INSULIN-LIKE GROWTH FACTOR ACTION IN BREAST CANCER CELLS

该提案的目标是调查 胰岛素样生长因子在人乳腺癌生物学中的作用 以及这些因素刺激有丝分裂的机制是什么 系统。长期目标是使用这些研究来定义 这种疾病的肿瘤进展背后的生化事件 确定治疗干预的新靶点。以前的工作有 研究表明，IGF-I和IGF-II在某些细胞中诱导了显著的有丝分裂反应 通过与IGF-I受体结合建立乳腺癌细胞系。此外， IGF-II在雌激素依赖细胞系中的过表达使一些 雌激素独立性的几个方面。此外，乳房中的基质细胞 肿瘤表达IGF-II，而肿瘤细胞只在少数 案子。综上所述，这些数据暗示IGF是潜在的旁分泌 对乳腺肿瘤细胞生长和IGF-II表达的调节作用 肿瘤细胞可能是肿瘤进展中的一个事件，它允许细胞 从基质因素中独立出来。 目前的提案旨在确定IGFS对乳腺癌的影响 更详细的细胞生长，探索IGFS与 激素剂和维甲酸及其与生长效应的相关性 IGF-I受体表达、酪氨酸激酶活性和 自动磷酸化。然后，该系统将被用作模型， 研究增殖剂转导的机制细节 通过IGFS发送信号。初步结果显示IGFS激活了IGF-I 受体酪氨酸激酶及其随后的β-磷酸化- 亚基和其他几种底物，包括pp185(IRS1)、GAP和 与GAP相关的pp62。目前的研究集中在进一步定义这些 在确定事件的功能后果方面具有重要意义。互动 将对pp185和与其他蛋白质的GAP进行表征和评估 在对IGF有反应和无反应的细胞系中，IGF-II转染体和 用抗雌激素和分化剂处理的细胞。特定的 事件和交互将与 增殖和转化表型。带间隙的传递 将使用表达载体来评估GAP-RAS的作用 调解这些事件的复杂性。

The goals of the proposal are the investigation of the role played by insulin-like growth factors (IGFs) in the biology of human breast cancer and of the mechanism by which these factors stimulate mitogenesis in this system. the long term aim is to use these studies to define the biochemical events underlying tumor progression in this disease and to identify new targets for therapeutic intervention. Previous work has shown that IGF-I and IGF-II elicit a marked mitogenic response in some breast cancer cell lines by binding to the IGF-I receptor. Moreover, overexpression of IGF-II in an estrogen-dependent cell line confers some aspects of estrogen independence. In addition, stromal cells in breast tumors express IGF-II, whereas tumor cells do in only a minority of cases. Taken together, the data imply that IGFs are potential paracrine regulators of breast tumor cell growth and that expression of IGF-II by the tumor cell may be an event in tumor progression that allows the cell to become independent of stromal factors. The current proposal aims to define the effects of IGFs on breast cancer cell growth in more detail, exploring the interactions of IGFs with hormonal agents and retinoic acid and correlating growth effects with IGF-I receptor expression, tyrosine kinase activity and autophosphorylation. The system will be then used as a model with which to study the mechanistic details of the transduction of the proliferative signal by IGFs. Preliminary results reveal that IGFs activate the IGF-I receptor tyrosine kinase with subsequent phosphorylation of its beta- subunit and several other substrates, including pp185 (IRS1), GAP, and GAP-associated pp62. Current studies focus on further defining these events and in identifying their functional consequences. Interactions of pp185 and GAP with other proteins will be characterized and assessed in IGF-responsive and unresponsive cell lines, IGF-II transfectants, and cells treated with antiestrogens and differentiation agents. Specific events and interactions will be correlated with aspects of the proliferative and transformed phenotype. Transfections with GAP expression vectors will be performed to evaluate the role of the GAP-ras complex in mediating these events.