Nutritionally Driven Sporadic Intestinal Tumors: Impact on Stem Cells

西式饮食与人类散发性结直肠癌（CRC）密切相关， 所有人类CRC的亚型。这可以在喂食纯化啮齿动物饲料的小鼠中重现（NWD 1） 模拟CRC的主要人类营养风险因素的摄入。我们在这方面的大量出版工作 模型已经建立，有基本的生物化学和分子场效应， 在散发性肿瘤发展之前很久，NWD 1喂养的小鼠的粘膜组织学上表现为正常。这 包括改变的上皮细胞成熟，扩大和提高整个粘膜的Wnt信号， 改变了能量代谢 最近，我们报道了饲喂NWD 1对Lgr 5 hi隐窝碱基的能力有深远的影响， 柱状细胞在肠内稳态和肿瘤发展中起干细胞的作用。数据 提交用于出版（在此呈现），建立了喂食NWD 1差异性地编程Lgr 5 hi 和Bmi 1creERT 2标记的肠干细胞（RNAseq分析）。在Lgr 5 hi细胞中，这显著提高了 DNA损伤反应（DDR）基因的表达，特别是在错配修复途径中， 抑制Lgr 5 hi细胞体细胞突变的积累，并改变突变谱和特征。 此外，与我们报告的碳水化合物和脂肪作为能量的相对利用率的变化一致， 在喂食NWD 1的小鼠中，Lgr 5 hi细胞中编码以下组分的基因表达减少： TCA循环和线粒体电子传递的5种复合物中的每一种的多个亚基， 和Pgc 1a，线粒体功能和生物发生的主要调节剂。因此，NWD 1 降低了Lg 5 hi细胞在肠道内稳态和肿瘤发生中的功能，但增加了Bmi 1 子代在体内平衡和肿瘤发展中充当干细胞样细胞。因此，NWD 1-高度 与人类营养暴露相关，与CRC的人群风险密切相关-具有重大影响 关于塑造不同肠道干细胞群对粘膜的贡献 稳态和肿瘤发生。这些饮食对成体干细胞的影响是潜在的范例 在对散发性肿瘤风险的理解方面发生了变化。我们的总体假设是这些变化 为早期评估和调节相对风险提供了新的方法。 目的1确定NWD 1改变的表观遗传和遗传改变随时间的演变 小鼠肠/结肠成体干细胞在增加散发性CRC的可能性中的作用， 当饮食改变时，一旦建立这种变化的稳定性。目标2确定了 NWD 1对不同干细胞促进肿瘤发生的DNA损伤反应的影响 人口。目的3确定靶向Lgr 5茎的Pgc 1a基因失活的程度 肠和结肠粘膜的细胞足以概括NWD 1对肠和结肠粘膜的细胞的改变的作用。 Lgr 5干细胞编程和Lgr 5细胞对肠道稳态和肿瘤发生的贡献。

Western-style diets are strongly linked to human sporadic colorectal cancer (CRC), the predominant subtype of all human CRCs. This can be recapitulated in the mouse fed a purified rodent diet (NWD1) mimicking intake of major human nutrient risk factors for CRC. Our extensive published work on this model has established that there are fundamental biochemical and molecular field effects in the histologically normal appearing mucosa of NWD1 fed mice, long before sporadic tumors develop. This includes altered epithelial cell maturation, expanded and elevated Wnt signaling throughout the mucosa, and altered energy metabolism. More recently, we reported that feeding NWD1 has profound effects on ability of Lgr5hi crypt base columnar cells to function as stem cells in intestinal homeostasis and in tumor development. Data submitted for publication (presented herein), establish that feeding NWD1 differentially programs Lgr5hi and Bmi1creERT2 marked intestinal stem cells (RNAseq analysis). In Lgr5hi cells, this significantly elevates expression of DNA damage response (DDR) genes, in particular in the mismatch repair pathway, suppresses accumulation of Lgr5hi cell somatic mutations, and alters mutational spectra and signature. Further, consistent with the shift we reported in relative utilization of carbohydrate and fat as energy sources in mice fed NWD1, there was reduced expression in Lgr5hi cells of genes encoding components of the TCA cycle and of multiple subunits for each of the 5 complexes of mitochondrial electron transport, and for Pgc1a, a master regulator of mitochondrial function and biogenesis. As a consequence, NWD1 reduced Lg5hi cell function in intestinal homeostasis and tumorigenesis, but increased ability of Bmi1 progeny to act as stem-like cells in homeostasis and tumor development. Therefore, NWD1 - highly relevant to human nutritional exposures strongly linked to population risk for CRC – had a major impact on sculpting the contribution of different intestinal stem cell populations to contribute to mucosal homeostasis and tumorigenesis. These dietary effects on adult stem cells are potentially paradigm shifting in terms of understanding risk for sporadic tumors. Our overall hypothesis is that these changes in long-lived stem cells provide new approaches for early evaluation and modulation of relative risk. Aim 1 identifies the evolution with time of epigenetic and genetic alterations by which NWD1 alters mouse intestinal/colonic adult stem cells in elevating probability for sporadic CRC, and the relative stability of such changes once established when the diet is altered. Aim 2 determines the impact of NWD1 on altered DNA damage response to promoting tumorigenesis from the different stem cell populations. Aim 3 determines the extent to which genetic inactivation of Pgc1a targeted to Lgr5 stem cells of the intestinal and colonic mucosa is sufficient to recapitulate the effects of NWD1 on alteration of Lgr5 stem cell programming and contribution of Lgr5 cells to intestinal homeostasis and tumorigenesis.