Environmental Chemical Body Burden and Prospective Breast Cancer Risk in the Cancer Prevention Study-3 Cohort

今天，美国环保署注册的合成化学品超过85，000种，但只有10%经过检测。 动物研究中的致癌性。在接受测试的人中，约200人显示出致癌和/或 乳腺肿瘤增加。然而，很少有化学物质在人类研究中进行评估，结果 在人类中的应用还没有定论。我们的研究将集中在全氟烷基和多氟烷基的化学体内负荷 物质（PFAS），以及绝经过渡期发生浸润性乳腺癌的伴随风险。 这些“永久性化学物质”普遍存在，持久存在，并且具有很高的公众利益，但对它们可能存在的研究 与乳腺癌的关系有限。我们假设这些物质的体内负荷水平升高 内分泌干扰物（EDCs）会增加患浸润性乳腺癌的风险， DNA甲基化（DNAm）和乳腺微环境的改变是将这些联系起来的机制。 化学品暴露和乳腺癌。我们将使用三管齐下的方法来检验这一假设。在特定 目标1，我们将在美国癌症协会癌症预防研究-3中对女性进行前瞻性研究 （CPS-3）评估绝经过渡期PFAS的身体负荷与 随后发生浸润性乳腺癌我们将测量采集的血浆样本中的PFAS水平 在1000名CPS-3参与者和1000名匹配的无癌症患者中，浸润性乳腺癌诊断前1至7年 CPS-3参与者，抽血时年龄均在40至57岁之间。在具体目标2中， 参与者，我们将使用Infinium MethylationEPIC BeadChips测量DNAm并进行表观基因组- 广泛关联研究（EWAS），以确定与无癌组织中PFAS水平相关的DNA变化。 参与者然后，我们将确定PFAS相关的DNAm变化与以下风险之间的关联： 发展成乳腺癌。这些有价值的DNAm数据也可以用于其他结果，包括 暴露于其他EDCs。在具体目标3中，我们将确定PFAS对组织和分子的直接影响， 与基因组学良好表征的原发性人类中癌症起始易感性相关的水平状态 乳腺上皮细胞（HMEC）。在原代乳腺细胞中识别这些机制至关重要 重要的是，PFAS的作用机制通常因组织而异。我们将使用二维培养来确定 短期接触和三维培养的影响，以确定长期化学品接触对 上皮细胞谱系的变化与加速老化和基因组中与年龄相关的分子变化一致 甲基化、谱系特异性转录和细胞角蛋白。这种多学科方法的结果 将促进我们对PFAS暴露对乳腺癌风险影响的理解， 敏感性的重要窗口。最终，我们希望我们所提出的项目的结果将确定一个 环境暴露的综合生物特征，提供对乳腺癌的机制见解 从内分泌干扰物的发展，并为未来的预防策略，以减少或减轻暴露的研究。

Today there are more than 85,000 EPA-registered synthetic chemicals, but only 10% have been tested for carcinogenicity in animal studies. Of those tested, ~200 have shown evidence of causing cancer and/or an increase in mammary tumors. However, few of the chemicals have been evaluated in human studies, and results in humans have been inconclusive. Our study will focus on chemical body burden of per- and poly-fluoroalkyl substances (PFAS), and concomitant risk of developing invasive breast cancer during the menopausal transition. These “forever chemicals” are pervasive, enduring, and of high public interest, yet studies of their possible relationship to breast cancer have been limited. We hypothesize that elevated body-burden levels of these endocrine-disrupting chemicals (EDCs) will increase the risk of developing invasive breast cancer, and that alterations in DNA methylation (DNAm) and the breast microenvironment are mechanisms that link these chemical exposures and breast cancer. We will test this hypothesis using a three-pronged approach. In Specific Aim 1, we will conduct a prospective study of women in the American Cancer Society Cancer Prevention Study-3 (CPS-3) to assess the association between body burden of PFAS during the menopausal transition and subsequent development of invasive breast cancer. We will measure PFAS levels in plasma samples collected 1 to 7 years before invasive breast cancer diagnosis in 1000 CPS-3 participants and 1000 matched, cancer-free CPS-3 participants, all between 40 and 57 years of age at blood draw. In Specific Aim 2, studying the same participants, we will measure DNAm using Infinium MethylationEPIC BeadChips and conduct an epigenome- wide association study (EWAS) to identify DNAm changes associated with levels of PFAS in the cancer-free participants. We then will determine the association between the PFAS-associated DNAm changes and risk of developing breast cancer. This valuable DNAm data also can be used later for other outcomes, including exposure to other EDCs. In Specific Aim 3, we will determine the direct effects of PFAS on tissue- and molecular- level states associated with susceptibility to cancer initiation in genomically-well-characterized primary human breast mammary epithelial cells (HMECs). Identifying these mechanisms in primary breast cells is critically important, as PFAS mechanisms of action generally differ by tissue. We will use 2-D cultures to determine the effects of short-term exposures and 3-D cultures to define the effects of protracted chemical exposures on changes in epithelial lineage consistent with accelerated aging and age-related molecular changes in genome methylation, lineage-specific transcription, and cytokeratin proteins. Results from this multi-disciplinary approach will advance our understanding of the effects of PFAS exposures on risk of developing breast cancer during an important window of susceptibility. Ultimately, we hope results from our proposed project will identify an integrated biological signature of environmental exposure, deliver mechanistic insights into breast cancer development from EDCs, and inform future studies for prevention strategies to reduce or mitigate exposures.