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

 描述(申请人提供)：导管原位癌(DCIS)是一种早期乳腺癌，占美国所有乳腺癌的20%以上。本研究旨在阐明DCIS潜在的分子和病理机制。我们最近的工作表明，与正常细胞相比，DCIS中肿瘤启动细胞中miR29c的表达显著下调。此外，miR29c抑制了ID2基因的表达，ID2基因是一种去分化因子，在非致癌和癌前细胞中都有表达。我们还发现ID2参与了DCIS中肿瘤起始细胞的形成。作为一种转录调节因子，ID2通过隔离bHLH转录因子来控制基因表达；我们发现ID2上调了SOX2和脂肪酸合成酶(FASN)基因的表达。SOX2是众所周知的干细胞自我更新调节因子，而FASN是脂质代谢的关键酶，在肿瘤进展中发挥关键作用。我们还发现FASN基因在DCIS的肿瘤启动细胞中显著上调，白藜芦醇是一种在葡萄中丰富存在的化合物，它抑制FASN的表达并阻止DCIS的生长。在白藜芦醇的衍生物中，小分子药物蕨类药物在抑制FASN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是由miR29c-ID2轴控制的一个过程中由肿瘤起始细胞启动的，(B)ID2通过隔离bHLH转录因子调节SOX2和FASN促进肿瘤起始细胞的自我更新；以及(C)刺五加总皂苷通过抑制FASN的表达来防止DCIS的形成。为了验证这些假说，我们提出了一系列实验：确定分子途径的机制并在临床样本中进行验证(目标1)；在各种动物模型中阐明miR29c和ID2在DCIS启动中的作用(目标2)；然后测试选定的小分子化合物在预防DCIS方面的潜在治疗作用(目标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，这将对当前的临床实践产生重大影响。培训将通过相关课程作业、每周研讨会和期刊俱乐部演示、与主要导师的一对一会议以及对申请人与导师团队进展的批判性分析和讨论来提供。此外，研究培训计划的目的是：(I)生成概念框架，(Ii)探索尖端技术以执行计划的项目，(Iii)增强拨款和手稿撰写技能，以及(Iv)通过科学会议与顶尖癌症研究人员建立网络。维克森林大学综合癌症中心提供的最先进的设施和经验丰富的导师都将促进申请者成为一名在癌症生物学方面进行具有临床意义的转化研究的独立调查员。

 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.