基于可生物响应性的纳米树枝状聚合物PAMAM介导靶向性肽联合131-I对甲状腺髓样癌的治疗研究

Currently, targeting therapy for the aggressive metastatic medullary thyroid cancer (MTC) has become a major research trend. Generally, the multiple targeted treatment of tyrosine kinase inhibitors is often studied and utilized in MTC. However, its drug-related side effects are common with 56 % incidence of grade 3 side effects, which include nausea, hypertension, QT prolongation and stroke etc.. In this study, a unique therapeutic system of Peptide-131I-PAMAM(G5) against MTC will be designed and synthesized. Through in vivo and in vitro experiments, the 131I labeling rate of therapeutic system, the dynamic changes of CT, CEA, VEGF and EGF, the 131I uptake rate and apoptosis rate and protein expresssion of MTC cells, as well as the tumor targeting image and the ratio of target organs vs non-target organs will be investigated and compared before and after treatment by various methods, including HPLC, Chemoluminescence, SPECT/CT，FCM, MTT, Westen-blotting and radionuclide biodistribution technologies. We expect to elucidate the physicochemical property, stability,targeting efficency, feasibility and treatment effects of Peptide-131I-PAMAM(G5) on MTC therapy. The results will have an important scientific significance to promote the nanoparticle dendrimers into 131I application for basic research field, and it has a potential application value for the MTC treatment of the specific double targeting peptide 131I, which will provide a novel scientific basis and technical support for effective MTC treatment.

靶向性治疗是当今甲状腺髓样癌(MTC)新的研究方向和热点，目前较多以多靶点酪氨酸激酶抑制剂为研究对象，但常伴有呕吐、高血压等高达3级以上的副反应。本课题拟设计独特的Peptide-131I-PAMAM(G5)纳米核素靶向性治疗系统，结合体内外试验，应用高效液相色谱、SPECT/CT、Westen-blotting等技术，检测治疗系统131I标记率、MTC细胞摄131I率、凋亡率和蛋白表达，分析治疗前后血浆CT和VEGF等浓度的动态变化，评价肿瘤靶向显像和计算靶器官/非靶器官比值。以期阐明Peptide-131I-PAMAM(G5)的理化性质及治疗MTC的可行性、靶向性和治疗效果，研究结果对于提升生物可响应性纳米树枝状聚合物在131I基础研究领域的应用水平具有重要的科学意义，同时使得特异双靶向肽131I治疗MTC具有潜在的临床应用价值，为丰富MTC有效治疗策略提供新的科学依据和技术支持。

靶向性治疗肿瘤是当今研究的热点话题，对于甲状腺髓样癌治疗的新研究方向较多以多靶点酪氨酸酶抑制剂为研究对象，但常常会出现不良的副作用。基于此，本课题设计独特的131I标记经过修饰的纳米材料PAMAM对甲状腺髓样癌进行体内外的研究。我们通过氯胺T法成功制备了Peptide-131I -PAMAM(G5.0)纳米核素靶向系统包括131I-PAMAM(G5.0)、131I -PAMAM(G5.0)-SR、131I -PAMAM(G5.0)-GP和131I -PAMAM(G5.0)-SR-GP，并经过C18萃取柱子纯化得到上述探针,进行了各探针稳定性分析和体外、体内相关实验。结果表明：各探针的体外稳定性良好，放化纯度高。通过各探针处理体外MTC细胞后在特定的时间段对MTC细胞进行MTT检测、细胞摄取实验等试验，实验结果提示与单纯的131I比较，我们设计的Peptide-131I-PAMAM(G5.0)纳米核素靶向系统对体外甲状腺髓样癌细胞存在治疗效果。另一方面，对体内实验的研究主要通过分别在裸鼠上注射上述各探针并进行SPETC-CT显像、生物分布、血液中CT、CEA等相关分泌蛋白检测，结果提示Peptide-131I -PAMAM(G5.0)纳米核素靶向系统可靶向肿瘤，同时进行生物分布检测发现肿瘤可摄取Peptide-131I -PAMAM(G5.0)纳米核素靶向系统，但正常脏器存在对Peptide-131I -PAMAM(G5.0)纳米核素靶向系统的生理上摄取。本项目的实施使特异性双靶向肽联合131I治疗甲状腺髓样癌具有潜在的临床应用价值，丰富了甲状腺髓样癌治疗方式和方法，也为甲状腺髓样癌治疗提供新的科学依据和技术支持。