Interrupting tumor progression by restoration of VDR expression

项目摘要 维生素D已在结直肠癌(CRC)中显示出预防癌症的益处。尽管有一些积极的发现， 相互矛盾的数据在人类干预试验中也很明显，需要进一步研究。一个重要的 据观察，维生素D的有限作用是维生素D受体水平的显著降低 (VDR)活动。我们最近在APCΔ14/小鼠中的研究表明，VDR在肠息肉中的表达缺失，大多数 可能是因为缺乏高剂量维生素D3提供的癌症保护。本研究中的进一步分析 而其他人的结果表明，VdR表达受损可能影响β的调节。 连环蛋白激活。基于这些观察，我们假设VDR在体内的强迫重新表达 肠道肿瘤可以恢复β-连环蛋白的控制，并有可能促进Δ14/小鼠肿瘤的消退。为了测试 在这一假设下，我们将使用我们最近开发的小鼠模型Scd3iCreer/，在该模型中，一个花环的表达 转基因可以特异性地驱动肠道肿瘤。为了控制VDR的表达，我们将利用一个加了花的- 停止系统，其中VDR的表达受到停止序列的限制，直到他莫昔芬控制的Cre 表达了重组酶。这个条件鼠标模型的成功创建将使我们能够直接测试 VDR定时表达对肠道肿瘤消退的影响在目标1中，我们计划生成 Δ14/：ROSA26LSL-vdr-gfp：scd3iCreer/。这些 将对小鼠模型进行彻底的定性，以确认VDR在肠道肿瘤中的强制表达。 在目标2中，使用APCΔ14/：ROSA26LSL-vdr-gfp：scd3iCreer/MICE，我们将检查外源VDR的影响 再激活对肠道肿瘤发展的时空影响。我们还将对基因进行分析 与VDR重新表达相关的表达变化，重点关注VDR和VDR之间的相互作用 Wnt/β-连环蛋白信号通路。目的3研究外源性VDR的表达对免疫功能的影响 用细胞TOF分析肿瘤微环境中的细胞运输。这些拟议的探索性研究将 提供对VDR抗癌活性的清楚了解，并最终使我们能够发现新的 结直肠癌患者VDR再激活的治疗策略。

Project Summary Vitamin D has shown cancer preventive benefit in colorectal cancer (CRC). Despite some positive findings, conflicting data is also evident in human intervention trials that further study is warranted. An important observation linking the limited effects of vitamin D is a significant reduction in the levels of vitamin D receptor (VDR) activity. Our recent study in ApcΔ14/+ mice showed a loss of VDR expression in intestinal polyps, most likely accounting for the lack of cancer protection afforded by high-dose vitamin D3. Further analysis in this study and results of others suggested that compromised VDR expression may have influence on the regulation of β- catenin activation. Based on these observations, we hypothesize that forced re-expression of VDR within intestinal tumors can restore β-catenin control and potentially promote tumor regression in ApcΔ14/+ mice. To test this hypothesis, we will use our recently developed mouse model, Scd3iCreER/+, in which the expression of a floxed transgene can be driven specifically to intestinal tumors. To control VDR expression, we will utilize a floxed- stop system, in which Vdr expression is restricted by a STOP sequence until tamoxifen-controlled Cre recombinase is expressed. The successful creation of this conditional mouse model will allow us to directly test the influence of timed VDR expression on tumor regression in the intestine. In Aim 1, we plan to generate ROSA26LSL-Vdr-GFP mice, and then a compound mutant mice, ApcΔ14/+:ROSA26LSL-Vdr-GFP:Scd3iCreER/+. These mouse models will be thoroughly characterized to confirm the forced expression of VDR within intestinal tumors. In Aim 2, using the ApcΔ14/+:ROSA26LSL-Vdr-GFP:Scd3iCreER/+ mice, we will examine the impact of exogenous VDR reactivation on intestinal tumor development in a spatio-temporal manner. We will also profile the gene expression changes associated with the re-expression of VDR, focusing on the interplay between VDR and Wnt/β-catenin signaling pathways. Aim 3 will investigate the effect of exogenous expression of VDR on immune cell trafficking within the tumor microenvironment using cyTOF analysis. These proposed exploratory studies will provide a clear understanding of the anticancer activities of VDR, and ultimately enable us to uncover new therapeutic strategies for the reactivation of repressed VDR in CRC.