EZH2 silencing with RNAi enhances irradiation-induced inhibition of human lung cancer growth in vitro and in vivo

Non-small cell lung cancer (NSCLC) has a high mortality rate and poor prognosis. The aim of the present study was to silence EZH2 and explore the antitumor effect of small interfering RNA (siRNA)-EZH2 in combination with radiotherapy, which is a main treatment for NSCLC. The results showed that irradiation in the presence of siRNA-EZH2 arrested A549 cells in the G(0) and G(1) phases, delayed cell cycle progression and effectively inhibited cell proliferation, compared with cells that received radiotherapy alone. The combined therapy enhanced the percentage of apoptotic A549 cells in vitro and reduced the tumor size, in addition to increasing the survival rate in tumor xenograft experiments. This study demonstrates the antitumor activity of ionizing radiation therapy in combination with siRNA-EZH2 in NSCLC, both in vitro and in vivo, as well as providing a scientific rationale for targeting EZH2 to enhance the sensitivity of cancer to radiotherapy in NSCLC patients.