Biodistribution and evaluation of 131I ‐labeled neuropilin‐binding peptide for targeted tumor imaging

Neuropilin‐1 (NRP‐1) is overexpressed in several kinds of cancer cell and contributes to tumor aggressiveness. Recently, the arginine/lysine‐rich peptide with C‐terminal motifs (R/K)XX(R/K) indicated promising penetrating and transporting capability into NRP‐1 positive cancer cells. In the present study, we describe a 131I‐labeled C‐end rule motif peptide conjugate, Tyr–tLyp‐1, for NRP‐1 positive tumor targeting and imaging properties. Briefly, a truncated Lyp‐1 peptide was designed to expose its C‐end motif and conjugated to tyrosine for radiolabeling after structural modification. The peptide indicated specific binding to A549 cancer cells at 2 μM concentration, and its binding was dependent on NRP‐1 expression and could be inhibited by other NRP‐1‐binding peptides. In vivo imaging of 131I‐labeled Tyr–tLyp‐1peptide showed that a subcutaneous A549 xenograft tumor could be visualized using a SPECT/CT scanner. The tumor uptake of 131I‐Tyr–tLyp‐1 was 4.77 times higher than the uptake in muscles by SPECT/CT software quantification at 6 h post injection. Together, this study indicated that truncated Lyp‐1 peptide could specifically localize in NRP‐1 positive tumors and successfully mediate the 131I radionuclide diagnosis, indicating promising targeted imaging capability for NRP‐1 positive tumors. Copyright © 2016 John Wiley & Sons, Ltd. C‐end (K/R)XX(K/R) motif peptide mediates tumor imaging of 131I‐Tyr‐tLyp‐1 to ...
Source: Contrast Media and Molecular Imaging - Category: Radiology Authors: Tags: Full paper Source Type: research