5-20 μM). We determined the cell survival rate, which was defined as the ratio of the number of living cells after 24, 48, and 72 h of incubation selleck with 1, 2.5, 5, 10 μM mevastatin, 1, 2.5, 5, and 10 μM fluvastatin or 2.5, 5, 10, and 20 μM simvastatin to the number of living cells in the control (0.1% DMSO-treated) samples. The survival rates on exposure to 1, 2.5, 5, and 10 μM of mevastatin were 81.44%, 58.41%, 31.81%, and 16.93%, respectively, at 72 h (Figure 2A). Thus, the number of U251MG cells significantly decreased at 72 h after the administration of 5 and 10 μM mevastatin. The survival rates on exposure to 1, 2.5, 5, and 10 μM of fluvastatin were 63.37%, 53.71%, 25.45%, and 24.08%, respectively,

at 72 h (Figure 2B). Thus, the

number of U251MG cells significantly decreased at 72 h after the administration of 5 and 10 μM fluvastatin. The survival rates on exposure to 2.5, 5, 10, and 20 μM of simvastatin were 65.57%, 57.59%, 25.11%, and 21.87%, respectively, at 72 h (Figure 2C). Thus, the number of U251MG cells significantly decreased at 72 h after the administration of 10 and 20 μM simvastatin. Figure 2 Effects of statins on U251MG cell viability. U251MG cells were treated check details with various concentrations of statins and trypan blue exclusion test was performed after 24, 48, or 72 h. The results are representative of 5 independent experiments. *p < 0.01 vs. controls (ANOVA with Dunnett's test). Statins-mediated activation of caspase-3 The cytotoxic effects of statins on C6 glioma cells were attributed to the induction of apoptosis, as demonstrated by the results of the following biochemical assays. We investigated the involvement of statins in caspase-3 activation. Caspase-3 activity was measured at 24 h after the addition of 5 μM mevastatin, 5 μM fluvastatin,

10 μM simvastatin to the tuclazepam C6 glioma cells. We observed that the addition of statins resulted in a Bucladesine purchase marked increase in caspase-3 activity in comparison with that in the control (0.1% DMSO-treated cells) (Figure 3A). Figure 3 Inhibition of statin-induced apoptosis in C6 glioma cells by intermediates of the mevalonate pathway. (A) Induction of caspase-3-like activity associated with statin-induced cell death. Caspase-3 activity is expressed as pM of proteolytic cleavage of the caspase-3 substrate Asp-Glu-Val-Asp-7-Amino-4-trifluoromethylcoumarin (DEVD-AFC) per h per mg of protein. The results are representative of 5 independent experiments. *p < 0.01 vs. controls (ANOVA with Dunnett’s test). (B-D) C6 glioma cells were pretreated with 1 mM mevalonic acid lactone (MVA), 10 μM farnesyl pyrophosphate (FPP), 10 μM geranylgeranyl pyrophosphate (GGPP), 30 μM squalene, 30 μM isopentenyladenine, 30 μM ubiquinone, or 30 μM dolichol for 4 h and then treated with (B) 5 μM mevastatin, (C) 5 μM fluvastatin, or (D) 10 μM simvastatin for 72 h.