GLYCOSYLTRANSFERASE ACTIVITIES IN HUMAN MENINGIOMAS - PRELIMINARY-RESULTS

The biosynthesis of a given glycosphingolipid is under the control of specific glycosyltransferases, while its catabolism is catalyzed by st ep-wise action of glycosidases. The net amount of glycolipids apparent ly result from the difference between these two processes. However, ot her parameters should be taken into consideration, such as intracellul ar recycling of catabolic products, membrane insertion, and membrane t urnover. In order to establish a possible correlation between ganglios ide expression in brain tumor and the activities of the enzymes involv ed in their metabolism, we analyzed the activities of specific sialylt ransferases (SAT-1 and SAT-2), galactosyltransferase (GalT-4), N-acety lgalactosaminyltransferase (GalNAcT-1), and N-acetylglucosaminyltransf erase (GlcNAcT-1) in 9 human meningiomas whose ganglioside pattern was characterized either by the predominance ganglioside GM(3) (4 out of 9) or ganglioside GD(3) (5 out of 9). The results indicated a strong c orrelation between the GM(3)/GD(3) ratio and SAT-2 activity; to the co ntrary, SAT-1 activity did not show any correlation if compared with t he Lc(2)/GM(3) ratio. Tu all the samples where GMB was the main gangli oside, little or no activity of GalNAcT-1 and GlcNAcT-1 was detectable .