ENHANCED EXPRESSION OF THE TYPE-II TRANSFORMING GROWTH-FACTOR-BETA RECEPTOR IN HUMAN PANCREATIC-CANCER CELLS WITHOUT ALTERATION OF TYPE-III RECEPTOR EXPRESSION

We have recently found that human pancreatic adenocarcinomas exhibit strong immunostaining for the three mammalian transforming growth factor beta (TGF-beta) isoforms. These important growth-regulating polypeptides bind to a number of proteins, including the type I TGF-beta receptor (TbetaR-I), type II TGF-beta receptor (TbetaR-II), and the type III TGF-beta receptor (TbetaR-III). In the present study we sought to determine whether TbetaR-II and TbetaR-III expression is altered in pancreatic cancer. Northern blot analysis indicated that, by comparison with the normal pancreas, pancreatic adenocarcinomas exhibited a 4.6-fold increase (P < 0.01) in mRNA levels encoding TbetaR-II. In contrast, mRNA levels encoding TbetaR-III were not increased. In situ hybridization showed that TbetaR-II mRNA was expressed in the majority of cancer cells, whereas mRNA grains encoding TbetaR-III were detectable in only a few cancer cells and were present mainly in the surrounding stroma. These findings suggest that enhanced levels of TbetaR-II may have a role in regulating human pancreatic cancer cell growth, while TbetaR-III may function in the extracellular matrix.