The antimalarial drug artemisinin and its derivatives have been explored as potential anticancer agents, but their underlying mechanisms are controversial. In this study, we found that artemisinin ...compounds can sensitize cancer cells to ferroptosis, a new form of programmed cell death driven by iron-dependent lipid peroxidation. Mechanistically, dihydroartemisinin (DAT) can induce lysosomal degradation of ferritin in an autophagy-independent manner, increasing the cellular free iron level and causing cells to become more sensitive to ferroptosis. Further, by associating with cellular free iron and thus stimulating the binding of iron-regulatory proteins (IRPs) with mRNA molecules containing iron-responsive element (IRE) sequences, DAT impinges on IRP/IRE-controlled iron homeostasis to further increase cellular free iron. Importantly, in both in vitro and a mouse xenograft model in which ferroptosis was triggered in cancer cells by the inducible knockout of GPX4, we found that DAT can augment GPX4 inhibition-induced ferroptosis in a cohort of cancer cells that are otherwise highly resistant to ferroptosis. Collectively, artemisinin compounds can sensitize cells to ferroptosis by regulating cellular iron homeostasis. Our findings can be exploited clinically to enhance the effect of future ferroptosis-inducing cancer therapies.
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New pharmaceutically active compounds can be obtained by modification of existing drugs to access more effective agents in the wake of drug resistance amongst others. To achieve this ...goal the concept of hybridization was established during the last decade. We employed this concept by coupling two artemisinin-derived precursors to obtain dimers or trimers with increased in vitro activity against Plasmodiumfalciparum 3D7 strain, leukemia cells (CCRF-CEM and multidrug-resistant subline CEM/ADR5000) and human cytomegalovirus (HCMV). Dimer 4 (IC50 of 2.6nM) possess superior antimalarial activity compared with its parent compound artesunic acid(3) (IC50 of 9.0nM). Dimer5 and trimers6 and 7 display superior potency against both leukemia cell lines (IC50 up to 0.002μM for CCRF-CEM and IC50 up to 0.20μM for CEM/ADR5000) and are even more active than clinically used doxorubicin (IC50 1.61μM for CEM/ADR5000). With respect to anti-HCMV activity, trimer6 is the most efficient hybrid (IC50 0.04μM) outperforming ganciclovir (IC50 2.6μM), dihydroartemisinin(IC50 >10μM) and artesunic acid (IC50 3.8μM).
The emergence of
Plasmodium falciparum
resistance to artemisinin-based therapy is a major global health challenge. In this report, investigators describe the distribution of K13-propeller ...polymorphisms, the basis of the majority of artemisinin resistance, in 59 countries.
Increased efforts have substantially reduced the global burden of malaria caused by
Plasmodium falciparum,
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but the recent gains are threatened by emerging resistance to artemisinins, the cornerstone of current first-line combination treatment.
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Artemisinins are active against a large range of intraerythrocytic developmental stages, but their usefulness is curtailed by ring-stage resistance.
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Clinical artemisinin resistance, which was first documented in western Cambodia,
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is now prevalent across Southeast Asia and South China.
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Widespread artemisinin resistance would have dramatic consequences, since replacement therapies are limited and threatened by resistance.
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Therapeutic efficacy studies are the standard method . . .
Artemisinin‐based combination therapy (ACT) has been adopted as a strategy to mitigate multidrug resistance to antimalarial monotherapies. ACT combines the rapid and effective but rather short plasma ...half‐life antimalarial action of an artemisinin derivative with a longer acting partner drug. Although the exact mechanisms of action of artemisinins are not well understood, several studies have proposed multiple cellular targets of artemisinins with involvement of reactive oxygen species (ROS). Most of the currently used ACT partner drugs are also known to involve ROS production in their mechanisms of action. This review gives a brief account of the oxidative stress and redox systems in malaria and discusses the context of antimalarial effectiveness of different ACTs compared with monotherapies of the partner drugs. A final account on the Pros and Cons of ACT as a strategy is discussed.
Malaria is characterized with oxidative stress derived from both the parasite's metabolism and the host immune response. Some antimalarial drugs increase oxidative stress. While oxidative stress can help eliminate parasites, it can also exacerbate the pathology. This article reviews oxidative stress in view of the current artemisinin‐based combination therapies in malaria.
Sesquiterpene lactones are of considerable interest due to their potent bioactivities, including cancer cell cytotoxicity and antineoplastic efficacy in in vivo studies. Among these compounds, ...artesunate, dimethylaminoparthenolide, and L12ADT peptide prodrug, a derivative of thapsigargin, are being evaluated in the current cancer clinical or preclinical trials. Based on the structures of several antitumor sesquiterpene lactones, a number of analogues showing greater potency have been either isolated as natural products or partially synthesized, and some potential anticancer agents that have emerged from this group of lead compounds have been investigated extensively. The present review focuses on artemisinin, parthenolide, thapsigargin, and their naturally occurring or synthetic analogues showing potential anticancer activity. This provides an overview of the advances in the development of these types of sesquiterpene lactones as potential anticancer agents, including their structural characterization, synthesis and synthetic modification, and antitumor potential, with the mechanism of action and structure-activity relationships also discussed. It is hoped that this will be helpful in stimulating the further interest in developing sesquiterpene lactones and their derivatives as new anticancer agents.
Six transcription factors of APETALA2/ethylene-response factor (AP2/ERF) family were cloned and analyzed in Artemisia annua. Real-time quantitative polymerase chain reaction (RT-Q-PCR) showed that ...AaORA exhibited similar expression patterns to those of amorpha-4,11-diene synthase gene (ADS), cytochrome P450-dependent hydroxylase gene (CYP71AV1) and double bond reductase 2 gene (DBR2) in different tissues of A. annua.
AaORA is a trichome-specific transcription factor, which is expressed in both glandular secretory trichomes (GSTs) and nonglandular T-shaped trichomes (TSTs) of A. annua. The result of subcellular localization shows that AaORA is targeted to the nuclei and the cytoplasm.
Overexpression and RNA interference (RNAi) of AaORA in A. annua regulated, positively and significantly, the expression levels of ADS, CYP71AV1, DBR2 and AaERF1. The up-regulated or down-regulated expression levels of these genes resulted in a significant increase or decrease in artemisinin and dihydroartemisinic acid. The results demonstrate that AaORA is a positive regulator in the biosynthesis of artemisinin.
Overexpression of AaORA in Arabidopsis thaliana increased greatly the transcript levels of the defense marker genes PLANT DEFENSIN1.2 (PDF1.2), HEVEIN-LIKE PROTEIN (HEL) and BASIC CHITINASE (B-CHI). After inoculation with Botrytis cinerea, the phenotypes of AaORA overexpression in A. thaliana and AaORA RNAi in A. annua demonstrate that AaORA is a positive regulator of disease resistance to B. cinerea.
Artemisinin is an extract from the plant Artemisia annua. With its semi-synthetic derivatives, they form a group of well-known and efficacious antimalarial drugs. Recent studies have documented the ...potential anticancer effect of artemisinin and its derivatives (ARTs). This review summarizes results of preclinical studies, documenting mechanisms of anticancer actions of ARTs and clinical studies focused mainly on efficacy, safety and dose-ranging of ARTs as anticancer chemotherapeutics. The main mechanisms of action of ARTs is the production of reactive oxygen species, inhibition of cell cycle in G
/G
phase, induction of apoptosis and inhibition of angiogenesis. Safety studies have shown no evident toxicity and low incidence of adverse effects. ARTs potential to inhibit growth of solid tumours suggests their application in a neoadjuvant therapy. Dihydroartemisinin and artesunate exhibit chemosensitising effects in vivo in breast, lung, pancreas and glioma cancer cells, proposing the use of ARTs also in combination anticancer therapy.
Artemisia annua L. is used throughout Asia and Africa as tea and press juice to treat malaria and related symptomes (fever, chills). Its active ingredient, artemisinin (ARS), has been developed as ...antimalarial drug and is used worldwide. Interestingly, the bioactivity is not restricted to malaria treatment. We and others found that ARS-type drugs also reveal anticancer in vitro and in vivo. In this review, we give a systematic overview of the literature published over the past two decades until the end of 2016. Like other natural products, ARS acts in a multi-specific manner against tumors. The cellular response of ARS and its derivatives (dihydroartemisinin, artesunate, artemether, arteether) towards cancer cells include oxidative stress response by reactive oxygen species and nitric oxide, DNA damage and repair (base excision repair, homologous recombination, non-homologous end-joining), various cell death modes (apoptosis, autophagy, ferroptosis, necrosis, necroptosis, oncosis), inhibition of angiogenesis and tumor-related signal transduction pathways (e.g. Wnt/β-catenin pathway, AMPK pathway, metastatic pathways, and others) and signal transducers (NF-κB, MYC/MAX, AP-1, CREBP, mTOR etc). ARS-type drugs are at the stairways to the clinics. Several published case reports and pilot phase I/II trials indicate clinical anticancer activity of these compounds. Because of unexpected cases of hepatotoxicity, combinations of ARS-type drugs with complementary and alternative medicines are not recommended, until controlled clinical trials will prove the safety of non-approved combination treatments.
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.
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.
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.
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.
The use of artemisinin-based combination therapies (ACTs), which combine an artemisinin derivative with a partner drug, in the treatment of uncomplicated malaria has largely been responsible for the ...significant reduction in malaria-related mortality in tropical and subtropical regions. ACTs have also played a significant role in the 18% decline in the incidence of malaria cases from 2010 to 2016. However, this progress is seriously threatened by the reduced clinical efficacy of artemisinins, which is characterised by delayed parasitic clearance and a high rate of recrudescence, as reported in 2008 in Western Cambodia. Resistance to artemisinins has already spread to several countries in Southeast Asia. Furthermore, resistance to partner drugs has been shown in some instances to be facilitated by pre-existing decreased susceptibility to the artemisinin component of the ACT. A major concern is not only the spread of these multidrug-resistant parasites to the rest of Asia but also their possible appearance in Sub-Saharan Africa, the continent most affected by malaria, as has been the case in the past with parasite resistance to other antimalarial treatments. It is therefore essential to understand the acquisition of resistance to artemisinins by Plasmodium falciparum to adapt malaria treatment policies and to propose new therapeutic solutions.
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