The Role of Thoc1 in Normal Development and Cancer

这项应用的长期目标是了解thod基因的正常功能，并 评估其作为癌症治疗和预后分子靶点的潜在适宜性。THOD编码一个 蛋白质(PThocI)，最近被发现是进化上保守的TREX的一个组成部分 很复杂。Trex是一组基因有效转录延长所必需的，而且它在物理上 将延伸与RNA加工和核出口过程结合在一起。THOD的酵母同源异构体 不是生存所必需的，但这种基因的丢失会导致细胞寿命缩短，生长速度降低，以及 对DNA损伤的敏感度增加。同样，pThod缺失的人类癌细胞表现出减少 生长、活力和对基因毒性化疗药物的抵抗力。相比之下，正常分化的细胞 相对不受pThod丢失的影响。THOD正常发育的生理要求 而癌症尚未在多细胞生物体中进行活体评估。我们假设癌细胞 是唯一依赖于生长和生存能力的表达的，特别是在存在 DNA损伤。为检验该假设而提出的一般实验方法是测量 利用基因工程技术研究pThod缺失对正常发育和恶性转化的影响 乳腺癌的等位基因和自体小鼠模型。提出了四个具体目标：1)测试 PThod耗竭是否能抑制体外恶性转化。2)确定pThod是否 衰竭会影响正常的乳腺发育。3)确定pThod是否耗尽 在体内抑制乳腺癌的发生。4)评估pThod水平是否影响 乳腺癌到基因毒性治疗。癌细胞积累的遗传和表观遗传改变 赋予它们不必要的扩散潜力，但也给它们带来独特的脆弱性。因此，就是这样 有可能识别出需要的基因。癌细胞的活性，但不是正常细胞。是这样的 合成致命性基因相互作用识别有望产生疗效的潜在分子靶点 对癌细胞有更强的特异性。成功完成拟议的研究将提供原则证明 THOD是这样一个分子靶子。由于pThod是新发现的TREX复合体的一个组成部分， 它具有一种新的作用机制。基于靶向pThod的治疗和诊断是 有望产生新的临床反应，获得新的联合治疗机会，并预测预后 可能与当前使用的标准无关的信息。拟议的研究与以下方面高度相关 人类健康，因为对癌细胞具有更强特异性的新的分子靶向治疗显然是 需要的。提议的实验将决定pThod是否是开发的有前途的目标 新的治疗方法和预后测试。

The long-term objectives of this application are to understand the normal function of the Thod gene and to assess its potential suitability as a molecular target for cancer therapy and prognosis. Thod encodes a protein (pThocI) that has recently been identified as a component of the evolutionarily conserved TREX complex. TREX is required for the efficient transcriptional elongation of a subset of genes, and it physically couples elongation to the processes of RNA processing and nuclear export. The yeast orthologue of Thod is not essential for viability, but loss of this gene causes reduced cellular lifespan, reduced growth rate, and increased sensitivity to DNA damage. Similarly, human cancer cells depleted of pThod exhibit reduced growth, viability, and resistance to genotoxic chemotherapeutics. In contrast, normal differentiated cells are relatively unaffected by loss of pThod. The physiological requirements for Thod in normal development and cancer have yet to be assessed in vivo in a multicellular organism. We hypothesize that cancer cells are uniquely dependent on Thod expression for growth and viability, particularly in the presence of DNA damage. The general experimental approach proposed for testing the hypothesis is to measure the effects of pThod loss on normal development and malignant transformation using genetically engineered Thod alleles and autochthonous mouse models of breast cancer. Four specific aims are proposed: 1) Test whether pThod depletion inhibits malignant transformation in vitro. 2) Determine if pThod depletion affects normal mammary gland development. 3) Ascertain whether pThod depletion inhibits breast carcinogenesis in vivo. 4) Assess whether pThod levels influence the response of breast cancer to genotoxic therapy. Cancer cells accumulate genetic and epigenetic alterations that endow them with unwanted proliferative potential, but also burden them with unique vulnerabilities. Thus it is possible to identify genes that are required for. the viability of cancer cells, but not normal cells. Such synthetic lethal genetic interactions identify potential molecular targets for therapy that promise to yield greater specificity for cancer cells. Successful completion of the proposed study will provide proof of principle that Thod is such a molecular target. Since pThod is a component of the newly discovered TREX complex, it functions with a novel mechanism of action. Therapies and diagnostics based on targeting pThod are expected to yield novel clinical responses, opportunities for novel combination therapies, and prognostic information potentially independent of currently used criteria. The proposed research is highly relevant to human health because new molecularly targeted therapies with greater specificity for cancer cells are clearly needed. The experiments proposed will determine whether pThod is a promising target for the development of new therapies and prognostic tests.