近红外光时序控释的基因-药物共输送纳米体系用于靶向治疗肝癌的研究

Co-delivery of gene therapy and chemotherapy components could significantly improve the cancer therapeutic outcomes, while it is very difficult to precisely control the release order of the gene therapy components and the chemotherapy drugs, which might led to insufficient synergistic effects. Here, we will design “Yolk-Shell” structured nanocages as NIR laser controlled siRNA/ doxorubicin co-delivery carriers, which could release different components depending on the wavelength of irradiation laser, and further apply this nanocage in the targeted therapy of hepatocellular carcinoma (HCC). The nanocage has a mesoporous silica shell modified with block copolymer (coumarin-poly[2-(N,N-dimethylaminoethyl) methacrylate]-polyethylene glycol-folic acid (Cou-PDMAEMA-PEG-FA)) on its surface. As a polycation with low toxicity and high buffer capacity, PDMAEMA can bind the siRNA which would silence the gene expression of multidrug resistance proteins to improve the drug sensitivity of chemotherapy drugs, while PEG would improve the stability of the nanocages under physiological conditions, and FA would help the nanocages target to the HCC cells via ligand-receptor mediated interactions. The 800 nm NIR laser irradiation can effectively drive the photolysis of the "Cou" to trigger the release of siRNAs along with the PDMAEMA-PEG-FA from the silica shell, which then could down-regulate the gene expression of drug resistance protein MDR-1 and increase the sensitivity of cancer cells to chemotherapy drug. The nanocage has upconversion nanophosphor (UCNP) as a core, which could produce UV emission under 980 nm laser irradiation. Then, the UV light can induce the photolysis of caged hydrophobic prodrug, and trigger the release of doxorubicin to kill the cancer cells. Therefore, the utilization of two distinct wavelengths of NIR laser (980 nm and 800 nm) could regulate the controlled sequential release of siRNA and doxorubicin at different time points, which is benefit to take full advantages of their synergistic therapeutic effects against HCC.

基因/药物共输送可提高肿瘤治疗效果，但两者在肿瘤部位的释放次序无法精确调控，不能充分发挥协同作用。本课题拟构建具有近红外光时序响应控释功能的纳米复合物作为siRNA/阿霉素的共输送载体，并将其用于靶向治疗肝癌的研究。复合物外壳由介孔二氧化硅构成，表面修饰嵌段共聚物Cou-PDMAEMA-PEG-FA；PDMAEMA作为聚阳离子可络合抑制耐药基因表达的siRNA，PEG提高生理稳定性，FA作为靶向基团可介导复合物与癌细胞高效结合。在800 nm光照射下，Cou（香豆素）发生光解驱使siRNA从壳层中脱落，发挥基因沉默作用来提高癌细胞对阿霉素的敏感性。内核由上转换材料构成，在980 nm光照射下发出紫外光切断填充在空腔中的阿霉素前药分子，使阿霉素从中释放出来，达到化学治疗的目的。在本研究中分别给予800和980 nm的激光照射，可实现siRNA和阿霉素在细胞内的可控时序释放，充分发挥协同疗效。

针对目前肿瘤化疗中普遍存在的化疗药物靶向性不强、毒副作用大、易诱发肿瘤细胞产生多药耐药性等缺点，本项目开发了一系列具备肿瘤内源性环境和外界物理刺激的智能响应性纳米递送系统，旨在提高癌症治疗的精准性、可控性和多种治疗方式的协调性。我们利用光活化技术，一方面在化疗和基因联合治疗中，通过时空调控实现了目的基因和化疗药物在肿瘤细胞内的时序释放，另一方面我们提高了基因和光动力协同治疗的可控性。并在体外细胞和动物肿瘤模型中，进一步阐明了时序递送、光控精准治疗对治疗协同增效的重要性，有望为临床上肝癌的低毒高效治疗提供新思路。开展的主要工作如下：（1）构建了一种具有双波长光时序响应控释功能的氧化硅纳米材料作为P-gp shRNA和阿霉素的共输送载体，通过“定点、定时、定速”释放来逆转肿瘤耐药性，优化两者的协同抗肝癌效果；（2）以上一部分的光响应氧化硅材料为基质，递送凋亡基因（Caspase-8）和光敏剂Ce6，将光活化控制肿瘤治疗的策略进一步拓展，实现其他功能基因（Caspase-8）和光动力联合治疗，提升基因和光动力联合治疗的精准可控性；（3）使用FDA批准的PLGA代替氧化硅材料作为基质，构建了肿瘤内源性微环境GSH控制siRNA释放和外源性光照刺激响应阿霉素释放的双敏感基因/药物递送系统，证明时序释放策略在除肝癌外的其他肿瘤（乳腺癌）模型中可以同样可以优化两者的协同抗肿瘤效果。综上所述，本项目利用光活化技术，将光响应性策略引入纳米递送系统，提高肿瘤化疗、基因治疗、光动力治疗等治疗手段时空可控性和精准性，实现多种治疗方式的有机协同，显著提升了肿瘤治疗疗效。