Legumain protease-sheddable PEGylated, tuftsin-modified nanoparticles for selective targeting to tumour-associated macrophages.

Tumour-associated macrophages (TAMs) represent an attractive cell target for anticancer therapy. However, selective and efficient targeting of TAMs remains difficult. Here, we constructed a novel dually functionalised nanoparticle platform (s-Tpep-NPs) by surface co-modification of nanoparticles (NPs) with tuftsin (Tpep) and legumain protease-sheddable polyethylene glycol 5k (PEG5k) to achieve selective targeted delivery to TAMs. The fluorescence resonance energy transfer experiment and in vitro cellular uptake assay confirmed that s-Tpep-NPs can responsively shed PEG5k and transform into active Tpep-NPs upon the cleavage of legumain that is overexpressed on TAM surfaces, which then promotes TAM phagocytosis through Fc receptor-mediated pathways. Owing to the shielding effect by legumain-sheddable PEG5k, s-Tpep-NPs can effectively decrease the Tpep-induced non-specific accumulation in mononuclear phagocyte system (MPS) organs during systemic circulation. Moreover, s-Tpep-NPs can significantly enhance the tumoural accumulation and improve the specificity and efficiency of targeting to TAMs, as compared with both controls of Tpep-NPs and non-sheddable ns-Tpep-NPs. Overall, this study provides a robust nanoplatform with a novel avenue for improved selectivity of targeted delivery to TAMs.

Legumain protease-activated tuftsin-functionalized nanoparticles for dual-targeting TAMs and cancer chemotherapy.

M2 tumor-associated macrophages (TAMs) play a pivotal role in cancer progression and therapy resistance. Inhibition of TAMs is of great significance to reshape the protumor environment to benefit therapeutic outcomes. In this work, we developed a novel TAMs and tumor cells dual-targeting nanoparticle (ATpep-NPs) system for cancer chemotherapy by integrating a docetaxel (DTX)-loaded nanocarrier and a multi-function peptide ATpep, which is composed of a phagocytosis-stimulating peptide-tuftsin (Tpep) fused with a substrate peptide-alanine-alanine-asparagine (AAN) of endoprotease legumain. In vitro protelytic and cellular uptake assays confirmed ATpep-NPs can be responsively activated into Tpep-NPs by cleavage of legumain that is overexpressed in both tumor cells and TAMs, which then promoted tumor cells internalization and TAMs phagocytosis through neuropilin-1/Fc receptor pathways. Due to AAN deactivation effect, ATpep-NPs can effectively decrease the Tpep-induced non-specific uptake by M1-polarized and normal macrophage during systemic circulation. Our results of in vivo experiments demonstrated ATpep-NPs outperformed Tpep-NPs in tumor and TAMs dual-targeting delivery efficiency with markedly enhanced efficacy against both tumor growth inhibition and TAMs depletion. Overall, this study offers a novel approach for development of multitargeted delivery vehicle for improved cancer chemotherapy.