PROGESTERONE, CELL CYCLE AND CANCER

黄体酮、细胞周期和癌症

• 批准号: 6489420
• 负责人: JEFFREY W. POLLARD
• 金额: $ 35.33万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-01-05 至 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6489420
• 关键词: carcinogenesis; cell cycle; cell cycle proteins; cell nucleus; cyclin dependent kinase; cyclins; endometrium; epithelium; estrogens; female; gene induction /repression; hormone regulation /control mechanism; immunofluorescence technique; laboratory mouse; microarray technology; phosphoprotein phosphatase; progesterone; transfection

Estrogens are the major carcinogen in the environment of most females with exposure to unopposed estrogen increasing the risk of breast and endometrial cancer. Conversely, it has become increasingly apparent that estrogens are essential for the well being of women (and men) throughout life. Progesterone acts to oppose the effects of estrogen on cell proliferation and, consequently, it is used in the treatment of endometrial cancer and it is an essential component of hormone replacement therapy designed to alleviate post-menopausal symptoms in women. It is, therefore, of fundamental importance to understand the mechanism of action of these hormones on cell proliferation. In adult ovariectomized mice, a single injection of estradiol-17beta (E2) results in the stimulation of a wave of DNA synthesis and cell proliferation that is restricted to the uterine epithelium. This proliferation is completely inhibited by pretreatment with progesterone (P4). The uterine epithelium can be isolated with great purity in a state suitable for biochemical analysis. This method together with defined hormonal regimens provides a controllable model in which to study the mechanism of action of these hormones in vivo. In tissue culture cells the cell cycle is regulated by the orderly activation of cyclins and their dependent kinases (Cdk). These include the cyclin D-Cdk4 and cyclin D-Cdk6 complexes acting early in G1 and the cyclin E-Cdk2 complex acting at the G1 to S-phase boundary. Our studies in the uterine epithelium have shown that E2 induces the re-localization of cyclin D1 and Cdk-4 to the nucleus and, results in orderly activation of cyclin-E and cyclin ACdk-2 activities and hyper-phosphorylation of pRb and p107. Progesterone pre- treatment prohibited the cyclin D1/Cdk-4 relocalization to the nucleus with a consequent inhibition of pRb and p107 phosphorylation. In addition, P4 abrogated the E2 induced cyclin E and cyclin A-Cdk2 activities. The specific aims of this grant are: 1) To determine the mechanism whereby P4 prohibits cyclin D1/Cdk4 nuclear accumulation following E2 treatment; 2) To determine the mechanism of action of P4-inhibition of Cdk-2 activation; 3) identify differentially regulated genes in the uterine epithelium following E2 treatment in the presence and absence of P4; 4) to develop methods to interfere with signaling pathways in the uterine epithelium in vivo. It is expected that by the end of the grant that the mechanisms of cyclin D1/Cdk4 exclusion can be identified and novel proteins associated with this process isolated. Furthermore, novel E2 and P4-regulated genes that play important roles in the control of epithelial cell proliferation should be identified. These studies will define specific mechanisms that may result in the development of therapeutics that would inhibit estrogen's mitogenic effects in tumors as well as in benign proliferative diseases such as endometrial polyps and endometriosis.

雌激素是大多数女性环境中的主要致癌物，接触无对抗的雌激素会增加患乳腺癌和子宫内膜癌的风险。相反，越来越明显的是，雌激素对于女性（和男性）一生的福祉至关重要。黄体酮可对抗雌激素对细胞增殖的影响，因此可用于治疗子宫内膜癌，并且​​是旨在缓解女性绝经后症状的激素替代疗法的重要组成部分。因此，了解这些激素对细胞增殖的作用机制至关重要。在成年卵巢切除小鼠中，单次注射雌二醇-17β (E2) 会刺激一波仅限于子宫上皮的 DNA 合成和细胞增殖。这种增殖被黄体酮 (P4) 预处理完全抑制。可以在适合生化分析的状态下以高纯度分离子宫上皮。该方法与确定的激素方案一起提供了一个可控模型，用于研究这些激素在体内的作用机制。在组织培养细胞中，细胞周期由细胞周期蛋白及其依赖性激酶 (Cdk) 的有序激活来调节。其中包括在 G1 早期起作用的细胞周期蛋白 D-Cdk4 和细胞周期蛋白 D-Cdk6 复合物以及在 G1 至 S 期边界起作用的细胞周期蛋白 E-Cdk2 复合物。我们对子宫上皮的研究表明，E2 诱导细胞周期蛋白 D1 和 Cdk-4 重新定位到细胞核，导致细胞周期蛋白 E 和细胞周期蛋白 ACdk-2 活性有序激活以及 pRb 和 p107 过度磷酸化。黄体酮预处理阻止细胞周期蛋白 D1/Cdk-4 重新定位至细胞核，从而抑制 pRb 和 p107 磷酸化。此外，P4 消除了 E2 诱导的细胞周期蛋白 E 和细胞周期蛋白 A-Cdk2 活性。本次资助的具体目的是： 1) 确定 E2 处理后 P4 抑制细胞周期蛋白 D1/Cdk4 核积累的机制； 2) 确定P4抑制Cdk-2激活的作用机制； 3) 在存在和不存在 P4 的情况下，鉴定 E2 处理后子宫上皮中差异调节的基因； 4）开发体内干扰子宫上皮信号通路的方法。预计在资助结束时，可以确定细胞周期蛋白 D1/Cdk4 排除的机制，并分离出与该过程相关的新蛋白质。此外，应该鉴定在控制上皮细胞增殖中发挥重要作用的新的E2和P4调节基因。这些研究将确定具体的机制，可能导致开发出抑制雌激素在肿瘤以及良性增殖性疾病（如子宫内膜息肉和子宫内膜异位症）中促有丝分裂作用的疗法。