Biochemical mechanisms of tumor invasion and metastases.

Tumor invasion and metastases is the major cause of treatment failure for cancer patients. There is a great need to develop new clinical methods to predict the clinical aggressiveness of a patient's tumor and to identify and eradicate clinically silent micrometastases. Such new methods may be derived from basic research into the biochemical mechanisms of invasion and metastases. We have isolated proteins involved in tumor cell attachment, invasion, and locomotion. The 'laminin receptor' is a tumor cell surface protein which specifically binds laminin, a glycoprotein of basement membranes. The laminin receptor may play a role in tumor cell attachment. 'Type IV collagenase' is a metalloproteinase which cleaves type IV basement membrane collagen but not interstitial collagens. The 'autocrine motility factor' is a secreted protein which binds to the cell surface and profoundly stimulates cell locomotion. All of these proteins appear to be augmented in actively metastatic tumor cells, at least in the models studied. They may provide strategies for diagnosis and therapy of metastases.