Roles of miR29c-ID2 axis in tumor initiating cells of breast ductal carcinoma in situ

 描述（由申请人提供）：导管原位癌（DCIS）是乳腺癌的早期形式，占美国所有乳腺癌的20%以上。本研究旨在阐明DCIS的分子和病理机制。我们最近的工作揭示，与正常细胞相比，在DCIS中肿瘤起始细胞中的miR 29 c的表达显著下调。此外，miR 29 c抑制ID 2基因（一种去分化因子）在非致瘤细胞和癌前细胞中的表达。我们还发现ID 2有助于DCIS中肿瘤起始细胞的形成。作为一种转录调节因子，ID 2通过隔离bHLH转录因子来控制基因表达;我们发现ID 2上调了SOX 2和脂肪酸合成酶（FXR）基因的表达。SOX 2是一种众所周知的干细胞自我更新调节因子，而FXR是脂质代谢的关键酶，在肿瘤进展中起关键作用。我们还发现，在DCIS的肿瘤起始细胞中，FXR基因显著上调，并且白藜芦醇（一种在葡萄中大量发现的化合物）抑制FXR表达并阻断DCIS的生长。在白藜芦醇衍生物中，小分子药物紫檀芪在抑制FXR方面的效果是其他药物的十倍。基于这些新的发现，我们假设（a）DCIS是在由miR 29 c-ID 2轴控制的过程中从肿瘤起始细胞起始的，（B）ID 2通过螯合bHLH转录因子调节SOX 2和FXR来促进肿瘤起始细胞的自我更新;和（c）紫檀芪通过抑制FXR表达来防止DCIS形成。为了验证这些假设，我们提出了一系列实验：确定分子途径的机制并在临床样品中验证（目的1）;阐明miR 29 c和ID 2在各种动物模型中DCIS起始中的作用（目的2）;然后测试所选小分子化合物在DCIS预防中的潜在治疗效用（目的3）。这项拟议研究的长期目标是开发一种新的预防DCIS的治疗策略，这将对目前的临床实践产生重大影响。培训将通过相关的课程工作，每周研讨会和期刊俱乐部演示，与主要导师一对一的会议，以及与导师团队对申请人的进展进行批判性分析和讨论，为申请人提供培训。此外，研究培训计划旨在使（i）概念框架的生成，（ii）尖端技术的探索，以执行计划的项目，（iii）增强赠款和论文写作技能，以及（iv）通过科学会议与一流的癌症研究人员建立网络。无论是在维克森林大学的综合癌症中心提供的最先进的设施和经验丰富的导师将促进申请人的进展，成为一个独立的研究者谁进行临床有意义的癌症生物学转化研究。

 DESCRIPTION (provided by applicant): Ductal carcinoma in situ (DCIS) is an early-stage form of breast cancer that accounts for over 20% of all breast cancers in the US. This proposal aims to elucidate the underlying molecular and pathological mechanisms of DCIS. Our recent work revealed that the expression of miR29c in tumor-initiating cells was significantly down- regulated in DCIS compared to normal cells. Furthermore, miR29c suppressed expression of the ID2 gene, a dedifferentiation factor, in both non-tumorigenic and premalignant cells. We also found that ID2 contributed to formation of tumor-initiating cells in DCIS. As a transcription regulator, ID2 controls gene expression by sequestering bHLH transcription factors; we found that ID2 up-regulated expression of both the SOX2 and fatty acid synthase (FASN) genes. SOX2 is a well- known self-renewal regulator of stem cells, while FASN is a key enzyme for lipid metabolism and plays a critical role in tumor progression. We also found that the FASN gene is significantly up-regulated in tumor-initiating cells of DCIS and that resveratrol, a compound found abundantly in grapes, suppressed FASN expression and blocked growth of DCIS. Among resveratrol derivatives, the small-molecule drug pterostilbene was ten times more effective than others in suppressing FASN. Based on these novel discoveries, we hypothesize that (a) DCIS is initiated from tumor-initiating cells in a process controlled by the miR29c-ID2 axis, (b) ID2 promotes self-renewal of tumor-initiating cells by regulating SOX2 and FASN through sequestration of bHLH transcription factors; and (c) pterostilbene prevents DCIS formation by suppressing FASN expression. To test these hypotheses, we propose a series of experiments to: determine the mechanisms of the molecular pathway and validate in clinical samples (Aim 1); clarify the role of miR29c and ID2 in DCIS initiation in various animal models (Aim 2); and then test the potential therapeutic utility of selected small molecule compounds in DCIS prevention (Aim 3). The long-term objective of this proposed research is to develop a novel therapeutic strategy for DCIS prevention, which will have a significant impact on current clinical practice. Training will be provided to the applicant through relevant course work, weekly seminars and journal club presentations, one-to-one meetings with the primary mentor, and critical analysis and discussions of the applicant's progress with the mentor team. In addition, the research training program is designed to enable (i) generation of conceptual frameworks, (ii) exploration of cutting-edge technology to execute the planned project, (iii) enhancement of grant- and manuscript-writing skills, and (iv) building a network with top-notch cancer researchers through scientific meetings. Both the state-of-art facilities available at the Comprehensive Cancer Center of Wake Forest University and the seasoned mentor will facilitate the applicant's progress toward becoming an independent investigator who conducts clinically meaningful translational research in cancer biology.