Epigenetic regulation of NKX2-1-negative lung adenocarcinoma cellular identity by FoxA1 and FoxA2

项目摘要 肺癌是男性和女性癌症死亡的主要原因。尽管在筛查方面取得了进展 方法和个性化治疗，患者预后仍然令人沮丧，5年生存率从4- 百分之十七肺腺癌（LUAD）是这种疾病最常见的诊断亚型， 其细胞特性或组织分化状态的异质性。细胞特性的变化已经显示出 与临床参数（包括患者预后、对化疗的敏感性）密切相关， 耐药性的发展。目前，该领域缺乏对分子生物学的全面了解。 调节肺腺癌细胞身份和控制肿瘤进展的网络。识别 主转录调节因子将提供新的见解癌症的进展机制，奠定了基础。 为肿瘤分化状态特异性治疗策略的发展奠定基础。 侵袭性粘液腺癌（IMA）是LUAD的一个亚型，它经历了肺到胃的谱系 在其自然发展过程中转换。使用基因工程小鼠模型，我们发现， 肺谱系特异性因子NKX 2 -1/TTF 1的表达在LUAD中引起胃转分化，产生小鼠 肿瘤的形态学和基因表达谱的人IMA重演。这种胃谱系转换 部分由先锋因子FoxA 1和FoxA 2（FoxA 1/2）的差异染色质结合介导， 在整个基因组中从肺基因座重新定位到胃基因的调节元件。在NKX 2 -1损失后， 这些胃基因也经历与基因活化相关的染色质修饰， 组蛋白3赖氨酸27乙酰化（H3 K27 ac）。然而，不知道FoxA 1/2是否需要 在它们的从头结合位点介导这些染色质改变，从而促进肿瘤谱系 切换FoxA 1/2除了调节肺-胃转分化外，还调节LUAD 对靶向治疗的反应。丝裂原活化蛋白激酶的药理学抑制 信号级联反应不仅导致NKX 2 -1阴性LUAD中的肿瘤消退，而且还导致胃内肿瘤消退。 谱系开关依赖于FoxA 1/2活性。因此，本提案的目的是确定 FoxA 1/2调节NKX 2 -1阴性LUAD的染色质景观以控制 癌症的身份核心假设是FoxA 1/2重组染色质可及性并修饰组蛋白/ DNA甲基化景观，以控制LUAD身份。为了验证这一假设，我们将确定 FoxA 1/2是在已建立的肿瘤中Nkx 2 -1缺失后染色质调节所必需的，并定义了 FoxA 1/2介导这些变化的精确机制。这一建议意义重大，因为它将提供 更深入地了解调节LUAD细胞身份和肿瘤进展的分子网络， 这些发现对于发展亚型特异性干预措施至关重要。

PROJECT ABSTRACT Lung cancer is the leading cause of cancer mortality in both men and women. Despite advances in screening methods and personalized therapy, patient prognosis remains dismal with 5-year survival rates varying from 4- 17%. Lung adenocarcinoma (LUAD), the most frequently diagnosed subtype of this disease, exhibits substantial heterogeneity in its cellular identity or tissue differentiation state. Changes in cellular identity have been shown to strongly correlate with clinical parameters including patient prognosis, sensitivity to chemotherapy, and development of drug resistance. Currently, the field lacks a comprehensive understanding of the molecular networks that regulate lung adenocarcinoma cell identity and govern tumor progression. Identifying master transcriptional regulators will provide novel insight into the mechanisms of cancer progression and lay the groundwork for the development of therapeutic strategies specific to tumor differentiation state. Invasive mucinous adenocarcinoma (IMA) is a subtype of LUAD that undergoes pulmonary to gastric lineage switching during its natural progression. Using genetically engineered mouse models, we have found that loss of the pulmonary lineage specifier NKX2-1/TTF1 causes gastric transdifferentiation in LUAD, generating murine tumors that recapitulate the morphology and gene expression profile of human IMA. This gastric lineage switch is mediated in part by differential chromatin binding of pioneer factors, FoxA1 and FoxA2 (FoxA1/2), which relocate throughout the genome from pulmonary loci to regulatory elements of gastric genes. Upon NKX2-1 loss, these gastric genes also undergo chromatin modifications associated with gene activation including increases in histone 3 lysine 27 acetylation (H3K27ac). However, it is unknown whether FoxA1/2 are required to mediate these chromatin alterations at their de novo binding sites and thereby, facilitate tumor lineage switching. In addition to regulating the pulmonary-to-gastric transdifferentiation, FoxA1/2 also modulate LUAD identity in response to targeted therapy. Pharmacologic inhibition of the mitogen-activated protein kinase signaling cascade not only causes tumor regression in NKX2-1-negative LUAD, but also results in a gastric lineage switch that is dependent upon FoxA1/2 activity. Thus, the objective of this proposal is to determine the mechanism by which FoxA1/2 modulate the chromatin landscape of NKX2-1-negative LUAD in order to control cancer identity. The central hypothesis is that FoxA1/2 restructure chromatin accessibility and modify the histone/ DNA methylation landscape in order to control LUAD identity. To test this hypothesis, we will determine whether FoxA1/2 are required for chromatin modulation following Nkx2-1 deletion in established tumors and define the precise mechanism by which FoxA1/2 mediate these changes. This proposal is significant because it will provide a deeper understanding of the molecular networks that regulate LUAD cellular identity and tumor progression, findings which are essential for the development of subtype-specific interventions.