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，CRC是主要的 所有人类CRC的亚型。这可以在喂食纯净啮齿动物饲料的小鼠身上重复(NWD1) 模拟人体主要营养危险因素对结直肠癌的摄入量。我们在这方面广泛出版的工作 模型已经建立了在生物化学和分子场效应的基础上 NWD1喂养的小鼠的组织学外观正常的粘膜，在散发性肿瘤发展之前很久就出现了。这 包括上皮细胞成熟改变，Wnt信号在整个粘膜中扩张和升高， 并改变了能量代谢。 最近，我们报道了饲喂NWD1对Lgr5hi隐窝基座能力的深刻影响 柱状细胞在肠道动态平衡和肿瘤发展中作为干细胞发挥作用。数据 提交以供出版(在此呈现)，确定馈送NWD1差异计划Lgr5hi 和Bmi1creERT2标记的肠干细胞(RNAseq分析)。在Lgr5hi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Lgr5hi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 来源：在喂食NWD1的小鼠中，Lgr5hi细胞中编码成分的基因表达减少 TCA循环和线粒体电子传递的5个复合体中的每一个的多个亚基， 对于线粒体功能和生物发生的主要调节者PGC1a。因此，NWD1 Lg5hi细胞在肠道内稳态和肿瘤发生中的功能降低，但Bmi1的能力增强 后代在动态平衡和肿瘤发展中扮演干细胞样细胞的角色。因此，NWD1-高度 与人类营养暴露密切相关，与结直肠癌的人口风险密切相关--产生了重大影响 关于塑造不同肠道干细胞群体对粘膜贡献的研究 动态平衡与肿瘤发生。这些饮食对成体干细胞的影响是潜在的范例 在理解散发性肿瘤风险方面的转变。我们的总体假设是，这些变化 在长期存活的干细胞中，为早期评估和调节相对风险提供了新的方法。 目标1确定NWD1改变的表观遗传和遗传改变随时间的进化 小鼠肠道/结肠成体干细胞发生散发性结直肠癌的概率升高及其相关因素 一旦饮食改变，这种变化就会变得稳定。目标2决定了 不同干细胞在促进肿瘤发生过程中DNA损伤反应的变化 人口。目的3确定针对Lgr5茎的PGC1a的遗传失活程度 肠和结肠粘膜的细胞足以概括NWD1在改变 Lgr5干细胞编程和Lgr5细胞在肠道内稳态和肿瘤发生中的作用。

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.