Effects of Acute UVB on Retinoid Metabolism

Abstract

Exposure to UVB light is the largest risk factor for the development of cutaneous squamous cell carcinoma, one of the most common cancers in the United States. UVB light causes changes to occur in the skin such as epidermal thickening, hyperproliferation, and alterations to epidermal differentiation. Retinoids regulate the differentiation and proliferation of the epidermis. The purpose of this study is to examine the effect of acute UVB on the expression of retinoid metabolism proteins. There is limited knowledge of how UVB may affect this pathway, and our results will allow us to gain a more complete understanding of changes in the entire retinoid metabolism pathway. We examined the expression of key retinoic acid metabolism proteins in the epidermis and hair follicle remnants 48 hours after UVB exposure in SKH‐1 mice using immunohistochemistry. UVB exposure increased the expression of retinoid synthesis, degradation, and binding proteins, and decreased the expression of the retinol storage enzyme, lectin:retinol acyltransferase (LRAT). These changes in expression suggest that acute UVB increases in the synthesis of retinoic acid in the epidermis. Many of these proteins changed their localization in the epidermis, concentrating in the more differentiated cells of the stratum granulosum and stratum corneum. This change in retinoic acid synthesis could affect the repair and normalization of UVB‐damaged epidermis. This work was supported by the Department of Human Sciences (Human Nutrition), The Molecular Carcinogenesis and Chemoprevention Program of The Ohio State University Comprehensive Cancer Center (grant P30 CA16058, National Cancer Institute) and the Center for Advanced Functional Foods Research and Entrepreneurship (CAFREE).