Double-Strand Break Repair in Mouse Mammary Gland Development and Tumorigenesis

描述（由申请人提供）：同源定向修复（HDR）缺陷-被认为是修复DNA双链断裂（DSB）的三种途径中最准确的一种-可导致基因组不稳定性，并与肿瘤易感性相关。HDR中涉及的多个基因的突变与乳腺癌易感性有关，包括BRCA 1。乳腺受到其激素环境的高度影响，并在妊娠、哺乳和退化期间发生显著变化，但关于DNA损伤反应，特别是DNA修复如何受到这些发育阶段和肿瘤发生的影响，仍存在许多问题。一种广泛用于研究HDR修复DSB的报告基因是DR-GFP，其中两个缺陷GFP基因的直接重复序列通过I-SceI内切核酸酶切割其中一个重复序列而被诱导重组。为了测量动物组织内的HDR，我们最近产生了含有DR-GFP的小鼠，其在四环素诱导型启动子的控制下表达I-SceI，从而允许分析正常组织和肿瘤内的HDR。拟议的工作将利用这些新型HDR报告小鼠来分析正常和修复缺陷小鼠发育中乳腺的DSB修复以及乳腺肿瘤发生的小鼠模型，以确定乳腺组织的修复能力如何影响乳腺癌易感性和进展。具体而言，该项目旨在1）评估乳腺发育不同阶段小鼠乳腺组织中的HDR，以确定与产次相关的变化是否影响DSB修复反应; 2）研究Brca 1突变对乳腺上皮中HDR和细胞命运的影响;和3）在小鼠乳腺肿瘤模型中鉴定和表征与肿瘤进展和对治疗的反应相关的DNA修复的体内变化。在K99期间（目标1和2），我将由DNA DSB修复领域的领导者Maria Jasin博士指导，他的实验室发表了关于BRCA 1和BRCA 2在HDR中作用的关键论文。这项工作将揭示组织特异性和遗传变化如何影响乳腺中的DNA修复过程和肿瘤发生，并为未来更具体的乳腺癌预防和治疗策略提供有价值的见解。

DESCRIPTION (provided by applicant): Defects in homology-directed repair (HDR)-considered the most accurate of three pathways for repairing double-strand breaks (DSBs) in DNA-can lead to genomic instability and are associated with tumor predisposition. Mutations in multiple genes involved in HDR are linked to breast cancer susceptibility including BRCA1. The mammary gland is highly influenced by its hormonal environment and undergoes significant changes during pregnancy, lactation and involution, but many questions remain about how the DNA damage response, and specifically DNA repair, is impacted by these developmental stages and during tumorigenesis. A widely used reporter for studying DSB repair by HDR is DR-GFP in which direct repeats of two defective GFP genes are induced to recombine by I-SceI endonuclease cleavage of one of the repeats. To measure HDR within tissues of an animal, we have recently generated DR-GFP containing mice that express I-SceI under the control of a tetracycline-inducible promoter, allowing for the analysis of HDR within both normal tissues and tumors. The proposed work will utilize these novel HDR reporter mice to analyze DSB repair in the developing mammary gland of normal and repair-deficient mice and in a mouse model of mammary tumorigenesis to determine how repair proficiency of mammary tissue affects breast cancer predisposition and progression. Specifically this project aims 1) to assess HDR in the mammary tissue of mice during different stages of mammary gland development to determine whether changes associated with parity affect the DSB repair response; 2) to investigate the impact of Brca1 mutations on HDR and cell fate in the mammary epithelium; and 3) to identify and characterize in vivo changes in DNA repair associated with tumor progression and response to treatment in a mouse mammary tumor model. During the K99 period (Aims 1 and 2), I will be mentored by Dr. Maria Jasin, a leader in the field of DNA DSB repair whose lab has published key papers on the roles of BRCA1 and BRCA2 in HDR. This work will shed new light on how tissue specific and genetic changes influence DNA repair processes and tumorigenesis in the mammary gland and provide valuable insight for more specific breast cancer prevention and treatment strategies in the future.