METHODS: Y79 cells were divided into si-NC group(transfected with si-NC), si-circ_0000144 group(transfected with si-circ_0000144), miR-NC group(transfected with miR-NC), miR-502-5p group(transfected with miR-502-5p mimic), pcDNA group(transfected with pcDNA), pcDNA-circ_0000144 group(transfected with pcDNA-circ_0000144), si-circ_0000144+anti-miR-NC group(transfected with si-circ_0000144+anti-miR-NC), si-circ_0000144+anti-miR-502-5p group(transfected with si-circ_0000144+anti-miR-502-5p). Quantitative real-time polymerase chain reaction(qRT-PCR)was used to detect the expression of circ_0000144 and miR-502-5p in retinoblastoma tissues and cells, thiazole blue tetrazolium bromide(MTT)detected cell proliferation, and western blot was employed to determine the expression of nuclear associated antigen Ki67(Ki-67), B cell lymphoma/lewkmia-2(Bcl-2), Bcl-2 associated X protein(Bax), matrix metalloprotease(MMP)-2, MMP-9 protein. Flow cytometry detected cell apoptosis, and Transwell measured cell migration and invasion. Bioinformatics prediction and dual luciferase report experiment analyzed whether circ_0000144 targets miR-502-5p.

RESULTS: The expression of circ_0000144 in 31 cases of retinoblastoma tissue was higher than that of adjacent tissues, and the expression of miR-502-5p was lower than that of adjacent tissues(P<0.05). Compared with the si-NC group, the circ_0000144 expression, OD value, expression of Ki-67, Bcl-2, MMP-2, MMP-9 protein, number of migration and invasion cells of the Y79 cells in the si-circ_0000144 group decreased, and the expression of Bax protein and apoptosis rate increased(P<0.05). circ_0000144 targets and negatively regulates the expression of miR-502-5p. Compared with miR-NC group, miR-502-5p group increased cell apoptosis rate and expression of Bax protein of the Y79 cells, while decreased OD value, number of migration and invasion cells, and the expression of Ki-67, Bcl-2, MMP-2 and MMP-9 protein(P<0.05). Compared with the si-circ_0000144+anti-miR-NC group, cell apoptosis rate and Bax protein expression of the Y79 cells in the si-circ_0000144+anti-miR-502-5p group decreased, but the OD value, number of migration and invasion cells, the protein expression of Ki-67, Bcl-2, MMP-2 and MMP-9 increased.

CONCLUSION: circ_0000144 was highly expressed in retinoblastoma tissue, and inhibiting circ_0000144 can reduce the proliferation, migration and invasion of retinoblastoma Y79 cells, and promote apoptosis through negative regulation of miR-502-5p.