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 - / - ），一种主要酶，可从脂肪酸和二酰基甘油底物中合成TG。 在正常的乳腺发育中，TG在上皮中合成以进行牛奶分泌，并保存在脂肪细胞中，脂肪细胞是乳腺基质中最丰富的细胞类型。 肥胖症的特征是脂肪组织中的TG储存过多，正在研究是乳腺癌的危险因素。 在动物研究以及某些营养和人类流行病学研究中，总脂肪的高摄入量与乳腺癌风险增加有关。 但是，这些影响的特定机制在很大程度上是未知的。 在DGAT1 - / - 小鼠中，怀孕期间乳腺上皮生长和分化受损。 近年来，乳腺基质在正常乳腺发育和癌症中都建立了上皮生长。 乳腺移植实验表明，DGAT1 - / - 小鼠上皮生长的降低是通过基质效应局部介导的。 基于初步实验，与野生型相比，将原发性乳腺癌细胞注入DGAT1 - / - 小鼠的乳腺脂肪垫中时，乳腺肿瘤的发育也会减少。 该提案中的实验将探索将脂质代谢改变DGAT1 - / - 乳腺基质中与正常和恶性上皮生长的机制。 我们假设在没有DGAT1的情况下，乳腺中脂质代谢产物或其他因素会改变，并且乳腺上皮发育的信号受损。 我们将使用生化技术来测量DGAT1 - / - 乳腺的脂质含量和组成。 我们还将执行微阵列实验，以分析与野生型相比，DGAT1 - / - 乳腺脂肪细胞中的基因表达变化。 作为识别改变因素的互补方法，将开发出上皮细胞和脂肪细胞共培养的体外体系。 为了探索DGAT1缺乏对乳腺癌的影响，我们将在DGAT1 - / - 小鼠中使用乳腺癌细胞的原位移植物以及DGAT1 - / - 小鼠之间的交叉和两个转基因小鼠模型，并增加了乳腺肿瘤的发生率。 我们将测量肿瘤的发病率，肿瘤负荷和形态，并确定DGAT1缺乏症的保护作用是否针对这些肿瘤模型之一。 最后，基于初步数据显示了白细胞在DGAT1 - / - 腹股沟淋巴结中的分布改变，我们将测试免疫系统在小鼠肿瘤排斥中起作用的假设。