ROLE OF IGFS AND THEIR BINDING PROTEINS IN THE GROWTH OF BREAST CANCER

胰岛素样生长因子(IGF)-I和II是有效的有丝分裂原 乳腺肿瘤。我们假设它们对生长的调节作用是 胰岛素样生长因子结合蛋白(IGFBPs)在很大程度上由六种蛋白组成 新近克隆的乳房合成和分泌的多肽 癌细胞。使用激素反应的N-亚硝基甲基脲(NMU)- 诱导大鼠乳腺肿瘤，我们计划研究该基因的表达和 体内激素和多胺对IGF和IGFBPs的调节作用。 由于NMU肿瘤的多激素依赖性，我们将能够 来考察不同类别的 雌激素、催乳素和孕酮等激素对其表达的影响 这些多肽中的一个。原位杂交与免疫组织化学 技术将使我们能够解决异构性问题 不同亚群的乳腺癌细胞的表达。 乳腺肿瘤组织与正常乳腺组织的差异 动物也将接受检查。我们计划直接评估这些行动 使用转基因技术和外源给药的IGFBPs 实验和培养中的人乳腺癌细胞中的IGFBPs。这个 以下终点将在我们的转基因和/或IGFBP中进行评估- 经处理的细胞：a)基础增殖活性；b)对 外源添加IGF-I和IGF-II的促生长作用 雌激素敏感性；d)对抗多胺治疗的敏感性；以及e) 裸鼠体内生长特点。我们将确定潜在的 调节IGF从IGFBPs释放到其靶点的机制 细胞可能在IGF刺激的肿瘤中起关键作用 成长。这些机制可能包括磷酸化和蛋白分解。 IGFBPs的加工及其与表面的相互作用 间质细胞和上皮细胞。激素和多胺的影响 对这些过程的操纵也将被检查。最后， IGF系统的潜在旁分泌效应将通过以下方式进行评估 基质细胞来源的生长调节作用的研究 靶上皮瘤细胞的条件培养液。对…的依赖 对IGF系统各组成部分的预期刺激反应将 使用中和抗体或定量检测进行免疫化学检测 免疫沉淀技术。

Insulin-like growth factors (IGF)-I and II are potent mitogens for mammary tumors. We hypothesize that their growth modulatory effects are governed, in large part, by IGF-binding proteins (IGFBPs), a class of six recently cloned polypeptides which are synthesized and secreted by breast cancer cells. Using the hormone-responsive N-nitrosomethylurea (NMU)- induced rat mammary tumor, we plan to investigate the expression and regulation by hormones and polyamines of IGFs and IGFBPs in vivo. Because of the multihormonal dependency of the NMU tumor, we will be able to examine the individual and combined effects of different classes of hormones such as estradiol, prolactin and progesterone on the expression of these peptides. In situ hybridization and immunohistochemistry techniques will allow us to address the issues of heterogeneous expression by different subpopulations of breast cancer cells. Differences between neoplastic and normal mammary tissue in the same animals will also be examined. We plan to directly evaluate the actions of IGFBPs using transfection techniques and exogenous administration of IGFBPs in experimental and human breast cancer cells in culture. The following endpoints will be assessed in our transfected and/or IGFBP- treated cells: a) basal proliferative activity; b) sensitivity to the growth-stimulatory effects of exogenously added IGF-I and -II; c) estrogen sensitivity; d) sensitivity to antipolyamine therapy; and e) in vivo growth characteristics in nude mice. We will determine potential mechanisms regulating the release of IGFs from the IGFBPs to their target cells since they may be critically involved in IGF-stimulated tumor growth. These mechanisms may include phosphorylation and proteolytic processing of the IGFBPs and their interactions with the surface of stromal and epithelial cells. The influence of hormonal and polyamine manipulations on these processes will also be examined. Finally, the potential paracrine effects of the IGF system will be assessed by studying the growth modulatory effects of stromal cell-derived conditioned medium on target epithelial tumor cells. The dependence of the projected stimulatory response on components of the IGF system will be tested immunochemically using neutralizing antibodies or quantitative immunoprecipitation techniques.