. Our findings indicate that DHA has potential not only as an anti-malarial drug, but also as an anti-CML chemotherapeutic.

More insights into the pharmacological effects of artemisinin

Artemisinin is one of the most widely prescribed drugs against malaria and has recently received increased attention because of its other potential biological effects. The aim of this review is to summarize recent discoveries of the pharmaceutical effects of artemisinin in basic science along with its mechanistic action, as well as the intriguing results of recent clinical studies, with a focus on its antitumor activity. Scientific evidence indicates that artemisinin exerts its biological activity by generating reactive oxygen species that damage the DNA, mitochondrial depolarization, and cell death. In the present article review, scientific evidence suggests that artemisinin is a potential therapeutic agent for various diseases. Thus, this review is expected to encourage interested scientists to conduct further preclinical and clinical studies to evaluate these biological activities.

Dihydroartemisinin Sensitizes Human Lung Adenocarcinoma A549 Cells to Arsenic Trioxide via Apoptosis

Recent studies have shown that arsenic trioxide (ATO) is an effective anti-cancer drug for treatment of acute promyelocytic leukemia and other types of human cancer. However, we have found that lung cancer cells constantly develop a high level of resistance to ATO. In this study, we have explored a possibility of combination of dihydroartemisinin (DHA) and ATO treatments to reduce ATO resistance of lung cancer cells. We determined the combinatory effects of DHA and ATO on cytotoxicity of human lung adenocarcinoma (A549) cells. We showed that co-exposure to DHA and ATO of A549 cells synergistically increased the cytotoxicity and apoptotic cell death in the cells. We found that the synergistic effect of DHA and ATO in promoting apoptosis mainly resulted from increased cellular level of reactive oxygen species (ROS) and DNA damage. ATO alone only exerted moderate growth inhibitory effects on A549 cells. The results indicate that DHA can significantly sensitize ATO-induced cytotoxicity of A549 lung cancer cells through apoptosis mediated by ROS-induced DNA damage. Interestingly, we found that the combinatory treatment of DHA and ATO did not result in significant adverse effects in normal human bronchial epithelial (HBE) cells. Our results further provide evidence for the potential application of combinatory effects of DHA and ATO as a safe therapy for human lung cancer.

Connexin-43 enhances tumor suppressing activity of artesunate via gap junction-dependent as well as independent pathways in human breast cancer cells

The gap junction (GJ) protein connexin-43 (Cx43) is considered as a tumour suppressor protein for its role in reversing the phenotype of the cancer cells. In this study, we exploited the antitumor property of Cx43 in conjunction with the artesunate (ART), a plant-based active anti-malarial compound. The reactive oxygen species (ROS) generated by ART resulted in DNA damage, which in turn led to DNA damage response by activation of DNA damage repair proteins. GJ deficient MCF-7 cells transfected with Cx43 gene showed an increased sensitivity towards dose-dependent ART treatment and required a significantly lower dose of ART to attain its IC50, as compared to parental cells. This would ultimately result in reduced dose-dependent side effects of ART. The Co-culture experiments involving GJ intercellular communication (GJIC) deficient and GJIC enabled cells, established the transfer of ROS to the neighbouring cancer cells not exposed to ART. The ROS accumulated in the ART-treated cells induced the oxidative damage in neighbouring cells, leading to bystander cell death and inhibition of bystander cell proliferation. Thus, our study revealed that expression of Cx43 helped in reducing the dose-dependent cytotoxicity of ART as well as enhanced the bystander apoptosis of the neighbouring cells.

Artemisinin as an anticancer drug: Recent advances in target profiling and mechanisms of action

Artemisinin and its derivatives (collectively termed as artemisinins) are among the most important and effective antimalarial drugs, with proven safety and efficacy in clinical use. Beyond their antimalarial effects, artemisinins have also been shown to possess selective anticancer properties, demonstrating cytotoxic effects against a wide range of cancer types both in vitro and in vivo. These effects appear to be mediated by artemisinin-induced changes in multiple signaling pathways, interfering simultaneously with multiple hallmarks of cancer. Great strides have been taken to characterize these pathways and to reveal their anticancer mechanisms of action of artemisinin. Moreover, encouraging data have also been obtained from a limited number of clinical trials to support their anticancer property. However, there are several key gaps in knowledge that continue to serve as significant barriers to the repurposing of artemisinins as effective anticancer agents. This review focuses on important and emerging aspects of this field, highlighting breakthroughs in unresolved questions as well as novel techniques and approaches that have been taken in recent studies. We discuss the mechanism of artemisinin activation in cancer, novel and significant findings with regards to artemisinin target proteins and pathways, new understandings in artemisinin-induced cell death mechanisms, as well as the practical issues of repurposing artemisinin. We believe these will be important topics in realizing the potential of artemisinin and its derivatives as safe and potent anticancer agents.