We previously established a rat F-11 cell line whose expression of ganglioside GD3 was inhibited by stable transfection of the anti-sense vector against the GD3-synthase gene, showing that specific inhibition of GD3-synthase expression in tumor cells greatly reduced their growth rate in nude mice. Here, we report that down-regulation of GD3-synthase expression in anti-sense-transfected F-11 cells correlates with reduced cell migration and invasion in vitro and tumor growth and metastasis in vivo. When cultures were denuded of cells in a 1-mm-wide strip, the anti-sense-transfected F-11 cells migrated very slowly into the denuded area. Differences in migration between anti-sense-transfected cells and control parental cells were easily apparent. In vitro invasion assay of F-11 cells revealed a 3-fold decrease in invasion ability from the GD3-synthase-suppressed cells; colony formation in soft agar was not affected. Injection (i.v.) of control sense-transfected and untransfected F-11 cells resulted in multiple, large metastatic nodules in each of the 12 mice, whereas i.v. injection of anti-sense-transfected F-11 cells formed a single, small metastatic nodule in only 2 of the 8 nude mice. In addition, even if metastasis occurred, the anti-sense-induced metastatic nodules were much smaller than the metastatic nodules formed by control F-11 cells. These results demonstrate that suppression of GD3-synthase expression, which results primarily in a marked decrease in the concentration of ganglioside GD3, greatly reduces cell spreading, invasion and both the incidence and growth rate of experimental metastasis of F-11 cells.
Copyright 2000 Wiley-Liss, Inc.