Effects of tetracyclines on angiogenesis in vitro.

Most tumors kill their hosts by the process of metastasis rather than by local growth of the primary mass. A significant factor contributing to the distant invasion of cancer cells is the ability of tumors to produce large numbers of new blood vessels in their midst, known as angiogenesis. This both provides access to nourishment for the primary cancer and enables the cells to escape from the tumor and enter the bloodstream. We have been examining agents that appear to inhibit metastasis and, in particular, angiogenesis. We now report on the ability of the synthetic tetracycline, doxycycline, and the chemically-modified tetracycline, COL-3, to inhibit angiogenesis in a quantitative in vitro assay of angiogenesis, using human umbilical vascular endothelial cells (HUVECs) attached to microcarrier beads.