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着重要作用。来自细胞外基质（ECM）的信号已被证明可以调节细胞分裂、转录和凋亡。我们最近发现ECM在人和小鼠细胞培养模型中也调节DNA双链断裂修复。这些结果对致癌和放射治疗具有潜在的意义。具体来说，我们发现ECM在正确的环境下（具有正确的细胞-细胞连接）上调乳腺上皮细胞的同源重组，但如果细胞是单一的（异常环境），则下调。细胞表面通过21整合素发出的信号对于ECM调节修复是必要和充分的，并且在细胞培养中，这种信号会改变电离辐射诱导的双链断裂上修复复合物的组装动力学。考虑到环境对于ECM如何调节DNA修复是如此重要，在这里，我们建议开发小鼠模型，在正确的环境中检查这一新途径：小鼠乳腺。本提案旨在开发两套模型：1。间接测量ECM对电离辐射诱导的小鼠乳腺双链断裂修复的影响；直接测量ECM对小鼠乳腺内切酶诱导的断裂同源修复的影响，通过开发适当的小鼠模型，使我们能够功能性下调或消融21整合素，并在体内进行双链断裂修复试验。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，同时也对将这些发现转化为临床影响放射治疗迈出了下一步。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和用于治疗癌症的基于电离辐射的疗法相关的新途径是必要的。这里开发的模型可以用来询问与乳腺癌和其他癌症相关的问题，并确定可能预测放射治疗反应的组织特异性标记。

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.