Estrogens, Paracrine Factors, and Endometrial Cancer

描述(申请人提供)：在人类子宫内膜中，雌激素对上皮细胞的有丝分裂作用通常是由子宫内膜间质细胞分泌并作用于上皮细胞的旁分泌因子介导的。尽管如此，影响这一过程的选择性雌激素受体调节剂(SERM)和保护性的、抗增殖的植物雌激素仅在缺乏这种间接控制机制的恶性上皮细胞系中得到了表征。胰岛素样生长因子(IGF)被认为是子宫内膜间质细胞分泌的主要旁分泌因子，可诱导子宫内膜上皮细胞增殖。我们假设雌激素通过基质细胞中雌激素受体(ER)α和β的不同信号来调节旁分泌因子的分泌，从而在体内产生他莫昔芬的子宫营养作用或植物雌激素的抗雌激素保护作用。雌激素对上皮细胞增殖的调控作用，既可以直接通过抑制间质细胞IGF的合成来解释，也可以通过改变间质细胞中IGF结合蛋白的比例来间接解释。为了便于研究这些机制，我们最近开发了通过转导端粒酶逆转录酶基因而永生化的人子宫内膜间质细胞株和系。利用这些细胞和ERα和ERβ的特异性抑制剂，我们将研究这两种受体在调节旁分泌因子合成中的各自作用。在这一修订的应用中，基质细胞株，特别是IGF多肽家族分泌的因子将在雌激素激动剂和拮抗剂的影响下进行评估，无论是否存在特定的ER-α或ER-β抑制剂。这将测试雌激素信号是否通过ERα或ERβ产生不同的IGF途径成分，从而解释子宫内膜上皮细胞有丝分裂速率的差异。由基质细胞在这些雌激素刺激下产生的条件培养液将被测试在石川子宫内膜癌细胞和原代正常子宫内膜上皮细胞培养上的有丝分裂活性。为了证明它们的作用，我们将测试IGF成分和其他因子已被免疫沉淀耗尽的条件培养液。这项研究将检验假设的机制是否解释了子宫内膜对雌激素的不同反应，并可能开发出更好的SERM和植物雌激素对子宫内膜影响的分析方法。

DESCRIPTION (provided by applicant): In the human endometrium, the mitotic effect of estrogen on epithelial cells is, normally mediated by paracrine factors that are secreted by endometrial stromal cells and act on the epithelial cells. Despite this, Selective Estrogen Receptor Modulators (SERMs) and protective, anti-proliferative phytoestrogens that influence this process have only been characterized in malignant epithelial cell lines where this indirect control mechanism is absent. Insulin-like Growth Factor (IGF) is thought to be the principal paracrine factor secreted by endometrial stromal cells that induces the proliferation of endometrial epithelial cells. We hypothesize that estrogens regulate secretion of paracrine factors, yielding the uterotrophic effect of tamoxifen or antiestrogenic protective effects of phytoestrogens in vivo, by differential signaling via estrogen receptors (ER) alpha and beta in stromal cells. The modulating effects of estrogen on epithelial proliferation could be explained either directly by inhibition of IGF synthesis in stromal cells, or indirectly by changing the ratio of the IGF Binding Proteins in stromal cells. To facilitate investigation of these mechanisms we recently developed strains and lines of human endometrial stromal cells immortalized by transduction of the telomerase reverse transcriptase gene. Using these cells and specific inhibitors of ER alpha and ER beta we will investigate the respective roles of the two receptors in regulating the synthesis of paracrine factors. In this revised application, factors secreted by stromal cell lines, particularly the IGF family of peptides, will be assessed under the influence of estrogen agonists and antagonists, in the presence or absence of specific ER-alpha or ER-beta inhibitors. This will test whether estrogen signaling either through ER alpha or ER beta produces different profiles of IGF pathway components which explain differences in the mitotic rates of endometrial epithelial cells. Conditioned medium, produced by stromal cells following stimulation by these estrogens will be tested for mitogenic activity on Ishikawa endometrial cancer cells and primary normal endometrial epithelial cell cultures. To prove their roles, we will test conditioned medium where IGF components and other factors have been depleted by immunoprecipitation. This study will test whether the hypothesized mechanism explains the differing responses of endometrium to estrogens and may allow development of a better assay of effects of SERMs and phytoestrogens on endometrium.