Immunohistochemical Study for MAPK Expression in Epidermal Tumors Related to Sun Exposure

Ko, Jung Hun; Kim, Jung Su; Choi, Kyu Cherl; Chung, Byoung Soo

Abstract

BACKGROUND
Mitogen-activated protein kinase(MAPK) is an important molecule in transducing extracellular signal from cell surface to the nucleus. MAPK family includes ERK(extracellular signal-regulated protein kinase), JNK(stress-activated c-Jun N-terminal kinase), p38 kinases. Not only various growth factors and cytokines, but also other signals such as UV light are able to activate MAPK, resulting in various cellular responses including proliferation, differentiation and apoptosis. OBJECTIVE: The purpose of our study was to determine patterns of MAPK expression in epidermal tumors including seborrheic keratosis(SK) on sun-exposed skin and unexposed area, actinic keratosis(AK), Bowen's disease(BD), acantholytic squamous cell carcinoma(ASCC), and other squamous cell carcinoma(SCC). METHODS: Using pan ERK, JNK-2 and p-JNK, we have examined MAPK expression immunohistochemically in epidermal tumors(total 30 cases) including SK on sun-exposed skin(5 cases) and unexposed areas(5 cases), AK(5 cases), BD(5 cases), ASCC(5 cases), and SCC(5 cases). RESULTS: ERK was expressed in AK and ASCC positively but not in BD, and the staining pattern with ERK also showed positivity in microinvasive area and dysplastic cells of SCC. JNK was not expressed in all tumor cells of SK, AK, BD, and ASCC with the exception of dyskeratotic cells in BD and acantholytic cells in ASCC. CONCLUSIONS: We suggest that ERK expression may be related to sun exposure and responsible for proliferation of tumor and invasion into surrounding tissue. JNK may not be related with malignant progression of tumor and carcinogenesis cauesd by sun exposure, but with apoptosis of tumor cells.