Plant-Derived Estrogens and Cell Proliferation

描述（由申请人提供）：更年期与体重增加约10-15磅和脂肪重新分配到腹部有关。腹部脂肪的增加，也被称为内脏脂肪，已知会产生细胞因子，引起炎症，从而导致代谢综合征。代谢综合征是一个主要的公共卫生负担，因为它增加了心血管疾病的风险，并促进胰岛素抵抗和糖尿病。在美国，估计有25%的人口（5000万人）被归类为患有这种疾病，这导致了巨大的医疗保健支出。有证据表明，雌激素在激素治疗（HT）的形式可以减少腹部脂肪堆积。雌激素替代疗法已被发现，以减少身体脂肪量以及腹内和盆腔内脂肪在绝经后妇女。不幸的是，HT有一个主要的缺点，它会导致乳腺和子宫内膜细胞的增殖。显然，雌激素保留其对脂肪积累的有益作用，但不促进细胞增殖和癌症，将对绝经后妇女产生深远的影响。开发更安全的HT雌激素的关键是靶向各种组织中的特异性雌激素受体（ER）。ER有两种亚型，ERa和ERb。研究表明，雌激素对脂肪积累的有益作用是由ER α介导的。类似地，对乳腺和子宫内膜细胞的刺激作用由ER α介导。分子生物学研究发现，ER调控基因和产生生物学效应需要多种转录因子和共调节蛋白。我们假设，尽管这两种作用都是由ER α介导的，但一些ER α激动剂对脂肪积累具有有益作用，而对细胞增殖不产生刺激作用。为了验证这一假设，我们筛选了超过50种用于传统中药的植物提取物的组织选择性ER α活性。我们发现，两种植物ER α活性使用荧光素酶报告基因。与雌二醇类似，这两种植物提取物都能减少高脂肪饮食小鼠的体重和腹部脂肪。然而，与雌二醇不同，两种植物都不刺激MCF-7乳腺癌细胞的增殖，MCF-7乳腺癌细胞是经典用于测试ER α介导的增殖作用的细胞系。此外，与雌二醇不同，植物提取物不会增加子宫的重量。这些结果表明植物提取物的ER α活性不导致细胞增殖。我们的目的是通过研究一系列剂量的两种具有ER α活性的植物提取物对小鼠乳腺上皮细胞和子宫细胞以及人乳腺癌和子宫内膜癌细胞增殖的影响，将这些发现扩展到动物模型。我们相信，如果这些临床前研究表明ER α激动剂不会引起乳腺和子宫上的增殖效应，如目前HT中使用的雌激素，这可能导致预防绝经后妇女腹部脂肪堆积和代谢综合征的治疗突破。 公共卫生相关性：许多绝经后妇女体重增加，脂肪重新分布到腹部，这可能导致代谢综合征。有证据表明，激素疗法形式的雌激素可以减少腹部脂肪堆积和代谢综合征，但妇女健康倡议试验发现，激素疗法增加了患乳腺癌的风险。我们的目标是发现不促进癌症的雌激素，但保留雌激素对体重和脂肪积累的有益作用。

DESCRIPTION (provided by applicant): Menopause is associated with about a 10-15 pound weight gain and a redistribution of fat to the abdomen. The increase in abdominal fat, also known as visceral fat is known to produce cytokines that cause inflammation which can lead to the metabolic syndrome. The metabolic syndrome represents a major public health burden because it increases the risk of cardiovascular disease, and promotes insulin resistance and diabetes. In the US, an estimated 25% of the population (50 million people) is classified as having this condition, which has led to enormous health care expenditures. There is evidence that estrogens in the form of hormone therapy (HT) can reduce abdominal fat accumulation. Estrogen replacement therapy has been found to decrease body fat mass as well as intra-abdominal and intrapelvic fat in postmenopausal women. Unfortunately, HT has a major drawback in that it causes proliferation of breast and endometrial cells. Clearly, estrogens that retain their beneficial effect on fat accumulation, but do not promote cell proliferation and cancer will have a profound impact on postmenopausal women. A key to developing safer estrogens for HT is to target specific estrogen receptors (ER) in various tissues. There are two ER subtypes, ERa and ERb. Studies indicate that the beneficial effect of estrogens on fat accumulation is mediated by ERa. Similarly, the stimulatory effects on breast and endometrial cells are mediated by ERa. Molecular studies have found that a variety of transcription factors and coregulatory proteins are required for ERs to regulate genes and produce biological effects. We hypothesize that; despite both effects being mediated by ERa, some ERa agonists could have beneficial effects on fat accumulation without producing the stimulatory effects on cell proliferation. To test this hypothesis, we screened over 50 plant extracts used in Traditional Chinese Medicine for tissue selective ERa activity. We found that two plants had ERa activity using a luciferase reporter gene. Similar to estradiol, both plant extracts produced a reduction in body weight and abdominal fat in mice fed a high fat diet. However, unlike estradiol, both plants did not stimulate the proliferation of MCF-7 breast cancer cells, which is the cell line classically used to test for ERa-mediated proliferative effects. Furthermore, unlike estradiol, the plant extracts did not increase the weight of the uterus. These results indicate that the ERa activity of the plant extracts do not lead to cell proliferation. Our objective is to extend these findings to animal models by studying the effect of a range of doses of two plant extracts with ERa activity on the proliferation of mouse mammary epithelial and uterine cells, and human breast and endometrial cancer cells. We believe that if these pre-clinical studies show that ERa agonists do not cause the proliferative effects as estrogens used currently in HT on the mammary gland and uterus this could lead to a therapeutic breakthrough for preventing abdominal fat accumulation and the metabolic syndrome in postmenopausal women. PUBLIC HEALTH RELEVANCE: Many postmenopausal women have increased weight gain and fat redistribution to the abdomen, which can lead to the metabolic syndrome. There is evidence that estrogens in the form of hormone therapy can reduce abdominal fat accumulation and the metabolic syndrome, but the Women's Health Initiative trial found that hormone therapy increases the risk of breast cancer. Our goal is to discover estrogens that do not promote cancer, but retain the beneficial of estrogens on body weight and fat accumulation.