Role of metalloproteinases in mammary gland remodeling

描述（申请人提供）：本研究的总体目标是阐明小鼠乳腺生长、分化和发育过程中组织重塑的分子机制，并深入了解这一过程在包括癌症在内的病理疾病中是如何出错的。实现这一目标的核心问题是了解基质微环境如何调节青春期发育过程中正常上皮的侵袭行为，以及乳腺腔上皮和肌上皮细胞如何相互作用以形成稳定的导管树。细胞外基质（ECM）降解基质金属蛋白酶（MMPs）在基质中表达。它们在发育过程中正常组织重塑中发挥作用，也有助于肿瘤进展的发病机制。目前的建议解决了这些基质基质蛋白协调间质和上皮间室之间的串扰的机制。本提案的目标是解剖，在分子和细胞生物学的细节，MMPs如何影响分支形态发生，通过他们的能力协调乳腺基质微环境。该项目将使用转基因小鼠和乳腺细胞工具箱，器官型细胞培养模型和体内移植系统来询问这些模型并确定MMPs的关键底物，MMPs调节的信号通路以及细胞间通讯如何受到MMPs的影响。将使用活细胞成像、生物化学和细胞生物学相结合的方法分析器官型培养物的生长、形态发生、分化和侵入行为。体内分析将利用基因修饰的乳腺和原位移植的乳腺上皮细胞，用野生型和突变的MMPs、它们的抑制剂和底物转导。MMPs在分支形态发生过程中微调细胞间通讯中的作用将重点研究肌上皮细胞。该研究将重点关注MMP3/基质溶解素Wnt通路中的候选底物，以及MMPs对它们的切割如何影响乳腺上皮中的信号传导。通过剖析这些信号通路如何在平衡青春期乳腺干细胞的激活、增殖和分化以及机械环境中发挥作用，它们在乳腺癌中的应用应该会继续展开。这些实验将深入了解MMPs的失调如何直接导致乳腺癌的发展。了解MMPs如何在正常组织中发挥作用，以及其功能的破坏如何促进肿瘤形成，对于实现找到乳腺癌治疗方法的长期目标是必要的。公共卫生相关性：乳腺癌是妇女癌症死亡的第二大原因，也是妇女中最常见的癌症。本研究解决了女性健康的一个重要方面，即基质金属蛋白酶如何调节正常和肿瘤乳腺功能。本项目中使用的方法将阐明MMPs如何改变结构微环境，以及这如何影响正常和异常乳腺上皮和间质中生长和侵袭的关键反应。这些研究可能构成乳腺癌干预和治疗的基础，可能是在癌前病变。

DESCRIPTION (provided by applicant): The global objective of this research is to elucidate the molecular mechanisms underlying tissue remodeling during growth, differentiation and development in mouse mammary gland, and to gain insights into how this process goes awry in pathologic disorders, including cancer. A central issue in achieving this goal is to understand how the stromal microenvironment regulates the invasive behavior of normal epithelia during pubertal development and how mammary luminal and myoepithelial cells interact to form a stable ductal tree. Extracellular matrix (ECM)-degrading matrix metalloproteinases (MMPs) are expressed in the stroma. They play a role in normal tissue remodeling during development and also contribute to the pathogenesis of tumor progression. The present proposal addresses the mechanisms by which these stromal MMPs orchestrate the cross talk between mesenchymal and epithelial compartments. The goal for this proposal is to dissect, in molecular and cell biological detail, how MMPs affect branching morphogenesis through their ability to orchestrate the stromal microenvironment of the breast. The project will use a toolbox of genetically modified mice and mammary cells, organotypic cell culture models and in vivo transplantation systems to interrogate these models and determine the critical substrates of MMPs, what signaling pathways are regulated by MMPs and how intercellular communication is affected by MMPs. The organotypic cultures will be analyzed for growth, morphogenesis, differentiation, and invasive behavior using a combination of live cell imaging, biochemistry and cell biology. In vivo analysis will utilize genetically modified mammary glands and orthotopic transplants of mammary epithelial cells transduced with wild type and mutated MMPs, their inhibitors and substrates. The role of MMPs in fine-tuning intercellular communication during branching morphogenesis will be studied with emphasize on myoepithelial cells. The study will focus on candidate substrates in the Wnt pathway for MMP3/stromelysin, and how their cleavage by MMPs affects signaling in the mammary epithelium. By dissecting how these signaling pathways operate in balancing stem cell activation, proliferation and differentiation and the mechanical environment in the pubertal mammary gland, the applications to breast cancer should continue to unfold. These experiments will give insights into how misregulation of MMPs directly leads to the development of breast cancer. An understanding of how MMPs function in the normal tissue and how disruption of their function promotes neoplasia is necessary to achieve the long-term goal of finding cures for breast cancer. PUBLIC HEALTH RELEVANCE: Breast cancer is the second leading cause of cancer deaths in women and is the most common cancer among women. This study addresses an important aspect of women's health, of how matrix metalloproteinases regulate normal and neoplastic mammary gland function. The approaches used in this project will elucidate how MMPs alter the structural microenvironment, and how this influences the critical responses of growth and invasion in normal and abnormal mammary gland epithelium and stroma. These studies may form the basis of intervention and therapy in breast cancer, potentially in the premalignant lesions.