神经肽Y1受体介导及可时序释放的纳米给药系统的构建及逆转肿瘤耐药研究

Multidrug resistance is the key problem to be addressed urgently in clinical cancer chemotherapy. Improving the tumor-targeted delivery of chemotherapuetic drug and using chemosensitizer are effective methods to solve the above problem, but how to controll the temporal release of drugs are key problems to be solved. Our preliminary results show that the resistance of tumor against docetaxel can be reversal by curcumin and the sequence of administration of curcumin could significantly affect its ability of reversal drug resistance, besides, using nanotechnology could significantly improve the tumor-targeted of curcumin. In this project, a Neuropeptide Y1 receptor mediated active targeting and temporally controlled nanoscale drug delivery system (NDDS) was designed and prepared by conjugating docetaxel to polyethylene glycol, and then encapsulating curcumin.This NDDS could active target to drug resistant breast cancer cell through the specific binding of target molecules called neuropeptide analogs (PNBL-NPY) in the surface of NDDS with the high expression of neuropeptide Y1 receptor in cancer cells. And this NDDS enable a temporal release of two drugs: encapsulated curcumin was reseased firstly, while conjugated docetaxel was released slowly. The NDDS designed in this project may provide new ideas and methods to overcome the problems of lower anticancer effect and higher toxicity of chemotherapy induing by nonspecific uptake of chemotherapuetic drugs, the leak of drug before reaching the target site of NDDS and chemotherapuetic drugs after effluxing reach the not-targeted sites. The project is expected to build an active targeting and temporally controlled drug released all-in-one NDDS and lay the foundation for future clinical safe and effective treatment of drug-resistant tumors.

多药耐药是临床化疗亟待解决的关键问题，增强药物的肿瘤特异靶向性同时抑制多药耐药是解决上述问题的有效途径，其关键是如何控制药物释放的时序性。我们前期研究表明：姜黄素能够逆转肿瘤对多西他赛的耐药，且给药顺序影响其耐药逆转效果；纳米技术能提高姜黄素的被动肿瘤靶向性。基于上述研究，本项目拟采用PEG修饰多西他赛形成两亲性轭合物，然后包裹姜黄素，通过自组装构建一可按时间先后释放药物的纳米给药系统；并进一步将特异靶向乳腺癌细胞上高度表达的神经肽Y1受体的活性靶分子——神经肽类似物修饰纳米给药系统，获得特异靶向且能时序释放的功能纳米给药系统。课题将系统探讨解决化疗药非特性摄取、纳米给药系统未到达靶点之前的药物泄漏、耐药细胞内化疗药物被外排到达非靶部位等导致疗效减弱、毒性增大问题的思路和方法。本项目有望构建一种集主动靶向和时序释药功能于一体的新型纳米给药系统，为将来临床更安全、有效地治疗耐药肿瘤打下基础。

肿瘤是人类最大杀手之一。虽然化疗对肿瘤有一定的治疗效果，但是临床化疗效果受到多方面的影响。化疗药物的非选择性导致对正常组织和细胞也会造成杀伤，引起十分严重的毒副作用，如临床一线抗癌药物紫杉醇会引起骨髓抑制、室性心律不齐等毒副作用、并可引起严重的过敏反应；阿霉素会引起非常强烈的心脏毒性。更为严重的是，长期使用化疗药物会导致肿瘤细胞产生耐药性，这是导致癌症临床治疗失败的重要原因。据统计，癌症死亡病例中有90%以上的病人其肿瘤细胞存在耐药现象。因此，克服肿瘤细胞对化疗药物产生的耐药性及促进化疗药物的高效低毒，对恶性肿瘤患者化疗的疗效及预后至关重要。. 本研究基于当前肿瘤高度耐药的严峻形势及肿瘤耐药机制的复杂性，将纳米给药系统的肿瘤靶向作用和耐药逆转的化疗增敏作用有机结合，旨在构建具有逆转肿瘤耐药和肿瘤靶向作用的纳米给药系统用于治疗耐药肿瘤，本项目成功构建了神经肽Y1受体介导即神经肽类似物修饰的时序释放药物的纳米给药系统，与游离药物相比，该纳米给药系统能够增强对耐药乳腺癌MCF-7/ADR 细胞的抑制率和对MCF-7/ADR 细胞皮下移植瘤动物模型肿瘤生长的抑制。初步的研究表明，该纳米给药系统能够抑制耐药乳腺癌MCF-7/ADR 细胞中P-gp的表达。此外实验结果表明所构建的PBL-NYP-PEG-DTX纳米给药系统，在细胞水平上具有抑制4T1小鼠乳腺癌干细胞的效果。本项目制备出的集时序释放与主动靶向于一体的纳米给药系统，为将来临床上更安全、有效地治疗耐药肿瘤夯实基础。