Elucidating roles for the heparan sulfate and chondroitin sulfate glycosaminoglycan chains on Betaglycan in Wnt Signaling

项目总结/摘要 由于对控制肿瘤促进信号传导的机制的理解存在重大差距， 乳腺癌仍然是第二大最常见的癌症诊断和第二大原因， 女人的死亡在过去的几十年里，过度活跃的Wnt/β-catenin信号转导与细胞凋亡有关。 包括乳腺癌在内的多种癌症的发展， Wnt/β-catenin信号转导对乳腺癌治疗策略的发展至关重要。Betaglycan是一种 可以与或不与乙酰肝素和/或硫酸软骨素一起存在的跨膜蛋白聚糖共受体 糖胺聚糖（GAG）修饰，其重要性通过小鼠胚胎致死性来强调， 在调节癌细胞生物学中的作用，独立于其TGF-β辅助受体功能。本研究的目的 建议是定义β聚糖的差异修饰形式对Wnt3a信号传导的具体作用， 上皮癌模型。为了实现我们的目标，我们将追求三个目标。目标1将阐明 通过使用CRISPR/Cas替代物调节Wnt3a信号传导的差异修饰的β聚糖 具有缺乏硫酸乙酰肝素（HS）的β聚糖的修饰形式的全长β聚糖， 硫酸软骨素（CS）或两条GAG链。在这个目标中，我们将测试假设，即HS β聚糖 抑制Wnt信号传导，而CS β聚糖增强Wnt信号传导。目标2将侧重于界定 通过测试由差异修饰的β聚糖调节的Wnt3a/Frizzled/β聚糖相互作用的变化 假设HS β聚糖通过高亲和力相互作用螯合Wnt3a， 卷曲蛋白/β聚糖复合物，而CS β聚糖与Wnt3a弱相互作用， 卷曲/β聚糖复合物形成以增强Wnt信号传导。目标3，将决定 差异修饰的β聚糖对体外和体内乳腺肿瘤发生的作用， HS β聚糖负责抑制上皮肿瘤生长和转移，而CS β聚糖负责抑制上皮肿瘤生长和转移。 增强上皮肿瘤生长和转移，部分是通过改变Wnt信号传导。几 将使用体外生物化学技术和体内同基因原位研究的组合， 解决目标。在这些研究完成后，我们完全期望能界定房屋协会和政务司的具体角色 修饰的BG在调节Wnt活性和上皮肿瘤发生中的作用。因此，我们的研究将与 公共卫生，因为我们将扩大我们目前对控制肿瘤发生机制的理解。

PROJECT SUMMARY/ABSTRACT Due to the significant gaps in the understanding of mechanisms controlling tumor-promoting signaling pathways, mammary cancer remains the 2nd most common cancer diagnosed and the 2nd leading cause of death in women. Over the past few decades, hyperactive Wnt/β-catenin signaling has been linked to the development of multiple cancers, including mammary cancer, making identification of molecules regulating Wnt/β-catenin signaling crucial to the development of mammary cancer treatment strategies. Betaglycan is a transmembrane proteoglycan co-receptor that can exist with or without heparan and/or chondroitin sulfate glycosaminoglycan (GAG) modifications whose significance is underscored by embryonic lethality in mice and roles in regulating cancer cell biology, independent of its TGF-β coreceptor functions. The goal of this research proposal is to define the specific role of the differentially modified forms of Betaglycan on Wnt3a signaling in epithelial cancer models. To accomplish our goal, three aims will be pursued. Aim 1 will delineate the role of differentially modified Betaglycan in regulating Wnt3a signaling through the use of CRISPR/Cas replacements of full length Betaglycan with modified versions of Betaglycan lacking either its heparan sulfate (HS), chondroitin sulfate (CS) or both GAG chains. In this aim, we will test the hypothesis that HS Betaglycan suppresses Wnt signaling while CS Betaglycan enhances Wnt signaling. Aim 2 will focus on delineating changes in Wnt3a/Frizzled/Betaglycan interactions regulated by differentially modified Betaglycan by testing the hypothesis that HS Betaglycan sequesters Wnt3a through high affinity interactions resulting in less Frizzled/Betaglycan complexes while CS Betaglycan weakly interacts with Wnt3a promoting Frizzled/Betaglycan complex formation to enhance Wnt signaling. Aim 3, will determine the effects of differentially modified Betaglycan on mammary tumorigenesis in vitro and in vivo by testing the hypothesis that HS Betaglycan is responsible for suppressing epithelial tumor growth and metastasis while CS Betaglycan enhances epithelial tumor growth and metastasis, in part, through changes in Wnt signaling. Several combinations of biochemical techniques in vitro and syngeneic orthotopic studies in vivo will be used to address the aims. At the completion of these studies, we fully expect to define the specific roles of HS and CS modified BG in modulating Wnt activity and epithelial tumorigenesis. Our research will thus be relevant to public health as we will broaden our current understanding of mechanisms controlling tumorigenesis.