Effects of Platycodin D on S100A8/A9-induced inflammatory response in murine mammary carcinoma 4T1 cells

Genome-wide identification and expression profiling of the WRKY gene family reveals abiotic stress response mechanisms in Platycodon grandiflorus

The WRKY family of transcription factors (TFs) is an important gene family involved in abiotic stress responses. Although the roles of WRKY TFs in plant abiotic stress responses are well studied, little is known about the stress-induced changes in WRKY family in Platycodon grandiflorus. 42 PgWRKY genes in seven subgroups were identified in the P. grandiflorus genome. The content of eight platycodins in P. grandiflorus was investigated under cold, heat, and drought stresses. Platycodin D levels significantly increased under three abiotic stresses, while the content changes of other platycodins varied. Transcriptome analysis showed that different WRKY family members exhibited varied expression patterns under different abiotic stresses. PgWRKY20, PgWRKY26, and PgWRKY39 were identified as three key candidates for temperature and drought stress responses, and were cloned and analysed for sequence characteristics, gene structure, subcellular localisation, and expression patterns. The RT-qPCR results showed that PgWRKY26 expression significantly increased after heat stress for 48 h, cold stress for 6 h, and drought stress for 2 d (DS_2 d). The PgWRKY39 expression level significantly increased at DS_2 d. This study provides a theoretical basis for clarifying the molecular mechanism of the abiotic stress responses of the WRKY gene family in P. grandiflorus.

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.

S100A8 and S100A9 in Cancer

S100A8 and S100A9 are Ca²⁺ binding proteins that belong to the S100 family. Primarily expressed in neutrophils and monocytes, S100A8 and S100A9 play critical roles in modulating various inflammatory responses and inflammation-associated diseases. Forming a common heterodimer structure S100A8/A9, S100A8 and S100A9 are widely reported to participate in multiple signaling pathways in tumor cells. Meanwhile, S100A8/A9, S100A8, and S100A9, mainly as promoters, contribute to tumor development, growth and metastasis by interfering with tumor metabolism and the microenvironment. In recent years, the potential of S100A8/A9, S100A9, and S100A8 as tumor diagnostic or prognostic biomarkers has also been demonstrated. In addition, an increasing number of potential therapies targeting S100A8/A9 and related signaling pathways have emerged. In this review, we will first expound on the characteristics of S100A8/A9, S100A9, and S100A8 in-depth, focus on their interactions with tumor cells and microenvironments, and then discuss their clinical applications as biomarkers and therapeutic targets. We also highlight current limitations and look into the future of S100A8/A9 targeted anti-cancer therapy.

Platycodin D induces neutrophil apoptosis by downregulating PD-L1 expression to inhibit breast cancer pulmonary metastasis

During breast cancer development, programmed cell death 1 ligand 1 (PD-L1) overexpression in neutrophils leads to delayed apoptosis and promotes neutrophil hyperproliferation in the lung to form a premetastatic niche, which is beneficial for pulmonary metastasis. Platycodin D (PlaD), a triterpenoid saponin with known anti-inflammatory and antitumor effects, has been reported to downregulate PD-L1 expression. This study aimed to investigate the inhibitory effect of PlaD on neutrophil PD-L1 in 4 T1 tumor-bearing mice and the potential mechanism of breast cancer pulmonary metastasis. In this study, the orthotopic 4 T1 murine mammary carcinoma model was administered 10 and 20 mg/kg PlaD by gavage. PlaD reduced the excess neutrophils and decreased their high migratory capacity in bone marrow, peripheral blood and lung tissue in the premetastatic period, thereby effectively inhibiting tumor growth and pulmonary metastasis. Moreover, PlaD inhibited the phosphatidylinositol-3-kinase (PI3K)/Akt pathway by decreasing the expression of PD-L1 in neutrophils and promoted neutrophil apoptosis. In vitro, PlaD treatment decreased the viability and inhibited migration of neutrophil-like dHL-60 in a dose-dependent manner. Similarly, PlaD inhibited the increase in PD-L1 induced by IFN-γ stimulation and subsequently induced apoptosis in dHL-60 cells. In conclusion, the administration of PlaD inhibited the PI3K/Akt signaling pathway by reducing the expression of PD-L1 in neutrophils. PlaD promoted neutrophil apoptosis, thereby inhibiting the establishment of a premetastatic niche and ultimately blocking the development of pulmonary metastasis.

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 Triggers Antitumor Immunity by Restricting PD-1 Expression of CD8+ T Cells in Local Tumor Microenvironment

In the tumor microenvironment (TME), the activation of programmed death-1 (PD-1)–programmed death ligand-1 (PD-L1) pathway is one of the main signals of immune escape and tumor deterioration. Clinically, the application of monoclonal antibodies slows down the progression of various malignancies and prolongs the survival of patients effectively. However, these treatments result in serious immune-related adverse events (irAEs) owning to systemic immune activation. Therefore, to achieve long-term therapeutic effects and low side effects, it is necessary to find drugs inhibiting the local PD-1/PD-L1 signaling pathway of the TME. Here, we discovered that Platycodon grandiflorum (PG), a medicine and food homology herb, reduced the expression of PD-1 on the surface of CD8⁺ T cells to exert antitumor effects in non-small cell lung cancer (NSCLC). Firstly, by combining systems pharmacology strategies and clinical data analysis, we found that PG has the potential to immunomodulate T cells and suppress tumors. Secondly, in vivo and in vitro experiments have confirmed the antitumor effect of the combination of Platycodin D and Platycodin D3, which is preferred and representative of the compounds. Mechanistically, PG increased the infiltration and killing activity of CD8⁺ T cells, which was related to the decrease of PD-1⁺ CD8⁺ T cells. Furthermore, we confirmed that PG regulated the expression of PD-1 on the surface of CD8⁺ T cells via reducing the secretion of VEGF-A regulated by the level of P-STAT3 in tumor cells. Additionally, PG also positively impacted the biological processes downstream of STAT3. Overall, we demonstrated that PG-mediated downregulation of PD-1 on the surface of CD8⁺ T cells represents a promising strategy to locally enhance T-cell responses and improve antitumor immunity.

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.

Shenling Baizhu Powder Inhibits RV-SA11-Induced Inflammation and Rotavirus Enteritis via TLR4/MyD88/NF-κB Signaling Pathway

Rotavirus enteritis (RVE) is a common acute intestinal infectious disease caused by rotavirus infection. It is an important cause of death in children younger than 5 years worldwide. Shenling baizhu powder (SBP), a classic traditional Chinese formulation, is one of the most popularly prescribed medicines for digestive diseases. Clinical studies have revealed the protective effects of SBP on RVE. However, the potential mechanism is still unclear. In this study, we aimed to evaluate the anti-rotavirus effect of SBP and its mechanism, focusing on the TLR4/MyD88/NF-κB signaling pathway. Our results demonstrated that, based on the inhibition of the virus-induced cytopathic effect in Caco-2 cells, the concentration for 50% of maximal effect (EC50) and selectivity index (SI) of SBP for RV-SA11 in the serum were 5.911% and 11.63, respectively. A total of 219 active compounds with oral bioavailability ≥30% and drug-likeness ≥ 0.18 were selected from the 10 ingredients present in the formulation of SBP, which acted on 471 potential targets. A total of 226 target genes of RVE were obtained from the GeneCards database. The protein-protein interaction (PPI) network showed that there was a close interaction between 44 common targets of SBP and RVE. The results of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that SBP acted on RVE through various inflammatory pathways and the intestinal immune network. Subsequently, we investigated the effect of SBP on TLR4/MyD88/NF-κB signaling pathway in vitro. After infection with RV- SA11, the expression of TLR4, MyD88, and NF-κB mRNA and protein increased significantly, which could be abolished by SBP treatment. In addition, the IL-1β, TNF-α, IL-6, and IFN-β levels increased markedly in Caco-2 cells infected with RV-SV11. Treatment with SBP partly reversed the changes of IL-1β, TNF-α, and IL-6, while further increased the level of IFN-β. In conclusion, our study revealed that SBP can significantly inhibit rotavirus replication and proliferation in vitro. The antiviral effect may be related to the regulation of the TLR4/MyD88/NF-κB signaling pathway, followed by the down regulation of inflammatory cytokines and up regulation of IFN-β induced by rotavirus.

Anti-inflammatory effects of Platycodin D on dextran sulfate sodium (DSS) induced colitis and E. coli Lipopolysaccharide (LPS) induced inflammation

Platycodin D (PLD) is a saponin found in Platycodon grandiflorum, which has been reported to have anti-inflammatory effects. However, the effects of PLD on ulcerative colitis (UC) remain unknown. In this study, PLD showed the potential to reduce inflammation, ameliorate intestinal damage, and maintain intestinal integrity in DSS-induced colitis. However, the beneficial effect of PLD was reduced when macrophages were depleted, indicating the key role of macrophages in the beneficial effect of PLD in DSS-induced colitis. Meanwhile, we found that PLD inhibited the expression of M1 markers and promoted the expression of M2 markers in colon. Similarly, we found PLD significantly attenuated the levels of pro-inflammatory cytokines, increased the level of anti-inflammatory cytokine and altered macrophage proportions in LPS-stimulated RAW 264.7 cells in vitro. Moreover, treating LPS-stimulated RAW 264.7 cells with PLD increased the activation of the PI3K/Akt signaling pathway and decreased activation of NF-κB pathway. Furthermore, we found that the anti-inflammatory and macrophage polarization regulatory effects of PLD was Adenosine 5'-monophosphate-activated protein kinase (AMPK)-dependent. These results indicate that PLD attenuates DSS-induced colitis and LPS-induced inflammation, and the mechanism behind the phenomenon may be regulating macrophage polarization via activation of AMPK. Our study provides a theoretical basis for PLD to be used as a potential treatment of colitis.

[18F]FDG uptake of bone marrow on PET/CT for predicting distant recurrence in breast cancer patients after surgical resection

Background

The objective of this study was to investigate the prognostic value of 2-Deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) uptake of bone marrow (BM) and metabolic parameters of primary tumor on positron emission tomography/computed tomography (PET/CT) for predicting distant recurrence in patients with breast cancer.

Methods

Pretreatment [¹⁸F]FDG PET/CT images of 345 breast cancer patients were retrospectively evaluated. Maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis (TLG) of primary breast cancer and bone marrow-to-liver uptake ratio (BLR) on PET/CT were measured. A Cox proportional hazard regression model was used to evaluate the prognostic potential of parameters for predicting recurrence-free survival (RFS) and distant RFS. For Kaplan-Meier analysis, the specific cutoff values pf BLR and TLG were determined by the maximal chi-square method.

Results

The median follow-up duration of the enrolled patients was 48.7 months, and during follow-up, 36 patients (10.4%) experienced the cancer recurrence. BLR was significantly correlated with T stage, serum inflammatory markers, and recurrence pattern (p < 0.05). Patients with high BLR and TLG showed worse RFS and distant RFS than those with low BLR and TLG. On multivariate analysis, BLR was significantly associated with both RFS and distant RFS after adjusting for T stage, estrogen receptor status, and TLG (p = 0.001 for both). Only 0.5% of patients with TLG < 9.64 g and BLR < 0.91 experienced distant recurrence. However, patients with TLG ≥ 9.64 g and BLR ≥ 0.91 had a distant recurrence rate of 40.7%.

Conclusions

BLR on pretreatment [¹⁸F]FDG PET/CT were significant predictors for RFS and distant RFS in patients with breast cancer. By combining [¹⁸F]FDG uptake of BM and volumetric PET/CT index of breast cancer, the risk of distant recurrence could be stratified.

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.

Protective Effect of Traditional Chinese Medicine Formula RP on Lung Microenvironment in Pre-Metastasis Stage of Breast Cancer

Background: Inflammatory response and inflammation-induced vascular hyper-permeability were established leading to the abnormalities of the pulmonary microenvironment in pre-metastasis stage of breast cancer. Ruyiping is a commonly used compound drug for clinical treatment of breast cancer metastasis, and Platycodon grandiflorum is mainly used to treat pulmonary inflammatory diseases. Therefore, this study used ruyiping combined with Platycodon grandiflorum (abbreviated as RP) to investigate their inhibitory effect on pre-metastatic microenvironment of lung in 4T1 tumor-bearing mice. Study Design and Methods: The permeability of lung tissue was detected by Evans blue method. The localization of S100A8/A9 in lung tissue was obtained by double-labeling immunofluorescence staining. The level of fibrinogen in pre-metastatic microenvironment of lung as well as the levels of pro-inflammatory factors (interleukin [IL]-1β and IL-6) and chemokines (CXCL2 and CXCL5) in bronchoalveolar lavage fluid was detected by ELISA (enzyme-linked immunosorbent assay). Results: From the experimental results, RP could protect the integrity of microvascular, inhibit the release of S100A8/A9, reduce the extravasation of fibrinogen, and decrease the expressions of IL-1β, IL-6, CXCL2, and CXCL5. Conclusions: RP could inhibit the extravasation of fibrinogen by protecting pulmonary vascular integrity and then interrupted its interaction with carcinoma in situ, thereby inhibiting the formation of inflammatory pre-metastatic microenvironment.

Characterization of β-Glycosidase from Caldicellulosiruptor owensensis and Its Application in the Production of Platycodin D from Balloon Flower Leaf

Platycodin D has diverse pharmacological activities. An efficient and economical mechanism for obtaining platycosides (platycodin D in particular) would be very useful. Balloon flower leaf extract (BFLE) was obtained by recycling leaves discarded from Platycodi radix production, as they have a high platycoside E content. A recombinant β-glycosidase from Caldicellulosiruptor owensensis was characterized and applied to BFLE for platycoside bioconversion. The enzyme specifically hydrolyzed the glucose residue at the C-3 position in platycosides and was suitable for platycodin D production. Under optimized reaction conditions, β-glycosidase from C. owensensis completely converted platycoside E from BFLE into platycodin D with the highest concentration and productivity reported so far. These results greatly improve the production process for deglycosylated platycosides.

miR-34a Enhances the Susceptibility of Gastric Cancer to Platycodin D by Targeting Survivin

INTRODUCTION

Platycodin D (PD), a triterpenoid saponin isolated from Platycodon grandiflorum, has a well-known anti-tumor effect in multiple human cancers, including gastric cancer (GC). miR-34a plays an important role in the progression of GC. However, the relationship between miR-34a and the susceptibility of GC cells to PD is still unclear. The aim of our research was to investigate the functions of miR-34a in mediating the susceptibility of GC to PD.

METHODS

qPCR was performed to detect the expression level of miR-34a and survivin in GC cells. The expression of survivin, Bcl-2, Bax, and cleaved caspase-3 was analyzed using Western blot. Cell viability was detected by MTT assay, and apoptosis was analyzed via Annexin V-FITC/PI staining followed by flow cy-tometry. The colony formation and scratch-wound assays were applied to assess cell proliferation and migration. Caspase-3/7 activity was detected by a Caspase-Glo®3/7 detection kit. The relationship between miR-34a and survivin was determined by dual luciferase reporter gene assay. Finally, a GC xenograft mouse model was used to confirm our findings in vivo.

RESULTS

The expression of miR-34a decreased but survivin increased inversely in human GC cells. Survivin is a direct target of miR-34a and may be negatively regulated by miR-34a. PD could inhibit GC cell proliferation and induce apoptosis. Importantly, overexpression miR-34a or suppressing survivin was shown to enhance the susceptibility of GC to PD both in vitro and in vivo.

CONCLUSIONS

miR-34a could modulate the susceptibility of GC to PD via targeting survivin, suggesting miR-34a overexpression may serve as a novel strategy to sensitize GC to anti-cancer drugs.

Platycodin D inhibits proliferation, migration and induces chemosensitization through inactivation of the NF-κB and JAK2/STAT3 pathways in multiple myeloma cells

Multiple myeloma (MM) is a malignancy characterized by the proliferation of malignant plasma cells. Platycodin D (PLD) is a triterpenoid saponin that exerts anti-tumour activity through multiple mechanisms. However, the role of PLD in MM remains unknown. Here, we investigated the effect of PLD on MM cell lines NCI-H929 and U266B1, and elucidated the underlying molecular mechanism. Cell Counting Kit-8 assay showed that the proliferation of NCI-H929 and U266B1 cells was significantly decreased after PLD treatment. Transwell assay confirmed that PLD treatment suppressed migration of NCI-H929 and U266B1 cells. Flow cytometry results indicated that the apoptotic rates of bortezomib (BTZ)-treated NCI-H929 and U266B1 cells were markedly increased after PLD treatment. Western blot analysis revealed that bcl-2 expression was decreased, while bax expression was increased in PLD-treated NCI-H929 and U266B1 cells compared with that in BTZ-treated cells. Furthermore, PLD treatment blocked the activation of nuclear factor-kappa B (NF-κB) and Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signalling pathways in NCI-H929 cells. Taken together, these data showed that PLD inhibited proliferation and migration, and enhanced chemosensitization to BTZ through inactivation of the NF-κB and JAK2/STAT3 pathways in MM cell lines. These findings indicated that PLD might serve as a novel therapeutic agent for the treatment of MM.