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

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