Anti-cancer effect and the underlying mechanisms of gypenosides on human colorectal cancer SW-480 cells

Gypenoside A Protects Human Myocardial Cells from Ischemia/Reperfusion Injury via the circ_0010729/miR-370-3p/RUNX1 Axis

Ischemia/reperfusion (I/R) injury is one of the major causes of cardiovascular disease. Gypenoside A (GP), the main active component of Gynostemma pentaphyllum, alleviates myocardial I/R injury. Circular RNAs (circRNAs) and microRNAs (miRNAs) are involved in the I/R injury. We explored the protective effect of GP on human cardiomyocytes (HCMs) via the circ_0010729/miR-370-3p/RUNX1 axis. Overexpression of circ_0010729 abolished the effects of GP on HMC, such as suppression of apoptosis and increase in cell viability and proliferation. Overexpression of miR-370-3p reversed the effect of circ_0010729 overexpression, resulting in the stimulation of HMC viability and proliferation and inhibition of apoptosis. The knockdown of miR-370-3p suppressed the effects of GP in HCMs. RUNX1 silencing counteracted the effect of miR-370-3p knockdown and maintained GP-induced suppression of apoptosis and stimulation of HMC viability and proliferation. The levels of RUNX1 mRNA and protein were reduced in cells expressing miR-370-3p. In conclusion, this study confirmed that GP alleviated the I/R injury of myocardial cell via the circ_0010729/miR-370-3p/RUNX1 axis.

Bacoside a inhibits the growth of glioma by promoting apoptosis and autophagy in U251 and U87 cells

Bacoside A (gypenoside, Gyp) is a potent bioactive compound derived from Gynostemma pentaphyllum, known to exert inhibitory effects on various malignant tumors. However, the effects of Gyp on glioma as well as the underlying mechanisms remain unclear. In the present study, we first conducted a comprehensive investigation into the anti-glioma potential of gypenosides using network pharmacology to identify potential glioma-related targets. Protein-protein interaction networks were assembled, and GO and KEGG enrichment analyses were performed for shared targets. Experimental validation involved assessing the viability of U251 and U87 cell lines using the MTS method. Furthermore, trans-well and scratch migration assays evaluated the cell migration, while flow cytometry and Hoechst 33342 staining were utilized for apoptosis assessment. The study also monitored changes in autophagy flow through fluorescence microscopy. The expression levels of proteins pertinent to migration, apoptosis, and autophagy were tested using Western blotting. Findings revealed that Gyp upregulated apoptosis-related proteins (Bax and cleaved caspase-9), downregulated anti-apoptotic protein Bcl-2, and migration-associated matrix metalloproteinases (MMP-2 and MMP-9). Furthermore, autophagy-related proteins (Beclin1 and LC3 II) were upregulated, and p62 protein expression was downregulated. Gyp displayed considerable potential in suppressing glioma progression by inhibiting cell proliferation, invasion, and migration and promoting apoptosis and autophagy. Gyp may offer potential clinical therapeutic choices in glioma management.

Natural products and mitochondrial allies in colorectal cancer therapy

Colorectal cancer (CRC) is a globally prevalent malignancy with a high potential for metastasis. Existing cancer treatments have limitations, including drug resistance and adverse effects. Researchers are striving to develop effective therapies to address these challenges. Impressively, contemporary research has discovered that many natural products derived from foods, plants, insects, and marine invertebrates can suppress the progression, metastasis, and invasion of CRC. In this review, we conducted a comprehensive search of the CNKI, PubMed, Embase, and Web of Science databases from inception to April 2023 to evaluate the efficacy of natural products targeting mitochondria to fight against CRC. Mitochondria are intracellular energy factories involved in cell differentiation, signal transduction, cell cycle regulation, apoptosis, and tumorigenesis. The identified natural products have been classified and summarized based on their mechanisms of action. These findings indicate that natural products can induce apoptosis in colorectal cancer cells by inhibiting the mitochondrial respiratory chain, ROS elevation, disruption of mitochondrial membrane potential, the release of pro-apoptotic factors, modulation of the Bcl-2 protein family to facilitate cytochrome c release, induction of apoptotic vesicle activity by activating the caspase protein family, and selective targeting of mitochondrial division. Furthermore, diverse apoptotic signaling pathways targeting mitochondria, such as the MAPK, p53, STAT3, JNK and AKT pathway, have been triggered by natural products. Natural products such as diosgenin, allopurinol, and clausenidin have demonstrated low toxicity, high efficacy, and multi-targeted properties. Mitochondria-targeting natural products have great potential for overcoming the challenges of CRC therapy.

Gypenosides suppress fibrosis of the renal NRK-49F cells by targeting miR-378a-5p through the PI3K/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of renal fibrosis caused by chronic kidney disease is increasing year by year. Preventing the activation and conversion of kidney-intrinsic fibroblasts to a myofibroblast phenotype is an important target for blocking the development of renal interstitial fibrosis. Our team established a stable renal interstitial fibrosis cell model in the early stage, and the screening results showed that GPs has good anti-fibrosis potential. At this stage, only a few literatures have reported its anti-fibrosis effect, and the mechanism of action is still unclear.

AIM OF THE STUDY

The massive synthesis and secretion of extracellular-matrix (ECM) components by activated fibroblasts in the kidneys causes irreversible renal interstitial fibrosis. Gypenosides (GPs) have been shown to decelerate this process, in which micro RNAs (miRNAs) play an important regulatory role. This study aimed to evaluate the mechanism underlying the suppressive effect of GPs on renal fibrosis.

MATERIALS AND METHODS

This study used TGF-β1-stimulated NRK-49F renal cells as an in-vitro model of renal interstitial fibrosis. First, the concentration range of GPs that significantly affects the cytoactive was determined. Then, the anti-fibrotic effects of various concentrations of GPs in the in-vitro model were assessed via immunofluorescence, western blotting, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Non-coding-RNA sequencing combined with bioinformatics was used to predict the mechanistic basis of the anti-fibrotic effect of GPs, and qRT-PCR was used to verify the sequencing results and bioinformatic predictions. The identified relationships of the anti-fibrotic effect of GPs with miR-378a-5p and the PI3K/AKT signaling were evaluated using a miR-NC mimic and the PI3K inhibitor LY294002 as controls, respectively.

RESULTS

TGF-β1 stimulation up-regulated α-SMA, COL1, and COL3 in NRK-49F cells, and this effect was suppressed by GPs. Additionally, TGF-β1 stimulation significantly changed the expression levels of 151 miRNAs, and GPs significantly suppressed the effect of TGF-β1 on the levels of 18 of these miRNAs. Among them, miR-3588 and miR-378a-5p were down-regulated, and miR-135b-5p and miR-3068-5p were up-regulated upon TGF-β1 induction. Of these miRNAs, miR-378a-5p was predicted to target the mRNAs of numerous proteins mainly enriched in the PI3K/AKT signaling pathway. The miRNA transfection experiments with the miR-NC mimic and PI3K inhibitor as controls showed that miR-378a-5p overexpression could suppress the TGF-β1-induced up-regulation of α-SMA, COL1, PI3K, and AKT, including the phosphorylated form (p-AKT).

CONCLUSION

GPs inhibit the PI3K/AKT signaling by up-regulating miR-378a-5p in TGF-β1-stimulated NRK-49F cells and thereby reduce their massive secretion of ECM components. Given that this in-vitro model of renal interstitial fibrosis closely mimics the in-vivo pathogenesis, our results most likely apply to the in-vivo conditions.

Gypenoside-Induced Apoptosis via the PI3K/AKT/mTOR Signaling Pathway in Bladder Cancer

Gynostemma pentaphyllum (Thunb.) Makino (G. pentaphyllum) is a natural herbal drug that has been widely used to treat many diseases. The antitumor effects of G. pentaphyllum were first described in the illustrated catalog of plants. Gypenosides are the major active components of G. pentaphyllum, and they have been widely reported to possess antitumor effects in prostate cancer, gastric cancer, hepatocellular carcinoma, colon cancer, lung cancer, and breast cancer. However, research on the use of gypenoside in the treatment of bladder cancer has not been conducted. In this study, we explored the potential molecular mechanisms of gypenosides in the treatment of bladder cancer using network pharmacology and experimental validation. First, we used a network pharmacology-based method to identify both the effective components of gypenosides and the molecular mechanism underlying their antibladder cancer effects. The results were further confirmed by molecular docking, CCK8 and colony formation assays, and cell cycle and cell apoptosis analyses. Additionally, a mouse xenograft model of bladder cancer was used to investigate the antitumor effect of gypenosides in vivo. We identified 10 bioactive ingredients and 163 gene targets of gypenosides. Network exploration suggested that VEGFA, STAT3, and PI3KCA may be candidate agents for the antibladder cancer effect of gypenosides. In addition, analysis of the Kyoto Encyclopedia of Genes and Genomes pathway revealed that the phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway may play a crucial role in the mechanism of action of gypenosides against bladder cancer. Molecular docking revealed that gypenosides combine well with PI3K, AKT, and mTOR. As expected, gypenosides displayed apoptosis-inducing properties in bladder cancer cells by inactivating the PI3K/AKT/mTOR signaling pathway in vitro. Furthermore, gypenosides significantly (P < 0.05) inhibited the growth of bladder cancer cells in vivo. Mechanistically, gypenosides induced the apoptosis of bladder cancer cells via inactivation of the PI3K/AKT/mTOR signaling pathway.

Prebiotic properties of jiaogulan in the context of gut microbiome

Jiaogulan (Gynostemma pentaphyllum) is a traditional Chinese medicinal herb that has been widely used in food and supplemental products. In the last 20 years, extensive research has been conducted to investigate the medicinal prospects of jiaogulan, and in this regard, more than 200 compounds have been isolated with various medicinal properties such as anticancer, anti-obesity, anti-inflammation, and antioxidation. In respect of potential benefits, jiaogulan market is likely growing, and various food items comprised of jiaogulan (beverage, sport drinks, cola, beer, tea, bread, and noodles) have been commercialized in the United States of America, China, and other Asian countries. More recently, there has been growing interest in the prebiotic potential of jiaogulan, especially at the interface of the gut microbiota. This review focuses on the prebiotic and therapeutic aspects of saponins and polysaccharides of jiaogulan tea by summarizing the literature on cancer, obesity, antioxidant activity, and immune-modulatory properties.

Promising Therapeutic Candidate for Myocardial Ischemia/Reperfusion Injury: What Are the Possible Mechanisms and Roles of Phytochemicals?

Percutaneous coronary intervention (PCI) is one of the most effective reperfusion strategies for acute myocardial infarction (AMI) despite myocardial ischemia/reperfusion (I/R) injury, causing one of the causes of most cardiomyocyte injuries and deaths. The pathological processes of myocardial I/R injury include apoptosis, autophagy, and irreversible cell death caused by calcium overload, oxidative stress, and inflammation. Eventually, myocardial I/R injury causes a spike of further cardiomyocyte injury that contributes to final infarct size (IS) and bound with hospitalization of heart failure as well as all-cause mortality within the following 12 months. Therefore, the addition of adjuvant intervention to improve myocardial salvage and cardiac function calls for further investigation. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in Chinese herbal medicine. Great effort has been put into phytochemicals because they are often in line with the expectations to improve myocardial I/R injury without compromising the clinical efficacy or to even produce synergy. We summarized the previous efforts, briefly outlined the mechanism of myocardial I/R injury, and focused on exploring the cardioprotective effects and potential mechanisms of all phytochemical types that have been investigated under myocardial I/R injury. Phytochemicals deserve to be utilized as promising therapeutic candidates for further development and research on combating myocardial I/R injury. Nevertheless, more studies are needed to provide a better understanding of the mechanism of myocardial I/R injury treatment using phytochemicals and possible side effects associated with this approach.

Progress in the Medicinal Value, Bioactive Compounds, and Pharmacological Activities of Gynostemma pentaphyllum

Gynostemma pentaphyllum (Thunb.) Makino (GP), also named Jiaogulan in Chinese, was known to people for its function in both health care and disease treatment. Initially and traditionally, GP was a kind of tea consumed by people for its pleasant taste and weight loss efficacy. With the passing of the centuries, GP became well known as more than just a tea. Until now, numbers of bioactive compounds, including saponins (also named gypenosides, GPS), polysaccharides (GPP), flavonoids, and phytosterols were isolated and identified in GP, which implied the great medicinal worth of this unusual tea. Both in vivo and in vitro tests, ranging from different cell lines to animals, indicated that GP possessed various biological activities including anti-cancer, anti-atherogenic, anti-dementia, and anti-Parkinson's diseases, and it also had lipid-regulating effects as well as neuroprotection, hepatoprotective, and hypoglycemic properties. With the further development and utilization of GP, the research on the chemical constituents and pharmacological properties of GP were deepening day by day and had made great progress. In this review, the recent research progress in the bioactive compounds, especially gypenosides, and the pharmacological activities of GP were summarized, which will be quite useful for practical applications of GP in the treatment of human diseases.

Mechanism of gypenosides of Gynostemma pentaphyllum inducing apoptosis of renal cell carcinoma by PI3K/AKT/mTOR pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Gynostemma pentaphyllum (Thunb.) Makino is a traditional medicine commonly used in China, East Asia and Southeast Asia. In clinic, it is mainly used for hyperlipidemia and antitumor. Its antitumor activity was first recorded in "Illustrated Catalogue of Plants". Gypenosides were the main active ingredients of G. pentaphyllum. The anticancer activity of gypenosides in vivo and in vitro had been widely reported. However, the mechanism of gypenosides in renal cell carcinoma (RCC) still unclear.

AIM OF THE STUDY

In this study, we tried to investigate the active constituents from G. pentaphyllum and potential mechanisms in RCC treatment through network pharmacology and in vitro experiments.

MATERIAL/METHODS

Active compounds and their targets were evaluated and screened through TCMSP and Swiss Target Prediction database. Notably, nine preliminary screened components obtained from database were identified by LC-MS and LC-MS/MS. The targets associated with RCC were obtained from OMIM, TTD and GeneCards database. The PPI network and active component/target/pathway networks were constructed to identify the potential drug targets using String database and Cytoscape software. The functions and pathways of targets were analyzed through DAVID database. Finally, AutoDockTools 1.5.6 was used for molecular docking to assess the binding ability between compounds and targets. To support our prediction, we then explore the antitumor effect and mechanism of gypenosides by vitro experiments. CCK8 and flow cytometry were performed to evaluate cell death treated with gypenosides. Quantitative real-time PCR and Western blot were conducted to detect the changes of PI3K/AKT/mTOR signaling pathway.

RESULTS

Nine saponins and 68 targets have been screened. The hub targets covered PIK3CA, VEGFA, STAT3, JAK2, CCND1 and MAPK3. Enrichment analysis showed that the pathways mainly contained PI3K/Akt/mTOR, HIF-1, TNF, JAK-STAT and MAPK signaling pathways. Gypenosides extracted from G. pentaphyllum showed strong activity against 786-O and Caki-1 cells, and cell apoptosis were detected through Annexin V/PI dual staining assay. RT-qPCR showed that gypenosides downregulated the levels of PIK3CA, Akt and mTOR in Caki-1 and 786-O cells. Mechanistically, gypenosides induced apoptosis of RCC cells through regulating PI3K/Akt/mTOR signaling pathway which was implemented though decreasing the phosphorylation level of Akt and mTOR.

CONCLUSIONS

Gypenosides induced apoptosis of RCC cells by modulating PI3K/Akt/mTOR signaling pathway.

Triterpenoids from the genus Gynostemma: Chemistry and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

G. pentaphyllum, also known as Jiao-Gu-Lan, has been used traditionally as folk remedies for many diseases, including diabetes mellitus, metabolic syndrome, aging, and neurodegenerative diseases in China and some countries in East and Southeast Asia. It is considered as an "immortality herb" in Guizhou Province, because it was consumed regularly by the elderly native inhabitants. Other species of the same genus Gynostemma such as G. longipes and G. laxum have been used as alternatives to G. pentaphyllum in ethno-medicine in Vietnam and other Asian countries.

AIM OF THE REVIEW

The review aims to summarize up-to-date study results on Gynostemma species, including traditional usage, phytochemical profile, pharmacological activities, and toxicological studies, in order to suggest future research orientation and therapeutic applications on acute and chronic diseases.

MATERIALS AND METHODS

The relevant literature on the genus Gynostemma was gathered from secondary databases (Web of Science and PubMed), books, and official websites. The latest literature cited in this review was published in February 2020.

RESULTS

The genus Gynostemma has been widely used in traditional medicine, mainly for treatment of diabetes, hypertension, obesity, and hepatosteatosis. To date, 328 dammarane-type saponins were isolated and structurally elucidated from Gynostemma species. Crude extracts, saponin-rich fractions (gypenosides), and pure compounds were reported to show a wide range of pharmacological activities in both in vitro and in vivo experiments. The most notable pharmacological effects were anti-cancer, cardioprotective, hepatoprotective, neuroprotective, anti-diabetic, anti-obesity, and anti-inflammatory activities. Toxicological studies were conducted only on G. pentaphyllum, showing that the plant extracts were relatively safe in both acute and long-term toxicity experiments at the given dosage while no toxicological studies were reported for the other species.

CONCLUSIONS

The review summarizes current studies on traditional uses, phytochemistry, biological properties, and toxicology of medicinal Gynostemma species. Till now, the majority of publications still focused only on G. pentaphyllum. However, the promising preliminary data of other Gynostemma species indicated the research potential of this genus, both in phytochemical and pharmacological aspects. Furthermore, clinical data are required to evaluate the efficacy and undesired effects of crude extracts, standard saponin fractions, and pure compounds prepared from Gynostemma medicinal plants.

The Significant Role of the Microfilament System in Tumors

Actin is the structural protein of microfilaments, and it usually exists in two forms: monomer and polymer. Among them, monomer actin is a spherical molecule composed of a polypeptide chain, also known as spherical actin. The function of actin polymers is to produce actin filaments, so it is also called fibroactin. The actin cytoskeleton is considered to be an important subcellular filament system. It interacts with numerous relevant proteins and regulatory cells, regulating basic functions, from cell division and muscle contraction to cell movement and ensuring tissue integrity. The dynamic reorganization of the actin cytoskeleton has immense influence on the progression and metastasis of cancer as well. This paper explores the significance of the microfilament network, the dynamic changes of its structure and function in the presence of a tumor, the formation process around the actin system, and the relevant proteins that may be target molecules for anticancer drugs so as to provide support and reference for interlinked cancer treatment research in the future.

Gypenosides Inhibit Inflammatory Response and Apoptosis of Endothelial and Epithelial Cells in LPS-Induced ALI: A Study Based on Bioinformatic Analysis and in vivo/vitro Experiments

Introduction

Severe inflammatory response leads to poor prognosis of acute lung injury (ALI), the role of gypenosides (GPs) on ALI is not fully clear. The study aimed at investigating the effects of GPs on ALI.

Methods

We firstly established LPS-induced ALI mice model. Then, we tested whether GPs contributed to alleviate inflammatory response and lung injury of ALI in vivo. In order to identify specific mechanisms of the phenomenon, we conducted a bioinformatic analysis of LPS-induced ALI mice based on GEO database to identify hub differentially expressed genes (DEGs). PPI network of the DEGs was used to find hub-genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were conducted based on the DAVID database to identify which pathways the genes enriched. Then, we tested whether GPs inhibited lung injury and inflammatory response via the enriched pathways. We also tested whether GPs inhibited the apoptosis of endothelial and epithelial cells secondary to severe inflammation.

Results

We found GPs significantly alleviated lung injury and improved the survival rate of LPS-induced ALI mice in vivo. Bioinformatic analysis identified 20 hub-genes from DEGs, they were mainly enriched in NF-κB and TNF-α pathways. GPs could reduce the lung injury and inflammatory response via inhibiting NF-κB and TNF-α pathways in vivo. Our results indicated that GPs also inhibited inflammatory response of epithelial and endothelial cells via NF-κB and TNF-α pathways in vitro. Severe inflammatory response could also lead to apoptosis of endothelial and epithelial cells. Our results indicated that GPs effectively inhibited the apoptosis of endothelial and epithelial cells.

Conclusion

Our study suggested GPs contributed to alleviated lung injury in vivo and inhibited inflammation and apoptosis of endothelial and epithelial cells in vitro, providing novel strategies for the prevention and therapy for ALI.

Self-assembled mono- and bilayers on gold electrodes to assess antioxidants—a comparative study

Oxidative stress is considered as an imbalance of reactive species over antioxidants, leading to diseases and cell death. Various methods have been developed to determine the antioxidant potential of natural or synthetic compounds based on the ability to scavenge free radicals. However, most of them lack biological relevance. Here, a gold-based self-assembled monolayer (SAM) was compared with a gold-supported lipid bilayer as models for the mammalian cell membrane to evaluate the free radical scavenging activity of different antioxidants. The oxidative damage induced by reactive species was verified by cyclic and differential pulse voltammetry and measured by the increase of electrochemical peak current of a redox probe. Trolox, caffeic acid (CA), epigallocatechin gallate (EGCG), ascorbic acid (AA), and ferulic acid (FA) were used as model antioxidants. The change in the decrease of the electrochemical signal reflecting oxidative membrane damage confirms the expected protective role. Both model systems showed similar efficacies of each antioxidant, the achieved order of radical scavenging potential is as follows: Trolox > CA > EGCG > AA > FA. The results showed that the electrochemical assay with SAM-modified electrodes is a stable and powerful tool to estimate qualitatively the antioxidative activity of a compound with respect to cell membrane protection against biologically relevant reactive species.

Chinese herbal medicines for prevention and treatment of colorectal cancer: From molecular mechanisms to potential clinical applications

Worldwide, colorectal cancer (CRC) is one of the most common malignant tumors, leading to immense social and economic burdens. Currently, the main treatments for CRC include surgery, chemotherapy, radiotherapy and immunotherapy. Despite advances in the diagnosis and treatment of CRC, the prognosis for CRC patients remains poor. Furthermore, the occurrence of side effects and toxicities severely limits the clinical use of these therapies. Therefore, alternative medications with high efficacy but few side effects are needed. An increasing number of modern pharmacological studies and clinical trials have supported the effectiveness of Chinese herbal medicines (CHMs) for the prevention and treatment of CRC. CHMs may be able to effectively reduce the risk of CRC, alleviate the adverse reactions caused by chemotherapy, and prolong the survival time of patients with advanced CRC. Studies of molecular mechanisms have provided deeper insight into the roles of molecules from CHMs in treating CRC. This paper summarizes the current understanding of the use of CHMs for the prevention and treatment of CRC, the main molecular mechanisms involved in these processes, the role of CHMs in modulating chemotherapy-induced adverse reactions, and CHM's potential role in epigenetic regulation of CRC. The current study provides beneficial information on the use of CHMs for the prevention and treatment of CRC in the clinic, and suggests novel directions for new drug discovery against CRC.

Medicinal Value and Potential Therapeutic Mechanisms of Gynostemma pentaphyllum (Thunb.) Makino and Its Derivatives: An Overview

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Gynostemma pentaphyllum (Thunb.) Makino (GpM) and its derivatives, especially gypenosides (Gyps), are widely used as safe and convenient natural herbal drugs for the treatment of many diseases for a long time, and Gyps have different oral bioavailability (OB) values and low ability to cross the blood-brain barrier (BBB). The effects of GpM and isolates on fibrosis, inflammation, oxidation, proliferation and migration are proved. GpM shows bidirectional regulation effect on proliferation, oxidation and apoptosis in tumor and non-tumor cells. GpM and its extractions can resist proliferation, activate oxidation and apoptosis in tumor cells and have opposite effects on non-tumor cells. We succinctly present some current views of medicinal value and potential therapeutic mechanisms of GpM and its derivatives.

Tripterine inhibits proliferation, migration and invasion of breast cancer MDA-MB-231 cells by up-regulating microRNA-15a

Breast cancer is the most commonly diagnosed cancer in women worldwide. Tripterine is an important active component isolated from Triperygium wilfordii Hook F. This study investigated the effects of tripterine on breast cancer cell proliferation, migration, invasion and apoptosis, as well as microRNA-15a (miR-15a) expression. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to measure the expression of miR-15a. Cell transfection was conducted to change the expression of miR-15a. Viability, proliferation, migration, invasion and apoptosis of MDA-MB-231 cells were assessed using the cell counting kit-8 (CCK-8) assay, BrdU incorporation assay, Annexin V-FITC/PI apoptosis detection kit and two-chamber Transwell assay, respectively. Expression of key factors involving in cell proliferation, migration, invasion and apoptosis, as well as the PI3K/AKT and JNK pathways, were evaluated using Western blotting. We found that tripterine inhibited MDA-MB-231 cell viability, proliferation, migration and invasion, but induced cell apoptosis. Moreover, tripterine up-regulated the expression of miR-15a in a concentration-dependent manner and miR-15a participated in the effects of tripterine on MDA-MB-231 cell proliferation, migration, invasion and apoptosis. In addition, tripterine inactivated PI3K/AKT and JNK pathways in MDA-MB-231 cells by up-regulating miR-15a. In conclusion, tripterine inhibited proliferation, migration and invasion of breast cancer MDA-MB-231 cells by up-regulating miR-15a and inactivating PI3K/AKT and JNK pathways.

Natural gypenosides: targeting cancer through different molecular pathways

The second foremost cause of mortality around the word is cancer. Conventional therapies, such as radiation, surgery, and chemotherapy have limited accessibility owing to secondary resistance. Therefore, convenient, safe, and nonresistant drugs are urgently needed. Plant-derived natural products have attracted considerable interest owing to their high efficacy, low toxicity, and convenience. Gypenosides (Gyp) inhibit invasion, migration, metastasis, and proliferation and induce apoptosis in different cancers, including oral, lung, colorectal, hepatocellular, and leukemic cancers through different molecular pathways. This review summarizes Gyp studies on cancer to serve as a reference for further research and clinical trials.

Chinese medicine CGA formula ameliorates liver fibrosis induced by carbon tetrachloride involving inhibition of hepatic apoptosis in rats

ETHNOPHARMACOLOGICAL REVELVANCE

CGA consisting of Cordyceps sinensis mycelia polysaccharide, gypenosides and amygdalin, was demonstrated to be the effective components formula in Fuzheng Huayu (FZHY) capsule, a traditional Chinese medicine approved by China food and drug administration for treatment of liver fibrosis and to inhibit transforming growth factor-β1 (TGF-β1) signaling, previously.

AIM OF THE STUDY

To evaluate the effects of CGA on hepatic apoptosis in liver fibrosis induced by carbon tetrachloride (CCl₄).

MATERIALS AND METHODS

The hepatic injury and histology was detected by serum biomarker assay and hematoxylin-eosin staining. The hepatic collagen was illustrated by Sirius red staining and hydroxyproline (Hyp) concentration. The hepatic stellate cells (HSCs) activation and hepatic apoptosis was visualized by immunohistochemical analysis of α-smooth muscle actin (α-SMA) and terminal deoxynucleotidyl transferase-mediated dUPT nick-end labeling (TUNEL) assay respectively. The protein expression of collagen type I (Col-I), α-SMA, TGF-β1, Fas, tumor necrosis factor receptor 1 (TNF-R1), cleaved-caspase-8, cleaved-caspase-10, cleaved-caspase-9, cleaved-caspase-3, mitochondrial Bcl-2, Bcl-2 associated X protein (Bax), Bcl-2 homologous antagonist/killer (Bak), cytochrome C and cytoplasmic cytochrome C was detected by western-blot.

RESULTS

CGA or FZHY ameliorated liver histological changes, decreasing serum alanine aminotransferase, aspartate aminotransferase, hepatic Hyp, TUNEL positive-stained area, and down-regulated the protein expression of α-SMA, TGF-β1, Col-I, Fas, TNF-R1, cleaved-caspase-8, cleaved-caspase-10, cleaved-caspase-9, and cleaved-caspase-3, mitochondrial Bax, Bak, and cytoplasmic cytochrome C, while restored the expression of mitochondrial Bcl-2 and cytochrome C.

CONCLUSION

CGA formula ameliorates liver fibrosis induced by CCl₄, which is correlated to its inhibition on hepatic apoptosis.

Gypenoside L Inhibits Proliferation of Liver and Esophageal Cancer Cells by Inducing Senescence

Senescence is an irreversible state of cell cycle arrest that can be triggered by multiple stimuli, such as oxygen reactive species and DNA damage. Growing evidence has proven that senescence is a tumor-suppressive approach in cancer treatment. Therefore, developing novel agents that modulate senescence may be an alternative strategy against cancer. In our study, we investigated the inhibitory effect of gypenoside L (Gyp-L), a saponin isolated from Gynostemma pentaphyllum, on cancer cell growth. We found that Gyp-L increased the SA-β-galactosidase activity, promoted the production of senescence-associated secretory cytokines, and inhibited cell proliferation of human liver and esophageal cancer cells. Moreover, Gyp-L caused cell cycle arrest at S phase, and activated senescence-related cell cycle inhibitor proteins (p21 and p27) and their upstream regulators. In addition, Gyp-L activated p38 and ERK MAPK pathways and NF-κB pathway to induce senescence. Consistently, adding chemical inhibitors efficiently counteracted the Gyp-L-mediated senescence, growth inhibition, and cell cycle arrest in cancer cells. Furthermore, treatment with Gyp-L, enhanced the cytotoxicity of clinic therapeutic drugs, including 5-fluorouracil and cisplatin, on cancer cells. Overall, these results indicate that Gyp-L inhibits proliferation of cancer cells by inducing senescence and renders cancer cells more sensitive to chemotherapy.

Kaempferol inhibits proliferation, migration, and invasion of liver cancer HepG2 cells by down-regulation of microRNA-21

Liver cancer is one of the most common and lethal cancers in human digestive system, which kills more than half a million people every year worldwide. This study aimed to investigate the effects of kaempferol, a flavonoid compound isolated from vegetables and fruits, on hepatic cancer HepG2 cell proliferation, migration, invasion, and apoptosis, as well as microRNA-21 (miR-21) expression. Cell viability was detected using cell counting kit-8 (CCK-8) assay. Cell proliferation was measured using 5-bromo-2′-deoxyuridine (BrdU) incorporation assay. Cell apoptosis was assessed using Guava Nexin assay. Cell migration and invasion were determined using two-chamber migration (invasion) assay. Cell transfection was used to change the expression of miR-21. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to analyze the expressions of miR-21 and phosphatase and tensin homologue (PTEN). Expression of key proteins involved in proliferation, apoptosis, migration, invasion, and phosphatidylinositol 3-kinase/protein kinase 3/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway were evaluated using western blotting. Results showed that kaempferol significantly inhibited HepG2 cell proliferation, migration, and invasion, and induced cell apoptosis. Kaempferol remarkably reduce the expression of miR-21 in HepG2 cells. Overexpression of miR-21 obviously reversed the effects of kaempferol on HepG2 cell proliferation, migration, invasion, and apoptosis. Moreover, miR-21 negatively regulated the expression of PTEN in HepG2 cells. Kaempferol enhanced the expression of PTEN and inactivated PI3K/AKT/mTOR signaling pathway in HepG2 cells. In conclusion, kaempferol inhibited proliferation, migration, and invasion of HepG2 cells by down-regulating miR-21 and up-regulating PTEN, as well as inactivating PI3K/AKT/mTOR signaling pathway.

Triptolide inhibits the proliferation and migration of medulloblastoma Daoy cells by upregulation of microRNA-138

Medulloblastoma is a primitive neuroectodermal-derived brain tumor and the most common malignant brain tumor in children. Triptolide (TPL) is the major active component extracted from Tripterygium wilfordii Hook F. This study aimed to explore the effects of TPL on medulloblastoma cell proliferation, migration, and apoptosis, as well as the underlying possible molecular mechanism. Viability, proliferation, and apoptosis of Daoy cells were measured using cell counting kit-8 assay, 5-bromo-2'-deoxyuridine incorporation assay, and Guava Nexin assay, respectively. Cell migration was detected using two-chamber transwell assay and wound healing assay. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to determine the relative expression of microRNA-138 (miR-138) in Daoy cells. Cell transfection was used to change the expression of miR-138 in cells. Western blot analysis was used to analyze the expression of key factors involved in cell apoptosis, cell migration, the phosphatidylinositol 3-kinase (PI3K)/protein kinase 3 (AKT) pathway, and the Notch pathway in Daoy cells. We found that TPL significantly inhibited the viability, proliferation, and migration of Daoy cells but promoted Daoy cell apoptosis. The expression levels of matrix metalloproteinases (MMP)-2 and MMP-9 after TPL treatment were decreased. The expression of miR-138 in Daoy cells after TPL treatment was increased. Suppression of miR-138 obviously reversed the TPL-induced Daoy cell proliferation, migration inhibition, and cell apoptosis enhancement, as well as the inactivation of the PI3K/AKT and Notch pathways. Cyclin-dependent kinase 6 (CDK6) was a direct target gene of miR-138, which might be involved in the antitumor effects of TPL on Daoy cells. In conclusion, our study verified that TPL exerted anticancer effects on medulloblastoma cells possibly via upregulating miR-138 and inactivating the PI3K/AKT and Notch pathways.

Triptolide Inhibits Proliferation and Migration of Human Neuroblastoma SH-SY5Y Cells by Upregulating MicroRNA-181a

Neuroblastoma is the primary cause of cancer-related death for children 1 to 5 years of age. New therapeutic strategies and medicines are urgently needed. This study aimed to investigate the effects of triptolide (TPL), the major active component purified from Tripterygium wilfordii Hook F, on neuroblastoma SH-SY5Y cell proliferation, migration, and apoptosis, as well as underlying potential mechanisms. We found that TPL inhibited SH-SY5Y cell viability, proliferation, and migration, but induced cell apoptosis. The expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 after TPL treatment in SH-SY5Y cells was decreased. The expression of microRNA-181a (miR-181a) was upregulated after TPL treatment. Moreover, suppression of miR-181a reversed the effects of TPL on SH-SY5Y cell proliferation, apoptosis, and migration. Overexpression of miR-181a enhanced the TPL-induced activation of p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor κ light chain enhancer of activated B cells (NF-κB) pathways. In conclusion, our research verified that TPL inhibited the proliferation and migration of human neuroblastoma SH-SY5Y cells by upregulating the expression of miR-181a.

NOX2-Mediated TFEB Activation and Vacuolization Regulate Lysosome-Associated Cell Death Induced by Gypenoside L, a Saponin Isolated from Gynostemma pentaphyllum

Downregulation of apoptotic signal pathway and activation of protective autophagy mainly contribute to the chemoresistance of tumor cells. Therefore, exploring efficient chemotherapeutic agents or isolating novel natural products that can trigger nonapoptotic and nonautophagic cell death such as lysosome-associated death is emergently required. We have recently extracted a saponin, gypenoside L (Gyp-L), from Gynostemma pentaphyllum and showed that Gyp-L was able to induce nonapoptotic cell death of esophageal cancer cells associated with lysosome swelling. However, contributions of vacuolization and lysosome to cell death remain unclear. Herein, we reveal a critical role for NADPH oxidase NOX2-mediated vacuolization and transcription factor EB (TFEB) activation in lysosome-associated cell death. We found that Gyp-L initially induced the abnormal enlarged and alkalized vacuoles, which were derived from lipid rafts dependent endocytosis. Besides, NOX2 was activated to promote vacuolization and mTORC1-independent TFEB-mediated lysosome biogenesis. Finally, raising lysosome pH could enhance Gyp-L induced cell death. These findings suggest a protective role of NOX2-TFEB-mediated lysosome biogenesis in cancer drug resistance and the tight interaction between lipid rafts and vacuolization. In addition, Gyp-L can be utilized as an alternative option to overcome drug-resistance though inducing lysosome associated cell death.

Anti-cancer effects of Gynostemma pentaphyllum (Thunb.) Makino (Jiaogulan)

Gynostemma pentaphyllum (Thunb.) Makino (GpM) (Jiaogulan) has been widely used in Chinese medicine for the treatment of several diseases, including hepatitis, diabetes and cardiovascular disease. Furthermore, GpM has recently been shown to exhibit potent anti-cancer activities. In this review, we have summarized recent research progress on the anti-cancer activities and mechanisms of action of GpM, as well as determining the material basis for the anti-cancer effects of GpM by searching the PubMed, Web of Science and China National Knowledge Infrastructure databases. The content of this review is based on studies reported in the literature pertaining to the chemical components or anti-cancer effects of GpM up until the beginning of August, 2016. This search of the literature revealed that more than 230 compounds have been isolated from GpM, and that most of these compounds (189) were saponins, which are also known as gypenosides. All of the remaining compounds were classified as sterols, flavonoids or polysaccharides. Various extracts and fractions of GpM, as well as numerous pure compounds isolated from this herb exhibited inhibitory activity towards the proliferation of cancer cells in vitro and in vivo. Furthermore, the results of several clinical studies have shown that GpM formula could have potential curative effects on cancer. Multiple mechanisms of action have been proposed regarding the anti-cancer activities of GpM, including cell cycle arrest, apoptosis, inhibition of invasion and metastasis, inhibition of glycolysis and immunomodulating activities.

Selective Pro-Apoptotic Activity of Novel 3,3'-(Aryl/Alkyl-Methylene)Bis(2-Hydroxynaphthalene-1,4-Dione) Derivatives on Human Cancer Cells via the Induction Reactive Oxygen Species

Selective induction of apoptosis in cancer cells barring the normal cells is considered as an effective strategy to combat cancer. In the present study, a series of twenty-two (22) synthetic 3,3'-(aryl/alkyl-methylene)bis(2-hydroxynaphthalene-1,4-dione) bis-lawsone derivatives were assayed for their pro-apoptotic activity in six different cell lines (five cancerous and one normal) using MTT assay. Out of these 22 test compounds, 1j was found to be the most effective in inducing apoptosis in human glioma cells (CCF-4) among the different cell lines used in the study. The activity of this compound, 1j, was then compared to a popular anticancer drug, cisplatin, having limited usage because of its nephrotoxic nature. In this study, 1j derivative showed much less toxicity to the normal kidney cells compared to cisplatin, thus indicating the superiority of 1j as a possible anticancer agent. This compound was observed to induce apoptosis in the glioma cells by inducing the caspase dependent apoptotic pathways via ROS and downregulating the PI3K/AKT/mTOR pathway. Estimation of different oxidative stress markers also confirms the induction of oxidative stress in 1j exposed cancer cells. The toxicity of 1j compound toward cancer cells was confirmed further by different flow cytometrical analyses to estimate the mitochondrial membrane potential and cell cycle. The sensitivity of malignant cells to apoptosis, provoked by this synthetic derivative in vitro, deserves further studies in suitable in vivo models. These studies not only identified a novel anticancer drug candidate but also help to understand the metabolism of ROS and its application in cancer treatment.

Mechanistic study of the anti-cancer effect of Gynostemma pentaphyllum saponins in the Apc(Min/+) mouse model

Gynostemma pentaphyllum saponins (GpS) have been shown to have anti-cancer activity. However, the underlying mechanisms remain unclear. In this study, we used the Apc(Min) (/+) colorectal cancer (CRC) mouse model to investigate the anti-cancer effect of GpS and we demonstrated that GpS treatment could significantly reduce the number and size of intestinal polyps in Apc(Min) (/+) mice. In order to identify the potential targets and mechanisms involved, a comparative proteomics analysis was performed and 40 differentially expressed proteins after GpS treatment were identified. Bioinformatics analyses suggested a majority of these proteins were involved in processes related to cellular redox homeostasis, and predicted Raf-1 as a potential target of GpS. The upregulation of two proteins known to be involved in redox homeostasis, peroxiredoxin-1 (Prdx1) and peroxiredoxin-2 (Prdx2), and the downregulation of Raf-1 were validated using Western blot analysis. After further investigation of the associated signaling networks, we postulated that the anti-cancer effect of GpS was mediated through the upregulation of Prdx1 and Prdx2, suppression of Ras, RAF/MEK/ERK/STAT, PI3K/AKT/mTOR signaling and modulation of JNK/p38 MAPK signaling. We also examined the potential combinatorial effect of GpS with the chemotherapeutic 5-fluorouracil (5-FU) and found that GpS could enhance the anti-cancer efficacy of 5-FU, further suppressing the number of polyps in Apc(Min/+) mice. Our findings highlight the potential of GpS as an anti-cancer agent, the potential mechanisms of its anti-cancer activities, and its effect as an adjuvant of 5-FU in the chemotherapy of CRC.

Gypenoside L, Isolated from Gynostemma pentaphyllum, Induces Cytoplasmic Vacuolation Death in Hepatocellular Carcinoma Cells through Reactive-Oxygen-Species-Mediated Unfolded Protein Response

Exploring novel anticancer agents that can trigger non-apoptotic or non-autophagic cell death is urgent for cancer treatment. In this study, we screened and identified an unexplored anticancer activity of gypenoside L (Gyp-L) isolated from Gynostemma pentaphyllum. We showed that treatment with Gyp-L induces non-apoptotic and non-autophagic cytoplasmic vacuolation death in human hepatocellular carcinoma (HCC) cells. Mechanically, Gyp-L initially increased the intracellular reactive oxygen species (ROS) levels, which, in turn, triggered protein ubiquitination and unfolded protein response (UPR), resulting in Ca(2+) release from endoplasm reticulum (ER) inositol trisphosphate receptor (IP3R)-operated stores and finally cytoplasmic vacuolation and cell death. Interruption of the ROS-ER-Ca(2+) signaling pathway by chemical inhibitors significantly prevented Gyp-L-induced vacuole formation and cell death. In addition, Gyp-L-induced ER stress and vacuolation death required new protein synthesis. Overall, our works provide strong evidence for the anti-HCC activity of Gyp-L and suggest a novel therapeutic option by Gyp-L through the induction of a unconventional ROS-ER-Ca(2+)-mediated cytoplasmic vacuolation death in human HCC.

Gypenoside attenuates renal ischemia/reperfusion injury in mice by inhibition of ERK signaling

Gynostemma pentaphyllum is a traditional Chinese medicine reported to possess a wide range of health benefits. As the major component of G. pentaphyllum, gypenoside (GP) displays various anti-inflammatory and anti-oxidant properties. However, it is unclear whether GP can protect against ischemia/reperfusion (I/R)-induced renal injury, and the underlying molecular mechanisms associated with this process remain unknown. In the present study, a renal I/R injury model in C57BL/6 mice was established. It was observed that, following I/R, serum concentrations of creatinine (Cr) and blood urea nitrogen (BUN) were significantly increased (P<0.01), indicating renal injury. Pretreatment with GP (50 mg/kg) significantly inhibited I/R-induced upregulation of serum Cr and BUN (P<0.01). Furthermore, renal malondialdehyde levels were significantly reduced in the I/R+GP group, compared with the I/R group (P<0.01), whereas renal tissue superoxide dismutase activity was significantly higher in the I/R+GP group compared with the I/R group (P<0.01). Further investigation demonstrated that pretreatment with GP produced inhibitory effects on the I/R-induced production of pro-inflammatory cytokines, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α and interferon-γ (P<0.01). In addition, heme oxygenase 1 (HO-1) expression levels were significantly increased in the I/R group compared with the control (P<0.01), indicating the presence of oxidative damage. However, the I/R-induced upregulation of HO-1 was significantly attenuated by pretreatment with GP (P<0.01), which also suppressed I/R-induced apoptosis by inhibiting pro-apoptotic Bax and upregulating anti-apoptotic Bcl-2 in renal cells (P<0.01). Finally, the activity of ERK signaling was significantly increased in the I/R+GP group compared with the I/R group (P<0.05), which may be associated with the protective effect of GP against I/R-induced renal cell apoptosis. To conclude, the present results suggest that GP produces a protective effect against I/R-induced renal injury as a result of its anti-inflammatory and anti-apoptotic properties.

Complete chloroplast genome sequence of the medicinal plant Gynostemma pentaphyllum

We report the complete chloroplast genome sequence of Gynostemma pentaphyllum, a well-known traditional Chinese medicine, which produces triterpenoid saponins similar to Panax ginseng. The assembled chloroplast genome (cpDNA) was 157,654 bp in length and structurally divided into four distinct regions, namely, large single copy region (86,794 bp), small single copy region (18,654 bp) and a pair of inverted repeat regions (26,103 bp). A total of 143 genes were annotated, including 87 protein-coding genes, 10 tRNA genes and 46 rRNA genes. Phylogenetic analysis revealed that the chloroplast genome sequence of G. pentaphyllum is most closely related to Cucumis melo.

Gypenosides Synergistically Enhances the Anti-Tumor Effect of 5-Fluorouracil on Colorectal Cancer In Vitro and In Vivo: A Role for Oxidative Stress-Mediated DNA Damage and p53 Activation

Objective

5-Fluorouracil (5-Fu) has been widely used as a first-line drug for colorectal cancer (CRC) treatment but limited by drug resistance and severe toxicity. The chemo-sensitizers that augment its efficiency and overcome its limitation are urgently needed. Gypenosides (Gyp), the main components from Gynostemma pentaphyllum (Thunb.) Makino, has shown potential anti-tumor property with little side-effect. Here, we carefully explored the chemo-sensitization of Gyp to potentiate the anti-tumor effect of 5-Fu in vitro and in vivo.

Methodology / Principal Findings

3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltertrazolium bromide tetrazolium assay and colony formation test reveal that Gyp could significantly enhance the 5-Fu-caused SW-480,SW-620 and Caco2 cells viability loss. Calcusyn analysis shows that Gyp acts synergistically with 5-Fu. Annexin V-PE/7-AAD staining indicates 5-Fu + Gyp could induce SW-480 cell apoptosis. The activations of caspase 3, caspase 9 and poly (ADP-ribose) polymerase (PARP) were involved in the process. Gyp was also found to up-regulate 5-Fu-caused phospho-p53 expression and thus augment 5-Fu-induced G0/G1 phase arrest. Gyp elevated intracellular ROS level, significantly enhanced 5-Fu-triggered DNA damage response as evidenced by flow cytometry, comet assay and the expression of Ser139-Histone H2A.X. Inhibition of ROS and p53 respectively reversed the cell death induced by 5-Fu + Gyp, suggesting the key roles of ROS and p53 in the process. Moreover, 5-Fu and Gyp in combination exhibits much superior tumor volume and weight inhibition on CT-26 xenograft mouse model in comparison to 5-Fu or Gyp alone. Immunohistochemistry analysis suggests the combinations greatly suppressed tumor proliferation. Preliminary toxicological results show that 5-Fu + Gyp treatment is relatively safe.

Conclusions

As a potential chemo-sensitizer, Gyp displays a splendid synergistic effect with 5-Fu to inhibit cancer cell proliferation and tumor growth. By using 5-Fu and Gyp in combination would be a promising therapeutic strategy for CRC treatment.

Inhibition of the Na+/H+ antiporter induces cell death in TF-1 erythroleukemia cells stimulated by the stem cell factor

Leukemia cells produce acidic metabolites due to their high metabolic condition. An alkaline pHi (intracellular pH) shift, caused by activation of the Na+/H+ exchange, is an important event in the mechanism of growth factor activity. However, the role of the Na(+)/H(+) exchanger in the survival of erythroleukemia TF-1 cells has not yet been studied in detail. The aim of this study was to identify the effects of 5-(N-ethyl-N-isopropyl) amiloride (EIPA), a highly specific blocker of the Na(+)/H(+) exchanger, on the survival of SCF-dependent TF-1 cells. The effects of EIPA on survival and mitochondrial membrane potential were studied when exposing wild type TF-1 cells and TF-1 cells expressing bcl-2 to EIPA for 48h. Ectopic expression of the bcl-2 gene maintained a mildly alkaline pH and prevented the simultaneous appearance of apoptosis and autophagy (typically displayed by TF-1 cells) in the presence of EIPA. Consistent with Stem Cell Factor (SCF) function, we found that this molecule rescued TF-1 cells during autophagy but not apoptosis, allowing these cells to subsequently respond to GM-CSF. Serum deprivation or SCF withdrawal induced cell death at 36h in TF-1 and TF-1 neo cells, whereas TF-1/bcl-2 cells tended to undergo apoptosis and show acidic vacuoles after 96h, pointing to a transient anti-apoptotic effect. The present study shows the suppressive effect of EIPA on the proliferation of leukemia cell line stimulated with SCF, apparently by decreasing the mitochondria membrane potential and averting alkalinization. Through the constitutive expression of bcl-2, TF-1 cells were survival factor independent. Proliferation in these cells was not affected by EIPA at the concentrations used against parental TF-1 cells, indicating that the inhibitory effect in SCF-stimulated cells can be attributed to specific blocking of the Na(+)/H(+) exchanger.