Drug-Free Mesoporous Silica Nanoparticles Enable Suppression of Cancer Metastasis and Confer Survival Advantages to Mice with Tumor Xenografts.

Despite advancements in nanomedicine for drug delivery, many drug-loaded nanoparticles reduce tumor sizes but often fail to prevent metastasis. Mesoporous silica nanoparticles (MSNs) have attracted attention as promising nanocarriers. Here, we demonstrated that MSN-PEG/TA 25, with proper surface modifications, exhibited unique antimetastatic properties. In vivo studies showed that overall tumor metastasis decreased in 4T1 xenografts mice treated with MSN-PEG/TA 25 with a notable reduction in lung tumor metastasis. In vitro assays, including wound-healing, Boyden chamber, tube-formation, and real-time cell analyses, showed that MSN-PEG/TA 25 could modulate cell migration of 4T1 breast cancer cells and interrupt tube formation by human umbilical vein endothelial cells (HUVECs), key factors in suppressing cancer metastasis. The synergistic effect of MSN-PEG/TA 25 combined with liposomal-encapsulated doxorubicin (Lipo-Dox) significantly boosted mouse survival rates, outperforming Lipo-Dox monotherapy. We attributed the improved survival to the antimetastatic capabilities of MSN-PEG/TA 25. Moreover, Dox-loaded MSN-PEG/TA 25 suppressed primary tumors while retaining the antimetastatic effect, thereby enhancing therapeutic outcomes and overall survival. Western blot and qPCR analyses revealed that MSN-PEG/TA 25 interfered with the phosphorylation of ERK, FAK, and paxillin, thus impacting focal adhesion turnover and inhibiting cell motility. Our findings suggest that drug-free MSN-PEG/TA 25 is highly efficient for cancer treatment via suppressing metastatic activity and angiogenesis.