FRα靶向共载siDNA-DBT/甲氨蝶呤的阳离子纳米胶束对鼻咽癌的放疗增敏作用及机制研究

Irradiation resistance is an important cause of local recurrence and distant metastasis of nasopharyngeal carcinoma. The new biological radiotherapy sensitizer Dbait (siDNA-DBT) can effectively enhance the radiosensitivity of nasopharyngeal carcinoma CNE1/R cell line, but it still needs further study that how to deliver it into the tumor tissue. We has proved that folate receptor (FRα) overexpressed specifically in the irradiated nasopharyngeal carcinoma tissue, which could be used as a suitable delivery target. At the same time, we have previously synthesized mulfunctional material MTX-PEG-DSPE, which could not only targete FRα site in tumor tissue, but also implement chemotherapy by MTX. Thus, we intend to construct Dbait-loaded targeted cationic micelles(M-DBT-MTX) using MTX-PEG-DSPE and cationic lipid DOTAP for the treatment of nasopharyngeal carcinoma, in order to achieve the effect of radiosensitization and chemotherapy. At the same time, the physical and chemical characterization, drug release, transfection and resistance reversal efficiency, in vivo safety and tissue distribution, anti-tumor activity and its mechanism of M-DBT-MTX would be studied. Research would provide a new method for improving radiotherapy effect of nasopharyngeal carcinoma or other tumors.

辐照抗性是鼻咽癌局部复发和远处转移的重要原因，临床尚缺乏有效治疗手段。新一代生物放射增敏剂Dbait（siDNA-DBT）可有效增强辐照抗性鼻咽癌CNE1/R细胞的放射敏感性，但如何将其靶向递送至肿瘤组织仍需进一步研究。课题组前期已证实叶酸受体（FRα）在辐照抗性鼻咽癌组织中特异性表达，可作为合适的递送靶点。同时我们已合成的功能材料MTX-PEG-DSPE不仅可靶向肿瘤组织中的FRα位点，且可同时对肿瘤组织实行甲氨蝶呤（MTX）化疗。故我们拟利用此材料及阳离子脂质DOTAP构建包裹Dbait因子的阳离子胶束（M-DBT-MTX），实现Dbait的体内鼻咽癌靶向输送，以期达到放疗增敏、同步化疗的目的。同时还将对M-DBT-MTX的理化表征、药物释放、细胞转染和抗性逆转效率、体内安全性与组织分布、抗肿瘤活性及作用机制等进行研究。旨在为提高鼻咽癌及其它恶性肿瘤的放疗效果提供一种新的方法与思路。

鼻咽癌复发与转移的很重要原因之一是放疗耐受，临床还未出现有效逆转手段。课题组前期发现Dbait这种生物放射增敏剂，可有效提高放疗照抗性鼻咽癌CNE1/R细胞的放射敏感性，将其载入纳米载体材料递送至抗性肿瘤组织可以在体内外改善放疗耐受。因此，课题组利用前期叶酸受体（FRα）靶向材料MTX-PEG-DSPE，合成了辐照鼻咽癌组织的阳离子胶束M-DBT-MTX。本研究测定该纳米载体的粒径100nm、电镜均一等性质表征，及其90%以上的核酸包封率。本项目还对其体内外转染效率与放射增敏信号通路（γ-H2AX等）作用及靶向效率评价，深入探讨其靶向放疗增敏作用机制。此外，本项目还通过考察靶向性M-DBT-MTX的体内代谢分布与急性毒性器官损伤等实验，证明本项目载体能够安全无毒用于临床前动物研究。在动物鼻咽癌模型上，与对照组相比，M-DBT-MTX显示出良好的抑瘤效率（p<0.05；n=5）。因此，本课题研究实现Dbait的放疗耐受鼻咽癌的靶向输送，达到改善放疗、同步化疗的目的，有望为抗性、复发转移性HNSCC的临床治疗提供一种新的有效策略。