The present invention relates to a novel function of Msx1 protein for inhibiting tumor angiogenesis and metastasis by targeting mTOR (mammalian target of rapamycin) signaling pathway, and for treating a cancer in a subject. Particularly, Msx1 suppresses mTOR through a direct interaction with mTOR, resulting in the inhibition of angiogenesis. The Msx1 significantly suppresses tumor angiogenesis that is necessary for the growth, invasion, and metastasis of solid tumors. Ad-Msx1 can be used to effectively inhibit tumor metastasis by suppressing angiogenesis, tumor cell invasion, and migration.