一氧化氮和吉西他滨共装载的超分子纳米载体在治疗耐药性胰腺癌上的应用及分子机制研究

Pancreatic cancer is one of the most lethal malignancies. Most of patients have tumors that cannot be surgically resected. Chemotherapy is one of the best options for pancreatic cancer treatment. However, because of the drug resistance of pancreatic cancer, chemotherapy has a very high rate of failure. In order to reverse the drug resistance of pancreatic cancer chemotherapy, this proposal focuses on the development of supramolecular prodrug nanocarriers for the co-delivery of nitric oxide (NO) and gemcitabine. Taking advantage of the “plug and play” property of supramolecular polymers, supramolecular multifunctional drug nanocarriers will be constructed by host-guest interaction of NO and gemcitabine conjugated guest molecules and Gd conjugated host molecules. The glutathione (GSH) triggered release of NO and gemcitabine will be studied. NO is expected to overcome the drug resistance in gemcitabine-resistant pancreatic cancer cells. The possible mechanism will be well studied by real-time PCR, Western Blot, and ELISA. The supramolecular prodrug nanocarriers are capable of simultaneously encapsulating and delivering NO and gemcitabine into the same pancreatic cancer cells after systemic administration to synergistically inhibit the growth of gemcitabine-resistant pancreatic tumors. The novel drug nanocarriers will provide a new strategy for more efficient treatment of pancreatic cancer.

胰腺癌是目前预后最差的实体肿瘤。化疗已成为胰腺癌治疗最常用且有效的手段之一。耐药性是胰腺癌临床化疗失败的主要原因。本项目以克服胰腺癌化疗的耐药性为目标，针对一氧化氮（NO）和吉西他滨体内传递的关键科学问题，拟利用超分子聚合物特有的“即插即用”（Plug-and-Play）特性，将谷胱甘肽（GSH）响应的长半衰期NO供体和吉西他滨共价键合到客体分子上，与负载了磁共振造影剂钆（Gd）的主体分子进行“乐高积木”式自组装，构筑具有磁共振诊断功能的超分子纳米前药载体，实现NO和吉西他滨的共传递；研究NO和吉西他滨在GSH还原环境下的药物释放增速效应；探索NO对胰腺癌化疗的增敏效应并研究其分子机制；评价不同NO和吉西他滨比例的纳米载体在抑制肿瘤细胞增殖上的协同增效作用，获得最佳“协同指数”和最好“耐药指数”；建立原位胰腺癌模型，研究超分子纳米载体的抗肿瘤效果，为耐药性胰腺癌治疗手段的突破提供新方法。

胰腺癌是目前预后最差的实体肿瘤。化疗已成为胰腺癌治疗最常用且有效的手段之一。耐药性是胰腺癌临床化疗失败的主要原因。本项目以克服胰腺癌化疗的耐药性为目标，针对一氧化氮（NO）和吉西他滨体内传递的关键科学问题，成功合成了环糊精基一氧化氮供体(α-CD-NO)和环糊精基吉西他滨前药（α-CD-GEM），并通过α-CD-GEM和α-CD-NO与PEG-PMPC的共组装，制备得到了GEM和NO共装载的超分子纳米载体。通过细胞毒性测试，发现当GEM和NO的摩尔比为1:5时联合指数最小，说明具有最好的协同效应。用耐GEM的胰腺癌肿瘤细胞株探究了纳米载体的细胞毒性，发现NO的引入能极大提高GEM的细胞毒性，更有效地促进耐药细胞的凋亡，进一步证明了NO能有效克服GEM的耐药性。我们探索了NO克服肿瘤耐药的机理，发现NO能增加线粒体的膜的通透性，从而影响线粒体的功能，能有效降低细胞内的ATP水平。同时，NO的引入能降低多药耐药相关蛋白MRP的表达，这证明了NO是通过抑制多药耐药相关蛋白MRP的表达来克服肿瘤细胞的耐药性，从而提高治疗的疗效。最后，我们通过皮下耐药肿瘤和原位胰腺癌耐药肿瘤的抑瘤实验，证明NO和GEM的联合使用显著降低了肿瘤组织内的MRP的表达，证明NO能通过抑制MRP的表达克服耐药性，有效抑制了肿瘤的生长。该研究不仅拓展了一氧化氮的生物医学应用，而且提供了克服吉西他滨引起耐药性的新方法,为胰腺癌治疗中纳米药物载体的优化设计提供科学依据。在该项目资助下，在Journal of the American Chemical Society、ACS Nano等期刊发表了17篇高水平论文，授权了两项发明专利。同时，项目负责人金桥获得了国家优秀青年科学基金的资助，并由副教授晋升为教授。该项目还培养了三位博士生和三位硕士生。