J. Soc. Cosmet. Chem., 35, 197-205 (July 1984) Effects of the chemical irritants anthralin and benzoyl peroxide on mouse skin epithelial cell protein production CHRISTOPHER J. MOLLOY, MICHAEL A. GALLO, and JEFFREY D. LASKIN, Department of Environmental and Community Medicine, UMDNJ-Rutgers Medical School, Joint Program in Toxicology, Rutgers University, Piscataway, NJ 08854. Received November 15, 1983. Presented at the Society of Cosmetic Chemists Annual Meeting, New York, December 1, 1983. Synopsis The widely used topical agents anthralin and benzoyl peroxide are potent skin irritants. In the mouse skin model these compounds produce hyperplasia and are effective skin tumor promoters. In the present studies, we have examined the effects of anthralin and benzoyl peroxide on epidermal proteins and compared them with changes produced by the potent phorbol ester tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). All compounds were applied topically to the shaved dorsal skin of mice. Twenty-four hours later skin fragments were pulse-labeled with 35S-methionine to assay total protein production. Anthralin and TPA produced a marked inhibition of protein synthesis when compared to control and benzoyl peroxide- treated skin. When skin was treated with anthralin at a promoting dose (80 }xg, 354 nmole), incorporation of the radiolabel into epidermis was only 22% of control. Promoting doses of TPA (10 }xg, 17 nmole), however, inhibited protein synthesis to 63% of control. Qualitative changes in protein production induced by the chemicals were examined using one- and two-dimensional gel electrophoresis. Using these tech- niques, we were able to detect over 100 individual proteins from both treated and untreated mouse skin. TPA and anthralin were found to alter the production of at least seven distinct proteins, six of which are keratins. The profile of benzoyl peroxide-treated epidermal proteins, however, resembled those of control skin, suggesting that this chemical promoter may act by a mechanism distinct from TPA and anthralin. INTRODUCTION Anthralin (1,8-dihydroxy-9-anthrone) and benzoyl peroxide are common pharmacologic agents employed in the topical treatment of various skin disorders. Anthralin is active against psoriasis and has been used clinically over the past 50 years (1). Benzoyl peroxide is a common ingredient in proprietary acne formulations (2). Both compounds, while structurally quite dissimilar (Figure 1), have in common the ability to cause skin irritation and tumor promotion in the two-stage mouse skin carcinogenesis assay (3,4). Tumor promoters do not cause cancer alone, but act to facilitate the expression of the altered tumor cell phenotype through mechanisms as yet unclear (for a review, see Weinstein, et al., ref 5). The most potent chemical of this class is the phorbol ester, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), derived from croton oil (6). Application 197

198 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Anthralin Benzoyl Peroxide OR • '-,•OR = • R 1= CO-(CH= )•=-CH 3 O R =.- COCH= CH=OH TPA Figure 1. Structures of TPA, anthralin, and benzoyl peroxide. of TPA to mouse skin causes a series of morphologic and biochemical changes. These include inflammation and epidermal hyperplasia as well as changes in cell growth and differentiation (7,8). Anthralin has been shown to be the most potent non-phorbol ester tumor promoter in the mouse skin bioassay (4). It inhibits DNA replication and repair (9), mitotic activity in skin (10), and DNA, RNA, and protein synthesis in cultured human fibroblasts (11). Benzoyl peroxide is a free radical-generating compound that, in addition to its tumor-promoting activity, is a potent inducer of epidermal hyperplasia (12). Previous studies have shown that benzoyl peroxide can induce mor- phologic changes in mouse skin similar to those observed with TPA (3). Benzoyl peroxide has also been shown to decrease cellular metabolic cooperation in Chinese hamster cells in vitro, a property correlated with tumor-promoting activity (3).