title: Ganglioside GD1a inhibits HGF-induced motility and scattering of cancer cells through suppression of tyrosine phosphorylation of c-Met.
abstract: We previously reported that ganglioside GD1a, which is highly expressed in poorly metastatic FBJ-S1 cells, inhibits the serum-induced motility of FBJ-LL cells and that the metastatic potential of FBJ-LL cells is completely suppressed by enforced GD1a expression (Hyuga et al., Int J Cancer 1999;83:685-91). We recently discovered that hepatocyte growth factor (HGF) induces FBJ-LL cell motility. In the present study, the HGF-induced motility of FBJ-S1 cells was found to be one-thirtieth that of FBJ-LL cells. This motility of GD1a-expressing transfectants, which were produced by transfection of FBJ-LL cells with GM2/GD2 synthase cDNA, decreased with increases in their GD1a expression and HGF induced almost no motility in GD1a-pretreated FBJ-LL cells, indicating that GD1a inhibits the HGF-induced motility of FBJ-LL cells. The expression of the HGF receptor c-Met on FBJ-S1 cells, FBJ-LL cells, transfectants and a mock-transfectant was almost the same. The level of tyrosine phosphorylation of c-Met after HGF stimulation in FBJ-S1 cells, GD1a-pretreated FBJ-LL cells and a GD1a-expressing transfectant was significantly lower than in FBJ-LL cells and a mock-transfectant. These findings suggested that GD1a inhibits the HGF-induced motility of FBJ-LL cells through suppression of tyrosine phosphorylation of c-Met. HepG2 cells, a human hepatoma cell line, were used to investigate whether GD1a interferes with other cancer cells expressing c-Met. HepG2 cells did not express GD1a. HGF induced cell scattering of HepG2 cells and the scattering was inhibited by pretreating the cells with GD1a. The c-Met in the cells was autophosphorylated by stimulation with HGF, but after treating the cells with GD1a, the HGF-induced autophosphorylation of c-Met was suppressed. These results suggest that GD1a acts as a negative regulator of c-Met in cancer cells.
authors.affiliation: Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, Setagayaku, Tokyo, Japan. hyuga@nihs.go.jp
authors.forename: S
authors.initials: S
authors.lastname: Hyuga
authors.forename: N
authors.initials: N
authors.lastname: Kawasaki
authors.forename: M
authors.initials: M
authors.lastname: Hyuga
authors.forename: M
authors.initials: M
authors.lastname: Ohta
authors.forename: R
authors.initials: R
authors.lastname: Shibayama
authors.forename: T
authors.initials: T
authors.lastname: Kawanishi
authors.forename: S
authors.initials: S
authors.lastname: Yamagata
authors.forename: T
authors.initials: T
authors.lastname: Yamagata
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002465:Cell Movement; D018076:DNA, Complementary / Q000378:metabolism; D005434:Flow Cytometry; D005677:G(M1) Ganglioside / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005732:Gangliosides / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D051379:Mice; D009369:Neoplasms / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D019859:Proto-Oncogene Proteins c-met / Q000276:immunology; D015398:Signal Transduction; D022502:Stress Fibers / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000199:Actins; D018076:DNA, Complementary; D005732:Gangliosides; C064020:ganglioside GD1alpha; D005677:G(M1) Ganglioside; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met