SERUM INSULIN-LIKE GROWTH FACTOR-BINDING PROTEIN-2 (IGFBP-2) IS INCREASED AND IGFBP-3 IS DECREASED IN PATIENTS WITH PROSTATE-CANCER - CORRELATION WITH SERUM PROSTATE-SPECIFIC ANTIGEN

Insulin-like growth factors (IGFs) are potent mitogens that stimulate the growth of prostate cells. In serum, IGFs circulate bound to IGF-bi nding proteins (IGFBPs), which modulate their proliferative action. We studied the electrophoretic pattern of IGFBPs in the serum of patient s with prostate cancer and in individuals with increased serum levels of prostate-specific antigen (PSA) in the absence of prostate malignan cy. Serum IGFBP-2 was dramatically increased in patients with metastat ic prostate cancer compared with healthy controls (23.83 +/- 6.93% vs. 2.95 +/- 0.52% of total serum IGFBPs; P < 0.02). A moderate rise in I GFBP-2 was also observed among patients with increased PSA without mal ignancy. In contrast, a decrease in serum IGFBP-3 was detected in most patients with metastatic prostate cancer (68.2 +/- 9.1% vs. 95.4 +/- 0.9% of total serum IGFBPs; P < 0.02) and was more pronounced in advan ced cases. A highly significant correlation between serum IGFBP-2 and PSA levels was found (r = 0.62; P < 0.002), with a significant negativ e correlation between serum PSA and IGFBP-3 (r = -0.63; P < 0.002). We suggest that IGFBPs may be involved in growth modulation of prostate malignancy and that alterations in their serum levels may serve as a m arker for prostate cancer.