N-glycosylation status of purified beta-
haptoglobin from sera of 17 patients, and from sera of 14 healthy volunteer subjects, was compared by blotting with various
lectins and
antibodies. Patients in this study were diagnosed as having
colon cancer through histological examination of each
tumor tissue by biopsy. Blotting index of serum beta-
haptoglobin with
Aleuria aurantia lectin (AAL) was clearly higher for
cancer patients than for healthy subjects. No such distinction was observed for blotting with three other
lectins and two
monoclonal antibodies. To determine
tumor-associated reactivity of AAL binding as compared to inflammatory processes in colonic tissues, beta-
haptoglobin separated from sera of 5 patients with
Crohn's disease (CD), and 4 patients with
ulcerative colitis (UC), was studied. All these cases, except one case of UC, showed AAL index lower than that in
cancer cases, similarly to healthy subjects. The higher AAL binding of beta-
haptoglobin in
colon cancer patients than in healthy subjects appeared to be due to alpha-L-fucosyl residue, since it was eliminated by bovine kidney
alpha-fucosidase treatment. N-linked
glycans of serum
haptoglobin from
colon cancer patients vs. healthy subjects were released by
N-glycanase, fluorescence-labeled, and subjected to normal-phase high performance liquid chromatography (NP-HPLC).
Glycan structures were determined based on
glucose unit (GU) values and their changes upon sequential treatment with various
exoglycosidases. Glycosyl sequences and their branching status of
glycans from 14 cases of serum beta-
haptoglobin were characterized. The identified
glycans were sialylated or nonsialylated, bi-antennary or tri-antennary structures, with or without terminal fucosylation.