Analysis of the cellular and molecular determinants of the human breast hierarchy

描述(由申请人提供)：鉴定人类乳腺前体细胞并了解它们的调节对于列举控制病理条件的起源和事件至关重要。确定正常原始细胞的身份和活性可以更好地理解干细胞生物学与癌症之间的联系。我们的研究旨在了解人类乳房发育的机制，以及激素生长因子信号对原始祖细胞的调控。对人类乳房发育和干细胞生物学的有限了解在很大程度上是由于缺乏适当的模型系统和分析方法来检测、分析和表征干细胞特性。近年来，我们的实验室开发和优化了各种体内和体外工具，以研究人类乳房发育的生物学和机制。我们开创并实施了一种创新的体内模型来研究人类乳房发育，方法是利用免疫缺陷小鼠的乳房脂肪垫作为重要内分泌信号事件的来源，并使用移植的人类间质支持人类乳房上皮的生长和分化。在最近的工作中，我们已经确定了：i)在人类乳腺组织中存在四种不同的上皮分化状态(两种腔型和两种基本表型)，它们基于CD24、EpCAM和CD49f的表达而不同；ii)存在有助于结构不同的元件(导管和小叶/肺泡)的双能前体细胞；iii)激素组合可以增强人类上皮细胞中的干/祖细胞活性；以及iv)激素生长因子机制通过TBX3的表达可以调节乳腺干细胞样细胞。在本项目的目标1中，我们将描绘成人乳腺组织中的上皮层级。在目标2中，我们将确定激素生长因子信号如何调节人类乳房祖细胞的活动。我们的研究为人类乳房祖细胞的特性提供了创新性的见解，并提供了激素驱动人类乳房祖细胞形态发生的关键分子基础，这可能是病理条件发展过程中的焦点。

DESCRIPTION (provided by applicant): The identification of human mammary progenitor cells and understanding their regulation is critical to enumerating the origins and events that control pathologic conditions. Determining the identity and activity of normal primitive cells could lead t a better understanding to the connection between stem cell biology and cancer. Our study is directed towards understanding the mechanisms that underlie human breast development and the regulation of primitive progenitor cells by hormone-growth factor signaling. The limited understanding of human breast development and stem cell biology has largely been due to the lack of appropriate model systems and assays to detect, analyze, and characterize stem cell properties. In recent years, our laboratory has developed and optimized various in vivo and in vitro tools to study the biology and mechanisms governing human breast development We have pioneered and implemented the use of an innovative in vivo model to study human mammary development by exploiting the mouse mammary fat pad of immunocompromised mice as a source of important endocrine signaling events and using grafted human stroma to support the growth and differentiation of the human mammary epithelium. In recent work, we have identified i) four distinguishable epithelial differentiation states (two luminal phenotypes and two basal phenotypes) within human breast tissues that differ on the basis of CD24, EpCAM and CD49f expression, ii) the existence of bipotent progenitors that contribute to structurally distinct elements (ducts and lobule/alveoli), iii) the hormonal combinations that enhance stem/progenitor cell activity within human epithelial cells, and iv) a hormone growth factor mechanism through TBX3 expression can regulate breast stem-like cells. In Aim 1 of this project, we will delineate the epithelial hierarchy in adult human breast tissue. In Aim 2, we will determine how hormone-growth factor signaling regulates human breast progenitor cell activity. Our studies provide innovative insight into the identity of human breast progenitor cells and provide critical molecula underpinnings by which hormones drive human breast progenitor cell morphogenesis that could serve as focal points during the development of pathological conditions.