HER-2/IGF-IR cross-talk and Herceptin resistance

描述(申请人提供)：Rita Nahta博士的职业目标是成为一名独立研究员，专注于乳腺癌耐药的分子机制，对靶向治疗和生长因子受体特别感兴趣。这一K01奖将帮助她过渡到一名完全独立的科学研究人员。未来一两年将是她在Francisco J.Esteva博士和Mien-Chie Hung博士的指导下，在纳米技术和动物模型领域磨练分子生物学技能和发展新技能的关键。安德森癌症中心为实施拟议的研究计划提供了一个极好的协作环境。Esteva博士和Hung博士在科学界享有很高的声誉，Nahta博士将受益于他们在信号转导、耐药性、分子治疗学、细胞周期调节和翻译研究领域的联合专业知识。乳腺癌转化研究实验室由Esteva博士指导，是Hung博士指导的乳腺癌研究计划的组成部分。该项目激动人心的智力和科学环境将极大地促进Nahta博士的职业发展。纳塔博士目前的研究重点是对HER-2靶向抗体Herceptin产生耐药性的分子机制。使用她开发的赫赛汀耐药体外模型，她观察到以下情况：1)在耐药细胞中，HER-2与IGF-IR形成独特的异源二聚体。该复合体中的HER-2被磷酸化，提示从IGF-IR到HER-2的串扰；2)位于HER-2和IGF-IR下游的p27kip1在耐药细胞中下调。异位表达p27kip1可恢复Herceptin的敏感性。基于这些发现，这一应用的中心假设是Herceptin耐药性是通过Her-2与IGFIR结合增加以及随后乳腺癌细胞中p27kip1的降解而介导的。我们的具体目标是：1)研究HER-2和IGF-IR之间的相互作用；2)确定HER-2/IGF-IR下调p27kip1的分子机制；3)研究HER-2/IGF-IR作为体内治疗靶点的作用。我们将使用GST下拉试验、纳米技术、蛋白质分析、聚合酶链式反应、siRNA转染法和小鼠体内研究。我们的研究将最终确定最有可能对赫赛汀有反应的肿瘤，并将指导开发更有效的针对HER-2过度表达的乳腺癌的靶向治疗。

DESCRIPTION (provided by applicant): Dr. Rita Nahta's career goal is to become an independent researcher focused on the molecular mechanisms of drug resistance in breast cancer with a specific interest in targeted therapeutics and growth factor receptors. This K01 Award will assist her transition to a fully independent scientific investigator. The next year or two will be critical for polishing her molecular biology skills and developing new skills in the areas of nanotechnology and animal models under the mentorship of Drs. Francisco J. Esteva and Mien-Chie Hung. The M. D. Anderson Cancer Center offers an excellent collaborative environment for implementation of the proposed research plan. Drs. Esteva and Hung are highly regarded among the scientific community, and Dr. Nahta will benefit from their combined expertise in the areas of signal transduction, drug resistance, molecular therapeutics, cell cycle regulation and translational research. The Breast Cancer Translational Research Laboratory, which is directed by Dr. Esteva, is an integral component of the Breast Cancer Research Program directed by Dr. Hung. The stimulating intellectual and scientific environment of this program will greatly enhance Dr. Nahta's career development. Dr. Nahta's current research focus is on the molecular mechanisms of resistance to the HER-2-targeted antibody Herceptin. Using an in vitro model of Herceptin resistance that she developed, she observed the following: 1) HER-2 forms a unique heterodimer with IGF-IR in resistant cells. HER-2 in this complex is phosphorylated, suggesting cross-talk from IGF-IR to HER-2; 2) p27kip1, which lies downstream of both HER-2 and IGF-IR, is downregulated in resistant cells. Ectopic expression of p27kip1 restores Herceptin sensitivity. Based on these findings, the central hypothesis of this application is that Herceptin resistance is mediated by increased binding of HER-2 to IGFIR with subsequent degradation of p27kip1 in breast cancer cells. Our specific aims are to: 1) Characterize the interaction between HER-2 and IGF-IR; 2) Define the molecular mechanism by which HER-2/IGF-IR downregulates p27kip1; 3) Investigate HER-2/IGF-IR as a therapeutic target in vivo. We will use GST pulldown assays, nanotechnology, protein assays, PCR, siRNAtransfection, and in vivo mouse studies. Our studies will ultimately allow the identification of tumors most likely to respond to Herceptin, and will guide the development of more effective targeted therapies for HER-2-overexpressing breast cancer.