July 7, 2005
To colonize a healthy tissue, cancer cells must degrade the extracellular matrix that encapsulates it. That means primarily being able to degrade a ubiquitous structural protein called collagen. For decades, researchers have focused on how tumor cells co-opt the body’s own protein-degrading machinery to cut holes in the collagen. What has not been well studied at all is whether cells within the developing tumor also possess their own internal machinery to carry out the job. In the June 20 issue of the Journal of Cell Biology, NIDCR scientists and colleagues report that a recently discovered molecule not only is present on the surface of certain cells in a tumor, it serves as a switch that activates an internal process to degrade collagen. In fact, the scientist indicate this internal, or intracellular, pathway appears to play a major role in collagen degradation during tumor invasion. This seminal finding raises an important clinical issue. A number of cancer drugs are under study to prevent collagen degradation through the co-opting of the body’s protein-degrading machinery. Is it possible that tumors simply can compensate for the effects of the drugs by activating the intracellular degradation pathway?