Identification of melanotransferrin (MFI2) as a membrane target and an MFI2-directed aptamer as a theranostic tool for pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by poor prognosis and limited targeted therapeutic options. Melanotransferrin (MFI2) is a membrane-anchored protein that we found to be significantly upregulated in PDAC tissues and cell lines. MFI2 knockdown markedly reduced cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in PDAC cells. Using cell-based SELEX, we identified a DNA aptamer, MS2, that specifically binds MFI2 with high affinity (Kd = 39 nM). We further optimized MS2 to generate the truncated aptamer MS2-1 and subsequently constructed an MS2-1-based aptamer-doxorubicin conjugate (MS2-1-GC-Dox). The conjugate exhibited greater cytotoxicity toward MFI2-positive pancreatic cancer cells than free doxorubicin, with IC50 values of 0.49 μM and 1.06 μM, respectively, while showing reduced cytotoxicity toward MFI2-negative cells. These results establish MFI2 as a novel, actionable membrane target in PDAC, and demonstrate that aptamer-based targeted drug delivery represents a promising therapeutic strategy for this aggressive malignancy.