Dissecting Tumor Heterogeneity by Analyzing Signaling Pathway Requirements.

描述(申请人提供)：HER2(Neu，ErbB2)扩增和过度表达在20-30%的乳腺癌中被发现。尽管开发了赫赛汀等靶向治疗，但治疗失败的病例比例高得令人震惊，可能是由于激活了绕过治疗的额外信号通路。了解E2F转录因子等途径在这一过程中的作用对于完善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，特别是E2F。该项目的近期目标是建立E2F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用于人类乳腺癌。这一建议的中心假设是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使用人类乳腺癌基因表达的初步结果。具体地说，生物信息学预测显示E2F在HER2+乳腺癌MMTV-Neu小鼠模型和人类HER2+肿瘤样本中的作用不同。与E2F基因敲除的MMTV-Neu小鼠杂交的初步结果也支持这一假设。这项拟议研究的基本原理是，一旦知道E2F是如何调控HER2+乳腺癌的，下游靶点就可以成为治疗靶点，从而产生新的创新治疗方法。我们计划测试我们的中心假设，并通过调查以下三个具体目标来实现此应用程序的目标。在第一个目标中，我们将通过基因杂交在MMTV-Neu转基因模型系统中去除单个E2F，在小鼠模型系统中验证E2F调节HER2+乳腺癌的假设。在第二个目标中，我们将通过体外和体内试验证实的基因表达研究，阐明E2F调节肿瘤潜伏期、生长速度、组织学和转移的遗传机制。其目的是确定特定的E2F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+人乳腺癌中的作用。这项建议是创新的，因为它将阐明E2F转录因子在HER2+乳腺癌中的一个新角色。这将为E2F的作用提供一种新的解释，而不是传统的将E2F简单地定位为细胞周期调节因子的想法。这一贡献意义重大，因为 这将为E2F在HER2+乳腺癌中发挥作用奠定基础。显然，这个项目将确定E2F在HER2+乳腺癌中的作用、机制和对人类的影响。一旦确定E2F在肿瘤发生发展中的作用，将在未来的工作中探索E2F作为临床生物标记物的作用。发现E2Fs在调节HER2+乳腺癌中的作用具有深远的意义，具有开发临床治疗以提高生存率的潜力。

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.