Effects of psychological stress on DNA damage and repair in healthy BRCA1+ women

 描述(申请人提供)：BRCA1突变导致乳腺癌风险增加的机制尚不完全清楚，但被认为与负责维持DNA完整性的细胞机制缺陷有关，包括DNA修复功能。除了众所周知的对双链断裂修复的影响外，BRCA1的突变现在被认为影响了维持DNA完整性的多个过程。新出现的证据表明，心理应激还可以通过导致ROS水平升高和DNA修复能力下降的分子途径对DNA完整性产生负面影响。这些考虑表明了我们计划研究计划的中心假设：BRCA1突变的女性可能特别容易受到心理压力对DNA完整性的负面影响。作为对这一假设的第一次关键检验，我们将在两个概念上和逻辑上相互关联的初步研究(最终n=50；25个BRCA1，25个年龄匹配的BRCA1-)中探索心理压力和DNA损伤之间的关系，以确认可行性并探索假设关系的影响大小。第一项先导性研究(目标1)将采用横断面相关研究设计，得出一个主要结果：在碱性条件下使用创新的CometChip技术评估外周血单个核细胞(PBMC)的脱氧核糖核酸损伤水平(第二个损伤特征是：γ-H2AX、pATM和DNA8-OHdG)。统计分析将探索DNA损伤水平与参与者在有效的心理压力和相关结构测量上的反应之间的关系强度，以及通过从体外伽马辐射造成的损伤中恢复来评估DNA修复能力的贡献。第二项先导性研究(目标2)将使用实验研究设计，主要结果是从采集的血液样本中分离出的PBMC的DNA损伤水平：参与者暴露于Trier社会压力测试(TSST)之前(基线，T1)、紧接着(压力，T2)和暴露后75分钟(恢复，T3)，这是心理生物学文献中验证最充分的实验压力范式。同时使用相同研究样本和共享血液样本(基线)的两个研究设计提供了一种经济高效的方法来测试我们的总体假设，方法具有高内部效度(实验研究)和强外部效度(关联研究)，同时还允许 两种方法的结果之间的直接比较。目的：统计分析BRCA1基因突变女性(BRCA1组)和非BRCA1突变女性(BRCA1组)的心理应激水平与DNA损伤水平之间的关系。目的：实验研究急性心理应激对BRCA1基因突变和不突变女性DNA损伤水平的影响。这项由R03支持的试点工作将记录可行性，并为研究假设提供效果大小，这些假设将用作以下项目的初步数据 一个全面的R01应用程序。研究结果对降低BRCA1女性患乳腺癌的风险具有方法学、理论和公共卫生意义。

 DESCRIPTION (provided by applicant): The mechanisms by which mutations in BRCA1 result in increased risk of breast cancer are not yet fully understood, but are thought to revolve around deficits in cellular machinery responsible for the maintenance of DNA integrity, including DNA repair functions. In addition to well-known effects on repair of double-strand breaks, mutations in BRCA1 are now recognized to impact multiple processes involved in maintaining DNA integrity. Emerging evidence indicates that psychological stress can also negatively impact DNA integrity through molecular pathways leading to increased ROS levels, as well as reductions in DNA repair capacity. These considerations suggest the central hypothesis of our planned program of research: women with BRCA1 mutations may be particularly susceptible to negative effects of psychological stress on DNA integrity. As a first critical test of that hypothesis we will explore the relationships between psychological stress and DNA damage in two conceptually and logistically interrelated pilot studies (final n=50; 25 BRCA1+, 25 age-, race-matched BRCA1-) to confirm feasibility and explore effect sizes for hypothesized relationships. The first pilot study (Aim 1) will use a cross-sectional correlational study design with one primary outcome: baseline DNA damage levels in peripheral blood mononuclear cells (PBMCs) assessed using an innovative CometChip technology under alkaline conditions, (with damage secondarily characterized by assay of: γ-H2AX, pATM, and DNA 8-OHdG). Statistical analyses will explore the strength of relationships between DNA damage levels and participants' responses on validated measures of psychological stress and related constructs, as well as the contribution of DNA repair capacity assessed by recovery from damage induced by ex vivo gamma radiation. The second pilot study (Aim 2) will use an experimental study design with a primary outcome of DNA damage levels in PBMCs isolated from blood samples collected: before (Baseline, T1), immediately after (Stress, T2), and 75 minutes after (Recovery, T3) exposure of participants to the Trier Social Stress Test (TSST), the most well validated experimental stress paradigm in the psychobiological literature. The concurrent use of both research designs with the same study sample and shared blood samples (Baseline) provides a cost effective way to test our overarching hypothesis with approaches having high internal validity (experimental study) and strong external validity (association study), while also allowing direct comparisons between the results from the two approaches. Aim 1: To statistically examine the relationships between psychological stress levels and DNA damage levels in women with (BRCA1+ Group) and without (BRCA1- Group) BRCA1 mutations. Aim 2: To experimentally investigate the impact of acute psychological stress on levels of DNA damage in women with and without BRCA1 mutations. This R03-supported pilot work will document feasibility and provide effect sizes for study hypotheses that will be used as preliminary data for a comprehensive R01 application. Results have methodological, theoretical, and public health significance for reducing breast cancer risk in BRCA1+ women.