The role of HEF1 protein in division and invasion of metastatic breast cancer

描述（由申请人提供）：本提案将验证HEF1基因在乳腺肿瘤中上调是肿瘤转移的重要促成因素的假设。这是基于升高的HEF1驱动增殖和侵袭的能力。对于侵袭，细胞变得越来越活跃，并获得了侵袭周围组织的能力，这使得转移成为可能。过去一年的一系列研究表明，HEF1蛋白是肿瘤中促转移行为的重要开关。这些研究已经确定HEF1是转移性乳腺腺癌中上调基因的一个小“特征”组成部分，表明HEF1对胶质母细胞瘤的侵袭性很重要，并确定超过30%的转移性黑色素瘤中HEF1上调。在这一提案中，我们将解决两个基本问题：1)HEF1缺乏或过表达如何导致AurA激活，以及2)HEF1如何调节乳腺癌细胞的侵袭？在回答这些问题的具体实验中，Aim 1将使用机制，基于细胞的分析来研究HEF1如何调节AurA降解。我们将验证HEF1保护AurA免受泛素依赖性蛋白体降解的假设，并确定HEF1-AurA复合物对临床相关AurA抑制剂疗效的影响。目的2将定义HEF1促进侵袭能力的分子机制。我们将验证hef1激活的AurA激活组蛋白去乙酰化酶HDAC6并促进invadopodia种子成分- cornatin的去乙酰化的假设。在Aim 3中，我们将利用HEF1诱导shrna和现代多模态非侵入性荧光/生物发光成像技术建立HEF1驱动人类肿瘤生长和转移的分子机制，验证HEF1表达升高显著促进乳腺癌转移的假设。这些实验的最终目的是提高人类癌症患者的诊断和治疗。

DESCRIPTION (provided by applicant): This proposal will test the hypothesis that up-regulation of the HEF1 gene in breast tumors is an important contributing factor for cancer metastasis. This is based on the ability of elevated HEF1 to drive proliferation and invasion. For invasion, cells become increasingly motile and acquire the ability to invade surrounding tissue which enables metastasis. A series of studies within the past year have nominated the HEF1 protein as an essential switch for pro-metastatic behavior in tumors. These studies have identified HEF1 as a component of a small "signature" of genes upregulated in metastasizing breast adenocarcinomas, shown HEF1 is important for glioblastoma invasiveness, and determined that upregulation of HEF1 occurred in more than 30% of metastatic melanomas. In this proposal, we will address two basic questions: 1) How does absence or overexpression of HEF1 condition AurA activation, and 2) How does HEF1 regulate invasion in breast cancer cells? In specific experiments to answer these questions, Aim 1 will use mechanistic, cell-based assays to investigate how HEF1 regulates AurA degradation. We will test the hypothesis that HEF1 protects AurA from ubiquitin-dependent proteosome degradation and determine the impact of the HEF1-AurA complex on efficacy of clinically relevant AurA inhibitors. Aim 2 will define the molecular mechanisms underlying HEF1's invasion promoting abilities. We will test the hypothesis that HEF1-activated AurA activates histone deacetylase HDAC6 and promotes deacetylation of invadopodia seeding component- cortactin. In Aim 3 we will test the hypothesis that elevated HEF1 expression contributes significantly to breast cancer metastasis using orthotopic mouse xenograft models with inducible shRNAs against HEF1 and modern multimodal non-invasive fluorescent/bioluminescent imaging technology to establish molecular mechanisms of HEF1-driven tumor growth and metastasis in human cancer. The ultimate goal of these experiments is to improve the diagnosis and treatment of cancer in human patients. PUBLIC HEALTH RELEVANCE: Changes in HEF1 protein expression drive metastasis in more than 30% of human melanomas, and have been linked to metastatic behavior in breast cancer. The proposed work will elucidate the action of HEF1 in metastatic cancer progression, and reveal points of cancer cell vulnerability that can be therapeutically exploited. Further, the proposed work will directly test existing, clinically validated drugs targeting AurA and HDAC6 for effects on metastases formation, and may thus provide basis for using these agents as new anti-invasive measures prior to tumor metastasis.