Metalloproteinases and cancer invasion.

The invasion and metastasis of cancer cells is a complex multistep process involving attachment of tumor cells to the basement membrane, proteolysis of the local connective tissue stroma, and migration through the proteolyzed stroma. Recent evidence implicates metalloproteinases such as type IV collagenase and transin/stromelysin in the proteolytic aspects of this process. Type IV collagenase activity is modulated by tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2). Immunohistochemical and biochemical studies of several human tumors show correlations between invasive potential and type IV collagenase activity.