新型可降解纳米载体介导RNAi靶向治疗胰腺癌的实验研究

Pancreatic cancer is one of the deadliest solid tumors throughout the world. Currently efficient therapy is rarely available. The application of small interfering RNA (siRNA)-based RNA interference (RNAi) for pancreatic cancer gene therapy has attracted great attention. However, the application of RNAi faces great challenge for lacking of safe and efficient carriers. In our previous work, cationic poly (lactic acid) (CPLA)-based degradable nanocapsules have been synthesized and utilized as novel carriers of siRNAs for effective gene silencing. In this proposal, we are going to develop new carriers with tumor-targeting property by modifying the previous nanoparticles, and deliver siRNA targeting the mutant K-Ras oncogene to pancreatic cancer cells for gene therapy. In vitro cell studies and in vivo small animal tumor model will be used to analyze the delivery abilities of the nanocapsules. Tumor growth suppression effect of the nanocapsule-siRNA complex will be monitored and analyzed. Also, the biocompatibility and biosafety of the nanocapsules will be evaluated. In this multidisciplinary project, we will combine the advantages of nanotechnology medical science to assess the feasibility of using siRNA based RNAi for pancreatic cancer gene therapy systematically. We expect that this project will provide a new therapeutic strategy for the treatment of pancreatic cancer.

胰腺癌是当前预后最差的实体恶性肿瘤之一，尚无有效治疗手段。 siRNA为基础的RNA干涉技术在胰腺癌基因治疗中进展显著，但仍缺乏安全有效的转运载体。本项目以申请人在前期工作中已成功制备的具有高效转运效率的可降解性聚乳酸阳离子纳米转运载体为基础，拟对其结构和性能进行进一步的修饰及优化改进，构建新的具有靶向性能的纳米载体，以胰腺癌中广泛存在的原癌基因K-Ras为治疗靶点，开展胰腺癌的基因干涉治疗研究。项目将利用人胰腺癌细胞体外模型和小动物移植瘤体内模型，分析新纳米载体对siRNA的靶向转运能力，在此基础上深入研究纳米载体-siRNA复合物对胰腺癌的抑瘤效应及机制，同时评价其在动物体内的生物安全性。通过以上几个方面的研究，我们将系统评估基于siRNA的基因干涉在胰腺癌治疗中的可行性，并期望利用纳米技术及医学学科交叉合作的优势为胰腺癌的生物治疗提供一种新的方法。

由于缺乏小干扰siRNA的有效运载体系，RNAi为基础的肿瘤基因治疗的临床应用受到了制约。在该项目中，我们使用可降解纳米载体运载K-Ras siRNA进行胰腺癌治疗的体内外实验研究。体外实验结果表明，可降解纳米载体可以通过静电作用和K-Ras siRNA形成稳定纳米复合物，该纳米复合物在两种胰腺癌细胞株中均有很高的转染效率能有效抑制胰腺癌细胞的增殖。体内实验结果表明，K-Ras siRNA纳米复合物能够持续富集在肿瘤组织达72小时以上。肿瘤组织K-Ras mRNA和蛋白表达水平下降约50%左右。经治疗后，肿瘤组织生长延缓，肿瘤浸润现象减少，肿瘤组织凋亡增加。此外，动物毒性研究表明，10倍治疗剂量的纳米载体是安全低毒的，提示该纳米载体运载siRNA治疗胰腺癌具有很好的应用潜能。