MiR-199~214 cluster at the crossroads of plasticity and malignancy in breastcancer

癌症的恶性进展与肿瘤细胞对现有肿瘤的抗性增加有关。 在美国，每年有超过40，000例与乳腺癌相关的死亡病例， 一个人更好地了解乳腺癌细胞（BCC）的恶性特征以及它们如何成为 转移性肿瘤的治疗将导致更有效的治疗方法的发展，以挽救患者的生命。 我们先前的研究已经确定，乳腺肿瘤的微环境是丰富的， 称为间充质干细胞（MSC）的祖细胞，否则有助于维持和 在创伤和炎症期间结缔组织的再生。重要的是，我们证明， 肿瘤相关的MSC发挥了强大的促恶性功能，甚至导致转移性乳腺癌 细胞（BCC）扩散到远处的组织。这些发现归因于一个新的作用，骨髓间充质干细胞作为重要的 乳腺癌发病机制的决定因素，并提供了新的见解癌症转移。 为了阐明在转移背景下MSC与BCCs建立的异型相互作用，我们 对MSC刺激的BCC进行了详细的分子分析，并确定miR-199 a ~214是最重要的 BCC中MSC刺激的microRNA。我们提出的证据表明，miR-199 a ~214促进癌症干细胞 (CSC)它的作用涉及FOXP 2的下调，FOXP 2是一种叉头蛋白， 转录因子与言语和语言发育密切相关。我们发现FOXP 2 在BCCs中敲低miR-199 a ~214的表达，并且它足以促进CSC 增殖、肿瘤起始和转移。重要的是，我们发现miR-199 a的升高和miR-199 a的降低， FOXP 2表达水平代表了恶性临床乳腺癌的显著特征， 三阴性（TN）和HER 2-富集乳腺癌。 在这个提议中，我们将阐明新发现的miR-199 a-FOXP 2轴在乳腺癌中的作用。 癌症发病机制使用体外、体内和临床方法，我们将：（1）确定miR-125在细胞内的作用。 199 a作为晚期临床疾病的生物标志物，并证明其在临床前转移中的重要性。 模型，以建立其作为乳腺癌治疗靶点的相关性;（2）阐明转移- miR-199 a ~214在体内外的相关活性;（3）破译调控分子网络 作为基底细胞癌中miR-199 a诱导的基础，阐明了这种网络如何汇聚和调节FOXP 2 沉默，并确定FOXP 2如何发挥其下游功能。 总的来说，我们提出的研究将确定和定义新的和重要的分子决定因素， 调节乳腺CSC的发生、维持和转移。这些见解将揭示内在的 乳腺癌的最恶性细胞的工作，并将有助于提供新的工具，在潜在的效用， 恶性疾病的预后和治疗。

Malignant progression of cancer is associated with increased resistance of neoplastic cells to existing therapies, and is responsible for the majority of the >40,000 breast-cancer-related yearly fatalities in the US alone. A better understanding of the malignant features of breast cancer cells (BCCs) and how they become metastatic will lead to the development of more effective therapies that save patients' lives. Our prior studies have identified that the microenvironment of breast tumors is enriched for certain progenitor cells called mesenchymal stem cells (MSCs), cells that otherwise contribute to the maintenance and regeneration of connective tissues during wounding and inflammation. Importantly, we demonstrated that tumor-associated MSCs exerted potent pro-malignant functions, causing even poorly metastatic breast cancer cells (BCCs) to spread to distant tissues. These findings ascribed a novel role for MSCs as important determinants of breast cancer pathogenesis and provided new insights into cancer metastasis. To elucidate the heterotypic interactions that MSCs establish with BCCs in the context of metastasis, we conducted detailed molecular analyses of MSC-stimulated BCCs, and identified miR-199a~214 as the most MSC-stimulated microRNA in BCCs. We present evidence that miR-199a~214 promotes cancer stem cell (CSC) -like properties in cancer cells, and that its actions involve the downregulation of FOXP2, a forkhead transcription factor tightly associated with speech and language development. We show that FOXP2 knockdown in BCCs phenocopies miR-199a~214 expression, and that it is sufficient in promoting CSC propagation, tumor-initiation, and metastasis. Importantly, we show that elevated miR-199a and depressed FOXP2 expression levels represent prominent features of malignant clinical breast cancer, associating significantly with triple-negative (TN) and HER2-enriched breast cancers. In this proposal, we will elucidate the involvement of the newly discovered miR-199a-FOXP2 axis in breast cancer pathogenesis. Using in vitro, in vivo, and clinical approaches, we will: (1) determine the role of miR- 199a as a biomarker of advanced clinical disease, and demonstrate its essentiality for metastasis in pre-clinical models so as to establish its relevance as a target in breast cancer therapy; (2) elucidate the metastasis- associated activities of miR-199a~214 in vitro and in vivo; and (3) decipher the regulatory molecular networks underlying the induction of miR-199a in BCCs, elucidate how such networks converge on and regulate FOXP2 silencing, and determine how FOXP2 exerts its downstream functions. Collectively, our proposed studies will identify and define novel and important molecular determinants that regulate breast CSC genesis, maintenance, and metastasis. These insights would shed light on the inner workings of breast cancer's most malignant cells, and will serve to provide novel tools of potential utility in the prognosis and therapy of malignant disease.