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.
Supported by USPHS Grant CA40162 awarded by the National Cancer Institute to M. K. and by an award from the Cancer Research Coordinating Committee of the University of California to M. K. and R. L. B. R. L. B. is the recipient of a Bank of America-Giannini Medical Research Fellowship.