Understanding and Targeting Tiam1 in Cancer

项目摘要： 了解细胞增殖信号转导途径的详细机制是至关重要的 对于开发用于诊断和治疗人类癌症的策略的重要性。因为大多数增殖性的 通路对于所有正常细胞的功能至关重要，癌细胞选择性干预的发展 没有脱靶效应是非常重要的，但也极具挑战性。这项研究计划 应用程序集中在增殖信号传导中的独特'球员'，鸟嘌呤核苷酸交换因子（GEFs） 来自Dbl（弥漫性B细胞淋巴瘤）家族。 GEF通过刺激小GTP酶Rho、Rac和Rac上的核苷酸交换来控制增殖信号传导。 Cdc42。在此过程中，GEF调节许多细胞活动，如基因表达、细胞骨架、细胞周期和细胞周期。 重组、蛋白质合成和代谢。GEF中的功能获得性突变与 多种人类癌症，并且来自Db1家族的GEF构成原癌基因的最大家族之一。 尽管不同的Dbl家族GEF具有相似的作用机制，但它们的表达是极其组织和组织特异性的。 细胞特异性和它们各自的突变形式与不同的癌症相关。因此，在本发明中， GEF信号的干预可能在多种看似无关的恶性疾病中非常有用。 这项工作的提出依赖于我们最近发现的一个新的酪氨酸磷酸化序列基序 （TEXXYVXXL），其调节涉及人类癌症的一些Dbl样GEF的活性。我们假设 与这种磷酸化的选择性相互参照包括独特的、新颖的和有效的选择性相互参照， 相关癌症的干预方法。这一原理证明提案的重点是Tiam1，这是一个GEF， 失调驱动结肠直肠肿瘤发生和转移。我们打算破译 Tiam 1中TEXXYVXXL磷酸化的机制和功能结果，并测试 靶向Tiam1的酪氨酸磷酸化作为选择性干预工具。在具体目标1中，我们将破译 TEXXYVXXL磷酸化在调节Tiam 1的关键活动，即GT3活化，细胞侵袭和 体外增殖和体内肿瘤发生和转移。在具体目标2中，我们将评估 靶向Tiam 1的TEXXYVXXL磷酸化位点用于干预小鼠结肠模型的新型试剂 癌这些在细胞和动物中的概念验证实验将为未来的发展打开大门， GEF相关恶性肿瘤的转化工作。

Project Summary: Understanding the detailed mechanisms that underlie proliferative signal transduction pathways is of critical importance for developing strategies for diagnosis and treatment of human cancer. Because most proliferative pathways are critical for the functioning of all normal cells, the development of cancer-cell-selective interventions without off-target effects is tremendously important yet highly challenging. The research proposed in this grant application focuses on unique ‘players’ in proliferative signaling, the guanine nucleotide exchange factors (GEFs) from the Dbl (diffuse B cell lymphoma) family. GEFs control proliferative signaling by stimulating nucleotide exchange on the small GTPases, Rho, Rac, and Cdc42. In doing so, GEFs regulate numerous cellular activities such as gene expression, cytoskeletal rearrangements, protein synthesis, and metabolism. Gain-of-function mutations in GEFs are associated with multiple human cancers, and GEFs from the Dbl family constitute one of the largest families of proto-oncogenes. Although different Dbl-family GEFs share similar mechanisms of action, their expression is extremely tissue- and cell-specific, and their respective mutated forms are associated with distinct and different cancers. Thus, intervention with GEF signaling may be extremely useful in multiple, seemingly unrelated malignant diseases. The proposed work relies on our recent discovery of a novel tyrosine phosphorylation sequence motif (TEXXYVXXL) that regulates the activity of some Dbl-like GEFs implicated in human cancers. We hypothesize that selective interreference with this phosphorylation comprises a unique, novel and effective selective intervention approach in relevant cancers. This proof-of-principle proposal focuses on Tiam1, a GEF whose dysregulation drives colorectal tumorigenesis and metastasis. We propose to decipher the molecular mechanisms and functional outcomes of TEXXYVXXL phosphorylation in Tiam1, and to test novel reagents that target Tiam1’s tyrosine phosphorylation as selective intervention tools. In Specific Aim 1 we will decipher the role of TEXXYVXXL phosphorylation in regulating Tiam1’s key activities, i.e. GTPase activation, cell invasion and proliferation in vitro, and tumorigenesis and metastasis in vivo. In Specific Aim 2, we will evaluate the utility of novel reagents that target Tiam1’s TEXXYVXXL phosphorylation site for intervention in a mouse model of colon cancer. These proof-of-concept experiments in cells and animals will open the door for future development and translational work in GEF-associated malignancies.