Development of Liver-Targeting αVβ5+ Exosomes as Anti-TGF-β Nanocarriers for the Treatment of the Pre-Metastatic Niche.

Abstract

Liver metastases frequently occur in pancreatic and colorectal cancer. Their development is promoted by tumor-derived exosomes with the integrin α_Vβ₅ on their membrane. This integrin directs exosomes to the liver, where they promote a TGF-β-dependent pre-metastatic niche. We proposed the development of α_Vβ₅⁺ exosomes to deliver anti-TGF-β therapy to the liver. This study demonstrates that the overexpression of α_Vβ₅ in 293T cells allows its transfer to the secreted exosomes. α_Vβ₅ overexpression increases exosome delivery to the liver, and α_Vβ₅⁺ exosomes accumulate more in the liver compared to the lungs, kidneys, and brain in mice. We then sought 293T cells to directly produce and load an anti-TGF-β agent in their exosomes. First, we transduced 293T cells to express shRNAs against Tgfb1; however, the exosomes isolated from these cells did not knock down Tgfb1 in treated macrophages in vitro. However, when 293T expressed an mRNA coding a soluble form of betaglycan (sBG), a TGF-β inhibitor, this mRNA was detected in the isolated exosomes and the protein in the conditioned media of macrophages treated in vitro. In turn, this conditioned media decreased the TGF-β-induced phosphorylation of SMAD2/3 in hepatic cells in vitro. Our findings suggest that α_Vβ₅⁺ exosomes could serve as nanocarriers for liver-targeted anti-TGF-β therapies.