Activation of androgen receptor in epidermal growth factor modulation of fetal mouse sexual differentiation

Previous studies from this laboratory indicated a role for epidermal growth factor (EGF) in androgen-dependent male sexual differentiation. The mechanism by which EGF modulates male sexual differentiation has not been determined and investigation has been made to assess the role for androgen receptor (AR) in mediating the EGF-induced effect. We report that EGF, like androgen, stabilized the Wolffian duct in the 13-day female specimen, grown in organ culture. Anti-AR, flutamide and cyproterone acetate blocked the Wolffian duct-stabilizing effect of EGF. EGF also induced cell proliferation of the fetal reproductive tract in a dose-dependent manner and a combination of physiological dosages of EGF and androgen-induced cell proliferation synergistically, suggesting an interactive effect of these two drugs. Cyproterone acetate blocked both EGF-induced normal cell proliferation and the synergistic cell proliferation induced by combination of EGF and androgen suggesting a role of AR in the effects of EGF. The role of AR was further assessed by determining the effect of EGF on AR binding directly. It was shown that EGF stimulated androgen binding activity of the male fetal reproductive tract cells significantly by increasing the number of binding sites by 3-fold with slight decrease in binding affinity. Thus, it appears that AR plays a role in mediating EGF-modulation of sexual differentiation.