[Proteases in cancer progression]

Invasion and metastasis are the most important events in cancer progression. In these two phases, several molecules are implicated and have been long associated with several forms of cancer. Proteases play a critical role not only in tumor cell invasion, but also in the earliest stages of carcinogenesis and its associated changes: angiogenesis and metastasis. Aside from their ability to degrade the extracellular matrix, facilitate invasion and metastasis, proteases target a great variety of substrates that favor or inhibit cancer progression: b-FGF, HGF, VEGF, cell death receptors, cistatin-C, galectin, procollagen, and other proteases. Proteases are also signaling molecules that modulate other molecules by underlying pathways in addition to their degradative role. Proteases form interconnected cascades, circuits and networks that bring about the tumor's potential for malignancy. Although, proteases are regulated by diverse molecules, it is known that tumoral and stromal cells secrete several biological molecules, including cytokines and chemokines that directly or indirectly regulate the protease-expression within the tumor's microenvironment. The present review briefly summarizes some of the major aspects associated with the role of proteases in cancer progression.