131I标记单链TSH治疗失分化甲状腺癌的基础研究

Patients with radioiodine-refractory de-differentiated thyroid carcinoma (dDTC) have high mortalities. Unfortunately, there is lack of effective therapeutic methods for treating this disease yet. Although the expressions of sodium/iodide symporter and thyroid peroxidase are silent in dDTC cells, most dDTC cells express thyroid stimulating hormone receptor (TSH-R) to some extent in that the thyroxine is used to limit the progression of patients with dDTC clinically. Several studies have demonstrated that the single-chain thyroid stimulating hormone (scTSH) has much stronger bioactivity compared to the heterodimeric TSH. Based on the high binding specificity between ligand and receptor, it is assumed that the scTSH could be utilized as a carrier for targeted therapy of dDTC. In this study, we will construct the scTSH by using overlapping polymerase chain reaction and radiolabel scTSH with radioiodine 131I (131I-scTSH). Then the safety and efficacy of 131I-scTSH will be observed in therapy of dDTC. To our best knowledge, none has utilized TSH to treat malignancies. Therefore, the current study is novel.

对放射碘抵抗的失分化甲状腺癌（dDTC）病死率较高，目前尚缺乏治疗dDTC的有效手段。尽管钠/碘同向转运体及甲状腺过氧化物酶在dDTC细胞表达沉默化，但多数dDTC仍表达有促甲状腺激素受体（TSH-R）并可有效的结合促甲状腺激素（TSH），这是临床利用甲状腺素减缓dDTC患者病情进展的分子学依据。研究显示，单链TSH较野生二聚体化的TSH具有更强的生物学活性。依据受体-配体结合的特异性，如以scTSH为载体，可靶向性治疗dDTC。本研究将利用重叠延伸聚合酶链式反应技术构建scTSH，并进行131I标记（131I-scTSH），体、内外观察131I-scTSH治疗dDTC的有效性及安全性。据我们所知，国内、外尚未无利用TSH治疗恶性肿瘤的报道，本课题具有一定的创新性。

失分化甲状腺癌（de-differentiated thyroid cancer, DTC) 病死率较高，严重威胁患者生命，寻找新的治疗方案，是目前迫切需要解决的问题。从临床角度来看，高血清甲状腺球蛋白、治疗活度131I显像阴性及具有影像学可测量大小的病灶，应是特征性的dDTC。本项目从临床随访中纳入了出现上述征象的甲癌患者，分离、培养了其手术切除的复发、转移灶，建立了dDTC细胞株，并利用甲基化酶抑制剂5-氮胞苷上调了dDTC促甲状腺激素受体（TSH-R）的表达。本项目利用重叠PCR法，构建了单链TSH（scTSH），放射配体结合分析显示scTSH可特异性结合TSH-R，并具有刺激生成cAMP的能力。利用131I标记scTSH，获得131I-scTSH。体外细胞杀伤实验显示，131I- scTSH对dDTC细胞具有选择性杀伤作用（P<0.05）。构建荷dDTC的裸鼠，131I-scTSH体内治疗实验显示，肿瘤病灶可特异性摄取131I-scTSH。本项目的完成，对dDTC的靶向治疗提供了新的思路。