Ganglioside (GD2) expression and intermediary filaments in astrocytic tumors

The search of proliferation markers in astrocytic tumors that may serve as targets for therapeutic interventions, is in full progress. Membrane-bound signal transducers for growth factors are amongst the substances of interest. Gangliosides are lipid-sugar compounds localized on the cell membrane that are thought to modify pertinent signals and, therefore, may influence a variety of functions in normal and pathologic conditions including those that act upon tumor growth. Intracranial supratentorial astrocytic gliomas of the adult represent a tumor group, that may be divided into three grades of malignancy, the most anaplastic member being the glioblastoma. A stepwise anaplasia is assumed and accompanied by genetic events that are partly specific for these grades. In earlier investigations, it had been shown that there is a tendency towards formation of more simple members of the ganglioside family with ongoing malignancy of those tumors. Yet, the results were only partly congruent and the correlation to tumor grades rather loose. We, therefore, investigated the occurrence of triaose gangliosides within these tumors in situ by immunohistochemistry. In this paper, we corroborate our earlier observation that triaose gangliosides preferentially occur within the cytoplasm of large protoplasmic and gemistocytic astrocytes. The potency of the expression of GD2 is calculated and plotted against the expression of two markers of intermediate glial filaments, namely GFAP (glial fibrillary acid protein) and vimentine. A high interdependence of the three compounds could be demonstrated by correlation analysis. Thus, the conclusion must be drawn that the correlation of ganglioside patterns to the proliferation of astrocytic tumors is as poor as that of GFAP or vimentin expression, respectively.