Previous immuno- and
lectin-histochemical studies using mAbs and Ulex europaeus
lectin I, which recognize various
fucose-containing
blood group antigens, have shown an increased expression of Lewis and
H blood group antigens in
endometrial carcinoma. We investigated the biochemical basis of aberrant
fucose-containing
antigen expression by comparing the activity of
fucosyltransferases (FTase) and
alpha-L-fucosidase in tissue biopsies from normal (n = 18) and malignant (n = 20) endometrium. Alteration of FTase activity in
tumor tissue homogenates was evaluated by using a panel of FTase substrates including
N-acetyllactosamine (type 2),
lacto-N-biose I (type 1), and phenyl-beta-D-galactoside. Based on histological subtyping, the endometrioid group (n = 14) showed a significant (P < 0.05) increase in
tumor FTase activity with all three substrates, while no significant increase was detected for the papillary serous group (n = 4). Matched pair analysis of normal and
tumor tissue from a subgroup (n = 5) of the patients with increased
tumor enzyme activity also showed higher FTase activity (P < 0.05) in the
tumor tissue when the type 1 substrate was used. Regression analysis showed a correlation between the FTase activities acting on type 2 or type 1 substrates (r = 0.821 and r = 0.722, respectively) and the endogenous
fucose levels in
tumor homogenates. Spectrophotometric analysis of
alpha-L-fucosidase activity using p-nitrophenyl-alpha-L-fucoside revealed a higher activity in
tumor homogenates than in normal homogenates (P < 0.05) and, therefore, could not account for the enhanced expression of
fucose-containing
antigens. The current study suggests that aberrant expression of
fucose-containing
antigens, such as the H and the
Lewis blood-group antigens, in
endometrial carcinoma is consequential to the change in FTase rather than in
alpha-L-fucosidase activity. In addition, the investigation suggests that different glycosylation mechanisms are operative in different subtypes of
endometrial cancer.