Wisteria floribunda agglutinin positive glycobiomarkers: a unique lectin as a serum biomarker probe in various diseases.

INTRODUCTION: Serum proteins are generally glycosylated and solubilized, and are thus present as glycoproteins. The glycan structure of glycoproteins reflects cell differentiation status; glycan structures generated by diseased cells are distinguishable from those produced by healthy cells. Proteins may therefore serve as markers of tissues that secrete them. Several strategies for the identification of novel serum biomarkers using a combination of glycoscience-based technologies have been recently proposed. The selection of lectins for use as probes for identification of altered glycan structures represents a critical step. Areas covered: This review describes the identification of Wisteria floribunda agglutinin (WFA) as a probe that recognizes the altered glycan structure of glycoproteins secreted by diseased cells. WFA may be employed as a probe for several diseases, e.g., liver fibrosis, liver cirrhosis, prostate cancer, ovarian cancer, and IgA nephropathy. The advantage of employing WFA as a serum biomarker probe is that only very small amounts of WFA-positive glycoproteins are present in serum; therefore, WFA background in serum is very low. Expert commentary: Based on the findings to date, several WFA-positive serum biomarkers may be measured without pre-purification of target glycoproteins, indicating their utility as serum biomarkers in patients with various diseases.

G2/M cell cycle arrest by an N-acetyl-D-glucosamine specific lectin from Psathyrella asperospora.

A new N-acetyl-D-glucosamine (GlcNAc) specific lectin was identified and purified from the fruiting body of the Australian indigenous mushroom Psathyrella asperospora. The functional lectin, named PAL, showed hemagglutination activity against neuraminidase treated rabbit and human blood types A, B and O, and exhibited high binding specificity towards GlcNAc, as well as mucin and fetuin, but not against asialofetuin. PAL purified to homogeneity by a combination of ammonium sulfate precipitation, chitin affinity chromatography and size exclusion chromatography, was monomeric with a molecular mass of 41.8 kDa, was stable at temperatures up to 55 °C and between pH 6-10, and did not require divalent cations for optimal activity. De novo sequencing of PAL using LC-MS/MS, identified 10 tryptic peptides that revealed substantial sequence similarity to the GlcNAc recognizing lectins from Psathyrella velutina (PVL) and Agrocybe aegerita (AAL-II) in both the carbohydrate binding and calcium binding sites. Significantly, PAL was also found to exert a potent anti-proliferative effect on HT29 cells (IC50 0.48 µM) that was approximately 3-fold greater than that observed on VERO cells; a difference found to be due to the differential expression of cell surface GlcNAc on HT29 and VERO cells. Further characterization of this activity using propidium iodine staining revealed that PAL induced cell cycle arrest at G2/M phase in a manner dependent on its ability to bind GlcNAc.

Wisteria floribunda agglutinin-positive mucin 1 is a sensitive biliary marker for human cholangiocarcinoma.

UNLABELLED: Cholangiocarcinoma (CC) is an aggressive malignant tumor for which useful markers are not presently available for early and precise diagnosis. The aim of this study was therefore to identify a high-performance diagnostic marker with a special focus on glyco-alteration of glycoproteins. In the course of study, we found that Wisteria floribunda agglutinin (WFA) is the best probe to differentiate intrahepatic cholangiocarcinoma (ICC) lesions from normal bile duct epithelia (BDE) (P < 0.0001). The subsequent histochemical study confirmed ICC-specific WFA staining on 165 tissue specimens. On the other hand, the WFA staining was shown to be closely associated with that of MY.1E12 established previously against sialylated mucin 1 (MUC1) by double-staining experiments. Moreover, glyco-alteration of MUC1 could be verified by western blotting of WFA-captured bile samples from patients with CC patients. Thus, we attempted to construct an enzyme-linked immunosorbent assay system for more convenient CC diagnosis, where WFA-coated plates, the specific monoclonal antibody MY.1E12, and the bile specimens from CC including ICC (n = 30) and benign diseases (n = 38) were combined. As a result, CC was clearly distinguished from benign diseases with statistical scores (sensitivity = 90.0%, specificity = 76.3%, and area under the curve = 0.85). As a particular note, the obtained sensitivity is the highest score among those having been so far reported. CONCLUSION: Our approach focusing significant glyco-alteration of a particular glycoprotein yielded a novel diagnostic system for CC with satisfactory clinical scores.

Surface expression of heterogeneous nuclear RNA binding protein M4 on Kupffer cell relates to its function as a carcinoembryonic antigen receptor.

Elevated concentrations of carcinoembryonic antigen (CEA) in the blood are associated with the development of hepatic metastases from colorectal cancers. Clearance of circulating CEA occurs through endocytosis by liver macrophages, Kupffer cells. Previously we identified heterogeneous nuclear ribonucleoproteins M4 (hnRNP M4) as a receptor (CEAR) for CEA. HnRNP M4 has two isoform proteins (p80, p76), the full-length hnRNP M4 (CEARL) and a truncated form (CEARS) with a deletion of 39 amino acids between RNA binding domains 1 and 2, generated by alternative splicing. The present study was undertaken to clarify any isoform-specific differences in terms of their function as CEA receptor and localization. We develop anti-CEAR isoform-specific antibodies and show that both CEAR splicing isoforms are expressed on the surface of Kupffer cells and can function as CEA receptor. Alternatively, in P388D1 macrophages CEARS protein has nuclear and CEARL has cytoplasmic localization. In MIP101 colon cancer and HeLa cells the CEARS protein is localized to the nucleus and CEARL to the cytoplasm. These findings imply that different functions are assigned to CEAR isoforms depending on the cell type. The search of 39 amino acids deleted region against the Prosite data base revealed the presence of N-myristylation signal PGGPGMITIP that may be involved in protein targeting to the plasma membrane. Overall, this report demonstrates that the cellular distribution, level of expression, and relative amount of CEARL and CEARS isoforms determine specificity for CEA binding and the expression of alternative spliced forms of CEAR is regulated in a tissue-specific manner.