Aims: Insulin-like growth factor-1 (IGF-1) is a polypeptide protein hormone, similar in molecular structure to insulin, which plays an important role in cell migration, cell cycle progression, cell survival and proliferation. In this study, we investigated the possible mechanisms of IGF-1 mediated cell cycle redistribution and apoptosis of vascular endothelial cells. Method: Human umbilical vein endothelial cells (HUVECs) were pretreated with 0.1, 0.5, or 2.5 mu g/mL of IGF-1 for 30 min before the addition of Ang II. Cell cycle redistribution and apoptosis were examined by flow cytometry. Expression of Ang II type 1 (AT(1)) mRNA and cyclin E protein were determined by RT-PCR and Western blot, respectively. Results: Ang II (1 mu mol/L) induced HUVECs arrested at G(0)/G(1), enhanced the expression level of AT(1) mRNA in a time-dependent manner, reduced the enzymatic activity of nitric oxide synthase (NOS) and nitric oxide (NO) content as well as the expression level of cyclin E protein. However, IGF-1 enhanced NOS activity, NO content, and the expression level of cyclin E protein, and reduced the expression level of AT(1) mRNA. L-NAME significantly counteracted these effects of IGF-1. Conclusions: Our data suggests that IGF-1 can reverse vascular endothelial cells arrested at G(0)/G(1) and apoptosis induced by Ang II, which might be mediated via a NOS-NO signaling pathway and is likely associated with the expression levels of AT(1) mRNA and cyclin E proteins. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.