Gene transfection-mediated overexpression of β1,4-N-acetylglucosamine bisecting oligosaccharides in glioma cell line U373 MG inhibits epidermal growth factor receptor function

N-linked oligosaccharides appear to be important for the function of the epidermal growth factor (EGF) receptor. In a previous study (Rebbaa, A., Yamamoto, H., Moskal, J. R., and Bremer, E. G. (1996) J. Neurochem. 67, 2265- 2272), we showed that binding of the erythroagglutinating phytohemagglutin lectin from Phaseolus vulgaris to the bisecting structures on the EGF receptor from U373 MG glioma cells blocked EGF binding and receptor autophosphorylation. In this study we examined the consequences of overexpression of the bisecting structure on the EGF receptor by gene transfection of U373 MG cells with the N-acetylglucosaminyltransferase III (GnT-III). This modification leads to a significant decrease in EGF binding and EGF receptor autophosphorylation. In addition, the cellular response to EGF was found to be altered. Proliferation of U373 MG cells in serum-free medium is inhibited by EGF. In contrast, proliferation of the GnT-III- transfected cells was stimulated by EGF. These data demonstrate that changes in EGF receptor glycosylation by GnT-III transfection reduces the number of the active receptors in U373 MG cells and that this change results in change in the cellular response to EGF.