Nucleolin-targeted Extracellular Vesicles as a Versatile Platform for Biologics Delivery to Breast Cancer

Abstract

Small interfering RNAs (siRNA)/microRNAs (miRNA) have promising therapeutic potential, yet their clinical application has been hampered by the lack of appropriate delivery systems. Herein, we employed extracellular vesicles (EVs) as a targeted delivery system for small RNAs. EVs are cell-derived small vesicles that participate in cell-to-cell communication for protein and RNA delivery. We used the aptamer AS1411-modified EVs for targeted delivery of siRNA/microRNA to breast cancer tissues. Tumor targeting was facilitated via AS1411 binding to nucleolin, which is highly expressed on the surface membrane of breast cancer cells. This delivery vesicle targeted let-7 miRNA delivery to MDA-MB-231 cells in vitro as confirmed with fluorescent microscopic imaging and flow cytometry. Also, intravenously delivered AS1411-EVs loaded with miRNA let-7 labeled with the fluorescent marker, Cy5, selectively targeted tumor tissues in tumor-bearing mice and inhibited tumor growth. Importantly, the modified EVs were well tolerated and showed no evidence of nonspecific side effects or immune response. Thus, the RNAi nanoplatform is versatile and can deliver siRNA or miRNA to breast cancer cells both in vitro and in vivo. Our results suggest that the AS1411-EVs have a great potential as drug delivery vehicles to treat cancers.

Extracellular Vesicles for Cancer Therapy: Impact of Host Immune Response

“…Immune response to the engineered EVs was investigated. Serum associated cytokines IFN-α and TNF-α were measured in mice treated with EV-AS1411-let-7, with no statistically significant difference found when compared to a PBS treated group [36].…”

“…AS1411 has shown inhibition of tumor activity and low systemic toxicity in a Phase II clinical trial [35]. EVs were isolated from murine dendritic cells, mixed with AS1411 overnight to coat the EVs, and then EV-AS1411 were engineered by electroporation to carry miR-let-7 [36]. Immunocompromised mice received IV EVs-AS1411-let-7 or conjugated AS1411-let-7.…”

Recent progress in microRNA-based delivery systems for the treatment of human disease

“…Wang et al reported that AS1411, DNA aptamermodified EVs-loaded with Cy5-labeled let-7, could effectively accumulate in tumor tissues and suppress tumor growth when injected intravenously [98]. In another study, researchers demonstrated that the systemic administration of brain metastatic cancer cell-derived EVs containing miRNA-181c promoted brain metastasis and destruction of the blood-brain barrier (BBB) [99].…”

Proteomic Analysis of Extracellular Vesicles for Cancer Diagnostics

“…The foreseeable identification of cancer EV‐specific DNA and “glycan signature” may further enable their capture for clinical diagnostic purposes. On the other hand, researchers have been decorating EV outer membrane for targeted delivery such as employing EV‐labeled with c(RGDyK) to cross the blood–brain barrier and target brain lesions, as well as with aptamers AS1411 to recognize nucleolin on breast cancer cells …”