Bo‐Kyung Son1,2, Koichi Kozaki1,2, Katsuya Iijima1,2, Masato Eto1,2, Taro Kojima1,2, Hidetaka Ota1,2, Y. Senda1,2, Koji Maemura1,2, Toru Nakano1,2, Masahiro Akishita1,2, Yasuyoshi Ouchi1,2
1Discovery Research Laboratory (T.N.), Shionogi & Co Ltd, Osaka, Japan. Current address for K.K.: Department of Geriatric Medicine, Kyorin University School of Medicine, Tokyo, Japan.
2From the Departments of Geriatric Medicine (B.-K.S., K.K., K.I., M.E., T.K., H.O., Y.S., M.A., Y.O.) and Cardiovascular Medicine (K.M.), Graduate School of Medicine, The University of Tokyo; and Discovery Research Laboratory (T.N.), Shionogi & Co Ltd, Osaka, Japan. Current address for K.K.: Department of Geriatric Medicine, Kyorin University School of Medicine, Tokyo, Japan.
Tóm tắt
Vascular calcification is clinically important in the development of cardiovascular disease. It is reported that hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (statins) inhibited vascular calcification in several clinical trials. However, the mechanism is poorly understood. Recently, it has been suggested that apoptosis is one of the important processes regulating vascular smooth muscle cell (VSMC) calcification. In this study, we investigated the effect of statins on VSMC calcification by testing their effect on apoptosis, focusing in particular on regulation of the survival pathway mediated by growth arrest-specific gene 6 (Gas6), a member of the vitamin K–dependent protein family, and its receptor, Axl. In human aortic smooth muscle cells (HASMC), statins significantly inhibited inorganic phosphate (Pi)-induced calcification in a concentration-dependent manner (reduced by 49% at 0.1 μmol/L atorvastatin). The inhibitory effect of statins was mediated by preventing apoptosis, which was increased by Pi in a concentration-dependent manner, and not by inhibiting sodium-dependent phosphate cotransporter (NPC) activity, another mechanism regulating HASMC calcification. Furthermore, the antiapoptotic effect of statins was dependent on restoration of Gas6, whose expression was downregulated by Pi. Restoration of Gas6 mRNA by statins was mediated by mRNA stabilization, and not by an increase in transcriptional activity. Suppression of Gas6 using small interfering RNA and the Axl-extracellular domain abolished the preventive effect of statins on Pi-induced apoptosis and calcification. These data demonstrate that statins protected HASMC from Pi-induced calcification by inhibiting apoptosis via restoration of the Gas6-Axl pathway.
