Feedback regulation and functional output of the RAS/RAF/MEK/MAPK pathway in huma

人RAS/RAF/MEK/MAPK通路的反馈调节和功能输出

基本信息

批准号：
8128465
负责人：
Christine Anne Pratilas
金额：
$ 17.32万
依托单位：
SLOAN-KETTERING INST CAN RESEARCH
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-21 至 2014-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8128465
关键词：
Accounting BRAF gene Binding Biological Process Breast Carcinoma Cell Line Cell Nucleus Cell Proliferation Cells Clinical Trials Data Disabled Persons Down-Regulation Drug usage ERBB2 gene ETV1 gene ETV4 gene Effectiveness Epidermal Growth Factor Receptor Event Exposure to Family Family member Feedback Fractionation Gene Expression Genes Genetic Transcription Genome Goals Growth Human Immunoblotting Impairment JUN gene MAP Kinase Gene MAP Kinase Kinase Kinase 1 MAPK1 gene MEK inhibition MEKs Measurement Measures Mediator of activation protein Mitogen-Activated Protein Kinases Mus Mutation Nuclear Oncogenic Output Pathway interactions Patients Pattern Phenotype Phosphoric Monoester Hydrolases Phosphorylation Phosphotransferases Physiological Principal Investigator Protein Kinase Inhibitors Proteins RNA Interference Receptor Protein-Tyrosine Kinases Refractory Regulation Research Research Personnel Research Proposals Resistance Role Signal Pathway Signal Transduction Small Interfering RNA System Testing Tetracyclines Transcript Transfection Up-Regulation base cell growth cell transformation gain of function human MAP3K1 protein immunocytochemistry in vivo in vivo Model inhibitor/antagonist melanoma mutant neoplastic cell overexpression programs promoter protein expression protein kinase inhibitor public health relevance receptor response selective expression small hairpin RNA small molecule tissue culture transcription factor tumor tumor growth tumor xenograft vector control

项目摘要

DESCRIPTION (provided by applicant): BRAF mutations occur in a significant proportion of human tumors, and represent a mechanism of constitutive activation of the MAPK pathway. We have demonstrated that activating mutations of BRAF confer sensitivity to small molecule inhibitors of the pathway. In contrast, we showed that HER2-overexpressing breast carcinomas were resistant to MEK inhibition, despite effective pharmacologic inhibition of MAPK activity. Our preliminary data suggest that tumors with HER kinase activation (and WT BRAF) and those with oncogenic BRAF have similar levels of phosphorylated ERK; however, BRAF mutant tumors have higher levels of phosphorylated MEK and selected MEK-ERK dependent transcripts. Further, MEK inhibitor-induced feedback upregulation of the pathway is seen only in the receptor-activated tumors, but not in tumors with activating BRAF mutation. We hypothesize that increased output of the MAPK pathway in B- RAF mutant tumors compared to HER kinase-activated tumors is due to the impairment of feedback inhibition of the pathway, upstream of, and/or at the level of, RAF. We hypothesize that disabling of upstream feedback in BRAF mutant tumors causes an increase in pathway throughput, resulting in increased expression of ERK effectors, and targets responsible for pathway feedback (DUSP, SPRY proteins). This increase in DUSPs (MAP kinase phosphatases) may be critical for the downregulation of ERK to physiologically tolerated levels. The increase in both feedback and effector proteins may together be responsible for aspects of the transformed phenotype. In this proposal, we describe further preliminary data which support these assertions, and describe a research plan to determine the mechanism of feedback response to MEK inhibition. We will determine whether phosphorylated ERK represents an accurate reflection of pathway activation. We will use small molecule inhibitors of the pathway, as well as RNA interference to determine the role of critical proteins in the feedback program. Finally, we will develop isogenic systems transformed by oncogenic BRAF and activated receptor tyrosine kinases to determine if specific feedback and effector protein expression patterns can be generated. The translational goals of these studies are to identify feedback pathways modulating the response to RAF and MEK inhibitors which will impact the effectiveness of these compounds in clinical trials. PUBLIC HEALTH RELEVANCE: The RAS-RAF-MEK-ERK signaling pathway is an important regulator of tumor cell growth and proliferation. The goals of this research proposal are to understand feedback mechanisms which regulate the activation of this pathway. Understanding this regulatory mechanism will help investigators use drugs which target this pathway to select patients whose tumors are most likely to respond to them. PHS 398/2590 (Rev. 11/07) Page Continuation Format Page

描述（由申请人提供）：BRAF突变发生在大部分人类肿瘤中，代表了MAPK途径的本构激活机制。我们已经证明，激活BRAF的突变赋予对途径的小分子抑制剂的敏感性。相比之下，我们表明，尽管有效地抑制了MAPK活性的有效的药理抑制，但表达HER2过表达的乳腺癌对MEK抑制作用。我们的初步数据表明，其激酶激活（和WT BRAF）和具有致癌BRAF的肿瘤具有相似水平的磷酸化ERK。但是，BRAF突变肿瘤具有较高水平的磷酸化MEK，并选择了MEK-ERK依赖性转录本。此外，仅在受体激活的肿瘤中可以看到MEK抑制剂诱导的途径反馈上调，而在激活BRAF突变的肿瘤中不观察到。我们假设与激酶激活的肿瘤相比，B-RAF突变肿瘤中MAPK途径的输出增加是由于RAF水平的途径，上游和/或在RAF水平上的反馈抑制抑制损害。我们假设BRAF突变肿瘤中上游反馈的禁用会导致途径吞吐量增加，从而导致ERK效应子的表达增加，并导致途径反馈（DUSP，SPRY蛋白）的靶标。 DUSP（MAP激酶磷酸酶）的这种增加对于将ERK下调至生理耐受水平至关重要。反馈和效应蛋白的增加可能会导致转化表型的各个方面。在此提案中，我们描述了支持这些主张的进一步初步数据，并描述了一项研究计划，以确定反馈对MEK抑制的反应机制。我们将确定磷酸化的ERK是否代表了途径激活的准确反射。我们将使用途径的小分子抑制剂，以及RNA干扰来确定临界蛋白在反馈程序中的作用。最后，我们将开发由致癌的BRAF和活化受体酪氨酸激酶转化的同源系统，以确定是否可以产生特定的反馈和效应蛋白表达模式。这些研究的转化目标是确定反馈途径调节对RAF和MEK抑制剂的反应，这将影响这些化合物在临床试验中的有效性。公共卫生相关性：Ras-Raf-Mek-ERK信号通路是肿瘤细胞生长和增殖的重要调节剂。该研究建议的目标是了解调节该途径激活的反馈机制。了解这种调节机制将帮助研究人员使用针对该途径的药物，以选择最有可能对其做出反应的患者。 PHS 398/2590（Rev. 11/07）页面延续格式页面