Suppression of vascular smooth muscle cell responses induced by TNF-α in GM3 synthase gene transfected cells

The natural accumulation of ganglioside GM3 (N-glycolylneuraminic acid) on atherosclerotic lesions is a common theory. The present study is the first to examine the effects of the GM3 synthase gene on the responses of vascular smooth muscle cells (VSMC) to tumor necrosis factor-α (TNF-α). We found that overexpression of the GM3 synthase gene inhibited DNA synthesis and ERK1/2 activity induced by TNF-α in VSMC, whereas the basal levels of DNA synthesis and ERK1/2 activity remained unchanged. In addition, GM3 synthase gene transfectants significantly reduced the migration and invasion of VSMC following TNF-α treatment, compared with empty vector transfectants. Furthermore, TNF-α-induced matrix metalloproteinase-9 (MMP-9) expression and promoter activity were also decreased in GM3 synthase gene transfectants. GM3 synthase gene expression markedly suppressed the TNF-α-stimulated transcriptional activity of activator protein-1 (AP-1) and nuclear factor-κB (NF-κB), which are the controlling factors of MMP-9 expression. Consistent with these results, the addition of anti-GM3 antibody into the GM3 synthase gene transfectants blocked inhibition of DNA synthesis, ERK1/2 activity, migration and invasion. Finally, GM3 synthase gene transfectants treated with anti-GM3 antibody reversed the suppression of MMP-9 expression by reducing AP-1 and NF-κB binding activity. These results suggest regulatory roles for the GM3 synthase gene in VSMC proliferation and migration during the formation of atherosclerotic lesions.