Novel anti-angiogenic agents for colorectal cancer. Are we moving on?

Abstract

Tumours depend greatly on blood supply to grow, spread and metastasise. It has been proposed, for a long time now, that angiogenesis and neo-vasculature development are present in tumours.(1;2) Angiogenesis is subject to regulation by a number of pro-angiogenic growth factors such as the vascular endothelial growth factors (VEGFs), angiopoetin, platelet derived growth factor (PDGF), placental growth factor (PlGF) and others, which are counteracted by proangiogenic growth factors such as angiostatin, transforming growth factor-beta (TGF-β) and others.(1;3) Among those growth factors, the most studied and associated with tumour growth and neo-angiogenesis is the family of the vascular endothelial growth factor (VEGF), which includes VEGF-A (the archetypal member, often called as VEGF), placental growth factor (PlGF), VEGF-B, VEGF-C, and VEGF-D (known also as c-Fos-induced growth factor, FIGF), and the viral VEGF-E. These growth factors exert their biological function through the VEGF transmembrane receptors VEGFR-1, -2 and -3. In particular, VEGF binds to VEGFR-1 and -2, VEGF-B and PlGF only to VEGFR-1, VEGF-C and VEGF-D to VEGFR-2 and -3.(4-8)