All cells in the body require a constant source of the nutrients and oxygen that are delivered through blood flow in the vascular system. Though tumor cells are abnormal and often harmful to the body, they also require an extensive vascular supply. Tumor angiogenesis refers to the mechanism by which tumors stimulate new blood vessel formation as they grow. The American Association for Cancer Research explains that tumor angiogenesis is vital for tumor expansion, local invasion and dissemination into the body. Several different tumor angiogenesis factors play key roles in the development of blood vessels to the cells.
VEGF
VEGF is a pro-angiogenic factor that binds to nearby endothelial cells and invades their blood vessels to promote vascular cell progression and migration into the tumor cells. The site Genentech Bio-Oncology explains that the tumor angiogenesis factor VEGF binds to receptors such as neuropilin-1, a transmembrane receptor that is located on vascular endothelial cells. This critical step in beginning angiogenesis allows the tumor to survive and grow in the body.
EGFL7
Genentech Bio-Oncology notes that another tumor angiogenesis factor called EGFL7 plays a key role in helping the newly forming vascular system proliferate to feed all the cells in the tumor. This protein is expressed or released by endothelial cells and also helps to promote the vascularization of normal, healthy body cells. It also helps to repair endothelial cells that are under stress or injured.
NRP1
The site Cancer Quest lists other tumor angiogenesis factors, including NRP1, which is a growth factor receptor that is important for promoting the maturation of newly developed blood vessels in the tumor. The site notes that a compound called anti-NRP1 factor is a natural and synthetic antibody that is designed to stop or control the growth of tumors by inhibiting angiogenesis and the maturation of blood vessels that support tumor growth.
