Understanding and Targeting Tiam1 in Cancer

项目总结： 了解增殖信号转导通路的详细机制是至关重要的 制定人类癌症诊断和治疗策略的重要性。因为最具增殖性 通路对所有正常细胞的功能、肿瘤细胞选择性干预的发展至关重要 没有偏离目标的效果是极其重要的，但也具有极大的挑战性。这项拨款中提出的研究 应用重点放在增殖信号中独特的“玩家”--鸟嘌呤核苷酸交换因子(GEF) 来自DBL(弥漫性B细胞淋巴瘤)家族。 GEFS通过刺激小的GTP酶、Rho、Rac和 Cdc42。在这样做的过程中，GEF调节许多细胞活动，如基因表达、细胞骨架 重组、蛋白质合成和新陈代谢。GEF中的功能增益突变与 多种人类癌症，来自DBL家族的GEF构成了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，但它们的表达具有极强的组织性 它们各自的突变形式与不同和不同的癌症有关。因此， 在多种看似无关的恶性疾病中，对全球环境基金信号的干预可能非常有用。 这项拟议的工作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)，调节一些与人类癌症有关的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一种独特的、新颖的和有效的选择性 相关癌症的干预方法。这项原则证明提案的重点是全球环境基金Tiam1，其 调节失调导致结直肠肿瘤的发生和转移。我们建议破译分子 Tiam1中TEXXYVXXL磷酸化的机制和功能结果，并测试新的试剂 以Tiam1‘S酪氨酸磷酸化为选择性干预工具。在具体目标1中，我们将破译 TEXXYVXXL磷酸化调控Tiam1‘S的关键活性，即GTP酶激活，细胞侵袭和 体外增殖，体内肿瘤发生和转移。在具体目标2中，我们将评估 靶向Tiam1‘S TEXXYVXXL磷酸化位点干预小鼠结肠模型的新试剂 癌症。这些在细胞和动物身上进行的概念验证实验将为未来的发展和 全球环境基金相关恶性肿瘤的翻译工作。

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.