Downregulation of Ezh2 expression by RNA interference induces cell cycle arrest in the G0/G1 phase and apoptosis in U87 human glioma cells

The Ezh2 gene is an important member of the polycomb-group (PcG) family.As a newly identified oncogene, the expression of Ezh2 has been shown to be significantlyincreased in prostate cancer, breast cancer, renal cell carcinoma and hepaticcancer; however, a role for Ezh2 in the occurrence of glioma has not yet beenreported. In this study, we found that the Ezh2 gene is highly expressed in U87human glioma cells. Using RNA interference, we demonstrated that the downregulationof Ezh2 expression in U87 human glioma cells resulted in apoptosis and a cellcycle arrest in the G0/G1 phase. In addition, we found that silencing of the Ezh2gene altered the mitochondrial membrane potential and promoted the release ofcytochrome c from the mitochondria. Furthermore, the reduced expression of Ezh2altered the Bax and Bcl-2 protein levels and led to the activation of caspase9 and 3. These results indicate that the apoptosis induced in U87 human gliomacells by the silencing of the Ezh2 gene is related to the mitochondrial pathway.