Cytotoxic Effects of Escin on Human Castration-resistant Prostate Cancer Cells Through the Induction of Apoptosis and G2/M Cell Cycle Arrest

Au/Doc/Quer@PDA/A10-3.2 Nanoparticles for targeted treatment of docetaxel-resistant prostate cancer

Docetaxel (Doc), as a first-line chemotherapy drug for prostate cancer (PC), often loses its therapeutic efficacy due to acquired resistance and lack of targeting specificity. Therefore, there is a need to develop a novel drug that can overcome Doc resistance and enhance its targeting ability to inhibit PC progression. In this study, we prepared Au/Doc/Quer@PDA/A10-3.2 nanoparticles (NPs) composite drug by encapsulating Doc and quercetin (Quer) within polydopamine (PDA)-coated Au NPs and further modifying them with RNA oligonucleotide aptamer A10-3.2. A10-3.2 was used for specific targeting of prostate-specific membrane antigen (PSMA)-positive PC cells (LNCaP). Quer was employed to reverse the resistance of Doc-resistant cell line (LNCaP/R) to Doc. Physical characterization using ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR) confirmed the successful preparation of Au/Doc/Quer@PDA/A10-3.2 NPs. Fluorescence imaging and flow cytometry experiments demonstrated the targeting ability of Au/Doc/Quer@PDA/A10-3.2 NPs towards PSMA-positive LNCaP/R cells. Cell proliferation, apoptosis, invasion, and migration experiments revealed that Quer reversed the resistance of LNCaP/R cells to Doc. Immunoblotting experiments further confirmed the mechanism behind sensitization of chemotherapy by Quer. Finally, we evaluated the therapeutic efficacy of Au/Doc/Quer@PDA/A10-3.2 NPs in a mouse model of PC. In conclusion, this study synthesized and validated a novel nano-composite drug (Au/Doc/Quer@PDA/A10-3.2 NPs) for combating Doc-resistant PC, which could potentially be applied in clinical treatment of PC.

Escin enhanced the efficacy of sorafenib by autophagy-mediated apoptosis in lung cancer cells

Combining anti-cancer drugs has been exploited as promising treatment strategy to target lung cancer. Synergistic chemotherapies increase anti-cancer effect and reduce effective drug doses and side effects. In this study, therapeutic potential of escin in combination with sorafenib has been explored. 3-(4,5-Dimethylthiazol-2-yl)-2 5-diphenyltetrazolium bromide assay was used to calculate IC50 values. The synergy was evaluated using Chou-Talaly algorithm. Cellular reactive oxygen species, mitochondrial membrane potential, annexin V, and cell-cycle studies were done by flow-cytometer, and autophagy biomarkers expression were determined using western blotting. Moreover, autophagy was knocked down using ATG5 siRNA to confirm its role, diethylnitrosamine-induced lung cancer model was used to check the synergy of sorafenib/escin. Escin significantly reduced the IC50 of sorafenib in A549 and NCIH460 cells. The combination of sorafenib/escin produced a 2.95 and 5.45 dose reduction index for sorafenib in A549 and NCI-H460 cells. The combination of over-expressed p62 and LC3-II reflects autophagy block-mediated late apoptosis. This phenomenon was reconfirmed by ATG5 knockdown. This combination also selectively targeted G0/G1 phase of cancer cells. In in vivo study, the combination reduced tumour load and lower elevated serum biochemical parameters. The combination of sorafenib/escin synergistically inhibits autophagy to induce late apoptosis in lung cancer cells' G0/G1 phase.

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.

Targeting the radiation-induced ARv7-mediated circNHS/miR-512-5p/XRCC5 signaling with Quercetin increases prostate cancer radiosensitivity

Background

Radiation therapy (RT) with androgen deprivation therapy (ADT) is an effective therapy to suppress the locally advanced prostate cancer (PCa). However, we unexpectedly found that RT could also induce the androgen receptor splice variant 7 (ARv7) expression to decrease the radiosensitivity.

Methods

The study was designed to target ARv7 expression with Quercetin or ARv7-shRNA that leads to enhancing and increasing the radiation sensitivity to better suppress the PCa that involved the modulation of the circNHS/miR-512-5p/XRCC5 signaling.

Results

Mechanism studies revealed that RT-induced ARv7 may function via altering the circNHS/miR-512-5p/XRCC5 signaling to decrease the radiosensitivity. Results from preclinical studies using multiple in vitro cell lines and in vivo mouse models concluded that combining RT with the small molecule of Quercetin to target full-length AR and ARv7 could lead to better efficacy to suppress PCa progression.

Conclusion

Together, these results suggest that ARv7 may play key roles to alter the PCa radiosensitivity, and targeting this newly identified ARv7 mediated circNHS/miR-512-5p/XRCC5 signaling with Quercetin may help physicians to develop a novel RT to better suppress the progression of PCa.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02287-4.

High Expression of PDLIM2 Predicts a Poor Prognosis in Prostate Cancer and Is Correlated with Epithelial-Mesenchymal Transition and Immune Cell Infiltration

Purpose

To elucidate the clinical and prognostic role of PDZ and LIM domain protein (PDLIM) genes and the association to epithelial-mesenchymal transition (EMT) and immune cell infiltration in patients with prostate cancer (PRAD).

Methods

The data of RNA-seq, DNA methylation, and clinical features of PRAD patients were collected from The Cancer Genome Atlas (TCGA) database to define the prognostic value of PDLIM gene expression and the association with EMT and immune cell infiltration. A tissue microarray including 134 radical prostatectomy specimens was served as validation by immunohistochemistry (IHC) staining analysis.

Results

The mRNA levels of PDLIM1/2/3/4/6/7 were significantly downregulated, while PDLIM5 was upregulated in PRAD (P < 0.05). High expression of PDLIM2 mRNA suggests poor progression free interval in PRAD patients. DNA methylation of PDLIM2 was correlated with its mRNA expression level, and that the cg22973076 methylation site in PDLIM2 was associated with shorter PFI (P < 0.05) in PRAD. Single-sample gene-set enrichment and gene functional enrichment results showed that PDLIM2 was correlated with EMT and immune processes. Spearman's test showed a significant correlation with six reported EMT signatures and several EMT signature-related genes. Tumor microenvironment analysis revealed that the PDLIM2 mRNA expression was positively correlated with the immune score, stromal score, and various tumor infiltrating immune cells. Additionally, the results showed that patients in the high-PDLIM2 mRNA expression group may be more sensitive to immune checkpoint blockade therapy. Finally, IHC analysis further implicated the protein level of PDLIM2 was upregulated in PRAD and acts as a novel potential biomarker in predicting tumor progression.

Conclusion

Our study suggests that PDLIM family genes might be significantly correlated with oncogenesis and the progression of PRAD. PDLIM2 correlated with EMT and immune cell infiltration by acting as an oncogene in PRAD, which may serve as a potential prognostic biomarker for PRAD patients.

Combination of quercetin and 2-methoxyestradiol inhibits epithelial-mesenchymal transition in PC-3 cell line via Wnt signaling pathway

Aim:

We have previously reported that quercetin (Qu) regulates epithelial–mesenchymal transition (EMT) by modulating Wnt signaling components. In this study, we investigated the synergistic effect of Qu and 2-methoxyestradiol (2-ME) and the role of Wnt signaling components in regulating EMT in PC-3 cells.

Materials & methods:

EMT was induced by treating PC-3 cells with TGF-β, followed by evaluation of expression of EMT markers and Wnt signaling proteins in naive, induced and after exposing induced cells to Qu and 2-ME at both gene and protein level by real-time PCR (RT-PCR) and western blot, respectively.

Results:

Qu and 2-ME synergistically downregulated mesenchymal markers with simultaneous upregulation of epithelial markers. Wnt signaling proteins expression was also downregulated by Qu and 2-ME in TGF-β-induced EMT in PC-3 cells.

Conclusion:

Thus, combination therapy of Qu and 2-ME could be a new promising therapeutic approach for the treatment of prostate cancer.

The current study describes the synergistic effect of quercetin and 2-methoxyestradiol and the role of Wnt signaling components in regulating epithelial–mesenchymal transition (EMT) in PC-3 cells. EMT was induced by treating PC-3 cells with TGF-β, followed by the evaluation of expression of EMT markers and Wnt signaling proteins in naive and induced states. Quercetin and 2-methoxyestradiol could synergistically downregulate mesenchymal markers with simultaneous upregulation of epithelial markers along with the downregulation of Wnt signaling proteins.

Pisosterol Induces G2/M Cell Cycle Arrest and Apoptosis via the ATM/ATR Signaling Pathway in Human Glioma Cells

BACKGROUND

Pisosterol, a triterpene derived from Pisolithus tinctorius, exhibits potential antitumor activity in various malignancies. However, the molecular mechanisms that mediate the pisosterol-specific effects on glioma cells remain unknown.

OBJECTIVE

This study aimed to evaluate the antitumoral effects of pisosterol on glioma cell lines.

METHODS

The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and trypan blue exclusion assays were used to evaluate the effect of pisosterol on cell proliferation and viability in glioma cells. The effect of pisosterol on the distribution of the cells in the cell cycle was performed by flow cytometry. The expression and methylation pattern of the promoter region of MYC, ATM, BCL2, BMI1, CASP3, CDK1, CDKN1A, CDKN2A, CDKN2B, CHEK1, MDM2, p14ARF and TP53 was analyzed by RT-qPCR, western blotting and bisulfite sequencing PCR (BSP-PCR).

RESULTS

Here, it has been reported that pisosterol markedly induced G2/M arrest and apoptosis and decreased the cell viability and proliferation potential of glioma cells in a dose-dependent manner by increasing the expression of ATM, CASP3, CDK1, CDKN1A, CDKN2A, CDKN2B, CHEK1, p14ARF and TP53 and decreasing the expression of MYC, BCL2, BMI1 and MDM2. Pisosterol also triggered both caspase-independent and caspase-dependent apoptotic pathways by regulating the expression of Bcl-2 and activating caspase-3 and p53.

CONCLUSION

It has been, for the first time, confirmed that the ATM/ATR signaling pathway is a critical mechanism for G2/M arrest in pisosterol-induced glioma cell cycle arrest and suggests that this compound might be a promising anticancer candidate for further investigation.

Phytochemicals With Anti 5-alpha-reductase Activity: A Prospective For Prostate Cancer Treatment

Prostate cancer (CaP) is one of the leading causes of death in men worldwide. Much attention has been given on its prevention and treatment strategies, including targeting the regulation of 5-alpha-Reductase (5αR) enzyme activity, aimed to limit the progression of CaP by inhibiting the conversion of potent androgen dihydrotestosterone from testosterone that is thought to play a role in pathogenesis of CaP, by using the 5-alpha-Reductase inhibitors (5αRis) such as finasteride and dutasteride. However, 5αRis are reported to exhibit numerous adverse side effects, for instance erectile dysfunction, ejaculatory dysfunction and loss of libido. This has led to a surge of interest on plant-derived alternatives that might offer favourable side effects and less toxic profiles. Phytochemicals from plants are shown to exhibit numerous medicinal properties in various studies targeting many major illnesses including CaP. Therefore, in this review, we aim to discuss the use of phytochemicals namely phytosterols, polyphenols and fatty acids, found in various plants with proven anti-CaP properties, as an alternative herbal CaP medicines as well as to outline their inhibitory activities on 5αRs isozymes based on their structural similarities with current 5αRis as part of CaP treatment approaches.

Potential Therapeutic Targets of Quercetin, a Plant Flavonol, and Its Role in the Therapy of Various Types of Cancer through the Modulation of Various Cell Signaling Pathways

Polyphenolic flavonoids are considered natural, non-toxic chemopreventers, which are most commonly derived from plants, fruits, and vegetables. Most of these polyphenolics exhibit remarkable antioxidant, anti-inflammatory, and anticancer properties. Quercetin (Qu) is a chief representative of these polyphenolic compounds, which exhibits excellent antioxidant and anticancer potential, and has attracted the attention of researchers working in the area of cancer biology. Qu can regulate numerous tumor-related activities, such as oxidative stress, angiogenesis, cell cycle, tumor necrosis factor, proliferation, apoptosis, and metastasis. The anticancer properties of Qu mainly occur through the modulation of vascular endothelial growth factor (VEGF), apoptosis, phosphatidyl inositol-3-kinase (P13K)/Akt (proteinase-kinase B)/mTOR (mammalian target of rapamycin), MAPK (mitogen activated protein kinase)/ERK1/2 (extracellular signal-regulated kinase 1/2), and Wnt/β-catenin signaling pathways. The anticancer potential of Qu is documented in numerous in vivo and in vitro studies, involving several animal models and cell lines. Remarkably, this phytochemical possesses toxic activities against cancerous cells only, with limited toxic effects on normal cells. In this review, we present extensive research investigations aimed to discuss the therapeutic potential of Qu in the management of different types of cancers. The anticancer potential of Qu is specifically discussed by focusing its ability to target specific molecular signaling, such as p53, epidermal growth factor receptor (EGFR), VEGF, signal transducer and activator of transcription (STAT), PI3K/Akt, and nuclear factor kappa B (NF-κB) pathways. The anticancer potential of Qu has gained remarkable interest, but the exact mechanism of its action remains unclear. However, this natural compound has great pharmacological potential; it is now believed to be a complementary-or alternative-medicine for the prevention and treatment of different cancers.

Anti-proliferation and apoptosis-inducing effects of sodium aescinate on retinoblastoma Y79 cells

AIM

To investigate the anti-proliferation and apoptosis-inducing effects of sodium aescinate (SA) on retinoblastoma Y79 cells and its mechanism.

METHODS

Y79 cells were cultured at different drug concentrations for different periods of time (24, 48, and 72h). The inhibitory effect of SA on proliferation of Y79 cells was detected by the cell counting kit-8 (CCK-8) assay, and the morphology of Y79 cells in each group was observed under an inverted microscope. An IC50 of 48h was selected for subsequent experiments. After pretreatment with SA for 24 and 48h, cellular DNA distribution and apoptosis were detected by flow cytometry. Real-time qunatitative polymerase chain reaction (RT-qPCR) and Western blot were used to assess changes in related genes (CDK1, CyclinB1, Bax, Bcl-2, caspase-9, caspase-8, and caspase-3).

RESULTS

SA inhibited proliferation and induced apoptosis of Y79 cells in a time-dependent and concentration-dependent manner. Following its intervention in the cell cycle pathway, SA can inhibit the expression of CDK1 and CyclinB1 at the mRNA and protein levels, and block cells in the G2/M phase. In caspase-related apoptotic pathways, up-regulation of Bax and down-regulation of Bcl-2 caused caspase-9 to self-cleave and further activate caspase-3. What's more, the caspase-8-mediated extrinsic apoptosis pathway was activated, and the activated caspase-8 was released into the cytoplasm to activate caspase-3, which as a member of the downstream apoptotic effect group, initiates a caspase-cascade reaction that induces cell apoptosis.

CONCLUSION

SA inhibits the proliferation of Y79 cells by arresting the cell cycle at the G2/M phase, and induces apoptosis via the caspase-related apoptosis pathway, indicating that SA may have promising potential as a chemotherapeutic drug.

Activation of p53 Gene Expression and Synergistic Antiproliferative Effects of 5-Fluorouracil and β-escin on MCF7 Cells

One of the most common malignancies in women is breast cancer. β-escin has pharmacological anticancer effects. 5-fluorouracil (5-FU) has antimetabolite and antiproliferative properties. The purpose of this study was to investigate the combined effects of 5-FU and β-escin on apoptosis, colony formation, Bcl-2 signaling protein, and p53 gene expression in MCF7 breast cancer cell line. The cytotoxic effects, the number of colonies, apoptosis, p53 gene expression, and Bcl-2 signaling protein of the combined 5-FU and β-escin on MCF7 cells were determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, clonogenic assay, flow cytometry, real-time quantitative polymerase chain reaction, and western blotting methods, respectively. Half-maximal inhibitory concentration values of β-escin and 5-FU were 80 μg/ml and 2 μM, respectively. The combination of 5-FU and β-escin on MCF7 cell viability showed a combination index equal to 0.5. The expression of p53 and apoptosis increased in the combination of 5-FU and β-escin on MCF7 cells compared to that of control group (P < 0.05). In addition, the number of colonies and Bcl-2 signaling protein in combination of 5-FU and β-escin decreased with respect to untreated control cells or single treatment of 5-FU and β-escin. The combination of 5-FU and β-escin not only has synergistic effects by increasing cell apoptosis and p53 gene expression but also decreases Bcl-2 signaling protein in MCF7 cell lines.

Inhibition of Migration and Invasion in Melanoma Cells by β-Escin via the ERK/NF-κB Signaling Pathway

β-Escin, a natural triterpene saponin was extracted from Aesculus hippocastanum seeds, which have been widely used to treat inflammation in traditional medicine. In an effort to study the possible anti-tumor effects of β-escin, we performed wound healing, invasion, and adhesion assays to examine the effects of β-escin on cell migration, invasion, and angiogenesis. Our results revealed that β-escin inhibits cell migration as well as motility in B16F10 and SK-MEL5 cells in a dose-dependent manner. RT-PCR and Western blot analysis showed that β-escin increased TIMP-1, -2 while significantly downregulated phosphorylated extracellular signal-regulated kinase (p-ERK) expression, and suppressing nuclear factor-kappa B (NF-κB) and inhibitor of nuclear factor-kappa B (IκB) expression. Overall, the data from the current study suggest that β-escin has the potential for inhibiting both metastatic and angiogenic activities, and are the earliest evidence for the involvement of the NF-κB/IκB signaling in β-escin-induced anti-tumor effects.

16-Tigloyl linked barrigenol-like triterpenoid from Semen Aesculi and its anti-tumor activity in vivo and in vitro

Barrigenol-like triterpenoids (BATs) showed promising anti-tumor, anti-inflammatory and anti-Alzheimer's activities, while, the inhibitory strength was usually affected by their states with aglycones or glycosides. In order to find more BATs as new anti-tumor agents with much more efficiency, the chemical and pharmaceutical studies were carried out on the acid hydrolysate product (AHP) of Semen Aesculi crude extract. Thirteen BATs, including three new aglycones (1–3), two new glycosides (4, 5) and eight known glycosides (6–13) were obtained. Compound 1, as the main product in AHP, with a tigloyl unit linked at the C-16 position was an unusual aglycone. All compounds exhibited various degrees of inhibitory activity against human breast cell line (MCF-7) and cervical cancer cell line (HeLa) growth, moreover, new aglycones 1 and 2, and the known glycoside 6 (escin Ia) and 9 were found to exhibit potent inhibitory activity which were similar to the positive control (doxorubicin hydrochloride). Compound 1, named 16-tigloyl-O-protoaescigenin, could suppress tumor progression and decreased lung metastasis focuses in mice, and no pathological change was observed at the end of the treatment course. Besides that, the hemolysis experiment between 1 and 6 revealed that the hemolysis toxicity of 1 was much less than that of 6. According to these results, 16-tigloyl-O-protoaescigenin, with the powerful anti-tumor activity and cancer cell apoptosis induction, might be considered as a new promising anti-tumor agent.

Barrigenol-like triterpenoids (BATs) showed promising anti-tumor, anti-inflammatory and anti-Alzheimer's activities, while, the inhibitory strength was usually affected by their states with aglycones or glycosides.

Recent advances on the progressive mechanism and therapy in castration-resistant prostate cancer

Background

Although there have been great advances in mechanisms and therapeutic methods of prostate cancer, the mortality rate of prostate cancer remains high. The castration-resistant prostate cancer (CRPC), which develops from hormone-sensitive prostate cancer, foreshadows a more dismal outcome. Concomitant with the researches in the mechanism of CRPC and therapy for CRPC, more and more landmark progress has been made in recent years.

Methods

A number of clinical and experimental studies were reviewed to indicate the novel advancement in the progressive mechanism and therapy of CRPC.

Results

The androgen receptor (AR) is still a vital driver in the progression of CRPC, while other multiple mechanisms also contribute to this progression, such as tumor immunity, cancer stem cells, epithelial–mesenchymal transition and DNA repair disorder. In terms of the therapeutic methods of CRPC, chemotherapy with drugs, such as docetaxel, has been the first-line therapy for CRPC for many years. Besides, newer agents, which target some of the above mechanisms, show additional overall survival benefits for CRPC patients. These therapies include drugs targeting the androgen axis pathway (androgen synthesis, androgen receptor splice variants, coactivators of AR and so on), PI3K-AKT pathway, WNT pathway, DNA repair, rearrangement of ETS gene, novel chemotherapy and immunotherapy, bone metastasis therapy and so on. Understanding these novel findings on the mechanisms of CRPC and the latest potential CRPC therapies will direct us for further exploration of CRPC.

Conclusion

Through comprehensive consideration, the predominant mechanism of CRPC might be the AR signal axis concomitant with tumor microenvironment, stress, immunity, tumor microenvironment and so on. For CRPC therapy, targeting the AR axis pathway and chemotherapy are the first-line treatments at present. However, with the advancements in CRPC therapy made by the researchers, other novel potential methods will occupy more and more important position in the treatment of CRPC, especially the therapies targeting the tumor microenviroment, tumor immunity and DNA repair and so on.

Inhibition of human prostate cancer (PC-3) cells and targeting of PC-3-derived prostate cancer stem cells with koenimbin, a natural dietary compound from Murraya koenigii (L) Spreng

BACKGROUND

Inhibition of prostate cancer stem cells (PCSCs) is an efficient curative maintenance protocol for the prevention of prostate cancer. The objectives of this study were to assess the efficiency of koenimbin, a major biologically active component of Murraya koenigii (L) Spreng, in the suppression of PC-3 cells and to target PC-3-derived cancer stem cells (CSCs) through apoptotic and CSC signaling pathways in vitro.

MATERIALS AND METHODS

The antiproliferative activity of koenimbin was examined using MTT, and the apoptotic detection was carried out by acridine orange/propidium iodide (AO/PI) double-staining and multiparametric high-content screening (HCS) assays. Caspase bioluminescence assay, reverse transcription polymerase chain reaction (RT-PCR), and immunoblotting were conducted to confirm the expression of apoptotic-associated proteins. Cell cycle analysis was investigated using flow cytometry. Involvement of nuclear factor-kappa B (NF-κB) was analyzed using HCS assay. Aldefluor™ and prostasphere formation examinations were used to evaluate the impact of koenimbin on PC-3 CSCs in vitro.

RESULTS

Koenimbin remarkably inhibited cell proliferation in a dose-dependent manner. Koenimbin induced nuclear condensation, formation of apoptotic bodies, and G0/G1 phase arrest of PC-3 cells. Koenimbin triggered the activation of caspase-3/7 and caspase-9 and the release of cytochrome c, decreased anti-apoptotic Bcl-2 and HSP70 proteins, increased pro-apoptotic Bax proteins, and inhibited NF-κB translocation from the cytoplasm to the nucleus, leading to the activation of the intrinsic apoptotic pathway. Koenimbin significantly (P<0.05) reduced the aldehyde dehydrogenase-positive cell population of PC-3 CSCs and the size and number of PC-3 CSCs in primary, secondary, and tertiary prostaspheres in vitro.

CONCLUSION

Koenimbin has chemotherapeutic potential that may be employed for future treatment through decreasing the recurrence of cancer, resulting in the improvement of cancer management strategies and patient survival.

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.

β-Escin Effectively Modulates HUVECS Proliferation and Tube Formation

In the present study we evaluated the anti-angiogenic activities of β-escin (the major active compound of Aesculus hippocastanum L. seeds). Human umbilical-vein endothelial cells (HUVECs) were used as an in vitro model for studying the molecular mechanism underlying the anti-angiogenic effect of β-escin. We investigated the in vitro effects on proliferation, migration, and tube formation of HUVECs and in vivo anti-angiogenic activity was evaluated in a chick chorioallantoic membrane (CAM) angiogenesis assay. Moreover, the effect on gene expressions was determined by the RT2 ProfilerTM human angiogenesis PCR Array. It was found that β-escin exerts inhibitory effect on the basic fibroblast growth factor (bFGF)-induced proliferation, migration and tube formation, as well as CAM angiogenesis in vivo. The inhibition of critical steps of angiogenic process observed with β-escin could be partially explained by suppression of Akt activation in response to bFGF. Moreover, the anti-angiogenic effects of β-escin could also be mediated via inhibition of EFNB2 and FGF-1 gene expressions in endothelial cells. In conclusion, β-escin affects endothelial cells as a negative mediator of angiogenesis in vitro and in vivo and may therefore be considered as a promising candidate for further research elucidating its underlying mechanism of action.

β-Escin inhibits the proliferation of osteosarcoma cells via blocking the PI3K/Akt pathway

β-Escin exhibits anticancer effects on a panel of established cancer cells. However, the effects of β-escin on human osteosarcoma (OS) are still unknown. The aim of the present study was to investigate whether β-escin was effective against OS both in vivo and in vitro. Our results showed that β-escin induced dose- and time-dependent effects against MG-63, OS732, U-2OS, HOS and SAOS-2 cell proliferation. β-Escin also exhibited excellent anti-proliferative and pro-apoptotic effects in an established OS xenograft model. β-Escin and cytotoxic drugs, including cisplatin, methotrexate (MTX), doxorubicin (Dox) and ifosfamide (Ifos), synergistically inhibited proliferation of MG-63 and OS732 cells in vitro. Moreover, β-escin induced apoptotic death, activated caspase-3, caspase-8 and caspase-9, and regulated expression of Bax and Bcl-2 in MG-63 cells. In addition, our results showed that β-escin treatment reduced expression of p-PI3K, p-Akt and p-mTOR both in MG-63 cells and in an MG-63 xenograft OS model. Interestingly, SC79, which is an Akt activator, inhibited the anti-proliferative effects of β-escin on MG-63 cells. Taken together, our data support the conclusion that β-escin effectively inhibits OS proliferation both in vivo and in vitro. The inhibitory effect of β-escin, at least in part, is due to the inactivation of the PI3K/Akt signalling pathway.

β-Escin exhibits anticancer effects on a panel of established cancer cells. However, the effects of β-escin on human osteosarcoma (OS) are still unknown.

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.

Antiviral escin derivatives from the seeds of Aesculus turbinata Blume (Japanese horse chestnut)

Porcine epidemic diarrhea virus (PEDV) causes severe diarrhea and high fatality of piglets, influencing the swine industry. Japanese horse chestnut (seed of Aesculus turbinata) contains many saponin mixtures, called escins, and has been used for a long time as a traditional medicinal plant. Structure-activity relationship (SAR) studies on escins have revealed that acylations at C-21 and C-22 with angeloyl or tigloyl groups were important for their cytotoxic effects. However, the strong cytotoxicity of escins makes them hard to utilize for other diseases and to develop as nutraceuticals. In this research, we investigated whether escin derivatives 1-7 (including new compounds 2, 3, 5 and 6), without the angeloyl or tigloyl groups and with modified glycosidic linkages by hydrolysis, have PEDV inhibitory effects with less cytotoxicity. Compounds 1-7 had no cytotoxicity at 20μM on VERO cells, while compounds 8-10 showed strong cytotoxicity at similar concentrations on PEDV. Our results suggest that escin derivatives showed strong inhibitory activities on PEDV replication with lowered cytotoxicity. These studies propose a method to utilize Japanese horse chestnut for treating PEDV and to increase the diversity of its bioactive compounds.

Association of aescin with β- and γ-cyclodextrins studied by DFT calculations and spectroscopic methods

Background: Aescin, a natural mixture of saponins occurring in Aesculus hippocastanum, exhibits important flebotonic properties, being used in the treatment of chronic venous insufficiency in legs. The inclusion of aescin into cyclodextrins (CDs) is a technical solution for its incorporation into the textile of stockings, but details of the physicochemistry of these host-guest systems are lacking. This work investigates the inclusion of aescin into the cavities of two native cyclodextrins, β-CD and γ-CD. Results: The continuous variation method applied to aqueous-phase ¹H nuclear magnetic resonance (¹H NMR) has demonstrated that the preferred CD/aescin inclusion stoichiometries are 2:1 with β-CD and 1:1 with γ-CD. The affinity constant calculated for γ-CD·aescin was 894 M^-1, while for 2β-CD·aescin it was estimated to be 715 M^-1. Density functional theory (DFT) calculations on the interaction of aescin Ib with CDs show that an inclusion can indeed occur and it is further demonstrated that the wider cavity of γ-CD is more adequate to accommodate this large guest. ROESY spectroscopy is consistent with the formation of a complex in which the triterpenic moiety of aescin is included into the cavity of γ-CD. The higher stability of this geometry was confirmed by DFT. Furthermore, DFT calculations were applied to determine the chemical shifts of the protons H3 and H5 of the CDs in the optimised structures of the inclusion complexes. The calculated values are very similar to the experimental data, validating the approach made in this study by NMR. Conclusion: The combination of experimental data from aqueous-state NMR measurements and theoretical calculations has demonstrated that γ-CD is the most suitable host for aescin, although the inclusion also occurs with β-CD. The geometry of the γ-CD·aescin complex is characterised by the inclusion of the triterpene segment of aescin into the host cavity.