Defining the β-catenin/CBP-catenin/CBP axis in head and neck cancer

头颈部鳞状细胞癌（HNSCC）是一种严重的恶性肿瘤， 发病率高、死亡率高和治疗选择有限。HNSCC的主要亚部位是口腔， 这种疾病主要表现为烟草和酒精相关的HPV（-）口腔鳞状细胞癌（OSCC）。 尽管对口腔鳞状细胞癌基因组改变的理解取得了很大进展，但其背后的分子细节仍然是未知的。 非侵入性口腔病变进展到具有淋巴结转移的晚期疾病仍然很差 明白为了深入了解OSCC进展为转移的机制，我们 研究了细胞核β-catenin与cAMP反应元件结合蛋白（CREB）的相互作用 (CBP)在口腔鳞状细胞癌中， 表观遗传、分子、生物化学和功能分析。我们发表的和初步的研究表明， 小分子拮抗剂ICG-001和E7386对一组口腔鳞癌中β-catenin/CBP活性抑制作用 细胞系抑制细胞增殖和间充质表型，同时诱导细胞分化。同样地， 抑制人口腔鳞状细胞癌细胞系来源的裸鼠肿瘤异种移植物中β-catenin/CBP信号传导抑制了 肿瘤生长和转移，并消除由OSCC干细胞样细胞亚群驱动的快速转移 细胞或癌症干细胞（CSC）。我们最近的全球染色质免疫沉淀 随后的测序（ChIPseq）研究表明，β-catenin/CBP与组蛋白 甲基转移酶，MLL 1，以促进在转录起始位点（TSS）的整体H3 K4三甲基化（H3 K4 me 3）， 许多CSC基因。这一发现得到了我们最近基于RNAseq和 scRNAseq数据显示β-连环蛋白/CBP活性与侵袭性细胞状态相关，包括CSC。 初步分析还表明，β-连环蛋白/CBP复合物包括Hippo途径效应物雅普和 TAZ（雅普/TAZ）与β-连环蛋白一样，与化疗和西妥昔单抗耐药相关， HNSCC（19，20）。我们使用特征良好的OSCC细胞系，整合了相关的基因表达特征， 从癌症基因组图谱（TCGA）的OSCC数据中，β-连环蛋白/CBP轴的抑制显示 β-catenin/CBP活性与疾病进展和患者生存率降低相关。根据这些 我们假设β-catenin/CBP信号的异常激活是扩张的基础， CSCs在HNSCC进展为转移性疾病过程中的作用，其拮抗作用可抑制晚期疾病。 这一假设将在两个目标中进行检验：1）确定β-连环蛋白/CBP轴在HNSCC中的作用 进展为晚期疾病; 2）确定β-连环蛋白/CBP活性的分子机制 在诱导CSC表型方面。我们的研究将产生一个动态整合的地图对齐β-连环蛋白-CBP- 活性与不同的侵略性细胞状态及其相关的基因签名，信号网络和蛋白质 组装，并提供了一个合理的发展新的治疗策略，以打击这种恶性肿瘤。

Head and neck squamous cell carcinoma (HNSCC) is a devastating malignancy associated with severe morbidity, high mortality and limited treatment options. The main subsite of HNSCC is the oral cavity, where the disease presents primarily as tobacco- and alcohol-associated HPV(-) oral squamous cell carcinoma (OSCC). Despite great progress in the understanding of genomic alterations in OSCC, the molecular details underlying the progression of non-invasive oral lesions to advanced disease with lymph node metastasis remain poorly understood. To gain insights into the mechanisms that contribute to OSCC progression to metastasis we have studied the interaction between nuclear β-catenin and cAMP-response element-binding (CREB)-binding protein (CBP) in OSCC by applying our newly developed computational methodologies coupled with genomic, epigenetic, molecular, biochemical and functional analyses. Our published and preliminary studies show that inhibition of β-catenin/CBP activity with small molecule antagonists, ICG-001 and E7386, in a panel of OSCC cell lines inhibits cell proliferation and mesenchymal phenotype while inducing cellular differentiation. Similarly, inhibition of β-catenin/CBP signaling in human OSCC cell line-derived tumor xenografts in nude mice inhibits tumor growth and metastasis and abrogates rapid metastases driven by subpopulations of OSCC stem cell-like cells, or cancer stem cells (CSCs), in embryonic zebrafish. Our recent global chromatin immunoprecipitation followed by sequencing (ChIPseq) studies show that β-catenin/CBP collaborates with the histone methyltransferase, MLL1, to promote global H3K4 trimethylation (H3K4me3) at transcription start sites (TSS) of numerous CSC genes. This finding is supported by our recent genomic analyses based on RNAseq and scRNAseq data showing that β-catenin/CBP activity is associated with aggressive cell states, including CSCs. Preliminary analyses also suggest that β-catenin/CBP complexes include the Hippo pathway effectors YAP and TAZ (YAP/TAZ), which, like β-catenin, are associated with resistance to both chemotherapy and cetuximab in HNSCC (19,20). Using well characterized OSCC cell lines, we integrated gene expression signatures associated with the inhibition of the β-catenin/CBP axis with OSCC data from The Cancer Genome Atlas (TCGA) to show that β-catenin/CBP activity is associated with progressive disease and reduced patient survival. Building on these collective findings we hypothesize that aberrant activation of β-catenin/CBP signaling underlies the expansion CSCs during HNSCC progression to metastatic disease and that its antagonism may inhibit advanced disease. This hypothesis will be tested in two aims that will: 1) define the role of the β-catenin/CBP axis in HNSCC progression to advanced disease; and 2) determine the molecular mechanisms underlying β-catenin/CBP activity in the induction of CSC phenotypes. Our studies will generate a dynamic integrated map aligning β-catenin-CBP- activity with distinct aggressive cell states and their associated in gene signatures, signaling networks and protein assemblies and provide a rationale for the development of new treatment strategies to combat this malignancy.