Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
Molecules. 2021 Feb 18;26(4):1067. doi: 10.3390/molecules26041067.
Blocking the PD-1/PD-L1 pathway can diminish immunosuppression and enhance anticancer immunity. PD-1/PD-L1 blockade can be realized by aptamers, which have good biocompatibility and can be synthesized in quantity economically. For in vivo applications, aptamers need to evade renal clearance and nuclease digestion. Here we investigated whether DNA nanostructures could be used to enhance the function of PD-L1 aptamers. Four PD-L1 aptamers (Apt) were built into a Holliday Junction (HJ) to form a tetravalent DNA nanostructure (Apt-HJ). The average size of Apt-HJ was 13.22 nm, which was above the threshold for renal clearance. Apt-HJ also underwent partial phosphorothioate modification and had improved nuclease resistance. Compared with the monovalent PD-L1 aptamer, the tetravalent Apt-HJ had stronger affinity to CT26 colon cancer cells. Moreover, Apt-HJ markedly boosted the antitumor efficacy in vivo vs. free PD-L1 aptamers without raising systemic toxicity. The results indicate that multiple aptamers attached to a DNA nanostructure may significantly improve the function of PD-L1 aptamers in vivo.
阻断 PD-1/PD-L1 通路可以减弱免疫抑制作用，增强抗癌免疫力。适体具有良好的生物相容性，可以经济地大量合成，可用于实现 PD-1/PD-L1 阻断。对于体内应用，适体需要逃避肾清除和核酸酶消化。本研究探讨了 DNA 纳米结构是否可用于增强 PD-L1 适体的功能。将四个 PD-L1 适体（Apt）构建成霍利迪连接（HJ），形成四价 DNA 纳米结构（Apt-HJ）。Apt-HJ 的平均大小为 13.22nm，超过了肾清除的阈值。Apt-HJ 还进行了部分硫代磷酸酯修饰，具有更好的耐核酸酶性。与单价 PD-L1 适体相比，四价 Apt-HJ 与 CT26 结肠癌细胞的亲和力更强。此外，与游离 PD-L1 适体相比，Apt-HJ 显著提高了体内抗肿瘤疗效，而没有增加全身毒性。结果表明，多个适体连接到 DNA 纳米结构上可以显著提高 PD-L1 适体在体内的功能。
