Induction of platelet-derived growth factor A and B chains and over-expression of their receptors in human pancreatic cancer.

Expression of platelet-derived growth factor (PDGF) and PDGF receptors was examined in cultured human pancreatic cancer cells, in the normal human pancreas and in pancreatic adenocarcinomas. mRNA transcripts encoding PDGF A and B chains, and PDGF receptor beta (PDGFR beta) were present in PANC-I and HPAF human pancreatic cancer cells. Transforming growth factor beta I (TGF-beta I), but not PDGF-AA or -BB, enhanced PDGF A and B chain mRNA levels in both cell lines. In the normal human pancreas PDGF A chain mRNA levels were relatively abundant, whereas PDGF B chain mRNA levels were not detected and PDGF receptor alpha (PDGFR alpha) and beta mRNA transcripts were present at low levels. PDGF immunoreactivity was present in islet cells, and PDGFR alpha was present in acinar cells, whereas PDGFR beta was present in acinar cells and in the connective tissue. In the pancreatic cancers, PDGF A chain mRNA transcripts were also abundant, and 6 of 13 samples exhibited the PDGF B chain mRNA transcript. In addition, there was a 7-fold increase in the levels of PDGFR alpha and PDGFR beta in the cancer samples by comparison with the normal pancreas. By immunohistochemistry, PDGF and both PDGF receptors were present in the cancer cells, and PDGFR beta was abundant in fibroblasts and endothelial cells within the connective tissue.