Due to its importance, angiogenesis is carefully regulated by both substances that stimulate and inhibit the process.
The term lymphangiogenesis refers to the formation of both new blood vessels and lymphatic vessels.
The first drug to inhibit angiogenesis was approved in 2004.
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As with many processes in the body, however, there is a delicate balance.
With cancer, this formation of new blood vessels (angiogenesis) is what allows tumors to grow.
Angiogenesis refers to the use ofpre-existingblood vessels.
Vasculogenesis, in contrast, refers to thede novo (original)formation of blood vessels in the embryo.
Cancers do this by secreting substances that stimulate angiogenesis, and hence, the growth of cancer.
When it Occurs
Ordinarily, angiogenesis can be thought of as being “switched off.”
It’s thought that a lack of oxygen (hypoxia) in a tumor stimulates angiogenesis.
One of these genes is VEGF.)
An example of one of these messengers is VEGF or vascular enodothelial growth factor.
With cancer, however, angiogenesis requires both activating factors and inhibition of inhibitory factors.
Factors that inhibit blood vessel growth also have to show less activity than they otherwise would.
Some of these include
Activating factors often work together in tumor growth.
For example, the endothelial cells that are activated by VEGF may secrete platelet derived growth factor.
PDGF, in turn, bind to receptors on pericytes (the supporting cells noted above).
This binding causes the pericytes to secrete more VEGF, hence enhancing the process.
Thep53 genecodes for a protein (tumor protein 53) that protects against the development of cancer.
Some tissues produce more inhibitory factors than others.
These medications can interfere with the process of angiogenesis at several different points.
Other medications work at different places in the process.
Since they specifically target pathways involved in the growth of cancer, they are referred to as targeted therapies.
Unlike many cancer medications, these drugs can sometimes work across different cancer types.
The reason this is done is easier to understand by looking at the mechanism by which angiogenesis inhibitors work.
Therefore, to get rid of a tumor, other treatments need to be combined with these medications.
11(9).
