Roles of p85, Ras, and elF3i/Trip1 in pI3-kinase oncogenic transformation

描述（由申请人提供）：pl3激酶信号通路在许多癌症中上调。pi3激酶催化亚基p110 α的热点突变发生在几种类型的实体肿瘤中，约占30%。本研究的目的是了解由癌症特异性突变体p110 α诱导的癌性转化的分子机制，并为设计突变体特异性抑制剂作为抗癌药物提供见解。本应用程序中提出的实验将广泛使用逆转录病毒构建体来分析p110 α突变体诱导的致癌转化。p85和Ras已被证明可调节p110 α的激酶活性。我将通过体外激酶测定和体内细胞转化测定来检查致癌的p110 α是否失去了p85的抑制调节。我将确定p110 α的致癌性是否取决于Ras结合并使用生化分析、细胞转化试验和RNAi引起Ras的组成性激活。我已经确定了一个新的p110 α结合伙伴，elF3i/Trip1。在这里，我将首先通过敲低elF3i/Trip1来检验elF3i/Trip1在pi3激酶转化中的重要性，然后研究致癌基因p110 α对elF3i介导的翻译起始和TGF β /Tripl通路介导的转录调控可能产生的影响。

DESCRIPTION (provided by applicant): The Pl3-kinase signaling pathway is upregulated in numerous cancers. Hot spot mutations in the catalytic subunit of PI3-kinase, p110 alpha, occur in approximately 30% of several types of solid tumors. The goal of this proposal is to understand the molecular mechanism underlying the oncogenic transformation induced by cancer specific mutant p110 alpha and provide insight into the design of mutant specific inhibitors as anti- cancer drugs. The experiments proposed in this application will make extensive use of retroviral constructs to analyze oncogenic transformation induced by p110 alpha mutants. p85 and Ras have been shown to regulate the kinase activity of p110 alpha. I will examine if oncogenic p110 alpha losses the inhibitory regulation by p85 via in vitro kinase assays and in vivo cell transformation assays. I will determine if the oncogenicity of p110 alpha depends on Ras binding and causes constitutive activation of Ras using biochemical analysis, cell transformation assay, and RNAi. I have identified a new p110 alpha-binding partner, elF3i/Trip1. Here, I will first test the importance of elF3i/Trip1 in PI3-kinase transformation by knocking down elF3i/Trip1, and then investigate the possible impact of oncogenic p110 alpha on translation initiation mediated by elF3i and transcriptional regulation mediated by TGF beta/Tripl pathways.