IRS-1 and -2 signaling in mammary development and cancer

描述（由申请人提供）：胰岛素受体底物1和2 （IRSs）是胰岛素样生长因子- 1受体（IGF-IR）下游的大接头蛋白，调节正常生长、代谢、生存和分化。最近的研究表明，IRSs可以与许多癌基因相互作用，并且在功能上是许多癌基因转化能力所必需的，并且IRSs在包括乳腺癌在内的许多人类肿瘤中升高和过度活跃。这些研究的长期目标是了解胰岛素受体底物（IRSs）在乳腺癌中的作用，并确定它们是否可能在预测抗igf - ir抑制剂的反应中起作用。

DESCRIPTION (provided by applicant): Insulin receptor substrates 1 and 2 (IRSs) are large adaptor proteins downstream of insulin-like growth factor-I receptor (IGF-IR) which modulate normal growth, metabolism, survival, and differentiation. Recent studies have shown that IRSs can interact with, and are functionally required for the transforming ability of many oncogenes, and IRSs are elevated and hyperactive in many human tumors including breast cancer. The long-term goal of these studies is to understand the role of inuslin receptor substrates (IRSs) in breast cancer, and determine if they may have a role in predicting response to anti-IGF-IR inhibitors. To better understand the role of IRSs in mammary gland development and breast cancer, in the last funding period, we created and studied several novel in vitro and in vivo models of IRS action. Using IRS-null mice we found that IRSs are required for embryonic mammary bud formation and for maximal lactation. Using human immortalized MCF-10A cells we showed that overexpression of IRSs disrupted formation of acini by altering polarity, proliferation, and survival. Finally, we generated transgenic mice with mammary-specific overexpression of either IRS-1 or IRS-2 with both lines of mice displaying progressive mammary hyperplasia, tumors, and metastasis. Intriguingly, studies from others using IRS-2-null mice have shown that only IRS-2 is required for mammary tumor metastasis. These studies have raised three fundamental questions: 1) How do IRSs modulate mammary cell polarity, transformation, and tumorigenesis? 2) Why do both IRS-1 and IRS-2 cause transformation, but only IRS-2 is required for metastasis? 3) Are IRSs important in breast cancer progression and prognosis, and can levels and/or activity predict response to anti-IGF-IR inhibitors? We will address these questions with the following specific aims: 1) Do both IRS-1 and IRS-2 disrupt morphogenesis of MCF-10A acini via aPKC mediated disruption of the polarity complex, and promote proliferation and survival downstream of IGF-IR? 2) Does IRS-2 utilize a unique bi-directional positive regulation of NF-?B activity to modulate migration, invasion, and metastasis? 3) Are IRSs important in breast cancer progression and prognosis, and can they be used as predictors of response to anti-IGF-IR therapy? The long-term impact of these studies will be a better understanidng of IRS action in breast cancer, and a possible new biomarker for predicting response to IGF-IR inhibitors in breast cancer. PUBLIC HEALTH RELEVANCE: The goal of this study is to better understand the role of signaling adaptors (IRSs) in breast cancer. The study will elucidate IRS function, and then translate this into human breast cancer to test if they affect patient prognosis and predict response to anti-IGF-IR inhibitors.