SP1 诱导的长链非编码 RNA SPRY4-IT1 的上调通过支架 EZH2/LSD1/DNMT1 和海绵 miR-101-3p 在胆管癌中发挥致癌作用。
SP1-induced upregulation of lncRNA SPRY4-IT1 exerts oncogenic properties by scaffolding EZH2/LSD1/DNMT1 and sponging miR-101-3p in cholangiocarcinoma.
机构信息
Department of Hepatopancreatobiliary Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, People's Republic of China.
Department of Endocrinology and Metabolism, Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, People's Republic of China.
出版信息
J Exp Clin Cancer Res. 2018 Apr 11;37(1):81. doi: 10.1186/s13046-018-0747-x.
BACKGROUND
Accumulating evidence has indicated that long non-coding RNAs (lncRNAs) behave as a novel class of transcription products during multiple cancer processes. However, the mechanisms responsible for their alteration in cholangiocarcinoma (CCA) are not fully understood.
METHODS
The expression of SPRY4-IT1 in CCA tissues and cell lines was determined by RT-qPCR, and the association between SPRY4-IT1 transcription and clinicopathologic features was analyzed. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were performed to explore whether SP1 could bind to the promoter region of SPRY4-IT1 and activate its transcription. The biological function of SPRY4-IT1 in CCA cells was evaluated both in vitro and in vivo. ChIP, RNA binding protein immunoprecipitation (RIP) and luciferase reporter assays were performed to determine the molecular mechanism of SPRY4-IT1 in cell proliferation, apoptosis and invasion.
RESULTS
SPRY4-IT1 was abnormally upregulated in CCA tissues and cells, and this upregulation was correlated with tumor stage and tumor node metastasis (TNM) stage in CCA patients. SPRY4-IT1 overexpression was also an unfavorable prognostic factor for patients with CCA. Additionally, SP1 could bind directly to the SPRY4-IT1 promoter region and activate its transcription. Furthermore, SPRY4-IT1 silencing caused tumor suppressive effects via reducing cell proliferation, migration and invasion; inducing cell apoptosis and reversing the epithelial-to-mesenchymal transition (EMT) process in CCA cells. Mechanistically, enhancer of zeste homolog 2 (EZH2) along with the lysine specific demethylase 1 (LSD1) or DNA methyltransferase 1 (DNMT1) were recruited by SPRY4-IT1, which functioned as a scaffold. Importantly, SPRY4-IT1 positively regulated the expression of EZH2 through sponging miR-101-3p.
CONCLUSIONS
Our data illustrate how SPRY4-IT1 plays an oncogenic role in CCA and may offer a potential therapeutic target for treating CCA.
背景
越来越多的证据表明，长非编码 RNA（lncRNA）在多种癌症过程中作为一类新型的转录产物发挥作用。然而，其在胆管癌（CCA）中改变的机制尚不完全清楚。
方法
采用 RT-qPCR 检测 CCA 组织和细胞系中 SPRY4-IT1 的表达，并分析 SPRY4-IT1 转录与临床病理特征的关系。通过荧光素酶报告和染色质免疫沉淀（ChIP）实验，探讨 SP1 是否能与 SPRY4-IT1 启动子区结合并激活其转录。采用体外和体内实验评估 SPRY4-IT1 在 CCA 细胞中的生物学功能。通过 ChIP、RNA 结合蛋白免疫沉淀（RIP）和荧光素酶报告实验，确定 SPRY4-IT1 在细胞增殖、凋亡和侵袭中的分子机制。
结果
SPRY4-IT1 在 CCA 组织和细胞中异常上调，其上调与 CCA 患者的肿瘤分期和肿瘤淋巴结转移（TNM）分期相关。SPRY4-IT1 过表达也是 CCA 患者预后不良的因素。此外，SP1 可直接与 SPRY4-IT1 启动子区结合并激活其转录。此外，沉默 SPRY4-IT1 通过减少 CCA 细胞的增殖、迁移和侵袭，诱导细胞凋亡和逆转上皮间质转化（EMT）过程，发挥肿瘤抑制作用。机制上，增强子结合蛋白同源物 2（EZH2）与赖氨酸特异性去甲基化酶 1（LSD1）或 DNA 甲基转移酶 1（DNMT1）一起被 SPRY4-IT1 招募，充当支架。重要的是，SPRY4-IT1 通过海绵吸附 miR-101-3p 正向调节 EZH2 的表达。
结论
本研究阐明了 SPRY4-IT1 在 CCA 中的致癌作用，并为治疗 CCA 提供了潜在的治疗靶点。
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