Hypoxic Response in Breast Cancer Progression and Metastasis

描述（由申请人提供）：实体肿瘤的缺氧区是肿瘤细胞治疗耐药部分的来源。氧调节的缺氧诱导因子(HIF)-1 α转录因子是缺氧反应的主要调节因子，在约29%的原发性乳腺肿瘤和约79%的转移瘤中过表达。此外，hif -1 α最近被证明下调雌激素受体(ER) α，表明肿瘤缺氧有助于他莫昔芬耐药。然而，hif -1 α对乳腺癌的具体作用仍不清楚。基于这些观察结果，我假设hif -1 α是乳腺肿瘤进展和转移的关键阳性因子，并具有促进肿瘤细胞适应微环境的功能。此外，我假设hif -1 α依赖基因在正常乳腺组织和肿瘤组织之间受到不同的调节，并且乳房中有一种独特的基因子集受到缺氧和雌激素的共同调节。我有使用遗传小鼠模型了解正常乳腺发育的丰富经验。现在，作为田纳西大学癌症研究所（UTCI）的新助理教授，我试图确定hif -1 α在乳腺癌病因学中的作用。我将通过以下目的来检验我的假设：1)确定乳腺上皮中HIF-1alpha条件缺失对乳腺癌进展和转移的功能意义。我之前开发了一个小鼠模型，使用Cre/loxP系统删除乳腺上皮中的hif -1 α。该模型将被培育到发展乳腺肿瘤的转基因小鼠身上。将比较野生型（WT）和HIF-1alpha阴性肿瘤的肿瘤潜伏期、生长速度、组织学和基因表达谱。来自WT和null肿瘤的稳定细胞系也将产生，用于进一步的体外分析。2)鉴定正常乳腺与乳腺肿瘤中hif -1 α靶基因，鉴定受雌激素共同调控的hif -1 α靶基因。我们将使用Affymetrix微阵列技术鉴定hif - 1α依赖性靶基因在WT和KO正常乳腺组织以及Aim 1衍生乳腺肿瘤中的差异表达谱。接下来，微阵列分析将用于确定雌激素在er α +乳腺癌细胞系MCF-7中共同调节的hif -1 α靶基因亚群。这些研究的最终目标是确定HIF-1alpha促进乳腺肿瘤发生和转移的机制，以便开发与乳腺癌患者直接相关的转化研究项目。

DESCRIPTION (provided by applicant): Hypoxic regions of solid tumors are the source of therapeutic-resistant fractions of tumor cells. The oxygen-regulated Hypoxia-lnducible Factor (HIF)-1alpha transcription factor is a master regulator of the hypoxic response, and is over-expressed in approximately 29% of primary breast tumors and approximately 79% of metastases. Moreover, HIF-1alpha has recently been demonstrated to down-regulate estrogen receptor (ER)alpha, suggesting that tumor hypoxia contributes to tamoxifen-resistance. Yet, the specific contribution of HIF-1alpha to breast cancer remains unclear. Based on these observations, I hypothesize that HIF-1alpha is a critical positive factor in breast tumor progression and metastasis and functions to promote tumor cell adaptation to the microenvironment. In addition, I hypothesize that HIF-1alpha-dependent genes are differentially regulated between normal breast tissue and tumors and that a unique subset of genes in the breast is co-regulated by hypoxia and estrogen. I have extensive experience using genetic mouse models to understand normal mammary gland development. Now, as a new Assistant Professor at the University of Tennessee Cancer Institute (UTCI), I seek to define the role of HIF-1alpha in breast cancer etiology. I will test my hypotheses through the following aims: 1) To determine the functional significance of HIF-1alpha conditional deletion in the mammary epithelium upon breast cancer progression and metastasis. I previously developed a mouse model to delete HIF-1alpha in the mammary epithelium using the Cre/loxP system. This model will be bred to transgenic mice that develop mammary tumors. The tumor latency, growth rate, histology and gene expression profile will be compared between wild type (WT) and HIF-1alpha null tumors. Stable cell lines from WT and null tumors will also be generated for further in vitro analysis. 2) To identify HIF-1alpha target genes in the normal gland vs. mammary tumors and to identify HIF-1alpha target genes co-regulated by estrogen. The differential expression profile of HIF-1alpha-dependent target genes between WT and KO normal mammary tissue and the mammary tumors derived in Aim 1 will be identified using Affymetrix microarrays. Next, microarray profiling will be used to determine the subset of HIF-1alpha target genes that is co-regulated by estrogen in the ERalpha+ breast cancer cell line MCF-7. The ultimate goal of these studies is to identify the mechanisms by which HIF-1alpha promotes breast tumorigenesis and metastasis in order to develop a translational research program immediately relevant to breast cancer patients.