Involvement of the mevalonate pathway in the antiproliferative effect of zoledronate on ACHN renal cell carcinoma cells.

Renal cell carcinoma (RCC) has been shown to be resistant to chemotherapy and radiotherapy. In order to examine the potential of zoledronate (ZOL), a bisphosphonate, as an anticancer agent, we investigated the effects of ZOL on RCC cells and the involvement of the mevalonate pathway in antiproliferative effects, as well as the effects of ZOL administration on mice inoculated with RCC. ACHN cells were used and cell viability was measured via intra-cellular reductase activity. Chromatin condensation was detected by Hoechst 33342 staining. Proteins were detected by western blot analysis. Tumor volume was measured bidimensionally in mice inoculated with ACHN cells after vehicle or ZOL subcutaneous administration. ZOL exhibited antiproliferative effects with an IC50 value of 2.29±0.53 µM in ACHN cells and chromatin condensation was observed when treated with ZOL. Farnesol (FOH) and geranylgeraniol (GGOH), precursors of farnesyl pyrophosphate and geranylgeranyl pyrophosphate, exhibited potency to rescue cells treated with ZOL. Additionally, Ras and RhoA proteins located in the membrane fraction decreased when treated with ZOL and recovered by FOH or GGOH treatment, suggesting that ZOL inhibited the mevalonate pathway, thereby suppressing the translocation of prenylated Ras and RhoA proteins to membrane fractions. An in vivo study showed the inhibitory potential of ZOL on tumor growth in mice without changes in body weight. Our study showed that ZOL could be useful as an anticancer agent for the treatment of RCC, and the mevalonate pathway could be an efficient target for novel therapeutic agents against RCC.