Alterations in the expression of specific epidermal keratin markers in the hairless mouse by the topical application of the tumor promoters 2,3,7,8-tetrachlorodibenzo-<i>p</i>-dioxin and the phorbol ester 12-<i>O</i>-tetradecanoylphorbol-13-acetate

The study investigated the effects of the toxin TCDD on keratin expression in hairless and haired HRS/J mice. Both TCDD and the tumor promoter TPA caused dose-dependent epidermal hyperplasia and altered keratin subunit expression. In hairless mice, TCDD decreased the synthesis of specific keratins associated with suprabasal differentiation and increased those linked to basal cell proliferation. In haired mice, TCDD-induced hyperplasia was associated with changes in keratin synthesis indicative of increased basal cell proliferation. The findings suggested that TCDD alters epidermal differentiation patterns in hairless mice, potentially due to molecular events affecting keratin gene expression, which may relate to the specific toxicity of TCDD in different strains or species.