Chemical Tumor-Targeting of Nanoparticles Based on Metabolic Glycoengineering and Click Chemistry

Tumor-targeting strategies for nanoparticles have been predominantly based on optimization of physical properties or conjugation with biological ligands. However, their tumor-targeting abilities remain limited and insufficient. Furthermore, traditional biological binding molecules have intrinsic limitations originating from the limited amount of cellular receptors and the heterogeneity of tumor cells. Our two-step <i>in vivo</i> tumor-targeting strategy for nanoparticles is based on metabolic glycoengineering and click chemistry. First, an intravenous injection of precursor-loaded glycol chitosan nanoparticles generates azide groups on tumor tissue specifically by the enhanced permeation and retention (EPR) effect followed by metabolic glycoengineering. These ‘receptor-like’ chemical groups then enhance the tumor-targeting ability of drug-containing nanoparticles by copper-free click chemistry <i>in vivo</i> during a second intravenous injection. The advantage of this protocol over traditional binding molecules is that there are significantly more binding molecules on the surface of most tumor cells regardless of cell type. The subsequent enhanced tumor-targeting ability can significantly enhance the cancer therapeutic efficacy in animal studies

Tumor-Targeting Transferrin Nanoparticles for Systemic Polymerized siRNA Delivery in Tumor-Bearing Mice

Transferrin (TF) is widely used as a tumor-targeting ligand for the delivery of anticancer drugs because the TF receptor is overexpressed on the surface of various fast-growing cancer cells. In this article, we report on TF nanoparticles as an siRNA delivery carrier for in vivo tumor-specific gene silencing. To produce siRNA carrying TF nanoparticles (NPs), both TF and siRNA were chemically modified with sulfhydryl groups that can build up self-cross-linked siRNA-TF NPs. Self-polymerized 5′-end thiol-modified siRNA (poly siRNA, psi) and thiolated transferrin (tTF) were spontaneously cross-linked to form stable NPs (psi-tTF NPs) under optimized conditions, and they could be reversibly degraded to release functional monomeric siRNA molecules under reductive conditions. Receptor-mediated endocytosis of TF induced rapid tumor-cell-specific uptake of the psi-tTF NPs, and the internalized NPs resulted in a downregulation of the target protein in red-fluorescent-protein-expressing melanoma cancer cells (RFP/B16F10) with negligible cytotoxicity. After systemic administration, the psi-tTF NPs showed marked accumulation at the tumor, leading to successful target-gene silencing in vivo. This psi-tTF NP system provided a safe and effective strategy for in vivo systemic siRNA delivery for cancer therapy