Mechanisms of RET/PTC rearrangements in thyroid cancer

甲状腺癌中RET/PTC重排的机制

• 批准号: 6909115
• 负责人: YURI E NIKIFOROV
• 金额: $ 22.22万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6909115
• 关键词: DNA damage; age difference; cell nucleus; clinical research; confocal scanning microscopy; enzyme activity; fluorescent in situ hybridization; gene rearrangement; human subject; ionizing radiation; neoplasm /cancer genetics; oncogenes; pediatric neoplasm /cancer; polymerase chain reaction; protein tyrosine kinase; protooncogene; radiation carcinogen; radiation carcinogenesis; radiation genetics; radiation related neoplasm /cancer; thyroid neoplasm

DESCRIPTION: (Scanned from the applicant's abstract) Thyroid cancer is the most common form of solid neoplasms known to be associated with radiation exposure. However, the mechanisms of radiation-induced carcinogenesis are not well understood. The high prevalence of rearrangements of the RET gene has been recently found in post-Chernobyl papillary thyroid carcinomas and in thyroid tumors from patients exposed to therapeutic external radiation. The positions of breakpoints sites in the RET and ELEI genes identified in post-Chemobyl tumors with RETPTC3 rearrangements suggested that these two genes may be aligned across from each other in the nucleus at the time of DNA breaks (Nikiforov et al., Oncogene, 1999). Consistent with this idea, we found that one pair of RET and H4 genes (contributing to RET/PTCI rearrangement) was juxtaposed in 35 percent of inter-phase nuclei of normal thyroid cells. These data suggest that two potentially recombinogenic chromosomal loci may be contiguous to each other in the nucleus predisposing to generation of rearrangement by adjacent double-strand DNA breaks produced by ionizing radiation or other genotoxic agents. The main goal of the current proposal is to explore the role of nuclear architecture and gene proximity in generation of chromosomal rearrangements after radiation exposure. We propose to use two-color FISH and three-dimensional confocal laser-scanning microscopy to determine the frequency of physical proximity of genes, contributing to the major types of RET/PTC rearrangements, in normal human thyroid follicular cells and in other cell lineages. We will establish whether chromosomal organization with respect to these loci is cell-type specific, age-dependent, or varies with cell cycle stage. Any of these parameters could explain in part the high prevalence of thyroid cancer after irradiation, and the higher susceptibility of children. Then, we will expose cultured cells to different doses of ionizing radiation to test directly the relationship between gene proximity and the frequency of radiation-induced RET/PTC rearrangements in vitro. These studies will extend our understanding of the mechanisms of radiation-induced carcinogenesis in the thyroid gland. In addition, they are likely to have importance for a broad range of chromosomal rearrangements found in cancer.

描述：（从申请人的摘要中扫描）甲状腺癌是最常见的癌症。 已知与辐射暴露有关的常见实体肿瘤形式。 然而，辐射致癌的机制尚不十分清楚。 明白了。 RET 基因重排的发生率很高 最近在切尔诺贝利事故后的甲状腺乳头状癌和甲状腺中发现 来自接受治疗性外部辐射的患者的肿瘤。职位 Chemobyl 后鉴定的 RET 和 ELEI 基因中断点位点的数量 具有 RETPTC3 重排的肿瘤表明这两个基因可能是 DNA 断裂时在细胞核中相互排列 （Nikiforov 等人，Oncogene，1999）。与这个想法一致，我们发现 一对 RET 和 H4 基因（有助于 RET/PTCI 重排） 并列于正常甲状腺细胞 35% 的间期细胞核中。这些 数据表明两个潜在的重组染色体位点可能是 在细胞核中彼此相邻，易于产生 电离产生的相邻双链 DNA 断裂引起的重排 辐射或其他遗传毒性物质。当前提案的主要目标是 探索核结构和基因邻近性在生成中的作用 辐射暴露后染色体重排。我们建议使用 双色 FISH 和三维共焦激光扫描显微镜 确定基因物理接近的频率，有助于 正常人甲状腺滤泡细胞中 RET/PTC 重排的主要类型 以及其他细胞谱系。我们将确定染色体组织是否 这些位点是细胞类型特异性的、年龄依赖性的或随细胞类型而变化 细胞周期阶段。这些参数中的任何一个都可以部分解释高 放射线照射后甲状腺癌的患病率较高，且易感性较高 儿童。然后，我们将培养的细胞暴露于不同剂量的电离 辐射直接测试基因邻近度和基因之间的关系 体外辐射诱导的 RET/PTC 重排频率。这些研究 将加深我们对辐射诱发机制的理解 甲状腺癌发生。此外，他们很可能有 对于癌症中发现的广泛染色体重排具有重要意义。