Microbial Metabolite Mimics, PXR and Colitis-Induced Colorectal Cancer

提出的项目直接针对控制异常炎症诱导的棘手问题。 通过了解领养孤儿的生物学特性了解肠道中的致癌信号(例如TLR4) 核受体(ONRs)。其中一种受体，孕烷X受体(PXR)，在 该药主要作用于肠道，是结肠炎相关性结肠癌(CRC)的潜在治疗靶点。自存在以来 结肠炎相关性结直肠癌的治疗是有限的，并且有显著的副作用，无毒的靶向性 有效的预防结肠癌的生物靶点是有根据的。根据我们的新观察，IPA 直接通过非造血性孕烷X受体抑制小鼠肠炎(IBD) (PXR)/Toll样受体4(TLR4)信号通路，本项目的目标是检验以下假设 肠道PXR可以由小分子独特地调节，这些小分子被设计成模拟肠道吲哚代谢产物 治疗IBD的新方法。基于吲哚/IPA化学支架的模仿，这个项目将生成 新型PXR配体，可以在治疗上针对人类的肠炎和结肠癌，并将 提供关于这些分子如何与PXR结合的机械性见解。我们的初步研究表明 共生菌来源的IPA在PXR和PXR中显著减轻吲哚美辛诱导的小鼠肠道损伤 TLR4依赖方式。IPA通过PXR调节肠道屏障功能。一种反向关系 在PXR和TLR4以及IPA和人类肠道样本和细胞系中的炎症之间，支持 我们在老鼠身上的发现。在小鼠中，IPA是PXR的有效激活剂，而人类受体则有效地激活 当在生理水平上与碱式吲哚结合时。人类PXR LBD突变体不敏感 被吲哚和IPA激活。吲哚和IPA在溶液中都能与PXR蛋白结合。IPA可防止 结肠炎诱导的小鼠结直肠癌。吲哚/间苯二酚化学支架的小分子模拟物(FKK)有效激活 PXR，对细胞和组织无毒。因此，由于PXR是肠道炎症的相关靶点，我们 假设微生物代谢物模拟将允许设计新的、有效的、最重要的是安全的 激活PXR和消除结肠炎相关CRC的化合物。为了实现我们的目标，我们将(1) 结构合理的靶向PXR的FKK类药物先导化合物的合成与体外验证 设计；(2)基于结合亲和力和特异性优化Lead FKK候选；(3)评估 先导FKK化合物在hPXR小鼠肠道化学模型中清除结直肠癌的体内效应 炎症/结直肠癌。在短期内，我们希望已经验证了一种新的治疗铅的基础上 它们在小鼠身上安全地消除CRC的可能性。这些研究可以作为进一步验证的基础。 在实验室建立针对人类疾病的动物模型后，才开始临床翻译。自.以来 PXR已被证明可以显著调节小鼠的屏障功能，我们的IPA样导联可以 可能对由肠道屏障功能障碍推动的其他疾病产生更广泛的影响。

The project proposed directly targets the vexing problem of controlling aberrant inflammation-induced carcinogenic signals (e.g., TLR4) in the intestine by understanding the biological properties of adopted orphan nuclear receptors (ONRs). One of these receptors, Pregnane X Receptor (PXR), is abundantly expressed in the intestines and is a potential therapeutic target for colitis –associated colon cancer (CRC). Since existing treatments for colitis-associated CRC are limited and have significant side effects, non-toxic targeting of validated biological targets to prevent colon cancer is warranted. Based on our novel observations that IPA abrogates murine intestinal inflammation (IBD) directly through the non-hematopoietic Pregnane X Receptor (PXR)/Toll-like Receptor 4 (TLR4) signaling pathway, the goal of this project is to test the hypothesis that intestinal PXR can be uniquely modulated by small molecules designed to mimic the gut indole metabolites as a novel approach to treat IBD. Based on the indole/IPA chemical scaffold mimicry, this project will generate novel PXR ligands that can therapeutically target intestinal inflammation and colon cancer in humans, and will provide mechanistic insights into how these molecules binds to PXR. Our preliminary studies have shown that IPA derived from symbionts significantly reduces indomethacin-induced intestinal injury in mice in a PXR and TLR4 dependent manner. IPA regulates intestinal barrier function through PXR. An inverse relationship between PXR and TLR4 as well as IPA and inflammation in human intestinal samples and cell lines, supports our findings in mice. In mice, IPA is a potent activator of PXR, while the human receptor is effectively activated when combined with base indole at a physiologically relevant level. Human PXR LBD mutants were insensitive to activation by indole and IPA. Both Indole and IPA bind to PXR protein in solution. IPA protects against colitis-induced CRC in mice. Small molecule mimics (FKK) of indole/IPA chemical scaffold potently activate PXR and are non-toxic to cells and tissues. Thus, as PXR is a relevant target for intestinal inflammation, we hypothesize that microbial metabolite mimicry will allow for the design of novel, potent and most of all safe compounds that activate PXR and abrogate colitis-associated CRC. To achieve our goals we will (1) synthesize and validate in vitro FKK drug-like lead compounds targeting PXR using rational structure based design; (2) optimize lead FKK candidates based on binding affinity and specificity; (3) evaluate the in vivo efficacy of the lead FKK compounds in abrogating CRC using chemical hPXR mouse models of intestinal inflammation/CRC. In the short-term, we hope to have validated a single novel therapeutic lead based on their likelihood to safely abrogate CRC in mice. These studies can serve as the basis for further validation in human disease-specific animal models in the laboratory prior to embarking on clinical translation. Since PXR has been shown to significantly modulate barrier function in mice, our IPA-like leads could potentially have broader impact on other diseases propelled by a dysfunctional intestinal barrier.