Intestinal region-specific Wnt signalling profiles reveal interrelation between cell identity and oncogenic pathway activity in cancer development

We use a 3D in vitro organoid model to study the early phase of colorectal cancer development. In reaction to Wnt activation we observe downregulation of location specific genes and differentiation markers. Furthermore, the signature of Wnt target genes differs between organoids representing three locations of the murine intestine. The location specific Wnt signatures are dominated by genes which have been lowly expressed in the tissue of origin, and are the targets of transcription factors that are activated following enhanced Wnt signalling. We concude that the cell of origin has a substantial effect on the reaction to Wnt activation in a simple intestinal adenoma model. Overall design: From three different murine intestinal locations we grow organoids. These are transformed to resemble adenomas after Wnt activation through lentiviral transduction with a stable form of beta-Catenin. The gene expression before and after Wnt activation is compared within each intestinal origin and across the three locations using RNA sequencing.

本研究采用三维体外类器官（3D in vitro organoid）模型，探究结直肠癌发生的早期进程。当受到Wnt信号通路激活刺激时，我们观察到位置特异性基因与分化标志物的表达出现下调现象。进一步分析发现，代表小鼠肠道三个不同解剖位置的类器官中，Wnt靶基因的特征谱存在显著差异。此类位置特异性Wnt特征以起源组织中低表达的基因为主导成分，这些基因同时也是Wnt信号增强后所激活的转录因子的靶标。本研究得出结论：在简易肠道腺瘤模型中，细胞起源对Wnt信号激活的应答反应具有显著影响。
实验整体设计：从小鼠肠道的三个不同解剖位置分离培养类器官，通过慢病毒转导稳定型β-连环蛋白（beta-Catenin）以激活Wnt信号通路，使类器官转化为腺瘤样表型。借助RNA测序（RNA sequencing）技术，我们分别在每个肠道起源位置内部，以及三个位置之间，对比了Wnt信号激活前后的基因表达谱差异。