Localization of endogenous sugar-binding proteins (lectins) in tumors of the central and peripheral nervous system by biotinylated neoglycoproteins

Abstract

The carbohydrate part of cellular glycoconjugates - glycoproteins, glycoproteins, glycolipids and proteoglycans - and specific endogenous sugar receptors, i.e. lectins, can establish a system of biological recognition based on protein-sugar interactions on the cellular and subcellular levels. To gain insight into the role of proteins in this type of interaction, sections of surgically removed tumor specimens of central and peripheral nervous tissue were analyzed glycohistochemically, using biotinylated neoglycoproteins with different sugar part. A specific staining with this type of probe, exposing different sugar moieties as ligands, indicated the presence of sugar receptors in different types of meningiomas, glioblastomas, gangliocytomas, anaplastic and well-differentiated oligodendrogliomas and ependymomas as well as in neurinomas and neurofibromas of peripheral nerves. In comparison to the well-differentiated ependymomas, the anaplastic form of this tumor exhibited a generally higher capacity to specifically bind the neoglycoproteins, containing alpha- or beta-glucosides. Inverse intensity of the glycohistochemical reaction was observed with galactose-6-phosphate-, galactose-beta(1.3)-N-acetylglucosamine-N-acetyl-D-glucosamine- and mannose- (BSA- biotin), respectively, when anaplastic and differentiated oligodendrogliomas were compared with each other. Tumorously dedifferentiated neurons, i.e. in gangliocytomas, showed a changed spectrum of endogenous sugar receptors in comparison to neurons of normal cerebral cortex. Qualitative and quantitative differences of sugar receptors were observed among the distinct subtypes of meningiomas. Receptors for N-acetyl-D-galactosamine were present only in the anaplastic form, while glucuronic acid-specific receptors were only found in the meningotheliomatous meningiomas. Distinctions in binding spectrum of neoglycoproteins suggest the presence of a possible additional subtype of meningiomas, called submalignant meningioma. Analysis of the spectrum of endogenous sugar receptors can serve to distinguish between different cell populations composing a given tumor, as shown in neurofibromas in the cases of Schwann cells and fibroblastoid cells stained with N-acetyl-D-glucosamine-(BSA-biotin). The analysis of expression of endogenous sugar receptors, as part of an intercellular information code system, may represent a further way of studying the mechanism of tumor differentiation and propagation.