Mechanisms in Perinatal Carcinogenesis

围产期致癌机制

基本信息

批准号：
8157172
负责人：
Lucy M Anderson
金额：
$ 70.88万
依托单位：
DIVISION OF BASIC SCIENCES - NCI
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/8157172
关键词：
Perinatal Carcinogenesis

项目摘要

Perinatal exposures may lead to increased risk of childhood cancers, as well as those later in life. Preconceptional parental, transplacental, and/or neonatal exposures may be involved. Studies with animal models are utilized to increase understanding of underlying cellular and molecular mechanisms. We have been focusing on transgenerational effects of exposures and experiences of male mice on tumorigenesis and other endpoints in offspring. A possible mechanism of paternal effects on childhood cancer is male-mediated transgenerational carcinogenesis. Exposure of male mice to chromium(III), an environmental/occupational metal, results in increased neoplasms and other lesions in the offspring. The nature of these changes suggested hormonal involvement, and we have discovered alterations in serum glucose, corticosterone, IGF1, and the thyroid hormone T3 in the offspring. It is also important to discover the molecular mechanism in the sperm, by which changes-in-gene-expression signals are passed to offspring. Use of representational difference analysis, bisulfite sequencing, and pyrosequencing has revealed hypomethylation in the spacer-promoter region of the ribosomal RNA (rRNA) gene in sperm from Cr(III)-treated males. Ribosomal RNA is implicated in both growth and cancer. To test whether paternally-mediated effects are inherited by offspring, we have examined the gene in embryos and in tissues of young adult offspring, including liver and lung. Extensive statistical analyses of large numbers of litters and of offspring are now almost completed, and some surprising and interesing results are clear. Acidic saline, used as a vehicle for the Cr(III), also has had transgenerational effects. Importantly, offspring body weights and liver weights have been significantly increased as a result of the paternal treatments. The potential significance of this for several human diseases in addition to cancer is obvious. At the molecular level in studies of rRNA, single nucleotide polymorphisms, including one in the spacer-promoter and four alleles in the main promoter of the rRNA gene, are involved. The ratio of the alleles for the main promoter was actually changed by exposure of the fathers, selectively in the offspring lungs. This suggests tissue-specific genomic effects, either selective allelic expansion or gene conversion. If confirmed it will be a qualitatively new finding. The nature of the allele in the main promoter correlated with degree of methylation at five CpG sites in the spacer-promoter, in a tissue specific way. Degree of methylation was significantly affected by the paternal chromium treatment, in male offspring lungs. Importantly, these relationships between gene polymorphisms and gene methylation at a distant regulatory site were significantly modulated by treatment of the fathers. Since both the chromium(III), and the acid saline vehicle administered as a control, had clear effects, we looked for general, stressor-type effects in the males. Both chemical treatments were found to be stressors of the fathers, causing changes in serum corticosterone, insulin, leptin and glucose. Currently we are finding that these types of molecular changes also carry over into the F2 offspring, fathered by F1 males, that is, the grandchildren of the exposed males. Changes in the rRNA gene, both methylation and gene variant frequency, are greater than in the F1 mice This is particularly interesting in view of human epidemiology showing that experiences of grandfathers, for example amount of food available to them during certain intervals of childhood, affects risk of disease in their grandsons. To confirm these findings with another model and to simplify the experimental paradigm, we explored ways of exposing male mice directly to the stress hormone corticosterone. Preliminary trials have indicated that a key parameter is the age of these males at weaning, with different results obtained if the mice are weaned at 14 vs 21 days. This observation points to perinatal stress having a lasting effect on adult responses, a phenomenon worth study in its own right. Most consistent results were obtained with male weaned at 21 days. With such males, corticosterone treatment has an apparent effect on baseline weight and weight gain in the offspring. Statistical analysis of this result is in progress

围产期暴露可能会导致儿童癌症以及以后生活的风险增加。可能会涉及预感的父母，移植和/或新生儿暴露。使用动物模型的研究用于增加对潜在的细胞和分子机制的理解。我们一直专注于雄性小鼠暴露和经历对肿瘤发生和后代其他终点的经历的转世影响。父亲对儿童癌症作用的可能机制是男性介导的跨代癌发生。雄性小鼠暴露于铬（III）（一种环境/职业金属）导致后代肿瘤和其他病变增加。这些变化的性质表明激素受累，我们发现了血清葡萄糖，皮质酮，IGF1和甲状腺激素T3的改变。在精子中发现分子机制也很重要，将基因表达信号传递给后代。使用表示差异分析，亚硫酸盐测序和焦磷酸测序的使用揭示了来自CR（III）治疗的雄性的精子中核糖体RNA（RRNA）基因的间隔促促促启动区的低甲基化。核糖体RNA与生长和癌症有关。为了测试后代是否遗传了亲子介导的作用，我们检查了包括肝脏和肺在内的年轻成年后代的胚胎和组织中的基因。现在几乎完成了大量垃圾和后代的广泛统计分析，一些令人惊讶和相交的结果很明显。用作CR（III）的酸性盐水也具有转世作用。重要的是，由于父亲的治疗，后代体重和肝脏体重已显着增加。除癌症外，这对于几种人类疾病的潜在意义是显而易见的。在RRNA研究的分子水平上，涉及单核苷酸多态性，其中包括间隔促销子中的一个和RRNA基因的主要启动子中的四个等位基因。实际上，父亲在后代肺中有选择地改变了主要启动子的等位基因的比率。这表明组织特异性基因组效应，是选择性等位基因膨胀或基因转化率。如果确认，这将是一个质性的新发现。主启动子中等位基因的性质与隔离促销中五个CpG位点的甲基化程度相关，以组织特异性方式相关。男性后代肺部的父亲铬处理严重影响甲基化程度。重要的是，通过父亲的处理，可以显着调节基因多态性与基因甲基化之间的这些关系。由于铬（III）和作为对照的酸盐载体都具有明显的影响，因此我们在男性中寻找一般的压力型效果。发现两种化学处理都是父亲的应激源，导致血清皮质酮，胰岛素，瘦素和葡萄糖的变化。目前，我们发现，这些类型的分子变化也延续到了由F1雄性（即暴露的雄性的孙子）父母的F2后代。 RRNA基因的变化（甲基化和基因变异频率）都比F1小鼠大得多，鉴于人类流行病学的观点表明，祖父的经历，例如在童年时期的一定时间间隔内可用的食物，会影响孙子中疾病的风险。为了用另一个模型确认这些发现并简化了实验范式，我们探索了将雄性小鼠直接暴露于应激激素皮质酮的方法。初步试验表明，关键参数是断奶时这些雄性的年龄，如果将小鼠断奶为14 vs 21天，则获得不同的结果。该观察结果表明，围产期压力对成人反应具有持久影响，这本身就是值得研究的现象。大多数一致的结果是在21天的男性断奶中获得的。使用这种雄性，皮质酮治疗对基线体重和后代体重增加有明显的影响。该结果的统计分析正在进行中