microRNA 干扰联合热疗的金纳米笼肝肿瘤靶向控释治疗和成像研究

Our previous work about gene therapy for liver cancer has shown that we should make an intensive study of eligible gene carrier. The gene carrier should be able to unite gene therapy and thermotherapy efficiently. ..Oncogenic microRNA-181b that is upregulated markedly in human primary HCCs and mouse models of HCC, is a potential therapeutic target in HCC. The level and activity of microRNA-181b can be inhibited specifically by microRNA interference (miRNAi)..In this study, a novel and efficient gene delivery system, pegylated immuno- thermally-responsive Au nanocages (PITR-AuNCs) will be developed. Encapsulation of therapeutic gene with PITR-AuNCs will selectively target human HCCs by a murine anti-human insulin receptor monoclonal antibody (HIRMAb) 8314. ..First, stability of PITR-AuNCs and their release profile of gene under conventional heating and near-infrared light (NIR) will be studied, and their normal hepatic cell-specific cytotoxicity and inhibition of HCCs will be evaluated in vitro..Next, their liver HCCs-specific therapeutic effect, property of photoacoustic tomography, and possible toxical effect for normal liver and other main organs will be studied by intravenous injection (i.v.)...Finally, we will compare the liver HCCs-specific inhibition by thermotherapy only and the combinational thermotherapy and gene therapy for discussing the cooperativity and molecularbiological mechanism of combinational gene therapy and hyperthermia. The aforementioned research tasks will provide new ideas and theoretical basis for multidisciplinary liver cancer treatment.

我们在肝癌基因治疗的研究中发现，研制适宜载体，将基因治疗与热疗有效结合是一个颇具前景的研究课题。以肝癌细胞高表达的microRNA-181b为靶标，采用microRNA干扰技术 (miRNAi) 抑制microRNA-181b 的水平和活性；以一种新的PEG 修饰的免疫热敏金纳米笼为载体，荷载治疗基因，由金纳米笼上的小鼠抗人胰岛素受体的单克隆抗体将金纳米笼转运到人肝癌细胞内。在体外研究金纳米笼的稳定性和热敏条件下的释药特性，研究金纳米笼对肝癌细胞生长的抑制作用和对正常肝细胞的毒副作用。通过静脉注射途径，研究金纳米笼对肝癌的靶向性治疗作用及其体内肿瘤部位成像特性，研究对正常肝脏及其它主要器官可能的毒副作用。通过比较金纳米笼介导的热疗，以及它所介导的热疗联合基因治疗对肝癌细胞的抑制效果，探讨基因治疗联合热疗的协同性及其可能的分子生物学机制，为肝癌综合治疗提供新思路和理论依据。

功能化金纳米笼具有靶向递送基因药物并能将热疗和基因治疗有效结合，从而对肝癌起到综合治疗的潜力。本研究以具有光热转换特性和中空多孔的金纳米笼作为药物转运的载体，并对其进行表面修饰使其具有肿瘤靶向性。利用近红外激光照射金纳米笼产生的热和其携带的抗癌药物（可同时荷载基因药物和化学药）杀伤肿瘤细胞，考察他们的协同效应，建立具有热疗特性、肿瘤靶向的药物转运载体。研究了不同粒径的功能化金纳米笼载体的肿瘤靶向性和成像特性；分别用肝肿瘤靶向性的A54多肽分子或叶酸对该药物载体进行修饰，以肝癌细胞和荷肝癌模型鼠考察其靶向性，激光共聚焦荧光显微镜考察其体内分布。研究功能化金纳米笼载体在近红外激光照射下产生热及对肿瘤细胞的影响。体外以上升温度和细胞生存率为指标，体内以裸鼠瘤体积大小和生存时间为考察指标，综合评价该体系肿瘤治疗的最佳条件及其热疗和基因治疗或化疗的协同效应。结果表明金纳米笼载体的粒径大小和表面修饰都是影响其体内分布的关键因素，所构建的功能化金纳米笼是低毒高效的基因递送载体，其本身的热疗和基因治疗或化疗的联合显著改善了肿瘤治疗效果。本研究在肿瘤的诊疗一体化及综合治疗方面取得了一些创新性研究成果，为肿瘤治疗提供了新的思路和理论依据。