Identifying the Genes that Function to Fuel RAS Driven SCCs

About This Grant

Project Summary Genetic mutations are crucial in driving cancer initiation and progression. However, while cancer is widely recognized as a genetic disease, not all cells with a high mutational burden become malignant. Conversely, some cells with a very low mutational burden can develop into cancer. This discrepancy underscores the importance of context and the tumor microenvironment in the process of tumorigenesis. Cutaneous squamous cell carcinoma (cSCC) typically arises in the stratified epithelium of the esophagus, head and neck, lungs, and skin through mutations in RAS. Previous studies in the lab have identified a population of cSCC cells, called cancer stem cells (CSCs), that are located at the tumor-stroma interface, rich in TGFβ, tumor-associated macrophages and blood vessels. My preliminary data, from a study in which I was a co-author, shows that upon oncogenic HRAS induction, normal stem cells undergo aberrant crosstalk with their neighbors that leads to a benign state with a few CSCs that then drive cSCC progression. cSCC-CSCs develop a unique gene signature that promotes malignant invasion and therapeutic resistance. I hypothesize that this signature enables cSCC-CSCs to establish the pro-tumorigenic environment for the tumor to survive and grow in. To address this concern, I plan to (Aim 1A) identify what in vivo cSCC-CSC signature genes persist when the cells are cultured under normal skin SC growth conditions and how this differs when in a more SCC- like environment (+serum and TGFβ); (Aim 1B and 1C) perform in vitro and in vivo CRISPR screens to identify which of the CSC signature genes are essential for survival independently of the niche, which depend upon prominent secreted niche factors and which are necessary only within the context of cellular/other components of the niche. With emphasis on niche-specific candidate genes, I will use rapid lentiviral genetics and multiplex immunofluorescence imaging to assess how the loss of key candidates alters the CSC niche (TME) and the mechanism these genes play in driving cancer (Aim 2). If successful, my work will represent a major advancement in our understanding of tumor progression and potentially lead to the development of new therapeutic targets.