Testosterone metabolism by cultured human beard outer root sheath cells in comparison with epidermal keratinocytes

In order to elucidate the mechanism of action of androgen in human hair follicles, we studied testosterone metabolism by cultured beard outer root sheath cells in comparison with that of epidermal keratinocytes. When cells were incubated as a monolayer in serum-free keratinocyte growth medium with physiological concentrations (25 nM) of [3H]testosterone, the major metabolite was androstenedione in either type of cells. Small amounts of androstanedione, dihydrotestosterone and androsterone were also formed. The ratio of apparent 5 alpha-reductase to 17 beta-hydroxy-steroid dehydrogenase activities ranged from 0.11 to 0.81 and did not differ between these two kinds of cells. After these cells were cultured in the presence of 10% fetal calf serum for 10 days, the activities of both metabolic pathways markedly increased without significant changes of the ratio of activities of these two enzymes. Thus, testosterone was rather converted to weak androgens even in beard outer root sheath cells under the experimental conditions.