Pleiotropic functions of FOXC2 in EMT, stem cells and breast cancer progression

对治疗产生耐药性、肿瘤复发和转移对乳腺癌构成重大风险 这些癌症患者中的大多数死亡都是由这些癌症患者造成的。最近的研究 表明发育过程被称为上皮-间充质转化（EMT）， 称为癌症干细胞（CSC）的癌细胞亚群在这些不同的过程中。我们和其他人 已经表明EMT程序和干细胞特性是相互关联的，特别是癌细胞 能够通过激活EMT获得干细胞属性。这表明，针对EMT 该计划可以减少疾病负担，并将减少癌症患者的死亡。然而，缺乏 从肿瘤微环境发出的信号通路能够诱导EMT-包括 炎性细胞因子和转化生长因子β 1（TGF β 1）使治疗靶向 急救员在过去的9年里，我们实验室的累积研究已经导致了以下的开创性鉴定： 转录因子FOXC 2，作为转移的关键参与者，也作为肿瘤转移的常见下游效应物， 多个EMT信号通路和不可或缺的采购CSC的属性。的特性 CSC的特征是它们通过不对称或对称自我更新类型的细胞分裂进行自我更新的能力 从而使得CSC池能够继续存在和扩展。目前的提案将 系统地测试FOXC 2作为促进CSC自我更新的分子开关的关键元件的作用 和扩增，并研究FOXC 2的异常激活是否通过Notch导致CSC群体的增加 信号传导，导致肿瘤进展和转移。我们将结合体外和体内肿瘤 模型，患者来源的异种移植物以及基因工程小鼠模型来梳理这一点 过程我们还将研究TGF β 1的功能，TGF β 1是EMT的生理相关诱导剂， FOXC 2诱导的CSC扩增。此外，我们将评估FOXC 2调节的有丝分裂书签在维持 干细胞分裂后CSC的身份。最后，我们将测试选择的小分子抑制剂， 调节FOXC 2功能，选择性地防止EMT期间CSC扩张。意义：总之， 我们的建议不仅有助于澄清规范CSC自我更新和扩展的基本程序， CSCs在EMT期间，但也将有助于设计新的战略，这将提供一个机会， CSC向更分化的细胞和耗尽治疗抗性、转移倾向的CSC的平衡。

Development of resistance to therapies, tumor relapse, and metastasis pose significant risks to breast cancer patients and are responsible for the majority deaths among these cancer patients. Recent studies have demonstrated that the developmental process is known as epithelial-mesenchymal-transition (EMT) as well as a subpopulation of cancer cells termed cancer stem cells (CSC), in these various processes. We and others have shown that the EMT program and stem cell properties are interconnected, and specifically, cancer cells are capable of acquiring stem cell attributes through the activation of EMT. This suggested that targeting EMT program may reduce the disease burden and will decrease death among cancer patients. However, the dearth of signaling pathways emanating from the tumor microenvironment capable of inducing EMT - including inflammatory cytokines and transforming growth factor β-1 (TGFβ1) makes it impossible to therapeutically target EMT. Cumulative studies from our laboratory over the last 9 years have resulted in the seminal identification of the transcription factor FOXC2, as a key player in metastasis and also as a common downstream effector of multiple EMT-signaling pathways and indispensable for the procurement of CSC properties. A characteristic feature of CSCs is their capability to self-renew via asymmetrical or symmetrical self-renewal type of cell divisions thereby enabling the continued existence and expansion of the CSC pool. The current proposal will systematically test the role of FOXC2 as a critical element of the molecular switch facilitating CSC self-renewal and expansion, and investigate if aberrant activation of FOXC2 leads to increase in CSC populations via Notch signaling, resulting in tumor progression and metastasis. We will use a combination of in vitro-, and in vivo tumor models, and patient-derived xenografts as well as genetically engineered mouse models to tease out this process. We will also examine the function of TGFβ1, a physiologically relevant inducer of EMT, in dictating FOXC2-induced CSC expansion. Also, we will evaluate FOXC2-regulated mitotic bookmarking in maintaining the identity of the CSCs following stem cell division. Finally, we will test select small molecule inhibitors capable of modulating FOXC2-function in selectively preventing CSC expansion during EMT. Significance: In summary, our proposal will not only help clarify the fundamental processes regulating CSC self-renewal and expansion of CSCs during EMT but will also contribute to designing novel strategies that would provide an opportunity to shift the balance of CSC towards more differentiated cells and exhaust therapy-resistant, metastasis-prone CSCs.