Inverse relation between prostate-specific antigen and insulin-like growthfactor-binding protein 3 in bone metastases and serum of patients with prostate cancer

The usual osteoblastic phenotype of metastatic prostate cancer is unexplain ed. Here we show that tissue and serum concentrations of prostate-specific antigen (PSA)-vary inversely with a substrate protein that binds a growth f actor known to activate osteoblasts, These findings suggest that PSA may co ntribute to the osteoblastic phenotype, and could thus represent a new drug target devoid of antiandrogenic toxicity.