The Akt and NFAT Pathway and the Regulaton of Cancer Cell Motility

Akt 和 NFAT 通路与癌细胞运动的调节

• 批准号: 7772392
• 负责人: Alex Toker
• 金额: $ 29.07万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-04-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7772392
• 关键词: 1-Phosphatidylinositol 3-Kinase; Actins; Address; Alleles; Attenuated; Boxing; Breast Cancer Cell; Cancer Control; Cancer Etiology; Cancer cell line; Cell Survival; Cells; Characteristics; Cytoskeleton; Data; Development; Dimensions; Enhancers; Enzymes; Epithelial; Epithelial Cells; Etiology; Future; Genetic; Goals; Growth; Human; Immigration; MDM2 gene; Malignant Neoplasms; Mediating; Modeling; Mutate; NFAT Pathway; Nuclear Export; Outcome; Pathway interactions; Phenotype; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphorylation; Play; Protein Isoforms; Protein Kinase; Publishing; Regulation; Research Personnel; Role; Signal Pathway; Signal Transduction; Small Interfering RNA; Specificity; Testing; Ubiquitination; attenuation; base; cancer cell; cell motility; defined contribution; gain of function; inhibitor/antagonist; insight; loss of function; migration; neoplastic cell; novel therapeutic intervention; nuclear factors of activated T-cells; programs; research study; response; transcription factor; tumor progression; tumorigenesis; ubiquitin-protein ligase

DESCRIPTION (provided by applicant): The objective of this proposal is to define the role of the protein kinase Akt and its downstream targets in the etiology of cancer. The PI 3-K-Akt signaling axis has been shown to be critical for tumor progression by impacting cell survival and growth. Little is known, however, concerning the role of Akt in controlling cell motility and invasive migration. Our studies have shown that Akt isoforms Akt1 and Akt2 have distinct effects on the motility of a number of breast cancer cell lines, where Akt1 functions as an inhibitor of invasive migration, whereas Akt2 may function as an enhancer. We further show that Akt can phosphorylate the transcription factor NFAT, promote its degradation and blunt transcriptional activity. Finally, we also show that the transcription factor FOXO3a, also an Akt substrate, increases motility and that phosphorylation by Akt blocks this phenotype. Based on our studies, we propose the hypothesis that Akt isoforms have distinct effects on the motility of epithelial cancer cells. We propose that this is mediated by cellular localization of Akt1 and Akt2, and that in turn this determines the Akt-mediated regulation and phosphorylation of NFAT and FOXO3a, leading to their nuclear export and degradation. Three aims will test this model:- In AIM 1, we will rigorously test the contribution of Akt1, Akt2 and Akt3 in regulating breast cancer cell motility and alterations in the actin cytoskeleton, using both loss-of-function approaches, such as siRNA, as well as gain-of-function genetic approaches with activated Akt alleles. We will investigate the importance of cellular localization of Akt isoforms, and also the contribution of the Akt phosphatase PHLPP. In AIM 2, we will determine the mechanism by which Akt isoforms control NFAT transcriptional activity, leading to nuclear export. We also propose experiments to mechanistically evaluate how Akt isoforms mediate ubiquitination and degradation of NFAT through the E3 ligases MDM2, Skp2 and NEDD4-2. We will evaluate the contribution of the ERK pathway in Akt-regulated invasive migration. In AIM 3, we will determine if FOXO3a, a distinct Akt substrate, promotes the acquisition of a motile phenotype in epithelial cells, and whether Akt-mediated phosphorylation, nuclear export, ubiquitination and proteasomal degradation block this response. The results of these studies will provide important new insights into the mechanisms by which Akt isoforms modulate cancer cell invasive migration through two crucial effectors, NFAT and FOXO3a. We anticipate that the successful completion of these studies will provide a paradigm shift in the field because they will show that signaling through Akt has profound effects on cell motility of cancer cells. There is also the potential that the outcome of our studies will provide for the future development of novel therapeutic interventions for tumor progression.

描述（由申请人提供）：该提案的目的是定义蛋白激酶AKT及其下游靶标在癌症病因中的作用。 PI 3-K-AKT信号轴已被证明通过影响细胞的存活和生长对肿瘤进展至关重要。然而，关于AKT在控制细胞运动和侵入性迁移中的作用的知之甚少。我们的研究表明，Akt同工型AKT1和AKT2对许多乳腺癌细胞系的运动有明显的影响，在许多乳腺癌细胞系的运动中，AKT1作为侵入性迁移的抑制剂，而AKT2可能起增强剂的作用。我们进一步表明，AKT可以磷酸化转录因子NFAT，促进其降解和钝性转录活性。最后，我们还表明，转录因子FOXO3A（也是AKT底物）增加了运动性，而Akt的磷酸化阻碍了这种表型。根据我们的研究，我们提出了以下假设：Akt同工型对上皮癌细胞的运动有明显的影响。我们建议这是由Akt1和Akt2的细胞定位介导的，这反过来决定了Akt介导的NFAT和FOXO3A的调节和磷酸化，从而导致其核出口和降解。三个目标将测试此模型： - 在AIM 1中，我们将使用两种功能丧失方法，例如siRNA，以及通过激活的AKT代替的功能丧失基因方法来严格测试AKT1，AKT2和AKT3在调节乳腺癌细胞运动和肌动蛋白细胞骨架上改变的贡献。我们将研究Akt同工型细胞定位的重要性，以及Akt磷酸酶PHLPP的贡献。 在AIM 2中，我们将确定AKT同工型控制NFAT转录活性的机制，从而导致核输出。我们还提出了实验，以机械学评估Akt同工型如何通过E3连接酶MDM2，SKP2和NEDD4-2介导NFAT的泛素化和降解。我们将评估ERK途径在AKT调节的侵入性迁移中的贡献。 在AIM 3中，我们将确定FOXO3A（一种独特的Akt底物）是否促进了上皮细胞中运动表型的采集，以及Akt介导的磷酸化，核输出，泛素化和蛋白酶体降解是否阻止了这种反应。 这些研究的结果将为AKT同工型通过两个关键效应子NFAT和FOXO3A调节癌细胞侵入性迁移的机制提供重要的新见解。我们预计，这些研究的成功完成将在现场提供范式转移，因为它们将表明通过AKT信号对癌细胞的细胞运动具有深远的影响。我们的研究结果也有可能为肿瘤进展的新型治疗干预措施提供未来的发展。