Expression of bone morphogenetic protein-7 (BMP-7) in human prostate.

BACKGROUND

It is known that BMP is a factor that strongly induces bone formation in muscle tissue. However, the expression of BMP-7 is not detected in normal bone tissues. Recently, we reported that the level of BMP-7 expression was significantly higher in metastatic bone lesions than in normal bone and that the high expression of BMP-7 in metastatic bone lesions was related to osteoblastic metastasis. The aim of this study was to investigate the level of BMP-7 gene expression in normal prostate glandular tissues, newly diagnosed prostate cancer tissues, and local recurrent prostate cancer tissues.

METHODS

Total RNA was extracted from 23 samples of normal prostate glandular tissues, 28 samples of newly diagnosed prostate cancer tissues, and 23 samples of local recurrent prostate cancer tissues. We also examined the expression of BMP-7 in human prostatic epithelial cells (HPECs) under conditions of androgen replacement. After reverse transcription of the RNA samples, the expression of BMP-7 was measured by real-time quantitative polymerase chain reaction (PCR). Glyceraldehyde phosphate dehydrogenase (GAPDH) was used as an internal standard.

RESULTS

The level of BMP-7 expression was highest in the normal prostate glandular tissue (P < 0.05). The expression of BMP-7 tended to be lower during the development and progression of prostate cancer. The expression of BMP-7 in prostate epithelial cells treated with 10(-7) M dihydrotestosterone (DHT) was significantly higher than in the DHT-free control (P = 0.0285).

CONCLUSIONS

It has been reported that the BMP-7 mRNA level is androgen-dependent in the mouse prostate. The present results suggest that the BMP-7 mRNA level is androgen-dependent in the human prostate, since the expression of BMP-7 was decreased in local recurrent prostate cancer tissues after hormonal therapy and was increased by DHT.