INSULIN-LIKE GROWTH FACTOR-BINDING PROTEIN-2 AND PROTEIN-3 EXPRESSIONIN BENIGN HUMAN PROSTATE EPITHELIUM, PROSTATE INTRAEPITHELIAL NEOPLASIA, AND ADENOCARCINOMA OF THE PROSTATE
Mk. Tennant et al., INSULIN-LIKE GROWTH FACTOR-BINDING PROTEIN-2 AND PROTEIN-3 EXPRESSIONIN BENIGN HUMAN PROSTATE EPITHELIUM, PROSTATE INTRAEPITHELIAL NEOPLASIA, AND ADENOCARCINOMA OF THE PROSTATE, The Journal of clinical endocrinology and metabolism, 81(1), 1996, pp. 411-420
Insulin-Like growth factor (IGF)-binding proteins (IGFBPs) modulate th
e activity of IGFs. In vitro human prostate epithelial cells secrete I
GFBP-2 and -3. In vivo IGFBP-2 is increased, and IGFBP-3 is decreased
in the serum of patients with prostate cancer. Immunohistochemistry an
d in situ hybridization were performed to compare the expression of IG
PBP-2 and -3 in vivo in prostate tissue containing benign epithelium,
high grade prostate intraepithelial neoplasia (PIN), and adenocarcinom
a. Immunoreactivity and messenger ribonucleic acid (mRNA) hybridizatio
n signals for IGFBP-2 and -3 were localized to epithelial cells. IGFBP
-2 immunostaining intensity was significantly increased in PIN regions
compared to that in normal epithelium and was further increased in ma
lignant cells. IGFBP-3 mRNA was also significantly increased in PIN an
d cancer cells. IGFBP-3 immunoreactivity was significantly increased i
n PIN regions compared to normal epithelium; however, IGFBP-3 protein
was significantly decreased in malignant cells. IGFBP-2 mRNA remained
virtually unchanged in benign epithelium, PIN, and adenocarcinoma cell
s. These results demonstrate that increased IGFBP-2 protein in PIN and
malignant cells is probably due to increased mRNA expression. However
, levels of IGFBP-3 protein may be due to pre- and/or posttranslationa
l mechanisms, including proteolysis. The changes in IGFBP-2 and -3 pro
tein levels in prostate tissue are in agreement with serum changes rep
orted in patients with prostate cancer.