286. Conditionally Replicating Adenoviral Vectors for Glioblastoma Treatment

Abstract

Metargidin, a transmembrane protein of the adamalysin family, and integrins, e.g. a5b1 and av, are preferentially expressed on endothelial cells upon angiogenesis. Furthermore, metargidin interacts with these integrins via its disintegrin domain. In this study, recombinant human disintegrin domain (RDD) was produced in Escherichia coli by subcloning its cDNA into the pGEX-2T vector, and the effect of purified RDD on different steps of angiogenesis was evaluated. At concentrations of 2–10 μg/ml, RDD exhibited inhibitory activities in a variety of in vitro functional assays, including endothelial cell proliferation and adhesion on the integrin substrates, fibronectin, vitronectin or fibrinogen. RDD (10 μg/ml) totally abrogated endothelial cell migration and blocked most capillary formation in a tridimensional fibrin gel. To test RDD efficacy in vivo, the RDD gene inserted into pBi vector containing a tetracycline-inducible promoter was eletrotransferred into nude mouse muscle. RDD was successfully synthesized by muscle cells in vivo as shown by immunolabeling and Western blotting. In addition, 78% less MDA-MB-231 tumor growth, associated with strong inhibition of tumor angiogenesis, was observed in athymic mice bearing electrotransferred RDD. Moreover, in the presence of RDD, 74% fewer B16F10 melanoma lung metastases were found in C57BL/6 mice. Taken together, these results identified this RDD as a potent intrinsic inhibitor of angiogenesis, tumor growth and metastasis, making it a promising tool for use in anticancer treatment.