A novel therapy for HER2 positive hormone refractory breast cancer

HER2阳性激素难治性乳腺癌的新疗法

• 批准号: 7814609
• 负责人: ANNE W. HAMBURGER
• 金额: $ 46.78万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7814609
• 关键词: Address; Animal Model; Area; Binding; Binding Proteins; Biological Assay; Breast Cancer Cell; Bypass; Cell Line; Cells; Clinic; Clinical; DNA; Data; Development; Disease Resistance; Down-Regulation; Drug Delivery Systems; ERBB2 gene; Endocrine; Enzymes; ErbB Receptor Family Protein; Estrogen Antagonists; Estrogen Receptor Modulators; Event; Genetic Transcription; Goals; Hormones; In Vitro; Laboratories; Lead; Malignant Neoplasms; Measures; Messenger RNA; Pharmaceutical Preparations; Phenotype; Phosphorylation; Phosphotransferases; Proteins; RNA Binding; RNA-Binding Proteins; Receptor Signaling; Recurrence; Refractory; Regulation; Reporter; Resistance; Signal Transduction; Tamoxifen; Testing; Therapeutic Agents; Translational Research; Trastuzumab; attenuation; base; cell growth; chemotherapy; design; hormone resistance; hormone sensitivity; in vitro testing; in vivo; inhibitor/antagonist; mRNA Stability; malignant breast neoplasm; mortality; novel; novel therapeutics; overexpression; preclinical study; promoter; public health relevance; receptor; restoration; small hairpin RNA; therapeutic target; therapy development; tumor progression

DESCRIPTION (provided by applicant): This application addresses the broad Challenge Area (15) Translational Science, and specific Challenge Topic, 15-CA-102: Understanding mechanisms of hormone refractory cancers for therapeutic targeting. The development of hormone resistance in breast cancer is a significant clinical problem. The enhanced expression of the ErbB2/3 heterodimer leads to the ability of breast cancer cells to bypass normal endocrine responsiveness. However, the use of ErbB2 targeted- agents such as Trastuzumab for hormone resistant disease in the clinic has been disappointing. Thus, new strategies that reduce the activity of the ErbB2/3 heterodimer are urgently needed for treatment of hormone refractory breast cancer. EBP1, a protein isolated in our laboratory by its binding to ErbB3, is a negative regulator of ErbB2/3 signal transduction due to its ability to downregulate ErbB2 protein levels. Preclinical studies from our laboratory demonstrate that ecoptic expression of EBP1 increases sensitivity of breast cancer cells to the antiestrogen tamoxifen. Further, depletion of EBP1 protein by shRNA or inactivation of EBP1 by phosphorylation by PAK1, a kinase implicated in both breast cancer progression and tamoxifen resistance, results in development of the hormone refractory phenotyope. These data suggest that EBP1, by decreasing ErbB2 protein levels, can diminish ErbB2/3 receptor signaling that leads hormone resistance. We propose that EBP1 based therapies may be effective in reversing hormone resistance. Our ongoing in vitro and in vivo data indicate that an understanding of EBP1's mechanism of action will illuminate ErbB2 regulation and thus offer a new avenue for treatment of hormone refractory breast cancer. The aim of this proposal is to understand the mechanism by which EBP1 decreases ErbB2 protein levels and how deletion or inactivation of EBP1 contributes to hormone resistance. In addition, we hypothesize that PAK1 directed therapies may reverse hormone resistance in part via their ability to restore EBP1 function and reduce ErbB2 levels. We anticipate that these studies will lead to new therapies for treatment of ErbB2+, hormone resistant breast cancer. In Specific Aim 1, we will determine the mechanism of EBP1's attenuation of ErbB2 levels with the ultimate goal of developing EBP1 based therapies to downregulate ErbB2 expression. As several independent groups have demonstrated that EBP1 is both a DNA and RNA binding protein, we will examine effects on EBP1 on ErbB2 transcription and post-transcriptional events. We will therefore a) determine EBP1 induced changes in ErbB2 transcription using both promoter reporter and ChIP assays b) measure EBP1-induced changes in ErbB2 mRNA stability. We will extend studies indicating EBP1 binds ErbB2 mRNA and determine the region of EBP1 critical for RNA binding and the effects of phosphorylation of EBP1 on such binding and ErbB2 mRNA stability. The region of ErbB2 mRNA that binds EBP1 will also be determined and the function of this region in maintaining ErbB2 mRNA stability assessed. In Specific Aim 2, we will determine how to overcome PAK1 inactivation of EBP1 function for treatment of hormone refractory cancer. In Specific Aim 2a, we will demonstrate that PAK1 disables EBP1 and contributes to tamoxifen resistance. First, the ability of PAK1 to abrogate the EBP1 downregulation of ErbB2 mRNA and protein levels will be assessed. We will also determine if an EBP1 that cannot be phosphorylated by PAK1 can rescue PAK1 induced tamoxifen resistance. In Specific Aim 2b, we will test the ability of PAK1 inhibitors to ameliorate the hormone refractory phenotype via restoration of EBP1 activity. The effect of PAK1 inhibitors on EBP1 phosphorylation, tamoxifen sensitivity and ErbB2 levels in hormone resistant cell lines will be tested in vitro. In addition, the ability of combinations of PAK1 and ErbB2 inhibitors to reverse hormone resistance will be tested in vitro based on the hypothesis that a combined approach to target the ErbB2 receptor may be efficacious. Finally, we will confirm in vitro results by demonstrating the importance of EBP1 for tamoxifen sensitivity in animal models. These studies will then form the basis for in vivo trials of PAK1 inhibitors in tamoxifen resistant breast cancer cells. We suggest that EBP1 can form the basis of a new class of therapeutic agents for treatment of ErbB2+, hormone refractory breast cancer. Drugs can be based either on the structural components of EBP1 or on PAK1 inhibitors that will reactivate EBP1 function. EBP1 based therapies, in conjunction with currently available ErbB2 targeted drugs, may offer a new avenue for the development of treatments to reverse hormone resistance. PUBLIC HEALTH RELEVANCE: Despite numerous advances in therapies for breast cancer in recent years, recurrence and mortality remain high. Deregulation of the ErbB receptor family, a group of enzymes which stimulates cell growth, leads to resistance to chemotherapy and hormone treatment. We have cloned and characterized EBP1, an ErbB binding protein that decreases levels and activity of ErbB receptors, thus restoring sensitivity to hormone treatments. The current study is designed to determine how EBP1 regulates ErbB expression and hormone sensitivity. Our studies would establish EBP1 as a new therapeutic agent in breast cancer to restore hormone sensitivity in cells which overexpress ErbB receptors.

描述（由申请人提供）：本申请涉及广泛的挑战领域（15）转化科学和特定的挑战主题，15-CA-102：了解激素难治性癌症的治疗靶向机制。乳腺癌中激素抵抗的发展是一个重要的临床问题。ErbB 2/3异二聚体的表达增强导致乳腺癌细胞绕过正常内分泌反应的能力。然而，在临床中使用ErbB 2靶向剂如曲妥珠单抗治疗激素抵抗性疾病令人失望。因此，迫切需要降低ErbB 2/3异二聚体活性的新策略来治疗激素难治性乳腺癌。EBP 1是我们实验室通过与ErbB 3结合而分离的蛋白质，由于其能够下调ErbB 2蛋白水平，因此是ErbB 2/3信号转导的负调节因子。我们实验室的临床前研究表明，EBP 1的ecoptic表达增加了乳腺癌细胞对抗雌激素他莫昔芬的敏感性。此外，EBP 1蛋白的消减或EBP 1的失活通过磷酸化PAK 1，一种激酶参与乳腺癌的进展和他莫昔芬耐药性，导致激素难治性表型的发展。这些数据表明，EBP 1通过降低ErbB 2蛋白水平，可以减少导致激素抵抗的ErbB 2/3受体信号传导。我们提出基于EBP 1的疗法可能有效逆转激素抵抗。我们正在进行的体外和体内数据表明，对EBP 1作用机制的理解将阐明ErbB 2的调节，从而为治疗激素难治性乳腺癌提供新的途径。该提案的目的是了解EBP 1降低ErbB 2蛋白水平的机制以及EBP 1的缺失或失活如何有助于激素抵抗。此外，我们假设PAK 1导向疗法可能部分通过其恢复EBP 1功能和降低ErbB 2水平的能力来逆转激素抵抗。我们预计，这些研究将导致治疗ErbB 2+，激素抵抗性乳腺癌的新疗法。在具体目标1中，我们将确定EBP 1减弱ErbB 2水平的机制，最终目标是开发基于EBP 1的疗法来下调ErbB 2表达。由于几个独立的研究小组已经证明EBP 1是一种DNA和RNA结合蛋白，我们将研究EBP 1对ErbB 2转录和转录后事件的影响。因此，我们将a）使用启动子报告基因和ChIP测定来确定EBP 1诱导的ErbB 2转录的变化B）测量EBP 1诱导的ErbB 2 mRNA稳定性的变化。我们将扩展研究表明EBP 1结合ErbB 2 mRNA，并确定该地区的EBP 1的关键RNA结合和EBP 1的磷酸化对这种结合和ErbB 2 mRNA的稳定性的影响。还将确定结合EBP 1的ErbB 2 mRNA区域，并评估该区域在维持ErbB 2 mRNA稳定性中的功能。在具体目标2中，我们将确定如何克服EBP 1功能的PAK 1失活，以治疗激素难治性癌症。在具体目标2a中，我们将证明PAK 1禁用EBP 1并有助于他莫昔芬耐药性。首先，将评估PAK 1消除ErbB 2 mRNA和蛋白水平的EBP 1下调的能力。我们还将确定不能被PAK 1磷酸化的EBP 1是否可以挽救PAK 1诱导的他莫昔芬耐药性。在特定目标2b中，我们将测试PAK 1抑制剂通过恢复EBP 1活性改善激素难治性表型的能力。将在体外测试PAK 1抑制剂对激素抗性细胞系中EBP 1磷酸化、他莫昔芬敏感性和ErbB 2水平的影响。此外，基于靶向ErbB 2受体的组合方法可能有效的假设，将在体外检测PAK 1和ErbB 2抑制剂组合逆转激素抗性的能力。最后，我们将通过在动物模型中证明EBP 1对他莫昔芬敏感性的重要性来证实体外结果。这些研究将为PAK 1抑制剂在他莫昔芬耐药乳腺癌细胞中的体内试验奠定基础。我们认为，EBP 1可以形成一类新的治疗药物治疗ErbB 2+，激素难治性乳腺癌的基础。药物可以基于EBP 1的结构成分或PAK 1抑制剂，其将重新激活EBP 1功能。基于EBP 1的疗法，结合目前可用的ErbB 2靶向药物，可能为开发逆转激素抵抗的治疗方法提供新的途径。 公共卫生相关性：尽管近年来乳腺癌治疗取得了许多进展，但复发率和死亡率仍然很高。ErbB受体家族（一组刺激细胞生长的酶）的失调导致对化疗和激素治疗的抵抗。我们已经克隆并鉴定了EBP 1，这是一种ErbB结合蛋白，可降低ErbB受体的水平和活性，从而恢复对激素治疗的敏感性。目前的研究旨在确定EBP 1如何调节ErbB表达和激素敏感性。我们的研究将确立EBP 1作为乳腺癌的新治疗剂，以恢复过表达ErbB受体的细胞中的激素敏感性。