Estrogen Exhibits a Biphasic Effect on Prostate Tumor Growth through the Estrogen Receptor β-KLF5 Pathway.

Estrogens are effective in the treatment of prostate cancer; however, the effects of estrogens on prostate cancer are enigmatic. In this study, we demonstrated that estrogen (17β-estradiol [E2]) has biphasic effects on prostate tumor growth. A lower dose of E2 increased tumor growth in mouse xenograft models using DU145 and PC-3 human prostate cancer cells, whereas a higher dose significantly decreased tumor growth.

Estrogen regulates tumor growth through a nonclassical pathway that includes the transcription factors ERβ and KLF5.

Clinical evidence suggests that antiestrogens inhibit the development of androgen-insensitive prostate cancer. Here, we show that the estrogen receptor β (ERβ) mediates inhibition by the antiestrogen ICI 182,780 (ICI) and its enhancement by estrogen. ERβ associated with gene promoters through the tumor-suppressing transcription factor KLF5 (Krüppel-like zinc finger transcription factor 5).