Chemical Genetic Dissection of Aurora A in Promoting EMT and Stem Cells Phenotype

描述（由申请人提供）：胰腺癌（PC）是极其致命的。在PC患者中，诊断前的早期转移、肿瘤复发和对当前化学-放射疗法的抵抗是常见的。最近的证据表明，在PC肿瘤中获得上皮向间质转化（EMT）和诱导癌症干细胞（CSC）表型是这些发生的重要潜在原因。然而，导致EMT和CSC表型的机制仍不清楚。这些信息对于发现治疗PC的新靶向疗法提供上级结果至关重要。长期目标是确定PC中治疗有效的药物靶点。我们最近未发表的数据揭示了极光A（AA）激酶在促进PC中的EMT和CSC中的关键作用。AA在PC中上调，并对肿瘤的发生和转移有显着作用;然而，其分子机制仍不清楚。使用创新的化学遗传筛选，FOXM 1转录因子被确定为高度恶性AsPC 1细胞中AA的直接靶点。AA在S361处直接磷酸化FOXM 1，稳定其水平。反过来，FOXM 1也稳定AA水平，从而触发一个相互的正反馈回路。已知FOXM 1上调促进PC细胞中的EMT和CSC表型。本提案的目的是确定FOXM 1作为AA的关键效应子的贡献，FOXM 1通过其促进PC肿瘤中的EMT和CSC表型。中心假设是AA和FOXM 1是潜在的药物靶点，协同促进PC中的侵袭性致癌途径。该假设将通过追求三个具体目标来测试：1）确定AA在PC细胞中促进EMT和CSC的潜在作用。2)确定AA介导的FOXM 1磷酸化对PC细胞中各种致癌途径的影响。3)确定人类临床样本中AA和FOXM 1水平及其与临床结果的相关性。该方法是创新的，因为中心假设是基于一种新的AA底物FOXM 1，使用强大的化学遗传方法发现的。在PC中未发现AA的癌症特异性底物。到目前为止，AA还没有与CSC或EMT联系起来。此外，尚未在人PC组织中串联分析FOXM 1或AA水平。这项研究意义重大，因为FOXM 1作为AA底物的验证将为抑制转移性PC中FOXM 1的失调提供有力的工具。AA和FOXM 1水平与不同临床结果的相关性有望揭示PC的潜在预后和诊断生物标志物。我们工作的积极影响将是验证AA作为治疗/预防EMT，CSC和耐药性的潜在药物靶标，无论是单独使用还是与FOXM 1抑制剂联合使用。

DESCRIPTION (provided by applicant): Pancreatic cancer (PC) is extremely lethal. Early metastasis prior to diagnosis, tumor recurrence and resistance towards current chemo-radiation therapies are common among PC patients. Recent evidence indicates that the acquisition of epithelial-to-mesenchymal transition (EMT) and induction of cancer stem cell (CSC) phenotypes in PC tumors are important underlying causes for these occurrences. However, the mechanisms leading to EMT and CSC phenotypes remain unclear. This information is critical for the discovery of novel targeted therapies for the treatment of PC that offer superior outcome. The long term goal is to identify therapeutically effective drug targets in PC. Our recent unpublished data have uncovered a critical role of Aurora A (AA) kinase in promoting EMT and CSC in PC. AA is upregulated in PC and contributes significantly to tumorigenesis and metastasis; however, the molecular mechanisms remain unknown. Using an innovative chemical genetic screen, FOXM1 transcription factor was identified as a direct target of AA in highly malignant AsPC1 cells. AA directly phosphorylates FOXM1 at S361 stabilizing its levels. In turn, FOXM1 also stabilizes AA levels, thereby triggering a reciprocal positive feedback loop. FOXM1 upregulation is known to promote EMT and CSC phenotypes in PC cells. The objective in this proposal is to determine the contribution of FOXM1 as a critical effector of AA by which it promotes EMT and CSC phenotype in PC tumors. The central hypothesis is that AA and FOXM1 are potential drug targets which promote aggressive oncogenic pathways in PC synergistically. This hypothesis will be tested by pursuing three specific aims: 1) Determine a potential role of AA in promoting EMT and CSC in PC cells. 2) Determine the consequences of AA-mediated phosphorylation of FOXM1 on various oncogenic pathways in PC cells. 3) Determine AA and FOXM1 levels in tandem in human clinical samples and their correlation with clinical outcomes. The approach is innovative because the central hypothesis was formulated based on a novel AA substrate, FOXM1, discovered using a powerful chemical genetic approach. No cancer-specific substrate of AA has been identified in PC. AA has not been linked to CSC or EMT to date. Furthermore, FOXM1 or AA levels have not been analyzed in tandem in human PC tissues. The proposed research is significant because validation of FOXM1 as an AA substrate will provide a potent tool to inhibit FOXM1 deregulation in metastatic PC. Correlation of AA and FOXM1 levels with divergent clinical outcomes are expected to reveal potential prognostic and diagnostic biomarkers for PC. The positive impact of our work will be the validation of AA as a potential drug target for treating/preventing EMT, CSC and chemoresistance, either alone or in combination with FOXM1 inhibitors.