The IGF axis in the prostate.
The insulin-like growth factor (IGF) axis is a multi-component network of molecules involved in the regulation of cell growth. The axis includes two major ligands, (IGF-I and IGF-II), cell surface receptors, (the type I IGF receptor family as well as the type II IGF receptor), a family of high affinity binding proteins which regulate IGF availability to the receptors, (the IGFBPs), and a group of IGFBP proteases which cleave IGFBBPs and modulate IGF action. Human seminal plasma contains IGF-I and -II, IGFBP-2 and -4, as well as IGFBP-3 fragments and IGFBP-3 protease activity. A prostatic source for these IGF-axis molecules is likely. We have demonstrated the human prostate to contain all the elements of a functional IGF system. Prostate fibroblasts in primary culture (PC-F) express mRNA for IGF-II and produce IGF-II peptide in biologically active concentrations. This IGF-II appears to be of a high molecular weight (15 kD) species. Prostate epithelial cells in primary culture (PC-E) express the type I IGF receptor. These cells also produce IGFBP-2 and -4, (on both mRNA and peptide levels), while PC-F secrete IGFBP-2, -3 and -4. PC-E are exquisitely sensitive to the mitogenic effects of IGFs. Finally, prostate specific antigen (PSA), secreted from PC- and found in seminal plasma, can function as a potent IGFBP-3 protease. This IGFBP-3 protease activity can remove the inhibitory effects of IGFBP-3 on IGF-I induced PC-3 growth.(ABSTRACT TRUNCATED AT 250 WORDS)
Cohen
P
P
Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia.
Peehl
D M
DM
Rosenfeld
R G
RG
D000818:Animals; D006801:Humans; D008297:Male; D011467:Prostate / Q000166:cytology / Q000502:physiology*; D017527:Receptor, IGF Type 2 / Q000096:biosynthesis / Q000502:physiology; D013002:Somatomedins / Q000502:physiology*
D017527:Receptor, IGF Type 2; D013002:Somatomedins