Multi-omic investigation of the mechanisms underlying the pathobiology of head and neck squamous cell carcinomas
Kartha, Vinay K.
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Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy associated with molecular heterogeneity, locoregional spread, resistance to therapy and relapse after initial treatment. Increasing evidence suggests that master developmental pathways with key roles in adult tissue homeostasis, including Hippo and Wnt/β-catenin signaling, are dysregulated in the initiation and progression of HNSCC. However, a comprehensive investigation into the crosstalk between these pathways is currently lacking, and may prove crucial to the discovery of novel targets for HNSCC therapy. More recent evidence points to the tumor microenvironment, mainly comprising cancer-associated fibroblasts (CAFs), as capable of influencing tumor cell behavior and promoting invasive HNSCC phenotypes. Nonetheless, current methods to screen for CAF markers in tumors are restricted to targeted immunostaining experiments with limited success and robustness across tissue types. The Cancer Genome Atlas network has generated multi-tiered molecular profiles for over 10,000 tumors spanning more than two dozen different cancer types, providing an unprecedented opportunity for the application and development of integrative methods aimed at the in silico interrogation of experimentally-derived signatures. These multi-omic profiles further enable one to link genomic anomalies, including somatic mutations and DNA copy number alterations, with phenotypic effects driven by pathogenic pathway activity. Effectively querying this vast amount of information to help elucidate subsets of functionally and clinically-relevant oncogenic drivers, however, remains an ongoing challenge. To address these issues, I first investigate the effects of oncogenic pathway perturbation in HNSCC using experimental models coupled with in vitro genome-wide transcriptional profiling. Next, I describe a new computational approach for the unbiased identification of CAF markers in HNSCC solely using bulk tumor RNA-sequencing information. Lastly, I have developed Candidate Driver Analysis or CaDrA - a statistical framework that allows one to query genetic and epigenetic alterations for candidate drivers of signature activity within a given disease context. Collectively, this work offers new perspectives on the molecular cues underlying HNSCC development, while simultaneously highlighting the power of integrative genomics methods capable of accelerating the discovery of novel targets for cancer diagnosis and therapy.