Mitotane has an estrogenic effect on sex hormone-binding globulin and corticosteroid-binding globulin in humans

Context: Side effects of mitotane (o,p′-DDD) have suggested estrogenic effects. Objective: The objective of the study was to explore o,p′-DDD potential estrogenic effect on SHBG and corticosteroid-binding globulin (CBG). Design: Human hepatoma cell lines (HepG2), lacking estrogen receptor (ER)-α, and Hep89, stably transfected by ERα, were used. Setting: The study was conducted at an academic research laboratory and medical center. Patients and Other Participants: The study included 10 male patients with recurrent adrenal carcinoma, receiving mitotane (4-6.5 g daily) for more than 6 months. Main Outcome Measures: The main outcome measures were SHBG/CBG mRNA levels measured by real-time PCR, culture medium SHBG/CBG concentrations measured by specific immunoassays, and transient transfection experiments with human SHBG proximal promoter reporter constructs. Results: Increased serum SHBG and CBG concentrations, which exceeded normal male limits, were observed in most mitotane-treated patients. In the HepG2 cell line, 17β-estradiol (E2) or o,p′-DDD treatment had no effect on mRNA or SHBG/CBG concentrations. In contrast, in the Hep89 cell line, E2 increased concentrations of SHBG (r = 0.44, P < 0.0001) and CBG (r = 0.585, P < 0.0001) secreted into culture media in a dose-dependent manner. o,p′-DDD significantly increased SHBG (150% vs. control, P < 0.05) and CBG (184% vs. control, P < 0.05) production by Hep89 cells, at a concentration of 2 × 10^-5 M. Transient transfection experiments in Hep89 cells showed that E2 or o,p′-DDD treatment did not increase the transcriptional activity of the minimal proximal promoter of human SHBG gene. Conclusions: Mitotane increased SHBG/CBG gene expression and liver production by mechanisms requiring the presence of ERα.