Intestinal Cell Growth Control: Role of Tyrosine Kinases

描述（由申请人提供）：我们感兴趣的是了解正常肠细胞如何调节其生长，以及这种调节的丧失如何导致恶性转化。我们的研究重点是Src激酶参与调控的分子机制。我们发现RACK1是Src的新型底物和结合伙伴，也是Src激酶和结肠细胞生长的抑制剂。RACK1通过在G1检查点抑制Src活性来调节细胞生长。我们假设RACK1调节生长的其他方面，部分是通过其对Src的抑制作用。为了验证这一假设，我们将：目的1：进一步分析Src和RACK1调节结肠细胞生长的机制。研究重点是通过Gy/W、Sam68在有丝分裂中的功能和细胞粘附对细胞周期进程的影响。在抑制Src活性方面存在缺陷的RACK1突变体将被用于区分Src依赖和独立的RACK1功能机制。目的2：评估Src和RACK1在蛋白质翻译中的功能。研究的重点是它们如何调控Src关键底物、效应物和参与蛋白质合成的结合伙伴的翻译活性。目的3：分析RACK1诱导细胞凋亡和Src促进结肠细胞存活的机制。研究重点关注其对内源性和外源性凋亡通路的影响，以及对Akt细胞存活通路的影响。致癌酪氨酸激酶的内源性抑制剂在细胞周期的关键检查点、细胞粘附位点、蛋白质翻译和凋亡过程中起作用，将对细胞生长施加强大而普遍的控制。利用这些多种功能可用于开发新的和更强大的和选择性的策略来治疗人类结肠癌。

DESCRIPTION (provided by applicant): We are interested in understanding how normal intestinal cells regulate their growth and how loss of that regulation results in malignant transformation. Our research focuses on molecular mechanisms by which the Src kinases contribute to the regulation. We identified RACK1 as a novel substrate and binding partner of Src, and an inhibitor of Src kinases and colonic cell growth. RACK1 regulates cell growth by suppressing Src activity at the G1 checkpoint. We hypothesize that RACK1 regulates other aspects of growth, in part via its inhibitory influence on Src. To test this hypothesis, we will: Aim 1: Further analyze mechanisms by which Src and RACK1 regulate growth of colon cells. Studies focus on their influence on cell cycle progression through Gy/W, Sam68 function during mitosis, and cell adhesion. A RACK1 mutant that is defective for suppressing Src activity will be used to distinguish Src-dependent and independent mechanisms of RACK1 function. Aim 2: Assess Src and RACK1 function in protein translation. Studies focus on mechanisms by which they regulate translational activities of key Src substrates, effectors and binding partners involved in protein synthesis. Aim 3: Analyze mechanisms by which RACK1 induces apoptosis, and Src promotes survival of colon cells. Studies focus on their influence on the intrinsic and extrinsic apoptotic pathways, and on the Akt cell survival pathway. Endogenous inhibitors of oncogenic tyrosine kinases that work at critical checkpoints in the cell cycle, at sites of cell adhesion and during protein translation and apoptosis, would exert powerful and pervasive control over cell growth. Exploitation of these multiple functions could be used to develop new and more powerful and selective strategies for treatment of human colon cancer.