Simvastatin protects human osteosarcoma cells from oxidative stress-induced apoptosis through mitochondrial-mediated signaling

Abstract

Abstract. Apoptosis of osteoblasts has been proposed as the common basis of osteoporosis, with oxidative stress as the major cause. This study was performed to investigate the protective effect of simvastatin (0.001-0.1 µM) on 100 µM hydrogen peroxide (H 2 O 2 )-mediated oxidative stress-induced apoptosis in human osteosarcoma (MG63) cells and the molecular mechanisms involved. Cell apoptosis was evaluated by observation of morphological changes and Annexin V-propidium iodide double staining followed by flow cytometric analysis. MTS assays were used to evaluate cell viability. To investigate the underlying molecular mechanisms, the expression of caspase-3, caspase-9 and Bcl-2 were analyzed by Western blotting. Following stimulation with H 2 O 2 for 24 h, a high proportion of MG63 cells underwent apoptosis, while a dosedependent inhibition of apoptosis was observed in the presence of simvastatin. A significant, dose-dependent reduction in the expression of caspase-3 and caspase-9 protein induced by H 2 O 2 in MG63 cells was observed in response to simvastatin and the Bcl-2 levels were increased. In conclusion, simvastatin protects MG63 cells from oxidative stress-induced apoptosis through downregulation of caspase-3 and caspase-9 activation and upregulation of Bcl-2 expression, suggesting a protective effect in osteoporosis. IntroductionOsteoporosis has been defined as a systemic skeletal disease characterized by gradual loss and microarchitectural deterioration of bone tissue, resulting in increased bone fragility and susceptibility to fracture (1). Osteoblasts are responsible for bone formation while osteoclasts are involved in bone resorption. Conditions such as postmenopausal osteoporosis are associated with significant changes in bone turnover; bone formation decreases and bone resorption increases or remains the same, resulting in net bone loss (2,3).Oxidative stress, resulting from excessive levels of reactive oxygen species (ROS), represents a major cause of cellular damage and death in a plethora of pathological conditions, including osteoporosis. This is associated with distinct increases in blood levels of oxidative stress markers (4-6). The main oxygen species responsible for oxidative stress are hydrogen peroxide (H 2 O 2 ), the free radical superoxide anion (O 2 -) and the hydroxyl radical (OH -). Osteoblasts produce antioxidants such as glutathione peroxidase that protect against ROS (7) and osteoclast-generated superoxide contributes to bone degradation (8). In ovariectomized rats, a model of postmenopausal osteoporosis, increased levels of lipid peroxidation and H 2 O 2 and decreased levels of enzymatic antioxidants were detected in tissue homogenates from the femora (9). Furthermore, antioxidant enzyme GPX1 gene polymorphisms are associated with low bone mineral density (BMD) and increased bone turnover markers (10).The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-COA) reductase inhibitor, simvastatin, is a widely used cholesterollowering drug that inhibits hepatic cholesterol biosynthesis. Recent...

Statin and Bisphosphonate Induce Starvation in Fast-Growing Cancer Cell Lines

“…Indeed, ibandronate had just a minor effect on NADPH, which was significantly reduced by simvastatin in PC-3 and MDA-MB-231 cells ( Figure 2 A,B). Thus, we could not confirm a previous report indicating that simvastatin might protect MG-63 osteosarcoma cells from oxidative stress [ 59 ], which could be a result of an induction of the anti-apoptotic BCL2 apoptosis regulator by the runt related transcription factor 2 (RUNX2) in response to the treatment with hydrogen peroxide in that study [ 60 ]. As both genes had about the same basal expressions in the cell lines that were investigated in this study and were not significantly regulated, it rather appears possible that reduction of NADPH is a general sign for reduced energy metabolism in treated cells, also because data on the influence of simvastatin and ibandronate on the production of reactive oxygen species (ROS) appear contradictory ( Supplementary Table S2 showing respective literature citations).…”

Erkek Rat Testislerinde Busulfan Kaynaklı Hasara Karşı Vitamin E, Melatonin, L-karnitin ve Atorvastatin’in Koruyucu Etkisi: Gen Ekspresyonunun Değerlendirilmesi

“…Several reports found that statins reduce levels of the anti-apoptotic protein Bcl2, and increase apoptosis and cell death [48][49][50] . Though, there is evidence that statins increase Bcl2 abundance which would desirable and in some instances reduce apoptosis and cell death [51,52] .…”

Simvastatin improves cerebrovascular injury caused by ischemia‑reperfusion through NF‑κB‑mediated apoptosis via MyD88/TRIF signaling

“…The present study revealed that simvastatin exhibited an important neuroprotective role against I/R injury-induced neuronal apoptosis via suppression neuronal apoptosis and attenuation of neurological dysfunctions. Zhao et al ( 42 ) demonstrated that simvastatin protects human osteosarcoma cells from oxidative stress-induced apoptosis by downregulating caspase-3 and caspase-9 activation, as well as upregulating of Bcl-2 expression. Suppression of MMP-9 expression was also reported to reduce neuronal apoptosis following I/R injury ( 43 ).…”