Small Molecules in Large Proteins

A theme is emerging in antiangiogenesis research: Small molecules stored within large proteins in the body can stop cancer cells from creating new blood vessels. Many enzymes that a tumor uses to invade surrounding tissue generate these angiogenesis inhibitors, but a tumor can locally override the effect of the inhibitors by generating angiogenesis stimulators. If researchers could shift this balance by increasing the concentration of endogenous angiogenesis inhibitors, they could potentially arrest tumor development. Without blood vessels, cells are unable to grow into tumors. Researchers have recently found a treasure chest of these molecules, which may bolster the clinical pipeline for cancer drugs.

Judah Folkman, director of the surgical research laboratory at Children's Hospital in Boston and professor of cell biology and pediatric surgery at Harvard Medical School, compares this facet of angiogenesis to the body's blood clotting mechanism. In both cases, proteins are made and stored in an...