Proliferative and apoptotic rates of U87 glioma cells under different NSPc1 and lncRNAs expression conditions. (A) siRNA knockdown efficiency of MALAT1, SOX2OT and ANRIL in U87 glioma cells. The knockdown efficiency was determined using a concentration gradient of each siRNA and reverse transcription-quantitative polymerase chain reaction with GAPDH as the loading control. (B) MTT assay was used to determine the viability of U87 cells following transfection with si-NC, pSE-NSPc1, si-MALAT1, si-SOX2OT, si-ANRIL, pSE-NSPc1+si-MALAT1, pSE-NSPc1+ si-SOX2OT, pSE-NSPc1+ si-ANRIL. (C) Flow cytometry analysis was performed to evaluate the apoptotic rate of U87 cells following knockdown of MALAT1, SOX2OT and ANRIL, and following the knockdown of the three candidate lncRNAs combined with knockdown of NSPc1. *P<0.05, **P<0.01; #siRNA concentration used for subsequent experiments. si, small-interfering; lncRNAs, long non-coding RNAs, NSPc1, nervous system polycomb-1; pSE-NSPc1, NSPc1 knockdown plasmid; MALAT1, metastasis associated lung adenocarcinoma transcript 1; ANRIL, antisense non-coding RNA in the INK4 locus; SOX2OT, sex-determining region of the Y chromosome-box 2 overlapping transcript.