Glycolipid markers of astrocytomas and oligodendrogliomas

Neutral glycolipids and gangliosides were analyzed in 149 astrocytomas (A), 46 oligodendrogliomas (O), and 21 oligoastrocytomas (OA) to determine if specific glycolipids correlate with histologic diagnosis and grade. Positivity for asialoGM1 (GA1) and negativity for paragloboside by immuno-TLC correlated with histological diagnosis of O and OA, whereas the reverse pattern correlated with A. High levels (over 5 microg hexose per mg dry weight) of CMH generally correlated with an O component, but the association was not as strong as for either GA1 presence or paragloboside absence. Pilocytic astrocytomas and pleomorphic xanthoastrocytomas had high proportions (> 15%) of globoside, low ratios (< 0.5) of GD1a: GD1b, and identifiable ceramide trihexoside (CTH). Three gangliosides of the 1b pathway were progressively lost with increasing grade of A, but a similar correlation with grade was not seen in O or OA. A high proportion of cases expressing sialosylparagloboside (3'LM1; 6'LM1) were grade 4 A. Glycolipids are synthesized by glycosyltransferases that add specific sugars to the nascent oligosaccharide. Correlation of specific glycolipids with histological diagnoses and grades indicate that these tumor types express specific patterns of glycosyltransferases, several of which have been cloned. It is possible that critical genes coding for these enzymes are deleted, overexpressed, or mutated in certain tumor types and grades, thus leading to the patterns of glycolipids that we found to be associated with these tumors.