Bakuchiol suppresses oestrogen/testosterone-induced Benign Prostatic Hyperplasia development through up-regulation of epithelial estrogen receptor beta and down-regulation of stromal aromatase

摘要

Estrogens and androgens play critical roles during benign prostatic hyperplasia (BPH) development. Estrogen receptors (ERs), androgen receptor (AR) and aromatase, the key conversion enzyme of androgen to estrogen, are thought to be the effective targets for BPH treatment. Bakuchiol (Ba)-containing herb Psoralea corylifolia has been long-termed used for BPH patients in traditional Chinese medicine while the role and regulatory mechanism of Ba involved remain unclear. Human prostatic cell lines WPMY-1 and BPH-1 and oestrodial/testosterone-induced BPH rats were used as the in vitro and in vivo models. Ba significantly inhibited the proliferation of WPMY-1 and BPH-1 cells. In E2/T-induced BPH model, Ba treatment also significantly inhibited the enlargement of prostate, decreased PI values, reduced the thickness of periglanular smooth muscle layer, and down-regulated the expressions of PCNA and smooth muscle cell marker alpha-SMA, all of which were highly induced in BPH rats. Moreover, the basal and PGE2-induced expressions of aromatase were reduced in Ba-stimulated WPMY-1 cells, while the expression of ER beta was highly increased in Ba-stimulated BPH-1 cells, both of which are consistent with the findings in Ba group in vivo. Ba induced ERE activity in BPH-1 cells as E2 did; however, silence of ER beta not ER alpha, blocked Ba-induced ERE activity while E2 still exhibited the significant ERE activity, indicating the regulation of estrogen signaling by Ba is particularly via ER beta. In conclusion, by downregulation of stromal aromatase and up-regulation of epithelial ER beta, Ba contributes to the balance of estrogen and androgen signaling and further inhibits BPH development.