The Impact of TLR on Intestinal Tumorigenesis

描述(申请人提供)：对肠上皮细胞(IEC)动态平衡至关重要的是模式识别受体，如TLR。将TLR适配器(如MyD88)KO小鼠与APC(Min/+)(APC)小鼠杂交，我们发现APC小鼠(即APC/MyD88-/-小鼠)MyD88基因缺失导致IEC肿瘤显著减少，存活率增加。我们观察到，控制这些小鼠肿瘤生长的IEC中c-myc蛋白的表达水平显著低于APC小鼠。我们发现，微生物来源的MyD88依赖的TLR配体通过p-ERK介导的翻译后修饰以不依赖Wnt的方式增强IEC中c-myc的表达。因此，在SA-1中，我们将探索p-ERK活性的调节是否通过遗传和药物手段控制APC小鼠的肠道肿瘤发生。我们将评估APC和APC/MKP-1-/-(其中MAPK phosphase-1基因缺失)的生存率和IEC肿瘤生长情况。我们将用UO126(一种MEK1/2抑制剂)治疗这些动物，并评估这种干预对生存和IEC肿瘤生长的影响。我们将测定从处理动物和未处理动物获取的IEC的组织病理学特征、关键信号事件、c-myc的表达以及增殖和凋亡，并将这些参数与APC/MyD88-/-和APC/c-mycIEC小鼠(其中c-myc在IEC中基因缺失)进行比较。我们认为，在炎症条件下，与生理条件相反，TLR-MyD88不依赖的途径使ERK磷酸化，从而增加IEC c-myc水平。因此，在SA-2中，我们将用诱导结肠炎的化学物质DSS治疗APC和APC突变体(见上文)，然后口服UO126或Sorafenib(一种RAS-RAF抑制剂)。如上所述，我们将分析和比较每种药物对生存率、IEC肿瘤诱导和IEC生物学的影响。这种遗传学和药理学方法的结合将使我们能够更好地了解IEC中c-myc表达的调节及其对IEC肿瘤发生的影响。公共卫生相关性：这项拨款申请建议在炎症和非炎症条件下，研究先天免疫对APC小鼠IEC肿瘤形成的影响。

DESCRIPTION (provided by applicant): Essential to intestinal epithelial cells (IEC) homeostasis are pattern recognition receptors such as TLR. Upon crossing TLR adapters (e.g., MyD88) ko mice to Apc(Min/+) (Apc) mice, we identified that the genetic deletion of MyD88 in Apc mice (i.e., Apc/MyD88-/- mice) resulted in a significant decrease in IEC tumors and an increase in survival. We observed that the expression levels of c-myc protein in IEC, which controls tumor growth in these mice, were significantly lower than those in Apc mice. We identified that microbial-derived MyD88-dependent TLR ligands enhance c-myc expression in IEC in a Wnt-independent manner by post-translational modifications, mediated by p-ERK. Thus, in SA-1 we will explore whether regulation of p-ERK activity controls intestinal tumorigenesis in Apc mice by genetic and pharmacological means. We will evaluate survival and IEC tumor growth in Apc and Apc/MKP-1-/- (in which MAPK phosphase-1 gene was deleted). We will treat these animals with UO126 (a MEK1/2 inhibitor) and assess the impact of this intervention on survival and IEC tumor growth. We will determine the histopathological features, key signaling events, the expression of the c-myc as well as proliferation and apoptosis of IEC harvested from treated and untreated animals and compare these parameters with those obtained from Apc/MyD88-/- and Apc/c-mycIEC mice (in which c-myc was genetically deleted in IEC). We assume that under inflammatory and in contrast to physiological conditions, TLR-MyD88-independent pathway phosphorylates ERK and therefore increases IEC c-myc levels. Thus, in SA-2, we will treat Apc, and Apc mutants (see above) with the colitis-inducing chemical, DSS, followed by oral administration of UO126 or Sorafenib (a RAS-RAF inhibitor). We will analyze and compare the impact of each drug on survival, IEC tumor induction and IEC biology as described above. This mix of genetic and pharmacological approaches will enable us to better understand the regulation of c-myc expression in IEC and its impact on IEC tumorigenesis. PUBLIC HEALTH RELEVANCE: This grant application proposes to study the impact of innate immunity on IEC tumorigenesis, under inflammatory and non-inflammatory conditions, in the Apc mouse.