lnc-MPEG1-1上调SERPINA1 促进甲状腺乳头状癌生长与转移的作用机制研究

Long non-coding RNA (lncRNA) plays a multifaceted role in tumorigenesis and progression. We previously found a novel lncRNA, lnc-MPEG1-1 (transcript 1) in PTC by a high-throughput array, which was further confirmed and found to be related with the lymph node metastasis in the clinical tissue samples. Our further exploratory experiments showed lnc-MPEG1-1 may promote the growth and invasion of PTC cells, upregulate the expresssion of SERPINA1, and activate the PI3K/AKT pathway. However, the molecular mechanisms of how lnc-MPEG1-1 regulates SERPINA1 and promote the growth and invasion of PTC cells are still unclear. In this study, we are going to thoroughly investigate the underlying molecular mechanisms of lnc-MPEG1-1 regulating the growth and metastasis of PTC in PTC cell lines, animal models and clinical PTC samples, including: (1) to confirm the function of lnc-MPEG1-1 in promoting the behavior of for PTC and to determnie its clinical significance; (2) to clarify the regulatory mechanism of the overexpression of lnc-MPEG1-1 in PTC and how it up-regulates the expression of SERPINA1 by using the RNA pulldown, mass spectrometry, and RIP; (3) to explore the role of the activation of SERPINA1/PI3K/AKT signaling in PTC cells in the condition of knocking out or overexpressing lnc-MPEG1-1. The results of this study will provide new clue for the mechanism of PTC development.

长链非编码RNA（lncRNA）在肿瘤发生和进展中发挥多方向作用。我们前期通过芯片检测并验证得知lnc-MPEG1-1在甲状腺乳头状癌（PTC）中高表达，并与PTC生长和侵袭行为相关。进一步预实验提示：lnc-MPEG1-1可上调SERPINA1的表达，并参与PI3K/AKT通路的激活。但其上调SERPINA1及促PTC生长和转移的具体机制并不清楚。本项目拟首先明确lnc-MPEG1-1 对PTC生长和转移的作用及临床意义。然后通过RNA-pulldown、质谱分析、RIP实验等从“lncRNA-蛋白”和“ceRNA”两个方面探索lnc-MPEG1-1调控SERPINA1表达的内在机制。最后在敲低/过表达lnc-MPEG1-1的细胞中，通过基因回复（沉默或导入）观察SERPINA1/PI3K/AKT 信号网络活性及其对PTC生长转移的影响。本研究将为揭示PTC生长和转移的机制提供新的线索。

甲状腺癌是最常见的内分泌肿瘤，近十年来其发病率在全世界呈现爆发式增长。2017年中国肿瘤统计年鉴显示甲状腺癌年发病率为6.63/10万，成为中国肿瘤发生率增长最快的肿瘤类型。甲状腺癌患者群体的迅速扩大引起了社会的高度关注。90%的以上甲状腺肿瘤为甲状腺乳头状癌（papillary thyroid carcinoma，PTC），新增病例增长几乎全部由PTC的增长所致。PTC恶性度相对较低，但极易发生颈部淋巴结转移，50-80%的PTC患者在确诊时已发生淋巴结转移。深入研究PTC 细胞的侵袭转移机制，对PTC的诊治具有重要指导意义。长链非编码RNA（lncRNA）在肿瘤发生和进展中发挥多方向作用。本项目通过芯片分析，发现了5个上调和5个下调的lncRNA，并在临床样本和公共数据库资料中进行了验证。除lnc-ARHGAP10-2:2在PTC癌组织中很少表达外，这些lncRNAs与LN转移呈正相关。晚期T期和晚期TNM期患者的lnc-RXRG-1:10、lnc-MPEG1-1:1和lnc-ABCA12-5:2显著增加，lnc-CENPJ-1:4、lnc-AADACL2-1:3、lnc-TCF4-5:18和lnc-PDLIM3-5:1降低。除lnc-ABCA12-5:2外,其余4个上调的lncRNA对PTC诊断效能均大于0.80。3个上调的lncRNAs显示出较好的预后评估效能，尤其是lnc-MPEG1-1:1，在TCGA队列和我们的验证队列中其AUC均超过0.70。随后的细胞实验和动物实验表明，lnc-MPEG1-1:1可以促进PTC的增殖和迁移，增加PTC的恶性潜能。细胞定位发现lnc-MPEG1-1:1主要位于细胞质中，其可以靶向调节miR-766-5p的表达。细胞实验显示lnc-MPEG1-1:1与miR-766-5p的互作促进了PTC的增殖、迁移和侵袭。进一步探索发现，lnc-MPEG1-1:1与miR-766-5p互相介导了EMT通路导致PTC的转移。