Biomimetic "nano-spears" for CAFs-targeting: Splintered three "shields" with enhanced cisplatin anti-TNBC efficiency.

The treatment dilemma of triple-negative breast cancer (TNBC) revolves around drug resistance and metastasis. Cancer-associated fibroblasts (CAFs) contribute to cisplatin (Cis) resistance and further metastasis in TNBC, making TNBC become a difficult-to-treat disease. The dense stromal barrier which restricts drug delivery, invasive phenotype of tumor cells, and immunosuppressive tumor microenvironment (TME) induced by CAFs serve as three "shields" for TNBC against Cis therapy. Here, we designed a silybin-loaded biomimetic nanoparticle coated with anisamide-modified red blood cell membrane (ARm@SNP) as a "nanospear" for CAFs-targeting, which could shatter the "shields" and significantly exhibit inhibitory effect on 4 T1 cells in combination with Cis both in vitro and in vivo. The ARm@SNP/Cis elicited 4 T1 tumor growth arrest and destroyed three "shields" as follows: disintegrating the stromal barrier by inhibiting blood vessels growth and the expression of fibronectin; decreasing 4 T1 cell invasion and metastasis by affecting the TGF-β/Twist/EMT pathway which impeded EMT activation; reversing the immunosuppressive microenvironment by increasing the activity and infiltration of immunocompetent cells. Based on CAFs-targeting, ARm@SNP reversed the resistance of Cis, remodeled the TME and inhibited invasion and metastasis while significantly improving the therapeutic effect of Cis on 4 T1 tumor-bearing mice, providing a promising approach for treating intractable TNBC.