Relationship of aberrant glycosylation of n-glycan on immunoglobulins with survival of patients with renal cell carcinoma.

Abstract

438 Background: Biomarkers for early detection and prediction of patient survival for renal cell carcinoma (RCC) have not yet been established. We have developed a novel glycoblotting method that allows high-throughput, comprehensive, and quantitative glycan analysis of whole human serum. We examined the relationship between serum N-glycan profiling and survival of the patient with RCC. Furthermore, we attempted to identify carrier protein to which the responsible N-glycan attached. Methods: We performed a comprehensive N-glycan structural analysis of sera from 64 patients with RCC using the glycoblotting methods and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The intensity of the N-glycans was then analyzed with the help of the logistic regression analysis and a receiver operating characteristic curve to select N-glycans which associated with patient survival in RCC. The candidate N-glycans which had statistically significant relationship in overall survival were evaluated their independency using Cox-regression model to elucidate its superiority comparing to other conventional biomarkers of RCC. Then, we recovered the responsible N-glycan together with its carrier protein by sialobloting method to identify the carrier protein. Results: We identified 56 kinds of N-glycans in sera from RCC patients. The intensity of peak 19 was significantly higher, and the intensity of peak 49 was significantly lower in the patients who survived longer. Multivariate analysis revealed that peaks 19 and 49 were independent predictors of overall survival as well as conventional risk factors. Protein analysis for the carrier protein revealed that the aberrant N-glycan was harbored by IgA1 or IgG4. Conclusions: Aberrant glycosylation of N-glycan on IgA1 or IgG4 may serve as novel biomarkers for RCC. Further validation study is warranted.