Expression of the intermediate filament protein keratin 17 (K17) is robustly upregulated in inflammatory skin diseases and in many tumors originating in stratified and pseudostratified epithelia1-3. We report that Autoimmune regulator (Aire), a transcriptional regulator, is inducibly expressed in human and mouse tumor keratinocytes in a K17-dependent manner and required for a timely onset of Gli2-induced skin tumorigenesis in mice. Induction of Aire mRNA in keratinocytes depends upon a functional interaction between K17 and the heterogeneous nuclear ribonucleoprotein hnRNP K4. Further, K17 colocalizes with Aire protein in the nucleus of tumor-prone keratinocytes, and each are bound to a specific promoter region featuring a NF-κB consensus sequence in a relevant subset of K17- and Aire-dependent pro-inflammatory genes. These findings provide radically new insight into keratin intermediate filament and Aire function, along with a molecular basis for the K17-dependent amplification of inflammatory and immune responses in diseased epithelia.

Despite preventive human papilloma virus (HPV) vaccination efforts, cervical cancer remains a leading cause of death in women worldwide. Development of therapeutic approaches for cervical cancer are hampered by a lack of mechanistic insight during tumorigenesis. The cytoskeletal protein Keratin 17 (KRT17;K17) is robustly expressed in a broad array of carcinomas, including in cervical tumors, where it has both diagnostic and prognostic value. In this study, we have established multiple functional roles for K17 in the promotion of cervical tumorigenesis in vivo using the established HPV16tg mouse model for cervical squamous cell carcinoma. In HPV16tg/+;Krt17−/−relative to HPV16tg/+ reference female mice, onset of cervical lesions is delayed and closely paralleled by marked reductions in hyperplasia, dysplasia and vascularization. In addition, loss of Krt17 is associated with a cytokine polarization and recruitment of effector immune cells to lesion-prone cervical epithelia. Further, we observed marked enhancement of terminal differentiation in HPV16tg/+;Krt17−/−cervical epithelium accompanied by a stimulation and expansion in the expression of p63, a known basal/reserve cell marker in this tissue. Altogether, the data suggest that the loss of Krt17 may foster an overall protective environment for lesion-prone cervical tissue. In addition to providing new insights into the immunomodulatory and cellular mechanisms of cervical tumorigenesis, these findings may help guide the development of future therapies including vaccines.