Proteases in invasion: matrix metalloproteinases

The role of proteases in general, and the matrix metalloproteinases in part icular, in tumor invasion and metastasis is well established. However, the classic view that these enzymes simply provide a mechanism for the breakdow n of connective tissue barriers has been challenged. This overview summariz es recent evidence to support the changing view of the role of matrix metal loproteinases in cancer progression. First we briefly review the central ro le of cell invasion in cancer progression and also the matrix metalloprotei nase family members. We then focus on the emerging roles for these enzymes in cancer progression, including the role of matrix metalloproteinases in c ell proliferation and release of growth factors, cell migration and in modi fication of the extracellular matrix to reveal cryptic sites that alter cel l behaviour.