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

项目摘要 转移性肾透明细胞癌(CcRCC)无病生存率低，治疗选择有限。 由于对肿瘤机制的了解，ccrcc的唯一治疗方法已被阐明。 肾细胞癌中最常见的突变基因VHL(von Hippel-Lindau)的抑制作用。继VHL之后，第二个 CcRCC患者最常见的突变基因是多溴-1(PBRM1)，它是SWI/SNF(或BAF)的一个亚基 对于BRG1/BRM相关因子)染色质重构复合体，其亚单位在20%的 人类癌症。PBRM1的特征是六个顺序的溴结构域被认为可以结合乙酰化赖氨酸 并且是称为PBAF(多溴-1 BAF)的次要BAF亚复合体中的一个亚基。这个项目的总体目标是 建议确定PBRM1介导的染色质靶向PBAF复合体的机制和 这与ccRCC中对肿瘤抑制至关重要的基因的下游转录调控有何关系。 根据我们的初步数据，我们假设PBRM1的六个溴域中的几个是必需的 用于将PBAF复合体多价靶向位于基因组区域的多个组蛋白乙酰化位点 对参与细胞黏附和上皮维持的基因的调节很重要。在建议的 研究我们计划1)使用细胞分析和动物模型来确认和表征PBRM1是一种肿瘤 参与细胞黏附调节的抑制子，2)定义PBRM1状态如何预测治疗 已建立和建议的ccRCC药物的有效性，3)确定ccRCC中PBRM1的基因组结合部位，以及 PBAF介导的染色质重塑对转录的调节，以及4)确定组蛋白乙酰化 负责特定招募PBRM1和PBAF的人员。拟议的研究将大大增加我们的 了解肾脏肿瘤的发生机制，扩大对肾脏肿瘤的认识 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 肾癌治疗新靶点的直接证据。

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.