Aptamer as a molecular tethering agent induces PrPC aggregation and degradation to inhibit melanoma proliferation

Melanoma, a malignant tumor originating from melanocytes, is the most aggressive and deadly form of skin cancer. Previous studies have revealed that the cellular prion protein (PrPC) is frequently overexpressed in melanoma, contributing to tumor progression. This study presents the first proof-of-concept evidence that nucleic acid aptamers can be used to construct a molecular tethering agent that regulates PrPC protein levels by inducing membrane-bound PrPC aggregation for anti-melanoma therapy. Using a screening strategy combining cell-SELEX and cell-internalization SELEX, we obtained an ssDNA aptamer, TT-1e, specifically binding to melanoma cells and tissues. We identified that the binding site of TT-1e is located at the octapeptide repeat region of glycosylated PrPC. Based on the binding characteristics of TT-1e, we engineered an aptamer-based molecular tethering agent TTe-TTe. We found that TTe-TTe induces aggregation of cell surface PrPC, promoting its internalization and facilitating its lysosomal degradation. This process resulted in the inhibition of AKT pathway activation. Importantly, in vivo studies confirmed the ability of TTe-TTe to target melanoma xenografts and suppress tumor growth through this unique mechanism. Our study presents a promising strategy for targeted melanoma therapy and introduces a paradigm-shifting approach for manipulating protein levels using aptamers as molecular tethering agents.