Aptamer-protamine-siRNA nanoparticles in targeted therapy of ErbB3 positive breast cancer cells.

Background: RNAi-based technology has achieved good results in both in vitro and in vivo applications, and it is expected to become a good genetic treatment for some diseases, especially neoplastic diseases. But there are still many obstacles in the in vivo application, the most important thing is the lack of an efficient and safe carrier.

Methods: In this study, we designed and constructed a new siRNA delivery, which was named as aptamer-protamine-siRNA nanoparticle (APR). APR was consisted of ErbB3 aptamer, protamine and siRNA. We used Zeta nanosize to detect the size of APR to verify whether it is a nano-scale compound. We use the FAMRNA to replace the siRNA to detect whether APR could recognize and enter ErbB3 positive MCF-7 cells. Then we replaced the siRNA as oncogene suvivin siRNA to detect whether APR could inhibit tumor growth by silence surviving, and replaced siRNA to CDK1 siRNA to detect the cell cycle blocking effect. At last we tested the anticancer effect and safety of APR by carrying survivin siRNA in MCF-7 bearing nude mice.

Results: APR was identified as a nanoscale compound. It showed specific targeting for ErbB3-positive MCF-7 cancer cells. APR has demonstrated the characteristics of inhibiting tumor growth by carrying siRNA against oncogene survivin. APR could also block cell cycle of MCF-7 cells by delivering CDK1 siRNAs. In the ErbB3 positive breast cancer xenograft mice model, APR nanoparticles could inhibit tumor growth and cause tumor regression without any toxicity.

Conclusions: In both in vivo and in vitro applications, APR nanoparticles could be targeted to recognize and enter ErbB3 positive tumor cells, and play a corresponding role by silencing targeted gene expression. APR nanoparticle is expected to become a good tumor treatment option.