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。

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.