Loss of WWOX Drives Cutaneous Squamous Cell Carcinoma (cSCC) through Regulating EMT [ChIP-Seq]

Cutaneous Squamous Cell Carcinoma (cSCC) is the second most common skin cancer, with a rising incidence in recent years. Through protein-protein interactions, the WW domain-containing oxidoreductase (WWOX) has been found to be a key player in many cellular processes, including DNA repair, apoptosis, metabolism, and transcriptional regulation. WWOX loss has been reported in many malignancies, including cSCC, suggesting a tumor suppressor role, but its function as a skin cancer antagonist and the underlying molecular mechanisms are not yet fully understood. To better understand WWOX's role in cSCC, we generated K14-Cre;Wwox;Trp53 conditional knock-out mice, leading to the development of cSCC. Strikingly, mice with ablated WWOX developed cSCC with increased penetrance and earlier onset. Characterization of cSCC morphology, immune markers, and transcriptional signatures revealed poorly differentiated cSCC with epithelial-to-mesenchymal transition (EMT) traits in tumors lacking WWOX compared to their controls. The hyperplastic phenotype of the epidermis in conditionally Wwox-knock-out mice was observed at an early age and impacted the surrounding microenvironment as well. Based on WWOX's known interaction with and stabilization of the transcription factor p63, we proposed that epidermal WWOX loss reduces p63 levels, destabilizing the tissue's epithelial integrity. Indeed, our findings confirmed this mechanism, demonstrating that diminished p63 impairs the epidermal protective barrier and accelerates the progression of aggressive cSCC. The WWOX-p63 correlation was also observed in human cSCC samples, inversely related to tumor stage. These findings were further supported in keratinocytes and cSCC human cell line models, where WWOX deficiency led to reduced p63 expression, concomitant with enhanced tumorigenic potential and migratory capacity.