Colorectal cancer (CRC) remains one of the most commonly diagnosed
malignancies worldwide.
Circular RNAs (
circRNAs) are being found to play crucial roles in human
cancer, including CRC. The purpose of this study was to explore the function and mechanism of circ_0007031 on CRC progression and
5-fluorouracil (5-FU) resistance. The levels of circ_0007031,
ATP-binding cassette subfamily C member 5 (ABCC5) and miR-133b were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot. Cell survival and proliferation were detected by the 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Cell colony formation was evaluated using a standard colony formation assay. Transwell assays were performed to determine cell migration and invasion. Targeted correlations among circ_0007031, miR-133b and ABCC5 were verified by dual-
luciferase reporter,
RNA immunoprecipitation (RIP) and
RNA pulldown assays. Animal experiments were performed to observe the role of circ_0007031 in vivo. Our data indicated that circ_0007031 up-regulation was associated with CRC resistance to
5-FU. Circ_0007031 knockdown repressed CRC cell proliferation, migration and invasion and enhanced
5-FU sensitivity. Circ_0007031 directly interacted with miR-133b. Moreover, circ_0007031 knockdown regulated CRC cell progression and
5-FU sensitivity by miR-133b. ABCC5 was a direct target of miR-133b, and circ_0007031 mediated ABCC5 expression via acting as a miR-133b sponge. Furthermore, miR-133b overexpression regulated CRC cell progression and sensitivity to
5-FU by down-regulating ABCC5. Additionally, circ_0007031 knockdown suppressed
tumor growth in vivo. Our current work had led to the identification of circ_0007031 knockdown that repressed CRC cell malignant progression and enhanced
5-FU sensitivity via regulating ABCC5 expression by sponging miR-133b.