Identification of Regulators and Effectors of the Oncoprotein CDK8 in Drosophila

果蝇中癌蛋白 CDK8 的调节子和效应子的鉴定

• 批准号: 8635677
• 负责人: Jun-yuan Ji
• 金额: $ 7.28万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-22 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8635677
• 关键词: Address; Animal Model; Biological Models; Colorectal Cancer; Complex; Cyclin-Dependent Kinases; Development; Disease; Drosophila genus; Enhancers; Epidermal Growth Factor Receptor; Eukaryota; Future; Gene Expression; Genes; Genetic; Genetic Models; Genetic Screening; Genetic Transcription; Goals; Growth; Human; Knowledge; Link; Malignant Neoplasms; Mammalian Cell; Mammals; Maps; Mediator of activation protein; Modeling; Molecular; Oncogene Proteins; Organism; Pathway interactions; Phenotype; Physiological; Public Health; RNA Polymerase II; Receptor Signaling; Regulation; Research; Role; Signal Pathway; Signal Transduction; System; Trans-Activators; Transcription Coactivator; Work; cancer cell; cancer therapy; clinically significant; cyclin C; genetic analysis; in vivo; melanoma; mutant; novel; overexpression; public health relevance; transcription factor; tumorigenesis

DESCRIPTION (provided by applicant): Both CDK8 (Cyclin-Dependent Kinase 8) and its regulatory partner CycC (Cyclin C) are dysregulated in a variety of human cancers. CDK8 has been recently identified as an oncoprotein in melanoma and colorectal cancers, and CDK8 is amplified and/or overexpressed in more than half of these cancers. Depletion of CDK8 effectively blocks the growth of melanoma and colorectal cancer cells, which underscores the centrality of CDK8 in gene expression and demonstrates why CDK8 is considered an attractive and promising target for cancer treatment. However, how dysregulation of CDK8-CycC contributes to tumorigenesis, which is obviously of public health importance, remains poorly understood. To determine the normal and dysregulated functions of CDK8, it is essential to identify both the upstream regulators and the downstream effectors of CDK8-CycC. Unfortunately, analyses of function and regulation of CDK8 have been hampered by the lack of specific phenotypes or in vivo readouts for CDK8 activity in multicellular organisms. Because CDK8 and CycC are highly conserved in eukaryotes, we have solved this challenge by using Drosophila, which provides unparalleled sophistication in manipulating CDK8 activity in vivo. The long-term goal of our research is to elucidate the function and regulation of CDK8. Using Drosophila as an experimental system, we have carried out an unbiased genetic screen to identify important upstream regulators and downstream effectors of CDK8. We have identified ~70 enhancers and suppressors of the CDK8/CycC-specific phenotypes. Several candidate modifiers of these phenotypes are components of the EGFR (epidermal growth factor receptor) signaling pathway, dysregulation of which is well established in tumorigenesis of various human cancers. However, the potential link between CDK8 and EGFR signaling is novel and unexplored. Thus, the objective of this proposal is to further identify the specific mutant genes from our initial modifier genetic screen and as an example to illustrate our general approach to understand CDK8 in future studies, we will also determine how CDK8 interacts with the EGFR signaling pathway. By identifying additional genes whose products function either upstream or downstream of CDK8, our genetic analyses will enable us to elucidate the regulatory network of CDK8. In addition, this study will define the molecular mechanisms for functions of CDK8 in interacting with the EGFR signaling. These results will open up many new research directions, which will significantly advance our understanding of how dys- regulation of CDK8-CycC contributes to tumorigenesis. Because CDK8 and CycC are well conserved in eukaryotes, the genetic interactions and the underlying molecular mechanisms that we identify in Drosophila will provide a working model in human studies, and will significantly impact how we evaluate the efficacy of targeting CDK8 in treating human cancers in the future.

描述（由申请人提供）：CDK 8（细胞周期蛋白依赖性激酶8）及其调控伴侣CycC（细胞周期蛋白C）在多种人类癌症中均失调。CDK 8最近已被鉴定为黑素瘤和结直肠癌中的癌蛋白，并且CDK 8在超过一半的这些癌症中扩增和/或过表达。CDK 8的消耗有效地阻断了黑色素瘤和结直肠癌细胞的生长，这强调了CDK 8在基因表达中的中心地位，并证明了为什么CDK 8被认为是一种有吸引力和有前途的癌症治疗靶点。然而，CDK 8-CycC的失调如何导致肿瘤发生，这显然具有公共卫生重要性，仍然知之甚少。为了确定CDK 8的正常和失调功能，必须鉴定CDK 8-CycC的上游调节子和下游效应子。不幸的是，CDK 8的功能和调节的分析受到了阻碍，缺乏特定的表型或在体内读出的CDK 8活性在多细胞生物体。由于CDK 8和CycC在真核生物中高度保守，我们通过使用果蝇解决了这一挑战，果蝇在体内操纵CDK 8活性方面提供了无与伦比的复杂性。 我们的长期研究目标是阐明CDK 8的功能和调控。使用果蝇作为实验系统，我们已经进行了无偏的遗传筛选，以确定重要的上游调控因子和下游效应的CDK 8。我们已经鉴定了约70种CDK 8/CycC特异性表型的增强子和抑制子。这些表型的几种候选修饰剂是EGFR（表皮生长因子受体）信号传导途径的组分，其失调在各种人类癌症的肿瘤发生中得到充分证实。然而，CDK 8和EGFR信号传导之间的潜在联系是新的和未探索的。因此，本提案的目的是从我们的初始修饰基因筛选中进一步鉴定特定的突变基因，并作为一个例子来说明我们在未来研究中理解CDK 8的一般方法，我们还将确定CDK 8如何与EGFR信号通路相互作用。 通过鉴定其产物在CDK 8上游或下游发挥作用的其他基因，我们的遗传分析将使我们能够阐明CDK 8的调控网络。此外，本研究将明确CDK 8与EGFR信号转导相互作用的分子机制。这些结果将开辟许多新的研究方向，这将大大推进我们对CDK 8-CycC的失调如何促进肿瘤发生的理解。由于CDK 8和CycC在真核生物中非常保守，我们在果蝇中鉴定的遗传相互作用和潜在的分子机制将为人类研究提供一个工作模型，并将显著影响我们如何评估靶向CDK 8治疗人类癌症的疗效。