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.