肿瘤相关成纤细胞酯酶响应阳离子聚酯载体用于胰腺癌基因治疗

Pancreatic cancer is a lethal disease with abundant cancer-associated-fibroblasts (CAFs) and extracellular matrix, which restrict the delivery of therapeutics to cancer cells. Cell death of fibroblasts caused by chemotherapy will lead to drug resistance and metastasis. Gene therapy has its own benefits for cancer treatment. Compared with virus, non-viral gene delivery system is safer and easier to produce. However, the transfection efficacy needs to be improved. In this project, the esterase-responsive cationic polyester library will be parallelly synthesized and screened for effective CAF-targeted gene transfection with low toxicity. Two therapeutic genes will be applied, TRAIL and HYAL1. The bystander effect and selective cytotoxicity of TRAIL could offer specific killing of tumor cells. The expression of HYAL1 can improve the penetration of drugs in tumor tissues. We will develop a novel polymeric gene delivery system targeting the fibroblast-enriched microenvironment in pancreatic cancer and evaluate the transfection efficacy and antitumor activity in vitro and in vivo. In addition, we aim to find out the relationships between structure characterizations of cationic polyesters (hydrophobicity-hydrophilicity, charge density and amine on the side chain) and the decisive factors for transfection (cytotoxicity, encapsulation and release of DNA, nuclear entry, transcription and translation).

胰腺癌生存率极低，其显著特征是肿瘤细胞被大量激活态成纤细胞及基质包围，导致药物难以输送。而化疗药物杀死成纤细胞会导致肿瘤耐药及转移。肿瘤的基因治疗已展现出独特的优势。相比病毒基因载体，非病毒载体的安全性高并易于生产，但转染效率有待提高。本项目针对胰腺癌的病理特点，采用平行合成技术及筛选优化策略设计合成可被肿瘤成纤细胞高活性酯酶水解的阳离子聚酯基因载体，实现胰腺癌成纤细胞中的高效低毒基因转染。载体将同时装载TRAIL和HYAL1基因，TRAIL的旁观者效应和选择性可使其只杀死肿瘤细胞，HYAL1的表达会提高载体在肿瘤部位的渗透。本项目不仅将胰腺癌富含成纤细胞的不利微环境转化为基因输送的有利媒介，开发新型高分子基因输送系统并考察体内外转染效率与抗癌活性，还将研究阳离子聚酯的结构特点（亲疏水性、电荷密度及侧链胺）与转染关键因素（细胞毒性、DNA包载及响应性释放、入核、转录及翻译等）的关系。

胰腺癌生存率极低且缺乏有效的治疗手段。本项目针对胰腺癌的病理特点，采用平行合成技术设计合成及筛选获得可高效转染激活态胰腺成纤维细胞的阳离子聚合物材料，实现针对胰腺癌成纤细胞的高效低毒基因转染，为胰腺癌的基因治疗奠定研究基础并提供非病毒递送材料。研究发现枝状聚乙烯亚胺包裹的质粒DNA能够选择性转染胰腺星状细胞而不是肿瘤细胞和其它成纤维细胞。在胰腺星状细胞中高表达的成纤维生长因子受体赋予该细胞更高的吞噬该纳米复合物的能力。该递送系统负载编码肿瘤坏死因子配体TRAIL的质粒DNA，利用胰腺癌微环境中成纤维细胞的高富集以及TRAIL的旁观者效应，有效的实现了胰腺肿瘤细胞选择性杀伤，而对非癌变细胞无明显毒性。在富含成纤维细胞的胰腺癌原位肿瘤模型中验证了该治疗策略的有效性。更重要的是，这一基因治疗策略将原本作为肿瘤微环境中阻碍药物递送的成纤维细胞障碍，转变为肿瘤杀伤蛋白的生产者和存贮站。此外，获得名为“一种基于细胞周期调控增强高分子聚合物载体基因转染效率的方法”的发明专利一项，并成功转让给生物公司用于开发转染试剂盒。