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

 描述（由申请人提供）：BRCA 1突变导致乳腺癌风险增加的机制尚未完全了解，但被认为是围绕负责维持DNA完整性（包括DNA修复功能）的细胞机制的缺陷。除了众所周知的对双链断裂修复的影响外，BRCA 1突变现在被认为会影响维持DNA完整性的多个过程。新出现的证据表明，心理压力也可以通过分子途径对DNA完整性产生负面影响，导致ROS水平增加，以及DNA修复能力降低。这些考虑表明了我们计划的研究计划的中心假设：BRCA 1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。 作为该假设的第一个关键检验，我们将在两个概念和逻辑相关的试点研究（最终n=50; 25 BRCA 1+，25年龄，种族匹配的BRCA 1-）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效应量。第一项初步研究（目的1）将采用横断面相关性研究设计，主要结局为：在碱性条件下使用创新的CometChip技术评估外周血单核细胞（PBMC）中的基线DNA损伤水平（通过γ-H2 AX、pATM和DNA 8-OHdG的测定对损伤进行次要表征）。统计分析将探讨DNA损伤水平和参与者对心理压力和相关结构的有效措施的反应之间的关系的强度，以及DNA修复能力的贡献评估从体外伽马辐射引起的损伤恢复。第二项初步研究（目标2）将使用一项实验研究设计，主要结局为从血液样本中分离的PBMC中的DNA损伤水平：参与者暴露于特里尔社会压力测试（TSST）之前（基线，T1）、之后立即（压力，T2）和之后75分钟（恢复，T3），特里尔社会压力测试是心理生物学文献中验证最充分的实验压力范例。同时使用具有相同研究样本和共享血液样本的两种研究设计（基线）提供了一种具有成本效益的方法来测试我们的总体假设，该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 直接比较两种方法的结果。目标1：统计分析BRCA 1基因突变女性（BRCA 1+组）和非BRCA 1基因突变女性（BRCA 1-组）的心理压力水平和DNA损伤水平之间的关系。目的2：实验研究急性心理应激对BRCA 1突变和非BRCA 1突变女性DNA损伤水平的影响。这项R 03支持的试点工作将记录可行性，并为研究假设提供效应量，这些研究假设将用作以下方面的初步数据： 全面的R 01应用。研究结果对降低BRCA 1+女性乳腺癌风险具有方法学、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.