Drospirenone drsp

11KT, 11KDHT and mibolerone (Mib) were purchased from Steraloids. T and DHT were purchased from Sigma-Aldrich, while [H³]-Mib (76.8 Ci/mmol) was purchased from Perkin Elmer. All steroids were dissolved in absolute ethanol and added to the culturing medium at a final concentration of no more than 0.1% ethanol. Cortisol-9, 11, 12, 12-d4 (cortisol-d9), testosterone-1, 2-d2 (T-d2), progesterone-2, 2, 4, 6, 6, 17α, 21, 21, 21-d9 (P4-d9) and 4-pregnen-17α-ol-3,20-dione-2, 2, 4, 6, 6, 21, 21, 21-d8 (17OHP4-d8) were purchased from Cambridge Isotope Laboratories. Gestodene (GES) and drospirenone (DRSP) were purchased from Sigma-Aldrich.

The human MCF-7 BUS (also known as MCF-7 BOS) breast cancer cell line was received from Prof. Ana Soto (Tufts University, Boston), and authenticated by short-tandem repeat profiling (NorthGene). The cells were maintained in Dulbecco’s Modified Eagle’s Medium (DMEM) containing 4.5 g/L glucose (Sigma-Aldrich, RSA), 5% heat-inactivated (HI) fetal calf serum (FCS) (Biochrom GmbH, Germany) and 100 IU/ml penicillin and 100 μg/ml streptomycin (Sigma-Aldrich, RSA) as previously described (35 (link)). All experiments were conducted within the first 35 passages since the cell line was thawed from storage, and only mycoplasma-negative cells were used. 17β-estradiol (E₂), P₄, MPA, NET, drospirenone (DRSP) and fulvestrant (ICI-182,780; ICI) were obtained from Sigma-Aldrich, RSA.