Mechanisms of gene amplification in human cancers

项目总结 我们提出的研究的目标是确定结构染色体的潜在机制。 人类肿瘤中的异常和基因组扩增。基因组(基因)扩增是关键之一。 肿瘤发生和发展的驱动力。在乳腺癌中有几个重复扩增的癌基因位点 基因组。为了对抗癌基因扩增的结果，人们付出了巨大的努力，比如 作为过度表达的蛋白质和下游信号通路。到目前为止，几乎没有人注意到 潜在扩增机制的翻译潜力。我们的长期目标是将 从基因组扩增机制获得控制侵袭性肿瘤的知识。 含有癌基因的基因组片段可以积累在染色体内或 染色体外以环形微染色体的形式存在。因此，识别单个分子过程 控制基因组扩增似乎具有挑战性。我们已经证明，DNA复制中的缺陷是 基因组扩增的关键启动事件。为了忠实地复制人类庞大的基因组，复制 机器(叉子)必须移动很长的距离并克服一些自然障碍，例如DNA 二级结构和与转录机器的碰撞。肿瘤细胞和癌前病变通常 在这些障碍下，无法保护复制分叉，结果，分叉停滞和崩溃(复制压力)。 折叠的叉子变成带有重组DNA末端的断叉，这可能导致染色体 异常和基因组扩增。 尽管我们现在认识到复制应激的关键作用，但分子机制从停滞/崩溃 通往经常性基因组扩增的分叉仍然难以捉摸。这些信息对于确定新的目标至关重要。 控制基因组扩增。要发生重复的基因组扩增，必须有自然障碍 靠近一个反复阻碍复制分叉运动的癌基因。我们假设特定的基因座， 自然的基因组应激阻碍复制叉子的移动，并护送崩溃的叉子进入重现的基因组 放大。我们已经在两个重复扩增的基因组座位8q24中发现了候选障碍。 癌基因(AIM1)和带有ERBB2癌基因的17q12-21(AIM2)，并将探讨其分子机制 从停滞的叉子到基因组扩增的一步一步。我们的结果将揭示一种特定的相互作用 在扩增机制和局部基因组背景之间，这可能为我们提供一种新的机制 具有治疗潜力的洞察力。

PROJECT SUMMARY The goal of our proposed study is to determine the mechanisms underlying structural chromosome abnormalities and genomic amplification in human tumors. Genomic (gene) amplification is one of the key drivers of tumor development and progression. There are several, recurrently amplified oncogene loci in the genome. Enormous efforts have been directed to antagonizing the outcomes of oncogene amplification, such as overexpressed proteins and downstream signaling pathways. So far, little attention has been paid to the translational potential of the underlying amplification mechanisms. Our long-term goal is to translate the knowledge from genomic amplification mechanisms for controlling aggressive tumors. A genomic segment harboring an oncogene can accumulate either within chromosomes or extrachromosomally in the form of circular minichromosomes. Therefore, identifying a single molecular process for controlling genomic amplification appears challenging. We have shown that a defect in DNA replication is a crucial initiating event for genomic amplification. To faithfully duplicate the large human genome, replication machinery (forks) must travel a long distance and overcome a number of natural obstacles, such as DNA secondary structures and collisions with transcription machinery. Tumor cells and pre-cancerous lesions often fail to protect replication forks at these obstacles, and as a result, forks stall and collapse (replication stress). Collapsed forks become broken forks with recombinogenic DNA ends, which can lead to chromosomal abnormalities and genomic amplification. Although we now recognize the crucial role of replication stress, molecular mechanisms from stalled/collapsed forks to recurrent genomic amplification remain elusive. Such information is essential to identify new targets to control genomic amplification. For recurrent genomic amplification to occur, there must be a natural obstacle near an oncogene that repeatedly impedes replication fork movements. We hypothesize that locus-specific, natural genomic stress impedes replication fork movements and escorts collapsed forks into recurrent genomic amplification. We have identified candidate obstacles in two recurrently-amplified genomic loci, 8q24 with MYC oncogene (AIM1) and 17q12-21 with ERBB2 oncogene (AIM2), and will investigate molecular mechanisms step-by-step from stalled/collapsed forks to genomic amplification. Our results will reveal a specific interaction between amplification mechanisms and local genomic context, which may provide us a novel mechanistic insight with therapeutic potential.