Genetic and Dietary Interactions in MMR Deficient Colon Tumorigenesis

Lynch综合征（LS）/缺陷型MMR（dMMR）驱动的肿瘤发生的小鼠遗传模型产生小的 肠道肿瘤然而，长期合作工作的Co-PI现在已经开发出一种新的鼠标 通过整合遗传和环境因素导致小鼠结肠LS/dMMR肿瘤发生的模型 模仿人类的病因学。在Villin-cre、Msh 2loxp/loxp、TgfbRIIhu/hu小鼠（VMshThu）中， 肠和结肠上皮细胞中Msh 2的失活导致组织特异性dMMR。此外，“G” 小鼠TgfbRII基因中另外的“A”段中的残基被CRISPR/Cas9改变为oligoA， 在人类基因中复制寡A，使TgbRII成为dMMR的关键靶标。老鼠的肠道发育 具有独特组织病理学扁平腺瘤进展为粘液浸润性癌的肿瘤 LS/dMMR肿瘤的特征，并且每个肿瘤在“人源化”TgfbRII的寡核苷酸A中具有突变。 基因给VMshThu小鼠喂食纯化的啮齿类动物西式饮食（NWD 1）， 结肠，产生与人LS/dMMR相同的独特病理。NWD 1概括了 在西方社会流行病学上， 结肠直肠癌这种新模型与人类LS具有非常高的相关性，包括与饮食相关的历史数据。 人LS向结肠转移，以及体细胞连锁dMMR和散发性结肠肿瘤发生 在一般人群中。 我们发表和提交的数据表明，给野生型小鼠喂食NWD 1会深刻地改变其功能。 肠干细胞在体内平衡和肿瘤发生中的作用，以及干细胞编程和 突变的积累、光谱和特征。因此，我们假设转移到结肠肿瘤转移率 通过给VMshThu小鼠喂食NWD 1是由于结肠干细胞功能改变。Aim 1剖析了 在Lgr 5 hi，Bmi 1+中，NWD 1在VMshThu小鼠中诱导的功能、编程、表观遗传和遗传变化 和Aldh 1+结肠干细胞群。重点是Tgfb，Wnt信号，DNA修复和氧化 磷酸化途径，并在全球范围内扩展。目标2涉及以下基本公共卫生问题： 长寿命结肠干细胞中特异性编程、表观遗传和遗传变化的持续性及其 在将促肿瘤性NWD 1转换回纯化的对照饮食后，目标3剖析分子 特征性的变化是从良性扁平腺瘤进展为粘液性侵袭性腺瘤， 癌此外，使用LS患者与平均风险个体相比的独特RNAseq数据库， 对于LS和dMMR患者的腺瘤和癌， 将确定小鼠模型和人类中的基因和途径。这将优先考虑以下目标： 风险和进展的标记物的开发以及进一步的机械解剖。

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.