Targeting a Tumor Cell's Exit From the Bloodstream

The protein vascular endothelial growth factor (VEGF) has the ability to disrupt the barrier formed by endothelial cells, which line the body's blood vessels. This is significant because metastatic tumor cells can use VEGF to exit the bloodstream -- a dramatic demonstration of which can be seen in this image. A tumor cell is extending a fingerlike projection between two endothelial cells. Over the next several hours, the tumor cell will extricate itself from the bloodstream, and over the next several days that single cell will divide over and over to establish a new tumor. Recent studies in the David Cheresh laboratory demonstrated how a pharmacological inhibitor can prevent this endothelial barrier from opening, thereby blocking the exit of metastatic cells from the bloodstream.