构建共载分子靶向药物及131I的新型纳米载体的策略优化研究

Some patients with differentiated thyroid cancer have poor prognosis because of occurrence of resistance to radioiodine therapy. Moreover, molecular targeted drugs have obvious side effects and might be prone to drug resistance. Our previous studies showed that 17-AAG, the prototypical HSP90 inhibitor, could restrain the proliferation of anaplastic thyroid cancer cells and induce apoptosis; BSA-PCL polymer liposomes could offer an effective nanotechnology platform for solubilization, co-loaded and targeted therapy of multiple drugs (research results have been published in Chin J Nucl Med Mol Imaging, Nanoscale, and so on). On the basis of these results, we plan to construct a new 3-in-1 BSA-PCL polymer liposomes targeting high expression of VEGF on the thyroid cancer cells’ surface, containing 131I-17-AAG and Torin2 (mTOR inhibitor). We will evaluate the dimensions, the level of drug loading, targeting, drug release kinetics and cytotoxicity of the nanoparticles (NP) to thyroid cancer cells. In addition, we shall perform preliminary animal experiments to verify the feasibility, safety and synergistic antineoplastic activity on this NP-based delivery which associating molecular targeted drugs with radioiodine. The research will combine advanced targeting nanotechnology with classic 131I therapy, investigate the feasibility and effectiveness of combination therapy of molecular targeted drugs with radionuclide.

部分甲状腺癌患者在治疗过程中出现核素治疗抵抗，而分子靶向治疗又存在毒副作用大及肿瘤耐药等问题。课题组前期研究表明，HSP90抑制剂17-AAG可明显抑制未分化甲状腺癌增殖，并可诱导其凋亡；纳米载体BSA-PCL高分子脂质体可有效实现多种药物的助溶、共载及肿瘤靶向性治疗（研究成果已发表于中华核医学与分子影像杂志及Nanoscale等杂志）。在此研究的基础上，我们拟构建一种新型的以甲状腺癌表面高表达的VEGF为靶向位点的三合一聚合纳米载体，将131I标记于17-AAG上，再与mTOR抑制剂Torin2共同包载于载体内，分析该共载纳米载体的粒径、载药量、靶向性、释药动力学及对甲状腺癌细胞的毒性作用；并建立荷瘤裸鼠模型，通过体内研究进一步分析该给药系统的可行性、安全性及协同抗肿瘤活性。本研究将先进的靶向性纳米技术与经典的131I治疗相结合，并将探讨分子靶向药物与核素联合治疗的可行性和高效性。

大多数分化型甲状腺癌（differentiated thyroid carcinoma，DTC）患者经规范的综合治疗后预后良好，但部分进展为碘难治性DTC的患者则因有效治疗手段匮乏而影响预后。分子靶向治疗虽可控制病灶进展，但又存在毒副作用大及肿瘤耐药等问题。.本研究结果显示，HSP90抑制剂17-AAG及mTOR抑制剂Torin2单独及联合应用均可明显抑制ATC细胞系FRO细胞的生长；两药浓度比为1:1、总药物浓度大于0.52μM时，联合作用指数CI＜1，二者呈现出协同抗癌作用。.本研究成功制备了包载17-AAG和Torin-2的介孔二氧化硅纳米粒，并完成了131I核素的表面标记，其标记率为66-78%，放化纯可高达98.8-99.4%。载体表面修饰Anti-VEGFR2 ab后，其细胞摄取能力增强。.体外细胞水平研究显示，分别经系列梯度浓度和/或递增放射性活度的 作用于FRO细胞后48h，核素药物纳米载体组对细胞生长的抑制率要高于其它组别（P<0.001）。.动物水平实验中，注药后1-3周，靶向组（修饰Anti-VEGFR2 ab）瘤体内放射性计数均高于非靶向组（t值分别为8.81、7.06、12.78，均P<0.05）。治疗后30天，Na131I组、对照组和非靶向组的瘤体体积变为基准体积的395.0±22.5%、405.0±24.1%和198.7±13.2%，而靶向组为基准体积的101.1±2.4%，靶向+载药组的瘤体体积减小为基准体积的94.1 ± 8.2%。生存分析曲线显示，上述各组的中位生存期分别为27、25、34、38和46天，Log-rank分析显示靶向+载药组和靶向组的中位生存期均较非靶向组延长(P分别为<0.001、0.0047)，并且靶向+载药组更为明显(P<0.001)。.本研究借助纳米载体运载两种药物并携带131I靶向作用于未分化甲状腺癌，使肿瘤细胞获得摄碘功能，同时两种药物产生协同抗肿瘤作用，开拓了不摄碘肿瘤的治疗思路。