circMMP11/miR-1204/MMP11 axis affects BC progression. (A) The repression of circMMP11 and MMP11 by si-circMMP11 were both reinforced or reversed respectively when miR-1204 mimic or inhibitor and si-circMMP11 were cotransfected into MDA-MB-231. (B) CCK-8 assay and (C, D) Colony formation assay showed that the miR-1204 mimics can intensify the proliferation-inhibiting effects induced by silencing of circMMP11 in MDA-MB-231 cells while the miR-1204 inhibitor can reverse it. (E, F) miR-1204 mimics together with si-circMMP11 distinctly inhibited the migration ability of MDA-MB-231 cells. (G, H) miR-1204 mimics together with si-circMMP11 distinctly inhibited the invasion ability of MDA-MB-231 cells. Data were shown as the mean ± SD, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.