NG2-PG in tumor vascularization and progression

在小鼠乳腺肿瘤病毒启动子(MMTV-PYMT)的控制下，表达多瘤中T癌蛋白的雌性转基因小鼠100%发生多灶性乳腺肿瘤。在MMTV-FyMT模型中，通过包括肿瘤潜伏期、生长速度和转移在内的几个标准，基因消融跨越膜的NG2蛋白多糖大大减缓了乳腺肿瘤的进展。尽管NG2在MMTV-PYMT小鼠的乳腺肿瘤细胞中不表达，但它在肿瘤间质中表达于三种重要的细胞类型：肿瘤微血管中的周细胞，乳房脂肪垫中的脂肪细胞，以及从循环中侵袭肿瘤的巨噬细胞。因此，我们假设NG2对血管生成、脂肪生成和巨噬细胞募集的影响可能通过改变肿瘤细胞与这三种关键基质元素的相互作用而影响乳腺肿瘤的进展。在MMTV-PYMT模型中，ARRA提案的这一简化版本的具体目的将是检查微血管NG2和巨噬细胞NG2对乳腺肿瘤血管形成和进展的各自影响。 在目标1中，我们将比较在野生型和NG2阴性的MMTV-P7MT baökgroUnd中看到的肿瘤血管模式。Thi‘MTF Iñciuddéth TntiöñDFvár fUhcf[oh(通畅，基底板沉积，组织缺氧)，形态(扭曲)和密度，以及对周细胞/内皮细胞关系的检查，导致两种细胞类型的成熟。我们还将使用PDGFRb/Cre转基因小鼠，结合NG2等位基因，产生周细胞特异性NG2缺失小鼠。在MMTV-PYMT背景下，这只小鼠的乳腺肿瘤进展将更充分地阐明NG2在肿瘤发生中的周细胞特异性作用。 在目标2中，我们将研究NG2在巨噬细胞依赖性肿瘤进展中的作用。这将包括巨噬细胞在发展中的肿瘤中的募集，以及巨噬细胞在肿瘤血管形成、肿瘤细胞内渗和肿瘤转移中的作用。我们还将在MMTV-PYMT背景下，结合溶菌酶M/Cre小鼠和NG2等位基因，培育出巨噬细胞特异性NG2基因敲除小鼠。该模型将揭示NG2在乳腺肿瘤血管形成和进展中的巨噬细胞特异性作用

100% of female transgenic mice expressing the polyoma middle T oncoprotein under control of the mouse mammary tumor virus promoter (MMTV-PyMT) develop multifocal mammary tumors. By several criteria, including tumor latency, growth rate, and metastasis, genetic ablation of the membrane-spanning NG2 proteoglycan greatly slows mammary tumor progression in the MMTV-FyMT model. Although NG2 is not expressed by mammary tumor cells in the MMTV-PyMT mouse, it is expressed by three important cell types in the tumor stroma: pericytes in the tumor microvasculature, adipocytes in the mammary fat pad, and macrophages that invade tumors from the circulation. We therefore hypothesize that effects of NG2 on vascularization, adipogenesis, and macrophage recruitment may affect mammary tumor progression by altering tumor cell interactions with these three key stromal elements. The specific aims of this shortened ARRA version of the proposal will be to examine the respective effects of microvascular NG2 and macrophage NG2 on mammary tumor vascularization and progression in the MMTV-PyMT model. In Aim 1, we will compare the tumor vascularization patterns seen in wild type and NG2 nulFrriice oñ the MMTV-P7MT baökgroUnd. Thi'MTF iñciuddéth Tntiöñ dfVàëUIàr fUhcf[oh (patency, basal lamina deposition, tissue hypoxia), morphology (tortuousity), and density, along with examination of pericyte/endothelial cell relationships leading to maturation of both cell types. We will also use Pdgfrb/Cre transgenic mice, in conjunction with a floxed NG2 allele, to generate a pericyte-specific NG2 null mouse. Mammary tumor progression in this mouse on the MMTV-PyMT background will more fully illuminate the pericyte-specific effects of NG2 on tumorigenesis. In Aim 2 we will study the role of NG2 in macrophage-dependent tumor progression. This will include the recruitment of macrophages to developing tumors, and the role of macrophages in tumor vascularization, tumor cell intravasation, and tumor metastasis. We will also produce a macrophage-specific NG2 knockout mouse on the MMTV-PyMT background, using the lysozyme M/Cre mouse in conjunction with a floxed NG2 allele. This model will reveal macrophage-specific effects of NG2 on mammary tumor vascularization and progression