Alteration of tumor phenotypes of B16 melanoma after genetic remodeling of the ganglioside profile.

Gangliosides have been thought to be tumor markers of various neuroectoderm-derived cancers. However, their roles in malignant phenotypes of cancer cells are not well understood. We have performed the remodeling of ganglioside profiles of mouse melanoma B16 (B78 subline) by introducing GM2/GD2 synthase cDNA, and analyzed the phenotypic changes such as cell morphology, growth, adhesion and c-fos gene expression. Although newly expressed GM2 was clearly detected, GM2-positive transfectant cells showed rather reduced growth rates in vivo and in vitro, lower expression levels of c-fos gene and increased levels of cell adhesion to extracellular matrices compared to control cells. These results suggested that GM2 is involved in the regulation of cell-cell or cell-extracellular matrix interaction, and negatively control cell proliferation.