Arctigenin anti-tumor activity in bladder cancer T24 cell line through induction of cell-cycle arrest and apoptosis

Design, synthesis and activity evaluation of arctigenin derivatives with HDAC inhibition activity

Arctigenin, a natural product with diverse pharmacological activities, can inhibit cell proliferation and survival and has shown promising potential in cancer research. In this study, we designed a series of arctigenin derivatives with HDAC inhibitory activity based on the synergistic effects between HDAC inhibitors and arctigenin. Among them, compound B7 exhibited significantly higher antiproliferative activity in the MV411 cell line compared to the positive control, tucidinostat. Additionally, enzymatic activity testing was performed with compound B7. Further mechanistic studies indicated that compound B7 induced apoptosis through the Caspase-3 pathway in MV411 cells and enhanced histone acetylation levels in the MV411 cell line. These findings highlight the broad potential application of these arctigenin derivatives in cancer therapy.

Arctigenin Suppresses the Proliferation and Metastasis, and Induces Apoptosis and Cycle Arrest of Osteosarcoma Cells by inhibiting HMOX1 Expression

BACKGROUND

Osteosarcoma is the most common malignant bone tumor, with highly proliferative and metastatic properties. Previous studies have reported that arctigenin (Arc), a bioactive lignin compound, showed excellent anti-tumor activities in a variety of human cancers. However, its role in osteosarcoma has not been studied.

OBJECTIVE

We aimed to investigate the anti-tumor effects of Arc on osteosarcoma cell proliferation, migration, invasion, apoptosis, and cell cycle.

METHODS

Effects of Arc on osteosarcoma cell proliferation were detected by MTT and colony formation assay. Flow cytometry analysis was performed to assess the cell apoptosis and cycle arrest. Transwell assay was used to evaluate the capability of migration and invasion. qRT-PCR and Western blot were employed to determine the changes in mRNA and protein levels.

RESULTS

Arc could significantly suppress the proliferation, colony formation, and induce cell apoptosis and S phase cycle arrest of MG63 and U-2 OS cells in a dose-dependent manner. In addition, we also observed an inhibitory effect of Arc treatment on osteosarcoma cell invasion, migration, and epithelial-mesenchymal transition (EMT). HMOX1, encoding enzyme heme oxygenase-1, was predicted to be a candidate target of Arc using STITCH. Arc treatment significantly reduced the mRNA and protein levels of HMOX1. Furthermore, overexpression of HMOX1 could partly reverse the inhibitory effects of Arc on osteosarcoma cell malignant phenotypes.

CONCLUSION

Our results suggest that Arc inhibits the proliferation, metastasis and promotes cell apoptosis and cycle arrest of osteosarcoma cells by downregulating HMOX1 expression.

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.

Arctigenin induces caspase-dependent apoptosis in FaDu human pharyngeal carcinoma cells

The present study was carried out to investigate the effect of Arctigenin on cell growth and the mechanism of cell death elicited by Arctigenin were examined in FaDu human pharyngeal carcinoma cells. To determine the apoptotic activity of Arctigenin in FaDu human pharyngeal carcinoma cells, cell viability assay, DAPI staining, caspase activation analysis, and immunoblotting were performed. Arctigenin inhibited the growth of cells in a dose-dependent manner and induced nuclear condensation and fragmentation. Arctigenin-treated cells showed caspase-3/7 activation and increased apoptosis versus control cells. FasL, a death ligand associated with extrinsic apoptotic signaling pathways, was up-regulated by Arctigenin treatment. Moreover, caspase-8, a part of the extrinsic apoptotic pathway, was activated by Arctigenin treatments. Expressions of anti-apoptotic factors such as Bcl-2 and Bcl-xL, components of the mitochondria-dependent intrinsic apoptosis pathway, significantly decreased following Arctigenin treatment. The expressions of pro-apoptotic factors such as BAX, BAD and caspase-9, and tumor suppressor -53 increased by Arctigenin treatments. In addition, Arctigenin activated caspase-3 and poly (ADP-ribose) polymerase (PARP) induced cell death. Arctigenin also inhibited the proliferation of FaDu cells by the suppression of p38, NF-κB, and Akt signaling pathways. These results suggest that Arctigenin may inhibit cell proliferation and induce apoptotic cell death in FaDu human pharyngeal carcinoma cells through both the mitochondria-mediated intrinsic pathway and the death receptor-mediated extrinsic pathway.

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.

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.

Enhancement of the apoptotic effects of Arctii Fructus extracts on cancer cells by the enzymatic bioconversion of lignans

The fruit of Arctium lappa L. (Arctii Fructus) is one of the most popularly used medicinal plant components in Asia. To enhance the functionality of Arctii Fructus extract, a bioconversion method was developed to produce arctigenin from arctiin. Treatment with β-glucosidase increased the arctigenin content by >5 fold in Arctii Fructus extracts. The bioconversion products enhanced the apoptosis of cancer cells. The cell viabilities of gefitinib-resistant lung cancer HCC827 (HCC827GR) cells and colon cancer cells (DLD1) were decreased by 40% and 35%, respectively. The bioconversion products also decreased anchorage-independent growth of cancer cells. In addition, the increase of apoptosis in cancer cells by bioconversion was confirmed by the flow cytometry analysis. These results indicated that arctigenin exerts anticancer effects on lung and colon cancer cells and that Arctii Fructus can potentially function as a chemopreventive agent. In addition, bioconverted Arctii Fructus extract displayed higher anticancer activity than the same levels of purified arctigenin, indicating the advantage of consuming Arctii Fructus itself as a food or medicinal material.

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.

Arctigenin attenuates diabetic kidney disease through the activation of PP2A in podocytes

Arctigenin (ATG) is a major component of Fructus Arctii, a traditional herbal remedy that reduced proteinuria in diabetic patients. However, whether ATG specifically provides renoprotection in DKD is not known. Here we report that ATG administration is sufficient to attenuate proteinuria and podocyte injury in mouse models of diabetes. Transcriptomic analysis of diabetic mouse glomeruli showed that cell adhesion and inflammation are two key pathways affected by ATG treatment, and mass spectrometry analysis identified protein phosphatase 2 A (PP2A) as one of the top ATG-interacting proteins in renal cells. Enhanced PP2A activity by ATG reduces p65 NF-κB-mediated inflammatory response and high glucose-induced migration in cultured podocytes via interaction with Drebrin-1. Importantly, podocyte-specific Pp2a deletion in mice exacerbates DKD injury and abrogates the ATG-mediated renoprotection. Collectively, our results demonstrate a renoprotective mechanism of ATG via PP2A activation and establish PP2A as a potential target for DKD progression.

Antioxidant Capacity and Cytotoxic Effects of Catechins and Resveratrol Oligomers Produced by Enzymatic Oxidation against T24 Human Urinary Bladder Cancer Cells

In this work the polymerization of catechin, epicatechin, and resveratrol was carried out through a peroxidase oxidation process in order to improve the biological activity of these phenolic compounds. The antioxidant activity of the oligomers was evaluated by their ability to scavenge reactive oxygen species (ROS) and their capacity to chelate metal ions Fe2+ and Cu2+. The antitumor effect of the oligomers was determined by their ability to induce toxicity in the T24 human bladder cancer cell line. By enzymatic peroxidase oxidation, it was possible to produce oligomers of catechin, epicatechin, and resveratrol with antioxidant capacity significantly higher than their preceding monomers. The ROS scavenging capacity of the oligomers was 20 times higher than that of the monomers, while the ability of the oligomers to chelate metal ions increased up to about 1000 times. Our data show the antitumor effect of the oligomers of catechin, epicatechin, and resveratrol in the T24 cell line, which was similar to that observed with cisplatin. Oligomers of catechin, epicatechin, and resveratrol have great potential to be used as therapeutic agents for the treatment of oxidative stress-related diseases and bladder cancer.

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 protects against ultraviolet-A-induced damage to stemness through inhibition of the NF-κB/MAPK pathway

The stemness of stem cells is negatively affected by ultraviolet A (UVA) irradiation. This study was performed to examine the effects of arctigenin on UVA-irradiation-induced damage to the stemness of human mesenchymal stem cells (hMSCs) derived from adipose tissue. The mechanisms of action of arctigenin were also investigated. A BrdU-incorporation assay demonstrated that arctigenin attenuated the UVA-induced reduction of the cellular proliferative potential. Arctigenin also increased the UVA-induced reduction in stemness of hMSCs by upregulating stemness-related genes such as SOX2, OCT4, and NANOG. In addition, the UVA-induced reduction in the mRNA expression level of hypoxia-inducible factor (HIF)-1α was significantly recovered by arctigenin. The antagonizing effect of arctigenin on UVA irradiation was mediated by reduced PGE₂ production through the inhibition of MAPKs (p42/44 MAPK, p38 MAPK, and JNK) and NF-κB. Overall, these findings suggest that arctigenin can ameliorate the reduced stemness of hMSCs induced by UVA irradiation. The effects of arctigenin are mediated by PGE₂-cAMP signaling-dependent upregulation of HIF-1α. Therefore, arctigenin could be used as an antagonist to attenuate the effects of UVA irradiation.

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.

Dietary phytoestrogens, intestinal microflora and human health

With the growth of age, the amount of estrogens produced by the human body will get less and less. Studies have shown that estrogen deficiency may cause many kinds of diseases, such as cardiovascular diseases, osteoporosis, and syndrome of menopause. Estrogens are also distributed extensively in numerous types of plants. Since there is a trace amount of natural estrogen in plants, our body can achieve continuous phytoestrogen supplementation while our health will not be influenced or damaged by the absorbed phytoestrogens in diets. After being absorbed, the phytoestrogens in diets may be converted by intestinal microflora to different metabolites with higher estrogenic activity. This review summarizes the types and distributions of phytoestrogens in diets, their metabolism, metabolites and bioactivities, with an aim to provide some guidelines for further study and utilization of microbial biotransforming metabolites of phytoestrogens.

The effects of arctigenin on human rheumatoid arthritis fibroblast-like synoviocytes

CONTEXT

Rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs) play an important role in the initiation and progression of RA, which are resistant to apoptosis and proliferate in an anchorage-independent manner.

OBJECTIVE

The effects of arctigenin on the proliferation and apoptosis of RAFLSs were explored.

MATERIALS AND METHODS

Arctigenin (0-160 µM) was used to treat RAFLSs for 48 h. Cell viability and apoptosis were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay and annexin V/propidium iodide staining. Western blot analysis was performed to detect the changes in apoptosis-related genes.

RESULTS AND DISCUSSION

Arctigenin decreased cell viability by 23, 30, and 38% at the dose of 10, 20, and 30 µM, respectively. The half maximal inhibitory concentration (IC50) of arctignein on RAFLSs was about 38 µM. Moreover, 9, 15, and 21% of RAFLSs are induced apoptosis by 10, 20, and 30 µM of arctigenin. The apoptotic response was due to the loss of mitochondrial membrane potential, coupled with the release of cytochrome C into cytoplasm, the up-regulation of pro-apoptotic protein, Bax, and down-regulation of antiapoptotic protein, B cell lymphoma 2 (Bcl-2). The activation of mitochondrial pathway in arctigenin-treated RAFLSs induced the cleavage of caspase-9, caspase-3, and poly (ADP-ribose) polymerase (PARP). Additionally, arctigenin inhibited the nuclear translocation of p65, decreased the degradation of inhibitor of kappa B alpha (IκBα), and attenuated the phosphorylation of Akt.

CONCLUSION

Our results reveal that arctigenin inhibits cell proliferation and induces mitochondrial apoptosis of RAFLSs, which is associated with the modulation of NF-κB and Akt signaling pathways.

The novel herbal cocktail MA128 suppresses tumor growth and the metastatic potential of highly malignant tumor cells

MA128, a novel herbal medicine, was previously identified and its effectiveness in the treatment of asthma and atopic dermatitis (AD) was demonstrated. In particular, post-inflammatory hyperpigmentation (PIH) in AD mice was improved by treatment with MA128. In addition, MA128 exhibited anti-melanogenic activity by inhibiting tyrosinase activity via the p38 MAPK and protein kinase A signaling pathways in B16F10 cells. In the present study, we examined whether oral administration of MA128 suppressed the in vivo tumor growth of HT1080 cells in athymic nude mice. The results showed that the daily oral administration of 75 and 150 mg/kg MA128 suppressed the tumorigenic growth of HT1080 cells efficiently. Since metastasis is a major cause of cancer-associated mortality and the greatest challenge during cancer treatment, we investigated the effect of non-toxic concentrations of MA128 on the metastatic potential of HT1080 cells. MA128 inhibited anchorage-independent colony formation, migration and invasion. Matrix metalloproteinase-9 (MMP-9) activity under resting and PMA-stimulated conditions was decreased in a dose-dependent manner by MA128 in HT1080 cells. In addition, the daily oral administration of MA128 at doses of 75 and 150 mg/kg efficiently blocked the lung metastasis of B16F10 cells that had been injected into the tail veins of C57BL/6 mice. In particular, none of the mice treated with MA128 exhibited systemic toxicity, such as body weight loss or liver and kidney dysfunction. MA128 also inhibited tumor‑induced angiogenesis. Taken together, the results suggest that MA128 is a potential therapeutic agent and a safe herbal medicine for controlling malignant and metastatic cancer.

Inhibitory Effect of Arctigenin from Fructus Arctii Extract on Melanin Synthesis via Repression of Tyrosinase Expression

To identify the active compound arctigenin in Fructus Arctii (dried seed of medicinal plant Arctium lappa) and to elucidate the inhibitory mechanism in melanogenesis, we analyzed melanin content and tyrosinase activity on B16BL6 murine melanoma and melan-A cell cultures. Water extracts of Fructus Arctii were shown to inhibit tyrosinase activity in vitro and melanin content in α-melanocyte stimulating hormone-stimulated cells to similar levels as the well-known kojic acid and arbutin, respectively. The active compound arctigenin of Fructus Arctii displayed little or no cytotoxicity at all concentrations examined and decreased the relative melanin content and tyrosinase activity in a dose-dependent manner. Melanogenic inhibitory activity was also identified in vivo with zebrafish embryo. To determine the mechanism of inhibition, the effects of arctigenin on tyrosinase gene expression and tyrosinase promoter activity were examined. Also in addition, in the signaling cascade, arctigenin dose dependently decreased the cAMP level and promoted the phosphorylation of extracellular signal-regulated kinase. This result suggests that arctigenin downregulates cAMP and the tyrosinase enzyme through its gene promoter and subsequently upregulates extracellular signal-regulated kinase activity by increasing phosphorylation in the melanogenesis signaling pathway, which leads to a lower melanin content.