PBRM1 bromodomain missense mutations in ccRCC vascular signaling

项目总结 肾透明细胞癌(CcRCC)是肾细胞癌最常见的亚型。虽然 早期发现和手术治疗效果良好，约30%的患者患有 转移性疾病。这突出了提高对生物化学的了解和针对性的必要性 慢性肾细胞癌的治疗选择。摘要肾细胞癌是一种独特的血管性癌，由von Hippel-Lindau基因突变引起。 (VHL)基因，编码降解缺氧的泛素连接酶的底物识别亚单位- 低氧诱导因子-α(HIF-α)转录因子。VHL丢失导致核HIF-α积聚和 下游促血管生成基因靶点的异常表达可能是以HIF-2α偏向的方式。因此， CcRCC肿瘤对抗血管生成治疗特别敏感，尽管有效，但与 对病人有很大的不良毒性。最近的临床试验表明，基因突变 多溴-1(Polybromo-1，PBRM1)是一种表观遗传性乙酰赖氨酸阅读器蛋白，在慢性肾细胞癌中常见突变，与 改善抗血管生成治疗的结果。然而，这些研究假设所有的PBRM1突变 是功能丧失，忽视了大约15%的ccRCC相关PBRM1突变是错误的 突变，产生全长蛋白质，具有一系列未知的结构和功能影响。 CcRCC相关的PBRM1错义突变聚集在溴域(BDS)中，其功能域是 结合组蛋白和其他核蛋白和核酸中的乙酰赖氨酸残基的PBRM1。因此，a 更好地了解ccRCC中PBRM1 BD错义突变对生化的影响对于促进 PBRM1作为预测患者对抗血管生成治疗反应的生物标志物，因此无反应 患者可以避免不必要的治疗毒性，并寻求替代治疗。这一团契将 阐明ccRCC相关PBRM1 BD错义突变对蛋白质稳定性的生化影响 和乙酰化组蛋白结合功能，并确定PBRM1在调节HIF-2α和 血管生成途径。目标1将确定哪些PBRM1 BD错义突变在生化上是良性的或 计算预测与生物物理检测相结合对蛋白质结构和功能的危害 验证。目的2确定PBRM1BD错义突变对缺氧诱导因子-2α和血管生成的影响 评估低氧诱导因子-2α转录输出、低氧诱导因子-2α启动子可及性和血管生成的通路调控 在ccRCC细胞检测中的潜力。这项奖学金解决了生物化学基础方面的知识空白。 CcRCC发病机制的总体目标是促进标准CcRCC治疗的最有效使用 医疗模式。成功完成这一奖学金将进一步推动精准医学的方法 通过提高PBRM1突变状态作为细微差别和预测性生物标志物预防慢性肾细胞癌的治疗 不必要的病人药物暴露。

PROJECT SUMMARY Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma. Although outcomes are favorable with early detection and surgery, approximately 30% of patients present with metastatic disease. This highlights the need for an improved biochemical understanding of and targeted therapeutic options for ccRCC. ccRCC is a uniquely vascular cancer due to mutations in the von Hippel-Lindau (VHL) gene, which encodes the substrate recognition subunit of a ubiquitin ligase that degrades hypoxia- inducible factor-α (HIF-α) transcription factors in normoxia. VHL loss results in nuclear HIF-α accumulation and aberrant expression of downstream pro-angiogenic gene targets in a likely HIF-2α-biased manner. Thus, ccRCC tumors are uniquely susceptible to anti-angiogenic therapies, which though effective, are associated with substantial undesirable toxicities for patients. Recent clinical trials have demonstrated that mutations in Polybromo-1 (PBRM1), an epigenetic acetyl-lysine reader protein commonly mutated in ccRCC, correlate with improved outcomes for anti-angiogenic therapies. However, these studies presume that all PBRM1 mutations are loss-of-function and neglect to consider that ~15% of ccRCC-related PBRM1 mutations are missense mutations, generating full-length proteins with a spectrum of undetermined structural and functional impacts. ccRCC-associated PBRM1 missense mutations cluster in bromodomains (BDs), the functional domains of PBRM1 that bind acetyl-lysine residues in histones and other nuclear proteins and nucleic acids. Therefore, a better knowledge of the biochemical impacts of PBRM1 BD missense mutations in ccRCC is critical to promote PBRM1 as a predictive biomarker for patient response to anti-antiangiogenic therapies, so that non-responding patients can avoid unnecessary therapeutic toxicity and seek alternative treatments. This fellowship will elucidate the biochemical impacts of ccRCC-associated PBRM1 BD missense mutations on protein stability and acetylated histone binding function and determine the role of PBRM1 in the regulation of the HIF-2α and angiogenesis pathways. Aim 1 will identify which PBRM1 BD missense mutations are biochemically benign or deleterious for protein structure and function by integrating computational prediction with biophysical assay validation. Aim 2 will determine the effects of PBRM1 BD missense mutations on HIF-2α and angiogenesis pathway regulation by assessing HIF-2α transcriptional output, HIF-2α promoter accessibility, and angiogenic potential in ccRCC cellular assays. This fellowship addresses knowledge gaps in the biochemical basis of ccRCC pathogenesis with the overall goal to promote the most effective use of standard ccRCC treatment modalities. Successful completion of this fellowship will further precision medicine approaches for the treatment of ccRCC by advancing PBRM1 mutational status as a nuanced and predictive biomarker to prevent unnecessary patient drug exposures.