Constitutive Production of Platelet-derived Growth Factor-like Proteins by Human Prostate Carcinoma Cell Lines1

Prostate carcinoma cell lines DU-14S and PC-3 express both platelet derived growth factor (PDGF)-1 and PDGF-2/s/Ãgenes. Concomitantly, these cells synthesize and secrete PDGF-like proteins, as judged by indirect immunofluorescence and by direct immunoprecipitation with specific PDGF antiserum. Conditioned media derived from DU-145 and PC-3 cells stimulated the incorporation of [3H]thymidine by 3T3 cells and competed with I25l-labeled PDGF for its binding to cell surface receptors of 3T3 cells. The biological activity was stable to heating at 100°Cfor 10 min, sensitive to reducing agents, and neutralized by the IgG fraction of PDGF ant ¡scrum,properties similar to those of authentic PDGF. Both DU-145 and PC-3 cell lines appear to lack receptors for PDGF as indicated by their inability to mitogenically respond to PDGF and receptor binding of '"I-labelcd PDGF. Production of PDGF-like proteins by human prostate carcinoma cells may play an important role in a paracrine mode in the organization of the extracellular matrix of the malignant tissue.