To investigate the regulatory role and potential mechanism of long non-coding RNAs (lncRNA) in human retinoblastoma (RB).

The lncRNA profile in RB tissues were analyzed by microarray and quantitative reverse transcription PCR (qRT-PCR). One of the identified lncRNAs (LncRNA CCAT1) was selected for further experiments. SO-RB50 and Y79 cells were transfected with negative control, siRNA targeting lncRNA CCAT1 (si-CCAT1) and si-CCAT1+miR218-5p inhibitor, respectively. lncRNA CCAT1 expression was measured by qRT-PCR. Cell proliferation, migration and invasion were detected by CCK8, wound scratching, and transwell assay, respectively. Apoptosis and cell cycle distribution were assessed by flow cytometry. Apoptosis- (cle-caspase-3, cle-caspase-9, Bax and Bcl-2) and cell cycle-related protein expression (cyclin B1, CDC2 and p-CDC2 (Thr161)) were analyzed by Western blot.

lncRNA CCAT1 expression in SO-RB50 and Y79 cells was significantly inhibited after si-CCAT1 transfection (P<0.01). Both RB cells exhibited significantly reduced proliferation, migration and invasion abilities, but markedly increased apoptosis at 48h after si-CCAT1 transfection (P<0.05 or 0.01). RB cells in si-CCAT1+miR218-5p inhibitor group had significantly higher proliferation, migration and invasion, but notably lower apoptosis compared with si-CCAT1 group at 24 and 48h after transfection (all P<0.05 or 0.01). si-CCAT1 significantly increased the expression of cle-caspase-3, cle-caspase-9, Bax, but decreased Bcl-2 expression (P<0.01). The proportion of G2/M SO-RB50 and Y79 cells in siCCAT1 group was significantly increased compared with negative control group (P<0.01). LncRNA CCAT1 interference significantly reduced the expression of cyclin B1, CDC2 and p-CDC2 (Thr161) (P<0.01).

LncRNA CCAT1 promotes the proliferation migration and invasion, and reduces cell apoptosis of SO-RB50 and Y79 cells, probably through negative modulation of miR-218-5p. Our study suggested lncRNA CCAT1 as a potential biomarker and therapeutic target for RB.