Preparation, characterization, and in vitro tumor-suppressive effect of anti-miR-21-equipped RNA nanoparticles.

MicroRNAs play an irreplaceable role in gene expression regulation. Upregulation of several miRNAs increases the risk of invasion and metastasis of breast cancer cells. An oncogenic miRNA, miR-21, is highly expressed in triple-negative breast cancer (TNBC) and is associated with tumor proliferation, invasion, carcinogenesis, prognosis, and therapeutic resistance. However, targeted delivery of therapeutic anti-miRNAs into cancer cells remains challenging, especially for TNBC. In this study, we report the application of an RNA nanotechnology-based platform for the targeted delivery of anti-miR-21 by epidermal growth factor receptor (EGFR) aptamer in vitro to TNBC and chemical-resistant breast cancer cells. RNA nanoparticles reduced cell viability and sensitized breast cancer cells to doxorubicin (DOX) treatment in vitro. Inhibition of miR-21 by RNA nanoparticles suppressed TNBC cell invasion, migration, and colony formation. The results indicate the potential application of nanotechnology-based delivery platforms in clinical anti-cancer therapeutics.