Cell Proliferation and Migration Induced by Angiotensin-II is Mediated by ACE

Abstract

We have demonstrated that the Angiotensin I Converting Enzyme (ACE) acts as a membrane receptor for Angiotensin II (AngII). Upon binding to ACE with high affinity, AngII activates a signaling cascade that generates inositol 1,4,5-triphosphate (InsP3), culminating in intracellular Ca2+ increase. The goal of this work was to investigate cellular function that AngII plays through ACE activation. For that, we used CHO-ACE, CHO-AT1 and melanoma cell line (Tm-5), as well as, confocal microscopy, immunofluorescence, western blotting, small interfering RNA (siRNA) and BrDU assay. We found that AngII binds to ACE and this complex is internalized through clathrin, to trigger preferential nucleoplasmic Ca2+ increase. Since nuclear Ca2+ is known to regulate cell growth, we then investigated whether the proliferative response induced by AngII is mediated by ACE activation. We verified that silencing either ACE or clathrin reduced cell proliferation stimulated by AngII by 33% or 71% respectively, compared to control (p<0.001). In melanoma cell line (Tm-5), that was known to expresses mainly ACE instead of the classical AngII receptor, the AT1, AngII increased cell migration by 75.7 ± 2% compared to control condition (p<0.05). This data correlated with reduced focal adhesion formation induced by AngII in the same cell line (154 ± 23.9 a.u. for control vs, 54.9 ± 9.8 a.u. for AngII, p<0.05), Together, these results indicate a new role for ACE in cell proliferation and migration induced by AngII. Moreover, these findings point ACE signaling as a novel therapeutic target for cancer treatment.