Jae-Ha Ryu

Effects of bisphenol A on breast cancer and its risk factors

The incidence of breast cancer in Korea has been increasing for the last two decades (1983–2005), and now, breast cancer is ranked the leading cause of cancer in Korean women. Along with other endocrine disrupting chemicals (EDCs), bisphenol A (BPA) has been suspected as a potential risk factor for breast cancer. We studied potential associations between BPA exposure and breast cancer risks in Korean women by performing biomonitoring of BPA among breast cancer patients and controls (Nxa0=xa0167). Blood samples were collected between 1994 and 1997 and kept over 10xa0years in a freezer under well controlled conditions. The blood BPA levels determined by HPLC/FD, ranged between LOD (0.012 µg/L) and 13.87xa0µg/L (meanxa0±xa0SD, 1.69xa0±xa02.57xa0µg/L; median, 0.043xa0µg/L). In age-matched subjects (Nxa0=xa0152), there were some associations between BPA levels and risks of breast cancer, such as age at first birth and null parity. However, there were no significant differences in blood BPA levels between the cases and the controls (Pxa0=xa00.42). Considering interactions between BPA exposure and risks of breast cancer, we suggest further enlarged biomonitoring studies of BPA to provide effective prevention against breast cancer.

Ajoene, a Stable Garlic By-Product, Has an Antioxidant Effect through Nrf2-Mediated Glutamate-Cysteine Ligase Induction in HepG2 Cells and Primary Hepatocytes

Cytoprotective effects of chemopreventive agents may be attributed to the induction of antioxidant enzymes. Among these, the induction of glutamate-cysteine ligase (GCL) protects cells from oxidative injury by increasing glutathione (GSH) content. Nuclear factor erythroid-2-related factor 2 (Nrf2) transcriptionally regulates the expression of genes encoding for GCL and other cysteine-metabolizing enzymes. Despite extensive studies on the components in garlic, little information is available on organosulfur by-products made from garlic. In this study, we investigated whether ajoene, a chemically stable garlic by-product, has the ability to activate Nrf2 and induce GCL, and, if so, what is the role of activating Nrf2 in cytoprotection against oxidative stress. Immunoblottings and reporter gene assays were performed in HepG2 cells. Ajoene treatment activated Nrf2, as indicated by increased phosphorylation and nuclear accumulation of Nrf2, decreased interaction with Kelch-like ECH-associated protein-1, and decreased Nrf2 ubiquitination. Consistently, treatment of ajoene increased antioxidant response element reporter gene activity and the mRNA and protein levels of GCL subunits. Ajoene activated protein kinase C-delta (PKCdelta). Inhibition of PKCdelta activation by rottlerin abrogated its ability to activate Nrf2 and induce GCL, suggesting that ajoene promotes the Nrf2-dependent antioxidant defense system via PKCdelta activation. Consequently, ajoene prevented cell death, GSH depletion, and hydrogen peroxide production elicited by tert-butylhydroperoxide. The important role of Nrf2 in cytoprotection was verified by the reversal of ajoenes ability to protect hepatocytes in Nrf2-knockout mice. Our results demonstrate that ajoene increases PKCdelta-dependent Nrf2 activation, GCL induction, and the cellular GSH concentration, which may contribute to protecting cells from oxidative stress.

In vitro anti-inflammatory activity of lignans isolated from Magnolia fargesii.

The overproduction of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) causes neurodegenerative diseases, such as Alzheimers disease and Parkinsons disease. Four lignans, (+)-eudesmin (1), (+)-magnolin (2), (+)-yangambin (3) and a new structure named as epimagnolin B (4) were isolated from Magnolia fargesii (Magnoliaceae) as the inhibitors of NO production in LPS-activated microglia. The most potent compound 4 inhibited the production of NO and PGE(2) and the expression of respective enzyme iNOS and COX-2 through the suppression of I-kappaB-alpha degradation and nuclear translocation of p65 subunit of NF-kappaB.

Selenium suppresses the activation of transcription factor NF-κB and IRF3 induced by TLR3 or TLR4 agonists

Toll-like receptors (TLRs) play an important role in recognition of microbial components and induce innate immune responses by recognizing invading microbial pathogens leading to the activation of the adaptive immune responses. The microbial components trigger the activation of two downstream signaling pathways of TLRs; MyD88- and TRIF-dependent pathways leading to the expression of pro-inflammatory cytokines and type I interferons (IFNs). The MyD88- and TRIF-dependent pathways lead to the activation of NF-kappa B and IRF3 through the activation of IKK-beta and TBK1, respectively. Selenium is an essential trace element nutrient possessing anticarcinogenic properties. Here, we attempted to identify the molecular targets of selenium in TLR signaling pathways. Selenium inhibited NF-kappaB activation induced by poly[I:C] (TLR3 agonist), LPS (TLR4 agonist) or overexpression of MyD88 or IKK-beta which is the key kinase of MyD88-dependent signaling pathway. Selenium inhibited IRF3 activation induced by poly[I:C], LPS or the overexpression of TRIF or TBK1. Selenium also suppressed the expression of COX-2 and iNOS and the endogenous IFN beta mRNA induced by poly[I:C] or LPS. Therefore, our results suggest that selenium can modulate both MyD88- and TRIF-dependent signaling pathways of TLRs leading to decreased inflammatory gene expression.

In vitro anti-inflammatory activity of 3-O-methyl-flavones isolated from Siegesbeckia glabrescens.

Four flavones, 3,4-O-dimethylquercetin (1), 3,7-O-dimethylquercetin (2), 3-O-methylquercetin (3) and 3,7,4-O-trimethylquercetin (4) were isolated as the inhibitors of nitric oxide production in activated microglia (IC(50) values: 11.1, 4.2, 3.8, and 25.1 microM, respectively). They suppressed the expression of protein and mRNA of inducible nitric oxide synthase. Furthermore, compounds 2 and 3 showed scavenging activity of peroxynitrite with SC(50) values of 1.75 and 0.77 microM, respectively.

Inhibition of lipopolysaccharide-induced inducible nitric oxide synthase and cyclooxygenase-2 expression by xanthanolides isolated from Xanthium strumarium

Three sesquiterpenoids, xanthatin (1), xanthinosin (2), and 4-oxo-bedfordia acid (3) were isolated from Xanthium strumarium as inhibitors of nitric oxide synthesis in activated microglia (IC(50) values: 0.47, 11.2, 136.5 microM, respectively). Compounds 1 and 2 suppressed the expression of iNOS and COX-2 and the activity of NF-kappaB through the inhibition of LPS-induced I-kappaB-alpha degradation in microglia.

Suppression of inducible nitric oxide synthase and cyclooxygenase-2 expression by tussilagone from farfarae flos in BV-2 microglial cells

Activated microglia produce diverse neurotoxic factors such as nitric oxide (NO) and prostaglandin E2 (PGE2) that may cause neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. From the EtOAc soluble fraction of Farfarae flos (Tussilago farfara), we purified tussilagone as a bioactive compound by monitoring the inhibitory potential of NO production in activated microglia through the purification procedures. Tussilagone showed dose-dependent inhibition of NO and PGE2 production in LPS-activated microglia with IC50 values of 8.67 μM and 14.1 μM, respectively. It suppressed the expression of protein and mRNA of inducible nitric oxide synthase and cyclooxygenase-2 through the inhibition of 1-κBα degradation and nuclear translocation of p65 subunit of NF-κB. Therefore tussilagone from Farfarae flos may have therapeutic potential in the treatment of neuro-inflammatory diseases through the inhibition of overproduction of NO and PGE2.

Anti-angiogenic and anti-tumor activity of Bavachinin by targeting hypoxia-inducible factor-1α

Hypoxia-inducible factor-1 (HIF-1) consists of two subunits, the HIF-1β, which is constitutively expressed, and HIF-1α, which is oxygen-responsive. HIF-1α is over-expressed in response to hypoxia, increasing transcriptional activity linked to tumor progression, angiogenesis, metastasis, and invasion. This study aimed to demonstrate that the natural compound, Bavachinin, has potent anti-angiogenic activity in vitro and in vivo. Bavachinin inhibited increases in HIF-1α activity in human KB carcinoma (HeLa cell derivative) and human HOS osteosarcoma cells under hypoxia in a concentration-dependent manner, probably by enhancing the interaction between von Hippel-Lindau (VHL) and HIF-1α. Furthermore, Bavachinin decreased transcription of genes associated with angiogenesis and energy metabolism that are regulated by HIF-1, such as vascular endothelial growth factors (VEGF), Glut 1 and Hexokinase 2. Bavachinin also inhibited tube formation in human umbilical vein endothelial cells (HUVECs) as well as in vitro migration of KB cells. In vivo studies showed that injecting Bavachinin thrice weekly for four weeks significantly reduced tumor volume and CD31 expression in nude mice with KB xenografts. These data indicate that Bavachinin could be used as a therapeutic agent for inhibiting tumor angiogenesis.

In Vitro Antiinflammatory Activity of a New Sesquiterpene Lactone Isolated from Siegesbeckia glabrescens

A new sesquiterpene lactone was isolated from Siegesbeckia glabrescens as an inhibitor of nitric oxide and prostaglandin E2 synthesis in the LPS‐activated RAW264.7 macrophage cell line. It dose‐dependently decreased the protein and mRNA levels of inducible nitric oxide synthase and cyclooxygenase‐2. Reporter gene assay revealed that the compound attenuated the LPS‐induced DNA transcriptional activity of nuclear factor‐kappa B (NF‐κB). In addition, it inhibited the nuclear translocation of the p65 subunit of NF‐κB by blocking the inhibitory kappa B‐α degradation. This compound from Siegesbeckia glabrescens might be beneficial for the treatment of inflammation‐related diseases. Copyright

SPA0355, a thiourea analogue, inhibits inflammatory responses and joint destruction in fibroblast‐like synoviocytes and mice with collagen‐induced arthritis

BACKGROUND AND PURPOSE NF‐κB has been implicated as a therapeutic target for the treatment of rheumatoid arthritis. We previously synthesized a thiourea analogue, SPA0355, which suppressed NF‐κB activity. Here we have assessed the anti‐inflammatory and anti‐arthritic effects of SPA0355.