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Super-enhancer-driven CCAT1 is co-activated by SOX2 and TP63 and promotes squamous cancer from esophagus, head and neck and lung [RNA-seq]

ABSTRACT: Squamous cell carcinomas (SCCs) are aggressive malignancies. Previous report demonstrated that the transcription factors TP63 and SOX2 exhibited overlapping genomic occupancy in SCCs. Our recent study have identified TP63 and SOX2 as super-enhancer-associated genes. However, functional consequences of their frequent co-localization at super-enhancers region remains unexplored. Here, ChIP-seq result indicated TP63 and SOX2 co-occupied peaks are significantly located the super enhancer region compare with unique of TP63 and SOX2 signaling, and combined RNA-seq analyses of different types of SCCs reveal that TP63 and SOX2 cooperatively regulate expression of the super-enhancer-associated the long non-coding RNA (lncRNA) gene, CCAT1. CCAT1 is highly expressed in SCCs compared to either other tumor types or normal tissues. CCAT1 expression strongly correlates with expression levels of TP63 and SOX2. Silencing of CCAT1 significantly reduces cellular growth both in vitro and in vivo, phenotyping the effect of silencing either TP63 or SOX2. Furthermore, ChIP-Seq and luciferase reporter assays demonstrate TP63 and SOX2 co-occupy the promoter and super-enhancer regions of CCAT1. Interaction of CCAT1 with TP63 and SOX2 are validated by RNA immunoprecipitation. In addition, ChIRP analysis suggests that CCAT1 regulates EGFR expression by binding to the super-enhancer of EGFR. Further investigations shows that CCAT1 activates both the MEK/ERK1/2 and PI3K/AKT signaling pathways through up-regulation of EGFR. In conclusion, CCAT1 is driven by master transcription factors TP63 and SOX2 and is recruited to the super-enhancer of EGFR, promoting SCC tumorigenesis through activation of the MEK/ERK1/2 and PI3K/AKT signaling pathways. These studies help to explain the pathogenesis of SCC and aids in providing novel therapeutic strategy.

ORGANISM(S): Homo sapiens

PROVIDER: GSE106564 | GEO | 2018/09/17

REPOSITORIES: GEO

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Project description:Cancer stem cells (CSCs) have been reported in various cancers including skin squamous cell carcinoma (SCC). The molecular mechanisms regulating tumour initiation and stemness are still poorly characterized. Here, we found that Sox2, a transcription factor expressed in various types of embryonic and adult stem cells (SCs), was the most upregulated transcription factor in CSCs of squamous skin tumours. Sox2 is absent in normal epidermis and begins to be expressed in the vast majority of mouse and human pre-neoplastic skin tumours and continues to be expressed in a heterogeneous manner in invasive mouse and human SCCs. In contrast to other SCCs, in which Sox2 is frequently genetically amplified, the expression of Sox2 in mouse and human skin SCCs is transcriptionally regulated. Conditional deletion of Sox2 in the mouse epidermis dramatically decreases skin tumour formation following chemical induced carcinogenesis. Using Sox2-GFP knockin mice, we showed that Sox2 expressing cells in invasive SCC are greatly enriched in tumour propagating cells (TPCs) that further increase upon serial transplantations. Lineage ablation of Sox2 expressing cells within primary benign and malignant SCCs leads to tumour regression, consistent with the critical role of Sox2 expressing cells in tumour maintenance. Conditional Sox2 deletion in pre-existing skin papilloma and SCC leads to their regression and decreases their ability to be propagated upon transplantation into immunodeficient mice, supporting the essential role of Sox2 in regulating CSC functions. Transcriptional profiling of Sox2-GFP expressing CSC and upon Sox2 deletion uncovered a gene network regulated by Sox2 in primary tumour cells in vivo. Chromatin immunoprecipitation identified several direct Sox2 target genes controlling tumour stemness, survival, proliferation, adhesion, invasion, and paraneoplastic syndrome. Altogether, our study demonstrates that Sox2, by marking and regulating the functions of skin tumour initiating cells and CSCs, establishes a continuum between tumour initiation and progression in primary skin tumours. We used microarrays to profile Sox2-GFP expressing CSC to uncover a gene network regulated by Sox2 in primary tumour cells in vivo. Two different biological replicates from SOX2-GFP+ and SOX2-GFP- TECs (control) from 2 different SCC from 2 different mice were analysed. Total RNA was analysed using Mouse whole genome 430 2.0 array from Affymetrix.

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Super-enhancer-driven CCAT1 is co-activated by SOX2 and TP63 and promotes squamous cancer from esophagus, head and neck and lung [RNA-seq]

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