Fellowship (Fellow, Jennifer Sosa): Single-cell profiling of Follistatin within the Tumor Landscape of Oral Squamous Cell Carcinoma

PROJECT SUMMARY Oral Squamous Cell Carcinomas (OSCC) are a heterogeneous group of cancers that arise from squamous epithelial cells lining the oral mucosa. Patient prognosis remains relatively poor for OSCC, highlighting the need for identification of new biomarkers for early diagnosis and novel targets for therapeutic intervention. To this end, our integrated molecular and bioinformatics-based analysis has identified follistatin (FST) as a potential driver of OSCC. FST is a secreted glycoprotein with potent neutralizing effects on the Transforming Growth Factor ß (TGF-ß) superfamily and is upregulated in oral cancer cells and tumors. Although the function of TGF-ß in cancer is well documented, the role of FST in OSCC is poorly understood. To address this gap in knowledge, we have performed gene knockdown or overexpression of FST human OSCC cell lines. Our functional studies revealed that FST promotes proliferation and migration in OSCC cells, suggesting that FST may inhibit TGF-ß to promote tumor aggression. Moreover, transcriptomic studies revealed FST regulates key oncogenic pathways important for cell migration, growth, and invasion. Interrogation of single cell RNA-sequencing datasets of OSCC revealed that a) expression of FST increases during tumor progression, and b) cancer cells and fibroblasts are the main sources of FST in OSCC. Furthermore, we found that FST is associated with increased communication between fibroblasts and cancer cells, impinging upon extracellular matrix remodeling and potential recruitment of fibroblasts by cancer cells to facilitate metastasis. Based on these preliminary findings, the broad hypothesis of this project is that FST reprograms the tumor microenvironment to promote tumor growth and metastasis in OSCC. However, it is not known whether the expression of FST by cancer cells is a direct and primary mediator of these tumor aggressive features. The goal of this project is hence to define the conserved molecular role of FST in OSCC in two Specific Aims. Aim 1 will determine the effects of loss of FST expression by cancer cells on tumor growth and metastasis using epithelial-specific conditional FST knock-out animals subjected to oral chemical carcinogenesis with 4-nitroquinoline 1-oxide (4NQO). Aim 2 will focus on single cell RNA sequencing-based studies to determine how FST modulates the tumor microenvironment of mouse tumors and parallel in vitro studies and immunostaining of human patient OSCC. This project will deepen our understanding of how cancer cells reprogram their environment to promote tumor aggression and provide mechanistic insights into the role of FST in cancer progression that can be leveraged for OSCC therapies. The University at Buffalo's rich scientific environment and the collaborative atmosphere within the sponsor's laboratory will provide the physical and intellectual resources for training in multidisciplinary approaches to further our understanding of the molecular programs driving OSCC and foster the development of essential skills in scientific writing, presentations, leadership, and career advancement.