Establishment of a novel lectin–antibody ELISA system to determine core-fucosylated haptoglobin

Background Fucosylated haptoglobin (Fuc-Hpt) is a novel cancer biomarker that increases in various pathological conditions. We previously established a Fuc-Hpt lectin–antibody assay using Aleuria aurantia lectin (AAL), and applied this to diagnose several diseases, including various cancers. AAL recognizes both α1-3/1-4 and α1-6 fucosylation on N/O-linked glycans. These fucosylation types differ in biological function, and in regulation by different fucosyltransferases. Recently, we identified a novel lectin, Pholiota squarrosa lectin (PhoSL), which specifically recognizes α1-6 fucosylation (core-fucosylation). Methods We developed a lectin–antibody ELISA kit using PhoSL to determine core-Fuc-Hpt levels in sera from colorectal or pancreatic cancer patients. Results Serum levels of AAL-reactive Hpt are higher in pancreatic cancer patients, whereas those of PhoSL-reactive Hpt are higher in colorectal cancer patients. Mass spectrometry analyses of Hpt fucosylation levels were consistent with lectin–antibody ELISA results. Hpt-transfected colorectal cancer cell lines produced significant amounts of core-Fuc-Hpt, suggesting that colorectal cancer tissues produce core-Fuc-Hpt. Conclusions These differences in Fuc-Hpt patterns might depend on cancer cells and the surrounding cells, which produce Hpt.