Dissecting Tumor Heterogeneity by Analyzing Signaling Pathway Requirements.

描述（由申请人提供）：20-30%的乳腺癌中存在HER2 （Neu, ErbB2）的扩增和过表达。尽管开发了靶向治疗，如赫赛汀，但治疗失败的病例比例高得惊人，可能是由于激活了绕过治疗的额外信号通路。了解诸如E2F转录因子等通路在这一过程中的作用，对于改善HER2+乳腺癌的治疗至关重要。我们工作的长期目标是通过分子和生物信息学手段阐明乳腺癌的机制和进展，特别关注E2Fs。该项目的直接目标是建立E2Fs在HER2+乳腺癌小鼠模型中的作用，确定其作用机制，并研究这些途径如何在人类乳腺癌中被利用。该建议的中心假设是E2F转录因子介导HER2+乳腺癌。我们的假设是基于小鼠模型系统的结果和人类乳腺癌基因表达的初步结果。具体来说，生物信息学预测证明了E2Fs在MMTV-Neu小鼠HER2+乳腺癌模型和人类HER2+肿瘤样本中的不同作用。与E2F基因敲除的mmtv - new小鼠杂交的初步结果也支持这一假设。这项研究的基本原理是，一旦知道了E2Fs如何调节HER2+乳腺癌，下游靶点就可以被靶向治疗，从而产生新的和创新的治疗方法。我们计划通过调查以下三个具体目标来检验我们的中心假设并实现本应用程序的目标。在第一个目标中，我们将通过基因杂交来验证E2Fs在小鼠模型系统中调节HER2+乳腺癌的假设，我们在MMTV-Neu转基因模型系统中切除单个E2Fs。在第二个目标中，我们将通过基因表达研究阐明E2Fs调节肿瘤潜伏期、生长速度、组织学和转移的遗传机制，并通过体外和体内试验得到证实。本目的目的是确定特定E2Fs影响肿瘤发生的遗传机制，并验证这些遗传途径。在最终目的中，我们将评估E2F转录因子在HER2阳性人乳腺癌中的作用。这一建议具有创新性，因为它将阐明E2F转录因子在HER2+乳腺癌中的新作用。这将为e2f的作用提供一种新的解释，而不是将e2f简单地视为细胞周期调节剂的传统思维。这一贡献意义重大，因为

DESCRIPTION (provided by applicant): Amplification and overexpression of HER2 (Neu, ErbB2) is noted in 20-30% of breast cancers. Despite development of targeted therapies such as Herceptin, treatment fails in an alarmingly high proportion of cases, likely due to activation o additional signaling pathways that circumvent treatment. Understanding the role of pathways, such as the E2F transcription factors, in this process will be critical for refining treatment for HER2+ breast cancer. The long term goal of our work is to elucidate the mechanism and progression of breast cancer through molecular and bioinformatic means, with a particular focus on the E2Fs. The immediate objective of this project is to establish the role of the E2Fs in a mouse model of HER2+ breast cancer, determine the mechanism of action and examine how these pathways are utilized in human breast cancer. The central hypothesis of this proposal is that the E2F transcription factors mediate HER2+ breast cancer. Our hypothesis has been predicated on results from a mouse model system and from preliminary results using gene expression from human breast cancer. Specifically, bioinformatic predictions demonstrated differential roles for the E2Fs both in the MMTV-Neu mouse model of HER2+ breast cancer and in human HER2+ tumor samples. Initial results from interbreeding MMTV-Neu mice with E2F knockouts also support this hypothesis. The rationale for the proposed research is that, once it is known how E2Fs regulate HER2+ breast cancer, the downstream targets can be therapeutically targeted, resulting in new and innovative approaches to treatment. We plan to test our central hypothesis and accomplish the objective of this application by investigating the following three specific aims. In the first aim we will test the hypothesis that the E2Fs regulate HER2+ breast cancer in mouse model systems through genetic crosses where we ablate individual E2Fs in the MMTV-Neu transgenic model systems. In the second aim we will elucidate the genetic mechanisms by which E2Fs regulate alterations to tumor latency, growth rate, histology and metastasis through gene expression studies, confirmed through in vitro and in vivo tests. The objective of this aim is to define the genetic mechanisms by which specific E2Fs affect tumorigenesis and to validate these genetic pathways. In the final aim we will assess the role of E2F transcription factors in HER2+ human breast cancer. This proposal is innovative because it will elucidate a novel role for E2F transcription factors in HER2+ breast cancer. This will offer a novel interpretation of the role of E2Fs, as opposed to traditional thinking that places E2Fs simply as cell cycle regulators. This contribution is significant because it will establish a role for the E2Fs in HER2+ breast cancer. Clearly this project will define the role, mechanism and human impact of the E2Fs in HER2+ breast cancer. Once the role for E2Fs in tumor development and progression is determined, the E2Fs will be explored as a clinical biomarker in future work. The implications of uncovering a role for E2Fs in regulation of HER2+ breast cancer are profound, with the potential for development of clinical therapies to enhance survival.