Question

fill in the blank:

Vascular endothelial cells secrete VEGF as a __________ signal which binds to the VEGFR on the surface of tumor cells, stimulating mitosis of these cells and producing blood vessels to supply the tumor with oxygen and nutrients.

a) autocrine

b) paracrine

c) endocrine

Answer 1

Before I answer the question, let understand these 3 terms in just a couple of sentences.

a) Autocrine :- When a cell secrete a hormone and the secreted hormone binds to the receptors present on the same cell in which it was synthesized. This will result in the changes in the same cell.

b) Paracrine :- When a cell secrete a hormone and the secreted hormone binds to the receptors of cells which are present in the immediate vicinity of the cell from where it was secreted.

c) Endocrine :- Endocrine is actually a secretion system which consists of glands. These glands supply the hormone to the blood and blood take these hormone to distant part of our body. In this way, one organ can control other organ of the body.

VEGF stands for Vascular endothelial growth factor is responsible for the formation of blood vessels. It signals a cell to perform angiogenesis (blood vessel formation). It plays a central role in cancer because cancer cells as they are rapidly dividing, they need a higher supply of oxygen and other nutrients, if they need grow beyond a certain size. This is achieved by formation of new blood vessels. Tumor cells over-express VEGF which stimulate the tumor cell to make blood vessel.

Thus it is a form of Autocrine signalling.

The right option is option (a) Autocrine