Tumor environment differentiated "nanodepot" programmed for site-specific drug shuttling and combinative therapy on metastatic cancer.

Metastatic cancer is difficult to defeat with current treatments due to lack of etiological therapeutics and efficient delivery platforms. Employing tumor microenvironment in programming intelligent nanosystems has attracted considerable attention for combinative antitumor therapy. Herein, we proposed a core-shell based drug depot consisting of micellar core and crosslinked-gel shell for site-specific shuttling of paclitaxel (PTX) and KIAA1199 specific shRNA (shKIAA). Poly (e-caprolactone) were grafted with branched polyethylenimine (PEI-PCL) as micellar core, into which hydrophobic PTX was embedded; while shKIAA, a reliable RNAi regimen for metastatic cell inhibition was condensed with PEI through electrostatic interaction; and then photo-crosslinked hyaluronic acid (m-HA) was further coated as shell. The nanoscale drug depot shared HAase-triggered charge switching and desirable release profile. Upon reaching tumor region, HA shell was degraded by concentrated HAase, and facilitated drug shuttling to individual subcellular targeting site. Rapid intracellular trafficking of micellar core achieved endo/lysosomal escape and cytoplasmic liberation. The half-maximal inhibitory concentration (IC50) of "nanodepot" toward human breast cancer cell line MDA-MB-231 was 0.016 μg/mL (PTX concentration), approximately 3-fold decrease compared to that of monotherapy group (0.043 μg/mL). The tumor weight inhibition (TWI) is 83.30% in xenografted MDA-MB-231 tumor model and metastasis was effectively inhibited in 4T1 orthotopic tumors. Moreover, knockdown of KIAA1199 via sustainable RNAi affected a broad range of cellular functions including apoptosis, migration and invasion. Collectively, tumor environment differentiated spatiotemporal co-delivery fashion holds a great promise for combinative treatment with enhanced efficacy on metastatic cancer cases.