Objective  To investigate the effect of total flavonoids from Selaginella uncinata on malignant biological behavior of colorectal cancer cells and its possible mechanism.

  Methods  Colorectal cancer cells Caco-2 were cultured in vitro. After Caco-2 cells were treated with different concentrations (10, 20 and 40 μg/mL) of total flavonoids from Selaginella uncinata for 24 hours, or Caco-2 cells were transfected with circ_0006528 small interfering RNA, or Caco-2 cells that transfected with circ_0006528 overexpression vector were treated with 40 μg/mL total flavonoids from Selaginella uncinata for 24 hours, methyl thiazolyl tetrazolium (MTT) assay, clone formation assay, scratch assay and flow cytometry were used to detect cell proliferation viability, the number of colony formation, migration and apoptosis, respectively. The expressions of Bax and Bcl-2 proteins were detected by western blot, and the expressions of circ_0006528 and miR-330-3p were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The regulatory relationship between circ_0006528 and miR-330-3p was verified by dual luciferase reporter gene assay.

  Results  After Caco-2 cells were intervened with total flavonoids from Selaginella uncinata, cell viability, the number of clone formation, migration distance and the expression of Bcl-2 protein as well as circ_0006528 in Caco-2 cells were significantly decreased, but apoptosis rate and the expression of Bax protein and miR-330-3p were significantly increased (P < 0.05), and they were dose-dependent. After circ_0006528 interference, Caco-2 cell activity, the number of clone formation, migration distance and Bcl-2 protein expression were significantly decreased, while apoptosis rate and Bax protein expression were significantly increased (P < 0.05). The circ_0006528 negatively regulated miR-330-3p by targeting. Overexpression of circ_0006528 reversed the effects of total flavonoids from Selaginella uncinata on proliferation, migration and apoptosis of Caco-2 cells and expression of miR-330-3p.

  Conclusion  The total flavonoids from Selaginella uncinata may inhibit the proliferation and migration of colorectal cancer cells and promote cells apoptosis by regulating the circ_0006528/miR-330-3p axis.