Increased Active Tumor Targeting by An αvβ3-Targeting and Cell-Penetrating Bifunctional Peptide-Mediated Dendrimer-Based Conjugate.

PURPOSE: A bifunctional RGDTAT peptide-modified PEG-PAMAM dendrimer conjugate RGDTAT-PEG-PAMAM (RTPP) was established for the targeted treatment of αvβ3-overexpressing tumor cells.

METHODS: The RGDTAT peptide was synthesized and attached to PAMAM using PEG to construct the RTPP conjugate. The methotrexate (MTX) encapsulated RTPPM complex was prepared and characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM) and in vitro release. The targeting ability was then studied in cells and tumor-bearing nude mice using fluorescence microscopy, confocal fluorescence microscopy, flow cytometry, and in vivo imaging. The cytotoxicity and pharmacokinetics of the RTPPM complex was also evaluated in cells and rats.

RESULTS: The successful synthesis of the RTPP conjugate was confirmed by 1 H-NMR. DLS and TEM measurements revealed that the size was 37 nm and the complex had a spherical shape. RTPP and RTPPM were taken up by αvβ3-overexpressing cells more efficiently than by αvβ3-lowexpressing cells. The RTPP conjugate localized to the cell nucleus and accumulated in the tumor more efficiently than did the conjugates without RGDTAT. The pharmacokinetic study of the RTPPM complex showed sustained drug release.

CONCLUSIONS: The bifunctional peptide-mediated dendrimer-based RTPP conjugate can serve as a promising nanocarrier for targeted drug delivery to improve anti-tumor activity.