Investigating essential chromatin regulators in cancers with SWI/SNF mutations

项目摘要 编码SWI/SNF染色质重塑复合物亚基的基因在近25%的癌症中发生突变。 此外，SWI/SNF亚基中的种系突变导致几种神经发育障碍。然而，在这方面， 这些突变驱动癌症和疾病的机制知之甚少。SWI/SNF 复合物在增强子和启动子处调动核小体以调节转录。双等位基因失活 SMARCB 1是一种编码SWI/SNF复合物亚基的基因，可导致儿童横纹肌样瘤（RT）。这些高度 侵袭性软组织肿瘤发生在婴儿和幼儿中，并且具有极差的结果。自RT 基因组是二倍体，缺乏其他突变，它们是研究SWI/SNF特异性机制的理想选择。 癌症和鉴定新的治疗靶点。我的导师和他的合作者发起了儿科 癌症依赖性项目，以确定新的驱动程序和治疗目标，在儿科癌症，包括RT。 在10种RT细胞系中进行全基因组CRISPR筛选，与800多种其他癌细胞系进行比较 揭示了SMARCB 1缺陷RT特异性依赖于生存的新基因。该提案寻求 研究这种假定的染色质调节因子的功能，并确定为什么它构成了一个 该基因的过表达与几种癌症的不良预后有关 因此已经在进行药理学努力以开发化学抑制剂。有趣的是，初步 实验表明，这种蛋白质可以控制组蛋白翻译后修饰（PTM）， 通过SWI/SNF复合物和基因表达进行重塑。了解RT细胞为什么依赖于这种蛋白质 将揭示染色质调节的新机制，并可能在细胞凋亡中确定新的治疗靶点。 这些致命的癌症。我的中心假设是，这种蛋白质控制组蛋白PTM， 缺乏SMARCB 1的SWI/SNF复合物的唯一家族的染色质募集，从而使其 这项建议将调查如何这种调节，缺乏酶活性，控制这些 组蛋白PTM及其如何影响染色质可及性。此外，它将确定该监管机构如何 影响SWI/SNF复合物控制的重塑和基因表达。总的来说，这项建议将 揭示这种相对未被充分研究的蛋白质的功能，为染色质功能是如何 调节，解释为什么RT选择性地依赖于这种蛋白质生存，并可能确定一种新的 致命的小儿横纹肌样瘤的治疗靶点。此外，该提案旨在解决我的 培养目标是熟练掌握染色质生物学的实验和计算。

PROJECT SUMMARY Genes that encode subunits of SWI/SNF chromatin remodeling complexes are mutated in nearly 25% of cancers. Additionally, germline mutations in SWI/SNF subunits cause several neurodevelopmental disorders. However, the mechanisms by which these mutations drive cancer and disease are poorly understood. SWI/SNF complexes mobilize nucleosomes at enhancers and promoters to modulate transcription. Biallelic inactivation of SMARCB1, a gene encoding a SWI/SNF complex subunit, causes pediatric rhabdoid tumors (RTs). These highly aggressive soft tissue tumors occur in infants and young children and have extremely poor outcomes. Since RT genomes are diploid and lack other mutations, they are ideal for studying SWI/SNF-specific mechanisms driving cancer and for identifying novel therapeutic targets. My mentor and his collaborators initiated the Pediatric Cancer Dependency Project to identify novel drivers and therapeutic targets in pediatric cancers, including RT. Performing genome-wide CRISPR screens in 10 RT cell lines compared to over 800 other cancer cell lines revealed a novel gene that SMARCB1-deficient RT specifically depend upon for survival. This proposal seeks to investigate the function of this putative chromatin regulator and to determine why it constitutes a specific dependency in RT. Overexpression of this gene is associated with poor prognosis in several cancers and thus pharmacological efforts are already underway to develop chemical inhibitors. Intriguingly, preliminary experiments suggest that this protein may control histone post-translational modifications (PTMs) that dictate remodeling by SWI/SNF complexes and gene expression. Understanding why RT cells depend on this protein for survival will reveal novel mechanisms of chromatin regulation and may identify a new therapeutic target in these lethal cancers. My central hypothesis is that this protein controls histone PTMs and is required for the chromatin recruitment of the sole family of SWI/SNF complexes that lack SMARCB1, thus making it essential in RT. This proposal will investigate how this regulator, which lacks enzymatic activity, controls these histone PTMs and how this influences chromatin accessibility. Additionally, it will determine how this regulator influences remodeling and gene expression controlled by SWI/SNF complexes. Collectively, this proposal will uncover the function of this relatively understudied protein, provide novel insight into how chromatin function is regulated, explain why RTs selectively depend on this protein for survival, and potentially identify a novel therapeutic target in the lethal pediatric rhabdoid tumor. Additionally, this proposal is designed to address my training goal of becoming proficient in studying chromatin biology both experimentally and computationally.