SPRY4-IT1介导SMD途径靶向降解TCEB1调控乳腺癌干细胞特性的分子机制

BCSCs是乳腺癌耐药复发的根源，LncRNA调控BCSCs特性备受关注。课题组通过LncRNA芯片检测到BCSCs中SPRY4-IT1特异高表达，并与P65表达正相关，与降解HIF-1α/2α的E3泛素连接酶关键因子TCEB1负相关；且预测到SPRY4-IT1存在与P65结合位点及与TCEB1-3'UTR区Alu元件互补。SPRY4-IT1是否被P65激活、进而通过STAU1介导mRNA降解（SMD）靶向抑制TCEB1调控BCSCs特性呢？有待阐明。本项目通过检测干扰STAU1表达后SPRY4-IT1降解TCEB1的变化，明确SPRY4-IT1降解TCEB1mRNA的SMD机制；通过确认p65与SPRY4-IT1启动子关键位点结合调控转录，阐明SPRY4-IT1被p65激活、进而介导SMD途径靶向降解TCEB1调控BCSCs特性的分子机制。为深入研究BCSCs特性机制提供新思路和新靶点。

Breast cancer stem cells (BCSCs) are responsible for the chemoresistance and recurrence of breast cancer. The regulation of long non-coding RNAs (LncRNAs) on the characteristics of BCSCs attracts researchers' more interest. We found that SPRY4 interionic transcript 1 (SPRY4-IT1) was specifically up-regulated in MCF-7 mammary sphere cells (MCF7 MS) with characteristics of BCSCs by LncRNA-Chip detection. Furthermore, in breast cancer tissues, we also found that the high expression of SPRY4-IT1 was positively correlated with the expression of p65, and negatively correlated with the expression of TCEB1, a key adaptor in E3 ubiquitin ligase complex, contributed to the HIF-1α/2α ubiquitination. Bioinformatic analysis showed that there were four binding sites between p65 and the promoter of SPRY4, and there was base-pairing between the Alu element with SPRY4-IT1 and the Alu element with the 3'UTR of TCEB1 mRNA. Can SPRY4-IT1 be activated by p65, and then regulate the characteristics of BCSCs through (STAU1)-mediated mRNA decay (SMD) degrading TCEB1 mRNA? This remains to be elucidated. Therefore, in this project, we plan to detect and analyze the changes of SPRY4-IT1 degrading TECB1 mRNA after interfering the STAU1 expression, and clarify the SMD mechanisms of SPRY4-IT1 degrading TCEB1. Furthermore, after confirming the direct key binding sites between p65 and SPRY4 promoter and translation activation of p65 on the SPRY4-IT1, our study will clarify the mechanism of SPRY4-IT1 activated by p65 and regulating the characteristics of BCSCs through degrading TCEB1 mRNA with SMD, and will propose a new idea and target for deep researching the mechanism of maintaining the BCSCs characteristics.