Expression of steroidogenic enzymes in human sebaceous glands

Androgens are well known to influence sebum synthesis and secretion. Various factors related to androgen biosynthesis are expressed in human sebaceous glands. In this study, immunohistochemical analysis of human skin specimens from 43 subjects indicated that various androgen-producing and -metabolizing enzymes were functionally localized to sebocytes accumulating lipid droplets and that the exclusive expression of 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2 (HSD17B2)) in sebaceous glands was negatively correlated with that of peroxisome proliferator-activated receptor gamma (PPARγ (PPARG)), which also significantly changed in an age-dependent manner. We also demonstrated that the changes of 17β-HSD2 expression in human immortalized sebocytes (SZ95) influenced the expressions of sebogenesis-related factors. In addition, the overexpression of 17β-HSD2 in SZ95 significantly increased the androstenedione production and markedly decreased the amounts of testosterone and dihydrotestosterone when DHEA was added externally. On the other hand, the phosphorylation of mammalian target of rapamycin, which is well known to induce sebum secretion and the onset and/or aggravation of acne, was increased by the addition of testosterone in the presence of IGF1 in hamster sebocytes. These results all indicated that local androgen biosynthesis and metabolism in human sebaceous glands could play a pivotal role in sebum synthesis and secretion.