骨架整合药物的反义核苷酸治疗耐药肿瘤

Combinatorial chemo and gene therapy provides a promising way to cure drug-resistant cancer since the co-delivered functional nucleic acids can regulate drug resistance genes, thus restoring sensitivity of the cells to chemotherapeutics. However, most drug delivery systems (DDSs) for combinatorial therapy still have several limitations, such as lack of precise control over drug-gene ratio, nanovehicle-induced side effects, and difficulties in sequential release genes and drugs. Herein, we propose a novel approach to synthesize a nanosized DDS using drug-integrated DNA with antisense sequences (termed “chemogene”) for curing drug-resistant cancer. As a proof of concept, floxuridine (F), a typical nucleoside analog antitumor drug, was incorporated in the antisense sequence with precise ratio to replace thymine (T) based on their structural similarity. The synthesized F-integrated antisense can be used as building units and further assembled into DNA nanogels without the usage of other delivery agent. These nanogels can responsively release F-integrated antisense in acid environment of lysosome to downregulate drug resistance genes. Thereafter, F-integrated antisense nanogels can chronic release chemotherapeutics after degradation by DNase II for cancer therapy. With the merits of self-delivery of drug and gene with precise ratio, fully biocompatible feature, and sequential release of each functional entity in a chronological manner, drug-integrated antisense nanogels are hopeful to effectively reverse the chemoresistance and achieve excellent antitumor efficacy. Our proposal will provide a promising candidate for combinatorial chemo and gene therapy of drug-resistant cancers.

化学-基因联合治疗是治疗核苷类药物耐药肿瘤的重要途径。但是现有的药物-基因输送系统难以精确控制基因、药物剂量比例，无法解决外源性载体的毒副作用，难以程序性释放治疗基因、化疗药物。本项目拟利用核苷类药物与天然核苷结构类似的特点，通过固相合成技术将药物（氟尿苷）整合进反义核苷酸中，制备得到“化疗基因”，并利用DNA纳米技术构建“化疗基因”自输送系统，避免外源性载体的使用。并利用肿瘤细胞溶酶体中的酸性环境及脱氧核糖核酸酶II（DNase II），程序性释放反义核苷酸和药物，增强协同治疗效果。上述研究系统可以精准调控药物与反义核苷酸的剂量比例，有利于阐明药物、基因剂量关系对协同治疗效果的影响。并且无需利用外源性载体，实现药物-基因自输送以减少毒副作用。该系统可以程序性释放反义核苷酸和药物，增强协同治疗效果。本项目的开展有望为核苷类药物耐药肿瘤的治疗提供新的方法，具有重要的科学价值和临床意义。

构筑高效药物输送系统是化学领域的重要研究方向之一。目前，核酸类药物递送系统主要面临递送效率低，肿瘤靶向效率低，以及药物负载率低的问题。为了提升药物输送系统的递送效率，本项目设计了精准可控的马来酰亚胺修饰的核酸类药物输送系统，可有效调节核酸类药物的亲疏水性，提升核酸类药物输送系统的递送效率及其细胞摄取效率。为了构筑高效的肿瘤靶向药物递送系统并提升药物负载率，我们设计了整合抗肿瘤药物的核酸适配体的靶向输送系统。我们通过将4种核苷类抗肿瘤药物替换适配体中天然核苷，得到基于药物的核酸适配体。该药物可以高效递送抗肿瘤药物进入肿瘤组织，并且具有100%的载药率，可以有效抑制肿瘤增殖。此外，为了提供设计纳米药物输送系统的不同策略，我们总结了纳米药物研究中的瓶颈，阐明怎样通过合理设计药物以克服相关的瓶颈，并撰写相关综述。最后，由于饮用水被氟离子污染易诱发癌症，为了预防癌症，我们开发出便携式、准确度高、特异性好的氟离子探针用于饮用水中氟离子检测。该探针具有高的灵敏性（最低检测限1.7 μM），很好的特异性（不受其他阴离子干扰），很宽的动态监测范围（0-800 μM），很快的检测响应时间（30分钟），具有较好的应用前景。上述的研究，可为设计高效药物输送系统、在生活中预防癌症提供新的思路。在本项目的资助下，我们已经在Journal of the American Chemical Society，Chemical Science， Chemical Communications，View等国际刊物发表SCI 论文4篇。在项目执行期间，协助指导博士研究生3人，其中毕业2人。