Investigating molecular regulators of a mixed-lineage state in lung adenocarcinoma

项目摘要： 肺腺癌(LUAD)是肺癌的最大亚型，也是最常见的致癌原因 相关死亡。LUAD的进展是由基因改变和表观遗传变化的组合推动的， 增加了可塑性和异质性，但决定细胞命运和可塑性的潜在机制 对LUAD的了解仍然很少。有趣的是，定义转录因子NKX2-1和FoxA1/2的谱系， 在LUAD中协调维护肺部身份。在没有NKX2-1的情况下，FoxA1/2可以激活胃 包括HNF4α在内的转录因子可显著改变LUAD的分化状态。近期工作 提示NKX2-1阳性(NKX2-1)LUAD从肺泡样状态演变而来，并采用各种不同的 推动进展的细胞命运，包括以获得胃肠道为特征的“混合血统”状态 (GI)和肺样状态在同一细胞中。这项提案将调查这些胃部状态是如何 以及它们可能如何促进LUAD肿瘤的发生。HNF4α水平在LUAD过程中升高 在人和小鼠NKX2-1LUAD亚群中共表达HNF4α和NKX2-1 肿瘤。这支持一种假定的模型，通过该模型，HNF4α推动土地利用障碍的进展，并促进混合血统 与NKX2-1竞争FoxA1/2结合的状态。此外，鉴于之前的研究结果，MAPK信号 NKX2-1对LUAD进展和肺泡命运很重要，并且已知NKX2-1被磷酸化和 被ERK失活的MEK/ERK信号可能通过破坏NKX2-1/FoxA1/2的稳定而促进混合血统状态 相互作用和有利于HNF4F4α/FoxA1/2结合。我推测HNF4α促进了LUAD肿瘤的发生 和增殖，而MAPK信号通过改变活性和增殖来调节混合血统状态 关键谱系说明者之间的相互作用。为了验证这一假设，我将使用 互补的药理学和遗传学方法，并评估关键混合血统基因的表达， 以及使用邻近连接分析在MAPK操作时可视化蛋白质复合体。另外， 我将进行CHIP-SEQ以确定调节MEK/ERK如何改变NKX2-1和FoxA1/2染色质结合 瞄准胃和肺目标。我还将详述我们小组的初步数据，这些数据表明HNF4α 促进小鼠器官类化合物的肿瘤形成和增殖，以及KRAS驱动的LUAD小鼠模型。这就做 在同时表达NKX2-1和HNF4a的人LUAD细胞系中对HNF4a进行基因调控 增殖分析，并建立细胞系异种移植模型来测量肿瘤的生长。我会综合表演 RNA-SEQ和CHIP-SEQ分析以了解HNF4α介导的生长和进展的关键因素 在NKX2-1LUAD中。这些目标的完成将揭示LUAD通过哪些机制 异质性推动肿瘤的生长和进展，知识将是开发有效、 针对这种疾病的血统定向治疗。这项提案还将探索致癌的创新概念 信号通路和关键转录因子在癌症中协调调节细胞命运。

PROJECT ABSTRACT: Lung adenocarcinoma (LUAD) is the largest subtype of lung cancer and is the most common cause of cancer related death. LUAD progression is driven by a combination of genetic alterations and epigenetic changes that confer increased plasticity and heterogeneity, but underlying mechanisms dictating cell fate and plasticity in LUAD remain poorly understood. Interestingly, the lineage defining transcription factors, NKX2-1 and FoxA1/2, coordinately maintain a pulmonary identity in LUAD. In the absence of NKX2-1, FoxA1/2 can activate gastric transcription factors including HNF4α to substantially alter the differentiation state of LUAD. Recent work suggests that NKX2-1-positive (NKX2-1+) LUAD evolves from an alveolar-like state and adopts various disparate cell fates that drive progression, including “mixed lineage” states, characterized by acquisition of gastrointestinal (GI) and pulmonary-like states in the same cell. This proposal will investigate how these gastric states are maintained and how they may promote LUAD tumorigenesis. HNF4α levels increase over the course of LUAD progression, and HNF4α and NKX2-1 are co-expressed in a subset of human and mouse NKX2-1+ LUAD tumors. This supports a putative model by which HNF4α drives LUAD progression and promotes a mixed-lineage state by competing with NKX2-1 for FoxA1/2 binding. Additionally, given previous findings that MAPK signaling is important for LUAD progression and alveolar fate, and that NKX2-1 is known to be phosphorylated and inactivated by ERK, MEK/ERK signaling may promote mixed-lineage states by destabilizing NKX2-1/FoxA1/2 interactions and favoring HNF4α/FoxA1/2 binding. I hypothesize that HNF4α promotes LUAD tumorigenesis and proliferation, and that MAPK signaling modulates the mixed-lineage state by altering the activity and interactions of key lineage specifiers. To test this hypothesis, I will modulate MAPK signaling using complementary pharmacological and genetic approaches and assess expression of key mixed lineage genes, as well as visualizing protein complexes upon MAPK manipulation using a Proximity Ligation Assay. Additionally, I will perform ChIP-seq to determine how modulating MEK/ERK alters NKX2-1 and FoxA1/2 chromatin binding at gastric and pulmonary targets. I will also expand on preliminary data from our group demonstrating that HNF4α drives tumorigenesis and proliferation in murine organoids as well as a KRAS-driven LUAD mouse model. I will genetically modulate HNF4A in human LUAD cell lines expressing both NKX2-1 and HNF4A, perform proliferation assays, and create cell line xenograft models to measure tumor growth. I will perform integrative RNA-seq and ChIP-seq analysis to understand key factors underlying HNF4α-mediated growth and progression in NKX2-1+ LUAD. Completion of these aims will unveil key insights into the mechanisms by which LUAD heterogeneity drives tumor growth and progression, knowledge which will be critical for development of effective, lineage-targeted therapies for this disease. This proposal will also explore the innovative notion that oncogenic signaling pathways and key transcription factors coordinately regulate cellular fate in cancer.