Silencing of the GnRH type 1 receptor blocks the antiproliferative effect of the GnRH agonist, leuprolide, on the androgen-independent prostate cancer cell line DU145

This study investigated the mechanism of action of a gonadotropin-releasing hormone (GnRH) agonist, leuprolide, on proliferation of the hormone-refractory prostate cancer cell line DU145, transfected with short hairpin RNA (shRNA), to reduce expression of the GNRHR1 gene (which encodes the GnRH type 1 receptor). DU145 cell proliferation in the presence of leuprolide (10−9 and 10−7 M) or control medium was measured before and after GnRHR1 knockdown. Reverse transcription—polymerase chain reaction and Western blot analysis were used to measure the degree of GNRHR1 silencing. DU145 cells treated with leuprolide (10−9 and 10−7 M) showed significant growth inhibition compared with control-treated DU145 cells. Transfection with GNRHR1–shRNA significantly decreased GNRHR1 expression at 48 h. DU145 cells transfected with silencing GNRHR1–shRNA showed normal growth patterns; however, there was no significant inhibition of proliferation of DU145 cells transfected with GNRHR1–shRNA compared with cells transfected with control—shRNA in response to leuprolide. These data demonstrated that the antiproliferative effect of leuprolide was mediated by the GnRHR1.