Zhang Te, Song Xuming, Zhang Zeyu, Mao Qixing, Xia Wenjie, Xu Lin, Jiang Feng, Dong Gaochao
Department of Thoracic Surgery, Affiliated Cancer Hospital of Nanjing Medical University, Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Nanjing, 210009, China.
The Fourth Clinical College of Nanjing Medical University, Nanjing, China.
Oncogenesis. 2020 Oct 17;9(10):92. doi: 10.1038/s41389-020-00277-9.
Lung adenocarcinoma (LUAD) relies on dysregulated gene expression to sustain its infinite growth and progression. Emerging evidence indicates that aberrant transcriptional program results from core transcriptional regulatory circuitry (CRC) which is driven by super-enhancers (SEs). In this study, by integrating profiles of H3K27Ac chromatin immunoprecipitation sequencing (ChIP-seq) from normal adult lung and LUAD cell lines, we revealed that widespread alterations of the super-enhancer were presence during lung carcinogenesis. With SE-based modeling of regulatory circuits and assessments of transcription factor (TF) dependencies, we reconstructed an interconnected transcriptional regulation network formed by three master TFs, including ELF3, EHF, and TGIF1, all of which promoted each other's expression that confirmed by ChIP-qPCR and western blot. Loss-of function assay revealed that each of them is essential for LUAD cells survival, invasion and metastasis. Meanwhile, the rescue assay also illustrated the transacting transcriptional regulatory circuitry. In addition, the mRNA levels of ELF3, EHF, and TGIF1 were differentially expressed in LUAD tumors and peritumoral tissue. IHC of serial sections revealed that high expressions of CRC (ELF3/EHF/TGIF1-High) were closely associated with high proliferative activity in tumor tissue and poor prognosis on patients with LUAD. Finally, we used small molecular inhibitors to perturb the transcriptional circuitry, also exhibited a prominent anti-cancer effect in vitro. Our findings reveal the mechanism of the transcriptional dysregulation and addiction of LUAD.
肺腺癌（LUAD）依赖基因表达失调来维持其无限生长和进展。新出现的证据表明，异常转录程序源于由超级增强子（SEs）驱动的核心转录调控回路（CRC）。在本研究中，通过整合正常成人肺组织和LUAD细胞系的H3K27Ac染色质免疫沉淀测序（ChIP-seq）图谱，我们发现在肺癌发生过程中存在超级增强子的广泛改变。通过基于SE的调控回路建模和转录因子（TF）依赖性评估，我们重建了一个由三个主要TF（包括ELF3、EHF和TGIF1）形成的相互连接的转录调控网络，所有这些TF相互促进表达，这通过ChIP-qPCR和蛋白质免疫印迹得到证实。功能丧失实验表明，它们中的每一个对LUAD细胞的存活、侵袭和转移都是必不可少的。同时，拯救实验也说明了反式作用转录调控回路。此外，ELF3、EHF和TGIF1的mRNA水平在LUAD肿瘤和瘤周组织中差异表达。连续切片的免疫组化显示，CRC（ELF3/EHF/TGIF1高表达）的高表达与肿瘤组织中的高增殖活性以及LUAD患者的不良预后密切相关。最后，我们使用小分子抑制剂干扰转录回路，在体外也表现出显著的抗癌作用。我们的研究结果揭示了LUAD转录失调和成瘾的机制。
