分子水平解析高分子刷RNA载体的胞内命运及其在长效沉默PD-L1中的研究

RNA类药物在临床上显示出巨大优势，但裸露的RNA分子易降解，成功的递送是其应用的关键。长效稳定的RNA递送能有效延长用药周期，提高治疗效果。聚阳离子RNA载体优势明显，应用广泛。载体的胞内命运与RNA功能的发挥密切相关。但目前该领域的研究局限于细胞器水平，无法在分子水平解释载体与胞内环境的相互作用及RNA释放的规律，严重制约RNA类药物的进一步应用。因此，本项目拟利用理化性质精准可控的高分子刷作为模型载体，通过蛋白组学等关键手段，系统分析载体与胞内生物分子的相互作用。拟提出一种基于竞争吸附的RNA释放理论，建立动力学模型，分析胞内典型生物分子对RNA释放的影响。由此在分子水平上解析RNA载体的胞内命运。最后以基于PD-L1的肿瘤免疫治疗为应用案例，用优化的载体长效沉默PD-L1的表达，以解决单抗类药物剂量大、效率低等困境，为RNA类药物在肿瘤免疫治疗等生物医学领域的应用提供基础和思路。

RNA therapeutics have shown great promise in clinical applications. The development of appropriate RNA delivery systems is crucial as naked RNA is susceptible to degradation by RNases. Long-term RNA delivery enables reducing drug dose and enhancing therapeutic effect. Amongst the range of delivery systems, polycationic vectors are particularly attractive and widely used. The function of RNAs is directly regulated by the intracellular fate of vectors. Current studies on cell fate of vectors are limited at organelle level, whilst the interaction between vectors and the biomolecules in cells and the release mechanism of RNAs from vectors at molecular level are poorly understood. These limitations hinder the further applications of RNA therapeutics. Hence, in this project, we aim to use polymer brush-based vector with precise control over the physicochemical properties as model vector for understanding the interaction of vectors and cell microenvironment at molecular level via proteomics etc. We also propose a competitive binding mechanism and develop a kinetic model for quantifying the contribution of different classes of molecules to RNA intracellular release. Eventually, we will optimize the vector and apply to long-term PD-L1 silencing, which provides alternatives to monoclonal antibody drugs for less dose and enhanced therapeutic effect in cancer immunotherapy. We believe this project will offer theoretical support and new paradigm for cancer immunotherapy and other biomedical applications of RNA therapeutics.