Department of Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University , University Town, Guangzhou, People's Republic of China 510006.
Biomacromolecules. 2013 Jun 10;14(6):1777-86. doi: 10.1021/bm400177q. Epub 2013 May 9.
Short interfering RNAs (siRNAs) as chemotherapeutic RNAi agents hold great promise for a significant improvement in cancer therapy. Despite the promise, effective transport of siRNA with minimal side effects remains a challenge. The common problem associated with the low delivery efficiencies of current polycation-based gene delivery systems is their low stability in the presence of salt and serum. In the present study we developed the polyglutamate derivatives (PGS) polyelectrolyte brushes for NF-κB p65 siRNA delivery. The PGS polyelectrolyte brushes/siRNA polyplex was colloidally stable (150 nm diameter) in physiological saline (150 mM NaCl), likely due to the osmotic brushes of PGS. The size-controlled siRNA/PGS polyplex also showed the serum resistance resulting in their efficient cellular uptake was not negatively influenced by the presence of serum. The endothermic profile of ITC, their low values of Gibbs free energy and binding constants Kb under salt conditions provided the direct evidence that PGS polyelectrolyte brushes had a much lower binding affinity for serum proteins, compared with PEI 25KDa. PGS polyelectrolyte brushes delivering NF-κB p65 siRNA achieved efficient down-regulation of NF-κB p65 protein in HeLa cells. The NF-κB p65 down-regulation mediated by PGS polyelectrolyte brushes was more significant than PEI 25KDa and comparable to Lipofectamine 2000. Furthermore, the combination treatment with PGS polyelectrolyte brushes/NF-κB p65 siRNA polyplex and doxorubicin demonstrated synergistic apoptotic and cytotoxic effects on HeLa cancer cells. The high stability in physiological saline and salt-induced serum resistance of PGS polyelectrolyte brushes/siRNA polyplex has potential applications together with standard chemotherapies such as doxorubicin to be a viable method to improve the clinical outcomes in cancer therapies.
短干扰 RNA（siRNA）作为化学治疗 RNAi 剂，在癌症治疗中具有显著改善的巨大潜力。尽管有希望，但具有最小副作用的 siRNA 的有效转运仍然是一个挑战。目前基于聚阳离子的基因传递系统的低递送效率的常见问题是它们在盐和血清存在下的低稳定性。在本研究中，我们开发了聚谷氨酸衍生物（PGS）聚电解质刷用于 NF-κB p65 siRNA 递送。PGS 聚电解质刷 / siRNA 聚集体在生理盐水中（150 mM NaCl）具有胶体稳定性（150nm 直径），可能是由于 PGS 的渗透刷。尺寸控制的 siRNA / PGS 聚集体也表现出对血清的抗性，因此其有效的细胞摄取不受血清存在的负面影响。ITC 的吸热谱，它们在盐条件下的 Gibbs 自由能和结合常数 Kb 的低值提供了直接证据，表明与 25 kDa 的 PEI 相比，PGS 聚电解质刷对血清蛋白的结合亲和力要低得多。PGS 聚电解质刷递送至 HeLa 细胞中的 NF-κB p65 siRNA 可有效下调 NF-κB p65 蛋白。PGS 聚电解质刷介导的 NF-κB p65 下调比 25 kDa 的 PEI 和 Lipofectamine 2000 更显著。此外，与 PGS 聚电解质刷 / NF-κB p65 siRNA 聚集体和阿霉素的联合治疗对 HeLa 癌细胞表现出协同的凋亡和细胞毒性作用。PGS 聚电解质刷 / siRNA 聚集体在生理盐水中的高稳定性和盐诱导的血清抗性具有与多柔比星等标准化疗相结合的潜在应用，以成为改善癌症治疗临床结果的可行方法。
