Microenvironment and Genome Stability: Mouse Models

描述（由申请人提供）：细胞外微环境在维持组织稳态中起重要作用。来自细胞外基质（ECM）的信号已经显示出调节细胞分裂、转录和凋亡。我们最近发现，ECM也调节DNA双链断裂修复在人类和小鼠细胞培养模型。这些结果对肿瘤的发生和放射治疗具有潜在的意义。具体地，我们发现ECM在正确的环境（具有正确的细胞-细胞连接）中上调乳腺上皮细胞中的同源重组，但如果细胞是单个的（异常环境）则下调它。通过细胞表面上的21整联蛋白的信号传导对于ECM调节修复是必要的和足够的，并且在细胞培养物中通过这种信号传导改变了电离辐射诱导的修复复合物在双链断裂上的组装动力学。鉴于环境对于ECM如何调节DNA修复非常重要，在这里，我们建议开发小鼠模型，以在正确的环境中检查这种新途径：小鼠体内乳腺。这项建议旨在发展两套模式，以：1。间接测量细胞外基质对小鼠乳腺电离辐射诱导的双链断裂修复的影响，以及2.直接测量ECM对小鼠乳腺中核酸内切酶诱导的断裂的同源修复的影响，通过开发适当的小鼠模型，使我们能够在功能上下调或消除21整合素，并在体内进行双链断裂修复测定。开发小鼠模型对于在正确的背景下理解这一新途径至关重要，并且采取下一步必要措施将这些发现转化为临床以影响放射治疗。公共卫生相关性：将细胞外微环境如何调节与基因组稳定性相关的过程的研究结果从细胞培养模型转化为小鼠模型对于理解与致癌作用相关的新途径和用于治疗癌症的基于电离辐射的疗法是必要的。这里开发的模型可用于询问与乳腺癌和其他癌症相关的问题，并确定可预测放射治疗反应的组织特异性标记物。

DESCRIPTION (provided by applicant): The extracellular microenvironment plays a significant role in maintaining tissue homeostasis. Signals from the extracellular matrix (ECM) have been shown to regulate cell division, transcription, and apoptosis. We recently found that ECM also regulates DNA double-strand break repair in both human and mouse cell culture models. These results have potential implications for carcinogenesis and radiation therapy. Specifically, we found that ECM up- regulates homologous recombination in mammary epithelial cells in the right context (with correct cell-cell junctions) but downregulates it if the cells are single (aberrant context). Signaling through 21 integrin on the cell surface is necessary and sufficient for ECM to regulate repair, and kinetics of assembly of ionizing-radiation induced repair complexes on the double- strand breaks are altered by such signaling in cell culture. Given that context is so important for how ECM regulates DNA repair, here we propose to develop mouse models to examine this new pathway in the right context: the mouse mammary gland in vivo. This proposal aims to develop two sets of models to: 1. indirectly measure the effects of ECM on ionizing radiation- induced double-strand break repair in the mouse mammary gland, and 2. directly measure the effects of ECM on the homologous repair of an endonuclease-induced break in the mouse mammary gland, by developing the appropriate mouse models that will allow us to functionally downregulate or ablate 21 integrin and perform double-strand break repair assays in vivo. Developing mouse models is crucial for understanding this new pathway in the right context, as well as taking the next necessary step towards translating these findings to the clinic to affect radiation therapy. PUBLIC HEALTH RELEVANCE: Translating the findings on how the extracellular microenvironment regulates processes related to genome stability from cell culture models to mouse models is necessary for understanding a new pathway relevant to carcinogenesis and to ionizing-radiation based therapies used to treat cancers. The models developed here can be used to ask questions relevant to breast and other cancers and in determining tissue-specific markers that may predict responses to radiation therapy.