Jedo Oh

Magnolol inhibits angiogenesis by regulating ROS-mediated apoptosis and the PI3K/AKT/mTOR signaling pathway in mES/EB-derived endothelial-like cells

Magnolol, a neolignan from the traditional medicinal plant Magnolia obovata, has been shown to possess neuroprotective, anti-inflammatory, anticancer and anti-angiogenic activities. However, the precise mechanism of the anti-angiogenic activity of magnolol remains to be elucidated. In the present study, the anti-angiogenic effect of magnolol was evaluated in mouse embryonic stem (mES)/embryoid body (EB)-derived endothelial-like cells. The endothelial-like cells were obtained by differentiation from mES/EB cells. Magnolol (20 µM) significantly suppressed the transcriptional and translational expression of platelet endothelial cell adhesion molecule (PECAM), an endothelial biomarker, in mES/EB-derived endothelial-like cells. To further understand the molecular mechanism of the suppression of PECAM expression, signaling pathways were analyzed in the mES/EB-derived endothelial-like cells. Magnolol induced the generation of reactive oxygen species (ROS) by mitochondria, a process that was associated with the induction of apoptosis as determined by positive Annexin V staining and the activation of cleaved caspase-3. The involvement of ROS generation by magnolol was confirmed by treatment with an antioxidant, N-acetyl-cysteine (NAC). NAC inhibited the magnolol-mediated induction of ROS generation and suppression of PECAM expression. In addition, magnolol suppressed the activation of MAPKs (ERK, JNK and p38) and the PI3K/AKT/mTOR signaling pathway in mES/EB-derived endothelial-like cells. Taken together, these findings demonstrate for the first time that the anti-angiogenic activity of magnolol may be associated with ROS-mediated apoptosis and the suppression of the PI3K/AKT/mTOR signaling pathway in mES/EB-derived endothelial-like cells.

Thio-Cl-IB-MECA, a novel A3 adenosine receptor agonist, suppresses angiogenesis by regulating PI3K/AKT/mTOR and ERK signaling in endothelial cells

Although A₃AR agonists exhibit a variety of biological activities including anticancer effects, their possible anti-angiogenic effects have not yet been investigated. In the present study, we assayed the anti-angiogenic activity of thio-Cl-IB-MECA, a novel A₃AR agonist, in cultured HUVECs and mES/EB-derived endothelial cells. Thio-Cl-IB-MECA inhibited migration and tube formation by endothelial cells and dramatically decreased ex vivo microvessel sprouting in cultured mouse aortic rings. The anti-angiogenic activity of thio-Cl-IB-MECA was associated with suppression of the expression of the endothelial biomarker PECAM via regulation of PI3K/AKT/mTOR and ERK signaling in mES/EB-derived endothelial cells.

Anti-Osteoporotic Activity of Harpagoside by Upregulation of the BMP2 and Wnt Signaling Pathways in Osteoblasts and Suppression of Differentiation in Osteoclasts

Harpagoside (1) is an iridoid glycoside isolated from the radix of Harpagophytum procumbens var. sublobatum, commonly called Devils claw. The anti-osteoporotic effect of 1 was investigated in both in vitro cell cultures and in vivo using an ovariectomized (OVX) mouse model. Compound 1 induced bone formation by stimulating osteoblast proliferation, alkaline phosphatase activity, and mineralization in osteoblastic MC3T3-E1 cells. Treatment with 1 increased the mRNA and protein expression of bone formation biomarkers through regulation of the BMP2 and Wnt signaling pathway in MC3T3-E1 cells. Compound 1 also suppressed the RANKL-induced osteoclastogenesis of cultured mouse bone marrow cells. Oral administration of 1 restored the OVX-induced destruction of trabecular bone. The bone mineral density of the femur was also increased significantly by 1. The elevated serum levels of osteocalcin, C-terminal telopeptide, and tartrate-resistant acid phosphatase in the OVX mice were decreased by treatment with 1. These findings suggest that compound 1 may protect against bone loss induced by OVX in mice by regulating stimulation of osteoblast differentiation and inhibition of osteoclast resorption. Therefore, harpagoside (1) is a potential candidate for management of postmenopausal osteoporosis.

Cytotoxic activities of Telectadium dongnaiense and its constituents by inhibition of the Wnt/β-catenin signaling pathway

BACKGROUND Wnt/β-catenin signaling pathway is a potential target for the treatment of human colon cancer. Thus, the inhibitory effects of various plant extracts on cell proliferation and Wnt signal transduction were evaluated to discover a Wnt signaling inhibitor. PURPOSE The present study aimed to investigate the cytotoxicity involved in Wnt pathway of the MeOH extract from Telectadium dongnaiense bark (TDB) and to identify its bioactive constituents by bioassay-guided fractionation. METHODS The sulforhodamine B-based proliferation assay and the β-catenin/TCF-responsive reporter gene assay were employed as screening systems. The isolation and identification of compounds were elucidated on the basis of spectroscopic methods. Inhibitory effects on the expression levels of Wnt target genes were determined by real-time PCR and western blotting. RESULTS The extract of TDB most strongly inhibited cell proliferation and TOPflash activity (IC50 = 1.5 and 2.0 µg/ml), which was correlated with its inhibitory effects on the expression of Wnt target genes. Three major compounds were isolated from bioactive fractions and were identified as 1,4-dicaffeoylquinic acid (1), quercetin 3-rutinoside (2), and periplocin (3). Only compound 3 showed anti-proliferative activity (IC50 = 0.06 µM) and exhibited Wnt signaling inhibitory effects in HCT116 colon cancer cells. CONCLUSIONS This study contributes to understanding the cytotoxic properties of TDB extract and its constituents and provides a potent strategy for its further application.

Esculetin suppresses tumor growth and metastasis by targeting Axin2/E-cadherin axis in colorectal cancer

Graphical abstract Figure. No Caption available. ABSTRACT Colorectal cancer (CRC) is the most common malignant disease worldwide due to its metastasis via the epithelial‐mesenchymal transition (EMT) process. E‐cadherin and Wnt signaling are emerging as potential targets for suppressing the EMT. In this context, Axin2 has been recognized as a negative regulator that inhibits glycogen synthase kinase 3&bgr; (GSK3&bgr;)‐mediated degradation of Snail1, a transcriptional repressor of E‐cadherin. However, Axin2 can also impede Wnt signaling via &bgr;‐catenin degradation. Therefore, Axin2 may serve as either a promoter or suppressor of tumors, and the effects of its inhibition on the cell proliferation and metastasis of CRC require further elucidation. Here, esculetin (ES), a coumarin, was found to have the most potential effects on both &bgr;‐catenin‐responsive transcriptional and E‐cadherin promoter activities. ES also showed anti‐proliferative and anti‐invasive activities in CRC cells. Mechanistically, Axin2 suppression by ES contributed to E‐cadherin‐mediated Wnt signaling inhibition. Moreover, the ability of ES to inhibit tumor growth and metastasis via Axin2 suppression was further supported in an HCT116‐implanted orthotopic mouse model. Collectively, these findings suggest that targeting the Axin2/E‐cadherin axis by ES may be an attractive therapeutic strategy for the treatment of metastatic CRC.

Abstract 4235: Anti-proliferative effect of (19Z)-halichondramide from the sponge Chondrosia corticata via G2/M cell cycle arrest and suppression of mTOR signaling in human lung cancer cells

Five oxazole-containing macrolides isolated from the marine sponge Chondrosia corticata were evaluated for their anti-proliferative activity in a panel of human solid cancer cell lines. (19Z)-Halichondramide ((19Z)-HCA), a novel trisoxazole-containing macrolide, exhibited the highest potency among the macrolides, with IC 50 values in the submicro-molar ranges. Prompted by the high potency of growth inhibition of cancer cells, we investigated the mechanism of action of the anti-proliferative activity of (19Z)-HCA in human A549 lung cancer cells. (19Z)-HCA induced cell cycle arrest in the G2/M phase, and this event was highly correlated with the expression of checkpoint proteins, including the up-regulation of p53 and GADD45α and the down-regulation of cyclin B1, cyclin A, CDC2, and CDC25C. In addition, the growth inhibition by (19Z)-HCA was associated with the suppression of mTOR and its downstream effector molecules 4EBP1 and p70S6K. The modulation of mTOR signaling by (19Z)-HCA was found to be mediated by the regulation of upstream proteins, including the down-regulation of Akt and p38 MAPK and the up-regulation of AMPK. These data suggest the potential of (19Z)-HCA to serve as a candidate for cancer chemotherapeutic agents derived from marine organisms by virtue of arresting the cell cycle in the G2/M phase and the modulation of mTOR/AMPK signaling pathways. [Acknowledgements: This work was supported by the MarineBio Research Program (NRF-2013045101) of the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (MEST).] Citation Format: Song Yi Bae, Jayoung Song, Yoonho Shin, Won Kyung Kim, Jedo Oh, Tae Joon Choi, Eun Ju Jeong, So Hyun Park, Eun Jeong Jang, Ji In Kang, Hyen Joo Park, Ji-Young Hong, Gi Dae Kim, Ju-eun Jeon, Jongheon Shin, Sang Kook Lee. Anti-proliferative effect of (19 Z )-halichondramide from the sponge Chondrosia corticata via G2/M cell cycle arrest and suppression of mTOR signaling in human lung cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4235. doi:10.1158/1538-7445.AM2014-4235

WS9326H, an Antiangiogenic Pyrazolone-Bearing Peptide from an Intertidal Mudflat Actinomycete

WS9326H (1), a new cyclic peptide, was isolated from a mudflat-derived Streptomyces strain. Based on analysis by 1D/2D NMR, UV spectroscopy, and mass spectrometry, compound 1 was determined to have the gross structure of a cyclic heptapeptide bearing an unprecedented pyrazolone ring connected to a d-arabinitol via an amide bond. The absolute configuration of 1 was established by multistep chemical derivatizations, comprehensive NMR, and LC/MS analyses of the derivatives and quantum mechanics-based computational methods. WS9326H (1) displayed significant antiangiogenesis activity.

New Scaffold for Angiogenesis Inhibitors Discovered by Targeted Chemical Transformations of Wondonin Natural Products

The structure of wondonin marine natural products was renovated to attain new drug-like scaffolds. Wondonins have novel antiangiogenic properties without overt cytotoxicity. However, the chemical instability and synthetic complexity of wondonins have hindered their development as a new type of antiangiogenesis agent. Using a structure-based bioisosterism, the benzodioxole moiety was changed to benzothiazole, and the imidazole moiety was replaced by 1,2,3-triazole. Our efforts resulted in a new scaffold with enhanced antiangiogenic activity and minimized cytotoxicity. One compound with this scaffold effectively inhibited hyaloid vessel formation in diabetic retinopathy mimic zebrafish model. The biological findings together suggested the potential of the scaffold as a lead structure for development of antiangiogenic drugs with novel functions and as a probe to elucidate new biological mechanisms associated with angiogenesis.

Abstract 5567: Anti-angiogenic activity of Thio-Cl-IB-MECA, a novel A3 adenosine receptor agonist, by regulating of PI3K/AKT/mTOR and ERK signaling pathways in endothelial cells

Angiogenesis is a complex process that involves sprouting of new capillaries from pre-existing blood vessels. Angiogenesis is also involved in many pathological conditions including tumor growth, diabetic retinopathy, psoriasis, rheumatoid arthritis, and atherosclerosis. In cancer, newly formed vessels not only promote tumor growth but also cause the tumor cells to become more malignant and metastatic. Therefore, angiogenesis is an attractive target for the development of a wide variety of therapies, including antitumor agents. A3 adenosine receptor (A3AR) agonists have exhibited anti-proliferative activity against cancer cells. However, anti-angiogenic effects of A3AR agonists in endothelial cells have not been investigated yet. In the present study, the potential anti-angiogenic activity and precise mechanism of action of the A3AR agonist thio-Cl-IB-MECA (TCIM) were investigated in cultured HUVECs and mouse embryonic stem cells/embryonic body (mES/EB) derived endothelial cells. TCIM inhibited migration and tube formation of endothelial cells and markedly decreased ex vivo microvessel sprouting in cultured mouse aortic rings. TCIM also suppressed the expression of the endothelial biomarker platelet endothelial cell adhesion molecule (PECAM) via regulation of PI3K/AKT/mTOR and ERK signaling in mES/EB-derived endothelial cells. Citation Format: Jedo Oh, Gi Dae Kim, Lak Shin Jeong, Sang Kook Lee. Anti-angiogenic activity of Thio-Cl-IB-MECA, a novel A3 adenosine receptor agonist, by regulating of PI3K/AKT/mTOR and ERK signaling pathways in endothelial cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5567. doi:10.1158/1538-7445.AM2015-5567

Abstract 4237: Antitumor activity of 2-hydroxycinnamaldehyde against human colorectal cancer cells is mediated by the Wnt/β-catenin signaling pathway

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA The antiproliferative and antitumor activities of 2-hydroxycinnamaldehyde (1), a phenylpropanoid isolated from the bark of Cinnamomum cassia , were investigated using human colorectal cancer cells. Compound 1 exhibited antiproliferative effects in HCT116 colon cancer cells, accompanied by modulation of the Wnt/β-catenin cell signaling pathway. This substance was found also to inhibit β-catenin/T-cell factor (TCF) transcriptional activity in HEK293 cells and HCT116 colon cancer cells. Further mechanistic investigations in human colon cancer cells with aberrantly activated Wnt/β-catenin signaling showed that 1 suppressed significantly the binding of β-catenin/TCF complexes to their specific genomic targets in the nucleus and led to the down-regulation of Wnt target genes such as c-myc and cyclin D1. In an in vivo xenograft model, the intraperitoneal administration of 1 (10 or 20 mg/kg body weight, three times/week) for four weeks suppressed tumor growth in athymic nude mice implanted with HCT116 colon cancer cells significantly, without any apparent toxicity. In an ex vivo biochemical analysis of the tumors, compound 1 was also found to suppress Wnt target genes associated with tumor growth including β-catenin, c-myc, cyclin D1, and survivin. The suppression of the Wnt/β-catenin signaling pathway is a plausible mechanism of action underlying the antiproliferative and antitumor activity of 1 in human colorectal cancer cells (Acknowledgements: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean Government (MEST) No. 20120004939) Citation Format: Won Kyung Kim, Jedo Oh, Song Yi Bae, Jayoung Song, Yoonho Shin, Tae Joon Choi, Eun Ju Jeong, So Hyun Park, Eun Jeong Jang, Ji In Kang, Hyen Joo Park, Ji-Young Hong, Min Ai Lee, Hwa-Jin Chung, Sang Kook Lee. Antitumor activity of 2-hydroxycinnamaldehyde against human colorectal cancer cells is mediated by the Wnt/β-catenin signaling pathway. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4237. doi:10.1158/1538-7445.AM2014-4237