KAT5/miR-210/TET2通路在甲状腺未分化癌侵袭与转移中的作用机制研究

Anaplastic thyroid carcinoma(ATC) is an aggressive cancer with extremely poor prognosis due to invasive nature and metastatic capacity. Although ATC is uncommon, it accounts for the majority of thyroid cancer-related death. Therefore, there is an urgent need to understand the molecular mechanism driving ATC invasion and metastasis. Our previous study demonstrated that: In 82 clinical ATC samples, there is a strong correlation of KAT5 over-expression with poorer prognosis and tumor metastasis; At cellular level, down-regulation of KAT5 inhibits EMT, invasion and expression of miR-210 in ATC cells; Meanwhile, TET2 has been identified as a novel potential target of miR-210. Thus, we hypothesized that dis-activated KAT5/miR-210/TET2 pathway promotes invasion and metastasis of ATC. By using KAT5 shRNA or KAT5 specific inhibitor, transwell assay, immunofluorescence, electrophoretic mobility shift assay, chromatin immunoprecipitation, luciferase reporter assay, ATC orthotopic transplantation model in nude mice and clinical samples, we plan to verify this hypothesis through: (1)Exam the expressions of KAT5, c-Myc, miR-210 and TET2 in human ATC tissues, and analyze their correlations with ATC clinical indexes and patients’ prognosis; (2)Explore the effect of Kat5 on invasion and metastasis ability of ATC cells; (3)Illuminate the molecular mechanism underlying Kat5 promoting invasion and metastasis of ATC cells. All together, these expected results will demonstrate KAT5 plays a key role in promoting ATC invasion and metastasis, and provide novel therapeutic target in clinical ATC treatment.

虽然甲状腺未分化癌(ATC)仅占全部甲状腺癌的2%，但却造成50%的甲状腺癌相关死亡。侵袭与转移是ATC疗效差的主要原因，但机制仍不明确。我们预实验发现：82例人ATC标本中KAT5蛋白高表达与患者预后差及转移相关；下调KAT5能抑制ATC细胞的EMT、侵袭及miR-210表达；生物信息学分析发现TET2是miR-210的新靶基因。由此，我们提出假说：KAT5/miR-210/TET2通路异常激活促进ATC的侵袭与转移。本项目中，我们拟运用EMSA、ChIP、裸鼠原位移植瘤模型等手段，聚焦：1）临床水平，分析人ATC标本中KAT5、miR-210、TET2表达水平及相互关系；2）细胞、动物水平，明确KAT5在ATC侵袭与转移中的作用；3）分子水平，重点阐明KAT5通过miR-210/TET2促进ATC侵袭与转移的机制。拟证实KAT5是ATC侵袭与转移新的关键因子，并为ATC治疗提供新靶点。

研究背景：侵袭与转移及对放疗抵抗是甲状腺未分化癌(ATC)疗效差的主要原因，但机制仍不明确。我们预实验发现：ATC临床标本中KAT5蛋白高表达与患者预后差及转移相关；下调KAT5能抑制ATC细胞的EMT、侵袭、增殖，并增加ATC的放射敏感性；miR-210等异常表达是潜在下游机制。由此，我们提出假说：KAT5/miR-210/TET2通路异常激活促进ATC的侵袭与转移及放疗抵抗。.研究内容：（1）分析临床甲状腺癌标本中KAT5、miR-210等表达水平与患者预后的相关性；（2）细胞、动物水平，明确KAT5在ATC迁移、侵袭、转移、增殖及放疗抵抗中的作用；（3）分子水平，阐明KAT5调控miR-210等的转导机制。.重要结果及关键数据：（1）证实在临床甲状腺癌标本中，KAT5与miR-210高表达与患者预后较差相关;（2)证实在ATC细胞中，过表达的KAT5可促进细胞迁移、侵袭、远处转移、增殖及放疗抵抗，而敲低或特异性抑制KAT5则可以抑制细胞迁移、侵袭、远处转移及增殖，并提高其放疗敏感性；（3）证实在ATC细胞中，KAT5通过转录因子c-Myc激活miR-210转录，后者负性调节抑癌基因TET2表达，促进癌细胞的侵袭与转移与放疗抵抗，从而造成了ATC患者较差的预后；（4）发现并初步证实miR-221和miR-222可以预测甲状腺癌患者的预后。研究结果共发表SCI及中文系列期刊5篇，并在美国放射肿瘤学年会做壁报展示。.研究意义：为KAT5作为ATC治疗的新靶点提供理论依据。