Simvastatin Reduces Cancerogenic Potential of Renal Cancer Cells via Geranylgeranyl Pyrophosphate and Mevalonate Pathway.

Simvastatin is a cholesterol-lowering drug, inhibiting 3-hydroxy-3-methylglutaryl-coenzyme CoA (HMG-CoA) reductase. Previous studies have indicated the anticancerous effects of simvastatin. Here, we evaluated the anticancerous potential of simvastatin in renal cell carcinoma (RCC) cell lines. RCC occurs with an incidence of 2-3% of all cancer entities with high chemoresistance rate. Therefore, the understanding of underlying mechanisms for RCC activity and the development of alternative therapies are essential. Human RCC cell lines Caki-1 and KTC-26 were treated with simvastatin (16 or 33 µM) for 48 or 72 h. The effects of the downstream substrates mevalonate (MA), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP) were evaluated using add-back experiments. Cell growth was assessed using MTT assay. Apoptosis and cell cycle were analyzed by flow cytometry. Apoptosis-involved proteins were evaluated by Western blot. Simvastatin caused dose- and time-dependent inhibition of RCC cell growth by cell cycle arrest and apoptosis induction. Substitution of MA or GGPP abolished these effects to a large extent. These findings suggest that the antiproliferative effects of simvastatin are not only mediated through cholesterol deprivation but also by prenylation-associated mechanisms, thereby providing new insights into tumor-suppressive ability of simvastatin and into novel additive treatment options in the management of RCC.