A novel αvβ3-blocking disintegrin containing the RGD motive, DisBa-01, inhibits bFGF-induced angiogenesis and melanoma metastasis

The integrin αvβ3 is involved in multiple aspects of malignant cancer, including tumor angiogenesis and metastasis, which makes the receptor a key target for the development of anti-cancer therapies. We report here on the production, the characterization and the in vivo anti-angiogenic and anti-metastatic properties of a novel αvβ3-binding disintegrin, DisBa-01, isolated from a cDNA library made with RNAs from the venom gland of Bothrops alternatus. The 11,637 Da-recombinant monomeric form of DisBa-01 displayed an RGD motif and interacted with purified αvβ3 integrin in surface plasmon resonance studies, in a dose-dependent and cation sensitive manner. A three-dimensional molecular model of DisBa-01 in complex with αvβ3 predicted a large surface of contacts with the β3 subunit. DisBa-01 inhibited the adhesion of αvβ3-expressing human microvascular endothelial cell line-1 (HMEC-1) and murine melanoma cell line B16F10 to vitronectin (IC50 = 555 nM and 225 nM, respectively), and transiently inhibited their proliferation without direct cell toxicity, but did not affect the binding nor the proliferation of a human breast cancer-derived cell line (MDA-MB-231) not expressing αvβ3. In vivo, DisBa-01 dose-dependently decreased bFGF-induced angiogenesis in a matrigel plug assay in athymic nude mice (IC50 = 83 nM). When injected intravenously to C57BL/6 mice together with B16F10 melanoma cells, DisBa-01 time- and dose-dependently inhibited lung metastasis monitored by bioluminescent imaging. We conclude that DisBa-01 is a potent new inhibitor of αvβ3-dependent adherence mechanisms involved in neo-vascularization and tumor metastasis processes.