Multiple lectin assays for detecting glyco-alteration of serum GP73 in liver diseases

Serum GP73 is a functional resident Golgi type II membrane protein with three potential N-glycosylation sites. In this study, we used multiple lectin assays to analyze glycan patterns of serum GP73 and evaluated its diagnostic value for distinguishing hepatocellular carcinoma (HCC) from liver cirrhosis (LC). Firstly, Antibody overlay lectin microarray and lectin blot were performed to observe altered glycans of GP73. Fucosylated structures were found to increase significantly in LC compared with HCC patients. Then, AAL ELISA assay using ELISA Index was utilized to measure fucosylation level of GP73 on its protein level (Fuc-GP73). ELISA Indices of 54 LC and 54 HCC patients was obtained and the area under the ROC curve (AUC) was 0.807 with a sensitivity of 85.2% and a specificity of 63.0% (cutoff of 3.182). In addition, combining Fuc-GP73 and AFP-L3 greatly improved the diagnostic accuracy (AUC = 0.953) and the diagnostic values were 94.4% sensitivity at 88.9% specificity. These data indicated that multiple lectin assays could contribute to pre-clinical evaluation of focused glycoprotein and Fuc-GP73 could act as a potential glycobiomarker complementary to AFP-L3 for discrimination of HCC from LC patients.