Integrin-mediated activation of latent transforming growth factor β

Members of the integrin family recognize a variety of spatially-restricted extracellular ligands. Classically, ligation of integrins activates cytoplasmic signals in the integrin-expressing cell and contributes to cell adhesion, migration, proliferation and survival. At least two members of this family, alpha v beta 6 and alpha v beta 8 perform an additional function, activation of latent complexes of transforming growth factor beta. In effect, this process allows integrins on one cell to activate signals on adjacent (in the case of alpha v beta 6) or nearby cells (in the case of alpha v beta 8). Integrin-mediated TGF beta activation has been shown to play important roles in modulating tissue fibrosis, acute lung injury and pulmonary emphysema. Given the important roles that TGF beta plays in modulating epithelial cell growth, epithelial-to-mesenchymal transformation and tumor invasion and metastasis, integrin-mediated TGF beta activation is likely to play important roles in tumor growth ad metastasis.