A novel nucleolin-binding peptide for Cancer Theranostics

Abstract

<b>Background:</b> Cancer-specific ligands have been of great interest as pharmaceutical carriers due to the potential for site-specific delivery. In particular, cancer-specific peptides have many advantages over nanoparticles and antibodies, including high biocompatibility, low immunogenicity, and the formation of nontoxic metabolites. The goal of the present study was the development of a novel cancer-specific ligand. <b>Methods:</b> Cancer-specific peptide ligands were screened using a one-bead-one-compound (OBOC) combinatorial method combined with a multiple-antigen-peptide (MAP) synthesis method. The specificity of the peptide ligands toward cancer cells was tested <i>in vitro</i> using a whole-cell binding assay, flow cytometry, and fluorescence confocal microscopy. The tissue distribution profile and therapeutic efficacy of a paclitaxel (PTX)-conjugated peptide ligand was assessed <i>in vivo</i> using xenograft mouse models. <b>Results:</b> We discovered that AGM-330 specifically bound to cancer cells <i>in vitro</i> and <i>in vivo</i>. Treatment with PTX-conjugated AGM-330 dramatically inhibited cancer cell growth <i>in vitro</i> and <i>in vivo</i> compared to treatment with PTX alone. The results of pull-down assay and LC-MS/MS analyses showed that membrane nucleolin (NCL) was the target protein of AGM-330. Although NCL is known as a nuclear protein, we observed that it was overexpressed on the membranes of cancer cells. In particular, membrane NCL neutralization inhibited growth in cancer cells <i>in vitro</i>. <b>Conclusions:</b> In summary, our findings indicated that NCL-targeting AGM-330 has great potential for use in cancer diagnosis and targeted drug delivery in cancer therapy.