Our bodies are in a constant state of change. Our cells divide and replenish. Tissues regenerate.
“Even in your brain, cells are regenerating,” says Professor Briony Forbes. “We’re constantly growing new cells. Skin needs to be replenished and regrow. If you cut it, you need growth to heal the wound.”
And in all these processes, the key ingredients are peptides – small proteins – known as “growth factors”.
As Head of Medical Biochemistry in the College of Medicine and Public Health, Professor Forbes is particularly focused on one in particular – the insulin-like growth factor (IGF).
While growth factors are vital to the growth of a foetus before birth and then the normal functions of the body after, too much can lead to disease. Too little can also cause growth-related diseases. A mutation in the growth factor gene can result in short stature or intellectual disability. IGF can also play a role in atherosclerosis and the laying down of arterial plaques.
“It's a balance. In the context of IGF, too much can cause abnormal overgrowth of bones known as acromegaly, or a greater risk of cancer,” she says.
“High circulating levels of IGF in pre-menopausal women lead to a higher risk of breast cancer, for instance.”
However, growth factors such as IGF are not the catalyst for cancerous cells; once they are present, high growth factor levels will make those cells grow faster, dividing and surviving even in the face of chemotherapy.
Whereas insulin is produced solely in the pancreas, most cells can produce IGF. The question is, why do some people suddenly make too much? Genetics is one reason, and taller people tend to have higher levels of IGF than smaller, shorter people.
Cancer, however, can actually switch on and even increase growth factor production for its own benefit.