Fucosyltransferase (FT) is considered to be one of the most important
glycosyltransferases responsible for the synthesis of
cancer-associated
carbohydrate chains such as CA19-9 and SLX. To determine whether FT is a sensitive
tumor marker, we measured the
enzyme activity of FT in sera from 136
cancer patients, 14 patients with benign diseases and 59 healthy controls, by using PA (pyridylamino)-labeled type II biantennary
oligosaccharide derived from human
serotransferrin as an acceptor substrate. Serum FT activity was significantly elevated in patients with
cancer compared to healthy controls. Analysis of the
enzyme products using HPLC and various fucosidases with different specificity revealed that alpha 1----
3 FT was responsible for most of the elevation of the
enzyme activity in sera from
cancer patients. It should be stressed that the alpha 1----3FT derived from
cancer patients transferred
fucose to terminal
lactosamine residues of type II biantennary
oligosaccharides already attached to
sialic acid. This indicates that the substrate specificity is clearly different from that reported in normal sera and tissues. In addition to alpha 1----3FT, some
glycosidases including
fucosidase were also elevated in sera from
cancer patients.