Background: Breast cancer remains the leading cause of cancer-related mortality among women globally. Among different subtypes of breast cancer, triple-negative breast cancer (TNBC), constituting about 10–20% of all breast cancers, lacks estrogen, progesterone, and HER2 receptors. It is clinically aggressive and lacks effective targeted therapies. RNA-based therapeutics, particularly microRNAs (miRNAs), have emerged as promising therapeutic agents for cancer therapy. However, efficient and targeted delivery remains a major translational challenge. Objective: This study aimed to evaluate functionalized small extracellular vesicle (sEVs)-based delivery system for the targeted delivery of therapeutic miRNAs in TNBC.
Methods: sEVs were isolated from non-tumorigenic HEK293 cells and were characterized by western blotting, DLS, and TEM analysis. The isolated sEVs were then conjugated to the GE11 peptide by EDC/Sulfo NHS reaction. Furthermore, the uptake efficiency of sEVs-GE11 was determined in non-TNBC and TNBC cell lines using FACS analysis.  Transcriptomic analysis of the miRNA-seq data from the Gene Expression Omnibus (GEO) datasets GSE38167, GSE40049, GSE86278, and GSE154255 was done to identify relevant tumor suppressor miRNA. The selected tumor suppressor miRNA was encapsulated into GE11-conjugated sEVs. Further, the targeted uptake and therapeutic efficacy of the complex were evaluated in TNBC cell lines and ex vivo 3D models.
Results: miR-204 was found to be the highly downregulated miRNA from the GEO transcriptomics analysis. sEVs-GE11 exhibited enhanced specificity and selectivity in TNBC cells compared to non-TNBC cells. Additionally, sEVs-GE11 could efficiently deliver miR-204 to TNBC cells and inhibit the proliferation, migration, and invasion of TNBC cell, both in 2D cultures and ex vivo 3D models.
Conclusion: We showed that sEVs-GE11 act as biocompatible, tumor-targeted nanocarriers capable of efficient miRNA delivery to TNBC cells. This study highlights functionalized sEVs as a promising platform for miRNA-based targeted therapeutics in TNBC.