αvβ6 integrin upregulates matrix metalloproteinase 9 and promotes migration of normal oral keratinocytes

Abstract

The integrin αvβ6 is a fibronectin receptor that is undetectable on normal keratinocytes in situ, but is increased significantly in wound healing and in culture-established keratinocytes, suggesting that it may promote changes associated with cell motility. Using normal human oral keratinocytes we have shown that cultured cells express relatively high levels of αvβ6 and this integrin has a functional role in both cell adhesion and migration towards fibronectin. We provide experimental evidence that the increased expression of αvβ6 by normal human oral keratinocytes results in coordinate changes, which promote a more migratory phenotype. Thus increased expression of αvβ6 results in a fibronectin-dependent increase in pro-matrix metalloproteinase 9, matrix metalloproteinase 9 activity increases normal human oral keratinocyte migration, and this may be further dependent on plasmin activation. The results suggest a key role for αvβ6 in these processes and indicate a coordinated link between αvβ6 expression and upregulation of matrix metalloproteinase 9. It appears that αvβ6 may function in normal human oral keratinocyte migration through matrix-metalloproteinase-9-dependent and -independent mechanisms.