Ganglioside GD3 induces convergence and synergism of adhesion and hepatocyte growth factor/Met signals in melanomas.
Bottom Line: In this study, we analyzed the effects of GD3 expression on cell signals triggered by hepatocyte growth factor (HGF)/Met interaction and by adhesion to collagen type I (CL-I).When resistance to induced apoptosis by H2O2 was examined, only GD3+ cells treated with both HGF and adhesion to CL-I showed clearly low percentages of dead cells compared with GD3- cells or GD3+ cells treated with either one of the stimulants.Cell growth measured by 5-ethynyl-2' deoxyuridine uptake also showed synergistic effects in GD3+ cells.
Affiliation: Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan; Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan.Show MeSH
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Mentions: It is well known that HGF binding to Met triggers activation of Akt, so we analyzed phosphorylation of Met and Akt after stimulation with HGF in GD3+ cells. The phosphorylation of Met and Akt was detected by immunoblotting with phosphorylation site-specific antibodies for Met (p-Met Tyr1234/1235, Tyr1349) or Akt (p-Akt Ser473, Thr308) as well as anti-Met or anti-Akt antibodies. Phosphorylation of Met and Akt after 15 min of stimulation with HGF increased depending on HGF concentration (Fig.1A). We analyzed the time-course of Met phosphorylation during stimulation with HGF. The peak of phosphorylation was found at 15 min, as shown in Figure1(B). When phosphorylation of Met (p-Met Tyr1234/1235, Tyr1349) after HGF treatment was compared between GD3+ cells and GD3− cells, relative intensities of phosphorylated Met bands corrected by β-actin or total Met bands showed no clear differences between GD3+ cells and GD3− cells (Fig.1C). These results suggested that phosphorylation of Tyr1234/1235 and Tyr1349 in Met is not affected by GD3 expression in the human melanoma cell line, SK-MEL-28 N1.
Affiliation: Department of Biomedical Sciences, Chubu University College of Life and Health Sciences, Kasugai, Japan; Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya, Japan.