Augmentation of UDP-GalNAc:: Fucα1-2Gal α1-3 N-acetylgalactosaminyl transferase activity in nitrosamine-induced hamster pancreatic cancers

Pancreatic cancers induced by N-nitrosobis(2-oxopropyl)amine (BOP) in hamsters produce blood group-A antigen (BG-A Ag), which is not present in the normal pancreas. To understand the neo-expression mechanism of BG-A Ag, we examined uridine diphosphate (UDP)-N-acetylgalactosamine (GalNAc): fucose (Fuc) alpha 1-2 galactose (Gal) alpha 1-3 GalNAc transferase (alpha 1-3 GalNAc Tf) activity, the enzyme responsible for BG-A production. The specific activity of alpha 1-3 GalNAc Tf in pancreatic cancers was similar to 8,000 nmole/g protein/h, whereas it was absent from the normal pancreas. Although the antrum and colon express A-Tf and BG-A Ag, the divalent cation requirements of alpha 1-3 GalNAc Tf in these tissues were different from those of cancers. These results suggest that alpha 1-3 GalNAc Tf is activated during BOP-induced pancreatic carcinogenesis, and that there are multiple alpha 1-3 GalNAc Tf isozymes present in hamster tissues.