Dietary Risk for Colon Cancer in the Mouse

描述（由申请人提供）：“散发性”结肠癌是指在美国和其他发达国家>90%的结肠癌。我们已经表明，这可以通过给C57 B1/6小鼠喂食“新西式饮食”（NWD 1）来模拟，所述饮食结合了美国和其他西方国家中结肠癌的许多营养风险因素：1）NWD是基于营养密度来配制的，以反映大部分人群消耗的较高脂肪和较低的钙和维生素D3水平; 2）在对照C57 B1/6小鼠中，肿瘤在其寿命的2/3内发生，与寿命的2/3相似（即50-60年）之前，大多数人散发性结肠癌的发展; 3）肿瘤发展的发病率和频率与一般人群相同; 4）将饮食中的钙和维生素D3提高到与人类结肠癌风险较低相关的水平，可以预防肿瘤的发展。我们报道，在C57 Bl/6小鼠中，在肿瘤形成之前，喂食NWD 1 6个月，大肠和小肠的平坦、组织学正常粘膜中的基因表达发生了微妙但显著的变化，这些变化与突变Apc等位基因遗传引起的变化显著重叠，并且可以通过提高钙和维生素D3（NWD 2）来预防。因此，扰动跟踪肿瘤形成的概率。最后，我们已经使用了一种新的方法，转录成像证明，Apc是单倍不足的Apc 1638 N/+小鼠调节肠细胞成熟的动力学，肠内稳态的扰动，也可能是由饮食引起的更高的风险。我们的假设是，散发性结肠癌的发展是一个随机过程，其概率是由肠粘膜适应营养摄入模式决定的。目的1，确定高风险饮食如何改变Lgr 5+肠干细胞的数量和位置分布，这些细胞分配到不同的谱系，Wnt和Notch信号传导的作用及其在粘膜稳态扰动中的相互作用，以及这些是否通过钙和维生素D3的升高来预防。这些实验利用了新的方法，包括：小鼠遗传品系，其中肠干细胞被标记，也允许谱系特异性追踪其后代;细胞分离的方法，作为细胞位置的函数沿着隐窝腔轴;和独特的成像特定基因的转录激活在单细胞水平原位。目的2采用了一种模型，更接近地概括了人类散发性结肠癌的Apc基因的条件性/诱导性突变将用于确定在适应营养因素后的动物寿命后期引入杂合或纯合Apc突变后，喂养6个月的饮食如何引发粘膜发生癌前病变和肿瘤病变。目的3扩展了我们发表的基因表达数据和最近生成的代谢组学数据，表明肠癌的饮食和遗传风险导致正常粘膜细胞（特别是祖细胞/增殖细胞室）早期向糖酵解转变，早于已知的结肠肿瘤特征的这种转变。为了回应之前的评论，我们将用2-脱氧-D葡萄糖抑制糖酵解，并确定这如何调节对干细胞，细胞成熟途径和谱系特异性分配以及炎症反应的饮食效应。增加了目标4，这也是为了回应在审查原始申请时提出的具体意见。在这一目标中，我们表征了饮食对结肠和小肠的炎症和细胞因子产生的影响。此外，基于我们最近的报告剖析了IL 12在介导巨噬细胞和结肠肿瘤上皮细胞之间的重要调节性串扰中的作用，以及我们的数据，即这种细胞因子被NWD 1升高，但这通过升高NWD 2中的钙和维生素D而被阻止，我们将使用一种新的抗IL 12的中和性单克隆抗体来确定这是否消除或调节饮食对粘膜中肿瘤相关改变的影响。

DESCRIPTION (provided by applicant): "Sporadic" colon cancer refers to >90% of colon cancer in the US and other developed countries. We have shown that this can be modeled by feeding C57Bl/6 mice a "new western- style diet" (NWD1) that combines a number of nutrient risk factors for colon cancer in the US and other western countries: 1) the NWD is formulated on the basis of nutrient density to reflect the higher fat and lower calcium and vitamin D3 levels consumed by large segments of the population; 2) tumors develop in control C57Bl/6 mice fed the diet for 2/3 of their life-span, similar to the 2/3 of the lifespan (ie 50-60 years) before most human sporadic colon cancer develops; 3) tumors develop at the same incidence and frequency as in the general population; 4) elevating calcium and vitamin D3 in the diet to levels associated with lower risk for colon cancer in the human prevents tumor development. We reported that in C57Bl/6 mice fed the NWD1 for 6 months, well before tumors form, there are subtle but significant alterations in gene expression in the flat, histologically normal mucosa of the large and small intestines that significantly overlap with alterations caused by inheritance of a mutant Apc allele, and that can be prevented by elevating calcium and vitamin D3 (NWD2). Thus, the perturbations track with probability of tumor formation. Finally, we have used a novel method of transcriptional imaging to demonstrate that Apc is haploinsufficient in the Apc1638N/+ mouse for regulating the dynamics of intestinal cell maturation, a perturbation of intestinal homeostasis that may also be caused by dietary induced higher risk. Our hypothesis is that development of sporadic colon cancer is a stochastic process the probability of which is determined by adaptation of the intestinal mucosa to patterns of nutrient intake. Aim 1, determines how the higher risk diet alters the number and positional distribution of Lgr5+ intestinal stem cells, allocation of these cells to different lineages, the role of Wnt and Notch signaling and their interaction in perturbations of mucosal homeostasis, and if these are prevented by elevation of calcium and vitamin D3. These experiments make use of novel methodology, including: a mouse genetic strain in which intestinal stem cells are marked and that also allows lineage specific tracing of their progeny; a method of cell isolation as a function of cell position along the crypt-luminal axis; and unique imaging of transcriptional activation of specific genes at the single cell level in situ. Aim 2 employs a model that more closely recapitulates human sporadic colon cancer in that conditional/inducible mutation of the Apc gene will be used to determine how the diets fed for 6 months prime the mucosa for development of preneoplastic and neoplastic lesions upon introduction of heterozygous or homozygous Apc mutation later in the animal's life-span following adaptation to nutritional factors. Aim 3 extends our published gene expression data and recently generated metabolomic data suggesting that both dietary and genetic risk for intestinal cancer cause an early shift towards glycolysis in cells of the normal appearing mucosa, specifically in the progenitor/proliferating cell compartment, long before such shifts that are known to characterize colon tumors. In response to comments made in the prior review, we will inhibit glycolysis with 2-deoxy-D glucose and determine how this modulates the dietary effects on stem cells, cell maturation pathways, and lineage specific allocation, and on inflammatory responses. Aim 4 has been added, again in response to specific comments in the review of the original application. In this aim we characterize the effects of the diets on inflammation and cytokine production of the colon and small intestine. Moreover, based on our recent reports dissecting the role of IL12 in mediating an important regulatory cross-talk between macrophages and colon tumor epithelial cells, and our data that this cytokine is elevated by the NWD1, but that this is prevented by elevating calcium and vitamin D in NWD2, we will use a novel neutralizing monoclonal Ab to IL12 to determine whether this eliminates or modulates the effects of diet on tumor associated alterations in the mucosa.