Head and neck squamous carcinoma (HNSCC) is known for its high aggressiveness and susceptibility to cervical lymph node metastasis, which greatly contributes to its poor prognosis. During tumorigenesis, many types of cancer cells acquire oncogenic super-enhancers (SEs) that drive the overexpression of oncogenes, thereby maintaining malignant progression. This study aimed to identify and validate the role of oncogenic SE-associated genes in the malignant progression of HNSCC. We identified HNSCC cell-specific SE-associated genes through H3K27Ac ChIP-seq and overlapped them with HNSCC-associated genes obtained from The Cancer Genome Atlas (TCGA) dataset and Gene Expression Omnibus (GEO) datasets using weighted gene coexpression network analysis (WGCNA) to identify hub genes. The expression of IGF2BP2 and KLF7 in HNSCC was detected using clinical samples. To determine the biological role of IGF2BP2, we performed CCK-8, colony formation assay, Transwell migration assay, invasion assay, and orthotopic xenograft model experiments. Furthermore, we utilized a CRISPR/Cas9 gene-editing system, small-molecule inhibitors, ChIP-qPCR, and dual-luciferase reporter assays to investigate the molecular mechanisms of IGF2BP2 and its upstream transcription factors. Our study identified IGF2BP2 as a hub SE-associated gene that exhibited aberrant expression in HNSCC tissues. Increased expression of IGF2BP2 was observed to be linked with malignant progression and unfavorable prognosis in HNSCC patients. Both in vitro and in vivo experiments confirmed that IGF2BP2 promotes the tumorigenicity and metastasis of HNSCC by promoting cell proliferation, migration, and invasion. Mechanistically, the IGF2BP2-SE region displayed enrichment for H3K27Ac, BRD4, and MED1, which led to the inhibition of IGF2BP2 transcription and expression through deactivation of the SE-associated transcriptional program. Additionally, KLF7 was found to induce the transcription of IGF2BP2 and directly bind to its promoter and SE regions. Moreover, the abundance of KLF7 exhibited a positive correlation with the abundance of IGF2BP2 in HNSCC. Patients with high expression of both KLF7 and IGF2BP2 showed poorer prognosis. Lastly, we demonstrated that the small molecule inhibitor JQ1, targeting BRD4, attenuated the proliferation and metastatic abilities of HNSCC cells. Our study reveals the critical role of IGF2BP2 overexpression mediated by SE and KLF7 in promoting HNSCC progression. Targeting SE-associated transcriptional programs may represent a potential therapeutic strategy in managing HNSCC.

中文翻译：

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KLF7调节超级增强子驱动的IGF2BP2过表达促进头颈鳞状细胞癌的进展

头颈鳞状细胞癌（HNSCC）以其高侵袭性和易发生颈部淋巴结转移而闻名，这在很大程度上导致了其预后不良。在肿瘤发生过程中，许多类型的癌细胞获得致癌超级增强子（SE），驱动癌基因过度表达，从而维持恶性进展。本研究旨在鉴定和验证致癌 SE 相关基因在 HNSCC 恶性进展中的作用。我们通过 H3K27Ac ChIP-seq 鉴定了 HNSCC 细胞特异性 SE 相关基因，并使用加权基因共表达网络分析 (WGCNA) 将其与从癌症基因组图谱 (TCGA) 数据集和基因表达综合 (GEO) 数据集中获得的 HNSCC 相关基因重叠识别枢纽基因。利用临床样本检测 HNSCC 中 IGF2BP2 和 KLF7 的表达。为了确定 IGF2BP2 的生物学作用，我们进行了 CCK-8、集落形成实验、Transwell 迁移实验、侵袭实验和原位异种移植模型实验。此外，我们利用CRISPR/Cas9基因编辑系统、小分子抑制剂、ChIP-qPCR和双荧光素酶报告基因检测来研究IGF2BP2及其上游转录因子的分子机制。我们的研究发现 IGF2BP2 是一个中心 SE 相关基因，在 HNSCC 组织中表现出异常表达。研究发现 IGF2BP2 表达增加与 HNSCC 患者的恶性进展和不良预后有关。体外和体内实验均证实IGF2BP2通过促进细胞增殖、迁移和侵袭而促进HNSCC的致瘤和转移。从机制上讲，IGF2BP2-SE 区域表现出 H3K27Ac、BRD4 和 MED1 的富集，从而通过 SE 相关转录程序的失活来抑制 IGF2BP2 转录和表达。此外，KLF7 被发现可诱导 IGF2BP2 转录并直接与其启动子和 SE 区域结合。此外，HNSCC 中 KLF7 的丰度与 IGF2BP2 的丰度呈正相关。KLF7和IGF2BP2同时高表达的患者预后较差。最后，我们证明了针对 BRD4 的小分子抑制剂 JQ1 可以减弱 HNSCC 细胞的增殖和转移能力。我们的研究揭示了 SE 和 KLF7 介导的 IGF2BP2 过表达在促进 HNSCC 进展中的关键作用。针对 SE 相关转录程序可能是治疗 HNSCC 的一种潜在治疗策略。