PROJECT 2

项目2-乳腺癌DNA脱氨酶的化学生物学 摘要 APOBEC酶是单链DNA胞嘧啶到尿嘧啶脱氨酶，通常保护细胞免受 病毒感染。然而，APOBEC3B(A3B)已被认为与导致肿瘤的乳腺癌突变有关 并导致抗药性的发展，最终导致治疗失败。A3B是 在所有雌激素受体(ER)阳性的乳腺肿瘤中，有一半以上过表达，这是最常见的类型，并且是 与较差的总体存活率有关。我们的计划已经表明，抑制A3B介导的肿瘤进化 改善ER阳性乳腺癌小鼠模型的治疗结果。我们的节目正在统一 假设A3B抑制将阻止ER阳性乳腺癌中很大比例的新突变， 从而提高当前治疗的耐久性，并产生更好的总体结果。要解决这个问题 假设我们的计划专注于了解A3B在乳腺癌细胞中的生物学(项目1)； 开发创新的核酸探针来分子表征A3B是如何与DNA底物和 抑制A3B催化的乳腺癌突变的小分子(项目2)；以及产生A3B X射线 用核酸、小分子和蛋白质配体的结构来了解A3B的结构基础- 介导的DNA突变及其抑制，以促进治疗性化合物的开发(项目3)。 这些活动将得到管理服务核心(核心A)、A3B驱动的动物模型的支持 乳腺癌(核心B)、计算化学和生物物理学(核心C)以及蛋白质和抗体生产 (核心D)。项目2-乳腺癌DNA脱氨酶的化学生物学将领导化学探针 1)合成A3B的复杂核酸配体以表征A3B如何 区分2‘-脱氧胞苷和其他核苷酸，并了解哪些核酸特征使 A3B对离散的DNA序列进行脱氨基，包括其结合DNA与RNA的总体偏好；以及 2)利用互补技术和方法开发一流的A3B小分子抑制剂 这将用于A3B驱动的乳腺癌突变的机械细胞分析(项目1)，结构 注释A3B配体结合的生物学研究(项目3)，以及动物模型的治疗效用实验 乳腺癌(核心B)。我们的研究将通过涉及计算配体的关键合作来实现 设计(核心C)和获得用于分析的高质量生物试剂(核心D)，我们的进展将 将我们的新型化合物定位于未来的治疗开发。有效的、选择性的A3B化学探针 具有体内活性，以及新的分析方法，是项目2的主要预期成果。 项目2将成为该计划的化学创新中心，加速所有项目并为 我们总体研究目标的实现。

PROJECT 2 – CHEMICAL BIOLOGY OF DNA DEAMINASES IN BREAST CANCER ABSTRACT APOBEC enzymes are single-stranded DNA cytosine-to-uracil deaminases that normally protect cells from viral infections. However, APOBEC3B (A3B) has been implicated in mutations in breast cancer that drive tumor evolution and contribute to the development of drug resistance and, ultimately, therapy failure. A3B is overexpressed in over half of all estrogen receptor (ER)-positive breast tumors, the most common type, and is associated with poor overall survival. Our Program has shown that inhibition of A3B-mediated tumor evolution improves therapy outcomes in a mouse model of ER-positive breast cancer. Our Program’s unifying hypothesis is that A3B inhibition will prevent a large proportion of new mutations in ER-positive breast cancer, thereby improving the durability of current treatments and resulting in better overall outcomes. To address this hypothesis our Program is focused on understanding the biology of A3B in breast cancer cells (Project 1); developing innovative nucleic acid probes to molecularly characterize how A3B engages DNA substrates and small molecules to inhibit A3B-catalyzed breast cancer mutations (Project 2); and generating A3B x-ray structures with nucleic acids, small molecules, and protein ligands to understand the structural basis of A3B- mediated DNA mutagenesis and its inhibition to enable development of therapeutic compounds (Project 3). These activities will be supported by Service Cores for administration (Core A), animal models of A3B-driven breast cancer (Core B), computational chemistry and biophysics (Core C), and protein and antibody production (Core D). Project 2 – Chemical Biology of DNA Deaminases in Breast Cancer will lead the chemical probe discovery efforts by 1) synthesizing complex nucleic acid ligands for A3B to characterize how A3B discriminates 2¢-deoxycytidine from other nucleotides and to understand which nucleic acid features enable A3B to deaminate discrete DNA sequences, including its overall preference for binding DNA versus RNA; and 2) using complimentary technologies and approaches to develop first-in-class small molecule inhibitors of A3B that will be used in mechanistic cellular assays of A3B-driven breast cancer mutation (Project 1), structural biology studies to annotate A3B-ligand binding (Project 3), and therapeutic utility experiments in animal models of breast cancer (Core B). Our studies will be enabled by critical collaborations involving computational ligand design (Core C) and access to high-quality biological reagents for assays (Core D), and our advances will position our novel compounds for future therapeutic development. Potent, selective chemical probes of A3B with in vivo activity, as well as novel assays, are the major anticipated deliverables of Project 2. As such, Project 2 will be the center of chemical innovation for the Program, accelerating all Projects and contributing to the achievement of our overall research objectives.