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

 描述（由申请人提供）：BRCA1 突变导致乳腺癌风险增加的机制尚未完全了解，但被认为与负责维持 DNA 完整性（包括 DNA 修复功能）的细胞机制的缺陷有关。除了众所周知的对双链断裂修复的影响外，BRCA1 突变现在被认为会影响涉及维持 DNA 完整性的多个过程。新的证据表明，心理压力还会通过分子途径对 DNA 完整性产生负面影响，导致 ROS 水平升高以及 DNA 修复能力降低。这些考虑因素表明了我们计划的研究计划的中心假设：携带 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。 作为对该假设的第一个关键测试，我们将在两项概念上和逻辑上相互关联的试点研究（最终 n=50；25 个 BRCA1、25 个年龄、种族匹配的 BRCA1-）中探讨心理压力和 DNA 损伤之间的关系，以确认可行性并探索假设关系的效应大小。第一项试点研究（目标 1）将采用横断面相关研究设计，其主要结果是：在碱性条件下使用创新的 CometChip 技术评估外周血单核细胞 (PBMC) 的基线 DNA 损伤水平（损伤的次要特征是通过测定：γ-H2AX、pATM 和 DNA 8-OHdG）。统计分析将探讨 DNA 损伤水平与参与者对经过验证的心理压力和相关结构测量的反应之间的关系强度，以及通过离体伽马辐射引起的损伤恢复来评估 DNA 修复能力的贡献。第二项试点研究（目标 2）将采用实验研究设计，主要结果是从收集的血液样本中分离出 PBMC 的 DNA 损伤水平：参与者接受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），TSST 是心理生物学文献中经过最充分验证的实验压力范式。同时使用具有相同研究样本和共享血液样本（基线）的两种研究设计，提供了一种具有成本效益的方法来检验我们的总体假设，方法具有高内部有效性（实验研究）和强大的外部有效性（关联研究），同时还允许 两种方法的结果之间的直接比较。目标 1：统计研究有（BRCA1 组）和无（BRCA1 组）BRCA1 突变女性的心理压力水平和 DNA 损伤水平之间的关系。目标 2：通过实验研究急性心理压力对有或没有 BRCA1 突变的女性 DNA 损伤水平的影响。这项 R03 支持的试点工作将记录可行性并提供研究假设的效应量，这些假设将用作初步数据 全面的 R01 应用程序。结果对于降低 BRCA1 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.