The role of estrogen receptor, androgen receptor and growth factors in diethylstilbestrol-induced programming of prostate differentiation.
Recently, others and we have demonstrated that prenatal exposure to an extremely low dose of diethylstilbestrol (DES) and other estrogenic compounds produces a significant effect on mouse prostate development in vivo and in vitro in the presence and absence of androgen. In this study, we investigated the mechanism by which DES produces this effect and determined the role of its estrogenic activity on the growth and branching, induced by DES in the 17-day-old fetal prostate in culture. Additionally, we investigated whether the androgen receptor (AR) plays a role and whether any of the growth factors, namely, EGF and IGF-1 which are known to modulate the estrogen receptor (ER) and androgen receptor (AR)-dependent process, mediate the DES-induced effects. Using the organ culture bioassay of prostate development, we demonstrate that DES enhanced the growth and branching of the prostate at both 0.1 and 0.5 pg/ml dosages, thus, confirming a previous report of ours. An anti-estrogen, ICI164,387 blocked both of the effect of DES, suggesting that both of these two effects are ER dependent. Anti-androgen, flutamide also blocked both branching and prostatic growth induced by DES, while cyproterone acetate blocked only the branching effect, suggesting a role for AR in the DES-induced effects. Depletion of EGF by anti-EGF antibody blocked the DES-induced effects and this was reversed following EGF replacement in the organ culture system. Anti-IGF-1 antibody, on the other hand, only blocked the branching effect, but produced no effect on the prostatic growth, induced by DES. Estrogenic chemicals, bisphenol A and DES enhanced EGF-mRNA level of the cultured prostates. Taken together, it appears that DES-induced prostatic enlargement involves enhancement of ER-dependent EGF and IGF-1 synthesis, mediating prostatic enlargement and androgen action.