Genetic and Dietary Interactions in MMR Deficient Colon Tumorigenesis

Lynch综合征(LS)/MMR缺陷(DMMR)驱动的肿瘤发生的小鼠遗传模型产生小 肠道肿瘤。然而，合作伙伴的长期合作工作现在已经开发出一种新的鼠标 整合遗传和环境因素导致小鼠结肠LS/dMMR肿瘤发生的模型 模仿人类的病原学。在绒毛蛋白Cre，Msh2loxp/loxP，TgfbRIIhu/Hu小鼠(VMshThu)中，纯合 肠和结肠上皮细胞中Msh2的失活会导致组织特异性dMMR。此外，“G” 小鼠TgfbR11基因的A段残基被CRISPR/Cas9改变为寡聚A， 在人类基因中复制寡核苷酸A，使TgbR11成为dMMR的关键靶点。小鼠发育成肠道 具有扁平腺瘤独特组织病理学的肿瘤进展为粘液性浸润性癌 LS/dMMR肿瘤的特征，每个肿瘤都有一个人源化的TgfbRII寡核苷酸A突变 吉恩。给VMshThu小鼠喂食纯化的啮齿动物西式饲料(NWD1)可将肿瘤的穿透性转移到 结肠，产生与人类LS/dMMR相同的独特病理。NWD1简要介绍了 在西方社会中，几种营养素水平的老鼠在流行病学上与更高的发病率有关 结直肠癌。这一新模型与人类LS有很高的相关性，包括与饮食相关的历史数据 人类LS向结肠外露的转变，以及与躯体相关的dMMR和散发性结肠肿瘤的发生 在普通人群中。 我们公布和提交的数据表明，给野生型小鼠喂食NWD1深刻改变了 肠干细胞在动态平衡和肿瘤发生中的作用，以及干细胞编程和 突变的积累、谱和特征。因此，我们假设转移到结肠癌的外显率。 给VMshThu小鼠喂食NWD1是由于结肠干细胞功能改变。目标1剖析了 NWD1对Lgr5hi、Bmi1小鼠VMshThu功能、编程、表观遗传学和遗传学的影响 和Aldh1结肠干细胞群。重点介绍了TGFb、Wnt信号、DNA修复和氧化 磷酸化途径，并在全球范围内延伸。目标2解决以下基本公共卫生问题 长期存活的结肠干细胞中特定编程、表观遗传学和遗传学变化的持久性及其 在将促肿瘤NWD1转换回纯净对照饲料时产生的后代。Aim 3剖析分子 独特的良性扁平腺瘤向粘液性侵袭性发展的特征变化 癌症。此外，使用LS患者与平均风险个体的独特RNAseq数据库进行比较 对于LS和dMMR患者的腺瘤和癌，两者之间的对应关系 老鼠模型和人类的基因和途径将被确定。这将确定以下目标的优先顺序 开发风险和进展的标记物，并进行进一步的机械解剖。

Mouse genetic models of Lynch syndrome (LS)/defective MMR (dMMR) driven tumorigenesis produce small intestinal tumors. However, long-standing collaborative work of the Co-PIs has now developed a new mouse model that causes LS/dMMR tumorigenesis in the mouse colon by integrating the genetic and environmental etiology that mimics that of the human. In the Villin-cre, Msh2loxp/loxp, TgfbRIIhu/hu mice (VMshThu), homozygous inactivation of Msh2 in intestinal and colonic epithelial cells causes tissue tissue-specific dMMR. Further, “G” residues in an otherwise “A” stretch in the mouse TgfbRll gene were altered by CRISPR/Cas9 to be oligoA, replicating the oligoA in the human gene that makes TgbRll a key target of dMMR. The mice develop intestinal tumors with the unique histopathologies of flat adenoma progressing to mucinous invasive carcinoma characteristic of LS/dMMR tumors, and every tumor has a mutation in the oligo A of the “humanized” TgfbRII gene. Feeding a purified rodent western-style diet (NWD1) to VMshThu mice shifts tumor penetrance into the colon, producing the same unique pathologies as in human LS/dMMR. The NWD1 recapitulates intake for the mouse of several nutrients at levels of each epidemiologically linked in western-societies to higher incidence of colorectal cancer. This new model has very high relevance to human LS, including historical data linking dietary shift in human LS to colon penetrance, as well as for somatically linked dMMR and sporadic colon tumorigenesis in the general population. Our published and submitted data establish that feeding NWD1 to wild-type mice profoundly alters function of intestinal stem cells in homeostasis and tumorigenesis, with underlying changes in stem cell programming and accumulation, spectra and signature of mutations. Therefore, we hypothesize shift to colon tumor penetrance by feeding NWD1 to VMshThu mice is due to altered colonic stem cell function. Aim 1 dissects alterations in function, programming, epigenetic and genetic changes induced by NWD1 in VMshThu mice in Lgr5hi, Bmi1+ and Aldh1+ colonic stem cell populations. Emphasis is on the Tgfb, Wnt signaling, DNA repair and oxidative phosphorylation pathways, and extended globally. Aim 2 addresses the fundamental public health issue of persistence of specific programming, epigenetic and genetic changes in long-lived colonic stem cells and their progeny upon switching the protumorigenic NWD1 back to purified control diet. Aim 3 dissects molecular changes that characterize the progression of the unique benign flat adenomas to mucinous invasive carcinomas. Further, using unique RNAseq data bases of LS patients compared to average risk individuals for the uninvolved mucosa, and for adenomas and carcinomas of LS and dMMR patients, correspondence between genes and pathways in the mouse model and in human will be determined. This will prioritize targets for development of markers of risk and progression and for further mechanistic dissection.