Differential regulation of glycosphingolipid biosynthesis in phenotypically distinct Burkitt's lymphoma cell lines.

Abstract

Earlier studies have shown that Burkitt's lymphoma (BL) cell lines can be divided into 2 major groups: group I, which retain the original BL biopsy phenotype with expression of CD10 and CD77 antigens and lack of B-cell activation markers, and group III, which, after several in vitro passages, progress toward an "LCL-Like" phenotype with loss of CD10 and C77 expression and up-regulation of B-cell activation antigens. In previous studies we have shown that several glycolipid molecules constitute stage-specific antigens for B cells and that sequential shifts in the 3 major glycolipid series are observed during B-cell differentiation, these changes being mostly due to sequential activations of the corresponding glycosyltransferases. In the present work, 10 BL cell lines with group I or group III phenotype have been examined for cell surface expression of 5 glycolipid antigens (LacCer, GM3, Gb3/CD77, Gb4 and GM2), total glycolipid content and enzymatic activities of 4 glycosyltransferases (GM3, Gb3, Gb4 and GM2 synthetases). We now report that group I and group III BL cells differ in their glycolipid metabolism and express either mostly globoseries or ganglioseries compounds. Indeed, Gb3 is the major glycolipid of group I cells, whereas GM3 and GM2 are the 2 major components of group III cells, and these phenotypic differences are mainly due to differential activities of the corresponding glycosyltransferases: group I cells have high Gb3 synthetase activities and low or no GM3 and GM2 synthetase activities, whereas group III cells have high GM3 and GM2 synthetase activities and low Gb3 synthetase activities. Finally, we also show that, unlike LCL, group III BL cells do not synthesize Gb4.