Mechanisms Underlying Replication Stress And Genome Instability Upon BRCA2 Deficiency

项目总结 BRCA2突变携带者极易患乳腺癌和卵巢癌(患乳腺癌和卵巢癌的风险为60% 卵巢癌的风险为30%-40%)，也增加了其他癌症的风险，如前列腺癌和胰腺癌。 然而，这些现象背后的机制仍然知之甚少。分子致病 步骤，特别是在BRCA2突变中驱动正常细胞(BRCA2mut/+)转变的最早步骤 肿瘤细胞的携带者在很大程度上是未知的。本提案中详述的实验将提供有价值的线索 这些早期的步骤可能是什么。对正常、假定健康的方式的知识和理解 细胞中携带BRCA2突变的个体开始成为肿瘤细胞，将会给我们带来急需的早期 有助于设计预防策略，并有助于降低B2突变癌症的发病率。 本提案中描述的实验策略是基于我们最近发表的工作，该工作表明 BRCA2缺陷细胞中单链DNA(SsDNA)积累增加，根据我们的初步数据 在BRCA2缺乏的细胞中显示高碱性部位和尿嘧啶积累。我们的初步数据还显示 BRCA2缺陷细胞中的核苷酸切除修复(NER)缺陷途径。基于我们强有力的初步调查 数据，我们建议研究胞嘧啶脱氨酶的APOBEC/AID家族在产生基本位点中的作用。 BRCA2缺陷细胞。我们还将使用BRCA2患者的来源组织来设计新的方法来对 未知的意义，并了解在B2杂合细胞中增加的基本位点和尿嘧啶是如何 有助于基因组的不稳定和肿瘤的发生。最后，我们还将研究BRCA2缺陷细胞是否 在经历复制应激时NER存在缺陷，如果BRCA2突变肿瘤中的这种弱点可能是 以联合药物治疗为靶点。 这项研究提供了一个机会来解决早期DNA损伤事件导致 BRCA2突变的肿瘤发生，并有可能提供急需的关键信息，将 帮助设计携带BRCA2突变的有效癌症预防和治疗策略 女人。

PROJECT SUMMARY BRCA2 mutation carriers are highly predisposed to breast and ovarian cancer (60% risk for breast cancer and 30-40% for ovarian cancer), and also have increased risk for other cancers like prostate and pancreatic. However, the mechanisms underlying these phenomena are still poorly understood. The molecular pathogenic steps, especially the earliest ones that drive the transition of normal cells (BRCA2mut/+) in a BRCA2 mutation carrier to tumor cells are largely unknown. Experiments detailed in this proposal will provide valuable clues to what those early steps could be. The knowledge and understanding of the way a normal, presumably healthy cell in BRCA2 mutation carrying individual starts becoming a tumor cell, will give us a much-needed early advantage to help design preventive strategies and contribute towards decreasing B2 mutant cancer incidence. The experimental strategy described in this proposal is based on our recently published work that shows increased single stranded DNA (ssDNA) accumulation in BRCA2 deficient cells, and on our preliminary data that shows high abasic site and uracil accumulation in BRCA2 deficient cells. Our preliminary data also shows defective nucleotide excision repair (NER) pathway in BRCA2 deficient cells. Based on our strong preliminary data, we propose to study the role of APOBEC/AID family of cytosine deaminases in generating abasic sites in BRCA2 deficient cells. We will also use BRCA2 patient derived tissue to design new ways to classify variants of unknown significance and also learn how increased abasic site and uracil in B2 heterozygous cells could contribute to genomic instability and tumorigenesis. Finally, we will also study whether BRCA2 deficient cells are defective in NER when undergoing replication stress, and if this weakness in BRCA2 mutant tumors could be targeted by combination drug therapy. This study provides an opportunity to address the question of early DNA damaging events that drive BRCA2 mutant tumorigenesis, and has the potential to provide the much needed, critical information that will help with the design of effective cancer prevention and therapeutic strategies for BRCA2 mutation bearing women.