Basal cell carcinoma (BCC) is the most commonly occurring cancer in humans, and is particularly prevalent in the Veteran population. BCC is driven by DNA damage to the interfollicular epidermis, the body’s outermost protective barrier. Preliminary studies demonstrate that DNA damage activates inflammasome signaling in dermal fibroblasts, which enhances epithelial cell proliferation and plasticity in wild-type interfollicular epidermis, characteristics that are associated with tumorigenesis. Strikingly, however, the role of dermal fibroblasts in cutaneous skin cancer development has not been adequately addressed. Cancer-associated fibroblasts (CAFs) are predominant in tumor stroma, and have been proposed to drive the progression of many epithelial cancers, including BCC. However, the direct role of CAFs in cutaneous skin cancer progression is currently unknown. The primary goal of this CDA-2 research proposal is to test the hypothesis that inflammasome signaling from dermal CAFs promotes BCC development. This research will be the first to deeply characterize 1) epidermal and dermal live cell dynamics during BCC formation, 2) the role of CAFs in BCC development, 3) CAF necessity and sufficiency for skin cancer progression, 4) CAF signaling changes during skin tumorigenesis, and 5) the impact of specific CAF signaling subpopulations on skin cancer cell behaviors. Transgenic mouse models, live intravital imaging, patient-derived xenografts, 3D organotypic co- culture, as well as single cell analyses of primary skin cancer tissue from Veteran patients will be employed to investigate these research aims. In addition, this work will take place in a highly collaborative, supportive and rigorous research environment, and will be accompanied by both technical training and formal coursework in cancer mouse models, ex vivo organoids, CRISPR/Cas9 technology, mass cytometry, and single cell RNA sequencing. The data generated in the CDA-2 training phase, coupled with the extensive technical expertise and career development skills that will be attained, will provide a strong foundation for the long-term goals of securing VA MERIT award funding and establishing a successful independent research program at a VA- affiliated institution. The broad objective of the proposed research is to significantly improve Veteran healthcare by informing the development of targeted therapies to effectively treat and prevent cutaneous skin cancer. Additionally, this research may provide important insights into therapeutic approaches for treating other epithelial cancers as well as inflammatory skin disorders that are also common among Veterans.