Analysis of STAG2 Inactivation and Aneuploidy in Human Cancer

描述（由申请人提供）：区分癌细胞与正常细胞的最常见特征之一是存在非整倍性。我们最近发现了在相当大部分的恶性人类肿瘤中非整倍性的原因-STAG 2基因的缺失、体细胞突变和表达丧失（Science 336：1039-1043，2011）。编码的STAG 2蛋白是多蛋白粘附素复合物的关键组分，其调节姐妹染色单体的粘附并有助于确保有丝分裂期间染色体的忠实分离。在这项资助中，我们提出了一个多方面的努力，以进一步确定STAG 2失活导致染色体不稳定，非整倍性和癌症的机制。在目标#1中，我们将评估STAG 2中肿瘤源性突变对姐妹染色单体凝聚力和蛋白质-蛋白质相互作用的影响。目的是功能性地评估STAG 2中的突变，以揭示STAG 2在肿瘤发生过程中丢失的关键活性。在目标#2中，我们将确定STAG 2截短突变对粘附素的蛋白质组成及其在细胞周期的不同阶段与染色质相互作用的能力的影响。这些实验将使我们能够确定STAG 2失活导致染色体不稳定性和非整倍性的关键机制。在目标#3中，我们将确定STAG 2失活对人星形胶质细胞和GBM细胞中转化的启动和维持的作用。这些实验将使我们能够确定STAG 2失活是否导致对恶性转化的易感性增强。在目标#4中，我们将确定STAG 2中的突变是否导致GBM细胞对电离辐射和DNA损伤化疗药物敏感。拟议研究计划的广泛目标是确定STAG 2失活导致染色体不稳定性，非整倍体和细胞转化的机制，从而有可能开发用于鉴定特异性靶向非整倍体细胞的新型抗癌疗法的策略。

DESCRIPTION (provided by applicant): One of the most common features that distinguishes cancer cells from normal cells is the presence of aneuploidy. We have recently discovered a cause of aneuploidy in a substantial fraction of malignant human tumors - deletions, somatic mutations, and loss of expression of the STAG2 gene (Science 336:1039-1043, 2011). The encoded STAG2 protein is a key component of the multi-protein cohesin complex which regulates sister chromatid cohesion and helps ensure faithful chromosome segregation during mitosis. In this grant we propose a multi-faceted effort to further define the mechanism through which STAG2 inactivation leads to chromosomal instability, aneuploidy, and cancer. In Aim #1 we will evaluate the effects of tumor-derived mutations in STAG2 on sister chromatid cohesion and protein-protein interactions. The goal is to functionally evaluate mutations in STAG2 to reveal the key activities of STAG2 that are lost during tumorigenesis. In Aim #2 we will determine the effect of STAG2 truncating mutations on the protein composition of cohesin and its ability to interact with chromatin at different phases of the cell cycle. These experiments wil enable us to identify key mechanisms by which STAG2 inactivation leads to chromosomal instability and aneuploidy. In Aim #3 we will determine the role of STAG2 inactivation on the initiation and maintenance of transformation in human astrocytes and GBM cells. These experiments will enable us to determine if STAG2 inactivation results in enhanced susceptibility to malignant transformation. In Aim #4 we will determine if mutations in STAG2 cause GBM cells to be sensitized to ionizing radiation and DNA damaging chemotherapeutic drugs. The broad goal of the proposed research program is to determine the mechanism through which STAG2 inactivation leads to chromosomal instability, aneuploidy, and cellular transformation, making it possible to develop strategies for identifying novel anticancer therapeutics that specifically target aneuploid cells.