The tumor suppressive role of PBRM1, the bromodomain-containing subunit of the PBAF chromatin remodeling complex

项目摘要 转移性透明细胞肾细胞癌（ccRCC）无病生存率低，治疗选择有限。 ccRCC的唯一治疗方法已被阐明为对肿瘤的机制理解的结果。 VHL（von Hippel-Lindau）抑制，VHL是ccRCC中最常见的突变基因。在VHL之后，第二个 ccRCC患者中最常见的突变基因是多溴-1（PBRM 1），SWI/SNF（或BAF）的亚基 对于BRG 1/BRM相关因子）染色质重塑复合物，其亚基在20%的 人类癌症PBRM 1的特征在于六个连续的溴结构域，建议结合乙酰化赖氨酸 并且是称为PBAF（聚溴-1 BAF）的次要BAF亚复合物中的亚基。这个项目的总体目标是 建议是确定PBRM 1介导的PBAF复合物的染色质靶向机制， 这与ccRCC中对肿瘤抑制重要的基因的下游转录调控有何关系。 基于我们的初步数据，我们假设PBRM 1的六个溴结构域中的几个是必需的， 用于PBAF复合物多价靶向位于基因组区域的多个组蛋白乙酰化位点 对于调节参与细胞粘附和上皮维持的基因很重要。拟议 我们的研究计划是：1）使用细胞分析和动物模型来确认和表征PBRM 1作为肿瘤 2）定义PBRM 1状态如何预测治疗性 确定和提出的ccRCC药物的功效，3）鉴定ccRCC中PBRM 1的基因组结合位点， PBAF介导的染色质重塑的转录调控，以及4）定义组蛋白乙酰化 负责PBRM 1和PBAF的具体招募标记。这项研究将大大提高我们的 了解肾脏肿瘤发生的机制，并扩大我们对肿瘤的理解 BAF介导的染色质重塑的抑制机制。我们相信这项研究将提供 治疗肾癌的新治疗靶点的直接证据。

Project Summary Metastatic clear cell renal cell carcinoma (ccRCC) has low disease-free survival and limited therapeutic options. The only treatments for ccRCC have been elucidated as a result of mechanistic understanding of tumor suppression by VHL (von Hippel-Lindau), the most commonly mutated gene in ccRCC. After VHL, the second most commonly mutated gene in ccRCC patients is Polybromo-1 (PBRM1), a subunit of the SWI/SNF (or BAF for BRG1/BRM associated factors) chromatin remodeling complex, subunits of which are mutated in 20% of human cancers. PBRM1 is characterized by six sequential bromodomains proposed to bind acetylated lysines and is a subunit in a minor BAF subcomplex called PBAF (for Polybromo-1 BAF). The overall goal of this proposal is to determine the mechanism of PBRM1-mediated chromatin targeting of the PBAF complex and how that relates to downstream transcriptional regulation of genes important for tumor suppression in ccRCC. Based on our preliminary data, we hypothesize that several of the six bromodomains of PBRM1 are required for multivalent targeting of the PBAF complex to multiple histone acetylation sites located at genomic regions important for the regulation of genes involved in cell adhesion and epithelial maintenance. In the proposed study we plan to 1) Use cellular assays and animal models to confirm and characterize PBRM1 as a tumor suppressor involved in the regulation of cell adhesion, 2) Define how PBRM1 status predicts therapeutic efficacy of established and proposed ccRCC drugs, 3) Identify genomic binding sites for PBRM1 in ccRCC and the transcriptional regulation by PBAF-mediated chromatin remodeling, and 4) Define the histone acetylation marks responsible for specific recruitment of PBRM1 and PBAF. The proposed study will greatly increase our understanding of the mechanisms involved in renal tumorigenesis and expand our understanding of the tumor suppressive mechanisms of BAF-mediated chromatin remodeling. It is our belief that this study will provide direct evidence of novel therapeutic targets for treating renal cancer.