Interrupting tumor progression by restoration of VDR expression

项目摘要 维生素D在结直肠癌（CRC）中显示出癌症预防益处。尽管有一些积极的发现， 在人类干预试验中，相互矛盾的数据也很明显，需要进一步研究。一个重要 维生素D的有限作用与维生素D受体水平的显著降低有关 (VDR)活动我们最近在ApcΔ14/+小鼠中的研究显示，肠息肉中VDR表达缺失，大多数 这可能解释了高剂量维生素D3对癌症缺乏保护的原因。本研究进一步分析 其他研究结果表明，VDR表达受损可能影响β- 连环蛋白激活基于这些观察结果，我们假设， 肠道肿瘤可以恢复β-连环蛋白控制，并可能促进ApcΔ14/+小鼠的肿瘤消退。测试 基于这一假设，我们将使用我们最近开发的小鼠模型Scd 3 iCreER/+，在该模型中， 转基因可以被特异性地驱动至肠肿瘤。为了控制VDR表达式，我们将使用floxed- 终止系统，其中Vdr表达受STOP序列限制，直到他莫昔芬控制的Cre 重组酶被表达。这个条件小鼠模型的成功创建将使我们能够直接测试 定时VDR表达对肠中肿瘤消退的影响。在目标1中，我们计划生成 ROSA 26 LSL-Vdr-GFP小鼠，然后是复合突变小鼠，ApcΔ14/+：ROSA 26 LSL-Vdr-GFP：Scd 3 iCreER/+。这些 将对小鼠模型进行彻底表征以证实VDR在肠肿瘤内的强制表达。 在目标2中，使用ApcΔ14/+：ROSA 26 LSL-Vdr-GFP：Scd 3 iCreER/+小鼠，我们将检查外源性VDR对细胞增殖的影响。 再激活以时空方式对肠肿瘤发展的影响。我们还将分析 与VDR再表达相关的表达变化，重点关注VDR和 Wnt/β-catenin信号通路。目的3探讨外源性VDR表达对小鼠免疫功能的影响 使用cyTOF分析肿瘤微环境内的细胞运输。这些探索性研究将 为VDR的抗癌活性提供了一个清晰的认识，并最终使我们能够发现新的 CRC中被抑制的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.