Identification of a Glypican-3 Binding Peptide From a Phage-Displayed Peptide Library for PET Imaging of...

Tumor-targeting peptides functioned as molecular probes are essential for multi-modality imaging and molecular-targeting therapy in caner theronostics. Here, we performed a phage-displayed bio-panning to identify a specific binding peptide targeting Glypican-3 (GPC-3), a promising biomarker in hepatocellular carcinoma (HCC). After screening in the cyclic peptide library, a candidate peptide named F3, was isolated and showed specific binding to HCC cell lines. In a bio-distribution study, higher accumulation of F3 peptide was observed in HepG-2 tumors compared to PC-3 tumors in xenograft models. After labeling with radioactive ⁶⁸Ga, the F3 peptide tracer enabled the specific detection of tumors in HCC tumor models with PET imaging. More importantly, the expression of GPC-3 in human tissue samples may be distinguished by an F3 fluorescent peptide probe indicating its potential for clinical application. This cyclic peptide targeting GPC-3 has been validated, and may be an alternative to serve as an imaging probe or a targeting domain in the drug conjugate.