Syndecan-1 promotes HGF-induced activation of Met, PKB/Akt, and MAP kinase.

To assess the contribution of syndecan-1 to HGF-induced signaling, MM cell line XG-1 and PM cells were treated with heparitinase (HT) before stimulation with HGF. (A) Activation of Met. Met activation in XG-1 was assessed by immunoprecipitation and subsequent immunoblotting with antiphosphotyrosine antibodies. (B) Activation of PKB/Akt and MAP kinase. Activation of PKB/Akt and the MAP kinases Erk1 and Erk2 was determined in total cell lysates of XG-1 immunoblotted with antiphospho PKB/Akt (top) and antiphospho Erk1 and Erk2 (α p-MAPK) (middle), respectively. (C) Activation of PKB/Akt and MAP kinase. Activation of PKB/Akt and the MAP kinases Erk1 and Erk2 was determined in total cell lysates of PM cells, immunoblotted with antiphospho PKB/Akt (top) and antiphospho Erk1 and Erk2 (α p-MAPK) (middle), respectively. Staining with anti-Met was used to verify equal loading (A,B,C bottom panels). Activation of PKB/Akt and MAP kinase by insulin, which does not bind to HS, was not affected by HT treatment (B and C).