APOBEC MUTAGENESIS IN BREAST CANCER

乳腺癌中APOBEC基因的整体突变 摘要 APOBEC特征突变占原发肿瘤碱基替换突变的20%， 在转移中增加到50%以上。在雌激素受体(ER)中经常观察到额外的富集物- 阳性疾病。APOBEC催化的单链DNA C-to-U损伤导致签名C-to-T和 5‘-TCA和5’-TCT三核苷酸基序的C-to-G突变。此外，APOBEC衍生的C-to-U病变 可被细胞DNA修复酶(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表达水平与突变相对应 临床结果不佳，如可手术的ER-R患者的无病生存期和总生存期较短。 阳性乳腺癌。APOBEC水平升高也预示着确诊为糖尿病的患者总体存活率较低 复发的ER阳性转移瘤。这些和其他公布的数据表明，APOBEC的突变是 在乳腺肿瘤细胞中正在进行，并支持我们的总体计划假设，即抑制APOBEC将 防止残留ER阳性疾病中发生很大比例的额外突变，并将 从而提高当前治疗的耐久性，并产生更好的整体治疗结果。三 多学科项目将以综合和全面的方式合作，以检验这一想法。 项目1将开发用于量化活细胞中APOBEC活性的报告系统，并确定 乳腺癌APOBEC调控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来研究APOBEC催化的机制 单链DNA脱氨基，并将开发核酸和小分子探针来抑制APOBEC的活性。 项目3将利用结构和生物物理方法研究亚太经合组织的全球机制 与单链DNA的结合以及对靶序列偏好和 乳腺癌中APOBEC酶的抑制作用。这些项目将由以下服务核心提供支持 给药，小鼠模型，计算化学和生物物理学，以及酶和抗体。我们的 该计划将对ER阳性乳腺癌产生直接和长期影响：立即 产生新技术的影响和对APOBEC机制的全面理解 突变，以及通过开发技术对临床翻译的长期影响 APOBEC阳性疾病的诊断和抑制这种突变的新化学物质的产生 为了治疗利益而进行的过程。

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.