Abstract 3701: Targeted Bcl2 siRNA delivery using DNA nanoparticles in cancer therapy
Authors: Rahman Mohammad Aminur , Wang Pengfei , Wang Dongsheng , Nannapaneni Sreenivas , Hurwitz Selwyn J. , Chen Zhuo G. , Ke Yonggang , Shin Dong M. 
Published: August 2018

Background: Short interfering RNA (siRNA), highly capable of knockdown of specific genes, has emerged as a promising molecular therapeutic tool in targeted cancer treatment. Nonetheless, only limited success has been achieved in the systematic administration of siRNA. Therefore, the lack of a robust and versatile siRNA delivery system is a critical issue in translating this therapeutic tool for cancer treatment. Recent development in DNA nanotechnology has made programmable DNA nanoparticles (DNPs) a potent drug delivery platform. Rationally designed DNPs have emerged as facile delivery vehicles since their physicochemical properties can be precisely controlled compared to other delivery systems. This study focuses on the development of tumor targeted novel DNP-based siRNA delivery system to knockdown Bcl2 gene, as a targeted cancer therapeutic.

Methods: Structural DNA technology was applied to design a library of DNPs with different sizes and shapes. Flow cytometry, confocal imaging, and transmission electron microscopy (TEM) were utilized to study the cellular internalization of DNPs. The efficacy of Bcl2 knockdown by DNP-siBcl2 and the resulting influence on cell growth and progression were assessed in cancer cells (in vitro) and in mice bearing corresponding tumor xenografts (in vivo).

Results: The correlation between DNPs design (size, shape, tumor-targeting) and internalization efficiency in different cancer cell lines remains elusive. We investigated the cellular uptake of different sizes and shapes of DNPs with or without aptamer (nucleolin targeting molecule) in multiple human cancer cell lines. The cellular uptake efficiency of DNPs was influenced by targeting ligand, size, shape, and cell line. We observed distinct stages of the internalization process of a gold nanoparticle (AuNP)-tagged DNP, using high-resolution TEM. This study provides detailed understanding of cellular uptake and intracellular trafficking of DNPs in cancer cells. Anti-cancer therapeutic potential of siBcl2 delivered by DNPs were studied in mice bearing DMS53 tumor xenografts. Significant tumor growth inhibition was observed in mice treated with DNPs-siBcl2 (5 mg/kg or 10 mg/kg, IV) relative to vehicle alone and naked siBcl2. No toxicity was observed by pathologic examination of lung, liver, kidney, heart, brain, or spleen.

Conclusions: Our study offers new insights for future optimization of DNP-based drug delivery systems for cancer therapy. Our novel aptamer conjugated DNP formulations demonstrated substantial cellular internalization. Targeting Bcl2 and its downstream signaling intermediaries reduced cellular growth. We validated the strategy of silencing of Bcl2 using DNPs in order to inhibit cancer progression in vivo. We believe that the DNPs and methodologies developed in this project will be applicable to knockdown of Bcl2 and other gene targets and may be an excellent platform to apply in future anti-cancer therapy.

Citation Format: Mohammad Aminur Rahman, Pengfei Wang, Dongsheng Wang, Sreenivas Nannapaneni, Selwyn J. Hurwitz, Zhuo G. Chen, Yonggang Ke, Dong M. Shin. Targeted Bcl2 siRNA delivery using DNA nanoparticles in cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3701.