ABSTRACT
BACKGROUND: In contrast to the relationship between UV exposure and nonmelanoma skin cancers, molecular evidence for the involvement of UV radiation in melanocytic tumorigenesis is quite limited. Mitogen-activated protein kinase (MAPK) is an important molecule in transducing extracellular signals from the cell surface to the nucleus. The MAPK family includes ERK (extracellular signal- regulated protein kinase), JNK (stress-activated c-Jun N-terminal kinase), and p38 kinases. Various growth factors and cytokines, as well as other signals such as UV light are able to activate MAPK, resulting in a variety of cellular responses including proliferation, differentiation and apoptosis. OBJECTIVE: The purpose of our study was to investigate the effect of UV irradiation on the expression of MAPK in melanocytic nevi. METHOD: Melanocytic nevi from ten healthy volunteers were partially covered, irradiated with a defined UV dose, and excised after 1 week. healthy The irradiated and non-irradiated area were examined separateted by immunohistochemistry using p-ERK, p-JNK, and p-p38 monoclonal antibodies. RESULTS: In the non-irradiated area of melanocytic nevus, p-ERK, p-JNK, and p-p38 were undetectable in nevus cells. After irradiation, p-ERK expression was observed in nevus cells in 7 cases, and p-p38 was stained diffusely in the cytoplasm of nevus cells in 6 cases, but there was no immunoreactivity of p-JNK. CONCLUSION: We suggest that a single UV irradiation of melanocytic nevi can stimulate both p-ERK and cytoplasmic p-p38 expression, but not p-JNK.