Role of ubiquitylation in renal cancer

描述（由申请方提供）：肾癌占美国成人恶性肿瘤的3%，是癌症死亡的第6大原因。在本申请中，我们建议检查致癌过程的分子基础，导致最常见的肾癌形式，肾透明细胞癌（RCC）。RCC肿瘤发生与von Hippel-Lindau肿瘤抑制蛋白（pVHL）功能丧失之间存在明确的联系。已知这种致癌作用可以通过破坏HIF α泛素化来介导。然而，在本申请中，我们将扩展我们以前的工作，涉及一种新的pVHL依赖性信号通路在RCC的发展：羟基化的大亚基RNA聚合酶II（RNAPII），Rpb 1，其随后的泛素化的pVHL肿瘤抑制复合物。我们的工作假设是，P1465羟基化和pVHL依赖的泛素化Rpb 1提供微调的RNAPII复合物的转录活性，从而导致基因表达的模式，促进适当的反应，环境变化（如氧化应激）。我们认为，这种微调的损失导致RNAPII的功能失调，从而导致肿瘤发生。这项工作的总体目标是了解pVHL依赖的Rpb 1羟基化和泛素化的机制，并评估这一过程的中断在肿瘤发生中发挥的作用。为了实现这一点，我们将1）鉴定泛素和Rpb 1中的赖氨酸，它们以P1465依赖的方式参与Rpb 1对氧化应激的pVHL依赖性多聚泛素化; 2）鉴定参与Rpb 1羟基化的脯氨酰羟化酶; 3）确定不经历pVHL依赖性羟基化和泛素化的Rpb 1突变体的致癌特性;和4）评估与正常肾组织相比，人RCC肿瘤中Rpb 1羟基化和泛素化的状态。如果在早期阶段诊断出癌症，RCC患者的预后要好得多;然而，早期诊断在RCC中并不常见，因为患者通常直到疾病的晚期才出现症状。由于这项研究探索了一种新的疾病发展的生化机制，它可以通过两种方式改善RCC患者的预后：1）通过促进治疗RCC的新药的开发，2）通过鉴定新的遗传标记，可用于鉴定有患RCC风险的个体。

DESCRIPTION (provided by applicant): Renal cancer accounts for 3% of adult malignancies in the US, and is the 6th leading cause of cancer mortality. In this application, we propose to examine the molecular basis of the oncogenic process leading to the most common form of kidney cancer, renal clear cell carcinoma (RCC). There is a well established link between RCC oncogenesis and the loss of function of the von Hippel-Lindau tumor suppressor protein (pVHL). It is known that this oncogenic effect can be mediated through disruption of HIFa ubiquitylation. However, in this application, we will expand on our previous work implicating a novel pVHL-dependent signaling pathway in the development of RCC: the hydroxylation of the large subunit of RNA Polymerase II (RNAPII), Rpb1, and its subsequent ubiquitylation by the pVHL tumor suppressor complex. Our working hypothesis is that P1465 hydroxylation and pVHL-dependent ubiquitylation of Rpb1 provide fine tuning of the RNAPII complex's transcriptional activity, which results in patterns of gene expression that facilitate appropriate responses to environmental changes (such as oxidative stress). We propose that loss of that fine-tuning results in dysfunctional activity of RNAPII leading to oncogenesis. The overall goal of this work is to understand the mechanism of pVHL-dependent Rpb1 hydroxylation and ubiquitylation, and to assess the role that disruption of this process plays in oncogenesis. To achieve this, we will 1) identify the lysines within ubiquitin and Rpb1 that participate in pVHL-dependent polyubiquitylation of Rpb1 in a P1465-dependent manner in response to oxidative stress; 2) identify the prolyl hydroxylases involved in hydroxylation of Rpb1; 3) determine the oncogenic properties of Rpb1 mutants that do not undergo pVHL-dependent hydroxylation and ubiquitylation; and 4) assess the status of Rpb1 hydroxylation and ubiquitylation in human RCC tumors as compared to normal kidney tissue. The prognosis for patients with RCC is much better if their cancer is diagnosed in early stages; however, early diagnosis is uncommon in RCC because patients often do not experience symptoms until advanced stages of the disease. Because this research explores a novel biochemical mechanism for disease development, it could improve the prognosis for RCC patients in two ways: 1) by contributing to the development of new drugs to treat RCC, and 2) by identifying new genetic markers that could be used to identify individuals at risk for developing RCC.