Genomic and Functional Identification of Chemotherapy Resistance Mechanisms in Small Cell Lung Cancer

项目摘要 小细胞肺癌（SCLC）每年仅在美国就造成超过30，000人死亡。 SCLC的两年生存率约为6%，与肺癌的其他主要亚型不同， 目前还没有针对SCLC的靶向治疗获批。SCLC最初对化疗高度敏感，但 迅速产生耐药性，导致约10个月内死亡。很明显，一个主要的未满足的治疗需求 SCLC的关键是确定新的治疗靶点和治疗策略，以对抗化疗耐药。 疾病我们对化疗耐药机制的理解一直受到缺乏 复发的人类SCLC组织由于罕见的手术切除。此外， 表现出短暂的潜伏期和化学敏感性。为了应对这些挑战，我们 来自30名患者的复发性SCLC的全外显子组测序。复发特异性基因组改变 WNT/APC/β-catenin通路在~66%的复发性SCLC中被鉴定，表明该通路 促进了耐药性。其次，我们开发了一种新的由Rb 1缺失驱动的SCLC小鼠模型， Trp 53和Myc的过表达是人类疾病中最常见的三种遗传改变。小鼠 在几周内发展SCLC，在组织病理学、生物标志物水平上与人类疾病高度相似 表达和化学敏感性，然后复发。该模型将成为测试候选人的有用工具 化疗耐药机制，并确定抑制化疗耐药的新的治疗靶点。的 本研究的目的是使用这种新的小鼠模型和全面的基因组分析的主要和 复发的人SCLC，以确定化疗耐药性的机制和新的治疗靶点， 对抗耐药性疾病。我们假设WNT/β-catenin通路的激活促进了 在SCLC中的化学抗性和靶向抑制途径将抑制化学抗性疾病。我们 预测我们的基因组和转录组分析的扩展将识别更多的新途径， 参与了化学抵抗。为了验证这些假设，我们将：1）鉴定在细胞中的复发性通路改变， 使用全基因组、外显子组、转录组和表观基因组测序的复发性人和小鼠SCLC 和2）在功能上确定经典WNT/β-连环蛋白信号传导和其他候选途径是否 是体内SCLC化疗耐药性的必要和充分条件。这种方法是创新的，因为我们将 对复发的人SCLC和一种新的SCLC进行无偏倚的综合基因组和表观基因组分析， SCLC的免疫活性小鼠模型，其概括了人类疾病的关键特征。WNT/β- 连环蛋白途径在SCLC中很大程度上未被探索。这项研究意义重大，因为目前没有 被批准用于SCLC的靶向治疗。更好地理解推动化疗的关键途径- SCLC中的耐药性将影响患有这种难治性疾病的患者的治疗和存活。

Project Summary Small cell lung cancer (SCLC) is responsible for over 30,000 deaths each year in the United States alone. SCLC has a two-year survival rate of ~6% and unlike the other major subtypes of lung cancer, there are currently no targeted therapies approved for SCLC. SCLC is initially highly responsive to chemotherapy, but rapidly develops resistance leading to mortality in ~10 months. Clearly, a major unmet need for the treatment of SCLC is the identification of new therapeutic targets and treatment strategies to combat chemo-resistant disease. Our understanding of chemotherapy resistance mechanisms has been hampered by a lack of relapsed human SCLC tissue due to rare surgical resections. In addition, there have been few mouse models of the disease that exhibit short latencies and chemo-sensitivity. To address these challenges, we performed whole exome sequencing on relapsed SCLC from 30 patients. Relapse-specific genomic alterations in the WNT/APC/β-catenin pathway were identified in ~66% of relapsed SCLC suggesting that this pathway promotes chemo-resistance. Second, we developed a novel mouse model of SCLC driven by loss of Rb1, Trp53 and overexpression of Myc—three of the most common genetic alterations in the human disease. Mice develop SCLC within weeks that highly resembles the human disease at the level of histopathology, biomarker expression and chemo-sensitivity followed by relapse. This model will be a useful tool to test candidate chemotherapy resistance mechanisms and identify novel therapeutic targets that inhibit chemo-resistance. The objective of this study is to use this novel mouse model and comprehensive genomic analyses of primary and relapsed human SCLC to identify mechanisms of chemotherapy resistance and novel therapeutic targets to combat chemo-resistant disease. We hypothesize that activation of the WNT/β-catenin pathway promotes chemo-resistance in SCLC and that targeted inhibition of the pathway will inhibit chemo-resistant disease. We predict that expansion of our genomic and transcriptomic profiling will identify additional novel pathways involved in chemo-resistance. To test these hypotheses, we will: 1) identify recurrent pathway alterations in relapsed human and mouse SCLC using whole genome, exome, transcriptome and epigenome sequencing and 2) functionally determine whether canonical WNT/β-catenin signaling and other candidate pathways are necessary and sufficient for chemo-resistance in SCLC in vivo. This approach is innovative because we will employ unbiased comprehensive genomic and epigenomic analyses on relapsed human SCLC and a novel immune-competent mouse model of SCLC that recapitulates key features of the human disease. The WNT/β- catenin pathway is largely unexplored in SCLC. This research is significant because there are currently no targeted therapies approved for SCLC. A better understanding of the critical pathways driving chemo- resistance in SCLC will impact the treatment and survival of patients with this intractable disease.