Endogenous sugar receptor pattern in human glioblastomas and gangliocytomas studied by histochemical application of biotinylated (neo)glycoproteins and affinity chromatography

Abstract

Biotinylation of chemically glycosylated bovine serum albumin, yielding a panel of neoglycoproteins, and of desialylated, naturally occurring glycoproteins allowed to systematically evaluate presence and distribution of various types of endogenous sugar receptors in the sections of human glioblastomas and gangliocytomas by a routine histochemical procedure. Pronounced cytoplasmic staining with markers, carrying constituents of natural glycoconjugates, e.g. for beta-galactoside-specific receptors, contrasted with the different intensities, noticed for alpha- and beta-glucoside-specific receptors. Significant qualitative differences between the two tumor types were detected with N-acetyl-D-galactosamine- and sialic acid-carrying probes. Nuclear staining with only a part of the applied panel underscored the specificity of the protein-carbohydrate interaction. Fine structural features of the synthetic neoglycoproteins, e.g. the mode of coupling of the carbohydrate moiety to the protein, were found to exert a significant influence on their suitability as histochemical markers. On the basis of the histochemical results, exemplary biochemical analysis of certain classes of endogenous sugar receptors by affinity chromatography and subsequent gel electrophoresis, namely of beta-galactoside-, alpha-fucoside-, alpha-mannoside- and alpha-glucoside-specific proteins, revealed presence and characteristics of respective sugar receptors that can contribute to the histochemical staining. Similar extent of histochemical staining with the respective probes notwithstanding, the different tumor types exhibited qualitative differences in the expression of individual endogenous sugar receptors. The combined histochemical and biochemical analysis is supposed to be of conspicuous value for biological and clinical investigations on endogenous sugar receptors.