PLAGL2 和 POFUT1 受一个进化上保守的双向启动子调控，通过维持干细胞特性协同参与结直肠癌的发生。
PLAGL2 and POFUT1 are regulated by an evolutionarily conserved bidirectional promoter and are collaboratively involved in colorectal cancer by maintaining stemness.
机构信息
Department of gastroenterological surgery, The Third XiangYa Hospital of Central South University, Changsha, Hunan 410013, China; Department of Colorectal and Anal Surgery of Zhongnan Hospital of Wuhan University, Wuhan 430071, Hubei Province, China.
Department of gastroenterological surgery, The Third XiangYa Hospital of Central South University, Changsha, Hunan 410013, China.
出版信息
EBioMedicine. 2019 Jul;45:124-138. doi: 10.1016/j.ebiom.2019.06.051. Epub 2019 Jul 4.
BACKGROUND
Our previous study revealed that PLAGL2 or POFUT1 can promote tumorigenesis and maintain significant positive correlations in colorectal cancer (CRC). However, the mechanism leading to the co-expression and the underlying functional and biological implications remain unclear.
METHODS
Clinical tumor tissues and TCGA dataset were utilized to analyze the co-expression of PLAGL2 and POFUT1. Luciferase reporter assays, specially made bidirectional promoter vectors and ectopic expression of 3'UTR were employed to study the mechanisms of co-expression. In vitro and in vivo assays were performed to further confirm the oncogenic function of both. The sphere formation assay, immunofluorescence, Western blot and qRT-PCR were performed to investigate the effect of both genes in colorectal cancer stem cells (CSCs).
FINDINGS
PLAGL2 and POFUT1 maintained co-expression in CRC (r = 0.91, p < .0001). An evolutionarily conserved bidirectional promoter, rather than post-transcriptional regulation by competing endogenous RNAs, caused the co-expression of PLAGL2 and POFUT1 in CRC. The bidirectional gene pair PLAGL2/POFUT1 was subverted in CRC and acted synergistically to promote colorectal tumorigenesis by maintaining stemness of colorectal cancer stem cells through the Wnt and Notch pathways. Finally, PLAGL2 and POFUT1 share transcription factor binding sites, and introducing mutations into promoter regions with shared transcription regulatory elements led to a decrease in the PLAGL2/POFUT1 promoter activity in both directions.
INTERPRETATION
Our team identified for the first time a bidirectional promoter pair oncogene, PLAGL2-POFUT1, in CRC. The two genes synergistically promote the progression of CRC and affect the characteristics of CSCs, which can offer promising intervention targets for clinicians and researchers. FUND: National Nature Science Foundation of China, the Hunan province projects of Postgraduate Independent Exploration and Innovation of Central South University.
背景
我们之前的研究表明，PLAGL2 或 POFUT1 可以促进结直肠癌（CRC）的肿瘤发生，并保持显著的正相关。然而，导致共表达的机制以及潜在的功能和生物学意义尚不清楚。
方法
利用临床肿瘤组织和 TCGA 数据集分析 PLAGL2 和 POFUT1 的共表达。利用荧光素酶报告基因检测、专门制作的双向启动子载体和 3'UTR 的异位表达来研究共表达的机制。进行体外和体内实验进一步证实两者的致癌作用。进行球体形成实验、免疫荧光、Western blot 和 qRT-PCR 来研究这两个基因在结直肠癌细胞（CSCs）中的作用。
发现
PLAGL2 和 POFUT1 在 CRC 中保持共表达（r=0.91，p<0.0001）。进化上保守的双向启动子，而不是竞争性内源性 RNA 的转录后调控，导致 CRC 中 PLAGL2 和 POFUT1 的共表达。双向基因对 PLAGL2/POFUT1 在 CRC 中被颠覆，并通过 Wnt 和 Notch 途径维持结直肠癌细胞的干性，协同促进结直肠肿瘤发生。最后，PLAGL2 和 POFUT1 共享转录因子结合位点，并且在具有共享转录调节元件的启动子区域引入突变会导致双向 PLAGL2/POFUT1 启动子活性降低。
解释
我们的团队首次在 CRC 中发现了一个双向启动子对致癌基因 PLAGL2-POFUT1。这两个基因协同促进 CRC 的进展并影响 CSCs 的特征，这为临床医生和研究人员提供了有希望的干预靶点。
基金
国家自然科学基金、湖南省中南大学研究生自主探索创新项目。
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