Angiogenesis Flashcards
Why is angiogenesis needed in tumour growth?
For solid tumors to grow beyond 1-2 mm^3 they require increased access to oxygen and nutrients from the blood supply
This is accomplished by a process called tumour angiogenesis
How does tumour angiogenesis begin?
Tumour angiogenesis begins when growing tumours, in response to hypoxia or other stimuli, secrete angiogenic factors
How do angiogenic factors work?
Angiogenic factors act on normal vascular endothelial cells, stimulating their growth and division, ultimately resulting in new blood vessel formation
Define angiogenesis?
Proliferation of a network of blood vessels that penetrates into cancerous growths, supplying nutrients and oxygen and removing waste products.
Outline the steps of angiogenesis
Tumour angiogenesis actually starts with cancerous tumour cells releasing molecules that send signals to surrounding normal host tissue.
This signaling activates certain genes in the host tissue that, in turn, make proteins to encourage growth of new blood vessels.
The walls of blood vessels are formed by vascular endothelial cells. These cells rarely divide, doing so only about once every 3 years on average. However, when the situation requires it, angiogenesis can stimulate them to divide.
How is angiogenesis regulated?
Angiogenesis is regulated by both activator and inhibitor molecules. Normally, the inhibitors predominate, blocking growth.
Should a need for new blood vessels arise, angiogenesis activators increase in number and inhibitors decrease = growth and division of vascular endothelial cells = formation of new blood vessels
When does angiogenesis occur in healthy individual?
Proliferation of new blood vessels takes place in adults, although it is a relatively infrequent event.
In women, angiogenesis is active a few days each month as new blood vessels form in the lining of the uterus during the menstrual cycle.
Also, angiogenesis is necessary for the repair or regeneration of tissue during wound healing.
