phytoestrogens and arctigenin

Intestinal mucus barrier dysfunction is closely involved in the pathogenesis of inflammatory bowel diseases (IBD). To investigate the protective effect and underlying mechanism of arctigenin, a phytoestrogen isolated from the fruits of Arctium lappa L., on the intestinal mucus barrier under colitis condition. The role of arctigenin on the intestinal mucus barrier and the apoptosis of goblet cells were examined by using both in vitro and in vivo assays. Arctigenin was demonstrated to promote the mucus secretion and maintain the integrity of mucus barrier, which might be achieved by an increase in the number of goblet cells via inhibiting apoptosis. Arctigenin selectively inhibited the mitochondrial pathway-mediated apoptosis. Moreover, arctigenin elevated the protein level of prohibitin 1 (PHB1) through blocking the ubiquitination via activation of estrogen receptor β (ERβ) to competitively interact with PHB1 and disrupt the binding of tripartite motif 21 (TRIM21) with PHB1. ERβ knock down in the colons of mice with DSS-induced colitis resulted in significant reduction of the protection of arctigenin and DPN against the mucosal barrier. Arctigenin can maintain the integrity of the mucus barrier by inhibiting the apoptosis of goblet cells through the ERβ/TRIM21/PHB1 pathway.

Topics: Animals; Apoptosis; Colitis; Estrogen Receptor beta; Furans; Goblet Cells; Inflammatory Bowel Diseases; Lignans; Mice; Mice, Inbred C57BL; Mucus; Phytoestrogens; Prohibitins

Phytoestrogens are plant-derived polyphenols with structural and functional similarities to mammalian oestrogens. The aim of this work was to study the metabolism of phytoestrogens by children's intestinal microbiota and to compare it with previous results in adults. Faecal samples of 24 healthy children were subjected to phytoestrogen fermentation assay. Only one child produced equol, while O-desmethylangolensin was found in all. Urolithin production was detected in 14 children and enterolactone in 10. Further comparison with the metabolism of phytoestrogens by adult intestinal microbiota reflected that glycitein, dihydrogenistein, urolithins D and E, enterolactone, secoisolariciresinol and arctigenin were the most important metabolites differentiating between adult and child microbial gut metabolism. Although the child intestinal microbiota showed the ability to metabolise isoflavones, ellagitannins and lignans to a certain extent, it generally showed a reduced metabolism of phytoestrogens, with a lack of 5-hydroxy equol and enterodiol, and less urolithins and enterolactone producers.

Topics: 4-Butyrolactone; Adult; Butylene Glycols; Case-Control Studies; Child, Preschool; Coumarins; Equol; Feces; Female; Furans; Gastrointestinal Microbiome; Humans; Hydrolyzable Tannins; Infant; Isoflavones; Lignans; Male; Phytoestrogens; Polyphenols

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.

Topics: Autophagy; Drug Synergism; Estrogen Receptor alpha; Female; Furans; Humans; Lignans; MCF-7 Cells; Phytoestrogens; Selective Estrogen Receptor Modulators; Signal Transduction; Tamoxifen; TOR Serine-Threonine Kinases

Arctigenin is a plant lignan extracted from Arctium lappa that has been shown to have estrogenic properties. In spite of the health benefits of phytoestrogens reducing the risk of osteoporosis, heart disease, and menopausal symptoms, its benefits against the risk of breast cancer have not been fully elucidated. Thus, we investigated the effects of arctigenin on metastasis of breast cancer using both estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cell lines to see if the effects are dependent on the status of ER expression. In ER-positive MCF-7 cells, arctigenin efficiently inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell migration and invasion. The activity of crucial metastatic protease matrix metalloprotease (MMP)-9 in gelatin zymography was also efficiently decreased by arctigenin, as well as its mRNA expression. Notably, arctigenin exhibited similar anti-metastatic effects even in ER-negative MDA-MB-231 cells, suggesting that the anti-metastatic effects of arctigenin were not exerted via the ER. The upstream signaling pathways involved in the regulation of MMP-9 and urokinase plasminogen activator (uPA) were analyzed using western blotting. The activation of Akt, NF-κB and MAPK (ERK 1/2 and JNK 1/2) was found to be inhibited. Taken together, these data suggest that arctigenin confers anti-metastatic effects by inhibiting MMP-9 and uPA via the Akt, NF-κB and MAPK signaling pathways on breast cancer, regardless of ER expression. Therefore, we propose that the intake of arctigenin could be an effective supplement for breast cancer patients.

Topics: Breast Neoplasms; Cell Line, Tumor; Cell Movement; Female; Furans; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Lignans; Matrix Metalloproteinase 9; MCF-7 Cells; Neoplasm Metastasis; Phytoestrogens; Receptors, Estrogen; Signal Transduction; Urokinase-Type Plasminogen Activator

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.

Topics: Activating Transcription Factor 2; Antioxidants; Apoptosis; Cell Line, Tumor; Epigenesis, Genetic; Ethylenediamines; Female; Furans; Gene Expression Regulation, Neoplastic; Histones; Humans; Lignans; Mammary Glands, Human; NADPH Oxidases; Organometallic Compounds; p38 Mitogen-Activated Protein Kinases; Phytoestrogens; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Receptors, Estrogen; Signal Transduction

Phytoestrogens are defined as plant-derived compounds with estrogen-like activities according to their chemical structures and activities. Plant lignans are generally categorized as phytoestrogens. It was reported that (-)-arctigenin, the aglycone of arctiin, was demethylated to (-)-dihydroxyenterolactone (DHENL) by Eubacterium (E.) sp. ARC-2. Through stepwise demethylation, E. sp. ARC-2 produced six intermediates, three mono-desmethylarctigenins and three di-desmethylarctigenins. In the present study, ligand binding affinities of (-)-arctigenin and its seven metabolites, including DHENL, were investigated for an estrogen receptor alpha, and found that demethylated metabolites had stronger binding affinities than (-)-arctigenin using a ligand binding screen assay method. The IC(50) value of (2R,3R)-2-(4-hydroxy-3-methoxybenzyl)-3-(3,4-dihydroxybenzyl)-butyrolactone was 7.9 × 10⁻⁴ M.

Topics: 4-Butyrolactone; Binding, Competitive; Estradiol; Estrogen Receptor alpha; Furans; Humans; Immobilized Proteins; Ligands; Lignans; Methylation; Phytoestrogens