Perinatal xenoestrogen exposure: epigenesis and neoplasia

围产期异雌激素暴露：表观发生和肿瘤形成

• 批准号: 7171699
• 负责人: ANA SOTO
• 金额: $ 22.22万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-22 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7171699
• 关键词: DNA methylation; antiantibody; bioinformatics; breast neoplasms; environment related neoplasm /cancer; epigenetics; estrogen analog; gene environment interaction; gene expression; genetic mapping; genetic regulation; immunoprecipitation; laboratory rat; mammary gland; messenger RNA; microarray technology; phenols

DESCRIPTION (provided by applicant): The increased incidence of uterine leiomyoma, testicular and breast cancer observed in European and US populations during the last 50 years prompted scientists to hypothesize that prenatal exposure to environmental estrogens may be the underlying cause of these neoplasms. Epidemiological studies suggest that fluctuating estrogen levels in the fetal environment have long-term consequences regarding the risk of developing breast cancer during adult life. This is supported by laboratory rodent studies showing that perinatal exposure to pharmacological doses of diethylstilbestrol (DES) increases the incidence and decreases the latency period of mammary cancer. Among the xenoestrogens, bisphenol-A was chosen for these studies because of its widespread use and because it is found in 95% of the urine samples analyzed in a recent CDC study. Perinatal exposure to environmentally relevant doses of the xenoestrogen bisphenol A (BPA) alters the development of the rodent mammary gland and results in outcomes such as increased sensitivity to estrogens at puberty, increased ductal density in adulthood, and an increase in the number of structures where cancer arises. Using a rat mammary carcinogenesis model a pilot experiment was performed that revealed that perinatal exposure to low BPA doses induces intraductal hyperplasias. When challenged with a subcarcinogenic dose of nitrosomethylurea, only the BPA exposed animals developed neoplasias. Thus it is hypothesized that BPA administered perinatally will permanently alter tissue-specific patterns of gene expression by altering the methylation pattern of specific genes. These alterations will, in turn, affect development beyond the period of exposure to BPA, leading to an increase in susceptibility to breast cancer. Specific Aim 1 will compare the global pattern of DNA methylation in the mammary glands of vehicle and BPA-exposed animals and to construct a chromosomal methylation idiogram. The three components of Specific Aim 2 are to: 1) Determine the mRNA expression profiles of the BPA-treated mammary glands by DNA microarray analysis and to map the loci of differentially expressed genes on the rat chromosomal ideogram; 2) Identify candidate genes that are differentially expressed according to the mRNA microarray analysis that map onto the BPA-methylated or demethylated chromosomal regions; and 3) Narrow the set of candidate genes by bioinformatics techniques (molecular pathway and ontology analysis). The most promising candidate(s) will be probed in detail using bisulfite mapping of the methylated CpG dinucleotides. If a causal link is found between perinatal BPA exposure and alterations in gene methylation, this work will provide testable hypotheses connecting BPA-induced gene marking and propensity to develop mammary gland neoplasia. If the hypothesis is consistent with the result, this will constitute a major shift in emphasis from adult exposures to in utero exposures. This will also have a great impact on the way we study risk factors and conduct epidemiological studies; it may even influence public policy about breast cancer prevention.

描述（由申请人提供）： 在过去的50年里，在欧洲和美国人群中观察到子宫平滑肌瘤、睾丸癌和乳腺癌的发病率增加，这促使科学家们假设产前暴露于环境雌激素可能是这些肿瘤的根本原因。流行病学研究表明，胎儿环境中雌激素水平的波动对成年后患乳腺癌的风险有长期影响。实验室啮齿动物研究支持这一点，研究表明，围产期暴露于药理剂量的己烯雌酚（DES）会增加乳腺癌的发病率，并缩短乳腺癌的潜伏期。 在异种雌激素中，双酚A被选择用于这些研究，因为它的广泛使用，并且因为它在最近CDC研究中分析的95%的尿液样本中被发现。围产期暴露于环境相关剂量的异雌激素双酚A（BPA）会改变啮齿动物乳腺的发育，并导致诸如青春期对雌激素敏感性增加、成年期导管密度增加以及癌症发生的结构数量增加等结果。使用大鼠乳腺癌发生模型进行了初步实验，结果表明，围产期暴露于低BPA剂量诱导导管内增生。当用亚致癌剂量的亚硝基甲基脲进行攻击时，只有BPA暴露的动物发生肿瘤。因此，假设围产期给予BPA将通过改变特定基因的甲基化模式永久改变组织特异性基因表达模式。这些改变反过来会影响BPA暴露期之后的发育，导致乳腺癌易感性增加。 具体目标1将比较溶剂和BPA暴露动物乳腺中DNA甲基化的总体模式，并构建染色体甲基化模式图。具体目标2的三个组成部分是：1）通过DNA微阵列分析确定BPA处理乳腺的mRNA表达谱，并绘制大鼠染色体表意图上差异表达基因的位点; 2）根据mRNA微阵列分析识别差异表达的候选基因，该分析映射到BPA甲基化或去甲基化的染色体区域; 3）利用生物信息学技术（分子通路和本体分析）缩小候选基因的范围。将使用甲基化CpG二核苷酸的亚硫酸氢盐图谱详细探测最有希望的候选物。如果发现围产期BPA暴露与基因甲基化改变之间存在因果关系，这项工作将提供可检验的假设，将BPA诱导的基因标记与发生乳腺肿瘤的倾向联系起来。如果假设与结果一致，这将构成重点从成人暴露到子宫内暴露的重大转变。这也将对我们研究风险因素和进行流行病学研究的方式产生重大影响;它甚至可能影响有关预防乳腺癌的公共政策。