HOTAIR participates in the silencing of PDCD4 in glioma cells. (A) PDCD4 expression level in U251 cells treated with siRNA targeting HOTAIR. Scr RNA was used as the negative control. (B) ChIP analysis of H3K27me3 histone modification at the PDCD4 promoter in U251 cells treated with siRNA. (C) ChIP analysis of EZH2 and SUZ12 recruitment to the PDCD4 promoter in U251 cells treated with siRNA. All experiments were repeated three times. *P<0.05 vs. negative control. HOTAIR, homeobox transcript antisense RNA; PDCD4, programmed cell death protein 4; siRNA, small interfering RNA; Scr, scramble; ChIP, chromatin immunoprecipitation; H3K27me3, histone 3 lysine 27 trimethylation; EZH2, enhancer of zeste homolog 2; SUZ12, suppressor of zeste 12; Con, control.