Loss of BMP2, Smad8, and Smad4 expression in prostate cancer progression.

Background: The role of the bone morphogenetic protein (BMP) pathway in prostate cancer (PC) is unclear. This study aimed to characterize aspects of the BMP pathway in PC by assessing BMP2, Smad8, and Smad4 expression in normal, hyperplastic, and malignant prostate tissue, and to correlate findings with progression to PC.

Methods: Radical prostatectomy (RP) specimens from 74 patients with clinically localized PC (median follow-up 51 months, range 15-152), 44 benign prostatic hypertrophy (BPH) lesions, and 4 normal prostates (NPs) were assessed for BMP2, Smad8, and Smad4 expression using immunohistochemistry.

Results: Both BMP2 (P < 0.001) and nuclear Smad4 (P < 0.0001) expression were significantly decreased in PC compared to benign prostate tissue. Nuclear Smad8 was present in normal/benign prostate tissue but absent in PC and adjacent hyperplasia. Furthermore, loss of BMP2 (P < 0.001) and decreased nuclear Smad4 (P = 0.05) expression correlated with increasing Gleason score.

Conclusions: These data suggest that decreased BMP2, nuclear smad8 and nuclear Smad4 expression are associated with the progression to PC, and in particular loss of BMP2 and Smad4 are related to progression to a more aggressive phenotype.