[Endothelin-1, angiotensin II and cancer]

Endothelin-1 (ET-1) and angiotensin II (AngII), two potent vasoactive peptides involved in the regulation of cardiovascular homeostasis, also induce mitogenic and pro-angiogenic responses in vitro and in vivo. Both peptides are produced by cleavage of inactive precursors by metalloproteases (endothelin-converting enzyme and angiotensin-converting enzyme, respectively) and activate two subtypes of membrane receptors (ETA-R and ETB-R for ET-1, AT1R and AT2R for AngII) that all belong to the superfamily of G-protein coupled receptors. There is increasing evidence that ETA-R, ETB-R and AT1R are expressed in a variety of cancer cells and tissues, and may play a role on tumor growth, angiogenesis and invasion in vivo. This review summarizes the similarities and differences between the ET-1 and AngII systems with regard to their reported effects on various aspects of cancer. In addition to being expressed on vascular endothelium, ET-1 and AngII receptors participate in tumor angiogenesis through the production of the angiogenic factor VEGF. Furthermore, recent clinical studies indicate that a selective ETA-R antagonist has beneficial effects in prostate cancer, suggesting that a similar approach using ETB-R and AT1R blockers might be envisioned. Experimental data presented here suggest that a combined therapy targeting both ET-1 and AngII systems may prove valuable for future treatments of highly angiogenic tumors.