TGF-β信号通过关键LncRNA在多层次调控Slug基因表达从而促进乳腺癌EMT及转移的新机制

The epithelial-mesenchymal transition (EMT) has been considered to be a critical step in breast cancer metastasis. Numerous studies and our recent work demonstrate that classical TGF-β signaling pathway plays an essential role in regulating breast cancer EMT and metastasis. However, the downstream signaling and detailed molecular mechanisms are far from being completely understood. Recently, we established an EMT model of breast cancer induced by TGF-β and compared the LncRNA expression profiles between mesenchymal-like and epithelial-like MCF-7 cells. We identified several LncRNAs that could coordinately regulate the expression of Slug and ZEB1 and studied preliminarily on the role of LncRNA-AC026904.1 and UCA1 in the process of TGF-β-induced breast cancer EMT. On this basis, we aim to delve deeper into the underlying mechanism by which LncRNA-AC026904.1 and UCA1 coordinately regulate Slug expression at both transcriptional and posttranscriptional levels. Moreover, we aim to elucidate the functional roles of key LncRNAs in the process of breast cancer EMT and metastasis induced by TGF-β. Taken together, this study could expand our understanding of TGF-β signaling pathway and provide novel molecular targets for diagnosis, treatment and prognosis of metastatic breast cancer. Therefore, this research project is significant to the theoretical research and practical applications.

上皮间质转化（EMT）是乳腺癌转移机制中一个核心的生物学过程，大量文献及我们最近的研究证明，经典TGF-β信号通路在乳腺癌EMT及转移中发挥关键调控作用，但其下游分子和调控机制尚不完全清楚。我们最近在TGF-β诱导的乳腺癌EMT模型中对比了乳腺癌发生EMT前后的长链非编码RNA（LncRNA）表达谱，鉴定出多个可能协同调控Slug与ZEB1基因表达的LncRNA，并对其中AC026904.1及UCA1在TGF-β调控乳腺癌EMT过程中的作用进行了初步探讨。本课题拟在此基础上，深入研究TGF-β下游关键LncRNA分子AC026904.1及UCA1在转录、转录后多个层次共同调节Slug基因表达的新机制，阐明关键LncRNA在TGF-β介导的乳腺癌EMT及转移中的功能意义。这些研究可以拓展对TGF-β信号调控机制的认识，还可为乳腺癌转移的诊断、治疗、预后判断提供新的分子靶标，具有重要意义和价值

上皮间质转化（EMT）是乳腺癌转移机制中一个核心的生物学过程，经典TGF-β信号通路在乳腺癌EMT及转移过程中发挥关键调控作用，但其下游分子和调控机制尚不完全清楚。在本项目的研究中，我们采用高通量方法分析比较了TGF-β处理组与对照组乳腺癌细胞之间的lncRNA表达谱，随后通过qPCR和Kaplan-Meier生存分析法对相关lncRNA在乳腺癌中的临床意义进行了探讨，又通过激光共聚焦技术、蛋白免疫印迹技术、3C技术、ChIRP技术、荧光素酶报告基因、染色质免疫沉淀、小动物活体成像等多种方法对lncRNA促进乳腺癌EMT的分子机制进行了深入研究。经过大量工作，我们发现TGF-β能够诱导乳腺癌细胞中119个lncRNA表达发生上调，其中的lncRNA-AC026904.1及lncRNA-UCA1在转移性乳腺癌组织中呈现高表达并与患者的预后不良密切相关。分子机制研究发现：lncRNA-AC026904.1与lncRNA-UCA1的表达分别受到非经典及经典TGF-β信号通路的调控；lncRNA-AC026904.1在细胞核中以增强子RNA的方式激活Slug基因转录，而lncRNA-UCA1则在细胞浆中以竞争性内源RNA (ceRNA)的方式从转录后水平调控Slug分子表达；受TGF-β信号激活的lncRNA-AC026904.1与lncRNA-UCA1殊途同归，共同上调EMT核心转录因子Slug的表达，从而促进乳腺癌EMT及转移过程。本项目揭示了TGF-β信号通过关键lncRNA调控Slug表达进而促进乳腺癌EMT和转移的新机制，不仅为乳腺癌转移的机制研究提供了新的思路，而且为确立lncRNA-AC026904.1与lncRNA-UCA1作为乳腺癌转移治疗的新靶点提供了充分科学依据。