转录因子CREB1介导的lncRNA-LOC100270746表达上调通过增加p68稳定性促进胃癌浸润转移的机制研究

Invasion and metastasis is an important reason for poor prognosis of patients with gastric cancer. The transcription factor CREB1 and long non-coding RNAs (lncRNAs) are closely related to the development and progression of tumors. At present, there is no report on CREB1 regulating non-coding RNAs in gastric cancer. Preliminary work of our group showed that CREB1, which was overexpressed in gastric cancer, could promote the migration and invasion of gastric cancer cells and was associated with poor prognosis of gastric cancer. CREB1 could positively regulate the expression of lncRNA LOC100270746. LOC100270746, mainly located in cell nucleus, could promote the migration and invasion of gastric cancer cells. LOC100270746 could bind directly to p68 protein and promote its stability. We intend to further investigate the expression of CREB1, LOC100270746 and p68 in gastric cancer and their clinical significance. The effects of CREB1, LOC100270746 and p68 on migration and invasion of gastric cancer would be investigated in vitro and in vivo. RNA pull-down, RNA-binding protein immunoprecipitation and Western blot would be performed to verify the regulatory effect of LOC100270746 on p68, and to construct the CREB1-LOC100270746-p68 signaling network in regulating invasion and metastasis of gastric cancer.

浸润转移是胃癌患者预后不良的重要原因。转录因子CREB1及长链非编码RNA（lncRNA）与肿瘤的发生发展有着密切的关系。然而目前在胃癌中尚未见CREB1调节非编码RNA的报道。本课题组前期工作发现胃癌中高表达的CREB1可促进胃癌细胞的迁移浸润能力，与患者预后不良相关。CREB1可正向调控lncRNA LOC100270746的表达。LOC100270746主要定位在细胞核，能够促进胃癌细胞的迁移浸润，其可以直接结合p68蛋白并促进其稳定性。我们拟进一步探究CREB1、LOC100270746、p68在胃癌中的表达情况及临床意义，通过体外、体内实验明确三者对胃癌迁移浸润能力的影响；采用RNA pull-down、RNA结合蛋白免疫沉淀、Western blot等方法验证LOC100270746对p68的调控作用，构建CREB1-LOC100270746-p68调节胃癌浸润转移的信号网络。

胃癌是严重危害人类健康的恶性肿瘤。浸润和转移依然是导致胃癌患者死亡的主要原因。深入探索胃癌浸润、转移机制，并在此基础上寻找新的治疗靶点成为当前的研究热点。CREB1是在多种肿瘤中发挥促癌作用的转录激活因子，目前已报道的其靶基因主要为mRNA。而长链非编码RNA（long non-coding RNA，lncRNA） 作为一类与肿瘤发生发展密切相关的RNA，其是否收到CREB1的调控尚不清楚。CREB1、lncRNA在胃癌浸润转移中的作用及机制有待进一步研究。本研究发现CREB1促进胃癌细胞迁移浸润，其可以结合到lncRNA LOC100270746的启动子区，促进LOC100270746的表达。体外细胞实验显示LOC100270746促进胃癌细胞迁移浸润。裸鼠体内实验显示LOC100270746促进胃癌肿瘤生长及转移。p68（DDX5）是LOC100270746的结合蛋白。LOC100270746通过促进p68（DDX5）的稳定性，上调p68（DDX5）的表达。下调p68（DDX5）后，可在一定程度上逆转LOC100270746的促迁移浸润作用。LOC100270746通过p68（DDX5）调控mTOR通路。综上，胃癌中转录因子CREB1 结合到lncRNA LOC100270746的启动子区，促进LOC100270746的表达。表达上调的LOC100270746直接结合p68（DDX5）蛋白并增加其稳定性，进而调控mTOR通路，促进胃癌的浸润转移。本项目构建了CREB1-LOC100270746-p68-mTOR调控胃癌浸润转移的信号网络，有望发现参与胃癌浸润转移的关键lncRNA，为胃癌转移的治疗提供新的潜在作用靶点。