The Promigratory Activity of the Matricellular Protein Galectin-3 Depends on the Activation of PI-3 Kinase

Expression of galectin-3 is associated with sarcoma progression, invasion and metastasis. Here we determined the role of extracellular galectin-3 on migration of sarcoma cells on laminin-111. Cell lines from methylcholanthrene-induced sarcomas from both wild type and galectin-32/2 mice were established. Despite the presence of similar levels of laminin-binding integrins on the cell surface, galectin-32/2 sarcoma cells were more adherent and less migratory than galectin-3+/+ sarcomacells on laminin-111. When galectin-3 was transiently expressed in galectin-32/2 sarcoma cells, it inhibited cell adhesion and stimulated the migratory response to laminin in a carbohydrate-dependent manner. Extracellular galectin-3 led to the recruitment of SHP-2 phosphatase to focal adhesion plaques, followed by a decrease in the amount of phosphorylated FAKand phospho-paxillin in the lamellipodia of migrating cells. The promigratory activity of extracellular galectin-3 wasinhibitable by wortmannin, implicating the activation of a PI-3 kinase dependent pathway in the galectin-3 triggered disruption of adhesion plaques, leading to sarcoma cell migration on laminin-111.

The promigratory activity of the matricellular protein galectin-3 depends on the activation of PI-3 kinase.

Expression of galectin-3 is associated with sarcoma progression, invasion and metastasis. Here we determined the role of extracellular galectin-3 on migration of sarcoma cells on laminin-111. Cell lines from methylcholanthrene-induced sarcomas from both wild type and galectin-3(-/-) mice were established. Despite the presence of similar levels of laminin-binding integrins on the cell surface, galectin-3(-/-) sarcoma cells were more adherent and less migratory than galectin-3(+/+) sarcoma cells on laminin-111. When galectin-3 was transiently expressed in galectin-3(-/-) sarcoma cells, it inhibited cell adhesion and stimulated the migratory response to laminin in a carbohydrate-dependent manner. Extracellular galectin-3 led to the recruitment of SHP-2 phosphatase to focal adhesion plaques, followed by a decrease in the amount of phosphorylated FAK and phospho-paxillin in the lamellipodia of migrating cells. The promigratory activity of extracellular galectin-3 was inhibitable by wortmannin, implicating the activation of a PI-3 kinase dependent pathway in the galectin-3 triggered disruption of adhesion plaques, leading to sarcoma cell migration on laminin-111.