Genomic Analysis of Gene Copy Number in Thyroid Cancer

描述（由申请方提供）：特定基因拷贝数的变化有助于人类肿瘤的发生。比较基因组杂交cDNA微阵列（阵列CGH）是一种新兴的功能基因组学技术，用于检测这些遗传变化。使用阵列CGH，我们已经获得了广泛的基因扩增的初步证据，在多个，聚集的位点存在于甲状腺上皮癌的儿童谁暴露于电离辐射从切尔诺贝利事故，但没有在可比的甲状腺上皮癌从美国儿童缺乏已知的辐射暴露。我们假设基因组中存在一个位点池，通过低水平基因扩增对辐射作出反应。为了扩展我们的初步发现，并验证我们的假设，我们将收集和分析来自同一人群的新甲状腺癌病例。这一新材料将使我们能够获得有关甲状腺中辐射相关基因拷贝数变化的肿瘤特异性、暴露时年龄、肿瘤潜伏期和估计辐射剂量与基因拷贝数变化的关系的数据。利用人类基因组序列，我们将绘制基因组内这些明显辐射效应的相对敏感度。此外，我们将尝试通过利用报道的肿瘤相关扩增子中存在的长回文序列来增强阵列CGH技术。在阵列分析中，将富集长回文序列的探针与常规DNA片段进行比较。将选择性地使用新的人类BAC阵列来补充从cDNA阵列获得的数据，以在需要时更好地定义扩增子。最后，通过这些新获得的患者样本，我们将利用微阵列技术的力量来探索基因拷贝变化与基因表达水平的关系，并寻找在这些甲状腺癌中持续过表达的候选癌基因。该项目的完成将增强阵列CGH作为在全基因组范围内检测和绘制基因拷贝数变化的技术，并提供更完整的辐射诱导甲状腺瘤形成机制的描述。

DESCRIPTION (provided by applicant): Changes in copy-number of specific genes contributes to the development of human neoplasia. Comparative genomic hybridization to cDNA microarrays (array-CGH) is an emerging functional genomic technique for detecting these genetic changes. Using array-CGH we have obtained preliminary evidence of widespread gene amplification in multiple, clustered loci present in thyroid epithelial cancers from children who were exposed to ionizing radiation from the Chernobyl accident, but not in comparable thyroid epithelial cancers from US children lacking known radiation exposure. We hypothesize the existence of a pool of sites in the genome which respond to radiation by low level gene amplification. To extend our initial findings, and test our hypothesis, we will collect and analyze new thyroid cancer cases from the same population. This fresh material will allow us to obtain data regarding the tumor-specificity of radiation-associated gene copy number change in the thyroid, the relationship of age at exposure, tumor latency and estimated radiation dose on gene copy number change. Taking advantage of the human genome sequence, we will map relative sensitivity of these apparent radiation effects within the genome. Additionally we will attempt to enhance the array CGH techniques by exploiting the reported presence of long palindromes in tumor-associated amplicons. Probes enriched for long palindromes will be compared with conventional DNA fragments in array analysis. A new human BAC array will be used selectively to supplement data obtained from cDNA arrays to better define amplicons where needed. Finally, by means of these newly acquired patient samples, we will exploit the power of microarray technology to explore the relationship of gene copy change to gene expression levels, and to seek candidate oncogenes consistently over expressed in these thyroid cancers. Completion of this project will enhance array CGH as a technique for detecting and mapping changes in gene copy-number on a genome-wide scale, and provide a more complete description of mechanisms underlying radiation-induce thyroid neoplasia.