Plant-Derived Estrogens and Cell Proliferation

描述（由申请人提供）：更年期与体重增加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，因为它增加了患心血管疾病的风险，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支出。有证据表明，激素治疗（HT）形式的雌激素可以减少腹部脂肪堆积。雌激素替代疗法已被发现可以减少绝经后妇女的体脂量以及腹腔和盆腔内脂肪。不幸的是，HT有一个主要的缺点，那就是它会导致乳腺和子宫内膜细胞的增殖。显然，雌激素保留了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。开发更安全的雌激素治疗激素的关键是针对不同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，雌激素对脂肪堆积的有益作用是由ERa介导的。同样，对乳腺和子宫内膜细胞的刺激作用是由ERa介导的。分子研究发现，内质网需要多种转录因子和协调节蛋白来调控基因并产生生物学效应。我们假设；尽管这两种作用都是由ERa介导的，但一些ERa激动剂可能对脂肪积累有有益作用，而不会对细胞增殖产生刺激作用。为了验证这一假设，我们筛选了50多种中药植物提取物的组织选择性ERa活性。我们发现两种植物利用荧光素酶报告基因具有ERa活性。与雌二醇类似，这两种植物提取物都能减少喂食高脂肪食物的老鼠的体重和腹部脂肪。然而，与雌二醇不同的是，这两种植物都没有刺激MCF-7乳腺癌细胞的增殖，而MCF-7是传统上用于测试era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ERa活性不导致细胞增殖。我们的目标是通过研究具有ERa活性的两种植物提取物的一定剂量对小鼠乳腺上皮细胞和子宫细胞以及人类乳腺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。我们认为，如果这些临床前研究表明ERa激动剂不会像雌激素那样对乳腺和子宫产生增生性作用，这可能会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。

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.