Statins inhibit hypoxia-induced endothelial proliferation by preventing calcium-induced ROS formation

Pathological hypoxia plays an important role in many diseases, such as atherosclerosis, cancer, and rheumatoid arthritis. The aim of the present study was to examine the effects of different statins on hypoxia-induced endothelial cell signalling. Human umbilical cord vein endothelial cells (HUVEC) were treated with NaCN (CN, 2.5 mmol/l) to simulate a transient hypoxia. The CN-induced increase of endothelial cell numbers was significantly (n = 10, p < 0.01) reduced by the Ca2+ chelator BAPTA (10 μmol/l), or the reactive oxygen species (ROS) scavenger N-acetylcysteine (ACC, 1 mmol/l), or the NAD(P)H-oxidase inhibitor diphenyleneiodonium (DPI, 5 μmol/l). In detail, cell numbers were (in percentage of control): 163.24 (CN), 90.06 (CN + ACC), 92.06 (CN + DPI). Intracellular-Ca2+ and -ROS, analysed by fluorescence imaging, were significantly increased by CN. Interestingly, the CN-induced increase of ROS was in part Ca2+-dependent, whereas the Ca2+ increase was not ROS-dependent. Simvastatin (5 μmol/l), fluvastatin (2.5 μmol/l), and cerivastatin (0.1 μmol/l) all reduced CN-induced proliferation, ROS generation and Ca2+ increase. Cell viability was not reduced by the statins and the antiproliferative effect was completely reversed by mevalonate (500 μmol/l). In conclusion our study demonstrates that statins block hypoxia-associated endothelial proliferation by preventing the increase of Ca2+ and ROS.