Primary Keratinocyte Model of Actinic Keratosis Reveals UV-Induced DNA Damage Accumulation and Persistent Interferon Signaling

Actinic keratosis (AK) is a precancerous, UV-induced skin lesion that can progress to cutaneous squamous cell carcinoma (cSCC). While UV radiation is known to drive mutations and immunosuppression in the skin, keratinocyte-intrinsic responses to chronic, low-dose solar 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 high-content morphological profiling, cyclobutane pyrimidine dimer (CPD) quantification and bulk RNA sequencing, we observed pronounced morphological remodeling and persistent DNA damage in AK keratinocytes despite activation of DNA repair and unfolded protein response pathways. Transcriptomic analyses revealed constitutive and UV-enhanced interferon signaling in AK cells, including upregulation of innate DNA sensing and ISGylation genes. Meta-analysis of five independent datasets confirmed interferon pathway activation as a conserved feature of AK, and IFN-α exposure further sensitized AK keratinocytes to UV-induced CPD formation. Our primary model thus uncovers sustained interferon signaling and attenuated DNA damage repair as key keratinocyte-intrinsic features of AK, suggesting that chronic interferon responses may modulate UV-induced damage and contribute to early photocarcinogenic processes.