RESUMO
Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and is linked to tobacco exposure, alcohol consumption, and human papillomavirus infection. Despite therapeutic advances, a lack of molecular understanding of disease etiology, and delayed diagnoses continue to negatively affect survival. The identification of oncogenic drivers and prognostic biomarkers by leveraging bulk and single-cell RNA-sequencing datasets of OSCC can lead to more targeted therapies and improved patient outcomes. However, the generation, analysis, and continued utilization of additional genetic and genomic tools are warranted. Tobacco-induced OSCC can be modeled in mice via 4-nitroquinoline 1-oxide (4NQO), which generates a spectrum of neoplastic lesions mimicking human OSCC and upregulates the oncogenic master transcription factor p63. Here, we molecularly characterized established mouse 4NQO treatment-derived OSCC cell lines and utilized RNA and chromatin immunoprecipitation-sequencing to uncover the global p63 gene regulatory and signaling network. We integrated our p63 datasets with published bulk and single-cell RNA-sequencing of mouse 4NQO-treated tongue and esophageal tumors, respectively, to generate a p63-driven gene signature that sheds new light on the role of p63 in murine OSCC. Our analyses reveal known and novel players, such as COTL1, that are regulated by p63 and influence various oncogenic processes, including metastasis. The identification of new sets of potential biomarkers and pathways, some of which are functionally conserved in human OSCC and can prognosticate patient survival, offers new avenues for future mechanistic studies.
RESUMO
Head and Neck Squamous Cell Carcinoma (HNSCC) is a heterogeneous disease with relatively high morbidity and mortality rates. The lack of effective therapies, high recurrence rates and drug resistance driven in part, by tumor heterogeneity, contribute to the poor prognosis for patients diagnosed with this cancer. This problem is further exacerbated by the fact that key regulatory factors contributing to the disease diversity remains largely elusive. Here, we have identified EHF as an important member of the ETS family of transcription factors that is highly expressed in normal oral tissues, but lost during HNSCC progression. Interestingly, HNSCC tumors and cell lines exhibited a dichotomy of high and low EHF expression, and patients whose tumors retained EHF expression showed significantly better prognosis, suggesting a potential tumor suppressive role for EHF. To address this, we have performed gain and loss of function studies and leveraged bulk and single-cell cancer genomic datasets to identify global EHF targets by RNA-sequencing (RNA-seq) and Chromatin Immunoprecipitation and next generation sequencing (ChIP-seq) experiments of HNSCC cell lines. These mechanistic studies have revealed that EHF, acts as a regulator of a broad spectrum of metabolic processes, specifically targeting regulators of redox homeostasis such as NRF2 and SOX2. Our immunostaining results confirm the mutually exclusive expression patterns of EHF and SOX2 in HNSCC tumors and suggest a possible role for these two factors in establishing discrete metabolic states within the tumor microenvironment. Taken together, EHF may serve as a novel prognostic marker for classifying HNSCC patients for actionable and targeted therapeutic intervention.
RESUMO
The complex heterogeneity of head and neck squamous cell carcinoma (HNSCC) reflects a diverse underlying etiology. This heterogeneity is also apparent within Human Papillomavirus-positive (HPV+) HNSCC subtypes, which have distinct gene expression profiles and patient outcomes. One aggressive HPV+ HNSCC subtype is characterized by elevated expression of genes involved in keratinization, a process regulated by the oncogenic transcription factor ΔNp63. Furthermore, the human TP63 gene locus is a frequent HPV integration site and HPV oncoproteins drive ΔNp63 expression, suggesting an unexplored functional link between ΔNp63 and HPV+ HNSCC. Here we show that HPV+ HNSCCs can be molecularly stratified according to ΔNp63 expression levels and derive a ΔNp63-associated gene signature profile for such tumors. We leveraged RNA-seq data from p63 knockdown cells and ChIP-seq data for p63 and histone marks from two ΔNp63high HPV+ HNSCC cell lines to identify an epigenetically refined ΔNp63 cistrome. Our integrated analyses reveal crucial ΔNp63-bound super-enhancers likely to mediate HPV+ HNSCC subtype-specific gene expression that is anchored, in part, by the PI3K-mTOR pathway. These findings implicate ΔNp63 as a key regulator of essential oncogenic pathways in a subtype of HPV+ HNSCC that can be exploited as a biomarker for patient stratification and treatment choices.
