Growth factors and cytokines: function and molecular regulation in pituitary adenomas.

The growth and functions of the anterior pituitary cells are regulated by hypothalamic factors, peripheral hormones and growth factors. However, the expression of numerous growth factors and cytokines, as well as their receptors, within the anterior pituitary suggests that these factors could be locally involved in the control of pituitary development, function and proliferation by auto-/paracrine mechanisms. In the normal pituitary, intrapituitary factors probably play a role in modifying endocrine signals in the pituitary cells. However, since alterations in growth factor production and receptor expression have been found in pituitary adenomas, these factors may also contribute to the pathophysiology and progression of pituitary tumours. The potential roles of the most important growth factors and cytokines in pituitary adenoma pathogenesis are reviewed.