Snail regulates cell-matrix adhesion by regulation of the expression of integrins and basement membrane proteins

Snail, a transcriptional repressor of E-cadherin expression, plays a role in the process of epithelial-mesenchymal transition. However, the molecular basis of the role of snail in epithelial-mesenchymal transition has not been fully clarified. Here we show that the expression of snail in epithelial Madin-Darby canine kidney (MDCK) and A431 cells enhances both cell detachment and attachment. Snail did not confer resistance to anoikis induced by loss of contact but instead enhanced cell attachment to extracellular matrices such as fibronectin. This attachment was inhibited by Arg-Gly-Asp (RGD) peptides. Up-regulation of the promoter activity of integrin V was observed in snail-expressing MDCK (MDCK/snail) cells. Snail also enhanced MDCK cell migration toward osteopontin that is a ligand for integrin V 3. We confirmed the reduction of basement membrane proteins such as laminin (LN) alpha 3, beta 3, and gamma 2 (laminin-5/LN-5) and of receptors for LN-5 such as integrins alpha 3, alpha 6, or alpha 4 in MDCK/snail or in snail-expressing A431 (A431/snail) cells. Nevertheless, suppression of LN-gamma 3 chain by transient transfection of small interference RNAs resulted in no enhancement of cell detachment. We also found an induction of matrix metalloproteinase-3 in MDCK/snail and A431/snailcells. However, the inhibition of matrix metalloproteinase-3 showed no significant effect on the detachment of MDCK/snail cells. These results suggest that snail enhances cell detachment by multiple mechanism and leads to cell migration and reattachment at a second site, at least in part, by changing the expression of integrins in the cells.