α1‐3/4 fucosylation at Asn 241 of β‐haptoglobin is a novel marker for colon cancer: A combinatorial approach for development of glycan biomarkers

TLDR

Aberrant glycosylation is observed in many cancers, yet the mechanisms underlying these changes remain poorly understood. The study aimed to elucidate how β‑haptoglobin glycosylation relates to colon cancer progression by analyzing samples from patients and controls. β‑Haptoglobin glycosylation was characterized using lectin blotting, microarray assays with fucose‑specific lectins, and sequential LC/MS to determine site‑specific occupancy. Aleuria aurantia lectin reactivity was higher in cancer β‑Hp, correlated with cancer stage, and the α1‑3/4 fucose epitope at Asn241 was markedly increased and eliminated by α1‑3/4 fucosidase, indicating its potential as a novel colon cancer marker.

Abstract

Aberrant glycosylation has been observed in many types of cancer, but the mechanism of glycosylation change is still poorly understood. To elucidate relationships between glycosylation and colon cancer progression, we analyzed glycosylation status of β-haptoglobin (β-Hp) obtained from 46 cancer patients, 14 inflammatory bowel disease patients and 38 normal subjects. Aleuria aurantia lectin reactivity with cancer β-Hp was much higher than in the other two study groups. These results were confirmed by lectin blotting and microarray assay using other lectins directed to fucosyl residues. Levels of such glycans were correlated with stage of colon cancer progression. Reactivity with fucosylated glycans was eliminated by treatment with α1-3/4 fucosidase but not α1-6 fucosidase, indicating that enhanced lectin reactivity with the fucose moiety of colon cancer β-Hp is due to Fucα1-3/4GlcNAc. Moreover, site-specific glycan occupancy was determined by sequential LC/MS analysis. Mass spectrometric analysis showed that fucosylation of β-Hp was higher in colon cancer patients than in other subjects. In particular, fucosylation at Asn 241 of β-Hp in sera of colon cancer patients was clearly higher than in the other groups, and the ratio of fucosylated glycopeptides containing Asn 241 decreased greatly after treatment with α1-3/4 fucosidase. In conclusion, the level of α1-3/4 fucosyl epitope at Asn 241 of β-Hp is potentially useful as a novel marker for colon cancer.