Master regulator transcription factors promote esophageal neoplastic evolution

项目总结 食管腺癌(EAC)是死亡率最高的恶性肿瘤之一，其发病率显著增加。 在西方国家(包括美国、英国和一些欧洲国家)增长了6-8倍 在过去的40年里。尽管最近的基因组分析获得了新的见解，但有意义的治疗 没有改善，EAC的5年存活率仍然非常低(~20%)。因此， 另一种研究方法，包括高级表观基因组学研究，迫切需要理解 EAC用于开发新的治疗方案的分子基础。巴雷特食道(BE)为癌前病变 并被认为是EAC的专有前驱病变。在巴雷特食道相关的过程中 肿瘤演变过程中，良性BE首先演变为发育不良，然后进展为EAC。因此，BE作为 一种理想的研究食道上皮逐步癌变的癌前模型 细胞。然而，我们对促进菜豆生长的分子机制的了解仍然有限，关键是 问题(例如，BE向EAC恶变的主要驱动因素)仍未解决。 我们和其他人已经证明，恶性转化伴随着全基因组的得失 增强剂和超级增强剂，由上游主监管者占据和监管 转录因子(MRTF)。事实上，我们最近的研究表明，这两个增强子都发生了深刻的变化 正常胃食道连接部(NGEJ)、BE和EAC标本的使用率和MRTF活性。尤其是， 我们已经确定了一组EAC特异的MRTF(ELF3、KLF5、GATA6、EHF)。初步实验表明， 这4个MRTF共同占据了数百个EAC特异性增强子和超级增强子，这表明它们可能 调节EAC转录组。此外，这些EAC特有的MRTF在 EAC与正常的GEJ或BE样本相比，在功能上是EAC细胞增殖所必需的。 基于这些发现，我们假设EAC特异性MRTF直接促进肿瘤的发生。 通过在表观基因组中重新连接增强子和超级增强子来转化BE细胞，激活 EAC发育所必需的信号通路和细胞过程。我们将通过以下方式验证这一假设 研究人BE来源的3D有机体内MRTF的生物学功能。此外，我们还将研究 肥胖与EAC之间强关联的机制基础--关注 MRTF和脂肪酸合成，这是我们初步数据确定的关键下游途径。这些 研究有望建立BE相关肿瘤演变的主要驱动力并揭示 食道转化的表观组学机制，这将从根本上改变我们的见解 关于食道癌的生物学。更重要的是，该提案的成功执行可能会确定 靶向脂肪酸合成途径预防和早期干预EAC的潜在途径 肥胖的高危个体(例如，顽固性和/或高度BE患者)。

PROJECT SUMMARY Esophageal adenocarcinoma (EAC) is one of the deadliest malignancies, and its incidence has strikingly increased 6-8 fold in Western countries (including the United States, UK and several European countries) over the past 4 decades. Despite new insights gained from recent genomic analyses, meaningful therapeutic improvements have not occurred and the 5-year survival of EAC has remained extremely low (~20%). Therefore, alternative research approaches, including advanced epigenomic studies, are desperately needed to understand the molecular basis of EAC for developing novel treatment regimens. Barrett’s esophagus (BE) is a premalignant condition and is considered as the obligate precursor lesion of EAC. During Barrett’s esophagus-associated neoplastic evolution, benign BE first becomes dysplastic and then progresses to EAC. Therefore, BE serves as an ideal pre-malignant model for the investigation of the step-wise neoplastic evolution of esophageal epithelial cells. However, our understanding of the molecular mechanisms promoting BEAN remains limited, with key questions (e.g., the primary drivers for the malignant transformation of BE into EAC) still unaddressed. We and others have shown that malignant transformation is accompanied by genome-wide gains and losses of enhancers and super-enhancers, which are occupied and regulated by upstream master regulator transcription factors (MRTFs). Indeed, our recent studies demonstrated profound alterations in both enhancer usage and MRTF activity between normal gastroesophageal junction (NGEJ), BE and EAC samples. Particularly, we have identified a set of EAC-specific MRTFs (ELF3, KLF5, GATA6, EHF). Pilot experiments have shown that these 4 MRTFs co-occupy hundreds of EAC-specific enhancers and super-enhancers, indicating they may regulate the EAC transcriptome. Moreover, these EAC-specific MRTFs are highly and uniquely expressed in EAC compared with normal GEJ or BE samples and are functionally required for EAC cell proliferation. Based on these findings, we hypothesize that EAC-specific MRTFs directly promote the malignant transformation of BE cells by rewiring enhancers and super-enhancers across the epigenome, activating signaling pathways and cellular processes essential for EAC development. We will test this hypothesis by investigating the biological functions of MRTFs in human BE-derived 3D organoids. In addition, we will study the mechanistic basis of the strong association between obesity and EAC by focusing on the regulatory loop of MRTF and fatty-acid synthesis, which is the key downstream pathway identified by our preliminary data. These investigations promise to establish primary driving forces of BE-associated neoplasia evolution and uncover epigenomic mechanisms underlying esophagus transformation, which will fundamentally transform our insights into the biology of esophageal cancer. More importantly, successful execution of this proposal may identify potential avenue for the prevention and early intervention of EAC by targeting fatty-acid synthesis pathway in the high-risk individuals (e.g., refractory and/or high-grade BE patients) with obese condition.