Platycodin D triggers autophagy through activation of extracellular signal-regulated kinase in hepatocellular carcinoma HepG2 cells

Advancements in Utilizing Natural Compounds for Modulating Autophagy in Liver Cancer: Molecular Mechanisms and Therapeutic Targets

Autophagy, an intrinsic catabolic mechanism that eliminates misfolded proteins, dysfunctional organelles, and lipid droplets, plays a vital function in energy balance and cytoplasmic quality control, in addition to maintaining cellular homeostasis. Liver cancer such as hepatocellular carcinoma (HCC) is one of the most common causes of cancer deaths globally and shows resistance to several anticancer drugs. Despite the rising incidence and poor prognosis of malignant HCC, the underlying molecular mechanisms driving this aggressive cancer remain unclear. Several natural compounds, such as phytochemicals of dietary and non-dietary origin, affect hepatocarcinogenesis signaling pathways in vitro and in vivo, which may help prevent and treat HCC cells. Current HCC cells treatments include chemotherapy, radiation, and surgery. However, these standard therapies have substantial side effects, and combination therapy enhances side effects for an acceptable therapeutic benefit. Therefore, there is a need to develop treatment strategies for HCC cells that are more efficacious and have fewer adverse effects. Multiple genetic and epigenetic factors are responsible for the HCC cells to become resistant to standard treatment. Autophagy contributes to maintain cellular homeostasis, which activates autophagy for biosynthesis and mitochondrial regulation and recycling. Therefore, modifying autophagic signaling would present a promising opportunity to identify novel therapies to treat HCC cells resistant to current standard treatments. This comprehensive review illustrates how natural compounds demonstrate their anti-hepatocellular carcinoma function through autophagy.

Platycodin D induces apoptotic cell death through PI3K/AKT and MAPK/ERK pathways and synergizes with venetoclax in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous and rapidly progressive hematopoietic neoplasm characterized by frequent relapses and variable prognoses. The development of new treatment options, therefore, is of crucial importance. Platycodin D (PD) is a triterpenoid saponin, extracted from the roots of the traditional Chinese herbal medicine Platycodon grandiflorum (Jacq.) A. DC., which has been reported to exhibit therapeutic potential against a broad range of cancers. Although the effects of PD on AML remain unclear, in the present study, we observed a concentration-dependent reduction in the viability of multiple human AML cell lines in response to treatment with PD. In addition to triggering mitochondria-dependent apoptosis via the upregulation of BAK and BIM, treatment with PD also induced cell cycle arrest at the G0/G1 phase. Western blot analyses revealed marked suppression of the phosphorylation of protein kinase B (AKT), glycogen synthase kinase-3β, ribosomal protein S6, and extracellular signal-regulated kinase (ERK) by PD, in turn implying the participation of the phosphoinositide 3-kinase (PI3K)/AKT and mitogen-activated protein kinase (MAPK)/ERK pathways. Pre-incubation with LY294002, MK2206, AR-A014418, or U0126 was consistently found to significantly aggravate PD-induced inhibition of viability. Additionally, PD combined with the B-cell lymphoma 2 (BCL2) inhibitor venetoclax elicited synergistically enhanced cytotoxic effects. The anti-leukemic activity of PD was further validated using primary samples from de novo AML patients. Given the results of the present study, PD may be a potent therapeutic candidate for the treatment of AML.

Ophiopogon japonicus and its active compounds: A review of potential anticancer effects and underlying mechanisms

BACKGROUND

Ophiopogon japonicus (Thunb.) Ker Gawl., a well-known Chinese herb, has been used in traditional Chinese medicine for thousands of years. Extensive in vitro and in vivo studies have shown that O. japonicus and its active compounds exhibit potential anticancer effects in a variety of cancer cells in vitro and suppress tumor growth and metastasis without causing serious toxicity in vivo.

PURPOSE

This review aims to systemically summarize and discuss the anticancer effects and the underlying mechanisms of O. japonicus extracts and its active compounds.

METHODS

The review is prepared following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Various scientific databases including Web of Science, PubMed, Scopus, and Chinese National Knowledge Infrastructure were searched using the keywords: Ophiopogon japonicus, tumor, cancer, carcinoma, content, pharmacokinetics, and toxicity.

RESULTS

O. japonicus extracts and the active compounds, such as ruscogenin-1-O-[β-d-glucopyranosyl(1→2)][β-d-xylopyranosyl(1→3)]-β-d-fucopyranoside (DT-13), ophiopogonin B, and ophiopogonin D, exert potential anticancer effects, including the induction of cell cycle arrest, activation of apoptosis and autophagy, and inhibition of metastasis and angiogenesis. In addition, the mechanisms underlying these effects, as well as the pharmacokinetics, toxicity and clinical utility of O. japonicus extracts and active compounds are discussed. Furthermore, this review highlights the research and application prospects of these compounds in immunotherapy and combination chemotherapy.

CONCLUSIONS

The traditional herb O. japonicus and its phytochemicals could be safe and reliable anticancer drug candidates, alone or in combination with chemotherapeutic drugs. We hope that this review, which highlights the anticancer properties of O. japonicus, will contribute to drug optimization, therapeutic development, and future studies on cancer therapies based on this medicinal plant.

Platycodin D induces proliferation inhibition and mitochondrial apoptosis in diffuse large B-cell lymphoma

Patients with diffuse large B-cell lymphoma (DLBCL) have unsatisfactory outcomes especially when relapse occurs after initial chemotherapy. Platycodin D (PD), a triterpenoid saponin isolated from the root of Platycodon grandiflorum (Jacq.) A. DC., has demonstrated potent anti-cancer activities. So far, however, information regarding the effect of PD on malignant lymphoma remains unavailable. In the present study, we showed that PD dose-dependently inhibited the viability of a serial of established DLBCL cell lines representing different molecular subtypes, and their sensitivities to PD were comparable. Mitochondrial dysfunction and subsequent intrinsic apoptosis were induced by PD, as indicated by the loss of mitochondrial membrane potential and the increase in the percentage of Annexin Ⅴ positive cells. Mechanistically, PD treatment downregulated expression levels of anti-apoptotic proteins including MCL-1, BCL-2, and BCL-XL, while upregulated the expression level of pro-apoptotic protein BAK, followed by the cleavage of PARP. Moreover, PD synergistically enhanced the cytotoxicity of BCL-2 inhibitor venetoclax. In a SUDHL-4-derived xenograft mouse model, PD administration significantly constrained the tumor growth without obvious side effects. Therefore, our results provided new insights into the role of PD in lymphoma therapy.

The pharmacology and mechanisms of platycodin D, an active triterpenoid saponin from Platycodon grandiflorus

Chinese doctors widely prescribed Platycodon grandiflorus A. DC. (PG) to treat lung carbuncles in ancient China. Modern clinical experiences have demonstrated that PG plays a crucial role in treating chronic pharyngitis, plum pneumonia, pneumoconiosis, acute and chronic laryngitis, and so forth. Additionally, PG is a food with a long history in China, Japan, and Korea. Furthermore, Platycodin D (PLD), an oleanane-type triterpenoid saponin, is one of the active substances in PG. PLD has been revealed to have anti-inflammatory, anti-viral, anti-oxidation, anti-obesity, anticoagulant, spermicidal, anti-tumor etc., activities. And the mechanism of the effects draws lots of attention, with various signaling pathways involved in these processes. Additionally, research on PLD's pharmacokinetics and extraction processes is under study. The bioavailability of PLD could be improved by being prescribed with Glycyrrhiza uralensis Fisch. or by creating a new dosage form. PLD has been recently considered to have the potential to be a solubilizer or an immunologic adjuvant. Meanwhile, PLD was discovered to have hemolytic activity correlated. PLD has broad application prospects and reveals practical pharmacological activities in pre-clinical research. The authors believe that these activities of PLD contribute to the efficacy of PG. What is apparent is that the clinical translation of PLD still has a long way to go. With the help of modern technology, the scope of clinical applications of PLD is probable to be expanded from traditional applications to new fields.

Platycodin D inhibits the proliferation and migration of hypertrophic scar-derived fibroblasts and promotes apoptosis through a caspase-dependent pathway

Abnormal fibroblast proliferation and excessive extracellular matrix (ECM) deposition lead to the formation of hypertrophic scars (HSs). However, there is no satisfactory method to inhibit the occurrence and development of HSs. In our study, platycodin D (PD), a natural compound extracted from Platycodon grandiflorus, inhibited HSs formation both in vitro and in vivo. First, qRT-PCR and Western blot were used to confirm PD dose-dependently downregulated the expression of Col I, Col III and α-SMA in human hypertrophic scar-derived fibroblasts (HSFs) (p < 0.05). Second, cck-8, transwell and wound healing assays verified PD suppressed the proliferation (p < 0.05) and migration of HSFs (p < 0.05), and inhibited the differentiation of HSFs into myofibroblasts. Moreover, PD-induced HSFs apoptosis were analyzed by flow cytometry and the apoptosis was activated through a caspase-dependent pathway. The rabbit ear scar model was used to further confirm the inhibitory effect of PD on collagen and α-SMA deposition. Finally, Western blot analysis showed that PD reduced TGF-β RI expression (p < 0.05) and affected matrix metalloproteinase 2 (MMP2) protein levels (p < 0.05). In conclusion, our study showed that PD inhibited the proliferation and migration of HSFs by inhibiting fibrosis-related molecules and promoting apoptosis via a caspase-dependent pathway. The TGF-β/Smad pathway also mediated the inhibition of HSFs proliferation and HSFs differentiation into myofibroblasts. Therefore, PD is a potential therapeutic agent for HSs and other fibrotic diseases.

Platycodon grandiflorum (Jacq.) A. DC.: A review of phytochemistry, pharmacology, toxicology and traditional use

BACKGROUND

The traditional Chinese medicine Platycodon grandiflorum (Jacq.) A. DC. (PG, balloon flower) has medicinal and culinary value. It consists of a variety of chemical components including triterpenoid saponins, polysaccharides, flavonoids, polyphenols, polyethylene glycols, volatile oils and mineral components, which have medicinal and edible value.

PURPOSE

The ultimate goal of this review is to summarize the phytochemistry, pharmacological activities, safety and uses of PG in local and traditional medicine.

METHODS

A comprehensive search of published literature up to March 2022 was conducted using the PubMed, China Knowledge Network and Web of Science databases to identify original research related to PG, its active ingredients and pharmacological activities.

RESULTS

Triterpene saponins are the primary bioactive compounds of PG. To date, 76 triterpene saponin compounds have been isolated and identified from PG. In addition, there are other biological components, such as flavonoids, polyacetylene and phenolic acids. These extracts possess antitussive, immunostimulatory, anti-inflammatory, antioxidant, antitumor, antiobesity, antidepressant, and cardiovascular system activities. The mechanisms of expression of these pharmacological effects include inhibition of the expression of proteins such as MDM and p53, inhibition of the activation of enzymes, such as AKT, the secretion of inflammatory factors, such as IFN-γ, TNF-α, IL-2 and IL-1β, and activation of the AMPK pathway.

CONCLUSION

This review summarizes the chemical composition, pharmacological activities, molecular mechanism, toxicity and uses of PG in local and traditional medicine over the last 12 years. PG contains a wide range of chemical components, among which triterpene saponins, especially platycoside D (PD), play a strong role in pharmacological activity, representing a natural phytomedicine with low toxicity that has applications in food, animal feed and cosmetics. Therefore, PG has value for exploitation and is an excellent choice for treating various diseases.

Recent Progress in Understanding the Action of Natural Compounds at Novel Therapeutic Drug Targets for the Treatment of Liver Cancer

Liver cancer is the third most common cause of cancer-related death following lung and stomach cancers. As a highly lethal disease, liver cancer is diagnosed frequently in less developed countries. Natural compounds extracted from herbs, animals and natural materials have been adopted by traditional Chinese medicine (TCM) practices and reported to be effective in the development of new medications for the treatment of diseases. It is important to focus on the mechanisms of action of natural compounds against hepatocellular carcinoma (HCC), particularly in terms of cell cycle regulation, apoptosis induction, autophagy mediation and cell migration and invasion. In this review, we characterize novel representative natural compounds according to their pharmacologic effects based on recently published studies. The aim of this review is to summarize and explore novel therapeutic drug targets of natural compounds, which could accelerate the discovery of new anticancer drugs.

Distribution, biotransformation, pharmacological effects, metabolic mechanism and safety evaluation of Platycodin D：A comprehensive review

Platycodonis Radix (Jiegeng), the dried root of Platycodon grandiflorum, is a traditional herb used as both medicine and food. Its clinical application for the treatment of cough, phlegm, sore throat, pulmonary and respiratory diseases has been thousands of years in China. Platycodin D is the main active ingredient in Platycodonis Radix, which belongs to the family of pentacyclic triterpenoid saponins because it contains an oleanolane type aglycone linked with double sugar chains. Modern pharmacology has demonstrated that Platycodin D displays various biological activities, such as analgesics, expectoration and cough suppression, promoting weight loss, anti-tumor and immune regulation, suggesting that Platycodin D has the potential to be a drug candidate and an interesting target as a natural product for clinical research. In this review, the distribution and biotransformation, pharmacological effects, metabolic mechanism and safety evaluation of Platycodin D are summarized to lay the foundation for further studies.

Platycodin D inhibits autophagy and increases glioblastoma cell death via LDLR upregulation

Targeting autophagy is a promising therapeutic approach in cancer therapy. Here, we screened 30 traditional herbal medicines to identify novel autophagy regulators and found that Platycodon grandiflorus (PG) and platycodin D (PD), a triterpenoid saponin from PG, inhibited autophagy in glioblastoma multiforme (GBM) cells. Mechanistically, PD prevented lysosomal degradation and the fusion between autophagosomes and lysosomes by inducing sequestration of free cholesterol in lysosomes. The autophagy inhibitory effect of PD was mimicked by both genetic and pharmacological inhibition of Niemann-Pick C1 (NPC1), which exports low-density lipoprotein (LDL)-derived cholesterol from lysosomes. Moreover, PD promoted the uptake of exogenous LDL cholesterol via upregulation of LDL receptor (LDLR), leading to further accumulation of cholesterol within lysosomes and GBM cell death. Importantly, these phenomena were more pronounced in LDLR-overexpressing GBM cells than in normal astrocytes. Finally, blockade of cholesterol uptake by LDLR knockdown reversed the PD-induced inhibition of autophagy and GBM cell growth. Our study proposes that PD could be a potent anti-GBM drug by disrupting cholesterol trafficking and autophagy.

Comprehensive review on signaling pathways of dietary saponins in cancer cells suppression

Nutrigenomics utilizes high-throughput genomic technologies to reveal changes in gene and protein levels. Excitingly, ever-growing body of scientific findings has provided sufficient evidence about the interplay between diet and genes. Cutting-edge research and advancements in genomics, epigenetics and metabolomics have deepened our understanding on the role of dietary factors in the inhibition of carcinogenesis and metastasis. Dietary saponins, a type of triterpene glycosides, are generally found in Platycodon grandifloras, Dioscorea oppositifolia, asparagus, legumes, and sea cucumber. Wealth of information has started to shed light on pleiotropic mechanistic roles of dietary saponins in cancer prevention and inhibition. In this review, we have attempted to summarize the in vitro research of dietary saponins in the last two decades by searching common databases such as Google Scholar, PubMed, Scopus, and Web of Science. The results showed that dietary saponins exerted anti-cancer activities via regulation of apoptosis, autophagy, arrest cell cycle, anti-proliferation, anti-metastasis, and anti-angiogenesis, by regulation of several critical signaling pathways, including MAPK, PI3K/Akt/mTOR, NF-κB, and VEGF/VEGFR. However, there is no data about the dosage of dietary saponins for practical anti-cancer effects in human bodies. Extensive clinical studies are needed to confirm the effectiveness of dietary saponins for further commercial and medical applications.

Terpenoids' anti-cancer effects: focus on autophagy

Terpenoids are the largest class of natural products, most of which are derived from plants. Amongst their numerous biological properties, their anti-tumor effects are of interest for they are extremely diverse which include anti-proliferative, apoptotic, anti-angiogenic, and anti-metastatic activities. Recently, several in vitro and in vivo studies have been dedicated to understanding the 'terpenoid induced autophagy' phenomenon in cancer cells. Light has already been shed on the intricacy of apoptosis and autophagy relationship. This latter crosstalk is driven by the delicate balance between activating or silencing of certain proteins whereby the outcome is expressed via interrelated signaling pathways. In this review, we focus on nine of the most studied terpenoids and on their cell death and autophagic activity. These terpenoids are grouped in three classes: sesquiterpenoid (artemisinin, parthenolide), diterpenoids (oridonin, triptolide), and triterpenoids (alisol, betulinic acid, oleanolic acid, platycodin D, and ursolic acid). We have selected these nine terpenoids among others as they belong to the different major classes of terpenoids and our extensive search of the literature indicated that they were the most studied in terms of autophagy in cancer. These terpenoids alone demonstrate the complexity by which these secondary metabolites induce autophagy via complex signaling pathways such as MAPK/ERK/JNK, PI3K/AKT/mTOR, AMPK, NF-kB, and reactive oxygen species. Moreover, induction of autophagy can be either destructive or protective in tumor cells. Nevertheless, should this phenomenon be well understood, we ought to be able to exploit it to create novel therapies and design more effective regimens in the management and treatment of cancer.

Platycodin D attenuates airway inflammation via suppression Th2 transcription factor in a murine model of acute asthma

Introduction: Bronchial asthma is a common chronic inflammatory condition of the airway tissue. Platycodin D (PLD) has antiinflammatory effects in a mouse model of allergic asthma. In this work, the anti-asthma potential of PLD was studied by investigation of its effect to suppress airway inflammation and mucin production, a murine model of asthma and the possible mechanisms.Methods: Mice were randomly assigned to five experimental groups: control, ovalbumin (OVA), OVA+ICS (intranasal fluticasone), OVA+PLD and OVA+PLD/ICS. Airway histological studies were evaluated by the H&E staining; IL-4, IL-5, and IL-13 in bronchoalveolar lavage fluid were evaluated by ELISA; GATA3 and IRF4 mRNA of airway were measured by RT-PCR and their protein level were measured by Western blotting.Results: Our study showed that PLD suppressed eosinophilic inflammation and mucin production in bronchial mucosa. Moreover, PLD inhibited production of Th2 cytokines such as IL-4, IL-5, and IL-13. Protein production of GATA3 and IRF4, were also decreased in PLD treated OVA asthma model. Taken together, our results provided evidence that PLD inhibits the airway inflammation via suppression of Th2 transcription factor production.Conclusion: These findings suggest that PLD may effectively ameliorate the progression of asthma. These results suggest that PLD could be used as a therapy for allergic asthma.

Anti-obesity Medications in Cancer Therapy: A Comprehensive Insight

The interplay between cancer and obesity is multifactorial and complex with the increased risk of cancer development in obese individuals posing a significant threat. Obesity leads to the upregulation or hyperactivation of several oncogenic pathways in cancer cells, which drives them towards a deleterious phenotype. The cross-talk between cancer and obesity is considered a large contributing factor in the development of chemotherapeutic drug resistance and the resistance to radiotherapy. The link between obesity and the development of cancer is so strong that a medication that demonstrates effectiveness against both conditions would serve as an essential step. In this context, anti-obesity medications provide a worthy list of candidates based on their chemo-preventive potential and chemotherapeutic properties. The current study focuses on exploring the potential of anti-obesity medicines as dual anticancer drugs. These medications target several key signaling pathways (e.g., AMPK, PI3K/Akt/mTOR, MAPK, NF-κB, JNK/ERK), which prove to be crucial for both cancer growth and metastases. Some of these drugs also play an important role in attenuating the signaling and cellular events which incite cancer-obesity cross-talk and demonstrate efficient counteraction of neoplastic transformation. Thus, this review highlights a comprehensive view of the potential use of anti-obesity medicines to treat both cancer and obesity for patients exhibiting both comorbities.

Platycodin D reverses histone deacetylase inhibitor resistance in hepatocellular carcinoma cells by repressing ERK1/2-mediated cofilin-1 phosphorylation

BACKGROUND

Chemoresistance remains the main obstacle in hepatocellular carcinoma (HCC) therapy. Despite significant advances in HCC therapy, HCC still has a poor prognosis. Thus, there is an urgent need to identify a treatment target to reverse HCC chemotherapy resistance. Platycodon grandiflorus (PG) is a perennial herb that has been used as food and traditional Chinese medicine for thousands of years in Northeast Asia. Platycodin D (PD), a main active triterpenoid saponin found in the root of PG, has been reported to possess anticancer properties in several cancer cell lines, including HCC; however, the reversal effect of this molecule on HCC chemoresistance remains largely unknown.

PURPOSE

This study aimed to investigate the role and the mechanism of PD-mediated reversal of the histone deacetylase inhibitor (HDACi) resistance in HCC cells.

METHODS

Human HCC cells (HA22T) and HDACi-resistant (HDACi-R) cells were used. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Combination index was used to calculate the synergism potential. Expression of ERK1/2 (total/phospho), cofilin-1 (total/phospho) and apoptosis-related protein was determined using western blotting. Mitochondrial membrane potential was assessed using the JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide) probe. Apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Mitochondrial reactive oxygen species generation was measured using the MitoSOX Red fluorescent probe.

RESULTS

We found that PD treatment inhibited cell viability both in HA22T HCC and HDACi-R cells. Inhibition of ERK1/2 by PD98059 could reverse drug resistance in HDACi-R cells treated with PD98059 and PD. Nevertheless, pre-treatment with U46619, an ERK1/2 activator, rescued PD-induced apoptosis by decreasing levels of apoptosis-related proteins in HCC cells. The combined treatment of PD with apicidin a powerful HDACi, dramatically enhanced the apoptotic effect in HDACi-R cells.

CONCLUSION

For the first time, we showed that PD reversed HDACi resistance in HCC by repressing ERK1/2-mediated cofilin-1 phosphorylation. Thus, PD can potentially be a treatment target to reverse HCC chemotherapy resistance in future therapeutic trials.

Targeting autophagy using saponins as a therapeutic and preventive strategy against human diseases

Autophagy is a ubiquitous mechanism for maintaining cellular homeostasis through the degradation of long-lived proteins, insoluble protein aggregates, and superfluous or damaged organelles. Dysfunctional autophagy is observed in a variety of human diseases. With advanced research into the role that autophagy plays in physiological and pathological conditions, targeting autophagy is becoming a novel tactic for disease management. Saponins are naturally occurring glycosides containing triterpenoids or steroidal sapogenins as aglycones, and some saponins are reported to modulate autophagy. Research suggests that saponins may have therapeutic and preventive efficacy against many autophagy-related diseases. Therefore, this review comprehensively summarizes and discusses the reported saponins that exhibit autophagy regulating activities. In addition, the relevant signaling pathways that the mechanisms involved in regulating autophagy and the targeted diseases were also discussed. By regulating autophagy and related pathways, saponins exhibit bioactivities against cancer, neurodegenerative diseases, atherosclerosis and other cardiac diseases, kidney diseases, liver diseases, acute pancreatitis, and osteoporosis. This review provides an overview of the autophagy-regulating activity of saponins, the underlying mechanisms and potential applications for managing various diseases.

Investigation of the Inhibitory Effect of Platycodin D in Human Transitional Cell Carcinoma Cell Line 5637

Platycodin D is an active component isolated from Chinese herb Platycodonis radix with various pharmacological activities, such as antitussive, expectorant, anti-inflammatory, and analgesic effects. Interestingly, platycodin D also exerts anticancer effects against several types of cancer. However, few studies on the anti-tumour effects of platycodin against urinary bladder cancer have been reported. In this study, we explored the anti-tumour effect of platycodin D against human bladder cancer and its mechanisms in vitro and in vivo. We found that platycodin D had significant anti-proliferative effects on four types of cancer cells, especially the 5637 bladder cancer cell line, and exerted these effects by preventing cell cycle progression from G0/G1 to S phase, down-regulating Ki-67 and cyclin D1 protein expression and up-regulating P21 protein expression. Furthermore, platycodin D inhibited 5637 cell migration by decreasing twist-related protein 1 (Twist1) and matrix metallopeptidase 2 (MMP2) expression and exerted significant tumour-suppressive effects in tumour-bearing nude mice. Platycodin D also increased caspase-9, caspase-8, caspase-3, and p53 expression and decreased Bcl-2 expression in tumour tissues. Taken together, our results provide a theoretical basis for application of platycodin D in treating urinary bladder cancer.

Saponins Extracted from Tea (Camellia Sinensis) Flowers Induces Autophagy in Ovarian Cancer Cells

Tea flower saponins (TFS) possess effective anticancer properties. The diversity and complexity of TFS increases the difficulty of their extraction and purification from tea flowers. Here, multiple methods including solvent extraction, microporous resin separation and preparative HPLC separation were used to obtain TFS with a yield of 0.34%. Furthermore, we revealed that TFS induced autophagy—as evidenced by an increase in MDC-positive cell populations and mCherry-LC3B-labeled autolysosomes and an upregulation of LC3II protein levels. 3-MA reversed the decrease in cell viability induced by TFS, showing that TFS induced autophagic cell death. TFS-induced autophagy was not dependent on the Akt/mTOR/p70S6K signaling pathway. TFS-induced autophagy in OVCAR-3 cells was accompanied by ERK pathway activation and reactive oxygen species (ROS) generation. This paper is the first report of TFS-mediated autophagy of ovarian cancer cells. These results provide new insights for future studies of the anti-cancer effects of TFS.

Effects of Platycodin D on apoptosis, migration, invasion and cell cycle arrest of gallbladder cancer cells

Platycodin D (PD) is a triterpenoid saponin that exists in the roots of Platycodonis. It exhibits evident growth inhibitory effects and potent cytotoxicity against multiple types of cancer. Gallbladder cancer (GBC) is the most common malignant disease of the biliary tract system. Patients with GBC usually have limited available treatment strategies and a poor prognosis. The present study investigated the antitumor effects of PD on human GBC cells in vitro and its underlying molecular mechanisms of action. The results indicated that PD, as assessed using MTT and colony forming assays, induced evident growth inhibition. Flow cytometry indicated that PD robustly induced apoptosis and blocked GBC cells at the G₂/M phase. Cell migration and invasion assays demonstrated that PD effectively inhibited the migratory and invasive abilities of GBC cell lines. Western blotting indicated that PD may initiate mitochondrial destruction in GBC cells through the JNK signaling pathway, thereby inducing apoptosis. The present results indicated that PD may exhibit antitumor effects by inducing apoptosis; inhibiting migration and invasion; and affecting the cell cycle in GBC cells. Therefore, PD has the potential to become a novel antitumor drug for GBC therapy.

Proposed mechanisms for the extracellular release of PD-L1 by the anticancer saponin platycodin D

Platycodin D (PTD) is an oleanane-type terpenoid saponin, isolated from the plant Platycodon grandiflorus. PTD displays multiple pharmacological effects, notably significant anticancer activities in vitro and in vivo. Recently, PTD was shown to trigger the extracellular release of the immunologic checkpoint glycoprotein PD-L1. The reduction of PD-L1 expression at the surface of cancer cells leads to interleukin-2 secretion and T cells activation. In the present review, we have analyzed the potential origin of this atypical PTD-induced PD-L1 release to propose a mechanistic explanation. For that, we considered all published scientific information, as well as the physicochemical characteristics of the natural product (a modeling analysis of PTD and the related saponin β -escin is provided). On this basis, we raise the hypothesis that the capacity of PTD to induce PD-L1 extracellular release derives from two main mechanisms: (i) a drug-promoted shedding of membrane PD-L1 by metalloproteases or more likely, (ii) a cholesterol binding-related effect, that would lead to perturbation of membrane raft domains, limiting the recruitment of proteins like TLR4. The drug-induced membrane effects (frequently observed with saponin drugs), associated with a production of interferon-γ,can favor the release of proteins like PD-L1 into membrane vesicles. Our analysis supports the hypothesis that PTD is a cholesterol-dependent lipid raft-modulating agent able to promote the formation of PD-L1 containing extracellular vesicles. The anticancer potential of PTD and its capacity to modulate the functioning of the PD-1/PD-L1 checkpoint should be further considered.

Bioactive platycodins from Platycodonis Radix: Phytochemistry, pharmacological activities, toxicology and pharmacokinetics

Platycodonis Radix, the root of Platycodon grandiflorum (Jacq.) A. DC., is a well-known edible herbal medicine. It is a common vegetable used for the preparation of side dish, kimchi, dessert, and tea. Besides, it has been used to treat respiratory disease including cough, excessive phlegm, and sore throat for a long history. In the past decades, the bioactive components and the pharmacological activities of Platycodonis Radix have been widely investigated. Thereinto, platycodins, the oleanane-type triterpenoid saponins were demonstrated to be the main bioactive components in Platycodonis Radix, and more than 70 platycodins have been identified up to date. This paper mainly reviewed the phytochemistry, pharmacological activities (apophlegmatic, anti-tussive, anti-inflammatory, anti-cancer, anti-obesity, anti-diabetic, immunomodulatory, cardiovascular protective, and hepatoprotective activities, etc.), toxicology and pharmacokinetics of platycodins isolated from Platycodonis Radix, aiming to promote further investigation on therapeutic potential of these platycodins.

Hydroxysafflor yellow A induces autophagy in human liver cancer cells by regulating Beclin 1 and ERK expression

Hydroxysafflor yellow A (HSYA) is a water-soluble component of the safflower (Carthamus tinctorius), and research has revealed that HSYA exhibits antitumor effects. In the present study, the effects of HSYA on the autophagy of a Hep-G2 liver cancer cell line, as well as the underlying mechanisms, were investigated. Hep-G2 cells were treated with HSYA and the viability of cells was measured using an MTT assay. Western blotting and immunofluorescence assays were performed to determine the expression of light chain 3 II (LC3-II) and p62, as well as the autophagy regulators Beclin 1 and ERK1/2. Transmission electron microscopy was performed to observe the formation of autophagosomes. The combined effects of HSYA and the autophagy inhibitor chloroquine (CQ) were also determined. The results revealed that the viability of Hep-G2 cells decreased with increasing concentrations of HSYA. Furthermore, LC3-II expression increased significantly and the level of p62 decreased significantly in the HYSA group compared with the control group. Additionally, an increase in Beclin 1 expression and a decrease in phosphorylated-ERK1/2 expression was observed in Hep-G2 cells treated with HYSA. Following treatment with CQ and HSYA, a significant increase in the viability of Hep-G2 cells was observed compared with the HSYA group. Collectively, the results indicated that HSYA induced autophagy by promoting the expression of Beclin 1 and inhibiting the phosphorylation of ERK in liver cancer cells. Therefore, HSYA may serve as a potential therapeutic agent for liver cancer.

Modulation of the Autophagy-lysosomal Pathway in Hepatocellular Carcinoma Using Small Molecules

Hepatocellular carcinoma (HCC) accounts for approximately 90% of all cases of primary liver cancer; it is the third most frequent cause of cancer-related death worldwide. In early-stage disease, surgical resection and liver transplantation are considered curative treatments. However, the majority of HCC patients present with advanced-stage disease that is treated using palliative systemic therapy. Since HCC is heterogeneous owing to its multiple etiologies, various risk factors, and inherent resistance to chemotherapy, the development of an effective systemic treatment strategy for HCC remains a considerable challenge. Autophagy is a lysosome-dependent catabolic degradation pathway that is essential for maintaining cellular energy homeostasis. Autophagy dysfunction is closely linked with the pathogenesis of various cancers; therefore, the discovery of small molecules that can modulate autophagy has attracted considerable interest in the development of a systemic treatment strategy for advanced HCC. Here, we reviewed the roles of autophagy in HCC and the recent advances regarding small molecules that target autophagy regulatory mechanisms.

MicroRNA-24 protects retina from degeneration in rats by down-regulating chitinase-3-like protein 1

MicroRNAs (miRNAs) have been shown to play critical roles in the pathogenesis and progression of degenerative retinal diseases like age-related macular degeneration (AMD). In this study, we first demonstrated that miR-24 plays an important role in maintaining retinal structure and visual function of rats by targeting chitinase-3-like protein 1 (CHI3L1). In the retinal pigment epithelial (RPE) cells of Royal College of Surgeons (RCS) rats, an animal model of genetic retinal degeneration (RD), miR-24 was found lower and CHI3L1 level was higher in comparison with those in Sprague-Dawley (SD) rats. Other changes in the eyes of RCS rats include activated AKT/mTOR and ERK pathways and abnormal autophagy in the RPE cells. Such roles of miR-24 and CHI3L1 were further confirmed in RCS rats by subretinal injection of agomiR-24, which decreased CHI3L1 level and preserved retinal structure and function. Upstream, NF-κB was identified as the regulator of miR-24 in the RPE cells of these rats. On the other hand, in SD rats, intraocular treatment of antagomiR-24 induced pathological changes similar to those in RCS rats. The results revealed the protective roles for miR-24 to RPE cells and a mechanism for RD in RCS rats was proposed: extracellular stress stimuli first activate the NF-κB signaling pathway, which lowers miR-24 expression so that CHI3L1 increased. CHI3L1 sequentially results in aberrant autophagy and RPE dysfunction by activating AKT/mTOR and ERK pathways. Taken together, although the possibility, that the therapeutic effects in RCS rats are caused by other transcriptional changes regulated by miR-24, cannot be excluded, these findings indicate that miR-24 protects rat retina by targeting CHI3L1. Thus, miR-24 and CHI3L1 might be the targets for developing more effective therapy for degenerative retinal diseases like AMD.

Sanggenon O induced apoptosis of A549 cells is counterbalanced by protective autophagy

Sanggenon O (SO) is a Diels-Alder type adduct extracted fromMorus alba, which has been used for its anti-inflammatory action in the Oriental medicine. However, whether it has regulatory effect on human cancer cell proliferation and what the underlying mechanism remains unknown. Here, we found that SO could significantly inhibit the growth and proliferation of A549 cells and induce its pro-apoptotic action through a caspase-dependent pathway. It could also impair the mitochondria which can be reflected by mitochondrial membrane permeabilization. Besides, SQSTM1 up-regulation and autophagic flux measurement demonstrated that exposure to SO led to autophagosome accumulation, which plays a protective role in SO-treated cells. In addition, knocking down of LC3B increased SO triggered apoptotic cell rates. These results indicated that SO has great potential as a promising candidate combined with autophagy inhibitor for the treatment of NSCLC. In conclusion, our results identified a novel mechanism by which SO exerts potent anticancer activity.

Platycodin D, a bioactive component of Platycodon grandiflorum, induces cancer cell death associated with extreme vacuolation

Platycodin D (PD) is a major active component of the roots of Platycodon grandiflorum (Jacq.) A.DC. and possesses multiple biological and pharmacological properties, including anti-cancer activity. The aim of this study was to characterize PD-induced cytoplasmic vacuolation in human cancer cells and investigate the underlying mechanisms. PD-induced cancer cell death was associated with cytoplasmic pinocytic and autophagic vacuolation. Cellular energy levels were decreased by this compound, leading to the activation of AMP-activated protein kinase (AMPK). Additionally, compound C, an inhibitor of AMPK, completely prevented PD-induced vacuolation. These results suggest that PD induces cancer cell death, associated with excessive vacuolation through AMPK activation when cellular energy levels are low. Therefore, our findings provide a mechanistic rationale for a novel combinatorial approach using PD to treat cancer.

Inhibiting autophagy overcomes docetaxel resistance in castration-resistant prostate cancer cells

Background

This study investigates the docetaxel-resistant mechanism and explores the effect of tea polyphenols (TP) on autophagy and its related mechanism in human castration-resistant prostate cancer (CRPC) cell lines PC3 and DU145.

Methods

Immunofluorescence assay and annexin V-FITC/PI double staining flow cytometry were used to analyze the apoptosis and autophagy of PC3 and DU145 cells. The expression of autophagy-related proteins was detected by western bolt.

Results

Docetaxel could induce autophagy and apoptosis, together with the expression increase in p-JNK, p-Bcl-2 and Beclin1. The level of autophagy was remarkably decreased, but apoptosis was increased after combining with TP. In addition, the expression of p-mTOR was increased after combining with TP.

Conclusion

Docetaxel induces protective autophagy in CRPC cells by JNK pathway activation and then Bcl-2 phosphorylation and Beclin1 dissociation. TP activates mTOR pathway, which ultimately inhibits docetaxel-induced autophagy and improves therapeutic efficacy of docetaxel in CRPC cells.

Non-apoptotic cell death in malignant tumor cells and natural compounds

Traditional cancer therapy is mainly targeting on enhancing cell apoptosis, however, it is well established that many cancer cells are chemo-resistant and defective in apoptosis induction. Therefore, it may have important therapeutic implications to exploit some novel natural compounds based on non-apoptotic programmed cell death. Currently, accumulating evidence shows that the compounds from nature source can induce non-apoptotic programmed cell death in cancer cells, and therefore these natural compounds have gained a great promise for the future anticancer therapeutics. In this review, we will concentrate our efforts on the latest developments regarding major forms of non-apoptotic programmed cell death--autophagic cell death, necroptosis, ferroptosis, pyroptosis, glutamoptosis and exosome-associated cell death. Our increased understanding of the role of natural compounds in regulating non-apoptotic programmed cell death will hopefully provide prospective strategies for cancer therapy.

Blocking autophagy enhances the apoptotic effect of 18β-glycyrrhetinic acid on human sarcoma cells via endoplasmic reticulum stress and JNK activation

Sarcoma, a rare form of cancer, is unlike the much more common carcinomas as it occurs in a distinct type of tissue. The potent antitumor effects of 18β-glycyrrhetinic acid (GA), a novel naturally derived agent, have been demonstrated in various cancers. However, the effect of GA on human sarcoma, and the underlying mechanisms, remain to be elucidated. In the current study, we show that GA inhibits sarcoma cell proliferation by inducing G0/G1-phase arrest. Exposure to GA resulted in the activation of caspase-3, -8, and -9, indicating that GA induced apoptosis through both extrinsic and intrinsic pathways. In addition, the autophagy pathway, characterized by the conversion of LC3-I to LC3- II, was activated, resulting in increased Beclin-1 protein levels, decreased p62 expression, and stimulation of autophagic flux. The present findings showed that GA stimulated autophagy by inducing endoplasmic reticulum (ER) stress via the IRE1–JNK pathway. Our data supported the prosurvival role of GA-induced autophagy when the autophagy pathway was blocked with specific chemical inhibitors. Finally, GA markedly reduced sarcoma growth, with little organ-related toxicity, in vivo. The present results suggest that the combination of GA with a specific autophagy inhibitor represents a promising therapeutic approach for the treatment of sarcoma.

Osimertinib induces autophagy and apoptosis via reactive oxygen species generation in non-small cell lung cancer cells

Osimertinib (OSI), also known as AZD9291, is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has been approved for the treatment of non-small cell lung cancer (NSCLC) patients harboring EGFR T790M mutation. Herein, we indicated for the first time that OSI increased the accumulations of cytoplasmic vacuoles, the expression of phosphatidylethanolamine-modified microtubule-associated protein light-chain 3 (LC3-II), and the formation of GFP-LC3 puncta in various cancer cells. The OSI-induced expression of LC3-II was further increased when combined treatment with chloroquine (CQ), an autophagy inhibitor, and the mRFP-EGFP-LC3 plasmid-transfected cells exposed to OSI led to the production of more red-fluorescent puncta than green-fluorescent puncta, indicating OSI induced autophagic flux in the NSCLC cells. Knockdown of EGFR showed no effect on the OSI-induced expression of LC3-II in NCI-H1975 cells. In addition, OSI increased reactive oxygen species (ROS) generation and scavenge of ROS via pretreatment with N-acetyl-l-cysteine (NAC), catalase (CAT), or vitamin E (Vita E) significantly inhibited OSI-induced the accumulations of cytoplasmic vacuoles, the expression of LC3-II, as well as the formation of GFP-LC3 puncta. Combinative treatment with CQ could not remarkably change the OSI-induced cell viability decrease, whereas the OSI-induced cell viability decrease and apoptosis could be reversed through pretreatment with NAC, CAT, and Vita E, respectively. Taken together, this is the first report that OSI induces an accompanied autophagy and the generation of ROS is critical for the OSI-induced autophagy, cell viability decrease, and apoptosis in NSCLC cells.

Baicalein Induces Beclin 1- and Extracellular Signal-Regulated Kinase-Dependent Autophagy in Ovarian Cancer Cells

Baicalein (BA), one of the major compounds isolated from the root of Scutellaria baicalensis Gerogi, exhibits various pharmacological effects, such as anti-oxidant, anti-inflammatory, and anticancer effects. In this study, we found that BA reduced cell viability and increased apoptosis in ovarian cancer cells. Treatment of cells with BA enhanced microtubule-associated protein light chain 3-II (LC3-II) expression, acidic vesicular organelle and GFP-LC3 fluorescence dot accumulation. Combined treatment with chloroquine and BA apparently reduced cell viability and increased the cleavage of poly (ADPribose) polymerase (PARP) in both HEY and A2780 ovarian cancer cell lines, indicating that BA induces a protective autophagy in these cells. Knockdown of Beclin 1 by siRNA remarkably decreased BA-induced LC3-II lipidation. In addition, we found an increase in the phosphorylation of extracellular signal-regulated kinase (ERK, Thr202/Thr204) and AKT (Ser473) after BA treatment, and inhibition of ERK activation by the pharmacological inhibitor U0126 or ERK siRNA blocked BA-induced autophagy. Taken together, these results suggest that BA induces Beclin 1- and ERK-dependent autophagy in ovarian cancer cells.

Fangchinoline accumulates autophagosomes by inhibiting autophagic degradation and promoting TFEB nuclear translocation

Fangchinoline, an alkaloid fromStephania tetrandraS. Moore, accumulates autophagosomes by inhibiting autophagic degradation and promoting TFEB nuclear translocation.

A platycoside-rich fraction from the root of Platycodon grandiflorum enhances cell death in A549 human lung carcinoma cells via mainly AMPK/mTOR/AKT signal-mediated autophagy induction

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Platycodon grandiflorum (PG), commonly known as Kilkyong in Korea, Jiegeng in China, and Kikyo in Japan, has been extensively used as a traditional anti-inflammatory medicine in Asia for the treatment of respiratory conditions, such as bronchitis, asthma, and tonsillitis. Platycosides isolated from PG are especially well-known for their anti-cancer effects.

AIM OF THE STUDY

We investigated the involvement of autophagic cell death and other potential molecular mechanisms induced by the platycoside-containing butanol fraction of PG (PGB) in human lung carcinoma cells.

MATERIALS AND METHODS

PGB-induced growth inhibition and cell death were measured using a 5-diphenyl-tetrazolium bromide (MTT) assay. The effects of PGB on autophagy were determined by observing microtubule-associated protein 1 light chain 3 (LC3) redistribution with confocal microscopy. The PGB-mediated regulation of autophagy-associated proteins was investigated using Western blotting analysis. Furthermore, the anti-cancer mechanism of PGB was confirmed using chemical inhibitors. A high-performance liquid chromatography (HPLC)-DAD system was used to analyze the platycosides in PGB.

RESULTS

In A549 cells, PGB induced significant autophagic cell death. Specifically, PGB upregulated LC3-II in a time- and dose-dependent manner, and it redistributed LC3 via autophagosome formation in the cytoplasm. PGB treatment increased the phosphorylation of AMP-activated protein kinase (AMPK) and subsequently suppressed the AKT/mammalian target of the rapamycin (mTOR) pathway. Furthermore, PGB inhibited cell proliferation by regulating the mitogen-activated protein kinase (MAPK) pathways. In this study, six types of platycosides were identified in the PGB using HPLC.

CONCLUSIONS

PGB efficiently induced cancer cell death via autophagy and the modulation of the AMPK/mTOR/AKT and MAPK signaling pathways in A549 cells. Therefore, PGB may be an efficacious herbal anti-cancer therapy.

Platycodin D potentiates proliferation inhibition and apoptosis induction upon AKT inhibition via feedback blockade in non-small cell lung cancer cells

AKT is the frequently overexpressed and constitutively active kinase within NSCLC cells and recognized as a promising target for NSCLC treatment. However, AKT inhibition relieves the feedback inhibition of upstream receptor tyrosine kinases (RTKs) that may weaken the efficiency of AKT inhibitors. Platycodin D (PD), isolated from widely-used traditional Chinese medicine Platycodonis Radix, is now found to remarkably enhance the anti-proliferative effect of AKT inhibitors. In this study, combinatorial activity of AKT inhibitor MK2206 and PD on cell proliferation, apoptosis and related signaling were disclosed. Long-term AKT inhibition induced up-regulation of RTKs, including EGFR and HER-2. Co-treatment of MK2206 with PD could abolish this feedback survival through decrease of EGFR, HER-2, and p-AKT, and profound inhibition of 4E-BP1, leading to an amplified anti-proliferative and apoptotic activity in NSCLC cells. Similarly, feedback activation in response to reduction of AKT expression by small interfering RNA (siRNA) was also blocked by PD and apoptotic effect was further enhanced. Thus, PD potentiated proliferative inhibition and apoptotic induction of both AKT inhibitor and siRNA. These findings also reveal the limitations of suppressing feedback-regulated pathways by monotherapy and establish a mechanistic rationale for a novel combination approach targeting AKT for the treatment of NSCLC.

Glycyrrhetinic acid induces cytoprotective autophagy via the inositol-requiring enzyme 1α-c-Jun N-terminal kinase cascade in non-small cell lung cancer cells

Glycerrhetinic acid (GA), one of the main bioactive constituents of Glycyrrhiza uralensis Fisch, exerts anti-cancer effects on various cancer cells. We confirmed that GA inhibited cell proliferation and induced apoptosis in non-small cell lung cancer A549 and NCI-H1299 cells. GA also induced expression of autophagy marker phosphatidylethanolamine-modified microtubule-associated protein light-chain 3 (LC3-II) and punta formation of green fluorescent protein microtubule-associated protein light-chain 3. We further proved that expression of GA-increased autophagy marker was attributed to activation instead of suppression of autophagic flux. The c-jun N-terminal kinase (JNK) pathway was activated after incubation with GA. Pretreatment with the JNK inhibitor SP600125 or silencing of the JNK pathway by siRNA of JNK or c-jun decreased GA-induced autophagy. The endoplasmic reticulum (ER) stress responses were also apparently stimulated by GA by triggering the inositol-requiring enzyme 1α (IRE1α) pathway. The GA-induced JNK pathway activation and autophagy were decreased by IRE1α knockdown, and inhibition of autophagy or the JNK cascade increased GA-stimulated IRE1α expression. In addition, GA-induced cell proliferative inhibition and apoptosis were increased by inhibition of autophagy or the JNK pathway. Our study was the first to demonstrate that GA induces cytoprotective autophagy in non-small cell lung cancer cells by activating the IRE1α-JNK/c-jun pathway. The combined treatment of autophagy inhibitors markedly enhances the anti-neoplasmic activity of GA. Such combination shows potential as a strategy for GA or GA-contained prescriptions in cancer therapy.

Saponins from Chinese Medicines as Anticancer Agents

Saponins are glycosides with triterpenoid or spirostane aglycones that demonstrate various pharmacological effects against mammalian diseases. To promote the research and development of anticancer agents from saponins, this review focuses on the anticancer properties of several typical naturally derived triterpenoid saponins (ginsenosides and saikosaponins) and steroid saponins (dioscin, polyphyllin, and timosaponin) isolated from Chinese medicines. These saponins exhibit in vitro and in vivo anticancer effects, such as anti-proliferation, anti-metastasis, anti-angiogenesis, anti-multidrug resistance, and autophagy regulation actions. In addition, related signaling pathways and target proteins involved in the anticancer effects of saponins are also summarized in this work.

A Homogeneous Polysaccharide from Fructus Schisandra chinensis (Turz.) Baill Induces Mitochondrial Apoptosis through the Hsp90/AKT Signalling Pathway in HepG2 Cells

According to the potential anti-hepatoma therapeutic effect of Schisandra chinensis polysaccharides presented in previous studies, a bioactive constituent, homogeneous Schisandra chinensis polysaccharide-0-1 (SCP-0-1), molecular weight (M_W) circa 69.980 kDa, was isolated and purified. We assessed the efficacy of SCP-0-1 against human hepatocellular liver carcinoma (HepG2) cells to investigate the effects of its antitumour activity and molecular mechanisms. Anticancer activity was evaluated using microscopy, 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst 33258 staining, acridine orange (AO) staining, flow cytometry (FCM), and cell-cycle analysis. SCP-0-1 inhibited the HepG2 cells’ growth via inducing apoptosis and second gap/mitosis (G2/M) arrest dose-dependently, with a half maximal inhibitory concentration (IC₅₀) value of 479.63 µg/mL. Western blotting of key proteins revealed the apoptotic and autophagic potential of SCP-0-1. Besides, SCP-0-1 upregulated Bcl-2 Associated X Protein (Bax) and downregulated B-cell leukemia/lymphoma 2 (Bcl-2) in the HepG2 cells. The expression of caspase-3, -8, and -9; poly (ADP-ribose) polymerase (PARP); cytochrome c (Cyt C); tumor protein 53 (p53); survivin; sequestosome 1 (p62); microtubule-associated protein 1 light chain-3B (LC3B); mitogen-activated protein kinase p38 (p38); extracellular regulated protein kinases (ERK); c-Jun N-terminal kinase (JNK); protein kinase B (AKT); and heat shock protein 90 (Hsp90) were evaluated using Western blotting. Our findings demonstrate a novel mechanism through which SCP-0-1 exerts its antiproliferative activity and induces mitochondrial apoptosis rather than autophagy. The induction of mitochondrial apoptosis was attributed to the inhibition of the Hsp90/AKT signalling pathway in an extracellular signal-regulated kinase-independent manner. The results also provide initial evidence on a molecular basis that SCP-0-1 can be used as an anti-hepatocellular carcinoma therapeutic agent in the future.

Platycodin D inhibits B16F10 melanoma metastasis via antiangiogenic activity

Platycodin D inhibits B16F10 melanoma metastasisviaantiangiogenic activity.

Killing cancer with platycodin D through multiple mechanisms

Cancer is a multi-faceted disease comprised of a combination of genetic, epigenetic, metabolic and signalling aberrations which severely disrupt the normal homoeostasis of cell growth and death. Rational developments of highly selective drugs which specifically block only one of the signalling pathways have been associated with limited therapeutic success. Multi-targeted prevention of cancer has emerged as a new paradigm for effective anti-cancer treatment. Platycodin D, a triterpenoid saponin, is one the major active components of the roots of Platycodon grandiflorum and possesses multiple biological and pharmacological properties including, anti-nociceptive, anti-atherosclerosis, antiviral, anti-inflammatory, anti-obesity, immunoregulatory, hepatoprotective and anti-tumour activities. Recently, the anti-cancer activity of platycodin D has been extensively studied. The purpose of this review was to give our perspectives on the current status of platycodin D and discuss its anti-cancer activity and molecular mechanisms which may help the further design and conduct of pre-clinical and clinical trials to develop it successfully into a potential lead drug for oncological therapy. Platycodin D has been shown to fight cancer by inducing apoptosis, cell cycle arrest, and autophagy and inhibiting angiogenesis, invasion and metastasis by targeting multiple signalling pathways which are frequently deregulated in cancers suggesting that this multi-target activity rather than a single effect may play an important role in developing platycodin D into potential anti-cancer drug.

Platycodin D induces apoptosis and triggers ERK- and JNK-mediated autophagy in human hepatocellular carcinoma BEL-7402 cells

AIM

Platycodin D, the main saponin isolated from Chinese herb Platycodonis Radix, exhibits anticancer activities against various cancer cell lines. Here we evaluated its anticancer action against human hepatocellular carcinoma cells in vitro and in vivo, and elucidated the relationship between platycodin D-induced apoptosis and autophagy.

METHODS

The viability of human hepatocellular carcinoma BEL-7402 cells was evaluated with MTT assay, and the apoptosis was examined using Annexin V/PI and Hoechst 33342 staining assays. Monodansylcadaverine (MDC) staining was used to label autophagic vacuoles. The proteins were detected using Western blot analysis. For studying its anticancer action in vivo, platycodin D (5 and 10 mg· kg(-1)·d(-1)) was intraperitoneally injected to BEL-7402-bearing mice for 21 days.

RESULTS

Platycodin D (5-40 μmol/L) inhibited the cell proliferation in vitro with IC50 values of 37.70±3.99, 24.30±2.30 and 19.70±2.36 μmol/L at 24, 48 and 72 h, respectively. Platycodin D (5-20 μmol/L) dose-dependently increased BEL-7402 cell apoptosis, increased the Bax/Bcl-2 ratio and the levels of cleaved PARP and cleaved caspase-3, and decreased the level of Bcl-2. Furthermore, platycodin D (5-20 μmol/L) induced autophagy in BEL-7402 cells, as evidenced by formation of cytoplasmic vacuoles, increased amounts of LC3-II, and increased numbers of MDC-positive cells. Pretreatment with the autophagy inhibitor chloroquine (5 μmol/L) or BAF (50 nmol/L) significantly enhanced platycodin D-induced proliferation inhibition and apoptosis. Moreover, platycodin D (20 μmol/L) activated the ERK and JNK pathways in BEL-7402 cells, and simultaneous blockage of the two pathways effectively suppressed platycodin D-induced autophagy and enhanced platycodin D-induced apoptosis. In BEL-7402-bearing mice, platycodin D (10 mg·kg(-1)•d(-1)) significantly reduced relative tumor volume with decreased body weight.

CONCLUSION

Platycodin D not only inhibits the proliferation of BEL-7402 cells but also suppresses BEL-7402 xenograft tumor growth. Platycodin D-induced cell proliferation inhibition and apoptosis are amplified by co-treatment with autophagy inhibitors.