To our knowledge, this is the first study to demonstrate that miR-126-3p has a tumor-suppressive function in thyroid cancer, that it is associated with aggressive disease, that it regulates angiogenesis and VEGF secretion, and that it directly regulates SLC7A5 and ADAM9 protein expression via regulation of the 3′-UTR of these two genes. This evidence concerns the gene ADAM9 and thyroid cancer.