Tumor Suppressive Function Of Human Macrophage-Derived Adam15 Exosomes.

A disintegrin and metalloproteinase (ADAM) 15, the only ADAM protein containing an Arg-Gly-Asp (RGD) motif in its disintegrin-like domain, is a widely expressed, human membrane protein. The present study demonstrates that macrophages derived from monocytes actively release ADAM15 into the extracellular space as an exosomal component. The exosomal ADAM15 release is further elevated by lipopolysaccharide stimulation, indicating that the exosome release is closely associated with immune cell differentiation and activation. ADAM15-rich exosomes display enhanced binding affinity for integrin alpha v beta 3, thereby interfering with the interaction between integrin alpha v beta 3 and vitronectin. ADAM15 exosomes significantly suppress vitronectin- and fibronectin-induced proliferation and migration of various tumor cells as well as tumor growth in vivo. Tumor suppressive function of exosomal ADAM15 is effectively blocked by monoclonal antibody specific for the extracellular domain of ADAM15. Experimental evidence shows that RGD-containing disintegrin-like domain, but not metalloproteinase activity, of ADAM15 is the responsible element for the tumor suppressive activity. Notably, proliferation and migration of macrophages are stimulated by the exosomes, indicating anti-tumor immunity. This work strongly suggests that a novel tumor suppressive mechanism is mediated by macrophage-derived ADAM15 exosomes. Citation Format: Hee Doo Lee, Yeon Hyang Kim, Doo-Sik Kim. Tumor suppressive function of human macrophage-derived ADAM15 exosomes. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A92.