APOBEC MUTAGENESIS IN BREAST CANCER

总体-乳腺癌中的脱辅基细胞突变 摘要 APOBEC特征突变占原发性肿瘤中碱基置换突变的20%， 在转移中增加到超过50%。在雌激素受体（ER）中经常观察到额外的富集。 阳性疾病。APOBEC催化的单链（ss）DNA中的C-to-U损伤导致签名C-to-T， 5′-TCA和5′-TCT三核苷酸基序内的C至G突变。此外，APOBEC衍生的C-to-U病变 可被细胞DNA修复酶（错误）处理，导致单链和双链DNA断裂 以及更复杂的染色体重排APOBEC表达水平和诱变对应 临床结果较差，如可手术ER的女性无病生存期和总生存期较短， 乳腺癌阳性。升高的APOBEC水平也预测诊断为患有以下疾病的患者的总生存率较差 复发性ER阳性转移。这些和其他已发表的数据表明，APOBEC诱变是 在乳腺肿瘤细胞中持续存在，并支持我们的总体计划假设，即抑制APOBEC将 防止在残留ER阳性疾病中发生大比例的额外突变， 从而提高当前治疗的耐久性并导致更好的总体治疗结果。三 多学科项目将以综合和全面的方式共同努力，以测试这一想法。 项目1将开发报告系统，用于定量活细胞中的APOBEC活性，并确定 乳腺癌中负责APOBEC调节和基因组尿嘧啶加工的分子机制 细胞项目2将使用化学生物学方法研究APOBEC催化的 ssDNA脱氨，并将开发核酸和小分子探针来抑制APOBEC活性。 项目3将利用结构和生物物理方法研究APOBEC的全球机制 与ssDNA的结合以及对靶序列偏好重要的局部结构特征， 乳腺癌中APOBEC酶的抑制。这些项目将得到服务核心的支持， 在一些实施方案中，所述方法包括施用、鼠模型、计算化学和生物物理学以及酶和抗体。我们 该计划有望对ER阳性乳腺癌产生直接和长期的影响：立即 通过生产新技术和全面了解APOBEC的机制来产生影响 诱变，以及通过开发用于 诊断APOBEC阳性疾病和创造新的化学物质来抑制这种突变， 治疗益处的过程。

OVERALL – APOBEC MUTAGENESIS IN BREAST CANCER ABSTRACT APOBEC signature mutations make up 20% of base-substitution mutations in primary tumors, which increases to over 50% in metastases. Additional enrichment is often observed in estrogen receptor (ER)- positive disease. APOBEC-catalyzed C-to-U lesions in single-stranded (ss)DNA lead to signature C-to-T and C-to-G mutations within 5′-TCA and 5′-TCT trinucleotide motifs. In addition, APOBEC-derived C-to-U lesions can be (mis)processed by cellular DNA repair enzymes, resulting in single- and double-stranded DNA breaks and more complex chromosomal rearrangements. APOBEC expression levels and mutagenesis correspond with poor clinical outcomes, such as shorter disease-free and overall survival in women with operable ER- positive breast cancer. Elevated APOBEC levels also predict poor overall survival for patients diagnosed with recurrent ER-positive metastases. These and other published data demonstrate that APOBEC mutagenesis is ongoing in breast tumor cells and underpin our overarching Program hypothesis that inhibiting APOBEC will prevent a large proportion of additional mutations from happening in residual ER-positive disease and will thereby improve the durability of current treatments and result in better overall therapeutic outcomes. Three multidisciplinary Projects will work together in an integrated and comprehensive manner to test this idea. Project 1 will develop reporter systems for quantifying APOBEC activity in living cells and determine the molecular mechanisms responsible for APOBEC regulation and for genomic uracil processing in breast cancer cells. Project 2 will use chemical biology approaches to investigate the mechanism of APOBEC-catalyzed ssDNA deamination and will develop nucleic acid and small molecule probes to inhibit APOBEC activity. Project 3 will leverage structural and biophysical approaches to investigate global mechanisms for APOBEC binding to ssDNA as well as the local structural features important for target sequence preferences and inhibition of APOBEC enzymes in breast cancer. These Projects will be supported by service Cores for administration, murine models, computational chemistry and biophysics, and enzymes and antibodies. Our Program is poised to have both immediate and long-term impact for ER-positive breast cancer: immediate impact by producing novel technologies and a comprehensive understanding of the mechanism of APOBEC mutagenesis, and long-term impact on clinical translation through the development of technologies for diagnosing APOBEC-positive disease and the creation of novel chemical matter to inhibit this mutational process for therapeutic benefit.