(PQB6) Genetics of Subclonal Evolution in Pancreatic Cancer

描述(申请人提供)：实体肿瘤90%的癌症死亡与转移有关。尽管如此，与癌变、细胞通路失控或治疗耐药相比，转移形成的机制研究相对较少。合乎情理的是，对转移的重点研究提供了通过确定治疗发展的方面来提高存活率的机会。这项提议将解决B-6组的挑衅性问题，“考虑到研究转移的困难，我们能否开发新的方法，如工程组织移植，来研究肿瘤扩散的生物学？”这一建议的假设是，原发癌内的亚克隆遗传进化选择了生存表型，这些表型的结果是转移。我们提出了三个迭代目标来解决我们的假设。在我们的第一个目标中，我们将确定亚克隆进化在多大程度上产生了肿瘤内的遗传异质性和原发部位内的转移亚克隆。为此，我们将应用原发和转移组织的深度测序来确定转移的遗传基础，并结合克隆进化的计算模型。在我们的第二个目标中，我们将确定在胰腺癌进展过程中亚克隆进化非随机选择特定基因或途径的程度。这一目标将依赖于对测序文库的生物信息学分析来确定在肿瘤进展中具有重要意义的核心途径，以及基于基因和使用各种模型确定的核心途径的转移形成机制研究。在我们的第三个目标中，我们将确定非遗传因素，如EMT、致癌间质信号或免疫渗透在多大程度上与转移亚克隆的亚克隆进化相关。这一目标将依赖于与高通量生物标记物筛选相关的转移亚克隆的无偏见表达分析。这一提议的预期总体影响将是它可能导致我们对肿瘤进展和转移的遗传基础的理解的范式改变，并识别亚克隆进化一贯靶向的核心途径和功能。要知道这一点很重要，因为最终目标是设计针对转移表型并考虑遗传异质性的治疗方法，而不是针对迄今几乎没有显示出优势的特定基因。

DESCRIPTION (provided by applicant): Metastasis is responsible for 90% of cancer deaths from solid tumors. Despite this reality, the mechanisms of metastasis formation are relatively understudied compared to that of carcinogenesis, deregulation of cellular pathways, or treatment resistance. It stands to reason that focused studies of metastasis provide opportunities to improve survival by identifying aspects for therapeutic development. This proposal will address Provocative Question Group B-6, "Given the difficulty of studying metastasis, can we develop new approaches, such as engineered tissue grafts, to investigate the biology of tumor spread?" The hypothesis of this proposal is that subclonal genetic evolution within a primary carcinoma selects for prosurvival phenotypes, and the consequence of these phenotypes is metastasis. We propose three iterative Aims to address our hypothesis. In our first aim, we will determine the extent to which subclonal evolution generates intratumoral genetic heterogeneity and metastatic subclones within the primary site. For this aim we will apply deep sequencing of primary and metastatic tissues to determine the genetic basis of metastasis, in association with computational modeling of clonal evolution. In our second aim, we will determine the extent to which subclonal evolution nonrandomly selects for specific genes or pathways during pancreatic cancer progression. This aim will rely upon bioinformatics analyses of sequencing libraries to identify core pathways of significance in tumor progression, coupled with mechanistic studies of metastasis formation based on genes and core pathways identified using a variety of models. In our third aim, we will determine the extent to which non-genetic factors such as EMT, oncogenic stromal signaling or immune infiltration correlates with subclonal evolution in the development of metastatic subclones. This aim will rely on unbiased expression analyses of metastatic subclones in association with high-throughput biomarker screening. The expected overall impact of this proposal will be its potential to cause a paradigm change in our understanding of the genetic basis of tumor progression and metastasis, and to identify the core pathways and functions consistently targeted by subclonal evolution. This is important to know for the ultimate goal of devising therapies that target the metastatic phenotype and that take genetic heterogeneity into account, rather than targeting of specific genes that has shown little advantage thus far.