Galectin-1 sensitizes carcinoma cells to anoikis via the α5β1 fibronectin receptor
Résumé
Anoikis resistance is a hallmark of transformed epithelial cells. Here, we show that treatment of anoikis-resistant carcinoma cell lines with the endogenous lectin galectin-1 (Gal-1) promoted apoptosis via interaction with the unligated fibronectin receptor α5β1-integrin. Gal-1 efficiency correlated with expression of α5β1-integrin, and transfection of the α5-subunit into deficient cell lines conferred Gal-1 binding and anoikis stimulation. Furthermore, Gal-1 and the α5-and β1-integrin subunits coprecipitated in Gal-1-stimulated cells undergoing anoikis. Other members of the galectin family failed to be active. The functional interaction between Gal-1 and α5β1-integrin was glycan-dependent with α2,6-sialylation representing a switch-off signal. Desialylation of cell surface glycans resulted in increased electrophoretic mobility of α5β1-integrin and facilitated Gal-1 binding and anoikis stimulation. On the level of signaling, Gal-1-stimulated anoikis was prevented by filipin, which impaired the internalization of α5β1-integrin via cholesterol-enriched microdomains, and by pretreatment with a caspase-8 inhibitor. We propose that Gal-1/α5β1-integrin interaction participates in the control of epithelial integrity and integrin sialylation may enable carcinoma cells to evade this Gal 1 dependent control mechanism.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...