Role of DGAT1 in Mammary Gland Development and Cancer

DGAT1 在乳腺发育和癌症中的作用

• 批准号: 6927393
• 负责人: SYLVAINE CASES
• 金额: $ 16.64万
• 依托单位: J. DAVID GLADSTONE INSTITUTES
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-07 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6927393
• 关键词: acyltransferase; adipocytes; antineoplastics; breast neoplasms; cell differentiation; cell growth regulation; connective tissue stroma; diacylglycerols; enzyme deficiency; fatty acid metabolism; female; genetically modified animals; glycerides; laboratory mouse; lipid metabolism; mammary epithelium; mammary gland; neoplastic growth; pregnancy

DESCRIPTION (provided by applicant): We propose to analyze the role of triacylglycerol (TG) metabolism in mammary epithelial development and breast cancer using mice lacking DGAT1 (Dgat1-/-), a major enzyme that synthesizes TGs from fatty acids and diacylglycerol substrates. In normal mammary gland development, TGs are synthesized in the epithelium for milk secretion and stored in adipocytes, the most abundant cell type in the mammary stroma. Obesity, characterized by excess TG storage in adipose tissue, is under study as a risk factor for breast cancer. High intake of total fat has been associated with increased breast cancer risk in animal studies and in some nutrition and epidemiological studies in humans. However, specific mechanisms for these effects are largely unknown. In Dgat1-/- mice, mammary epithelial growth and differentiation are impaired during pregnancy. In recent years, the role of the mammary stroma in epithelial growth has been established in both normal breast development and cancer. Mammary transplantation experiments showed that the reduction in epithelial growth in Dgat1-/- mice is mediated locally by stromal effects. Based on preliminary experiments, breast tumor development is also reduced when primary breast cancer cells are injected into the mammary fat pad of Dgat1-/- mice compared to wild-types. Experiments in this proposal will explore mechanisms linking alteration of lipid metabolism in Dgat1-/- mammary stroma with both normal and malignant epithelial growth. We hypothesize that lipid metabolites or other factors are altered in mammary gland in the absence of DGAT1 and impair signaling for mammary epithelial development. We will use biochemical techniques to measure the lipid content and composition of Dgat1-/- mammary glands. We will also perform microarray experiments to analyze gene expression changes in Dgat1-/- mammary adipocytes compared to wild-types. As a complementary approach to identify altered factors, an in vitro system of co-culture of epithelium and adipocytes will be developed. To explore effects of DGAT1 deficiency in breast cancer, we will use orthotopic grafts of breast cancer cells in Dgat1-/- mice and crosses between Dgat1-/- mice and two transgenic mouse models with increased incidence of breast tumors. We will measure tumor incidence, tumor load, and morphology, and determine whether the protective effect of DGAT1 deficiency is specific for one of these tumor models. Finally, based on preliminary data showing altered distribution of leukocytes in Dgat1-/- inguinal lymph nodes, we will test the hypothesis that the immune system plays a role in tumor rejection by mice.

描述（由申请人提供）：我们建议使用缺乏 DGAT1 的小鼠分析三酰甘油 (TG) 代谢在乳腺上皮发育和乳腺癌中的作用 (Dgat1-/-)，一种从脂肪酸和二酰基甘油底物合成甘油三酯的主要酶。 在正常乳腺发育中，TG 在上皮中合成用于乳汁分泌，并储存在脂肪细胞中，脂肪细胞是乳腺基质中最丰富的细胞类型。 肥胖的特点是脂肪组织中甘油三酯储存过多，目前正在将其作为乳腺癌的危险因素进行研究。 在动物研究以及一些人类营养和流行病学研究中，高总脂肪摄入量与乳腺癌风险增加有关。 然而，这些影响的具体机制在很大程度上尚不清楚。 在 Dgat1-/- 小鼠中，妊娠期间乳腺上皮生长和分化受到损害。 近年来，在正常乳房发育和癌症中，乳腺基质在上皮生长中的作用已得到证实。 乳腺移植实验表明，Dgat1-/- 小鼠上皮生长的减少是由基质效应局部介导的。 根据初步实验，与野生型小鼠相比，当将原发性乳腺癌细胞注射到 Dgat1-/- 小鼠的乳腺脂肪垫中时，乳腺肿瘤的发展也会减少。 本提案中的实验将探索 Dgat1-/- 乳腺基质中脂质代谢的改变与正常和恶性上皮生长之间的联系机制。 我们假设在缺乏 DGAT1 的情况下，乳腺中的脂质代谢或其他因素会发生改变，并损害乳腺上皮发育的信号传导。 我们将使用生化技术来测量 Dgat1-/- 乳腺的脂质含量和成分。 我们还将进行微阵列实验来分析 Dgat1-/- 乳腺脂肪细胞与野生型相比的基因表达变化。 作为识别改变因素的补充方法，将开发上皮细胞和脂肪细胞共培养的体外系统。 为了探索 DGAT1 缺陷对乳腺癌的影响，我们将在 Dgat1-/- 小鼠中使用乳腺癌细胞的原位移植物，并在 Dgat1-/- 小鼠和两种乳腺肿瘤发病率增加的转基因小鼠模型之间进行杂交。 我们将测量肿瘤发生率、肿瘤负荷和形态，并确定 DGAT1 缺陷的保护作用是否对这些肿瘤模型之一具有特异性。 最后，根据显示 Dgat1-/- 腹股沟淋巴结中白细胞分布改变的初步数据，我们将检验免疫系统在小鼠肿瘤排斥中发挥作用的假设。