title: Simvastatin rescues homocysteine-induced apoptosis of osteocytic MLO-Y4 cells by decreasing the expressions of NADPH oxidase 1 and 2.
abstract: Clinical studies have shown that hyperhomocysteinemia is associated with bone fragility. Homocysteine (Hcy) induces apoptosis of osteoblastic cell lineage by increasing oxidative stress, which may contribute to Hcy-induced bone fragility. Statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, ameliorate oxidative stress by regulating oxidant and anti-oxidant enzymes. However, the effects of statins on Hcy-induced apoptosis of osteocytes are unknown. This study was thus aimed to investigate whether or not statins prevent Hcy-induced apoptosis of osteocytic MLO-Y4 cells and regulate NADPH oxidase (Nox) expression. TUNEL staining showed that 5 mM Hcy induced apoptosis of MLO-Y4 cells, and that co-incubation of 10(-9) or 10(-8) M simvastatin significantly suppressed the apoptotic effect. Moreover, we confirmed the beneficial effect of simvastatin against Hcy's apoptotic effect by using a DNA fragment ELISA assay. However, TUNEL staining showed no significant effects of pravastatin, a hydrophilic statin, on the Hcy-induced apoptosis. Real-time PCR showed that Hcy increased the mRNA expressions of Nox1 and Nox2, whereas simvastatin inhibited the stimulation of Nox1 and Nox2 expressions by Hcy. In contrast, neither Hcy nor simvastatin had any effect on Nox4 expression. These findings indicate that simvastatin prevents the detrimental effects of Hcy on the apoptosis of osteocytes by regulating the expressions of Nox1 and Nox2, suggesting that statins may be beneficial for preventing Hcy-induced osteocyte apoptosis and the resulting bone fragility.
authors: Department of Internal Medicine 1, Shimane University Faculty of Medicine, Izumo 693-8501, Japan.
authors: Ayumu
authors: A
authors: Takeno
authors: Ippei
authors: I
authors: Kanazawa
authors: Ken-Ichiro
authors: K
authors: Tanaka
authors: Masakazu
authors: M
authors: Notsu
authors: Maki
authors: M
authors: Yokomoto-Umakoshi
authors: Toshitsugu
authors: T
authors: Sugimoto
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016723:Bone Remodeling / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006710:Homocysteine / Q000633:toxicity*; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics*; D000074624:NADPH Oxidase 1; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics*; D010011:Osteocytes / Q000187:drug effects* / Q000502:physiology; D019821:Simvastatin / Q000494:pharmacology*
chemical_list: D008562:Membrane Glycoproteins; D006710:Homocysteine; D019821:Simvastatin; D009247:NADH, NADPH Oxidoreductases; C488842:Cybb protein, mouse; D000074624:NADPH Oxidase 1; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C000614711:NOX1 protein, mouse