MAPPING OF RECEPTORS FOR CARBOHYDRATE CONSTITUENTS OF GLYCOCONJUGATES IN WELL–DIFFERENTIATED AND MALIGNANT EPENDYMOMAS: A GLYCOHISTOCHEMICAL STUDY

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Abstract
Recognitive interactions between the carbohydrate of part of cellular glycoconjugates and endogeneous receptors supposedly govern important biological processes. Consequently, their elucidation can be of considerable value in tumor diagnosis. The histochemical patterns of expression of endogenous sugar receptors (e.g. endogenous lectin-like proteins) of 10 cases of well-differentiated ependymoma and 10 cases of malignant ependymoma were analysed, using a panel of 18 biotinylated (neo)glycoproteins and a standardized staining protocol. Within this panel, differences in the extent of staining for intracellular sugar receptors in well-differentiated and malignant ependymomas were histochemically detectable. In comparison to the well-differentiated ependymomas, the anaplastic form of the tumor exhibited a generally higher capacity to specifically bind labelled (neo)glycoproteins, containing .alpha.- or .beta.-glucosides and adisaccharide, characteristic for one type of .beta.-galactoside-terminated chain structure of glycoproteins. A significantly reduced binding was seen for tumors of the anaplstic type with labelled markers, carrying histochemically indispensable glucuronic acid residues. These findings suggest that labelled neoglycoproteins are a valuable tool for assessing the endogenous sugar-binding capacity in diagnositc histopathology. Our descriptive analysisof endogenous sugar receptors may also be a rational basis for studies on the functional significance of changes in the expression of their endogenous ligands and the cellular glycoconjugates. Further investigations are also possible on the correlation between the degree of differentiation and expression of both parts of a recognitive system, based on protein (receptor)-carbohydrate (ligand) interactions, in tumours of the central nervous system, especially ependymomas.