The Formation of 5α-Reduced Androgens in Stromal Cells from Human Breast Adipose Tissue*

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Abstract
The present study was designed to determine if stromal cells derived from human breast adipose tissue contain 5α-reductase activity, and to study the effect of 5a-reduced androgens on aromatase activity under basal and cortisol stimulated conditions. Stromal cells were prepared from breast adipose tissue obtained at the time of surgery from four patients. The cells were isolated after collagenase digestion and were cultured in α-minimum essential medium with 15% fetal calf serum. Studies were carried out between days 4 and 11 of the third subculture in the presence or absence of cortisol (10−6 M). Metabolism of androstenedione (A) was studied over a period of 8 h after addition of medium containing 20 × 106 dpm (100 pM) [3H]A. The cells metabolized A to estrone (E1), testosterone (T), 5α-androstane 3, 17-dione (5α-A-dione), androsterone (AND), and dihydrotestosterone. On day 7 of culture, product formation expressed as percent conversion of A per 1 × 106 cells ranged as follows: E1, 0.02-0.13; T, 0.12-0.36; 5α-A-dione, 2.05-9.91; and a fraction containing AND and dihydrotestosterone, 0.38-0.59. In the presence of cortisol the rate of cell growth was decreased by 25% to 50%. The formation of E1 increased 150- to 1500-fold and AND formation increased 2- to 8-fold. There was no consistent change in the formation of 5α-A-dione and T. The addition of 5α-Adione (10−6 M) to the culture medium at the time of assay resulted in greater than 90% inhibition of E1 formation under both basal and cortisol stimulated conditions. The studies indicate that adipose tissue is an important site for the formation of 5α-reduced androgens.