Anti-angiogenic properties of artemisinin derivatives (Review)

En Route to Targeted Ribosome Editing to Replenish Skin Anchor Protein LAMB3 in Junctional Epidermolysis Bullosa

Severe junctional epidermolysis bullosa is a rare genetic, postpartum lethal skin disease, predominantly caused by nonsense/premature termination codon (PTC) sequence variants in LAMB3 gene. LAMB3 encodes LAMB3, the β subunit of epidermal-dermal skin anchor laminin 332. Most translational reads of a PTC mRNA deliver truncated, nonfunctional proteins, whereas an endogenous PTC readthrough mechanism produces full-length protein at minimal and insufficient levels. Conventional translational readthrough-inducing drugs amplify endogenous PTC readthrough; however, translational readthrough-inducing drugs are either proteotoxic or nonselective. Ribosome editing is a more selective and less toxic strategy. This technique identified ribosomal protein L35/uL29 (ie, RpL35) and RpL35-ligands repurposable drugs artesunate and atazanavir as molecular tools to increase production levels of full-length LAMB3. To evaluate ligand activity in living cells, we monitored artesunate and atazanavir treatment by dual luciferase reporter assays. Production levels of full-length LAMB3 increased up to 200% upon artesunate treatment, up to 150% upon atazanavir treatment, and up to 170% upon combinatorial treatment of RpL35 ligands at reduced drug dosage, with an unrelated PTC reporter being nonresponsive. Proof of bioactivity of RpL35 ligands in selective increase of full-length LAMB3 provides the basis for an alternative, targeted therapeutic route to replenish LAMB3 in severe junctional epidermolysis bullosa.

Berberine Inhibits Endothelial Cell Proliferation via Repressing ERK1/2 Pathway

Abnormal angiogenesis plays a key role in cancer progression. In recent years, anti-angiogenic therapy has attracted increasing attention. Berberine (BBR), the main component extracted from Coptis (Ranunculaceae) rhizome, has an anti-angiogenic effect. However, the underlying mechanisms remain to be elucidated. Endothelial cell proliferation is a pivotal process in angiogenesis. In our research, we observed that BBR specifically downregulated the expression of the extracellular signal-regulated kinase 1/2 (ERK1/2) protein in human umbilical vein endothelial cells (HUVECs). The role of BBR in HUVEC proliferation was then assessed using methylthiazolyldiphenyl-tetrazolium bromide and cell counting Kit-8 (CCK-8) assays. The effect of BBR on the ERK1/2 signaling pathway was evaluated using Western blotting. BBR decreased HUVEC proliferation in a dose-dependent manner and inhibited the expression of phospho-ERK1/2 in HUVECs. PD98059, a specific inhibitor of ERK1/2 signaling, attenuated the BBR-induced decrease in the proliferation of HUVECs. Phorbol 12-myristate 13-acetate, a natural activator of ERK1/2 signaling, did not alter BBR-induced proliferation. In conclusion, BBR inhibited endothelial cell proliferation by suppressing ERK1/2 signaling. These findings may provide a potential therapeutic strategy for suppressing tumor growth.

Effects of natural products on skin inflammation caused by abnormal hormones secreted by the adrenal gland

The cortex of adrenal gland produces glucocorticoid, mineralocorticoid, and androgen. The medulla of adrenal gland secrets catecholamines. These hormones play an important role in regulating blood pressure, metabolism, and homeostasis of glucose or electrolytes. Hypersecretion or hyposecretion by the adrenal gland will cause a complex cascade of hormone effects and lead to diseases, including Addison's disease, Cushing's syndrome, and congenital adrenal cortical hyperplasia. Skin is the largest organ of body. It provides protection and acts as a barrier against external damage factors like infectious organisms, chemicals, and allergens. Endocrinologic disorders often induce cutaneous abnormalities. According to the previous evidences, natural products have the potential properties for attenuating skin disorders and improving dermatologic symptoms by inhibiting inflammation through MAPK or PI3K/AKT-dependent NF-κB pathways. The natural products may also promote skin wound healing by inhibiting the production of matrix metalloproteinase-9. We systematically searched the relevant articles from databases, including PubMed, Embase, and Cochrane library databases, to review the effects of natural products on skin disorders. This article summarized the effects of natural products on skin inflammation caused by abnormal hormone secreted by adrenal gland. And the published papers indicated that natural products might be a potential source for treating skin diseases.

Novel artemisinin derivative FO8643 with anti-angiogenic activity inhibits growth and migration of cancer cells via VEGFR2 signaling

The vascular endothelial growth factor receptor 2 (VEGFR2) is widely recognized as a key effector in angiogenesis and cancer progression and has been considered a critical target for the development of anti-cancer drugs. Artemisinin (ARS) and its derivatives exert profound efficacy in treating not only malaria but also cancer. As a novel ARS-type compound, FO8643 caused significant suppression of the growth of a panel of cancer cells, including both solid and hematologic malignancies. In CCRF-CEM leukemia cells, FO8643 dramatically inhibited cell proliferation coupled with increased apoptosis and cell cycle arrest. Additionally, FO8643 restrained cell migration in the 2D wound healing assay as well as in a 3D spheroid model of human hepatocellular carcinoma HUH-7 cells. Importantly, SwissTargetPrediction predicted VEGFR2 as an underlying target for FO8643. Molecular docking simulation further indicated that FO8643 forms hydrogen bonds and hydrophobic interactions within the VEGFR2 kinase domain. Moreover, FO8643 directly inhibited VEGFR2 kinase activity and its downstream action including MAPK and PI3K/Akt signaling pathways in HUH-7 cells. Encouragingly, FO8643 decreased angiogenesis in the chorioallantoic membrane assay in vivo. Collectively, FO8643 is a novel ARS-type compound exerting potential VEGFR2 inhibition. FO8643 may be a viable drug candidate in cancer therapy.

Co-Targeting Tumor Angiogenesis and Immunosuppressive Tumor Microenvironment: A Perspective in Ethnopharmacology

Tumor angiogenesis is one of the most important processes of cancer deterioration via nurturing an immunosuppressive tumor environment (TME). Targeting tumor angiogenesis has been widely accepted as a cancer intervention approach, which is also synergistically associated with immune therapy. However, drug resistance is the biggest challenge of anti-angiogenesis therapy, which affects the outcomes of anti-angiogeneic agents, and even combined with immunotherapy. Here, emerging targets and representative candidate molecules from ethnopharmacology (including traditional Chinese medicine, TCM) have been focused, and they have been proved to regulate tumor angiogenesis. Further investigations on derivatives and delivery systems of these molecules will provide a comprehensive landscape in preclinical studies. More importantly, the molecule library of ethnopharmacology meets the viability for targeting angiogenesis and TME simultaneously, which is attributed to the pleiotropy of pro-angiogenic factors (such as VEGF) toward cancer cells, endothelial cells, and immune cells. We primarily shed light on the potentiality of ethnopharmacology against tumor angiogenesis, particularly TCM. More research studies concerning the crosstalk between angiogenesis and TME remodeling from the perspective of botanical medicine are awaited.

Progress on the study of the anticancer effects of artesunate

Artesunate (ART) is a derivative of artemisinin that is extracted from the wormwood plant Artemisia annua. ART is an antimalarial drug that has been shown to be safe and effective for clinical use. In addition to its antimalarial properties, ART has been attracting attention over recent years due to its reported inhibitory effects on cancer cell proliferation, invasion and migration. Therefore, ART has a wider range of potential clinical applications than first hypothesized. The aim of the present review was to summarize the latest research progress on the possible anticancer effects of ART, in order to lay a theoretical foundation for the further development of ART as a therapeutic option for cancer.

Recent pharmacological advances in the repurposing of artemisinin drugs

Artemisinins are a family of sesquiterpene lactones originally derived from the sweet wormwood (Artemisia annua). Beyond their well-characterized role as frontline antimalarial drugs, artemisinins have also received increased attention for other potential pharmaceutical effects, which include antiviral, antiparsitic, antifungal, anti-inflammatory, and anticancer activities. With concerted efforts in further preclinical and clinical studies, artemisinin-based drugs have the potential to be viable treatments for a great variety of human diseases. Here, we provide a comprehensive update on recent reports of pharmacological actions and applications of artemisinins outside of their better-known antimalarial role and highlight their potential therapeutic viability for various diseases.

Dihydroartemisinin inhibits endothelial cell migration via the TGF-β1/ALK5/SMAD2 signaling pathway

Anti-angiogenesis therapy is a novel treatment method for malignant tumors. Endothelial cell (EC) migration is an important part of angiogenesis. Dihydroartemisinin (DHA) exhibits strong anti-angiogenic and anti-EC migration effects; however, the underlying molecular mechanisms are yet to be elucidated. The TGF-β1/activin receptor-like kinase 5 (ALK5)/SMAD2 signaling pathway serves an important role in the regulation of migration. The present study aimed to explore the effects of DHA treatment on EC migration and the TGF-β1/ALK5/SMAD2 signaling pathway. The effects of DHA on human umbilical vein EC migration were assessed using wound healing and Transwell assays. The effects of DHA on the TGF-β1/ALK5/SMAD2 signaling pathway were detected using western blotting. DHA exhibited an inhibitory effect on EC migration in the wound healing and Transwell assays. DHA treatment upregulated the expression levels of ALK5 and increased the phosphorylation of SMAD2 in ECs. SB431542 rescued the inhibitory effect of DHA during EC migration. DHA inhibited EC migration via the TGF-β1/ALK5/SMAD2-dependent signaling pathway, and DHA may be a novel drug for the treatment of patients with malignant tumors.

The Potential Roles of Artemisinin and Its Derivatives in the Treatment of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a chronic disease that has become a global public health problem. Studies on T2DM prevention and treatment mostly focus on discovering therapeutic drugs. Artemisinin and its derivatives were originally used as antimalarial treatments. In recent years, the roles of artemisinins in T2DM have attracted much attention. Artemisinin treatments not only attenuate insulin resistance and restore islet ß-cell function in T2DM but also have potential therapeutic effects on diabetic complications, including diabetic kidney disease, cognitive impairment, diabetic retinopathy, and diabetic cardiovascular disease. Many in vitro and in vivo experiments have confirmed the therapeutic utility of artemisinin and its derivatives on T2DM, but no article has systematically demonstrated the specific role artemisinin plays in the treatment of T2DM. This review summarizes the potential therapeutic effects and mechanism of artemisinin and its derivatives in T2DM and associated complications, providing a reference for subsequent related research.

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 expression of von Willebrand factor by downregulation of transcription factor ERG in endothelial cells

Dihydroartemisinin (DHA), a semi‐synthetic derivative of artemisinin, has effective antitumor and anti‐inflammatory actions. von Willebrand factor (vWF), a large multifunctional glycoprotein, has a prominent function in hemostasis and is a key factor in thrombus formation. In addition, vWF has been regarded as a prospective biomarker for the diagnosis of endothelial dysfunction. In our experiment, we observed that 25 μM DHA specifically downregulated the expression of vWF mRNA and protein in human umbilical vein endothelial cells (HUVECs). Further investigations demonstrated that this DHA‐decreased vWF expression was mediated by the transcription factor ERG and not GATA3. Luciferase activity assay confirmed that DHA regulated the ERG binding with the −56 ETS‐binding motif on the human vWF promoter. Thus, the −56 ETS motif on the vWF promoter region regulates the expression of vWF gene which is induced by DHA. Taken together, we proved that DHA decreased the vWF transcription through the downregulation of ERG in HUVECs. As vWF plays a key role in vascular homeostasis, our findings suggest a new role of DHA in vascular diseases.

Artemisinins as Anticancer Drugs: Novel Therapeutic Approaches, Molecular Mechanisms, and Clinical Trials

Artemisinin and its derivatives have shown broad-spectrum antitumor activities in vitro and in vivo. Furthermore, outcomes from a limited number of clinical trials provide encouraging evidence for their excellent antitumor activities. However, some problems such as poor solubility, toxicity and controversial mechanisms of action hamper their use as effective antitumor agents in the clinic. In order to accelerate the use of ARTs in the clinic, researchers have recently developed novel therapeutic approaches including developing novel derivatives, manufacturing novel nano-formulations, and combining ARTs with other drugs for cancer therapy. The related mechanisms of action were explored. This review describes ARTs used to induce non-apoptotic cell death containing oncosis, autophagy, and ferroptosis. Moreover, it highlights the ARTs-caused effects on cancer metabolism, immunosuppression and cancer stem cells and discusses clinical trials of ARTs used to treat cancer. The review provides additional insight into the molecular mechanism of action of ARTs and their considerable clinical potential.

Dihydroartemisinin Prevents Distant Metastasis of Laryngeal Carcinoma by Inactivating STAT3 in Cancer Stem Cells

Background

Accumulating evidence indicates that cancer stem cells (CSCs) are a minor subpopulation of cancer cells that may be the primary source of cancer invasion, migration, and widespread metastasis.

Material/Methods

We investigated the effects of dihydroartemisinin (DHA) on distant metastasis of laryngeal carcinoma and the relevant mechanism. In vitro, we used the Hep-2 human laryngeal squamous carcinoma cell line (Hep-2 cells) to assemble CSCs, using CD133 as the cell surface marker. Our data demonstrate that the CD133⁺ subpopulation of Hep-2 cells has greater invasion and migration capabilities than CD133⁻ cells. We also evaluated the effects of DHA, a newly defined STAT3 inhibitor, on the invasion and migration of CD133⁺ Hep-2 cells under hypoxia and IL-6 stimulation, both of which can activate STAT3 phosphorylation.

Results

CSCs exhibited a significant decrease in the ability of migration and invasion upon the application of DHA, along with simultaneous alterations in related proteins, both in cultured cells and in xenograft tumors. The associated signaling proteins included phosphorylated STAT3 (p-STAT3), matrix metalloproteinase-9 (MMP-9), and E-cadherin, which are closely involved in cancer invasion and metastasis. In vivo, we found that DHA can reduce lung metastasis formation caused by CSCs and prolong survival in mice, and can inhibit STAT3 activation, downregulate MMP-9, and upregulate E-cadherin in lung metastatic tumors.

Conclusions

Taken together, our findings indicate that CSCs possess stronger invasive and metastatic capabilities than non-CSCs, and DHA inhibits invasion and prevents metastasis induced by CSCs by inhibiting STAT3 activation.

Potential applications of artemisinins in ocular diseases

Artemisinin, also named qinghaosu, is a family of sesquiterpene trioxane lactone originally derived from the sweet wormwood plant (Artemisia annua), which is a traditional Chinese herb that has been universally used as anti-malarial agents for many years. Evidence has accumulated during the past few years which demonstrated the protective effects of artemisinin and its derivatives (artemisinins) in several other diseases beyond malaria, including cancers, autoimmune disorders, inflammatory diseases, viral and other parasite-related infections. Recently, this long-considered anti-malarial agent has been proved to possess anti-oxidant, anti-inflammatory, anti-apoptotic and anti-excitotoxic properties, which make it a potential treatment option for the ocular environment. In this review, we first described the overview of artemisinins, highlighting the activity of artemisinins to other diseases beyond malaria and the mechanisms of these actions. We then emphasized the main points of published results of using artemisinins in targeting ocular disorders, including uveitis, retinoblastoma, retinal neurodegenerative diseases and ocular neovascularization. To conclude, we believe that artemisinins could also be used as a promising therapeutic drug for ocular diseases, especially retinal vascular diseases in the near future.

Dihydroartemisinin Induces Endothelial Cell Autophagy through Suppression of the Akt/mTOR Pathway

Aims: Dihydroartemisinin (DHA), a derivative of artemisinin, suppresses angiogenesis by regulating endothelial cell phenotypes. In this study, we investigated the effect of DHA on endothelial cell autophagy and the underlying mechanisms.

Methods: Human umbilical vein endothelial cells (HUVECs) were treated with DHA. Formation of autophagosomes in HUVECs was observed by fluorescence microscope after pcDNA3.1-green fluorescent protein (GFP)-microtubule-associated protein 1 light chain 3 (LC3) plasmids transfection. Dichlorofluorescein diacetate (DCFH-DA) staining was used to detect intracellular reactive oxygen species (ROS). Western blot was performed to detect the protein levels of LC3, p62, beclin 1, autophagy-related protein (Atg) 5, p-Akt (protein kinase B), p-mTOR (mammalian target of rapamycin), p-4E-BP1 (eukaryotic translation initiation factor 4E-binding protein 1), and p-p70S6K (p70 ribosomal S6 kinase).

Results: DHA increased LC3-II and the number of fluorescent GFP-LC3 puncta in HUVECs. Silencing ATG5 by siRNA interference attenuated DHA-induced LC3-II elevation. DHA enhanced ROS production, but pretreatment with antioxidant N-acety-l-cysteine (NAC) failed to reduce DHA-induced autophagy in HUVECs. Pretreatment with PD98059, SP600125 and SB203580, the inhibitors of ERK, JNK, and p38 MAPK, did not reverse autophagy in DHA-treated HUVECs. DHA significantly reduced phosphorylation of Akt, mTOR, p70S6K, 4E-BP1 in HUVECs. Rapamycin, an mTOR antagonist, compromised DHA-induced autophagy.

Conclusion: DHA induces autophagy in HUVECs by inhibition of the Akt/mTOR pathway

Transcription profiling of artemisinin-treated diabetic nephropathy rats using high-throughput sequencing

Artemisinin (Art) plays a renoprotective role in diabetic nephropathy (DN) rats. However, the differential gene expression profile and underlying molecular mechanism of Art treatment in DN is not well understood. We constructed an animal model of DN by injection of streptozotocin (STZ) in rats. We then examined the profile of differentially expressed genes following administration of Art using RNA-sequencing (KANGCH&EN, Shanghai, China). Five genes identified by RNA-sequencing were randomly selected and validated by qRT-PCR. Bioinformatic analyses were performed to study these differentially expressed genes. We identified a total of 31 genes that were significantly up-regulated in DN samples compared to both normal and Art treatment samples, and 38 genes that were significantly down-regulated in DN samples compared to both normal and Art treatment samples. The identified genes were associated with a list of gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and may be involved in the mechanism underlying Art treatment of DN. Thus, the results from the current study demonstrate that genes are aberrantly expressed after Art treatment and identify promising targets in the treatment of DN with artemisinin.

Dihydroartemisinin enhances VEGFR1 expression through up-regulation of ETS-1 transcription factor

Angiogenesis is required for tumor growth. Dihydroartemisinin (DHA), a the effective anti-malarial derivative of artemisinin, demonstrated potent anti-angiogenic activities that closely related to the regulation of vascular endothelial growth factor (VEGF) signaling cascade. VEGF receptor 1 (VEGFR1), a receptor in endothelial cells (ECs), coordinately regulate angiogenic activity triggered by ligand-receptor binding. Here we aimed to explore the effects of DHA on VEGFR1 expression in ECs. We found that DHA significantly increases VEGFR1 expression in human umbilical vein endothelial cells (HUVECs). In addition, DHA significantly upregulates the level of V-Ets Avian Erythroblastosis Virus E26 Oncogene Homolog 1 (ETS-1), a transcriptional factor which binds to the human VEGFR1 promoter. ChIP assay showed that DHA increases ETS-1 binding to the -52 ETS motif on the VEGFR1 promoter. Knockdown of ETS-1 by RNA interference abolished DHA-induced increase of VEGFR1 expression. Taken together, we demonstrated that DHA elevates VEGFR1 expression via up-regulation of ETS-1 transcription in HUVECs.