PROJECT 1

项目1 -乳腺癌中DNA脱氨酶的生物学 摘要 雌激素受体（ER）阳性乳腺癌是最常见的乳腺癌形式，占 每年超过75%的浸润性乳腺癌被诊断出来。ER阳性的总体突变景观 乳腺癌是多因素的，但DNA脱氨酶APOBEC 3B（A3 B）占原发性疾病中碱基取代突变的近20%，占转移灶中碱基取代突变的50%以上。A3 B在正常人中不表达。 乳腺上皮细胞中表达，并在大多数乳腺癌中过度表达。A3 B过表达 与ER阳性乳腺癌的不良临床结局相关，包括复发、转移和 耐药性我们的计划是测试总体假设，即A3 B抑制，作为一种佐剂， 主要治疗选择，将有助于防止有害的突变驱动的结果，如耐药性 和转移。项目1将直接促进合作计划的努力，通过以下方式检验这一假设： 3具体目标在目标1中，我们提出开发用于定量A3 B介导的编辑的报告系统， 活细胞，包括一个创新的，可移动的记者。在一个潜在的应用中，该系统将使 在一组作为候选的乳腺癌细胞系中快速检测候选小分子A3 B抑制剂 化合物是通过所有计划组成部分的协调活动开发的。在目标2中，我们 描述了正常和乳腺癌细胞中蛋白质水平A3 B调节的机制。这些研究将 专注于蛋白质组学数据集优先考虑的蛋白质-蛋白质相互作用。的全面表征 直接相互作用也有望揭示潜在的药物表面的合作研究， 化学探针（项目2），计算建模（核心C）和结构生物学（项目3）。在目标3中， 将讨论A3 B催化的基因组尿嘧啶病变如何被处理成无错误和致突变的结果 通过不同的DNA修复途径。这些研究有可能揭示DNA中的分子依赖性 修复是特定于乳腺肿瘤细胞经历A3 B催化的DNA损伤水平升高。 因此，项目1是这一整体计划的一个组成部分，因为它将提供创新的测定方法， 定量乳腺癌活细胞中的A3 B活性，产生对调节和潜在的 药物蛋白质表面，并揭示遗传依赖性，可能构成新的机会， 诊断和治疗发展。

PROJECT 1 – BIOLOGY OF DNA DEAMINASES IN BREAST CANCER ABSTRACT Estrogen receptor (ER)-positive breast cancer is the most common form of breast cancer, accounting for over 75% of invasive breast cancers diagnosed each year. The overall mutation landscape in ER-positive breast cancer is multifactorial, but the DNA deaminase APOBEC3B (A3B) accounts for nearly 20% of base-substitution mutations in primary disease and over 50% in metastases. A3B is not expressed in normal mammary epithelial cells and becomes overexpressed in the majority of breast cancers. A3B overexpression correlates with poor clinical outcomes for ER-positive breast cancer, including recurrence, metastasis, and drug resistance. Our Program is testing the overarching hypothesis that A3B inhibition, as an adjuvant to primary treatment options, will help to prevent detrimental mutation-driven outcomes such as drug resistance and metastasis. Project 1 will contribute directly to collaborative Program efforts to test this hypothesis through 3 specific aims. In Aim 1, we propose to develop reporter systems for quantifying A3B-mediated editing in living cells, including an innovative, transportable reporter. In one potential application, this system will enable rapid testing of candidate small molecule A3B inhibitors in a panel of breast cancer cell lines as candidate compounds are developed through the concerted activities of all Program components. In Aim 2, we will delineate mechanisms of protein-level A3B regulation in normal and breast cancer cells. These studies will focus on protein–protein interactions prioritized by proteomics data sets. Comprehensive characterization of direct interactions is also anticipated to reveal potentially druggable surfaces for collaborative studies on chemical probes (Project 2), computational modeling (Core C), and structural biology (Project 3). In Aim 3, we will address how A3B-catalyzed genomic uracil lesions are processed into error-free and mutagenic outcomes by different DNA repair pathways. These studies have the potential to reveal molecular dependencies in DNA repair that are specific to breast tumor cells undergoing elevated levels of DNA damage catalyzed by A3B. Thus, Project 1 is an integral component of this overall Program because it will provide innovative assays for quantifying A3B activity in living breast cancer cells, yield molecular insights into regulatory and potentially druggable protein surfaces, and uncover genetic dependencies that may constitute new opportunities for diagnostic and therapeutic development.