[Signaling 101] Vascular Endothelial Growth Factor (VEGF) Signaling (PART I)

When talking about cancer, we often come across acronyms like VEGF, VEGFR, EGFR, IGF, IGFR, etc... which after a few, sound and look the same. Our goal here is to pick one of them each month and go into the details about each of these cellular molecules that play important role in our body and can serve and potential targets for cancer therapy.

First, we are going to tackle Vascular Endothelial Growth Factors, also known as VEGF.

WHAT IS VEGF? 

VEGF (vascular endothelial growth factor), which was previous called VPF (vascular permeability factor) is a molecule that plays a major role in tumor growth by inducing angiogenesis. Angiogenesis is the process of new blood vessel formation from pre-existing vessels. This process plays a major role in:

1) stimulating proliferation and migration of endothelial cells for new vessels
2) contributing to the progress of a benign tumor (okay) to a malignant one (BAD!).

VEGF, thus, plays a role in turning a  normally co-existing tumor to a malignant cancer. As a result, there has been many research and drug discovery targetting VEGF to treat cancer.

HOW IS VEGF PRODUCTION INITIATED IN THE FIRST PLACE?

VEGF production is induced by cellular environmental factors such as hypoxia (insufficient oxygen), sex hormones such as androgen and estrogen, chemokines (chemical signaling molecules), as well as by genetic changes of oncogene (cancer inducing genes) or mutational inactivation of tumor suppressor gene. This molecule in a normally functioning body is produced to induce vasculogenesis for maintaining the overall homeostasis of oxygen, nutrients, and other essential factors that should be kept in balance throughout the body. However, cancer cells can manipulate this system that exists to benefit the host for their growth and mobilization in their host's body.

ARE THERE DIFFERENT KINDS OF VEGF? 

Yes, VEGF exists in six different forms: VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, and (ironically) PIGF (placental growth factor). They interact with three types of receptors: VEGFR (vascular endothelial factor receptor)-1, VEGFR-2, and VEGFR-3. Here's a little chart I made to makes things a little easier to see which factor binds to which receptor:

Receptors	Ligands
VEGFR-1	VEGF-A, VEGF-B, and PIGF
VEGFR-2	VEGF-A, VEGF-C, VEGF-D, and VEGF-E
VEGFR-3	VEGF-C, VEGF-D

I have made a mini-matching game to help you remember which factor binds to which receptor. :)

(will continue on part II...)