Enhanced Expression of the Type II Transforming Growth Factor β Receptor in Human Pancreatic Cancer Cells without Alteration of Type III Receptor Expression¹

We have recently found that human pancreatic adenocarcinomas exhibit strong immunostaining for the three mammalian transforming growth factor β (TGF-β) isoforms. These important growth-regulating polypeptides bind to a number of proteins, including the type I TGF-β receptor (TβR-I), type II TGF-β receptor (TβR-II), and the type III TGF-β receptor (TβR-III). In the present study we sought to determine whether TβR-II and TβR-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 TβR-II. In contrast, mRNA levels encoding TβR-III were not increased. In situ hybridization showed that TβR-II mRNA was expressed in the majority of cancer cells, whereas mRNA grains encoding TβR-III were detectable in only a few cancer cells and were present mainly in the surrounding stroma. These findings suggest that enhanced levels of TβR-II may have a role in regulating human pancreatic cancer cell growth, while TβR-III may function in the extracellular matrix.