FXR silencing in human colon cancer by DNA methylation and KRAS signaling
FXR silencing in human colon cancer by DNA methylation and KRAS signaling
复制标题
DOI：
10.1152/ajpgi.00234.2013
复制
发表时间：
2014-01-01
影响因子：
4.5
通讯作者：
Guo, Grace L.
中科院分区：
文献类型：
--
作者：
Bailey, Ann M.;Zhan, Le;Guo, Grace L.
法尼醇X受体（FXR）是一种胆汁酸核受体，通过小鼠基因敲除研究被描述为结肠腺癌发展的肿瘤抑制因子。本研究探讨了FXR在人类结肠癌发展中的调节作用。我们在正常组织（n = 238）、息肉（n = 32）和腺癌（I-IV期）中使用FXR免疫组化（n = 43、39、68和9）; 15种结肠癌细胞系中的RT-定量PCR、反相蛋白阵列和Western印迹分析;来自The Cancer Genome Atlas的结肠癌样品中的NR 1H 4启动子甲基化和mRNA表达; DNA甲基转移酶抑制;甲基DNA免疫沉淀（MeDIP）;亚硫酸氢盐测序;和V-Kiras 2 Kirsten大鼠肉瘤病毒癌基因同源物（KRAS）敲低评估，以研究结肠癌发展中的FXR调控。免疫组化和定量RT-PCR显示，FXR的表达和功能在癌前病变中减少，在大多数I-IV期肿瘤中沉默。FXR表达与磷脂酰肌醇-4，5-二磷酸3激酶信号传导和上皮-间质转化呈负相关。NR 1H 4启动子在类似于12%的结肠癌中被甲基化。癌症基因组图谱样本中，甲基化模式与肿瘤亚型分离。抑制DNA甲基化和KRAS沉默均增加FXR表达。FXR表达在人类结肠癌进展的早期降低，DNA甲基化和KRAS信号传导可能是FXR沉默的促成因素。FXR潜在地抑制上皮-间质转化和其他致癌信号级联，并且通过阻断沉默机制或增加残留FXR活性来恢复FXR活性代表了用于治疗结肠癌的有前景的治疗选择。
Farnesoid X receptor (FXR) is a bile acid nuclear receptor described through mouse knockout studies as a tumor suppressor for the development of colon adenocarcinomas. This study investigates the regulation of FXR in the development of human colon cancer. We used immunohistochemistry of FXR in normal tissue (n = 238), polyps (n = 32), and adenocarcinomas, staged I-IV (n = 43, 39, 68, and 9), of the colon; RT-quantitative PCR, reverse-phase protein array, and Western blot analysis in 15 colon cancer cell lines; NR1H4 promoter methylation and mRNA expression in colon cancer samples from The Cancer Genome Atlas; DNA methyltransferase inhibition; methyl-DNA immunoprecipitation (MeDIP); bisulfite sequencing; and V-Kiras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) knockdown assessment to investigate FXR regulation in colon cancer development. Immunohistochemistry and quantitative RT-PCR revealed that expression and function of FXR was reduced in precancerous lesions and silenced in a majority of stage I-IV tumors. FXR expression negatively correlated with phosphatidylinositol-4, 5-bisphosphate 3 kinase signaling and the epithelial-to-mesenchymal transition. The NR1H4 promoter is methylated in similar to 12% colon cancer The Cancer Genome Atlas samples, and methylation patterns segregate with tumor subtypes. Inhibition of DNA methylation and KRAS silencing both increased FXR expression. FXR expression is decreased early in human colon cancer progression, and both DNA methylation and KRAS signaling may be contributing factors to FXR silencing. FXR potentially suppresses epithelial-to-mesenchymal transition and other oncogenic signaling cascades, and restoration of FXR activity, by blocking silencing mechanisms or increasing residual FXR activity, represents promising therapeutic options for the treatment of colon cancer.