miR-221/222调控上皮间质转化对甲状腺癌细胞131I（碘）代谢和靶向内放疗敏感性的影响及机制

Targeted radiation with 131I (iodine) is an effective treatment for differentiated thyroid cancer (DTC). De-differentiation of DTC cells results in a decline in iodine uptake and a reduced sensitivity to radiation, thus appearing resistance to iodine treatment. It is the current problem, which is urgently needed related research. Through analysis on miRNA profiles and Oncomine database, it is found that miR-221/222 are generally higher expressed and SOCS3, TRPS1, TIMP3 the negative regulators of epithelial-mesenchymal transition (EMT) and several iodine metabolism-related genes lower expressed in thyroid cancer(TC). EMT is a key mechanism influencing TC cell iodine uptake and sensitivity to tumor radiotherapy. Demonstration on TC cell lines, we found that miR-221/222 regulate EMT. Bioinformatics analysis identified that SOCS3, ect. are the potential target genes of miR-221/222. This topic uses bioinformatics tools and gene expression profiles analysis to screen the potential targeted genes. And molecular biology techniques and in vivo and in vitro experiments were used to verify targeted gene and its mechanism on iodine resistance. Based on the regulation of miRNA on EMT, this research tempts to restore the iodine metabolism in TC cells and improve their radiosensitivity, namely systematically resolves the two issues together and provides a new way for further clinical studies.

分化型甲状腺癌失分化进展后对131I（碘）治疗抵抗，是甲状腺癌致死主要原因。逆转碘治疗抵抗是理想治疗方案，其中涉及碘代谢和靶向内放疗敏感性，两者在碘治疗过程中又相辅相成。通过现有miRNA表达谱和Oncomine数据库分析发现不同类型甲状腺癌中miR-221/222高表达，负向调控上皮间质转化（EMT）的基因SOCS3、TRPS1和TIMP3以及碘代谢相关基因低表达。经我们初步研究表明，甲状腺癌中miR-221/222调控EMT且SOCS3等为其潜在靶基因。本课题拟从miRNA研究着手，利用生物信息学、分子生物学、细胞和动物移植瘤模型等探讨其调控EMT机制及通过EMT调控对碘代谢和放疗敏感性影响并初步验证相关机制。甲状腺癌碘治疗抵抗细化为碘代谢和放疗敏感性两个层面，利于针对性的开展机制研究。通过miRNA又将二者结合，为深入的开展碘治疗抵抗机制研究和临床miRNA靶向治疗研究奠定基础。

近年来，分化型甲状腺癌（DTC）发病率迅速上升，DTC转移灶失分化进展后对131I（碘）治疗抵抗，是甲状腺癌致死主要原因，且仍然缺乏有效治疗措施。逆转碘治疗抵抗是理想治疗方案，其中涉及碘代谢和靶向内放疗敏感性，两者在碘治疗过程中又相辅相成。miRNA是一类核苷酸小分子，可以靶向抑制靶基因的表达发挥多样的生物学功能。我们选取DTC中高表达的miR-221/222为研究对象，通过构建过表达和抑制细胞模型验证其调控DTC碘代谢及放疗敏感性的机制。通过高通量测序、结合生物信息学选择miR-221/222潜在调控的靶基因及其生物学功能；按照课题既定设计方案，通过Western blot实验、Transwell、划痕实验、QRT-PCT等实验技术验证miR-221/222通过抑制SOCS3表达，增强STAT3磷酸化水平调控DTC细胞的上皮间质转化并抑制钠碘转运体（NIS）蛋白的表达和增强细胞的侵袭、转移能力。抑制miR-221/222可以逆转NIS蛋白的表达和抑制细胞的侵袭、转移能力；通过集落形成实验和增殖实验验证miR-221/222促进细胞的增殖和增强细胞的放疗抵抗。抑制miR-221/222表达后可以增强放疗敏感性。本研究初步验证miR-221/222调控EMT机制及其通过EMT调控对碘代谢和放疗敏感性影响。本课题表明miRNA具有多种生物学功能性，以miR-221/222为靶点具有调控碘代谢和放疗敏感性潜在价值。