Objective To explore the effects of circRBM33 on the apoptosis, migration and invasion of colorectal cancer cells, and its molecular mechanism.

Methods The expression levels of circRBM33 and miR-33a-5p in cancer tissues and adjacent tissues of 43 patients with colorectal cancer were detected using the real-time fluorescent quantitative PCR (RT-qPCR). The colorectal adenocarcinoma LoVo line cells were randomly divided into the con group, si-circRBM33 group, si-NC group, miR-33a-5p group, miR-NC group and si-circRBM33 + miR-33a-5p inhibitor group. The flow cytometry was used to detects the apoptosis rate of LoVo cells, the scratch test was used to detect the scratch healing rate of LoVo cells, the Transwell test was used to detects the number of LoVo cell migration and invasion, and the dual luciferase reporter experiment was used to detect the targeting relationship between circRBM33 and miR-33a-5p.

Results The expression level of circRBM33 in colorectal cancer tissue was higher than that in adjacent tissues, while the expression level of miR-33a-5p was lower than that in adjacent tissues (P ＜ 0.05). Silencing the circRBM33 or overexpressing miR-33a-5p, the expression level of miR-33a-5p increased, the apoptosis rate of LoVo cells increased, the scratch healing rate decreased, and the number of migratory and invasive cells decreased (P ＜ 0.05). The circRBM33 regulated miR-33a-5p. Inhibiting the miR-33a-5p could weaken the effects of silencing circRBM33 on the apoptosis, migration and invasion of LoVo cells.

Conclusions Silencing the circRBM33 can inhibit the migration and invasion of colorectal cancer cells, and promote the cell apoptosis by targeting up-regulation of miR-33a-5p.