Ephrin-A1 in lipid metabolism and breast cancer

Ephrin-A1 在脂质代谢和乳腺癌中的作用

• 批准号: 8897851
• 负责人: Victoria Youngblood
• 金额: $ 2.36万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-06 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8897851
• 关键词: 3-Dimensional; Ablation; Address; Animals; Area; Binding; Biochemical; Bioenergetics; Biological; Biomass; Breast; Breast Cancer Cell; Breast Cancer Model; Breast Cancer Patient; Breast Epithelial Cells; Cancer cell line; Cell Proliferation; Cell Survival; Cell surface; Cells; Complement; Complex; Data; Data Set; Deposition; Development; Disease; EPHA2 gene; ERBB2 gene; Endocytosis; Enzymes; EphA2 Receptor; Ephrin-A1; Epithelial Cells; Exhibits; Fatty acid glycerol esters; Fatty-acid synthase; Generations; Genetic Models; Genotype; Gland; Growth; Human; Hyperplasia; Image Analysis; Investigation; Knockout Mice; Ligands; Link; Lipids; Malignant - descriptor; Malignant Neoplasms; Mammary Neoplasms; Mammary gland; Membrane; Metabolic; Metabolic Control; Metabolism; Modeling; Molecular; Mouse Mammary Tumor Virus; Mus; Mutation; Neoplasm Metastasis; Noninfiltrating Intraductal Carcinoma; Organoids; Oxidative Phosphorylation; Pathway interactions; Patients; Phenotype; Play; Positive Lymph Node; Procedures; Proliferating; Property; Proteins; Receptor Protein-Tyrosine Kinases; Regulation; Role; Series; Signal Pathway; Signal Transduction; Signal Transduction Pathway; Solid Neoplasm; Staging; System; Techniques; Testing; Tissue Microarray; Tissues; Transgenic Mice; Transplantation; Tumor Burden; Tumor Suppressor Proteins; Xenograft Model; Xenograft procedure; aerobic glycolysis; base; breast tumorigenesis; cancer initiation; cancer therapy; cell growth; cell motility; effective therapy; genome-wide; human FRAP1 protein; human disease; in vivo; in vivo Model; infiltrating duct carcinoma; lipid biosynthesis; lipid metabolism; lymph nodes; macromolecule; malignant breast neoplasm; metaplastic cell transformation; neoplastic cell; new therapeutic target; novel; outcome forecast; overexpression; prevent; protein expression; public health relevance; receptor; research study; small hairpin RNA; targeted treatment; tissue culture; tumor; tumor growth; tumor initiation; tumor progression; tumorigenesis

Project Summary Tumor cells have increased rates of proliferation that demand enhanced energy and biomass requirements. Proliferating tumor cells commonly support macromolecule duplication by shifting bioenergetics from oxidative phosphorylation, as observed in non-proliferating cells, to aerobic glycolysis as this form of metabolism produces critical building blocks and energy. Tumor cell lipid metabolism is intimately linked to aerobic glycolysis and recent findings suggest a critical role for lipid metabolism in tumorigenesis and malignant progression. Fatty acid synthase (FASN), the key enzyme in endogenous lipid synthesis, is overexpressed in breast cancer and is linked to poor prognosis. Yet, despite the importance of lipid metabolism in breast cancer, it is an understudied area. One way that lipid metabolism is regulated is by receptor tyrosine kinase (RTK) signaling. Dysregulation of RTK signaling can promote aberrant metabolism that contributes to cellular transformation. Therefore, it is necessary to elucidate the mechanisms that promote malignancy and metabolic reprogramming. We recently found that ephrin-A1, a prototypic ligand of EphA2 RTK, suppresses mammary gland hyperplasia. We next performed two separate experiments to evaluate whether this growth phenotype was due to the intrinsic function of ephrin-A1 within the epithelial cells or the surrounding stroma. First, we isolated mammary epithelial cells from both WT and ephrn-A1 knockout mice and performed 3-dimensional organoid cultures. Next, we performed mammary gland transplant procedures where we transplanted mammary glands into the cleared fat pads of mice of opposite genotype. Both of these experiments indicated that it is the function of ephrin-A1 within epithelial cells that plays the greatest role in this growth phenotype. Since lipid metabolism can influence growth, we tested whether ephrin-A1 regulated levels of cellular lipid deposits. In human cancer cell lines, we applied shRNA techniques to knockdown ephrin-A1 (EFNA1) and observed that ephrin-A1 knockdown cells not only had elevated levels of lipid deposits but also acquired invasive properties and enhanced tissue spheroid formation. Since FASN contributes to growth, is linked to breast cancer progression and is the key enzyme in endogenous lipid synthesis, we investigated FASN protein expression in hyperplastic glands/tumors from a small number of WT and ephrin-A1 knockout mice. We were able to demonstrate that ephrin-A1 knockout mice have elevated levels of FASN protein compared to WT tissues. These preliminary data suggest that ephrin-A1 may regulate breast tumor malignancy by regulating lipid metabolism. To further investigate this in the context of human disease, invasive ductal carcinoma and lymph node metastases tissue microarray datasets were analyzed for ephrin- A1 and FASN protein expression. We observed that low ephrin-A1 expression correlated with elevated FASN protein expression. Based on our preliminary data, we hypothesize that ephrin-A1 suppresses mammary epithelial cell lipid metabolism to inhibit breast cancer development and progression. To elucidate the mechanistic connection between ephrin-A1, lipid metabolism and breast cancer growth we have proposed experiments in 2 Specific Aims. In Aim 1, we will determine the mechanism for ephrin-A1 regulation of lipid metabolism in tumor cells and will determine whether it is through EphA2/HER2 clustering or the Akt-mTOR-SREBP signaling. Based on previous studies, we postulate that ephrin-A1 binding to EphA2 RTK may prevent EPHA2/HER clustering or may promote its degradation thus inhibiting lipid biosynthesis. Another possibility is the ephrin-A1 suppresses SREBP activation, since we have shown that ephrin-A1 inhibits Akt activity in breast epithelial cells. In Aim 2 we will systematically analyze ephrin-A1 function in mammary tumor development and progression in MMTV-Neu mice. From these animals we will evaluate protein expression within tumors and will be able to further evaluate targets identified in aims 1. Together these aims will identify the role of ephrin-A1 in breast cancer development, progression and metabolism. Furthermore, these studies will have broader implications since it may reveal a novel mechanism of metabolic regulation, potentially linking ephrin-A1 to other cancers and human diseases with aberrant lipid metabolism.

项目摘要 肿瘤细胞具有增加的增殖速率，这需要增加的能量和生物量 要求.恶性肿瘤细胞通常通过转移来支持大分子复制 从氧化磷酸化的生物能量学，如在非增殖细胞中观察到的， 糖酵解作为这种形式的代谢产生关键的积木和能量。肿瘤细胞脂质 代谢与有氧糖酵解密切相关，最近的研究结果表明，脂质 代谢在肿瘤发生和恶性进展中的作用。脂肪酸合成酶（FATTY）， 内源性脂质合成酶，在乳腺癌中过表达，与乳腺癌的不良预后有关。 预后然而，尽管脂质代谢在乳腺癌中的重要性， 区调节脂质代谢的一种方式是通过受体酪氨酸激酶（RTK）信号传导。 RTK信号转导的失调可以促进异常代谢，导致细胞凋亡。 转型因此，有必要阐明促进恶性肿瘤的机制， 代谢重编程 我们最近发现，ephrin-A1，一种EphA 2 RTK的原型配体， 增生我们接下来进行了两个单独的实验，以评估这种生长表型是否 是由于上皮细胞或周围基质中ephrin-A1的内在功能。 首先，我们从野生型和ephrn-A1基因敲除小鼠中分离乳腺上皮细胞，并进行 3-三维类器官培养接下来，我们进行了乳腺移植手术， 我们将乳腺移植到相反基因型小鼠的清洁脂肪垫中。两 这些实验表明，上皮细胞内的肝配蛋白-A1的功能发挥了 在这种生长表型中的最大作用。由于脂质代谢会影响生长，我们测试了 肝配蛋白A1是否调节细胞脂质沉积水平。在人类癌细胞系中， shRNA技术敲低ephrin-A1（EFNA 1），观察到ephrin-A1敲低细胞 不仅脂质沉积水平升高，而且还获得了侵袭性， 组织球体形成。由于Festival有助于生长，与乳腺癌进展有关 并且是内源性脂质合成的关键酶，我们研究了Festival蛋白表达， 来自少量WT和肝配蛋白-A1敲除小鼠的增生性腺体/肿瘤。我们能够 为了证明肝配蛋白-A1敲除小鼠与WT小鼠相比具有升高的肝配蛋白水平， 组织中这些初步数据表明，肝配蛋白-A1可能通过以下途径调节乳腺肿瘤的恶性程度： 调节脂质代谢。为了在人类疾病的背景下进一步研究这一点， 对导管癌和淋巴结转移组织微阵列数据集进行肝配蛋白分析， A1和FcB蛋白表达。我们观察到低ephrin-A1表达与 增加的Festival蛋白表达。基于我们的初步数据，我们假设肝配蛋白-A1 抑制乳腺上皮细胞脂质代谢以抑制乳腺癌发展， 进展 阐明ephrin-A1、脂质代谢和乳腺癌之间的机制联系 我们提出了两个具体目标的实验。在目标1中，我们将确定机制 用于肝配蛋白A1调节肿瘤细胞的脂质代谢，并将确定它是否通过 EphA 2/HER 2聚类或Akt-mTOR-SREBP信号传导。基于以往的研究，我们假设 肝配蛋白-A1与EphA 2 RTK的结合可以防止EPHA 2/HER聚集或可以促进其在EphA 2/HER中的表达。 降解，从而抑制脂质生物合成。另一种可能是肝配蛋白A1抑制SREBP 激活，因为我们已经表明肝配蛋白-A1抑制乳腺上皮细胞中Akt的活性。在目标2中 我们将系统地分析ephrin-A1在乳腺肿瘤发生和发展中的作用， MMTV-Neu小鼠。从这些动物中，我们将评估肿瘤内的蛋白质表达， 能够进一步评价目标1中确定的具体目标。这些目标将共同确定 ephrin-A1在乳腺癌发生、发展和代谢中的作用此外，这些研究 将具有更广泛的意义，因为它可能揭示一种新的代谢调节机制， 肝配蛋白-A1可能与其他癌症和脂质代谢异常的人类疾病相关。