Self-assembled RNA nanocarrier-mediated chemotherapy combined with molecular targeting in the treatment of esophageal squamous cell carcinoma.

Background: Esophageal cancer is the fifth most common cancer affecting men in China. The primary treatment options are surgery and traditional radio-chemotherapy; no effective targeted therapy exists yet. Self-assembled RNA nanocarriers are highly stable, easily functionally modified, and have weak off-tumor targeting effects. Thus, they are among the most preferred carriers for mediating the targeted delivery of anti-tumor drugs. miR-375 was found to be significantly down-regulated in esophageal squamous cell carcinoma (ESCC) tissues and its overexpression effectively inhibits the proliferation, migration, and invasion of ESCC cells. Moreover, epidermal growth factor receptor (EGFR) was overexpressed in ESCC cells, and accumulation of RNA nanoparticles in ESCC tumors was enhanced by EGFR-specific aptamer (EGFR) modification.

Results: Herein, a novel four-way junction RNA nanocarrier, 4WJ-EGFR-miR-375-PTX simultaneously loaded with miR-375, PTX and decorated with EGFR, was developed. In vitro analysis demonstrated that 4WJ-EGFR-miR-375-PTX possesses strong thermal and pH stabilities. EGFR decoration facilitated tumor cell endocytosis and promoted deep penetration into 3D-ESCC spheroids. Xenograft mouse model for ESCC confirmed that 4WJ-EGFR-miR-375-PTX was selectively distributed in tumor sites via EGFR-mediating active targeting and targeted co-delivery of miR-375 and PTX exhibited more effective therapeutic efficacy with low systemic toxicity.

Conclusion: This strategy may provide a practical approach for targeted therapy of ESCC.