Prostatic Effects of Chronic Exposure to Bisphenol A in a Rat Model

描述(由申请人提供)：本申请建议在国家毒理学计划/食品和药物管理局(NTP/FDA)为期两年的双酚A(BPA)毒性研究中增加终点，特别关注扩大前列腺分析。先前的研究表明，短暂的发育过程中暴露于低剂量的双酚A可以增加成年前列腺癌对衰老后雌激素水平升高的致癌敏感性。对前列腺DNA甲基组永久性改变的鉴定表明，BPA重新编程的分子机制涉及到表观遗传记忆的改变。拟议项目的目标是扩大慢性口服双酚A暴露后的前列腺终点，包括对尿道周围前列腺管、表观遗传标记和干细胞重新编程的分析，这些将通过提供一个分子框架来了解疾病易感性的增加，从而为符合GLP的毒理学研究增加重大价值。提出了以下具体目标：目的1：扩大前列腺癌的评估范围，将尿道部的前列腺管也包括在内。目的2：评价慢性双酚A暴露大鼠对激素致癌的易感性。目的：分析慢性双酚A暴露后前列腺侧部DNA甲基化和雌二醇(E2)/双酚A重编程基因的表达，以确定前列腺重编程的分子指纹图谱。目的4：检测双酚A暴露的前列腺干/祖细胞的自我更新活性、分化潜能和对雌二醇的反应性。在FDA的动物设施中，Spraogue-Dawley大鼠将接受一系列BPA剂量的慢性治疗，对于AIM 2，成年后接受睾酮+雌二醇(T+E)治疗1.5年。运往伊利诺伊大学芝加哥分校(UIC)实验室的组织将使用组织学方法、DNA甲基化和基因转录的分子分析以及使用前列腺素试验的前列腺干细胞培养进行评估。通过检查致癌易感性和确定长期暴露于BPA造成的终身前列腺紊乱的分子基础，目前的多学科方法将显著增强NTP/FDA使用GLP指南研究进行的证据评估的权重。

DESCRIPTION (provided by applicant): The present application proposes additional endpoints in the National Toxicology Program/Food and Drug Administration (NTP/FDA) 2-year bisphenol A (BPA) toxicity study with a specific focus on expanding prostate gland analysis. Prior research has shown that transient developmental exposure to low-dose BPA can enhance the carcinogenic susceptibility of the adult prostate gland to elevated estrogen levels upon aging. Identification of permanent changes in the prostate DNA methylome indicated that the molecular mechanisms of BPA reprogramming involve altered epigenetic memory. The goals of the proposed project are to expand the prostatic endpoints following chronic, oral BPA exposure to include analysis of periurethral prostatic ducts, epigenetic marks and stem cell reprogramming that will together add significant value to the GLP-compliant toxicology studies by providing a molecular framework to understand heightened disease susceptibility. The following specific aims are proposed: Aim 1: Expand the prostatic evaluation to include the periurethral prostatic ducts. Aim 2: Evaluate prostatic susceptibility to hormonal carcinogenesis in chronic BPA-exposed rats. Aim 3: Analyze DNA methylation and expression of estradiol (E2)/ BPA-reprogrammed genes in lateral prostates following chronic BPA exposure to identify molecular fingerprints of prostate reprogramming. Aim 4: Examine the stem/progenitor cells from BPA exposed prostates for self-renewal activity, differentiation potential and responsiveness to estradiol. Sprague-Dawley rats will be chronically treated with a range of BPA doses at the FDA animal facility and for Aim 2, treated with testosterone + estradiol (T+E) as adults for 1.5 years. Tissues shipped to the University of Illinois at Chicago (UIC) laboratory will be evaluated using histologic approaches, molecular analysis of DNA methylation and gene transcription, and prostate stem cell culture using a prostasphere assay. By examining carcinogenic susceptibility and identifying the molecular underpinnings of life-long prostate perturbations by prolonged BPA exposure, the present multidisciplinary approach will markedly enhance the weight-of-evidence assessment by the NTP/FDA using GLP-guideline studies.