Eun-Joung Moon

Histone deacetylases induce angiogenesis by negative regulation of tumor suppressor genes.

Low oxygen tension influences tumor progression by enhancing angiogenesis; and histone deacetylases (HDAC) are implicated in alteration of chromatin assembly and tumorigenesis. Here we show induction of HDAC under hypoxia and elucidate a role for HDAC in the regulation of hypoxia-induced angiogenesis. Overexpressed wild-type HDAC1 downregulated expression of p53 and von Hippel–Lindau tumor suppressor genes and stimulated angiogenesis of human endothelial cells. A specific HDAC inhibitor, trichostatin A (TSA), upregulated p53 and von Hippel–Lindau expression and downregulated hypoxia-inducible factor-1α and vascular endothelial growth factor. TSA also blocked angiogenesis in vitro and in vivo. TSA specifically inhibited hypoxia-induced angiogenesis in the Lewis lung carcinoma model. These results indicate that hypoxia enhances HDAC function and that HDAC is closely involved in angiogenesis through suppression of hypoxia-responsive tumor suppressor genes.

Hepatitis B virus X protein induces angiogenesis by stabilizing hypoxia-inducible factor-1α

Hepatitis B virus X protein (HBx) is closely involved in the development of hepatocellular carcinoma, a highly vascularized solid tumor. Here we show that HBx increases the transcriptional activity and protein level of hypoxia‐inducible factor‐1α (HIF‐1α) under both normoxic and hypoxic conditions, and it also stimulates angiogenesis. HBx directly interacted with the bHLH/PAS domain of HIF‐1α but not with the von Hippel‐Lindau protein (pVHL). HBx decreased the binding of pVHL to HIF‐1α and prevented ubiquitin‐dependent degradation of HIF‐1α. In HBx‐transgenic mice, HIF‐1α and vascular endothelial growth factor were strongly detected in the dysplastic lesion, where HBx was also more highly expressed than in the non‐neoplastic region of the liver. An immunohistochemical study showed that microvessels are more abundant in the dysplastic lesion than in the non‐neoplastic region. Our data suggest that HBx stabilizes HIF‐1α and leads to angiogenesis during hepatocarcinogenesis.

A novel angiogenic factor derived from Aloe vera gel: beta-sitosterol, a plant sterol.

Aloe vera gel has a beneficial effect on wound healing. Because angiogenesis is an essential process in wound healing, we hypothesized that Aloe vera gel might contain potent angiogenic compounds. Here we demonstrate that Aloe vera gel and its extracts are angiogenic on the chorioallantoic membrane (CAM) of chick embryo. Out of the three compounds purified from the final fraction of Aloe vera gel, β-sitosterol showed a potent angiogenic activity in the CAM assay. In the presence of heparin, β-sitosterol stimulated neovascularization in the mouse Matrigel plug assay and the motility of human umbilical vein endothelial cells in an in vitro wound migration assay. Thus β-sitosterol is a novel plant-derived angiogenic factor which may have potential pharmaceutical applications for the management of chronic wounds.

Identification of angiogenic properties of insulin-like growth factor II in in vitro angiogenesis models.

Insulin-like growth factor II (IGF-II), highly expressed in a number of human tumours, has been recently known to promote neovascularization in vivo. Yet, the detailed mechanism by which IGF-II induces angiogenesis has not been well defined. In the present study, we explored an angiogenic activity of IGF-II in in vitro angiogenesis model. Human umbilical vein endothelial cells (HUVECs) treated with IGF-II rapidly aligned and formed a capillary-like network on Matrigel. In chemotaxis assay, IGF-II remarkably increased migration of HUVECs. A rapid and transient activation of p38 mitogen-activated protein kinase (p38 MAPK) and p125 focal adhesion kinase (p125FAK) phosphorylation was detected in HUVECs exposed to IGF-II. IGF-II also stimulated invasion of HUVECs through a polycarbonate filter coated with Matrigel. Quantitative gelatin-based zymography identified that matrix metalloproteinase-2 (MMP-2) activity generated from HUVECs was increased by IGF-II. This induction of MMP-2 activity was correlated with Northern blot analysis, showing in HUVECs that IGF-II increased the expression of MMP-2 mRNA, while it did not affect that of TIMP-2, a tissue inhibitor of MMP-2. These results provide the evidence that IGF-II directly induces angiogenesis by stimulating migration and morphological differentiation of endothelial cells, and suggest that IGF-II may play a crucial role in the progression of tumorigenesis by promoting the deleterious neovascularization.

Anti-angiogenic activity of torilin, a sesquiterpene compound isolated from Torilis japonica

Torilin is a sesquiterpene compound purified from fruits of Torilis japonica (Umbelliferae). In this study, we demonstrated the anti‐angiogenic activity of torilin using in vivo and in vitro assay systems. Torilin decreased both neovascularization of chick embryos in the chorioallantoic membrane assay and basic fibroblast growth factor–induced vessel formation in the mouse Matrigel plug assay. Torilin also reduced the proliferation and tube formation of human umbilical vein endothelial cells. In addition, the concentrated conditioned media obtained from torilin‐treated HepG2 human hepatoblastoma cells blocked the angiogenic activation of torilin‐untreated concentrated conditioned media, indicating that torilin may have an inhibitory effect on tumor‐induced angiogenesis. To determine what molecules were involved in the anti‐angiogenic activity, we examined the expression of hypoxia‐inducible angiogenic factors in torilin‐treated HepG2 cells. Torilin significantly down‐regulated the expression of hypoxia‐inducible vascular endothelial growth factor and insulin‐like growth factor‐II. Taken together, our data suggest that torilin may be a strong angiogenic inhibitor with the ability to decrease tube formation of vascular endothelial cells and to reduce expression of angiogenic factors of tumor cells. Int. J. Cancer 87:269–275, 2000.

NEW METHOD OF EVALUATING RELATIVE THERMAL STABILITIES OF PROTEINS BASED ON THEIR AMINO ACID SEQUENCES: TARGETSTAR

Several computational methods have been developed to solve the problem of protein thermostabilization. One common drawback of them is that they must have the information of a backbone structure of a protein for the generation of a proper amino acid sequence. In this paper, we propose a new method called TargetStar by incorporating computational biology and statistical physics, in which an approximate partition function and a specific heat are used to calculate the folding transition temperature of a protein and then to predict the relative thermal stabilities for given proteins based only on their amino acid sequences. To evaluate the prediction accuracy of TargetStar, we calculated folding transition temperatures of 289 orthologous protein pairs using the proposed method, where each protein pair contains one hyperthermophilic protein and one mesophilic protein. According to our evaluation, hyperthermophilic and mesophilic proteins are distinguished from each other in terms of relative thermal stabilities with 77% prediction accuracy. Thus, TargetStar may serve as an efficient method to design an amino acid sequence of a target protein with the desired thermal stability prior to the expensive and time-consuming mutagenesis experiment.

AngioDB: database of angiogenesis and angiogenesis-related molecules

Angiogenesis is the formation of new capillaries sprouting from pre-existing vessels. Angiogenesis occurs in a variety of normal physiological and pathological conditions and is regulated by a balance of stimulatory and inhibitory angiogenic factors. The control of this balance may fail and result in the formation of a pathologic capillary network during the development of many diseases. Therefore, we developed the angiogenesis database (AngioDB), which can provide a signaling network of angiogenesis-related biomolecules in human. Each record of AngioDB consisted of 12 fields and was developed by using a relational database management system. For the retrieval of data, Active Server Page (ASP) technology was integrated in this system. Users can access the database by a query or imagemap browsing program. The retrieving system also provides a list of angiogenesis-related molecules classified by three categories, and the database has an external link to NCBI databases. AngioDB is available via the Internet at http://angiodb.snu.ac.kr/.

WebChemDB: An Integrated Chemical Database Retrieval System

Abstract WebChemDB is an integrated chemical database re-trieval system that provides access to over 8 million publicly available chemical structures, including related information on their biological activities and direct links to other public chemical resources, such as PubChem, ChEBI, and DrugBank. The data are publicly available over the web, using two-dimensional (2D) and three-di-mensional (3D) structure retrieval systems with various filters and molecular descriptors. The web services API also provides researchers with functionalities to pro-grammatically manipulate, search, and analyze the data.Availability: The database is accessible at http://bio-community.kr/chemsearch/index.jsp.Keywords: Chemical database, biological activities, struc-ture retrieval system, molecular descriptors Introduction Small molecules can be used as building blocks for combinatorial chemical synthesis; as molecular probes for analyzing biological systems in systems biology; and for the screening, design, and discovery of useful drug compounds (Chen et al., 2005; Ahn, 2007; Kang et al., 2009). Tying together many disparate sources of chem-ical and life sciences data into an integrated database is one of the main issues in the bioinformatics commu-nity. Large public chemical databases, such as Pub-Chem (Wang et al., 2009) and DrugBank (Wishart et al., 2008), provide chemical structures and associated bio-logical information, focusing on small organic molecules that have potential use in drug development with bio-medical research. PubChem is an increasingly popular, free-access, on-line molecular database that is operated by the National Center for Biotechnology Information (NCBI). But, many of the kinds of information that biologists find most in-teresting (links to primary literature; characterization data in the form of spectra, solubilities, melting/boiling points, etc.) do not appear in PubChem. Although the existing databases, in their current form, consist mainly of a catalog of biologically relevant mole-cules, increasing the level of crosslinking to other bio-logical databases could result in a much more useful service. As chemical databases that contain intersecting information continue to proliferate, such crosslinking is likely to increase in importance (http://zusammen.meta-molecular.com/). This paper, therefore, presents an integrated chemical database retrieval system for searching, visualizing, and analyzing chemical structures with associated biological information, including precalculated values for molecular properties (e.g., 3D coordinates, molecular weight, polar surface area, hydrogen bond donors/acceptors, rotat-able bonds, XLogP, etc.). The system also offers a fo-cused subset of calculated properties (e.g., drug-like, lead-like, etc.) for molecules that are filtered by physical properties. As such, it may be useful to those who per-form docking experiments or build focused chemical databases.