Alteration of ganglioside composition by stable transfection with antisense vectors against GD3-synthase gene expression

Gangliosides are ubiquitous components of mammalian cells. Their expression is frequently altered in many tumor types. We previously showed that alter ation of the ganglioside composition often resulted in changes in cellular morphology and differentiation of cultured cells. In this study, we targete d sialyltransferase gene expression by the antisense knockdown experiment, and the results showed that inhibition of the expression of gangliosides GD 3 and O-acetylated GD3 (OAc-GD3) in the neuroblastoma F-11 cells greatly re duced the tumor growth in nude mice. The sense and antisense vectors contai ning either a 5' end fragment or the entire sequence of the cDNA coding for GD3-synthase were prepared and used in separate experiments to transfect t he F-11 cells which express high levels of gangliosides GD3 and OAc-GD3, Si ngle clones were isolated and expanded. Both the activity of the GD3-syntha se and the concentrations of GD3 and OAc-GD3 in the antisense-transfected c ells were dramatically decreased as a result of transfection with the antis ense expression vectors. Further characterization of the antisense-transfec ted cells showed reduced rates of cell growth and neurite formation and cha nges in cellular morphology. When the cells were inoculated in athymic nude mice, the tumor growth rate was remarkably suppressed although the tumor i ncidence was not affected by the altered ganglioside composition. These res ults indicate that the tumor-associated ganglioside(s) is(are) involved in regulation of tumor growth, probably through the stimulation of angiogenesi s of the tumor.