In vitro and in vivo antiproliferative effects of simvastatin, an HMG-CoA reductase inhibitor, on human glioma cells.

We analyzed the antiproliferative effect of simvastatin (SV), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, on human glioma cell lines. Inhibition of cell growth with SV was observed in all cell lines tested. Different culture conditions altered this inhibition of growth: the lower the concentration of fetal bovine serum (FBS) in the medium, the higher the inhibitory effect of SV on glioma cells. On morphological examination, we found that most of the cells exposed to SV became rounded and the proportion of floating cells was increased in a time-dependent manner. Then we examined whether exogenously added mevalonic acid reversed the growth inhibitory effect of SV. Exogenous mevalonic acid suppressed the inhibitory effect of SV on glioma cells in a dose-dependent manner. SV also enhanced the expression of low-density lipoprotein (LDL) receptor on glioma cells. We also found that peroxidized LDL (p-LDL) was cytotoxic to glioma cells and that SV had additive effects on pLDL-induced cytotoxicity. In a mouse model, growth of glioma cells inoculated into nude mice was inhibited by intratumoral injection of both SV and peroxidized LDL. These results indicate that mevalonic acid or a metabolite in the cholesterol synthesis pathway is necessary for the growth of glioma cells and that simvastatin and/or peroxidized LDL should be examined further as potential therapeutic agents for gliomas.