BREAST CANCER & AGING--A SOMATIC CELL GENETICS APPROACH

描述：乳腺癌是发病的主要原因之一， 美国和其他工业化国家妇女的死亡率; 最新的统计数据显示，乳腺癌的发病率正在上升， 60岁以上女性的癌症。自然和环境 雌激素似乎参与了致癌的几个阶段， 过程，尤其是在更年期和绝经后时期。 雌激素通过调节靶细胞的增殖， 两步机制在第一步，雌激素介导增加 在第二步中，它们抑制细胞增殖， （关闭）。如果没有严格回应后一个正常的失败- 安全机制可能最终导致乳腺肿瘤发生。虽然 第二步比第一步更难理解，它提供了理论上的 DES治疗晚期乳腺癌成功的原因。 本申请所述的目的是了解 参与了雌激素诱导的增殖关闭。使用MCF 7 细胞，我们已经成功地分离了仅表达 两个雌激素介导的步骤之一：a）变体E8 CASS表达 仅关闭（步骤II）和B）变体A2 E8 CASS仅表达步骤 I.除了上述与致癌物质的相关性外， 这些变异提供了一个研究模型， 从雌激素敏感性发展到抵抗性。这代表 这是我们探索细胞调控的一个重要里程碑 在正常条件下增殖，并进入初始和 向恶性肿瘤发展。 这项建议的具体目的是分离独特的mRNA序列 介导雌激素诱导的抑制细胞增殖 乳腺癌细胞流式细胞术将用于表征 增殖关闭的动力学;这是需要找到 合适的条件来引发增殖性关闭。独特的mRNA 负责关断的序列将使用两个 互补方法：a）消减文库/遗传筛选 方法（Wang & Brown），和B）差异显示方法（Liang & Pardee）。由此获得的候选物将被克隆到哺乳动物中。 由诱导型启动子控制的表达载体。他们的 将在细胞中测试表达和引起关闭反应的能力。 培养和在裸鼠中。从这个实验中获得的知识 设计将有助于设计更好的预后和治疗工具 对抗乳腺癌，尤其是雌激素受体阳性的 老年妇女的多样性。

DESCRIPTION: Breast cancer is one of the leading causes of morbidity and mortality among women in America and other industrialized countries; latest statistics show that there is an increased incidence of breast cancer among women above 60 years of age. Natural and environmental estrogens appear to be involved at several stages of the carcinogenetic process, especially during menopause and postmenopausic periods. Estrogens regulate the proliferation of their target cells through a two-step mechanism. In the first step, estrogens mediate an increase of the cell number; in the second step, they inhibit cell proliferation (shutoff). Failure to stringently respond to this latter normal fail- safe mechanism may eventually result in breast tumorigenesis. Although this Step-II is less understood than Step-I, it provides the theoretical explanation for the success of DES treatment in advanced breast cancer. The stated purpose of this application is to understand the mechanisms involved in the estrogen-induced proliferative shutoff. Using MCF7 cells, we have succeeded in segregating fixed phenotypes expressing only one of the two estrogen-mediated steps: a) variant E8CASS expresses only the shutoff (Step- II) and b) variant A2E8CASS expresses only Step- I. In addition to the above mentioned relevance to the carcinogenetic process in the breast, these variants provide a model to study progression from estrogen sensitivity to resistance. This represents an important milestone in our quest to explore the regulation of cell proliferation under normal conditions and into the initial and progressive paths toward malignancy. The specific aim of this proposal is to isolate unique mRNA sequences that mediate the estrogen-induced inhibition of the proliferation of breast cancer cells. Flow cytometry will be used to characterize the kinetics of the proliferative shutoff; this is required to find the appropriate conditions to evoke a proliferative shutoff. Unique mRNA sequences responsible for the shutoff will be isolated using two complementary approaches: a) a subtraction library/genetic screen method (Wang & Brown), and b) a differential display method (Liang & Pardee). Candidates thus obtained will be cloned into mammalian expression vectors controlled by an inducible promoter. Their expression and ability to evoke a shutoff response will be tested in cell culture and in nude mice. Knowledge gathered from this experimental design will contribute to devise better prognostic and therapeutic tools to fight breast cancer, especially the estrogen receptor-positive variety in older women.