Knockdown of circ_0000512 Inhibits Cell Proliferation and Promotes Apoptosis in Colorectal Cancer by Regulating miR-296-5p/RUNX1 Axis

BACKGROUND: Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. Increasing evidence showed that circular RNAs (circRNAs) played critical roles in the progression of CRC. However, the effects and underlying mechanisms of circ_0000512 in CRC progression remain unclear. METHODS: The expression levels of circ_0000512, microRNA-296-5p (miR-296-5p) and runt-related transcription factor 1 (RUNX1) were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability, colony formation, cell cycle distribution and cell apoptosis were detected by Cell Counting Kit-8 (CCK-8) assay, colony formation assay and flow cytometry analysis, respectively. Western blot assay was utilized to measure the protein expression of Cyclin D1, Cleaved Caspase-3 and RUNX1. The interaction between miR-296-5p and circ_0000512 or RUNX1 was predicted by starBase and verified by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay. The mice xenograft model was established to explore the function of circ_0000512 in vivo. RESULTS: The expression of circ_0000512 was increased in CRC tissues and cells. Knockdown of circ_0000512 suppressed cell viability and colony formation and arrested the cells at the G0/G1 phase while it accelerated apoptosis in CRC cells. Mechanistically, circ_0000512 could increase RUNX1 expression by acting as a molecular sponge of miR-296-5p in CRC cells. Furthermore, miR-296-5p downregulation or RUNX1 overexpression reversed the anti-proliferation and pro-apoptosis effects caused by circ_0000512 knockdown in CRC cells. In addition, circ_0000512 interference inhibited tumor growth by upregulating miR-296-5p and downregulating RUNX1 in vivo. CONCLUSION: Knockdown of circ_0000512 inhibited cell proliferation and induced apoptosis in CRC cell by regulating miR-296-5p/RUNX1 axis, which might provide a potential therapeutic target for CRC treatment.