A disintegrin and metalloproteinases 10 and 17 modulate the immunogenicity of glioblastoma-initiating cells

Background. There are emerging reports that the family of a disintegrin and metalloproteinases (ADAM) are involved in the maintenance of the malignant phenotype of glioblastomas. Notably, ADAM proteases 10 and 17 might impair the immune recognition of glioma cells via the activating immunoreceptor NKG2D by cleavage of its ligands from the cell surface. Glioblastoma-initiating cells (GIC) with stemcell properties have been identified as an attractive target for immunotherapy. However, GIC immunogenicity seems to be low. Methods and Results. Here, we show that ADAM10 and ADAM17 are expressed on the cell surface of GIC and contribute to an immunosuppressive phenotype by cleavage of ULBP2. The cell surface expression of ULBP2 is enhanced upon blocking ADAM10 and ADAM17, and treatment with ADAM10 and ADAM17 specific inhibitors leads to enhanced immunerecognition of GIC by natural killer cells. Conclusions. Therefore, ADAM10 and ADAM17 constitute suitable targets to boost an immune response against GIC.