Prohibitin in Mediating Suppression of Breast Cancer

抑制素介导乳腺癌的抑制

• 批准号: 6686277
• 负责人: SHENG WANG
• 金额: $ 8.08万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6686277
• 关键词: antineoplastics; breast neoplasms; cell cycle proteins; cell proliferation; gel mobility shift assay; growth inhibitors; hormone inhibitor; hormone regulation /control mechanism; hormone related neoplasm /cancer; immunoprecipitation; neoplastic cell; northern blottings; protein quantitation /detection; transcription factor; transfection; western blottings

DESCRIPTION (provided by applicant): Background: Estrogen antagonists are widely employed in the treatment of breast cancer. They also comprise the most promising drugs for breast cancer chemo-prevention. Despite these facts, the molecular mechanisms by which these compounds inhibiting cellular proliferation are not fully defined. One of such compound, tamoxifen, leads to highly-significant decreases in the rates of both disease recurrence and death, but tamoxifen is limited by a less that 50 percent response rate in breast cancer prevention and the inevitable development of cellular resistance in breast cancer therapy. Our preliminary studies have demonstrated that depletion of prohibitin protein or introducing dominant negative forms of co-repressors of prohibitin overcomes 4-hydroxytamoxifen-induced growth suppression in breast cancer cells. A potential role for prohibitin gene in breast cancer has also been suggested in earlier studies, in which prohibitin was found to be mutated in some sporadic breast cancers. Objective/Hypothesis: I hypothesize that prohibitin and its co-repressors Brg-1/Brm play a role in estrogen antagonists-induced growth suppression of breast cancer, and that estrogen antagonists target the prohibitin/E2F pathway to affect breast cancer cell proliferation. The studies proposed will test and prove a critical and necessary role for prohibitin/Brm-Brg/E2F axis in the response of breast cancer cells to estrogen antagonists. Specific Aims: I. Determine the mechanism of estrogen antagonist-induced growth repression of breast cancer cells II. Determine the molecular level at which estrogen antagonists regulate prohibitin activity. Study Design: Northern blot or RT-PCR and immunoblot analysis will be carried out to assess the regulation of endogenous E2F responsive promoters by estrogen antagonists. The requirement for prohibitin/Brg-1/Brm in estrogen antagonist-mediated transcriptional repression of natural E2F-responsive promoters will be tested, using anti-sense and dominant-negative strategies. Chromatin immuno-precipitation assays (CHIP) will be employed to study the effect of estrogen antagonists on the interactions of prohibitin, Brg-1, and Brm with the natural E2F-responsive promoters. Relevance: A major problem facing breast cancer chemo-prevention is the low response rate. Estrogen antagonists treatment is further limited by the inevitable development of resistance. The lack of information about the molecular mechanisms of estrogen antagonists-mediated growth suppression prevents the development of strategies to overcome the problems. Our demonstration of the involvement of prohibitin in 4-HT induced growth arrest suggests that the prohibitin/E2F pathway is the/a cellular target for estrogen antagonists, and thereby also implicates prohibitin as a potentially important target for breast cancer therapy.

描述（由申请人提供）： 背景：雌激素拮抗剂广泛应用于乳腺癌的治疗。它们还包括最有前途的乳腺癌化学预防药物。尽管有这些事实，这些化合物抑制细胞增殖的分子机制尚未完全确定。其中一种化合物他莫昔芬可显着降低疾病复发率和死亡率，但他莫昔芬在乳腺癌预防方面的反应率低于 50%，并且在乳腺癌治疗中不可避免地会产生细胞耐药性，因此受到限制。我们的初步研究表明，消除抑制素蛋白或引入显性负性抑制素形式的抑制素可以克服 4-羟基他莫昔芬诱导的乳腺癌细胞生长抑制。早期的研究也表明了抑制素基因在乳腺癌中的潜在作用，其中发现抑制素在一些散发性乳腺癌中发生突变。 目的/假设：我假设抑制素及其共阻遏物 Brg-1/Brm 在雌激素拮抗剂诱导的乳腺癌生长抑制中发挥作用，并且雌激素拮抗剂靶向抑制素/E2F 途径影响乳腺癌细胞增殖。拟议的研究将测试并证明抑制素/Brm-Brg/E2F轴在乳腺癌细胞对雌激素拮抗剂的反应中发挥关键和必要的作用。 具体目标： 一、确定雌激素拮抗剂诱导乳腺癌细胞生长抑制的机制 二.确定雌激素拮抗剂调节抑制素活性的分子水平。 研究设计：将进行Northern印迹或RT-PCR和免疫印迹分析来评估雌激素拮抗剂对内源性E2F反应性启动子的调节。将使用反义和显性失活策略来测试雌激素拮抗剂介导的天然 E2F 响应启动子的转录抑制中对抑制素/Brg-1/Brm 的需求。染色质免疫沉淀测定 (CHIP) 将用于研究雌激素拮抗剂对抑制素、Brg-1 和 Brm 与天然 E2F 响应启动子相互作用的影响。 相关性：乳腺癌化学预防面临的一个主要问题是反应率低。不可避免的耐药性的发展进一步限制了雌激素拮抗剂的治疗。由于缺乏有关雌激素拮抗剂介导的生长抑制的分子机制的信息，阻碍了克服这些问题的策略的发展。我们对抑制素参与 4-HT 诱导的生长停滞的证明表明，抑制素/E2F 途径是雌激素拮抗剂的细胞靶点，因此也暗示抑制素是乳腺癌治疗的潜在重要靶点。