INTRODUCTION & HYPOTHESIS
Androgens are known to strongly regulate the physio-pathological status of the sebaceous gland. Acne, oily and dry skin are induced or modulated by active androgens, and relationships with the circulating testosterone (TESTO) level have been currently reported. On another hand, little is known about a potential role of the second major circulating androgen dehydroepiandrosterone DHEA in these processes, and speculations about the role of DHEA by itself or in regulating the effects of other androgens have never been clearly confirmed.
We previously established a sebocyte cell line constitutively expressing a functional androgen receptor (AR)1. We showed that the most potent intracellular androgen metabolite, dihydrotestosterone (DHT), induced AR translocation, specific transcripts such as ras-related dexamethasone induced 1 (RASD1) and lipogenesis/lipid storage. We used these parameters to assess the behaviour and activity of the two main circulating androgens TESTO and DHEA, in comparison with DHT, in this model.
The SEBO662AR cell line metabolizes testosterone (which is an active androgen by itself), into other active androgens, especially DHT. The androgenic effect of DHEA by itself or after its potential metabolism remains hypothetic, as well as its influence on the effects of other androgens especially testosterone. We analysed the effects of TESTO and DHEA and their metabolites in this androgen-responsive model.
MATERIALS & MEHODS
AR translocation was followed by immunofluorescence1. Lipid accumulation was evidenced by incubation with the fluorescent probe Bodipy®1. RASD1 expression was measured by RT-qPCR1.
Relative expression levels of the androgen-metabolizing enzyme transcripts were obained from Affymetrix full transcriptome data1. [14C]-TESTO and [14C]-DHEA metabolism was analysed after incubation with cell cultures for different times followed by metabolite extraction, chromatography/phosphorimaging as previously described2.
1 – Exogenous androgens (TESTO, DHEA) & DHT activity
2 – Exogenous androgens (TESTO, DHEA) metabolism & activity
In this model,
– TESTO is an active androgen by itself and is converted into DHT through the activity of type 1 5-alpha reductase. DHT direct androgenic activity is achieved at concentrations 10-fold lower than TESTO. Other metabolites are also formed such as –dione metabolites which exhibit a low but significant androgenic activity (> 10-fold less active than TESTO).
– DHEA is totally inactive by itself. It is not transformed into TESTO and 3bHSD expression was not detected. DHEA is very slowly metabolized into androsterone and other discrete species. Androsterone is moderately active by itself (> 10-fold less active than TESTO) and could explain the low activity of DHEA in long term assays.
– An excess of DHEA did not interfere with Testo metabolism and DHT production, nor with the androgenic activity of DHT, thus it cannot be considered as a “competitor” of TESTO.
1 Barrault et al. (2015) J Steroid Biochem Mol Biol ;152:34-44
2 Bernard et al. (2000) Int J Cosmet Sci ;22:397-407