Glycomic analysis of alpha-fetoprotein L3 in hepatoma cell lines and hepatocellular carcinoma patients

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2007-2008

This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.

Development of an antibody-lectin enzyme immunoassay for fucosylated α-fetoprotein

BACKGROUND

Fucosylation is one of the most important types of glycosylations related to cancer. Our previous studies of the enzymatic basis and structural studies of α-fetoprotein (AFP) samples from liver cancer patients indicated that core-fucosylation by α1,6-fucosyltransferase (FUT8) resulted in the production of fucosylated AFP, and in fact fucosylated AFP allowed differential diagnosis in some types of liver cancer from liver cirrhosis. This served as a predictive biomarker for the development of liver cancer 3 to 18 months before it could be detected using imaging techniques. Fucosylated AFP is currently measured by means of a liquid-phase binding assay (LBA) or by an electrokinetic analyte transport assay (EATA). However, these methods require special instrumentation that is currently available only in major medical laboratories. To overcome this problem, we attempted to develop an enzyme immunoassay (EIA) based on the sandwich technique with specific antibody and lectin.

RESULTS

Dilute solutions of highly fucosylated AFP in human sera were assayed using a microtiter plate coated with a periodate-oxidized anti-AFP antibody, a fucose-specific biotinylated Aleuria aurantia lectin (AAL), a peroxidase-conjugated streptoavidin, and a chemiluminescent detection system. The technique was able to measure highly fucosylated AFP diluted to 5 to 80ng/ml in human sera using the developed antibody-lectin EIA in combination with the enrichment of AFP.

CONCLUSION

A simple method using an antibody-lectin EIA for quantifying fucosylated AFP that does not require special instrumentation was developed.

GENERAL SIGNIFICANCE

The method can be generally applied to the quantitative measurement of various fucosylated glycoproteins using specific antibodies. This article is part of a Special Issue entitled Glycoproteomics.

Evaluation of revisited fucosylated alpha-fetoprotein (AFP-L3) with an autoanalyzer μTAS in a clinical laboratory

BACKGROUND

We assessed clinical and analytical performances of AFP and fucosylated AFP (AFP-L3) assays by a newly developed automated analyzer based on liquid-phase binding (micro-total analysis systems, μTAS).

METHODS

A total of 239 serum samples were obtained from 120 patients with hepatocellular carcinoma (HCC) and 119 without HCC. Precision of assays by the μTAS was evaluated, and the correlation between AFP-L3 and AFP levels was analyzed. Receiver operating characteristics curve-area under the curve (ROC-AUC) value was calculated to measure the diagnostic performance.

RESULTS

Imprecision for AFP (ng/ml), AFP-L3 (ng/ml), and AFP-L3 (%) with 2 levels of QC materials was all within 5% coefficient of variation. AFP levels measured by the μTAS were correlated well with those by the UniCel DxI 800 Access (r=0.83). AFP-L3 concentrations in HCC patients were higher than those in control group (median 379.2 ng/ml in HCC, 1.0 ng/ml in non-HCC, P<0.05). AUC of AFP-L3 was 0.91 which was significantly higher than that of AFP (0.88 by μTAS; 0.84 by UniCel DxI 800, P<0.05 for both).

CONCLUSION

AFP-L3 in HCC was significantly higher than that of control group. The μTAS showed good performances for routine uses in clinical laboratories for measuring AFP and AFP-L3.

Development of recombinant Aleuria aurantia lectins with altered binding specificities to fucosylated glycans

Changes in glycosylation have long been associated with disease. While there are many methods to detect changes in glycosylation, plant derived lectins are often used to determine changes on specific proteins or molecules of interest. One change in glycosylation that has been observed by us and by others is a disease or antigen associated increase in fucosylation on N-linked glycans. To measure this change, the fucose binding Aleuria aurantia lectin (AAL) is often utilized in plate and solution based assays. AAL is a mushroom derived lectin that contains five fucose binding sites that preferentially bind fucose linked (α-1,3, α-1,2, α-,4, and α-1,6) to N-acetyllactosamine related structures. Recently, several reports by us and by others have indicated that specific fucose linkages found on certain serum biomarker glycoprotein's are more associated with disease than others. Taking a site-directed mutagenesis approach, we have created a set of recombinant AAL proteins that display altered binding affinities to different analytes containing various fucose linkages.

Cancer detection using nanoparticle-based sensors

This tutorial review surveys the latest achievements in the use of nanoparticles to detect cancer biomarkers and cancer cells with a focus on optical and electrochemical techniques. Nanoparticle based cancer diagnostics are becoming an increasingly relevant alternative to traditional techniques. Although some drawbacks exist in relation to the obtained sensitivity the use of nanoparticle-based sensors in biomarker detection or cancer cell detection offers some advantages in comparison to conventional methods. The developed techniques can be interesting and relevant for their use in point-of-care of cancer diagnostics. The methods can be of low cost and in addition easy to be incorporated into user-friendly sensing platforms.

N-linked glycan changes of serum haptoglobin β chain in liver disease patients

Human haptoglobin is a serum glycoprotein secreted by the liver with four potential N-glycosylation sites on its β chain. Many studies have reported glycan changes of haptoglobin in diseases such as breast cancer and pancreatic cancer. The objective of our study is to analyze N-linked glycan alterations of serum haptoglobin β chain obtained from patients with the hepatitis B virus (HBV), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). MALDI-QIT-TOF mass spectrometry revealed the intensity of m/z 1809.6, identified as a fucosylated glycan, was much higher in samples from patients with LC and HCC relative to the patients with HBV and healthy controls. Compared with LC patients, triantennary glycan was elevated and the biantennary structure was decreased in the haptoglobin β chain of HCC patients. Thus, alterations in the glycan structure of the haptoglobin β chain may constitute significant spectral signatures of cirrhosis and HCC disease.

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

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.

Development of a competitive radioimmunoassay for glypican-3 and the clinical application in diagnosis of hepatocellular carcinoma

OBJECTIVE

Glypican-3 (GPC3) is a promising specific tumor maker for hepatocellular carcinoma (HCC). The aim of this study is to establish a method to detect serum GPC3 and evaluate the clinical application on clinical diagnosis.

DESIGN AND METHODS

A competitive radioimmunoassay for detecting serum GPC3 was developed. Clinical sera were detected by the proposed method and AFP, CA19-9 chemiluminescence immunoassay kit.

RESULTS

The proposed method with high sensitivity, specificity and precision had no or little detectable cross-reactivity with relating tumor markers in the dynamic range from 15 to 500 ng/mL, and the detection limit was 0.5 ng/mL. The level of GPC3 in HCC was obviously higher than that in normal liver or other liver diseases. Additionally, our method showed high shows higher sensitivity and specificity for GPC3 than AFP and combined AFP/CA19-9.

CONCLUSIONS

This paper provided an applicable competitive radioimmunoassay for GPC3 with high sensitivity, specificity and precision. In addition, using GPC3 for HCC diagnosis was more valuable than AFP.

Identification of candidate biomarkers with cancer-specific glycosylation in the tissue and serum of endometrioid ovarian cancer patients by glycoproteomic analysis

Epithelial ovarian cancer is diagnosed less than 25% of the time when the cancer is confined to the ovary, leading to 5-year survival rates of less than 30%. Therefore, there is an urgent need for early diagnostics for ovarian cancer. Our study using glycotranscriptome comparative analysis of endometrioid ovarian cancer tissue and normal ovarian tissue led to the identification of distinct differences in the transcripts of a restricted set of glycosyltransferases involved in N-linked glycosylation. Utilizing lectins that bind to glycan structures predicted to show changes, we observed differences in lectin-bound glycoproteins consistent with some of the transcript differences. In this study, we have extended our observations by the use of selected lectins to perform a targeted glycoproteomic analysis of ovarian cancer and normal ovarian tissues. Our results have identified several glycoproteins that display tumor-specific glycosylation changes. We have verified these glycosylation changes on glycoproteins from tissue using immunoprecipitation followed by lectin blot detection. The glycoproteins that were verified were then analyzed further using existing microarray data obtained from benign ovarian adenomas, borderline ovarian adenocarcinomas, and malignant ovarian adenocarcinomas. The verified glycoproteins found to be expressed above control levels in the microarray data sets were then screened for tumor-specific glycan modifications in serum from ovarian cancer patients. Results obtained from two of these glycoprotein markers, periostin and thrombospondin, have confirmed that tumor-specific glycan changes can be used to distinguish ovarian cancer patient serum from normal serum.

Comparative analysis of core-fucose-binding lectins from Lens culinaris and Pisum sativum using frontal affinity chromatography

Lens culinaris lectin (LCA) is a useful probe for the detection in serum of a core-fucosylated alpha-fetoprotein, called AFP-L3 fraction, which is a well-known marker for the diagnosis and prognosis of hepatocellular carcinoma. Here we performed a systematic quantitative interaction analysis of LCA and its close homolog, Pisum sativum lectin (PSA), by frontal affinity chromatography with 143 pyridylaminated (PA) glycans including a series of core-fucosylated glycans. Both lectins showed binding affinity to core-fucosylated, mono- and bi-antennary N-glycans, but not to their tri- and tetra-antennary forms, indicating that the addition of the GlcNAc residue at the N-acetylglucosaminyltransferase IV position abrogates the binding affinity. However, their specificities are distinguishable: while LCA showed the highest affinity to the core-fucosylated, agalactosylated, bi-antennary N-glycan (K(a)=1.1 x 10(5) M(-1)), PSA showed the highest affinity to the core-fucosylated, trimannosyl structure (K(a)=1.2 x 10(5) M(-1)). Glycan-binding specificities of LCA and PSA were also analyzed by glycoconjugate microarray compared to other core-fucose-binding lectins from Aspergillus oryzae (AOL) and Aleuria auratia (AAL). LCA and PSA bound specifically to core fucose, whereas AOL and AAL exhibited broad specificity to fucosylated glycans. These results explain why LCA is appropriate as a specific probe for AFP-L3, which mainly contains a core-fucosylated, biantennary N-glycan, but not its highly branched forms.

Glycoproteomics of plasma based on narrow selectivity lectin affinity chromatography

Lectin affinity chromatography using concanavalin A (Con A), Helix pomatia agglutinin (HPA), Lycopersicon esculentum lectin (LEL), Aleuria aurantia lectin (AAL) and Lens culinaris agglutinin (LCA) was used to investigate the utility of narrow selectivity lectins in the characterization of plasma glycoproteome diversity and to recognize cancer associated aberrations in glycosylation. Following affinity chromatographic selection, proteins were tryptically digested, the peptide fragments separated by reversed phase chromatography (RPC), and fractions from RPC identified by tandem mass spectrometry. The diversity of glycosylation found with narrow selectivity lectins was generally 2/3 that of Con A and not related to protein abundance. Small groups of proteins were found with each of the affinity columns, HPA, LEL, AAL, and LCA, that changed 3-fold or more in concentration between normal and breast cancer patient plasma. Although the number of cancer patients examined was too small to validate cancer marker candidates, they are clearly worth examining in a larger, more diverse patient population.

Alteration of glycan structure in liver cancer

Glycosylation is a common post-translational protein modification, and almost half of all proteins have been estimated to be glycosylated. Protein glycosylation produces lots of glycans and altered glycan structures are associated with physiological and pathological process, including malignant transformation and invasion. This review describes the structure and function of glycans and highlights changes in glycan structure associated with liver cancer.