LAUSR

BACKGROUND Circular RNA (circRNA) plays an important role in the malignant progression of many tumors, including retinoblastoma (RB). However, the role and regulatory mechanism of circ-E2F3 in RB have not been fully elucidated. METHODS Quantitative real-time PCR was used to measure circ-E2F3, miR-204-5p and Rho-associated protein kinase 1 (ROCK1) expression. Cell proliferation, apoptosis and metastasis were monitored by MTT, colony formation, flow cytometry, transwell and wound healing assays. Dual-luciferase reporter assay was employed to verify the relationship between miR-204-5p and circ-E2F3 or ROCK1. ROCK1 protein expression was detected by western blot assay. Mice xenograft models were built to assess the role of circ-E2F3 on RB tumor growth. RESULTS Circ-E2F3 was upregulated in RB tissues and cells. Silencing of circ-E2F3 inhibited the proliferation, migration, invasion, and induced the apoptosis of RB cells in vitro, as well as reduced RB tumor growth in vivo. MiR-204-5p could be sponged by circ-E2F3, and its inhibitor reversed the suppressive effect of circ-E2F3 silencing on RB progression. In addition, ROCK1 was confirmed to interact with miR-204-5p. MiR-204-5p regulated RB progression by targeting ROCK1. Also, circ-E2F3 positively regulated ROCK1 expression by sponging miR-204-5p. CONCLUSION Circ-E2F3 functioned as a tumor promoter in RB through the miR-204-5p/ROCK1 axis.