ESPE Abstracts

Steroidogenic enzyme expression in the fetal adrenal and the placenta hints at the production and metabolism of adrenal-derived 11-oxy androgens (11OxyAs) in the fetal-placental unit. Thus, 11OxyAs are present in placental tissue, fetal cord blood and neonatal serum, and could have a particular role during fetal development. The metabolism of the 11OxyAs in the fetal unit, therefore, presents as a focal point of investigation. Adrenal androgens are primarily metabolized by the fetal liver cytochrome P450 3A7 (CYP3A7) producing metabolites that circulate to the placenta, evident in the conversion of dehydroepiandrosterone/-sulfate (DHEA/-S) to 16⍺-hydroxy-DHEA/-S in the liver and the production of estriol in the placenta. Notably, CYP3A7 expression decreases after birth, with a concomitant increase in the expression of CYP3A4. To date, the catalytic activities of these CYP3A isoforms towards the 11OxyAs have not been studied and the role of CYP3A7 in this biological route from the adrenal to the liver to the placenta is of interest, as it would regulate the biological activity of the 11OxyAs, especially in clinical conditions characterized by adrenal androgen excess. This study aimed to investigate the conversion of the 11OxyAs (11β-hydroxyandrostenedione [11OHA4], 11β-hydroxytestosterone [11OHT], 11keto-androstenedione [11KA4], 11keto-testosterone [11KT]) and the classical androgens (androstenedione, testosterone, and DHEA) by CYP3A7 and CYP3A4. Using recombinant proteins and transiently transfected HEK293 cells, together with liquid- and gas-chromatography mass spectrometry (LC-/GC-MS), steroid conversions and steroid products were investigated. The conversions of 11OHA4, 11KA4 and 11KT were catalyzed comparably by recombinant CYP3A7, while the conversion of 11OHT was doubled compared to the other 11OxyAs. Most interestingly, the 11OxyAs were converted 2.5-fold (P<0.01) and 4-fold (P<0.001) less compared to testosterone and androstenedione, respectively, and DHEA (90% metabolized) was the control for the reaction. CYP3A4 metabolized both testosterone and DHEA, 95%, compared to androstenedione, 75%, and again the 11OxyAs were not as efficiently metabolized compared to the classical androgens (3.5-fold less). In support of these results, our cell system also showed less efficient conversion of the 11OxyAs compared to androstenedione and testosterone. Moreover, unique GC-MS spectral patterns identify the novel CYP3A metabolites of the 11OxyAs as C6-hydroxylated 11OxyAs. To summarize, our data show the metabolism of 11OxyAs by CYP3As is less efficient compared to classical androgens. Therefore, if overproduced, 11OxyAs would not be efficiently metabolized by CYP3A7 in the fetal stage nor by CYP3A4 in the neonatal stage, underscoring the bioavailability of the 11OxyAs in hyperandrogenic endocrine disorders.