β-escin selectively targets the glioblastoma-initiating cell population and reduces cell viability

Characterization of size-tuneable aescin-lipid nanoparticles as platform for stabilization of membrane proteins

Disc-like lipid nanoparticles stabilized by saponin biosurfactants display fascinating properties, including their temperature-driven re-organization. β-Aescin, a saponin from seed extract of the horse chestnut tree, shows strong interactions with lipid membranes and has gained interest due to its beneficial therapeutic implications as well as its ability to decompose continuous lipid membranes into size-tuneable discoidal nanoparticles. Here, we characterize lipid nanoparticles formed by aescin and the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine. We present site-resolved insights into central molecular interactions and their modulations by temperature and aescin content. Using the membrane protein bacteriorhodopsin, we additionally demonstrate that, under defined conditions, aescin-lipid discs can accommodate medium-sized transmembrane proteins. Our data reveal the general capability of this fascinating system to generate size-tuneable aescin-lipid-protein particles, opening the road for further applications in biochemical, biophysical and structural studies.

β-Escin: An Updated Review of Its Analysis, Pharmacology, Pharmacokinetics, and Toxicity

[Formula: see text]-Escin is an oleanane-type pentacyclic triterpenoid saponin extracted from the seeds of Aesculus hippocastanum (AH), which is more widely distributed. [Formula: see text]-Escin sodium has been approved by the American FDA for clinical usage. This paper is intended to summarize an updated and comprehensive review of the pharmacological activities, pharmacokinetic properties, toxicity, and analytical methods of [Formula: see text]-escin. Studies have shown that [Formula: see text]-escin has significant antitumor, antiviral, anti-inflammatory, and other activities alongside less adverse effects and higher safety than other compounds. The review shows that the pharmacological effects of [Formula: see text]-escin involve mechanisms such as ATM/[Formula: see text]H2AX, RhoA/Rock, GSK-3[Formula: see text]/[Formula: see text]-Catenin, HER2/HER3/Akt, and PI3K/Akt signaling pathways, and Cyclin A, p21[Formula: see text], survivin, Bcl-2, Mcl-1, Caspases, TGF-[Formula: see text], MMPs, and TNF-[Formula: see text] among other inflammatory factors. [Formula: see text]-Escin has significant cytotoxicity; the use of the chitosan/xanthan gum-based polyelectrolyte complexes PA1 and PC-11 to modify it not only to reduces its toxicity, but also improves its drug efficacy. Because of this, these compounds may become a new research hotspot. [Formula: see text]-Escin in vivo metabolism can be converted by the CYP1A2 enzyme in the intestinal flora to produce [Formula: see text]-escin, deacylated, deglycosylated, and 21[Formula: see text]-[Formula: see text]-crotonoyl-protoescin, and the binding rate of the plasma proteins is higher than 90%. These are mainly metabolized by the liver, kidneys, and other organs, and excreted in the form of urine and feces. The number of reports on the specific mediators of the metabolism of [Formula: see text]-escin and their mechanisms and metabolites is relatively small; furthermore, the results are vague. Therefore, a complete and in-depth exploration of the pharmacokinetic characteristics of [Formula: see text]-escin is needed to provide a more complete and effective theoretical reference for the study of its pharmacodynamic activity.

Escin's Multifaceted Therapeutic Profile in Treatment and Post-Treatment of Various Cancers: A Comprehensive Review

Although modern medicine is advancing at an unprecedented rate, basic challenges in cancer treatment and drug resistance remain. Exploiting natural-product-based drugs is a strategy that has been proven over time to provide diverse and efficient approaches in patient care during treatment and post-treatment periods of various diseases, including cancer. Escin-a plant-derived triterpenoid saponin-is one example of natural products with a broad therapeutic scope. Initially, escin was proven to manifest potent anti-inflammatory and anti-oedematous effects. However, in the last two decades, other novel activities of escin relevant to cancer treatment have been reported. Recent studies demonstrated escin's efficacy in compositions with other approved drugs to accomplish synergy and increased bioavailability to broaden their apoptotic, anti-metastasis, and anti-angiogenetic effects. Here, we comprehensively discuss and present an overview of escin's chemistry and bioavailability, and highlight its biological activities against various cancer types. We conclude the review by presenting possible future directions of research involving escin for medical and pharmaceutical applications as well as for basic research.

Saponins -Uptake and Targeting issues for brain-specific delivery for enhanced cell death induction in glioblastoma

Abstract:

Saponins represent a category of diverse, natural glycoside molecules that belong to the triterpenoid or the steroid class. They vary in terms of their solubility and permeability characteristics and are classifiable based on the biopharmaceutics classification system. They have drug delivery potential as surfactants that can solubilize cholesterol in the plasma membrane of tumorigenic cells. Glioblastoma is an important malignancy that can aggressively afflict the brain of humans with a poor prognosis. Glioblastoma Stem Cells (GSCs), are an important subset of cancer cells and are major determinants for drug resistance and tumour relapse. These cells are quiescent and have been known to survive current therapeutic strategies. Certain saponins have shown potential to eliminate glioblastoma cells in a variety of model systems and hence provide a sound scientific basis for their development as a “stand-alone” drug or as part of a drug combination (from the existing arsenal of drugs) developed for the treatment of glioblastoma. However, due to their reactogenicity towards the immune system and hemolytic potential, selective delivery to the tumorigenic site is essential. Hence, nano-formulations (liposome/emulsion-based delivery systems/nano-structured lipid and calix[n]arenes-based carriers) and variants that are resistant to saponin may serve as delivery tools that can be functionalized to improve the selectivity. It is necessary to develop/validate/refine in vitro higher order models that replicate the features of the glioma microenvironment (BBB/BTB). Reproducible validation of the model as well as the drug/delivery system will help in the development of formulations that can augment cell death in this recalcitrant brain tumour.

Escin inhibits angiogenesis by suppressing interleukin‑8 and vascular endothelial growth factor production by blocking nuclear factor‑κB activation in pancreatic cancer cell lines

Pancreatic cancer (PaCa) is one of the most aggressive types of cancer. Thus, the development of new and more effective therapies is urgently required. Escin, a pentacyclic triterpenoid from the horse chestnut, has been reported to exhibit antitumor potential by reducing cell proliferation and blocking the nuclear factor-κB (NF-κB) signaling pathway in several types of cancer. Our previous study reported that NF-κB enhanced the secretion of interleukin (IL)-8 and vascular endothelial growth factor (VEGF), thereby inducing angiogenesis in PaCa cell lines. In the present study, it was examined whether escin inhibited angiogenesis by blocking NF-κB activation in PaCa. It was initially confirmed that escin, at concentrations >10 µM, significantly inhibited the proliferation of several PaCa cell lines. Next, using immunocytochemical staining, it was found that escin inhibited the nuclear translocation of NF-κB. Furthermore, ELISA confirmed that NF-κB activity in the escin-treated PaCa cells was significantly inhibited and reverse transcription-quantitative PCR showed that the mRNA expression levels of tumor necrosis factor-α-induced IL-8 and VEGF were significantly suppressed following escin treatment in the PaCa cell lines. ELISA also showed that escin decreased the secretion of IL-8 and VEGF from the PaCa cells. Furthermore, tube formation in immortalized human endothelial cells was inhibited following incubation with the supernatants from escin-treated PaCa cells. These results indicated that escin inhibited angiogenesis by reducing the secretion of IL-8 and VEGF by blocking NF-κB activity in PaCa. In conclusion, escin could be used as a novel molecular therapy for PaCa.

Natural Compounds Targeting Cancer Stem Cells: A Promising Resource for Chemotherapy

BACKGROUND

Cancer Stem Cells (CSCs) are the subpopulation of cancer cells which are directly involved in drug resistance, metastases to distant organ and cancer recurrence.

METHODS

A systematic literature search was conducted through various electronic databases including, Pubmed, Scopus, Google scholar using the keywords "cancer stem cells" and "natural compounds" in the present study. Articles published between 1999 and 2019 were reviewed. All the expositions concerning CSCs associated cancer pathogenesis and therapy resistance, as well as targeting these properties of CSCs by natural compounds were selected for the current study.

RESULTS

Natural compounds have always been thought as a rich source of biologically active principles, which target aberrantly activated signaling pathways and other modalities of CSCs, while tethering painful side effects commonly involved in the first-line and second-line chemo-radiotherapies. In this review, we have described the key signaling pathways activated in CSCs to maintain their survival and highlighted how natural compounds interrupt these signaling pathways to minimize therapy resistance, pathogenesis and cancer recurrence properties of CSCs, thereby providing useful strategies to treat cancer or aid in cancer therapy improvement. Like normal stem cells, CSCs rely on different signaling pathways and other properties for their maintenance. Therefore, the success of cancer treatment depends on the development of proper anti-neoplastic drugs capable of intercepting those signaling pathways as well as other properties of CSCs in order to eradicate this evasive subpopulation of cancer cells.

CONCLUSION

Compounds of natural origin might act as an outstanding source to design novel therapies against cancer stem cells.

Antioxidant and Anticancer Activity of Novel Derivatives of 3-[(4-Methoxyphenyl)amino]propane-hydrazide

Series of novel 3-[(4-methoxyphenyl)amino]propanehydrazide derivatives bearing semicarbazide, thiosemicarbazide, thiadiazole, triazolone, triazolethione, thiophenyltriazole, furan, thiophene, naphthalene, pyrrole, isoindoline-1,3-dione, oxindole, etc. moieties were synthesized and their molecular structures were confirmed by IR, ¹H-, ¹³C-NMR spectroscopy and mass spectrometry data. The antioxidant activity of the synthesized compounds was screened by DPPH radical scavenging method. The antioxidant activity of N-(1,3-dioxoisoindolin-2-yl)-3-((4-methoxyphenyl)amino)propanamide and 3-((4-methoxyphenyl)amino)-N’-(1-(naphthalen-1-yl)-ethylidene)propanehydrazide has been tested to be ca. 1.4 times higher than that of a well-known antioxidant ascorbic acid. Anticancer activity was tested by MTT assay against human glioblastoma U-87 and triple-negative breast cancer MDA-MB-231 cell lines. In general, the tested compounds were more cytotoxic against U-87 than MDA-MB-231 cell line. 1-(4-Fluorophenyl)-2-((5-(2-((4-methoxyphenyl)amino)ethyl)-4-phenyl-4H-1,2,4-triazol-3-yl)thio)ethanone has been identified as the most active compound against the glioblastoma U-87 cell line.

β-Escin alleviates cobalt chloride-induced hypoxia-mediated apoptotic resistance and invasion via ROS-dependent HIF-1α/TGF-β/MMPs in A549 cells

Hypoxia is contributed in various pathophysiological conditions including obesity, cardiovascular diseases, and cancer. In cancer, hypoxia is a salient phenomenon and has been correlated with tumor progression, metastasis, and provoke resistance to therapies in cancer patients, which exert with stabilization of main effector, hypoxia inducible factor-1 alpha (HIF-1α). Therefore, therapeutic targeting of hypoxic responses in cancer is the potential approach to improve the better treatment efficacy. In the present study, we evaluated the effect of β-Escin (β-Es) on hypoxia-induced resistance to apoptosis and metastasis in human non-small-cell lung cancer cells. The MTT assay revealed that β-Es treatment decreased the A549 cells viability under cobalt chloride-induced hypoxia. Apoptotic proteins were analyzed by western blot that showed cancer cells treated with β-Es induced cell death in hypoxia condition as proteins compared with normoxia. Moreover, we observed that cobalt chloride induced hypoxia through the generation of intracellular reactive oxygen species and stabilized the transcriptional factor HIF-1α, which leads to cancer metastasis. This notion was supported by the migration, invasion, and adhesion assays. Furthermore, hypoxia increased the expression of transforming growth factor-β, and the activation of matrix metalloproteinases were suppressed by the treatment of β-Es as well as pretreatment with N-acetylcysteine (NAC). Therefore, we demonstrate that a concurrent activation of HIF-1α, transforming growth factor-β, and matrix metalloproteinases participate in hypoxia-induced metastasis and that β-Es prevent A549 cells metastasis by inhibition of reactive oxygen species.

Effect of Cholesterol and Ibuprofen on DMPC-β-Aescin Bicelles: A Temperature-Dependent Wide-Angle X-ray Scattering Study

β -aescin is a versatile biosurfactant extracted from the seeds of the horse chestnut tree Aesculus hippocastanum with anti-cancer potential and is commonly used in the food and pharmaceutical and cosmetic industries. In this article, wide-angle X-ray scattering (WAXS) is used in order to study the modifications of the structural parameters at the molecular scale of lipid bilayers in the form of bicelles composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the triterpenoid saponin β -aescin. In particular, the impact on the cooperative phase transition and the structural parameters of the DMPC bilayers at different compositions and temperatures is of special interest. Moreover, we show how cholesterol and the non-steroidal anti-inflammatory drug (NSAID) ibuprofen modulate the structural parameters of the β -aescin-DMPC assemblies on a molecular scale. Ibuprofen and cholesterol interact with different parts of the bilayer, namely the head-region in the former and the tail-region in the latter case allowing for specific molecular packing and phase formation in the binary and ternary mixtures.

The Biosurfactant β-Aescin: A Review on the Physico-Chemical Properties and Its Interaction with Lipid Model Membranes and Langmuir Monolayers

This review discusses recent progress in physicochemical understanding of the action of the saponin β-aescin (also called β-escin), the biologically active component in the seeds of the horse chestnut tree Aesculus hippocastanum. β-Aescin is used in pharmacological and cosmetic applications showing strong surface activity. In this review, we outline the most important findings describing the behavior of β-aescin in solution (e.g., critical micelle concentration (cmc) and micelle shape) and special physicochemical properties of adsorbed β-aescin monolayers at the air–water and oil–water interface. Such monolayers were found to posses very special viscoelastic properties. The presentation of the experimental findings is complemented by discussing recent molecular dynamics simulations. These simulations do not only quantify the predominant interactions in adsorbed monolayers but also highlight the different behavior of neutral and ionized β-aescin molecules. The review concludes on the interaction of β-aescin with phospholipid model membranes in the form of bilayers and Langmuir monolayers. The interaction of β-aescin with lipid bilayers was found to strongly depend on its cmc. At concentrations below the cmc, membrane parameters are modified whereas above the cmc, complete solubilization of the bilayers occurs, depending on lipid phase state and concentration. In the presence of gel-phase phospholipids, discoidal bicelles form; these are tunable in size by composition. The phase behavior of β-aescin with lipid membranes can also be modified by addition of other molecules such as cholesterol or drug molecules. The lipid phase state also determines the penetration rate of β-aescin molecules into lipid monolayers. The strongest interaction was always found in the presence of gel-phase phospholipid molecules.

Escin induces apoptosis in human bladder cancer cells: An in vitro and in vivo study

Escin (β-escin) is used as traditional folk medicine. The anti-tumour effects of escin have been demonstrated in vitro in certain cell lines, but its effect on bladder cancer has not been well investigated. In this study, the apoptotic activity of escin dissolved in dimethyl sulfoxide (DMSO) in bladder cancer cells and normal peripheral blood mononuclear cells (PBMC) and SV-HUC1 cells (controls) was determined. Cell cytotoxicity was assessed using the MTT assay. Cell cycle, Reactive oxygen species (ROS) generation, annexin V-FITC staining (for detecting early apoptosis), and changes in mitochondrial membrane potential were evaluated using flow cytometry. Expression of apoptosis-related proteins such as Fas (CD95) death receptor/FADD (Fas-associated protein with death domain) and BCL2 family of proteins was assessed using immunoblotting. Escin dose-dependently inhibited the growth of human bladder cancer cells, and showed IC₅₀ of ~40 μM. The cell population in the sub-G1 phase, annexin-V staining, Fas expression, ratio of BAX/BCL2, cleavage of activated caspase-3/-8/-9, increase in poly (ADP-ribose) polymerase (PARP) levels, and suppression of nuclear factor kappa B (NF-κB) were observed after 24 h of escin treatment. Escin decreased mitochondrial membrane potential and increased cytochrome C release via generation of reactive oxygen species, which led to apoptosis of bladder cancer cells. Furthermore, escin effectively inhibited bladder tumour growth in a xenograft mouse model. Together, these results demonstrate that escin induces apoptosis in human bladder cancer cells through the Fas death receptor and mitochondrial pathways and inhibits bladder tumour growth. Escin is a potential chemotherapeutic agent for bladder cancer.

Escin-induced DNA damage promotes escin-induced apoptosis in human colorectal cancer cells via p62 regulation of the ATM/γH2AX pathway

Escin, a triterpene saponin isolated from horse chestnut seed, has been used to treat encephaledema, tissue swelling and chronic venous insufficiency. Recent studies show that escin induces cell cycle arrest, tumor proliferation inhibition and tumor cell apoptosis. But the relationship between escin-induced DNA damage and cell apoptosis in tumor cells remains unclear. In this study, we investigated whether and how escin-induced DNA damage contributed to escin-induced apoptosis in human colorectal cancer cells. Escin (5-80 μg/mL) dose-dependently inhibited the cell viability and colony formation in HCT116 and HCT8 cells. Escin treatment induced DNA damage, leading to p-ATM and γH2AX upregulation. Meanwhile, escin treatment increased the expression of p62, an adaptor protein, which played a crucial role in controlling cell survival and tumorigenesis, and had a protective effect against escin-induced DNA damage: knockdown of p62 apparently enhanced escin-induced DNA damage, whereas overexpression of p62 reduced escin-induced DNA damage. In addition, escin treatment induced concentration- and time-dependent apoptosis. Similarly, knockdown of p62 significantly increased escin-induced apoptosis in vitro and produced en escin-like antitumor effect in vivo. Overexpression of p62 decreased the rate of apoptosis. Further studies revealed that the functions of p62 in escin-induced DNA damage were associated with escin-induced apoptosis, and p62 knockdown combined with the ATM inhibitor KU55933 augmented escin-induced DNA damage and further increased escin-induced apoptosis. In conclusion, our results demonstrate that p62 regulates ATM/γH2AX pathway-mediated escin-induced DNA damage and apoptosis.

Molecular targets and anti-cancer potential of escin

Escin is a mixture of triterpenoid saponins extracted from the horse chestnut tree, Aesculus hippocastanum. Its potent anti-inflammatory and anti-odematous properties makes it a choice of therapy against chronic venous insufficiency and odema. More recently, escin is being actively investigated for its potential activity against diverse cancers. It exhibits anti-cancer effects in many cancer cell models including lung adenocarcinoma, hepatocellular carcinoma and leukemia. Escin also attenuates tumor growth and metastases in various in vivo models. Importantly, escin augments the effects of existing chemotherapeutic drugs, thereby supporting the role of escin as an adjunct or alternative anti-cancer therapy. The beneficial effects of escin can be attributed to its inhibition of proliferation and induction of cell cycle arrest. By regulating transcription factors/growth factors mediated oncogenic pathways, escin also potentially mitigates chronic inflammatory processes that are linked to cancer survival and resistance. This review provides a comprehensive overview of the current knowledge of escin and its potential as an anti-cancer therapy through its anti-proliferative, pro-apoptotic, and anti-inflammatory effects.

Pharmacological targeting of apelin impairs glioblastoma growth

Glioblastoma are highly aggressive brain tumours that are associated with an extremely poor prognosis. Within these tumours exists a subpopulation of highly plastic self-renewing cancer cells that retain the ability to expand ex vivo as tumourspheres, induce tumour growth in mice, and have been implicated in radio- and chemo-resistance. Although their identity and fate are regulated by external cues emanating from endothelial cells, the nature of such signals remains unknown. Here, we used a mass spectrometry proteomic approach to characterize the factors released by brain endothelial cells. We report the identification of the vasoactive peptide apelin as a central regulator for endothelial-mediated maintenance of glioblastoma patient-derived cells with stem-like properties. Genetic and pharmacological targeting of apelin cognate receptor abrogates apelin- and endothelial-mediated expansion of glioblastoma patient-derived cells with stem-like properties in vitro and suppresses tumour growth in vivo. Functionally, selective competitive antagonists of apelin receptor were shown to be safe and effective in reducing tumour expansion and lengthening the survival of intracranially xenografted mice. Therefore, the apelin/apelin receptor signalling nexus may operate as a paracrine signal that sustains tumour cell expansion and progression, suggesting that apelin is a druggable factor in glioblastoma.

Review of Natural Product-Derived Compounds as Potent Antiglioblastoma Drugs

Common care for glioblastoma multiforme (GBM) is a surgical resection followed by radiotherapy and temozolomide- (TMZ-) based chemotherapy. Unfortunately, these therapies remain inadequate involving severe mortality and recurrence. Recently, new approaches discovering combinations of multiple inhibitors have been proposed along with the identification of key driver mutations that are specific to each patient. To date, this approach is still limited by the lack of effective therapy. Hopefully, novel compounds derived from natural products are suggested as potential solutions. Inhibitory effects of natural products on angiogenesis and metastasis and cancer suppressive effect of altering miRNA expression are provident discoveries. Angelica sinensis accelerates apoptosis by their key substances influencing factors of apoptosis pathways. Brazilin displays antitumor features by making influence on reactive oxygen species (ROS) intensity. Sargassum serratifolium, flavonoids, and so on have antimetastasis effect. Ficus carica controls miRNA that inhibits translation of certain secretory pathway proteins during the UPR. Serratia marcescens and patupilone (EPO 906) are physically assessed materials through clinical trials related to GBM progression. Consequently, our review puts emphasis on the potential of natural products in GBM treatment by regulating multiple malignant cancer-related pathway solving pending problem such as reducing toxicity and side effect.

Escin induces caspase-dependent apoptosis and autophagy through the ROS/p38 MAPK signalling pathway in human osteosarcoma cells in vitro and in vivo

Osteosarcoma is one of the most malignant neoplasms in adolescents, and it generally develops multidrug resistance. Escin, a natural mixture of triterpene saponins isolated from Aesculus hippocastanum (horse chestnut), has demonstrated potent anti-tumour potential in vitro and in vivo. In the present study, we found that escin inhibited osteosarcoma proliferation in a dose- and time-dependent manner. Additionally, escin-induced apoptosis was evidenced by the increased expression of caspase-related proteins and the formation of apoptotic bodies. Escin also induced autophagy, with elevated LC3, ATG5, ATG12 and Beclin expression as well as autophagosome formation. Inhibition of escin-induced autophagy promoted apoptosis. Moreover, p38 mitogen-activated protein kinases (MAPKs) and reactive oxygen species (ROS) were activated by escin. A p38 MAPK inhibitor partially attenuated the autophagy and apoptosis triggered by escin, but a ROS scavenger showed a greater inhibitory effect. Finally, the therapeutic efficacy of escin against osteosarcoma was demonstrated in an orthotopic model. Overall, escin counteracted osteosarcoma by inducing autophagy and apoptosis via the activation of the ROS/p38 MAPK signalling pathway; these findings provide evidence for escin as a novel and potent therapeutic for the treatment of osteosarcoma.