Id1 is the direct downstream effector of bone morphogenetic proteins (BMPs), which are angiogenic and HS-binding proteins. xenografted in male nude mice. Immunohistochemical analysis showed that both the expression of Id1 and the endothelial cell marker CD31 were lower in the WSS25-treated tumor tissue than in the control. Therefore, WSS25 is a potential drug candidate for HCC therapy as a tumor angiogenesis inhibitor. Keywords:Anticancer Drug, Heparan Sulfate, Microarray, Protein Drug Interactions, Signal Transduction, BMP/Smad/Id1 Signaling, Hepatocellular Cancer, Id1, Angiogenesis, Quartz Crystal Microbalance (QCM) == Introduction == Hepatocellular cancer (HCC)3is the fourth leading cause of death from cancer worldwide and the second most lethal malignant cancer in China since the 1990s (1). However, there are few treatment options aside from surgery (1). HCC is characterized by hypervascularity, which can distinguish HCC from benign lesions by angiography. The strategy of blocking angiogenesis in HCC to inhibit tumor growth has been used for more than 20 years in the clinic (2). However, there are no ideal antiangiogenesis chemotherapeutic agents developed thus far for HCC therapy. Id1 is one of the inhibitors of DNA binding proteins (Ids), which belongs to the basic helix loop helix transcriptional factor superfamily (3). There are four members, Id1, Id2, Id3, and Id4, in the Ids family. Accumulating evidence show that Id1 is overexpressed in solid tumors and their supporting vasculatures (4,5). Although essential during embryo development, Id1 expression is extremely low in adult tissues, including the quiescent endothelial cells (6). Partial loss of Id1 by genetic manipulation in mice effectively inhibits tumor angiogenesis (6). Id1 ablation leads to the impairment of bone marrow endothelial progenitor cell recruitment and mobilization to form tumor vasculature (7,8). Id1 also has been implicated in the regulation of cell senescence, drug resistance, tumor cell invasion, (R)-MG-132 and apoptosis resistance (9). Interestingly, Id1 has been demonstrated to be highly expressed in malignant HCC and to promote angiogenesis in HCC (10,11). Thus, Id1 is a rational target for the development of antiangiogenesis therapeutics for HCC. Heparan sulfate proteoglycans are glycoconjugates composed of protein cores to which heparan sulfate (HS) chains are attached. Direct genetic evidence Rabbit Polyclonal to ZADH2 supports that heparan sulfate proteoglycans are necessary for tumor angiogenesis (12). Heparan sulfate proteoglycans, especially those located on the cell surface, act as co-receptors through their HS chains (13). HS chains are negatively charged polymers composed of hexaronic acid and glucosamine disaccharide repeats. Due to their negative charge, they bind multiple functional proteins, including proangiogenic factors such (R)-MG-132 as VEGF and FGF2, and thus mediate angiogenic signaling (14). HS mimetics such as PI-88 can inhibit angiogenesis via disrupting those interactions between HS and growth factors (15). TGF- family proteins can also bind HS chains. The binding is isoform-specific, and the established examples include BMP2 (16) and BMP4 (17), two angiogenic factors (18), and the upstream molecules of the BMP/Smad signaling pathway (19), whereas Id1 is a canonical and direct downstream effector of this pathway (20). More importantly, stimulation of Id1 expression by BMP proteins is sufficient and necessary for activating endothelial cells (21). Id1 also is the downstream effector of VEGF and FGF2 signaling pathway (3,22). Moreover, targeting the HS-protein interaction is a new approach for drug design (23). Therefore, we hypothesized that HS mimetics may inhibit angiogenesis through (R)-MG-132 blocking BMP-induced Id1 expression. We previously isolated an -d-(14) glucan with an -d-(14) branch periodically at O-6 from a well known Chinese herbGastrodia elataBl. WSS25 (Fig. 1) is a sulfated derivative of the aforementioned glucan and a HS mimetic (24). In this study, we investigated the role of WSS25 on angiogenesis, Id1 expression, BMP2-induced BMP/Smad/Id1 signaling, and growth of HCC. == FIGURE 1. == Structural diagram of WSS25. == EXPERIMENTAL PROCEDURES == == (R)-MG-132 == == == == General Materials == WSS25 was prepared in our lab as described previously (24) and dissolved in normal saline for experimental use after passing through a (R)-MG-132 0.22-m filter. Matrigel with growth factors and reduced growth factors were obtained from BD Biosciences. The proteinase inhibitor mixture.