Arctigenin induces cell cycle arrest by blocking the phosphorylation of Rb via the modulation of cell cycle regulatory proteins in human gastric cancer cells

Arctigenin from Forsythia viridissima Fruit Inhibits the Replication of Human Coronavirus

Coronavirus can cause various diseases, from mild symptoms to the recent severe COVID-19. The coronavirus RNA genome is frequently mutated due to its RNA nature, resulting in many pathogenic and drug-resistant variants. Therefore, many medicines should be prepared to respond to the various coronavirus variants. In this report, we demonstrated that Forsythia viridissima fruit ethanol extract (FVFE) effectively reduces coronavirus replication. We attempted to identify the active compounds and found that actigenin from FVFE effectively reduces human coronavirus replication. Arctigenin treatment can reduce coronavirus protein expression and coronavirus-induced cytotoxicity. These results collectively suggest that arctigenin is a potent natural compound that prevents coronavirus replication.

A systematic review on botany, ethnopharmacology, quality control, phytochemistry, pharmacology and toxicity of Arctium lappa L. fruit

ETHNOPHARMACOLOGICAL RELEVANCE

Arctium lappa L., is a biennial plant that grows around the Eurasia. Many parts of Arctium lappa L. (roots, leaves and fruits, etc.) are medically used in different countries. Arctium lappa L. fruit, also called Arctii Fructus, is traditionally applied to dispel wind-heat, ventilate lung to promote eruption, remove toxicity substance and relieve sore throat.

THE AIM OF THE REVIEW

The review aims to integrate the botany, ethnopharmacology, quality control, phytochemistry, pharmacology, derivatives and toxicity information of Arctii Fructus, so as to facilitate future research and explore the potential of Arctii Fructus as an agent for treating diseases.

MATERIALS AND METHODS

Related knowledge about Arctii Fructus were acquired from Science Direct, GeenMedical, PubMed, China National Knowledge Infrastructure (CNKI), Web of Science, Pharmacopoeia of the People's Republic of China, Doctoral and Master's thesis, ancient books, etc. RESULTS: Arctii Fructus as an herb used for medicine and food was pervasively distributed and applicated around the world. It was traditionally used to treat anemopyretic cold, dyspnea and cough, sore throat, etc. To date, more than 200 compounds have been isolated and identified from Arctii Fructus. It contained lignans, phenolic acids and fatty acids, terpenoids, volatile oils and others. Lignans, especially arctigenin and arctiin, had the extensive pharmacological effects such as anti-cancer, antiviral, anti-inflammatory activities. The ester derivatives of arctigenin had the anti-cancer, anti-Alzheimer's disease and immunity enhancing effects. Although Arctii Fructus extract had no toxicity, arctigenin was toxic at a certain dose. The alleviating effects of Arctii Fructus on chronic inflammation and ageing have been demonstrated by clinical studies.

CONCLUSION

Arctii Fructus is regarded as a worthy herb with many chemical components and various pharmacological effects. Several traditional applications have been supported by modern pharmacological research. However, their action mechanisms need to be further studied. Although many chemical components were isolated from Arctii Fructus, the current research mainly focused on lignans, especially arctiin and arctigenin. Therefore, it is very important to deeply clarify the pharmacological activities and action mechanism of the compounds and make full medicinal use of the resources of Arctii Fructus.

Preclinical Evidence that Arctigenin Effectively and Selectively Targets Clear Cell Renal Cell Carcinoma Via Suppressing EGFR and RhoA

Clear cell renal cell carcinoma (ccRCC) has poor clinical outcomes and necessitates new treatment options. Epidermal growth factor receptor (EGFR) is a potential therapeutic target, due to the associations with various carcinomas' progression. Arctigenin, a natural compound of Arctium lappa, has been shown to display anticancer abilities in various carcinomas. Cellular assays and combination studies were conducted using arctigenin and anti-ccRCC drugs. In vivo efficacy of arctigenin was determined using ccRCC xenograft mouse model. Immunoblotting and biochemistry analysis were applied to investigate the signaling affected by arctigenin. Arctigenin inhibits growth, migration, and survival of ccRCC cells while sparing normal kidney cells. Arctigenin acts synergistically with 5-FU and sorafenib but not temsirolimus in inhibiting ccRCC cells. Synergism of arctigenin with 5-FU and sorafenib was further shown in ccRCC xenograft mouse model. The combination of arctigenin with clinical anti-RCC drugs completely inhibits tumor growth without tumor progression even for an extended time period. Mechanistically, arctigenin inhibits migration in a RhoA-dependent manner while inhibits growth via suppressing EGFR-mediated signaling pathways. Our findings suggest that arctigenin performs well to add to current treatment in ccRCC and confirm the value to target EGFR to improve therapy in RCC.

Arctigenin: pharmacology, total synthesis, and progress in structure modification

Arctium lappa L. is a prevalent medicinal herb and a health supplement that is commonly used in Asia. Over the last few decades, the bioactive component arctigenin has attracted the attention of researchers because of its anti-inflammatory, antioxidant, immunomodulatory, multiple sclerosis fighting, antitumor, and anti-leukemia properties. After summarising the research and literature on arctigenin, this study outlines the current status of research on pharmacological activity, total synthesis, and structural modification of arctigenin. The purpose of this study is to assist academics in obtaining a more comprehensive understanding of the research progress on arctigenin and to provide constructive suggestions for further investigation of this useful molecule.

Emergence of nutrigenomics and dietary components as a complementary therapy in cancer prevention

Cancer is an illness characterized by abnormal cell development and the capability to infiltrate or spread to rest of the body. A tumor is the term for this abnormal growth that develops in solid tissues like an organ, muscle, or bone and can spread to other parts of the body through the blood and lymphatic systems. Nutrition is a critical and immortal environmental component in the development of all living organisms encoding the relationship between a person's nutrition and their genes. Nutrients have the ability to modify gene expression and persuade alterations in DNA and protein molecules which is researched scientifically in nutrigenomics. These interactions have a significant impact on the pharmacokinetic properties of bioactive dietary components as well as their site of action/molecular targets. Nutrigenomics encompasses nutrigenetics, epigenetics, and transcriptomics as well as other "omic" disciplines like proteomics and metabolomics to explain the vast disparities in cancer risk among people with roughly similar life style. Clinical trials and researches have evidenced that alternation of dietary habits is potentially one of the key approaches for reducing cancer risk in an individual. In this article, we will target how nutrigenomics and functional food work as preventive therapy in reducing the risk of cancer.

Anti-inflammatory activity of arctigenin against PCV2 infection in a mouse model

Arctigenin (ACT) is a novel anti-inflammatory lignan extracted from Arctium lappa L, a herb commonly used in traditional Chinese herbal medicine. In this study, we investigated the molecular mechanism whereby ACT inhibits PCV2 infection-induced proinflammatory cytokine production in vitro and in vivo. We observed that in PCV2 infection+ACT treated PK-15 cells, proinflammatory cytokine production was significantly reduced, compared to the PCV2-infected cells. The transfection and luciferase reporter assay confirmed that ACT suppressed NF-κB signalling pathway activation following PCV2 infection in PK-15 cells. Furthermore, western blotting demonstrated that ACT suppressed the NF-κB signal pathway in PCV2 infection-stimulated PK-15 cells by inhibiting the translocation of p65 from the cytoplasm to the nucleus and IκBα phosphorylation. BALB/c mice were used as a model to evaluate the anti-inflammatory effect of ACT in vivo. We found that the BALB/c mice inoculated with PCV2 infection + ACT treated showed a significant reduction of proinflammatory cytokine production in serum, lung and spleen tissue, compared to the PCV2-infected mice. Western blotting confirmed that ACT suppressed the NF-κB signal pathway in PCV2-infected mice by inhibiting the translocation of p65 from the cytoplasm to the nucleus and IκBα phosphorylation in lung tissue. Our studies first demonstrate that ACT inhibits PCV2 infection-induced proinflammatory cytokine production by suppressing the phosphorylation and nuclear translocation of NF-κB in vitro and in vivo. These results will help further develop ACT as a Traditional Chinese herbal medicine remedy in the treatment of porcine circovirus-associated diseases.

Fructus arctii: an overview on its traditional uses, pharmacology and phytochemistry

OBJECTIVES

Fructus arctii (F. arctii) is the dried ripe fruit of Arctium lappa Willd (Asteraceae). It is being used as a traditional medicine in China, Japan, Iran, Europe, Afghanistan, India, etc. for cough, inflammation, clearing the heat, detoxification, cancer and diabetes. This review summarized the botanical description, distribution, ethnopharmacology, bioactive constituents and pharmacological actions of F. arctii including methods to assess its quality. In addition, this review also provides insights into future research directions on F. arctii to further explore its bioactive constituents, mechanism involved in pharmacological activity, and clinical use including the development of new analytical methods for assessing the quality.

KEY FINDINGS

The comprehensive analysis of the literature revealed that F. arctii contains lignans, volatile oil, flavonoids, sesquiterpenoids, triterpenes, phenolic acids, etc. Experimental studies on various extracts and drug formulations showed that it has antioxidant, antimicrobial, hypoglycaemic, lipid-lowering, anti-inflammatory, analgesic, antiviral, anti-tumour activity, etc.

SUMMARY

The pharmacological activity of a few major constituents in F. arctii have been identified. However, there are still need more studies and more new technologies to prove the pharmacological activity and the effective mechanism of the other constituents that undergoing uncertain. Except for the animal experiments, clinical studies should be carried out to provide the evidence for clinical application.

Arctigenin, an anti-tumor agent; a cutting-edge topic and up-to-the-minute approach in cancer treatment

Today, herbal-derived compounds are being increasingly studied in cancer treatment. Over the past decade, Arctigenin has been introduced as a bioactive dibenzylbutyrolactone lignan which is found in Chinese herbal medicines. In addition to anti-microbial, anti-inflammatory, immune-modulatory functions, Arctigenin has attracted growing attention due to its anti-tumor capabilities. It has been shown that Arctigenin can induce apoptosis and necrosis and abolish drug resistance in tumor cells by inducing apoptotic signaling pathways, caspases, cell cycle arrest, and the modulating proteasome. Moreover, Arctigenin mediates other anti-tumor functions through several mechanisms. It has been demonstrated that Arctigenin can act as an anti-inflammatory compound to inhibit inflammation in the tumor microenvironment. It also downregulates factors involved in tumor metastasis and angiogenesis, such as matrix metalloproteinases, N-cadherin, TGF-β, and VEGF. Additionally, Arctigenin, through modulation of MAPK signaling pathways and stress-related proteins, is able to abolish tumor cell growth in nutrient-deprived conditions. Due to the limited solubility of Arctigenin in water, it is suggested that modification of this compound through amino acid esterification can improve its pharmacogenetic properties. Collectively, it is hoped that using Arctigenin or its derivates might introduce new chemotherapeutic approaches in future treatment.

Natural Lignans Honokiol and Magnolol as Potential Anticarcinogenic and Anticancer Agents. A Comprehensive Mechanistic Review

Plant lignans constitute an important group of polyphenols, which have been demonstrated to significantly induce cancer cell death and suppress cancer cell proliferation with minimal toxicity against non-transformed cells. Numerous epidemiological studies have shown that the intake of lignans is associated with lower risk of several cancers. These natural compounds have the potential to inhibit carcinogenesis, tumor growth, and metastasis by targeting various signaling molecules and pathways. Growing evidence indicates that honokiol and magnolol as natural lignans possess potent anticancer activities against various types of human cancer. The aim of present review is to provide the reader with the newest findings in understanding the cellular and molecular mechanisms mediating anticancer effects of honokiol and magnolol. This review comprehensively elucidates the effects of honokiol and magnolol on the molecular targets and signal transduction pathways implicated in cancer cell proliferation and metastasis. The findings of current review indicate that honokiol and magnolol can be considered as promising carcinopreventive and anticancer agents.

A comprehensive mechanistic insight into the dietary and estrogenic lignans, arctigenin and sesamin as potential anticarcinogenic and anticancer agents. Current status, challenges, and future perspectives

A large body of evidence indicates that lignans as polyphenolic compounds are beneficial against life-threatening diseases such as cancer. Plant lignans have the potential to induce cancer cell death and interfere with carcinogenesis, tumor growth, and metastasis. Epidemiological studies have revealed that the intake of lignans is inversely associated with the risk of several cancers. Moreover, numerous experimental studies demonstrate that natural lignans significantly suppress cancer cell proliferation with minimal toxicity against non-transformed cells. Dietary lignans arctigenin and sesamin have been found to have potent antiproliferative activities against various types of human cancer. The purpose of this review is to provide the reader with a deeper understanding of the cellular and molecular mechanisms underlying anticancer effects of arctigenin and sesamin. Our review comprehensively describes the effects of arctigenin and sesamin on the signaling pathways and related molecules involved in cancer cell proliferation and invasion. The findings of present review show that the dietary lignans arctigenin and sesamin seem to be promising carcinopreventive and anticancer agents. These natural lignans can be used as dietary supplements and pharmaceuticals for prevention and treatment of cancer.

Hegazy ME, Naqishbandi AM, Efferth T. Induction of Apoptosis, Autophagy and Ferroptosis by Thymus vulgaris and Arctium lappa Extract in Leukemia and Multiple Myeloma Cell Lines

Thymus vulgaris and Arctium lappa have been used as a folk remedy in the Iraqi Kurdistan region to deal with different health problems. The aim of the current study is to investigate the cytotoxicity of T. vulgaris and A. lappa in leukemia and multiple myeloma (MM) cell lines and determine the mode of cell death triggered by the most potent cytotoxic fractions of both plants in MM. Resazurin assay was used to evaluate cytotoxic and ferroptosis activity, apoptosis, and modulation in the cell cycle phase were investigated via Annexin V-FITC/PI dual stain and cell-cycle arrest assays. Furthermore, we used western blotting assay for the determination of autophagy cell death. n-Hexane, chloroform, ethyl acetate, and butanol fractions of T. vulgaris and A. lappa exhibited cytotoxicity in CCRF-CEM and CEM/ADR 5000 cell lines at concentration range 0.001–100 μg/mL with potential activity revealed by chloroform and ethyl acetate fractions. NCI-H929 displayed pronounced sensitivity towards T. vulgaris (TCF) and A. lappa (ACF) chloroform fractions with IC₅₀ values of 6.49 ± 1.48 and 21.9 ± 0.69 μg/mL, respectively. TCF induced apoptosis in NCI-H929 cells with a higher ratio (71%), compared to ACF (50%) at 4 × IC₅₀. ACF demonstrated more potent autophagy activity than TCF. TCF and ACF induced cell cycle arrest and ferroptosis. Apigenin and nobiletin were identified in TCF, while nobiletin, ursolic acid, and lupeol were the main compounds identified in ACF. T. vulgaris and A. lappa could be considered as potential herbal drug candidates, which arrest cancer cell proliferation by induction of apoptosis, autophagic, and ferroptosis.

Association between Polyphenol Intake and Gastric Cancer Risk by Anatomic and Histologic Subtypes: MCC-Spain

Several anticancer properties have been largely attributed to phenolics in in vivo and in vitro studies, but epidemiologic evidence is still scarce. Furthermore, some classes have not been studied in relation to gastric cancer (GC). The aim of this study was to assess the relationship between the intake of phenolic acids, stilbenes, and other phenolics and the risk of developing GC and its anatomical and histological subtypes. We used data from a multi-case-control study (MCC-Spain) obtained from different regions of Spain. We included 2700 controls and 329 GC cases. Odds ratios (ORs) were calculated using mixed effects logistic regression considering quartiles of phenolic intake. Our results showed an inverse association between stilbene and lignan intake and GC risk (OR_{Q4 vs. Q1} = 0.47; 95% CI: 0.32–0.69 and OR_{Q4 vs. Q1} = 0.53; 95% CI: 0.36–0.77, respectively). We found no overall association between total phenolic acid and other polyphenol class intake and GC risk. However, hydroxybenzaldehydes (OR_{Q4 vs. Q1} = 0.41; 95% CI: 0.28–0.61), hydroxycoumarins (OR_{Q4 vs. Q1} = 0.49; 95% CI: 0.34–0.71), and tyrosols (OR_{Q4 vs. Q1} = 0.56; 95% CI: 0.39–0.80) were inversely associated with GC risk. No differences were found in the analysis by anatomical or histological subtypes. In conclusion, a diet high in stilbenes, lignans, hydroxybenzaldehydes, hydroxycoumarins, and tyrosols was associated with a lower GC risk. Further prospective studies are needed to confirm our results.

Arctigenin inhibits proliferation of ER-positive breast cancer cells through cell cycle arrest mediated by GSK3-dependent cyclin D1 degradation

Estrogen receptor (ER) positive accounts for a large proportion of breast cancer. Although there are many targeted therapeutic drugs, the emergence of drug resistance urgently requires the development of new drugs. Arctigenin (Arc), a lignan found in certain plants of the Asteraceae, has the effect on inhibiting breast cancer, but its molecular mechanism has not been clear.

AIMS

To this end, the current study focuses on understanding the mechanism of Arc on ER-positive breast cancer cells.

MAIN METHODS

Colony formation experiments and sulforhodamine B methods were used to determine the growth-inhibitory effect of Arc. The cell cycle and apoptosis were analyzed by flow cytometry. Alterations of signaling proteins were measured by Western blotting. Protein degradation was determined by comparing protein half-lives and inhibiting proteasome.

KEY FINDINGS

The experimental results show that Arc did not induce apoptosis in ER-positive breast cancer cell, rather caused G1 cycle arrest by decreasing cyclin D1 levels without effect on altering CDK4/6 levels. Moreover, we have demonstrated that Arc decreases cyclin D1 levels through prompting Akt/GSK3β-mediated degradation.

SIGNIFICANCE

These findings warrant the potential of Arc as a candidate treatment for ER-positive breast cancer.

Arctigenin Enhances the Cytotoxic Effect of Doxorubicin in MDA-MB-231 Breast Cancer Cells

Several reports have described the anti-cancer activity of arctigenin, a lignan extracted from Arctium lappa L. Here, we investigated the effect of arctigenin (ATG) on doxorubicin (DOX)-induced cell death using MDA-MB-231 human breast cancer cells. The results showed that DOX-induced cell death was enhanced by ATG/DOX co-treatment in a concentration-dependent manner and that this was associated with increased DOX uptake and the suppression of multidrug resistance-associated protein 1 (MRP1) gene expression in MDA-MB-231 cells. ATG enhanced DOX-induced DNA damage and decreased the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the expressions of RAD51 and survivin. Cell death caused by ATG/DOX co-treatment was mediated by the nuclear translocation of apoptosis inducing factor (AIF), reductions in cellular and mitochondrial Bcl-2 and Bcl-xL, and increases in mitochondrial BAX levels. However, caspase-3 and -7 did not participate in DOX/ATG-induced cell death. We also found that DOX/ATG-induced cell death was linked with activation of the p38 signaling pathway and suppressions of the phosphorylations and expressions of Akt and c-Jun N-terminal kinase. Taken together, these results show that ATG enhances the cytotoxic activity of DOX in MDA-MB-231 human breast cancer cells by inducing prolonged p21 expression and p38-mediated AIF-dependent cell death. In conclusion, our findings suggest that ATG might alleviate the side effects and improve the therapeutic efficacy of DOX.

Activation of reactive oxygen species-mediated mitogen-activated protein kinases pathway regulates both extrinsic and intrinsic apoptosis induced by arctigenin in Hep G2

OBJECTIVES

Arctigenin (ARG) has been proved to inhibit the viability of hepatocellular carcinoma (HCC) via inducing apoptosis. However, the precise mechanism remains unknown. The present study was aimed to further investigate the mechanism of ARG against HCC in vitro and in vivo.

METHODS

Arctigenin was applied in vitro and in vivo. Western blotting, immunohistochemistry, etc., were used to investigate the mechanisms.

KEY FINDINGS

The time-dependent enhancement of Bax/Bcl-2 ratio, cytochrome c release, Fas and FasL levels, caspase cascade activation and the loss in the mitochondrial out membrane potential indicated that both intrinsic and extrinsic apoptotic pathways were triggered by ARG. Moreover, Jun NH2-terminal kinase (JNK) and p38 phosphorylated time-dependently. And inhibition of the phosphorylation of either p38 or JNK led to a significant reduction in HepG2 apoptosis, owing to the crucial roles of p38 and JNK played in regulating the apoptosis pathways. In addition, ARG increased the generation of reactive oxygen species (ROS) in HepG2 cells, while the antioxidant N-acetyl cysteine almost reversed ARG-induced JNK and p38 activation, and dramatically decreased cell apoptosis. In vivo, ARG increased the cell apoptosis in tumour tissues, and p-p38, p-JNK and Bax were significantly upregulated.

CONCLUSIONS

Our findings demonstrated that ARG induced apoptosis in HCC via ROS-mediated mitogen-activated protein kinases apoptosis pathway.

3'-Desmethylarctigenin induces G2/M cell cycle arrest and apoptosis through reactive oxygen species generation in hepatocarcinoma cells

Previous studies have shown that arctigenin is a promising chemopreventive or therapeutic agent against various cancers. However, less is known about anticancer activity of 3'-desmethylarctigenin (3'-DMAG), which is a biotransformed product from arctigenin or arctin. In this study, we compared the anticancer activity of 3'-DMAG with its parent compound arctigenin and demonstrated that 3'-DMAG exerted a more potent inhibitory effect on HepG2 cells than arctigenin. Mechanistically, reactive oxygen species generation played an apical role in 3'-DMAG-induced G2/M cell cycle arrest and apoptosis in HepG2 cells. Furthermore, the Chk2-Cdc25c-Cdc2-cyclin B1 cascade was found to contribute to the cell cycle arrest, whereas the activation of mitochondrial pathway was involved in the cell apoptosis by 3'-DMAG. Additionally, a mouse xenograft hepatocellular carcinoma model was used to evaluate the antitumor effect of 3'-DMAG in vivo, and the results indicated that 3'-DMAG treatment significantly inhibited tumor growth without apparent toxicity. Taken together, 3'-DMAG is highly effective against liver cancer both in vitro and in vivo. The findings of the present study suggest that this compound deserves to be further investigated for its potential anticancer activity.

Molecular mechanisms of the action of Arctigenin in cancer

Since antediluvian times, the scientific community has realized that natural compounds exhibit enormous potential for the treatment of terrible diseases, such as cancer. Despite a variety of effective bioactive molecules, effective therapies still need to be developed to treat cancer. Hence, it is necessary to study the interactions of natural molecules with their cellular targets. Arctigenin (ATG), a natural lignan compound extracted from Arctium lappa, inhibits the growth of various cancer cells, such as those of the stomach, lungs, liver, and colon, as well as leukocytes, and regulates numerous intracellular activities, such as antioxidative, anti-inflammatory, and anticancer activities. The intention of this paper is to summarize and generally analyse the molecular pathways that are involved in the anticancer effects of ATG. In addition, the interactions of ATG with other drugs are also highlighted in this paper.

Arctigenin Inhibits Liver Cancer Tumorigenesis by Inhibiting Gankyrin Expression via C/EBPα and PPARα

Burdock (Arctium lappa) is a popular vegetable in China and Japan that is consumed for its general health benefits. The principal active component of burdock is arctigenin, which shows a range of bioactivities in vivo and in vitro. Here, we investigated the potential anti-tumor effects of arctigenin using two human hepatocellular carcinoma (HCC) cell lines, HepG2 and Hep3B, and sought to elucidate its potential mechanisms of action. Our results showed that arctigenin treatment inhibited cell growth in both HepG2 and Hep3B cell lines (IC₅₀ of 4.74 nM for HepG2 cells, and of 59.27 nM for Hep3B cells). In addition, migration, invasion, and colony formation by HepG2 cells were significantly inhibited by arctigenin. By contrast, treatment of Hep3B cells with arctigenin did not alter these parameters. Arctigenin also significantly reduced the levels of gankyrin mRNA and protein in HepG2 cells, but not in Hep3B cells. A luciferase assay indicated that arctigenin targeted the -450 to -400 region of the gankyrin promoter. This region is also the potential binding site for both C/EBPα and PPARα, as predicted and confirmed by an online software analysis and ChIP assay. Additionally, a co-immunoprecipitation (Co-IP) assay showed that binding between C/EBPα and PPARα was increased in the presence of arctigenin. However, arctigenin did not increase the expression of C/EBPα or PPARα protein. A binding screening assay and liquid chromatography-mass spectrometry (LC-MS) were performed to identify the mechanisms by which arctigenin regulates gankyrin expression. The results suggested that arctigenin could directly increase C/EBPα binding to the gankyrin promoter (-432 to -422 region), but did not affect PPARα binding. Expression of gankyrin, C/EBPα, and PPARα were analyzed in tumor tissues of patients using real-time PCR. Both C/EBPα and PPARα showed negative correlations with gankyrin. In tumor-bearing mice, arctigenin had a significant inhibitory effect on HCC growth. In conclusion, our results suggested that arctigenin could inhibit liver cancer growth by directly recruiting C/EBPα to the gankyrin promoter. PPARα subsequently bound to C/EBPα, and both had a negative regulatory effect on gankyrin expression. This study has identified a new mechanism of action of arctigenin against liver cancer growth.

Arctigenin inhibits the activation of the mTOR pathway, resulting in autophagic cell death and decreased ER expression in ER-positive human breast cancer cells

Arctigenin, a member of the Asteraceae family, is a biologically active lignan that is consumed worldwide due to its several health benefits. However, its use may pose a problem for patients with estrogen receptor (ER)α-positive breast cancer, since studies have shown that arctigenin is a phytoestrogen that exerts a proliferative effect by binding to the ER. Thus, in this study, we examined the effect of arctigenin on ERα-positive MCF-7 human breast cancer cells to determine whether the consumption of arctigenin is safe for patients with breast cancer. First, we found that arctigenin inhibited the viability of the MCF-7 cells, and colony formation assay confirmed that this effect was cytotoxic rather than cytostatic. The cytotoxic effects were not mediated by cell cycle arrest, apoptosis, or necroptosis, despite DNA damage, as indicated by poly(ADP-ribose) polymerase (PARP) cleavage and phosphorylated H2A.X. An increase in lipidated LC3, a marker of autophagosome formation, was observed, indicating that autophagy was induced by arctigenin, which was found to be triggered by the inhibition of the mechanistic target of rapamycin (mTOR) pathway. We then examined the effects of arctigenin on ERα expression and determined whether it affects the sensitivity of the cells to tamoxifen, as tamoxifen is commonly used against hormone-responsive cancers and is known to act via the ERα. We found that treatment with arctigenin effectively downregulated ERα expression, which was found to be a consequence of the inhibition of the mTOR pathway. However, treatment with arctigenin in combination with tamoxifen did not affect the sensitivity of the cells to tamoxifen, but instead, exerted a synergistic effect. On the whole, our data indicate that the phytoestrogen, arctigenin, mainly targeted the mTOR pathway in ERα-positive MCF-7 human breast cancer cells, leading to autophagy-induced cell death and the downregulation of ERα expression. Furthermore, the synergistic effects between arctigenin and tamoxifen suggest that the consumption of arctigenin is not only safe for patients with hormone-sensitive cancers, but may also be an effective co-treatment.

Arctigenin represses TGF-β-induced epithelial mesenchymal transition in human lung cancer cells

Arctigenin (ARC) is a lignan that is abundant in Asteraceae plants, which show anti-inflammatory and anti-cancer activities. The current study investigated whether ARC affects cancer progression and metastasis, focusing on EMT using invasive human non-small cell lung cancer (NSCLC) cells. No toxicity was observed in the cells treated with different doses of ARC (12-100 μM). The treatment of ARC repressed TGF-β-stimulated changes of metastatic morphology and cell invasion and migration. ARC inhibited TGF-β-induced phosphorylation and transcriptional activity of smad2/3, and expression of snail. ARC also decreased expression of N-cadherin and increased expression of E-cadherin in dose-dependent and time-dependent manners. These changes were accompanied by decreased amount of phospho-smad2/3 in nucleus and nuclear translocation of smad2/3. Moreover, ARC repressed TGF-β-induced phosphorylation of ERK and transcriptional activity of β-catenin. Our data demonstrate anti-metastatic activity of ARC in lung cancer model.

Arctigenin induced gallbladder cancer senescence through modulating epidermal growth factor receptor pathway

Gallbladder cancer has poor prognosis and limited therapeutic options. Arctigenin, a representative dibenzylbutyrolactone lignan, occurs in a variety of plants. However, the molecular mechanisms involved in the antitumor effect of arctigenin on gallbladder cancer have not been fully elucidated. The expression levels of epidermal growth factor receptor were examined in 100 matched pairs of gallbladder cancer tissues. A positive correlation between high epidermal growth factor receptor expression levels and poor prognosis was observed in gallbladder cancer tissues. Pharmacological inhibition or inhibition via RNA interference of epidermal growth factor receptor induced cellular senescence in gallbladder cancer cells. The antitumor effect of arctigenin on gallbladder cancer cells was primarily achieved by inducing cellular senescence. In gallbladder cancer cells treated with arctigenin, the expression level of epidermal growth factor receptor significantly decreased. The analysis of the activity of the kinases downstream of epidermal growth factor receptor revealed that the RAF-MEK-ERK signaling pathway was significantly inhibited. Furthermore, the cellular senescence induced by arctigenin could be reverted by pcDNA-epidermal growth factor receptor. Arctigenin also potently inhibited the growth of tumor xenografts, which was accompanied by the downregulation of epidermal growth factor receptor and induction of senescence. This study demonstrates arctigenin could induce cellular senescence in gallbladder cancer through the modulation of epidermal growth factor receptor pathway. These data identify epidermal growth factor receptor as a key regulator in arctigenin-induced gallbladder cancer senescence.

β-Catenin Mediates Anti-adipogenic and Anticancer Effects of Arctigenin in Preadipocytes and Breast Cancer Cells

Arctigenin is a lignan abundant in Asteraceae plants and has anti-inflammatory, antiobesity, and anticancer activities. Obesity is one of the leading causes of several types of cancers including breast cancer. The current study was performed to investigate if arctigenin suppresses differentiation of preadipocytes and proliferation of breast cancer cells and to explore potential molecular mechanisms. Treatment of arctigenin reduced lipid accumulation in differentiated 3T3-L1 adipocytes in a dose- and time-dependent manner without toxicity. Arctigenin suppressed the expression of peroxisome proliferator-activated receptor-gamma (PPARγ), CCAAT/enhancer-binding protein-alpha (C/EBPα), perilipin, and fatty acid binding protein 4 (FABP4) in a dose-dependent manner in differentiated 3T3-L1 cells. Both total and unphosphorylated (active) β-catenin were increased in whole cell lysates and the nuclear fraction of differentiated 3T3-L1 cells treated with 25 μM arctigenin. On the other hand, arctigenin decreased proliferation of two human breast cancer cells (MCF-7 and MDA-MB-231). Arctigenin induced apoptosis and decreased expression of total and unphosphorylated (active) β-catenin and cyclin D1 in MCF-7, but not in MDA-MB-231. These data indicate that arctigenin suppressed adipogenesis in preadipocytes and activated apoptosis in estrogen receptor (ER) positive breast cancer cells through modulating expression of β-catenin.

Arctigenin, a natural lignan compound, induces G0/G1 cell cycle arrest and apoptosis in human glioma cells

The aim of the current study was to investigate the anticancer potential of arctigenin, a natural lignan compound, in malignant gliomas. The U87MG and T98G human glioma cell lines were treated with various concentrations of arctigenin for 48 h and the effects of arctigenin on the aggressive phenotypes of glioma cells were assessed. The results demonstrated that arctigenin dose-dependently inhibited the growth of U87MG and T98G cells, as determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and bromodeoxyuridine incorporation assays. Arctigenin exposure also induced a 60-75% reduction in colony formation compared with vehicle-treated control cells. However, arctigenin was not observed to affect the invasiveness of glioma cells. Arctigenin significantly increased the proportion of cells in the G0/G1 phase and reduced the number of cells in the S phase, as compared with the control group (P<0.05). Western blot analysis demonstrated that arctigenin increased the expression levels of p21, retinoblastoma and p53 proteins, and significantly decreased the expression levels of cyclin D1 and cyclin-dependent kinase 4 proteins. Additionally, arctigenin was able to induce apoptosis in glioma cells, coupled with increased expression levels of cleaved caspase-3 and the pro-apoptotic BCL2-associated X protein. Furthermore, arctigenin-induced apoptosis was significantly suppressed by the pretreatment of cells with Z-DEVD-FMK, a caspase-3 inhibitor. In conclusion, the results suggest that arctigenin is able to inhibit cell proliferation and may induce apoptosis and cell cycle arrest at the G0/G1 phase in glioma cells. These results warrant further investigation of the anticancer effects of arctigenin in animal models of gliomas.

The Novel miR-9600 Suppresses Tumor Progression and Promotes Paclitaxel Sensitivity in Non-small-cell Lung Cancer Through Altering STAT3 Expression

MicroRNAs have been identified to be involved in center stage of cancer biology. They accommodate cell proliferation and migration by negatively regulate gene expression either by hampering the translation of targeted mRNAs or by promoting their degradation. We characterized and identified the novel miR-9600 and its target in human non-small-cell lung cancer (NSCLC). Our results demonstrated that the miR-9600 were downregulated in NSCLC tissues and cells. It is confirmed that signal transducer and activator of transcription 3 (STAT3), a putative target gene, is directly inhibited by miR-9600. The miR-9600 markedly suppressed the protein expression of STAT3, but with no significant influence in corresponding mRNA levels, and the direct combination of miR-9600 and STAT3 was confirmed by a luciferase reporter assay. miR-9600 inhibited cell growth, hampered expression of cell cycle-related proteins and inhibited cell migration and invasion in human NSCLC cell lines. Further, miR-9600 significantly suppressed tumor growth in nude mice. Similarly, miR-9600 impeded tumorigenesis and metastasis through directly targeting STAT3. Furthermore, we identified that miR-9600 augmented paclitaxel and cisplatin sensitivity by downregulating STAT3 and promoting chemotherapy-induced apoptosis. These data demonstrate that miR-9600 might be a useful and novel therapeutic target for NSCLC.

Hypoxia-induced autophagy mediates cisplatin resistance in lung cancer cells

Hypoxia which commonly exists in solid tumors, leads to cancer cells chemoresistance via provoking adaptive responses including autophagy. Therefore, we sought to evaluate the role of autophagy and hypoxia as well as the underlying mechanism in the cisplatin resistance of lung cancer cells. Our study demonstrated that hypoxia significantly protected A549 and SPC-A1 cells from cisplatin-induced cell death in a Hif-1α- and Hif-2α- dependent manner. Moreover, compared with normoxia, cisplatin-induced apoptosis under hypoxia was markedly reduced. However, when autophagy was inhibited by 3-MA or siRNA targeted ATG5, this reduction was effectively attenuated, which means autophagy mediates cisplatin resisitance under hypoxia. In parallel, we showed that hypoxia robustly augmented cisplatin-induced autophagy activation, accompanying by suppressing cisplatin-induced BNIP3 death pathways, which was due to the more efficient autophagic process under hypoxia. Consequently, we proposed that autophagy was a protective mechanism after cisplatin incubation under both normoxia and hypoxia. However, under normoxia, autophagy activation ‘was unable to counteract the stress induced by cisplatin, therefore resulting in cell death, whereas under hypoxia, autophagy induction was augmented that solved the cisplatin-induced stress, allowing the cells to survival. In conclusion, augmented induction of autophagy by hypoxia decreased lung cancer cells susceptibility to cisplatin-induced apoptosis.

Mechanism of Arctigenin-Induced Specific Cytotoxicity against Human Hepatocellular Carcinoma Cell Lines: Hep G2 and SMMC7721

Arctigenin (ARG) has been previously reported to exert high biological activities including anti-inflammatory, antiviral and anticancer. In this study, the anti-tumor mechanism of ARG towards human hepatocellular carcinoma (HCC) was firstly investigated. We demonstrated that ARG could induce apoptosis in Hep G2 and SMMC7721 cells but not in normal hepatic cells, and its apoptotic effect on Hep G2 was stronger than that on SMMC7721. Furthermore, the following study showed that ARG treatment led to a loss in the mitochondrial out membrane potential, up-regulation of Bax, down-regulation of Bcl-2, a release of cytochrome c, caspase-9 and caspase-3 activation and a cleavage of poly (ADP-ribose) polymerase in both Hep G2 and SMMC7721 cells, suggesting ARG-induced apoptosis was associated with the mitochondria mediated pathway. Moreover, the activation of caspase-8 and the increased expression levels of Fas/FasL and TNF-α revealed that the Fas/FasL-related pathway was also involved in this process. Additionally, ARG induced apoptosis was accompanied by a deactivation of PI3K/p-Akt pathway, an accumulation of p53 protein and an inhibition of NF-κB nuclear translocation especially in Hep G2 cells, which might be the reason that Hep G2 was more sensitive than SMMC7721 cells to ARG treatment.

Arctigenin promotes apoptosis in ovarian cancer cells via the iNOS/NO/STAT3/survivin signalling

Arctigenin is a biologically active lignan extracted from the seeds of Arctium lappa and shows anticancer activity against a variety of human cancers. The aim of this study was to determine the effects of arctigenin on ovarian cancer cell proliferation and survival and associated molecular mechanisms. Human ovarian cancer OVCAR3 and SKOV3 cells were treated with arctigenin, and cell proliferation and apoptosis were assessed. Western blot analysis was used to examine signal transducer and activator of transcription-3 (STAT3) phosphorylation and survivin and inducible nitric oxide synthase (iNOS) expression. The involvement of STAT3/survivin/iNOS/NO signalling in arctigenin action was checked. Arctigenin treatment resulted in a significant and dose-dependent inhibition of cell proliferation. Arctigenin-treated cells showed a 4-6 times increase in the percentage of apoptosis, compared with control cells. Pre-treatment with Ac-DEVD-CHO, a specific inhibitor of caspase-3, counteracted the induction of apoptosis by arctigenin. Arctigenin treatment significantly inhibited STAT3 phosphorylation and survivin and iNOS expression. Arctigenin-induced apoptosis was impaired by pre-transfection with survivin-expressing plasmid or addition of chemical nitric oxide (NO) donors. Additionally, exogenous NO prevented the suppression of STAT3 phosphorylation and survivin expression by arctigenin. Arctigenin treatment inhibits the proliferation and induces caspase-3-dependent apoptosis of ovarian cancer cells. Suppression of iNOS/NO/STAT3/survivin signalling is causally linked to the anticancer activity of arctigenin. Therefore, arctigenin may be applicable to anticancer therapy for ovarian cancer.

The novel miR-9500 regulates the proliferation and migration of human lung cancer cells by targeting Akt1

MicroRNAs have crucial roles in lung cancer cell development. They regulate cell growth, proliferation and migration by mediating the expression of tumor suppressor genes and oncogenes. We identified and characterized the novel miR-9500 in human lung cancer cells. The miR-9500 forms a stem-loop structure and is conserved in other mammals. The expression levels of miR-9500 were reduced in lung cancer cells and lung cancer tissues compared with normal tissues, as verified by TaqMan miRNA assays. It was confirmed that the putative target gene, Akt1, was directly suppressed by miR-9500, as demonstrated by a luciferase reporter assay. The miR-9500 significantly repressed the protein expression levels of Akt1, as demonstrated via western blot, but did not affect the corresponding mRNA levels. Akt1 has an important role in lung carcinogenesis, and depletion of Akt1 has been shown to have antiproliferative and anti-migratory effects in previous studies. In the current study, the overexpression of miR-9500 inhibited cell proliferation and the expression of cell cycle-related proteins. Likewise, the overexpression of miR-9500 impeded cell migration in human lung cancer cells. In an in vivo assay, miR-9500 significantly suppressed Fluc expression compared with NC and ASO-miR-9500, suggesting that cell proliferation was inhibited in nude mice. Likewise, miR-9500 repressed tumorigenesis and metastasis by targeting Akt1. These data indicate that miR-9500 might be applicable for lung cancer therapy.

Arctigenin, a dietary phytoestrogen, induces apoptosis of estrogen receptor-negative breast cancer cells through the ROS/p38 MAPK pathway and epigenetic regulation

This study investigates the anticancer effect of arctigenin (ATG), a natural lignan product of Arctium lappa L., in human breast cancer MDA-MB-231 cells. Results indicate that ATG inhibits MDA-MB-231 cell growth by inducing apoptosis in vitro and in vivo. ATG triggers the mitochondrial caspase-independent pathways, as indicated by changes in Bax/Bcl-2 ratio, resulting in AIF and EndoG nuclear translocation. ATG increased cellular reactive oxygen species (ROS) production by increasing p22(phox)/NADPH oxidase 1 interaction and decreasing glutathione level. ATG clearly increases the activation of p38 MAPK, but not JNK and ERK1/2. Antioxidant EUK-8, a synthetic catalytic superoxide and hydrogen peroxide scavenger, significantly decreases ATG-mediated p38 activation and apoptosis. Blocking p38 with a specific inhibitor suppresses ATG-mediated Bcl-2 downregulation and apoptosis. Moreover, ATG activates ATF-2, a transcription factor activated by p38, and then upregulates histone H3K9 trimethylation in the Bcl-2 gene promoter region, resulting in Bcl-2 downregulation. Taken together, the results demonstrate that ATG induces apoptosis of MDA-MB-231 cells via the ROS/p38 MAPK pathway and epigenetic regulation of Bcl-2 by upregulation of histone H3K9 trimethylation.

Arctigenin inhibits osteoclast differentiation and function by suppressing both calcineurin-dependent and osteoblastic cell-dependent NFATc1 pathways

Arctigenin, a lignan-derived compound, is a constituent of the seeds of Arctium lappa. Arctigenin was previously shown to inhibit osteoclastogenesis; however, this inhibitory mechanism has yet to be elucidated. Here, we showed that arctigenin inhibited the action of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), a key transcription factor for osteoclastogenesis. NFATc1 in osteoclast precursors was activated through two distinct pathways: the calcineurin-dependent and osteoblastic cell-dependent pathways. Among the several lignan-derived compounds examined, arctigenin most strongly inhibited receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast-like cell formation in mouse bone marrow macrophage (BMM) cultures, in which the calcineurin-dependent NFATc1 pathway was activated. Arctigenin suppressed neither the activation of nuclear factor κB and mitogen-activated protein kinases nor the up-regulation of c-Fos expression in BMMs treated with RANKL. However, arctigenin suppressed RANKL-induced NFATc1 expression. Interestingly, the treatment of osteoclast-like cells with arctigenin converted NFATc1 into a lower molecular weight species, which was translocated into the nucleus even in the absence of RANKL. Nevertheless, arctigenin as well as cyclosporin A (CsA), a calcineurin inhibitor, suppressed the NFAT-luciferase reporter activity induced by ionomycin and phorbol 12-myristate 13-acetate in BMMs. Chromatin immunoprecipitation analysis confirmed that arctigenin inhibited the recruitment of NFATc1 to the promoter region of the NFATc1 target gene. Arctigenin, but not CsA suppressed osteoclast-like cell formation in co-cultures of osteoblastic cells and bone marrow cells, in which the osteoblastic cell-dependent NFATc1 pathway was activated. The forced expression of constitutively active NFATc1 rescued osteoclastogenesis in BMM cultures treated with CsA, but not that treated with arctigenin. Arctigenin also suppressed the pit-forming activity of osteoclast-like cells cultured on dentin slices. These results suggest that arctigenin induces a dominant negative species of NFATc1, which inhibits osteoclast differentiation and function by suppressing both calcineurin-dependent and osteoblastic cell-dependent NFATc1 pathways.

Mechanism of arctigenin-mediated specific cytotoxicity against human lung adenocarcinoma cell lines

The lignan arctigenin (ARG) from the herb Arctium lappa L. possesses anti-cancer activity, however the mechanism of action of ARG has been found to vary among tissues and types of cancer cells. The current study aims to gain insight into the ARG mediated mechanism of action involved in inhibiting proliferation and inducing apoptosis in lung adenocarcinoma cells. This study also delineates the cancer cell specificity of ARG by comparison with its effects on various normal cell lines. ARG selectively arrested the proliferation of cancer cells at the G0/G1 phase through the down-regulation of NPAT protein expression. This down-regulation occurred via the suppression of either cyclin E/CDK2 or cyclin H/CDK7, while apoptosis was induced through the modulation of the Akt-1-related signaling pathway. Furthermore, a GSH synthase inhibitor specifically enhanced the cytotoxicity of ARG against cancer cells, suggesting that the intracellular GSH content was another factor influencing the susceptibility of cancer cells to ARG. These findings suggest that specific cytotoxicity of ARG against lung cancer cells was explained by its selective modulation of the expression of NPAT, which is involved in histone biosynthesis. The cytotoxicity of ARG appeared to be dependent on the intracellular GSH level.

Arctigenin enhances chemosensitivity to cisplatin in human nonsmall lung cancer H460 cells through downregulation of survivin expression

Arctigenin, a dibenzylbutyrolactone lignan, enhances cisplatin-mediated cell apoptosis in cancer cells. Here, we sought to investigate the effects of arctigenin on cisplatin-treated non-small-cell lung cancer (NSCLC) H460 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and annexin-V/propidium iodide staining were performed to analyze the proliferation and apoptosis of H460 cells. Arctigenin dose-dependently suppressed cell proliferation and potentiated cell apoptosis, coupled with increased cleavage of caspase-3 and poly(ADP-ribose) polymerase. Moreover, arctigenin sensitized H460 cells to cisplatin-induced proliferation inhibition and apoptosis. Arctigenin alone or in combination with cisplatin had a significantly lower amount of survivin. Ectopic expression of survivin decreased cell apoptosis induced by arctigenin (P < 0.05) or in combination with cisplatin (P < 0.01). Moreover, arctigenin (P < 0.05) or in combination with cisplatin (P < 0.01) induced G1/G0 cell-cycle arrest. Our data provide evidence that arctigenin has a therapeutic potential in combina-tion with chemotherapeutic agents for NSLC.

Synthesis and biological evaluation of arctigenin ester and ether derivatives as activators of AMPK

A series of new arctigenin and 9-deoxy-arctigenin derivatives bearing different ester and ether side chains at the phenolic hydroxyl positions are designed, synthesized, and evaluated for activating AMPK potency in L6 myoblasts. Initial biological evaluation indicates that some alkyl ester and phenethyl ether arctigenin derivatives display potential activities in AMPK phosphorylation improvement. Further structure-activity relationship analysis shows that arctigenin ester derivatives 3a, 3h and 9-deoxy-arctigenin phenethyl ether derivatives 6a, 6c, 6d activate AMPK more potently than arctigenin. Moreover, the 2-(3,4-dimethoxyphenyl)ethyl ether moiety of 6c has been demonstrated as a potential functional group to improve the effect of AMPK phosphorylation. The structural optimization of arctigenin leads to the identification of 6c as a promising lead compound that exhibits excellent activity in AMPK activation.

Tumor specific cytotoxicity of arctigenin isolated from herbal plant Arctium lappa L

The effectiveness of cancer chemotherapy is often limited by the toxicity to other tissues in the body. Therefore, the identification of non-toxic chemotherapeutics from herbal medicines remains to be an attractive goal to advance cancer treatments. This study evaluated the cytotoxicity profiles of 364 herbal plant extracts, using various cancer and normal cell lines. The screening found occurrence of A549 (human lung adenocarcinoma) specific cytotoxicity in nine species of herbal plants, especially in the extract of Arctium lappa L. Moreover, purification of the selective cytotoxicity in the extract of Arctium lappa L. resulted in the identification of arctigenin as tumor specific agent that showed cytotoxicity to lung cancer (A549), liver cancer (HepG2) and stomach cancer (KATO III) cells, while no cytotoxicity to several normal cell lines. Arctigenin specifically inhibited the proliferation of cancer cells, which might consequently lead to the induction of apoptosis. In conclusion, this study found that arctigenin was one of cancer specific phytochemicals, and in part responsible for the tumor selective cytotoxicity of the herbal medicine.