Primary keratinocyte model of actinic keratosis reveals UV-induced DNA damage accumulation and persistent IFN signaling

Actinic keratosis (AK) is a precancerous, UV-induced skin lesion that can progress to cutaneous squamous cell carcinoma. Although UVR drives field cancerization and immunosuppression in the skin, keratinocyte-intrinsic responses to chronic, low-dose UV exposure have been insufficiently studied in AK. We established a patient-derived in vitro model using primary keratinocytes from AK lesions and age-matched, sun-exposed skin to investigate how repeated low-dose UV irradiation shapes keratinocyte stress responses. Integrating morphological profiling, cyclobutane pyrimidine dimer quantification, and bulk RNA sequencing, we observed morphological remodeling and accumulating DNA damage in AK keratinocytes despite activation of DNA repair and unfolded protein response pathways. Transcriptomic analyses revealed constitutive and UV-enhanced IFN signaling in AK cells, including upregulation of innate DNA sensing and ISGylation genes. Meta-analysis of 5 independent datasets validated IFN pathway activation as a conserved feature of AK, and IFNα exposure further sensitized AK keratinocytes to UV-induced cyclobutane pyrimidine dimer accumulation. Immunohistochemistry confirmed lesion-specific enrichment of ISG15 and UBE2L6 in AK epidermis, indicating spatially confined IFN pathway activation in vivo. Our model uncovers sustained IFN signaling and attenuated DNA damage repair as keratinocyte-intrinsic features of AK, suggesting that persistent IFN responses may modulate UV-induced damage responses and contribute to early photocarcinogenesis.